This technical guide discusses bearing currents in modern AC drive systems. High frequency bearing currents are generated through three main mechanisms: circulating currents induced by asymmetric capacitive currents in large motors; shaft grounding currents from voltage increases along impedance paths; and capacitive discharge currents from internal voltage divisions in small motors. Proper grounding, motor cabling, and bonding connections are necessary to prevent damage from these high frequency currents flowing through motor bearings. Specialized measurement may be needed to analyze bearing currents.
This document provides an overview of harmonics with AC drives, including:
- Chapters discuss harmonic distortion sources and effects, calculation methods using DriveSize software, and standards for harmonic limits.
- DriveSize is used to model a network supplying a frequency converter and motor load, calculating the harmonic currents and voltages.
- Standards discussed include EN61800-3, IEC1000-2-2, IEC1000-2-4, IEC1000-3-2, IEC1000-3-4, and IEEE519, which set limits on harmonic distortion.
- Methods for reducing harmonics are examined, including rectifier configuration, use of inductors, and passive or active filters
This technical guide provides information on dimensioning drive systems. It discusses selecting induction motors based on thermal loadability, speed range and torque requirements. It also covers selecting frequency converters based on load type, current and network conditions. The guide describes motor fundamentals including torque-speed curves, current components, and power calculations. It also reviews basic mechanical laws regarding rotational motion, gears, moments of inertia, and how they impact torque requirements during acceleration and deceleration. Dimensioning involves considering all system factors like the electric supply, driven machine, and environmental conditions.
This technical guide discusses electrical braking solutions for AC drives. It begins by evaluating braking power needs based on load characteristics such as constant versus quadratic torque. It then describes various electrical braking methods available in drives, including motor flux braking, braking choppers with resistors, and IGBT regeneration units. The guide concludes by comparing the life cycle costs of different braking solutions.
This document is a technical guide that provides an overview of variable speed drives (VSDs). It discusses why VSDs are necessary for industrial processes, examples of industrial segments that use VSD processes, and the variables that affect processing systems. The guide focuses on how electric motors are used to power machines and can be controlled by frequency converters to vary speed based on process needs. It also examines the benefits of electrical VSDs like AC drives for process control and cost savings compared to other control methods.
This technical guide book provides 10 chapters that explain different aspects of variable speed drive technology, with a focus on Direct Torque Control (DTC). Chapter 1 introduces DTC and outlines the guide. Chapter 2 discusses the evolution of variable speed drives from early DC motor drives to modern DTC. It compares features and performance of different technologies. Chapter 3 addresses common questions about DTC performance and operation.
This technical guide provides an overview of motion control drives and synchronous servo motor technology. It discusses the differences between motion control and standard speed control systems, and decentralized versus centralized control architectures. The guide also covers various drive and motor combinations, synchronous motor principles, feedback devices, motion control concepts, and application examples. Key topics explained in more detail include synchronous servo motor operation, performance measurement, and how synchronous motors differ from induction motors.
This technical guide provides information on dimensioning drive systems. It discusses selecting induction motors based on thermal loadability, speed range and torque requirements. It also covers selecting frequency converters based on load type, current and network conditions. The guide describes motor fundamentals including torque-speed curves, current components, and power calculations. It also reviews basic mechanical laws regarding rotational motion, gears, moments of inertia, and how they impact torque requirements during acceleration and deceleration. Dimensioning involves considering all system factors like the electric supply, driven machine, and environmental conditions.
This technical guide provides information to help ensure electromagnetic compatibility (EMC) compliance when installing and configuring power drive systems (PDS). It defines key EMC terms and concepts. It describes EMC solutions related to emissions, filtering, cabling, and installation practices. Practical examples of EMC-compliant installations are also provided. The guide is intended to assist original equipment manufacturers, system integrators, and panel builders in meeting EMC directive requirements when incorporating drives and auxiliary components into their own systems.
This document provides an overview of harmonics with AC drives, including:
- Chapters discuss harmonic distortion sources and effects, calculation methods using DriveSize software, and standards for harmonic limits.
- DriveSize is used to model a network supplying a frequency converter and motor load, calculating the harmonic currents and voltages.
- Standards discussed include EN61800-3, IEC1000-2-2, IEC1000-2-4, IEC1000-3-2, IEC1000-3-4, and IEEE519, which set limits on harmonic distortion.
- Methods for reducing harmonics are examined, including rectifier configuration, use of inductors, and passive or active filters
This technical guide provides information on dimensioning drive systems. It discusses selecting induction motors based on thermal loadability, speed range and torque requirements. It also covers selecting frequency converters based on load type, current and network conditions. The guide describes motor fundamentals including torque-speed curves, current components, and power calculations. It also reviews basic mechanical laws regarding rotational motion, gears, moments of inertia, and how they impact torque requirements during acceleration and deceleration. Dimensioning involves considering all system factors like the electric supply, driven machine, and environmental conditions.
This technical guide discusses electrical braking solutions for AC drives. It begins by evaluating braking power needs based on load characteristics such as constant versus quadratic torque. It then describes various electrical braking methods available in drives, including motor flux braking, braking choppers with resistors, and IGBT regeneration units. The guide concludes by comparing the life cycle costs of different braking solutions.
This document is a technical guide that provides an overview of variable speed drives (VSDs). It discusses why VSDs are necessary for industrial processes, examples of industrial segments that use VSD processes, and the variables that affect processing systems. The guide focuses on how electric motors are used to power machines and can be controlled by frequency converters to vary speed based on process needs. It also examines the benefits of electrical VSDs like AC drives for process control and cost savings compared to other control methods.
This technical guide book provides 10 chapters that explain different aspects of variable speed drive technology, with a focus on Direct Torque Control (DTC). Chapter 1 introduces DTC and outlines the guide. Chapter 2 discusses the evolution of variable speed drives from early DC motor drives to modern DTC. It compares features and performance of different technologies. Chapter 3 addresses common questions about DTC performance and operation.
This technical guide provides an overview of motion control drives and synchronous servo motor technology. It discusses the differences between motion control and standard speed control systems, and decentralized versus centralized control architectures. The guide also covers various drive and motor combinations, synchronous motor principles, feedback devices, motion control concepts, and application examples. Key topics explained in more detail include synchronous servo motor operation, performance measurement, and how synchronous motors differ from induction motors.
This technical guide provides information on dimensioning drive systems. It discusses selecting induction motors based on thermal loadability, speed range and torque requirements. It also covers selecting frequency converters based on load type, current and network conditions. The guide describes motor fundamentals including torque-speed curves, current components, and power calculations. It also reviews basic mechanical laws regarding rotational motion, gears, moments of inertia, and how they impact torque requirements during acceleration and deceleration. Dimensioning involves considering all system factors like the electric supply, driven machine, and environmental conditions.
This technical guide provides information to help ensure electromagnetic compatibility (EMC) compliance when installing and configuring power drive systems (PDS). It defines key EMC terms and concepts. It describes EMC solutions related to emissions, filtering, cabling, and installation practices. Practical examples of EMC-compliant installations are also provided. The guide is intended to assist original equipment manufacturers, system integrators, and panel builders in meeting EMC directive requirements when incorporating drives and auxiliary components into their own systems.
To Design and simulate 3-Ø Induction motor driveUmang Patel
This document is a project report submitted by four students to fulfill the requirements for a Bachelor of Engineering degree in Power Electronics. It outlines a project to design and simulate a three-phase induction motor drive using constant voltage-to-frequency control with a PIC microcontroller. The report includes sections on electric drives, induction motors, voltage source inverters, simulation in MATLAB and Proteus, PIC microcontrollers, hardware implementation, and PCB design. Tables and figures are included to illustrate the system components, simulation results, and PCB layouts.
The document presents a presentation on dynamic modeling of DC motor drives. It discusses different types of DC drives including single phase, three phase, and DC-DC converter drives. It also provides the generalized electrical diagram and dynamic model of a DC motor, describing the stator inductance and resistance, and how the electrical equation for a DC motor can be derived using Laplace transforms. The dynamic model expresses the stator current as a function of the stator gain and time constant.
A PROJECT REPORT SIM & SPEED CONTROL OF INDUCTIO DRIVEPawan Kumar
The document discusses speed control methods for three-phase induction motors. It analyzes the transients during starting of an induction motor with different machine parameters. It then examines various speed control methods including variable rotor resistance, variable stator voltage, and constant V/f control. Simulation results are presented to show the torque-speed characteristics for each method. Vector control is also introduced, which allows independent control of torque and flux.
Vector control is a more advanced and precise method of controlling AC induction motors compared to scalar control. It involves transforming the motor currents and voltages into a rotating reference frame to obtain decoupled control similar to a DC motor. This allows for independent control of flux and torque for faster dynamic response and better performance than scalar control. The basic implementation of vector control uses Clarke and Park transformations to convert between stationary and rotating reference frames in the controller. It provides DC motor-like precision in speed and torque control of induction motors.
Speed control of three phase im by vf open and close loop methodeSAT Journals
This document presents a simulation of speed control for a three-phase induction motor using open-loop and closed-loop V/F control methods. In the open-loop method, a PWM inverter drives the motor and the torque is observed to remain constant with varying rotor speed. In the closed-loop method, a PI controller provides feedback to vary the supply frequency to maintain a constant V/F ratio. Simulation results in MATLAB Simulink show that closed-loop control provides superior speed regulation compared to the open-loop method.
This document describes a study on modeling and simulating a permanent magnet brushless DC (PMBLDC) motor drive system in MATLAB/Simulink. The authors develop a model of a PMBLDC motor with a 120-degree inverter system and implement closed-loop speed control using a PI controller. Simulation results confirm the validity of the model and controller. The paper examines the effects of load and inertia changes on the motor's speed performance.
This document proposes a direct torque control strategy for doubly fed induction machine-based wind turbines that can operate under voltage dips without crowbar protection. The control strategy generates a rotor flux amplitude reference to control the torque of the wind turbine and reduce stator and rotor overcurrents during faults. It also provides fast dynamic response. While the control does not eliminate the need for crowbar protection entirely, it can prevent the crowbar from activating during low-depth voltage dips. The direct torque control approach maintains machine connection to the grid and reduces torque oscillations during faults.
Use of Modular Multilevel Cascade Inverter as a Method to Speed-Sensorless St...IRJET Journal
This document summarizes a research paper that presents a speed-sensorless start-up method for an induction motor driven by a modular multilevel cascade inverter (MMCI) based on double-star chopper cells (DSCC). The start-up method combines capacitor-voltage control with motor-speed control. Capacitor-voltage control regulates the dc voltage of each capacitor and mitigates voltage fluctuations. Motor-speed control forms a feedback loop of stator currents to enable stable start-up from zero speed to middle speed without a speed sensor. Experimental results from a 15kW downscaled system verify the method enhances start-up torque by 3x under voltage fluctuations compared to previous methods.
Speed Control System of Induction Motor by using Direct Torque Control Method...ijtsrd
Escalator is useful and act in the important part to carry passengers to the targeted floors of building. Every escalator must be driven by its own motor and this motor speed must be controled. To drive escalator with a constant speed, direct torque control technique is used to drive three phase squirrel cage induction motor. In this paper, the development of speed control system for three phase squirrel cage induction motor using a direct torque control method is presented and simulation for proposed system is done with the help of MATLAB SIMULINK. Soe Sandar Aung | Thet Naing Htun "Speed Control System of Induction Motor by using Direct Torque Control Method used in Escalator" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27903.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/27903/speed-control-system-of-induction-motor-by-using-direct-torque-control-method-used-in-escalator/soe-sandar-aung
SPEED AND TORQUE CONTROL OF AN INDUCTION MOTOR WITH ANN BASED DTCijics
Due to advantages such as fast dynamic response, simple and robust control structure, direct torque
control (DTC) is commonly used method in high performance control method for induction motors. Despite
mentioned advantages, there are some chronically disadvantages with this method like high torque and
current ripples, variable switching behaviour and control problems at low speed rates. On the other hand,
artificial neural network (ANN) based control algorithms are getting increasingly popular in recent years
due to their positive contribution to the system performance. The purpose of this paper is investigating of
the effects of ANN integrated DTC method on induction motor performance by numerical simulations. For
this purpose, two different ANN models have been designed, trained and implemented for the same DTC
model. The first ANN model was designed to select optimum inverter and the second model was designed to
use in the determination of the flux vector position. Matlab/Simulink model of the proposed ANN based
DTC method was created in order to compare with the conventional DTC and the proposed DTC methods.
The simulation studies proved that the induction motor torque ripples have been reduced remarkably with
the proposed method and this approach can be a good alternative to the conventional DTC method for
induction motor control.
Review of Improved Direct Torque Control Methodologies for Induction Motor Dr...AM Publications
ecoupled control of induction motor drives is possible using Direct Torque Control (DTC) method which
is very simple control strategy compared to field oriented control. In this method direct torque control is achieved by
selecting suitable inverter switching voltage vector from a lookup table. But drawback of this method is that it
produces toque ripples. Also the switching frequency of inverter switches is not constant. Many methods have been
proposed to address these issues of DTC. This paper reviews various methodologies which are suggested to improve
performance of basic DTC induction motor drive.
Matlab simulation on chopper based speed control of dc motor: A ReviewIRJET Journal
This document summarizes a literature review on MATLAB simulation of chopper-based speed control of a DC motor. It describes how the speed of a DC motor below rated speed can be controlled by varying the armature voltage using a chopper converter in a closed-loop control system with a PI controller. The review covers DC chopper circuits, separately excited DC motors, modeling a DC motor drive system in MATLAB Simulink with a PI speed controller, and conclusions on simulating speed control of a DC motor using a chopper.
Efficient Motor Control Solutions: High Performance Servo Control (Design Con...Analog Devices, Inc.
This document provides a legal disclaimer and proprietary information notice for a presentation by Analog Devices (ADI) on efficient motor control solutions. It states that all information in the presentation is the exclusive property of ADI and cannot be reproduced or distributed without permission. It also disclaims all warranties, stating that while ADI intends the information to be accurate, no guarantees are made. It excludes liability for any damages arising from the use of the information. The presentation agenda is then outlined, covering motor applications and markets, motor operation and construction, control strategies, feedback sensors, power and isolation, and an ADI high performance servo control board.
This document presents a project report on simulating automatic speed control of a DC drive. It was submitted by four students to fulfill the requirements of a Bachelor of Technology degree. The report includes an introduction to the project, descriptions of the key components used including the DC motor, H-bridge, PWM, and sensors. It also provides the specifications of the components in the Simulink model, discusses the applications of the drive on different loads, and presents the simulation results. The conclusions discuss the advantages of the automatic speed control drive and potential future applications.
Brushles DC motor are one type of motors that are rapidly gaining the popularity and are penetrating in industrial applications, home appliances, automotive, consumer, medical etc. Because of there many advantages such as high efficiency ,silent operation, compact form ,reliability, low maintenance (due to the absence of brushess), long operating life, high speed ranges etc. for the proper commution of current in inverter the rotar position information is necessary, this information is usually provided by the mechanical position sensors mounted within the motor. however it is well known that these position sensors have many drawbacks therefore a sensor less control of BLDC motor is developed which eliminates the sensing equipment ,reduces the cost of motor and increases the reliability of the BLDC motor. In this paper the position information is obtained from the zero crossing detection of the back EMF which is also called as the terminal voltage sensing method which is the simplest ,method of detecting the back EMF zero crossing ,here the motor voltages are sensed and give to the lowpass filter whose output is give to the ZCD which determines the zero crossing of the back EMF waveform and ZCD generates the signal required for the controller to provide the pulses for the inverter operation the controller used is a high performance controller(DSPic30F4011) which as both the features of microcontroller and digital signal processor .The complete model is simulated in MATLAB/SIMULINK software. the proposed hardware and simulation program are found to be efficient and the results are promising
IRJET- Variable Frequency Drive Used in TreadmillIRJET Journal
This document summarizes the use of variable frequency drives in treadmills. It discusses how most treadmills previously used DC brush motors but these had issues like high failure rates and maintenance costs. The document then explores how using an AC motor with a variable frequency drive can improve on the limitations of DC motors. It provides details on how variable frequency drives work, including discussing the rectifier, DC bus, inverter and control circuit components. It also explains techniques like pulse width modulation and flux vector control that are used to control the speed of AC motors. The objectives of using a variable frequency drive in a treadmill are listed as energy savings, increased life of components, reduced noise and vibration, lower thermal and mechanical stresses, and
Direct torque control of induction motor using space vector modulationIAEME Publication
This document discusses direct torque control of an induction motor using space vector modulation. It begins with introducing direct torque control as an alternative to field oriented control for controlling torque and flux directly and independently. It then provides details on the principles of vector control and direct torque control in stator reference frames. The document describes the modeling of an induction motor and simulations performed in MATLAB to validate the direct torque control approach. The simulations demonstrate control of speed, torque, and flux under different gain settings of the PI controller.
V/F Control of Squirrel Cage Induction Motor Drives Without Flux or Torque Me...Waqas Tariq
Based on the popular constant volts per hertz principle, two improvement techniques are presented: keeping maximum torque constant or keeping magnetic flux constant. An open-loop inverter-three-phase squirrel-cage induction motor drive system that provides constant maximum torque or increased maximum torque and reduced slip speed at frequencies below the nominal frequency has been modeled, simulated and tested. Load performance analysis of the proposed system under different operation conditions was provided. These principles of operation are extended to the case of operation from variable frequency or variable voltage control method. Finally, the effects of the non-sinusoidal voltage and/or current wave shapes are covered. The results show that both suggested improvement techniques (constant torque or constant flux) improve the steady-state performance A.C. drive system with squirrel cage induction motors. The slip speed has been decreased and the starting torque and maximum torque have been increased, which means that the suggested control techniques can be used in drive systems with short time operating mode under light loads.
Matrix Converter based Direct Torque Control of Induction MotorNeehar NLN
This topic falls under the area of speed control of induction motor. The using of advanced power electronic converters provides better response. In this case, a AC/AC converter is used to control the induction motor.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Analysis and Simulation of Asynchronous Machine Connected with Load Accomplis...YogeshIJTSRD
This paper presents the simulation analysis of pulse width modulation based induction motor drive. The main objective of this paper is analysis of asynchronous machine with PWM fed inverter and harmonic analysis of active and reactive power as well as voltage and current. Space vector pulse width modulation technique is used in various industrial applications. Variation in voltage and frequency supply to ac drives is produced from a voltage source inverter and space vector PWM is used frequently now a day due to their easy understanding. This work is based on a SVPWM based induction motor based on space vector theory. The simulation is done on MATLAB software and the simulation results obtained and analyzed. Ms. Neetu Khunte | Mr. Abhijeet Lal | Mr. Abhishek Agrawal "Analysis and Simulation of Asynchronous Machine Connected with Load Accomplished with Chopper Control and PWM Based Inverter" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-4 , June 2021, URL: https://www.ijtsrd.compapers/ijtsrd41190.pdf Paper URL: https://www.ijtsrd.comengineering/electronics-and-communication-engineering/41190/analysis-and-simulation-of-asynchronous-machine-connected-with-load-accomplished-with-chopper-control-and-pwm-based-inverter/ms-neetu-khunte
To Design and simulate 3-Ø Induction motor driveUmang Patel
This document is a project report submitted by four students to fulfill the requirements for a Bachelor of Engineering degree in Power Electronics. It outlines a project to design and simulate a three-phase induction motor drive using constant voltage-to-frequency control with a PIC microcontroller. The report includes sections on electric drives, induction motors, voltage source inverters, simulation in MATLAB and Proteus, PIC microcontrollers, hardware implementation, and PCB design. Tables and figures are included to illustrate the system components, simulation results, and PCB layouts.
The document presents a presentation on dynamic modeling of DC motor drives. It discusses different types of DC drives including single phase, three phase, and DC-DC converter drives. It also provides the generalized electrical diagram and dynamic model of a DC motor, describing the stator inductance and resistance, and how the electrical equation for a DC motor can be derived using Laplace transforms. The dynamic model expresses the stator current as a function of the stator gain and time constant.
A PROJECT REPORT SIM & SPEED CONTROL OF INDUCTIO DRIVEPawan Kumar
The document discusses speed control methods for three-phase induction motors. It analyzes the transients during starting of an induction motor with different machine parameters. It then examines various speed control methods including variable rotor resistance, variable stator voltage, and constant V/f control. Simulation results are presented to show the torque-speed characteristics for each method. Vector control is also introduced, which allows independent control of torque and flux.
Vector control is a more advanced and precise method of controlling AC induction motors compared to scalar control. It involves transforming the motor currents and voltages into a rotating reference frame to obtain decoupled control similar to a DC motor. This allows for independent control of flux and torque for faster dynamic response and better performance than scalar control. The basic implementation of vector control uses Clarke and Park transformations to convert between stationary and rotating reference frames in the controller. It provides DC motor-like precision in speed and torque control of induction motors.
Speed control of three phase im by vf open and close loop methodeSAT Journals
This document presents a simulation of speed control for a three-phase induction motor using open-loop and closed-loop V/F control methods. In the open-loop method, a PWM inverter drives the motor and the torque is observed to remain constant with varying rotor speed. In the closed-loop method, a PI controller provides feedback to vary the supply frequency to maintain a constant V/F ratio. Simulation results in MATLAB Simulink show that closed-loop control provides superior speed regulation compared to the open-loop method.
This document describes a study on modeling and simulating a permanent magnet brushless DC (PMBLDC) motor drive system in MATLAB/Simulink. The authors develop a model of a PMBLDC motor with a 120-degree inverter system and implement closed-loop speed control using a PI controller. Simulation results confirm the validity of the model and controller. The paper examines the effects of load and inertia changes on the motor's speed performance.
This document proposes a direct torque control strategy for doubly fed induction machine-based wind turbines that can operate under voltage dips without crowbar protection. The control strategy generates a rotor flux amplitude reference to control the torque of the wind turbine and reduce stator and rotor overcurrents during faults. It also provides fast dynamic response. While the control does not eliminate the need for crowbar protection entirely, it can prevent the crowbar from activating during low-depth voltage dips. The direct torque control approach maintains machine connection to the grid and reduces torque oscillations during faults.
Use of Modular Multilevel Cascade Inverter as a Method to Speed-Sensorless St...IRJET Journal
This document summarizes a research paper that presents a speed-sensorless start-up method for an induction motor driven by a modular multilevel cascade inverter (MMCI) based on double-star chopper cells (DSCC). The start-up method combines capacitor-voltage control with motor-speed control. Capacitor-voltage control regulates the dc voltage of each capacitor and mitigates voltage fluctuations. Motor-speed control forms a feedback loop of stator currents to enable stable start-up from zero speed to middle speed without a speed sensor. Experimental results from a 15kW downscaled system verify the method enhances start-up torque by 3x under voltage fluctuations compared to previous methods.
Speed Control System of Induction Motor by using Direct Torque Control Method...ijtsrd
Escalator is useful and act in the important part to carry passengers to the targeted floors of building. Every escalator must be driven by its own motor and this motor speed must be controled. To drive escalator with a constant speed, direct torque control technique is used to drive three phase squirrel cage induction motor. In this paper, the development of speed control system for three phase squirrel cage induction motor using a direct torque control method is presented and simulation for proposed system is done with the help of MATLAB SIMULINK. Soe Sandar Aung | Thet Naing Htun "Speed Control System of Induction Motor by using Direct Torque Control Method used in Escalator" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27903.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/27903/speed-control-system-of-induction-motor-by-using-direct-torque-control-method-used-in-escalator/soe-sandar-aung
SPEED AND TORQUE CONTROL OF AN INDUCTION MOTOR WITH ANN BASED DTCijics
Due to advantages such as fast dynamic response, simple and robust control structure, direct torque
control (DTC) is commonly used method in high performance control method for induction motors. Despite
mentioned advantages, there are some chronically disadvantages with this method like high torque and
current ripples, variable switching behaviour and control problems at low speed rates. On the other hand,
artificial neural network (ANN) based control algorithms are getting increasingly popular in recent years
due to their positive contribution to the system performance. The purpose of this paper is investigating of
the effects of ANN integrated DTC method on induction motor performance by numerical simulations. For
this purpose, two different ANN models have been designed, trained and implemented for the same DTC
model. The first ANN model was designed to select optimum inverter and the second model was designed to
use in the determination of the flux vector position. Matlab/Simulink model of the proposed ANN based
DTC method was created in order to compare with the conventional DTC and the proposed DTC methods.
The simulation studies proved that the induction motor torque ripples have been reduced remarkably with
the proposed method and this approach can be a good alternative to the conventional DTC method for
induction motor control.
Review of Improved Direct Torque Control Methodologies for Induction Motor Dr...AM Publications
ecoupled control of induction motor drives is possible using Direct Torque Control (DTC) method which
is very simple control strategy compared to field oriented control. In this method direct torque control is achieved by
selecting suitable inverter switching voltage vector from a lookup table. But drawback of this method is that it
produces toque ripples. Also the switching frequency of inverter switches is not constant. Many methods have been
proposed to address these issues of DTC. This paper reviews various methodologies which are suggested to improve
performance of basic DTC induction motor drive.
Matlab simulation on chopper based speed control of dc motor: A ReviewIRJET Journal
This document summarizes a literature review on MATLAB simulation of chopper-based speed control of a DC motor. It describes how the speed of a DC motor below rated speed can be controlled by varying the armature voltage using a chopper converter in a closed-loop control system with a PI controller. The review covers DC chopper circuits, separately excited DC motors, modeling a DC motor drive system in MATLAB Simulink with a PI speed controller, and conclusions on simulating speed control of a DC motor using a chopper.
Efficient Motor Control Solutions: High Performance Servo Control (Design Con...Analog Devices, Inc.
This document provides a legal disclaimer and proprietary information notice for a presentation by Analog Devices (ADI) on efficient motor control solutions. It states that all information in the presentation is the exclusive property of ADI and cannot be reproduced or distributed without permission. It also disclaims all warranties, stating that while ADI intends the information to be accurate, no guarantees are made. It excludes liability for any damages arising from the use of the information. The presentation agenda is then outlined, covering motor applications and markets, motor operation and construction, control strategies, feedback sensors, power and isolation, and an ADI high performance servo control board.
This document presents a project report on simulating automatic speed control of a DC drive. It was submitted by four students to fulfill the requirements of a Bachelor of Technology degree. The report includes an introduction to the project, descriptions of the key components used including the DC motor, H-bridge, PWM, and sensors. It also provides the specifications of the components in the Simulink model, discusses the applications of the drive on different loads, and presents the simulation results. The conclusions discuss the advantages of the automatic speed control drive and potential future applications.
Brushles DC motor are one type of motors that are rapidly gaining the popularity and are penetrating in industrial applications, home appliances, automotive, consumer, medical etc. Because of there many advantages such as high efficiency ,silent operation, compact form ,reliability, low maintenance (due to the absence of brushess), long operating life, high speed ranges etc. for the proper commution of current in inverter the rotar position information is necessary, this information is usually provided by the mechanical position sensors mounted within the motor. however it is well known that these position sensors have many drawbacks therefore a sensor less control of BLDC motor is developed which eliminates the sensing equipment ,reduces the cost of motor and increases the reliability of the BLDC motor. In this paper the position information is obtained from the zero crossing detection of the back EMF which is also called as the terminal voltage sensing method which is the simplest ,method of detecting the back EMF zero crossing ,here the motor voltages are sensed and give to the lowpass filter whose output is give to the ZCD which determines the zero crossing of the back EMF waveform and ZCD generates the signal required for the controller to provide the pulses for the inverter operation the controller used is a high performance controller(DSPic30F4011) which as both the features of microcontroller and digital signal processor .The complete model is simulated in MATLAB/SIMULINK software. the proposed hardware and simulation program are found to be efficient and the results are promising
IRJET- Variable Frequency Drive Used in TreadmillIRJET Journal
This document summarizes the use of variable frequency drives in treadmills. It discusses how most treadmills previously used DC brush motors but these had issues like high failure rates and maintenance costs. The document then explores how using an AC motor with a variable frequency drive can improve on the limitations of DC motors. It provides details on how variable frequency drives work, including discussing the rectifier, DC bus, inverter and control circuit components. It also explains techniques like pulse width modulation and flux vector control that are used to control the speed of AC motors. The objectives of using a variable frequency drive in a treadmill are listed as energy savings, increased life of components, reduced noise and vibration, lower thermal and mechanical stresses, and
Direct torque control of induction motor using space vector modulationIAEME Publication
This document discusses direct torque control of an induction motor using space vector modulation. It begins with introducing direct torque control as an alternative to field oriented control for controlling torque and flux directly and independently. It then provides details on the principles of vector control and direct torque control in stator reference frames. The document describes the modeling of an induction motor and simulations performed in MATLAB to validate the direct torque control approach. The simulations demonstrate control of speed, torque, and flux under different gain settings of the PI controller.
V/F Control of Squirrel Cage Induction Motor Drives Without Flux or Torque Me...Waqas Tariq
Based on the popular constant volts per hertz principle, two improvement techniques are presented: keeping maximum torque constant or keeping magnetic flux constant. An open-loop inverter-three-phase squirrel-cage induction motor drive system that provides constant maximum torque or increased maximum torque and reduced slip speed at frequencies below the nominal frequency has been modeled, simulated and tested. Load performance analysis of the proposed system under different operation conditions was provided. These principles of operation are extended to the case of operation from variable frequency or variable voltage control method. Finally, the effects of the non-sinusoidal voltage and/or current wave shapes are covered. The results show that both suggested improvement techniques (constant torque or constant flux) improve the steady-state performance A.C. drive system with squirrel cage induction motors. The slip speed has been decreased and the starting torque and maximum torque have been increased, which means that the suggested control techniques can be used in drive systems with short time operating mode under light loads.
Matrix Converter based Direct Torque Control of Induction MotorNeehar NLN
This topic falls under the area of speed control of induction motor. The using of advanced power electronic converters provides better response. In this case, a AC/AC converter is used to control the induction motor.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Analysis and Simulation of Asynchronous Machine Connected with Load Accomplis...YogeshIJTSRD
This paper presents the simulation analysis of pulse width modulation based induction motor drive. The main objective of this paper is analysis of asynchronous machine with PWM fed inverter and harmonic analysis of active and reactive power as well as voltage and current. Space vector pulse width modulation technique is used in various industrial applications. Variation in voltage and frequency supply to ac drives is produced from a voltage source inverter and space vector PWM is used frequently now a day due to their easy understanding. This work is based on a SVPWM based induction motor based on space vector theory. The simulation is done on MATLAB software and the simulation results obtained and analyzed. Ms. Neetu Khunte | Mr. Abhijeet Lal | Mr. Abhishek Agrawal "Analysis and Simulation of Asynchronous Machine Connected with Load Accomplished with Chopper Control and PWM Based Inverter" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-4 , June 2021, URL: https://www.ijtsrd.compapers/ijtsrd41190.pdf Paper URL: https://www.ijtsrd.comengineering/electronics-and-communication-engineering/41190/analysis-and-simulation-of-asynchronous-machine-connected-with-load-accomplished-with-chopper-control-and-pwm-based-inverter/ms-neetu-khunte
Permanent magnet motors like brushless DC (BLDC) motors have higher efficiency than induction motors due to using fixed magnets instead of induced currents for magnetization. BLDC motors are commonly driven with either trapezoidal or sinusoidal commutation. Trapezoidal commutation provides rougher torque but is simpler to implement, while sinusoidal commutation provides smoother torque without commutation noise. Field-oriented control allows maximum performance from permanent magnet synchronous motors like BLDC motors but requires position sensing or estimation.
Power Quality Analysis of Vienna Rectifier for BLDC Motor Drive ApplicationIJPEDS-IAES
This paper presents the power quality improvements for a BLDC driver using
Vienna rectifier as front end converter. The major drawbacks in the BLDC
motor drive and non linear load applications are the line pollution and
depreciation of the power factor. The conventional power factor correction
method is not economical and efficient. It requires bulky components as load
changes and produce high THD and less Power factor. The front end
converter of BLDC bridge inverter drive is proposed by the Vienna rectifier,
which can contribute more significantly in improving the power factor and
reduce the line pollution. The Vienna rectifier topology is controlled by the
constant switching frequency control technique for wide range of load
variation and it reduces the THD, improve the power factor and provide a
steady DC link voltage to the bridge inverter to drive the BLDC motor. The
design calculation and performance characteristics of BLDC motor and
Vienna rectifier are verified by using Matlab simulation.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
This document provides information about different types of DC motors, including brush-type DC motors. It discusses the operation of brush-type DC motors, including how a commutator allows the motor to continue rotating in one direction. It also summarizes the characteristics of series wound, shunt wound, and permanent magnet DC motors, comparing their advantages and disadvantages. Key details include the varying speed characteristic of series wound motors, the relatively constant speed of shunt wound motors, and the compact size and high efficiency of permanent magnet motors.
This document provides an overview of induction and synchronous motor fundamentals, including:
- Synchronous motors operate at synchronous speed and have fixed stator windings connected to AC power, with a separate DC excitation source for the rotor. Induction motors have no separate power source for the rotor; current is induced in the rotor by the stator field.
- Synchronous motors can operate at unity or leading power factor by adjusting rotor excitation, while induction motors operate at lagging power factor.
- Common induction motor components include the squirrel cage rotor and wound stator. Synchronous motor starting methods include using a starting resistor or reduced voltage.
- Motors have different enclosure types for protection from environmental factors
1) The document discusses direct torque control (DTC) of induction motors using space vector modulation (SVM-DTC). DTC aims to control torque and flux of the motor but causes current and torque ripple.
2) SVM-DTC is proposed to reduce ripple by increasing the number of available voltage vectors applied to the motor. This provides benefits like lower torque ripple and current distortion.
3) The document then provides background on induction motors, including their construction, operation, speed control, and starting methods before discussing DTC and SVM-DTC in more detail.
This document describes scalar (V/f) control of 3-phase induction motors using TMS320F2803x microcontrollers. Scalar control is a simpler form of motor control that can provide satisfactory steady-state response. It explores using the TMS320F2803x devices to implement scalar control through variable voltage and frequency control of an induction motor. The system is built incrementally, starting with basic voltage and frequency generation and expanding to include closed-loop speed control. Experimental results are presented at each build level.
The document discusses different types of electric motors including DC motors, AC motors, and stepper motors. It provides details on the fundamental characteristics, construction, and applications of series, shunt, and permanent magnet DC motors as well as single phase, three phase, and stepper AC motors. The document also covers modeling and control methods for DC and AC motors including H-bridge control and variable frequency drives.
IRJET- Phase Conversion of VFD based Induction MotorIRJET Journal
This document discusses using a variable frequency drive (VFD) to control the speed of a three-phase induction motor. A VFD allows the motor to operate at variable speeds, which can provide energy savings compared to operating at a single rated speed. The VFD converts incoming single-phase power to three-phase power using a rectifier to produce DC power, then an inverter uses pulse width modulation to generate a three-phase AC output that can be varied in frequency to control motor speed. This setup allows flexible control of the induction motor's speed while improving efficiency over constant speed operation.
- The single phase series motor has excessive commutator sparking, making it only practical for the smallest sizes.
- Adding a compensating winding yields the compensated series motor, which overcomes sparking issues. Most AC commutator motors have this design.
- Universal motors can operate on either AC or DC and are used in small appliances requiring high speeds.
- A repulsion motor uses offset brushes to induce opposing magnetic fields for starting torque.
- A repulsion start induction motor uses shorted brushes to start the motor like a repulsion motor before engaging the induction rotor.
This document discusses traction motors used in electric rail vehicles. It covers the requirements of traction systems including high starting torque and withstanding overloads. Common types of traction motors are described like DC series motors and induction motors. Methods of controlling DC motor speed are explained, particularly electronic speed control using pulse width modulation. Braking methods for traction motors include dynamic braking by converting motors to generators and regenerative braking by feeding energy back to the supply system. Recent trends involve using multilevel converters for improved waveforms and reduced harmonics.
The document summarizes research on using space vector modulation (SVM) for speed control of an induction motor driven by a three-phase inverter. It compares SVM to sine triangle pulse width modulation (SPWM) and finds that SVM provides better harmonic performance, higher DC bus utilization, and a more sinusoidal output voltage. The document simulates v/f control of an induction motor using SVM for both open-loop and closed-loop speed control systems. It is observed that the induction motor's performance is improved with SVM compared to SPWM modulation.
By installing variable speed AC drives, you can improve process controls, increase energy savings, reduce wear on machinery, and improve power factor (PF). AC drives improve PF by circulating the motor's reactive current internally rather than sending it back to the power supply. This allows the drive's input current to be lower than the output current to the motor. For example, a drive might have an output current of 94.5A but only require an input current of 60A, reducing losses in the power system by 5%. While the primary benefits of drives are improved control and energy savings, higher PF is an added advantage that can save on utility penalties for low PF.
Speed Control of Induction Motor Using Hysteresis MethodIRJET Journal
This document discusses speed control of an induction motor using a hysteresis control method. It begins with an abstract that outlines using hysteresis current control in the speed loop control design to optimize induction motor performance. It then discusses using an extended state observer to estimate disturbances and compensate the speed controller. The document provides background on induction motors, including details on their stator, squirrel cage and wound rotors. It also discusses using inverters like diode-clamped and flying-capacitor inverters to generate the AC voltages used to drive the motor.
Study of Vector Control Algorithm and Inverter design for BLDC Motor, V/f con...Amol Mahurkar
This document summarizes a study on vector control algorithms and inverter design for BLDC motors. It discusses the objectives of studying BLDC motor operation, different control algorithms including vector control, and inverter design. It also covers V/F control of induction motors. Key topics covered include Clarke/Park transformations, sensorless control, inverter topologies, and a comparison of vector and V/F control techniques. The document is authored by engineering students and provides an overview of various motor control concepts and algorithms.
The document discusses upgrading an Elektra-Faurandau motor control system by implementing variable frequency drive (VFD) technology. It describes the working principles of the existing Elektra-Faurandau motor and identifies issues with it like commutator sparking and overheating. It proposes replacing the motor with an induction motor for improved efficiency and reliability. Implementing VFD controllers would allow variable speed control of the induction motors while reducing starting current and mitigating issues on the electrical supply network. The document provides details on selecting VFD parameters for different applications like pumps and extruders to optimize performance and protection.
This document provides an overview of functional safety and the requirements of the Machinery Directive. It discusses safety systems for machinery that monitor operations and ensure safe functioning. The document is divided into three parts that cover the theory of functional safety, standards related to the Machinery Directive, and steps for meeting the Directive's requirements. Ensuring functional safety helps prevent accidents and injury while allowing for productivity. The Machinery Directive defines essential health and safety requirements that machinery in the EU must fulfill.
The document provides guidance on EU Council Directives and their application to adjustable speed electrical power drive systems. It addresses questions about CE marking and what it signifies. CE marking indicates a product complies with applicable EU directives, but does not guarantee quality. The document outlines responsibilities and actions required of different parties in the supply chain, such as manufacturers, machine builders, end users and installers, to ensure compliance. It provides checklists and refers to other sections for more detailed explanations of technical documentation, standards, directives and related terminology.
This document provides an overview of direct torque control (DTC) technology, which is described as the most advanced AC drive technology. It discusses the evolution of variable speed drives from early DC motor drives to modern AC drives that use frequency control, flux vector control, and finally DTC. DTC directly controls motor torque and flux without requiring a modulator or feedback device, providing faster torque response than other drive technologies. The document compares different drive technologies and explains the advantages of DTC in meeting industry demands for better product quality, reduced downtime, fewer required products, and a more comfortable working environment.
El documento describe las pruebas de factor de potencia/disipación para evaluar el aislamiento de transformadores de potencia. Estas pruebas eléctricas miden la corriente de fuga en el aislamiento bajo tensión alterna para determinar la capacitancia y el factor de disipación. Los resultados indican el estado del aislamiento y si ha habido cambios debidos a envejecimiento, contaminación u humedad. Se explican los diferentes modos de prueba y la importancia de corregir los resultados por la temperatura para una adecuada interpretación.
The document discusses Megger's Dielectric Oil Test Set product line. It provides details on the applications and customers of oil testing, an overview of the product range and improvements, and how the tests are performed. Key features of the new test sets are highlighted such as their lightweight and durable design, precise electrode gap adjustment, reliable results, easy recording and reporting of test data, and flexibility to update test standards.
El documento presenta el nuevo DET14C y DET24C, pinzas probadoras de tierra digitales fabricadas por Megger. Proporcionan mediciones seguras de resistencia de tierra y corriente hasta 600V. Ofrecen características mejoradas como pantalla retroiluminada, memoria avanzada, larga duración de batería y filtro de ruido. Están diseñados para usos como pruebas en subestaciones, torres de comunicación y sistemas de protección contra rayos.
Este documento presenta la gama de ohmímetros de baja resistencia DLRO10 de Megger. Describe las características y especificaciones de los modelos DLRO10, DLRO10X e DLRO10HD. El DLRO10HD es el modelo más reciente diseñado para condiciones extremas con una carcasa dura, pantalla LCD retroiluminada, batería recargable, conexión a la red eléctrica y cinco modos de prueba. La gama completa ofrece mediciones de resistencia desde 100 microohmios hasta 2500 ohmios con protección de entrada
El documento presenta diferentes técnicas modernas de diagnóstico para transformadores de potencia, incluyendo mediciones de capacitancia y factor de disipación, análisis de respuesta en frecuencia y espectroscopia dieléctrica. Explica la importancia del mantenimiento de transformadores y describe sus principales componentes. Además, analiza en detalle las mediciones de capacitancia y factor de disipación tanto de los arrollamientos como de los bushings.
The document provides information on new insulation resistance testers from Megger, including the MIT515, MIT525, MIT1025, S1-568, and S1-1068 models. It discusses the features and benefits of the new models compared to previous versions, such as increased noise immunity, faster charge times, remote operation via Bluetooth or USB, and improved safety. The document also outlines how the different models are suited to various applications and customer types, with the MIT series targeted towards industrial users and the S1 series aimed at utilities and service companies operating in noisier environments.
Este documento presenta información sobre la espectroscopia dieléctrica en el dominio de la frecuencia (DFR) y su aplicación para el diagnóstico de transformadores de potencia. Explica que la DFR mide la capacitancia y el factor de disipación a diferentes frecuencias para determinar la humedad en el aislamiento de papel y la conductividad del aceite aislante. También describe cómo la respuesta del sistema aislante del transformador es una combinación de las respuestas del aceite y el papel, y cómo la DFR puede usarse para evalu
Este documento trata sobre las pruebas de factor de potencia y factor de disipación que se realizan en transformadores. Explica que estas pruebas aplican tensión alterna para medir la corriente de fuga en el aislamiento eléctrico. También describe los diferentes modos de prueba como UST, GST y GST con guarda, y cómo estas pruebas pueden identificar problemas en el aislamiento como contaminación o deterioro.
La gama DET3 y DET4 ofrece probadores de tierra portátiles con pantalla digital para medir la resistividad del suelo y resistencia de sistemas de tierra. Incluyen características como salida especificada para cumplir con normas de seguridad, función de voltímetro, rechazo de ruido, clasificación IP54 y CATIV 100V, y capacidad para realizar pruebas ART, sin estacas, con frecuencia variable, medición de corriente de tierra y rango de 200kΩ. Están diseñados para aplicaciones de campo y
Este documento presenta información sobre pruebas eléctricas para transformadores de potencia. Explica la necesidad de realizar pruebas para evitar averías, y describe varias pruebas de campo comunes como relación de transformación, resistencia de devanados, corriente de excitación y reactancia de fuga. El objetivo de estas pruebas es diagnosticar posibles defectos y asegurar un funcionamiento confiable de los transformadores.
Este documento presenta información sobre el Código Nacional de Electricidad de Perú. Incluye secciones sobre el objetivo del código, las tensiones normalizadas, normas técnicas de referencia, protección contra rayos, y distancias de seguridad requeridas entre instalaciones eléctricas y establecimientos de gas. El documento proporciona detalles técnicos sobre los requisitos de seguridad para instalaciones eléctricas en Perú.
Accident detection system project report.pdfKamal Acharya
The Rapid growth of technology and infrastructure has made our lives easier. The
advent of technology has also increased the traffic hazards and the road accidents take place
frequently which causes huge loss of life and property because of the poor emergency facilities.
Many lives could have been saved if emergency service could get accident information and
reach in time. Our project will provide an optimum solution to this draw back. A piezo electric
sensor can be used as a crash or rollover detector of the vehicle during and after a crash. With
signals from a piezo electric sensor, a severe accident can be recognized. According to this
project when a vehicle meets with an accident immediately piezo electric sensor will detect the
signal or if a car rolls over. Then with the help of GSM module and GPS module, the location
will be sent to the emergency contact. Then after conforming the location necessary action will
be taken. If the person meets with a small accident or if there is no serious threat to anyone’s
life, then the alert message can be terminated by the driver by a switch provided in order to
avoid wasting the valuable time of the medical rescue team.
Levelised Cost of Hydrogen (LCOH) Calculator ManualMassimo Talia
The aim of this manual is to explain the
methodology behind the Levelized Cost of
Hydrogen (LCOH) calculator. Moreover, this
manual also demonstrates how the calculator
can be used for estimating the expenses associated with hydrogen production in Europe
using low-temperature electrolysis considering different sources of electricity
Supermarket Management System Project Report.pdfKamal Acharya
Supermarket management is a stand-alone J2EE using Eclipse Juno program.
This project contains all the necessary required information about maintaining
the supermarket billing system.
The core idea of this project to minimize the paper work and centralize the
data. Here all the communication is taken in secure manner. That is, in this
application the information will be stored in client itself. For further security the
data base is stored in the back-end oracle and so no intruders can access it.
Tools & Techniques for Commissioning and Maintaining PV Systems W-Animations ...Transcat
Join us for this solutions-based webinar on the tools and techniques for commissioning and maintaining PV Systems. In this session, we'll review the process of building and maintaining a solar array, starting with installation and commissioning, then reviewing operations and maintenance of the system. This course will review insulation resistance testing, I-V curve testing, earth-bond continuity, ground resistance testing, performance tests, visual inspections, ground and arc fault testing procedures, and power quality analysis.
Fluke Solar Application Specialist Will White is presenting on this engaging topic:
Will has worked in the renewable energy industry since 2005, first as an installer for a small east coast solar integrator before adding sales, design, and project management to his skillset. In 2022, Will joined Fluke as a solar application specialist, where he supports their renewable energy testing equipment like IV-curve tracers, electrical meters, and thermal imaging cameras. Experienced in wind power, solar thermal, energy storage, and all scales of PV, Will has primarily focused on residential and small commercial systems. He is passionate about implementing high-quality, code-compliant installation techniques.
Digital Twins Computer Networking Paper Presentation.pptxaryanpankaj78
A Digital Twin in computer networking is a virtual representation of a physical network, used to simulate, analyze, and optimize network performance and reliability. It leverages real-time data to enhance network management, predict issues, and improve decision-making processes.
Blood finder application project report (1).pdfKamal Acharya
Blood Finder is an emergency time app where a user can search for the blood banks as
well as the registered blood donors around Mumbai. This application also provide an
opportunity for the user of this application to become a registered donor for this user have
to enroll for the donor request from the application itself. If the admin wish to make user
a registered donor, with some of the formalities with the organization it can be done.
Specialization of this application is that the user will not have to register on sign-in for
searching the blood banks and blood donors it can be just done by installing the
application to the mobile.
The purpose of making this application is to save the user’s time for searching blood of
needed blood group during the time of the emergency.
This is an android application developed in Java and XML with the connectivity of
SQLite database. This application will provide most of basic functionality required for an
emergency time application. All the details of Blood banks and Blood donors are stored
in the database i.e. SQLite.
This application allowed the user to get all the information regarding blood banks and
blood donors such as Name, Number, Address, Blood Group, rather than searching it on
the different websites and wasting the precious time. This application is effective and
user friendly.
Prediction of Electrical Energy Efficiency Using Information on Consumer's Ac...PriyankaKilaniya
Energy efficiency has been important since the latter part of the last century. The main object of this survey is to determine the energy efficiency knowledge among consumers. Two separate districts in Bangladesh are selected to conduct the survey on households and showrooms about the energy and seller also. The survey uses the data to find some regression equations from which it is easy to predict energy efficiency knowledge. The data is analyzed and calculated based on five important criteria. The initial target was to find some factors that help predict a person's energy efficiency knowledge. From the survey, it is found that the energy efficiency awareness among the people of our country is very low. Relationships between household energy use behaviors are estimated using a unique dataset of about 40 households and 20 showrooms in Bangladesh's Chapainawabganj and Bagerhat districts. Knowledge of energy consumption and energy efficiency technology options is found to be associated with household use of energy conservation practices. Household characteristics also influence household energy use behavior. Younger household cohorts are more likely to adopt energy-efficient technologies and energy conservation practices and place primary importance on energy saving for environmental reasons. Education also influences attitudes toward energy conservation in Bangladesh. Low-education households indicate they primarily save electricity for the environment while high-education households indicate they are motivated by environmental concerns.
Height and depth gauge linear metrology.pdfq30122000
Height gauges may also be used to measure the height of an object by using the underside of the scriber as the datum. The datum may be permanently fixed or the height gauge may have provision to adjust the scale, this is done by sliding the scale vertically along the body of the height gauge by turning a fine feed screw at the top of the gauge; then with the scriber set to the same level as the base, the scale can be matched to it. This adjustment allows different scribers or probes to be used, as well as adjusting for any errors in a damaged or resharpened probe.
Open Channel Flow: fluid flow with a free surfaceIndrajeet sahu
Open Channel Flow: This topic focuses on fluid flow with a free surface, such as in rivers, canals, and drainage ditches. Key concepts include the classification of flow types (steady vs. unsteady, uniform vs. non-uniform), hydraulic radius, flow resistance, Manning's equation, critical flow conditions, and energy and momentum principles. It also covers flow measurement techniques, gradually varied flow analysis, and the design of open channels. Understanding these principles is vital for effective water resource management and engineering applications.
5. Technical guide No. 5 | Bearing currents in modern AC drive systems 5
Contents
Chapter 1 - Introduction ............................................................................7
General .............................................................................................7
Avoiding bearing currents ..................................................................7
Chapter 2 - Generating bearing currents ...................................................8
High frequency current pulses ............................................................8
Faster switching ................................................................................9
How are HF bearing currents generated?.............................................9
Circulating current ........................................................................9
Shaft grounding current .................................................................9
Capacitive discharge current ........................................................10
Common mode circuit ......................................................................10
Stray capacitances ..........................................................................11
How does the current flow through the system? ................................12
Voltage drops...................................................................................13
Common mode transformer ..............................................................14
Capacitive voltage divider .................................................................15
Chapter 3 - Preventing high frequency bearing current damage.............17
Three approaches ............................................................................17
Multicore motor cables.................................................................17
Short impedance path .................................................................17
High frequency bonding connections ...........................................18
Follow product specific instructions ..................................................19
Additional solutions .....................................................................19
Measuring high frequency bearing currents........................................19
Leave the measurements to the specialists ........................................20
Chapter 4 - References............................................................................21
Chapter 5 - Index.....................................................................................22
7. Technical guide No. 5 | Bearing currents in modern AC drive systems 7
Chapter 1 - Introduction
General
Some new drive installations can have their bearings fail only
a few months after startup. Failure can be caused by high fre-
quency currents, which flow through the motor bearings.
While bearing currents have been around since the advent
of electric motors, the incidence of damage they cause has
increased during the last few years. This is because modern
variable speed drives with their fast rising voltage pulses and
high switching frequencies can cause current pulses through
the bearings whose repeated discharging can gradually erode
the bearing races.
Avoiding bearing currents
To avoid damage occurring, it is essential to provide proper
earthing paths and allow stray currents to return to the inverter
frame without passing through the bearings. The magnitude of
the currents can be reduced by using symmetrical motor cables
or inverter output filtering. Proper insulation of the motor bearing
construction breaks the bearing current paths.
8. 8 Bearing currents in modern AC drive systems | Technical guide No. 5
Chapter 2 - Generating bearing currents
High frequency current pulses
Bearing currents come in several different guises. However,
while modern motor design and manufacturing practices have
nearly eliminated the low frequency bearing currents induced by
the asymmetry of the motor, the rapid switching in modern AC
drive systems may generate high frequency (HF) current pulses
through the bearings. If the energy of these pulses is sufficiently
high, metal transfers from the ball and the races to the lubricant.
This is known as electrical discharge machining or EDM. The
effect of a single pulse is insignificant, but a tiny EDM pit is an
incontinuity that will collect more pulses and expand into a typi-
cal EDM crater. The switching frequency of modern AC drives is
very high and the vast number of pulses causes the erosion to
quickly accumulate. As a result, the bearing may need replacing
after only a short time in service.
High frequency bearing currents have been investigated by
ABB since 1987. The importance of system design has been
highlighted in the last few years. Each individual item involved,
such as the motor, the gearbox or the drive controller, is the
product of sophisticated manufacturing techniques and normally
carries a favourable mean time between failure (MTBF) rate. It is
when these components are combined and the installed system
is looked upon as a whole, that it becomes clear that certain
installation practices are required.
Figure 1: Bearing currents can cause “bearing fluting”, a rhythmic
pattern on the bearing’s races.
9. Technical guide No. 5 | Bearing currents in modern AC drive systems 9
Faster switching
Current AC drive technology, incorporating insulated gate bipo-
lar transistors (IGBT), creates switching events 20 times faster
than those considered typical ten years ago. Recent years have
seen a rising number of EDM-type bearing failures in AC drive
systems relatively soon after startup, within one to six months.
The extent to which this occurs depends on the AC drive system
architecture and the installation techniques used.
How are HF bearing currents generated?
The source of bearing currents is the voltage that is induced
over the bearing. In the case of high frequency bearing currents,
this voltage can be generated in three different ways. The most
important factors that define which mechanism is prominent, are
the size of the motor and how the motor frame and shaft are
grounded. The electrical installation, meaning a suitable cable
type and proper bonding of the protective conductors and the
electrical shield, plays an important role. Du/dt of the AC drive
power stage components and the DC-link voltage level affect
the level of bearing currents.
Circulating current
In large motors, high frequency voltage is induced between the
ends of the motor shaft by the high frequency flux circulating
around the stator. This flux is caused by a net asymmetry of
capacitive current leaking from the winding into the stator frame
along the stator circumference. The voltage between the shaft
ends affects the bearings. If it is high enough to overcome the
impedance of the bearings’ oil film, a current that tries to com-
pensate the net flux in the stator starts to flow in the loop formed
by the shaft, the bearings and the stator frame. This current is a
circulating type of high frequency bearing current.
Shaft grounding current
The current leaking into the stator frame needs to flow back to
the inverter, which is the source of this current. Any route back
contains impedance, and therefore the voltage of the motor
frame increases in comparison to the source ground level. If the
motor shaft is earthed via the driven machinery, the increase of
the motor frame voltage is seen over the bearings. If the voltage
rises high enough to overcome the impedance of the drive-end
bearing oil film, part of the current may flow via the drive-end
bearing, the shaft and the driven machine back to the inverter.
This current is a shaft grounding type of high frequency bearing
current.
Generating bearing currents
10. 10 Bearing currents in modern AC drive systems | Technical guide No. 5
Capacitive discharge current
In small motors, the internal voltage division of the common
mode voltage over the internal stray capacitances of the motor
may cause shaft voltages high enough to create high frequency
bearing current pulses. This can happen if the shaft is not earthed
via the driven machinery while the motor frame is earthed in the
standard way for protection.
Common mode circuit
High frequency bearing currents are a consequence of the cur-
rent flow in the common mode circuit of the AC drive system.
A typical three-phase sinusoidal power supply is balanced and
symmetrical under normal conditions. That is, the vector sum of
the three phases always equals zero. Thus, it is normal that the
neutral is at zero volts. However, this is not the case with a PWM
switched three-phase power supply, where a dc voltage is con-
verted into three phase voltages. Even though the fundamental
frequency components of the output voltages are sy mmetrical
and balanced, it is impossible to make the sum of three output
voltages instantaneously equal to zero with two possible output
levels available. The resulting neutral point voltage is not zero.
This voltage may be defined as a common mode voltage source.
It is measurable at the zero point of any load, eg. the star point
of the motor winding.
Figure 2: This schematic shows the phase voltages of a typical three
phase PWM power supply and the average of the three, or neutral point
voltage, in a modern AC drive system. The neutral voltage is clearly
not zero and its presence can be defined as a common mode voltage
source. The voltage is proportional to the DC bus voltage, and has a
frequency equal to the inverter switching frequency.
Generating bearing currents
11. Technical guide No. 5 | Bearing currents in modern AC drive systems 11
Figure 3: An example of the common mode current at the inverter output.
The pulse is a superposition of several frequencies due to the different
natural frequencies of the parallel routes of common mode current.
Stray capacitances
A capacitance is created any time two conductive components
are separated by an insulator. For instance, the cable phase wire
has capacitance to the PE-wire separated by PVC insulation,
for example, and the motor winding turn is insulated from the
frame by enamel coating and slot insulation, and so has a value
of capacitance to the motor frame. The capacitances within a
cable and especially inside the motor are very small. A small
capacitance means high impedance for low frequencies, thus
blocking the low frequency stray currents. However, fast rising
pulses produced by modern power supplies contain frequencies
so high that even small capacitances inside the motor provide a
low impedance path for current to flow.
Any time one of the three inverter outputs is changed from one
of the possible potentials to another, a current proportional
to this voltage change is forced to flow to earth via the earth
capacitances of all the components of the output circuit. The
current flows back to the source via the earth conductor and
stray capacitances of the inverter, which are external to the
three phase system. This type of current, which flows through
the system in a loop that is closed externally to the system, is
called common mode current.
Generating bearing currents
12. 12 Bearing currents in modern AC drive systems | Technical guide No. 5
Figure 4: Simplified loop of the common mode current of a PWM inverter
and induction motor. The inverter power supply acts as a common mode
voltage source (Vcm). Common mode current (CMC) flows through the
common mode cable and motor inductances, Lc Lm and through the stray
capacitances between the motor windings and motor frame, combined
to be Cm. From the motor frame, the current proceeds through the
factory earth circuit which has the inductance Lg. Lg is also fed common
mode current from the stray cable capacitance Cc. The inverter frame is
connected to the factory earth and couples the common mode current/
earth currents through stray inverter to frame capacitances, combined
as Cin, back to the common mode voltage source.
How does the current flow through the system?
The return path of the leakage current from the motor frame
back to the inverter frame consists of the motor frame, cable
shielding or PE-conductors and possibly steel or aluminium
parts of the factory building structure. All these elements contain
inductance. The flow of common mode current through such
inductance will cause a voltage drop that raises the motor frame
potential above the source ground potential at the inverter frame.
This motor frame voltage is a portion of the inverter’s common
mode voltage. The common mode current will seek the path of
least impedance. If a high amount of impedance is present in
the intended paths, like the PE-connection of the motor frame,
the motor frame voltage will cause some of the common mode
current to be diverted into an unintended path, through the
building. In practical installations a number of parallel paths
exist. Most have a minor effect on the value of common mode
current or bearing currents, but may be significant in coping with
EMC-requirements.
Generating bearing currents
13. Technical guide No. 5 | Bearing currents in modern AC drive systems 13
Voltage drops
If the value of this inductance is high enough, the reactance at
the upper range of typical common mode current frequencies,
50 kHz to 1 MHz, can support voltage drops of over 100 volts
between the motor frame and the inverter frame. If, in such a
case, the motor shaft is connected through a metallic coupling
to a gearbox or other driven machinery that is solidly earthed
and near the same earth potential as the inverter frame, then it
is possible, that part of the inverter common mode current flows
via the motor bearings, the shaft and the driven machinery back
to the inverter.
Figure 5: A schematic presentation showing the circulating current
and shaft grounding current, the latter resulting from high motor frame
voltage with superior machine earthing.
If the shaft of the machinery has no direct contact to the ground
level, current may flow via the gearbox or machine bearings.
These bearings may be damaged before the motor bearings.
Figure 6: Source of circulating high frequency bearing current. Current
leakage through distributed stator capacitances gives a non-zero current
sum over the stator circumference. This leads to a net magnetising
effect and flux around the motor shaft.
Generating bearing currents
14. 14 Bearing currents in modern AC drive systems | Technical guide No. 5
Common mode transformer
The largest share of the motor’s stray capacitance, is formed
between the stator windings and the motor frame. This capaci-
tance is distributed around the circumference and length of the
stator. As the current leaks into the stator along the coil, the
high frequency content of the current entering the stator coil is
greater than the current leaving.
This net current produces a high frequency magnetic flux that
will circulate in the stator laminations, inducing an axial voltage
in the shaft ends. If the voltage becomes large enough, a high
frequency circulating current can flow, internal to the motor,
through the shaft and both bearings. The motor can, in this case,
be thought of as a transformer, where the common mode current
flowing in the stator frame acts as a primary and induces the
circulating current into the rotor circuit or secondary. This bear-
ing current is considered to be the most damaging with typical
peak values of 3 to 20 amps depending on the rated power of
the motor, du/dt of the AC drive power stage components and
DC-link voltage level.
Figure 7: The high frequency axial shaft voltage can be thought of as
the resultant of a transformer effect, in which the common mode current
flowing in the stator frame acts as a primary, and induces the circulating
current into the rotor circuit or secondary.
Another version of circulating bearing current occurs when, the
current, instead of circulating completely inside the motor, flows
via the shaft and the bearings of the gearbox or driven machinery
and in a structural element that is both external and common to
the motor and the driven machine. The origin of the current is the
same as in the current circulating inside the motor. An example of
this “vagabond” circulating bearing current is shown in figure 8.
Generating bearing currents
15. Technical guide No. 5 | Bearing currents in modern AC drive systems 15
Generating bearing currents
Figure 8: “Vagabond” circulating bearing current, where the current loop
is external to the motor.
Capacitive voltage divider
Other stray capacitances are also present in the motor, such as
the capacitance between the stator windings and the rotor, or
that existing in the motor’s airgap between the stator iron and the
rotor. The bearings themselves may even have stray capacitance.
The existence of capacitance between the stator windings and
the rotor effectively couples the stator windings to the rotor
iron, which is also connected to the shaft and the bearing’s in-
ner races. Fast changes in the common mode current from the
inverter can not only result in currents in the capacitance around
the circumference and length of the motor, but also between the
stator windings and the rotor into the bearings.
Figure 9: Common mode loop of variable speed drive, showing stator,
rotor and bearing stray capacitances.
The current flow into the bearings can change rapidly, as this
depends on the physical state of the bearing at any one time. For
instance, the presence of stray capacitance in the bearings is only
sustained for as long as the balls of the bearings are covered in
oil or grease and are non-conducting. This capacitance, where
16. 16 Bearing currents in modern AC drive systems | Technical guide No. 5
the induced shaft voltage builds up, can be short-circuited if the
bearing voltage exceeds the threshold of its breakover value or
if a “high spot” on a ball breaks through the oil film and makes
contact with both bearing races. At very low speed, the bearings
have metallic contact since the balls have not risen on an oil film.
Generally, the bearing impedance governs the voltage level at
which the bearings start to conduct. This impedance is a non-
linear function of bearing load, temperature, speed of rotation
and lubricant used, and the impedance varies from case to case.
Generating bearing currents
17. Technical guide No. 5 | Bearing currents in modern AC drive systems 17
Chapter 3 - Preventing high frequency
bearing current damage
Three approaches
There are three approaches used to affect high frequency bear-
ing currents: a proper cabling and earthing system; breaking the
bearing current loops; and damping the high frequency common
mode current. All these aim to decrease the bearing voltage to
values that do not induce high frequency bearing current pulses
at all, or damp the value of the pulses to a level that has no ef-
fect on bearing life. For different types of high frequency bearing
currents, different measures need to be taken.
The basis of all high frequency current mastering is the proper
earthing system. Standard equipment earthing practices are
mainly designed to provide a sufficiently low impedance connec-
tion to protect people and equipment against system frequency
faults. A variable speed drive can be effectively earthed at the
high common mode current frequencies, if the installation fol-
lows three practices:
Multicore motor cables
Use only symmetrical multicore motor cables. The earth (pro-
tective earth, PE) connector arrangement in the motor cable
must be symmetrical to avoid bearing currents at fundamental
frequency. The symmetricity of the PE-conductor is achieved
by a conductor surrounding all the phase leads or a cable that
contains a symmetrical arrangement of three phase leads and
three earth conductors.
Figure 10: Recommended motor cable with symmetrical core
configuration.
Short impedance path
Define a short, low impedance path for common mode current
to return to the inverter. The best and easiest way to do this is to
use shielded motor cables. The shield must be continuous and
of good conducting material, ie, copper or aluminium and the
connections at both ends need to be made with 360° termination.
18. 18 Bearing currents in modern AC drive systems | Technical guide No. 5
Preventing high frequency bearing current damage
Figures 11a and 11b show 360° terminations for European and
American cabling practices.
Figure 11 a: Proper 360° termination with European cabling practice.
The shield is connected with as short a pigtail as possible to the PE
terminal. To make a 360° high frequency connection between the EMC
sleeve and the cable shield, the outer insulation of the cable is stripped
away.
Figure 11 b: Proper 360° termination with American cabling practice.
An earthing bushing should be used on both ends of the motor cable to
effectively connect the earth wires to the armour or conduit.
High frequency bonding connections
Add high frequency bonding connections between the installa-
tion and known earth reference points to equalise the potential
of affected items, using braided straps of copper 50 - 100 mm
wide; flat conductors will provide a lower inductance path than
round wires. This must be made at the points where discontinu-
ity between the earth level of the inverter and that of the mo-
tor is suspected. Additionally it may be necessary to equalise
the potential between the frames of the motor and the driven
machinery to short the current path through the motor and the
driven machine bearings.
19. Technical guide No. 5 | Bearing currents in modern AC drive systems 19
Figure 12: HF bonding strap
Follow product specific instructions
Although the basic principles of installations are the same, for
different products suitable installation practices may differ. There-
fore, it is essential to carefully follow the installation instructions
given in product specific manuals.
Additional solutions
Breaking the bearing current loops is achieved by insulating the
bearing construction. The high frequency common mode current
can be damped by using dedicated filters. As a manufacturer of
both inverters and motors, ABB can offer the most appropriate
solution in each case as well as detailed instructions on proper
earthing and cabling practices.
Measuring high frequency bearing currents
Monitoring the bearing condition must be conducted with es-
tablished vibration measurements.
It is impossible to measure bearing currents directly from a
standard motor. But if high frequency bearing currents are
suspected, field measurements can be taken to verify the exist-
ence of suspected current loops. Measuring equipment needs
to have wide bandwidth (minimum 10 kHz to 2 MHz) capable of
detecting peak values of at least 150 to 200 A and RMS values
at least down to 10 mA. The crest factor of measured signals
is seldom less than 20. The current may flow in unusual places,
such as rotating shafts. Thus, special equipment and experienced
personnel are needed.
ABB uses a specially designed, flexible, air-cored, Rogowski-
type current sensor with dedicated accessories and has vast
experience of over one thousand measured drives in different
applications worldwide.
Preventing high frequency bearing current damage
20. 20 Bearing currents in modern AC drive systems | Technical guide No. 5
The most important measurement points are within the motor.
During measurements, the motor speed needs to be at least
10% of the nominal for the bearings to rise on the oil film. As an
example, basic measurements are shown in figure 13. Figure 14
shows examples of measured current waveforms. GTO (gate
turn-off thyristor) inverters were used mainly in the 1980s and
IGBT inverters are used today. Note the different scale in the
various graphs.
Figure 13: Basic measurements: A) circulating current measured with a
jumper, B) shaft grounding current.
A) Circulating current
GTO-inverter, 5 μs/div, 2 A/div IGBT-inverter, 5 μs/div, 2 A/div
B) Shaft grounding current
GTO-inverter, 2 μs/div, 10 A/div IGBT-inverter, 5 μs/div, 500 mA/div
Figure 14: Examples of current waveforms at the measuring points
shown in Figure 13.
Leave the measurements to the specialists
Since suitable commercial measurement equipment is not
available on the market and specialised experience is needed
to make the measurements and interpret the results, it is advis-
able that bearing current measurements are made by dedicated
personnel only.
Preventing high frequency bearing current damage
21. Technical guide No. 5 | Bearing currents in modern AC drive systems 21
Chapter 4 - References
1. Grounding and Cabling of the Drive System,
ABB Industry Oy, 3AFY 61201998 R0125
2. A New Reason for Bearing Current Damage in Variable
Speed AC Drives
by J. Ollila, T. Hammar, J. Iisakkala, H. Tuusa. EPE 97, 7th
European Conference on Power Electronics and Applica-
tions, 8-10 September 1997. Trondheim, Norway.
3. On the Bearing Currents in Medium Power Variable
Speed AC Drives
by J. Ollila, T. Hammar, J. Iisakkala, H. Tuusa. proceedings
of the IEEE IEDMC in Milwaukee, May 1997.
4. Minimizing Electrical Bearing Currents in Adjustable
Speed Drive Systems
by Patrick Link. IEEE IAS Pulp & Paper
Conference Portland, ME, USA. June 1998.
5. Instruction on Measuring Bearing Currents with a
Rogowski Coil, ABB Industry Oy, 3BFA 61363602.EN.
6. Laakerivirta ja sen minimoiminen säädettyjen vaihto-
virtakäyttöjen moottoreissa,
I. Erkkilä, Automaatio 1999, 16.9.1999, Helsinki, Finland.
(In Finnish).
7. High Frequency Bearing Currents in Low Voltage
Asynchronous Motors,
ABB Motors Oy and ABB Industry Oy, 00018323.doc.
8. Bearing Currents in AC Drives
by ABB Industry Oy and ABB Motors Oy. Set of overheads
in LN database “Document Directory Intranet” on ABB_
FI01_SPK08/FI01/ABB
9. The Motor Guide
GB 98-12.
See also product specific installation manuals.
22. 22 Bearing currents in modern AC drive systems | Technical guide No. 5
Chapter 5 - Index
Symbols
360° termination 17, 18
360° terminations 18
A
ABB 19
AC drive 9, 10
armour 18
axial shaft voltage 14, 15
axial voltage 14
B
balls 15, 16
bearing 8, 9, 15, 16
bearing current 9, 14, 20
bearing current loops 17, 19
bearing current paths 7
bearing currents 7, 9, 17, 19
bearing fluting 8
bearing races 7
bearings 7, 8, 14, 15, 16
bearing voltage 16
bonding connections 18
braided straps 18
C
cable 17
cable capacitance 12
cable shield 18
circulating current 14
common mode cable 12
common mode current 11, 12, 13,
14, 15, 17, 19
common mode loop 15
common mode voltage 10, 12
conduit 18
crest factor 19
current pulses 7
D
DC bus voltage 10
dedicated filters 19
drive controller 8
driven machine 9, 18
driven machinery 10, 13, 14
E
earthing paths 7
EDM 9
EDM crater 8
electrical discharge machining 8
electrical shield 9
electric motors 7
F
field measurements 19
flat conductors 18
frame 18
G
gearbox 8, 13, 14
GTO (gate turn-off thyristor) invert-
ers 20
H
high frequency bearing currents 9
high frequency bearing voltage 9
high frequency circulating current
14
high frequency current mastering
17
high frequency current pulses 8
high frequency flux 9
high switching frequencies 7
I
IGBT inverters 20
induced shaft voltage 16
insulated gate bipolar transistors
(IGBT) 9
internal voltage division 10
inverter 9, 11, 12, 13, 15, 17, 18
inverter frame 7, 13
inverter output filtering 7
inverter power supply 12
inverter switching frequency 10
L
low frequency bearing currents 8
M
machine 13
machinery 13, 18
magnetic flux 14
mean time between failure (MTBF)
8
metallic coupling 13
modern drive systems 8
motor 8, 11, 12, 14, 15, 17, 18,
19
motor bearing 7
motor cable 17, 18
motor frame 9, 10, 11, 12, 13, 14
motors 9, 10, 19
motor shaft 9, 13
motor windings 12
23. Technical guide No. 5 | Bearing currents in modern AC drive systems 23
N
neutral point voltage 10
O
oil film 9, 20
P
primary 14
PWM 10, 12
R
races 8, 16
Rogowski-type current sensor 19
rotor 14, 15
rotor circuit 14
S
secondary 14
shaft 10, 14, 15
shaft ends 14
shaft voltages 10
shield 17
stator 9, 14, 15
stator frame 9, 13, 14
stator laminations 14
stator windings 14, 15
stray capacitance 10, 11, 12, 14, 15
stray currents 7
symmetrical motor cables 7
symmetrical multicore motor cables
17
T
three-phase sinusoidal power supply
10
three phase power supply 10
transformer 14
V
variable speed drive 15, 17
voltage drop 12, 13
voltage pulses 7
W
winding 9, 10, 11, 12, 14, 15
Index