Automobile alternators can provide a low-cost alternative to conventional stepper motors for speed control applications. By disconnecting the rectifier stack and connecting a transistorized inverter, an alternator can function as a stepper motor. Typical performance curves show a alternator-based motor can output up to 180W at 1800 rpm, with a holding torque of 1-3 Nm and maximum speed of 2500 rpm. Compared to traditional stepper motors, alternator-based motors have similar performance at a lower cost, making them suitable for constant-speed control applications.
A ZVS Interleaved Boost AC/DC Converter Using Super Capacitor Power for Hybri...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
High Tension Current Transformer in Punebizproto26
We are recognized as a successful manufacturers, exporters and traders of Current Transformers. It is a static machine used for transforming power from one circuit to another without changing frequency. Current Transformers is generally used in transmission network which is normally known as power transformer, distribution transformer is used in distribution network and this is lower rating transformer and current transformer & potential transformer, we use for relay and protection purpose in electrical power system and in different instruments in industries are called instrument transformer.
Modified Bidirectional Converter with Current Fed InverterIJPEDS-IAES
A bidirectional dc-dc converter with multiple outputs are concatenated with a
high frequency current source parallel resonant push pull inverter is
presented in this paper. The two outputs are added together and it is taken as
the input source for the inverter. The current source parallel resonant push
pull inverter implemented here with high frequency applications like
induction heating, Fluorescent lighting, Digital signal processing sonar. This
paper proposes a simple photovoltaic power system consists of a
bidirectional converter and a current fed inverter for regulating the load
variations. Solar power is used as the input source for the system. Simulation
of the proposed system is carried out in PSIM software and experimentally
verified the results.
Modified Distribution Transformer for Enhancing Power Quality in Distribution...IAES-IJPEDS
The percentage of non-linear loads in the power distribution sector is increasing
day by day. Harmonics injected by these non-linear loads circulate in the delta
windings of the conventional distribution transformer thereby increasing the
temperature and losses. This reduces the efficiency and life of the transformers.
In a modified distribution transformer configuration proposed recently, called
star-star-delta_utilized configuration (YYD_utilized), the harmonics circulating
in the delta winding was utilized and the drainage power thus recovered was
used to power auxiliary loads. This paper presents the experimental studies
conducted on YYD_utilized distribution transformer. When compared to
conventional star-star, delta-star and star-star-delta transformers, the new
configuration of YYD_utilized transformer has shown considerable
improvement in transformer efficiency. The results obtained show that when
the power from the circulating harmonics is recovered and utilized, it not only
improves transformer efficiency but also improves the power factor
and reduces the harmonic distortions at the primary side of the transformer.
The results obtained also suggest the existence of maximum power point or an
optimum loading for the recovered harmonic power.
A ZVS Interleaved Boost AC/DC Converter Using Super Capacitor Power for Hybri...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
High Tension Current Transformer in Punebizproto26
We are recognized as a successful manufacturers, exporters and traders of Current Transformers. It is a static machine used for transforming power from one circuit to another without changing frequency. Current Transformers is generally used in transmission network which is normally known as power transformer, distribution transformer is used in distribution network and this is lower rating transformer and current transformer & potential transformer, we use for relay and protection purpose in electrical power system and in different instruments in industries are called instrument transformer.
Modified Bidirectional Converter with Current Fed InverterIJPEDS-IAES
A bidirectional dc-dc converter with multiple outputs are concatenated with a
high frequency current source parallel resonant push pull inverter is
presented in this paper. The two outputs are added together and it is taken as
the input source for the inverter. The current source parallel resonant push
pull inverter implemented here with high frequency applications like
induction heating, Fluorescent lighting, Digital signal processing sonar. This
paper proposes a simple photovoltaic power system consists of a
bidirectional converter and a current fed inverter for regulating the load
variations. Solar power is used as the input source for the system. Simulation
of the proposed system is carried out in PSIM software and experimentally
verified the results.
Modified Distribution Transformer for Enhancing Power Quality in Distribution...IAES-IJPEDS
The percentage of non-linear loads in the power distribution sector is increasing
day by day. Harmonics injected by these non-linear loads circulate in the delta
windings of the conventional distribution transformer thereby increasing the
temperature and losses. This reduces the efficiency and life of the transformers.
In a modified distribution transformer configuration proposed recently, called
star-star-delta_utilized configuration (YYD_utilized), the harmonics circulating
in the delta winding was utilized and the drainage power thus recovered was
used to power auxiliary loads. This paper presents the experimental studies
conducted on YYD_utilized distribution transformer. When compared to
conventional star-star, delta-star and star-star-delta transformers, the new
configuration of YYD_utilized transformer has shown considerable
improvement in transformer efficiency. The results obtained show that when
the power from the circulating harmonics is recovered and utilized, it not only
improves transformer efficiency but also improves the power factor
and reduces the harmonic distortions at the primary side of the transformer.
The results obtained also suggest the existence of maximum power point or an
optimum loading for the recovered harmonic power.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Hearing loss is one of the most common human impairments. It is estimated that by year 2015 more
than 700 million people will suffer mild deafness. Most can be helped by hearing aid devices depending on the
severity of their hearing loss. This paper describes the implementation and characterization details of a dual
channel transmitter front end (TFE) for digital hearing aid (DHA) applications that use novel micro
electromechanical- systems (MEMS) audio transducers and ultra-low power-scalable analog-to-digital
converters (ADCs), which enable a very-low form factor, energy-efficient implementation for next-generation
DHA. The contribution of the design is the implementation of the dual channel MEMS microphones and powerscalable
ADC system.
Development of Dual Frequency Alternator Technology Based Power Source For Mi...IDES Editor
This paper presents a Dual frequency alternator,
which generates power output at 50Hz and 400Hz. In weapon
system applications 50Hz and 400Hz power is required to meet
the requirement of different loads which operate at different
frequencies simultaneously. To cater power supply to these
loads either separate generators are required to be used or
50Hz and 400Hz power is obtained by solid-state conversion
using power converters. These separate power sources
increases the logistics, space requirement, maintenance,
repairs and overhauls. To overcome these difficulties special
kind of machine called Dual Frequency Alternator has been
designed to give power outputs of 50Hz and 400Hz frequencies
simultaneously with a single prime mover (Engine). In this
paper design, development and performance evaluation of the
Dual frequency output alternator along with integrated power
supply system is discussed. Experimental results are also
presented that demonstrate the high performance of Dual
frequency output Alternator technology for future Power
generation system.
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.
Performance and Analysis of Hybrid Multilevel Inverter fed Induction Motor Drivernvsubbarao koppineni
This paper presents the Five level inverter with single DC source which is used to generate a five level output with two bridges and six switches and performance of three phase induction motor is analyzed when connected to PV array For this two identical dc sources of 50V each for two bridges in five levels using Multi level inverter and five level output is obtained by using a single DC source of 100V with six switches. A virtual DC source (charged capacitor acts as virtual DC source) is used for getting the output. The same technique is implemented for three-phase circuit i.e. by using single DC source. An asynchronous motor (three-phase) is connected as load and its performance characteristics are analyzed. And further the DC source is replaced by a renewable resource such as solar panels, fuel cell etc. and DC voltage is obtained. Performance characteristics of three-phase asynchronous motor are analyzed with PV array connected. The method can be easily extended to an m-level inverter.
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 of Multilevel Inverter using Bipolar and Unipolar Switching Schemes ...ijsrd.com
Cascaded H-bridge Multilevel Inverter (MLI) is most efficient topology for medium and high voltage DC-AC conversion, having less output harmonics and less commutation losses. Disadvantages are their complexity, more number of power devices, passive components and a complex control circuitry. Here a Cascaded Hybrid Multilevel Inverter is used to produce a three phase 9-level output voltages. Now a day inverter is also know as a DC-AC converter, is one of the most popular part of electrical device. This proposed inverter widely used in industries application such as speed control of induction motor. This thesis focus on three phase 9-level bipolar and unipolar switching inverter with characteristics like output voltage boosting ability and also we discus about the bipolar and unipolar switching scheme along with capacitor voltage control. The modified topology uses Cascaded H-bridge (CHB) with bidirectional and unidirectional switches producing boost up output voltage. Here a hybrid Pulse Width Modulation (PWM) technique is applied to control the power devices. This modulation technique uses a sine wave and a repeating wave, these waves are combined and a complete reference wave is generated. There is comparative study between CHB and modified topology between number of power devices used and Total Harmonic Distortions (THD). THD of modified topology is reduced and analyzed by FFT window. The results are observed by MATLAB/SIMULINK software.
Active Power Exchange in Distributed Power-Flow Controller (DPFC) At Third Ha...IJERD Editor
This paper presents a component within the flexible ac-transmission system (FACTS) family, called
distributed power-flow controller (DPFC). The DPFC is derived from the unified power-flow controller (UPFC)
with an eliminated common dc link. The DPFC has the same control capabilities as the UPFC, which comprise
the adjustment of the line impedance, the transmission angle, and the bus voltage. The active power exchange
between the shunt and series converters, which is through the common dc link in the UPFC, is now through the
transmission lines at the third-harmonic frequency. DPFC multiple small-size single-phase converters which
reduces the cost of equipment, no voltage isolation between phases, increases redundancy and there by
reliability increases. The principle and analysis of the DPFC are presented in this paper and the corresponding
simulation results that are carried out on a scaled prototype are also shown.
Reduction of circulating current is one of the major considerations in inverter fed electrical drives. Diode clamped MLI enables higher output current per phase, thereby rating of the drive gets increased effectively. Various methods of triggering in the inverter legs creates better voltage profile and leads to the enabling of circulating current in the drive system. The induced circulating current flows through the apparatus neutral (N) and supply ground (G) is caused by the existence of parasitic capacitance. This circulating current may cause potential danger especially when parasitic capacitance poses large. In the past, different modulation techniques and conversion topologies have been introduced to minimize the flow of circulating current. However, these techniques lead to complexity, high cost, low voltage profile and efficiency due to lower modulation parameters. This paper proposes PS, POD, PD carrier shifting PWM algorithms for diode clamped MLI to tumbling the circulating current within the each phase of inverter legs. The performances of proposed algorithm, in terms of circulating current, THD, losses and efficiencies are analyzed theoreticallyand are validated via simulation and experimental results.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Hearing loss is one of the most common human impairments. It is estimated that by year 2015 more
than 700 million people will suffer mild deafness. Most can be helped by hearing aid devices depending on the
severity of their hearing loss. This paper describes the implementation and characterization details of a dual
channel transmitter front end (TFE) for digital hearing aid (DHA) applications that use novel micro
electromechanical- systems (MEMS) audio transducers and ultra-low power-scalable analog-to-digital
converters (ADCs), which enable a very-low form factor, energy-efficient implementation for next-generation
DHA. The contribution of the design is the implementation of the dual channel MEMS microphones and powerscalable
ADC system.
Development of Dual Frequency Alternator Technology Based Power Source For Mi...IDES Editor
This paper presents a Dual frequency alternator,
which generates power output at 50Hz and 400Hz. In weapon
system applications 50Hz and 400Hz power is required to meet
the requirement of different loads which operate at different
frequencies simultaneously. To cater power supply to these
loads either separate generators are required to be used or
50Hz and 400Hz power is obtained by solid-state conversion
using power converters. These separate power sources
increases the logistics, space requirement, maintenance,
repairs and overhauls. To overcome these difficulties special
kind of machine called Dual Frequency Alternator has been
designed to give power outputs of 50Hz and 400Hz frequencies
simultaneously with a single prime mover (Engine). In this
paper design, development and performance evaluation of the
Dual frequency output alternator along with integrated power
supply system is discussed. Experimental results are also
presented that demonstrate the high performance of Dual
frequency output Alternator technology for future Power
generation system.
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.
Performance and Analysis of Hybrid Multilevel Inverter fed Induction Motor Drivernvsubbarao koppineni
This paper presents the Five level inverter with single DC source which is used to generate a five level output with two bridges and six switches and performance of three phase induction motor is analyzed when connected to PV array For this two identical dc sources of 50V each for two bridges in five levels using Multi level inverter and five level output is obtained by using a single DC source of 100V with six switches. A virtual DC source (charged capacitor acts as virtual DC source) is used for getting the output. The same technique is implemented for three-phase circuit i.e. by using single DC source. An asynchronous motor (three-phase) is connected as load and its performance characteristics are analyzed. And further the DC source is replaced by a renewable resource such as solar panels, fuel cell etc. and DC voltage is obtained. Performance characteristics of three-phase asynchronous motor are analyzed with PV array connected. The method can be easily extended to an m-level inverter.
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 of Multilevel Inverter using Bipolar and Unipolar Switching Schemes ...ijsrd.com
Cascaded H-bridge Multilevel Inverter (MLI) is most efficient topology for medium and high voltage DC-AC conversion, having less output harmonics and less commutation losses. Disadvantages are their complexity, more number of power devices, passive components and a complex control circuitry. Here a Cascaded Hybrid Multilevel Inverter is used to produce a three phase 9-level output voltages. Now a day inverter is also know as a DC-AC converter, is one of the most popular part of electrical device. This proposed inverter widely used in industries application such as speed control of induction motor. This thesis focus on three phase 9-level bipolar and unipolar switching inverter with characteristics like output voltage boosting ability and also we discus about the bipolar and unipolar switching scheme along with capacitor voltage control. The modified topology uses Cascaded H-bridge (CHB) with bidirectional and unidirectional switches producing boost up output voltage. Here a hybrid Pulse Width Modulation (PWM) technique is applied to control the power devices. This modulation technique uses a sine wave and a repeating wave, these waves are combined and a complete reference wave is generated. There is comparative study between CHB and modified topology between number of power devices used and Total Harmonic Distortions (THD). THD of modified topology is reduced and analyzed by FFT window. The results are observed by MATLAB/SIMULINK software.
Active Power Exchange in Distributed Power-Flow Controller (DPFC) At Third Ha...IJERD Editor
This paper presents a component within the flexible ac-transmission system (FACTS) family, called
distributed power-flow controller (DPFC). The DPFC is derived from the unified power-flow controller (UPFC)
with an eliminated common dc link. The DPFC has the same control capabilities as the UPFC, which comprise
the adjustment of the line impedance, the transmission angle, and the bus voltage. The active power exchange
between the shunt and series converters, which is through the common dc link in the UPFC, is now through the
transmission lines at the third-harmonic frequency. DPFC multiple small-size single-phase converters which
reduces the cost of equipment, no voltage isolation between phases, increases redundancy and there by
reliability increases. The principle and analysis of the DPFC are presented in this paper and the corresponding
simulation results that are carried out on a scaled prototype are also shown.
Reduction of circulating current is one of the major considerations in inverter fed electrical drives. Diode clamped MLI enables higher output current per phase, thereby rating of the drive gets increased effectively. Various methods of triggering in the inverter legs creates better voltage profile and leads to the enabling of circulating current in the drive system. The induced circulating current flows through the apparatus neutral (N) and supply ground (G) is caused by the existence of parasitic capacitance. This circulating current may cause potential danger especially when parasitic capacitance poses large. In the past, different modulation techniques and conversion topologies have been introduced to minimize the flow of circulating current. However, these techniques lead to complexity, high cost, low voltage profile and efficiency due to lower modulation parameters. This paper proposes PS, POD, PD carrier shifting PWM algorithms for diode clamped MLI to tumbling the circulating current within the each phase of inverter legs. The performances of proposed algorithm, in terms of circulating current, THD, losses and efficiencies are analyzed theoreticallyand are validated via simulation and experimental results.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Proposed PV Transformer-Less Inverter Topology Technique for Leakage Current ...IJPEDS-IAES
Importance and demand of using renewable energy is dramatically escalated globally. Hence, the use of renewable energy is going to touch in peak. This demand is varying according to the site choosing. For instance, Wind is preferable where air is following highly as well as solar recommended place is high sun ray reducing places. Especially, the renewable system is highly recommended for electrification issues where it’s possible to produce the electricity for fulfilling rural and remote areas electricity problem. The photovoltaic (PV) panel of connecting with transformer based system is popular where some limitations are occurred especially cost and weight. In contrast, in this paper is focusing these issues where the transformer-less inverter system is used. Here will discuss some transformer-based and transformer-less inverter topologies and the leakage current issue which is occurred when transformer-less inverter system is used. Moreover, here is proposed a topology for reducing the leakage current after doing switching technique in both 50% and 75% duty cycle where output voltage remains quite same.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Interleaved Boost Converter Fed with PV for Induction Motor/Agricultural Appl...IAES-IJPEDS
In present Electricity market Renewable Energy Sources (RES) are gaining much importance. The most common Renewable Energy Sources are Photo voltaic (PV), fuel cell (FC) and wind energy systems, out of these three PV systems PV system can implemented in most of the locations. Due to the power cuts and power disturbances in Distribution systems agriculture application is concentrated on PV based Energy system. The use of PV system is increasing day by day in agriculture application, due to their ease of control and flexibility. PV Electrification schemes also involves various subsidies in government national and international donors. Especially in Agriculture field by use of PV one can achieve higher subsidy. The output of PV system is low voltage DC to have high efficiency. The motors used in agriculture field are Induction Motors (IM) fed from Three phase AC supply, to boost the PV output we need a high voltage gain boost converter along with PWM inverter to Induction motor drive. Out of various DC-DC converter configurations interleaved boost converter is gaining much attention, due to its reduction in size and Electromagnetic Interference (EMI). In this work we are proposing a PV fed interleaved boost converter with PWM inverter for agriculture applications. The design process of interleaved boost converter is explain detail and compared with existing boost converter. A 10 KW Power rating is choosing for the Induction motor drive and design calculations are carried out. A MATLAB/SIMULINK based model is developed for boost and interleaved boost converter and simulation results are presented, finally a scaled down hardware circuit design for interleaved boost converter and results are presented.
Report On diode clamp three level inverterVinay Singh
three level diode clamp inverter. that converts any type of DC ( rectified, PV cell, battery etc.) to AC supply. we made by mosfet and ardiuno . in this ppt we present the Simulink model of a three-level inverter and the hardware reort of the inverter.
also discuss about other level inverter and there THD analysis, simulink model and detail. compression between another inverter.
Performance Analysis of Current Controlled Three Phase Switched Reluctance Motoridescitation
Switched Reluctance Motor is an old member of Electrical Machines Family.It’s
simple structures and ruggedness and inexpensive manufacturing capability make it more
attractive for industrial application. However these merits are overshadowed by inherent
high torque ripple, acoustic noise and difficulty to control. In proposed converter, the
hysteresis
current control technique is applied
for analysis of three phase 6/4
Switched Reluctance motor. Using this technique ,torque, current, and flux linkage speed
curves of SRM are obtained at no load and load condition by MATLAB /SIMULINK.
Index Terms—
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdf
Economical stepper motor
1. Correspondence
ECONOMICAL STEPPER MOTORS FOR SPEED-CONTROL APPLICATIONS
Indexing terms: Stepping motors, Velocity control
Abstract: It is shown that automobile alternators can provide a low-cost alternative to a conventional stepper
motor in speed-control applications. Typical performance curves using a transistorised inverter are provided.
Introduction: Stepper motors are widely used in industry, Measured line voltages and line currents at different
and elsewhere, for two principal purposes;position control motor speeds are shown in Fig. 2. At low speeds the current
and speed control. To these ends a wide variety of motors waveform has the expected form while, at higher speeds,
differing in step size, speed, drop-out torque and cost have more distortion is present. As discussed by Tal3 this
been developed and marketed. In general the emphasis has constant-current excitation maximises the output power
been on higher resolution at the expense of speed and cost. for a given thermal dissipation in the motor. These wave-
Such motors are ideal for operating machine tools and forms, although distorted, are closer approximations to
other applications where an accurate position must be sinusoidal currents than square waves and give close to
maintained for some process time and then changed. optimal performance.
In many applications, however, these motors, while In practice, with a 25—40 V d.c. busbar, constant motor
suitable, are overdesigned for the purpose. For example, currents of 10 A can be achieved with d.c. busbar currents
in chemical plants a constant rate of flow through some of the order of 3—2 A when the motor is unloaded. At
positive-displacement pump requires a constant-speed higher loads the d.c. current and the maximum line current
motor. The step size is, in this case, largely irrelevant, and tend to become more equal. The exact ratio between these
significant savings in cost can readily be achieved using currents depends on the d.c. busbar voltage, the inverter
lower-resolution motors. Such motors are not usually switching speed and efficiency, the motor core and I2R
available from traditional stepper-motor sources, but losses, and the mechanical load.
automobile alternators have been found to be extremely Performance curves for a typical automobile alternator
useful and almost universally available. They are available used as a stepper motor driven with a constant current
with power ratings up to ~ 1 kW at much lower cost than transistorised inverter are shown in Fig. 3. In this case the
conventional stepper motors. maximum power output is 180 W at 1800 r/min. The motor
has a useful holding torque of 1 -3 Nm and a maximum
Description and results: Automobile alternators are usually speed of 2500 r/min. Higher d.c. busbar voltages are
star-connected 3-phase machines with, commonly, 8 or 12 effective in increasing the maximum speed and higher
poles giving 24 or 36 equivalent steps/revolution. To (constant) currents increase the holding torque.
modify an automobile alternator for use as a stepper motor
it is only necessary to disconnect the rectifier stack and d.c. busbar «•
connect a 3-phase inverter directly to the stator windings.
Rotor excitation is conveniently provided using the slip
rings on the machine. In explosion-critical environments
such external rotor excitation can be dispensed with by
replacing the rotor winding with toroidal permanent
magnets on a (new) nonmagnetic shaft.
A suitable inverter configuration is shown schematically ^® A
in Fig. 1. In essence this inverter is less complex than that
required for a 2- or 4-phase system, as it only requires three
'totem-pole' drivers. Following Nagasaka and Shinohara,1 current
constant current excitation has been used, but the select /control
implementation, in this case, is rather novel as it uses the
inductance of the motor in conjunction with the flywheel
diodes and transistors as a high-efficiency switching
regulator.
Transistors 1—6 are switched in the usual 'quasi-square-
wave' or '6-step' sequence described by Miller and
Lawrence.2 The three currents to the motor are monitored Fig. 1 Schematic diagram of transistorised inverter
using electronic ammeters / , , / 2 , and / 3 . The magnitude Transistors Tl — Tf are any suitable switching transistor (e.g. 2N305 5)
of the largest current is selected, and, if this magnitude is The diodes should be fast soft recovery types
above a predetermined level, the whole inverter is turned
off until the current drops to slightly below that level.
Switching the inverter off and on is accomplished by simply Conclusions: Automobile alternators are ' designed to
switching whichever of transistors 2, 4, or 6 are active in operate over a wide range of conditions in a very hostile en-
the 6-step sequence. The hysteresis in the current level at vironment. When they are used as stepping motors they
which switching occurs is chosen to ensure that the on/off still have these performance characteristics. Coupled with
switching rate is kept well into the ultrasonic area where it this ruggedness the lower cost of an automobile alternator
is not aurally objectionable. often means that a complete stepper-motor system (motor
ELECTRIC POWER APPLICATIONS, FEBRUARY 1979, Vol. 2, No. 1 27
0140-1327/79/010027 + 02 $01-50/0
2. plus inverter) can be made for less cost than the equivalent
stepping motor alone.
l200
500 1000 1500 2000 2500
speed, r/min
Fig. 3 Measured torque and power characteristics of a typical
automobile alternator type BOSCH 14 V, 35 A (G.M. part number
9929209)
Rotor excitation 2 A d.c., busbar voltage 40 V
Inverter constant current setting 7 A
J.T. BOYS 25th September 1978
Department of Electrical Engineering
University of Auckland
Auckland
New Zealand
G.R. DUNLOP
Department of Electrical Engineering
University of Canterbury
Christchurch
New Zealand
References
1 NAGASAKA, M., and SHINOHARA, K.: 'A study of large
capacity electric pulse motors', Electr. Eng. Jpn., 1974, 94, pp.
101-109
Fig. 2 Measured line voltages and line currents for a typical 2 MILLER, D.W., and LAWRENCE, R.G.: 'Variable-frequency
automobile alternator at different speeds inverter and its application to motor drives', Electron. & Power,
Upper 60 r/min. middle 300 r/min, lower 1200 r/min 1976, 22, pp. 675-678
The d.c. busbar is an unregulated supply of 40 V 3 TAL, J.: 'Control modes of step motors', IEEE Trans., 1977,
All current waveforms (upper traces) are 7 A peak AES-13, pp. 56-61
T284P
28 ELECTRIC POWER APPLICATIONS, FEBRUARY 1979, Vol. 2, No. I