This paper presents an analysis of a single-phase grid-connected photovoltaic inverter. It proposes a new transformerless inverter topology that utilizes two split ac-coupled inductors to operate separately for positive and negative half grid cycles, eliminating shoot-through issues. The topology is designed and analyzed using MATLAB/Simulink. Two modulation techniques, phase disposition PWM and sine PWM, are implemented and compared. Phase disposition PWM is shown to reduce the total harmonic distortion and common mode leakage current compared to sine PWM.
An Improved Single Phase Transformer less Inverter Topology for Cost Effecti...IJMER
In grid connected PV systems, the elimination of isolation transformer introduces common
mode leakage current due to the parasitic capacitance between PV panels and the ground. The common
mode leakage current reduces the efficiency of power conversion stage, affects the quality of grid
current, deteriorate the electric magnetic compatibility and give rise to various safety threats. In order
to eliminate the leakage current, an improved transformer less topology with virtual DC bus concept is
proposed here. By connecting the grid neutral line directly to the negative pole of the DC bus, the stray
capacitance between the PV panels and the ground is bypassed. The topology consists of only five power
switches, two capacitors and the filter section. Therefore, the power electronics cost can be curtailed.
This advanced topology can be modulated with the sinusoidal pulse width modulation (SPWM) to reduce
the output current ripple. The simulation result of the proposed topology using MATLAB/SIMULINK is
presented.
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.
Design and Simulation of Efficient DC-DC Converter Topology for a Solar PV Mo...Sajin Ismail
Modulated Integrated Converter systems are considered to be the new and global turning point in the field of
Solar PV systems. These converters are highly recognised for its modular size and compact nature and they are supposed to
be attached directly with each PV module and since one PV module is having the power rating of a few watts ranging from
0-500Ws, the design rating would be in the same range and thus the most vital condition in such a design is efficiency
under these relatively low loads. In this paper an isolated interleaved boost converter topology is considered in the DC-DC
section and which is designed and simulated for a specific power rating (250W) and the efficiency is analysed with varying
load conditions and compared with the target efficiency of the system.
Fuzzy based control of Transformer less Coupled inductor based DC-DC converterIJERA Editor
Most of the industrial applications use any one of the basic DC-DC converter configurations namely buck,
boost, buck–boost, and Cuk converters. These converters are non-isolating converters. Buck-boost converters
use inductors for storing energy from the source and release the same to load or output. This results in high
stress across magnetic components. This drawback restricts usage of buck-boost converters to low power
applications. Flyback converters popularly have known as buck-boost converters uses transformers for
achieving wide range of step down and step up voltages. Coupled inductor based converters or tapped inductor
based converters are used for achieving wide input – wide output conversion ratios. Coherent transition between
step-down and step-up modes is achieved by a proper control scheme. This paper proposes fuzzy logic based
closed loop control scheme for control of converter switches. Theoretical derivations of control parameters with
their membership values, mamdani based rules for development of fuzzy rules and simulation results of a
coupled inductor based DC-DC converter using MATLAB / SIMULINK are concluded.
An Improved Single Phase Transformer less Inverter Topology for Cost Effecti...IJMER
In grid connected PV systems, the elimination of isolation transformer introduces common
mode leakage current due to the parasitic capacitance between PV panels and the ground. The common
mode leakage current reduces the efficiency of power conversion stage, affects the quality of grid
current, deteriorate the electric magnetic compatibility and give rise to various safety threats. In order
to eliminate the leakage current, an improved transformer less topology with virtual DC bus concept is
proposed here. By connecting the grid neutral line directly to the negative pole of the DC bus, the stray
capacitance between the PV panels and the ground is bypassed. The topology consists of only five power
switches, two capacitors and the filter section. Therefore, the power electronics cost can be curtailed.
This advanced topology can be modulated with the sinusoidal pulse width modulation (SPWM) to reduce
the output current ripple. The simulation result of the proposed topology using MATLAB/SIMULINK is
presented.
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.
Design and Simulation of Efficient DC-DC Converter Topology for a Solar PV Mo...Sajin Ismail
Modulated Integrated Converter systems are considered to be the new and global turning point in the field of
Solar PV systems. These converters are highly recognised for its modular size and compact nature and they are supposed to
be attached directly with each PV module and since one PV module is having the power rating of a few watts ranging from
0-500Ws, the design rating would be in the same range and thus the most vital condition in such a design is efficiency
under these relatively low loads. In this paper an isolated interleaved boost converter topology is considered in the DC-DC
section and which is designed and simulated for a specific power rating (250W) and the efficiency is analysed with varying
load conditions and compared with the target efficiency of the system.
Fuzzy based control of Transformer less Coupled inductor based DC-DC converterIJERA Editor
Most of the industrial applications use any one of the basic DC-DC converter configurations namely buck,
boost, buck–boost, and Cuk converters. These converters are non-isolating converters. Buck-boost converters
use inductors for storing energy from the source and release the same to load or output. This results in high
stress across magnetic components. This drawback restricts usage of buck-boost converters to low power
applications. Flyback converters popularly have known as buck-boost converters uses transformers for
achieving wide range of step down and step up voltages. Coupled inductor based converters or tapped inductor
based converters are used for achieving wide input – wide output conversion ratios. Coherent transition between
step-down and step-up modes is achieved by a proper control scheme. This paper proposes fuzzy logic based
closed loop control scheme for control of converter switches. Theoretical derivations of control parameters with
their membership values, mamdani based rules for development of fuzzy rules and simulation results of a
coupled inductor based DC-DC converter using MATLAB / SIMULINK are concluded.
Grid tied photovoltaic (PV) system is an operation mode of PV system working together with utility power supply to provide power to the power load. Conventionally, transformer is used together with the power inverter. The power transformer works as galvanic insolation amongst PV system and power grid. It works also to raise the voltage of power inverter. However, use of transformer will add system complexity, price, weight and size of the entire system. Transformer-less system is an alternative to make the system simpler and more practical in use. The paper discusses performance of transformer-less grid tied PV systems using diode clamped and neutral point shorted inverters. Effects of transformer elimination to the feat of the grid tied PV system especially harmonics content and leakage current of PV system were examined and analyzed. The performance was also compared with the traditional system using H-bridge inverter. The leakage currents did not flow in the system applying diode clamped inverter, and neutral point shorted inverter. In case of harmonics content, the diode clamped inverter injected less harmonics components than the neutral point shorted inverter. The neutral point shorted provides a simpler inverter circuit in the transformerless systems.
The voltage source inverters (VSI) are ever required section in the AC motor drive and power system interface. The electrical drive segment, the VSI based drives are unavoidable and they are closely operated with induction motor, permanent magnate synchronous motor and BLDC motor. These drives are normally needed high torque-power characters. Hence, the input DC-link side voltage is increased with help of increasing input AC in the rectifier input. However, this causes the power quality disturbance in the AC main and DC-link. In order to go for a increasing the AC voltage, the rectifier out is connected with DC to DC boost converter and they are increasing the DC voltage to meet out the drive DC-link voltage demand. With this aim, the paper proposes the idea to connect high step non-isolated high gain coupled DC to DC converter with three phase VSI for drives applications. The proposed converter has an ability to increase the voltage five times and the counter winding arrangement ratio of the converter is help for the further increase of gain. Inn this interface the front end DC to DC converters inductors are charged by making the short circuit with inverter switching. The converter voltage gain is controlled by shoot through of the VSI switch (converter gain directly proportional to inverter shoot through). The proposed converter has a higher degree of freedom in their values of winding and output voltage. Hence, the DC-link voltage of the inverter can be extended in any level. The operation principle and modes of the proposed DC to DC Source tied VSI is analyzed and simulated using MATLAB-Simulink software simulation. The laboratory based small scale power circuit is developed with help of control algorithm. The entire implementation is done through PIC microcontroller platform. The deign Investigation, system simulation and experimentation confirming the proposed DC to DC converter tied VSI drive system.
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.
High Proficiency Grid ConnectedPhotovoltaic Power Generation SystemIJRES Journal
Solar energy hasbecomepopular nowadays and desire for clean energy. Since the solar radiation on no occasion remains constant,it keeps on insecure throughout the day. The need of the hour is to distribute a constant voltage to the grid irrespective of the deviation in temperatures and solar insolation. The inverter is designed from a boost converter along with a line frequency. The voltage from the boost converter is fedto the grid through inverter. In this proposed method high efficiency can be achievedby using only one switch functioning at high frequency at a time. The converter uses IGBT and ultra-fast reverse recovery diode. The simulation and experiment results are verified using MATLAB/Simulink software.
Solid-State Transformer (S2T) also known as Power Electronic Transformer (PET) is applied in various industrial fields compared to the conventional transformer due to it flexible voltage transfer ratio, high power density, and low harmonic distortion. This paper presents the S2T of Single Phase Matrix Converter (SPMC) that acts as cyclo-converter. A 1kHz frequency was synthesized on the primary side of the transformer using Pulse Width Modulation (PWM) technique, whilst, the output converted by the SPMC that produces the 50Hz frequency. A part of AC to AC operation, the switching algorithm for safe-commutation technique is also presented to solve the commutation problem caused by the usage of inductive load. Minimization of size, losses and optimal efficiency are the advantages of this approach. The proposed model was simulated by using MATLAB/Simulink (MLS).
An Asymmetrical Dc-Dc Converter with a High Voltage GainIJMER
An asymmetrical full bridge converter is proposed in the paper. The proposed converter
achieves zero voltage switching of all the power switches. Zero current switching of all the output diodes
are also achieved here. This in turn provides a highly efficienct operation. The proposed converter can
provide a high voltage gain and the voltages across the semi- conductor devices are effectively clamped.
The converter can be utilised effectively in high voltage applications as embedded systems, renewable
energy systems, fuel cells, mobility applications and uninterrupted power supply
Multilevel DC Link Inverter with Reduced Switches and BatteriesIJPEDS-IAES
Multilevel inverters are the best solution for medium and high voltage power electronic drives. Because of its unique characteristic of synthesizing sinusoidal voltage with less harmonic contents using several DC sources. In a three phase multilevel inverter, each phase of a cascaded H-bridge inverter requires ‘n’ DC sources to obtain 2n + 1 output voltage levels. One particular disadvantage is that, it increases number of power semiconductor switches. To overcome this disadvantage a multilevel DC link inverter (MLDCLI) with reduced number of switches and batteries is proposed.
Basic MOSFET Based vs Couple-Coils Boost Converters for Photovoltaic GeneratorsIJPEDS-IAES
Considering the optimization of a photovoltaic system, several studies show the advantage in the choice of a distributed structure. For such structures small power converters such as the boosts and buck converters appear as most appropriate. We have analysed the efficiency of small power boost- converters especially dedicated for photovoltaic energy conversion systems working in the middle and high voltage ranges. The setup studied is a photovoltaic generator connected to an AC grid working in 230 Volts via an inverter. Moreover, we considered the possibility of multiple electrical energy sources as photovoltaic, wind systems in the same energy production system, which obliged an adaptive converter structure. We evaluated the losses in the various stages of a boost converter and point out the importance of the power MOSFET used as the commutation element. New transistors databases obtained from manufacturers show the nonlinear dependency between the resistance drain-source when passing, Rdson and the maximum rating voltage when the transistor is off, Vdsmax, for all transistor families. Thus nonlinear dependency induces a huge increase of losses with the voltage in the MOSFET, and as a direct consequence in the converter the more as Vdsmax is higher. In order to minimize losses of the converter we have designed and realized a new high efficiency version of a Step-Up structure based on a commutation element integrating a low Vdsmax voltage MOSFET and very low Rdson.
Research Inventy : International Journal of Engineering and Scienceinventy
Research Inventy : International Journal of Engineering and Science
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed
This work highlights a modular power conditioning system (PCS) in photovoltaic (PV) applications which consists with a DC-DC converter. The converter is able to regulate and amplify the input DC voltage produced by the PV panal. The implementation of Mosfet as bidirectional switch on the converter yields greater conversion ratio and better voltage regulation than a conventional DC-DC step up converter and PWM resonant converter. It also reduces the switching losses on the output DC voltage of the converter, as the MOSFET switches on primary winding of converter switch on under ZVS conditions. The proposed resonant converter has been designed, with the modification of series resonant converter and PWM boost converter that utilizes the high frequency of AC bidirectional switch to eliminate the weaknesses of used converters. The topology of the proposed converter includes the mode of operations, designing procedure and components selection of the new converter elements. This topology provides a DC output voltage to the inverter at range of about 120Vac-208 Vac.
An inclination towards renewable energy resources has been increased due to the requirement of clean environment and to satisfy the increasing power demand for the long run. A grid connected system requires the availability of a transformer in its power conversion stages that provides galvanic isolation between the grid and the power system. But inclusion of transformer results in making the system bulky and more expensive. In this paper different transformer-less PV inverter topologies are analyzed by comparing their efficiency, leakage current and THD of load current using MATLAB/Simulink environment. In order to achieve maximum power, maximum power point tracking (P&O algorithm) is used. From the simulation results, modified HB-ZVR is found to have minimum leakage current and constant common mode voltage with higher efficiency. Also, the hardware results are obtained for modified HB-ZVR topology.
Grid tied photovoltaic (PV) system is an operation mode of PV system working together with utility power supply to provide power to the power load. Conventionally, transformer is used together with the power inverter. The power transformer works as galvanic insolation amongst PV system and power grid. It works also to raise the voltage of power inverter. However, use of transformer will add system complexity, price, weight and size of the entire system. Transformer-less system is an alternative to make the system simpler and more practical in use. The paper discusses performance of transformer-less grid tied PV systems using diode clamped and neutral point shorted inverters. Effects of transformer elimination to the feat of the grid tied PV system especially harmonics content and leakage current of PV system were examined and analyzed. The performance was also compared with the traditional system using H-bridge inverter. The leakage currents did not flow in the system applying diode clamped inverter, and neutral point shorted inverter. In case of harmonics content, the diode clamped inverter injected less harmonics components than the neutral point shorted inverter. The neutral point shorted provides a simpler inverter circuit in the transformerless systems.
The voltage source inverters (VSI) are ever required section in the AC motor drive and power system interface. The electrical drive segment, the VSI based drives are unavoidable and they are closely operated with induction motor, permanent magnate synchronous motor and BLDC motor. These drives are normally needed high torque-power characters. Hence, the input DC-link side voltage is increased with help of increasing input AC in the rectifier input. However, this causes the power quality disturbance in the AC main and DC-link. In order to go for a increasing the AC voltage, the rectifier out is connected with DC to DC boost converter and they are increasing the DC voltage to meet out the drive DC-link voltage demand. With this aim, the paper proposes the idea to connect high step non-isolated high gain coupled DC to DC converter with three phase VSI for drives applications. The proposed converter has an ability to increase the voltage five times and the counter winding arrangement ratio of the converter is help for the further increase of gain. Inn this interface the front end DC to DC converters inductors are charged by making the short circuit with inverter switching. The converter voltage gain is controlled by shoot through of the VSI switch (converter gain directly proportional to inverter shoot through). The proposed converter has a higher degree of freedom in their values of winding and output voltage. Hence, the DC-link voltage of the inverter can be extended in any level. The operation principle and modes of the proposed DC to DC Source tied VSI is analyzed and simulated using MATLAB-Simulink software simulation. The laboratory based small scale power circuit is developed with help of control algorithm. The entire implementation is done through PIC microcontroller platform. The deign Investigation, system simulation and experimentation confirming the proposed DC to DC converter tied VSI drive system.
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.
High Proficiency Grid ConnectedPhotovoltaic Power Generation SystemIJRES Journal
Solar energy hasbecomepopular nowadays and desire for clean energy. Since the solar radiation on no occasion remains constant,it keeps on insecure throughout the day. The need of the hour is to distribute a constant voltage to the grid irrespective of the deviation in temperatures and solar insolation. The inverter is designed from a boost converter along with a line frequency. The voltage from the boost converter is fedto the grid through inverter. In this proposed method high efficiency can be achievedby using only one switch functioning at high frequency at a time. The converter uses IGBT and ultra-fast reverse recovery diode. The simulation and experiment results are verified using MATLAB/Simulink software.
Solid-State Transformer (S2T) also known as Power Electronic Transformer (PET) is applied in various industrial fields compared to the conventional transformer due to it flexible voltage transfer ratio, high power density, and low harmonic distortion. This paper presents the S2T of Single Phase Matrix Converter (SPMC) that acts as cyclo-converter. A 1kHz frequency was synthesized on the primary side of the transformer using Pulse Width Modulation (PWM) technique, whilst, the output converted by the SPMC that produces the 50Hz frequency. A part of AC to AC operation, the switching algorithm for safe-commutation technique is also presented to solve the commutation problem caused by the usage of inductive load. Minimization of size, losses and optimal efficiency are the advantages of this approach. The proposed model was simulated by using MATLAB/Simulink (MLS).
An Asymmetrical Dc-Dc Converter with a High Voltage GainIJMER
An asymmetrical full bridge converter is proposed in the paper. The proposed converter
achieves zero voltage switching of all the power switches. Zero current switching of all the output diodes
are also achieved here. This in turn provides a highly efficienct operation. The proposed converter can
provide a high voltage gain and the voltages across the semi- conductor devices are effectively clamped.
The converter can be utilised effectively in high voltage applications as embedded systems, renewable
energy systems, fuel cells, mobility applications and uninterrupted power supply
Multilevel DC Link Inverter with Reduced Switches and BatteriesIJPEDS-IAES
Multilevel inverters are the best solution for medium and high voltage power electronic drives. Because of its unique characteristic of synthesizing sinusoidal voltage with less harmonic contents using several DC sources. In a three phase multilevel inverter, each phase of a cascaded H-bridge inverter requires ‘n’ DC sources to obtain 2n + 1 output voltage levels. One particular disadvantage is that, it increases number of power semiconductor switches. To overcome this disadvantage a multilevel DC link inverter (MLDCLI) with reduced number of switches and batteries is proposed.
Basic MOSFET Based vs Couple-Coils Boost Converters for Photovoltaic GeneratorsIJPEDS-IAES
Considering the optimization of a photovoltaic system, several studies show the advantage in the choice of a distributed structure. For such structures small power converters such as the boosts and buck converters appear as most appropriate. We have analysed the efficiency of small power boost- converters especially dedicated for photovoltaic energy conversion systems working in the middle and high voltage ranges. The setup studied is a photovoltaic generator connected to an AC grid working in 230 Volts via an inverter. Moreover, we considered the possibility of multiple electrical energy sources as photovoltaic, wind systems in the same energy production system, which obliged an adaptive converter structure. We evaluated the losses in the various stages of a boost converter and point out the importance of the power MOSFET used as the commutation element. New transistors databases obtained from manufacturers show the nonlinear dependency between the resistance drain-source when passing, Rdson and the maximum rating voltage when the transistor is off, Vdsmax, for all transistor families. Thus nonlinear dependency induces a huge increase of losses with the voltage in the MOSFET, and as a direct consequence in the converter the more as Vdsmax is higher. In order to minimize losses of the converter we have designed and realized a new high efficiency version of a Step-Up structure based on a commutation element integrating a low Vdsmax voltage MOSFET and very low Rdson.
Research Inventy : International Journal of Engineering and Scienceinventy
Research Inventy : International Journal of Engineering and Science
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed
This work highlights a modular power conditioning system (PCS) in photovoltaic (PV) applications which consists with a DC-DC converter. The converter is able to regulate and amplify the input DC voltage produced by the PV panal. The implementation of Mosfet as bidirectional switch on the converter yields greater conversion ratio and better voltage regulation than a conventional DC-DC step up converter and PWM resonant converter. It also reduces the switching losses on the output DC voltage of the converter, as the MOSFET switches on primary winding of converter switch on under ZVS conditions. The proposed resonant converter has been designed, with the modification of series resonant converter and PWM boost converter that utilizes the high frequency of AC bidirectional switch to eliminate the weaknesses of used converters. The topology of the proposed converter includes the mode of operations, designing procedure and components selection of the new converter elements. This topology provides a DC output voltage to the inverter at range of about 120Vac-208 Vac.
An inclination towards renewable energy resources has been increased due to the requirement of clean environment and to satisfy the increasing power demand for the long run. A grid connected system requires the availability of a transformer in its power conversion stages that provides galvanic isolation between the grid and the power system. But inclusion of transformer results in making the system bulky and more expensive. In this paper different transformer-less PV inverter topologies are analyzed by comparing their efficiency, leakage current and THD of load current using MATLAB/Simulink environment. In order to achieve maximum power, maximum power point tracking (P&O algorithm) is used. From the simulation results, modified HB-ZVR is found to have minimum leakage current and constant common mode voltage with higher efficiency. Also, the hardware results are obtained for modified HB-ZVR topology.
Universal demand for power increases due to continuous development to fulfil all these demand. Resources
are used with optimization. A high efficiency and high power factor converters are the major parts of energy
transfer system. This paper present a general review on single stage forward and flyback converter topologies to get
better its performance. This is paper presents a kind general idea of increasing efficiency and power factor of single
stage forward and fly back converter.
Performance numerical evaluation of modified single-ended primary-inductor c...IJECEIAES
Single-ended primary-inductor converter (SEPIC) was considered a good alternative to a DC-DC converter for photovoltaic (PV) systems. The SEPIC converter can operate with an input voltage greater or less than the regulated output voltage, or as a step-up or step-down. As a step-up converter, SEPIC boosts PV voltage to specific levels. However, gain limitation and voltage stress continue to reduce the efficiency of conventional SEPIC converters. Because of this, researchers created a modified SEPIC converter to improve performance. In this paper, six modified SEPIC converters were compared and evaluated. To compare fairly, all modified SEPIC converters are nonisolated and use a single switch. Power simulator (PSIM) software was used to simulate each converter with a BISOL BMO-250 PV module and maximum power point tracking (MPPT) P&O controller. The converter with the highest static voltage gain and lowest duty cycle has been identified. It results in up to ten times voltage increment with a 0.8-duty ratio. All topologies have the same voltage stress, with maximum and minimum values of 30.1 and 29.5 V, respectively. On the other hand, each topology produces different average efficiencies, with the highest and lowest efficiency at 99.5% and 97.2%, respectively.
High Reliability and Efficiency Single phase Transformerless Inverter for Gri...Anoop kumar Niravuparambil
TODAY, the energy demand is increasing due to the rapid increase of the human population and fast-growing industries. Hence, renewable energy plays an important role to replace traditional natural resources such as fuel and coal. Photovoltaic (PV) energy has recently become a common interest of research because it is free, green, and inexhaustible.
Generally, there are two types of grid-connected PV systems, i.e., those with transformer and without transformer. Besides stepping up the voltage, it plays an important role in safety purpose by providing galvanic isolation, and thus eliminating leakage current and avoiding dc current injection into the grid. Nevertheless, the transformers are bulky, heavy, and expensive. Even though significant size, weight and reduces the efficiency of the entire PV system. Hence, transformerless PV systems are introduced to overcome these issues. They are smaller, lighter, lower in cost, and highly efficient
However, safety issue is the main concern for the transformerless PV systems due to high leakage current. Without galvanic isolation, a direct path can be formed for the leakage current to flow from the PV to the grid. At the same time, the fluctuating potential, also known as common-mode voltage (CMV), charges and discharges the stray capacitance which generates high leakage current. This will introduce losses in the PV system. There are many methods available for reducing this leakage current. Here are some inverter topologies are proposed, in-order to achieve High efficiency for the grid connected photovoltaic system
Hysteresis SVM for Coupled Inductor Z Source Diode Clamped 3-Level Inverter B...IAES-IJPEDS
Due to its advantages such as it can defeat problems such as leakage current
and insertion of DC in the grid and provides low stress on power devices,
Diode-clamped three-level inverter (DCTLI) is habitually used in
transformerless photovoltaic (PV) connected to grid network. But it still has
a problem of shoot-through which dwells in its legs, so its operation not
reliable. Z source network is employed to permit operation without shoot
through risk and improve its reliability. Coupled inductors are replaced the
line transformers in to attain lower cost, reduced size, and improved its
reliability and efficiency. Coupled inductor which avoids leakage current
problem and losses. It employs coupled inductor z source diode clamped
three level inverter (CI-Z-DC-TLI) to boost the voltage and further progress
the consistency of the proposed system by avoiding the shoot through the
problem. The proposed system assures that common-mode voltage
and shoot-through risk is avoided. Moreover, controlling DC-TLI with
Hysteresis SVM algorithm which improves output voltage and current
control. Simulation and experimental results of this proposed system were
analyzed using MATLAB environment and FPGA hardware.
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.
High gain dc-dc step up converters have been used in renewable energy systems, for example, photovoltaic grid connected system and fuel cell power plant to step up the low level dc voltage to a high level dc bus voltage. If the conventional boost converter is to meet this demand, it should be operated at an extreme duty cycle (duty cycle closes to unity), which will cause electromagnetic interference, reverse recovery problem and conduction loss at the power switches. This paper proposes a class of non-isolated dc-dc step up converters which provide very high voltage gain at a small duty cycle (duty cycle < 0.5). Firstly, the converter topologies are derived based on active switched inductor network and combination of active and passive switched inductor networks; secondly, the modes of operation of proposed active switched inductor converter and combined active and passive switched inductor converter are illustrated; thirdly, the performance of the proposed converters are analyzed mathematically in details and compared with conventional boost converter. Finally, the analysis is verified by simulation results.
Transformerless Topology for Grid-Conected Inverters With Unipolar PWM ControlIJERA Editor
Most of the PV systems are designed with transformer for safety purpose with galvanic isolation. However, the transformer is big, heavy and expensive. Also, it reduces the overall frequency of the conversion stage. Generally PV inverter with transformer is having good efficiency. To overcome these problems, transformer less PV system is introduced. It is smaller, lighter, cheaper and higher in efficiency. However, dangerous leakage current will flow between PV array and the grid due to the stray capacitance. There are different types of configurations available for transformer less inverters like H5, H6, HERIC, and Dual paralleled buck inverter. But each configuration is suffering from its own disadvantages like high conduction losses, shoot-through issues of switches, dead-time requirements at zero crossing instants of grid voltage to avoid grid shoot-through faults and MOSFET reverse recovery issues. The main objective of the proposed transformer less inverter is to address two key issues: One key issue for a transformer less inverter is that it is necessary to achieve high efficiency compared to other existing inverter topologies. Another key issue is that the inverter configuration should not have any shoot-through issues for higher reliability.
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An Heterogeneous Population-Based Genetic Algorithm for Data Clusteringijeei-iaes
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Development of a Wireless Sensors Network for Greenhouse Monitoring and Controlijeei-iaes
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Analysis of Genetic Algorithm for Effective power Delivery and with Best Upsurgeijeei-iaes
Wireless network is ready for hundreds or thousands of nodes, where each node is connected to one or sometimes more sensors. WSN sensor integrated circuits, embedded systems, networks, modems, wireless communication and dissemination of information. The sensor may be an obligation to technology and science. Recent developments underway to miniaturization and low power consumption. They act as a gateway, and prospective clients, I usually have the data on the server WSN. Other components separate routing network routers, called calculating and distributing routing tables. Discussed the routing of wireless energy balance. Optimization solutions, we have created a genetic algorithm. Before selecting an algorithm proposed for the construction of the center console. In this study, the algorithms proposed model simulated results based on "parameters depending dead nodes, the number of bits transmitted to a base station, where the number of units sent to the heads of fuel consumption compared to replay and show that the proposed algorithm has a network of a relative.
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Optimal Power Flow with Reactive Power Compensation for Cost And Loss Minimiz...ijeei-iaes
One of the concerns of power system planners is the problem of optimum cost of generation as well as loss minimization on the grid system. This issue can be addressed in a number of ways; one of such ways is the use of reactive power support (shunt capacitor compensation). This paper used the method of shunt capacitor placement for cost and transmission loss minimization on Nigerian power grid system which is a 24-bus, 330kV network interconnecting four thermal generating stations (Sapele, Delta, Afam and Egbin) and three hydro stations to various load points. Simulation in MATLAB was performed on the Nigerian 330kV transmission grid system. The technique employed was based on the optimal power flow formulations using Newton-Raphson iterative method for the load flow analysis of the grid system. The results show that when shunt capacitor was employed as the inequality constraints on the power system, there is a reduction in the total cost of generation accompanied with reduction in the total system losses with a significant improvement in the system voltage profile
Mitigation of Power Quality Problems Using Custom Power Devices: A Reviewijeei-iaes
Electrical power quality (EPQ) in distribution systems is a critical issue for commercial, industrial and residential applications. The new concept of advanced power electronic based Custom Power Devices (CPDs) mainly distributed static synchronous compensator (D-STATCOM), dynamic voltage restorer (DVR) and unified power quality conditioner (UPQC) have been developed due to lacking the performance of traditional compensating devices to minimize power quality disturbances. This paper presents a comprehensive review on D-STATCOM, DVR and UPQC to solve the electrical power quality problems of the distribution networks. This is intended to present a broad overview of the various possible DSTATCOM, DVR and UPQC configurations for single-phase (two wire) and three-phase (three-wire and four-wire) networks and control strategies for the compensation of various power quality disturbances. Apart from this, comprehensive explanation, comparison, and discussion on D-STATCOM, DVR, and UPQC are presented. This paper is aimed to explore a broad prospective on the status of D-STATCOMs, DVRs, and UPQCs to researchers, engineers and the community dealing with the power quality enhancement. A classified list of some latest research publications on the topic is also appended for a quick reference.
Comparison of Dynamic Stability Response of A SMIB with PI and Fuzzy Controll...ijeei-iaes
Consumer utilities are non –linear in nature. This injects increased flow of current and reduced voltage with distortions which cause adverse effect on the stability of consumer utilities. To overcome this problem we are using a modern Flexible Alternating Current Transmission System controller i.e. distributed power flow controller (DPFC). This controller is similar to UPFC, which can be installed in a transmission line between the two electrical areas. In DPFC, instead of the common Dc link capacitor three single phase converters are used. In this paper we are concentrating on system stability (oscillation damping). For analyzing the stability of a single machine infinite bus system (SMIB) we have used PI controlled Distributed Power Flow Controller (DPFC) and Fuzzy controlled DPFC. All these models are simulated using MATLAB/SIMULINK. Simulation results shows Fuzzy controlled DPFC are better than PI controlled DPFC. The significance of the results are better stability and constant power supply.
Embellished Particle Swarm Optimization Algorithm for Solving Reactive Power ...ijeei-iaes
This paper proposes Embellished Particle Swarm Optimization (EPSO) algorithm for solving reactive power problem .The main concept of Embellished Particle Swarm Optimization is to extend the single population PSO to the interacting multi-swarm model. Through this multi-swarm cooperative approach, diversity in the whole swarm community can be upheld. Concurrently, the swarm-to-swarm mechanism drastically speeds up the swarm community to converge to the global near optimum. In order to evaluate the performance of the proposed algorithm, it has been tested in standard IEEE 57,118 bus systems and results show that Embellished Particle Swarm Optimization (EPSO) is more efficient in reducing the Real power losses when compared to other standard reported algorithms.
Intelligent Management on the Home Consumers with Zero Energy Consumptionijeei-iaes
The energy and environment crisis has forced modern humans to think about new and clean energy sources and in particular, renewable energy sources. With the development of home network, the residents have the opportunity to plan the home electricity usage with the goal of reducing the cost of electricity. In this regard, to improve the energy consumption efficiency in residential buildings, smart buildings with zero energy consumption were considered as a proper option. Zero-energy building is a building that has smart equipment whose integral of generated and consumed power within a year is zero. In this article, smart devices submit their power consumption with regard to the requested activity associated with the user’s time setting for run times and end times of the work to the energy management unit and ultimately the time to start work will be determined. The problem’s target function is reducing the energy cost for the consumer with taking into account the applicable limitations.
Analysing Transportation Data with Open Source Big Data Analytic Toolsijeei-iaes
Big data analytics allows a vast amount of structured and unstructured data to be effectively processed so that correlations, hidden patterns, and other useful information can be mined from the data. Several open source big data analytic tools that can perform tasks such as dimensionality reduction, feature extraction, transformation, optimization, are now available. One interesting area where such tools can provide effective solutions is transportation. Big data analytics can be used to efficiently manage transport infrastructure assets such as roads, airports, bus stations or ports. In this paper an overview of two open source big data analytic tools is first provided followed by a simple demonstration of application of these tools on transport dataset.
A Pattern Classification Based approach for Blur Classificationijeei-iaes
Blur type identification is one of the most crucial step of image restoration. In case of blind restoration of such images, it is generally assumed that the blur type is known prior to restoration of such images. However, it is not practical in real applications. So, blur type identification is extremely desirable before application of blind restoration technique to restore a blurred image. An approach to categorize blur in three classes namely motion, defocus, and combined blur is presented in this paper. Curvelet transform based energy features are utilized as features of blur patterns and a neural network is designed for classification. The simulation results show preciseness of proposed approach.
Computing Some Degree-Based Topological Indices of Grapheneijeei-iaes
Graphene is one of the most promising nanomaterial because of its unique combination of superb properties, which opens a way for its exploitation in a wide spectrum of applications ranging from electronics to optics, sensors, and bio devices. Inspired by recent work on Graphene of computing topological indices, here we compute new topological indices viz. Arithmetic-Geometric index (AG2 index), SK3 index and Sanskruti index of a molecular graph G and obtain the explicit formulae of these indices for Graphene.
A Lyapunov Based Approach to Enchance Wind Turbine Stabilityijeei-iaes
This paper introduces a nonlinear control of a wind turbine based on a Double Feed Induction Generator. The Rotor Side converter is controlled by using field oriented control and Backstepping strategy to enhance the dynamic stability response. The Grid Side converter is controlled by a sliding mode. These methods aim to increase dynamic system stability for variable wind speed. Hence, The Doubly Fed Induction Generator (DFIG) is studied in order to illustrate its behavior in case of severe disturbance, and its dynamic response in grid connected mode for variable speed wind operation. The model is presented and simulated under Matlab/ Simulink.
Fuzzy Control of a Large Crane Structureijeei-iaes
The usage of tower cranes, one type of rotary cranes, is common in many industrial structures, e.g., shipyards, factories, etc. With the size of these cranes becoming larger and the motion expected to be faster and has no prescribed path, their manual operation becomes difficult and hence, automatic closed-loop control schemes are very important in the operation of rotary crane. In this paper, the plant of concern is a tower crane consists of a rotatable jib that carries a trolley which is capable of traveling over the length of the jib. There is a pendulum-like end line attached to the trolley through a cable of variable length. A fuzzy logic controller with various types of membership functions is implemented for controlling the position of the trolley and damping the load oscillations. It consists of two main types of controllers radial and rotational each of two fuzzy inference engines (FIEs). The radial controller is used to control the trolley position and the rotational is used for damping the load oscillations. Computer simulations are used to verify the performance of the controller. The results from the simulations show the effectiveness of the method in the control of tower crane keeping load swings small at the end of motion.
Site Diversity Technique Application on Rain Attenuation for Lagosijeei-iaes
This paper studied the impact of site diversity (SD) as a fade mitigation technique on rain attenuation at 12 GHz for Lagos. SD is one of the most effective methods to overcome such large fades due to rain attenuation that takes advantage of the usually localized nature of intense rainfall by receiving the satellite downlink signal at two or more earth stations to minimize the prospect of potential diversity stations being simultaneously subjected to significant rain attenuation. One year (January to December 2011) hourly rain gauge data was sourced from the Nigerian Meteorological Agency (NIMET) for three sites (Ikeja, Ikorodu and Marina) in Lagos, Nigeria. Significant improvement in both performance and availability was observed with the application of SD technique; again, separation distance was seen to be responsible for this observed performance improvements.
Impact of Next Generation Cognitive Radio Network on the Wireless Green Eco s...ijeei-iaes
Land mobile communication is burdened with typical propagation constraints due to the channel characteristics in radio systems.Also,the propagation characteristics vary form place to place and also as the mobile unit moves,from time to time.Hence,the tramsmission path between transmitter and receiver varies from simple direct LOS to the one which is severely obstructed by buildings, foliage and terrain. Multipath propagation and shadow fading effects affect the signal strength of an arbitrary Transmitter-Receiver due to the rapid fluctuations in the phase and amplitude of signal which also determines the average power over an area of tens or hundreds of meters. Shadowing introduces additional fluctuations, so the received local mean power varies around the area –mean. The present paper deals with the performance analysis of impact of next generation wireless cognitive radio network on wireless green eco system through signal and interference level based k coverage probability under the shadow fading effects.
Music Recommendation System with User-based and Item-based Collaborative Filt...ijeei-iaes
Internet and E-commerce are the generators of abundant of data, causing information Overloading. The problem of information overloading is addressed by Recommendation Systems (RS). RS can provide suggestions about a new product, movie or music etc. This paper is about Music Recommendation System, which will recommend songs to users based on their past history i.e. taste. In this paper we proposed a collaborative filtering technique based on users and items. First user-item rating matrix is used to form user clusters and item clusters. Next these clusters are used to find the most similar user cluster or most similar item cluster to a target user. Finally songs are recommended from the most similar user and item clusters. The proposed algorithm is implemented on the benchmark dataset Last.fm. Results show that the performance of proposed method is better than the most popular baseline method.
A Real-Time Implementation of Moving Object Action Recognition System Based o...ijeei-iaes
This paper proposes a PixelStreams-based FPGA implementation of a real-time system that can detect and recognize human activity using Handel-C. In the first part of our work, we propose a GUI programmed using Visual C++ to facilitate the implementation for novice users. Using this GUI, the user can program/erase the FPGA or change the parameters of different algorithms and filters. The second part of this work details the hardware implementation of a real-time video surveillance system on an FPGA, including all the stages, i.e., capture, processing, and display, using DK IDE. The targeted circuit is an XC2V1000 FPGA embedded on Agility’s RC200E board. The PixelStreams-based implementation was successfully realized and validated for real-time motion detection and recognition.
Wireless Sensor Network for Radiation Detectionijeei-iaes
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Analysis and Design of Solar Photo voltaic Grid Connected Inverter
1. Indonesian Journal of Electrical Engineering and Informatics (IJEEI)
Vol. 3, No. 4, December 2015, pp. 199~208
DOI: 10.11591/ijeei.v3i4.174 199
Received June 24, 2015; Revised September 11, 2015; Accepted October 9, 2015
Analysis and Design of Solar Photo Voltaic Grid
Connected Inverter
M. Satyanarayana, P. Satish Kumar
Department of Electrical Engineering, University college of Engineering,
Osmania University (Autonomous), Hyderabad, Telangana, India
e-mail: mail2satyanarayana.m@gmail.com
Abstract
This paper presents common mode voltage analysis of single phase grid connected photovoltaic
inverter. Many researchers proposed different grid tie inverters for applications like domestic powering,
street lighting, water pumping, cooling and heating applications, however traditional grid tie PV inverter
uses either a line frequency or a high frequency transformer between the inverter and grid but losses will
increase in the network leading to reduced efficiency of the system. In order to increase the efficiency, with
reduced size and cost of the system, the effective solution is to remove the isolation transformer. But
common mode (CM) ground leakage current due to parasitic capacitance between the PV panels and the
ground making the system unreliable. The common mode current reduces the efficiency of power
conversion stage, affects the quality of grid current, deteriorate the electric magnetic compatibility and give
rise to the safety threats. In order to eliminate the common mode leakage current in Transformerless PV
systm two control algorithms of multi-carrier pwm are implemented and compared for performance
analysis.The shoot-through issue that is encountered by traditional voltage source inverter is analyzed for
enhanced system reliability. These control algorithms are compared for common mode voltage and THD
comparisons. The proposed system is designed using MATLAB/SIMULINK software for analysis.
Keywords: common mode leakage current, transformerless grid connected PV inverter, SPWM, PD
1. Introduction
Grid tie photovoltaic (PV) systems, particularly low-power single-phase systems up to 5
kW, are becoming more important worldwide. They are usually private systems where the
owner tries to get the maximum system profitability. Issues such as reliability, high efficiency,
small size and weight, and low price are of great importance to the conversion stage of the PV
system [1]–[3]. Quite often, these grid-connected PV systems include a line transformer in the
power-conversion stage, which guarantees galvanic isolation between the grid and the PV
system, thus providing personal protection. Furthermore, it strongly reduces the leakage
currents between the PV system and the ground, ensures that no continuous current is injected
into the grid, and can be used to increase the inverter output voltage level [1],[2],[4]. The line
transformer makes possible the use of a full-bridge inverter with unipolar pulse width modulation
(PWM). This inverter is simple and it requires only four insulated gate bipolar transistors (IGBTs)
and has a good trade-off between efficiency, complexity and price [5].
Due to its low frequency, the line transformer is large, heavy and expensive.
Technological evolution has made possible the implementation, within the inverters, of both
ground-fault detection systems and solutions to avoid injecting dc current into the grid. The
transformer can then be eliminated without impacting system characteristics related to personal
safety and grid integration [1],[4],[6]–[8]. In addition, the use of a string of PV modules allows
maximum power point (MPP) voltages large enough to avoid boosting voltages in the
conversion stage. This conversion stage can then consist of a simple buck inverter, with no
need of a transformer or boost dc–dc converter, and it is simpler and more efficient. But if no
boost dc–dc converter is used, the power fluctuation causes a voltage ripple in the PV side at
double the line frequency. This in turn causes a small reduction in the average power generated
by the PV arrays due to the variations around the MPP. In order to limit the reduction, a larger
input capacitor must be used. Typical values of 2 mF for this capacitor limit the reduction in the
MPPT efficiency to 1% in a 5-KW PV system [8]. However, when no transformer is used, a
galvanic connection between the grid and the PV array exists. Dangerous leakage currents
2. ISSN: 2089-3272
IJEEI Vol. 3, No. 4, December 2015 : 199 – 208
200
(common-mode currents) can flow through the large stray capacitance between the PV array
and the ground if the inverter generates a varying common-mode voltage [1]-[4].
Recently, several transformerless inverter topologies have been presented that use
super junction MOSFETs devices as main switches to avoid the fixed voltage-drop and the tail-
current induced turn-off losses of IGBTs to achieve ultra high efficiency. However, this topology
has high conduction losses due to the fact that the current must conduct through three switches
in series during the active phase. Another disadvantage of the H5 is that the line-frequency
switches S1 and S2 cannot utilize MOSFET devices because of the MOSFET body diode’s slow
reverse recovery. The slow reverse recovery of the MOSFET body diode can induce large turn-
on losses, has a higher possibility of damage to the devices and leads to EMI problems. Shoot-
through issues associated with traditional full bridge PWM inverters remain in the H5 topology
due to the fact that the three active switches are series-connected to the dc bus Replacing the
switch S5 of the H5 inverter with two split switches S5 and S6 into two phase legs and adding
two freewheeling diodes D5 and D6 for freewheeling current flows, the H6 topology was
proposed [9]-[10].
The H6 inverter can be implemented using MOSFETs for the line frequency switching
devices, eliminating the use of less efficient IGBTs. The fixed voltage conduction losses of the
IGBTs used in the H5 inverter are avoided in the H6 inverter topology improving efficiency;
however, there are higher conduction losses due to the three series-connected switches in the
current path during active phases. The shoot-through issues due to three active switches series
connected to the dc-bus still remain in the H6 topology. Another disadvantage to the H6 inverter
is that when the inverter output voltage and current has a phase shift the MOSFET body diodes
may be activated. This can cause body diode reverse-recovery issues and decrease the
reliability of the system. The adjustment to improve the system reliability comes at the cost of
high zero-crossing distortion for the output grid current one key issue for a high efficiency and
reliability transformerless PV inverter is that in order to achieve high efficiency over a wide load
range it is necessary to utilize MOSFETs for all switching devices. Another key issue is that the
inverter should not have any shoot-through issues for higher reliability [11]-[13]. The Figure 1
shows the improvements to traditional systems for common mode voltage analysis.
Figure 1. Common-mode currents in a transformerless conversion stage
In order to address these two key issues, a new inverter topology is proposed for single-
phase transformerless PV grid-connected systems in this paper. The proposed converter
utilizes two split ac-coupled inductors that operate separately for positive and negative half grid
cycles. This eliminates the shoot-through issue that is encountered by traditional voltage source
inverters, leading to enhanced system reliability. Dead time is not required at both the high-
frequency pulse width modulation switching commutation and the grid zero crossing instants,
improving the quality of the output ac-current and increasing the converter efficiency.
This paper is organized as section I is about the literature survey on transformerless PV
inverter, sections II is presented about proposed topology with Sine PWM its principle of
3. IJEEI ISSN: 2089-3272
Analysis and Design of Solar Photo Voltaic Grid Connected Inverter (M. Satyanarayana)
201
operation, section III is about common voltage analysis of proposed system, section IV matlab
implementation of the proposed system with sine PWM and Phase Disposition technique.
Comparison of two techniques for THD of output voltages with reduced leakage current is
shown.
2. The Proposed Topology and Operational Analysis
The proposed topology is shown in Figure 2. Circuit diagram of the proposed
transformerless PV inverter, which is composed of six MOSFETs switches (S1–S6), six diodes
(D1–D6), and two split ac-coupled inductors L1 and L2. The diodesD1–D4 performs voltage
clamping functions for active switches S1–S4. The ac-side switch pairs are composed of S5, D5
and S6, D6, respectively, which provide unidirectional current flow branches during the
freewheeling phases decoupling the grid from the PV array and minimizing the CM leakage
current.
Figure 2. Proposed high efficiency and reliability PV transform less inverter topology.
Compared to the HERIC topology the proposed inverter topology divides the ac side
into two independent units for positive and negative half cycle. In addition to the high efficiency
and low leakage current features, the proposed transformerless inverter avoids shoot-through
enhancing the reliability of the inverter. The inherent structure of the proposed inverter does not
lead itself to the reverse recovery issues for the main power switches and as such super
junction MOSFETs can be utilized without any reliability or efficiency Penalties.
Figure 3 illustrates the PWM scheme for the proposed inverter. When the reference
signal Vcontrol is higher than zero, MOSFETs S1 and S3 are switched simultaneously in the
PWM mode and S5 is kept on as a polarity selection switch in the half grid cycle; the gating
signals G2, G4, and G6 are low and S2, S4, and S6 are inactive. Similarly, if the reference
signal –Vcontrol is higher than zero, MOSFETs S2 and S4 are switched simultaneously in the
PWM mode and S6 is on as a polarity selection switch in the grid cycle; the gating signals G1,
G3, and G5 are low and S1, S3, and S5 are inactive.
Figure 3. Phase disposition PWM signal used to control the system
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Table 1. Switching states and respective common mode voltages
S1 S2 S3 S4 S5 S6 Vcm Sequence
pwm off off pwm on off Udc/2
positive
off off off off off off Udc/2
off pwm pwm off of on Udc/2
negative
off off off off off off Udc/2
Figure 4 shows the four operation stages of the proposed inverter within one grid cycle.
In the positive half-line grid cycle, the high-frequency switches S1 and S3 are modulated by the
sinusoidal reference signal Vcontrol while S5 remains turned ON.
Figure 4. Active stage of positive half-line cycle
When S1 and S3 are ON, diode D5 in Figure 5 is reverse-biased, the inductor currents
of iLo1 and iLo3 are equally charged, and energy is transferred from the dc source to the grid.
Figure 5. Freewheeling stage of positive half-line cycle
When S1 and S3 are deactivated, the switch S5 and diode D5 in Figure 6 provide the
inductor current iL1 and iL3 a freewheeling path decoupling the PV panel from the grid to avoid
the CM leakage current. Coupled-inductor L2 is inactive in the positive half-line grid cycle.
Figure 6. Active stage of negative half-line cycle
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Similarly, in the negative half cycle, S2 and S4 in Figure 7 are switched at high
frequency and S6 remains ON. Freewheeling occurs through S6 and D6. When S2 and S4 are
ON, diode D6 is reverse-biased, the inductor currents of iLo2 and iLo4 are equally charged, and
energy is transferred from the dc source to the grid; when S2 and S4 are deactivated, the switch
S6 and diode D6 provide the inductor current iL2 and iL4 a freewheeling path decoupling the PV
panel from the grid to avoid the CM leakage current.
Figure 7. Freewheeling stage of negative half-line cycle
3. Ground Loop Leakage Current Analysis for the Proposed Transformerless Inverter
A galvanic connection between the ground of the grid and the PV array exists in
transformerless grid-connected PV systems. Large ground leakage currents may appear due to
the high stray capacitance between the PV array and the ground. In order to analyze the ground
loop leakage current, Figure 8 shows a model with the phase output points 1, 2, 3, and 4
modeled as controlled voltage sources connected to the negative terminal of the dc bus (N
point).
Figure 8. Simplified CM leakage current analysis model for positive half-line cycle
The value of the stray capacitances Cg1, Cg2, Cg3, and Cg4 of MOSFETs is very low
compared with that of CPVg, therefore the influence of these capacitors on the leakage current
can be neglected. It is also noticed that the DM capacitor Cx does not affect the CM leakage
current. Moreover, during the positive half-line cycle, switches S2, S4, and S6 are kept
deactivated; hence the controlled voltage sources V2N and V4N are equal to zero and can be
removed. Consequently, a simplified CM leakage current model for the positive half-line cycle is
derived as shown in Figure 8.
4. Matlab Verification of the Proposed Circuit
The Figure 9 is the Matlab design of proposed system with unipolar PWM with the
switching frequency of 20KHz. Sine PWM is used to generate the control signals to convert DC
of supply into AC supply. The subsystem of Solar PV system is shown in Figure 10.
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Figure 9. Proposed circuit in Matlab
Figure 10. Solar pv system designed in Matlab
Phase of Disposition is the one multi-carrier pwm applied to the proposed system for
common mode analysis. Multiple carriers were chosen based on the principle of POD pwm
technique is shown in Figure 11.
Figure 11. POD pwm applied to proposed system
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The inverter output voltage and current waveform is shown in Figure 12 with output
voltage of 230V, 50Hz and 4 amps of current is obtained as AC grid tie output. The green
waveform is shown in figure represents the leakage currents due to common mode voltages.
Figure 12. Grid voltage and current
As shown in the proposed circuit the output of inverter is not directly connected to grid,
two inductive filters are employed for positive half and negative half cycle of the output
independently. The waveforms represent the currents through the inductors for positive and
negative half of full cycle. Figure 13 shows the closer image of the leakage current due to the
common mode voltage. The Figure 14 shows the individual currents that flow through the filter
inductor during both half cycles.
Figure 13. Common mode leakage current with POD PWM
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Figure 14. Inductor currents of iLo1, iLo2, iLo3 and iLo4
The Figure 15 shows the total Harmonic distortion of output voltage tied to grid while
using sine PWM as the pulse generator, it is found that the THD is about 14.60%.
Figure 15. THD of output voltage using POD PWM technique
Phase opposition is the one of the efficient technique among the PD, POD, APOD,
Figure 16 shows the PD technique implemented by using Matlab for generating gate signals it is
evident from Figure 17 that the leakage current due to common mode voltage is became nearly
to zero and the total harmonic distortion is reduced to 9.86%.
Figure 16. Phase Disposition modulation technique applied to proposed system
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Figure 17. Reduced Leakage currents when applying PD technique
The Figure 6 is the gate pulse generation for the proposed converter for 20KHZ
operating frequency of converter. The figure 11 is the grid voltages and current at pcc. The
Figure 14 gives grid voltage, inductor currents of iLo1 and iLo2. The main of this project is
reducing common mode currents is presented in Figure 17. The Figure 18 shows the THD of
output voltage is about 2.22% shows that power quality is up to the mark. According to IEEE
standard 5% of THD is acceptable limit.
Figure 18. FFT analysis using PD technique
5. Conclusion
A high reliability and efficiency inverter for transformerless solar PV grid-connected
systems is presented in this paper using Matlab/Simulink model design. The leakage current
present due to the effect of common mode voltage with POD PWM and PD PWM are applied on
the proposed converter performance analysis interms of THD. It is observed from FFT analysis
of POD and PD pwm techniques that PD has very low thd and also the characteristics of the
proposed transformerless inverter shows the reduced shoot-through issue leads to greatly
enhanced reliability, low ac output current distortion is achieved because a high dead time is not
needed at PWM switching commutation instants in the case of PD technique. It is shown that
the proposed transformerless PV grid tie inverter is efficient when using PD as control technique
for controlling the switching operation with overall improved efficiency.
The asymmetry of the switch arrangements in less usage of the number of high
frequency switches in order to reduce the losses and increase the efficiency of proposed system
will be a good option.
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Appendix
Parameters Specifications
Input voltage 440V DC
Grid voltage/ Frequency 230V/50Hz
Rated Power 1000W
Switching Frequency 20KHz
Dc bus capacitor 470µF
Filter capacitor 4.7µF
Filter Inductors 2mH
Parasitic capacitors 750nF
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