EPE Association: EPE-PEMC 2008 - Topic: Application and Design of Power Electronic Systems

EPE-PEMC 2008 - Topic: Application and Design of Power Electronic Systems
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2008 - Conference > EPE-PEMC 2008 - Topic: Application and Design of Power Electronic Systems

   [return to parent folder]

   A New Soft Switching Synchronous Buck Converter for Critical Load Applications
By Swapnajit Pattnaik

Abstract: This paper proposes a zero-voltage-transition PWM synchronous buck converter, which is designed to operate at low voltage and high efficiency typically required for portable systems. A new passive auxiliary circuit that allows the main switch to operate with ZVS has been incorporated in the conventional PWM synchronous buck converter. The operation principles with detailed steady-state analysis of the ZVT PWM synchronous converter are presented. Besides the main switch all of the semiconductor devices operate under soft switching conditions. Thus the auxiliary circuit provides larger overall efficiency. The feasibility of the auxiliary circuit is confirmed by simulation and experimental results.

   AC Voltage Regulator Using PWM Technique and Magnetic Flux Distribution
By A. M. Dabroom [View]
[Download]

Abstract: This paper proposes an AC voltage regulator for resistive loads using the PWM technique and magnetic flux distribution. The load voltage can be controlled using one switching element( MOSFET) and three limb magnetic circuit. The proposed regulator depend on the PWM technique and control the magnetic flux distribution in the magnetic circuit sections.The suggested regulator gives smooth variation of the load voltage and nearly sinusoidal current at the supply terminals with minimum harmonics. The power factor at the supply terminals is nearly unity over the control range of the load voltage. Equivalent circuit of the regulator is proposed. The computed results are compared with those obtained experimentally using a test model, where good agreement is achieved.

   Calculation of Leakage Inductance of Core-Type Transformers for Power Electronic Circuits
By Reinhard Doebbelin, Marcel Benecke and Andreas Lindemann [View]
[Download]

Abstract: Leakage inductances of transformers significantly influence the behavior of power electronic circuits. This paper deals with their prediction: The application of the approximation method of Lebedev for the calculation of leakage inductance of core-type transformers as well as an extension of this method for pie winding arrangements are presented. Design aspects influencing leakage inductance are additionally investigated by means of finite element simulations.

   Control of Power Supply Unit for Military Vehicles Based on Four-Leg Three-Phase VSI with Proportional-Resonant Controllers
By Tomáš Glasberger [View]
[Download]

Abstract: This paper deals with the control of the output part of a power electronics converter, which we have designed for a diesel-electric power supply unit for military applications. The output part of the unit is composed of a four-leg three-phase voltage source inverter and a sinusoidal filter. The output part of the power supply unit with help of proposed control system allows to create three-phase symmetrical sinusoidal output voltage under arbitrary load condition (1-phase, 3-phase, linear, non-linear, symmetrical, unsymmetrical) with minimum output voltage distortion. The employed control is based on a set of proportional-resonant (PR) controllers. Behaviour of designed converter has been verified by simulation results as well as by experiments performed on designed laboratory prototype of rated power of 18 kVA.

   Corona Treatment System with Resonant Inverter - Selected Proprieties
By Mućko Jan [View]
[Download]

Abstract: The paper describes a mathematical model and proprieties of series resonant inverters used in application for activators of polyethylene foil (corona treatment). The method of identification of corona treatment parameters and power calculation is described as well. The area of soft switching and the area with corona discharge is shown. In this paper a new control method of corona treatment based on PDM and PFM modulation is presented. The control characteristics were determined. The circuits were tested by means of simulation and experimentally by industrial applications.

   Enhanced Current Pulsation Smoothing Parallel Active Filter for Single Stage Grid-Connected AC-PV Modules
By A.C. Kyritsis [View]
[Download]

Abstract: On single stage PV Converters the output power has a large amount of power pulsation at twice line frequency, causing PV module voltage and current fluctuation. However, a PV module should operate at a sufficiently small area around the maximum power point, in order to maximize PV generation. To overcome this defect a buffering storage unit between the PV module and the inverter, which performs the well known Power Decoupling, is inevitable. This paper presents an enhanced configuration of a Current Pulsation Smoothing Parallel Active Filter (CPS-PAF) which permits the elimination of the low frequency PV current ripple with significant smaller capacitor comparatively to the classical configuration. The enhanced CPS-PAF conception, control and effectiveness are validated by PSpice simulation results as well as by experimental results accomplished on a laboratory prototype.

   Evaluation of Different Loss Calculation Methods for High-Voltage IGBT-s Under Small Load Conditions
By T. Jalakas, D. Vinnikov and J. Laugis [View]
[Download]

Abstract: This paper focuses on the evaluation of the calculated and measured values of high-voltage 6.5 kV IGBT module losses, used in mid-power applications under low load conditions. The values of the losses were calculated by use of widely known equations and IPOSIM 6.0 software. The experimental setup was based on a high-voltage halfbridge isolated DC/DC converter. Comparison of calculation and experimental results shows that the dynamic losses on higher switching frequencies are smaller than those calculated and that the IPOSIM software is relatively accurate. This knowledge helps developers to avoid overestimation of the losses and allows us to construct more compact power electronics applications with much higher switching frequencies.

   Feasibility Study of Half- and Full-Bridge Isolated DC/DC Converters in High-Voltage High-Power Applications
By Dmitri Vinnikov [View]
[Download]

Abstract: This paper discusses the half- and full-bridge DC/DC converter topologies for high-power (200 kW) high-voltage (3.6 kV) applications. Focus is on the primary part of these topologies, i.e. the feasibility of replacement of two high-voltage IGBTs in the full-bridge by two high-voltage film capacitors in the half-bridge. The implementation of a half-bridge topology will lead to a sufficient simplification of a power scheme layout as well as control and protection algorithms. The full-bridge topology gives a clear advantage of the twofold reduced current of inverter switches, thus providing a possibility of implementation of smaller devices for the same transferred power as compared to a halfbridge.

   High Power, High Voltage, High Frequency Transformer / Rectifier for HV Industrial Applications
By T. Filchev [View]
[Download]

Abstract: This paper presents a high voltage (HV), high frequency (HF) transformer with voltage multiplier. The described systems employ a low profile HV, HF transformers and voltage bridge technology multiplier. A model of the converter of 150kW is presented and verified by Saber simulator. Design considerations and models of the HV, HF transformers are presented.

   Investigation of High Frequency Effects on Layered Coils
By Georgios S. Dimitrakakis [View]
[Download]

Abstract: Copper losses in magnetic coils depend on several geometrical parameters, as well as on frequency, in a way that makes their modeling a quite difficult task. In this paper a Finite Element Analysis (FEA) software is utilized for the investigation of a series of issues critical for the accurate determination of copper losses in layered coils with round wires or foils. Some of the issues investigated are the edge effect in foil and round wire windings as well as the effect of the winding pitch on the copper losses. The results that come up from this work help to fully understand the real impact of two dimensional (2D) effects in layered windings of real rather than ideal magnetic components and they consist a tool for the accurate calculation of the encountered losses, which is necessary for an optimized magnetic component design.

   Magnetic Material Comparisons for High-Current Gapped and Gapless Foil Wound Inductors in High Frequency DC-DC Converters
By Marek S. Rylko and Michael G. Egan [View]
[Download]

Abstract: The inductor often drives the dc-dc converter size. Thus, the inductor optimization process is required for the most effective design. The paper presents inductor analysis only. The material properties are essential for the design size. In this paper, various magnetic materials are analysed and investigated for use in a practical design. The investigation is concerned with the magnetic material selection for a dc-dc power inductor in the medium (20 kHz) to high (150 kHz) frequency range. The materials under investigation are iron-based amorphous metal, silicon steel, nanocrystalline, ferrite, and gap-less powder materials. A lumped parameter algorithm is derived which includes such effects as the foil ac copper loss effects, the gap core loss, and the cooling path. The algorithm is implemented in EXCEL and generates material comparisons over a range of frequencies, ripple ratios, cooling paths. The results show that the core power loss limited inductor tends to be oversized while the minimum size is achieved for the design which is at the sweet-spot where the size is driven by the core power loss, winding power loss and core saturation limit. A 1.25 kW half-bridge dc-dc converter is built in order to proof the algorithm feasibility at the interest frequency range.

   Minimum Reactive Power Filter Design for High Power Converters
By Alex-Sander Amavel Luiz [View]
[Download]

Abstract: This work proposes and evaluates an optimized filter design for high power converter with sinusoidal voltage and current. The inherent low switching frequency of this class of converters complicates the filter design and generally results in large filter components. The proposed design culminates in minimum filter reactive power, size and cost. Simulation and experimental results support those ideas.

   Optimal Design of a Half Wave Cockroft-Walton Voltage Multiplier with Different Capacitances Per Stage
By Ioannis C. Kobougias [View]
[Download]

Abstract: Even though the Half-Wave Cockroft-Walton Voltage Multiplier (H-W C-W VM) is one of the most common AC-DC step-up topologies, most of the VM designers persist in using equal capacitances in every stage, a fact that leads to a non optimal design. The aim of this paper is to introduce a new designing method of H-W C-W VM that lays both on the choice of the adequate capacitance values to minimize the output voltage drop and ripple and the calculation of the optimal number of stages that is necessary to produce the desired output voltage with the minimum base capacitance value. In this way the voltage gain is maximized and the required capacitance value per stage is minimized. The theoretical analysis is validated by PSPICE simulations and experimental results, accomplished on laboratory prototypes.

   Outline of the Design of a Cascaded H-Bridge Medium Voltage STATCOM
By R. E. Betz [View]
[Download]

Abstract: The University of Newcastle and its joint venture company, ResTech Pty Ltd, are developing a cascaded H-bridge based multilevel STATCOM. This tutorial paper outlines the salient design issues for this system. The issues covered in the paper include the choice of the converter topology, the structure of the control system hardware, the software structure and methodology, some details on the control algorithm, and the rationale behind the design decisions.

   Power Supply for a IGBT-Driver with High Insulation Voltage based on a Printed Planar Transformers
By Günter Schmitt, Wolf Kusserow and Ralph Kennel [View]
[Download]

Abstract: For the operation of high-power semiconductors in medium-voltage converters, the insulation of the control signal as well as for the powersupply is indispensable. In this paper, we present a DC/DCconverter based on a printed transformer that reached an insulation voltage of 10 kV. Due to the fact that the circuit board itself is used as insulation, we avoid the use of vias or a closed magnetic core. The converter operates at a frequency of 420 kHz and provides an output power of 6 W. By minimising the amount of components and not using a standard transformer, a great cost-reduction has been achieved.

   Power Supply Unit for an Electric Discharge Machine
By Wojciech Mysiński [View]
[Download]

Abstract: The electrical discharge machining process provides one of the best solutions available for machining a growing number of high-strength and corrosion -and-wear resistant materials. It operates on the principle of erosion of metal surfaces by an interrupted electric spark. The power supply design and configuration requirements for producing the desired spark have always been a challenge to the researchers. This paper presents an example of a configuration of a power supply used for the EDM process. The power supply (a pulse power generator) is based on an electronic current source utilising MOSFET transistors. This article describes both simulation tests carried out on the circuit, and results of laboratory tests.

   Requirements for Power Electronics in Solid Oxide Fuel Cell System
By T. Riipinen, V. Väisänen, M. Kuisma, L. Seppä, P. Mustonen and P. Silventoinen [View]
[Download]

Abstract: The fuel cell has special electrical characteristics which set challenging requirements for power conditioning units. Many of these requirements origin from the operation principle and physical structure of the fuel cell and cannot be ignored in the design of power electronics. In this paper the operational requirements for power conditioning units are reviewed from the point of view of basic operation principles and characteristics of solid oxide fuel cell.

   Small Power Laboratory Model and High Power Prototype of the Four-Level VSI
By Ryszard Michal Strzelecki [View]
[Download]

Abstract: In the paper, we discuss a laboratory mode of a Diode Clamped 4-level Voltage Source Inverter (VSI) of power approximately 5kVA, that is designed for initial experimental verification of solutions for "software" and "hardware" of the control components in prototype model of inverter 6kV and 0,5-1 MVA. The paper discusses tasks of control console in the PC. The article also discussed construction and development of the power part of the inverter model. In addition, it presents the voltage PWM algorithm implemented in the DSP. Experimental results are presented.

   Soft Switching PWM Inverter for Induction Heating Applied to Heating of Ferromagnetic Metal
By Sachio Kubota, Muneo Sato, Fumio Ito, Yoshihiro Shimaoka and Kunihiro Nishioka [View]
[Download]

Abstract: In this paper, a soft switching PWM (Pulse Width Modulation) inverter for heating up to high temperature ferromagnetic metals is proposed as a power supply to apply to the diesel emission control system. And an optimal circuit design and an operating method about this inverter to solve several problems caused by heating up to high temperature it are described in detail. The validity of the proposed method is verified through both the simulated results and the experimental results.

   Variable Motor Operating Point by Integration of Power Electronic Device into Rotor
By Adrian Tulbure [View]
[Download]

Abstract: The main issue of this work is to analyze and to test how the characteristic curve of the induction machine can be adjusted by the power electronic devices, when these are integrated into rotor circuits. In order to technically analyze the characteristic performances of the induction machine by switching between cages, the simulator software's MATLAB and NETASIM have been used. The simulated current- and torque-waveforms are compared with the experimental values from the test bench. To practical validation of the results, a main feed induction machine with working-cage controller has been designed and tested at the Institute of Electrical Power Engineering in Clausthal, Germany.

EPE-PEMC 2008 - Topic: Application and Design of Power Electronic Systems
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2008 - Conference > EPE-PEMC 2008 - Topic: Application and Design of Power Electronic Systems
	[return to parent folder]

	A New Soft Switching Synchronous Buck Converter for Critical Load Applications By Swapnajit Pattnaik
Abstract: This paper proposes a zero-voltage-transition PWM synchronous buck converter, which is designed to operate at low voltage and high efficiency typically required for portable systems. A new passive auxiliary circuit that allows the main switch to operate with ZVS has been incorporated in the conventional PWM synchronous buck converter. The operation principles with detailed steady-state analysis of the ZVT PWM synchronous converter are presented. Besides the main switch all of the semiconductor devices operate under soft switching conditions. Thus the auxiliary circuit provides larger overall efficiency. The feasibility of the auxiliary circuit is confirmed by simulation and experimental results.

	AC Voltage Regulator Using PWM Technique and Magnetic Flux Distribution By A. M. Dabroom	[View] [Download]
Abstract: This paper proposes an AC voltage regulator for resistive loads using the PWM technique and magnetic flux distribution. The load voltage can be controlled using one switching element( MOSFET) and three limb magnetic circuit. The proposed regulator depend on the PWM technique and control the magnetic flux distribution in the magnetic circuit sections.The suggested regulator gives smooth variation of the load voltage and nearly sinusoidal current at the supply terminals with minimum harmonics. The power factor at the supply terminals is nearly unity over the control range of the load voltage. Equivalent circuit of the regulator is proposed. The computed results are compared with those obtained experimentally using a test model, where good agreement is achieved.

	Calculation of Leakage Inductance of Core-Type Transformers for Power Electronic Circuits By Reinhard Doebbelin, Marcel Benecke and Andreas Lindemann	[View] [Download]
Abstract: Leakage inductances of transformers significantly influence the behavior of power electronic circuits. This paper deals with their prediction: The application of the approximation method of Lebedev for the calculation of leakage inductance of core-type transformers as well as an extension of this method for pie winding arrangements are presented. Design aspects influencing leakage inductance are additionally investigated by means of finite element simulations.

	Control of Power Supply Unit for Military Vehicles Based on Four-Leg Three-Phase VSI with Proportional-Resonant Controllers By Tomáš Glasberger	[View] [Download]
Abstract: This paper deals with the control of the output part of a power electronics converter, which we have designed for a diesel-electric power supply unit for military applications. The output part of the unit is composed of a four-leg three-phase voltage source inverter and a sinusoidal filter. The output part of the power supply unit with help of proposed control system allows to create three-phase symmetrical sinusoidal output voltage under arbitrary load condition (1-phase, 3-phase, linear, non-linear, symmetrical, unsymmetrical) with minimum output voltage distortion. The employed control is based on a set of proportional-resonant (PR) controllers. Behaviour of designed converter has been verified by simulation results as well as by experiments performed on designed laboratory prototype of rated power of 18 kVA.

	Corona Treatment System with Resonant Inverter - Selected Proprieties By Mućko Jan	[View] [Download]
Abstract: The paper describes a mathematical model and proprieties of series resonant inverters used in application for activators of polyethylene foil (corona treatment). The method of identification of corona treatment parameters and power calculation is described as well. The area of soft switching and the area with corona discharge is shown. In this paper a new control method of corona treatment based on PDM and PFM modulation is presented. The control characteristics were determined. The circuits were tested by means of simulation and experimentally by industrial applications.

	Enhanced Current Pulsation Smoothing Parallel Active Filter for Single Stage Grid-Connected AC-PV Modules By A.C. Kyritsis	[View] [Download]
Abstract: On single stage PV Converters the output power has a large amount of power pulsation at twice line frequency, causing PV module voltage and current fluctuation. However, a PV module should operate at a sufficiently small area around the maximum power point, in order to maximize PV generation. To overcome this defect a buffering storage unit between the PV module and the inverter, which performs the well known Power Decoupling, is inevitable. This paper presents an enhanced configuration of a Current Pulsation Smoothing Parallel Active Filter (CPS-PAF) which permits the elimination of the low frequency PV current ripple with significant smaller capacitor comparatively to the classical configuration. The enhanced CPS-PAF conception, control and effectiveness are validated by PSpice simulation results as well as by experimental results accomplished on a laboratory prototype.

	Evaluation of Different Loss Calculation Methods for High-Voltage IGBT-s Under Small Load Conditions By T. Jalakas, D. Vinnikov and J. Laugis	[View] [Download]
Abstract: This paper focuses on the evaluation of the calculated and measured values of high-voltage 6.5 kV IGBT module losses, used in mid-power applications under low load conditions. The values of the losses were calculated by use of widely known equations and IPOSIM 6.0 software. The experimental setup was based on a high-voltage halfbridge isolated DC/DC converter. Comparison of calculation and experimental results shows that the dynamic losses on higher switching frequencies are smaller than those calculated and that the IPOSIM software is relatively accurate. This knowledge helps developers to avoid overestimation of the losses and allows us to construct more compact power electronics applications with much higher switching frequencies.

	Feasibility Study of Half- and Full-Bridge Isolated DC/DC Converters in High-Voltage High-Power Applications By Dmitri Vinnikov	[View] [Download]
Abstract: This paper discusses the half- and full-bridge DC/DC converter topologies for high-power (200 kW) high-voltage (3.6 kV) applications. Focus is on the primary part of these topologies, i.e. the feasibility of replacement of two high-voltage IGBTs in the full-bridge by two high-voltage film capacitors in the half-bridge. The implementation of a half-bridge topology will lead to a sufficient simplification of a power scheme layout as well as control and protection algorithms. The full-bridge topology gives a clear advantage of the twofold reduced current of inverter switches, thus providing a possibility of implementation of smaller devices for the same transferred power as compared to a halfbridge.

	High Power, High Voltage, High Frequency Transformer / Rectifier for HV Industrial Applications By T. Filchev	[View] [Download]
Abstract: This paper presents a high voltage (HV), high frequency (HF) transformer with voltage multiplier. The described systems employ a low profile HV, HF transformers and voltage bridge technology multiplier. A model of the converter of 150kW is presented and verified by Saber simulator. Design considerations and models of the HV, HF transformers are presented.

	Investigation of High Frequency Effects on Layered Coils By Georgios S. Dimitrakakis	[View] [Download]
Abstract: Copper losses in magnetic coils depend on several geometrical parameters, as well as on frequency, in a way that makes their modeling a quite difficult task. In this paper a Finite Element Analysis (FEA) software is utilized for the investigation of a series of issues critical for the accurate determination of copper losses in layered coils with round wires or foils. Some of the issues investigated are the edge effect in foil and round wire windings as well as the effect of the winding pitch on the copper losses. The results that come up from this work help to fully understand the real impact of two dimensional (2D) effects in layered windings of real rather than ideal magnetic components and they consist a tool for the accurate calculation of the encountered losses, which is necessary for an optimized magnetic component design.

	Magnetic Material Comparisons for High-Current Gapped and Gapless Foil Wound Inductors in High Frequency DC-DC Converters By Marek S. Rylko and Michael G. Egan	[View] [Download]
Abstract: The inductor often drives the dc-dc converter size. Thus, the inductor optimization process is required for the most effective design. The paper presents inductor analysis only. The material properties are essential for the design size. In this paper, various magnetic materials are analysed and investigated for use in a practical design. The investigation is concerned with the magnetic material selection for a dc-dc power inductor in the medium (20 kHz) to high (150 kHz) frequency range. The materials under investigation are iron-based amorphous metal, silicon steel, nanocrystalline, ferrite, and gap-less powder materials. A lumped parameter algorithm is derived which includes such effects as the foil ac copper loss effects, the gap core loss, and the cooling path. The algorithm is implemented in EXCEL and generates material comparisons over a range of frequencies, ripple ratios, cooling paths. The results show that the core power loss limited inductor tends to be oversized while the minimum size is achieved for the design which is at the sweet-spot where the size is driven by the core power loss, winding power loss and core saturation limit. A 1.25 kW half-bridge dc-dc converter is built in order to proof the algorithm feasibility at the interest frequency range.

	Minimum Reactive Power Filter Design for High Power Converters By Alex-Sander Amavel Luiz	[View] [Download]
Abstract: This work proposes and evaluates an optimized filter design for high power converter with sinusoidal voltage and current. The inherent low switching frequency of this class of converters complicates the filter design and generally results in large filter components. The proposed design culminates in minimum filter reactive power, size and cost. Simulation and experimental results support those ideas.

	Optimal Design of a Half Wave Cockroft-Walton Voltage Multiplier with Different Capacitances Per Stage By Ioannis C. Kobougias	[View] [Download]
Abstract: Even though the Half-Wave Cockroft-Walton Voltage Multiplier (H-W C-W VM) is one of the most common AC-DC step-up topologies, most of the VM designers persist in using equal capacitances in every stage, a fact that leads to a non optimal design. The aim of this paper is to introduce a new designing method of H-W C-W VM that lays both on the choice of the adequate capacitance values to minimize the output voltage drop and ripple and the calculation of the optimal number of stages that is necessary to produce the desired output voltage with the minimum base capacitance value. In this way the voltage gain is maximized and the required capacitance value per stage is minimized. The theoretical analysis is validated by PSPICE simulations and experimental results, accomplished on laboratory prototypes.

	Outline of the Design of a Cascaded H-Bridge Medium Voltage STATCOM By R. E. Betz	[View] [Download]
Abstract: The University of Newcastle and its joint venture company, ResTech Pty Ltd, are developing a cascaded H-bridge based multilevel STATCOM. This tutorial paper outlines the salient design issues for this system. The issues covered in the paper include the choice of the converter topology, the structure of the control system hardware, the software structure and methodology, some details on the control algorithm, and the rationale behind the design decisions.

	Power Supply for a IGBT-Driver with High Insulation Voltage based on a Printed Planar Transformers By Günter Schmitt, Wolf Kusserow and Ralph Kennel	[View] [Download]
Abstract: For the operation of high-power semiconductors in medium-voltage converters, the insulation of the control signal as well as for the powersupply is indispensable. In this paper, we present a DC/DCconverter based on a printed transformer that reached an insulation voltage of 10 kV. Due to the fact that the circuit board itself is used as insulation, we avoid the use of vias or a closed magnetic core. The converter operates at a frequency of 420 kHz and provides an output power of 6 W. By minimising the amount of components and not using a standard transformer, a great cost-reduction has been achieved.

	Power Supply Unit for an Electric Discharge Machine By Wojciech Mysiński	[View] [Download]
Abstract: The electrical discharge machining process provides one of the best solutions available for machining a growing number of high-strength and corrosion -and-wear resistant materials. It operates on the principle of erosion of metal surfaces by an interrupted electric spark. The power supply design and configuration requirements for producing the desired spark have always been a challenge to the researchers. This paper presents an example of a configuration of a power supply used for the EDM process. The power supply (a pulse power generator) is based on an electronic current source utilising MOSFET transistors. This article describes both simulation tests carried out on the circuit, and results of laboratory tests.

	Requirements for Power Electronics in Solid Oxide Fuel Cell System By T. Riipinen, V. Väisänen, M. Kuisma, L. Seppä, P. Mustonen and P. Silventoinen	[View] [Download]
Abstract: The fuel cell has special electrical characteristics which set challenging requirements for power conditioning units. Many of these requirements origin from the operation principle and physical structure of the fuel cell and cannot be ignored in the design of power electronics. In this paper the operational requirements for power conditioning units are reviewed from the point of view of basic operation principles and characteristics of solid oxide fuel cell.

	Small Power Laboratory Model and High Power Prototype of the Four-Level VSI By Ryszard Michal Strzelecki	[View] [Download]
Abstract: In the paper, we discuss a laboratory mode of a Diode Clamped 4-level Voltage Source Inverter (VSI) of power approximately 5kVA, that is designed for initial experimental verification of solutions for "software" and "hardware" of the control components in prototype model of inverter 6kV and 0,5-1 MVA. The paper discusses tasks of control console in the PC. The article also discussed construction and development of the power part of the inverter model. In addition, it presents the voltage PWM algorithm implemented in the DSP. Experimental results are presented.

	Soft Switching PWM Inverter for Induction Heating Applied to Heating of Ferromagnetic Metal By Sachio Kubota, Muneo Sato, Fumio Ito, Yoshihiro Shimaoka and Kunihiro Nishioka	[View] [Download]
Abstract: In this paper, a soft switching PWM (Pulse Width Modulation) inverter for heating up to high temperature ferromagnetic metals is proposed as a power supply to apply to the diesel emission control system. And an optimal circuit design and an operating method about this inverter to solve several problems caused by heating up to high temperature it are described in detail. The validity of the proposed method is verified through both the simulated results and the experimental results.

	Variable Motor Operating Point by Integration of Power Electronic Device into Rotor By Adrian Tulbure	[View] [Download]
Abstract: The main issue of this work is to analyze and to test how the characteristic curve of the induction machine can be adjusted by the power electronic devices, when these are integrated into rotor circuits. In order to technically analyze the characteristic performances of the induction machine by switching between cages, the simulator software's MATLAB and NETASIM have been used. The simulated current- and torque-waveforms are compared with the experimental values from the test bench. To practical validation of the results, a main feed induction machine with working-cage controller has been designed and tested at the Institute of Electrical Power Engineering in Clausthal, Germany.