EPE Association: EPE 1999 - Topic 02b: Power Converter Circuits and Control

EPE 1999 - Topic 02b: Power Converter Circuits and Control
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1999 - Conference > EPE 1999 - Topic 02: POWER ELECTRONICS CONVERTER CIRCUITS > EPE 1999 - Topic 02b: Power Converter Circuits and Control

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   A 160 A IGBT Welding Power Source with 100 kHz Output Switching F...
By E. Lourenço; E. Margato; P. Verdelho [View]
[Download]

Abstract: In this paper a welding power source using electronic power conversion techniques is described. A dc current power source gives 160 A under a maximum 35 V arc voltage. The power input may be obtained directly from the public electricity supply network through a AC-DC voltage rectifier. The transformer primary coil voltage is obtained by a 50 kHz full wave IGBT Voltage Source Inverter (VSI). The welding current rectification is obtained by a full wave diode bridge operating after the transformer secondary coil. This topology will allow maximum output dc current grow factors and a output switching frequency of 100 kHz. Applying non-linear control techniques a very fast dynamic for the dc current control is obtained without steady state error and with low current ripple. This process has however the drawback of requiring a average current control external loop of the transformer primary side, with the propose of prevent the emergence of a dc component. A relative simple control circuit is obtained.

   A Full Regulated Two Output Forward Converter with a Novel Parallel Regulation Technique
By A. Ferreres; J. A. Carrasco; A.E. Navarro; R. García; E. J. Dede [View]
[Download]

Abstract: The complete elimination of cross-regulation in PWM multiple-output converters requires post-regulation. For medium-high output currents the more usual post-regulators are: the PWM regulators in cascade, the magamp, and the synchronous switch post-regulators (SSPR) [1]. The last two are very efficient but their actuation can only reduce the duty cycle and the design of the magamp control loop is difficult due to the presence of non linear elements and a phase delay [2][3]. For high outputs currents an alternative for the elimination of cross-regulation is the parallel post-regulator with controlled transformer [4] [5], this combines a good efficiency and the easiness of design of classical switching power supplies. The idea is based on handling only a percentage of the power delivered by the output in order to regulate it. By using the transformer the post-regulator adds a positive or negative voltage to the output filter and adjusts the voltssecond balance. The model for a parallel post-regulator is not described for PWM converters. This paper describes the post-regulation strategy for obtaining two outputs independently regulated, and presents a model to obtain the control transfer function and the expressions of cross-impedances.

   A Matrix Converter with Space Vector Control Enabling Overmodulation
By J. Mahlein; O. Simon; M. Braun [View]
[Download]

Abstract: In this paper the design and testing of a matrix converter using a new method of vector overmodulation is described. The selection of the bi-directional switches as a main part of the converter is discussed and an overview of admissible commutation switching sequences is given. The theoretical output voltage limit which is 86.6% of the input voltage on sinusoidal operation can be increased up to 105%. Using overmodulation means to stress the grid and the load with non sinusoidal currents for higher voltage transfer ratio.

   A New Conception of a Battery Regulation Unit for Mini-Satellites
By A.E. Navarro; J.A. Carrasco; E. Maset; A. Ferreres; E.J. Dede [View]
[Download]

Abstract: This paper describes the conception and design of a new battery regulation unit (BRU) for a minisatellite with a regulated voltage bus. Normally a mini-satellite has two converters, one working as a battery charge regulator and another working as a battery discharge regulator. This paper proposes to use one converter for both working modes that can be use either if the battery voltage is over or down the bus voltage, characteristic that increases the modularity on the mini-satellite design, maintaining the normal efficiency and reliability required by the space agencies. These properties are verifyed with experimental results.

   A New Topology for PWM Current Source Inverter with IGBT
By R. Mecke; U. Riefenstahl; B. Neumann [View]
[Download]

Abstract: At the moment PWM current source inverters are equiped with GTO-thyristors and used for asynchronous drives in the power range between 1.5 and 13.5 megawatt. An essential problem of these inverter topology are the interactions between the impedance and the filter capacitors on the line and motor side. These oscillating circuits can be excited by low order harmonics and by the switching frequency and can cause instable operation of the drive. The paper presents a new topology for PWM current source inverters. In comparison to the conventional inverter circuit it enables a considerable reduction of the filter capacitors and therefore a decrease of the inverter size. Moreover the small filter capacities create high resonance frequencies of several kilohertz, which cannot be excited by low order harmonics. Thats why the resonance problems on the line and motor side can be avoided, the field oriented control can be strongly simplified and the dynamic behaviour of the drive system can be improved. A condition for this are switching frequencies of several kilohertz, which can be realized for instance by using IGBT. The function of the new inverter topology was proved by simulation and experiment. Some results are shown.

   An Overcurrent Portection Coordination in Converters with IGBT Transistors
By S. Januszewski; K. Zymmer [View]
[Download]

Abstract: The explosion strength of high power IGBT modules is one of the important parameters that may decide on converter equipment reliability in extreme circumstances. Service conditions connected with explosion hazard of these modules dangerous for converter accessories and personal safety is discussed. Principles of overcurrent protection coordination in medium and high power IGBT converters taking into account this phenomenon is considered.

   Characterization of Semiconductor Losses in Series Resonant DC-DC...
By H. Reinold; M. Steiner [View]
[Download]

Abstract: The well known series resonant DC-DC converter with galvanic insulation realizes zero current switching (ZCS). Semiconductor losses can be optimized through changing the blanking time. The use of a transformer with extremely low leakage inductance (e.g. coaxial winding transformer) leads to an unconventional commutation process that results in very low switching losses even in non ZCS mode which will be described in this paper. This paper compares the semiconductor losses of the different modes of operation (conventional ZCS, ZCS with increased blanking time and without ZCS) as experimental result of a 12kW test setup and of a 200kW prototype converter.

   Digital Control of a Three Phase 4 Wire PWM Inverter for PV Applications
By S. El-Barbari; W. Hofmann [View]
[Download]

Abstract: The microcontroller based digital control of a three phase 4 wire PWM inverter for simultaneously supply of three phase and single phase load in transformerless stand alone photovoltaic application with battery energy storage (BES) ald LC output filter is described. An observer is implimented to estimate the load current and to predict the space states for one step ahead. A control method based on the dead beat control algorithm is described to regulate the output voltage of the LC filter so that disturbance of the output voltage due to load unbalances is eliminated. Simulation results for various operation conditions are presented to verify the validity of the control method.

   Fault Tolerant UPF Converters Operating from a Variable Frequency Supply for an Aerospace Application
By S. R. Green; D. J. Atkinson; B. C. Mecrow; A. G. Jack [View]
[Download]

Abstract: This paper describes two fault tolerant Unity Power Factor (UPF) converter topologies for operation from an aircraft variable frequency supply. It discusses the reasons for choosing these topologies and the performance of current controllers on a variable frequency supply.

   Harmonic Reduction in DC Link Current of a PWM Drive by Direct Ripple Injection
By F. M. Pérez Hidalgo; J. R. Heredia Larrubia; J. L. Durán Paz [View]
[Download]

Abstract: Substitution for DC motors by PWM inverter-fed leads to high harmonics levels in the DC side of the converters. Higher order harmonics can still be a source of electromagnetic interference and often need to be filtered. The conventional solution for the reduction of DC side Harmonics is the passive filter. It is an easy solution but unfortunately the requiered reduction of harmonics leads to a filter of excessive size and weight. It is also an expensive solution. The use of an active filter in combination with the pasive ones has been recently succesfully tried to reduce the higer harmonics content. This paper describes an alternative solution to passive and active filter arrangements on the DC side of the converter [1]. It shares with the active filter the principle of an active cancellation of harmonic content, but differs from it in the absence of processing and amplification of signal. The new concept that DC side harmonics elimination proposes is based on direct reinjection of the voltage ripple in series with the DC line. The paper analyses the operation of the proposed scheme and provides experimental verification in a six pulse scaled down model of an Ac/DC converter link with a PWM inverter feed. In many cases a smothing reactor is used in the output of a rectifier to eliminate the current harmonic. It is typical in the use of this type of reactor in series between the rectifier and a load, or a power inverter to feed a machine AC. The concept proposed here is not pulse-related and unlike the earlier DC side harmonic reinjection scheme, only attenuates the DC side harmonics. It is, however, considerably simpler than the above alternatives since it does not involve any switching devices. The proposal uses a transformer whose secondary it is connected in a similar way to the smothing reactor mentioned previously. For this secondary one circulates the direct current and also the harmonics current, but in opposed phase with the object of eliminating harmonics content. In the filter, it is also necessary to include a capacitor in the transformer primary circuit in order to block the DC voltage.

   High Power Factor High Efficiency GTO Rectifier for Locomotive Application
By J. Bou Saada; P. Colignon; L. Delporte; P. Thomas; P. Mathys; M. Osée [View]
[Download]

Abstract: This paper deals with the design of a bi-directional rectifier supplying the DC link of an asynchronous traction drive for locomotive. The need of a trade-off between the main constraints (Power factor, weight and efficiency) is established. Different solutions are presented and compared to the first design presented in a previous paper.

   On Output Capacitor Size in Boost-Type Power-Converters with Constant Power
By A. Carlsson; M. Alaküla; L. Gertmar [View]
[Download]

Abstract: The back-to-back converter has interesting properties. The controlled rectifier makes it possible to simulate a purely resistive load. Further, the DC-link voltage regulation makes it possible to reduce the DC-link capacitor to about 4 µF per kW nominal power. With this capacitor size, however, the converter can not normally handle grid imbalance and voltage distortion while simulating a resistive load. By using the load to regulate the DC-link voltage, transferring power variations to the load, the reduced capacitor will not limit the capability to handle distortion and imbalance. This strategy also enables the converter to continue operation through power dropouts. By automatically using energy stored in the load inertia to keep up the dc-link voltage, the converter can stay alive for several seconds, depending on the load characteristic.

   ONIX 3000: an IGBT Drive Directly Coupled to the 3kV Catenary for Railway Application
By J-M. Bodson; J. Bou Saada; A. Colasse; P. Mathys; M. Osée [View]
[Download]

Abstract: The paper deals with the design and realisation of an IGBt inverter, directly coupled to the 3kV catenary, for railway applications. Important aspects of the design (gate drive, protection, insulation and cooling) are presented through simulations and measurements on the test bench. A prototype is mounted in an EMU for field tests on Belgian trracks.

   Pulsed DC Bus Composite Converters
By M. A. de Rooij; J. A. Ferreira; J. D. Van Wyk [View]
[Download]

Abstract: A low frequency pulsating DC bus is proposed as an alternative to a DC bus or a high frequency AC bus as a link voltage in compound converters. The Pulsed DC Bus is realised with the partial series resonant converter, which also provides galvanic isolation. Using the pulsed DC bus as an input to an inverter reduces the output filter requirement because the link voltage of the DC Bus is shaped according to the output requirements. Further advantages are unity power factor and low switching losses due to the soft switching requirements of the Partial Series Resonant Converter. The Pulsed DC bus is applied to a single phase AC to AC converter and a three phase front end converter in the paper.

   PWM Schemes for 3-phase Current Source Inverter in Photovoltaic Power System
By S. Iida; H. Fujikawa; S. Masukawa [View]
[Download]

Abstract: PWM control schemes for a three-phase current source inverter in the photovoltaic power system interconnected to the utility are investigated. As the conventional PWM control scheme for applying to the motor drive systems cannot adjust the PV-array voltage, the novel PWM control schemes are discussed so as to carry out the MPPT control, that is, the maximum power point tracking control, for the PV-array. Three schemes are proposed in this paper and the several characteristics in those control schemes are examined. As a result, by employing the final proposed method, the MPPT control can be easily realized and the ac currents with lower distortions can be outputted from the inverter into the utility systems.

   Reduction of Losses in the DC Link Capacitor of Two-Stage Self-Commutated Converters
By L. Sack [View]
[Download]

Abstract: The main part of the losses in DC link capacitors are caused by the AC current through the capacitor due to its equivalent series resistor. If a self-commutated converter consists of an input stage and an output stage, the AC current of the DC link capacitor can be reduced by synchronization of the pulse patterns of both stages. The paper describes the reduction for different converter topologies and shows this effect by experimental results for a converter with single-phase and three-phase input-stage. The advantages are the rise of life time expectancy and minimized capacity in the DC link.

   Sine-Wave Voltage Inverter for Variable Speed Cage Induction Motor Drive System
By W. Koczara; R. Seliga; J. Matraszek [View]
[Download]

Abstract: The paper describes topology and control of three-phase dc-to-ac converter for variable speed cage induction machine. The proposed dc-to-ac four quadrant converter provides wide range frequency and amplitude sinusoidal voltage. The sinusoidal voltage is produces by PWM modulation, passive LC filter and control system. The multiloop controller consists of voltage controller and a current controller. Simulation and experimental results have been given to verify the proposed topology and the control scheme. The results confirm the practical feasibility of the topology and control system.

   Sliding Mode Control Strategy Applied to Parallel-connected Converter
By M. López; L. García de Vicuña; M. Castilla; O. López; J. Matas [View]
[Download]

Abstract: This paper presents a control strategy for the design of feedback loops in modular power systems (MPS) using sliding mode techniques. The design process is based on a reduced bilinear model of the MPS that allows to deduce constraints that must be satisfied by the sliding surfaces, independently of the number of modules that constitute the structure.

   Sliding-LQR Based Control of DC-DC Converters
By J. Matas; L. Garcia de Vicuña; O. López; M. López; M. Castilla [View]
[Download]

Abstract: This paper proposes a sliding-LQR (Linear Quadratic Regulator) control method for DC-DC converters. The coefficients of the linear sliding control surfaces are obtained using LQR theory. This method has been applied to a buck, boost, buck-boost and SEPIC converter and a modular power system. The simulation and experimental results show a good dynamic behavior during the start-up transient response and against load and input voltage perturbations.

   Study of Direct Series Connection of IGBT for a 3kV Chopper
By J-M. Bodson; J. Bou Saada; A. Colasse; P. Colignon; L. Delporte; J-E Masselus; P. Mathys; M. Osée [View]
[Download]

Abstract: The paper deals about voltage balancing of two series-connected IGBT. Several methods have been investigated by simulations and are compared. The final solution is an active clamping on each IGBT with a feedback between collector and gate. This solution is presented in detail and has been tested on prototypes.

   Three-phase PWM AC Line Conditioner Based on the Cúk Converter Topology: Study of the Basic Energetic Properties
By Z. Fedyczak; R. Strzelecki; K. Skórski [View]
[Download]

Abstract: This paper deals with PWM AC line conditioners with a hybrid "power electronics autotransformer (PEA)" based on Cúk converter topology. As distinct from the matrix PEA, the hybrid PEA contains additional passive elements similar to DC/DC converter topologies. The presented PEA has the capability to increase the AC load voltage or current above the AC line supplying voltage or current without an electromagnetic transformer. This paper discusses the basic energetic properties of PWM AC line conditioners with the hybrid PEA. Some interesting simulation and experimental results, obtained from a 500 VA laboratory model, along with theoretical analysis, are shown to study the viabilities for effective applications of such PWM AC line conditioners.

EPE 1999 - Topic 02b: Power Converter Circuits and Control
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1999 - Conference > EPE 1999 - Topic 02: POWER ELECTRONICS CONVERTER CIRCUITS > EPE 1999 - Topic 02b: Power Converter Circuits and Control
	[return to parent folder]

	A 160 A IGBT Welding Power Source with 100 kHz Output Switching F... By E. Lourenço; E. Margato; P. Verdelho	[View] [Download]
Abstract: In this paper a welding power source using electronic power conversion techniques is described. A dc current power source gives 160 A under a maximum 35 V arc voltage. The power input may be obtained directly from the public electricity supply network through a AC-DC voltage rectifier. The transformer primary coil voltage is obtained by a 50 kHz full wave IGBT Voltage Source Inverter (VSI). The welding current rectification is obtained by a full wave diode bridge operating after the transformer secondary coil. This topology will allow maximum output dc current grow factors and a output switching frequency of 100 kHz. Applying non-linear control techniques a very fast dynamic for the dc current control is obtained without steady state error and with low current ripple. This process has however the drawback of requiring a average current control external loop of the transformer primary side, with the propose of prevent the emergence of a dc component. A relative simple control circuit is obtained.

	A Full Regulated Two Output Forward Converter with a Novel Parallel Regulation Technique By A. Ferreres; J. A. Carrasco; A.E. Navarro; R. García; E. J. Dede	[View] [Download]
Abstract: The complete elimination of cross-regulation in PWM multiple-output converters requires post-regulation. For medium-high output currents the more usual post-regulators are: the PWM regulators in cascade, the magamp, and the synchronous switch post-regulators (SSPR) [1]. The last two are very efficient but their actuation can only reduce the duty cycle and the design of the magamp control loop is difficult due to the presence of non linear elements and a phase delay [2][3]. For high outputs currents an alternative for the elimination of cross-regulation is the parallel post-regulator with controlled transformer [4] [5], this combines a good efficiency and the easiness of design of classical switching power supplies. The idea is based on handling only a percentage of the power delivered by the output in order to regulate it. By using the transformer the post-regulator adds a positive or negative voltage to the output filter and adjusts the voltssecond balance. The model for a parallel post-regulator is not described for PWM converters. This paper describes the post-regulation strategy for obtaining two outputs independently regulated, and presents a model to obtain the control transfer function and the expressions of cross-impedances.

	A Matrix Converter with Space Vector Control Enabling Overmodulation By J. Mahlein; O. Simon; M. Braun	[View] [Download]
Abstract: In this paper the design and testing of a matrix converter using a new method of vector overmodulation is described. The selection of the bi-directional switches as a main part of the converter is discussed and an overview of admissible commutation switching sequences is given. The theoretical output voltage limit which is 86.6% of the input voltage on sinusoidal operation can be increased up to 105%. Using overmodulation means to stress the grid and the load with non sinusoidal currents for higher voltage transfer ratio.

	A New Conception of a Battery Regulation Unit for Mini-Satellites By A.E. Navarro; J.A. Carrasco; E. Maset; A. Ferreres; E.J. Dede	[View] [Download]
Abstract: This paper describes the conception and design of a new battery regulation unit (BRU) for a minisatellite with a regulated voltage bus. Normally a mini-satellite has two converters, one working as a battery charge regulator and another working as a battery discharge regulator. This paper proposes to use one converter for both working modes that can be use either if the battery voltage is over or down the bus voltage, characteristic that increases the modularity on the mini-satellite design, maintaining the normal efficiency and reliability required by the space agencies. These properties are verifyed with experimental results.

	A New Topology for PWM Current Source Inverter with IGBT By R. Mecke; U. Riefenstahl; B. Neumann	[View] [Download]
Abstract: At the moment PWM current source inverters are equiped with GTO-thyristors and used for asynchronous drives in the power range between 1.5 and 13.5 megawatt. An essential problem of these inverter topology are the interactions between the impedance and the filter capacitors on the line and motor side. These oscillating circuits can be excited by low order harmonics and by the switching frequency and can cause instable operation of the drive. The paper presents a new topology for PWM current source inverters. In comparison to the conventional inverter circuit it enables a considerable reduction of the filter capacitors and therefore a decrease of the inverter size. Moreover the small filter capacities create high resonance frequencies of several kilohertz, which cannot be excited by low order harmonics. Thats why the resonance problems on the line and motor side can be avoided, the field oriented control can be strongly simplified and the dynamic behaviour of the drive system can be improved. A condition for this are switching frequencies of several kilohertz, which can be realized for instance by using IGBT. The function of the new inverter topology was proved by simulation and experiment. Some results are shown.

	An Overcurrent Portection Coordination in Converters with IGBT Transistors By S. Januszewski; K. Zymmer	[View] [Download]
Abstract: The explosion strength of high power IGBT modules is one of the important parameters that may decide on converter equipment reliability in extreme circumstances. Service conditions connected with explosion hazard of these modules dangerous for converter accessories and personal safety is discussed. Principles of overcurrent protection coordination in medium and high power IGBT converters taking into account this phenomenon is considered.

	Characterization of Semiconductor Losses in Series Resonant DC-DC... By H. Reinold; M. Steiner	[View] [Download]
Abstract: The well known series resonant DC-DC converter with galvanic insulation realizes zero current switching (ZCS). Semiconductor losses can be optimized through changing the blanking time. The use of a transformer with extremely low leakage inductance (e.g. coaxial winding transformer) leads to an unconventional commutation process that results in very low switching losses even in non ZCS mode which will be described in this paper. This paper compares the semiconductor losses of the different modes of operation (conventional ZCS, ZCS with increased blanking time and without ZCS) as experimental result of a 12kW test setup and of a 200kW prototype converter.

	Digital Control of a Three Phase 4 Wire PWM Inverter for PV Applications By S. El-Barbari; W. Hofmann	[View] [Download]
Abstract: The microcontroller based digital control of a three phase 4 wire PWM inverter for simultaneously supply of three phase and single phase load in transformerless stand alone photovoltaic application with battery energy storage (BES) ald LC output filter is described. An observer is implimented to estimate the load current and to predict the space states for one step ahead. A control method based on the dead beat control algorithm is described to regulate the output voltage of the LC filter so that disturbance of the output voltage due to load unbalances is eliminated. Simulation results for various operation conditions are presented to verify the validity of the control method.

	Fault Tolerant UPF Converters Operating from a Variable Frequency Supply for an Aerospace Application By S. R. Green; D. J. Atkinson; B. C. Mecrow; A. G. Jack	[View] [Download]
Abstract: This paper describes two fault tolerant Unity Power Factor (UPF) converter topologies for operation from an aircraft variable frequency supply. It discusses the reasons for choosing these topologies and the performance of current controllers on a variable frequency supply.

	Harmonic Reduction in DC Link Current of a PWM Drive by Direct Ripple Injection By F. M. Pérez Hidalgo; J. R. Heredia Larrubia; J. L. Durán Paz	[View] [Download]
Abstract: Substitution for DC motors by PWM inverter-fed leads to high harmonics levels in the DC side of the converters. Higher order harmonics can still be a source of electromagnetic interference and often need to be filtered. The conventional solution for the reduction of DC side Harmonics is the passive filter. It is an easy solution but unfortunately the requiered reduction of harmonics leads to a filter of excessive size and weight. It is also an expensive solution. The use of an active filter in combination with the pasive ones has been recently succesfully tried to reduce the higer harmonics content. This paper describes an alternative solution to passive and active filter arrangements on the DC side of the converter [1]. It shares with the active filter the principle of an active cancellation of harmonic content, but differs from it in the absence of processing and amplification of signal. The new concept that DC side harmonics elimination proposes is based on direct reinjection of the voltage ripple in series with the DC line. The paper analyses the operation of the proposed scheme and provides experimental verification in a six pulse scaled down model of an Ac/DC converter link with a PWM inverter feed. In many cases a smothing reactor is used in the output of a rectifier to eliminate the current harmonic. It is typical in the use of this type of reactor in series between the rectifier and a load, or a power inverter to feed a machine AC. The concept proposed here is not pulse-related and unlike the earlier DC side harmonic reinjection scheme, only attenuates the DC side harmonics. It is, however, considerably simpler than the above alternatives since it does not involve any switching devices. The proposal uses a transformer whose secondary it is connected in a similar way to the smothing reactor mentioned previously. For this secondary one circulates the direct current and also the harmonics current, but in opposed phase with the object of eliminating harmonics content. In the filter, it is also necessary to include a capacitor in the transformer primary circuit in order to block the DC voltage.

	High Power Factor High Efficiency GTO Rectifier for Locomotive Application By J. Bou Saada; P. Colignon; L. Delporte; P. Thomas; P. Mathys; M. Osée	[View] [Download]
Abstract: This paper deals with the design of a bi-directional rectifier supplying the DC link of an asynchronous traction drive for locomotive. The need of a trade-off between the main constraints (Power factor, weight and efficiency) is established. Different solutions are presented and compared to the first design presented in a previous paper.

	On Output Capacitor Size in Boost-Type Power-Converters with Constant Power By A. Carlsson; M. Alaküla; L. Gertmar	[View] [Download]
Abstract: The back-to-back converter has interesting properties. The controlled rectifier makes it possible to simulate a purely resistive load. Further, the DC-link voltage regulation makes it possible to reduce the DC-link capacitor to about 4 µF per kW nominal power. With this capacitor size, however, the converter can not normally handle grid imbalance and voltage distortion while simulating a resistive load. By using the load to regulate the DC-link voltage, transferring power variations to the load, the reduced capacitor will not limit the capability to handle distortion and imbalance. This strategy also enables the converter to continue operation through power dropouts. By automatically using energy stored in the load inertia to keep up the dc-link voltage, the converter can stay alive for several seconds, depending on the load characteristic.

	ONIX 3000: an IGBT Drive Directly Coupled to the 3kV Catenary for Railway Application By J-M. Bodson; J. Bou Saada; A. Colasse; P. Mathys; M. Osée	[View] [Download]
Abstract: The paper deals with the design and realisation of an IGBt inverter, directly coupled to the 3kV catenary, for railway applications. Important aspects of the design (gate drive, protection, insulation and cooling) are presented through simulations and measurements on the test bench. A prototype is mounted in an EMU for field tests on Belgian trracks.

	Pulsed DC Bus Composite Converters By M. A. de Rooij; J. A. Ferreira; J. D. Van Wyk	[View] [Download]
Abstract: A low frequency pulsating DC bus is proposed as an alternative to a DC bus or a high frequency AC bus as a link voltage in compound converters. The Pulsed DC Bus is realised with the partial series resonant converter, which also provides galvanic isolation. Using the pulsed DC bus as an input to an inverter reduces the output filter requirement because the link voltage of the DC Bus is shaped according to the output requirements. Further advantages are unity power factor and low switching losses due to the soft switching requirements of the Partial Series Resonant Converter. The Pulsed DC bus is applied to a single phase AC to AC converter and a three phase front end converter in the paper.

	PWM Schemes for 3-phase Current Source Inverter in Photovoltaic Power System By S. Iida; H. Fujikawa; S. Masukawa	[View] [Download]
Abstract: PWM control schemes for a three-phase current source inverter in the photovoltaic power system interconnected to the utility are investigated. As the conventional PWM control scheme for applying to the motor drive systems cannot adjust the PV-array voltage, the novel PWM control schemes are discussed so as to carry out the MPPT control, that is, the maximum power point tracking control, for the PV-array. Three schemes are proposed in this paper and the several characteristics in those control schemes are examined. As a result, by employing the final proposed method, the MPPT control can be easily realized and the ac currents with lower distortions can be outputted from the inverter into the utility systems.

	Reduction of Losses in the DC Link Capacitor of Two-Stage Self-Commutated Converters By L. Sack	[View] [Download]
Abstract: The main part of the losses in DC link capacitors are caused by the AC current through the capacitor due to its equivalent series resistor. If a self-commutated converter consists of an input stage and an output stage, the AC current of the DC link capacitor can be reduced by synchronization of the pulse patterns of both stages. The paper describes the reduction for different converter topologies and shows this effect by experimental results for a converter with single-phase and three-phase input-stage. The advantages are the rise of life time expectancy and minimized capacity in the DC link.

	Sine-Wave Voltage Inverter for Variable Speed Cage Induction Motor Drive System By W. Koczara; R. Seliga; J. Matraszek	[View] [Download]
Abstract: The paper describes topology and control of three-phase dc-to-ac converter for variable speed cage induction machine. The proposed dc-to-ac four quadrant converter provides wide range frequency and amplitude sinusoidal voltage. The sinusoidal voltage is produces by PWM modulation, passive LC filter and control system. The multiloop controller consists of voltage controller and a current controller. Simulation and experimental results have been given to verify the proposed topology and the control scheme. The results confirm the practical feasibility of the topology and control system.

	Sliding Mode Control Strategy Applied to Parallel-connected Converter By M. López; L. García de Vicuña; M. Castilla; O. López; J. Matas	[View] [Download]
Abstract: This paper presents a control strategy for the design of feedback loops in modular power systems (MPS) using sliding mode techniques. The design process is based on a reduced bilinear model of the MPS that allows to deduce constraints that must be satisfied by the sliding surfaces, independently of the number of modules that constitute the structure.

	Sliding-LQR Based Control of DC-DC Converters By J. Matas; L. Garcia de Vicuña; O. López; M. López; M. Castilla	[View] [Download]
Abstract: This paper proposes a sliding-LQR (Linear Quadratic Regulator) control method for DC-DC converters. The coefficients of the linear sliding control surfaces are obtained using LQR theory. This method has been applied to a buck, boost, buck-boost and SEPIC converter and a modular power system. The simulation and experimental results show a good dynamic behavior during the start-up transient response and against load and input voltage perturbations.

	Study of Direct Series Connection of IGBT for a 3kV Chopper By J-M. Bodson; J. Bou Saada; A. Colasse; P. Colignon; L. Delporte; J-E Masselus; P. Mathys; M. Osée	[View] [Download]
Abstract: The paper deals about voltage balancing of two series-connected IGBT. Several methods have been investigated by simulations and are compared. The final solution is an active clamping on each IGBT with a feedback between collector and gate. This solution is presented in detail and has been tested on prototypes.

	Three-phase PWM AC Line Conditioner Based on the Cúk Converter Topology: Study of the Basic Energetic Properties By Z. Fedyczak; R. Strzelecki; K. Skórski	[View] [Download]
Abstract: This paper deals with PWM AC line conditioners with a hybrid "power electronics autotransformer (PEA)" based on Cúk converter topology. As distinct from the matrix PEA, the hybrid PEA contains additional passive elements similar to DC/DC converter topologies. The presented PEA has the capability to increase the AC load voltage or current above the AC line supplying voltage or current without an electromagnetic transformer. This paper discusses the basic energetic properties of PWM AC line conditioners with the hybrid PEA. Some interesting simulation and experimental results, obtained from a 500 VA laboratory model, along with theoretical analysis, are shown to study the viabilities for effective applications of such PWM AC line conditioners.