EPE Association: EPE 1995 - 38 - Dialogue Session DS4b: Electronic Supply Systems (II)

EPE 1995 - 38 - Dialogue Session DS4b: Electronic Supply Systems (II)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1995 - Conference > EPE 1995 - 38 - Dialogue Session DS4b: Electronic Supply Systems (II)

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   FlLTER DESIGN OF MAGNET POWER SUPPLY SYSTEM USING CS PWM CONVERTER
By H.S. Kim; J.H. Choi [View]
[Download]

Abstract: Current Source (CS) PWM converter is appropriate for the magnet power supply system which requests high power and high precision current control. Passive filters should be installed to eliminate the current or voltage harmonics caused by the PWM switching for the CS PWM converter. But the passive filters limit the output DC current range and may destroy the system with filter resonance, and make the system equation more complicate. In this paper, the systematic and simple filter design method which considers not only the harmonic attention but the total system performance also.

   TWO STAGE DC/DC CONVERTER WITH LOW OUTPUT VOLTAGE (3.3V) AND OPTIMIZED SYNCHRONOUS RECTIFICATION STAGE
By J.A. Cobos; O. Garcia; J. Uceda; F. Aldana; J. Sebastian; E. de la Cruz [View]
[Download]

Abstract: A new structure of high power density and high efficiency low output voltage (3.3V) DC/DC converter is proposed in this paper. The connection in series of two power stages provides optimum performance of the synchronous rectification stage with low overall complexity. The performance of this structure is almost independent of the variations of input voltage, because these variations are absorbed by the pre-regulator. Therefore, the driving voltage applied to the self-driven synchronous rectifiers does not depend on input voltage. The high efficiency obtained (91%) in such a low output voltage converter (3.3V/20A) with independence of the input voltage, allows size reduction in on board converters (OBC) for distributed power systems (DPS).

   MODELLING AND SIMULATION OF A POWER FACTOR CORRECTION CIRCUIT BASED ON THE UNITRODE UC3854 INTEGRATED CIRCUIT
By A. R. G. Patterson [View]
[Download]

Abstract: The techniques of power factor correction in order to reduce current harmonics fed back to the power supply utility are well understood. Integrated circuits such as the Unitrode UC3854 have evolved to assist in the design of switching Power Factor Correction techniques. The application of the Saber simulator to such circuits allows a very thorough analysis of the circuit design sensitivities, and potential compliance with the EN60555-2 standard. This type of analysis results in a safer, more robust design.

   STEADY-STATE ANALYSIS OF A CLAMPED-MODE LCC RESONANT INVERTER FOR HID LAMP SUPPLY
By J. M. Alonso; M. Rico; E. Corominas; C. Blanco [View]
[Download]

Abstract: Nowadays, high intensity discharge (HID) lamps appear as an attractive source of light, with high luminous efficacy and reduced size. In this paper, a complete study of the clamped mode LCC resonant inverter is presented, together with some of the control-to-output characteristics obtained, showing the different commutation zones. This inverter results specially adequate to supply HID lamps, where typical output power is above 100 W and the use of four switches is justified. Experimental results obtained from a prototype at the laboratory are also shown to validate the analysis.

   INFLUENCE OF THE MODIFICATIONS OF DIODES CHARACTERISTICS FOR A 200°C-OPERATION QUASI-RESONANT CONVERTER
By P.J. Viverge; J.J. Rousseau; F. Sarrus; J.P. Chante [View]
[Download]

Abstract: The Use of electronics systems at very high temperature (>=200°C) induces important constraints on devices. In this article the consequences of the temperature enhancement on devices are studied in a quasi-resonant power supply. The switch allows soft commutation and is current-bidirectional. The influence of temperature on the complete converter and the implications in the diodes are analysed. This analysIs enables one to define some rules of choice for such applications. With particular precautions, use of classical passive and semiconductor devices is possible above their temperature specifications and the operation of a complete electronics system is feasible at 200°C.

   PRELIMINARY DESIGN APPROACH BY ATP SIMULATION OF THE 18 KV DC TRACTION SYSTEM
By M. Carpita; P. Cesario; P. Farina; O. Ventura [View]
[Download]

Abstract: In this paper the authors propose a feasibility analysis of the high voltage DC feeding system for an electric plant. High DC voltage application in traction power supply system may be interesting if compared with 15 KV 16. 2/3 Hz or 25 KV 50 Hz for many reasons: the lower harmonic contents and the consequent reduction of electromagnetic interference; the possibility to have higher distance between electric substations; the symmetry of power consumption from the main line. The development high cost of the test plant is not justified due to the low compatibility and possibility of integration with the other supply systems working all around the world. From the other side, high voltage in DC traction may be of some interest in many situations such as mines lines where a high power per Km supplied by a reduced number of substations is requested. This study is based on the complete model of two electric substations and of the fed traction track. Substations are made by four parallel conversion groups each of them made of two twelve pulse thyristor rectifier series connection. Simulation result analysis can demonstrate the system feasibility. The simulation program is EMTP/ATP.

   A HIGH FREQUENCY POWER SUPPLY SYSTEM FOR NON-LINEAR LOADS
By A. Kern; B. Yu [View]
[Download]

Abstract: Tubular fluorescent lamps used in industrial printing machines are powered by conventional transformers. These configurations have severe disadvantages concerning maintenance, space requirements and energy efficiency. In this paper a system is presented which eliminates these disadvantages and makes it possible to control the luminous flux of the fluorescent lamp over a wide range. The power supply system requires approximately the same space as a standard PC-switching power supply device of about 300W. The applied concepts will be explained and accompanied by practical results.

   THE PARALLEL OPERATION OF INVERTERS SUPPLYING INDUCTION HEATING LOADS
By A.M. Green; A.C. Williamson [View]
[Download]

Abstract: A novel method of induction heating has been proposed which requires that a number of coils, supplied by separate inverters of differing frequencies, heata common workpiece. An undesirable mutual inductance exists between each of the. electrically separate coils, the magnitude of which is dependent on coil geometry and the type of workload being heated. This mutual inductance causes a voltage to be induced into the cpils. The freguency of this induced voltage, for a given coil, differs from the frequency of the inverter connected to that coil. This paper describes the investigation of the effects of the induced voltage on the operation of different inverters encountered in high-power induction heating applications. The simulation package, PSPICE, was used to develop models of load-commutated and selfcommutated inverters and simulate the operation of two inverters supplying loads of the type described above. Load-commutated inverters were found to be particularly sensitive to the mutually injected voltage, with commutation failures occurring for quite small values of mutual coupling. Experimental verification of the simulation was obtained using a 300kW selfcommutated inverter and a 450kW load-commutated inverter.

   A 1 KW HIGH PERFORMANCE CONVERTER FOR 120 V BUS REGULATION
By Christian Elisabelar; Laurent Jarry [View]
[Download]

Abstract: The study of a 1 kW converter for 120 V bus regulation in a spatial application is proposed. Several converters based on the full bridge inverter topology are evaluated as classic PWM hard switching converter, serie resonant, ZVT PWM, Phase Shift PWM with or without active snubber. Particularly, different full-bridge phase-shift PWM converters that present the best performance are studied and compared. The active controlled clamp option allowing ZVS operation and high efficiency is selected. Then, the study and design of this converter is made, completed by experimental results on 1kW, 100kHz converter. Impacts of the clamp switch command on the efficiency and performance from low load to full load are analysed and tested.

   DC-DC CONVERTER WITH NO MAGNETIC ELEMENTS AND GOOD REGULATION FOR LARGE CHANGES IN LINE AND LOAD
By G. Y. Zhu; A. Ioinovici [View]
[Download]

Abstract: A new type of DC power supply, containing only switches and capacitors, but no inductors or transformers, is presented. All the elements of the converter, but the capacitors, can be implemented in Integrated-Circuit (lC) technlology. Thus, the proposed power supply is characterized by low weight, small size and high power density. An original switching sequence is designed by dividing each switching cycle into eight stages. Four of the stages are for regulation purpose only. As a result, the new DC-DC regulator provides constant output voltage despite large variation in input voltage or load. The capacitors are grouped in two subcircuits; in each half-cycle, one of the subcircuits operates in the charging mode (from the input Voltage) and the other one in the discharging mode (on the load); their role is interchanged in the subsequent halfcycle. An optimum design of the values of the switching period and of capacitors assures a small ripple in the output voltage.

   A NEW ZERO-CURRENT-SWITCHING SERIES RESONANT lNVERTER TOPOLOGY
By M. Chindris; S. Stefanescu [View]
[Download]

Abstract: The paper aims to introduce a new zero-current-switching (ZCS) series resonant inverter (SRI) topology. This inverter includes an input inductor, two switches, one bidirectional voltage switch and the other bidirectional current, the resonant path and the load. The main advantages of the proposed inverter are as follows: simple structure of the power and control circuits, high frequency operation, soft switching at turn-on/off of the power devices; connected with a non-controlled rectifier as power source, the inverter forms a resonant converter practically having a unity ac power factor. The paper presents the basic principles and the theoretical analysis of the inverter behavior, some considerations on the commutation and turn-off switches losses. the Pspice simulation and a few experimental waveforms of a resonant converter including the proposed inverter.

   800 kW FOUR QUADRANT AMPLIFIER WITH LARGE FULL SIGNAL BANDWIDTH AND LOW RIPPLE CONSISTING OF IGBT's AND ACTIVE FILTER
By L.A.E. van Lieshout [View]
[Download]

Abstract: In the field of fusion experiments four quadrant converters are needed for the purpose of plasma stabilisation. The inductive load requires a voltage modulation on top of a relative slowly variying current. The power supply frequency response is usually in the order of 3 to 5 kHz, depending on the size of the fusion machine. The demand, as to the output voltage ripple is at an extremely low level (500 ppm). The output power of the amplifier discussed is 800 kW. This paper describes the application of a four quadrant IGBT bridge with passive filter and a linear MOSFET active filter for the purpose of frequency voltage modulation. IGBT bridge voltage control around zero output voltage is critical. A comparision is made with two other possible power supply concepts.

   COMPARISON BETWEEN TWO NEW SOFT SWITCHING TECHNICS ADAPTED TO HIGH FREQUENCY CONVERTERS
By W. Abida; D. Sadamac; S. d'Almeida; M. Rocher; O. Daluz; M. Perelle [View]
[Download]

Abstract: This paper presents two new high frequency DC-DC power converters. They are regulated at constant frequency by the pulse width modulation (PWM) technic. These converters are derived from the classical PWM phase-shifted converter by adding two impulsive current sources to achieve soft switching operation. These impulsive current sources are obtained by two new different technics, the first is built by an association of LC branches and the second one with saturable inductors. These two technics are presented and compared. The theoretical analysis and experimental results of two 2kW prototypes of the converter operating at 1Mhz are given.

   IMPROVING ELECTRONIC SIMULATION ACCURACY BY USING NEW EQUIVALENT CIRCUITS FOR WOUND COMPONENTS
By F. Blache; J.P. Keradec ; J.-L. Schanen [View]
[Download]

Abstract: Recently, representation of wound passive components by electrical equivalent circuit improved drastically. We show here how to take advantage of these advances during the electronic simulation phase. For a power electronic circuit, several results of simulation are compared to experimental measurements. Improvements related to the quality of wound component models are brought to the fore.

   MODELLING AND SIMULATION OF PWM POWER SOURCE
By J. Przybylski; W. Koczara; E.B. Patterson; D. Morley [View]
[Download]

Abstract: A simulation study controlled single-phase (Constant Voltage Constant Frequency CVCF) is presented. The control system was designed as digital Application Specific Integrated Circuit (ASIC). Different load circuits have been investigated linear and non-linear loads. A similation study and laboratory tests are presented.

   Assessment, Modelling and Simulation of an EDM Power Supply using Saber
By P.R. Holme; C.D. Manning [View]
[Download]

Abstract: An assessment is made of the power supply requirements for the next generation of high precision, high response EDM systems. A buck derived topology with digital current mode control is proposed and modelled using Saber. Simulation results are presented which confmn the suitability of this topology for use in EDM.

   PROGRAMMABLE POWER MODULE
By J. Jelonkiewicz; J. Ludwin [View]
[Download]

Abstract: A new concept of the intelligent power module is presented in the paper. The power module is a switched mode voltage converter which function can be easy programmed to obtain required direction of energy flow and parameters to be stabilised. If more energy conversion is required, modules can be connected and information between them can be interchanged via serial interface. The modules are designed for different voltage and current capabilities, thus forming a family of efficient converters enables to change one voltage waveform to any other required.

   A RESONANT POWER SUPPLY FOR DISTRIBUTED SYSTEMS
By A. Nagel; K. Backhaus; H. Reinold [View]
[Download]

Abstract: Mechanical engineering develops a rising demand for reliable, easy-to-use power supplies, which are short-circuit proof, electrically isolated and possesses the capability to transmit energy to moving parts of a machine. As a solution this paper describes a distributed mid-frequency range AC power system consisting of resonant DC-DC converters and ferrite transformers for a power range of up to 100 kW. Experimental results of such a system integrated in a 7 axis robot are presented.

   ANALYSIS OF THE LCL-RESONANT CONVERTER OPERATING ABOVE RESONANCE
By Kh. Louati; W. Abida; D. Sadarnac [View]
[Download]

Abstract: The LCL-type resonant converter (LCL-RC) has more desirable features than the conventional parallel resonant converter (PRC), such as the small frequency range and the reduced circulating current in the inverter. A steady state analysis of the converter operated above resonance gave a set of characteristic curves from which a systematic design procedure is developed. In order to get good efficiency, an optimum design result is obtained by minimizing the energy in the inductors and maximizing the current gain of the LCL-resonant circuit. Experimental results of prototype of a 750 watt-500 KHz full bridge LCL-RC are also presented.

   DESIGN TRADE-OFFS IN A BOOST TOPOLOGY USED AS A PF CONTROLLER
By A.Martinez; D. Abud; J. A. Cobos; J. Sebastian; J. Uceda; J. Arau [View]
[Download]

Abstract: In the last decade, the number of electronics equipments connected to the AC line has been increased; these equipments present low values of Poyver Factor (PF) and high Total Harmonic Distortion (THD) due to their non-linear behavior [1]. Boost topology has been widely used as PF controller due to its step-up voltage conversion ratio, continuous input current, simple topology, and high efficiency. For high voltage applications, the major concerns of the conventional boost converter are the losses on the power devices, which will affect converter cost and efficiency. In this document, the experimental results of a Boost converter build as a PF controller, are presented. Besides, an analysis of the design compromises to keep in mind in order to develop a PF controller, for the Boost topology case, has been included in this paper. This analysis evaluates the compromises that must be considered when in the design of a PF Controller, we try to obtain the best Power Factor (PF), Total Harmonic Distortion (THD) and construction cost.

   FAULT TOLERANCE IN DISTRIBUTED POWER SYSTEMS
By R.V. White [View]
[Download]

Abstract: The demand for continuously available information processing systems increases every day. Transaction processing, communications systems, and critical processes all require non-stop, fault tolerant operation. There are four steps to achieving fault tolerance in any system. However, no system will operate without a supply of electrical power. This paper is a tutorial that reviews the four principles of fault tolerance. Special considerations for high availability and fault tolerance in distributed power systems are highlighted.

   TOPOLOGIES FOR HIGH POWER FACTOR THREE-PHASE AC-TO-DC CONVERTER
By B.-R. Lin; T.-S. Hwang [View]
[Download]

Abstract: This paper reviews and describes techniques for three-phase ac-to-dc converter with near unity power factor. The system consists of three-phase ac source and three-phase full bridge rectifier, power stage of the converter, dc link capacitor and load. It is proposed to achieve high performance and simple control circuit. The output voltage can be maintained above or below the peak ac input voltage by changing the duty cycle of the active switch. The PWM and resonant switch classification, ac-to-dc converter circuit topology, design of control circuit, small-signal modeling for continuous conduction mode (CCM) and discontinuous conduction mode (DCM), experimental results are reviewed and discussed in this paper.

   A COMBINED-GRAPH APPROACH - OBTAINING MODELS OF DC-DC PWM CONVERTERS BY AVERAGING AND INCREMENTAL REPRESENTATION
By M.S. Makowski [View]
[Download]

Abstract: The well adopted approach to analysing DC and low-frequency behaviour of PWM DC-DC converters is through the notion of state-space averaged-circuit models. In this paper a related approach is exploited. It starts directly from the circuit graph and topological matrix description but in contrary to previous contributions it is proposed here to split the models in two distinct categories: the incremental model (introduced in this paper) and the averaged model (adopted in the literature) depending on whether the topological degeneracies are present or not in the converter graphs, respectively. A unified-form combined-graph model is proposed resulting in the reduced number of system equations and simplest possible means for evaluating DC and AC network functions. Illustrative DC modelling examples concerning nondegenerate, semidegenerate and degenerate converters are included.

EPE 1995 - 38 - Dialogue Session DS4b: Electronic Supply Systems (II)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1995 - Conference > EPE 1995 - 38 - Dialogue Session DS4b: Electronic Supply Systems (II)
	[return to parent folder]

	FlLTER DESIGN OF MAGNET POWER SUPPLY SYSTEM USING CS PWM CONVERTER By H.S. Kim; J.H. Choi	[View] [Download]
Abstract: Current Source (CS) PWM converter is appropriate for the magnet power supply system which requests high power and high precision current control. Passive filters should be installed to eliminate the current or voltage harmonics caused by the PWM switching for the CS PWM converter. But the passive filters limit the output DC current range and may destroy the system with filter resonance, and make the system equation more complicate. In this paper, the systematic and simple filter design method which considers not only the harmonic attention but the total system performance also.

	TWO STAGE DC/DC CONVERTER WITH LOW OUTPUT VOLTAGE (3.3V) AND OPTIMIZED SYNCHRONOUS RECTIFICATION STAGE By J.A. Cobos; O. Garcia; J. Uceda; F. Aldana; J. Sebastian; E. de la Cruz	[View] [Download]
Abstract: A new structure of high power density and high efficiency low output voltage (3.3V) DC/DC converter is proposed in this paper. The connection in series of two power stages provides optimum performance of the synchronous rectification stage with low overall complexity. The performance of this structure is almost independent of the variations of input voltage, because these variations are absorbed by the pre-regulator. Therefore, the driving voltage applied to the self-driven synchronous rectifiers does not depend on input voltage. The high efficiency obtained (91%) in such a low output voltage converter (3.3V/20A) with independence of the input voltage, allows size reduction in on board converters (OBC) for distributed power systems (DPS).

	MODELLING AND SIMULATION OF A POWER FACTOR CORRECTION CIRCUIT BASED ON THE UNITRODE UC3854 INTEGRATED CIRCUIT By A. R. G. Patterson	[View] [Download]
Abstract: The techniques of power factor correction in order to reduce current harmonics fed back to the power supply utility are well understood. Integrated circuits such as the Unitrode UC3854 have evolved to assist in the design of switching Power Factor Correction techniques. The application of the Saber simulator to such circuits allows a very thorough analysis of the circuit design sensitivities, and potential compliance with the EN60555-2 standard. This type of analysis results in a safer, more robust design.

	STEADY-STATE ANALYSIS OF A CLAMPED-MODE LCC RESONANT INVERTER FOR HID LAMP SUPPLY By J. M. Alonso; M. Rico; E. Corominas; C. Blanco	[View] [Download]
Abstract: Nowadays, high intensity discharge (HID) lamps appear as an attractive source of light, with high luminous efficacy and reduced size. In this paper, a complete study of the clamped mode LCC resonant inverter is presented, together with some of the control-to-output characteristics obtained, showing the different commutation zones. This inverter results specially adequate to supply HID lamps, where typical output power is above 100 W and the use of four switches is justified. Experimental results obtained from a prototype at the laboratory are also shown to validate the analysis.

	INFLUENCE OF THE MODIFICATIONS OF DIODES CHARACTERISTICS FOR A 200°C-OPERATION QUASI-RESONANT CONVERTER By P.J. Viverge; J.J. Rousseau; F. Sarrus; J.P. Chante	[View] [Download]
Abstract: The Use of electronics systems at very high temperature (>=200°C) induces important constraints on devices. In this article the consequences of the temperature enhancement on devices are studied in a quasi-resonant power supply. The switch allows soft commutation and is current-bidirectional. The influence of temperature on the complete converter and the implications in the diodes are analysed. This analysIs enables one to define some rules of choice for such applications. With particular precautions, use of classical passive and semiconductor devices is possible above their temperature specifications and the operation of a complete electronics system is feasible at 200°C.

	PRELIMINARY DESIGN APPROACH BY ATP SIMULATION OF THE 18 KV DC TRACTION SYSTEM By M. Carpita; P. Cesario; P. Farina; O. Ventura	[View] [Download]
Abstract: In this paper the authors propose a feasibility analysis of the high voltage DC feeding system for an electric plant. High DC voltage application in traction power supply system may be interesting if compared with 15 KV 16. 2/3 Hz or 25 KV 50 Hz for many reasons: the lower harmonic contents and the consequent reduction of electromagnetic interference; the possibility to have higher distance between electric substations; the symmetry of power consumption from the main line. The development high cost of the test plant is not justified due to the low compatibility and possibility of integration with the other supply systems working all around the world. From the other side, high voltage in DC traction may be of some interest in many situations such as mines lines where a high power per Km supplied by a reduced number of substations is requested. This study is based on the complete model of two electric substations and of the fed traction track. Substations are made by four parallel conversion groups each of them made of two twelve pulse thyristor rectifier series connection. Simulation result analysis can demonstrate the system feasibility. The simulation program is EMTP/ATP.

	A HIGH FREQUENCY POWER SUPPLY SYSTEM FOR NON-LINEAR LOADS By A. Kern; B. Yu	[View] [Download]
Abstract: Tubular fluorescent lamps used in industrial printing machines are powered by conventional transformers. These configurations have severe disadvantages concerning maintenance, space requirements and energy efficiency. In this paper a system is presented which eliminates these disadvantages and makes it possible to control the luminous flux of the fluorescent lamp over a wide range. The power supply system requires approximately the same space as a standard PC-switching power supply device of about 300W. The applied concepts will be explained and accompanied by practical results.

	THE PARALLEL OPERATION OF INVERTERS SUPPLYING INDUCTION HEATING LOADS By A.M. Green; A.C. Williamson	[View] [Download]
Abstract: A novel method of induction heating has been proposed which requires that a number of coils, supplied by separate inverters of differing frequencies, heata common workpiece. An undesirable mutual inductance exists between each of the. electrically separate coils, the magnitude of which is dependent on coil geometry and the type of workload being heated. This mutual inductance causes a voltage to be induced into the cpils. The freguency of this induced voltage, for a given coil, differs from the frequency of the inverter connected to that coil. This paper describes the investigation of the effects of the induced voltage on the operation of different inverters encountered in high-power induction heating applications. The simulation package, PSPICE, was used to develop models of load-commutated and selfcommutated inverters and simulate the operation of two inverters supplying loads of the type described above. Load-commutated inverters were found to be particularly sensitive to the mutually injected voltage, with commutation failures occurring for quite small values of mutual coupling. Experimental verification of the simulation was obtained using a 300kW selfcommutated inverter and a 450kW load-commutated inverter.

	A 1 KW HIGH PERFORMANCE CONVERTER FOR 120 V BUS REGULATION By Christian Elisabelar; Laurent Jarry	[View] [Download]
Abstract: The study of a 1 kW converter for 120 V bus regulation in a spatial application is proposed. Several converters based on the full bridge inverter topology are evaluated as classic PWM hard switching converter, serie resonant, ZVT PWM, Phase Shift PWM with or without active snubber. Particularly, different full-bridge phase-shift PWM converters that present the best performance are studied and compared. The active controlled clamp option allowing ZVS operation and high efficiency is selected. Then, the study and design of this converter is made, completed by experimental results on 1kW, 100kHz converter. Impacts of the clamp switch command on the efficiency and performance from low load to full load are analysed and tested.

	DC-DC CONVERTER WITH NO MAGNETIC ELEMENTS AND GOOD REGULATION FOR LARGE CHANGES IN LINE AND LOAD By G. Y. Zhu; A. Ioinovici	[View] [Download]
Abstract: A new type of DC power supply, containing only switches and capacitors, but no inductors or transformers, is presented. All the elements of the converter, but the capacitors, can be implemented in Integrated-Circuit (lC) technlology. Thus, the proposed power supply is characterized by low weight, small size and high power density. An original switching sequence is designed by dividing each switching cycle into eight stages. Four of the stages are for regulation purpose only. As a result, the new DC-DC regulator provides constant output voltage despite large variation in input voltage or load. The capacitors are grouped in two subcircuits; in each half-cycle, one of the subcircuits operates in the charging mode (from the input Voltage) and the other one in the discharging mode (on the load); their role is interchanged in the subsequent halfcycle. An optimum design of the values of the switching period and of capacitors assures a small ripple in the output voltage.

	A NEW ZERO-CURRENT-SWITCHING SERIES RESONANT lNVERTER TOPOLOGY By M. Chindris; S. Stefanescu	[View] [Download]
Abstract: The paper aims to introduce a new zero-current-switching (ZCS) series resonant inverter (SRI) topology. This inverter includes an input inductor, two switches, one bidirectional voltage switch and the other bidirectional current, the resonant path and the load. The main advantages of the proposed inverter are as follows: simple structure of the power and control circuits, high frequency operation, soft switching at turn-on/off of the power devices; connected with a non-controlled rectifier as power source, the inverter forms a resonant converter practically having a unity ac power factor. The paper presents the basic principles and the theoretical analysis of the inverter behavior, some considerations on the commutation and turn-off switches losses. the Pspice simulation and a few experimental waveforms of a resonant converter including the proposed inverter.

	800 kW FOUR QUADRANT AMPLIFIER WITH LARGE FULL SIGNAL BANDWIDTH AND LOW RIPPLE CONSISTING OF IGBT's AND ACTIVE FILTER By L.A.E. van Lieshout	[View] [Download]
Abstract: In the field of fusion experiments four quadrant converters are needed for the purpose of plasma stabilisation. The inductive load requires a voltage modulation on top of a relative slowly variying current. The power supply frequency response is usually in the order of 3 to 5 kHz, depending on the size of the fusion machine. The demand, as to the output voltage ripple is at an extremely low level (500 ppm). The output power of the amplifier discussed is 800 kW. This paper describes the application of a four quadrant IGBT bridge with passive filter and a linear MOSFET active filter for the purpose of frequency voltage modulation. IGBT bridge voltage control around zero output voltage is critical. A comparision is made with two other possible power supply concepts.

	COMPARISON BETWEEN TWO NEW SOFT SWITCHING TECHNICS ADAPTED TO HIGH FREQUENCY CONVERTERS By W. Abida; D. Sadamac; S. d'Almeida; M. Rocher; O. Daluz; M. Perelle	[View] [Download]
Abstract: This paper presents two new high frequency DC-DC power converters. They are regulated at constant frequency by the pulse width modulation (PWM) technic. These converters are derived from the classical PWM phase-shifted converter by adding two impulsive current sources to achieve soft switching operation. These impulsive current sources are obtained by two new different technics, the first is built by an association of LC branches and the second one with saturable inductors. These two technics are presented and compared. The theoretical analysis and experimental results of two 2kW prototypes of the converter operating at 1Mhz are given.

	IMPROVING ELECTRONIC SIMULATION ACCURACY BY USING NEW EQUIVALENT CIRCUITS FOR WOUND COMPONENTS By F. Blache; J.P. Keradec ; J.-L. Schanen	[View] [Download]
Abstract: Recently, representation of wound passive components by electrical equivalent circuit improved drastically. We show here how to take advantage of these advances during the electronic simulation phase. For a power electronic circuit, several results of simulation are compared to experimental measurements. Improvements related to the quality of wound component models are brought to the fore.

	MODELLING AND SIMULATION OF PWM POWER SOURCE By J. Przybylski; W. Koczara; E.B. Patterson; D. Morley	[View] [Download]
Abstract: A simulation study controlled single-phase (Constant Voltage Constant Frequency CVCF) is presented. The control system was designed as digital Application Specific Integrated Circuit (ASIC). Different load circuits have been investigated linear and non-linear loads. A similation study and laboratory tests are presented.

	Assessment, Modelling and Simulation of an EDM Power Supply using Saber By P.R. Holme; C.D. Manning	[View] [Download]
Abstract: An assessment is made of the power supply requirements for the next generation of high precision, high response EDM systems. A buck derived topology with digital current mode control is proposed and modelled using Saber. Simulation results are presented which confmn the suitability of this topology for use in EDM.

	PROGRAMMABLE POWER MODULE By J. Jelonkiewicz; J. Ludwin	[View] [Download]
Abstract: A new concept of the intelligent power module is presented in the paper. The power module is a switched mode voltage converter which function can be easy programmed to obtain required direction of energy flow and parameters to be stabilised. If more energy conversion is required, modules can be connected and information between them can be interchanged via serial interface. The modules are designed for different voltage and current capabilities, thus forming a family of efficient converters enables to change one voltage waveform to any other required.

	A RESONANT POWER SUPPLY FOR DISTRIBUTED SYSTEMS By A. Nagel; K. Backhaus; H. Reinold	[View] [Download]
Abstract: Mechanical engineering develops a rising demand for reliable, easy-to-use power supplies, which are short-circuit proof, electrically isolated and possesses the capability to transmit energy to moving parts of a machine. As a solution this paper describes a distributed mid-frequency range AC power system consisting of resonant DC-DC converters and ferrite transformers for a power range of up to 100 kW. Experimental results of such a system integrated in a 7 axis robot are presented.

	ANALYSIS OF THE LCL-RESONANT CONVERTER OPERATING ABOVE RESONANCE By Kh. Louati; W. Abida; D. Sadarnac	[View] [Download]
Abstract: The LCL-type resonant converter (LCL-RC) has more desirable features than the conventional parallel resonant converter (PRC), such as the small frequency range and the reduced circulating current in the inverter. A steady state analysis of the converter operated above resonance gave a set of characteristic curves from which a systematic design procedure is developed. In order to get good efficiency, an optimum design result is obtained by minimizing the energy in the inductors and maximizing the current gain of the LCL-resonant circuit. Experimental results of prototype of a 750 watt-500 KHz full bridge LCL-RC are also presented.

	DESIGN TRADE-OFFS IN A BOOST TOPOLOGY USED AS A PF CONTROLLER By A.Martinez; D. Abud; J. A. Cobos; J. Sebastian; J. Uceda; J. Arau	[View] [Download]
Abstract: In the last decade, the number of electronics equipments connected to the AC line has been increased; these equipments present low values of Poyver Factor (PF) and high Total Harmonic Distortion (THD) due to their non-linear behavior [1]. Boost topology has been widely used as PF controller due to its step-up voltage conversion ratio, continuous input current, simple topology, and high efficiency. For high voltage applications, the major concerns of the conventional boost converter are the losses on the power devices, which will affect converter cost and efficiency. In this document, the experimental results of a Boost converter build as a PF controller, are presented. Besides, an analysis of the design compromises to keep in mind in order to develop a PF controller, for the Boost topology case, has been included in this paper. This analysis evaluates the compromises that must be considered when in the design of a PF Controller, we try to obtain the best Power Factor (PF), Total Harmonic Distortion (THD) and construction cost.

	FAULT TOLERANCE IN DISTRIBUTED POWER SYSTEMS By R.V. White	[View] [Download]
Abstract: The demand for continuously available information processing systems increases every day. Transaction processing, communications systems, and critical processes all require non-stop, fault tolerant operation. There are four steps to achieving fault tolerance in any system. However, no system will operate without a supply of electrical power. This paper is a tutorial that reviews the four principles of fault tolerance. Special considerations for high availability and fault tolerance in distributed power systems are highlighted.

	TOPOLOGIES FOR HIGH POWER FACTOR THREE-PHASE AC-TO-DC CONVERTER By B.-R. Lin; T.-S. Hwang	[View] [Download]
Abstract: This paper reviews and describes techniques for three-phase ac-to-dc converter with near unity power factor. The system consists of three-phase ac source and three-phase full bridge rectifier, power stage of the converter, dc link capacitor and load. It is proposed to achieve high performance and simple control circuit. The output voltage can be maintained above or below the peak ac input voltage by changing the duty cycle of the active switch. The PWM and resonant switch classification, ac-to-dc converter circuit topology, design of control circuit, small-signal modeling for continuous conduction mode (CCM) and discontinuous conduction mode (DCM), experimental results are reviewed and discussed in this paper.

	A COMBINED-GRAPH APPROACH - OBTAINING MODELS OF DC-DC PWM CONVERTERS BY AVERAGING AND INCREMENTAL REPRESENTATION By M.S. Makowski	[View] [Download]
Abstract: The well adopted approach to analysing DC and low-frequency behaviour of PWM DC-DC converters is through the notion of state-space averaged-circuit models. In this paper a related approach is exploited. It starts directly from the circuit graph and topological matrix description but in contrary to previous contributions it is proposed here to split the models in two distinct categories: the incremental model (introduced in this paper) and the averaged model (adopted in the literature) depending on whether the topological degeneracies are present or not in the converter graphs, respectively. A unified-form combined-graph model is proposed resulting in the reduced number of system equations and simplest possible means for evaluating DC and AC network functions. Illustrative DC modelling examples concerning nondegenerate, semidegenerate and degenerate converters are included.