EPE Association: EPE 1991 - 41 - Session 4.8: DC/DC CONVERTERS

EPE 1991 - 41 - Session 4.8: DC/DC CONVERTERS
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   HIGH POWER BUCK-BOOST TYPE VOLTAGE-RESONANT DC-DC CONVERTER OPERATING IN THE DISCONTINUOUS REACTOR CURRENT REGION
By H. Hayashi; H. Matsuo; F. Kurokawa; T. Koga [View]
[Download]

Abstract: In the resonant dc-dc converter, the regulation of the output voltage for the changes of the input voltage and the load is performed by the control of the switching frequency. Consequently, it is often observed that the switching frequency in a voltage-resonant type dc-dc converter becomes extremely low when the input voltage decreases. This lowering of the switching frequency deteriorates the advantage of the high frequency in designing the circuit and sometimes causes the acoustic noise problem. In this paper, high power (5kW) buck-boost type voltage-resonant dc-dc converter with a single SI thyristor switch is proposed and analyzed, which operates in the discontinuous reactor current region. As a result, in this voltage-resonant dc-dc converter, the output voltage can be regulated sufficiently for the load change from no load to full load and for ±15% change of the input voltage. In this case, the change of the switching frequency can be restricted within ±10% and the switching frequency can be kept above 20kHz, the power conversion efficiency of 90% or more can be obtained.

   SIMULATION OF RESONANT TANK AND RECTIFIER INTERACTION IN A CLASS E DC/DC CONVERTER
By A. J. Forsyth; Y. T. Leung [View]
[Download]

Abstract: The significant second-order effects arising from the interaction of the relatively low Q factor resonant tank and the non-linear rectifier load in a class E dc/dc converter are examined using computer simulation techniques. In particular, the effects of asymmetrical rectifier conduction and the possibility of dc magnetisation in the transformer are assessed. The simulation package Matrixx is used in the simulation work and full supporting practical results are included from a 1 MHz 50V to 15V dc/dc converter.

   A SYSTEMATIC MODELLING OF DC-DC CONVERTERS USING SPICE SIMULATION PROGRAM
By Marek S. Makowski [View]
[Download]

Abstract: This paper presents a new model of dc-dc converter for the SPICE simulation program. In this approach the configuration of a converter is first identified using averaged topological matrices and then its equivalent circuit is determined. The procedure is systematic and leads to circuit models representing the defined classes of loop voltage and cut-set current two-topology converters. The model is valid for both small and large signals and is therefore suitable for frequency and transient simulation.

   PARAMETER SELECTION AND DIMENSIONING OF A HALF-BRIDGE SERIES RESONANT DC/DC CONVERTER
By J. P. Laur; J. Jalade; F. Lappas [View]
[Download]

Abstract: At present, electric power conversion devices rely on resonant or quasi resonant structures in an increasing number of applications. Although this technique features numerous advantages, circuit dimensioning requires engineering delicate tradeoffs. This paper details a method of parameter selection and dimensioning of a series resonant DC/DC converter using a thyristor-dual mode switch control. The curves showing the sensitivity of characteristic variables to the setup parameters support the selection made and an example is given to illustrate this study.

   ANALYSIS OF THE DYNAMIC BEHAVIOUR OF A DC/DC SERIES RESONANT CONVERTER OPERATING ABOVE THE NATURAL FREQUENCY
By C. Collomb; M. Fadel; Y. Cheron [View]
[Download]

Abstract: In this paper, the authors deal with the behaviour of the frequency controlled DC/DC series resonant converter. As far as the efficiency and the power to weight ratio are concerned such a converter bears attractive features; however, its control problem are a well-known drawback. The modelling method developed allows expressing a transfer function that links the output voltage to the switching frequency for any operating conditions. The model obtained shows that the dynamic characteristics depend on the operating point to a large extend. The results are shown in the output plane and the dominant behaviour zones corresponding to the connected load are displayed. The theoretical results are compared with simulation and experiment results.

   A NOVEL CONTROL STRATEGY FOR DC-DC RESONANT CONVERTER
By J. Petzoldt; U. Köbe [View]
[Download]

Abstract: In this paper a novel control strategy for a zero-voltage-switching, clamped-voltage topology is described. The control strategy is based on a direct integration of the inverter output voltage. A comparator compares the integrated ac-voltage with a threshold voltage, as the extern control voltage. There is a linear relationship between the control voltage and the voltage time areas of the ac voltage and a high dynamic suppression of a dc-share in the ac-voltage.

   CONTROL OF THE BOOST DC-DC CONVERTER WITH CURRENT-VOLTAGE FEEDBACK
By DJordje Garabandic; Nandor Burany [View]
[Download]

Abstract: In this paper the use of a current-voltage feedback for the control of boost switching regulators is proposed. Instead of the conventional current loop with comparator used by Current Injection Control (CIC), the use of a proportional regulator in the current loop is suggested. The results of the theoretical analysis of the proposed feedback circuit based on the small signal model and computer simulation results for the large signal case are presented. The theoretical and simulation results are verified by measurements on a laboratory prototype. The advantages compared to CIC are that switching instability is eliminated and susceptibility to noise is lowered. An alqorithm is included for the design of the proposed feedback circuit.

   DEAD-BEAT CONTROLLERS FOR FLYBACK AND FORWARD DC/DC CONVERTERS
By P. Miljanic; Lj. Peric; S. Vukosavic [View]
[Download]

Abstract: The output voltage of flyback and forward DC/DC converters can be adjusted by affecting the width of the power switch pulses. Closed-loop control designed to control the average value of the output voltage cannot eliminate the output voltage error produced by the input voltage fluctuations or the load current pulsatlons. In order to suppress the output voltage transients, the pulse width modulator should be placed in the closed loop controlling the output voltage instantaneous value. Modulation signal samples consist of reference signal and samples of the output filter states. With the proper selection of the regulator structure and feedback coefficients, the dead-beat response can be achieved for both flyback and forward converters. The paper presents theoretical background and design considerations for both flyback and forward converters along with the parameter setting guidelines.

EPE 1991 - 41 - Session 4.8: DC/DC CONVERTERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 41 - Session 4.8: DC/DC CONVERTERS
	[return to parent folder]

	HIGH POWER BUCK-BOOST TYPE VOLTAGE-RESONANT DC-DC CONVERTER OPERATING IN THE DISCONTINUOUS REACTOR CURRENT REGION By H. Hayashi; H. Matsuo; F. Kurokawa; T. Koga	[View] [Download]
Abstract: In the resonant dc-dc converter, the regulation of the output voltage for the changes of the input voltage and the load is performed by the control of the switching frequency. Consequently, it is often observed that the switching frequency in a voltage-resonant type dc-dc converter becomes extremely low when the input voltage decreases. This lowering of the switching frequency deteriorates the advantage of the high frequency in designing the circuit and sometimes causes the acoustic noise problem. In this paper, high power (5kW) buck-boost type voltage-resonant dc-dc converter with a single SI thyristor switch is proposed and analyzed, which operates in the discontinuous reactor current region. As a result, in this voltage-resonant dc-dc converter, the output voltage can be regulated sufficiently for the load change from no load to full load and for ±15% change of the input voltage. In this case, the change of the switching frequency can be restricted within ±10% and the switching frequency can be kept above 20kHz, the power conversion efficiency of 90% or more can be obtained.

	SIMULATION OF RESONANT TANK AND RECTIFIER INTERACTION IN A CLASS E DC/DC CONVERTER By A. J. Forsyth; Y. T. Leung	[View] [Download]
Abstract: The significant second-order effects arising from the interaction of the relatively low Q factor resonant tank and the non-linear rectifier load in a class E dc/dc converter are examined using computer simulation techniques. In particular, the effects of asymmetrical rectifier conduction and the possibility of dc magnetisation in the transformer are assessed. The simulation package Matrixx is used in the simulation work and full supporting practical results are included from a 1 MHz 50V to 15V dc/dc converter.

	A SYSTEMATIC MODELLING OF DC-DC CONVERTERS USING SPICE SIMULATION PROGRAM By Marek S. Makowski	[View] [Download]
Abstract: This paper presents a new model of dc-dc converter for the SPICE simulation program. In this approach the configuration of a converter is first identified using averaged topological matrices and then its equivalent circuit is determined. The procedure is systematic and leads to circuit models representing the defined classes of loop voltage and cut-set current two-topology converters. The model is valid for both small and large signals and is therefore suitable for frequency and transient simulation.

	PARAMETER SELECTION AND DIMENSIONING OF A HALF-BRIDGE SERIES RESONANT DC/DC CONVERTER By J. P. Laur; J. Jalade; F. Lappas	[View] [Download]
Abstract: At present, electric power conversion devices rely on resonant or quasi resonant structures in an increasing number of applications. Although this technique features numerous advantages, circuit dimensioning requires engineering delicate tradeoffs. This paper details a method of parameter selection and dimensioning of a series resonant DC/DC converter using a thyristor-dual mode switch control. The curves showing the sensitivity of characteristic variables to the setup parameters support the selection made and an example is given to illustrate this study.

	ANALYSIS OF THE DYNAMIC BEHAVIOUR OF A DC/DC SERIES RESONANT CONVERTER OPERATING ABOVE THE NATURAL FREQUENCY By C. Collomb; M. Fadel; Y. Cheron	[View] [Download]
Abstract: In this paper, the authors deal with the behaviour of the frequency controlled DC/DC series resonant converter. As far as the efficiency and the power to weight ratio are concerned such a converter bears attractive features; however, its control problem are a well-known drawback. The modelling method developed allows expressing a transfer function that links the output voltage to the switching frequency for any operating conditions. The model obtained shows that the dynamic characteristics depend on the operating point to a large extend. The results are shown in the output plane and the dominant behaviour zones corresponding to the connected load are displayed. The theoretical results are compared with simulation and experiment results.

	A NOVEL CONTROL STRATEGY FOR DC-DC RESONANT CONVERTER By J. Petzoldt; U. Köbe	[View] [Download]
Abstract: In this paper a novel control strategy for a zero-voltage-switching, clamped-voltage topology is described. The control strategy is based on a direct integration of the inverter output voltage. A comparator compares the integrated ac-voltage with a threshold voltage, as the extern control voltage. There is a linear relationship between the control voltage and the voltage time areas of the ac voltage and a high dynamic suppression of a dc-share in the ac-voltage.

	CONTROL OF THE BOOST DC-DC CONVERTER WITH CURRENT-VOLTAGE FEEDBACK By DJordje Garabandic; Nandor Burany	[View] [Download]
Abstract: In this paper the use of a current-voltage feedback for the control of boost switching regulators is proposed. Instead of the conventional current loop with comparator used by Current Injection Control (CIC), the use of a proportional regulator in the current loop is suggested. The results of the theoretical analysis of the proposed feedback circuit based on the small signal model and computer simulation results for the large signal case are presented. The theoretical and simulation results are verified by measurements on a laboratory prototype. The advantages compared to CIC are that switching instability is eliminated and susceptibility to noise is lowered. An alqorithm is included for the design of the proposed feedback circuit.

	DEAD-BEAT CONTROLLERS FOR FLYBACK AND FORWARD DC/DC CONVERTERS By P. Miljanic; Lj. Peric; S. Vukosavic	[View] [Download]
Abstract: The output voltage of flyback and forward DC/DC converters can be adjusted by affecting the width of the power switch pulses. Closed-loop control designed to control the average value of the output voltage cannot eliminate the output voltage error produced by the input voltage fluctuations or the load current pulsatlons. In order to suppress the output voltage transients, the pulse width modulator should be placed in the closed loop controlling the output voltage instantaneous value. Modulation signal samples consist of reference signal and samples of the output filter states. With the proper selection of the regulator structure and feedback coefficients, the dead-beat response can be achieved for both flyback and forward converters. The paper presents theoretical background and design considerations for both flyback and forward converters along with the parameter setting guidelines.