EPE Association: EPE 1989 - 45 - Dialogue Session 3.7: SWITCHED MODE POWER SUPPLIES: DC to DC CONVERTERS, DEVICES

EPE 1989 - 45 - Dialogue Session 3.7: SWITCHED MODE POWER SUPPLIES: DC to DC CONVERTERS, DEVICES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 45 - Dialogue Session 3.7: SWITCHED MODE POWER SUPPLIES: DC to DC CONVERTERS, DEVICES

   [return to parent folder]

   TEST AND MEASUREMENT CIRCUIT FOR POWER DEVICES IN RESONANT APPLICATIONS
By K. Heumann; D. Tegtmeier [View]
[Download]

Abstract: Resonant inverters become more important in power electronics. For the power semiconductor devices the switching and on-state stress is quite different from that in a PWM inverter. A novel test circuit for resonant concepts at high switching frequencies (> 200 kHz) is presented, which allows to determine the semiconductor losses. Typical current and voltage waveforms of power semiconductors (MOSFET and SIT) in resonant inverters are given. A simulation of the test circuit proves the performance to have similar current and voltage waveforms. Measurement results of the power semiconductor losses in a high frequency series resonant inverter are shown.

   A COMPACT HIGH PERFORMANCE 300 W / 5 V SWITCHED MODE POWER SUPPLY
By H. van der Broeck; K. Löhn; F. Chevalier; H. Dethienne; W. Lemmens [View]
[Download]

Abstract: This paper describes a design example for a switched mode power supply (SMPS) of high power density made in a half bridge push-pull topology. The size of the transformer and output filter is substantially reduced at improved efficiency by operating the converter at high frequency with low losses. This requires careful design and use of special components. The transformer is optimized for low losses and low leakage inductance. The output filter uses ceramic capacitors and single turn chokes with extremely low parasites resulting in low EMI. The realized converter shows an efficiency of 85% for a 250 kHz primary frequency.

   QUASI-RESONANT-CONVERTERS FOR LOW OUTPUT VOLTAGE AND HIGH OUTPUT CURRENT
By J. Kunze; N. Fröhleke [View]
[Download]

Abstract: Recently introduced quasi-resonant-converter (QRC) create the supposition to raise switching frequency and power density of power supplies, by employing frequency- or pulse-width-modulated resonant-switches with reduced switching losses of the power devices. Examination of multiple resonant-switch-topologies with regard to the power switch stresses leads to the choice of a zero-current-switching (ZCS) QRC for realisation of a converter with high output power, low output voltage and a wide range of load variation. The mathematical model of a buck-resonant-converter with parasitics of the power switches shows the influence of conduction losses to the voltage conversion ratio and efficiency. Theoretical results are verified by measurements. Since new IGBT devices seem to be suitable to reduce conduction losses of ZCS-resonant-switches, measurements were taken on a buck-converter with a variaty of IGBT power switches. Experimental results permit to calculate the total losses of the switching device and determine individual losses caused by different physical mechanism when the clock frequency is increased.

   A NOVEL RESONANT DC TO DC CONVERTER WITH HIGH POWER DENSITY AND HIGH EFFICIENCY
By J. Mucko; H. G. Langer; J. Ch. Bendien [View]
[Download]

Abstract: For dc to dc power conversion with constant voltage transfer ratio, a novel type of a series resonant converter is presented. The converter operates with sinusoidal currents and the devices are switched under "low-voltage" and "low-current" conditions. Thus, the switching losses are low, and high switching frequencies improving the power density can be achieved. Furthermore, the radio interference is minimized. The paper describes the circuit in a half-bridge configuration and presents results obtained from a 3.5-kW converter, operating at switching frequencies of up to 50 kHz. The measurements are compared to a similar hard switched converter operating at a switching frequency of 22 kHz.

   VARIATIONS OF BUCK-BOOST ZERO-VOLTAGE-SWITCHING QUASI-RESONANT CONVERTERS: TOPOLOGlES AND ANALYSIS
By Ivo Barbi; D. C. Martins; J. B. Vieira Junior [View]
[Download]

Abstract: This paper deals with Buck-Boost Zero-Voltage-Switching Quasi-Resonant Converters (BB-ZVS-QRC's). A simple procedure is introduced to generate six BB-ZVS-QRC's from the conventional Buck-Boost PWM converter, without the use of the Resonant-Switch concept. Two of the six circuit configurations generated were already reported in the literature. The equations describing converters operation are derived and with them the similiraties and differences among the six topologies are discussed, particularly from the point of view of component stresses. By employing state-plane technique, the constraints to ensure Zero-Voltage-Switching are defined for each topology. Some important experimental results are presented, from a laboratory prototype operating at resonant frequency of 1.60 MHz and maximum switching frequency of 1.11 MHz. The effect of the junction capacitance of the output rectifier diode on, component stresses and losses are also presented and experimentaly demonstrated.

   REDUCTION OF DEVICES RATINGS IN A FORWARD RESONANT CONVERTER
By R. Bausiere; H. Tacca [View]
[Download]

Abstract: Resonant switches have been introduced in order to reduce switching losses. But the peak current through the switch is higher than with a classical switch. The forward resonant converter presented here illustrates an operating principle that would be applicable to several other converter topologies. This converter is not more complex than the former ones, but it includes 3 advantageous features:
- The devices ratings are reduced, for a specified output power.
- The conduction power losses are reduced, for a given load and identical devices.
- This circuit may be operated at a fixed frequency, so improving the filter design.

   OPTIMIZING SNUBBER LOSSES IN SERIES-RESONANT CONVERTERS
By H. Huisman; B. Gravendeel [View]
[Download]

Abstract: One of the hot items in designing a power converter is the choice of a heat sink. Thermal effects set a limit to the maximum power which can be handled by the converter. Actually even a moderate increase in the efficiency of a converter may lead to a substantially higher power level for the same power part. By careful examination of efficiency measurements a determination of the various loss components is possible. The insights obtained in this way can be used to optimize a power circuit.

   BIPOLAR TRANSISTORS IN HIGH FREQUENCY AREAS SWITCH-ON DRIVE TECHNIQUES FOR SERIES RESONANT CONVERTERS
By J. Arnould; D. Lafore; J. M. Li [View]
[Download]

Abstract: High voltage power bipolar transistors (H.V.P.B.T.) behavior in high frequency areas depends not only on their own performances but also on the converter structures in which they are implemented. The series resonant converter structure with spontaneous turn-on, appears as a favorable way to increase frequency. This paper shows that it is necessary to have special base drive circuits due to a half sine collector current, having positive and negative dlk/dt during conduction. With frequency increasing, dlk/dt becomes important; consequently the base drive must have very high dynamic performances. It is demonstrated by simulation and experiment that the peak base current reaches the same value as maximum collector current for the frequencies above 200kHz and that to keep the transistor in the pseudo-saturation after turn-on and out of hard saturation at turn-off, the base drive must be bi-directional in current during on-state.

   RESONANT DC-DC CONFIGURATIONS
By I. Nagy [View]
[Download]

Abstract: The paper describes a new generation of quasi-resonant switching DC-DC converters. Some of them have been suggested first in a previous paper [1]. They have strong similarities in their configurations with the buck, boost and buck and boost choppers [1], although their operations have salient differences. The currents of their controlled switches are sinusoidal like rather than trapezoidal. They are called Zero Voltage Turn-off Quasi-Resonant Converters (ZVT - QRC) rather than Zero Voltage Switching (ZVS) or Zero Current Switching (ZCS) QRC for the voltage across the controlled switches are practically zero during their turning-off, Either transistors of SCR's can be applied as controlled switches in them. They were devised for high frequency operation. They offer services from low up to high power. Their output voltage can be changed in wide range and it can be either higher or lower than the input one depending on the configuration. One converter can operate as current generator.

   DESIGN OF A HIGH-FREQUENCY PLANAR POWER TRANSFORMER IN MULTILAYER TECHNOLOGY
By D. van der Linde; C. A. M. Boon; J. B. Klaassens [View]
[Download]

Abstract: A high-frequency power transformer in multilayer printed circuit board (ML-PCB) technology is presented. The transformer with applications in switched mode power supplies operates at frequencies up to several MHz and therefore parasitics play a major role. The mechanical configuration of laboratory prototypes is discussed, as well as the electrical, parasitic and thermal behavior. The presentation is focussed on the leakage inductance, since the anilysis of other aspects is relatively simple. Test results show a high efficiency, low leakage inductance, a good thermal behavior and line insulation properties. Further, the topology enables the designer to make a trade-off between leakage inductance and interwinding capacitance. These parasitic components have to be minimized. Due to the strictly defined geometry, parasitic interwinding capacitance and leakage inductance are reproducable and can be computed relatively easily.

EPE 1989 - 45 - Dialogue Session 3.7: SWITCHED MODE POWER SUPPLIES: DC to DC CONVERTERS, DEVICES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 45 - Dialogue Session 3.7: SWITCHED MODE POWER SUPPLIES: DC to DC CONVERTERS, DEVICES
	[return to parent folder]

	TEST AND MEASUREMENT CIRCUIT FOR POWER DEVICES IN RESONANT APPLICATIONS By K. Heumann; D. Tegtmeier	[View] [Download]
Abstract: Resonant inverters become more important in power electronics. For the power semiconductor devices the switching and on-state stress is quite different from that in a PWM inverter. A novel test circuit for resonant concepts at high switching frequencies (> 200 kHz) is presented, which allows to determine the semiconductor losses. Typical current and voltage waveforms of power semiconductors (MOSFET and SIT) in resonant inverters are given. A simulation of the test circuit proves the performance to have similar current and voltage waveforms. Measurement results of the power semiconductor losses in a high frequency series resonant inverter are shown.

	A COMPACT HIGH PERFORMANCE 300 W / 5 V SWITCHED MODE POWER SUPPLY By H. van der Broeck; K. Löhn; F. Chevalier; H. Dethienne; W. Lemmens	[View] [Download]
Abstract: This paper describes a design example for a switched mode power supply (SMPS) of high power density made in a half bridge push-pull topology. The size of the transformer and output filter is substantially reduced at improved efficiency by operating the converter at high frequency with low losses. This requires careful design and use of special components. The transformer is optimized for low losses and low leakage inductance. The output filter uses ceramic capacitors and single turn chokes with extremely low parasites resulting in low EMI. The realized converter shows an efficiency of 85% for a 250 kHz primary frequency.

	QUASI-RESONANT-CONVERTERS FOR LOW OUTPUT VOLTAGE AND HIGH OUTPUT CURRENT By J. Kunze; N. Fröhleke	[View] [Download]
Abstract: Recently introduced quasi-resonant-converter (QRC) create the supposition to raise switching frequency and power density of power supplies, by employing frequency- or pulse-width-modulated resonant-switches with reduced switching losses of the power devices. Examination of multiple resonant-switch-topologies with regard to the power switch stresses leads to the choice of a zero-current-switching (ZCS) QRC for realisation of a converter with high output power, low output voltage and a wide range of load variation. The mathematical model of a buck-resonant-converter with parasitics of the power switches shows the influence of conduction losses to the voltage conversion ratio and efficiency. Theoretical results are verified by measurements. Since new IGBT devices seem to be suitable to reduce conduction losses of ZCS-resonant-switches, measurements were taken on a buck-converter with a variaty of IGBT power switches. Experimental results permit to calculate the total losses of the switching device and determine individual losses caused by different physical mechanism when the clock frequency is increased.

	A NOVEL RESONANT DC TO DC CONVERTER WITH HIGH POWER DENSITY AND HIGH EFFICIENCY By J. Mucko; H. G. Langer; J. Ch. Bendien	[View] [Download]
Abstract: For dc to dc power conversion with constant voltage transfer ratio, a novel type of a series resonant converter is presented. The converter operates with sinusoidal currents and the devices are switched under "low-voltage" and "low-current" conditions. Thus, the switching losses are low, and high switching frequencies improving the power density can be achieved. Furthermore, the radio interference is minimized. The paper describes the circuit in a half-bridge configuration and presents results obtained from a 3.5-kW converter, operating at switching frequencies of up to 50 kHz. The measurements are compared to a similar hard switched converter operating at a switching frequency of 22 kHz.

	VARIATIONS OF BUCK-BOOST ZERO-VOLTAGE-SWITCHING QUASI-RESONANT CONVERTERS: TOPOLOGlES AND ANALYSIS By Ivo Barbi; D. C. Martins; J. B. Vieira Junior	[View] [Download]
Abstract: This paper deals with Buck-Boost Zero-Voltage-Switching Quasi-Resonant Converters (BB-ZVS-QRC's). A simple procedure is introduced to generate six BB-ZVS-QRC's from the conventional Buck-Boost PWM converter, without the use of the Resonant-Switch concept. Two of the six circuit configurations generated were already reported in the literature. The equations describing converters operation are derived and with them the similiraties and differences among the six topologies are discussed, particularly from the point of view of component stresses. By employing state-plane technique, the constraints to ensure Zero-Voltage-Switching are defined for each topology. Some important experimental results are presented, from a laboratory prototype operating at resonant frequency of 1.60 MHz and maximum switching frequency of 1.11 MHz. The effect of the junction capacitance of the output rectifier diode on, component stresses and losses are also presented and experimentaly demonstrated.

	REDUCTION OF DEVICES RATINGS IN A FORWARD RESONANT CONVERTER By R. Bausiere; H. Tacca	[View] [Download]
Abstract: Resonant switches have been introduced in order to reduce switching losses. But the peak current through the switch is higher than with a classical switch. The forward resonant converter presented here illustrates an operating principle that would be applicable to several other converter topologies. This converter is not more complex than the former ones, but it includes 3 advantageous features: - The devices ratings are reduced, for a specified output power. - The conduction power losses are reduced, for a given load and identical devices. - This circuit may be operated at a fixed frequency, so improving the filter design.

	OPTIMIZING SNUBBER LOSSES IN SERIES-RESONANT CONVERTERS By H. Huisman; B. Gravendeel	[View] [Download]
Abstract: One of the hot items in designing a power converter is the choice of a heat sink. Thermal effects set a limit to the maximum power which can be handled by the converter. Actually even a moderate increase in the efficiency of a converter may lead to a substantially higher power level for the same power part. By careful examination of efficiency measurements a determination of the various loss components is possible. The insights obtained in this way can be used to optimize a power circuit.

	BIPOLAR TRANSISTORS IN HIGH FREQUENCY AREAS SWITCH-ON DRIVE TECHNIQUES FOR SERIES RESONANT CONVERTERS By J. Arnould; D. Lafore; J. M. Li	[View] [Download]
Abstract: High voltage power bipolar transistors (H.V.P.B.T.) behavior in high frequency areas depends not only on their own performances but also on the converter structures in which they are implemented. The series resonant converter structure with spontaneous turn-on, appears as a favorable way to increase frequency. This paper shows that it is necessary to have special base drive circuits due to a half sine collector current, having positive and negative dlk/dt during conduction. With frequency increasing, dlk/dt becomes important; consequently the base drive must have very high dynamic performances. It is demonstrated by simulation and experiment that the peak base current reaches the same value as maximum collector current for the frequencies above 200kHz and that to keep the transistor in the pseudo-saturation after turn-on and out of hard saturation at turn-off, the base drive must be bi-directional in current during on-state.

	RESONANT DC-DC CONFIGURATIONS By I. Nagy	[View] [Download]
Abstract: The paper describes a new generation of quasi-resonant switching DC-DC converters. Some of them have been suggested first in a previous paper [1]. They have strong similarities in their configurations with the buck, boost and buck and boost choppers [1], although their operations have salient differences. The currents of their controlled switches are sinusoidal like rather than trapezoidal. They are called Zero Voltage Turn-off Quasi-Resonant Converters (ZVT - QRC) rather than Zero Voltage Switching (ZVS) or Zero Current Switching (ZCS) QRC for the voltage across the controlled switches are practically zero during their turning-off, Either transistors of SCR's can be applied as controlled switches in them. They were devised for high frequency operation. They offer services from low up to high power. Their output voltage can be changed in wide range and it can be either higher or lower than the input one depending on the configuration. One converter can operate as current generator.

	DESIGN OF A HIGH-FREQUENCY PLANAR POWER TRANSFORMER IN MULTILAYER TECHNOLOGY By D. van der Linde; C. A. M. Boon; J. B. Klaassens	[View] [Download]
Abstract: A high-frequency power transformer in multilayer printed circuit board (ML-PCB) technology is presented. The transformer with applications in switched mode power supplies operates at frequencies up to several MHz and therefore parasitics play a major role. The mechanical configuration of laboratory prototypes is discussed, as well as the electrical, parasitic and thermal behavior. The presentation is focussed on the leakage inductance, since the anilysis of other aspects is relatively simple. Test results show a high efficiency, low leakage inductance, a good thermal behavior and line insulation properties. Further, the topology enables the designer to make a trade-off between leakage inductance and interwinding capacitance. These parasitic components have to be minimized. Due to the strictly defined geometry, parasitic interwinding capacitance and leakage inductance are reproducable and can be computed relatively easily.