EPE Association: EPE 1991 - 10 - Session 1.10: DC/DC CONVERTERS

EPE 1991 - 10 - Session 1.10: DC/DC CONVERTERS
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   A 350W-500kHz PWM DC-DC CONVERTER UTILIZING SATURABLE REACTOR ASSISTED SOFT-SWITCHING TECHNIQUE
By S. Hamada; Y. Ogino; M. Nakaoka [View]
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Abstract: This paper presents newly-developed DC-DC converters employing saturable reactor assisted (SRA) soft-switching technique. The SRA soft-switching converters have advantages such as low switching and low conduction losses, wide load range and constant frequency operation. The steady-state analysis of a full-bridge DC-DC converter utilizing this technique is presented. Some experimental and simulation results of a 350W-500kHz converter are also provided. Moreover, A family of the SRA soft-switching converters are illustrated and discussed.

   ADVANCED CONSTANT-FREQUENCY PWM RESONANT DC-DC CONVERTER WITH REAL TIME DIGITAL CONTROL FOR X-RAY POWER GENERATOR
By H. Takano; H. Uemura; M. Nakaoka [View]
[Download]

Abstract: This paper presents a newly developed DC-DC converter for an X-ray power generator with a digitally-controlled resonant PWM inverter. The converter makes use of the parasitic elements of the circuit such as the leakage inductances and secondary-side stray capacitances of the high-voltage transformer , and as the input capacitances of the cables connected to X-ray tube. In order to radiate efficacious X-ray for medical usage, stabilized and low-rippled high- voltage DC, which has to be in the range of 150kV, must be applied to the X-ray tube with speedy response. In addition to this, the major difficulty with the X-ray generator consists in the need to make adjustments for the very wide load range, where the operation is not always in identical resonant mode. The countermeasure for the nonlinear characteristics is essential in this development. The paper discusses the applicable dynamic modeling to simulate the resonant converter circuit behavior and the linearlized compensation methods with the real time software digital control. The experimental results are demonstrated as compared with the computer aided simulation.

   ANALYSIS OF THE OVERCURRENT-LIMITING CHARACTERISTICS OF THE DC-DC CONVERTER WITH CURRENT-INJECTED CONTROL
By Hirofumi Matsuo; Fujio Kurokawa; Takashi Takeda [View]
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Abstract: The purpose of this paper is to analyze the overcurrent-limiting characteristics of the dc-dc converter with current-injected control. First, the overcurrent-limiting characteristics is revealed as a function of parameters such as circuit constants of the main and control circuits, switching frequency, gain of voltage and current detection circuits, incline in the sawtooth voltage which is added to the threshold level to limit the peak of switch current, and so forth, in order to sufficiently understand and design how these parameters affect the circuit behavior and characteristics in the overcurrent-limited mode. As a result, the circuit condition is defined for the foldback current limiting, constant current and voltage drooping characteristics. Further, it is shown that the steady-state and dynamic characteristics in the overcurrent-limited mode can be improved by controlling the incline in the sawtooth voltage which is added to the threshold level in proportion to the output voltage.

   A NOVEL FULL BRIDGE SEMI-CONTROLLED SWITCH MODE RECTIFIER
By Stefanos Manias [View]
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Abstract: In this paper a novel semicontrolled Switch Mode Rectifier (SMR) topology is proposed and analyzed which exhibits the following advantages when compared to other existing SMR topologies: a) High true power factor at the AC source (almost unity), b) high displacement power factor at the input of the SMR unit (almost unity), c) high efficiency, d) low implementation cost and e) high power density.

   IGBTs IN FULL-BRIDGE DC TO DC CONVERTERS - COMPARISON OF TOPOLOGIES WITH HARD AND SOFT SWITCHING
By Hans Georg Langer [View]
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Abstract: Many research activities have been caried out on converter topologies using resonant elements to achieve soft switching. Some dc to dc converters use the inverter legs with resonant commutation to attain zero-voltage-switching. It is interesting to look at the behaviour of IGBTs at zero-voltage-switching because they are displacing bipolar transistors. In this paper, measured energy losses of a 50A/1000V IGBT at hard and zero-voltage-switching are used to design different converters with hard and resonant commutation. Experimental results of these converters are presented. A comparison of the component values shows the advantages and disadvantages of the resonant commutation in an inverter leg.

   ANALYSIS, DESIGN AND EXPERIMENTAL EVALUATION OF A HIGH-POWER HIGH-FREQUENCY BI-DIRECTIONAL DC/DC CONVERTER
By M. H. Kheraluwala; R. W. De Doncker; D. M. Divan [View]
[Download]

Abstract: The paper outlines the performance characteristics of a high power, high power density dc/dc converter based on the single-phase dual active bridge topology proposed in [1]. The dual active bridge converter has very attractive features in terms of low device and component stresses, small filter components, low switching losses (by virtue of zero voltage switching), high power density and high efficiency, bi-directional power flow, buck-boost operation, low sensitivity to system parasitics and simple first-order stable dynamics. The lnfluence of dominant system parasitics on the soft switching region are discussed. Since, the leakage inductance of the transformer is the main energy transfer element, special transformer design techniques [2] have been utilized to carefully control this parameter. Experimental results from a prototype 50 kW, 50 kHz are presented.

EPE 1991 - 10 - Session 1.10: DC/DC CONVERTERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 10 - Session 1.10: DC/DC CONVERTERS
	[return to parent folder]

	A 350W-500kHz PWM DC-DC CONVERTER UTILIZING SATURABLE REACTOR ASSISTED SOFT-SWITCHING TECHNIQUE By S. Hamada; Y. Ogino; M. Nakaoka	[View] [Download]
Abstract: This paper presents newly-developed DC-DC converters employing saturable reactor assisted (SRA) soft-switching technique. The SRA soft-switching converters have advantages such as low switching and low conduction losses, wide load range and constant frequency operation. The steady-state analysis of a full-bridge DC-DC converter utilizing this technique is presented. Some experimental and simulation results of a 350W-500kHz converter are also provided. Moreover, A family of the SRA soft-switching converters are illustrated and discussed.

	ADVANCED CONSTANT-FREQUENCY PWM RESONANT DC-DC CONVERTER WITH REAL TIME DIGITAL CONTROL FOR X-RAY POWER GENERATOR By H. Takano; H. Uemura; M. Nakaoka	[View] [Download]
Abstract: This paper presents a newly developed DC-DC converter for an X-ray power generator with a digitally-controlled resonant PWM inverter. The converter makes use of the parasitic elements of the circuit such as the leakage inductances and secondary-side stray capacitances of the high-voltage transformer , and as the input capacitances of the cables connected to X-ray tube. In order to radiate efficacious X-ray for medical usage, stabilized and low-rippled high- voltage DC, which has to be in the range of 150kV, must be applied to the X-ray tube with speedy response. In addition to this, the major difficulty with the X-ray generator consists in the need to make adjustments for the very wide load range, where the operation is not always in identical resonant mode. The countermeasure for the nonlinear characteristics is essential in this development. The paper discusses the applicable dynamic modeling to simulate the resonant converter circuit behavior and the linearlized compensation methods with the real time software digital control. The experimental results are demonstrated as compared with the computer aided simulation.

	ANALYSIS OF THE OVERCURRENT-LIMITING CHARACTERISTICS OF THE DC-DC CONVERTER WITH CURRENT-INJECTED CONTROL By Hirofumi Matsuo; Fujio Kurokawa; Takashi Takeda	[View] [Download]
Abstract: The purpose of this paper is to analyze the overcurrent-limiting characteristics of the dc-dc converter with current-injected control. First, the overcurrent-limiting characteristics is revealed as a function of parameters such as circuit constants of the main and control circuits, switching frequency, gain of voltage and current detection circuits, incline in the sawtooth voltage which is added to the threshold level to limit the peak of switch current, and so forth, in order to sufficiently understand and design how these parameters affect the circuit behavior and characteristics in the overcurrent-limited mode. As a result, the circuit condition is defined for the foldback current limiting, constant current and voltage drooping characteristics. Further, it is shown that the steady-state and dynamic characteristics in the overcurrent-limited mode can be improved by controlling the incline in the sawtooth voltage which is added to the threshold level in proportion to the output voltage.

	A NOVEL FULL BRIDGE SEMI-CONTROLLED SWITCH MODE RECTIFIER By Stefanos Manias	[View] [Download]
Abstract: In this paper a novel semicontrolled Switch Mode Rectifier (SMR) topology is proposed and analyzed which exhibits the following advantages when compared to other existing SMR topologies: a) High true power factor at the AC source (almost unity), b) high displacement power factor at the input of the SMR unit (almost unity), c) high efficiency, d) low implementation cost and e) high power density.

	IGBTs IN FULL-BRIDGE DC TO DC CONVERTERS - COMPARISON OF TOPOLOGIES WITH HARD AND SOFT SWITCHING By Hans Georg Langer	[View] [Download]
Abstract: Many research activities have been caried out on converter topologies using resonant elements to achieve soft switching. Some dc to dc converters use the inverter legs with resonant commutation to attain zero-voltage-switching. It is interesting to look at the behaviour of IGBTs at zero-voltage-switching because they are displacing bipolar transistors. In this paper, measured energy losses of a 50A/1000V IGBT at hard and zero-voltage-switching are used to design different converters with hard and resonant commutation. Experimental results of these converters are presented. A comparison of the component values shows the advantages and disadvantages of the resonant commutation in an inverter leg.

	ANALYSIS, DESIGN AND EXPERIMENTAL EVALUATION OF A HIGH-POWER HIGH-FREQUENCY BI-DIRECTIONAL DC/DC CONVERTER By M. H. Kheraluwala; R. W. De Doncker; D. M. Divan	[View] [Download]
Abstract: The paper outlines the performance characteristics of a high power, high power density dc/dc converter based on the single-phase dual active bridge topology proposed in [1]. The dual active bridge converter has very attractive features in terms of low device and component stresses, small filter components, low switching losses (by virtue of zero voltage switching), high power density and high efficiency, bi-directional power flow, buck-boost operation, low sensitivity to system parasitics and simple first-order stable dynamics. The lnfluence of dominant system parasitics on the soft switching region are discussed. Since, the leakage inductance of the transformer is the main energy transfer element, special transformer design techniques [2] have been utilized to carefully control this parameter. Experimental results from a prototype 50 kW, 50 kHz are presented.