• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.598-609
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• 2005

Conventional phase shift full bridge (PSFB) converter has serious voltage oscillation problem across the secondary rectifier diodes, which would require the dissipate snubber circuit, thus degrades the overall efficiency. To overcome this problem a new simple voltage oscillation reduction technique (VORT) which effectively reduce the voltage oscillation of the secondary rectifier diodes for phase shift full bridge converter is proposed. Therefore, no dissipate snubber for rectifier diodes is needed. In addition, since it has wide zero voltage switching (ZVS) range, high efficiency can be achieved. Operational principle, analysis of voltage oscillation, and design consideration are presented compare with that of the conventional PSFB converter. To confirm the validity of the proposed VORT, experimental results from a 420W prototype are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.228-234
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• 2009

In this paper, we present an analytical method that provides fast and efficient evaluation of the power losses and the conversion efficiency for phase-shift controlled full-bridge converter. In the proposed method, the conduction losses are evaluated by calculating the effective values of the ideal current waveform first and incorporating them into an exact equivalent circuit model of the phase-shift controlled full-bridge converter that includes all the parasitic resistances of the circuit components. While the conduction losses are accurately accounted for the synchronous rectification, the core losses are assumed to be negligible in order to simplify the analysis. The validity and accuracy of the proposed method are verified with experiments on a prototype phase-shift controlled full-bridge converter. An excellent correlation between the experiments and theories are obtained for the input voltages of 400V, output voltage 12V and maximum power 720W.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.623-628
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• 2009

There is an increasing demand for efficient high power/weight auxiliary power supplies for use on high speed traction application. Many new conversion techniques have been proposed to reduce the voltage and current stress of switching components, and the switching losses in the traditional pulse width modulation(PWM) converter. Especially, the phase shift full bridge zero voltage switching PWM techniques are thought most desirable for many applications because this topology permits all switching devices to operate under zero voltage switching(ZVS) by using circuit parasitic components such as leakage inductance of high frequency transformer and power device junction capacitance. The proposed topology is found to have higher efficiency than conventional soft-switching converter. Also it is easily applicable to phase shift full bridge converter by applying an energy recovery snubber consisted of fast recovery diodes and capacitors.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.167-174
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• 2015

This study describes how digital time delay deteriorates control performance in zero voltage switching (ZVS) phase-shifted full bridge (PSFB) converter. The small-signal model of the ZVS PSFB converter is derived from the buck-converter small-signal model. Digital time delay effects have been considered according to the digital sampling methods. The analysis verifies that digital time delays reduce the stability margin of the converter, and the double sampling technique exhibits better performance than the single sampling technique. Both simulation and experimental results based on 250 W ZVS PSFB confirm the validity of the analyses performed in the study.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.35-36
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• 2012

본 논문은 EV용 탑재형 배터리 충전기(OBC)와 같은 중 대용량 충전시스템에 적용한 Phase Shift Full Bridge Converter (PSFB) 토폴로지를 사용하는 경우, 트랜스포머의 구조에 따른 특성을 분석한다. 일반적으로 PSFB는 다른 토폴로지에 비해 코어 사용 효율이 높기 때문에 상대적으로 소형 경량화 설계가 용이하다. 그러나 수 kW급의 시스템 응용에서는 기존 코어 형상이나 Ap-limit과 제약이 따른다. 또한 특화된 코어의 경우 높은 가격으로 설계 경쟁력이 낮아진다. 따라서 본 논문에서는 이러한 대용량 PSFB의 응용 시스템에 적합한 코어 설계를 위해 다양한 트랜스포머의 구조를 선정하여 그 특성을 비교분석한다.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.286-288
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• 2005

Conventional phase shift full bridge (PSFB) converter has serious voltage oscillation problem across the secondary rectifier diodes, which would require the dissipate snubber circuit, thus degrades the overall efficiency. To overcome this problem, a new voltage oscillation reduction technique (VORT) which effectively reduce the voltage oscillation of the secondary rectifier diodes for phase shift 1011 bridge converter is proposed. Therefore, no dissipate snubber for rectifier diodes is needed. In addition, since it has wide zero voltage switching (ZVS) range, high efficiency can be achieved. Operational principle, analysis of voltage oscillation, and design consideration are presented compare with that of the conventional PSFB converter. To confirm the validity of the proposed VORT, experimental results from a 420W, 385Vdc/210Vdc prototype are presented.

• Journal of Power Electronics
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• v.14 no.3
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• pp.413-420
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• 2014

The conventional Phase-Shift Full-Bridge (PSFB) converter has a serious voltage spike because of the ringing between the leakage inductance of the transformer and the parasitic output capacitance of the secondary side rectifier switches. To overcome this problem, an asynchronous active clamp technique employing an auxiliary DC/DC converter has been proposed. However, an exact analyses for designing the auxiliary DC/DC converter has not been presented. Therefore, the amount of power that is supposed to be handled in the auxiliary DC/DC converter is calculated through a precise mode analyses in this paper. In addition, this paper proposes a lossy snubber circuit with hysteresis characteristics to reduce the burden that the auxiliary DC/DC converter should take during the starting interval. This technique results in optimizing the size of the magnetic component of the auxiliary DC/DC converter. The operational principles and the theoretical analyses are validated through experiments with a 48V-to-30V/15A prototype.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.379-381
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• 2008

Generally additional leakage inductance and two clamp diodes are adopted into the conventional phase shift full bridge (PSFB) converter for reducing the voltage stress of secondary rectifier diodes and extending the range of zero voltage switching (ZVS) operation. However, since additional leakage inductance carries the ac current similar to the primary one, the core and copper loss oriented from additional leakage inductance can be high enough to decrease the whole efficiency of DC/DC converter. Therefore, in this paper, a new ZVS phase shift full bridge converter with separated primary winding (SPW) is proposed. Proposed converter makes the transformer and additional leakage inductor with one ferrite core. Using this method, leakage inductance is controlled by the winding ratio of separated primary winding. Moreover, by manufacturing the both magnetic components with one core, size and core loss can be reduced and it turns out the improvement of efficiency and power density of DC/DC converter. The operational principle of proposed converter is analyzed and verified by the 1.2kW prototype.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.1
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• pp.54-61
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• 2000

Conventionally, ZVS FB DC/DC converter was controlled by monolithic IC UC3879, which includes the functions of oscillator, error amplifier and phase-shift circuit. Also, microprocessor and DSP have been widely used for the remote control and for the immediate waveform control in ZVS FB DC/DC converter. However the conventional microprocessor controller is complex and difficult to control because the controller consists of analog and digital parts. In the case of the control of FB DC/DC converter, the output is required of driving a direct signal to the switch drive circuits by the digital controller. So, this paper presents the method and realization of designing the digital-to-phase shift PWM circuit controlled by DSP (TMX320C32) in a 2,500A, 40㎾ ZVS FB DC/DC converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.5
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• pp.443-452
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• 2002

A new phase shift full bridge (PSFB) converter with serially connected two transformers for telecommunication equipments of several hundred watts is proposed. The main features of the proposed converter are a wide input voltage range, an easiness to meet the requirement for zero voltage switching (ZVS) condition at a light load, and a small output voltage ripple. Furthermore, the serially connected two transformers can replace both a main transformer and an output inductor since the two transformers act as not only a main transformer but an output inductor by turns. Therefore, there is no need to use an output inductor, then the proposed converter features high power density. A mode analysis, design equations through a large signal modeling, and experimental results are presented to verify the validity of the proposed converter.