• 전력전자학회논문지
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• 제21권5호
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• pp.396-403
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• 2016

Usually, large-sized buses and trucks have a very high load. In addition, frequent braking during downhill or long-distance driving, causes the conventional method using the brake friction to have a problem in safety because of brake fade and brake burst phenomenon. Auxiliary brakes dividing the braking load is essential. Hence, environment-friendly auxiliary brakes, such as contactless brake rather than the engine auxiliary brake system are needed. A study aimed at improving the energy efficiency by recharging electric energy with changing mechanical to electrical energy that occurs when braking is actively in progress. In this paper, the voltage control method is utilized to recover the electric energy generated in the electromagnetic retarder instead of the eddy current. To regenerate the braking energy into the electrical energy, the resonant L-C circuit is configured in the retarder. The voltage generated in the retarder is simply modeled as a transformer. However, retarder voltage control in this paper is simulated by modeling the induction generator because this induction generator modeling is more practical than transformer modeling. The changes in the voltage of the resonance circuit, which depends on the switch pulse duration of the control device, were analyzed. A PI controller algorithm to control this voltage is proposed. The feasibility of modeling retarder and voltage controller are shown by using MATLAB Simulink in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.226-228
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• 2006

This paper presents the two lossless auxiliary inducors-assisted voltage source type half bridge(single ended push pull:SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation forwide its output power regulation ranges and load variations under constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operatprinciple is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation charactertics-based on the high frequency PDM strategy. The experimenoperating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimenones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliimplemented here is proved from the practical point of view.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.327-331
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• 2003

This paper proposes a novel ZVZCS-PWM Boost Converter. It enables the main switch to be turned on and off with both zero voltage and zero current and the auxiliary switch to be turned on and off with ZCS, the rectify diode to be turned on and off with ZVS. Moreover, this converter is suitable for not on]y minority carrier device but also majority carrier device. The auxiliary resonant circuit of the proposed boost converter is placed out the main power path, therefore, there are no voltage/current stresses on the main switch and diode. The operation of the proposed boost converter is explained and analyzed theoretical and experimentally, from a prototype operating at 100kHz, with an input voltage rated at 50V.

• Journal of Power Electronics
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• 제11권6호
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• pp.787-792
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• 2011

In this paper, a new three phase soft switching inverter is presented. All of the semiconductor elements of this converter are soft switched. Employing only two auxiliary switches as DC-link switches and a simple control circuit are the advantages of the proposed inverter. The analytical equations and operating modes of the presented inverter are explained in details. The design considerations are presented and the experimental results verify the theoretical analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1215-1217
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• 2000

For the application of soft-switching technique to single Phase-full bridge inverter. in this paper ZCT(Zero Current Transition) and ZVT(Zero Voltage Transition) techniques proposed previously are compared and discussed the merit and demerit of both. Both have a excellency that can reduce the number of auxiliary switch and resonant circuit compared to other techniques and achive soft-switching in auxiliary switch itself. Therefore, it has enabled us to have benifits of realizing high efficiency and reliability, low EMI for high switching frequency and reducing the cost as well as size of device.

• 전력전자학회논문지
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• 제6권6호
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• pp.556-563
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• 2001

본 논문에서는, 기존의 PWM 방식의 컨버터와 공진형 컨버터의 단점을 보완하면서 이들의 장점을 가지는 새로운 형태의 ZCT 벅 컨버터를 소개한다. 제안한 회로는 기존의 벅 컨버터에 보조화를 추가하여 주 스위치와 다이로드의 스위칭천이 순간에만 소프트 스위칭 조건을 제공함으로써 전체적인 동작은 벅 컨버터와 동일하게 된다. 아울러 보조회로에서의 부가적인 손실은 존재하지 않는다. 본 논문에서는 제안된 회로의 동작을 분석하고 이를 바탕으로 보조회로에서의 소자값 결정에 도움이 되는 설계 방식을 제공한다. 또한 제안한 회로의 동작 및 유용성을 확인하기 위하여 실험을 행하였다.

• Journal of Power Electronics
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• 제19권2호
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• pp.353-362
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• 2019

To address the problem of circulating current loss in the traditional zero-current switching (ZCS) full-bridge (FB) DC/DC converter, a ZCS FB DC/DC converter topology and modulation strategy is proposed in this paper. The strategy can achieve ZCS turn on and zero-voltage and zero-current switching (ZVZCS) turn off for the primary switches and realize ZVZCS turn on and zero-voltage switching (ZVS) turn off for the auxiliary switches. Moreover, its resonant circuit power is small. Compared with the traditional phase shift full-bridge converter, the new converter decreases circulating current loss and does not increase the current stress of the primary switches and the voltage stress of the rectifier diodes. The diodes turn off naturally when the current decreases to zero. Thus, neither reverse recovery current nor loss on diodes occurs. In this paper, we analyzed the operating principle, steady-state characteristics and soft-switching conditions and range of the converter in detail. A 740 V/1 kW, 100 kHz experimental prototype was established, verifying the effectiveness of the converter through experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술대회 논문집 전문대학교육위원
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• pp.166-170
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• 2003

This paper deals with the power loss analysis of voltage source type space voltage vector modulated soft switching inverter, and proposed the new voltage vector correction principle during one sampling period on realize high quality cutput voltage waveforms for two soft-swiching approches. The operating pinciple of a single active auxiliary resonant DC link snubber circuit is described. Moreover, the effectiveness of soft switching inverter operating under the corrected voltage pattern is proved on the basis of simulation and experimental results.

• 전기학회논문지
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• 제57권2호
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• pp.214-220
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• 2008

Most of converter system could obtain almost unity power factor and make input current sinusoidal waveform, but they have many problems, such as electromagnetic interference and switching losses caused by switching noise in main switch. To solve these problems in hard switching PFC converter, soft switching converter using a resonant between capacitor and inductor is invented In this paper, advantages and disadvantages of conventional ZVT(Zero-Voltage-Transition) soft switching converter using a auxiliary resonant circuit is discussed. Then Improved ZVT soft switching converter proposed. This improved ZVT converter's operation principal, specific property, design scheme of main are described. From Simulation and experiment results of conventional ZVT soft switching and improved ZVT soft switching converter with active snubber, characteristics of the converter are confirmed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.479-480
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• 2010

In this paper, the bi-directional soft switching DC-DC converter using ZCT(Zero Current Transition) method is proposed for using battery application system. This topology is composed of soft switching bi-directional buck/boost converter having the ZCT auxiliary circuit with two switches, two resonant capacitors, one resonant inductor. Therefore, the proposed topology can reduce switching loss. To verify the validity of the proposed topology, theoretical analysis and simulation results are presented.