• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.294-298
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• 2003

In this paper, the new zero-current-transition (ZCT) circuit cell is proposed. The main switch is turned-off under the zero current and zero voltage condition, and there is no additional current stress and voltage stress in, the main switch and the main diode. The Auxiliary switch is turned-off under the zero voltage condition, and the main diode is turned-on under the zero voltage condition, The resonant current required to obtain the ZCT is small and regenerated to the input voltage source. The operational principles of the boost converter integrated with the proposed ZCT circuit cell is analyzed theoretically and verified by the simulation and experimental result. Index terms - zero-current-transition (ZCT), zero-current- switching (ZCS), zero-voltage-switching (ZVS)

• Journal of Power Electronics
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• 제3권4호
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• pp.215-223
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• 2003

In this paper, a new zero-current-transition (ZCT) circuit cell is proposed. The main switch is turned-off under the zero current and zero voltage condition, and there is no additional current stress and voltage stress in the main switch and the main diode, respectively. The auxiliary switch is turned-off under the zero voltage condition, and the main diode is turned-on under the zero voltage condition. The resonant current required to obtain the ZCT condition is relatively small and regenerated to the input voltage source. The operational principles of a boost converter integrated with the proposed ZCT circuit cell are analyzed and verified by the simulation and experimental results.

• 전기전자학회논문지
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• 제20권4호
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• pp.373-377
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• 2016

열전 변환 에너지 하베스팅을 위한 저 전력 부스트 컨버터에 사용하는 새로운 Zero Current Sensor (ZCS)를 이 논문에서 제안한다.새로 제안하는 ZCS를 사용하는 Zero Current Switching은 기존 방식인 아날로그 비교기를 사용한 Zero Current Switching방식 보다 파워 측면에서 큰 장점을 보이고 기존의 다른 방식인 딜레이 라인을 이용하는 Zero Current Switching 방식보다 면적에서 큰 장점을 보인다. 새로운 ZCS는 기존의 아날로그 비교기에 고의적으로 offset을 발생시키고 offset의 양을 digital code로 calibration 하여 출력이 나오는 시간을 조절한다. 새로운 ZCS를 이용한 Zero Current Switching은 기존의 아날로그 비교기를 이용한 Zero Current Switching 보다 대략 10배정도 적은 파워를 사용하면서 같은 성능을 보인다.

• 조명전기설비학회논문지
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• 제24권12호
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• pp.9-16
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• 2010

In this paper, we have proposed a new dimmable magnetic ballast for HID(High Intensity Discharge) lamps consisted of AC switches to variate inductance value by using Silicon Controlled Rectifiers and the isolated zero current detector on inductor. Conventional dimming ballast has used relays or Solid State Relays in AC switches. However, a relay is difficult to zero current switching, because it has long operating time(10[ms]), and price competitiveness of SSR is very low. The proposed AC switches are suitable to switch at zero inductor current and it is accurately detected by using a opto-coupler. SCR is cheaper than SSR, and it is suitable to switch at zero inductor current because SCR is automatically turned off under holding current at no gate signal. Operating principles, simulation results and experimental results of the proposed ballast are described.

• 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.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1998년도 학술발표회논문집
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• pp.120-124
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• 1998

In this paper, new zero voltage and zero current switched PWM(Pulse Width Modulated) converters are suggested. The main and auxiliary switch of the converters satisfy soft switching conditions, which are zero voltage or zero current switching of the switches. The switching characteristics of the proposed converters are experimentally verified by boost typed converter, which has 250 kHz switching frequency. For the 250 kHz operation, turn on period of auxiliary switch is about 1/40 for switching period of 4 ${\mu}\textrm{s}$. Therefore, the conduction loss of auxiliary switch is reduced.

• Journal of Power Electronics
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• 제19권1호
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• pp.278-287
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• 2019

In this study, a zero-crossing spike current issue in a totem-pole bridgeless power factor correction (PFC) converter is comprehensively investigated for the first time. Spike current occurs when input voltage crosses zero, becomes a noise source, and causes severe common mode emission issues. A generation mechanism for electromagnetic interference (EMI) is presented to investigate the EMI problem caused by zero-crossing issue, and a noise spectrum due to this issue is predicted by a theoretical analysis based on the Fourier coefficient of an approximate spike current waveform. Furthermore, a noise reduction method is proposed and then improved to reduce the spike current. Experimental measurements are implemented on a GaN-based totem-pole bridgeless PFC converter, and the spike current can be effectively suppressed through the proposed method. Furthermore, the noise spectrums measured without and with the reduced zero-crossing spike current are compared. Experimental results validate the analysis of the noise spectrum caused by the zero-crossing spike current issue.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.79-84
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• 1998

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter with low output current ripple is presented. A simple auxiliary circuit added in the secondary provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches, as well as reduces the output current ripple (ideally zero ripple). The auxiliary circuit includes neither lossy components nor additional active switches which are demerits of the previously presented ZVZCS converters. Many advantages including simple circuit topology, high efficiency, low cost and low current ripple make the new converter attractive for high performance high power (＞1kW) applications. The principle of operation, features and design considerations are illustrated and verified on a 2.5kW, 100KHz IGBT based experimental circuit.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.26-27
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• 2011

This paper focuses on the zero-voltage/zero current transition voltage equalization circuit for the series connected battery cell. By adding auxiliary resonant cells at the main switching devices such as MOSFET or IGBT, zero current switching is achieved and turned off loss of switching elements is eliminated and by the voltage/second balancing of the inductor, zero voltage switching can be applied to switching element. Transformer coupling between battery cells and ZVZCT (Zero Voltage Zero Current Transition) switching method allow the fast balancing speed and high frequency operation, which reduces the size and weight of the circuit. The validity of the battery equalization is further verified using simulation involving four lithium-ion battery cell models.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1241-1250
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• 2018

Parallel three-phase voltage source inverters in a direct connection configuration are widely used to increase system power ratings. A zero-sequence circulating current can be generated according to the switching method; however, the zero-sequence circulating current not only distorts current, but also reduces the system reliability and efficiency. In this paper, a model predictive control scheme is proposed for parallel inverters to drive an interior permanent magnet synchronous motor with zero-sequence circulating current suppression. The voltage vector of the parallel inverters is derived to predict and control the torque and stator flux components. In addition, the zero-sequence circulating current is suppressed by designing the cost function without an additional current sensor and high-impedance inductor. Simulation and experimental results are presented to verify the proposed control scheme.