• Journal of Power Electronics
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• 제11권4호
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• pp.520-526
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• 2011

This paper presents a balanced soft-chopping circuit and a modified PI controller for a high speed 4/2 Switched Reluctance Motor (SRM) with a 16 pulse per revolution encoder. The proposed balanced soft-chopping circuit can supply double the switching frequency in the fixed switching frequency of power devices to reduce current ripple. The modified PI controller uses maximum voltage, back-emf voltage and PI control modes to overcome the over-shoot current due to the time delay effect of current sensing. The maximum voltage mode can supply a fast excitation current with consideration of the hardware time delay. Then the back-emf voltage mode can suppress the current over-shoot with consideration of the feedback signal delay. Finally, the PI control mode can adjust the phase current to a desired value with a fast switching frequency due to the proposed balanced soft-chopping technology.

• 한국조명전기설비학회지:조명전기설비
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• 제13권2호
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• pp.220-220
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• 1999

This paper describes the high efficiency inverter ballast circuit using very cheap microprocessor, which has been developed by the author. A variety of soft-switching techniques have been proposed to reduce the switching losses and EMI problems that occur with higher switching frequencies in switched inverter ballast. The inverter ballast circuit, which employs a temperature sensing circuits has been also proposed to improve starting performance of the fluorescent lamps. That is, the inverter ballast circuit, which employs a soft-starting circuit and soft-switching techniques to implement the power factor correction and to mitigate of power-loss and increase a life time of the fluorescent lamps, has become an attractive performance for ballasting the fluorescent lamps. In this paper, the operation and the control of the inverter ballast are described in detail and experimental results are presented. As the experimental results, when environment temperature is at -40℃, the inverter ballast circuit has low THD(4.8%) of the input current and large power factor(98%) of the lamp current. The proposed improved ballast circuit appears to be a good performance for ballasting fluorescent lamps.

• 전력전자학회논문지
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• 제25권6호
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• pp.484-489
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• 2020

This study proposes a new soft-switching three-level flying capacitor converter with low filter inductance. The proposed converter can achieve zero voltage switching (ZVS) turn-on of all switches by using auxiliary components La and Ca. It can also reduce filter inductance because the applied voltage of the filter inductor is decreased by using the flying capacitor. Furthermore, filter inductance can be reduced because the operating frequency of the filter inductor is doubled by the phase shifting between switches S3 and S4. The operation principle, design of passive components for ZVS turn-on, interleaving effects, and comparison of different topologies are presented. The experimental waveforms of a 1 kW two-phase interleaved converter prototype are provided to verify the validity of the proposed converter.

• 전력전자학회논문지
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• 제11권2호
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• pp.149-158
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• 2006

본 논문에서는 기존에 널리 사용되는 펄스폭 변조 (Pulse width modulation : PWM) 방식의 컨버터와 공진형 컨버터의 장점을 활용하고 단점을 보완할 수 있는 새로운 형태의 영전류 천이형 (Zero current transition : ZCT) 부우스트 컨버터를 제안한다. 제안한 회로는 기존의 PWM 부우스트 컨버터에 보조회로를 추가하여 주 스위치와 출력 다이오드의 스위칭 천이 순간에만 소프트 스위칭 조건을 제공함으로써 전체적인 동작은 기존의 부우스트 컨버터와 크게 차이가 없도록 하였다. 아울러, 보조회로에서의 부가적인 손실 역시 존재하지 않으므로 해서 고효율이 가능하게 된다. 본 논문에서는 제안한 회로의 동작을 분석하고 이를 바탕으로, 보조 회로의 소자값 결정에 도움이 되는 설계방식을 제공한다. 또한, 실험을 통하여 제안한 회로의 동작 원리 및 유용성을 검증하였다.

• Journal of Power Electronics
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• 제16권5호
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• pp.1629-1638
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• 2016

Differential power processing (DPP) systems are among the most effective architectures for photovoltaic (PV) power systems because they are highly efficient as a result of their distributed local maximum power point tracking ability, which allows the fractional processing of the total generated power. However, DPP systems require a high-efficiency, high step-up/down bidirectional converter with broad operating ranges and galvanic isolation. This study proposes a single, magnetic, high-efficiency, high step-up/down bidirectional DC-DC converter. The proposed converter is composed of a bidirectional flyback and a bidirectional isolated switched-capacitor cell, which are competitively cheap. The output terminals of the flyback converter and switched-capacitor cell are connected in series to obtain the voltage step-up. In the reverse power flow, the converter reciprocally operates with high efficiency across a broad operating range because it uses hard switching instead of soft switching. The proposed topology achieves a genuine on-off interleaved energy transfer at the transformer core and windings, thus providing an excellent utilization ratio. The dynamic characteristics of the converter are analyzed for the controller design. Finally, a 240 W hardware prototype is constructed to demonstrate the operation of the bidirectional converter under a current feedback control loop. To improve the efficiency of a PV system, the maximum power point tracking method is applied to the proposed converter.

• Journal of Power Electronics
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• 제15권2호
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• pp.469-478
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• 2015

In order to promote the application of switched reluctance machines (SRM) in electric vehicles (EVs), the braking torque closed-loop control of a SRM is proposed. A hysteresis current regulator with the soft chopping mode is employed to reduce the switching frequency and switching loss. A torque estimator is designed to estimate the braking torque online and to achieve braking torque feedback. A feed-forward plus saturation compensation torque regulator is designed to decrease the dynamic response time and to improve the steady-state accuracy of the braking torque. The turn-on and turn-off angles are optimized by a genetic algorithm (GA) to reduce the braking torque ripple and to improve the braking energy feedback efficiency. Finally, a simulation model and an experimental platform are built. The simulation and experimental results demonstrate the correctness of the proposed control strategy.

• 전력전자학회논문지
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• 제12권1호
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• pp.98-106
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• 2007

본 논문에서는 개선된 온라인 턴 오프각 제어방식을 이용하여 스위치드 릴럭턴스 전동기의 성능최적화를 위한 온라인 전류제어방식을 제안한다. 성능최적화를 위한 제어방식은 에너지효율의 최대화와 토크리플 저감이라는 두가지 측면에서 접근하며, 두 가지 조건을 모두 만족할 수 있는 최적의 턴 오프 위치각은 제안된 알고리즘의 연산방식을 통해 획득된 턴 오프각 제어기를 통해 구현됨으로서 SRM의 성능최적화를 이룬다. 제안된 제어기는 토크와 전류 특성, 자속변동의 정보와 같은 복잡한 데이터베이스나 SRM이 가지는 고유의 자화곡선을 요구하지 않는다는 장점을 가지며 제안된 연산 제어기를 시뮬레이션과 실험을 통해 실제 적용가능성과 그 타당성을 입증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.210-213
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• 1991

The clamp mode Zero-Volatge-Switched Multi-Resonant-Converter(ZVS-MRC) is proposed. In the converter, the performance of the conventional ZVS-MRC is improved by clamping the drain-to-source voltage of the power switch using a soft switching nondissipative active clamp network. The analysis for each stage of the converter operation modes is presented and is verified by experiments.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.58-61
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• 2003

In this paper, resonant Characteristics of the soft switched asymmetrical half bridge converter is analysis. The operation principle for proposed converter is explained in steady state and its circuit is analyzed by means of equivalent circuit. Experimental results carried out on a system prototype are included in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2512-2514
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• 1999

A new zero voltage and zero current switching(ZVZCS) full bridge DC-DC converter with transformer isolation is proposed for arc welding machines. The proposed DC-DC converter uses an auxiliary transformer to obtain ZCS for leading leg, which provides load current control capability even in short circuit condition. The auxiliary circuit also operates in ZVZCS mode. The power rating of the auxiliary transformer is about 10% of the main transformer. The operation is verified by experiments for 12[KW] prototype.