• 한국위성정보통신학회논문지
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• 제12권2호
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• pp.28-32
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• 2017

본 연구에서는 컨버터를 일정한 주파수로 제어할 수 있는 쿼지 공진형 컨버터를 제안하였다. 제안된 컨버터의 스위치는 쿼지 공진형 컨버터와 유사하게 고주파에서 고효율로 동작할 수 있도록 소프트 스위칭 특성을 갖는다. 또한, 쿼지 공진형 컨버터는 출력전압의 제어를 위해 컨버터의 스위칭 주파수를 변동시키는 데 비하여 제안된 컨버터는 일정한 주파수로 PWM 제어가 가능하다. 따라서 필터설계 및 EMI 필터설계의 최적화가 가능하다. 본 연구에서는 컨버터의 스위치 모드를 해석하여 컨버터의 동작원리를 기술하고, 컨버터의 스위치가 소프트 스위칭 조건을 만족하여 고주파에서도 동작할 수 있음을 보였다. 또한, DC-DC 컨버터에 대하여 100 kHz의 스위칭 주파수로 동작시켜 컨버터가 일정한 주파수로 PWM 제어되는 특성을 비롯한 컨버터의 특성을 시뮬레이션과 실험으로 증명하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권4호
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• pp.471-476
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• 2015

This paper describes a CMOS hysteretic DC-DC buck converter with a constant switching frequency for mobile applications. The inherent problems of a large output ripple voltage that the conventional hysteretic DC-DC buck converters has faced have been resolved by using the proposed DC-DC buck converter which employed a ramp generator circuit to be able to increase a switching frequency. The proposed architecture enables the settling response time of charge pump circuit within the converter to become less than 6us suitable for mobile applications. The proposed DC-DC buck converter was implemented by using 0.35 um BCDMOS process and die size was $1.37mm{\times}1.37mm$. The measurement results showed that the proposed circuit received the input of 3.7 V and generated output of 1.2 V with the output ripple voltages less than 20 mV under load currents of 100~400 mA at the fixed switching frequency of 2 MHz. The maximum efficiency of the proposed hysteretic buck converter was measured to be around 93%.

• 전력전자학회논문지
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• 제22권1호
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• pp.67-74
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• 2017

This study proposes a novel random pulse-width modulation (PWM) technique with a constant switching frequency utilizing a random offset voltage. The proposed PWM technique spreads switching harmonics by varying the position of an active voltage vector without a switching frequency variation. The implementation of the proposed PWM technique is simple because it does not require additional hardware and complex algorithm. The proposed random PWM technique is compared with the conventional PWM technique on the factors of harmonic spectrum, total harmonic distortion, and harmonic spread factor to confirm the harmonic spread effect. The validity of the proposed method is verified by simulations and experiments on a three-phase inverter drive system.

• 조명전기설비학회논문지
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• 제30권3호
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• pp.65-72
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• 2016

This paper discussed the LCL-type & Isolated bidirectional dc-dc converter(BDC) with dual full bridge inverter. In order to verify the analysis of the BDC, Experimental prototype has been designed and implemented to supply constant voltage regardless of loads and proposed a method to select switching frequency that depended on two inductors' inductance ratio and transformer parameters. The proposed converter has been composed of LCL resonant network with unit inductance ratio ($L_r/L_f$=1) and then operated with fixed duty, 50% duty ratio and fixed frequency. There are some characteristics that input voltage and output voltage of the BDC is nearly identical and zero voltage turn-on switching is possible in forward and reverse mode. Finally, it has been showed that BDC is possible to commutate operating mode normally and provide constant output voltage in selected switching frequency.

• Journal of Power Electronics
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• 제10권1호
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• pp.1-8
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• 2010

A new scheme for sliding-mode control (SMC) of DC-DC converters with a constant switching frequency is proposed. The scheme is based on the averaging model and the output signal of the controller is $d^+$ or $d^-$ instead of the on or off signal of a direct sliding-mode (SM) controller or the continuous signal d = $u_{eq}$ of an indirect SM controller. Two approaches using the new scheme are also proposed and the design procedures for a buck converter are given in detail. The first approach called constant $d^+$ and $d^-$ SMC is simple, cost effective and dynamically fast. In order to improve the dynamic characteristics of the reaching phase and to alleviate chattering, the second approach called reaching law SMC is also presented. Analyses and simulation results demonstrate the feasibility of the proposed scheme.

• Journal of Power Electronics
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• 제6권2호
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• pp.95-103
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• 2006

In this paper, a novel prototype of auxiliary switched capacitor assisted voltage source soft switching PWM Single-Ended Push Pull (SEPP) series capacitor compensated load resonant inverter with two auxiliary edge resonant lossless inductor snubbers is proposed and discussed for small scale consumer high-frequency induction heating (IH) appliances. The operation principle of this inverter is described by using switching mode equivalent circuits. The newly developed multi resonant high-frequency inverter using trench gate IGBTs can regulate its output AC power via constant frequency edge-resonant associated soft switching commutation by using an asymmetrical PWM control or duty cycle control scheme. The brand-new consumer IH products which use the newly proposed edge-resonant soft switching PWM-SEPP type series load resonant high-frequency inverters are evaluated using power regulation characteristics, actual efficiency vs. duty cycle and input power vs. actual efficiency characteristics. Their operating performance compared with some conventional soft switching high-frequency inverters for IH appliances is discussed on the basis of simulation and experimental results. The practical effectiveness of the newly proposed soft switching PWM SEPP series load resonant inverter is verified from an application point of view as being suitable for consumer high-frequency IH appliances.

• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.647-657
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• 2011

The present paper proposes a sliding mode control with fixed switching frequency for three-phase three-leg voltage source inverter based four-wire shunt active power filter. The aim is to improve phase current waveform, neutral current mitigation, and reactive power compensation in electric power distribution system. The performed sliding mode for active filter current control is formulated using elementary differential geometry. The discrete control vector is deduced from the sliding surface accessibility using the Lyapunov stability. The problem of the switching frequency is addressed by considering hysteresis comparators for the switched signals generation. Through this method, a variable hysteresis band has been established as a function of the sliding mode equivalent control and a predefined switching frequency in order to keep this band constant. The proposed control has been verified with computer simulation which showed satisfactory results.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.393-404
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• 2016

In this paper, a carrier-based pulse with modulation (PWM) strategy for three-phase three-level inverter is dealt with, which can keep the common mode voltage constant with minimized switching frequency. The voltage gain and the switching frequency in overall operating ranges including overmodulation are investigated and the analytic equations are presented. Finally, the leakage current reduction effect is confirmed by carrying out simulation and experiment. It will be pointed out that the leakage current cannot be perfectly eliminated because of the dead time.

• 전력전자학회논문지
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• 제3권4호
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• pp.382-387
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• 1998

본 논문은 신경회로망을 사용하여 PWM인버터의 스위칭주파수를 일정하게 유지시키기 위한 적응 히스테리시스 밴드 전류제어 방식을 제안하였다. 신경회로망의 지도신호로 중성점전압을 고려한 적응 히스테리시스 밴드 식을 유도하고, 이 전류제어에 적합한 신경회로망의 구조 및 학습 알고리즘을 제시하였다. 시뮬레이션을 통하여 전동기의 동작 상태에 관계없이 스위칭 주파수를 거의 일정하게 유지되며, 전류의 과도응답 특성의 우수함을 확인하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.774-777
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• 2005

In this paper, a constant frequency phase shifting PWM controlled voltage source full bridge-type series load resonant high-frequency inverter using the IGBT power modules is presented for innovative consumer electromagnetic induction heating applications such as a hot water producer, steamer and super heated steamer. The full bridge arm side link passive quasi-resonant capacitor snubbers in parallel with the each power semiconductor device and high frequency AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is discussed and evaluated on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency soft switching PWM inverter topology, what is called class DE type. including the variable-power variable-frequency(VPVF) regulation function can expand zero voltage soft switching commutation range even under low output power setting ranges, which is more suitable and acceptable for induction heated dual packs fluid heater developed newly for consumer power utilizations. Furthermore, even in the lower output power regulation mode of this high-frequency load resonant tank high frequency inverter circuit it is verified that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.