• 전자공학회논문지T
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• 제35T권2호
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• pp.39-47
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• 1998

가변구조 제어기는 이론적으로 빠른 응답특성을 가지며 오버슈트가 없고 외란이나 파라미터 변동에 강인한 제어기로 알려져왔다. 그러나 가변구조 제어기는 모델링과정에서 무시된 플랜트의 고주파 동특성을 여기할 수 있고, 또 시스템을 구성하는 소자들에 손상을 줄 수 있는 채터링현상이 발생하기 때문에 산업현장에서 널리 적용되지 못하고 있다. 본 논문에서는 채터링을 저감시키기 위한 개선된 가변구조 제어기를 제안하고 유도전동기의 위치제어에 적용한다. 기존의 가변구조 제어기는 한 개의 스위칭면을 중심으로 고주파 스위칭을 행하여 시스템의 구조를 절환한 반면에, 개선된 가변구조 제어기는 한 개의 면 대신 슬라이딩 영역을 이루기 위해 두 개의 스위칭면을 가지며 이 영역 내에서 저주파 스위칭으로써 시스템 구조를 절환하게 된다. 그러므로 제안된 알고리즘은 기존의 가변구조 제어기가 가지는 빠른 응답성이나 강인성을 유지하면서 고주파 채터링을 저감시키는 특징을 가지며 전동기정수 변동에도 양호하게 동작하고 있다. 제안하는 제어기의 타탕성을 확인하기 위해 실험을 행하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권5호
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• pp.352-357
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• 2000

This paper presents about an example of circuit design and characteristics of inverter according to the variable capacitance of the DC voltage source separation capacitor used in ZVS-HB type high frequency resonant inverter. The soft switching technology known as ZVS is used to reduce turn off loss at switching. In the event the capacitance of the DC voltage source separation capacitor is varied, the analysis of inverter circuit has generally described by using normalized parameter and operating characteristics have been evaluated in terms of switching frequency and parameters. According to the calculated characteristics value, a method of the circuit designs and operating characteristic of the inverter is also presented in this paper. In addition, this paper proves the validity of theoretical analysis through the experiment. This proposed inverter shows that it can be practically used in future as power source system for the lighting equipment of discharge lamp, DC-DC converter etc.

• Journal of Power Electronics
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• 제9권6호
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• pp.823-834
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• 2009

This paper proposes a high-efficiency single-stage ac/dc converter. The proposed converter features low voltage stresses and reduced switching losses. It operates at the boundary of discontinuous- and continuous-conduction modes by employing variable switching frequency control. The turn-on switching loss of the switch can be reduced by turning it on when the voltage across it is at a minimum. The voltage across the bulk capacitor is independent of the output loads and maintained within the practical range for the universal line input, so the problem of high voltage stress across the bulk capacitor is alleviated. Moreover, the voltage stress of the output diodes is clamped to the output voltage, and the output diodes are turned off at zero-current. Thus, the reverse-recovery related losses of the output diodes are eliminated. The operational principles and circuit analysis are presented. A prototype circuit was built and tested for a 150 W (50V/3A) output power. The experimental results verify the performance of the proposed converter.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권2호
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• pp.114-122
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• 2004

This paper presents a novel single-stage active-clamp type high frequency resonant inverter. The proposed topology is integrated full-bridge boost rectifier as power factor corrector and active-clamp type high frequency resonant inverter into a single-stage. The input stage of the full-bridge boost rectifier works in discontinuous conduction mode(DCM) with constant duty cycle and variable switching frequency. So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. By adding additional active-clamp circuit to conventional class-E high frequency resonant inverter, main switch of inverter part operates not only at Zero-Voltage-Switching mode but also reduces the switching voltage stress of main switch. Simulation results have demonstrated the feasibility of the proposed high frequency resonant inverter. Characteristics values based on characteristics estimation through circuit analysis is given as basis data in design procedure. Also, experimental results are presented to verify theoretical discussion. This proposed inverter will be able to be practically used as a power supply in the fields of induction heating applications, fluorescent lamp and DC-DC converter etc.

• 전자공학회논문지SC
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• 제38권1호
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• pp.53-60
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• 2001

전력전자의 많은 응용분야에서 고주파 공진형 인버터가 이용되며, 이들 공진형 인버터의 출력 전력을 제어하기 위하여는 PAM(Pulse Amplitude Modulation), PFM(Pulse Frequency Modulation) 혹은 PWM(Pulse Width Modulation) 기법들이 이용된다. 그리고 이들 공진형 인버터는 변화하는 부하 상태에서도 신뢰성 있게 동작하기 위하여 출력추파수를 제어하여야 한다. 본 논문에서는 공진형 인버터의 PWM 제어의 일환으로써 새로운 스위칭 방법을 제안하였다. 제안한 방법에 의하면, 변화하는 공진 주파수하에서도 최적의 공진 주파수와 출력 기본파 역률 1을 달성할 수 있다. 제안한 PWM 스위칭 방법의 상세한 알고리즘 및 출력특성을 기술하였다. 그리고 실험 결과를 통하여 제안한 방법의 타당성을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.525-527
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• 1996

Hysteresis current control is one of the simplest techniques used to control currents for high speed drive systems, because of its simplicity of implementation, fast current control response, and inherent peak current limiting capability. However the conventional fixed-band hysteresis control has a variable switching frequency throughout the fundamental period, and consequently the load current harmonics spreaded on the wide frequency range. In this paper, a simple, novel alterative approach is proposed for a variable-hysteresis band current controller which uses feedback techniques to achieve constant switching frequency with good dynamic response. The method is easily implemented in hardware, the resultant controller is easily tuned to a particular load, and has good immunity to variation in PV parameter and dc supply voltage.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.166-171
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• 2008

본 논문은 가변주파수 스위칭 방식의 flyback 컨버터를 이용한 자동차용 35[W]급 고휘도 방전 램프용 전자식 안정기의 고효율 제어시스템을 구현하였다. 또한 안정기 성능, 크기 그리고 효율을 고려하여 planar 변압기를 이용하여 flyback 컨버터를 설계하였다. HID 램프를 자동차에 적용하기 위해 복잡한 과도특성을 제어할 수 있는 매우 복잡한 제어회로와 고효율의 안정기의 제작이 요구되어진다. 제안된 전자식 안정기는 planar 변압기를 사용한 flyback 컨버터, full bridge 인버터와 승압 점화장치로 구성되어 있으며, flyback 컨버터의 스위칭 주파수는 안정기에 입력전압의 변화에 따라 제어되도록 설계하였고, planar변압기를 사용하여, 안정기의 가격과 크기를 크게 절감할 수 있었다. 제안된 시스템에 대한 성능 및 효율은 여러 가지 실험을 통해 확인하였다.

• Journal of Power Electronics
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• 제4권3호
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• pp.138-151
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• 2004

In this paper, a constant frequency phase shifting PWM-controlled voltage source full bridge-type series load resonant high-frequency inverter using the $4^{th}$ generation IGBT power modules is presented for innovative consumer electromagnetic induction heating applications, such as a hot water producer, steamer and super heated steamer. The bridge arm side link passive capacitive snubbers in parallel with each power semiconductor device and 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 evaluated and discussed 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 inverter topology, what is called, DE class type, including the variable-power variable-frequency regulation function can expand zero voltage soft switching commutation area even under low output power setting ranges, which is more suitable and acceptable for newly developed induction heated dual pack fluid heaters. Furthermore, even the lower output power regulation mode of this high-frequency load resonant tank inverter circuit is verified so that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2534-2536
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• 1999

This paper suggested a new sensorless driving strategy for brushless de motor which can improve the conventional degradation of highspeed operating performances, lowspeed operating performances and starting performances caused by applying general single pwm switching frequency. By varying PWM switching frequency during operating time, the proposed method can get some desired upper performances. For confirming the validity of the proposed method, the sensorless driving system is implemented with an rPM module and 87c196MC micro controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.409-411
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• 1999

Usually, in many applications. high frequency resonant inverters are used and the ZVS(Zero Voltage Switching) or ZCS(Zero Current Switching) techniques are used to improve the efficiency of resonant inverters. In this paper, a new switching scheme is proposed to improve the efficiency of resonant inverters which is based on the plan to keep the unity output displacement factor under the variable resonant frequency. The detail algorithm of the proposed switching sheme and the simulation results are presented.