• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.267-271
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• 1990

This paper describes a 3-Phase Quasi-Resonant DC Link Inverter (3-phase QRI), which has two operating modes, ie. inverting mode and rectifying mode. First the 3-Phase QRI is simplified and the resonant circuit is analyzed in comparison with two resonant DC-to-DC converters. This analysis shows that the maximum voltage of resonant capacitor is limited to twice the input voltage irrespective of operating modes. A new simple control method in rectifying mode is suggested, which does not require any other element in power circuit. The characteristic of 3-Phase Quasi Resonant Inverter has been verified by simulation using the proposed control method.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.134-139
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• 2005

This paper presents a cost effective quasi-resonant soft-switching PWM high frequency inverter with minimum circuit components. This inverter can achieve wider soft commutation, simpler power circuit configuration, smaller volumetric size, lower cost and wider power regulation range, higher-efficiency as compared with single ended quasi-resonant ZVS-PFM inverter and active voltage clamped quasi-resonant ZVS-PWM inverter. The operation principle of the proposed inverter is described on the basis of the simulation and experimental results, together with its operating performances in steady state. The operating performances of this unique proposed high frequency inverter based on ZVS and ZCS arms-related soft commutation principle is evaluated and discussed as compared with the active voltage-clamped ZVS-PWM inverter and a conventional single-ended ZVS-PFM inverter. The practical effectiveness of a novel type quasi-resonant soft-switching PWM high frequency inverter using IGBT is actually proved for consumer induction heated appliances as rice cooker, hot water producer, steamer and super heated steamer. The extended bidirectional circuit topology of quasi-resonant PWM high frequency inverter with minimum circuit components is demonstrated, which operate as the direct frequency changer.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.28-32
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• 2017

In this paper, a quasi-resonant PWM converter, which is controlled by constant frequency, has been suggested. As quasi-resonant converter, the switches of the suggested converter has soft switching characteristics, which can operate to high frequency with high efficiency. Comparing with varied controlled frequency of quasi-resonant converter for controlling output voltage, the suggested converter has advantages which optimize filter and EMI filter design at constant switching frequency. The converter has been analyzed by switch mode analysis which verified soft switching operation. Also, the PWM operation and characteristics of the converter are verified by simulation and experiment of 100 kHz DC-DC converter.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.328-331
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• 1990

A new quasi-resonant do link inverter is suggested, which can operate at the constant peak do link voltage irrespective of the magnitude of load current. The inverter is analyzed by using the topological analogy between the proposed inverter and the resonant DC/DC converter. Based on the analysis, an appropriate current controller is developed, which results in low current stress to the resonant capacitor and also enjoys the inherent capability of the current initialization of resonant inductor. For the purpose of confirming the inverter characteristics, some simulation results are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.91-98
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• 1999

An integrated ZCS quasi-resonant converter(QRC) for the power factor correction with a single switch is presented in this paper. The power factor correction can be achieved by the discontinuous conduction mode(DCM) operation of the input current. The proposed converter gives the good power factor, low line current harmonics, and tight output regulation. The input current waveform of the prototype designed using design equations shows about 15% of total harmonic distortion at rated condition. Also, the efficiency and power factor can be obtained about 86% and 0.985, respectively, at rated condition. The proposed converter is suitable for a low power level converter with a tightly regulated low output voltage and switching frequency of more than several hundreds kHz.

• Journal of Power Electronics
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• v.5 no.1
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• pp.29-35
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• 2005

This paper presents a novel prototype of an active auxiliary quasi-resonant snubber(Auxiliary Quasi-Resonant Commutation Block-Link; ARCB)-assisted three phase voltage source soft switching space voltage vector modulated PFC rectifier, which uses Zero Voltage Soft Switching (ZVS) commutation. The operating principles of this digitally-controlled three phase soft switching PWM-PFC rectifier system with an instantaneous power feedback scheme are illustrated and its steady-state performance is evaluated using computer-aided simulation analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.170-175
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• 2000

A new quasi-parallel resonant DC link inverter is proposed for three phase soft switching application. By i inserting only one additional switch, the proposed inverter excludes both voltage stresses and restricted PWM p problems, which are demerits of the conventional resonant inverter. In this paper, the circuit operations are e explained in detail using the operational mode analysis of the proposed inverter and design methods of the r resonant components are suggest('x:l. Lastly, the applicable possibility of the proposed inverter is vel예fied t through the experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.4
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• pp.384-394
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• 1999

This paper deals with a fixed frequency full-bridge inverter type DC-DC high-power converter with high frequency high voltage(HFHV) transformer-coupled stage, which operates under quasi-resonant ZVS transition priciple in spite of a wide PWM-based voltage regulation processing and largely-changed load conditions. This multi-resonant(MR) converter topology is composed of a series capacitor-connected parallel resonant tank which makes the most of parasitic circuit reactive components of HFHV transformer and two additional quasi-resonant pole circuits incorporated into the bridge legs. The soft-switching operation and practical efficacy of this new converter circuit using the latest IGBTs are actually ascertained through 50kV trially-produced converter system operating using 20kHz/30kHz high voltage(HV) transformers which is applied for driving the diagnostic HV X-ray tube load in medical equipments. It is proved from a practical point of view that the switching losses of IGBTs and their electrical dynamic stresses relating to EMI noise can be considerably reduced under a high frequency(HF) switching-based phase-shift PWM control process for a load setting requirements.

• Journal of Power Electronics
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• v.17 no.4
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• pp.860-873
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• 2017

The present article reports an analysis and investigation of a direct AC-AC quasi-resonant converter. A bidirectional power device, whose switching frequency is lower than the frequency of the current passing through the load, is used for its realization. The zero voltage switching mode is described when zero voltage on the power device is available by measuring it with the control system. The continuous current in the resonant inductance by switching the power device at zero voltage is considered, and it is characterized by two sub-modes. A mathematical analysis of the processes has been made and comparative results from the computer simulation and experimental study have been brought. The converter can be used in a wide areas of power electronics: induction heating, wireless power transfer, AC-DC converters, etc.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.477-483
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• 2010

This paper is studied on a novel buck-boost isolated converter for high efficiency and high power factor. The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit, and are driven with discontinuous conduction mode (DCM) according to pulse width modulation (PWM). The quasi-resonant circuit makes use of a step up-down inductor and a loss-less snubber capacitor. The proposed converter with DCM also simplifies the requirement of control circuit and reduces a number of control components. The input ac current waveform in the proposed converter becomes a quasi sinusoidal waveform in proportion to the magnitude of input ac voltage under constant switching frequency. As a result, it is obtained by the proposed converter that the switching power losses are low, the efficiency of the converter is high, and the input power factor is nearly unity. The validity of analytical results is confirmed by some simulation results on computer and experimental results.