• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1024-1029
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• 1998

In this paper, the voltage-fed series compensated inductor type load-resonant high-frequency inverter is originally presented for driving a newly-developed silent discharge ozone generating tube. The effective power regulation scheme of this ozonizer is proposed, which is based on PDM (Pulse Density Modulation) related PWM strategy due to DSP implementation. The effectiveness of this inverter type ozonizer is proved in simulation and experiment.

• Journal of Power Electronics
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• v.8 no.4
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• pp.332-344
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• 2008

High frequency AC (HFAC) power distribution systems delivering power through a high frequency AC link with sinusoidal voltage have the advantages of simple structure and high efficiency. In a multiple module system, where multiple resonant inverters are paralleled to the high frequency AC bus through connection inductors, it is necessary for the output voltage phase angles of the inverters be controlled so that the circulating current among the inverters be minimized. However, the phase angle of the resonant inverters output voltage can not be controlled with conventional phase shift modulation or pulse width modulation. The phase angle is a function of both the phase of the gating signals and the impedance of the resonant tank. In this paper, we proposed a pulse phase modulation (PPM) concept for the resonant inverters, so that the phase angle of the output voltage can be regulated. The PPM can be used to minimize the circulating current between the resonant inverters. The mechanisms of the phase angle control and the PPM were explained. The small signal model of a PPM controlled half-bridge resonant inverter was analyzed. The concept was verified in a half bridge resonant inverter with a series-parallel resonant tank. An HFAC power distribution system with two resonant inverters connected in parallel to a 500kHz, 28V AC bus was presented to demonstrate the applicability of the concept in a high frequency power distribution system.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.4
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• pp.175-182
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• 2000

The back-light inverter used in the laptop computer is designed in this paper. It has been difficult for electromagnetic transformer to enhance the efficiency and compact profile of the inverter. In this paper, (1) the piezoelectric transformer (PT) is used for reducing the loss; (2) the volumes of core and winding coil are used in electromagnetic transformer, and (3) the half-bridge series parallel resonant circuit is used in the driver of the inverter. The modified PT for this paper and the equivalent circuit are supported by the simulation program. The result of the experiment shows more than 91% improvement in terms of the efficiency.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.8
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• pp.417-425
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• 1999

This paper presents an effective control scheme with the voltage-fed half-bridge series resonant inverter for induction heating system, which is based upon a load-adaptive tuned frequency tracking control strategy using PLL(Phase Locked Loop) and its peripheral control circuits. The proposed control strategy ensures a stable operation characteristics of overall inverter system and ZVS(Zero Voltage Switching) irrespective of sensitive load parameter variations, specially in the non-magnetic materials as well as power regulation. The detail operation principle and the characteristics of inverter system with the proposed control scheme are described and its validity is verified by the simulation and the experimental results for a prototype induction cooking system rated at 1.2kW.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.271-279
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• 2015

Induction cooking application with multiple loads need high power inverters and appropriate control techniques. This paper proposes an inverter configuration with buck-boost converter for multiple load induction cooking application with independent control of each load. It uses one half-bridge for each load. For a given dc supply of $V_{DC}$, one more $V_{DC}$ is derived using buck-boost converter giving $2V_{DC}$ as the input to each half-bridge inverter. Series resonant loads are connected between the centre point of $2V_{DC}$ and each half-bridge. The output voltage across each load is like that of a full-bridge inverter. In the proposed configuration, half of the output power is supplied to each load directly from the source and remaining half of the output power is supplied to each load through buck-boost converter. With buck-boost converter, each half-bridge inverter output power is increased to a full-bridge inverter output power level. Each half-bridge is operated with constant and same switching frequency with asymmetrical duty cycle (ADC) control technique. By ADC, output power of each load is independently controlled. This configuration also offers reduced component count. The proposed inverter configuration is simulated and experimentally verified with two loads. Simulation and experimental results are in good agreement. This configuration can be extended to multiple loads.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.3
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• pp.231-239
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• 1999

An improved version of current-regulated delta modulator (CRDM) is investigated for the output cunent control of v voltage-source inverters that have transformer-coupled series resonant load and are operated at the resonant frequency. Conventional CRDM has not only CUlTent offset problem but also transformer flux saturation problem when i it is applied to induction heating systems that have transformel-coupled loads. To cope with these problems, the effect of flux saturation is analysed, and simple method to av이d the problem is proposed. And integral type of CRDM is a adopted to remove the cunent offset. The boundaries of integrator gain for stable operation is calculated using the c concept of sliding mode controL The validity of proposed strategy is vel퍼ed through simulations and prototype e experiments.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.4
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• pp.123-129
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• 2003

We propose a high voltage dc-dc converter for a CW (continuous wave) $CO_2$ laser system using a current resonant half-bridge inverter and a Cockcroft-Walton circuit. This high voltage power supply includes a 2-stage voltage multiplier driven by a regulated half-bridge series resonant inverter. The inverter drives a step-up transformer and the secondary transformer is applied to the voltage multiplier. It is highly efficient because of the reduced amount of switching losses by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step up secondary transformer combined with the Cockroft-Walton circuit. We obtained a maximum laser output power of 44 W and a maximum system efficiency of over 16%.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.301-303
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• 2001

In this paper we present a Capacitor Charging Power Supply (CCPS) using a series-resonant three-level inverter topology to improve voltage regulation and use semiconductor switches having low blocking voltage capability such as MOSFETs. This inverter can be operated with two modes, Full Power Mode (FPM) and Half Power Mode (HPM). In FPM inverter supplies the high frequency step up transformer with full DC-link voltage and in HPM with half DC-link voltage. HPM switching method will be adopted when CCPS output voltage reaches the preset target value and operates in refresh mode-charge is maintained on the capacitor. In this topology each semiconductor devices blocks a half of the DC-link voltage[2]. A 15kW, 30kV CCPS has been built and will be tested for an electric precipitator application. The CCPS operates from an input voltage of 500VDC and has a variable output voltage between 10 to 30kV and 1kHz repetition rate at 44nF capacitive load [3]. A resonant frequency of 67.9kHz was selected and a voltage regulation of $0.83\%$ has been achieved through the use of half power mode without using the forced cut off the switch current [1]. The theory of operation, circuit topology and test results are given.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.1
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• pp.48-54
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• 2002

This paper is described the indirect induction heated boiler and induction heated hot air producer using the voltage-fed series resonant high-frequency inverter which can operate in the frequency range from 20 kHz to 50 kHz. A specially designed induction heater is composed of laminated stainless plates, which have many tiny holes and are interconnected by spot welding. This heater is inserted into the ceramic type vessel with external working coil. This working coil is connected to the inverter and turbulence fluid through this induction heater to moving fluid generates in the vessel. The operating performances of this unique appliance in next generation and its effectiveness are evaluated and discussed from a practical point of view.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.3
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• pp.124-128
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• 1999

The object of the present study is to obtain a 20[kHz], 10[kW] rating, high efficiency induction heating system by high frequency serises-resonant inverter. Proposed is a topology that minimize a reactive power, by which direct iOIrt voltage is variable corresponding to the variation of the load, heated-object, and by which the switching of inverter is forced to follow a resonant frequency. And assured that the power foctor of the inverter in a induction heating system is proper about O.96 through the simulation and results.esults.