• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.561-565
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• 2001

This paper proposes a new switching scheme of a static var compensator(SVC) with cascade multilevel inverter which employs H-bridge inverter(HBI). To improve the un­balanced problem of the DC capacitor voltages, the rotated switching scheme of fundamental frequency is newly used. The optimized fundamental switching pattern with low switching frequency is adapted to be suitable for high application. The selective harmonic elimination method(SHEM) allows to keep the total harmonic distortion(THD) low in the output voltage of multilevel inverter. The SVC system is modeled using the d-q transform which calculates the instantaneous reactive power. This model is used to design a controller and analyze the SVC system. Simulated and experimental results are also presented and discussed to validate the proposed schemes.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.4
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• pp.179-184
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• 2005

This paper examines the application of high voltage static var compensator(SVC) with cascade multilevel inverter which employs H-bridge inverter(HBI). A new switching scheme is developed for the SVC system. To improve the unbalanced problem of the DC capacitor voltages, the rotated switching scheme of fundamental frequency is newly used. The optimized fundamental switching pattern with low switching frequency is adapted to be suitable for high application. The selective harmonic elimination method(SHEM) allows to keep the total harmonic distortion(THD) low in the output voltage of multilevel inverter. The SVC system is modeled using the d-q transform which calculates the instantaneous reactive power. This model is used to design a controller and analyze the SVC system. Simulated and experimental results are also presented and discussed to validate the proposed schemes.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.63-65
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• 2004

The recent advancement in the power electronic technique has increased the use of induction motor fed by inverter using high-frequency switching devices. Also the tendency is toward larger size and higher voltage. Therefore, The IGBT (Insulated-Gate Bipolar Transistor) that is high switching frequency element has been using increase. But, The switching surge voltage was occurred by high switching frequency of inverter has appeared a voltage doubling in the motor input terminal due to mismatching of cable characteristic impedance and motor characteristic impedance. Actually, The Switching surge voltage became the major cause to occur the insulation failure by serious voltage stress in the stator winding of induction motor. The short during rise time of switching surge and cable length is increased, the maximum transient voltage seen at the motor terminals increases. In this paper, Analyzed switching surge transient voltage of power cable pulling is used EMTP(Electromagnetic Transient Program) at the induction motor terminal and in cable.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.27-30
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• 2003

This paper describes two novel current fed high frequency resonant inverter can be used as the power supp]y for wax-sealing. This two topology can be obtained higher output frequency than switching frequency by composing modified unit inverter based on conventional half-bridge serial resonant inverter in parallel with input power source. also, By using time-sharing gate control method, this proposed inverter can not only realize the output control of dependence irrespective of the switching frequency using phase-shift but also reduce switching loss because it has ZVS function. Simulation results through the Pspice have demonstrated the feasibility of the proposed inverter. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, DC-DC converter etc.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.3
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• pp.76-81
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• 2002

In high power motor drive system, the hard-switching topology produces severs switching losses and EMI noises. Also the inverter switching frequency is thus limited because of excessive loss and thermal handling problem. The primary purpose of the proposed works on the induction motor drive system is to develop an advanced soft-switching inverter topology that is most suitable for high power induction motor drive applications. To make the optimal selection EMI comparison of the switching losses presented. To verify the proposed design procedure, detailed simulation analysis with theoretical and experimental approaches have been done using laboratory prototype.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.668-672
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• 2001

The utility interactive sinewave modulated inverter for the solar photovoltaic (PV) power conversion and conditioning with a new high frequency pulse modulated link is presented for domestic residential applications. As compared with the conventional full-bridge hard switching PWM inverter with a high frequency AC link, the simplest single-ended quasi-resonant soft switching sinewave modulated inverter with a duty cycle pulse control is implemented, resulting in size and weight reduction and low-cost. This paper presents a prototype circuit of the single-ended zero voltage soft switching sinewave inverter for solar power conditioner and its operating principle. In addition, this paper proposes a control system to deliver high quality output current. Major design of each component and the power loss analysis under actual power processing is also discussed from an experimental point of view. A newly developed interactive sinewave power processor which has $92.5\%$ efficiencty at 4kW output is demonstrated. It is designed 540mm-300mm-125mm in size, and 20kg in weight.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.203-205
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• 2006

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switching mode and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft switching (ZVS) operation ranges and the power dissipation as compared with those of the previously developed high-frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation (PWM) and pulse density modulation (PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.387-390
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• 2006

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit Incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switching mode and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft switching (ZVS) operation ranges and the power dissipation as compared with those of the previously developed high-frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation (PWM) and pulse density modulation (PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.6
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• pp.620-631
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• 2000

A torque ripple reduction technique of direct torque control(DTC) for high power induction motors driven by 3-level inverters with the inverter switching frequency limited around 0.5-1.0kHz level is presented. It is noted that conventional DTC algorithms to reduce torque ripple are devised for applications with relatively high switching frequency above 2-3kHz. Such conventional algorithms can not accomplish satisfactory torque ripple reduction for 3-level inverter systems with lower switching frequency. A new DTC algorithm, especially for low switching frequency inverter system, illustrates relatively reduced torque ripple characteristics all over the operating speed region. Simulation and experimental results show the effectiveness of the proposed control algorithm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.51-57
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• 1998

This paper proposed a novel SIT high frequency resonant inverter having drive signal phase shift control function. Phasor control type inverters using SIT can realize a power conversion on the high switching frequency with low switching loss. Especially, the high output power can be abstained by connecting the output voltage of two unit inverters In serIes. The stability of system using protection circuit for over current and the automatic follow-up control with load variation by PLL is presented. This inverter produce approximately sinusoidal waveform at a high frequency, switching frequency ranging from 180[kHz] to 220[kHz], and is applied to the 2[kW] induction heating. The operating characteristics of this inverter circuit are discussed from a theoretical point of view and compared with experimental results. results.