• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.82-93
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• 2006

In this paper, filters are designed to reduce transients overvoltage in inverter fed high-voltage large-capacity induction motor drive system. Design issues for a LCR filter at the inverter output terminals to reduce the dv/dt of the inverter output pulse and a RC filter at the induction motor input terminals to match the characteristic impedance between cable and induction motor are examined in detail. These filters are modeled to be suitable to high-voltage large-capacity induction motor. The performance of the filter is evaluated through simulation using EMTP(ElectroMagnetic Transients Program). We presented filters that used high voltage large-capacity induction Motor on the basis of this. Effect of the filter is analyzed for variation of the cable length. Characteristics of filters are analyzed to reduce harmonic in voltage waveform of induction motor input terminal. The switching surge voltage became the major cause to occur the insulation failure by serious voltage stress in the stator winding of induction motor. Filter for to mitigate transients overvoltage presents a required component in drive system of high-voltage large-capacity induction motor. Also, proposed filters are proved through simulation using EMTP.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.644-649
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• 2001

This paper proposes a soft-switching current -source inverter for photovoltaic power system, which has an H-type switched-capacitor module composed of two semiconductor switches, two diodes, and an L-C resonant circuit. The operation of proposed system was analyzed by a theoretical approach with equivalent circuits and verified by computer simulations with SPICE and experimental works with a hardware prototype. The proposed system could be effectively applied for the power converter of photovoltaic power system interconnected with the power system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.8
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• pp.402-407
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• 2001

This paper proposes a soft-switching current source inverter for photovoltaic power system, which has an H-type switched-capacitor module composed of two semiconductor switches, two diodes , and an L-C resonant circuit. The operation of proposed system was analyzed by a theoretical approach with equivalent circuits and verified by computer simulations with SPICE. The feasibility of hardware implementation was verified by experimental works with a prototype. The proposed system could by effectively applied for the photovoltaic power system with high efficiency.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2616-2619
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• 1999

The Backlight inverter used in the laptop computer is designed in this study. It has been difficult for electromagnetic transformer to enhance the efficiency and compact profile. In this study, (l) the piezoelectric transformer(PT) is used for reducing the loss: (2) the volume of core and winding coil are used in electromagnetic transformer, and (3) the zero voltage switching(ZVS) is used in the driver of the resonant circuit. The modified PT for this paper and the equivalent circuit are supported by the simulation program. ZVS is achieved by Half-Bridge inverter circuit. The result of the experiment shows more than 91% improvement in terms of the efficiency.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.337-345
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• 2003

In the case of heat exchangers operating under frosting condition, the growth of frost layer causes the heat exchanger to increase the thermal resistance and pressure loss of the air flow. In this paper, a transient characteristic prediction model of the heat transfer for multi inverter heat pump with frosting on its surface was presented taking into account the change of the fin efficiency due to the growth of the frost layer. In this dynamic simulation program, which was peformed for a basic air conditioning system model, such as evaporator, condenser, compressor, linear electronic expansion valve (LEV) and bypass circuit. The theoretical model was driven from the obtained heat transfer coefficient and mass transfer coefficient, independently. And we consider heat transfer performance was only affected by a decrease of the wind flow area. The calculated results were compared with some cases of experiments for frosting conditions.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.278-280
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• 2003

As the use of ASD due to developing of power electronics technology was increased, the failure of induction motor by switching surge also was increased. This paper presented a switching surge modeling of inverter and a induction motor modeling using EMTP program. As a output waveform of square wave inverter and PWM inverter and the input terminal waveform of induction motor were shown, the effect of switching surge was analyzed.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.5
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• pp.627-634
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• 2006

We have proposed the methods how to control the slope of CMOS inverter's characteristic and how to shift it in y axis. We control the MOS transistor threshold voltage for these methods. By observing that two transistors are in saturation region at the center of the CMOS inverter's characteristic, we have presented how to make the characteristic for one pole neuron. The circuit level simulation is used for verifying the proposed method. PSpice(OrCAD Co.) is used for circuit level simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2320-2323
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• 2014

Piezoelectric inverter for driving CCFL is designed in this study. Of them, CCFL is generally used because it has advantages such as small size, high efficiency and good brightness characteristics. the description of the piezoelectric effect is not present here and can be easily found in numerous publications as well as complex equations and formulae. What is the most important to understand is that "they are different" one cannot just change an electromagnetic transformer(EMT) for a piezoelectric one. The simulation program supports the modeled piezoelectric inverter for this paper and the equivalent circuit. The result of the experiment shows more than 90% improvement in terms of the efficiency.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.950-954
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• 1998

This paper describes a development of traction unit for 2-motor driven electric vehicle (EV). The traction unit is consisted with an interior permanent magnet synchronous motor (IPMSM), a reduction gear and an inverter for electric vehicle that is driven by 2 motors without differential gear. For traction unit, prototype IPMSM and inverter have been developed. The IPMSM was designed by CAD program that was developed with both equivalent circuit method and FEM. Also the inverter was developed to drive 2 motors with 6 legs IGBT switches in a control board. The vector control algorithm was implemented with maximum torque control method in the constant torque region and field weakening control method in the constant power region considering inverter capacity. To verify that the traction unit is more high efficiency and has more high power density than a traction unit with induction motor with the same power, we would like to show the results about the design and analysis of the IPMSM and the experiment results about the traction unit.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.1
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• pp.27-34
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• 2010

To dissipate the heat generated from the switching devices in the inverter system of HEV, the water cooling structure is proposed. The bolt type cooling structure has a problem such as water leakage for high pressure of water, therefore the proposed cooling structure applied pipe structure in the heat sink. The heat dissipation characteristics for various structures of water channel and distance between heat source and water channel was analyzed through the simulation. heat dissipation effect for two types of water cooling structures was investigated. Based on the simulation results, two types of water cooling system for 30kW inverter system of HEV were manufactured and the heat dissipation effect was verified.