• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.484-488
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• 2000

This paper proposes a highy efficient inverter circuit for fluorescent lamp inverters using two state capacitors. A waveform of full-wave rectification used as a direct current power supply at fluorescent lamp inverters contains a lot of harmonic wave from inrush current which is generated near the maximum of input voltage with purse shape when voltage smoothing capacitor is charged. Therefore, In order to suppress inrush current which will result in harmonic wave, This paper proposed a method to control abrupt charging current by use of charging voltage at pre-state capacitor. As the result of it, power factor comes to be improved through the suppression of harmonic wave generation at supply current. Validity as to this experiment is confirmed through simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.176-183
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• 2000

In this paper, sixth order hannonic injected PWM for improving‘ input CWTent distortion of single switch t three phase boost converter is presented. Peliodic sixth order hmmonic ${\gamma}$oltage is inj<:ded in the control circuit t to var${\gamma}$ the duty ratio of the converter switch within one switching cycle. In the result, the input phase c currents are forced to track the input voltage and an 해most unity power factor is obtained. Expelimental r results are verified by converter operating at 400V /6kW with three phase 140V ~220V input and by C02 arc w welding machine which was nonlinear load with 3 $\phi$ 220V input.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.84-90
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• 2013

This paper explains control methods of single-phase grid connected battery charger. Charging mode is control by Constant Current - Constant Voltage method and discharging mode is controlled by active-reactive power control method. Current control method is based on the synchronous reference frame(SRF) PI controller, and the second harmonic of battery current is compensated by an added L-C resonant circuit. Feasibility of the proposed control methods is verified through experiment with a prototype of 5kW single-phase grid connected battery charger.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.91-99
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• 2017

In order to meet the thermal performance analysis accuracy requirements of high density permanent magnet synchronous motor (PMSM), a method of multi physical domain coupling thermal analysis based on control circuit, electromagnetic and thermal is presented. The circuit, electromagnetic, fluid, temperature and other physical domain are integrated and the temperature rise calculation method that considers the harmonic loss on the frequency conversion control as well as the loss non-uniformly distributed and directly mapped to the temperature field is closer to the actual situation. The key is to obtain the motor parameters, the realization of the vector control circuit and the accurate calculation and mapping of the loss. Taking a 48 slots 8 poles high density PMSM as an example, the temperature rise distribution of the key components is simulated, and the experimental platform is built. The temperature of the key components of the prototype machine is tested, which is in agreement with the simulation results. The validity and accuracy of the multi physical domain coupling thermal analysis method are verified.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.568-572
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• 1991

This paper describes the three-phase inverter system for 1/2[HP] induction servo motor, using TMS370C050 single-chip microprocessor. The Power MOSFETs are used for PWM inverter circuit because of the advantages such as less harmonic losses and smaller peak current, less torque ripples and noises. Single-chip microprocessor enables the whole controller to be simple and reduced size as well as to more stable and flexible. The basic structures are shown for the power circuit, including the protection and driving circuitry, and the control loops for inverter control functions. The experimental results are given for the prototype PWM inverter system.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.673-676
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• 2005

In this paper, we proposed the electric circuit using one common arm of H-Bridge Inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and Transformers. and furthermore we suggested the new multi-level PWM inverter using PWM level to reduce THD(Total Harmonic Distortion). and we used the switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1477-1479
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• 2005

In this paper, we proposed the electric circuit using one common arm of H-Bridge inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and Transformers. and furthermore we suggested the new multi-level PWM inverter using PWM level to reduce THD(Total Harmonic Distortion) and we used the switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype 15-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.187-189
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• 2003

Conventional Switched Mode Power Supplies(SMPS) with diode-capacitor rectifier have distorted input current waveform with high harmonic content. Typically, these SMPS have a power factor lower than 0,65. To improve with this problem the power factor correction(PFC) circuit of power supplies has to be introduced. Specially. to the reduce size and manufacture cost of power conversion device, the single-stage PFC converter is increased to demand as necessary of study. in this paper, The comparative analysis of power factor correction circuit using Feedforward control with average current mode flyback converter(single-stage) and boost converter(two-stage). Also, the validity of designed and manufactured high power factor flyback converter and boost converter is confirmed by simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.77-80
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• 2003

Switching Mode Power Supply(SMPS) is widely used in many industrial fields. Power factor improvement and harmonic reduction technique are very important in SMPS. In this paper, we propose the circuit applied Flying Capacitor Snubber for improving power factor of boost converter on fast switching state. Snubber circuit consists of a inductor, two diodes and a capacitor. The losses of switching are reduced by inserting a snubber inductor in the series path of the boost switch and the rectifier diode to control the di/dt rate of the rectifier during it's turn-off. Prior to actual experiment, the circuit analysis Is implemented by PSPICE simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.5
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• pp.527-534
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• 1987

Two phase voltage controlled oscillation was realized by using the Electronic analog simulation of nonlinear simultaneous 2st order equation in terms of vibration and it's usefullness was sustined. Sinde it is complex and expensive to implement the circuits actually which composits and multiplicate the two phase signal squared respectively, this paper is obtained the simplificotion and switching circuit. The circuit introducced in this paper had propotionality of frequency to control input voltage, rapid response time, and little phase error, also this circuit operated with very low THD(Total Harmonic Distortion) and constant amplitude at higher than 10 :1 of frequency ratio.