• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.160-168
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• 2001

The RPWM (Random· Pulse Width Modulation) is a switching technique to spread the voltage and current harmonics over a wide frequency area. By using randomly changing switching frequency of the inverter, the power spectrum of the electromagnetic acoustic noise can be spread to the wide-band area. The wide­band noise is much more comfortable and less annoying than the narrow-band one. So, the RPWM has been attracting interest as an excellent method for the reduction of acoustic noise on the inverter drive system. In this paper a new RPPWM (Random Position Space Vector PWM) is proposed and implemented. Each of three phase pulses is located randomly in each switching interval. Along with the randomization of PWM pulses, the space vector modulation is also executed in the C167 micro-controller. The experimental results show that the voltage and current harmonics are spread to a wide band area and that the audible switching noise is reduced by the proposed RPPWM method.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.178-186
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• 2004

This paper proposes a two-phase RCD-PWM scheme which is much better than a three-phase RCD-PWM scheme from the standpoint of the broadening and linearizing effect of the power spectrum. To implement the proposed scheme and conventional scheme, the experiment based on the SAB-Cl67 micro-controller was executed. Based on the space vector modulation technique, the duty ratio of the pulses is calculated using the SAB-Cl67 and each of PWM pulses is located randomly in each switching interval. The power spectrum of the output voltage, output current, the d.c link current and the acoustic noise radiated from inverter drives are experimentally investigated. 1'hen, the performance of the proposed scheme was compared and discussed with the conventional scheme.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.6 no.2
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• pp.56-61
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• 1992

This paper is reported on the simulation and test results of a constant flux vector control scheme of an induction motor without any speed detecting eqiupment, in which the adaptive current PWM inverter is used. The rotor speed is estimated form stator voltage, current and parameters of motor, and control algorithm in the system is performed with by micro processor. By comparing the waveform of input current of this system with that of the case with taco-generator, good agreement is observed except small ripple component. Experimental results which are acquired at start up and during acceleration/deceleration are quite similar to those of the simulation results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4975-4983
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• 2010

In this paper, the ordinariest and strongest simulator that many used to power electronics circuits and many different control technology can apply to more easily understand modeling the element, PSPICE and MATLAB are adapted a micro IGBT, a macro IGBT, PWM generator and to library moeling of validity of the Induction motor is interpreted. Micro IGBT model of demagnetization quality proved for modeling accuracy to through experiment, macromodel IGBT were simulated which the applied to voltage type PWM inverter to the cyclo-converter and induction motor of demagnetization.

• Journal of Welding and Joining
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• v.19 no.6
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• pp.622-629
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• 2001

The aim of this experiment is to establish the method that obtains symmetrically two nuggets in microresistance series spot welding. The sheets of austenite stainless steel STS304 applied to various electronic parts were experimented by the inverter welding power source of polarity controllable type and by the twin head for left and right electrode force to be controlled separately. The experimental results were obtained as follows : 1) When series spot welding was carried out by DC 1 pulse as welding current with same electrode force at left and right, the asymmetry of nuggets was resulted from the larger nugget of the (-) pole because of the Peltier effect. The dynamic resistance of weld spot at left and right was appeared differently according to the growth of nuggets. 2) When AC 1 cycle by welding power source of polarity controllable type was applied, the nuggets were almost symmetrically formed. 3) In a twin head, if the electrode force of (-) pole was larger than that of (+) pole, the diameters of two nuggets became to same. It was confirmed that the dynamic resistance of (-) pole was decreased to the same level as it of (+) pole. 4) Although the forces of left and right electrode were same, and only DC 1 pulse was applied, symmetric nuggets were obtained if the conductivity of (+) pole was lower than it of (-) pole.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.205-206
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• 2011

태양광 발전용 마이크로 인버터는 PV 모듈에 직접 설치되기 때문에 크기, 무게 등이 중요한 설계 요소다. 따라서 출력 필터 설계 시 전력 품질 뿐만 아니라 필터에 사용되는 수동 소자의 크기 또한 고려해야 한다. 본 논문에서는 마이크로 인버터용 출력 필터로서 Trap-CL 구조를 분석하고, 필터의 소형화를 고려한 설계 기법을 제안한다. 설계 된 Trap-CL 필터의 특성을 단상 플라이백 인버터에 적용하여 확인하였으며, 기존 플라이백 인버터에 사용되던 CL 필터와의 비교를 통하여 그 타당성을 검증하였다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.10
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• pp.445-451
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• 1986

The speed control system of induction motor without speed sensor is proposed in this paper. The speed of induction motor is calculated by motor terminal voltages and currents. The equations for speed calculation are derived and they are implemented on 16bit micro-processor Mc68000. The software and hardware for the Mc 68000 is developed. To prove the validity of the proposed method, the calculated speed is compared with the measured speed. The maximum speed error is nearly 1% in the overall range. The proposed speed calculation method is applied to the Current Source Inverter(CSI) fed induction motor drive system. The experimental results show the good dynamics and the resonable speed control accuracy.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.496-499
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• 1991

Photovoltaic system has very low energy conversion efficiency and the output characteristics of solar cell is varied by the Insolation quantity and the temperature. In order to improve the efficiency of photovoltaic system, the energy which has got from solar cell must be use maximum. In this paper, it was stimultaneous executed both MPPT control and instrumentation in order that the operating point of solar cell is located maximum power point, using the PWM inverter and micro-computer, which is for the purpose of acquiring maximum power from the solar cell. As a result, maximum power point tracking had carried out and the efficiency of photovoltaic system improved, even if insolation quantity and the temperature are varied.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.637-640
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• 1991

In this paper deals with linearized control of induction motor by vector control. Output equation induced from d-q axies voltage and current equation of induction moter. The condition of induced equation is that rotor's current of axies has 0 and state current of D axies which was driven by synchronous speed is constant. The fully digital controlled induction motor drive system based on the proposed linearized method and the control circuit of system consists of 16bits micro computer and all the function are implemented with software. When the voltage source inverter control with PI controller is empolyed, in spite of secondary resistance Rr Variation, the Vector control condition is satisfied.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1045_1046
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• 2009

This paper presents an active and reactive power compensator for the wind power system with squirrel-cage induction generator. The developed system is able to continuously compensate the active and reactive power. The 3-phase inverter operates for the compensation of reactive power, while the DC/DC converter with super-capacitors operates for the compensation of active power. The proposed compensator can be expected that developed system may be used to compensated the abrupt power variation due to sudden change of wind speed or sudden power-drop by tower effect. It can be also applied for the distributed generation and the Micro-Grid.