• Journal of Institute of Control, Robotics and Systems
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• v.6 no.3
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• pp.235-240
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• 2000

In this paper a digital-control algorithm of a power system suing a high-speed PWM for a MRI system is proposed. The MRI system requires an elaborate ladder-shaped current source. And the load of current source is the inductance with resistance. For the inductive load a voltage output of the power system has hi호 frequency components. Therefore this system requires high-speed PWM above 80KHz, A high speed PWM control algorithm which satisfies those conditions is designed. Finally the performance of proposed control algorithm is shown by simulation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.387-392
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• 1999

The micro electronic control technology with developing microcomputers make great contribution to electrohydraulic control systems. The electrohydraulic pulse control simplifies in conjunction with power electronic amplifier and high speed operated solenoid valves. It is necessary to valves to convert electronic pulse signal to hydraulic pulse flow as fast as possible. This study deals with the speed control of an oil hydraulic motor operated by two way high speed solenoid valves. The valves acts as converters of electronic-pulse signals to hydraulic power. By constructing systems in which a hydraulic motor is operated by two solenoid valves, the pulse with modulation method (PWM) has adopted as the speed control of hydraulic motor systems. The static and dynamic characteristics of the systems are investigated by the experiment. It is clarify that a hydraulic motor operated PWM show good performance as a control component, achieving accurate velocity control.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.283-288
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• 2000

This paper proposes a novel Pulse Width Modulation (PWM) method for microprocessor implementation of full-bridge PWM inverters. In the method, the period of unipolar full-bridge inverters is divided equally into the frequency modulation ratio and the reference fundamental amplitude and the inverter output fundamental amplitude are compared. Using this method, the turn-on time computation of each interval is very favored for the microprocessor implementation. The harmonic analysis shows that the harmonics can be ignored when the modulation ratio is enough large. The simulation and experimental results show the effectiveness of the proposed algorithms.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.3
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• pp.246-253
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• 2000

전동기의 제어기법과 제어기 등의 발달로 유도전동기는 산업용으로 널리 보급되고 있으며, 유도전동기를 고효율로 제어하기 위하여 PWM 인버터가 널리 사용되고 있다. 그리고 IGBT와 같은 고속 스위칭 소자의 발달로 인해 전압형 PWM 인버터의 스위칭 주파수가 증가가 가능하게 됐으며, 그로 인해 매우 우수한 동작 특성을 가지게 되었다. 그러나 고속 스위칭은 전압과 전류의 급격한 변화로 인해 매 스위칭마다 발생하는 고주파 성분의 커먼 모드전압과 전류를 발생하게 되고 이들은 베어링 전류와 축전압, 전도 및 방사 EMI, 기기의 절연수명 단축, 등의 악영향을 유발한다. 본 연구에서는 이러한 커먼 모드 전압과 전류에 대한 시스템 레벨 해석이 가능한 시뮬레이션 기법에 대해 실제 측정과 시뮬레이션을 통해 검정하였다. 이를 통해서 커먼 모드 전압과 전류가 PWM 인버터 시스템의 각 부에 미치는 영향을 쉽게 확인 할 수 있으며, 커먼 모드 전압과 전류의 저감을 위해 추가될 수 있는 부가적인 보조회로의 영향에 대해서도 제시된 시뮬레이션 기법을 통해 확인 할 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1552-1557
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• 2007

In this work, temperature stable pulse width modulation controller using bandgap reference voltage is proposed. Two bandgap reference voltages are designed by using BiCMOS technology which are temperature dependent and independent voltage references. PWM controller is designed by using 3.3 volt supply voltage and the output frequency is 1MHz. From simulation results, the variation of output pulse width is less than form +0.86% to -0.38% in the temperature range $0^{\circ}C\;to\;70^{\circ}C$.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.277-279
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• 2007

본 논문에서는 댐핑저항을 사용하지 않고 LCL필터를 사용한 AC/DC PWM 컨버터를 제어하기 위해 다중 구조의 궤환 선형화 제어 알고리즘을 제안한다. 일반 궤환선형화와는 달리 다중구조를 지니므로 컨버터 입력전류의 제한이 가능하다는 장점을 지닌다. 전원전압과 전원전류를 추정하기 위해 추정기가 사용되며 시뮬레이션을 통해 제안된 제어기의 성능이 검증된다.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.230-238
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• 2003

In this paper, Inverter drives adopting 2 phase space vector SRP-PWM (Separately Randomized Pulse Position PWM) with fixed switching frequency is proposed. The proposed 2 phase space vector SRP-PWM scheme is based on the 3 phase SRP-PWM. In the proposed SRP-PWM scheme, each of two phase pulses is located randomly in each switching interval. The experimental results show that the voltage and acoustic noise harmonics are spread to a wide band area. Also, the performance of the proposed 2 phase SRP-PWM and the conventional center aligned SVM are compared to each other. In result, the speed response is nearly similar to each other from the viewpoint of the v/f constant control.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.151-164
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• 2003

In this paper, induction motor drives with low switching acoustic noise based on the 2 phase modulated RLL(Random Lead-Lag) PWM is proposed and implemented. The proposed switching method is much bettor than 3 phase modulated RLL-PWM from the standpoint of the broadening effect of the acoustic noise spectrum. Along with the randomization of PWM Pulses, SVM(Space Vector Modulation) is executed in the TMS320C31 DSP(Digital Signal Processor). To verify the validity of the proposed RPWM(Random PWM), the experimental study was tried. The experimental results show that the performance of the proposed method and the 3 phase center-aligned SVM / conventional RLL-PWM are nearly the same from the viewpoint of the constant v/f centrel. But, in case of the proposed 2 phase modulated RLL-PWM, the spectrum characteristics of the voltage and the switching acoustic noise are shown to have better broadening effect than 3 phase modulated one.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.851-858
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• 2017

In this study, the voltage control system of a single phase full bridge inverter was designed based on the SPWM driving method. The voltage control system consists of a single-phase full-bridge inverter, a PI controller for linearly compensating the error between the reference voltage and the output voltage, a PWM driving circuit for generating the gate signal using the SPWM method from the controller signal, and an LC filter for filtering the inverter output voltage waveform into sinusoidal waveform. Finally, the voltage control system of a single-phase full-bridge inverter based on the PWM driving method was modeled using EMTP-RV and by showing that the output voltage accurately converges the reference voltage through several simulation examples, the validity of the control system design was verified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1116-1121
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• 2001

Phase shifter has been used as a means of power-flow control and for transient stability improvement in AC transmission system. Until now, phase shifters have been based on an injection transformer. Conventional phase shifters with tap changers require regular maintenance and allow only step-like control of the phase angle. This paper propose a three-phase phase shifter using PWM AC/AC converter, which can improve system response and control stability in the applications. This paper deals with the circuit topology, operating principle so that the features of the phase shifter will be shown through computer simulation, especially using PSIM software.