• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.523-530
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• 1999

This paper presents the on -line techniques of SHE-PvVI\I for GTO current source converter. The look-up t table is linearized with this proposed method so that the tum-on/off periods of the GTO switches can be c computed in real-time for any modulation index. This allows the rapid and continuous regulation of the DC O output current while producing the sinusoidal AC input current waveform and unity power factor. The l linearized S}lE-PW~I technique and the high power factor control scheme are Prolxlsed and their‘ performance i is tested analytically. The validity of this proposed technique is well verified through the simulation and e experimental results.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1090-1100
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• 2017

This paper presents the comparison of starting current characteristics of a three-phase induction motor fed by two types of soft starters. The first soft starter under investigation is a conventional AC voltage controller on the basis of a phase-control technique. The other is the proposed asynchronous PWM AC chopper which is developed from the conventional synchronous PWM AC chopper. In this paper, the proposed asynchronous PWM AC chopper control scheme is developed by generating only two asynchronous PWM signals for a three-phase main power circuit (6 switching devices) from a single voltage control signal which is compared with a single sawtooth carrier signal. By this approach, the PWM signals are independent and easy to implement since the PWM signals do not need to be synchronized with a three-phase voltage source. Details of both soft starters are discussed. The experimental and simulation results of the starting currents are shown. It is found that the asynchronous PWM AC chopper efficiently works as a suitable soft starter for the three-phase induction motor due to that the starting currents are reduced and are sinusoidal with less harmonic contents, when being compared with the starting current waveforms using the conventional phase-control starting technique. Also the proposed soft starter offers low starting electromagnetic torque pulsation.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.466-476
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• 2013

This paper describes a fuzzy control method to control the output voltage of the three-phase Z-source PWM rectifier. A fuzzy control system is a control system based on fuzzy logic, and the fuzzy controller uses a single input fuzzy theory with its fuzzification. Analytical structure of the simplest fuzzy controller is derived through the triangular membership functions with its fuzzification. By setting the membership functions of the fuzzy rules, fuzzy control is achieved. The PI portion of the output DC voltage controller is controlled by fuzzy method. To confirm the validity of the proposed method, the simulation and experiment were performed, The simulation is performed with PSIM and MATLAB/SIMULINK. For the experiment, we used a DSP(TMS320F28335) controller to compute the reference value and generate the PWM pulses. For the transient state performance of the output DC voltage control of Z-source PWM rectifier, the PI controller and fuzzy controller were compared, also the conventional PWM rectifier and Z-source PWM rectifier were compared. From the results, the Z-source rectifier could allow to buck or boost of the output DC voltage. Through the analysis of the transient state, we could observe that the fuzzy controller has better performance than the conventional PI controller.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.3
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• pp.56-63
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• 1999

In this paper, we realize the active PFC(Power Factor Correction) system of BF (Boost Forward) converter with PWM-PFM control technique to control DC output voltage, and to control the input current with sinusoidal wave synchronized by the converter and inverter using power switching element, FET and IGBT. The control circuit of the suggested Boost converter is implemented with a microprocessor 80C196. After making the ratio of output voltage to current as 50V/1A and the duty ratio greater than 0.5. When input voltage is 30V and boost inductance is 1.1mH. We control the voltage changing rate according to the variation of load resistance using a PWM-PFM control technique. And finally we prove experimentally. PF can be improved up to 0.96 using the current shaping technique.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.5
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• pp.57-63
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• 1995

In this paper, 3-Phase PWM AC/DC step up type converter that reduces the harmonics and reactive power of the distribution line is analyzed and the stable control method is proposed as controlling the sinusoidal phase current and phase voltage in phase. In implementation of controller, simple control algorithm is derived as the instantaneous voltage control methods without current sensor. The instantaneous voltage is controled by PWM method and the switching frequency is presented in low range 3 [kHz] for reducing the switching loss. In case of active load, four quadrants operation converter regenerate power from the load to the power source is conducted. Through the computer simulation and experimentation, the proposed control method is justified.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.105-112
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• 2003

Diode rectifier which can't be controlled output voltage and phase control converter as AC/DC converter have low power factor and harmonics of lower order in the line current. In this paper, three phase PWM(Pulse Width Modulation) AC/DC boost converter is studied to solve these problems. The characteristics of a proposed converter are to control the phase of current without current sensor as a very simple control algorithm using circuit parameters only and to apply sinusoidal PWM method with fixed switching frequency due to a difficult design of input filter and switching device. We simulate for the proposed algorithm that high power factor is achieved and DC link voltage has fast dynamic response without ripple in rectifying and regenerating operation. As a result of experiment with circuit parameter(inductor, capacitor) decided in simulation, the proposed converter had high power factor and reduction of low order harmonics as against diode rectifier.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.29-36
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• 2010

In this paper, we propose a single-phase inverter system using new modulation method. The proposed system is composed of a buck-boost converter and an inverter and controlled by PWAM scheme. PWAM method is a new modulation method which is the incorporation of PWM(Pulse Width Modulation) and PAM(Pulse Amplitude Modulation) methods. The DC voltage which is the input voltage of buck-boost converter is converted into a variable DC voltage by buck-boost converter. Also, the variable DC voltage which is the output voltage of buck-boost converter is converted into a sinusoidal AC voltage by inverter. The input voltage of inverter is processed by PWM switching in PWM section and bypassed in PAM section. By using PWAM method, switching action is not existed in PAM section and thus the times of switching is reduced. As a result, the switching loss can be reduced.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1103-1105
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• 2002

A conventional AC-DC boost converter has much variation of input current as more increased the load or output voltage by the hysterical control method that is comparing area of current pulse by using PWM method and integration to sinusoidal input current. To improve the problems. in this paper, we propose the single-phase voltage doubler AC-DC converter circuit using the capacitor for boost:confirm characteristics of normal and transition state by using simulation, be stabilized voltage of doubler capacitor for boost, and Identify to get the sinusoidal input current with unity power factor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.298-302
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• 2012

The linear encoder used in the BLAC driving circuit consists usually analog type sensor, and need signal transform from analog sinusoidal to digital one for application in the PWM algorithm that is used to control motor current. When the motor is driven in low speed, it is required many operations and higher quality DSP to convert the hole sensor signal to digital one with enough resolution. In this paper, the another method to convert that signal with enough resolution without calculation of sine function is proposed. This is very simple and have high resolution even if the motor is driving in low speed. To verify the proposed method, BLAC motor is used, and it is proved that the motor is tracking well the reference step signal in the low speed as well as in the high one.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.511-515
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• 2003

This paper presents a novel prototype of the utility-interfaced sinusoidal pulse width modulated (SPWM) inverter using the high-frequency flyback transformer fur the small-scale solar photo-voltaic power conditioner (1kW - 4kW). The proposed SPWM power conditioner circuit with a high-frequency link has a function of electrical isolation, which is vital fur solar photovoltaic power conditioner systems with the viewpoint of safety and convenience. The discontinuous conduction mode (DCM) operation of the flyback transformer is also maintained to simplify the topology of the inverter circuit and control scheme. First, the operating principle of the proposed circuit is described far the understanding of the circuit parameters establishment. Then, the digitally constructed SPWM control scheme is presented. The proposed circuit is verified by the computer simulation and the prototype experiment.