• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.5
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• pp.238-245
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• 2003

In this paper, a single Phase voltage source voltage-controlled active power filter(APF) for power quality improvement was proposed. The proposed APF has the performance of harmonic suppression and unity power factor correction. The performance of harmonic suppression can be obtained by controlling the waveshape of the APF output voltage to be sine wave. And, unity power factor is controlled by the reactive power control loop of the APF output. Simulation and experimental results using diode rectifier showed that the voltage-controlled APF, unlike the current-controlled APF, can reduce the voltage harmonics as well as current harmonics. Also the results showed that the input dover factor and power quality were greatly improved.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.485-488
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• 1999

In this paper, a current control system for single phase PWM AC/DC converter without the source voltage sensors is proposed. The sinusoidal input current and unity effective power factor are realised based on the estimated source voltage in the controller. The estimation of source voltage is performed by the reduced-order Luenberger observer using actual currents. The estimated source voltage is used to accomplish unity power factor. The proposed method is proved by experiments.

• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.78-82
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• 1998

In this paper, the authors propose a current control system of single phase PWM AC/DC converter without the source voltage sensors. The sinusoidal input current and unity effective power factor are realised based on the estimated source voltage in the controller. The estimations of source voltage are performed based on the reduced-order Luenberger observer using actual currents. The estimated source voltage is used to accomplish unity power factor. The proposed method is proved by simulations

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1187-1189
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• 2000

This paper presents a high power-hybrid multilevel PWM rectifier with unity power factor. The features and advantages of the proposed PWM rectifier can be summarized as follows; 1) It realizes the high power high voltage AC/DC power conversion. 2) It uses no transformer which is bulky and heavy, 3) It has hybrid structure so that switching devices can be effectively utilized, 4) It produces high quality AC current even in high power high voltage applications, 5) The input power factor remains unity by simple modulation index control. The multilevel rectifier is analyzed by using the circuit DQ transformation whereby the characteristics and control equations are obtained.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.767-781
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• 2013

In this paper, we proposes the AC input voltage and current sensorless control scheme to control the input power factor and DC output voltage of the three-phase Z-source PWM rectifier. For DC-link voltage control which is sensitive to the system parameters of the PWM rectifier, fuzzy-PI controller is used. Because the AC input voltage and current are estimated using only the DC-link voltage and current, AC input voltage and current sensors are not required. In addition, the unity input power factor and DC output voltage can be controlled. The phase-angle of the detected AC input voltage and estimated voltage, the response characteristics of the DC output voltage according to the DC voltage references, the FFT results of the estimated voltage and current, efficiency, and the response characteristics of the conventional PI controller and fuzzy-PI controller are verified by PSIM simulation.

• Journal of Power Electronics
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• v.9 no.2
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• pp.173-179
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• 2009

This paper proposes a new three-phase diode rectifier system with a sinusoidal input current at unity power factor and a regulated and isolated output voltage at low level. The inherent natural wave-shaping capability of the reduced kVA polyphase transformer together with an active current wave-shaping technique results in a significant reduction of input and output filter requirements associated with switching ripple and EMI. The operation principles are described along with a design example and a comparative evaluation. Experimental results on a 1.5kW prototype are provided to validate the proposed concept.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.355-364
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• 2013

Respect to the input AC voltage and output DC voltage, conventional three-phase PWM rectifier is classified as the voltage type rectifier with boost capability and the current type rectifier voltage with buck capability. Conventional PWM rectifier can not at the same time the boost and buck capability and its bridge is weak in the shoot- through state. These problems can be solved by Z-source PWM rectifier which has all characteristic of voltage and current type PWM rectifier. By shoot-through duty ratio control, the Z-source PWM rectifier can buck and boost at the same time, also, there is no need to consider the dead time. This paper proposes the input AC voltage sensorless control method of a three-phase Z-source PWM rectifier in order to accomplish the unity input power factor and output DC voltage control. The proposed method is estimated the input AC voltage by using input AC current and output DC voltage, hence, the sensor for the input AC voltage detection is no needed. comparison of the estimated and detected input AC voltage, estimated phase angle of the input voltage, the output DC voltage response for reference value, unity power factor, FFT(Fast Fourier Transform) of the estimated voltage and efficiency are verified by PSIM simulation.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.180-182
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• 2001

Input Current Correction of Single-Phase Buck Rectifier is studied in the paper. To sinusoidal waveform the input current with a near-unity power factor over a wide variety of operating conditions, the output capacitor is operated with voltage reversibility for the supply by arranging the auxiliary diode and power switching device. Then the output voltage is superposed on the input voltage during on time duration of power switching devices in order to minimize the input current distortion caused by the small input voltage when changing the polarity. The tested setup, using two insulated-gate bipolar transistors(IGBT) and a microcomputer, is implemented and IGBT are switched with 20[kHz], which is out of the audible band. Moreover, a rigorous state-space analysis is introduced to predict the operation of the rectifier. The simulated results confirm that the input current can be sinusoidal waveform with a near-unity power factor and a satisfactory output voltage regulation can be achieved.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1048-1057
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• 2017

An indirect matrix converter (IMC) is a modern power generation system that enables a direct ac/ac conversion without the need for any bulky and limited lifetime electrolytic capacitor. This system also allows four-quadrant operation, generation of sinusoidal output voltage waveforms with variable frequency and amplitude, and control of input power factor. This study proposes a pulse-width modulation-based sliding-mode controller to achieve unity input-power factor operation of the IMC independently of the active power exchanged with the grid, as well as a fast dynamic response. The designed equivalent control law determines, at each sampling period, the appropriate q-axis component of the modulated input current to be injected into the grid through the LC input filter. An integral term of the error is included in the expression of the sliding surface to increase the accuracy of the control method. A double space vector modulation method is used to synthesize the direction of the space vector of the input currents as required by the sliding-mode controller and the space vectors of the target output voltages. Simulation and experimental results are provided to show the effectiveness and evaluate the performance of the proposed control method.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1940-1943
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• 1998

A new PWM rectifier which offers a unity power factor is proposed. The circuit has same inductance as the conventional boosting type PWM rectifier in powering mode, but the inductance is splitted to 2 part in freewheeling mode. So the period of freewheeling mode is shorter than that of conventional boosting type PWM rectifier, and discontinuous input current is obtained in wide duty range. Therefore the proposed PWM rectifier accomplishs a unity power factor in wide range of duty ratio and boosting factor. And the conventional boosting type PWM rectifier has poor power factor near the unity boosting ratio, the proposed PWM rectifier improves this problem. The mathmatical analysis are presented and experimental results are given.