• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.8
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• pp.389-395
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• 2006

In the single-phase switched reluctance motor (SRM) drive, the required DC source is generally supplied by the circuit consisting of bridge rectifier with diodes and many filter capacitances connected with AC source. Although the peak torque ripple of SRM is small because of large capacity of the capacitance, the charge and discharge time swhich the AC source acts on the capacitance are small and the peak current will pass on the side of source, so power factor and system efficiency decrease. Therefore a novel SRM drive system is presented in this paper, which includes drive circuit realizing reduction of torque ripple and improvement of power factor and switching topology. The proposed drive circuit consists of one switching part and diodes which can separate the output of AC/DC rectifier from the large capacitance and supply power to SRM alternately in order to realize reduction of torque ripple and improvement of power factor through the turn on and turn off of switching part. In addition, the validity of method is tested by simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.533-541
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• 2011

This paper studies modeling of Jeju 80kV HVDC system and its controller by using PSCAD/EMTDC program. Reduced ac network is applied to verify interaction between ac network and dc system. Design parameter is applied to the converter transformer, harmonic filter and dc transmisstion line to simulate dc system. HVDC controller is divided into a rectifier controller and a inverter controller according to the converter operating mode. The inverter controller is composed of current control, voltage control and extingtion angle control. The rectifier controller is composed of current control and voltage control. Both controller has VDCOL characteristics so that current order is dependant on voltage variation. Step response, ac network single phase fault, three phase fault is simulated to verify the dynamic performance of controller model in both transient state and steady state.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.648-653
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• 1998

The conventional three-phase rectifier with bulky LC output filter has been widely used in the industry because of its distinctive advantages over the active power factor correction rectifier such as simple circuit, high reliability, and low cost. Over than 0.9 power factor can be achieved, which is acceptable in most of industry applications. This rectifier, however, is not easy to use for high power density applications since the LC filter is bulky and heavy. To solve this problem, a new simple rectifier is presented in this paper. By eliminating the bulky LC filter from the conventional diode rectifier without losing most of the advantages of the conventional rectifier, very high power density power conversion with high power factor can be achieved. Operation principle and design considerations are illustrated and verified by Pspice simulation and experimental results from a prototype of 3.3 kW rectifier followed by 100KHz zero voltage switching full bridge PWM converter

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.3
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• pp.76-83
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• 1983

This paper describes the method of operating the phase controlled rectifier by controlling the firing angle in III, IV quadrant to absorb the lrading reactive power and of improving the waveform of ac current by driving dual converter. The system is intended to compensate the reactive power for any lagging load. Also, by the above method this paper enables us to improve the power factor and waveform referred to the source current and the dc output voltage in the converter.

• Journal of Power Electronics
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• v.15 no.1
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• pp.202-215
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• 2015

This paper investigates the stability and performance of model predictive controlled active-front-end (AFE) rectifiers for energy storage systems, which has been increasingly applied in power distribution sectors and in renewable energy sources to ensure an uninterruptable power supply. The model predictive control (MPC) algorithm utilizes the discrete behavior of power converters to determine appropriate switching states by defining a cost function. The stability of the MPC algorithm is analyzed with the discrete z-domain response and the nonlinear simulation model. The results confirms that the control method of the active-front-end (AFE) rectifier is stable, and that is operates with an infinite gain margin and a very fast dynamic response. Moreover, the performance of the MPC controlled AFE rectifier is verified with a 3.0 kW experimental system. This shows that the MPC controlled AFE rectifier operates with a unity power factor, an acceptable THD (4.0 %) level for the input current and a very low DC voltage ripple. Finally, an efficiency comparison is performed between the MPC and the VOC-based PWM controllers for AFE rectifiers. This comparison demonstrates the effectiveness of the MPC controller.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.902-904
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• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a practical point of view that 92.1[%]of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.3114-3116
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• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a practical point of view that 92.1[%] of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2462-2464
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• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a Practical point of view that 92.1[%]of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1820-1822
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• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a practical point of view that 92.1[%]of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.43-48
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• 2000

In this paper, CPLD(Complex Programmable Logic Device) controller designed with VHDL is developed. With the controller, the harmonics from 3 phase diode rectifier are suppressed and power factor is also improved. The input current of diode rectifier is drawn from the ac mains only during the period in the ac cycle when the instantaneous voltage is greater than the voltage across the dc-link capacitor. The three bidirectional switches rated at very small power are installed in a conventional three phase diode rectifier. Using CPLD controller, an idle current charges to capacitors continuously. Results of simulation and experimental demonstrate a reduction of harmonics, a improvement of power factor and THD.