• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.342-345
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• 1999

This paper describes a current regulated PWM boost type rectifier based on modified trapezoidal PWM. Each switch of a converter has no switching for one third period of a fundamental line current. Therefore, the switching loss of the proposed scheme is less than that of the hysteresis current controller. Operating principle is described and controller. Operating principle is described and simulations and experiments are carried out.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.5-9
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• 1998

In the high speed rail system, the distortion of the voltage and the current waveform of the input power line increases the power loss and make a several electro-magnetic problems such as EMI or the interference of the communication line. In this paper, the control scheme of the PWM converter to make a good power factor and to regulated the output voltage as well as to reduce the harmonic component of the input current is proposed. Also a control schem of the PWM converter in the parallel operation to reduce the harmonics of the input current is proposed

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.151-156
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• 2002

The output voltage of Synchronous Generator is regulated constantly by field current control in excitation system. A synchronous generator is equipped with an automatic voltage regulator(AVR), which is responsible for keeping the constant output voltage under normal operating conditions about various levels. High frequency PWM converter (Current Mode Control Buck converter) type excitation system for synchronous generator is able to sustain output voltage level properly when the fault condition happened. This paper deals with the design and evaluation of the excitation system controller for a synchronous generator to improve the steady state and transient stability. The simulation and experimental results show that the proposed excitation system is improve the respons time by the AVR(automatic voltage regulator) of 50kW synchronous generator that is applied the current mode control excitation system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.32-39
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• 2003

The output voltage of synchronous generator is regulated constantly by field current control in excitation system High frequency PWM converter (current control mode buck converter) type excitation systam fer synchronous generator is able to control exciter current when the load change happened. This paper deals with the design and evaluation of the excitation system for a synchronous generator to improve the steady state and transient stability. The simulation and experimental results show that the proposed excitation system is able to improve the response time by the DVR(digital voltage regulator) of 50[kW] synchronous generator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.9
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• pp.753-763
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• 1990

This paper proposes a new current control strategy for current regulated VSI-PWM lnverter. The conventional hysteresis control method has good dynamic response, but the switching frequency in lower region are high because it does not optimise switching patterns. Proposed current control strategy can optimize switching patterns. As regulater, three level comparator are used, the output of comparator select appropriate inverter output voltage vectors via switching table stored in EPROM. The simulation and experimental results in comparison to conventional hysteresis strategy are presented and discussed.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.373-377
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• 1996

Recently, active power factor control for AC/DC converter has been required to replace for a conventional diode rectifier. A voltage type AC/DC converter is widely used to obtain higher regulated DC voltage than input voltage with a unity power factor and a sinusoidal line current. This paper describes several active power factor control method for AC/DC converter. The analysis of several active power factor control is given. The simulations for hysteresis control, peak current control. constant frequency control and average current mode control are represented and compared.

• Proceedings of the KIEE Conference
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• 2006.10b
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• pp.154-158
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• 2006

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. Random Pulse Width Modulation (RPWM) is peformed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300v/1kW with $5%{\sim}30%$ white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• Journal of Power Electronics
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• v.12 no.2
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• pp.249-257
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• 2012

An interleaved PWM converter is proposed to implement the features of zero voltage switching (ZVS), load current sharing and ripple current reduction. The proposed converter includes two ZVS converters with a common clamp capacitor. With the shared capacitor, the charge balance of the two interleaved parts is automatically regulated under input voltage and load variations. The active-clamping circuit is used to realize the ZVS turn-on so that the switching losses on the power switches are reduced. The ZVS turn-on of all of the switching devices is achieved during the transition interval. The interleaved pulse-width modulation (PWM) operation will reduce the ripple current and the size of the input and output capacitors. The current double rectifier (CDR) is adopted in the secondary side to reduce output ripple current so that the sizes of the output chokes and capacitor are reduced. The circuit configuration, operation principles and design considerations are presented. Finally experimental results based on a 408W (24V/17A) prototype are provided to verify the effectiveness of the proposed converter.

• Journal of Power Electronics
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• v.10 no.5
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• pp.548-554
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• 2010

In this paper, a 1.5 kW Interior Permanent Magnet Synchronous Generator (IPMSG) with a power conditioner for the grid integration of a variable-speed wind turbine is developed. The power-conditioning system consists of a series-type 12-pulse diode rectifier powered by a phase shifting transformer and then cascaded to a PWM voltage source inverter. The PWM inverter is utilized to supply sinusoidal currents to the utility line by controlling the active and reactive current components in the q-d rotating reference frame. While the q-axis active current of the PWM inverter is regulated to follow an optimized active current reference so as to track the maximum power of the wind turbine. The d-axis reactive current can be adjusted to control the reactive power and voltage. In order to track the maximum power of the wind turbine, the optimal active current reference is determined by using a simple MPPT algorithm which requires only three sensors. Moreover, the phase angle of the utility voltage is detected using a simple electronic circuit consisting of both a zero-crossing voltage detecting circuit and a counter circuit employed with a crystal oscillator. At the generator terminals, a passive filter is designed not only to decrease the harmonic voltages and currents observed at the terminals of the IPMSG but also to improve the generator efficiency. The laboratory results indicate that the losses in the IPMSG can be effectively reduced by setting a passive filter at the generator terminals.

• 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.