• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.3
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• pp.241-247
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• 2007

This paper presents a new Leading edge modulation Buck converter operating in discontinuous conduction mode (DCM) for the pulse voltage input. In the slave output of the LLC half-bridge multi-resonant converter, to regulate the direct chopper's output voltage, its PWM switch is controlled by the leading edge modulation. The principles of this proposed LEM control method and the fast dynamics in inductor current based on the converter impulse response are studied. The theoretical results are verified through an experimental prototype of the 100W 60inch PDP Address power module.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.120-126
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• 2021

DC-link capacitors are one of the main components in two-level three-phase voltage source inverters (VSIs); they provide the pulsating input current and stabilize the vacillating DC-link voltage. Ideally, the larger the capacitance of DC-link capacitors, the better the DC-link voltage stabilizes. However, high capacitance increases the cost and decreases the power density of VSI systems. Therefore, the capacitance should be chosen carefully on the basis of the DC-link voltage ripple requirement. However, the DC-link voltage ripple is dependent on the pulse-width modulation (PWM) strategy. This study especially presents a DC-link voltage ripple analysis when the minimum loss discontinuous PWM strategy is applied. Furthermore, an equation for the selection of the minimum capacitance of DC-link capacitors is proposed. Experimental results with R-L loads are also provided to verify the effectiveness of the presented analysis.

• 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.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.327-332
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• 1999

In this paper, six harmonic injection PWM method for reducing total harmonic distortion in single switch three phase discontinuous conduction mode boost converter is presented. In the proposed method, periodic six harmonic voltage is injected in the control circuit to vary the duty ratio of the converter switch within a line cycle so that the fifth order harmonic of the input current is reduced. Experimental results are verified by converter operating at 400V/6kW with three phase 140V~220V input.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1107-1115
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• 2013

A new PWM technique for a two-phase BLDC motor fed by a two-phase eight-switch inverter is proposed in this paper. It is well known that a two-phase eight-switch inverter can significantly improve power output compared with a two-phase six-switch inverter in a two-phase motor drive. To drive the two-phase BLDC motor simply and effectively, two normal PWM strategies are investigated to manage speed regulation. However, under the conditions of low speed and light load, especially during the braking process, the current in a short time of one period is near zero, which is a discontinuous waveform every half period. To solve it, a novel PWM technique is investigated to improve the operational performance of normal technique. Using the new PWM scheme, the current continues every half period and the braking performance is improved. The effectiveness of the proposed PWM method is verified through the experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.3
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• pp.25-33
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• 1999

In this paper, the method of reducing hanmnics and correcting of power factor in single PWM converter associated with diode rectifier and boost converter is studied. In the general diode rectifier there are sorre problems that discontinuous current of reducing power factor and including distortion of hanmnics at the input current affects other sources. To solve the problems of performance degradation due to pulse wavefonn in the input current, the ac-dc converter in which the hanmnic distortion in the input current is reduced using a third-hanmnic-injected PWM is proposed. A lower power loss of switching and easy configuration of circuit are obtained by adopting discontinuous current mode. Simulation and experimental results of ac-dc converter with 5[kHz] switching frequency are presented and correction of power factor and reduction of total hanmnic distortion was established.lished.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.388-389
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• 2018

최근 차량용 인버터의 소형화 문제가 대두되고 있는 가운데, 3상 인버터의 구성품인 DC 링크 커패시터와 방열 시스템은 인버터에서 큰 부피를 차지하고 있다. DC 링크 커패시터의 부피는 커패시터에 흐르는 전류에 의해 결정되므로, 커패시터의 RMS 전류를 저감하는 것이 중요하다. 또한, 인버터의 스위칭 손실을 저감하면 방열 시스템의 크기를 줄일 수 있다. 본 논문에서는 추가적인 하드웨어 없이 PWM 방식 변경만으로 DC 링크 커패시터 RMS 전류와 스위칭 손실을 저감할 수 있는 Extended Double Carrier PWM을 소개한다. 또한, PSIM 시뮬레이션으로 이를 영구자석 동기 전동기의 구동에 적용하고, 기존에 널리 쓰이는 방식인 Space Vector PWM 및 Discontinuous PWM과 비교하여 그 특성을 살펴본다.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.4
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• pp.325-331
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• 1999

In a utility interactive photovoltaic generation system. a PWM inverter is used for the connection between the p photovoltaic arrays and the utility. The dc current becomes pulsated when the conventional inverter system operates i in the continuous current mode and de current pulsation causes the distortion of the accurrent waveform. This paper p presents the reduced pulsation of de input current by operating the inverter with buck-boost chopper in the d discontinuous conduction mode. The dc current which contains harmonic component is analyzed by means of s separating into two terms of a ripple component and a direct component. The constant dc current without p pulsation is supplied from photovoltaic array to the inverter. The proposed inverter system provides a sinusoidal ac c current for domestic loads and the utility line with unity power factor.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.169-176
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• 2005

In this paper, a DC and small-signal AC modeling for the active-clamp, ful1-bridge boost converter is described. Based on the operation principle, the ac part of the converter can be replaced by a dc counterpart. Then, a conceptual equivalent circuit is derived by rearranging the switches. The equivalent circuit for this converter consists of CCM(Continuous conduction mode) boost and DCM(Discontinuous conduction mode) buck converter. The analyses for the equivalent CCM boost and DCM buck converter are done using the model of PWM switch. The theoretical modeling results are confirmed through experiment or SIMPLIS simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.547-550
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• 2017

This paper presents a loss analysis and compares three pulse width modulation (PWM) methods applied in a three-phase grid-connected bidirectional inverter for an energy storage system. The losses in switching devices and output low pass filters are theoretically analyzed by using PWM control techniques. Grid-connected bidirectional inverters are designed by using PWM techniques, and the designed inverters are simulated to verify the analysis results.