• Journal of Power Electronics
• /
• v.14 no.2
• /
• pp.203-216
• /
• 2014

In the conventional dc-dc converter, a pair of additional diode and the adjacent passive component capacitor/inductor can be added to the circuit with an X-shape connection, which generates a family of new topologies. The novel circuits, also called diode-assisted dc-dc converter, enhance the voltage boost/buck capability and have a great potential for high step-up/step-down power conversions. This paper mainly investigates and compares conventional dc-dc converter and diode-assisted dc-dc converter in wide range power conversion from the aspects of silicon devices, passive components requirements, electro-magnetic interference (EMI) and efficiency. Then, a comprehensive comparison example of a high step-up power conversion system was carried out. The two kinds of boost dc-dc converters operate under the same operation conditions. Mathematical analysis and experiment results verify that diode-assisted dc-dc converters are very promising for simultaneous high efficiency and high step-up/step-down power conversion in distributed power supply systems.

• Journal of Power Electronics
• /
• v.11 no.4
• /
• pp.499-506
• /
• 2011

This paper presents an interleaved active-clamping zero-voltage-switching (ZVS) forward-flyback converter without an output choke. The presented topology has two active-clamping circuits with two separated transformers. Because of the interleaved operation of the converter, the output current ripple will be reduced. The proposed converter can approximately share the total load current between the two secondaries. Therefore, the transformer copper loss and the rectifier diodes conduction loss can be decreased. The output capacitor is made of two series capacitors which reduces the peak reverse voltage of the rectifier diodes. The circuit has no output inductor and few semiconductor elements, such that the adopted circuit has a simpler structure, a lower cost and is suitable for high power density applications. A detailed analysis and the design of this new converter are described. A prototype converter has been implemented and experimental results have been recorded with an ac input voltage of 85-135Vrms, an output voltage of 12V and an output current of 16A.

• Journal of Power Electronics
• /
• v.6 no.2
• /
• pp.131-138
• /
• 2006

An active clamp ZVS PWM forward converter using a secondary synchronous switch control is proposed in this paper. The proposed converter is suitable for low-voltage and high-current applications. The structure of the proposed converter is the same as a conventional active clamp forward converter. However, since it controls the secondary synchronous switch to build up the primary current during a very short period of time, the ZVS operation is easily achieved without any additional conduction losses of magnetizing current in the transformer and clamp circuit. Furthermore, there are no additional circuits required for the ZVS operation of power switches. Therefore, the proposed converter can achieve high efficiency with low EMI noise, resulting from soft switching without any additional conduction losses, and shows high power dens~ty, a result of high efficiency, and requires no additional components. The operational principle and design example are presented. Experimental results demonstrate that the proposed converter can achieve an excellent ZVS performance throughout all load conditions and demonstrates significant improvement in efficiency for the 100W (5V, 20A) prototype converter.

• Journal of Power Electronics
• /
• v.17 no.6
• /
• pp.1454-1468
• /
• 2017

In this study, a new dual-active soft-switching converter is proposed to improve conversion efficiency and extend the load range for an MTEM electromagnetic transmitter in geological exploration. Unlike a conventional DC/DC converter, the proposed converter can operate in passive soft-switching, single-active soft-switching, or dual-active soft-switching modes depending on the change in load power. The main switches and lagging auxiliary switches of the converter can attain soft-switching over the entire load range. The conduction and switching losses are greatly reduced compared with those of ordinary converters under the action of the cut-off diodes and auxiliary windings coupled to the main transformer in the auxiliary circuits. The conversion efficiency of the proposed converter is significantly improved, especially under light-load conditions. First, the working principle of the proposed converter is analyzed in detail. Second, the relationship between the different operating modes and the load power is given and the design principle of the auxiliary circuit is presented. Finally, the Saber simulation and experimental results verify the feasibility and validity of the converter and a 50 kW prototype is implemented.

• Journal of Power Electronics
• /
• v.19 no.6
• /
• pp.1413-1428
• /
• 2019

In this paper, a novel zero-voltage and zero-current switching (ZVZCS) interleaved two switch forward converter is proposed. By using a coupled-inductor-type smoothing filter, a snubber capacitor, the parallel capacitance of the leading switches and the transformer parasitic inductance, the proposed converter can realize soft-switching for the main power switches. This converter can effectively reduce the primary circulating current loss by using the coupled inductor and the snubber capacitor. Furthermore, this converter can reduce the reverse recovery loss, parasitic ringing and transient voltage stress in the secondary rectifier diodes caused by the leakage inductors of the transformer and the coupled inductance. The operation principle and steady state characteristics of the converter are analyzed according to the equivalent circuits in different operation modes. The practical effectiveness of the proposed converter was is illustrated by simulation and experimental results via a 500W, 100 kHz prototype using the power MOSFET.

• Journal of Power Electronics
• /
• v.8 no.3
• /
• pp.239-247
• /
• 2008

This paper presents the design of 1 kW prototype high frequency link boost half bridge inverter-fed DC-DC power converters with bridge voltage-doublers suitable for small scale PEM fuel cell systems and associated control schemes. The operation principle of this converter is described using fuel cell modeling and some operating waveforms. The switching mode equivalent circuits are based on simulation results and a detailed circuit operation analysis at soft-switching conditions.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.543-547
• /
• 2000

Power factor and harmonics are increasingly important for high speed train auxiliary block. This paper presents experimental results of the power factor and harmonic performance of two parallel PWM circuits under various supply and load conditions. For reducing harmonics the harmonic content is eliminated by the phase shift between two converters switching phase. Experimental results show the usefulness of the proposed method and applicability to PWM converter in auxiliary block of high speed train.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.40 no.3
• /
• pp.266-274
• /
• 1991

This paper proposed the resonant DC-DC converter with constant switching frequency. Its output is controlled by the auxiliary switch which is attached in conventional MRC circuits. The average output voltage is equal to the average voltage of the auxiliary switch. If the on time of the auxiliary switch is short, output voltage is decreased. Because of using the multi resonant method, the power loss from the parasitic elements can be decreased. Experimental performance of DF ZVS Forward MRC topology with switching frequency of 1MHz is presented.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.549-550
• /
• 2008

This paper proposed and designed the modified flash analog-to-digital converter(ADC). The speed of new architecture is similar to conventional flash ADC but the die area consumption is much less due to reduce numbers of comparators. The circuits which are implemented in this paper is simulated with LT SPICE and layout with Electric tools of computer.

• Journal of Electrical Engineering and information Science
• /
• v.3 no.3
• /
• pp.366-372
• /
• 1998

A high efficiency interleaved active clamp forward converter with self driven synchronous rectifiers for a modular power processor is presented. To simplify the gate drive circuits, N-P MOSFETs coupled active clamp method is used. An efficiency about 90% for the load range of 50-100% is achieved. The details of design for the power stage and current mode control circuit are provided, and also some experimental results are given.