• Journal of Electrical Engineering and Technology
• /
• v.9 no.5
• /
• pp.1592-1601
• /
• 2014

In this study, a novel single phase soft switched power factor correction (PFC) converter is developed with active snubber cell. The active snubber cell provides boost switch both to turn on with zero voltage transition (ZVT) and to turn off with zero current transition (ZCT). As the switching losses in the proposed converter are too low, L and C size can be reduced by increasing the operating frequency. Also, all the semiconductor devices operate with soft switching. There is no additional voltage stress in the boost switch and diode. The proposed converter has a simple structure, low cost and ease of control as well. It has a simple control loop to achieve near unity power factor with the aid of the UC3854. In this study, detailed steady state analysis of the proposed converter is presented and this theoretical analysis is verified by a prototype of 100 kHz and 500 W converter. The measured power factor and efficiency are 0.99 and 97.9% at full load.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.6
• /
• pp.464-470
• /
• 2022

A new type of soft-switching forward converter is proposed in this study. By adding only a few components, the inductor, diode, switch, and capacitor exhibit higher efficiency than the conventional forward converter. Therefore, the switching losses of the proposed forward converter are considerably reduced compared with those of the conventional forward converter. In addition, the reset winding is not used because of the capacitor employed in the auxiliary circuit. The auxiliary capacitor is adopted for zero-current-transition operation and for dissipating magnetization energy. The performance of the proposed forward converter is validated using experimental results from a 60 W, single-output, forward converter prototype, and design guidelines are presented.

• Journal of Power Electronics
• /
• v.15 no.3
• /
• pp.602-609
• /
• 2015

In this paper, a zero current transition (ZCT) double-ended flyback converter is proposed. All of the switching elements act under soft switching conditions and the voltage stress of the main switches is limited to the input voltage due to the innate behavior of the double-ended flyback converter. Providing soft switching conditions and clamping the voltage stress improves the efficiency and electromagnetic compatibility (EMC). The Proposed converter is analyzed in detail and its operating modes are discussed in detail. Experimental results are presented to verify the theoretical predictions. Moreover, the conducted electromagnetic emissions of the proposed ZCT double-ended flyback converter are measured to show another merit of the proposed converter in addition to providing soft switching conditions. The measured electromagnetic interference (EMI) of the proposed converter demonstrates that its EMI is lower than the conventional double-ended flyback converter. Furthermore, two simple and cost effective EMI reduction methods are applied to satisfy the EMC standard.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.479-480
• /
• 2010

In this paper, the bi-directional soft switching DC-DC converter using ZCT(Zero Current Transition) method is proposed for using battery application system. This topology is composed of soft switching bi-directional buck/boost converter having the ZCT auxiliary circuit with two switches, two resonant capacitors, one resonant inductor. Therefore, the proposed topology can reduce switching loss. To verify the validity of the proposed topology, theoretical analysis and simulation results are presented.

• Journal of Power Electronics
• /
• v.17 no.6
• /
• pp.1445-1453
• /
• 2017

In this study, a new zero-voltage transition (ZVT) buck converter with coupled inductor using a synchronous rectifier and a lossless clamp circuit is proposed. The regular buck converter with tapped inductor has extended duty cycle for high step-down applications. However, the leakage inductance of the coupled inductor produced considerable voltage spikes across the switch. A lossless clamp circuit is used in the proposed converter to overcome this problem. The freewheeling diode was replaced with a synchronous rectifier to reduce conduction losses in the proposed converter. ZVT conditions at turn-on and turn-off instants were provided for the main switch. The synchronous rectifier switch turned on under zero-voltage switching, and the auxiliary switch turn-on and turn-off were under zero-current condition. Experimental results of a 100 W-100 kHz prototype are provided to justify the validity of the theoretical analysis. Moreover, the conducted electromagnetic interference of the proposed converter is measured and compared with its hard-switching counterpart.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.1215-1217
• /
• 2000

For the application of soft-switching technique to single Phase-full bridge inverter. in this paper ZCT(Zero Current Transition) and ZVT(Zero Voltage Transition) techniques proposed previously are compared and discussed the merit and demerit of both. Both have a excellency that can reduce the number of auxiliary switch and resonant circuit compared to other techniques and achive soft-switching in auxiliary switch itself. Therefore, it has enabled us to have benifits of realizing high efficiency and reliability, low EMI for high switching frequency and reducing the cost as well as size of device.