Discussion of Junction Capacitance of SiC Schottky Diode on Soft-Switching Condition of LLC Resonant Converter with Cockcroft-Walton Voltage Multiplier for High-Voltage Generator

Conference: PCIM Asia 2020 - International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management
11/16/2020 - 11/18/2020 at Shanghai, China

Proceedings: PCIM Asia 2020

Pages: 9Language: englishTyp: PDF

Wang, Runze; Dong, Minghai; Li, Hui (School of Aeronautics and Astronautics, University of Electronic Science and Technology of China, Chengdu, China)
Yin, Shan; Xin, Xiong (Microsystem and Terahertz Research Center, China Academy of Engineering Physics, Chengdu, China & Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, China)

The combination of LLC resonant converter and Cockcroft-Walton voltage multiplier (CWVM) as a high-voltage generator (HVG) can realize soft switching and low voltage stress on transformer as well as rectifier. Experimental results have indicated that the junction capacitances of diodes in the CWVM show a significant impact on the soft switching condition. In this paper, a detailed analysis for the LLC converter with the consideration of parasitic capacitance Cp (including diode junction capacitance and transformer winding capacitance) is conducted, which is called as LLC-C converter in this work. The theoretical analysis shows that a double pole in a relatively high frequency is introduced, especially at the light load. At the heavy load, the LLC-C converter operates similar to the LLC, and the effect of Cp can be neglected. It is also verified by the experiment with a 24-V/2-kV HVG prototype.