A Digital Self-Sustained Phase Shift Modulation Control Strategy for Full-Bridge LLC Resonant Converters

Abstract

A digital self-sustained phase shift modulation (DSSPSM) strategy that allows for good soft switching and dynamic response performance in the presence of step variations is presented in this paper. The working principle, soft switching characteristics, and voltage gain formulae of a LLC converter with DSSPSM have been provided separately. Furthermore, the method for realizing DSSPSM is proposed. Specifically, some key components of the proposed DSSPSM are carefully investigated, including a parameter variation analysis, the start-up process, and the zero-crossing capture of the resonant current. The simulation and experiment results verify the feasibility of the proposed control method. It is observed that the zero voltage switching of the switches and the zero current switching of the rectifier diodes can be easily realized in presence of step load variations.

An 8kW LLC resonant converter in plasma power supply based on SiC power devices for efficiency improvement

“…Nevertheless, the rapid development and gradual improvement of SiC MOSFET have pushed plasma and welding supply to enter a new field. A LLC zero-voltageswitching (ZVS) resonant converter topology is adopted to further improve the efficiency and power density, which has the advantages of excellent electromagnetic compatibility, superior output power characteristics, and high efficiency and reliability (Zheng et al, 2016). However, it is difficult to achieve these goals in a specific circuit, and additional knowledge and advanced technology are needed to overcome difficulties.…”