Research on current‐type high frequency resonant power converter based on magnetic energy recovery switch

Abstract

LCL resonant converters have been widely used to get a constant current output. This paper proposes an LCL resonant converter based on the magnetic energy recovery switch (MERS), which adjusts the output current of the converter by controlling the paralleled equivalent capacitance, as responding to the parameter errors or input voltage disturbance. Firstly, based on the equivalent model of the LCL resonant converter, the effect of variable capacitive impedance on the output current characteristics of the converter is analysed. Then the topological structure of MERS is introduced and its working principle as a controllable capacitive impedance controller is further explained. On this basis, the operating characteristics and soft switching characteristics of the proposed topology in each complete working cycle are analysed in detail. By controlling the phase shift angle between the output voltage of bridge and the fundamental component of MERS voltage, the equivalent capacitance of the MERS is changed, and the resonant frequency of the converter is accordingly adjusted to accurately compensate the output current against the input voltage disturbance. Finally, the effectiveness and feasibility of the MERS applied to the LCL resonant converter are verified by simulation and experiments. Besides, its operating characteristics are analysed and evaluated.