Research on a novel variable-frequency and phase-shift control method based on a high-voltage and high-power full-bridge converter.

This paper presents a new variable-frequency phase-shift control method to improve the conversion efficiency for a high-power wide-range converter based on a phase-shifted full-bridge (PSFB) converter. The proposed converter can adjust the switching-frequency according to the load power to make the input impedance be inductive. The main switches of the converter can achieve zero voltage switching (ZVS) over a wide load range (500 W–50 kW) without any auxiliary circuit. The maximum switching-frequency of high-power insulated gate bipolar transistor (IGBT) is determined by analyzing the influence of collector current on IGBT switching time. The necessary condition for the proposed converter to realize ZVS is given according to the steady-state model of the full-bridge converter. This paper analyzed the influence of voltage, current and temperature on the switching time of high-power IGBT in detail, and obtained the relationship between the load current and the dead time of high-power IGBT. The optimal switching-frequency under different loads was determined by establishing a switching-frequency loss model of the proposed converter. A 50 kW prototype of the proposed converter was developed and the experimental and simulation results verify the effectiveness and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]