Characterization Of Phase Shift Control Of LLC Resonant Converter Based On SiC MOSFET

Resonant conversion technology is an effective way to enhance the power density of switching power supply, in recent years, the LLC resonant converter has been widely used. In order to expand power capacity or reduce current ripple, LLC resonant converter can be used in interleaved parallel. To achieve output current sharing between converters, phase shift control is introduced typically, this paper focuses on the characteristic of LLC resonant converter with phase shift control and the current sharing control with phase shift of two phase LLC converters.Firstly, this paper deduces the relationship between the dc gain of LLC resonant converter and phase shift angle based on fundamental model, and compared with PSIM simulative and experimental result. This paper finds that the result based on fundamental model is quite different from experimental result, and the characteristic of between dc gain and phase shift angle is non-monotonic. This paper analyzes the main influence factor based on PSIM simulation, compares it with experimental result, then analyzes the reasons of difference of gain curve between light and heavy load. In order to analyze the effect of circuit parameter error on characteristic between dc gain and phase shift angle, this paper deduces the relationship between the phase shift angle and circuit parameter error of converter.This paper introduces the design procedure of LLC converter, then a 15kW two-phase interleaved LLC resonant converter is built. The principle of current sharing control with phase shift of interleaved parallel LLC converter is introduced, analysis the influence of parameter error on the interleaved LLC resonant converter through experiment result.