Design and optimization of three-winding planar transformer for three-port high-frequency resonant converter

To improve the power density of three-port high-frequency resonant converter using wide bandgap devices, a three-winding planar transformer is proposed. By analysing the topology and working conditions of the converter, the design requirements for the three-winding transformer are clarified. Based on the equivalent circuit of the three-winding transformer, the magnetizing inductance of transformer is directly and accurately controlled by the air gap of the core. The factors affecting the accuracy of air gap reluctance and transformer loss are analysed and some improved schemes are proposed. According to the optimized design process of the transformer, the method of selecting the optimal core size is given.