Design and control of bidirectional resonant converter for Vehicle-to-Grid (V2G) applications

In this paper, a detailed design procedure is presented for a bidirectional resonant converter for battery charging application. This converter is similar to the LLC resonant converter with an extra inductor and capacitor in the secondary side. Soft-switching can be ensured in all switches without additional circuitry, and because of that, very high frequency operation is possible, hence; the size of the magnetics and the capacitors can be reduced. In this manuscript, first, an equivalent model for the bidirectional converter is derived for the steady-state analysis. Then, the design methodology is presented. Design of a converter includes finding the transformer turns ratio, design of magnetizing inductance based on ZVS condition, design of resonant inductances and resonant capacitances. To validate the design procedure, a 3.3 kW converter was designed following the guidelines in the proposed methodology as a design example. A prototype was built and tested in the lab. Experimental results verified the design procedure presented.