Bidirectional Asymmetrical Dual Active Bridge Resonant Converter for Renewable to DC Microgrid Interface

This paper presents an isolated high-frequency bidirectional asymmetrical dual active bridge resonant converter (ADABRC) for renewable to DC microgrid interface. The converter utilizes one active bridge at the input side and one half-active bridge at the output side for bidirectional power transfer. At the output side, one leg of the bridge consists of film capacitors so the need for the electrolytic capacitor at the output node could be avoided. A phase-shift-based modulation technique has been adopted for the control of power transfer in forward and backward modes. For the analysis of the resonant converter, a Fourier-based modified fundamental harmonics approximation (FHA) has been used. Using the FHA approximation method, the condition for soft-switching has been analyzed. To validate the analysis, a design example for the bidirectional converter has been given and verified in forward and backward modes of operation for a 500 W converter.