Design Methodology to Improve Efficiency of Semi-dual Active Bridge Converter

Semi-dual active bridge converters (SDABCs) find their use in cost-competitive applications requiring unidirectional power flow. However, the efficiency of SDABC with single phase shift (SPS) control is poor at light-load conditions. In this paper, a design approach is suggested to improve the light-load efficiency of SDABC. Here, transformer turns ratio and leakage inductance are selected to achieve a relatively flat efficiency profile over a wide load range. The proposed design approach utilizes the capability of SDABC to operate in a discontinuous conduction state to improve the light-load efficiency. The efficiency improvement of SDABC with the proposed methodology is validated using analytical calculations and experimentation studies. For 1.5 kW laboratory prototype, SDABC with conventional design has 48 % efficiency at 44 % load. At the same operating conditions, SDABC with the proposed design has 97 % efficiency.