Analysis and Implementation of Input Parallel Output Parallel DAHB DC-DC Converters with Sensorless Current Sharing Control Strategy

The isolated bidirectional converter dual active half-bridge (DAHB) DC-DC converter consists of two half bridge converters and a high frequency transformer. The DAHB converter has significant features such as high dynamic response, high voltage gain, and zero-voltage soft switching. The series parallel combination of low voltage and small capacity DC-DC converter is a typical scheme to improve the voltage and power level of the converter. However, the complexity and cost increase due to too many current sensors. In view of the current sharing problem in the power module cascaded structure, this paper employs a single phase shift-based sensorless current sharing method for input-parallel output-parallel (IPOP) connected DAHB converter. The converter is analyzed and a 500W IPOP experimental prototype with 50V input voltage and 200V output voltage under 20kHz switching frequency is implemented to verify the theoretical results. Finally, a comparative analysis is given to demonstrate the superiority of the proposed current sharing strategy.