Duty-cycle plus phase-shift control for a dual active half bridge based bipolar DC microgrid

This paper studies the dual active half bridge when used to achieve flexible (symmetric or asymmetric) bipolar DC output. The circuit is operated with combined duty-cycle and phase-shift control to provide voltage splitting functionality without the requirement for an additional voltage balancing circuit. This topology uses reduced number of components needed to achieve the flexible bidirectional DC bipolar output with galvanic isolation, and has potential applications in low-cost bipolar DC microgrids. Depending on the relationship of the duty cycle and phase shift ratio, six different working cases are analyzed and corresponding power transfer is derived. Using a laboratory prototype, the performance of this dual active half bridge converter was further validated by experimental tests.