Unified harmonics based method to reduce reactive power of the dual active bridge converter

In order to improve the efficiency of the dual active bridge (DAB) converter for a wide operating range, a novel unified-harmonics analysis based control strategy under 3-level modulated phase-shift framework is proposed. The mathematic model of the transmission power of the DAB converter is derived and the zero-voltage-switch soft-switching region is presented. Compared with piecewise time domain model, the expressions are simplified and easy online implementation. Then, a reactive-power-minimization method and its control implementation are presented. Both of the simulation and experiment results verify the feasibility of the proposed control method.