OPTIMAL MODULATION AND CONTROL OF VOLTAGE FED DUAL ACTIVE BRIDGE BIDIRECTIONAL DC-DC CONVERTER

Abstract

The demand for energy storage systems are increasing in many industries (automation, renewable energy etc.), requiring power electronic system interface. The Voltage Fed - Dual Active Bridge (VF-DAB) converter is the most suitable topology for such applications. However, Single Phase Shift (SPS) controlled VF-DAB converters suffer from transient DC bias effect and poor steady-state performance at wide load and voltage variations. A modified SPS control scheme is proposed in order to mitigate the effects of transient DC bias. Similarly, a variable transformer turns ratio based method for a single module and phase shedding/adding method for parallel operated SPS controlled VF-DAB are proposed to improve the steady-state performance. Although both solutions improve the steady-state performance, they still do not provide complete soft-switching. A solution based on use of passive auxiliary inductors is proposed to achieve complete soft-switching in the entire operating range of Triple Phase Shift controlled VF-DAB converters