Individual Current Stress Optimization for Multiple Dual Active Bridges with Common Input Stage

In this paper, an optimised modulation strategy for a multi-port converter consisting of two dual active bridges with a common input stage is proposed to reduce the link current stresses in either bridge. The switching losses are reduced through zero-voltage switching in a wide range of operating conditions in the proposed optimization method. Controlled by the Triple phase shift (TPS) scheme, the typical operating modes are identified with respect to the phase-shift limits for a Dual Active Bridge. The same method is then extended to a second DAB with one common phase shift with respect to the input bridge and two additional phase shifts. The proposed optimization required simple computation compared to that with penta phase shift optimization for three-port converter, however it has certain operation power ranges where optimization can not be achieved. A trade-off study between the selection of transformer turns ratio and the non-optimization zones are highlighted.