A Novel Direct Duty-to-Current Control for DC Bias Mitigation in Dual Active Bridge Converters for Enhanced EV Applications

This paper presents a novel direct duty-to-current control strategy to mitigate the dc bias and eliminate the need for a dc blocking capacitor in Dual Active Bridge (DAB) converters. The proposed control mechanism directly controls the duty cycle of each leg in the primary H-bridge to regulate the average (over one switching period) volt-seconds applied to the transformer primary winding to be zero without a dc blocking capacitor, under both steady-state and transient operations. This strategy is particularly relevant for electric vehicle (EV) applications, where variations in power demand and charging protocols can introduce dc bias, and the proposed control strategy work seamlessly with the output voltage control loop, during both steady-state operation and transients. The analysis, presented in detail, includes simulation results validating the effectiveness of the proposed control strategy under various steady-state and transient conditions, demonstrating its robustness and applica-bility in EV systems.