An Asymmetrical Duty Cycle Control of Three Phase LCL Dual Active Bridge Converter to Reduce RMS Phase Current

The three-phase dual active bridge (3ph-DAB) converter, an isolated bidirectional DC-DC converter (IBDC), is gaining increasing interest for its application in high-power industries due to its promising features. However, the prevalent single-phase shift (SPS) modulation method is hampered by significant drawbacks, including high root-mean-square (RMS) currents, substantial reverse power flow, and challenges in achieving soft switching. While numerous modulation strategies have been developed to address these issues, their complexity often limits practical application. This paper proposes an innovative approach by presenting a three-phase LCL dual active bridge (3ph-LCL-DAB) topology that incorporates asymmetrical duty cycle (ADC) control. This method effectively manages non-reactive power, thereby minimizing RMS phase currents across the entire power range. By fine-tuning the duty cycles on both the primary and secondary sides, it aligns the voltage and current phasors, eradicating the reverse power flow in the 3ph-LCL-DAB system. The ADC control significantly diminishes the RMS phase current, a claim substantiated by simulation results demonstrating the technique's efficacy. Simulation results verify its effectiveness.