Current Utilization Optimization of DAB-Based Single-Stage AC-DC Converter Using Third Harmonic Injection

The present dual-period-decoupled triple phase shift modulation (DPD TPSM) reduces the utilization of port current, thus limiting the maximum output power of dualactive-bridge based three-phase single-stage (DAB-3P1S) ac-dc converter. A new modulation strategy proposed in this paper involves injecting a third harmonic current to enhance the current utilization of the DAB-3P1S ac-dc converter. This paper utilizes three single-phase single-stage (1P1S) ac-dc converters to create a 3P1S ac-dc converter. The three 1P1S converters are connected in a delta configuration. The third harmonic current circulates among the converters without entering the grid when injected into the single-phase converter port. This method increases fundamental component of the ac port current, boosts the maximum output power without distorting the grid current. Moreover, this article analyzes the impact of this method on current enhancement at different output voltages. It increases utilization of port current and output power of ac-dc converter by 10%.