A Single-Phase Dual Active Semi-Bridge Converter

The dual active bridge (DAB) converter is the topology of choice for bidirectional energy transfer between two galvanically isolated dc sources. The single-phase full-bridge DAB converter allows synthesizing primary-side and secondary-side switched voltages utilizing the full primary-side and secondary-side dc-link voltages and offers the versatility of operating with single-phase-shift (SPS), dual-phase-shift (DPS), and triple-phase-shift (TPS) modulation schemes. Conversely, the single-phase half-bridge DAB offers substantial cost benefits by replacing four of the power switching devices with capacitors at the expense of limited single-phase-shift (SPS) modulation only and synthesis of switched voltages that utilize half the dc-link voltages. This digest presents a topological variant of the single-phase full-bridge DAB converter formed by replacing the primary-side and secondary-side phase legs with asymmetrical semi-bridge phase legs. This new arrangement retains the benefits of galvanic isolation, bidirectional power flow, full dc-link utilization, and the SPS, DPS, or TPS modulation capability of a full-bridge DAB converter while using half the number of semiconductor devices and gate drives. The single-switch characteristic of semi-bridge phase legs eliminates the need for switching dead-time and the associated distortion and control non-linearity. Results from switched simulations and experiments on a 2-kW proof-of-concept prototype are presented to demonstrate the converter operation at non-unity primary-to-secondary voltage ratio under forward- and reverse power flow conditions.