Three-Phase Single-Stage Bidirectional CCM Soft-Switching AC-DC Converter With Minimum Switch Count

In this article, a three-phase single-stage bidirectional ac-dc converter with low component count is proposed. The single-stage structure is configured by integrating a three-phase ac-dc converter and a three-phase dual active bridge converter. The power factor correction and bidirectional power control are performed by adjusting the modulation index of sinusoidal pulse width modulation (SPWM) and phase-shift angle between the primary and secondary bridges. The low-frequency components generated by SPWM are absorbed by fundamental blocking capacitors connected in series with transformer windings, resulting in true high-frequency isolation. The proposed converter can achieve soft-switching of all switching devices even in continuous conduction mode. A 110 Vac, 3 kW, 100 kHz prototype is implemented to validate the proposed concept and demonstrated 95.34% peak efficiency.