Three-phase Single-stage Bi-directional Electrolytic Capacitor-less AC-DC converter with minimum switch count

摘要

The paper proposes single-stage three-phase bidirectional ac-dc converter with high frequency isolation. The proposed converter is composed of a three-phase PWM converter and a three-phase dual active bridge (DAB) converter through circuit integration. The low frequency component that is inevitably generated in the process of ac-dc power conversion is absorbed by low frequency blocking capacitor (LFBC) connected in series with the transformer wingding, and the low frequency component is almost not applied to transformer, resulting in enabling high frequency isolation. Also, power factor correction (PFC) and bidirectional power control are performed by two control variables, amplitude modulation index and phase shift angle, and soft switching of all switching devices is possible even in continuous conduction mode (CCM) operation. A prototype was built and experimental results are obtained and discussed in order to verify validity of proposed concept.