Novel Soft-Switched Three-Phase Inverter With Output Current Ripple Cancellation

A novel three-phase dc–ac full-bridge soft-switched inverter topology is proposed in this article that provides an ultralow ripple output current. The proposed circuit utilizes a passive filter that comprises a transformer, an inductor, and a capacitor for achieving soft switching and output current ripple cancellation. Zero-voltage switching (ZVS) is achieved at turn on time instant for all the switches in the proposed circuit. The magnitude of ZVS current is optimized throughout the line cycle by the application of the variable frequency modulation technique. In addition to soft switching, an ultralow ripple output current is achieved due to the current ripple cancellation property of the proposed circuit. The output current ripple cancellation is achieved by combining the inverter current with an additional high-frequency ripple current generated by the passive filter. The soft-switched inverter operation and inherent current ripple cancellation achieved by the proposed circuit, result in a high power conversion efficiency. Theoretical analysis and the improvements in inverter performance presented in this article are validated through the experimental verification of the proposed converter topology using a $\mathbf{600\text{-}W}$ lab prototype.