Coupled-inductor buck-boost inverter with reduced current ripple

This article presents novel buck-boost inverter using coupled inductors and half-cycle phase-shifted modulation. The effective switching frequency of the input inductors is twice the actual switching frequency of semiconductor switches. In addition, the number of voltage levels of the input inductors is increased and the voltage magnitude is decreased. As a result, the input inductors are designed much smaller and the current ripples of both the input inductors and the dc voltage source are decreased. To reduce the number of inductors, input inductors are incorporated in the leakage inductance of the coupled inductors. Moreover, part of the circuit can be bypassed to improve the efficiency of the proposed inverter. The clamping switches decrease the power loss of circulating current and improve the peak efficiency to 97.2%. Besides, the proposed inverter has no shoot-through. Furthermore, mosfets can be used without reverse-recovery issues and associated loss. As a proof of concept, the experimental results of the proposed single-phase 500-W prototype inverter with 100-200 V input voltage and 110 Vrms output voltage at 50 kHz are provided.