A hybrid redundancy scheme for medium‐voltage three‐phase cascaded H‐bridge electronic power transformer

Abstract

A hybrid redundancy (HR) scheme is proposed for the medium-voltage three-phase cascaded H-bridge electronic power transformer (CHB-EPT) based on the combination of the global redundant power modules and local redundant power modules. A “HOT-FIRST-LOCAL-FIRST” transition strategy is designed to achieve a short transition time. Furthermore, to reduce the power loss of the redundant power modules, an intermittent charging (IC) strategy is proposed for the hot-reserved redundant power modules. The detailed analysis of the topology shows that the proposed scheme can achieve low cost, high reliability, low power loss, and good transition performance. The performances are verified by simulations and experimental results.