Switched-boost-based multilevel inverters

Multilevel voltage source inverters/converters (ML-VSIs) with an integrated voltage-boosting feature have been popular in recent years as an interface between the provided low-magnitude DC voltage and standard 220V rms grid voltage. The voltage-boosting feature is achieved with an integrated switched-capacitor (SC) or a switched-boost (SB) technique, while the circuit configuration of the resulting ML-VSIs can be based on a standard half-bridge-based design or a common-ground/midpoint-clamp-based structure. The critical challenges for SC-based ML-VSIs are the discontinuous nature of the input current, pulsating current stress over devices, and the static ratio of the voltage-conversion gain. These challenges require that researchers go through either a two-stage-based boost-integrated design with a front-end DC–DC boost converter or a single-stage SB-based ML-VSI with inherent dynamic voltage-conversion gain. This chapter investigates the state-of-the-art contributions of boost-integrated ML-VSIs and provides insights for overcoming critical challenges like excessive current stress and the inrush current problem. The chapter also outlines the relatively new concept of SB-based MLIs, while the working principles of several recently proposed structures are reviewed and compared.