Three-Phase Step-Up Multilevel Inverter With Self-Balanced Switched-Capacitor

Abstract

This article presents a new three-phase multilevel inverter with boosting capability for low-voltage applications like electric vehicles and renewable energy sources. This inverter is fed by a single dc voltage source and each phase involves two low-voltage transistors, two high-voltage transistors, two diodes, and two capacitors. Except that the two high-voltage transistors withstand twice the dc input voltage, all other components are rated to the dc input voltage. With phase-disposition pulsewidth modulation, the two types of high- and low-voltage transistors operate in low and high switching frequencies, respectively. This is very beneficial for reducing switching losses and selecting semiconductor switches. The two capacitors are connected in parallel and series alternately with the dc source resulting in high ac output voltage with multiple levels, self-balanced capacitor voltages as well as low voltage ripples. The topology, operation principle, capacitors' voltage ripples and power loss are analyzed in detail. Both simulation and experimental results are provided to demonstrate the feasibility of the proposed inverter.