Novel five-level inverter based on DC power-capacitor series charge-discharge switching strategy

Abstract

Photovoltaic power generation systems generally include four modules: solar cells, batteries, inverters and controllers. Among them, the inverter converts the direct current generated by the photovoltaic array into a power conversion device that meets the grid-connected requirements for industrial frequency alternating current, which is the key equipment for grid-connected photovoltaic power generation system. Most multilevel inverters in the market today are based on the Neutral-Point-Clamped (NPC) structure to generate voltages at different levels, and then control the magnitude and direction of the voltages through H-bridge circuits. This topology has been maturely used in three-level inverters, but if we want to build five-level, seven-level and more level numbers of inverters based on NPC, the number of capacitors used is increasing, and the circuit becomes more and more complex. Therefore, this paper proposes a five-level inverter topology based on single power supply-single capacitor series charging and discharging. (Power-capacitor series charge-discharge switching, PCSCDS). This inverter has a simple structure, comprehensible control strategy and requires only one DC power supply and one large capacitor to generate a five-level voltage. The topology is subsequently simulated and analyzed by MATLAB/Simulink simulation, which proves the effectiveness of the novel inverter.