Voltage Balance Control Strategy for FC 3-Level Inverter Based on Zero Vector Time Redistribution

This paper proposes a voltage balancing method based on adjusting the action time of the O redundant vector to address the voltage balancing problem of flying capacitor three-level. Firstly, the main reason for capacitor voltage imbalance in the flying capacitor three-level inverter are analyzed from the topology structure. Based on traditional voltage equalization control, a scheme of voltage regulation coefficient for flying capacitors is introduced: sampling output phase current and flying capacitor voltage, adjusting the time allocation of O redundancy state according to the deviation between actual capacitor voltage and expected value, and adjusting the impact of output current on capacitor voltage charging and discharging, in order to achieve voltage equalization effect on flying capacitors. Finally, a simulation model was built in Matlab/Simulink and an experimental platform was established for verification. The results showed that the scheme achieved stable control of capacitor voltage.