Decentralized Capacitor Voltage Control of Flying Capacitor Multilevel Inverter

This paper proposes a decentralized capacitor voltage control strategy for the flying capacitor multilevel inverter (FC-MLI) in combination with the decentralized self-aligned phase-shifted pulse width modulation (PWM) (self-aligned carriers) method. For FC-MLI, the capacitor voltage of switching modules requires a special condition of initial capacitor voltage to startup and reach the desired value. To overcome this issue, a decentralized capacitor voltage control algorithm is proposed to regulate the capacitor voltage to the required value under normal operation as well as in case of reconfiguration of the system when the number of switching cells is changed. The key approach is that each switching cell controller of the FC-MLI synchronizes and regulates its own voltage effectively by using information from its neighboring cell controllers. The validity of proposed decentralized capacitor voltage control method in association with the self-aligned phase-shifted carriers is shown by simulation results using Matlab Simulink software.