Capacitor-Voltage Self-Balance Seven-Level Inverter With Unequal Amplitude Carrier-Based APODPWM

In this article, a seven-level inverter based on bridge modular switched-capacitor circuits is presented. The inverter cannot only obtain dc–dc boosting conversion ability but also own capacitor voltage self-balance capability. Meanwhile, some of the switches can be operated under line voltage frequency, which makes the control strategy simpler and reduces the switching loss. More importantly, a new unequal amplitude carrier-based alternative phase opposition disposition pulsewidth modulation method is proposed to control the inverter, where the amplitude of the carrier wave will change based on the output voltage level. Under the proposed strategy, the inverter can output seven different voltage levels and the capacitor voltage self-balance can be realized during the switching period, the quality of the output waveforms can be improved remarkably. Last, a loss analysis within the two time-scale of switching period and 1/4 line voltage period is presented to give the loss insight. The simulation and experimental results verify the correctness and practicability of these analyses.