Variable switching frequency PWM for quasi‐Z‐Source inverter based on DC current ripple prediction

Abstract

Herein, a variable switching frequency pulse width (VSFPWM) modulation strategy for quasi‐Z‐source inverter (qZSI) based on a recently proposed modulation method, named as ZSVM8, is proposed. The formulae of quasi‐Z‐source inverter inductor current ripple of ZSVM8 are deduced in detail, and a prediction model for the current ripple is obtained. Combining with the VSFPWM technique, an improved modulation method named ZSVM8 VSFPWM is proposed to further reduce the switching times without increasing the maximum inductor current ripple. As a result, the switching losses can be reduced compared with the conventional ZSVM8. Besides, ZSVM8 VSFPWM also suppresses electromagnetic interference noise, such as current EMI and common‐mode voltage. Simulations and hardware experimental results are implemented to verify the efficacies of the proposed modulation method.