The Variable-frequency Carrier Bands Pulse Width Modulation Using in Cascade H-Bridge Converter

In this paper, cascade H-bridge converter with Variable-Frequency Carrier Bands PWM method (VFCB-PWM) has been proposed, which is the combination of cascade structure and CPS-SPWM method. High equivalent switching frequency can be obtained with low switching frequency devices. Such advantages as simple structure, wide bandwidth and good transient response can be obtained in large power equipment. Moreover, reducing the harmonic content and increasing the DC voltage of Variable-Frequency Carrier Bands PWM is also employed all right. Simulation result proves that cascade multilevel converter based on Variable-Frequency Carrier Bands PWM can achieve excellent performance of reducing the harmonic at much low switch frequency, which is of perfect prospect in industry application.