Novel random switching PWM with constant sampling frequency and constant inductor average current for digital-controlled power factor corrector

The objective of this paper is to present a random switching method which changes switching frequency while retaining constant sampling frequency. The proposed method can effectively reduce magnitude of PWM harmonics. Experimental results derived from an FPGA-based controller are presented for confirmation. The power factor corrector is with 400 W power rating, 90 V/AC/60 Hz input and 385 V/DC output. Experimental results demonstrate the effectiveness of the proposed random switching technique.