PCC Voltage Switching Harmonic Mitigation by Periodic Carrier Frequency Pulsewidth Modulation for SiC High-Frequency Active Power Filter

The high-frequency active power filter (HF-APF) is an effective solution to suppress the grid-wideband harmonics. However, with the increase of switching frequency, the harmonic voltage pollution at the point of common coupling (PCC) becomes worse. This article introduces a novel periodic carrier frequency pulsewidth modulation (PCF-PWM) scheme for HF-APF. Compared with the traditional sinusoidal PWM and random switching frequency (RSF) PWM schemes, PCF-PWM not only would decrease the switching harmonic amplitudes in the PCC voltage by dispersing the harmonic energy within a certain band, but also has better performances working with the selective harmonic extraction algorithm. The basic principle of PCF-PWM is introduced and the harmonic reduction effect is analyzed quantitatively. The harmonic reference extraction errors are analyzed with different modulation schemes, and the superiority of the proposed method is revealed. Experimental results from a 380 V/10 kVar/100 kHz SiC-MOSFET based HF-APF prototype verify the correctness of the theoretical analysis.