A novel single-phase soft-switching unipolar PWM shunt active power filter

This paper proposed a novel single-phase soft-switching unipolar PWM active power filter (SSUPAPF). The proposed active power filter uses a simple auxiliary resonant circuit. The main switches of high-frequency arm operate at zero-voltage- switching (ZVS) turn-on. Also, the auxiliary switches operate at zero-current-switching (ZCS) turn-off. The main switches of low-frequency arm operate at 60Hz to reduce switching losses. Moreover, a unipolar PWM strategy is used for the proposed SSUPAPF. This strategy results in a better input current waveform than for the bipolar PWM strategy. The advantages of the proposed SSUPAPF are found in efficiency improvement, reduced the voltage stresses, and greatly reduced EMI. Furthermore, the proposed active power filter achieves a unity power factor and a sinusoidal line current. Finally, some experimental results are presented for demonstration.