Active Filter Based on Four-Leg Inverter and PQ Theory

The active power filter and unbalance compensator systems play an important role in power quality enhancement. This paper introduces the active power filter based on the 4-leg inverter for 4-wire applications. This system is capable to filter the source current from both harmonics and unbalance components. The analysis and simulation are based on calculating the control reference current based on p-q theory to compensate for the unwanted current components in the supply source. Also, a comparison between the Hysteresis Current Controller (HCC) and Three-Dimensional Space Vector Modulation (3DSVM) technique has been done. The 3DSVM achieves a lower current total harmonic distortion (THD) than that of the HCC.