ANALYSIS AND DESIGN OF A UNIPOLAR AC-AC THREE-PHASE ACTIVE POWER FILTER BASED ON SWITCHED MODE TECHNIQUE

This paper presents and analyzes a novel topology for harmonic mitigation in three-phase system. The power circuit is simple which employs two single-phase unipolar bi-directional ac/ac converters that are based on switched capacitor (SC) technology. Unlike the traditional active filters, the scheme presents fast speed of response and does not create low order harmonics. Further, the voltage across the capacitors can be limited to a range of relatively low values by an adequate design of the passive components, which reduce the rating of them. The circuit can reduce the number of switching devices compared with the inverter based active filters that may reduce the power losses in the system, increase its reliability, and reduce its cost. Finally, the effectiveness of the design methodology of the scheme is verified by simulation with PS CAD software which proved that the scheme could compensate for harmonics for different nonlinear loads.