A comparative study of shunt hybrid and shunt active power filters for single-phase applications: Simulation and experimental validation

The aim of this paper is to compare the performance of the single-phase shunt active power filter (SPSAPF) and the single-phase shunt hybrid power filter (SPSHPF) that adopt both an indirect current control scheme with a unipolar pulse width modulation (U-PWM) strategy. The SPSHPF topology includes, in addition to the components of the SPSAPF, a power factor correction capacitor connected in series with a transformer. The primary winding of the transformer is connected to the single-phase voltage–source inverter, which is the main part of the filter. The indirect current control technique that is implemented for both filters is based on extracting the source current reference from the distorted waveform of the load current. The U-PWM control technique is based on comparing simultaneously a triangular high frequency carrier signal with a slow-varying regulation signal and its opposite. The double comparison process results in the gate signals for the semiconductors. A laboratory prototype for each filter is built. It is demonstrated that the rating of the inverter used in the SPSHPF is three to four times lower than the one corresponding to the SPSAPF. In addition, the performance of the SPSHPF is found to be much better than that of the SPSAPF as far as the line current distortion is concerned.