Boost-type inverter-less shunt active power filter for VAR and harmonic compensation

Harmonics in power system caused by non-linear loads degrade the power quality. As a result, shunt active power filters are widely applied to deal with current harmonics and poor power factor. However, the traditional voltage-source inverter-based active filters, which usually employ large electrolytic capacitors as the energy-storage elements, cannot get much market penetration. An emerging technique that adopts the direct AC–AC conversion and even harmonic modulation can help to eliminate the bulky energy-storage elements while realising the harmonic compensation and power factor correction functions. A three-phase three-wire boost-type inverter-less active power filter for power factor correction and harmonic compensation is presented. The proposed solution eliminates the bulky electrolytic capacitors. Meanwhile, smaller amount of AC capacitors are needed compared with the buck-type AC–AC converters. Furthermore, continuous grid-side current is obtained, which implies that no extra grid-side filters are needed. Numerical calculation is applied to build the model, and the closed-loop control algorithm employing the synchronous reference frame for power factor correction and multi-harmonics compensation is also developed. The proposed topology and control algorithm is simulated in MATLAB/ Simulink and validated with a 15 kVA experimental prototype.