DSP based implementation of sliding mode control on an active filter for voltage regulation and compensation of harmonics, power factor and unbalance of nonlinear loads

A TMS320C31 DSP based new and simple control algorithm of a three-phase shunt active filter to regulate load terminal voltage, harmonics elimination, power factor correction and balancing of the nonlinear unbalanced loads is proposed in this paper. A three-phase IGBT based voltage source inverter (VSI) with indirect current control (ICC) is considered as an active filter (AF). In indirect current control of the VSI, a carrier-based PWM control strategy is employed to generate the gating signals for devices used in the inverter. Two sliding mode controllers (SMCs) based closed-loop control scheme of the proposed AF uses the three-phase supply voltages and DC link voltage of the AF as the feedback signals and generates the three-phase reference supply currents which are inputs to the PWM current controller. A prototype laboratory model of the AF is developed and its performance is examined for voltage regulation and compensation of harmonics, power factor and unbalance. The experimental results are given and discussed in detail.