Sliding Mode Control Method Of Parallel Three-phase Active Power Filter

Active power filter can compensate harmonic current, flexible and effective. Existing control methods of shunt active power filter are lack of robustness, when load current change rapidly, especially load switching, the shunt active power filters can't compensation harmonic current well. This paper use sliding mode control theory to control shunt active power filters. The content of this paper is:1) We propose a sliding mode control method of shunt active power filters, which can control compensation current and DC voltage unified. We build models of shunt active power filter inαβ. A sliding mode control method to minimize compensation error is proposed in a(3 coordinate system. Existence of equivalent control is proved. Simulation indicate that the method is effective, the THD is 3.75%, reduce from 21.74%.2) According to the characteristics that the change of the DC side voltage is much smaller than the current changes, we view the DC voltage as a constant, and so the model can be simplified with the only currents as state variables. We employ asymptotic rate to design slide mode function, derive the simplified slide mode model of three-phase active power filters, and prove that it is stable at any time. Experimental results show that this method can not only guarantee the system stability, and sudden changes in load control methods to ensure robustness. Simulation indicate that the method is effective, the THD is 3.54%, reduce from 21.74%.3) A 5kVA shunt active power filter experimental device was built, using PM200CLA120 as inverter and TMS320F2812 as its core controller.