Modeling and Sliding Mode Control for Three-Phase Active Power Filters Using the Vector Operation Technique

Traditionally, the vector operation technique (VOT) has been used to control three-phase converters using one cycle control. In this paper, a three-phase active power filter large-signal model with a VOT in a new coordinate system is presented. By using the VOT, only two phase-legs are switching at high frequency, thus reducing the switching losses. This paper not only covers the literature gap about the modeling of three-phase converters using the vector operation, but also presents a sliding mode control for this converter. The control scheme consists of a nonlinear matrix transformation in order to obtain the voltages and currents in a new two-dimensional frame, \gamma \theta-frame, a sliding mode controller designed in these coordinates, and a modulator to obtain the control signals in a natural frame. The sliding mode control is designed with the help of the presented large-signal model assuring sinusoidal grid currents in phase with the grid voltages. This controller provides a fast transient response against sudden load changes with a good current tracking capability and a reduction of the switching losses. A stability analysis is performed in order to validate the control parameters. Experimental results are provided using a fully digital control system in order to validate the performances of the proposed controller.