Novel analytical model for design and implementation of three-phase active power filter controller

The paper presents a simple analytical model for the design and implementation of a three-phase active power filter controller. Voltage decouplers and pole-zero cancellation are used in current regulators to simplify the current control plant to a first-order delay type. This simplification is made by considering the delay times caused by the lowpass filter of reference current calculation circuits, line inductors of an active power filter and the feedback circuit of a DC-link voltage. From the derived analytical model, the cutoff frequency of the lowpass filter and controller parameters can be appropriately determined to increase the harmonic current compensating capability of an active power filter and accelerate the dynamic response of the DC-link voltage. Analytical and experimental results indicate that the proposed active power filter can largely improve the total harmonic distortion of current and correct the power factor to unity with balanced and unbalanced loads