Abstract：To improve harmonic current tracking performance of shunt active power filter (APF) based on double hysteresis current control strategy of voltage space vector, a novel 4level αβ hysteresis comparator was proposed. The control strategy was directly implemented on αβ coordinates. The 4level αβ hysteresis comparators were inputted current error vectors and outputted 4 state values to determine the location region of current error vectors. The differential relationship between reference voltages and reference currents was discretely calculated to determine the location region of reference voltage vectors. The optimum output switching vector at each instant was selected according to state values output of two 4level αβ hysteresis comparators and reference voltage vector. The compensatory current error was limited within the hysteresis width. APF models with constant load and variable load were established and simulated by Matlab/Simulink software. The results show that the proposed strategy can efficiently increase the utilization of DC bus with fast response. The total harmonic distortion of power grid current drops from 21.65% to 3.11%， and the per phase switching number in one power supply cycle decreases from 342 of the conventional hysteresis control to 230 of the proposed method at steady state.
2013, Vol. 34 
