Direct power control of active filters with averaged switching frequency regulation

This paper develops a direct power control structure to improve the performance of active filters. The PWM switching functions are defined based on the instantaneous power terms and the bandwidths of the two hysteresis comparators are dynamically adjusted to limit the averaged switching frequency. The controller directly uses the instantaneous power as control variables, to replace the current and voltage variables used in multi-loop control systems. It demonstrates that full control of the active filter, including the line current and the dc-bus voltage, can be realized within an integrated control loop. The advantages of the proposed control strategy are verified by simulation and experimental results on a 2 kVA laboratory prototype.