Current controller for active power filter based on optimal voltage space vector

An hysteresis current controller for an active power filter based on the optimal voltage space vector is proposed. The controller jointly utilises two sets of phase current difference comparators to determine the location region of the reference voltage space vector and the current error space vector. When the system reference voltage space vector is changing rapidly and randomly, which makes its location region very difficult to estimate, the novel controller can quickly detect its location region by a trial-and-error process which is essential to the performance improvement of active power filters. The related concept and formulation are presented. A computer simulation is conducted on a test system and the results show that the controller can quickly determine the optimal voltage space vector, therefore effectively reducing the current tracking error. Since the new controller can reduce VSI switching frequency, it can reduce the switching loss and improve APF efficiency noticeably