A novel hysteresis current controller for active power filter with constant switching frequency

A novel hysteresis current controller for active power filter (APF) is suggested which is based on optimal voltage vectors and in the meantime with constant switching frequency. In this controller the location region of the reference voltage vector is detected quickly by a set of hysteresis comparators through one trial-and-error process. Two appropriate switches are then selected to control the corresponding two line to line currents independently with constant switching frequency. The new method has the advantages of quick response, good current tracking accuracy, and constant switching frequency. Therefore it is very efficient and secure in operation. Computer simulation results show that the new current control method can improve APF performance noticeably.