Novel Hysteresis Current Controller for Active Power Filter

The switching losses of Active Power Filter (APF) is one of the important factors that influence the performance-price ratio of APF. In this paper, a novel method is suggested. Under this new method, each phase output reference current of APF is compared to adjust hysteresis of each phase, so that the switching number of the phase that has greater switching losses is decreased, meanwhile the switching number of the phase that has lowest losses is increased to maintain overall control precision. Only an adjusting circuit is needed, and the switching losses will be decreased significantly. Computer simulation under electro-magnetic transient program shows that, this method can decrease the switching losses significantly but has the same control precision and switching frequency, and the temperature rising of each phase switching device become more smoothly.