Abstract
A single-phase active power filter (APF) with nonlinear load is disclosed. The APF adopts a 'direct power current control method'and uses only a current converter with a current detector to detect the side current of the power source. By means of the self-learning law of the current converter', 'current converter with current detector', and 'the circular-graphics method of power limit', the following purposes can be achieved: reaching the nonlinear inductance value of an on-line measurement of the current converter, estimating the output current of the current converter, and controlling the output power of the current converter. Hence, this invention is able to make improvements on the conventional active power filter with its inabilities such as: being unable to take the nonlinear characteristic of the current converter into consideration, adding an additional current detector is needed to measure the output current to obtain the degree of the compensation current of the power filter, and being incapable of actively adjusting the power filter in terms of invalidity and distortion of power.