  As modern accelerators demand excellent stability to magnet power supply
(PS), it is necessary to decrease harmonic currents passing magnets. Aim at
depressing rappel current from PS in Beijing electron-positron collider II, a
wavelet-based active power filter (APF) is proposed in this paper. APF is an
effective device to improve the quality of currents. As a countermeasure to
these harmonic currents, the APF circuit generates a harmonic current,
countervailing harmonic current from PS. An active power filter based on
wavelet transform is proposed in this paper. Discrete wavelet transform is used
to analyze the harmonic components in supply current, and active power filter
circuit works according to the analysis results. At end of this paper, the
simulation and experiment results are given to prove the effect of the
mentioned Active power filter.
