In order to eliminate the influence of traditional harmonic current extraction chain on the dynamic and steady performance of APF

a kind of novel control structure for the split loop decoupling of fundamental current and harmonic current in dq coordinates is proposed in this paper. Through the split loop decoupling

the fundamental current control loop only tracks and controls the DC component to achieve the voltage stability at DC side. The harmonic current control loop feeds the load current directly into the harmonic current loop by taking the frequency selection characteristics of resonance control without the harmonic component extraction

thus eliminating the command signal error and time delay due to harmonic extraction. For improving the phase margin

a kind of novel improved resonance controller is proposed

in which a zero point on the half right side of the real axis is introduced into the cosine internal mode resonance controller. Then

the frequency characteristic comparison and parameter influence analysis are performed in discrete domain. Finally

the effectiveness of the proposed method is verified by the experiment.