An Improved VPI Current Control Strategy

In order to achieve high-precision compensation of LCL-type APF(active power filter) harmonic current error signals, this paper proposes a VPI (vector proportional integral)current control strategy based on the $\alpha\beta$ stationary coordinate system. Compared with the traditional PR (Proportion Resonant) current control strategy, the VPI current control strategy based on the $\alpha\beta$ stationary coordinate system has the characteristics of phase advance, which can compensate the lagging phase of the LCL interface filter, ensuring that the closed-loop frequency response of the current control achieves an ideal 0° phase response at the resonance frequency, which improves the APF current closed-loop control stability and current control accuracy. By comparing the open-loop amplitude-frequency characteristics and closed-loop frequency response characteristics of the PR and VPI current control strategies in the $\alpha\beta$ stationary coordinate system, the excellent characteristics of the VPI current control strategy based on the $\alpha\beta$ stationary coordinate system are demonstrated. The experimental results verify the superiority and effectiveness of the proposed control strategy.