基于H∞鲁棒二阶广义积分器的单相逆变器锁相环电网同步方法

This article proposes a new design framework based on H_ control theory to synthesize the loop filter (LF) of phase-locked loops (PLLs). Taking the frequency-fixed and frequency-adaptive second-order generalized integrator (SOGI) PLLs as representative cases, the control problem is formulated in terms of the PLL's voltage-controlled oscillator while considering the influence of the SOGI block on the PLL dynamics. By specifying the weighting function as a function of PLL settling time in the H_ control problem, optimal LFs are obtained to achieve robustness in the PLL's tracking performances. Furthermore, reduction of the LF's implementations and computational costs without loss in performance are achieved by means of Hankel singular value approximation. Performance-wise, the proposed SOGI PLLs provide robust estimations of a single-phase voltage's frequency and phase angle when compared with their existing pairs through experimental studies. Finally, employing the proposed PLLs for grid synchronization of a single-phase inverter demonstrates reduced power oscillation when compared to the conventional proportional-integral control-based PLLs.