For the traditional phase-locked loop based on synchronous reference frame (SRF-PLL), the frequency estimation is directly affected by abnormal changes of grid voltage phase. In this paper, the influence of controller parameters on the coupling relationship between phase and frequency is analyzed and a variable inertia synchronous reference frame phase-locked loop (VISRF-PLL) is proposed. The input frequency error is used to construct an adaptive function, which dynamically adjusts the time scale of frequency estimation link and weakens the coupling effect of forward channel variables. The results of simulation and experiment show that the proposed method can reduce the frequency fluctuation in the transition process and increase the response speed of the system. It is more suitable for frequency sensitive converters.
