A Class of Nonlinear Active Disturbance Rejection Loop Filters for Phase-Locked Loop

Abstract

It is well-known that a phase-locked loop (PLL) technique is widely used in engineering scenarios, recovering and synthesizing the phase and frequency values. The loop filter is the core part of the PLL. This article proposes a class of nonlinear active disturbance rejection loop filters for the PLL. First, we present the detailed nonlinear mathematical model of PLL in consideration of the phase unbalancing, the voltage harmonics, and the voltage offset. Next, based on the model, a class of nonlinear active disturbance rejection loop filters with different nonlinearity degree-of-freedom are proposed in the synchronous reference frame, which can make the PLL in possession of better performance in comparison with that of PLL designed by traditional methods. Moreover, the parameter tuning rules of the nonlinear loop filters are given. Furthermore, hardware-in-the-loop experiments are finished in the dSPACE platform so as to check the real-time performance of the loop filters in more electronic aircraft power grid system scenario. At last, we conclude that the loop filter with the nonlinear generalized integrator extended state observer type2 possesses the best performance among the three loop filters for PLL in this article.