Single-Phase Phase-Locked Loop Based on Tracking Differentiator

To better capture the phase information of single-phase power grids, a novel single-phase phase-locked loop method is proposed in this paper. The method uses a tracking differentiator as an orthogonal signal generator. Because the generator is sensitive to the input signal’s frequency, the amplitudes of the tracking and differential signals may not be equivalent, causing a failed phase tracking. Therefore, the amplitude correction of the differential signal needs to be done. Then, the corrected differential signal and the tracking signal are both input to the phase detector. To further verify the practical feasibility of the method, the voltage sampling and phase tracking experiments were performed on a digital signal processor-based inverter experimental platform, which is aimed to simulate the grid. The experimental results show that the proposed algorithm has strong dynamic performance and steady-state performance under different states of the power grid, and the phase-locked method has a practical feasibility in single-phase grid-connected applications.