Design and Application of Software Phase-Locked Loop Based on DSP under Voltage Asymmetry

Accurate phase information is very important for stable operation of power converter, such as PWM rectifier. The software phase-locked loop (SPLL) has the advantages of free design and strong adaptability, which can quickly obtain the phase of the grid voltage. In this paper, the situation of voltage asymmetry in three-phase electric network is considered, the principle of SPLL is analyzed, the linearized model of SPLL is obtained, the SPLL controller is designed, and the design of SPLL based on digital signal processor (DSP) is realized. Simulation and experimental results show that the designed SPLL can work well in a PWM rectifier, it has reference significance for the design of SPLL in other electric energy conversion devices.