Sensorless Control of SPMSM Based on Optimized PLL

The technique of phase locked loop is always implemented to calculate the angle and velocity in sensorless estimation for surface-mounted permanent magnet synchronous machine (SPMSM). It takes advantage of simplicity and good performance. However, the PLL deteriorates under transient states because the PLL cannot track the quadratic angle. Many researchers have proposed different methods to improve the PLL by different compensators, which increase the order of PLL. This article implements a feed-forward compensator to develop the dynamics and ensure the stability from another aspect. The compensator is constructed by the lag compensation in control theory. The order of PLL is increased, but the parameters can still be tuned easily. Lastly, the performance is verified through simulation results.