A Novel Modified PLL-based Position Estimator in SynRMs Injection-based Sensorless Control

For the purpose of improving the dynamic performance of the injection-based sensorless control for synchronous reluctance machines, a novel phase-locked loop (PLL)-based position estimator has been proposed. The new estimator is modified from the conventional proportional-integral-based PLL by adding a feedforward path as a new control degree of freedom (DOF). Hence, the dynamic performance could be improved by designing the 2DOF controllers. One of the controllers could eliminate the adverse effect of the preceded filter, while the other dominates the cutoff frequency of the estimator. Therefore, the proposed estimator can be treated as a kind of first-order low pass filter with less 'aggressive' for position and speed tracking. Finally, the effectiveness of the proposed method has been verified on the simulations and experiments.