Improved Position Estimation Accuracy for Sensorless IPMSM Drives using Dual-loop-based Feedforward PLL

The phase-locked loop (PLL) has been widely used in sensorless control for IPMSM drives. High-order PLLs are used to overcome the insufficient dynamic performance of conventional PLLs, but the stability is reduced. This paper proposes a novel dual-loop-based feedforward PLL (DFPLL) to improve the position estimation accuracy during transient process. Firstly, the position estimation error of conventional type-2 PLL caused by frequency ramp input is derived. Secondly, the proposed DFPLL is derived and analyzed. Compared with the conventional type-2 PLL and third-order PLL, the position estimation error caused by frequency changes during transient state is reduced by adopting the proposed DFPLL. Finally, simulation results verify the effectiveness of the proposed method.