Sensorless control for PMSM in underwater propeller based on improved phase-locked loop

Abstract

As the core part of underwater propeller, the performance of permanent magnet synchronous motor (PMSM) affects the thrust of it. In the operation of a PMSM, when the speed of PMSM is reversed, a position error of 180° will be generated by the traditional phase-locked loop (PLL). In this paper, an improved PLL based Luenberger observer is proposed to resolve this problem. The back electromotive force (EMF) was been obtained by the Luenberger observer. In contrast to the traditional PLL, the improved PLL has a different phase discriminator to tackle rotor position errors. Results of simulation and experiments show the effective convergence of the proposed improved PLL for rotor position errors and that the trust of propeller meets the requirements.