An Enhanced Linear Extended State Observer Based Sensorless Control for PMSM Drives

Sliding-mode observer (SMO) based sensorless field-oriented control (FOC) methods have been widely employed for permanent-magnet synchronous motor (PMSM) drives in medium-speed and high-speed electrical vehicles. However, these methods have two main problems, i.e., phase delay and speed chattering problems. Moreover, the position estimation performance is subjected to position harmonic ripples caused by inverter nonlinearities and flux spatial harmonics. To cope with these issues, an enhanced linear extended state observers (ELESO) based sensorless FOC scheme is proposed in this paper. The ELESO consists of two ELESOs. One LESO is designed to estimate the back electromotive force (EMF) including high-order harmonic contents, which is treated as the external disturbance, without using any low-pass filters or switching functions. Another LESO is designed to only estimate the internal disturbance, i.e., high-order back EMF harmonic contents, which in turn further enhances the performance of the rotor position estimation. The proposed ELESO-based sensorless FOC scheme is validated by experimental results for a 275-W salient-pole PMSM drive in which the PMSM is similar to the traction motor used in Toyota Prius hybrid electric vehicles at a reduced scale.