ABSTRACT
Rotor position information is required for the field orientation control of permanent magnet synchronous motors (PMSMs). Sensorless techniques for PMSMs are classified broadly into two types: Back-electromotive-force (EMF) based methods and signal injection methods. Back EMF estimation-based sensorless methods have critical drawback in the low frequency area. To overcome such a low-speed sensing problem, signal injection methods were developed: High frequency probing signals are injected into the motor terminal with the main driving power. The influence of measurement errors and inverter irregularities on the performance of the sensorless control was studied by Nahid-Mobarakeh et al. Two sensorless algorithms for SPMSM: Ortega's sensorless algorithm utilizing a nonlinear observer for stationary SPMSM model and Matsui's original sensorless algorithm that is still being used in home appliances are illustrated.
