A Novel Rotor Position-Offset Injection-Based Online Parameter Estimation of Sensorless Controlled Surface-Mounted PMSMs

Rotor position estimation error in sensorless controlled surface-mounted permanent magnet synchronous machines (PMSMs) will cause errors in parameter estimation. This paper proposes a novel rotor position-offset injection method for parameter estimation of sensorless controlled PMSMs. During the period of square wave rotor position-offset injection, it is found that the amplitude response of
q
-axis voltage fluctuation decreases with the increasing accuracy of parameters, and thus, stator inductance and resistance can be estimated by controlling the
q
-axis voltage fluctuation. The permanent magnet flux linkage is subsequently obtained from the back-EMF observation. Moreover, the guideline is provided for selecting appropriate amplitude and frequency of injected position offset. Compared with conventional methods, the proposed parameter estimation method is immune to rotor position error. The proposed parameter estimation method based on sensorless controlled PMSMs is verified by experiments at different speeds, loads, and temperatures.