Dual Signal Injection-Based Online Parameter Estimation of Surface-Mounted PMSMs Under Sensorless Control

The rotor position error in sensorless controlled permanent magnet synchronous machines (PMSMs) will lead to parameter estimation errors. In this paper, a novel and simple online parameter estimation method with dual signal injection is proposed for surface-mounted PMSMs under sensorless control, by which the winding inductance, resistance, and rotor flux linkage can be estimated immune to the rotor position error. It is found that the response from <tex-math notation="LaTeX">qᵉ</tex-math>-axis voltage caused by injecting a square wave position offset to the estimated rotor position and the response from <tex-math notation="LaTeX">qᵉ</tex-math>-axis current caused by injecting a square wave current to the <tex-math notation="LaTeX">dᵉ</tex-math>-axis are solely related to winding inductance and resistance errors, respectively. Since the amplitudes of both responses decrease as the parameter errors reduce, the responses in <tex-math notation="LaTeX">qᵉ</tex-math>-axis voltage and current are controlled to minimum for estimating the winding inductance and resistance, respectively. At last, the rotor flux linkage is estimated from the observed back-EMF after winding inductance and resistance estimations are completed. The experiments are performed to verify the proposed method.