An improved high-frequency square wave injection considersing the variction of inductance

Resulting in the error of rotor position estimation, harmonics of high-frequency response incremental (HFI) current are generated by the nonlinear characteristics of inductance. In this paper, a new high-frequency square wave injection (HFSWI) scheme considering the variation of the inductance is proposed and implemented. Compared with the conventional one, the key is to establish a new model of high-frequency square wave injection method with the change of inductance, and improve the conventional rotor position signal observer. And with the new scheme, the harmonics of HFI current generated by the dynamic change of the inductance have been successfully suppressed. Both computer simulation and experimental results verify that the proposed strategy exhibits good capability in harmonic suppression and retain the accuracy of estimated angle.