Position self-sensing evaluation of a FI-IPMSM based on high frequency signal injection methods

The flux intensified, interior permanent magnet synchronous machine, FI-IPMSM, lends itself to designing for good self-sensing properties. This paper begins by evaluating the self-sensing position estimation performance of a suitably designed FI-IPMSM machine using different high frequency injection methods. The paper then proposes a new rotor position estimation method for square wave injection. The experiment results show that the estimation accuracy and system robustness is greatly improved by the proposed method. It is known that secondary saliencies and saliency offset caused by the saturation of the machine can degrade the estimation accuracy. This paper also includes modeling, measurement, and decoupling methods that mitigate these undesirable effects, which are also implemented using an experimental FI-IPMSM. Estimation accuracy and torque ripple caused by the injection current are examined for this FI-IPMSM. Comparisons of the methods are presented.