Characteristics of Interior Permanent Magnet Synchronous Motor with Imperfect Magnets

This paper investigates the effect of demagnetization of the permanent magnets (PM) on the performance of interior permanent magnet motors. In order to remove the individual difference of the motors, several shapes of PMs are prepared, and the experiments are carried out with the same stator. This paper takes into account two types control strategy, V/f constant control and vector control. It is clarified that the stator current and the vibration acceleration are useful for the fault detection of demagnetized PMs under controlled by V/f constant. Under the vector control, the stator voltage and the vibration acceleration are useful for the detection of demagnetized PMs. Moreover, it is found that the fundamental component of stator voltage of the motor with magnets demagnetized in the axial direction is larger than that with magnets demagnetized in the radial direction.