To address the challenge of accurately diagnosing the fault severity in permanent magnet synchronous motors (PMSM) under inter-turn short circuit conditions, a new fault severity diagnosis and prediction method is developed to evaluate the fault turn ratio based on d-axis and q-axis currents and rotating coordinate transformation. Firstly, the stator current under the inter-turn short circuit fault condition is analyzed. Then, the second-order harmonic components of d-axis and q-axis currents related to inter-turn short-circuit faults are extracted by performing a rotational coordinate system transformation, and the fault indicator is established. Finally, a series of experiments have been conducted to establish the functional relationship between the fault turn ratio and fault indicator, and a correction factor related to the motor speed is proposed to enhance the accuracy of fault turn ratio evaluation, thus establishing the prediction method for the fault turn ratio. The verification results have demonstrated that the proposed fault severity diagnosis and prediction method can successfully detect the occurrence of inter-turn short-circuit faults and accurately evaluate the fault turn ratio and exhibit strong robustness to speed variations.

Inter-turn short circuit fault, permanent magnet synchronous motor, fault diagnosis, fault severity prediction