Adaptability Research of the Dynamic Equivalent Model of Variable Frequency Drive Motors

With the increasing proportion of variable frequency drive motors (VFDMs) in production and daily life, the classical load characteristics of motors will change, and the existing load models need to be adjusted accordingly. Therefore, it is necessary to conduct research on the dynamic equivalent model of the VFDM. At present, some equivalent models and methods have been proposed. However, the accuracy of these equivalent models has not been compared, and the adaptability of the models has not been comprehensively tested. Therefore, this article first experimentally obtained the dynamic response data of VFDM under different operating conditions and voltage drop forms. Then, the accuracy of the motor model equivalence method, multiple regression equivalence model, and transfer function equivalence model (TFEM) in characterizing the dynamic characteristics of VFDM was compared. Considering the possibility and convenience of future improvement, we recommend to use TFEM to represent the VFDM. Subsequently, the adaptability of the TFEM to different voltage drops, equipment initial power, and different fault modes was tested. The results indicate that the existing TFEM has good adaptability to different voltage drops, while improving its adaptability to different initial powers of the VFDM and different fault types is crucial, and attention should be given to improving the accuracy of reactive power dynamic characteristics.