Measurement-based Modeling of High Frequency Equivalent Circuit of Permanent Magnet Synchronous Motor of Electric Vehicle

The high-frequency circuit model of drive motor will affect the accuracy of electromagnetic interference (EMI) prediction of electric drive system. Therefore, a measurement-based high-frequency equivalent circuit modeling method for the permanent magnet synchronous motor (PMSM) of electric vehicles (EVs) is proposed. The common mode (CM) and differential mode (DM) impedance of star-connected PMSM is measured using a vector network analyzer (VNA). According to resonance points on the impedance curve, the circuit topology of motor winding is determined and parameters are calculated, the high-frequency CM and DM equivalent circuit models of PMSM are established respectively. There is a clear correlation between the components and geometry of the motor. The simulation and measurement comparison results verify the accuracy of the model. The influence of the motor impedance on the conducted EMI is analyzed through the system conducted emission test. Using this model, main components of PMSM that cause conducted emission to exceed the standard can be found, which provides a theoretical basis for suppressing conducted EMI exceeding the standard point.