Operation Characteristic of IPMSM Considering PM Saturation Temperature

In this study, the operation characteristics of an interior permanent magnet synchronous motor (IPMSM) for an electric oil pump (EOP) are analyzed, based on the irreversible demagnetization of the permanent magnet due to temperature saturation. EOP motors are targeted to operate at low-speed high-torque and high-speed low-torque under low and high temperatures, respectively. Hence, the operating temperature is essential for determining the performance characteristics of these motors. Moreover, as a NdFeB type permanent magnet (PM) is utilized, the motor is vulnerable to high temperatures in terms of the irreversible demagnetization of the PM. In this study, the output performance and PM demagnetization ratio of an IPMSM is analyzed at a target ambient temperature. Subsequently, the saturation temperature for each operating point is derived using MotorCAD, which is based on a precise analysis of the thermal equivalent circuit. Finally, the IPMSM for an EOP is analyzed using the derived saturation temperature and compared to the that derived using the ambient temperature.