Real-time prediction of torque availability of an IPM synchronous machine drive for hybrid electric vehicles

This paper presented a methodology for real-time prediction of the torque availabilities of an interior permanent magnet (IPM) synchronous machine and a high voltage (HV) battery sub-system for hybrid electric vehicle (HEV) applications. Having the torque availabilities information available to vehicle system control (VSC) in real-time can ensure the optimal vehicle operations, while reducing vehicle control complexities. In addition, by knowing the real-time torque and power availabilities of the combined motor and battery subsystem, VSC can avoid issuing these commands that exceed the capabilities of the motor and the HV battery such that (a) the battery is protected from excessive draining or excessive over-charging, (b) the motor drive is protected from overheating, and (c) the degradations in vehicle performance due to underperformed motor drive are minimized. Hence, the ability to reliably predict the torque and power availabilities from the motor and HV battery in real-time is beneficial for optimal operations of a hybrid electric vehicle. Extensive test results are presented to validate the proposed algorithm. The methodology implemented here has been in use in fleet hybrid electric vehicles for the last two years