A Simplified Method to Make the Flux Table Considering Temperature Dependence of IPMSM

This paper proposes a simplified method to make the flux table considering the magnetic flux variation of the IPMSM (Interior Permanent Magnet Synchronous Machine) caused by temperature change in vehicle traction applications. Nowadays, normally an IPMSM with a rare-earth magnet is used for HEV traction applications. But because the flux density of the magnet varies with temperature, the optimal operating points, such as MTPA (Maximum Torque Per Ampere) and MTPV (Maximum Torque Per Voltage) of the motor drift according to temperature change. Those operating points can be expressed in a lookup table, that is, a flux table obtained by off-line experiment, which produces the DQ-axis current command with respect to the torque and flux reference. To reflect this temperature dependence in control, usually flux tables are generated at high, medium and low temperatures. Conventionally, all the three tables are constructed by experiment, which takes a great deal of time. In this paper, suggested is a simplified way that the two tables at low and high temperatures are constructed using a flux table at a medium temperature and the back EMF values at three temperatures. The simulation and experimental results of the proposed method are shown to verify its feasibility.