Optimum Control for Interior Permanent Magnet Synchronous Motors (IPMSM) in Constant Torque and Flux Weakening Range

Interior Permanent Magnet Synchronous Motors (IPMSM) gain importance due to their high torque per volume ratio particularly for hybrid electrical vehicles. However, unlike to standard control theory, the torque control strategy for these motors is not apparently due to their reluctance torque, which is typical with interior magnet design. In this contribution, a control strategy is presented, which enables optimal torque control both in the lower speed range as well in the full flux weakening range. Operation during flux weakening, however, causes stress to the magnets of the motor with the risk of permanent demagnetization. The relations between the crucial design parameters are shown.