Current control method of IPMSM in constant power region for HEV

In the flux-weakening control, Interior Permanent Magnet Synchronous Motor (IPMSM) for traction motor of Hybrid Electric Vehicles (HEVs) makes it possible to operate at the region of high speed and assists the power, which improve the efficiency of HEV. If the magnetic flux generated by the rotor does not reduced enough in the constant power region, the current controller is saturated and then the transient response of the current controller will be unstable. It leads to decreases the efficiency of the vehicles because the traction motor is operated as load. In order to solve this problem, the method that flux-weakening is operated under rated speed of the IPMSM is commonly used. However, it causes to reduce the torque due to the limitation of the phase current. This paper presents the current control method in the constant power region to avoid the saturation of the current controller. The simulation and experimental results are represented for the verification of the presented method.