A research on flux weakening control strategy for fast response of PMSM in HEV

The relationship between gear shift time and torque response time of interior permanent magnet synchronous motor (IPMSM) in a parallel hybrid electric vehicle (HEV) with automated mechanical transmission (AMT) is analyzed, and based on over-modulation mode, a flux weakening strategy is proposed, which uses the difference of voltage amplitude before and after over modulation to calculate flux weakening current. The results of simulation and bench test show that the strategy proposed can raise the utility rate of bus line voltage in flux weakening region, attain a torque response time of 20ms without obvious low-order harmonic components of torque and current, and is superior to traditional flux weakening strategy based on output voltage closed-loop control, meeting the requirements of motor torque response for HEV application.