Vector control of an IPM synchronous machine capable of full range operations for hybrid electric vehicle application

Interior PM (IPM) synchronous machines are popularly used as traction motors for mild hybrid and hybrid electric vehicles. In order to achieve desired performance, such as, propulsion of the vehicle, torque boost, charging battery, driveline synchronization during gearshift, and active damping of driveline oscillation, the IPM synchronous machine must be able to operate at every load point inside the envelope as defined by the maximum torque-speed curve. The maximum electrical speed is typically in the range of 36000 RPM. These requirements represent considerable challenges to the motor control strategy, particularly the field weakening strategy. This paper presents a simple, yet practical field weakening strategy and the associated control techniques to ensure the traction motor drive capable of full range operations for the desired performance in hybrid electric vehicle applications. Extensive experimental results, including torque and speed transient responses, phase current responses, full range steady state torque control performance, power losses over the entire operating range, are reported to demonstrate the performance of the drive over the entire operating ranges and consequently the validity of the proposed control strategy.