Two flux weakening schemes for surface-mounted permanent-magnet synchronous drives. Design and transient response considerations

Two recently published flux weakening schemes for surface-mounted permanent-magnet synchronous (SMPMS) motor drives have offered estimable advantages over previous solutions. The first scheme uses values of the voltage reference to generate an adequate flux weakening component of the stator current, whereas the second method detects an increase of the tracking error in torque-producing current component and uses the error signal for the flux weakening control. The viability of the algorithms has been demonstrated and the schemes have been compared and analyzed in steady-state operation. The transient behavior is very important for electric vehicles and other high-performance applications. Here, the authors analyze the transient response characteristics of both schemes when a sudden change in the torque reference is received. The paper also describes an approach to practical regulator design and parameter selection for the flux weakening control section.