System and method for controlling induction motor applicable to electric motor-driven vehicle

摘要

A system and method for controlling an induction motor which basically achieve reductions in a steady state loss and in a transient loss of the induction motor such as a stepwise input of a torque instruction value Te*. Basically, a steady-state loss minimization magnetic flux calculating section calculates a secondary (rotor) magnetic flux phi r* which minimizes the steady-state loss of the induction motor in response to a torque instruction value. A target magnetic flux phi r and a differentiation of the target magnetic flux d phi r/dt are thereafter calculated using a low pass filter transfer function such as phi r= phi r* 1/(1+ tau phi .S)(, wherein tau phi denotes a time constant, and S denotes a Laplace operator). A target torque Tm is calculates using a predetermined transfer function in response to the torque instruction value such as Tm=Te*.1/(1+ tau T.S)(, wherein tau T is a time constant for the target torque). At the steady state, the slip frequency omega se is set to a loss minimization slip frequency omega se-opt and, at the transient state, a magnetic flux response gives an optimum value corresponding to a torque response described above. The induction motor is used to drive an electric motor-driven vehicle.