A nonlinear, field-oriented model is described for saturated induction machines. The model is an extended version of the rotor-flux-oriented dynamic model developed by W. Leonhard (1985), which is valid under linear magnetic conditions and is used in a wide range of applications. The effects of main flux saturation are discussed. The theory is applied to an induction machine subjected to field-oriented control which operates in the field-weakening region where the changes of saturation level play an important role in the dynamic behavior. It is also shown that, with the implemented current control, the control response is seriously distorted by the effects of variable saturation during field weakening. >