Induction motor control in presence of magnetic saturation: Speed regulation and power factor correction

Controlling induction motors have been given a great deal of interest. Generally, the control issue has been dealt with, neglecting the saturation effect of the magnetic characteristic and ignoring the presence of the AC/DC/AC converter. The originality of the present work is twofold: (i) the magnetic saturation effect is accounted for in the control design model; (ii) the induction motor is considered together with its AC/DC/AC converter. The control objectives for the association ´converter-machine´ are: (i) forcing the motor speed to track a varying reference signal and optimizing the rotor flux reference, (ii) regulating the DC Link voltage, (iii) assuring a satisfactory power factor correction (PFC) with respect to the power supply net. A nonlinear multi-loop controller is designed using the backstepping technique and formally analyzed using Lyapunov stability and averaging theory. In addition to closed-loop stability, it is proved that all control objectives (motor speed tracking, DC link voltage regulation and unitary power factor) are asymptotically achieved, up to unavoidable, but small, harmonic errors (ripples).