DIGITAL CURRENT REGULATION OF FIELD-ORIENTED CONTROLLED INDUCTION-MOTOR BASED ON PREDICTIVE FLUX OBSERVER

The switching frequency of an inverter for high-power induction motor drive cannot become higher than a few kilohertz, and such switching frequency produces a large current ripple, which, in turn, produces torque ripple. To minimize the current ripple, a new method based on deadbeat current regulation under the field oriented control is proposed. Stator currents and motor speed are measured, by which rotor fluxes are predicted using a state observer with variable poles selection. Then, the PWM pattern of the inverter is controlled such that the stator currents are exactly equal to the reference currents at every sampling instant. This paper describes a theoretical analysis, computer simulations, and experimental results.