Active disturbance rejection control and energy consumption of three-phase asynchronous motor based on dynamic system’s decoupling

Abstract

To allow a complex, high-order, nonlinear three-phase asynchronous motor to track a load torque quickly and realize high performance speed regulation, a precise nonlinear feedback linearization method based on the theory of differential geometry was used to transform the motor nominal dynamic model into two completely decoupled, second-order, linear rotor speed and flux linkage subsystems. Two active disturbance rejection controllers (ADRC) with identical structures were designed for the rotor speed and flux linkage subsystems. The extended state observer (ESO) of the ADRC could estimate the unmodeled dynamics of the motor and the variation of motor parameters. A crane hoisting motor driving system was selected as an experimental object. A closed-loop system with ADRC and an open-loop system without a controller were compared. The motor’s full-load starting time was reduced by about 50%. When the motor operated smoothly at different load rates and the rated load was suddenly applied, the electromagnetic torque would change, but the fluctuation range did not exceed 20 N·m. The nominal dynamics model of the motor was completely decoupled into two independent subsystems of the speed and flux linkage. The rotor flux was always stable at the reference value. The motor speed decreased, but the amount of decrease did not exceed 7 rad·s−1. The closed-loop system had a significant energy-saving effect during the motor’s starting process. The power saving rate could exceed 50% when the motor started with a light load. Even, the power saving rate could reach about 70% if the motor started with a heavy load. Furthermore, the motor with ADRC could adapt to parameter variations and ADRC exhibited strong robustness.