Adaptive speed control of AC servo induction motors with on-line load estimation

An adaptive speed control with load torque compensation for AC servo induction motors is proposed. This adaptive control loop that precedes the field oriented control loop consists of a proportional plus integral (PI) controller and a load torque compensator. Their control gains are adjusted adaptively in terms of estimated parameters of an estimation model. The estimation model is a simple first-order predictor with a nonlinear load term, whose parameters are functions of motor time constant, moment of inertia of the rotor, load torque and sampling time of the discrete-time motor model. The total control law is then a combination of the adaptive PI control gain and the load compensation, resulting in a torque command that is fed into the field oriented control loop. Simulation and experimental results show that the proposed adaptive control strategy is robust to the load change and system parameters variation.