Controle digital de sistemas de acionamento com máquina assíncrona.

Abstract

This work presents a contribution to the study of control of induction motor on vector field oriented control schemes. The motor drive system employed is composed by a microprocessor IBM-PC-486DX266, a three phase inverter, an acquisition control board and a squirrel cage induction motor. The flux an torque, voltage and current and speed control strategies are developed from the dynamical model of the machine on a specific reference frame. The analysis of control schemes implemented are made due the experimental results obtained. Also, the complexity of the control strategies is analyzed by computing the number of the mathematic operations. Two types of current control scheme are investigated: the predictive and proportional and integral (PI). The last one is implemented on stationary and synchronous reference frames. To reduce the harmonic content on the output currents, the PWM and the current control loop are realized with different sample rates. The flux and torque control schemes are investigated for direct and feedforward control loops. In the direct mode, the flux control loop is obtained by the estimation of the air-gap machine flux. The performance of the feedforward scheme is obtained from the quadrature vector control. A l l the strategies above are realized on the stator/rotor and stator vector flux/rotor vector flux reference frames. Finally, the speed control strategy is implemented by the use of the flux and torque control schemes developed and some experimental results are presented.