A robust total compensation algorithm for the torque control of a synchronous servomotor

In this paper, we present a performing torque controller for a synchronous servomotor. As we will see, this controller, called the total compensation controller, brings a new solution to the defects of the well known proportional integral controller in the D-Q frame, omnipresent in industrial applications. Here, we propose a comparative study of these two algorithms, the main problem of the proportional integral controller in the D-Q frame being its high sensitivity to the speed's dynamics. We show that the total compensation controller resolves this problem. Nevertheless, the total compensation controller algorithm requires a measurement of the mechanical speed. Thus, we had to test its robustness with respect to an imprecise measurement of the motor velocity. As we will see, this controller is not robust enough. In order to improve this robustness, we propose a solution : the total compensation controller with integrators. This last controller, which has been implemented with a broadly diffused microprocessor (Intel 8086), presents convincing features : a fast torque response time for any dynamics of the mechanical speed, with a very good robustness.