Nonlinear control of synchronous servo drive

The complete tracking control for a permanent magnet synchronous (PMAC) motor, based on two nonlinear design methods is presented in the paper. The motor model, given in the rotor´s d-q coordinates, is nonlinear with respect to the state variables and linear in the control. First design method is based on Lyapunov´s stability theorem and the second one on input-output linearization approach. In both cases the derived control law implies similar nonlinear feedback structure. The input-output linearization makes it possible to write the motor´s model in Brunovsky´s decoupled canonical form which allows the synthesis of linear controllers. The proposed control laws allow perfect tracking of smooth references in the case of nominal parameters. In relation to the bounded parameter perturbations the robustness of the input-output linearized feedback system is improved by introducing an additional compensation signal which assures the stability of the perturbed system in Lyapunov´s sense. The experimental results of the proposed PMAC servo drive control are presented.