Interconnection and damping assignment approach to control of PM synchronous motors

We apply the energy-shaping controller design technique to the speed regulation of permanent magnet synchronous motors. To illustrate different design choices, two controllers are presented along with their stability analysis. The resulting schemes consist of a static state feedback to which a simple nonlinear observer is added to estimate the unknown load torque. It is shown that, for isotropic rotor machines, we can set the tuning gains to recover a controller often used in industrial applications, where a nonlinear observer is used instead of a simple proportional integral (PI) speed loop. Thus, the proposed scheme constitutes a possible upgrade to current practice which, in view of the availability of a complete stability analysis, should be easier to tune and yield an improved performance. Simulations and experimental results are presented to illustrate the performance of the proposed scheme.