Robust control of a permanent magnet synchronous machine

This paper describes an application of the robust control theory applied to a Permanent Magnet Synchronous Machine (PMSM). To keep a simple design, the authors considered only parametric disturbances of the process coefficients. In this particular case, inertia is the uncertainty parameter. To avoid the uncertainty problem, usage of the H_∞ robust control theory is proposed. As a first step, all the equations of the motor must be defined and presented in the state space domain. As a further step, a H_∞ controller is designed by using the H_∞ robust control theory. This allows the variation of inertia into a predefined range. While the selection of the weighting functions is not unique, finding them is an important problem in the robust control design. In most of the cases such functions can be either low pass filters or band pass filters. The authors are proposing a method to cope with the required system performance. The design and the experimental results are done in Matlab.