Robust Control of Permanent Magnet Synchronous Motor: Nevanlinna-Pick Approach

The dynamic performance of permanent magnet synchronous motor (PMSM) is affected by variation of machine parameters due to temperature, saturation and other effects. Design of controller for the PMSM does not consider the robustness issue systematically. We provide a design technique for the robust control of PMSM which takes into account the machine uncertainty, such as, gain variation of the linear model of the machine, in a natural way. The method uses interpolation theory applied to the PMSM machine model. The design technique not only provides robust stability for system gain variation but also can guarantee a certain minimum damping (as desired) of the closed loop system. The technique, being fundamental, can be applied to induction motor and other machine models as well.