Robust control of PMSM using geometric model reduction and μ-synthesis

In this paper we design a linear time-invariant (LTI) two-input-two-output (TITO) controller for the Permanent Magnet Synchronous Motor (PMSM). First the nonlinear system of a PMSM is approximated using a linear system with structured uncertainties according to the PMSM geometric structures. We then design a linear controller for the approximated linear system using a standard μ-synthesis robust control method. The main contribution of this paper is that a unified LTI controller is designed for the nonlinear PMSM plant using mature modern control theory, without referring to classical PID control. Thus largely reducing the design effort. The newly designed robust controller is not only easy to calculate, it is also easy to implement and requires less sensors. By virtue of modern robust control theory, it responds fast to exogenous inputs, and robust against parameter uncertainties as well.