A note on the nonlinear H∞ control for synchronous motors

Deals with the nonlinear H^∞ control of a permanent magnet synchronous motor subject to parameter variations during its operation. The control aim is to track a desired angular trajectory. First, a controller based on the nominal parameter values is determined, while the parameter variations are considered disturbances acting on the nominal plant. Second, a nonlinear H^∞ controller is designed in order to satisfy the sub-optimal attenuation problem in the case of availability of the whole state vector. This second step entails the approximated resolution of a (nonlinear) Hamilton-Jacobi-Isaacs equation. The resulting controller is tested in numerical simulations and its performance is compared with that of a linear H^∞ controller