Abstract
The given paper presents an application of linear H-infinity control technique on SPMSM for robust control without load torque observer. It is possible due to additional equation embedded into mathematical model of the SPMSM model to provide tracking capability. Despite of severe conditions such as high parameter variations and unknown load torque, H-infinity control method demonstrates robust speed tracking. H-infinity controller minimizes the effect of unmatched disturbance, i.e. load torque disturbance, on the output. The proposed control technique was compared with conventional three equation state-space model H- infinity controller. The proposed control scheme was shown to effectively attenuate both matched and unmatched disturbances. Although the transient characteristics are not as smooth as in the case of conventional third order system, the proposed robust H-infinity controller exhibits satisfactory behavior in conditions of load torque step changes and dramatic motor parameters changes without load torque observer.