Study on Load Torque Identification On-line Based on Vector Control of Saliency PMSMs

To overcome the influence of load torque change on rotor speed, a variable-structure MRAS observer for load torque was proposed. This observer was used to estimate load torque and updated the load value used in speed regulator on- line. This strategy selected PMSM itself as reference model and its current model as the adjustable model; the sliding mode surface was formulated based on two model output errors. The simulations were carried out to verify the availability of the observer. The results demonstrate that the load torque observer possess good dynamic and static performance, and improve the robustness of PMSM drive system.