Speed control of electrical drives with resonant loads

摘要

This thesis deals with the speed control methods of electrical drives with resonant loads such as rolling mill drives with long shafts, robotic arms with flexible couplings and elevators with flexible ropes. The electrical drive with a resonant load is modeled as a two-mass resonant system. Three speed controlling techniques have been designed: a state-space controller, a two-degree-of-freedom (2DOF) controller tuned according to the rigid system model; and a 2DOF controller tuned according to the flexible system model. The state-space controller is designed based on the pole placement technique and with the assumption that all state variables are available. Both 2DOF methods include PI feedback controllers, where two different feed-forward controllers are considered. The design principles and analytical tuning methods of the controllers are presented. Three simulation studies are carried out to test and analyze the reference-tracking capabilities and sensitivity to disturbances of the designed speed controllers. Finally, the benefits and limitations of the speed controllers as well as some recommendations for future research areas are presented.