Modeling and control of an AMBs supported milling spindle

Abstract

In machining applications, active magnetic bearings (AMBs) have great potential to improve efficiency, reduce costs, and enhance product quality, due to its high force capacity, high speed capability, and ability to monitor states and employ active controls. This paper describes structure, rotor dynamic modeling and control of a milling spindle with AMBs. The rotor dynamic model is created using FEM according to the Timoshenko beam theory. Before applying the spindle to suppress milling chatter, we develop an μ-synthesis design framework to stabilize the unload system considering the uncertainty in spindle speed. Balance truncation procedure is implemented for the controller order reduction. Finally, a 15th order controller which ensures performance requirements and robust stability, is obtained. The spindle with the controller has speed range of 0–40000 rpm.