Dynamic electromechanical coupling resulting from the air-gap fluctuation of the linear motor in machine tools

摘要

This paper investigates a dynamic electromechanical coupling resulting from the air-gap fluctuation of the linear motor in machine tools. The modes of the mechanical vibration are analyzed firstly in the linear motor feed system. Then the influence of mechanical vibration on the air-gap fluctuation is researched. Based on the Maxwell's equation and energy method, the analytical expression of the motor thrust is established considering the air-gap fluctuation. Then we discuss the effects of air-gap fluctuation on the motor thrust. At last, the dynamic electromechanical coupling caused by the air-gap fluctuation is theoretically analyzed and verified by experiments. The results show that the mechanical vibration can affect the characteristics of the motor thrust conversely causing the fluctuation of the motor air-gap. The air-gap fluctuation can produce new thrust harmonics. These new thrust harmonics excite mechanical system again, and then the electromechanical coupling loop is formed, leading to a worse dynamic precision of the feed system. In addition, the couplings will aggravate with the increase of velocity and load. (C) 2015 Elsevier Ltd. All rights reserved.