Active Compensation of the Eigen-Dynamics of Electromagnetic Actuators by ECU-Based Non-linear Feedback Control

Increasing demands on the dynamic behaviour of in- dustrial machines lead to a rising use of active el- ements for an active optimization of the dynamic properties of those systems. Especially in mechan- ical engineering applications electromagnetic actua- tors with a unidirectional motion are often the most suitable ones. For the use of those actuator types in industrial systems a linear dependence of the actuator-force on the control current and an inde- pendence of the force from the displacement of the pull-disk in the magnetic field are most desirable. In this paper, investigations are presented of an electromagnetic actuator with high level permanent- magnets to realize the bias- ux. But besides many advantages, the use of high level permanent-magnets also leads to a high instability and a poor controlla- bility of the system over the entire operating range. By the use of an electronic-control-unit (ECU)-based non-linear feedback control the negative stiffness of the system could be eliminated and the non-linear de- pendence of the actuator-force on the control current could be linearized. Above that, the actuator dynam- ics have been compensated by an active compensation of the inertia forces. Thus, in order to further de- velop the actuator towards a compact machine tool for an easy integration into mechanical systems, an electromagnetic actuator has been realized that can be handled with classical linear control concepts.