Studies on Coil-less Reluctance Force Actuators

Flux control in magnetic actuators can be achieved by additional field superposition or flux path ma-nipulation. Usually, coils are used for external flux control, but inductance lags and ohmic losses degrade actuator effi-ciency. To design energy-efficient reluctance force actuators innovative concepts for controlling the magnetic flux without coils are investigated. On the one hand, this contribution deals with variable reluctance elements based on the in-verse magnetostrictive effect. On the other, magnetic flux is redirected in the magnetic circuit by means of small displacements of reluctance switch elements. For high ma-nipulation rates these elements feature cog-slot structures. Some general design rules are outlined and two examples of application are presented. An active magnetic bearing and a bidirectional actuator are simulated and compared to a bipolar electromagnetic actuator. Finally, all results show the capability of coil-less reluctance force actuators to outperform present electromagnetic systems in terms of bandwidth and energy balance.