Frequency-dependency of force dynamics in hybrid reluctance actuators

Abstract

In this paper, the dynamics of hybrid reluctance actuators (HRAs) are investigated by conducting dynamic force measurements on two HRAs, one with a laminated core and one with a solid core. The performance of current-controlled HRAs is limited by a frequencydependent force-to-current relationship (FCR), which leads to a higher current demand for a constant force generation at higher frequencies due to eddy current diffusion in the stator yoke. The FCR is further depending on the amplitude of the driving signal due to hysteresis. Flux feedback control on the other hand can realise a largely frequency-independent force-to-flux relationship (FFR) up to 1 kHz for both a solid and a laminated core actuator. The force dynamics are evaluated in the frequency domain and the power consumption for positioning applications is compared for a current-controlled layered core and a flux-controlled solid core HRA, showing an increased power consumption by a factor of six in the latter case.