Structural design of a superconductive actuator

Superconductivity is promising to improve the acceleration for future actuators. High mechanical stiffness is required to transmit the highly dynamic forces. However, an extremely efficient thermal insulation is required to achieve stable low temperatures (<90K). These arguments form the basis of the research.

PhD Candidate: ir. Bart Koolmees
Supervisor: dr.ir. P.C.J.N. Rosielle
Promotor: prof.dr.ir. J.P.M.B. Vermeulen, prof.dr.ir. M. Steinbuch
Project Period: January 2016 – January 2020

The required acceleration of motion systems is an important design driver. The application of superconductivity is investigated to increase the acceleration by generating higher magnetic fields compared to current actuators.

A superconductor is a material which has exactly zero resistivity below the critical temperature (Tc), critical current density (Jc) and critical magnetic field density (Bc). The temperature dependent resistivity is shown in Figure 1 and the measured critical surface of YBaCuO is shown in Figure 2. The low temperatures require a thermally efficient construction due to low cooling efficiency at large temperature difference (Carnot).

The highly dynamic motion profile of industrial motion systems requires a mechanically stiff construction to allow for a high control bandwidth. The contradiction of high mechanical stiffness with efficient thermal insulation is part of the research in this PhD project. Furthermore, the mechanical fixation of coils of superconductive material is challenging due to thermal contraction between assembly (~300K) and operation (<100K). Finally, the electromagnetic actuator requires a small airgap to make use of the magnetic field strength which requires a thin thermal insulation. The goal is to resolve the challenges given above and realize a demonstrator as a proof of principle.