2018.04.10. Superconducting motor uses solid-state cooling

At the upcoming Hannover Fair, Festo will be demonstrating a superconducting claw-pole motor with solid-state cooling. Details are sketchy, but the company says that the SupraMotor’s technology is characterised by a compact design, a high holding torque and a long-life, coolant-free electrical direct-cooling system.

The drive exploits of thge ability of appropriately cooled superconducting materials to transmit electricity without any losses. This allows a strong magnetic field to be generated using high currents. The SupraMotor has a high overload capacity and is suitable for applications that require continuous operation. The resistance-free superconducting coils mean that it is almost impossible for the motor to overheat as a result of conduction losses.

An exploded view of the motor, released by Festo, shows that, at its heart is a double pancake coil made of superconducting tape, housed in a GRP cryostat – a vacuum chamber that insulates the coils thermally. The extremely low temperatures needs to achieve superconductivity are achieved using a sold-state cooling technology based on the Stirling cycle.

The motor has an external rotor linked to a timing belt, while a claw-shaped stator guides the magnetic flux. An array of permanent magnets is arranged in a ring shape on the rotor.
Festo says that the motor will work particularly efficiently at low speeds with high torques. If a load has to be held, the motor uses no energy even at maximum holding torque. While the motor’s output power is in the double-digit kW range, the energy it needs for cooling is in the low three-digit Watt range, with the coil consuming less than 5W.

The motor can currently be operated only with low phase currents, because the ferromagnetic materials presently available cannot handle higher magnetic flux densities. Festo believes, however, that with further research, new concepts and materials could emerge that could fully exploit the superconductor’s current-carrying capacity of well over 100A.

The superconducting motor is the latest in a series of superconducting applications that Festo has demonstrated in recent years. It has developed the motor in conjunction with the Swiss motor developer SmartDrives, the German superconductor specialist evico, and the Leibniz Institute for Solid State and Materials Research.



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