Abstract Body

High-temperature superconducting induction motors (HTS-IM) have attracted considerable attention due to their near 100% energy efficiency and simple structure. To further advance this technology, we are incorporating an active-type bearingless mechanism into the HTS-IM, which will prevent the rotor from making mechanical contact while maintaining a compact design. This approach will help avoid issues related to mechanical wear and friction. Given that HTS-IMs are fundamentally induction motors, the primary challenge, as highlighted in a research on active-type bearingless mechanism for normal-conducting induction motors[1], lies in the mutual interference between the torque magnetic field and the bearingless magnetic field. To address this challenge, a solution is presented in Fig.1. As shown in Fig.1(a), the rotor will first be redesigned based on a standard HTS-IM. More specifically, as illustrated in Fig.1(b), the HTS rotor bar will be reconfigured as a "pole-specific circuit[2]," which allows only the 4-pole magnetic field to induce current, while the 2-pole magnetic field does not induce any current. This design enables the decoupling of the torque magnetic field from the bearingless magnetic field, allowing them to be independently controlled. Regarding the stator, as shown in Fig.1(c), the dual-purpose no-voltage (DPNV)[3]excitation method will be employed, which only requires minor alterations to the winding coils without the need to modify the stator core. Finally, as shown in Fig.1(d), a control system for the bearingless mechanism will be developed, utilizing magnetic levitation control algorithms such as PID control, sliding mode control, and feedback linearization to stabilize the system.

References

[1] J. Chen, Y. Fujii, M. W. Johnson, A. Farhan and E. L. Severson, "Optimal Design of the Bearingless Induction Motor," IEEE Transactions on Industry Applications, vol. 57, no. 2, pp. 1375-1388, 2021.

[2] A. Chiba, et al. "Magnetic bearings and bearingless drives," Elsevier, 2005.

[3] E. L. Severson, et al. "Design of dual purpose no-voltage combined windings for bearingless motors," IEEE Transactions on Industry Applications, vol. 53, no. 5, pp. 4368-4379, 2017.

Figure 1. Design process of the bearingless system for high-temperature superconducting induction motor

Keywords: Active-type bearingless system, High-temperature superconducting induction motor