CAT-1 (China Astro-Torus 1) is a levitated dipole field magnetic confinement device, which mainly used for dipole plasma physics experiments, requiring a central floating superconducting coil to be stably levitated for at least 5 h without cooling or power supply.

This study aims to design a levitation control system of coupling superconducting levitation coil and floating coil for CAT-1 dipole device.

According to the design parameters of the suspension magnet system of the CAT-1 device, Simulink model of the control system was established and applied to the simulation. Based on Routh-Hurwitz stability criterion, the influence of PID (Proportion-Integral-Derivative) control strategy on stability control was studied. The selection range of stability control parameters was determined to ensure the stable levitation of 1 200 kg, 5 MA floating magnet.

Simulation results show that under ideal conditions, delay time of the PD (Proportion-Derivative) control system is 0.046 3 s, rise time is 0.154 5 s, peak time is 0.628 3 s, adjustment time is 0.084 8 s, and overshot δ=1.6. It means that PD can restore the levitated superconducting ring to the preset balance position in a short time, and the load of the circuit can be greatly reduced by adopting the appropriate starting mode.

The results provide key technical support for the design and development of levitated superconducting dipole field devices.