In this paper, according to the induction motor in rotating coordinate system mathematical model, established based on rotor flux oriented vector control model and realized flux linkage and torque decoupling. In order to solve the current high coupling, designed the sliding mode variable structure control algorithm of current controller. Based on the sliding mode variable structure control algorithm achievable conditions and Lyapunov stability theorem, proved that the sliding mode of accessibility and stability, determined the sliding model parameters. The simulation results show that the sliding mode variable structure control of induction motor vector control system, can reduce the torque ripple and the speed overshoot and improve the system parameter perturbation and external disturbance signal robustness.

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The electrical jointing of superconducting wires / tapes is a key issue for the construction of the scientific superconducting magnet that required high field stability, such as NMR, FTICR-MS and some inertial navigators. In this paper, the preliminary experiment of electromagnetic formed NbTi superconducting joint was done. The fabrication technique was researched by changing the parameters. The joint resistances were tested in liquid helium using coil current decay method. The contact resistance properties of the superconducting joint were investigated. The plastic deformation and the electrical contact characteristics of the NbTi superconducting joint were discussed. The results show that the electromagnetic formed NbTi superconducting joint has the excellent low-resistance property and good repeatability.