Search

A permanent-magnet synchronous motor with high-Tc superconducting (HTS) armature operated at sub-cooled liquid nitrogen temperature has been designed. The prototype model has a ten-pole rotor and twelve sets of armature windings which are fabricated with BSCCO tapes, and its output power is 400 kW at the rated speed of 250 rpm. In order to decrease the AC loss of HTS coils to an appropriate level, the conventional stator iron cores are adopted. The coil design, behaviors of HTS conductors, even cooling system design will be proved in the armature case. And the prediction of AC loss in stacked tape conductor exposed to external magnetic fields with various directions have been carried out using FEA method. Based on the 3D magnetic field finite element analyses, this paper presents an AC loss analysis method for the armature winding and provides upper the limit of operating temperature for the cooling system. [ABSTRACT FROM AUTHOR]

The technique of subdivision protection is extensively applied to protect large superconducting solenoid magnets such as accelerator magnets and MRI magnets. The number of subdivision and the parameters of protection circuit are usually decided by the quench simulation results. The accurate current data during quench process is important to verify the quench simulation code and estimate the magnet performance. But not like voltage signal, the acquisition of which just needs to attach a pair of voltage taps on both side of each protection resistor, current signal is very difficult to be obtained from cryogenic environment. This paper presents an algorithm to calculate the quench current from the quench voltage measurement result. By this algorithm the temperature rise history of protection resistor is obtained simultaneously. [ABSTRACT FROM AUTHOR]

A 400kW radial-axial flux type experimental HTS synchronous motor is designed. There are twelve armature coils used HTS wires in the motor. They are accommodated in the cooling vessels made of FRP material, and twelve cooling vessels are enclosed in the vacuum vessel. In order to cool the HTS coils of the motor, a sub-cooled liquid nitrogen cryogenic system is presented. The operation temperature is below 70 K. This system consists of HTS coils cryostats, liquid nitrogen transfer-line, liquid nitrogen dewar and a cold box with liquid nitrogen pump, G-M cryorefrigerators and some control valves inside. In this paper, different kinds of the heat loads of the system including the AC loss, current lead, supporters and radiation are presented. Basis on the heat load and operating temperature, the main parameters and equipments of the system are determined. [ABSTRACT FROM AUTHOR]

This paper presents a power assist lower extremity exoskeleton and a fuzzy sliding mode compensation controller. First, the mechanical design of this exoskeleton and the control configuration are introduced. Second, the dynamics of lower extremity exoskeleton is analyzed and the sliding mode controller with fuzzy compensation algorithm under uncertainties for exoskeleton joints is proposed. The theoretical proof shows that it is globally stable in the sense of Lyapunov. The experiments indicate that the proposed control scheme is effective; not only it ensures the control accuracy but also is robust to external uncertainties compared with PID control. [ABSTRACT FROM AUTHOR]