PURPOSE: To facilitate starting of a rotary induction machine, by employing a closed circuit comprising superconductors and a cooling means therefor as the secondary winding of the rotary induction machine.
CONSTITUTION: A secondary winding 2 comprising cage superconductors is placed on a rotor 1, while an armature winding 3 is placed on a stator 4. The winding 2 is provided with a cooling means which employs fluid refrigerant in gap or fluid flowing in the conductor. Upon supplying commercial power source onto the armature winding 3, the secondary winding 2 on the static rotor receives alternating flux of commercial frequency, and AC loss and AC resistance appear in the secondary winding 2 thus producing starting torque. It is controlled such that the cooling means for the superconductors is functioned sufficiently when a predetermined speed is achieved so as to lower the temperature below the critical temperature of the superconductor. At the time point when the temperature drops below the critical temperature, the secondary winding 2 functions as a field winding of persistent current.
MAKI NAOKI
TOMEOKU HIROSHI
YAMAMOTO HIROE
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