ac powered, thyristor-switched electric motors having superconducting fields

Patent · Tue Sep 30 04:00:00 EDT 1975

OSTI ID:5377281

Smith, Jr, J L

An electric motor using thyristor switches to allow connection to an ac supply voltage is described. The thyristor switching is accomplished in part, by the use of a sensor which notes and uses relative positions of the magnetic fields of the armature and of the field to change the gate voltage applied to the thyristor and, in part, by the ac system voltage that serves to bias the thyristor. Switching is timed to cause the armature magnetic axis to lead the field magnetic axis by about 90 electrical degrees, thereby providing a motor that operates from an ac line yet exhibits the speed-control characteristics of a separately excited dc motor. The concept disclosed in particular is useful in connection with superconducting machines that, because of size, are not ordinarily considered to be operable in the dc mode.

• Assignee: Massachusetts Inst. of Tech.
• Patent Number(s): US 3909684
• OSTI ID: 5377281
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALTERNATING CURRENT
ARMATURES
CONTROL EQUIPMENT
CURRENTS
DESIGN
ELECTRIC CURRENTS
ELECTRIC MOTORS
ELECTRONIC CIRCUITS
GATING CIRCUITS
MAGNETIC FIELDS
MOTORS
SEMICONDUCTOR DEVICES
SPEED REGULATORS
SUPERCONDUCTING DEVICES
SUPERCONDUCTING MOTORS
SWITCHING CIRCUITS
THYRISTORS