GB492644A - Improvements in and relating to electric motors - Google Patents

Abstract

492,644. A.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd. July 22, 1937, No. 16299/38. Convention date, July 22, 1936. Divided out of 490,708. [Class 35] The stator of a synchronous motor comprises permanent magnets and laminated segments each carrying two salient poles arranged alternately, the two poles of a segment being similarly magnetized by the magnets but oppositely by windings energized with alternating current, the windings on adjacent pairs of poles being phase displaced and the teeth on the salient poles not being simultaneously in alignment with the rotor teeth which, however, have the same pitch. In the form shown, the stator has eight toothed salient poles with the windings on poles 1, 2, 5, 6 in series with a condenser 9 and the windings on poles 3, 4, 7, 8 series connected across the supply, and although the teeth on all poles are equally spaced, the teeth on poles not of the same phase and polarity due to their winding are staggered by a fraction of a toothed pitch. The stator has four laminated segments separated by four permanent magnets 30 so arranged that both poles on any one segment are similarly magnetized, but due to the windings the poles on any one segment are oppositely magnetized. The dotted lines 35 indicate the path of the permanent magnet flux. The motor is selfstarting. Specifications 424,746, [Group II], and 490,708 are referred to.