GB1199301A - Electronically Phase Locked Motor - Google Patents

Abstract

1199301 Automatic speed-control BUNKER-RAMO CORP 28 July 1967 [28 July 1966] 34908/67 Headings G3T and TA5T [Also in Division H2] A constant-speed motor comprises rotatable magnets 18, 20, associated with a sensing coil 22 and a driving coil 24 which is energized from pulse generator 28. A transistor 26, in series with the driving coil, is controlled by signals from the coil 22 responsive to rotation of the magnet 18 so that the driving coil is energized when a pulse from the generator 28 coincides with a conductive period of the transistor. If the speed of shaft 10 tends to change due to a variation of loading, the pulse from coil 22 slips in phase, resulting in a greater or lesser effective duration of the pulse which is applied to the coil 24 whereby the speed is restored to a value which depends solely upon the frequency of the generator 28. Since the magnets 18, 20 are mutually normal there is no interaction between magnet 20 and coil 22 or between magnet 18 and coil 24. In a modification, the non- magnetic disc 16 carries a plurality of vertical permanent magnets around its periphery, these magnets having their poles arranged in the same direction. A first transistor has its collector connected to the pulse generator and its base and emitter are connected to the sensing coil. A second transistor has its emitter connected to the pulse generator, its base to the emitter of the first transistor, and its collector connected through the driving coil to a D.C. source.