GB1138155A - Synchronous motor system - Google Patents

Abstract

1,138,155. Automatic speed control. SANDERS ASSOCIATES Inc. April 13, 1966 [April 26, 1965], ], No. 16230/66. Heading G3R. [Also in Division H2] Rotation of the permanent magnet field units of a synchronous motor induces a speed-responsive signal in generator winding 22 which is applied through amplifier 24 to the armature winding across terminals 62, 64. The motor is given a small initial velocity which is increased by the rise in frequency of the signal from winding 22 until a speed sensor 26 emits a signal to currentcontroller 28 for reducing the current supplied by amplifier 24 to the armature winding. If the motor speed then tends to change, the sensor 26 and controller 28 will return the speed substantially to the desired value. Transistor 48 switches between its conducting and non-conducting states when the voltage from winding 22 passes through zero. When the transistor 48 is cut-off, transistor 72 renders the transistors 50, 56 conductive to energize the armature winding from battery 58. During the next half-cycle, transistor 48 conducts to turn-on transistor 80. The armature winding is then energized through transistors 54, 52. When the voltage from winding 22 reaches a predetermined level, the impedance of tunnel diodes 104, 106, increases to render transistor 102 conductive during negative half-cycles. The current in transistor 112 is reduced and that in transistor 114 is increased to decrease the armature current passing through transistor 60 whereby acceleration of the motor is halted for operation at the desired speed. Small variations of speed about the operating point causes transistor 102 to discharge capacitor 116 occasionally by an amount corresponding to the charge current through resistor 108. The operating speed of the motor is adjusted by emitter resistor 118 which changes the gain of transistor 92. Resistor 100 compensates for temperature changes.