GB1066572A - Improvements in Regulators for Generators - Google Patents

Abstract

1,066,572. Automatic voltage control. ROBERT BOSCH G.m.b.H. July 14, 1964 [July 20, 1963], No.29436/64. Heading G3R. A voltage regulator for a generator 10, which may be an alternator with a rectified output, comprises a main transistor 21 in series with the field winding 19 of the generator; a control transistor 22 which has its base connected by way of a Zener diode 23 to the tap 24 of a potentiometer 25 connected across the generator output and which is arranged to switch transistor 21 by way of an amplifying transistor 28, and hence to control the field current, in dependence upon output voltage variations; and a transistor 35 arranged to block transistors 21 and 28 and thereby protect them against overload should the field current become excessive due to a short circuit in the field winding. Transistor 35 has its collector connected to the collector of transistor 22, and has its base connected over a resistor 36 to a resistor 31 in the emitter lead of transistor 21 and over a capacitor 37 and a resistor 38 to the collector of transistor 21. Positive feedback through the circuit 37, 38 ensures that transistor 35 is quickly rendered conductive to block transistors 21, 28 when the potential drop across resistor 31 exceeds a predetermined value representative of an excessive field current.