GB1295441A - - Google Patents

Abstract

1295441 Automatic voltage control JOSEPH LUCAS (INDUSTRIES) Ltd 17 March 1970 [31 March 1969] 16674/69 Addition to 1239766 Heading G3R [Also in Division H2] The battery charging system described in parent Specification is modified in that:- (1) the alternator is of single phase, wound field type and the voltage regulator controls the current in the field winding instead of thyristors in the output rectifier. The latter can thus be composed entirely of diodes. or (2) the alternator 8 is of multi-phase permanent magnet type and the warning lamp 31 is held off only by the switching action of the regulator 16. The latter may take the form of an oscillator controlled by a Zener diode responsive to the battery voltage and controlling thyristors 10 in the output rectifier. When the battery voltage exceeds a predetermined value, the Zener diode conducts to stop the oscillator and cause the thyristors 10 to turn off when they are next reversebiassed by the alternator. The lamp 31 is illuminated when the alternator is not producing an output and when the alternator is charging the battery continuously due to the voltage between lines 14,15 being below the predetermined value. In the latter condition the amplitude of the ripple voltage across the lines 14,15 is insufficient to turn off the transistor 19 and hence the lamp 31. When the regulator starts operating however, the amplitude of the ripple voltage increases and the transistor 29 is held off permanently by virtue of the control of the transistors 19, 26 by the respective capacitors 21, 24. The operation of the circuit to maintain the lamp 31 off is explained. If the voltage between the lines 14, 15 rises above a predetermined value set by a Zener diode 33, the latter conducts to turn on the transistor 29 and hence the lamp 31 irrespective of the aforementioned operation of the circuit.