GB1045287A - Improvements relating to power supply systems - Google Patents

Abstract

1,045,287. Automatic voltage control. ROBERT BOSCH G. m. b. H. Aug. 7, 1963 [Aug. 8, 1962], No. 31084/63. Heading G3R. A voltage regulator for a permanent magnet alternator having a rectified output for connection to a battery comprises a controllable semi-conductor which carries the load current and which is controlled in dependence upon the output voltage. As shown, a three-phase alternator A having a permanent-magnet field F supplies a battery B over rectifiers 13, 14 and 15, a power transistor 16, positive lead 18 and negative lead 17. When the output voltage is below a pre-determined value, e.g. 13V, transistor 16 is conductive by virtue of a base/emitter voltage derived from a voltage divider 23, 24; any increase in this pre-determined value operates a relay 20 connected across the leads 17,18 by a switch 19 which is closed in its operative position, whereby the relay contacts 21, 22 are closed to short circuit the base/emitter path of the transistor 16 which is then cut off. When the battery voltage subsequently drops below a lower limit e.g. 12. 8V, the relay 20 is de-energized and the control cycle starts again. In a modification (Fig. 2, not shown), the switching of the power transistor 16 is effected by a blocking oscillator comprising a feedback transformer and a control transistor responsive to the output voltage. In another embodiment (Fig. 4, not shown), each winding of the three-phase alternator is connected in series with an individual transistor, the three transistors being controlled by a common blocking oscillator.