Ripple-compensated voltage regulator, particularly for automotive use

Claim 1

Ripple-compensated voltage regulator circuit for connection to and in combination with an electrical generator, especially an AC generator, having a field winding, for the on-board electrical supply in motor vehicles, ships, and the like, having a main switching circuit including a semiconductor switch (8, 9) serially connected with the field or exciter winding (6) of the generator; a control transistor (10) having its main switching path connected to the control terminal of the semiconductor switch, and to the output of the generator; a voltage divider (13, 14, 15) connected across the output of the generator; a Zener diode (16) connected to a junction of the voltage divider and to the base of the control transistor (10) to provide for conduction of the control transistor when the generator voltage exceeds the nominal or set-point voltage defined by the Zener diode (16) and thus switches the semiconductor switch (8, 9) of the regulator into non-conducting state, thereby blocking current flow through the exciter or field winding (6), said control transistor becoming blocked or non-conducting whenever the generator voltage drops below the nominal set-point voltage defined by the Zener diode (16) to permit the semiconductor switch (8, 9) of the regulator to become conductive and permit current flow through the exciter or field winding (6); and further comprising a compensation circuit (20) including an active semiconductor switch (25) connected as an inverter, controlled by the undulating portion of the voltage supplied by the generator, and supplying a compensation voltage (II) of opposite phase to the undulating portion of the voltage supplied by the generator to a tap point of said voltage divider, whereby the Zener diode will receive a control voltage unaffected by generator ripple.