Generator voltage regulator

• US 4,629,967 A
• Filed: 04/29/1985
• Issued: 12/16/1986
• Est. Priority Date: 04/29/1985
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Voss, Richard J.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Simpson, Mark D.
• Application Number:
  US06/727,557
• Time in Patent Office: 596 Days
• Field of Search: 322/17, 322/28, 322/33, 322/34, 320/35, 320/36, 320/39, 320/40, 320/64
• US Class Current: 322/28
• CPC Class Codes: H02J 7/007192 in response to temperature
• CPC Class Codes: H02J 7/16 Regulation of the charging current or voltage by variation of field

Abstract

A voltage regulating system for a diode-rectified alternating current generator that supplies the electrical loads on a motor vehicle including charging the storage battery. The voltage regulator has a reference voltage developing circuit that can operate either in a temperature compensated mode or a flat mode. In the temperature compensated mode the reference voltage developed by the circuit varies with temperature and while the circuit is in the flat mode the reference voltage remains substantially constant with changes in temperature. The voltage regulator has a switching transistor connected in series with the field winding of the generator which can operate in a current limiting mode in the event that sensed field current becomes excessive. The voltage regulator includes circuitry for ensuring that the output voltage of the generator properly builds-up when the field winding is initially excited by the battery.

Claims

1. A reference voltage developing circuit for a voltage regulator for providing a voltage at a junction of said circuit comprising, first and second conductors adapted to be connected across a voltage source, a first circuit connected across said conductors comprising in a series connection a first resistor, a junction connected to said first resistor and a transistor having its collector-emitter circuit connected between said junction and one of said conductors, the base-emitter circuit of said transistor having a temperature responsive characteristic, a second circuit connected between said junction and said one of said conductors comprising in a series connection a second resistor and the current carrying electrodes of a semiconductor switch, said semiconductor switch being so connected with said transistor as to bias said transistor nonconductive while simultaneously connecting said first and second resistors across said conductors when said semiconductor switch is biased conductive whereby when said semiconductor switch is biased conductive the voltage developed at said junction does not vary substantially with changes in temperature of said circuit, said transistor being so connected with said semiconductor switch as to enable said transistor to conduct when said semiconductor switch is biased nonconductive whereby the voltage at said junction varies with changes in temperature of said transistor, said semiconductor switch having a control electrode which is adapted to be controlled so as to selectively cause said semiconductor switch to be biased either conductive or nonconductive.

2. A voltage regulating system for a generator that has a field winding and an output winding that supplies charging voltage to a storage battery comprising, means connecting said output winding and said battery, a first semiconductor switch connected with said field winding and output winding for controlling field current, a voltage sensing circuit connected across said battery having a first junction for developing a battery voltage at said first junction that varies with the voltage across the battery, a reference voltage developing circuit having a second junction connected with said output winding for developing a reference voltage at said second junction, voltage comparator means connected to said junctions for biasing said first semiconductor switch conductive when said reference voltage exceeds said battery voltage and nonconductive when battery voltage exceeds the reference voltage, said reference voltage developing circuit comprising a second semiconductor switch, a transistor having a base-emitter circuit which has a temperature responsive characteristic and voltage divider circuit elements that are so connected to each other and to said second semiconductor switch as to provide a temperature compensated mode of operation wherein the voltage of said second junction varies with temperature or a flat compensated mode of operation wherein the voltage at said second junction does not vary substantially with changes in temperature, said mode of operation being dependent upon the conductive or nonconductive state of said second semiconductor switch, said transistor being biased nonconductive when said regulator is in said flat compensated mode and being biased conductive when the regulator is in the temperature compensated mode, the conductive or nonconductive state of said second semiconductor switch being controlled by whether or not a conductor connected to the control electrode of said second semiconductor switch is connected to or disconnected from said output winding, said reference voltage developing circuit being connected to said output winding while said regulator is in either said temperature compensated mode or said flat compensated mode.

3. A reference voltage developing circuit for a voltage regulator for providing a voltage at a junction of said circuit comprising, first and second conductors adapted to be connected across a voltage source, a first circuit connected across said conductors comprising in a series connection a first resistor, said junction and the collector and emitter electrodes of a first transistor, a second circuit connected between said junction and one of said conductors comprising in a series connection a second resistor and the collector and emitter electrodes of a second transistor, the collector-emitter circuit of said second transistor connected across the base and emitter of said first transistor whereby when said second transistor is biased conductive said first transistor is biased nonconductive and said first and second resistors are connected across said conductors to develop a voltage at said junction that does not vary substantially with changes in temperature, and whereby said first transistor is biased conductive when said second transistor is biased nonconductive to thereby cause the voltage at said junction to vary with temperature due to the temperature responsive characteristic of the base emitter circuit of said first transistor.

4. A reference voltage developing circuit for a voltage regulator for providing a voltage at a junction of said circuit comprising, first and second conductors adapted to be connected across a voltage source, a first circuit connected across said conductors comprising in a series connection a first resistor, said junction, a second resistor and the collector and emitter electrodes of a first NPN transistor, a second NPN transistor having a collector connected to the base of said first transistor and an emitter connected to the emitter of said first transistor, a third resistor connected between said junction and the connection of the collector of said second transistor and the base of said first transistor, a fourth resistor connected across the base and emitter of said first transistor and across the collector and emitter of said second transistor, said second transistor when biased conductive biasing said first transistor nonconductive and connecting said first and third resistors across said conductors whereby the voltage at said junction does not vary substantially with changes in temperature, said first transistor being biased conductive when said second transistor is biased nonconductive and operative to cause the voltage at said junction to vary with changes in temperature over a predetermined temperature range due to the temperature dependent characteristic of the base-emitter circuit of said first transistor.

5. The reference voltage developing circuit according to claim 4 wherein said first transistor is biased into saturation at some predetermined high temperature and is biased to cut-off at some predetermined low temperature whereby at temperatures above said high temperature the voltage of said junction has a constant low value and at temperatures below said low temperature the voltage at said junction has a constant high value.

6. A voltage regulating system for a motor vehicle battery charging generator comprising, an alternating current generator having an output winding and a field winding, rectifier means connected to said output winding having direct voltage output terminals, a battery connected across said output terminals, a circuit for energizing said field winding connected to said output winding comprising a semiconductor switch connected in series with said field winding and a resistor connected in series with said field winding and semiconductor switch, a voltage sensing circuit connected across said battery for sensing the voltage across said battery, means connected to said sensing circuit and responsive to the voltage across said battery for biasing said semiconductor switch fully conductive when the voltage across the battery is below a regulated value and biasing said semiconductor switch fully nonconductive when the voltage across the battery is above the regulated value, means responsive to a disconnection of said sensing circuit from said battery for biasing said semiconductor switch continuously fully nonconductive, and means operative in response to the voltage developed across said resistor exceeding a predetermined value indicative of excessive field current for biasing said semiconductor switch such that the conduction of said switch is reduced from its fully conductive condition to a current limit value.

7. A voltage regulating system for an alternating current generator that supplies the electrical loads on a motor vehicle including charging the storage battery comprising, an alternating current generator having an output winding and a field winding, rectifier means connected to said output winding having direct voltage output terminals connected to said battery, a field circuit for energizing said field winding connected to said output winding including a semiconductor switch connected in series with said field winding that is biased conductive and nonconductive, a voltage dividing circuit connected across said battery having a battery voltage junction that has a voltage that is a function of battery voltage, a reference voltage generating circuit comprising a reference voltage divider having a reference voltage junction that develops a reference voltage that is a function of the voltage applied to said reference voltage divider, a voltage comparator connected to said junctions for biasing said semiconductor switch fully conductive when the voltage of said battery junction is below the voltage of said reference junction and biasing said semiconductor switch nonconductive when the voltage of said battery junction is higher than the voltage of said reference voltage junction, means connecting said output winding to a conductor means that feeds said voltage reference generating circuit, said conductor means being connected to said field winding to energize said field winding from said conductor means when said semiconductor switch is biased conductive, a circuit for initially exciting said field winding from said battery to cause generator voltage build-up comprising a manually operable switch and resistor means connected in series between said battery and said conductor means, said switch when initially closed causing a voltage to be applied to said conductor means through said resistor means that is of such a value that the voltage at said battery voltage junction is higher than the voltage at said reference voltage junction, and means operative when the output voltage of said generator is building up and is below a predetermined value for preventing the higher voltage at said battery voltage junction relative to said reference voltage junction from biasing said semiconductor switch nonconductive.

8. A voltage regulating system for a motor vehicle battery charging generator comprising, an alternating current generator having an output winding and a field winding, rectifier means connected to said output winding having direct voltage output terminals, a battery connected across said output terminals, a circuit for energizing said field winding connected to said output winding comprising a semiconductor switch connected in series with said field winding and a resistor connected in series with said field winding and semiconductor switch, a voltage sensing circuit connected across said battery for sensing the voltage across said battery, means connected to said sensing circuit and responsive to the voltage across said battery for biasing said semiconductor switch fully conductive when the voltage across the battery is below a regulated value and biasing said semiconductor switch fully nonconductive when the voltage across the battery is above the regulated value, and means operative in response to the voltage developed across said resistor exceeding a predetermined value indicative of excessive field current for biasing said semiconductor switch such that the conduction of said switch is reduced from its fully conductive condition to a current limit value, said last-named means comprising a voltage multiplier that has a transistor, the temperature response of said transistor being similar to the negative temperature coefficient characteristic of the current flowing through said field coil.