Voltage regulators for use in battery charging systems

Claim 2

A voltage regulator for use in a battery charging system on a road vehicle, comprising in combination first and second supply lines for connection to the vehicle battery, a first resistor, a Zener diode and a second resistor connected in series between said supply lines, said Zener diode having a positive temperature coefficient, a third resistor connected across the series combination of the Zener diode and second resistor, an input transistor having its base-emitter circuit connected across said second resistor, the base-emitter circuit of said input transistor having a negative temperature coefficient substantially less than the positive temperature coefficient of said Zener diode, control means coupled to the collector of said input transistor for controlling charging of said battery in accordance with the conduction of said input transistor, and said negative temperature coefficient of said base-emitter circuit of the input transistor being multiplied by a factor dependent on the ratio of the resistance values of said first resistor and said second resistor, whereby said negative temperature coefficient is at least equal to the positive temperature coefficient of the Zener diode.

Claim 3

A battery charging system for a road vehicle, comprising in combination a battery, a generator incorporating a field winding, means coupling said generator to said battery whereby said generator charges said battery, a first resistor, a Zener diode and a second resistor connected in series across said battery, a third resistor connected across the series combination of said Zener diode and said second resistor, an input transistor having a base, a collector and an emitter, means connecting said base and emitter across said second resistor, an output transistor having said field winding in its collector circuit, means coupling the input transistor to the output transistor whereby conduction of the input transistor controls conduction of the output transistor, a positive feedback circuit between the output and input transistors whereby the circuit oscillates between one state with the output transistor fully on and the input transistor fully off, and another state with the output transistor off and the input transistor fully on, the periods of conduction of the input and output transistors being determined by the current flow through said Zener diode, the base-emitter of said input transistor having a negative temperature coefficient and said Zener diode having a positive temperature coefficient which is substantially greater than the negative temperature coefficient of the base-emitter of said input transistor, and said first resistor having a substantially larger resistance than said second resistor, whereby the effective negative temperature coefficient of said base-emitter is increased by a factor determined by the ratio of the first and second resistors to a value at least equal to the positive temperature coefficient of said Zener diode.

Claim 4

A battery charging system for a road vehicle, comprising in combination a battery, a generator incorporating a field winding, means coupling said generator to said battery whereby said generator charges said battery, a first resistor, a Zener diode and a second resistor connected in series across said battery, a third resistor connected across the series combination of said Zener diode and said second resistor, an input transistor having a base, a collector and an emitter, means connecting said base and emitter across said second resistor, an output transistor having said field winding in its collector circuit, means coupling the input transistor to the output transistor whereby conduction of the input transistor controls conduction of the output transistor, a positive feedback circuit between the output and input transistors whereby the circuit oscillates between one state with the output transistor fully on and the input transistor fully off, and another state with the output transistor off and the input transistor fully on, the periods of conduction of the input and output transistors being determined by the current flow through said Zener diode, the base-emitter of said input transistor having a negative temperature coefficient and said Zener diode having a positive temperature coefficient which is substantially greater than the negative temperature coefficient of the base-emitter of said input transistor, and said first resistor having a substantially larger resistance than said second resistor, whereby the effective negative temperature coefficient of said base-emitter is increased by a factor determined by the ratio of the first and second resistors to a value at least equal to the positive temperature coefficient of said Zener diode.

Claim 5

A battery charging system for a road vehicle, comprising in combination a battery, a generator incorporating a field winding, means coupling said generator to said battery whereby said generator charges said battery, a first resistor, a Zener diode and a second resistor connected in series across said battery, a third resistor connected across the series combination of said Zener diode and said second resistor, an input transistor having a base, a collector and an emitter, means connecting said base and emitter across said second resistor, an output transistor having said field winding in its collector circuit, means coupling the input transistor to the output transistor whereby conduction of the input transistor controls conduction of the output transistor, a positive feedback circuit between the output and input transistors whereby the circuit oscillates between one state with the output transistor fully on and the input transistor fully off, and another state with the output transistor off and the input transistor fully on, the periods of conduction of the input and output transistors being determined by the current flow through said Zener diode, the base-emitter of said input transistor having a negative temperature coefficient and said Zener diode having a positive temperature coefficient which is substantially greater than the negative temperature coefficient of the base-emitter of said input transistor, and said first resistor having a substantially larger resistance than said second resistor, whereby the effective negative temperature coefficient of said base-emitter is increased by a factor determined by the ratio of the first and second resistors to a value at least equal to the positive temperature coefficient of said Zener diode, the system further including a fourth resistor and a second Zener diode connected in series across the series combination of said first resistor and first Zener diode, the ratio of said first resistor to said second resistor being chosen so that until a predetermined temperature is reached the overall circuit has a zero temperature coefficient, but said second Zener diode conducting at said predetermined temperature and the ratio of said fourth resistor to said second resistor being chosen so that above said predetermined temperature the overall circuit has a negative temperature coefficient.

Claim 6

A battery charging system for a road vehicle, comprising in combination a battery, a generator incorporating a field winding, means coupling said generator to said battery whereby said generator charges said battery, a first resistor, a Zener diode and a second resistor connected in series across said battery, a third resistor connected across the series combination of said Zener diode and said second resistor, an input transistor having a base, a collector and an emitter, means connecting said base and emitter across said second resistor, an output transistor having said field winding in its collector circuit, means coupling the input transistor to the output transistor whereby conduction of the input transistor controls conduction of the output transistor, a positive feedback circuit between the output and input transistors whereby the circuit oscillates between one state with the output transistor fully on and the input transistor fully off, and another state with the output transistor off and the input transistor fully on, the periods of conduction of the input and output transistors being determined by the current flow through said Zener diode, the base-emitter of said input transistor having a negative temperature coefficient and said Zener diode having a positive temperature coefficient which is substantially greater than the negative temperature coefficient of the base-emitter of said input transistor, and said first resistor having a substantially larger resistance than said second resistor, whereby the effective negative temperature coefficient of said base-emitter is increased by a factor determined by the ratio of the first and second resistors to a value at least equal to the positive temperature coefficient of said Zener diode, the system further including a fourth resistor and a second Zener diode connected in series across the series combination of said first resistor and first Zener diode, the ratio of said first resistor to said second resistor being chosen so that until a predetermined temperature is reached the overall circuit has a zero temperature coefficient, but said second Zener diode conducting at said predetermined temperature and the ratio of said fourth resistor to said second resistor being chosen so that above said predetermined temperature the overall circuit has a negative temperature coefficient.

Claim 7

A battery charging system for use in a road vehicle, comprising in combination first and second supply lines, a battery having its positive terminal connected to the first supply line and its negative terminal connected to the second supply line, an alternator, a full wave rectifier connected to the alternator and supplying power to the first and second supplY lines, a third supply line, means connecting said third supply line to said first supply line through a warning lamp and an ignition switch of the vehicle in series, a plurality of diodes connected to the phase points of said alternator and supplying power to said third supply line, whereby when the alternator is operating the potential of said third supply line is equal to the potential of said first supply line so that said warning lamp is extinguished, a series circuit connected between said first and second supply lines and including a first resistor, a Zener diode and a second resistor, a third resistor connected across the series combination of said Zener diode and said second resistor, an input transistor having its base connected to the junction of the Zener diode and second resistor and its emitter connected to the second line, a fourth resistor coupling the collector of said input transistor to said third supply line, a second transistor having its base connected to the collector of the input transistor, its collector connected through a fifth resistor to the third supply line and its emitter connected to the base of an output transistor, said output transistor having its emitter connected to the second supply line and its collector connected to the third supply line through a field winding of said alternator, a diode bridging said field winding, said diode conducting energy stored in said field winding when said output transistor is off, and a positive feedback circuit coupling the collector of said output transistor to the base of said input transistor, the circuit incorporating the input transistor, second transistor and output transistor oscillating by virtue of said positive feedback circuit to establish a mean current flow in said field winding, said mean current flow depending on the current flow through said Zener diode, which depends on the voltage between the first and second supply lines, the base-emitter of said input transistor having a negative temperature coefficient, and said Zener diode having a positive temperature coefficient, and said first resistor being substantially greater in magnitude than said second resistor whereby the negative temperature coefficient of said base-emitter is multiplied by a factor determined by the ratio of the values of the first and second resistors, to a value at least equal to the positive temperature coefficient of said Zener diode.

Claim 8

A battery charging system for use in a road vehicle, comprising in combination first and second supply lines, a battery having its positive terminal connected to the first supply line and its negative terminal connected to the second supply line, an alternator, a full wave rectifier connected to the alternator and supplying power to the first and second supplY lines, a third supply line, means connecting said third supply line to said first supply line through a warning lamp and an ignition switch of the vehicle in series, a plurality of diodes connected to the phase points of said alternator and supplying power to said third supply line, whereby when the alternator is operating the potential of said third supply line is equal to the potential of said first supply line so that said warning lamp is extinguished, a series circuit connected between said first and second supply lines and including a first resistor, a Zener diode and a second resistor, a third resistor connected across the series combination of said Zener diode and said second resistor, an input transistor having its base connected to the junction of the Zener diode and second resistor and its emitter connected to the second line, a fourth resistor coupling the collector of said input transistor to said third supply line, a second transistor having its base connected to the collector of the input transistor, its collector connected through a fifth resistor to the third supply line and its emitter connected to the base of an output transistor, said output transistor having its emitter connected to the second supply line and its collector connected to the third supply line through a field winding of said alternator, a diode bridging said field winding, said diode conducting energy stored in said field winding when said output transistor is off, and a positive feedback circuit coupling the collector of said output transistor to the base of said input transistor, the circuit incorporating the input transistor, second transistor and output transistor oscillating by virtue of said positive feedback circuit to establish a mean current flow in said field winding, said mean current flow depending on the current flow through said Zener diode, which depends on the voltage between the first and second supply lines, the base-emitter of said input transistor having a negative temperature coefficient, and said Zener diode having a positive temperature coefficient, and said first resistor being substantially greater in magnitude than said second resistor whereby the negative temperature coefficient of said base-emitter is multiplied by a factor determined by the ratio of the values of the first and second resistors, to a value at least equal to the positive temperature coefficient of said Zener diode.