Automotive battery charging system
First Claim
1. An automotive battery charging system comprising a generator having a field winding and output terminals connected to the battery and a voltage regulator controlling the field current, said voltage regulator including a battery voltage sensitive input stage coupled to an output stage which is in series with the field winding, said input stage including first and second resistors in series across the battery, the voltage at the junction of said resistors determining whether the output stage is conductive, or not, and a temperature compensation circuit for varying the voltage at said junction independently of the battery voltage and including a first transistor having its collector-emitter path in series with a third resistor across said second resistor and a temperature sensing circuit controlling the base voltage of said transistor so as to reduce such voltage substantially linearly with increasing temperature up to a predetermined upper temperature at which said output transistor ceases to conduct, the first and third resistors being adjusted to determine the height and slope of the temperature characteristics of the regulator.
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Accused Products
Abstract
An automotive battery charging system includes a novel temperature compensation arrangement. The conventional input potential divider has a further resistor and a temperature compensation output transistor in series across one leg of the divider. The voltage at the base of the temperature compensation output transistor is controlled by a temperature sensing circuit so as to fall linearly with rising temperature. Resistors are adjusted in manufacture to give the required level and slope for the temperature compensation characteristic.
23 Citations
16 Claims
- 1. An automotive battery charging system comprising a generator having a field winding and output terminals connected to the battery and a voltage regulator controlling the field current, said voltage regulator including a battery voltage sensitive input stage coupled to an output stage which is in series with the field winding, said input stage including first and second resistors in series across the battery, the voltage at the junction of said resistors determining whether the output stage is conductive, or not, and a temperature compensation circuit for varying the voltage at said junction independently of the battery voltage and including a first transistor having its collector-emitter path in series with a third resistor across said second resistor and a temperature sensing circuit controlling the base voltage of said transistor so as to reduce such voltage substantially linearly with increasing temperature up to a predetermined upper temperature at which said output transistor ceases to conduct, the first and third resistors being adjusted to determine the height and slope of the temperature characteristics of the regulator.
Specification