Circuit to measure vehicle battery voltage

• US 20060132140A1
• Filed: 12/17/2004
• Published: 06/22/2006
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Weber, Charles F.
• Granted Patent: US 7,812,569 B2
• Time in Patent Office: Days
• US Class Current: 324/433
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36

Abstract

A system for measuring a battery voltage is provided. The system includes a battery, a time encoding circuit, and a controller. The time encoding circuit is in electrical communication with the battery to receive the battery voltage. The time encoded circuit is configured to generate a time encoded signal corresponding to the battery voltage. The controller is in electrical communication with the time encoding circuit to receive the time encoded signal and configured to determine the battery voltage based on the time encoded signal.

Claims

1. A system for measuring a battery voltage, the system comprising:

a battery;

a time encoding circuit in electrical communication with the battery to receive the battery voltage, the time encoding circuit generating a time encoded signal corresponding to the battery voltage;

a controller in electrical communication with the time encoding circuit, and the controller being configured to determine the battery voltage based on the time encoded signal.

2. The system according to claim 1, wherein the controller includes a timer configured to receive the time encoded signal.

3. The system according to claim 1, wherein the controller is configured to decode the time encoded signal based on the relationship V_bat=V_ref (t_high+t_low)/t_low where t_high is the amount of time the time encoded signal is high during a switch cycle, and t_low is the amount of time the time encoded signal is low during a switch cycle.

4. The system according to claim 1, wherein the time encoding circuit includes a switch in electrical communication with the battery.

5. The system according to claim 1, wherein the switch includes a first and second transistor, the first transistor being in electrical series connection with the second transistor, the control input of the first and second transistor being in electrical communication with the battery voltage, and a first conducting terminal being in electrical communication with the battery voltage, the second transistor having a conducting terminal in electrical communication with electrical ground.

6. The system according to claim 5, wherein the switch includes a third transistor connected between the gate of the first and second transistor and an electrical ground, the control input of the third transistor being in electrical communication with the comparator to receive a feedback signal.

7. The system according to claim 5, wherein the feedback signal causes the switch circuit to oscillate.

8. The system according to claim 1, wherein the time encoding circuit includes an integrator configured to integrate the battery voltage.

9. The system according to claim 8, wherein the integrator is configured to integrate the battery voltage according to the relationship V(t)=−

∫

(V_sw−

V_ref)t dt, where V is the integrated signal, V_sw is a switch signal based on the battery voltage, and V_ref is the reference voltage.

10. The system according to claim 8, wherein the integrator includes a operational amplifier.

11. The system according to claim 10, wherein the operational amplifier has a resistor connected to a negative input of the operational amplifier and configured to receive the battery voltage, and a capacitor connected between the negative input and an output of the operational amplifier, and a voltage reference connected to a positive input of the operational amplifier.

12. The system according to claim 1, wherein the time encoding circuit includes a comparator.

13. The system according to claim 12, wherein the comparator includes an operational amplifier.

14. The system according to claim 13, wherein the operational amplifier includes two positive feedback loops.

15. The system according to claim 13, wherein the operational amplifier includes a resistor connected between a positive input and an output of the operational amplifier.

16. The system according to claim 13, wherein an output of the operational amplifier is connected to a control input of a transistor, and the transistor is in electrical communication with the negative input of the operational amplifier.

17. The system according to claim 16, wherein the transistor is an n-channel MOSFET, and a gate of the transistor is connected to the output of the operational amplifier, the drain of the transistor is connected to an electrical ground, and the source of the transistor is in electrical communication with the negative input of the operational amplifier.

18. The system according to claim 13, wherein the negative input of the operational amplifier is in communication with a voltage divider.

19. The system according to claim 1, further comprising a kelvin connection connected between the comparator and the controller.

20. The system according to claim 1, wherein the controller is configured to control a power circuit to power down the time encoding circuit.

21. The system according to claim 20, wherein the power circuit includes a transistor connected between the battery voltage and the operational amplifier power supply.

22. The system according to claim 1, wherein the time encoding circuit includes a switch, an integrator, and a comparator.

23. The system according to claim 22, wherein the battery is connected to the switch, the switch generates a switch signal that is provided to the integrator, the integrator generates a integrated signal that is provided to the comparator, and the comparator is configured to generate a time encoded signal that is provided to the controller.

24. The system according to claim 23, wherein the comparator provides a feedback signal to the switch, causing the switch to oscillate.