Circuit to measure vehicle battery voltage

• US 7,812,569 B2
• Filed: 12/17/2004
• Issued: 10/12/2010
• Est. Priority Date: 12/17/2004
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Weber, Charles F.
• Primary Examiner(s): Vu; Bao Q
• Assistant Examiner(s): Tran; Nguyen
• Application Number:
  US11/016,579
• Publication Number:
  US 20060132140A1
• Time in Patent Office: 2,125 Days
• Field of Search: 324/522, 324/713, 324/433, 324/429, 324/428, 324/427, 324/444, 324/426, 320/134, 320/127, 320/129, 320/130, 320/131, 320/135, 320/136, 702/35, 702/58, 702/63
• US Class Current: 320/134
• 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 voltage, the system comprising:

a time encoding circuit in electrical communication with the voltage, the time encoding circuit generating a time encoded signal corresponding to the voltage, the time encoding circuit includes a switch, an integrator, and a comparator,

the switch generating a switched signal based on the voltage, the switch being in communication with the integrator through a first resistor to provide the switched signal, a first side of the first resistor being in communication with the switch and a second side of the first resistor being in communication with the integrator,

the integrator integrating the switched signal to generate an integrated signal, the integrator being in communication with an input of the comparator to provide the integrated signal, the integrator including a capacitor, a first side of the capacitor being in communication with the input of the comparator and a second side of the capacitor being in communication with the second side of the first resistor,

the comparator receiving the integrated signal to generate the time encoded signal, a first feedback loop between being connected between an output of the comparator and the switch causing the switch to oscillate based on the time encoded signal;

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

wherein a second feedback loop includes a transistor, the output of the comparator is connected to a gate of the transistor and an output of the transistor is connected to the negative input of the comparator.

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 2, wherein the timer receives the time encoded signal 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, V_bat is the voltage being measured, and V_ref is the time encoded signal voltage.

4. 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 voltage, and a first conducting terminal being in electrical communication with the voltage, the second transistor having a conducting terminal in electrical communication with electrical ground.

5. The system according to claim 4, 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 through the first feedback loop to receive a feedback signal.

6. The system according to claim 4, wherein the feedback signal causes the switch circuit to oscillate.

7. The system according to claim 1, wherein the integrator is configured to integrate the 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 voltage, and V_ref is the reference voltage.

8. The system according to claim 1, wherein the integrator includes an operational amplifier.

9. The system according to claim 8, wherein the operational amplifier has a second resistor connected to a negative input of the operational amplifier and configured to receive the voltage, and the capacitor is 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.

10. The system according to claim 1, wherein the comparator includes an operational amplifier.

11. The system according to claim 10, wherein the operational amplifier includes two positive feedback loops.

12. The system according to claim 10, wherein the operational amplifier includes a resistor connected between a positive input and an output of the operational amplifier.

13. The system according to claim 10, 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.

14. The system according to claim 13, 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.

15. The system according to claim 10, wherein the negative input of the operational amplifier is in communication with a voltage divider.

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

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

18. The system according to claim 17, wherein the power circuit includes a transistor connected between the voltage and the operational amplifier power supply.

19. The system according to claim 1, wherein substantially all current of the switched signal travels through the capacitor.

20. The system according to claim 1, wherein 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, V_bat is the voltage being measured, and V_ref is the time encoded signal voltage.

21. A system for measuring a voltage, the system comprising:

a time encoding circuit in electrical communication with the voltage, the time encoding circuit generating a time encoded signal corresponding to the voltage, the time encoding circuit includes a switch, an integrator, and a comparator,

the switch generating a switched signal based on the voltage, the switch being in communication with the integrator through a first resistor to provide the switched signal, a first side of the first resistor being in communication with the switch and a second side of the first resistor being in communication with the integrator,

the integrator integrating the switched signal to generate an integrated signal, the integrator being in communication with an input of the comparator to provide the integrated signal, the integrator including a capacitor, a first side of the capacitor being in communication with the input of the comparator and a second side of the capacitor being in communication with the second side of the first resistor,

the comparator receiving the integrated signal to generate the time encoded signal, a first feedback loop comprising a resistor being connected between an output of the comparator and the switch, the first feedback loop communicating the time encoded signal from the comparator to the switch causing the switch oscillate;

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

wherein a second feedback loop is connected between the output of the comparator and a negative input of the comparator, wherein the second feedback loop includes a transistor, the output of the comparator is connected to a gate of the transistor and an output of the transistor is connected to the negative input of the comparator.

22. The system according to claim 21, wherein a third feedback loop is connected between the output of the comparator and a positive input of the comparator.