System and method for monitoring a state of charge of a battery

• US 10,173,613 B2
• Filed: 08/18/2015
• Issued: 01/08/2019
• Est. Priority Date: 08/18/2015
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Kloess, Scott R., Zuzelski, John T.
• Primary Examiner(s): Nguyen, Cuong H
• Application Number:
  US14/829,313
• Publication Number:
  US 20170050592A1
• Time in Patent Office: 1,239 Days
• Field of Search: 701 22, 701 41, 323284-285, 320104, 320134, 180443, 180 651, 307 101
• CPC Class Codes: B60R 16/033 characterised by the use of electrical cells or batteries for propulsion puposes B60K1/04; supplying batteries to, or removing batteries from, vehicles B60S5/06; testing of charge state G01R31/36
• CPC Class Codes: B62D 5/0481 monitoring the steering system, e.g. failures
• CPC Class Codes: G01R 31/3647 for determining the ability of a battery to perform a critical function, e.g. cranking
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

Systems and methods for monitoring the state of charge of a battery of a vehicle are provided. A battery monitor having a processor and a memory is configured to monitor an operating voltage and a loaded voltage of the battery. An electric power steering system is configured to be supplied with power from the battery. The battery monitor is configured to calculate a voltage drop between the operating voltage and the loaded voltage when the battery is under load from the electric power steering system. The battery monitor compares the voltage drop to a predetermined voltage drop and determines that the state of charge of the battery is low when the voltage drop is greater than or equal to the predetermined voltage drop. The battery monitor instructs the electric power steering system to operate in a limited state when the state of charge of the battery is low.

Claims

1. A method for monitoring a state of charge of a battery of a vehicle comprising:

monitoring an operating voltage of the battery with a battery monitor;

calculating a voltage drop between the operating voltage and a loaded voltage with the battery monitor when the battery is under load from an electric power steering system;

comparing the voltage drop to a predetermined voltage drop;

determining that the state of charge of the battery is low when the voltage drop is greater than or equal to the predetermined voltage drop; and

operating the electric power steering system in a limited state, wherein when the state of charge of the battery is low the current draw of the electric power steering system is limited to a current draw less than a peak current draw requirement when the voltage drop is less than the predetermined voltage drop.

2. The method of claim 1, further comprising:

alerting a vehicle control system that the state of charge of the battery is low when the voltage drop is greater than or equal to the predetermined voltage drop; and

providing a haptic response through a steering wheel of the vehicle.

3. The method of claim 1, further comprising:

calculating the voltage drop when a current load on the battery from the electric power steering system is greater than a predetermined current.

4. The method of claim 1, wherein the electric power steering system operates in a reduced current mode when the state of charge of the battery is low.

5. The method of claim 1, further comprising:

calculating the state of charge of the battery; and

operating the electric power steering system in the limited state based on the calculated state of charge of the battery.

6. The method of claim 1, further comprising:

storing a history of voltage drops in a memory; and

predicting the state of charge of the battery based on the history of voltage drops.

7. A monitoring system for determining a state of charge of a battery of a vehicle, comprising:

a battery monitor having a processor and a memory, the battery monitor configured to monitor an operating voltage and a loaded voltage of the battery; and

an electric power steering system configured to be supplied with power from the battery,

wherein the battery monitor is configured to calculate a voltage drop between the operating voltage and the loaded voltage when the battery is under load from the electric power steering system, compare the voltage drop to a predetermined voltage drop, determine that the state of charge of the battery is low when the voltage drop is greater than or equal to the predetermined voltage drop, and instruct the electric power steering system to operate in a limited state when the state of charge of the battery is low; and

wherein the electric power steering system is configured to operate when instructed by the battery monitor to limit a current draw of the electric power steering system to less than a peak current draw requirement when the voltage drop is less than the predetermined voltage drop.

8. The monitoring system of claim 7, wherein the battery monitor is further configured to monitor a current load of the battery and calculate the voltage drop when the current load of the battery is greater than a predetermined current.

9. The monitoring system of claim 7, wherein the battery monitor is configured to alert a vehicle control system that the state of charge of the battery is low when the voltage drop is greater than or equal to the predetermined voltage drop;

and to provide a haptic response through a steering wheel of the vehicle.

10. The monitoring system of claim 7, wherein the battery monitor is configured to determine that the state of charge of the battery is normal when the voltage drop is less than the predetermined voltage drop.

11. The monitoring system of claim 7, wherein the electric power steering system is configured to operate in a reduced current mode when the state of charge of the battery is low.

12. The monitoring system of claim 7, wherein the battery monitor is configured to calculate the state of charge of the battery and the electric power steering system is configured to operate in the limited state based on the calculated state of charge of the battery.

13. The monitoring system of claim 7, wherein the battery monitor is configured to store a history of voltage drops in the memory module and predict the state of charge of the battery based on the history of voltage drops.

14. A vehicle, comprising:

a battery;

an electric power steering system configured to be supplied with power from the battery; and

a monitoring system for determining a state of charge of the battery, the monitoring system comprising;

a battery monitor having a processor and a memory, the battery monitor configured to monitor an operating voltage and a loaded voltage of the battery,

wherein the battery monitor is configured to calculate a voltage drop between the operating voltage and the loaded voltage when the battery is under load from the electric power steering system, compare the voltage drop to a predetermined voltage drop, determine that the state of charge of the battery is low when the voltage drop is greater than or equal to the predetermined voltage drop, and instruct the electric power steering system to operate in a limited state when the state of charge of the battery is low; and

wherein the electric power steering system is configured to operate when instructed by the battery monitor to limit a current draw of the electric power steering system to less than a peak current draw requirement when the voltage drop is less than the predetermined voltage drop.

15. The vehicle of claim 14, wherein the battery monitor is configured to monitor a current load of the battery and calculates the voltage drop when the current load of the battery is greater than a predetermined current.

16. The vehicle of claim 14, wherein the battery monitor is configured to alert a vehicle control system that the state of charge of the battery is low when the voltage drop is greater than or equal to the predetermined voltage drop;

and to provide a haptic response through a steering wheel of the vehicle.

17. The vehicle of claim 14, wherein the battery monitor is configured to determine that the state of charge of the battery is normal when the voltage drop is less than the predetermined voltage drop.

18. The vehicle of claim 14, wherein the electric power steering system is configured to operate in a reduced current mode when the state of charge of the battery is low.

19. The vehicle of claim 14, wherein the battery monitor is configured to calculate the state of charge of the battery and the electric power steering system is configured to operate in the limited state based on the calculated state of charge of the battery.

20. The vehicle of claim 14, wherein the battery monitor is configured to store a history of voltage drops in the memory module and predict the state of charge of the battery based on the history of voltage drops.