Method and apparatus for estimating a battery temperature

• US 5,079,716 A
• Filed: 05/01/1990
• Issued: 01/07/1992
• Est. Priority Date: 05/01/1990
• Status: Expired due to Fees

• Current Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Original Assignee: Globe-Union Inc.
• Inventors: Walker, Arlen P., Delaney, William C., Lenhardt, Brett M.
• Primary Examiner(s): Dixon, Joseph L.
• Application Number:
  US07/517,622
• Time in Patent Office: 616 Days
• Field of Search: 364/557, 364/424.05, 364/707, 364/483, 324/431, 322/33, 320/22-24, 320/30-32, 320/35, 180/65.8, 374/102, 374/103, 374/107, 374/169
• US Class Current: 320/153
• CPC Class Codes: H02J 7/007192 in response to temperature
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: H02J 7/14 for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle

Abstract

A method and apparatus for estimating the temperature of a vehicle battery, wherein the estimated temperature is used to control the voltage at which the vehicle battery is charged. The variables used to estimate the temperature of the vehicle battery can include a reference temperature sensed from one or more temperature sensors located apart from the battery, and a group of coefficients. Each type of vehicle using the vehicle battery temperature estimation method utilizes a group of coefficients tailored specifically for the vehicle. For a given type of vehicle, empirical data is compiled for determining the specific group of coefficients for the vehicle. This data is compiled by operating the vehicle, and periodically sampling and storing the vehicle speed, the reference temperature, the actual battery temperature, and the elapsed time between samplings. From this data a group of coefficient is determined for the vehicle. The coefficients are then utilized by the vehicle control unit to estimate battery temperature. Based upon the estimated battery temperature, the control unit then can control the voltage at which the vehicle battery is charged.

Claims

1. A method for charging a vehicle battery located in the engine compartment of a vehicle, the method comprising the steps of:

providing a vehicle with means for selectively controlling a charge voltage at which the vehicle battery is charged;

charging a vehicle battery at a charge voltage;

reading a first reference temperature from a temperature sensor within the engine compartment at a first time;

reading a second reference temperature from the temperature sensor with in the engine compartment at a second time;

determining a vehicle parameter at the second time;

determining a time difference between the first time and the second time;

performing a look up function to determine a coefficient, wherein the input to the look up function is the vehicle parameter;

estimating the vehicle battery temperature as a function of the first reference temperature, the second reference temperature, the time difference, and the coefficient;

reading a battery charging voltage at the second time;

determining an acceptable range of battery charging voltages for the estimated temperature;

applying a control signal related to the acceptable range to the means for selectively controlling which adjusts the charge voltage within the acceptable range of battery charging voltages;

wherein the step of estimating the vehicle battery temperature further comprises the steps of;

providing an initial battery temperature;

determining a first product of the coefficient and one-half of the time difference;

determining a first sum of 1 and the first product;

determining a second sum of the first reference temperature and the second reference temperature;

determining a first difference between the second sum and the initial battery temperature;

determining a second product of the first difference and the first product;

determining a third sum of the second product and the initial battery temperature; and

determining a quotient of the third sum and the first sum, wherein the quotient is the estimated vehicle battery temperature.

2. The method of claim 1, wherein the vehicle parameter is vehicle speed, and the step of performing the look up function comprises the steps of:

comparing the vehicle speed to a plurality of predetermined ranges of vehicle speeds, wherein each range of vehicle speeds corresponds to a vehicle state; and

accessing a look up table to determine the coefficient, wherein the look up table is accessed based upon the vehicle state.

3. The method of claim 1, wherein the range of battery charging voltages includes only one charging voltage.

4. The method of claim 1, wherein the vehicle parameter is vehicle speed, and the step of performing the look up function comprises the steps of:

comparing the vehicle speed to a plurality of predetermined ranges of vehicle speeds, wherein each range of vehicle speeds corresponds to a vehicle state; and

determining the coefficient from a function of vehicle state.

5. The method of claim 1, wherein the step of applying a control signal includes the step of comparing the charge voltage to the acceptable range of battery charging voltages.

6. A method for adjusting a charge voltage of a vehicle battery based upon the estimated temperature of the battery which is located in the engine compartment of a vehicle and adjusting the charge voltage of the vehicle battery based upon the estimated temperature of the battery, the method comprising the steps of:

1) determining a plurality of operational coefficients each associated with a vehicle parameter, the determination of each operational coefficient comprising the step of;

(1a) determining and storing at least one vehicle parameter during a first time period;

(1b) reading and storing at least one under hood temperature value from a temperature sensor during the first time period;

(1c) reading and storing at least one vehicle battery temperature value from a battery temperature sensor during the first time period;

(1d) providing an array of estimated temporary coefficients;

(1e) determining an array of estimated battery temperatures as a function of the under hood temperature and the array of temporary coefficients;

(1f) comparing each of the array of estimated battery temperatures with the respective vehicle battery temperature to determine an array of error terms each associated with one of the array of temporary coefficients;

(1g) selecting the one of the array of temporary coefficients having the smallest error term and saving the temporary coefficient as an operational coefficient referenced to the vehicle parameter;

2) estimating the temperature of the vehicle battery comprising the steps of;

(2a) determining an operating vehicle parameter during a second time period;

(2b) reading an under hood temperature value from a temperature sensor during the second time period;

(2c) selecting the one of the plurality of operational coefficients referenced to a vehicle parameter substantially similar to the operating vehicle parameter determined during the second time period; and

(2d) producing an estimated battery temperature as a function of the under hood temperature and the selected operating coefficient; and

3) adjusting the charge voltage at the vehicle battery based upon the estimated battery temperature.

7. The method of claim 6, wherein:

1) the step of determining and storing at least one vehicle parameter during the first time period comprises the steps of;

determining engine speed;

comparing the engine speed to a plurality of engine speed ranges each associated with a vehicle state;

determining the vehicle state associated with the engine speed range within which the engine speed falls; and

storing the vehicle state as the vehicle parameter; and

2) the step of determining an operating vehicle parameter during a second time period, comprises the steps of;

determining engine speed;

comparing the engine speed to the plurality of engine speed ranges;

determining the vehicle state associated with the engine speed range within which the engine speed falls; and

storing the vehicle state as the operating vehicle parameter.

8. The method of claim 6, wherein:

1) the step of determining and sorting at least one vehicle parameter during the first time period comprises the steps of;

determining vehicle speed;

comparing the vehicle speed to a plurality of vehicle speed ranges each associated with a vehicle state;

determining the vehicle state associated with the vehicle speed range within which the vehicle speed falls; and

storing the vehicle state as the vehicle parameter; and

2) the step of determining an operating vehicle parameter during a second time period comprises the steps of;

determining vehicle speed;

comparing the vehicle speed to the plurality of vehicle speed ranges;

determining the vehicle state associated with the vehicle speed range within which the vehicle speed falls; and

storing the vehicle state as the operating vehicle parameter.

9. The method of claim 6, wherein the step of providing an array of estimated temporary coefficients comprises the step of estimating one temporary coefficient.

10. The method of claim 6, wherein the step of providing an array of estimated temporary coefficients comprises the step of estimating a plurality of temporary coefficient.

11. The method of claim 6, wherein the step of determining the array of error terms comprises the step of squaring the difference between each one of the array of estimated battery temperatures and the respective vehicle battery temperature.