Method for calculating the parameters of the power battery of an electric motor vehicle

• US 20030034780A1
• Filed: 08/05/2002
• Published: 02/20/2003
• Est. Priority Date: 08/10/2001
• Status: Active Grant

• Current Assignee: Peugeot Citroen Automobiles SA (Stellantis NV)
• Original Assignee: Peugeot Citroen Automobiles SA (Stellantis NV)
• Inventors: Vacher, Cecile
• Granted Patent: US 6,788,069 B2
• Time in Patent Office: Days
• US Class Current: 324/427
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

The invention relates to a method for determining at least one operating parameter of the power battery (12) of a vehicle having an electric traction motor. The battery parameter comprises at least one of the following parameters: charging capacity, discharge power, state of overcharge or state of total discharge. The power battery'"'"'s internal resistance and the intensity of the current supplied or received are determined in order to calculate the parameter(s). This internal resistance is calculated, for example, using a low voltage auxiliary battery (18).

Claims

1. Method for determining at least one operating parameter of the power battery of a vehicle having an electric traction motor, wherein:

the battery parameter comprises at least one of the following parameters;

charging capacity, discharge power, state of overcharge or state of total discharge, and that;

the power battery'"'"'s internal resistance and the intensity of the current supplied or received is determined in order to calculate the parameter(s).

2. Method according to claim 1, wherein the parameter being the battery'"'"'s charging capacity state and/or discharge power state, the calculation of the charging capacity and/or discharge power uses the following equation:

3. Method according to claim 1, wherein the parameter being the state of overcharge, the battery terminal voltage threshold U_max is determined from the following formula:

4. Method according to claim 1, wherein the parameter being the state of total discharge, the battery terminal voltage threshold U_min, below which the battery is considered to be totally discharged, is determined using the following formula:

5. Method according to claim 2, 3 or 4, wherein the battery'"'"'s electromotive force or back electromotive force is preset according to the state of charge (SOC).

6. Method according to claim 5, wherein the electromotive force or back electromotive force is also preset according to the temperature of the battery.

7. Method according to claim 1, wherein a corrective expression which depends on the battery'"'"'s state of polarization is applied to each measured value of the battery'"'"'s internal resistance.

8. Method according to claim 7, wherein the corrective expression is made dependent upon the temperature.

9. Method according to claim 7, wherein the corrective expression is made dependent on the parameter to be calculated.

10. Method according to claim 9, wherein the corrective expression is made dependent on the time at the end of which the parameter must be calculated.

11. Method according to claim 1, wherein the internal resistance is also determined in order to detect the battery'"'"'s state of ageing.

12. Method according to claim 1, wherein the battery'"'"'s internal resistance is determined by means of an auxiliary low voltage battery connected to the power battery via a two-way DC/DC type converter.

13. Method according to claim 12, wherein the calculation of the internal resistance is carried out when the battery ignition circuit is switched off.

14. Method according to claim 13, wherein the calculation of the internal resistance is carried out automatically at intervals, for example at the same time as power battery self-discharge calculations.

15. Method according to claim 1, wherein determination of at least one of the vehicle'"'"'s power battery operating parameters comprises the determination of the power battery'"'"'s internal resistance and the intensity of the current supplied or received in order to calculate the parameter(s) is triggered by means of a signal outside the vehicle and the calculation result is obtained outside the vehicle.

16. Application of the method according to claim 1 to the calculation of the parameters of a power battery for a hybrid type vehicle comprising, besides the electric traction motor, an internal combustion type engine for propulsion which is also used to charge the battery via an alternator.