BATTERY STATE DETERMINING APPARATUS

• US 20090088994A1
• Filed: 03/08/2007
• Published: 04/02/2009
• Est. Priority Date: 03/10/2006
• Status: Active Grant

• Current Assignee: Shin-Kobe Electric Machinery Company Limited (Resonac Holdings Corp.)
• Original Assignee: Shin-Kobe Electric Machinery Company Limited (Resonac Holdings Corp.)
• Inventors: Hara, Takashi, Machiyama, Yoshiaki, Yamada, Keizo, Yamada, Yoshifumi
• Granted Patent: US 8,036,839 B2
• Time in Patent Office: Days
• US Class Current: 702/63
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• 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 31/379 for lead-acid batteries
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H01M 10/06 Lead-acid accumulators semi-lead accumulators H01M10/20
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

The present invention provides a battery state determining apparatus which can determine a battery state of a lead battery from an engine starting voltage accurately considering influence of a temperature of a vehicle. An engine starting voltage Vst1 obtained by correcting an engine starting voltage Vst of a lead battery at an engine starting time is calculated based upon an open-circuit voltage OCV and a temperature of a vehicle (S112), a battery determination voltage Vst_th representing a voltage of the lead battery at an engine starting time when a growth rate of internal resistance of the lead battery reaches a predetermined value from the open-circuit voltage OCV is calculated (S126), and a battery state of the lead battery is determined by determining whether an engine starting voltage Vst1 belongs to a predetermined region on a characteristic map (S132). A temperature of the lead battery measured after at least a predetermined time elapsing from engine stopping is regarded as temperature of the vehicle so that the engine starting voltage Vst1 is calculated.

Claims

1. A battery state determining apparatus for determining a battery state of a lead battery mounted on a vehicle, comprising:

an open-circuit voltage measuring section which measures an open-circuit voltage OCV of the lead battery;

an engine starting voltage measuring section which measures an engine starting voltage Vst representing a voltage at an engine starting time of the lead battery;

a vehicle temperature measuring section which measures a temperature of the vehicle;

an engine starting voltage correcting section which calculates an engine starting voltage Vst1 obtained by correcting the engine starting voltage Vst measured at the engine starting voltage measuring section based upon the open-circuit voltage OCV measured at the open-circuit voltage measuring section and the temperature of the vehicle measured at the vehicle temperature measuring section;

a determination voltage arithmetic section which calculates, from the open-circuit voltage OCV measured at the open-circuit voltage measuring section, a lead battery determination voltage Vst_th representing a voltage at an engine starting time of the lead battery when an increase rate of internal resistance of the lead battery reaches a predetermined value for lead battery replacement; and

a battery state determining section which determines whether or not the engine starting voltage Vst1 calculated at the engine starting voltage correcting section is equal to or more than the lead battery determination voltage Vst_th calculated at the determination voltage arithmetic section.

3. The battery state determining apparatus according to claim 1, wherein, when the temperature of the vehicle is represented as T, a reference temperature of temperature correction is represented as T0, a temperature correction coefficient for correcting electric resistance of the vehicle at an engine starting time to a value based upon the reference temperature T0 is represented as alpha, and a constant taking a value in a range of from 0.9 to 1.1 is represented as “

A”

, the engine starting voltage correcting section calculates the engine starting voltage Vst1 according to the following Equation (1).

Vst1=OCV×

Vst/[Vst+{A+(T−

T0)×

alpha}×

(OCT−

Vst)] 

 

(1)

4. The battery state determining apparatus according to claim 3, wherein the temperature correction coefficient alpha is a temperature correction coefficient of electric resistance of a copper wire.

5. The battery state determining apparatus according to claim 1, wherein, when internal resistance of a new lead battery at the open-circuit voltage OCV=OCV0 (12.4<

=OCV0<

=13.0V) is represented as r0, an internal resistance threshold value of a lead battery for lead battery replacement is represented as r_th, electric resistance of the vehicle is represented as R, and a constant taking a value in a range of from 0.9 to 1.1 is represented as “

B”

, the determination voltage arithmetic section calculates the lead battery determination voltage Vst_th according to the following Equation (2).

Vst_—

th=OCV/{B+(r0/R)×

(r_—

th/r0)} 

 

(2)

6. The battery state determining apparatus according to claim 5, wherein the determination voltage arithmetic section calculates (r_th/r0) in the Equation (2) as a constant falling within a range of from 1.2 to 1.6.

7. The battery state determining apparatus according to claim 5, wherein, when the engine starting voltage Vst in a case in which the open-circuit voltage OCV of the new lead battery takes the OCV0 is represented as Vst0, the determination voltage arithmetic section calculates (r_th/r0) in the Equation (2) according to the following Equation (3).

(r0/R)=(OCV0−

Vst0)/Vst0 

 

(3)

8. The battery state determining apparatus according to claim 7, wherein the determination voltage arithmetic section calculates the engine starting voltage Vst0 in the Equation (3) according to the following Equation (4).

Vst0=Vst1×

OCV0/OCV 

 

(4)

9. The battery state determining apparatus according to claim 1, further comprising a lead battery temperature measuring section which measures a temperature of the lead battery, wherein the engine starting voltage correcting section further corrects the engine starting voltage Vst1 by adding an correction amount corresponding to the temperature of the lead battery measured at the lead battery temperature measuring section on one-to-one relationship to the engine starting voltage Vst1.

11. The battery state determining apparatus according to claim 1, wherein the open-circuit voltage measuring section measures a stable open-circuit voltage OCV when a dark current is flowing from the lead battery, and the engine starting voltage correcting section and the determination voltage arithmetic section calculate the engine starting voltage Vst1 and the lead battery determination voltage Vst_th using an open-circuit voltage OCV1 after corrected obtained by adding a correction amount which is a function of a temperature to the open-circuit voltage OCV measured at the open-circuit voltage measuring section.

12. The battery state determining apparatus according to claim 11 further comprising a storage section which stores therein a characteristic map defining a relationship between OCV and Vst1 of the lead battery and divided into a plurality of regions representing a degraded state of the lead battery,

wherein the battery state determining section determines the degraded state of the lead battery by determining a region of the plurality of regions of the characteristic map stored in the storage section to which OCV measured at the open-circuit voltage measuring section and Vst1 calculated at the engine starting voltage correcting section belong,

and wherein, when OCV is taken in a horizontal axis and Vst1 is taken in a vertical axis, the characteristic map stored in the storage section is divided to five regions of a first region where both OCV and Vst1 are high, a second region positioned on the left side of the first region where OCV is low, a third region positioned on a lower side of the first region where OCV is high and Vst1 is low, a fourth region positioned between the first and third regions, and a fifth region between the second and third regions,

and wherein a boundary between the first and fourth regions, a boundary between the second and fifth regions, a boundary between the fourth and third regions, and a boundary between the fifth and third regions are Vst_th calculated from OCV at the determination voltage arithmetic section, have positive slopes, and are curves with a shape of a logarithmic curve.

13. The battery state determining apparatus according to claim 12, wherein a boundary between the first and second regions and a boundary between the fourth and fifth regions of the characteristic map stored in the storage section are straight lines.

14. The battery state determining apparatus according to claim 12, wherein the battery state determining section determines that the lead battery has degraded when determining that OCV measured at the open-circuit voltage measuring section and Vst1 calculated at the engine starting voltage correcting section belong to the fourth to fifth regions of the characteristic map, and the battery state determining section determines that replacement of the lead battery is required when determining that OCV measured at the open-circuit voltage measuring section and Vst1 calculated at the engine starting voltage correcting section belong to the third region.

15. The battery state determining apparatus according to claim 12, wherein the open-circuit voltage measuring section measures OCV of the lead battery after a predetermined time elapsing after engine stopping.

16. The battery state determining apparatus according to claim 1, further comprising a converting section which converts an analog voltage at an engine starting time of the lead battery to a digital voltage value at a rate of 100 Hz or higher, wherein the battery state determining section deletes a lowest voltage value equal to or higher than a predetermined upper limit voltage value and a lowest voltage value equal to or lower than a predetermined lower limit voltage value from a plurality of the engine starting voltages (Vst) extracted for respective engine starts at the engine starting voltage measuring section and determines whether or not one of a medium value, a mode value and an average value of the remaining lowest voltage values is at most a preset determination reference voltage value.

17. The battery state determining apparatus according to claim 16, wherein the upper limit voltage value is 10.5V and the lower limit voltage value is 3.0V.

18. The battery state determining apparatus according to claim 16, wherein the upper limit voltage value is the maximum value of the lowest voltage values (Vst) and the lower limit voltage value is the minimum value of the lowest voltage values (Vst).

19. The battery state determining apparatus according to claim 16, further comprising a nonvolatile storage section which stores the lowest voltage values (Vst) extracted at the engine starting voltage measuring section, wherein the battery state determining section reads a plurality of the engine starting voltages (Vst) stored in the storage section.

20. The battery state determining apparatus according to claim 16, further comprising an engine starting interval determining section which determines whether or not engine start has been performed after at least a predetermined time elapsing after engine stopping, wherein, when the engine starting interval determining section makes an affirmative determination, the engine starting voltage measuring section extracts an engine starting voltage value (Vst) at an engine starting time of the lead battery from digital voltage values converted at the converting section.

2. A battery state determining apparatus for determining a battery state of a lead battery mounted on a vehicle, comprising:

an open-circuit voltage measuring section which measures open-circuit voltage OCV of the lead battery;

an engine starting voltage measuring section which measures an engine starting voltage Vst representing a voltage at an engine starting time of the lead battery;

a lead battery temperature measuring section which measures a temperature of the lead battery;

an engine starting voltage correcting section which calculates an engine starting voltage Vst1 obtained by correcting the engine starting voltage Vst measured at the engine starting voltage measuring section based upon the open-circuit voltage OCV measured at the open-circuit voltage measuring section and a temperature of the vehicle;

a determination voltage arithmetic section which calculates, from the open-circuit voltage OCV measured at the open-circuit voltage measuring section, a lead battery determination voltage Vst_th representing a voltage at an engine starting time of the lead battery when an increase rate of internal resistance of the lead battery reaches a predetermined value for lead battery replacement; and

a battery state determining section which determines whether or not the engine starting voltage Vst1 calculated at the engine starting voltage correcting section is equal to or more than the lead battery determination voltage Vst_th calculated at the determination voltage arithmetic section,

wherein the engine starting voltage correcting section calculates the engine starting voltage Vst1 while regarding the temperature of the lead battery measured at the lead battery temperature measuring section after a predetermined time elapsed since engine stopping as the temperature of the vehicle.

10. The battery state determining apparatus according to claim 2, wherein the engine starting voltage correcting section further corrects the engine starting voltage Vst1 by adding an correction amount corresponding to the temperature of the lead battery measured at the lead battery temperature measuring section on one-to-one relationship to the engine starting voltage Vst1.