Automotive battery state monitor apparatus

• US 20040257045A1
• Filed: 06/17/2004
• Published: 12/23/2004
• Est. Priority Date: 06/23/2003
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Taniguchi, Makoto, Sada, Takeshi, Ichikawa, Atsushi
• Granted Patent: US 7,317,300 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/379 for lead-acid batteries

Abstract

A voltage control apparatus checks a battery voltage when an automotive generator gradually increases its output to be within a predetermined range after temporarily stopping the generator. Then, the battery voltage is picked up to calculate the charge rate. Further, a first charge rate and a first residual capacity of the battery is memorized when the engine is stopped. Periodically, a pseudo-open circuit voltage is checked when a charge/discharge current fits within a predetermined small range while the engine is not running, and a second charge rate calculated based on the checked pseudo-open circuit voltage. A second residual capacity is calculated using the first charge rate, the first residual capacity and the second charge rate.

Claims

1. An automotive battery state monitor apparatus comprising:

an automotive generator driven by an engine;

a controlling device that controls the generator;

an automotive battery to store electricity generated by the generator;

means for stopping the automotive generator temporarily after starting of the engine by a starter;

means for increasing an output of the generator gradually; and

means for picking up a battery voltage value when a battery charge/discharge current reaches within a predetermined small range to calculate a charge rate of the battery.

2. The automotive battery state monitor apparatus according to claim 1, wherein the stopping means controls a polarization state in the battery to stay within a predetermined range by controlling the output of the generator.

3. The automotive battery state monitor apparatus according to claim 1, wherein the predetermined range is a value between plus one ampere and minus one ampere.

4. The automotive battery state monitor apparatus according to claim 2, wherein the stopping means stops the generator for a predetermined period of time after starting of the engine.

5. The automotive battery state monitor apparatus according to claim 2, wherein the polarization state of the battery is defined as a polarization index P_n defined in the following formula.

6. The automotive battery state monitor apparatus according to claim 1, wherein the charge rate of the battery, calculated by using the voltage picked up when the charge/discharge current of the battery fits within the predetermined range, is considered as an initial charge rate.

7. The automotive battery state monitor apparatus according to claim 6, wherein the battery charge rate is calculated successively as a sum of repeated addition of a value to the initial charge rate by deriving added value as the product of the sampled current value and a sampling interval divided by the battery capacity when the charge/discharge current is sampled at the sampling interval.

8. The automotive battery state monitor apparatus according to claim 1, wherein the output increasing means periodically performs a controlled increase of the output of the generator after a temporal stoppage for the battery charge/discharge current to fit within the predetermined range while an engine is running.

9. The automotive battery state monitor apparatus according to claim 1, wherein the output increasing means performs a periodically controlled increase of the output of the generator after a temporal stoppage, with the period of time prior to a first stoppage being different from the others, for the battery charge/discharge current to fit within the predetermined range while an engine is running.

10. The automotive battery state monitor apparatus according to claim 1, the output increasing means further performs a periodically controlled increase of the output of the generator after a temporal stoppage, with the increase rate accordingly controlled based on a hysteretic curve relation between a terminal voltage and an actual-SOC, for the battery charge/discharge current to fit within the predetermined range while an engine is running.

11. An automotive battery state monitor apparatus comprising:

an electric device;

an automotive generator driven by an engine;

a battery that stores electricity generated by the generator in a vehicle, wherein a terminal voltage of the battery is defined as a pseudo-open circuit voltage (pseudo-OCV) when a charge/discharge current of the battery is within a predetermined small range;

means for storing a correlation information that maps the pusdo-OCV to the battery charge rate; and

means for calculating a present residual capacity SOH2 based on a first charge rate. SOC1, a first residual capacity SOH1 and a second charge rate SOC2, each of which are prepared in such a way that the first charge rate SOC1 and the first residual capacity SOH1 are memorized when the engine is stopped,

wherein the terminal voltage that is the pseudo-open circuit voltage is periodically checked when the battery charge/discharge current is within the predetermined range while an engine is not running, and the second charge rate SOC2 is calculated based on the picked up pseudo-OCV.

12. The automotive battery state monitor apparatus according to claim 11, wherein the present residual capacity SOH2 is defined in the following formula.

SOH2=(SOH1/SOC1)·

SOC2

13. The automotive battery state monitor apparatus according to claim 11, wherein contents of SOC1 are replaced with those of SOC2 and also contents of SOH1 are replaced with those of SOH2 at the time when the SOH2 is calculated.

14. The automotive battery state monitor apparatus according to claim 11, wherein the predetermined small range of the battery charge/discharge current means that the value of the electric current is between plus one ampere and minus one ampere.

15. The automotive battery state monitor apparatus according to claim 11, wherein a discharge current value is integrated and an integration value is subtracted from the SOH1 whenever updating a present residual capacity SOH2 when the electric device is put into operation while an engine is not running.

16. The automotive battery state monitor apparatus according to claim 15, wherein the present charge rate is calculated based on the SOC1, the SOH1, and the SOH2, by using the following formula.

SOC2=(SOC1/SOH1)·

SOH2

17. The automotive battery state monitor apparatus according to claim 16, wherein the contents of SOC1 are replaced with those of SOC2 and also the contents of SOH1 are replaced with those of SOH2 at the time when the SOH2 is calculated.

18. The automotive battery state monitor apparatus according to claim 11, wherein discharge current value and the terminal voltage of the automotive battery are picked up, an initial residual capacity is calculated based on these current value and voltage value, and thereafter the present residual capacity is calculated by adding the integrated amount of charge/discharge current value to the initial residual capacity.

19. The automotive battery state monitor apparatus according to claim 18, wherein the automotive generator is stopped temporarily after a predetermined period of time from starting of the engine, the output of the generator is increased gradually when a polarization state of the battery reaches within a predetermined range, the battery charge/discharge current value is controlled to be fitted within a predetermined small range, and a terminal voltage of the battery is checked when the charge/discharge current value reaches within the predetermined small range.