JPH05322998A - Battery capacity discriminator - Google Patents

Abstract

PURPOSE:To obtain the battery capacity detector capable of reducing the accumulation of offset errors at the time when current is detected with simple device constitution. CONSTITUTION:A battery current detection means 9a detects electric current of charge and discharge of a battery current compensation means 9b previously stores an error current value of the battery current detection means 9a and correct the output of the battery current detection means 9a by means of the error current value. A charge and discharge current integration means 9d integrates the output of the corrected battery current compensation means 9k and a battery capacity discrimination means 9g compares an integrated value with a specified reference value and discriminate a battery capacity. Otherwise the reference value is modified according to the integration value of the error current value, the modified reference value is compared with a battery value in which charge and discharge currents are integrated and obtained and same functions are constituted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery capacity determination device for detecting battery capacity.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 59-8789 discloses a starter.
It is disclosed that the battery capacity is detected by adding / subtracting the integrated value of the charging / discharging current during traveling to / from the initial characteristic obtained from the battery discharging characteristic at the time of starting the battery.

[0003]

However, since an ordinary current sensor has an offset error (that is, a fixed error included in the detected value by a fixed amount), the offset error of the current sensor is accumulated in this battery capacity detection method.
As a result, there arises a problem that the battery capacity includes a large error. For example, when an offset of 1A occurs, 30
An error of 0.5 AH is obtained in minute driving, but an error of 5 AH is obtained in 5 hour traveling. Of course, if a current sensor with an extremely small offset error is used, the above problem can be avoided, but for that purpose, it is necessary to employ an expensive and precise current sensor, which causes cost and maintenance problems.

The present invention has been made in view of the above problems, and an object thereof is to provide a battery capacity determination device capable of reducing the accumulation of offset errors in current detection with a simple device configuration.

[0005]

A battery capacity determination device according to the first aspect of the present invention stores a battery current detecting means for detecting a charging / discharging current of a battery, an error current value of the battery current detecting means in advance, and the error. A battery current compensating means for correcting the output of the battery current detecting means using a current value, a charging / discharging current integrating means for integrating the output of the battery current compensating means, and an output of the charging / discharging current integrating means as a predetermined reference. And a battery capacity determination means for determining the battery capacity by comparing with the value.

A battery capacity determination device according to a second aspect of the present invention is a battery current detection means for detecting a charging / discharging current of a battery,
Charge / discharge current integrating means for integrating the output of the battery current detecting means and error current integrating means for storing the error current value of the battery current detecting means in advance and integrating the error current value to output the error current integrated value. Means, reference value correction means for correcting a predetermined reference value based on the error current integrated value, and battery capacity determination means for comparing the output of the charge / discharge current integration means with the corrected reference value to determine the battery capacity. It is characterized by having and.

[0007]

In the first aspect of the invention, the battery current detecting means detects the charging / discharging current of the battery, the battery current compensating means stores the error current value of the battery current detecting means in advance, and the battery current detecting means uses the error current value. The output of the detection means is corrected. The charging / discharging current integrating means integrates the corrected output of the battery current compensating means, and the battery capacity determining means compares the integrated value with a predetermined reference value to determine the battery capacity.

In the second invention, the battery current detecting means detects the charge / discharge current of the battery, and the charge / discharge current integrating means integrates the output of the battery current detecting means. On the other hand, the error current integrating means stores the error current value of the battery current detecting means in advance and integrates the error current value to output the error current integrated value, and the reference value correcting means determines the predetermined reference value based on the error current integrating value. To correct. Then, the battery capacity determination means compares the output of the charge / discharge current integration means with the corrected reference value to determine the battery capacity.

[0009]

As described above, the battery capacity judging device of the first invention comprises the battery current compensating means for correcting the output of the battery current detecting means by using the error current value of the battery current detecting means stored in advance, Since the battery capacity is detected based on the magnitude of the integrated value of the correction output, it is possible to prevent the error current value of the battery current detecting means from being integrated, and it is possible to detect the battery capacity easily and accurately.

The battery capacity determination device of the second invention is
The error current value of the battery current detection means stored in advance is stored and integrated, the error current integration means, the reference value correction means for correcting a predetermined reference value by the error current integration value, and the integrated value of the battery charge / discharge current Since the battery capacity is determined by comparing it with the corrected reference value, the same effect as the first invention can be obtained.

[0011]

【Example】

(Embodiment 1) An embodiment of the first invention will be described below with reference to the drawings. In FIG. 1, 1 is an in-vehicle battery, 2 is a vehicle driving engine, 3 is an engine starting starter, 4
Is a starter switch for starting the starter. As is well known, the starter switch 4 is turned on to supply electric power from the battery 1 to the starter, whereby the starter 3 is rotated. , The engine 2 starts.

A generator 5 is driven by the engine 2 via a belt and pulley (not shown) to charge the battery 1 and supply electric power to an electric load 8 such as a lamp, a blower motor, a defogger, and the like. Is a current detector for detecting the charge / discharge current of the battery 1 (a part of the battery current detecting means in the present invention), 7 is a temperature detector for detecting the temperature of the battery 1, 9 is the state of the engine 2, The control circuit detects the voltage, the current, and the temperature to control the rotation speed of the engine 2 and the power generation of the power generator 5, and further detects the life of the battery to display it on the display 10.

Next, the control circuit 9 will be described with reference to the block diagram shown in FIG. The control circuit 9 is an ordinary microcomputer device, and includes an I / A converter including a D / A and A / D converter.
/ O interface, memory, and CPU are connected to the bus. The control circuit 9 is functionally equivalent to the battery current detector 9
a, battery temperature detector 9b, battery voltage detector 9c
(Remaining part of battery current detecting means in the present invention), current integrating section (charging / discharging current integrating means in the present invention) 9d, discharge characteristic calculating section 9e, power generation control section 9f, battery capacity monitoring section (battery in the present invention) It comprises a capacity determination means) 9g, an engine state detection section 9h, an engine control section 9j, an alarm section 9i, and a battery current compensation section (battery current compensation means in the present invention) 9k. The battery current detector 9a, the battery temperature detector 9b, and the battery voltage detector 9c each have A
It consists of a / D converter.

The control circuit 9 will be described with reference to the flowchart shown in FIG. First, in step S1, the starter switch 4 is turned on to start the starter 3. The next step S2 is a step of measuring the discharge characteristic at the start of the starter, and the battery 1 detected by the current detector 6
The discharge current I _B1 and the voltage V _B1 of the battery 1 detected by the voltage detector 9c are read.

Details of step S2 will be described with reference to FIG.
I will explain in detail. Battery detected by current detector 6
1 discharge current I_B1In step 302, the current detector 9a
Read in, and in step 303 discharge current I_B1Is 1
Since it is over 00 [A], it is possible to confirm the start of the starter 3.
Acknowledge. When it is confirmed that the starter 3 is started, the starter 3
Immediately after starting, a large current suddenly flows and noise is generated.
Therefore, in order not to be affected by this noise,
50 after the starter start is detected at step 303
Wait ms (step 304), and in the next step 305
Is the discharge current I of the battery 1 by the current detector 9a. _B1Read
See in.

In the next step 306, step 305
The discharge current I _B1 read in is from 60 [A] to 250
If it is within the range up to [A], it is detected that the starter 3 is in operation, and in step 307, the voltage detection unit 9c reads the voltage V _B1 of the battery 1. Here, the above discharge current range is 60 [A] to the starter 3 when the starter 3 is operating and the engine is not yet started.
It is set by judging that the current of 250 [A] flows, and it is not particularly limited to this range.

In the next step 308, the discharge current I _B1 of the battery 1, the voltage V _B1 and the time t are stored. In the next step 309, 3 [s] after starting the starter (normally,
The above operation is stopped when a certain amount of time has been set in consideration of the fact that 1 [s] is not required from the start of the starter to the start of the engine. If 3 [s] has not elapsed after the start, step 30 is performed again.
Return to 5.

At this time, the discharge current I during the operation of the above-mentioned steps 305 to 309, that is, when the starter is operated.
_B1 and voltage V _B1 are read and stored at intervals of 25 [ms], and the discharge current I corresponding to the time t at that time is repeated.
_B1 and the voltage V _B1 are stored. It should be noted that these data always store new 10 data. Then, in step 306, when the discharge current becomes 60 [A] or less and the start of the engine is detected, the operation except step 307 and step 308 is repeated to start the start 3
After [s], the process moves from step 309 to step 310. In step 310, de-stored at step 308 - from the data, calculates the discharge current I _B1 of the battery, and the voltage V _B1, the maximum value I _Bmax of the time t, V _Bmax and the t _{ma x,} step 311 On the contrary, the minimum values I _Bmin , V _Bmin, and t _min are calculated.

In the next step 312, the horizontal axis represents the discharge current and the vertical axis represents the voltage.
0, the discharge current and the maximum and minimum values of the voltage calculated in step 311 are blotted, and a characteristic diagram is drawn by connecting them with a straight line. Next, according to this characteristic diagram, the discharge current is 150
The voltage at the time of [A] is the first capacitance detection voltage V _Bd1, and the time t from the start of the starter to the detection of the voltage V _Bd1 is 10 times t stored in step 308.
Data is averaged and this is taken as the capacity detection time t _d . However, the discharge current for determining the first capacitance detection voltage V _Bd1 need not be limited to 150 [A].

In the next step S3, the first capacity detection voltage V _Bd1 is corrected as follows to obtain the battery capacity VI ₁ during starter operation. This step S3 will be described in detail with reference to the flowchart of FIG. That is, the battery voltage when the battery 1 is discharged decreases with time, and shows a stable voltage value after about 5 seconds have elapsed from the start of discharging. On the other hand, the start-up of the engine 2 by driving the starter 3 is normally performed within 1 second as described above, and the measured value of the voltage of the battery 1 when the starter is driven, that is, as described above. The first capacitance detection voltage V _Bd1 measured in the above shows a value higher than the voltage when it is stable.

Therefore, the relationship between the discharge time and the voltage of the battery characteristics is obtained in advance, and in step 402, the first capacity detection voltage V determined by the discharge current during the starter operation.
A deviation ΔV between _Bd1 and a stable value obtained 5 seconds after the starter 3 is started is corrected by subtracting it from the first capacitance detection voltage V _Bd1 . By correcting in this way, the battery 1
More accurate battery 1 when discharging at 50 [A]
Of the second capacitance detection current V
_Bd2 .

Furthermore, since the battery voltage has a temperature characteristic, the battery temperature detector 7 is operated at step 403.
The battery temperature T _B detected by is input to the battery temperature detection unit 9b, and in step 404, the battery temperature T _B is input.
The second capacitance detection voltage V _Bd2 is corrected according to _B. By this correction, a more accurate voltage of the battery 1 can be obtained, which is used as the third capacity detection voltage V _Bd3 .

Next, at step 405, the battery capacity V during starter operation is calculated from the third capacity detection voltage V _Bd3.
I ₁ is calculated, which will be described below. FIG. 4 is a characteristic showing the relationship between the battery voltage and the battery capacity in the case where the battery 1 is in a new state, is discharged at a predetermined current for a predetermined time, and there is no stratification of the battery liquid specific gravity or polarization immediately after charging. Is indicated by a solid line. It can be understood from FIG. 4 that the battery voltage is low when the battery capacity is small. Then, this characteristic is stored in the memory.

In step 405, the capacity of the battery 1 during starter operation (hereinafter referred to as the first battery capacity) is determined by using the third capacity detection voltage V _Bd3 obtained as described above from this characteristic diagram. ) Determine VI ₁ . In this way, step S3 is executed. Next step S4 will be described below.

First, in the case of the first running last time, the charging / discharging current of the battery 1 after the start of the engine detected by the current detecting unit 6 and read by the battery current detecting unit 9a is integrated (current integrating unit 9d). ), The integrated value is the first
In addition to the battery capacity VI ₁ of the above, the second battery capacity VI ₂ during traveling is detected (battery capacity monitor unit 9g).
Next, the last value of the second battery capacity VI ₂ , that is, the value at the end of travel is stored as the third battery capacity VI ₃ (battery capacity monitor unit 9g).

In this run, this step S4
At the third battery capacity VI₃Read out. Next step
Up S5 (battery capacity monitor unit 9g)
Battery capacity VI of 3₁, VI₃Compare the size of
The first value is the fourth battery capacity VI. _FourAnd

If the state of the battery 1 is good, the first and third battery capacities have substantially equal values, and therefore either of the first and third battery capacities may be adopted. However, in case of the following case, the smaller one of the first and third battery capacities VI ₁ and VI ₃ is adopted, and the reason will be described below. Firstly, the first battery capacity VI ₁ is larger than the _third battery capacity VI ₃ by a predetermined value.

This is because the concentration of the battery liquid becomes high near the electrodes (hereinafter referred to as polarization) after stratification of the battery liquid specific gravity or after charging and charging, so that the characteristic shown by the broken line in FIG. 4 is obtained. This is a case where the first battery capacity VI ₁ is required to be large relative to the true capacity because the battery voltage with respect to the capacity is large with respect to the true characteristic indicated by the solid line.

Therefore, in this case, it is determined that the second battery capacity VI ₂ is close to the true battery capacity, and the third battery capacity VI ₃ is selected as VI ₄ . Secondly, the third battery capacity VI ₃ is larger than the _first battery capacity VI ₁ by a predetermined value. As shown in FIG. 5, when the capacity of the battery 1 is approximately 80% or less of the actual capacity (capacity in a 100% charged state), the charging efficiency (rate of increase in capacity with respect to charging current) is approximately 100%. However, when the capacity of the battery 1 is approximately 80% or more of the actual capacity, gassing (when the battery is charged, the voltage of the electrodes increases as the capacity increases, and when the voltage increases to a predetermined value or more,
As the charging current causes electrolysis of water in the battery fluid), the charging efficiency gradually decreases.
The charging efficiency of the battery varies depending on the capacity of the battery.

That is, when the battery is charged, its capacity becomes approximately 80% or more of the actual capacity, and when charging is continued, the charging current used for gassing was used for charging the battery. Since it is accumulated as
This is because the battery capacity VI ₃ is required to be larger than the true capacity. Further, when the battery is deteriorated, as shown by the broken line, the charging efficiency is reduced more rapidly, so that the third battery capacity VI ₃ at the time of deterioration is required to be larger than that at the time of new product. Therefore, in this case, it is determined that the first battery capacity VI ₁ is close to the true battery capacity, and the first battery capacity VI ₁ is selected as the fourth battery capacity VI ₄ .

In contrast to the above-mentioned stratification, gassing causes bubbles in the electrodes, and the battery liquid is agitated by the bubbles, so stratification and gassing are unlikely to occur at the same time. Therefore, since the first and third battery capacities do not increase, it is possible to know the correct capacity by adopting the smaller value as described above. In the next S6, the charging current I _{B2 of the} battery is detected by the current detector 6.

In next step S7, the running battery capacity VI ₂ is calculated by integrating the battery current obtained in S6 with the initial battery capacity VI ₄ obtained in S5 as an initial value. The current detector 6 generally has a current detection error. This error does not cause much problem when the integrated time (running time) is short, but cannot be ignored when the integrated time becomes long. (For example, when an offset error of 1A occurs, a cumulative error of 0.5AH is obtained after running for 30 minutes.
Accumulation error of 5 AH will occur in Hr traveling. ) Next S8
The (battery current compensator 9k) corrects the current detection error of the current detector 6 described above. Specifically, the current detection error (the current detector 6 and the battery current detection unit 9
The error component (particularly the offset error) caused by a is obtained by a test in advance and stored. The current detection error may be obtained for each device, or may be obtained as an average value of the current detector 6 and the battery current detection unit 9a for each model. Here, the current detection error is obtained and stored as a predetermined range for each model. If the positive one of the current detection errors is I _BH and the negative one is I _BL , the true battery current is I _B2 −. It should be between I _BH and I _B2 + I _BL . In other words, I _BH means the maximum error in the excess current direction that can be assumed as the current detection error, and I _BL means the maximum error in the insufficient current direction that can be assumed as the current detection error.

Further, in S8, the maximum integrated capacity VI _2H = VI
₄ + Σ (I _B2 + I _BL ), minimum integrated capacity VI _2L = VI ₄ +
Calculate Σ (I _B2 −I _BH ). That is, as shown in FIG. 7, the battery capacity during traveling is between VI _2H and VI _2L . The estimated range of the true capacity (difference between VI _2H and VI _2L ) becomes wider as the error of the current detector becomes larger and the integration time becomes longer.

The following steps S9 to S12 are steps for controlling power generation in accordance with the battery capacity. The prevention of overcharging prevents liquid slippage and the improvement of fuel consumption, and the prevention of overdischarge prevents the battery from going up. Has a purpose. In the next S9, if the maximum integrated capacity VI _2H obtained in S8 is larger than the preset upper limit SOC _H of the battery capacity, the power generation control unit 9f suppresses power generation in S10 to prevent overcharging.

When the minimum integrated capacity VI _2L is smaller than the preset capacity lower limit value SOC _L in S11 (time in FIG. 7), the power generation control unit 9f increases power generation in S12 to prevent the battery from going up. .. If necessary, the engine control unit 9j may increase the idle speed to increase the generator output. Thus, the upper limit value SOC _H and the lower limit value SO of the capacity
C _L (reference value in the present invention) is the maximum integrated capacity V
I _2H and minimum integrated capacity VI _2L are compared, and power generation is controlled so as to maintain them within the allowable upper and lower limit values SOC _H and SOC _L , thereby overcharging and overdischarging regardless of the presence of a current detection error. Can be avoided.

In the above embodiment, the current detection error error component (I _BL , I _BH ) is set to a fixed value. However, based on the characteristics of the current detector 6 and the like, the temperature and the battery current are used as variables. Good. In S13, when the battery capacity VI ₂ has decreased, a battery life or battery up alarm is issued. In S14, the key SW is judged, and if ON, the process returns to S6 and repeats S6 to S14. The final accumulation result after running step S15 is stored as a VI _3, ready for the next run.
Incidentally, by using the least integrated capacity VI _2L in place of the VI ₂ at S15, it can be set on the safe side the initial capacity of the next running against a dead battery.

In the above description, step S8 is
Battery current compensating means referred to in the present invention and charge / discharge current integration
Means and the steps S9 and S11 are battery capacity.
It constitutes a quantity determination means. (Example 2) Also, the above
In the embodiment, in step S8, the current detection error component I_BL, I_BHTotal
Measured current I _B2The upper limit capacity SOC is corrected._H
And lower limit capacity SOC_LEven if you correct the
(See FIG. 8).

That is, in S8, the upper and lower limit capacities SOC _H and SOC _H may be corrected by the following calculation. SOC _H = SOC _H over _{ΣI BL SOC L = SOC L +} ΣI BH Furthermore, the battery 1 is the real capacity be (charge for the full-charge capacity is lowered due to the life, as shown in FIG. 6 is not increased, gassing It is desirable to change and set the upper limit value SOC _{H of the} capacity (which is consumed by the battery) according to the battery life. The upper limit capacity (SOC _H, SOC _L) when the corrected as described above, in this embodiment should be noted that it may be set to an initial value at the time of E / G starts (before the correction by the current detection error), S7 constitutes charging / discharging current integrating means, and S8 constitutes error current integrating means and reference value correcting means.

As described above, in this embodiment, it is possible to prevent the battery from being overcharged or the battery going up due to the accumulation of the detection error without providing a special circuit configuration for the current detection error generated in the current detector. Is possible.

[Brief description of drawings]

FIG. 1 is a block diagram of a vehicle power supply device that employs a battery capacity determination device of the present invention;

FIG. 2 is a functional configuration diagram showing a functional configuration of a control circuit 9 of FIG.

3 is a flowchart showing the operation of the control circuit 9 of FIG. 1,

FIG. 4 is a characteristic diagram showing a relationship between a battery voltage and a battery capacity of a battery,

FIG. 5 is a characteristic diagram showing the relationship between battery charging efficiency and battery capacity,

FIG. 6 is a characteristic diagram showing the relationship between the integrated current amount of the battery and the battery capacity in FIG.

FIG. 7 is a characteristic diagram showing a time change of the battery capacity in FIG.

FIG. 8 is a characteristic diagram showing a time variation of the battery capacity in a modified mode,

FIG. 9 is a flowchart showing details of S3 in FIG.

10 is a flowchart showing the details of S3 in FIG.

[Explanation of symbols]

1 is a battery, 6 is a current sensor (battery current detecting means), 9 is a control circuit (battery current compensating means, charging / discharging current integrating means, battery capacity determining means)

Claims (2)

[Claims] 1. A battery current detecting means for detecting a charging / discharging current of a battery, an error current value of the battery current detecting means is stored in advance, and the output of the battery current detecting means is corrected using the error current value. Battery current compensating means, charging / discharging current accumulating means for accumulating the output of the battery current compensating means, and battery capacity judging means for judging the battery capacity by comparing the output of the charging / discharging current accumulating means with a predetermined reference value. And a battery capacity determination device. 2. A battery current detecting means for detecting a charge / discharge current of a battery, a charge / discharge current integrating means for integrating outputs of the battery current detecting means, and an error current value of the battery current detecting means stored in advance. An error current integration unit that integrates the error current value and outputs an error current integration value; a reference value correction unit that corrects a predetermined reference value based on the error current integration value; and an output of the charge / discharge current integration unit. A battery capacity determination device comprising: a battery capacity determination means for determining a battery capacity by comparing with a predetermined reference value.