JPH05134020A - Battery state detection device - Google Patents

Abstract

PURPOSE:To enable it to be estimated that an error due to gushing, etc., is included in a battery capacity by measuring the battery capacity according to a relationship between a battery terminal voltage and a charge current in the case of a low capacity. CONSTITUTION:When the number of rotations of E/G is low on idling, etc., capacity of a generator is low and a battery is discharged. A judgment voltage VC is obtained according to a discharge current IB2 and a battery temperature TB2 in this case. In a battery with a charging rate of 25%, the voltage VC at a battery temperature of 25 deg.C is 11v in the case of discharging at 20A, where a battery voltage VB2 during driving is compared with the voltage VC. When it is judged that the voltage VB2 is smaller than the voltage VC, the battery charging rate is 25% or less. When a driving capacity VI2 which is obtained by calculation is 255 or more, it is estimated that the above value is calculated by containing an error due to gushing, etc., thus preventing the battery from running out by taking account of this error.

Description

Detailed Description of the Invention

[0001]

2. Description of the Related Art In recent years, there is a need for a device for accurately detecting the capacity of a battery in a vehicle in order to prevent the battery from rising and improve fuel consumption.

As a conventional device for detecting the capacity of an on-vehicle battery, as shown in JP-A-53-127646, the battery charge / discharge current integrated value after that is added to the capacity obtained from the discharge characteristics at the starter start. There was a thing to detect the capacity.

However, in the above device, the rate of increase in capacity with respect to the charging current (hereinafter referred to as "charging efficiency") is not taken into consideration, and even if a decrease in the capacity of the battery can be detected, it is due to discharging. It was not possible to detect whether it was due to deterioration of the battery. Therefore, the applicant of the present application has provided a battery capacity detection device in consideration of charging efficiency in the prior application (Japanese Patent Application No. 2-175).
023). This device can measure the deviation between the integrated current value and the amount of change in capacity by comparing the battery capacity detected based on the discharge characteristics with the battery capacity measured immediately before the detection based on the integrated current. The degree of deterioration of the battery can be estimated based on the size of the deviation.

[0004]

However, in the device of the above-mentioned prior application, although the deterioration of the battery can be detected, the integrated value of the charging / discharging current is used as it is as in the prior art while the battery is in use. Since the change amount is used, the charging efficiency is not taken into consideration when the battery is used, and the capacity that changes momentarily when the battery is used cannot be accurately detected. Then, if the error amount due to gassing included in the integrated value of the charge / discharge current becomes large, it is detected as a large value even though the actual battery capacity has decreased, so that there is a problem that the battery runs out. Occurs.

Therefore, the present invention pays attention to the fact that the battery terminal voltage and the discharge current at the time of low capacity have a relatively large correlation, and the capacity of the battery is measured from the relationship between the voltage and the current, and by gassing or the like. The purpose is to estimate the error.

[0006]

In order to achieve the above object, the present invention provides a current detecting means for detecting a charging / discharging current of a battery, a voltage detecting means for detecting a terminal voltage of the battery, and the current detecting means. Current integrating means for integrating the charging / discharging current of the battery detected by, and the discharge current detected by the voltage detecting means when the discharge current of the battery detected by the current detecting means is a first predetermined value. Initial capacity setting means for setting the initial capacity of the battery based on the voltage of the battery, and battery capacity for calculating the capacity of the battery by adding the charging / discharging current integrated value to the initial capacity set by the initial capacity setting means. Calculating means and a second discharge current of the battery smaller than the first predetermined value
Error detection means for comparing the terminal voltage of the battery with a predetermined voltage, and detecting an integration error included in the integrated value by the current integration means, wherein the predetermined voltage is Set as a terminal voltage corresponding to when the discharge current is the second predetermined value, based on a characteristic that shows a relationship between the discharge current and the terminal voltage when the battery has a predetermined capacity that is extremely lower than the full charge capacity. The present invention provides a battery state detection device characterized by the above.

[0007]

When the actual battery capacity is the predetermined capacity, the terminal voltage when the discharge current of the battery is the second predetermined value is close to the predetermined voltage. At this time, if the capacity calculated by the calculating means is larger than the predetermined capacity because the integrated value by the current integrating means contains an error,
Since the terminal voltage of the battery corresponds to the capacity of the battery,
The terminal voltage should be higher than the predetermined voltage.
Therefore, when the terminal voltage detected by the voltage detecting means is lower than the predetermined voltage, the calculated battery capacity is smaller than the predetermined capacity even if the calculated capacity is larger than the predetermined capacity. It can be detected that it is included.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the device of the present invention is applied to an on-vehicle battery will be described below with reference to the drawings. In FIG. 1, 1 is an on-vehicle battery, 2 is an engine for driving a vehicle, 3 is a starter for starting an engine, 4 is a starter switch for starting a starter. Is supplied to the starter 3, the starter 3 operates and the engine 2 starts.

The engine 5 is driven by the engine 2 via a belt and a pulley (not shown) to charge the battery 1 and an electric load 8 such as a lamp, a blower motor, and a defogger.
, 6 is a current detector that detects the charging / discharging current of the battery 1, 7 is a temperature detector that detects the temperature of the battery 1, 9 is the state of the engine 2, the voltage and current of the battery 1, And the temperature, input the engine speed,
It is a control circuit using a microcomputer that controls the power generation of the generator 5 and further detects the life of the battery 1 and displays it on the display 10.

The control in the control circuit 9 will be described below. FIG. 2 is a block diagram showing processing functions in the control circuit 9,
FIG. 3 is a flow chart showing the control in the control circuit 9. Based on these, (I) battery capacity detection, (I
An explanation will be given for each item of I) error detection according to the present invention, and (III) power generation control.

(I) Battery Capacity Detection When the starter 3 is started, the discharge characteristic when the starter is driven is measured in step S1. First, the discharge current during driving of the starter is detected by the current detector 6, and this is input from the battery current detector 9a. At the same time, the battery voltage is input from the battery voltage detector 9c, and the battery voltage is measured when the discharge current has a first predetermined value (for example, 150 A). The measurement may be performed by measuring the voltage when a predetermined value is actually discharged, or may be calculated by performing (inside) the relationship between the discharge current and the voltage. The voltage thus obtained ( _denoted as V ₀ ) is a value within 1 second (usually the cranking time of the starter is within 1 second) from the start of normal discharge, so the relationship between the discharge time of the battery and the voltage obtained in advance The voltage is corrected to the voltage at the 5th second (V ₀₁ ) where the voltage stabilizes, based on the characteristic shown in FIG. This is because the battery voltage rises due to a transient phenomenon at the initial stage of discharge and becomes almost stable after about 5 seconds. Further, since the battery voltage has a temperature characteristic, the voltage V depends on the temperature obtained by the temperature detector 7.
₀₁ is corrected to obtain the capacitance detection voltage V ₀₂ .

Next, in step S2, the battery capacity when the starter is driven (hereinafter referred to as "starting capacity") is determined from the capacity detection voltage V ₀₂ , which will be described below.
The solid line in FIG. 5 shows the characteristic showing the relationship between the battery voltage and the battery capacity when the battery 1 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. Shows. As shown in the figure, when the battery capacity is small, the battery voltage becomes low. This characteristic is stored in the discharge characteristic calculation unit 9e. Then, in this characteristic diagram, a capacity corresponding to the capacity at the time of starting is obtained and is defined as a capacity at starting VI ₁ . Here, when the capacity of the battery 1 is unknown because the previous run was the first run, or the battery 1 was exchanged before the run but was not the first run, the battery capacity monitor unit 9g causes the start-up capacity VI to be determined. ₁ is set as the initial capacity VI ₄ . Current accumulator 9
d is the charge / discharge current of the battery 1 after the engine 2 is started, which is detected by the current detector 6 and is input to the battery current detector 9a, and the battery capacity monitor unit 9g
The initial capacity battery capacity during traveling by adding an integrated value of the charge and discharge current (hereinafter referred to as "running at capacity") to detect the VI _2. Then, the battery capacity monitoring unit 9g stores the last value of the running capacity VI ₂ , that is, the value when the engine is stopped, as the stopped capacity VI ₃ .

In the traveling this time, the following description will be made on the assumption that the capacity VI ₃ at stop is stored in the battery capacity monitor 9g. In step S3 in FIG. 3, the capacity VI ₃ during stop is read. In step S4, the battery capacity monitor unit 9g compares the starting capacity VI ₁ detected when the starter 3 is driven with the stopping capacity VI ₃ , and regards the smaller value as the true value, and determines this as the initial capacity VI. Set to ₄ . Normally, when the battery 1 is in a good state, the starting capacity VI ₁ and the stopping capacity VI ₃ have substantially equal values, so either of these capacities VI _{1 and} VI ₃ may be adopted. .. However, the following cases occur, so the one with the smaller value is adopted.

First, the starting capacity VI ₁ is larger than the stopping capacity VI ₃ by a predetermined value. Battery 1
When the phenomenon that the concentration of the battery liquid becomes high near the electrodes (hereinafter, referred to as “polarization”) immediately after the stratification of the battery liquid specific gravity or immediately after charging, the characteristic of the voltage with respect to the capacity is shown by the broken line in FIG. Like That is, when stratification or polarization occurs, the voltage generated with respect to the capacitance becomes higher than that in the normal state. For this reason, when stratification or polarization occurs at the time of detecting the capacity at the time of starting, the capacity detection voltage V ₀₂ is obtained with a value larger than that at the normal time, and the capacity VI ₁ at the time of starting becomes larger than the true capacity and the capacity VI ₃ at the time of stopping. Therefore, in this case, it is determined that the stopped capacity VI ₃ is close to the true capacity, and the initial capacity V 3
I set it to I ₄ .

Second, the stop capacity VI ₃ is larger than the start capacity VI ₁ by a predetermined value. This is because gassing has occurred. Here, gassing means
This is a phenomenon in which the voltage of the electrodes rises as the battery is charged and its capacity increases, and when the electrode voltage rises above a specified value, the water in the battery liquid is electrolyzed by the charging current. is there.

When gassing occurs, the running capacity VI
₂The integrated value of the battery charge / discharge current, which is the basis of
The value includes the charging current used for
Running capacity VI₂Capacity VI at stop, which is the final value of₃But
True capacity and starting capacity VI ₁Get bigger. further
As shown in Fig. 6, when the battery is deteriorated, it is a new product.
However, the charging efficiency decreases, so there is a lot of gassing.
And capacity VI when stopped ₃Will be even larger. Therefore,
In this case, the starting capacity VI₁Is determined to be close to the true capacity
And initial capacity VI_FourIs set to.

As described above, steps S1 to S4 form an initial capacity setting means. Incidentally, for the above-mentioned stratification,
In the gassing, bubbles are generated from the electrodes, and the battery liquid is agitated by the bubbles, so that stratification and gassing are unlikely to occur at the same time. Therefore, both the amounts VI ₁ at the time of starting and the amounts VI ₃ at the time of stopping do not become large, and an accurate capacity can be known by adopting the smaller value as described above.

The above-mentioned detection of the battery capacity during traveling is
This is performed in steps S5 and S6 which form a battery capacity calculating means. That is, the charge / discharge current I _B2 , the voltage V _B2, and the temperature T _B2 of the running battery 1 are read in step S5, and based on this, the charge / discharge current I _B2 is read in step S6.
The integrated with current accumulating section 9d, which was added seek traveling capacity VI ₂ and the initial capacity VI ₄ set in step 4, and stored in the battery capacity monitor unit 9g. In other words, the running capacity VI ₂ that constantly changes is constantly detected.

The detection of the battery capacity described above is an outline of the one disclosed in the above-mentioned prior application. Next, the detection of an error according to the present invention will be described. (II) Detection of Error According to the Present Invention In the battery capacity detection described above, stratification, gassing, etc. are taken into consideration when starting the engine, which means that errors that occur during traveling are collectively corrected at the time of starting. Is. However, when power generation control, which will be described later, is performed while the vehicle is traveling, since the control is performed according to the running capacity VI ₂ that changes every moment, the detected value of the running capacity VI ₂ must always be accurate. That is, if gassing occurs when charging the battery, the integrated value in step S6 becomes larger than the actually charged value, and the running capacity VI ₂ is calculated as a value larger than the actual capacity of the battery, and this error is calculated. This is because the generator is controlled based on the included running capacity, and if this error becomes extremely large, the battery may run out.

Therefore, attention is paid to the voltage when the battery is discharged, and the error during running is detected and appropriately corrected to prevent the battery from being exhausted due to the error. Generally, when the battery is appropriately charged, the change in the terminal voltage at the time of discharging is small with respect to the change in the battery capacity, as shown in FIG. This tendency is particularly strong when the discharge current is small (50 A or less). However, in the case of insufficient charging (for example, low capacity with a charging rate of 25%), the terminal voltage change at the time of discharging relative to the battery capacity change is relatively large. The relationship between the discharge current and the terminal voltage is almost as shown in the characteristic diagram of FIG. The present invention focuses on this.

First, in step S7, the battery voltage V_B2To
evaluate. Generally, the vehicle's E / G speed when idling
Is low, the generator's capacity is low and the battery
It Discharge current and battery temperature at this time (at S5,
Each I_B2, T_B2It is measured as
Ask. For example, with a 25% charged battery, 20A
If the battery temperature during discharging is 25 ° C,
The determination value Vc is obtained from 4 as 11v. And in S7,
Battery voltage V_B2Is compared with the judgment value Vc. Step S8
Is V_B2<Determining whether or not the state of Vc has continued for 1 second
It is a step and for 1 second (for repeating S5 to S12
Always) S5 discharge current I_B2,Temperature T _B2Is measured
In S7, the determination value Vc thus obtained is sequentially compared and determined.
In vehicles, electric radiator fans, etc. are momentarily
There are many loads in which a large current flows, and these loads are turned on.
-When OFF, the battery voltage stabilizes after a transition period. So
For 1 second in step 8 (necessarily 1 second
There is no need to provide a timer function for about 1 to 5 seconds)
We are trying to prevent misjudgment due to unstable voltage.

Steps S7 and S8 (error detecting means)
When it is determined that the battery voltage V _B2 is lower than the determination voltage Vc, the battery 1 is considered to have a charging rate of 25% or less. That is, if the capacity VI ₂ calculated and calculated in step S6 is equal to or higher than 25% of the charging rate, it can be estimated that this is calculated including an error due to gassing or the like. In step S9, the running capacity is corrected in consideration of this error. In the present embodiment, a predetermined value VI _C (for example, 1 [Ah]) is subtracted from the battery capacity VI ₂ that is found to be large. V
Based on the capacity VI ₂ corrected by I _C , the power generation control described below is performed (the power generator is controlled by detecting the capacity decrease to increase the charge). Also, steps S5 to S1
2 is repeated while the key SW is on, and the above-mentioned VI _C (1Ah)
If the correction amount for one time is insufficient, the relationship of V _B2 <Vc is established again in S7, and again V _C is corrected in S9. In this way, the correction of VI _C is repeated, and finally the current integration capacity VI ₂ is corrected to an accurate value. By continuously performing such a correction, it is possible to correct the capacity and prevent the malfunction of the device due to the battery voltage drop.

(III) Power Generation Control The power generation control in step S10 is the same as that disclosed in the prior application, and is mainly as follows.

(1) The power generation is increased so as not to fall below the minimum required capacity (for example, a charging rate of 25%), and engine start failure and battery exhaustion are prevented. When the amount of power generation is insufficient only by controlling the generator, the idle speed is increased (see FIG. 7).

(2) Acceleration is improved and fuel consumption is improved by controlling the amount of power generation according to E / G and the battery state. (3) The power generation is controlled so as not to greatly exceed the capacity at which gassing starts to occur, the life of the battery is improved, and the decrease of the battery electrolyte is prevented.

In step S11, when the running capacity VI ₂ becomes 25% or less of the charging rate, the alarm unit 9i gives an alarm indicating that the battery is dead. When it is determined that the key switch is turned off in step S12, in step S13, the last value of the running time of capacity VI _2, and stored as stop-time capacity VI ₃ in the battery capacity monitor unit 9 g, prepare for the next run.

As described above, in the embodiment, it is possible to estimate the error amount of the battery capacity calculation value including the error due to the gassing etc. when the vehicle is running. Therefore, the battery exhaustion can be prevented by considering the error amount. You can

Although the running capacity VI ₂ is corrected in step S9 in the above embodiment, the determination value for power generation control (or battery alarm) may be corrected without this correction. That is, when a decrease in the battery voltage is detected in steps S7 and S8, a determination value (for example, the determination value 8Ah set to determine the battery up alarm) is set.
) Is increased by 1 AH to 9 AH and compared with the battery capacity VI ₂ . In other words, by performing the power generation increase control in step S10 earlier, it is possible to prevent the malfunction of the device and the battery exhaustion due to the battery voltage drop. Further, as in the case of the above-described embodiment, if the voltage drops even after one correction (increase of 1 AH in the embodiment), the correction is repeated. Also, step S
The correction performed in 9 is performed only when the capacity detection value obtained by the composite of the discharge characteristic of the battery and the integrated current at the time of engine start includes an error caused by various factors such as a gassing phenomenon. Anything can be used as long as it can prevent the worst situation such as equipment malfunction due to rising or voltage drop.At the time of the most restart after the engine is stopped, the correction of the judgment value performed before the last engine stop is eliminated and the initial value (above In the example, it may be returned to 8Ah). Further, in the present invention, the correction with the relatively small correction value (1 AH in the embodiment) is performed while the condition of S7 is satisfied (the battery voltage is lower than the determination value).
Since the battery capacity is corrected by suddenly satisfying the condition, it is possible to prevent a sudden change in power generation control or idle speed control (for example, a rapid increase in idle speed).

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment showing a vehicle charging control device using a battery state detection device of the present invention.

FIG. 2 is a block diagram showing a processing function of a control circuit 9 of the apparatus of the above embodiment.

FIG. 3 is a flowchart showing a process in the control circuit 9.

FIG. 4 is a characteristic diagram showing a relationship between a battery and a discharge current used for explaining the error detection of the present invention.

FIG. 5 is a characteristic diagram showing a relationship between a battery capacity and a battery voltage when the battery is discharged.

FIG. 6 is a characteristic diagram showing a relationship between a battery capacity that actually increases when a battery is charged and an integrated value of a battery charging current.

FIG. 7 is a diagram showing the relationship between the idle speed setting number and the battery capacity.

[Explanation of symbols]

 1 Battery 6 Current Detector 9 Control Circuit 9a Battery Current Detector 9c Battery Voltage Detector 9d Current Accumulator 9e Discharge Characteristic Calculator 9g Battery Capacity Monitor

Claims (1)

[Claims] 1. A current detection means for detecting a charge / discharge current of a battery, a voltage detection means for detecting a terminal voltage of the battery, and a current integration for integrating a charge / discharge current of the battery detected by the current detection means. Means and an initial capacity for setting an initial capacity of the battery based on the voltage of the battery detected by the voltage detection means when the discharge current of the battery detected by the current detection means has a first predetermined value. Setting means, battery capacity calculating means for calculating the capacity of the battery by adding the charging / discharging current integrated value to the initial capacity set by the initial capacity setting means, and the discharging current of the battery is the first predetermined value. When the battery voltage is a second predetermined value smaller than the predetermined value, the terminal voltage of the battery is compared with the predetermined voltage, and an integrated error included in the integrated value by the current integrating means. Error detecting means for detecting, and the predetermined voltage is a discharge current based on a characteristic indicating a relationship between a terminal voltage and a discharge current when the battery has a predetermined capacity that is extremely lower than the capacity when the battery is fully charged. Is set as the terminal voltage corresponding to the second predetermined value, the battery state detecting device.