JP3457227B2 - Battery remaining capacity measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery remaining capacity measuring apparatus, and more particularly to a battery remaining capacity measuring apparatus capable of accurately obtaining and displaying a remaining capacity of a battery even when the load fluctuates greatly.

[0002]

2. Description of the Related Art Generally, a battery has a discharge characteristic which varies depending on the fluctuation of the connected load, the ambient temperature, the secular change and the like. Therefore, the remaining capacity of the battery also differs depending on the load fluctuation, the ambient temperature, the secular change, and the like.

For example, as shown in FIG. 14, in the case of a battery, even if the temperature T is constant at 20 degrees, the discharge characteristics differ between 10 A discharge, 20 A discharge, ... Assuming that the range is 25V to 20V, 160 A is discharged for 10 minutes, and 30 A is discharged for 4 minutes.
It becomes unusable in 0 minutes. That is, the discharge rate of the battery varies depending on the load variation, and the remaining capacity of the battery also varies.

In particular, an electric vehicle is driven by a battery, and therefore accurate prediction of the remaining capacity of the battery is required. There are the following methods for measuring the remaining capacity of the battery. (1) A method in which the amount of power actually supplied from the battery to the load side is measured and integrated, and the remaining capacity is predicted from this integrated power value and the amount of power during charging. (2) A method of predicting the remaining capacity by measuring the terminal voltage when a discharge current flows from the battery terminal to the load side. (3) A method of predicting the remaining capacity by measuring the specific gravity of the electrolytic solution in the battery. (4) A method of predicting the remaining capacity by releasing the battery from the load and measuring the terminal voltage in the open circuit state. Etc.

However, the method (4) cannot be applied to a system such as an electric vehicle because the load and the battery must be electrically separated and measured. Also,
The method (3) utilizes the fact that the specific gravity of the electrolytic solution is reduced by discharging, but in general, since a specific gravity sensor must be provided in the battery, it is necessary to improve the electrolytic cell. , Not suitable for electric vehicles.

Therefore, in general, the above (1) or (2)
This method is the mainstream in electric vehicles. An example of the battery remaining capacity meter of Japanese Patent Laid-Open No. 6-34727 adopting such a system will be described.

FIG. 15 is a schematic configuration diagram of a conventional battery remaining capacity meter. As shown in the figure, the conventional battery remaining capacity meter 1
0 is a voltmeter 9 and an ammeter 7 when the switch 2 is turned on.
Therefore, when the current from the main battery 3 exceeds a predetermined value, V-
In the I characteristic calculation means 10a, the current and voltage at that time are obtained from the detection data from the temperature sensor 4 to obtain the VI characteristic.

Then, there is a good correlation between the VI characteristics obtained in such a state and the remaining capacity of the battery. Therefore, the relationship between the two is obtained in advance and stored, and the remaining capacity of the main battery is obtained by the remaining capacity calculating means 10b from the actually obtained VI characteristic and the stored relationship, and the display unit 11 is obtained.
Was to be displayed.

[0009]

However, with respect to changes in voltage and current, the degrees of changes do not always correlate. For example, comparing the waveforms of the voltage and the current in FIGS. 16A and 16B, there is a portion where the relationship between the voltage and the current is not correlated as shown by A in FIG. 16C.

It is considered that this is because when there is a rapid change in the load, the terminal voltage of the battery does not follow the rapid change in the discharge current of the battery.

Therefore, when the load fluctuates drastically, the degree of change in current and voltage has no correlation.

However, since there is a good correlation between the VI characteristic and the remaining capacity of the battery, the relationship between the two is preliminarily obtained and stored, and the actually obtained VI characteristic is stored. Since the remaining capacity of the main battery is obtained from the relationship, there is a problem that an accurate remaining capacity of the battery cannot be obtained when the load fluctuates drastically.

Therefore, there is a problem that the remaining capacity of the battery displayed when the load fluctuates drastically is not reliable.

The present invention has been made in order to solve the above problems, and an object of the present invention is to obtain a battery remaining capacity measuring device which can accurately determine the remaining capacity of a battery even when the load changes rapidly. To aim.

[0015]

SUMMARY OF THE INVENTION A battery remaining capacity measuring apparatus of the present invention comprises a detection section including a voltage sensor for detecting a terminal voltage of a battery connected to a load and a current sensor for detecting a current flowing through the load. Having a battery remaining capacity measuring device for displaying the obtained remaining capacity of the battery, the detection voltage and the detection current are sampled every time a fixed time elapses, and each time a fixed number is reached, the averaged value is obtained. Defined in the coordinate system of the voltage-current axis, and every time a predetermined number of the averaged detected voltage and the averaged detected current are collected in the coordinate system, a voltage-current change tendency notifying that the scattered data is calculated. The calculation unit, reading the scattered data, the minimum error between the plurality of averaged detected voltage and the averaged detected current of the scattered data is obtained by the least squares method in the coordinate system, Each time the voltage-current approximate straight line calculation unit that defines the voltage-current approximate straight line defining the voltage-current approximate straight line in the period in which the equalized detected voltage and the averaged detected current are collected by the predetermined number, each time the voltage-current approximate straight line is obtained, When a perpendicular line is drawn from the intersection of a preset reference current value and the voltage-current approximation straight line to the voltage axis of the coordinate system, the intersection point intersecting the voltage axis is displayed by obtaining the remaining capacity based on the voltage value. The gist of the present invention is to include a battery remaining capacity calculation unit.

In addition to the voltage sensor and the current sensor, the detection unit includes a temperature sensor for detecting the temperature of the battery, and the temperature value of the battery is associated with the voltage value and the ratio of the remaining capacity. The battery remaining capacity calculation unit reads the voltage value of the voltage axis of the coordinate system and the temperature of the temperature sensor, each time the voltage-current approximate straight line is obtained, and the voltage The gist is to display the ratio of the remaining capacity of the table corresponding to the value and the temperature as the remaining capacity.

Further, every time a predetermined number of the averaged detected voltages and detected currents are gathered, a correlation coefficient is obtained, and the correlation coefficient is the first reference negative correlation coefficient and the second reference negative correlation coefficient ( When the correlation is large or small, the first reference negative correlation coefficient> the second reference negative correlation coefficient: numerically, the value of the first reference negative correlation coefficient <the value of the second reference negative correlation coefficient) On the other hand, when the value of the correlation coefficient is numerically larger than the value of the second reference negative correlation coefficient, a determination unit that determines that the load is stopped. When the load is determined to be stopped by the determination unit, and the ignition is turned on, the remaining capacity calculation unit stops the voltage-current approximate straight line calculation unit, and the voltage sensor. A method for determining the remaining capacity based on the detected voltage from the sensor and the detected current from the current sensor. And summarized in that with a.

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiments, an example of using the battery residual capacity measuring device of the present invention when measuring the residual capacity of a battery mounted on an electric vehicle will be described.

First Embodiment FIG. 1 is a schematic configuration diagram of the first embodiment. In the figure,
1 to 11 are the same as those in FIG. Reference numeral 12 is a detection value input circuit unit. The detection value input circuit unit 12 uses the I / O
13, the LPF 15 and the A / D 17, the battery discharge current and the terminal voltage are input as the detection voltage and the detection current from the voltage sensor 9 and the current sensor 7, noise is removed, and digital conversion is performed.

Reference numeral 19 is a computer. The program configuration of the computer 19 is the voltage-current change tendency calculation unit 2
1, a battery remaining capacity calculation unit 23, a voltage-current approximate straight line calculation unit 29, and the like. The operation is performed by the electric power from the sub-battery in accordance with the operation of the ignition key.

The voltage-current change tendency calculating section 21 comprises an average number judging means 27 and a voltage-current averaging means 25.

The voltage-current averaging means 25 inputs the digital detection current and voltage of the battery 3 from the detection value input circuit section 11, and the first output signal is the average number judging means 27.
Each time it is output from, the detection current and the detection voltage are sampled, and each time it is added to the previous value,
The sum of the voltage data and the current data is stored in the memory 31, and each time the second output signal is output from the average number determination means 27, the sum of the voltage data and the sum of the current data of the memory 31 is added. Are averaged based on the above, and are stored in the memory 33 separately for each averaging. Also, every time the third output signal is output, the stored values in the memory 31 and the memory 33 are cleared.

The average number judging means 27 outputs the first output signal to the voltage-current averaging means 25 every 100 ms while the load operation signal indicating that the electric vehicle is in operation is being output. A second output signal is output to the voltage-current averaging means 25 each time the number of detected currents and voltages added reaches 100 (every 10 seconds). Furthermore, when the average current value and the average voltage value in the memory 33 become 100, that is, when the average current value becomes approximately 16 minutes, the third output signal is calculated as the voltage-current averaging means 25 and the voltage-current approximate straight line calculation. It is output to the unit 29.

That is, the voltage-current averaging means 25 and the average number determining means 27 obtain the scatter data of the discharge current and the voltage of the battery 3 every predetermined period.

The voltage-current approximate straight line calculation unit 29 reads a plurality of average voltage values and average current values from the memory 33 every time a third output signal is output after 16 minutes have elapsed, and the error of both is read. Then, a and b for minimizing the error are obtained, and a voltage-current approximate linear function (Y = aX + b) for 16 minutes is obtained based on the a and b.

Each time the voltage-current approximate straight line calculating unit 29 obtains the voltage-current approximate linear function, the battery remaining capacity calculating unit 23 converts the predetermined discharge current value Y into a linear expression (Y = aX + b). Based on this, the voltage value X on the voltage-current axis is specified, and this voltage value X is displayed on the display unit 11.

The operation of the battery residual capacity measuring device configured as described above will be described below. FIG. 2 is a flowchart explaining the operation of the first embodiment.

First, the computer checks each part with the supply of electric power from the sub-battery in response to the operation of the ignition key, and performs the initial setting such as storing the ROM program in the RAM (S201). Then, the average number determination means 27 determines whether or not the electric vehicle is stopped based on the load operation signal (S203).

The load operation signal is output, for example, when the accelerator operation amount, the speed pulse amount, the wiper rotation amount, or the like is above a predetermined level, or when the air conditioner compressor or the like is performing a switching operation. Is something
When there is this load operation signal, it is determined that the electric vehicle is operating, and if there is no output, it is determined that the electric vehicle is stopped.

There is also a case where the judgment whether the operation is being performed or the operation is stopped is made by the correlation and the load operation signal is outputted. This example will be described in a fourth embodiment described later.

Next, when the vehicle is not stopped, that is, when it is determined that the vehicle is operating, the average number determination means 27 determines whether 100 ms has elapsed (S205). When 100 ms has elapsed, the first output signal is output. It outputs to the voltage-current averaging calculation means 25, and the voltage-current averaging calculation means 25 outputs the battery voltage (VOLT) from the detection value input circuit unit 12,
Read discharge current (CURR) (S207), 100ms
The sampling data (discharging current, voltage) at the time is added to the previous value and stored in the memory 31 as the total value of the voltage data and the total value of the current data, and the average number determination means 27 counts the number of additions ( S209).

Next, the average number judging means 27 judges whether the count value N is 100, that is, whether 10 seconds have elapsed (S211), and if 10 seconds has not elapsed, the control is moved to step S203 and the above-mentioned is performed. Then, the current-voltage averaging calculation means 25 adds the discharge current and the voltage for each 100 ms, and counts the number of additions.

Next, when the average number determination means 27 has passed 10 seconds, that is, when the number of times of addition of the detected current and the detected voltage has reached 100, the second output signal is changed to the current-voltage averaging means 25. Then, the 100 detected currents (sum of current data) and voltages (sum of voltage data) during 10 s are averaged and stored in the memory 33 (S213). Then, it is determined whether or not the average value in step S213 is 100, that is, whether or not about 16 minutes have elapsed (S215), and when about 16 minutes have not elapsed, control is transferred to step S203,
As described above, 100 detected currents and voltages during 10 s are added, and 100 average values based on the number of additions are obtained.

Therefore, the voltage-current averaging means 25 and the average number judging means 27 scatter a plurality of voltages and currents in a plurality of discharge characteristics according to load variations as shown in FIG. 14 during 16 minutes. The obtained data are obtained on the voltage and current axes as shown in FIG.

Further, as shown in FIG. 3, the current and voltage of the battery 3 have such characteristics that the voltage drops with the passage of time. Therefore, the following processing is performed using the voltage-current approximate straight line calculation unit 29.

In step S215, the average number determination means 27
When it is determined that the time becomes about 16 minutes, the third output signal is output to the voltage-current averaging means 25 and the voltage-current approximate straight line calculation unit 29. The voltage-current approximate straight line calculation unit 29 reads 100 average voltage values and average current values from the memory 33, and takes the sum of squares of both errors (least square method), a of the linear expression (Y = aX + b), Find b.

Then, the battery remaining capacity calculation unit 23
A voltage value is specified from this linear expression (Y = aX + b) and a predetermined discharge current value (S217).

This means that, as shown in FIG. 3, the voltage of the voltage-current approximate linear function corresponding to the discharge current value Y on the voltage axis and the current axis is specified.

When the discharge current at this time is 10 A, the voltage shown in FIG. 3 has a voltage value slightly higher than 24 V when calculated based on the linear expression Y = aX + b.

Here, how to obtain the approximate straight line will be described to some extent. For example, let S be the sum of the squared errors of both current and voltage,

[Equation 1] Next, each time the specified voltage value is obtained, the battery remaining capacity calculation unit 23 causes the display unit 35 to display the specified voltage value (S219).

Next, it is judged whether or not it is the end, that is, whether the ignition is OFF, and if it is not the end, the control is moved to step S203, and similarly to the above, during the operation,
Every time the scatter data of the voltage and the current is obtained within a predetermined time, a VI approximation line that minimizes the error between the current and the voltage is obtained from the scatter data, and the VI approximation line is obtained. The voltage is specified and displayed based on a straight line and a predetermined reference discharge current value.

Therefore, since each VI approximated straight line obtained during operation is an approximated straight line function in which fluctuations in voltage and current are sufficiently taken into consideration, the voltage value specified each time the VI approximated straight line is obtained. Is a value representative of the terminal voltage at a constant reference discharge current.

Further, when the fluctuation is so great that the rate of change in the voltage and the current is too great, more variation data can be obtained, so that the change tendency can be noticed remarkably.

Embodiment 2 Generally, in a battery, the VI characteristic changes abruptly depending on the temperature. In the first embodiment, since the voltage value itself is a value that includes a temperature change, the rest can be considered by displaying the voltage if the vehicle is operated for a long period of time. In the second embodiment, the remaining capacity of the battery is calculated and displayed in consideration of the temperature change.

FIG. 5 is a schematic configuration diagram of the second embodiment.
In the figure, 1 to 33 are the same as those in FIG.
A temperature sensor 4 is provided in the battery 3 and detects the temperature.

The program configuration of the computer 41 is shown in FIG.
The voltage / current change tendency calculation unit 21 and the battery remaining capacity calculation unit 44 similar to the above are included.

When the terminal voltage of the battery 3 is specified on the basis of the approximate linear function of the voltage-current approximate linear calculation unit 29, the battery remaining capacity calculation unit 44 reads the temperature detected by the temperature sensor 4 for the battery, and reads this temperature. Then, the remaining capacity corresponding to the specific voltage is read from the memory 44 and output to the display unit 11.

As shown in FIG. 6, the memory 44 stores the remaining capacity according to the temperature of the battery 3 and the terminal voltage of the battery 3. Although the correspondence table of FIG. 6 is a table, it may be stored as a function indicating the remaining capacity according to the temperature of the battery 3 and the terminal voltage of the battery 3.

The operation of the battery residual capacity measuring apparatus of the second embodiment having the above-described structure will be described below. FIG. 7 is a flowchart explaining the operation of the second embodiment.

As shown in FIG. 7, steps S701 to S717 are steps S201 to S2 of FIG.
The same process as 17 is performed, and the voltage-current change tendency calculation unit 2
1 voltage-current averaging means 25, average number determination means 27
Similarly to the above, the voltage-current approximate straight line calculation unit 29 reads the terminal voltage of the battery 3 from the voltage sensor 9 and the current sensor 7 and the current flowing through the load every 100 ms, and reads 10
Every time s elapses, the values are added and averaged, 100 averaged voltages and currents are obtained, and data of the voltage-current scattering is obtained. Based on the scattering data, the voltage-current approximate straight line is obtained. The function is obtained, and the terminal voltage X of the battery 3 is specified from the voltage-current approximate linear function and the reference discharge current (S
701-S717).

Then, the battery remaining capacity calculation processing unit 44
When the specific voltage X is input, reads the battery temperature of the temperature sensor 4 from the detection value input circuit unit 12 (S719),
The remaining capacity corresponding to the specific voltage X and the battery temperature is read from the memory 42 (S721) and displayed on the display unit 11 (S723).

Next, it is judged whether or not it is finished (S72).
5) If not finished, control is transferred to step S703, and the same processing as above is performed.

Therefore, the battery remaining capacity calculation processing unit 44
Is the memory 4 from the specific voltage obtained by the approximate linear function.
Since the ratio corresponding to the temperature, voltage and remaining capacity ratio of 2 is displayed as the remaining capacity, the structure of the device is simplified and the remaining capacity is displayed at low cost and with high accuracy.

Further, since the remaining capacity is based on the temperature and the voltage, the driver does not have to estimate the remaining capacity based on the displayed voltage value. You can know the capacity.

Third Embodiment FIG. 8 is a schematic configuration diagram of the third embodiment. In the figure,
1 to 33 are the same as those in FIG. Reference numeral 52 is a battery remaining capacity calculation unit. Battery remaining capacity calculator 52
Is equipped with a start-up determination means 54, and operates the voltage-current change tendency calculation unit 21 and the voltage-current approximate straight line calculation unit 29 to obtain an approximate straight line function in the same manner as above when a load operation signal is input. The voltage is specified, and the remaining capacity is calculated based on this voltage.

When the load is not operating, the voltage-current change tendency calculation unit 21 and the voltage-current approximate straight line calculation unit 29 are stopped, and the remaining capacity of the battery is calculated based on the detected voltage and the detected current. Display in search. In addition, “during load operation” is output when a change in load is greater than or equal to a predetermined value, and load operation is stopped when the change in load is less than or equal to a predetermined value (however, when the device is in the ON state) It is in a state.

The start-judgment means 52 is provided as a voltage-current approximation straight line function, in which a highly accurate voltage-current approximation straight line can be obtained only when the voltage and current vary to some extent. However, for example, when the electric vehicle is stopped (however, the ignition key is in the ON state), there is almost no change in the load. Therefore, as shown in (a) and (b) of FIG. Since it does not change, the VI characteristic hardly varies as shown in FIG. 9 (c).

Therefore, the voltage-current change tendency calculation unit 21
This is to stop the voltage-current approximate straight line calculation unit 29.

Next, the operation will be described. FIG. 10 is a flowchart explaining the operation of the third embodiment. The battery remaining capacity calculation processing unit may be that of the second embodiment in which the remaining capacity is calculated based on the battery temperature and the voltage value, but in this example, the battery remaining capacity calculation processing unit of the first embodiment is used. The case will be described.

As shown in FIG. 10, steps S1001 to S1001
Step S1021 is a process similar to steps S201 to S221 in FIG. 2, and the voltage-current averaging means 25, the average number determination means 27, and the voltage-current approximate straight line calculation section 29 of the voltage-current change tendency calculating section 21 are processed by Similar to the above, the battery 3 from the voltage sensor 9 and the current sensor 7
The terminal voltage and the current flowing through the load are read every 100 ms, and the values are added and averaged until 10 s elapse, and 100 averaged voltages and currents are obtained to obtain the voltage-current scattering data. A voltage-current approximation linear function is obtained based on this scattering data, the terminal voltage X of the battery 3 is specified from the voltage-current approximation linear function and the reference discharge current, and the remaining capacity is obtained (S1001 to S1021).

Further, when the start determination means 52 determines in step S1003 that the electric vehicle is stopped, that is, when the load operation stop signal is output, the start determination means 5
2 stops the voltage-current change tendency calculation unit 21 and the voltage-current approximate straight line calculation unit 29, and the battery remaining capacity calculation unit 52 samples the current and voltage from the detection value input circuit unit 12, The remaining capacity is obtained and displayed based on the value of (S1023). Therefore, an accurate remaining capacity can always be obtained even when the terminal voltage and discharge current of the battery fluctuate remarkably or conversely.

Fourth Embodiment FIG. 11 is a schematic configuration diagram of the fourth embodiment. In the figure, 1 to 54 are the same as above. The computer 56 includes a voltage-current change tendency calculation unit 21, a voltage-current approximate straight line calculation unit 29, a battery remaining capacity calculation unit 54, and a determination unit 58. The determination unit 58 is activated in response to the input of the third output signal, obtains a correlation coefficient from the scattered data of the detected voltage and the detected current stored in the memory 33, and determines the correlation coefficient and the first Based on the reference negative correlation coefficient and the second reference negative correlation coefficient, it is determined whether the load fluctuates by a predetermined amount or more or is less than a predetermined value, and the determination result is output to the battery remaining capacity calculation unit 54. When the obtained correlation coefficient is between both reference negative correlation coefficients, a signal indicating that the remaining capacity of the battery 3 is below a predetermined level is output to the display unit 11. As shown in FIG. 13, the first and second reference correlation coefficients are, for example, -0.9 for the first reference negative correlation coefficient and -0.8 for the second reference negative correlation coefficient.

As shown in FIG. 13, these reference negative correlation coefficients indicate that the battery has a negative correlation when the load is fluctuating to some extent, and with the passage of time, the battery has a negative correlation with the voltage. The correlation distribution of the current is as shown in FIG. Therefore, the first reference correlation coefficient is set to a value close to a strong negative correlation (for example, −0.9), and when the negative variation is small, the correlation coefficient is a weak negative correlation, as shown in FIG. Is a value close to (for example, -0.8). That is, both reference correlation coefficients are set to the first reference correlation coefficient> the second reference correlation coefficient.

Next, the operation will be described. FIG. 12 is a flowchart explaining the operation of the second embodiment. As shown in FIG. 12, steps S1201 to S1213 are the same processes as steps S201 to S215 in FIG. 2, and the voltage-current averaging means 25 and the average number determining means 27 of the voltage-current change tendency calculating unit 21 are used. , Voltage sensor 9
And, the terminal voltage of the battery 3 from the current sensor 7 and the current flowing through the load are read every 100 ms, added and averaged until 10 s has elapsed, 100 averaged voltages and currents are obtained, and the voltage-current is obtained. Create a scatter table of the scattered leaflets. Then, the third output signal is output to the determination unit 58 and activated (S1201 to S1213).

Next, the determination unit 58 obtains the correlation coefficient from the voltage-current scattering data of the memory 33 (S121).
5).

To obtain this correlation coefficient r, the correlation coefficient calculation unit reads a plurality of average voltage values and average current values for 100 s from the memory 33, and calculates both correlation coefficients r as follows. (S217).

[0079]

[Equation 2] Next, it is determined whether the correlation coefficient r is −0.9 or less (S1217). When it is determined to be −0.9 or less, it is determined that the vehicle is operating (S1219), the voltage-current approximate linear calculation unit 29 is activated, and the current-voltage approximate linear function is obtained by the least square method. (S1221).

Next, the battery remaining capacity calculation unit 54 is informed that the vehicle is operating, and the battery remaining capacity is calculated as described above by the current-voltage approximate linear function (S1223). Then, the computer 56 determines whether or not the ignition key is OFF (S1225),
If it is not OFF, the control is moved to step S1203 and the above operation is performed.

When the correlation function r calculated from -0.9 in step S1217 is large, for example, r is -0.85.
If it is, it is determined whether it is −0.8 or less (S122).
7).

When −0.8 or less, the obtained correlation coefficient r
Is determined to be between -0.9 and -0.8 (S122
9) The display unit 11 is caused to warn that the remaining capacity is low, and control is passed to step S1225 (S1225).

When it is determined that the correlation coefficient r obtained in step S1227 is larger than -0.8, for example,-
When 0.7, it is determined that the vehicle is stopped (S123
3) Stop the voltage-current approximate straight line calculation unit 29 and notify the battery remaining capacity calculation unit 54 that the vehicle is stopped.

Then, in the battery remaining capacity calculation section 54,
The remaining capacity in voltage and current stable states is calculated (S12
35).

That is, in the fourth embodiment, as shown in FIG. 13, when the ignition key is operated, the correlation coefficient with the passage of time is obtained, and the correlation coefficient is close to a non-correlation value (second value). (Reference correlation value), it is determined that the vehicle has stopped and no processing such as warning is performed. When the statistical reference value is less than or equal to the first reference correlation value, the low battery warning is displayed. Output to.

Therefore, even if the temperature sensor is not provided and the battery operation can be accurately detected without detecting, for example, the operation amount of the accelerator, the speed pulse amount, the rotation amount of the wiper, whether the discharge current has flowed more than a predetermined value, and the like. It is possible to make a determination without storing a map of discharge characteristics or the like for determining a decrease in the ROM.

Even without using such a map,
Since the low battery can be detected easily and easily, it is not necessary to change the contents of the ROM even if the battery is replaced or the load to be measured is changed.

Further, the judging section of the fourth embodiment may be provided in the battery remaining capacity measuring apparatus of the first, second or third embodiment.

In each of the above-mentioned embodiments, the remaining capacity of the battery of the electric vehicle has been described as an example, but the battery remaining capacity measuring device of the present invention may be used in a portable personal computer, a mobile phone or the like.

In each of the above-mentioned embodiments, the voltage-current approximate straight line is obtained by averaging, but it is substituted into a predetermined approximate linear formula to perform addition, integration, division, etc. You may ask.

In the above embodiment, the collection time is set to 1
Six minutes was used, but it may be shorter or longer depending on the device used.

[0092]

As described above, according to the present invention, the voltage-current approximation straight line obtained during operation is one in which the voltage and current fluctuations of the battery are sufficiently taken into consideration, and the voltage-current approximation straight line is obtained. The voltage value specified each time becomes a value that represents the terminal voltage of the battery at a constant reference current, and even if there is no correlation in the rate of change between the detected voltage and current, the obtained voltage is highly accurate. .

Also, every time the scattered data is output,
Since the voltage-current characteristic calculation unit obtains an approximate straight line by the method of least squares for the error between a plurality of voltages and currents, even if the load changes drastically, the obtained straight line has an effect that the error is small. Has been obtained.

Each time the voltage-current approximation linear function is obtained, a voltage value corresponding to a predetermined discharge current is calculated from the voltage-current approximation linear function, and this voltage value is used as the remaining capacity of the battery. Since the display is made, it is possible to obtain an effect that it can be seen that the remaining capacity is lowered by observing the change in the displayed voltage.

Further, a table in which the temperature value of the battery is associated with the voltage value and the ratio of the remaining capacity is provided, and each time the voltage-current approximate straight line is obtained, the obtained voltage value of the voltage axis and the temperature sensor By reading the temperature and displaying the ratio of the remaining capacity in the table corresponding to the voltage value and the temperature as the remaining capacity, the calculation can be simplified even with the temperature sensor.

Further, a correlation coefficient is calculated every time a predetermined number of averaged detected voltages and detected currents are gathered. When this correlation coefficient is numerically larger than the value of the second reference negative correlation coefficient,
Determine that the load is stopped. And it is determined that it is stopped,
And the ignition is turned on, the voltage-
The calculation of the current approximation line is stopped, and the remaining capacity is obtained based on the detected voltage from the voltage sensor and the detected current from the current sensor. Therefore, the remaining capacity can be accurately obtained regardless of the fluctuation of the load.

[0097]

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment.

FIG. 2 is a flowchart illustrating the operation of the first embodiment.

FIG. 3 is an explanatory diagram illustrating a tendency of a VI characteristic of a battery.

FIG. 4 is an explanatory diagram illustrating a tendency of a terminal voltage of a battery.

FIG. 5 is a schematic configuration diagram of a second embodiment.

FIG. 6 is an explanatory diagram showing the relationship between the temperature, the voltage, and the remaining capacity of the memory 42.

FIG. 7 is a flowchart illustrating the operation of the second embodiment.

FIG. 8 is a schematic configuration diagram of a third embodiment.

FIG. 9 is an explanatory diagram illustrating a correlation between a voltage and a current when a load change is very small.

FIG. 10 is a flowchart illustrating the operation of the third embodiment.

FIG. 11 is a schematic configuration diagram of a fourth embodiment.

FIG. 12 is a flowchart illustrating the operation of the fourth embodiment.

FIG. 13 is an explanatory diagram illustrating determination of a correlation coefficient according to the third embodiment.

FIG. 14 is an explanatory diagram illustrating discharge characteristics of a battery.

FIG. 15 is a schematic configuration diagram of a conventional battery remaining capacity meter.

FIG. 16 is an explanatory diagram when there is no correlation between voltage and current.

[Explanation of symbols]

1 car load 3 battery 7 Current sensor 9 Voltage sensor 12 Detection value input circuit 21 Voltage-current change tendency calculator 23 Battery Remaining Capacity Calculation Unit 25 voltage-current averaging means 27 Average number determination means 29 Voltage-current approximate straight line calculation unit 52 Start-up determination means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenichi Shimoyama               1500 Onjuku, Susono City, Shizuoka Prefecture Yazaki General Stock Company               In-house (72) Inventor Ryo Kumagai               1500 Onjuku, Susono City, Shizuoka Prefecture Yazaki General Stock Company               In-house (72) Inventor Yoshihide Takada               1500 Onjuku, Susono City, Shizuoka Prefecture Yazaki General Stock Company               In-house                (56) References JP-A-3-200082 (JP, A)                 JP-A-6-34727 (JP, A)                 JP-A-6-59003 (JP, A)                 JP-A-2-162275 (JP, A)                 Actual Kaihei 4-115084 (JP, U)

Claims (3)

(57) [Claims] 1. A display unit for displaying the obtained remaining capacity of the battery, comprising a detection unit including a voltage sensor for detecting a terminal voltage of a battery connected to a load and a current sensor for detecting a current flowing in the load. In the battery residual capacity measuring device, the detection voltage and the detection current are sampled every time a certain time has elapsed, and each time a constant number is sampled, averaged and defined in the coordinate system of the voltage-current axis, and the average Each time a predetermined number of the detected voltage and the averaged detected current that have been converted are collected in the coordinate system, a voltage-current change tendency calculation unit that notifies the calculation of scatter data, and the scatter data is read, and the scatter data is read. A minimum error between a plurality of the averaged detection voltages of the data and the averaged detection current is obtained by the least square method in the coordinate system, and the averaged detection voltage and the averaged detection current are in front of each other. A voltage-current approximation straight line calculation unit that defines a voltage-current approximation straight line in a period in which a predetermined number of data are collected, and a preset reference current value and the voltage-current approximation line each time the voltage-current approximation straight line is obtained. A battery having a battery remaining capacity calculation unit for displaying and displaying a remaining capacity based on a voltage value at an intersection intersecting with the voltage axis when a perpendicular line is drawn from the intersection with a straight line to the voltage axis of the coordinate system. Remaining capacity measuring device. 2. The detection unit includes a temperature sensor for detecting the temperature of the battery in addition to a voltage sensor and a current sensor, and associates the temperature value of the battery with the voltage value / remaining capacity ratio. The battery remaining capacity calculation unit reads the voltage value of the voltage axis of the coordinate system and the temperature of the temperature sensor, each time the voltage-current approximate straight line is obtained, and the voltage The ratio of the remaining capacity of the table corresponding to the value and the temperature is displayed as the remaining capacity.
The battery residual capacity measuring device described. 3. A correlation coefficient is calculated every time a predetermined number of the averaged detected voltages and detected currents are gathered, and the correlation coefficient is the first reference negative correlation coefficient and the second reference negative correlation coefficient ( When the correlation is large or small, the first reference negative correlation coefficient> the second reference negative correlation coefficient: numerically, the value of the first reference negative correlation coefficient <the value of the second reference negative correlation coefficient) On the other hand, when the value of the correlation coefficient is numerically larger than the value of the second reference negative correlation coefficient, a determination unit that determines that the load is stopped. The remaining capacity calculation unit, when the determination unit determines that the load is stopped, and the ignition is turned on, the voltage-current approximate straight line calculation unit is stopped, the voltage sensor Means for obtaining the remaining capacity based on the detected voltage from the sensor and the detected current from the current sensor. Battery remaining capacity measuring apparatus according to claim 1 or 2, wherein that.