JPH08146106A - Computing device for remaining battery capacity of motor vehicle - Google Patents

Abstract

PURPOSE: To make it possible to compute remaining battery capacity without requiring any dedicated parts, device, and the like specially by obtaining the remaining capacity based on an integration value of a battery voltage drop. CONSTITUTION: The output voltage V of a battery 12 is detected by an output voltage detection means 14, and is integrated on a time T by a voltage drop integration means 16. An integration value ΔVint and the remaining capacity Wb of the battery 12 are in a relation corresponding to each other, and these relations are stored in an integration value-remaining capacity storing means 18. Accordingly, when the integration value ΔVint is obtained by the output voltage detection means 14, the remaining capacity Wb corresponding to the integration value ΔVint is computed by a remaining capacity computing means 20. The remaining capacity is corrected based on the open end voltage of the battery 12 output voltage so as to obtain the remaining capacity more accurately.

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 calculation device for informing a driver of the remaining capacity of a battery in an electric vehicle that drives a motor by the electric power of the battery to run.

[0002]

2. Description of the Related Art A conventional battery remaining capacity calculating device is a current detecting means for detecting an output current of a battery, an output current integrating means for integrating an output current detected by the current detecting means with time, and an output current of this output current. The remaining capacity calculation means for calculating the remaining capacity of the battery based on the integrated value obtained by the integration means.

In such a remaining capacity calculating device, a value [Ah] obtained by integrating the output current with time is subtracted from the remaining capacity when the battery is charged.

[0004]

However, the conventional battery remaining capacity calculating device has the following problems.

It has been necessary to provide a current detection sensor or the like as the current detection means.

Further, in order to store the remaining capacity of the battery even when the electric vehicle is at rest, it is necessary to provide a storage element and a power supply circuit for holding the storage. Then, it is necessary to continue supplying power to the storage element even when the electric vehicle is at rest.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a dedicated component
It is an object of the present invention to provide a battery remaining capacity calculation device that does not require a device or the like and can calculate the remaining capacity of a battery by using parts / devices or the like provided in an electric vehicle.

[0008]

FIG. 1 is a functional block diagram showing a basic configuration of a battery remaining capacity calculating device according to a first aspect of the present invention.

A battery remaining capacity calculation device 10 according to claim 1.
Is based on the output voltage detecting means 14 for detecting the output voltage V of the battery 12, the voltage drop integrating means 16 for integrating the voltage drop ΔV of the output voltage V detected by the output voltage detecting means 14 in the time T, and the time T. Integral value-remaining capacity storage means 18, which stores in advance the relationship between the integrated value ΔVint of the voltage drop ΔV and the remaining capacity Wb of the battery 12, and the relationship stored in the integrated value-remaining capacity storage means 18 and the voltage drop. A remaining capacity calculating means 20 for calculating the remaining capacity Wb of the battery 12 based on the integrated value ΔVint obtained by the integrating means 16 is provided.

FIG. 2 is a functional block diagram showing the basic configuration of the battery remaining capacity calculation device according to the second aspect.

In addition to the same components as the battery remaining capacity calculation device 10, the battery remaining capacity calculation device 30 includes a speed detection means 32 for detecting the speed Vel of the electric vehicle, and a constant stop of the electric vehicle by the speed detection means 32. The relationship between the open end voltage detection means 34 that sets the output voltage V detected by the output voltage detection means 14 when the time is detected as the open end voltage Vop, and the open end voltage Vop of the battery 12 and the remaining capacity Wb is stored in advance. Open circuit voltage-remaining capacity storage means 36,
The relationship stored in the open end voltage-remaining capacity storage means 36 and the open end voltage Vop obtained by the open end voltage detection means 34.
The correction value calculating means 38 for calculating the remaining capacity Wbc of the battery 12 based on the above, the remaining capacity Wbc obtained by the correction value calculating means 38, and the remaining capacity W obtained by the remaining capacity calculating means 20.
and a remaining capacity correcting means 40 that uses the remaining capacity Wbc obtained by the correction value calculating means 38 as the true remaining capacity Wb when the difference from b is more than a certain value.

[0012]

The operation of the battery remaining capacity calculating device according to claim 1 will be described with reference to FIG.

The output voltage V of the battery 12 is detected by the output voltage detection means 14 and the time T by the voltage drop integration means 16.
Is integrated by On the other hand, the integrated value ΔVint and the battery 12
Has a corresponding relationship with the remaining capacity Wb, and these relationships are stored in the integrated value-remaining capacity storage means 18 in advance. Therefore, the integrated value ΔVint is calculated by the voltage drop integrating means 16.
Is obtained, the remaining capacity W corresponding to the integrated value ΔVint
b is calculated by the remaining capacity calculating means 20.

Hereinafter, a more detailed description will be given with reference to FIGS. 3 to 5.

FIG. 3 is a graph showing an example of the output current I-output voltage V characteristic of the battery. The battery shown in FIGS. 3 to 6 has a large number of lead oxide batteries connected in series and is mounted in a small electric vehicle.

The type of dot represents the type of remaining capacity Wb. Remaining capacity Wb is 100% when the discharge rate of the battery is 0%, and remaining capacity Wb is 25% when the discharge rate of the battery is 75%. Here, under no load (I =
When the output voltage at 0 [A] is V ₀ [V] and the output voltage at a certain output current I is V [V], V ₀ -V is defined as a voltage drop ΔV.

FIG. 4 is a graph showing an example of the battery voltage drop ΔV-power consumption W characteristic.

The power consumption W is calculated from the relationship shown in FIG. As is clear from this drawing, the voltage drop ΔV
If the remaining capacity Wb is known, the power consumption W at that time can be obtained. On the other hand, the remaining capacity Wb ₀ of the battery immediately after charging
Is 100%. The power consumption W at the voltage drop ΔV at this time is clear from FIG. 4, and the value obtained by integrating the voltage drop ΔV at the time T (hereinafter referred to as “integral value ΔVint”) corresponds to the power consumption Wt. Therefore, the remaining capacity Wb after the lapse of time T is

Wb = Wb ₀ -Wt ...

Is sequentially obtained as

The integrated value ΔVint is obtained as follows.
For example, the output voltage V is sampled every 10 [ms], and the voltage drop ΔV is calculated for each output voltage V. Then, this voltage drop ΔV is integrated for 6000 times (1 minute).
The value divided by 6000 is taken as the integral value ΔVint [V-min].

FIG. 5 is a chart showing an example of the correspondence relationship between the integrated value ΔVint and the remaining capacity Wb.

In this example, the temperature tem is also added as a parameter in consideration of the influence of the battery temperature tem on the output voltage V. The integrated value ΔVint in the right column corresponds to the remaining capacity Wb in the left column each time the threshold value in the chart is exceeded.

The operation of the battery remaining capacity calculation device according to claim 2 will be described with reference to FIG.

In the open circuit voltage detecting means 34, when the speed detecting means 32 detects the stop of the electric vehicle for a predetermined time T ₁ ,
Battery 1 detected by the output voltage detection means 14 at that time
The output voltage V of 2 is the open end voltage Vop. On the other hand, the open circuit voltage Vop and the remaining capacity Wbc have a corresponding relationship, and these relationships are stored in advance in the open circuit voltage-remaining capacity storage means 36. Therefore, the open end voltage detection means 34
When the open end voltage Vop is obtained at, the correction value calculating means 38 calculates the remaining capacity Wbc corresponding to the open end voltage Vop. This remaining capacity Wbc is determined by the remaining capacity correcting means 40 to be the true remaining capacity Wb when the difference from the remaining capacity Wb obtained by the remaining capacity calculating means 20 is more than a certain value.

FIG. 6 is a graph showing an example of the relationship between the open circuit voltage Vop of the battery and the remaining capacity Wbc.

Since the remaining capacity Wb obtained by the remaining capacity calculating means 20 is given by the above equation, the error increases as the remaining capacity Wb ₀ of the battery immediately after charging increases. In such a case, the correction is made based on the relationship shown in FIG. In this example, the fixed time T ₁ is 5
[sec] is set.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 7 is a block diagram showing an embodiment of a battery remaining capacity calculating apparatus according to the present invention, and corresponds to FIG. Hereinafter, description will be given with reference to FIGS. 2 and 7. However, the same parts as those in FIG.

The voltage drop integrating means 16, the integrated value-remaining capacity storing means 18, the remaining capacity calculating means 20, the open end voltage detecting means 34, the open end voltage-remaining capacity storing means 36, the correction value calculating means 38, and Remaining capacity correction means 40
Are realized by the microcomputer 50 in this embodiment.

The output voltage detecting means 14 is the battery 1
The speed detecting means 32 is a rotation speed sensor 58 attached to the drive shaft 56 of the front wheel 54. A temperature sensor 60 for detecting the temperature tem of the battery 12 is attached to the battery 12. The load 62 is composed of a motor, a motor drive circuit, and the like.

The microcomputer 50 may be the one already used for another purpose in the electric vehicle with a new computer program added. The conductor 52 may be provided in the electric vehicle to display the output voltage V of the battery 12, and the rotation speed sensor 58 may be provided in the electric vehicle to display the speed Vel of the electric vehicle.

The output signals of the conducting wire 52, the rotation speed sensor 58 and the temperature sensor 60 are input to an A / D converter, a waveform shaping circuit, etc. built in the microcomputer 50. The remaining capacity Wb calculated by the microcomputer 50 is converted into the remaining travel distance Dr and output to the remaining travel distance display device 64 such as a light emitting diode or a liquid crystal display panel.

8 to 10 show a microcomputer 5
8 is a flowchart showing the operation of 0, FIG. 8 is a main routine, FIG. 9 is a subroutine for calculating the voltage drop ΔV,
FIG. 10 shows a subroutine for updating the remaining capacity Wb.
Hereinafter, description will be given with reference to FIGS.

The main routine will be described with reference to FIG. First, each part is initialized by an initialization routine (step 101). Then, the temperature tem of the battery 12 is input from the temperature sensor 60 (step 102).
Then, the output voltage V of the battery 12 is input from the lead wire 52 (step 103), the voltage drop ΔV is calculated (step 104), and the integrated value ΔVint of the voltage drop ΔV is calculated (step 105). Then, temperature tem, integral value ΔVint
The remaining capacity Wb corresponding to is calculated (step 10
6). This is based on, for example, the chart shown in FIG.
The column to which em belongs is determined, and the integrated value ΔVint in that column
The remaining capacity Wb corresponding to is determined. When the remaining capacity Wb is calculated, it is determined whether the value has changed from the value calculated last time (step 107). If it has changed, the remaining capacity Wb is updated (step 108),
If it has not changed, the remaining capacity Wb is not updated. Finally, the remaining travel distance Dr is calculated and updated (step 10
9) and returns to step 102 again. Remaining mileage Dr
Is the total travelable distance = (distance traveled / used capacity x total capacity)
Then, it is calculated by (total travelable distance-traveling distance). The travel distance is the speed Vel obtained by the rotation speed sensor 58.
Is obtained by integrating. In this embodiment, since the remaining capacity Wb is converted into the remaining travel distance Dr and displayed, the information required by the driver can be provided, which is very practical.

A subroutine for calculating the voltage drop ΔV will be described with reference to FIG. After step 103 in FIG. 8, the speed Vel is input from the rotation speed sensor 58 (step 201). Then, it is determined whether or not the speed Vel = 0 continues for 5 seconds (step 202). If it continues for 5 seconds, the output voltage V at that time can be regarded as the open end voltage Vop. Therefore, the open end voltage Vop is input and set as the output voltage V _{0 under} no load (step 203). The output voltage V ₀ is the remaining capacity W
Since it decreases as b decreases, it is always corrected to an accurate value in this way. If it does not continue for 5 seconds, the previous value is used as the output voltage V ₀ . Finally, the voltage drop ΔV is obtained by ΔV = V ₀ −V (step 204), and the process proceeds to step 105 in FIG.

A subroutine for updating the remaining capacity Wb will be described with reference to FIG. Step 107 of FIG.
In the case of “Y”, the speed sensor 58 detects the speed Vel.
Is input (step 301). And speed Vel = 0
Is continued for 5 seconds or not (step 302).
If it continues for 5 seconds, the output voltage V at that time can be regarded as the open end voltage Vop, so the open end voltage Vop is input (step 3).
03). Then, the remaining capacity W corresponding to the open end voltage Vop
bc is obtained from, for example, the graph of FIG. 6 (step 30
4). It is judged whether or not the difference between the remaining capacity Wbc and the remaining capacity Wb obtained in step 106 of FIG. 8 is a certain value or more (step 305).
Since the cumulative error of b cannot be ignored, the remaining capacity Wbc is set as the remaining capacity Wb (step 306). Since the accumulated error of the remaining capacity Wb can be ignored if the value is equal to or less than a certain value, this remaining capacity Wb is used as it is. Finally, step 1 of FIG.
Go to 08.

Needless to say, the present invention is not limited to the above embodiment. For example, when the accuracy is not required so much, the open end voltage detecting means 34, the open end voltage-remaining capacity storage means 36, the correction value calculating means 38, the remaining capacity correcting means 40, the temperature sensor 60 and the like are unnecessary.

[0038]

According to the battery remaining capacity calculation device of the first aspect, the remaining capacity is obtained based on the integrated value of the voltage drop of the battery, so that no dedicated parts and devices are required, and the electric vehicle The remaining capacity of the battery can be calculated using the parts / devices and the like provided in the.

According to the battery remaining capacity calculating device of the second aspect, in addition to the above effects, the remaining capacity is corrected based on the open circuit voltage of the output voltage of the battery. Therefore, the remaining capacity can be obtained more accurately. You can Also, since it is not necessary to store the remaining capacity when the electric vehicle is at rest,
It is possible to eliminate the need for a power supply circuit for storing data and to reduce power consumption.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a basic configuration of a battery remaining capacity calculation device according to claim 1.

FIG. 2 is a functional block diagram showing a basic configuration of a battery remaining capacity calculation device according to claim 2;

FIG. 3 is a graph showing an example of output current-output voltage characteristics of a battery.

FIG. 4 is a graph showing an example of a voltage drop-power consumption characteristic of a battery.

FIG. 5 is a chart showing an example of a correspondence relationship between an integrated value of a voltage drop of a battery and a remaining capacity.

FIG. 6 is a graph showing an example of the relationship between the open circuit voltage of the battery and the remaining capacity.

FIG. 7 is a configuration diagram showing an embodiment of a battery remaining capacity calculation device according to the present invention.

8 is a flowchart showing the operation of the microcomputer shown in FIG.

9 is a flowchart showing the operation of the microcomputer of FIG.

10 is a flowchart showing the operation of the microcomputer of FIG.

[Explanation of symbols]

 10, 30 Battery Remaining Capacity Calculator 12 Battery 14 Output Voltage Detecting Means 16 Voltage Drop Integrating Means 18 Integral Value-Remaining Capacity Storage Means 20 Remaining Capacity Calculating Means 32 Speed Detecting Means 34 Open End Voltage Detecting Means 36 Open End Voltage-Remaining Capacity Storage unit 38 Correction value calculation unit 40 Remaining capacity correction unit V Battery output voltage ΔV Output voltage voltage drop ΔVint Integrated value of voltage drop Wb, Wbc Battery remaining capacity Vel Electric vehicle speed Vop Battery open end voltage

Claims (2)

[Claims] 1. An output voltage detecting means for detecting an output voltage of a battery, a voltage drop integrating means for integrating a voltage drop of the output voltage detected by the output voltage detecting means with time, and an integration of the voltage drop with time. Integral value-remaining capacity storage means for storing in advance the relationship between the value and the remaining capacity of the battery, the relationship stored in this integral value-remaining capacity storage means and the integral obtained by the voltage drop integrating means. And a state-of-charge calculation means for calculating the state-of-charge of the battery on the basis of the value. 2. A speed detecting means for detecting the speed of the electric vehicle, and an output voltage detected by the output voltage detecting means when the speed detecting means detects the stop of the electric vehicle for a certain period of time as an open end voltage. The open end voltage detecting means, the open end voltage-remaining capacity storing means for storing the relationship between the open end voltage of the battery and the remaining capacity in advance, and the open end voltage-remaining capacity storing means for storing. A correction value calculation means for calculating the remaining capacity of the battery based on the relationship and the open end voltage obtained by the open end voltage detection means, and the remaining capacity obtained by the correction value calculation means and the remaining capacity calculation means. The battery for an electric vehicle according to claim 1, further comprising: a remaining capacity correcting means for setting the remaining capacity obtained by the correction value calculating means as a true remaining capacity when a difference from the obtained remaining capacity is more than a certain value. Remaining Capacity calculator.