JP3390559B2 - Battery display device for electric vehicles - 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 residual quantity display device for an electric vehicle.

[0002]

2. Description of the Related Art As a battery residual quantity display device for an electric vehicle of this type, for example, in Japanese Patent Application Laid-Open No. 1-193675, a table of the characteristics of the internal battery resistance and the battery discharge time is prepared in advance, and the table value is stored. It is used to calculate the remaining battery capacity. In addition, JP-A-6-54402
The publication has a memory that stores unique information and history information about the battery, and uses the correction information of the battery capacity by the memory to calculate the remaining battery capacity.

[0003]

However, the remaining amount display devices of the above publications have the following problems. That is,
The device disclosed in the former publication is not suitable for use in an electric vehicle in which the use environment changes significantly, and has a problem in that it cannot adapt to deterioration of the battery over time. Further, the device of the latter publication discloses a broad idea of correcting the battery capacity using the unique information and the history information about the battery, but does not disclose the technical content for practical use.

The present invention is to solve such a problem, and an object of the present invention is to have a novel configuration and to accurately display the remaining battery amount adapted to changes in the usage state and deterioration state of the battery. Another object of the present invention is to provide a battery residual quantity display device for an electric vehicle.

[0005]

In order to achieve the above object, the invention as set forth in claim 1 is, as shown in FIG. 8, an integration for detecting an integrated amount of power consumed from a fully charged state of a battery M1. A power amount detecting means M2, a discharge voltage detecting means M3 for detecting a battery discharge voltage at the time of discharging the specific power by using a battery required power satisfying a predetermined traveling condition of the electric vehicle as a specific power, and a charging state of a predetermined reference power amount. Based on the relationship between the battery discharge voltage and the integrated power amount during the specific power discharge corresponding to, the power amount correction data according to the battery discharge voltage and the integrated power amount during the specific power discharge in the battery usage state is stored in advance. Memory M4, the integrated power amount detected by the integrated power amount detection means M2, and the battery discharge voltage at the time of specific power discharge detected by the discharge voltage detection means M3 Accordingly, the reference power amount is corrected by the correction data calculation unit M5 that reads the power amount correction data from the memory M4, and the power amount correction data by the correction data calculation unit M5. Battery residual quantity calculating means M6 for calculating the battery residual quantity from the integrated electric energy detected by the integrated electric energy detecting means M2
And the display means M7 for displaying the battery remaining amount calculated by the battery remaining amount calculating means M6.

According to a second aspect of the present invention, in the first aspect of the present invention, the reference electric energy is set as an electric energy that can be taken out by discharging from a fully charged state at a battery rated capacity to an end voltage. To be done.

According to a third aspect of the present invention, in the first or second aspect of the invention, the specific electric power is set to a minimum electric power value required according to an acceleration request of the electric vehicle. In the invention according to claim 4 which cites the invention according to any one of claims 1 to 3, in the memory M4, the battery discharge at the time of specific power discharge is higher than the characteristic indicating the charge state of the reference power amount. Correction data for correcting the reference power amount in the decreasing direction is set in a low voltage region, and correction data for no correction is set in a high battery discharge voltage region.

According to the invention described in claim 5, claims 1 to 4 are provided.
In any one of the inventions described above, the battery M1 is composed of a lead storage battery, and the relationship between the battery discharge voltage and the integrated power amount at the time of specific power discharge in the reference power amount is 3
It is represented by an approximate straight line or an approximate curve of the book.

[0009]

According to the invention described in claim 1, the integrated power amount detecting means M2 detects the integrated power amount consumed from the fully charged state of the battery M1. The discharge voltage detecting means M3 is
The battery required electric power satisfying the predetermined traveling condition of the electric vehicle is set as the specific electric power, and the battery discharge voltage at the time of discharging the specific electric power is detected. In addition, the memory M4, based on the relationship between the battery discharge voltage at the time of specific power discharge corresponding to the state of charge of the reference power amount and the integrated power amount, the battery discharge voltage and integrated power at the time of specific power discharge in the battery operating state. Electric power amount correction data corresponding to the amount is stored in advance.

Then, the correction data calculating means M5 is responsive to the integrated power amount detected by the integrated power amount detecting means M2 and the battery discharge voltage at the time of discharging the specific power detected by the discharge voltage detecting means M3, and the memory M4. The electric energy correction data is read from. Further, the battery remaining amount calculation means M6
Corrects the reference power amount with the power amount correction data by the correction data calculation unit M5, and calculates the remaining battery amount from the corrected power amount and the integrated power amount detected by the integrated power amount detection unit M2. The display unit M7 displays the battery remaining amount calculated by the battery remaining amount calculating unit M6.

In short, the battery M composed of a lead storage battery or the like.
In No. 1, the battery voltage tends to decrease as the integrated power amount increases, and the relationship between the integrated power amount and the battery voltage changes as the battery usage state or battery deterioration state changes. Therefore, the change in the above relationship means that the battery use state or the battery deterioration state has changed, and the full charge electric energy of the battery M1 also changes. In this case, the reference power amount is corrected by the power amount correction data of the memory M4 that stores the relationship between the discharge voltage and the integrated power amount at the time of specific power discharge, so that the corrected reference power amount is the same as that of the battery M1 at that time. The amount of electric power corresponds to the amount of fully charged electric power. Then, the battery remaining amount is calculated by using the corrected power amount, so that the battery remaining amount according to the battery usage state or the battery deterioration state can be obtained.

According to the second aspect of the present invention, the amount of electric power that can be taken out by discharging from the fully charged state at the battery rated capacity to the end voltage is set as the reference amount of electric power, so that the remaining amount of the battery is discharged. It is displayed as the battery capacity capable of running before reaching the voltage. In this case, the driver can determine whether or not the electric vehicle can run by looking at the display result, and can avoid an accidental output reduction of the vehicle due to insufficient capacity. In other words, an electric vehicle cannot run normally until the battery capacity reaches "0", and the capacity =
A predetermined capacity before reaching 0 (capacity corresponding to the discharge end voltage) interferes with normal running. Therefore, in a general display device that displays the remaining capacity of the battery, it is difficult for the driver to determine whether or not the vehicle can travel based on the remaining capacity. On the other hand, in this configuration, the above problem is solved.

According to the third aspect of the present invention, the specific electric power is set to the minimum electric power value required according to the acceleration request of the electric vehicle. In this case, the remaining battery amount is displayed as the minimum remaining amount that the electric vehicle can accelerate without any trouble, and the driver can determine whether or not normal running including general acceleration is possible by looking at the display result and running.

According to the fourth aspect of the invention, based on the charge state of the reference power amount, the reference power amount is corrected in the decreasing direction in a region where the battery discharge voltage at the time of specific power discharge is lower than that. That is, when the battery use state or the deterioration state changes and the battery discharge voltage decreases, the full charge electric energy of the battery M1 changes in the decreasing direction. Therefore, the reduction correction of the reference power amount is performed according to the transition of the above state.

Further, the correction is not executed in the region where the battery discharge voltage is high. That is, for example, immediately after regenerative charging of the battery M1 or after rapid charging, the terminal voltage of the battery M1 is detected higher than usual due to the influence of the charge polarization, and if the detected amount of data is used to correct the power amount, the battery remaining amount May be displayed erroneously. However, according to this configuration, since the correction is limited in this area, the remaining battery level is always displayed accurately. Further, even if an error occurs in the display of the battery remaining amount, the battery remaining amount is displayed in a small amount, and it is possible to avoid an inadvertent decrease in the output of the vehicle and the suspension of traveling.

According to the fifth aspect of the invention, the correction data is calculated by the approximation line formed of a simple arithmetic expression, and the calculation process of the remaining battery amount is simplified. In this case, the memory M
The number of stored data of 4 is limited, and the reduction of the storage capacity and the calculation time are also realized.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a battery remaining amount display device for an electric vehicle according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the outline of a battery remaining amount display device in this embodiment. In FIG. 1, an AC motor 2 is connected to both polar terminals of a battery 1 via an inverter 3. The battery 1 is composed of, for example, 16 lead storage batteries. The ECU (electronic control unit) 4 includes a microcomputer 5 having a CPU 5a and a memory 5b, and a motor control circuit 6 for controlling the drive of the motor 2. In addition, the present device includes a voltage detector 7 for detecting a battery terminal voltage, a discharge current from the battery 1 to the motor 2, a regenerative charging current from the motor 2 to the battery 1, or a charger (not shown) to the battery 1. A current detector 8 for detecting a charging current is provided, and the detection result of each detector is input to the microcomputer 5.

The CPU 5a of the microcomputer 5 is
The power consumption of the battery 1 (= battery terminal voltage × discharge current) is calculated based on the detection results from the detectors 7 and 8, and the integrated amount of power (hereinafter,
The integrated electric energy x) is calculated. Also, the CPU 5a
Is based on information such as the fully charged power amount Wh0 as the “reference power amount” of the battery 1 and the integrated power amount x
CW is calculated, and the calculated battery residual amount SOCW is displayed on the battery residual amount meter 9. The integrated electric energy x corresponds to the electric energy consumed from the fully charged state of the battery 1,
In the fully charged state, the integrated power amount x = 0. The full charge electric energy Wh0 is the battery rated capacity (15 in this embodiment).
0 Ah) is the amount of electric power that can be extracted by discharging from the fully charged state to the final voltage at 0 Ah), that is, the amount of electric power that the electric vehicle can normally drive without a problem after full charging.

The full charge electric energy Wh0 is stored in the memory 5b.
Amount correction data (hereinafter referred to as a correction amount γ) for correcting the above according to the battery usage state or the deterioration state is stored in advance. A storage table of the correction amount γ is shown in FIG. “Correction amount γ = 0” is given to the four data enclosed in the frame in FIG. 2 as reference data for power amount correction. That is, the correction amount γ corresponds to the correction data of the discharge voltage y and the integrated power amount x during the specific power discharge corresponding to the state of charge of the fully charged power amount Wh0. The specific electric power corresponds to the minimum electric power required to obtain acceleration during general driving of the electric vehicle, which is set according to the vehicle specifications. In this embodiment, specific power = 3k per lead-acid battery
It is set to W (hereinafter, "when specific power is discharged" is set to "3k
At the time of W discharge ”).

The data in the frame (γ = 0) in FIG. 2 is experimentally obtained as shown by the mark ◯ in FIG. 3, and the data in the mark ◯ is divided into three straight lines (hereinafter referred to as a reference straight line). Can be linearly approximated. The experimental data indicated by the circles are obtained in a road running test of an electric vehicle using a new battery (unused battery), and are plots of the discharge voltage y and the integrated electric energy x when discharging 3 kW. . In addition, when the discharge end voltage is 9 (V / piece) in FIG. 3, the full charge electric energy Wh
0 is the point shown in the figure (Wh0 = 1.17 kWh / unit).

Further, when the use state or the deterioration state of the battery 1 changes, the relation between the discharge voltage y and the integrated electric energy x at the time of discharging 3 kW changes as shown by, for example, a mark in FIG. In other words, when the use environment becomes severe due to a decrease in battery temperature, repeated rapid acceleration of the vehicle, or deterioration over time progresses, the above relationship shifts in the direction of → in the figure. In this case, the negative correction amount γ is set in the region where the discharge voltage y is lower than the in-frame data of FIG. 2 (the region below the reference straight line of FIG. 3) based on the experimental value. There is. The experimental data indicated by the squares are obtained in a road running test of an electric vehicle using a deteriorated battery (battery in use). Further, γ = “0” is set in a region where the discharge voltage y is higher than the in-frame data of FIG. 2 (region above the reference straight line of FIG. 3).

In FIG. 1, a battery fuel gauge 9 is provided on, for example, an instrument panel of an electric vehicle, and the battery remaining amount SOCW is changed from the fully charged state (F).
Display 10 categories up to = 0% (E). In the present embodiment, the CPU 5a of the microcomputer 5 constitutes the integrated electric energy detecting means, the discharge voltage detecting means, the correction data calculating means and the battery residual quantity calculating means, and the battery residual quantity meter 9 constitutes the displaying means. .

Next, the battery remaining amount S by the CPU 5a
The calculation process of OCW will be described with reference to the flowchart shown in FIG. Now, when the microcomputer 5 is powered on, the routine of FIG. 4 is started. Here, if the battery is fully charged at the start of the routine (immediately after normal charging), the integrated power amount x, the remaining battery amount SO
Initial values are given to various data such as CW. And C
The PU 5a first inputs the detection results of the voltage detector 7 and the current detector 8 in step 101, takes in the detection data of the battery terminal voltage and the discharge current every 0.1 seconds, and calculates the average value for each 1 second. .

In step 102, the CPU 5a calculates the internal resistance value of the battery based on the detection result (terminal voltage, discharge current) of step 101. FIG. 5 shows the relationship between the battery terminal voltage, the discharge current and the battery internal resistance value. In FIG. 5, the slopes of L1 to L4 (two-dot chain line) indicate the battery internal resistance, and the battery internal resistance value shifts from L1 to L4 as the depth of discharge increases. Also,
In the subsequent step 103, the CPU 5a calculates the integrated power amount x by time integration of power consumption.

After that, the CPU 5a calculates the discharge voltage y at the time of electric power discharge of 3 kW by comparing with the internal resistance value of the battery previously obtained in step 104. That is, the electric characteristics of the 3 kW discharge are represented by the solid line in FIG. 5, and the discharge voltage y at the time of the 3 kW discharge is obtained by the voltage at the intersection of the internal resistance value at that time and the solid line in the figure (for example, L2 Discharge voltage y2) with respect to internal resistance.

Further, in step 105, the CPU 5a uses the table of the memory 5b (FIG. 2) described above to obtain the correction amount γ corresponding to the integrated power amount x at that time and the discharge voltage y at the time of discharging 3 kW. In addition, between each table data,
For example, the correction amount γ is calculated by the interpolation based on the reference straight lines shown in FIG. 6 (the reference straight lines shown in FIG. 6 are the same as those in FIG. 3).

Then, the CPU 5a calculates the remaining battery charge SOCW by the following formula 1 in step 106, and displays the calculated value on the remaining battery charge meter 9.

[0029]

## EQU1 ## SOCW = (Wh0 + .gamma.-x) / (Wh0 +
γ) × 100 (%) After that, in step 107, the CPU 5a determines whether or not the traveling has ended, depending on the ON / OFF state of the ignition key.
When the traveling continues (for example, when the ignition key = ON), the CPU 5a returns to step 101, and when the traveling ends (when the ignition key = OFF), this routine ends.

FIG. 7 is a diagram showing the display results of the battery remaining amount SOCW when the electric vehicle is running on the road for a new battery and a deteriorated battery (however, the remaining amount is displayed in percentage here). The same traveling environment and constant speed traveling (for example, 60 km / h) are set as the traveling conditions on the road. In FIG. 7, the solid line shows the ideal value of the battery remaining amount change when using a new battery, and the broken line shows the ideal value of the battery remaining amount change when using a deteriorated battery. That is, in the ideal state, the remaining battery charge S
OCW decreases linearly. Also, in the figure, the X mark shows the test result of the remaining amount display when using a new battery, and the Δ mark shows the test result of the remaining amount display when using a deteriorated battery. According to this FIG. 7, the battery remaining amount SOC obtained in the present embodiment
It can be seen that W decreases when it matches the ideal value.

In addition to this, even when quick charging was performed during traveling, good results were obtained in which the battery remaining amount display according to the present embodiment matched the ideal value. That is, during the rapid charge, the state of charge of the battery 1 does not reach full charge, and during charging, the integrated power amount x is updated to a predetermined value of "x>0" by a process not shown. Then, the battery remaining amount SOCW starts to decrease from 80%, for example, with the integrated electric energy x updated at the time of rapid charging as an initial value. At this time, the apparent battery voltage becomes higher than the actual battery voltage due to the influence of the charge polarization during the rapid charge, and the calculated value of the discharge voltage y at the time of 3 kW discharge (step 104 in FIG. 4) is the reference of FIG. The value exceeds the straight line. Therefore, there is a possibility that the integrated electric energy x is treated less and the remaining battery charge SOCW is displayed more than the original normal value. But,
In the present embodiment, since the correction limited area (γ = 0) is provided as shown in the table of FIG. 2, the above erroneous display is prevented.

According to the battery remaining amount display device for an electric vehicle described in detail above, the following effects can be obtained. That is, in the battery 1 made of a lead storage battery, the battery voltage tends to decrease as the integrated power amount increases, and such a relationship between the integrated power amount and the battery terminal voltage changes with the transition of the battery usage state or the battery deterioration state. Change. On the other hand, the fully charged power amount W of the battery 1 as the reference power amount is calculated by using the correction amount γ (power amount correction data) that reflects the transition of the battery usage state or the battery deterioration state.
By correcting h0 and calculating the battery remaining amount SOCW using the corrected electric energy data (Wh0 + γ), it is possible to obtain an accurate battery remaining amount according to the battery usage state or the battery deterioration state.

Further, according to the present embodiment, the battery remaining amount SO is based on the amount of electric power (full charged electric power amount Wh0) that can be taken out by discharging from the fully charged state to the final voltage.
By displaying CW, it is possible to easily determine whether or not the electric vehicle can be run from the display result, and avoid an inadvertent output reduction of the vehicle due to insufficient capacity.

Further, according to this embodiment, the battery remaining amount S
OCW is displayed as the minimum remaining amount that the electric vehicle can accelerate without any trouble, and the driver can judge whether or not normal driving including general acceleration is possible by looking at the display result and driving.

Furthermore, according to the present embodiment, it is possible to prevent the erroneous display of the remaining battery charge SOCW even when the apparent battery voltage rises immediately after regenerative charging of the battery 1 or after rapid charging. Further, even if an error occurs in the display of the remaining battery charge SOCW, the remaining battery charge SOCW is displayed in a small amount, and it is possible to avoid an inadvertent decrease in the output of the vehicle or a stoppage of running.

Further, according to the present embodiment, the correction data can be calculated by the approximate straight line consisting of a simple arithmetic expression, and the calculation process of the battery remaining amount SOCW can be simplified. In this case, the number of data stored in the memory 5b is limited, and the storage capacity is reduced and the calculation time is shortened.

The present invention can be embodied with the following modifications other than the above embodiment. (1) In the above embodiment, the three reference straight lines 1 to 3 are set in the relationship shown in FIG. 3, but they may be approximated curves. In addition, it is possible to improve the accuracy by increasing the number of approximate lines.

(2) In the above-mentioned embodiment, the battery 1 made of a lead storage battery was used for the embodiment, and the battery characteristics were approximated by three reference straight lines ~ as shown in FIG. 6, but this is used as a nickel-cadmium storage battery or the like. It may be embodied in a battery using another secondary battery of. In this case, the relationship between the integrated electric energy and the battery voltage differs from that shown in FIG. 3 depending on the type of battery, and a new correction amount table is set.

(3) In the above embodiment, the reference power amount is the fully charged power amount at the battery rated capacity, and the specific power is the minimum power value according to the acceleration request of the electric vehicle (in the above embodiment,
3 kW), but this can be changed. For example, when the specific electric power is set to the electric power that can be driven by the electric vehicle lower than 3 kW, the battery remaining amount SOCW = 0% corresponds to the battery remaining amount that allows the vehicle to run by itself, although acceleration is not normally obtained.

(4) In the above embodiment, the display means 1
Although the 0-stage display battery fuel gauge 9 is embodied, it can be changed to a percentage display digital fuel gauge.
Alternatively, the pointer can be changed to an analog fuel gauge that displays the SOC W of the battery.

[0041]

According to the first aspect of the present invention, it has an excellent effect that it has a novel structure and can accurately display the remaining battery level adapted to the change in the usage state or deterioration state of the battery. Exert.

According to the second aspect of the present invention, the remaining battery level is displayed as the battery capacity capable of running until the discharge end voltage is reached, and the capacity is insufficient by judging whether or not the electric vehicle can run based on the display result. It is possible to avoid an inadvertent decrease in the output of the vehicle due to.

According to the third aspect of the present invention, the remaining battery level is displayed as the minimum remaining level at which the electric vehicle can accelerate without hindrance, and the result of this display determines whether or not normal running including general acceleration is possible. it can.

According to the fourth aspect of the present invention, it is possible to prevent erroneous detection of the remaining battery level even when the voltage temporarily rises during rapid charging of the battery. According to the invention described in claim 5, it is possible to realize simplification of the calculation process of the battery remaining amount, reduction of the memory storage capacity, and reduction of the calculation time.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a battery residual quantity display device for an electric vehicle according to an embodiment.

FIG. 2 is a table for calculating a correction amount γ.

FIG. 3 is a diagram showing a relationship between a discharge voltage and an integrated electric energy when discharging 3 kW by a road running test.

FIG. 4 is a flowchart showing a main routine executed by a CPU.

FIG. 5 is a diagram showing the relationship between battery terminal voltage, discharge current, and battery internal resistance.

FIG. 6 is a diagram showing the relationship between the discharge voltage and the integrated electric energy when discharging 3 kW.

FIG. 7 is a diagram showing a display result of a battery remaining amount when traveling on a road.

FIG. 8 is a block diagram corresponding to a claim.

[Explanation of symbols]

1 ... Battery, 5a ... Integrated power amount detecting means, discharge voltage detecting means, correction data calculating means, CPU as battery remaining amount calculating means, 5b ... Memory, 9 ... Battery remaining amount meter as displaying means.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirochi Asa 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc. (56) Reference JP-A-6-68912 (JP, A) JP-A 6-59003 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01R 31/36 H01M 10/42-10/48 H02J ⁷ /00-7/12

Claims (5)

(57) [Claims] 1. An integrated power amount detecting means for detecting an integrated power amount consumed from a fully charged state of a battery, and a battery required power satisfying a predetermined traveling condition of an electric vehicle as a specific power, and a battery at the time of discharging the specific power. Discharge voltage detection means for detecting a discharge voltage, and a specific power discharge in a battery operating state based on the relationship between the battery discharge voltage and the integrated power amount during the specific power discharge corresponding to the charge state of a predetermined reference power amount Memory for pre-storing power amount correction data according to the battery discharge voltage and the integrated power amount at the time, the integrated power amount detected by the integrated power amount detection means, and the specific power discharge detected by the discharge voltage detection means Correction data calculation means for reading the power amount correction data from the memory according to the battery discharge voltage of Battery remaining amount calculating means for correcting the reference power amount with amount correction data, and calculating a battery remaining amount from the corrected power amount and the integrated power amount detected by the integrated power amount detecting means; A battery remaining amount display device for an electric vehicle, comprising: a display unit that displays the remaining battery amount calculated by the remaining amount calculating unit. 2. The remaining amount display of the battery for an electric vehicle according to claim 1, wherein the reference amount of electric power is set as an amount of electric power that can be taken out by discharging from a fully charged state at a battery rated capacity to a cutoff voltage. apparatus. 3. The battery level indicator for an electric vehicle according to claim 1, wherein the specific electric power is set at a minimum electric power value required in response to an acceleration request of the electric vehicle. 4. In the memory, correction data for correcting the reference power amount in a decreasing direction is set in a region where a battery discharge voltage at a specific power discharging time is lower than a characteristic representing a charge state of the reference power amount, The battery residual quantity display device according to claim 1, wherein correction data indicating no correction is set in a region where the battery discharge voltage is high. 5. The battery is constituted by a lead storage battery, and the relationship between the battery discharge voltage and the integrated power amount at the time of specific power discharge in the reference power amount is represented by three approximate straight lines or approximate curves. 5. A battery remaining amount display device for an electric vehicle according to any one of 1.