Battery residual quantity display system

Abstract

To correct and display a current battery residual quantity in consideration of a current actual travelable distance in an electric vehicle including a rechargeable battery.SOLUTION: A battery residual quantity display system of an electric vehicle including a rechargeable battery, includes: an estimation unit that estimates a current battery residual quantity of the rechargeable battery on the basis of a power quantity output from the rechargeable battery; a corrected battery residual quantity calculation unit that corrects the current battery residual quantity in consideration of a current actual travelable distance on the basis of a battery residual quantity at the time of previous charging, the current battery residual quantity, and output efficiency for each magnitude of the power residual quantity, to calculate a corrected battery residual quantity; and a display control part that causes a display part to display the corrected power residual quantity.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a battery remaining amount display system.

Background Art

[0002] In recent years, in electric vehicles equipped with rechargeable batteries (including plug-in hybrid vehicles, etc.), management of the remaining amount of the rechargeable battery is very important. This is because there are limitations such as the number of charging facilities, charging time, and charging amount, and just because the remaining amount of the battery has decreased, it is not always possible to freely charge immediately.

[0003] Generally, in an electric vehicle, there is no battery remaining amount sensor, and the current remaining amount of the battery is estimated from the amount of power used. In that case, by taking into account the environmental temperature of the rechargeable battery, etc., the current remaining amount of the battery can be estimated with high accuracy.

[0004] Then, the driver looks at the display of the current remaining amount of the battery and estimates the current available driving distance. For example, if the rechargeable battery was fully charged at the previous charge, the driving distance from the previous charge to the present is 200 km, and the current remaining amount of the battery (SOC (State of Charge)) is 50%, the driver will estimate that the current available driving distance is about 200 km by proportional calculation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, generally, the smaller the SOC, the shorter the driving range per unit SOC. One of the reasons is as follows. First, the smaller the SOC, the lower the output voltage from the rechargeable battery, so the current amount needs to be increased to ensure a certain amount of power. As a result, the heat generation amount increases, the heat loss becomes larger, and the output efficiency of the rechargeable battery decreases.

[0007] Therefore, for example, even if the driving range when the SOC changes from 100% to 50% is 200 km, the driving range when the SOC changes from 50% to 0% will be shorter than that. Even in that case, the driver assumes that the current driving range is about 200 km. However, for example, if the actual driving range is 160 km, when driving aiming for a charging facility 180 km ahead, the SOC will become 0 (power outage state) during driving. Therefore, improvement is needed.

[0008] Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a remaining battery amount display system that can correct and display the current remaining battery amount based on the current actual driving range in an electric vehicle equipped with a rechargeable battery.

Means for Solving the Problem

[0009] In order to solve the above problems, the remaining battery amount display system of the present invention is a remaining battery amount display system for an electric vehicle equipped with a rechargeable battery, and based on the amount of power output from the rechargeable battery, an estimation unit that estimates the current remaining battery amount of the rechargeable battery, the remaining battery amount at the time of the previous charge, the current remaining battery amount, and the output efficiency for each size of the remaining battery amount, based on these, a corrected remaining battery amount calculation unit that corrects the current remaining battery amount based on the current actual driving range and calculates a corrected remaining battery amount, and a display control unit that causes the display unit to display the corrected remaining battery amount.

[0010] According to this configuration, for example, by correcting the current remaining battery amount based on the output efficiency for each size of the remaining battery amount, it is possible to display the corrected remaining battery amount based on the current actual driving range.

[0011] Further, in the battery remaining amount display system, the corrected battery remaining amount calculation unit may correct the current battery remaining amount based on the output efficiency for each region obtained by dividing the magnitude of the battery remaining amount into a plurality of regions, taking into account the current actual travelable distance, and calculate the corrected battery remaining amount.

[0012] According to this configuration, for example, specifically, the current battery remaining amount can be corrected based on the output efficiency for each region obtained by dividing the magnitude of the battery remaining amount into a plurality of regions.

[0013] Further, the battery remaining amount display system may further include a travelable distance calculation unit that calculates the current actual travelable distance based on the corrected battery remaining amount, and the display control unit may cause the display unit to display the current actual travelable distance.

[0014] According to this configuration, for example, based on the corrected battery remaining amount, the current actual travelable distance can be calculated and displayed.

Advantages of the Invention

[0015] According to the present invention, in an electric vehicle equipped with a rechargeable battery, the current battery remaining amount can be corrected and displayed taking into account the current actual travelable distance.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0017] Hereinafter, embodiments of the battery remaining amount display system of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram showing an electric vehicle 12 equipped with the battery remaining amount display system (ECU (Electronic Control Unit) 20, display unit 24) of the embodiment. FIG. 2 is a block diagram showing the functional configuration of the ECU 20 of the embodiment.

[0018] As shown in FIG. 1, the electric vehicle 12 includes a motor unit 16 connected to drive wheels 14D, a battery pack 18, and an ECU 20 that controls the entire electric vehicle 12. Further, a DC / DC converter 22 and a display unit 24 are connected to the ECU 20. A auxiliary battery 26 is connected to the DC / DC converter 22. In the present embodiment, for the sake of simplicity of explanation, the ECU is represented as a single ECU 20, but it is not limited thereto, and a plurality of ECUs may be provided.

[0019] The electric vehicle 12 charges the battery pack 18 with the power supplied by an external charger BS, and drives the motor generator 16a included in the motor unit 16 as a motor with the power charged in the battery pack 18 to control the rotation of the drive wheels 14D and run. In FIG. 1, a front-wheel drive vehicle in which the motor unit 16 is connected to the front wheels 14F and the front wheels 14F are used as the drive wheels 14D is shown, but the motor unit 16 may be connected to the rear wheels 14R and the rear wheels 14R may be used as the drive wheels 14D. Further, the motor unit 16 may be connected to each of the front wheels 14F and the rear wheels 14R to form a four-wheel drive vehicle.

[0020] The motor unit 16 is a power device called a so-called "e-axle" that integrates devices such as a motor generator 16a (MG), an inverter 16b, and a transaxle 16c (power transmission mechanism). The motor generator 16a can function as a motor and can be a drive source for the electric vehicle 12. For the motor generator 16a, for example, a type using permanent magnets can be used.

[0021] The inverter 16b converts the direct current supplied from the battery pack 18 into an alternating current (three-phase alternating current) and drives the motor generator 16a. Also, the inverter 16b controls the motor output according to the accelerator operation of the electric vehicle 12. When the motor generator 16a functions as a generator, the inverter 16b converts the regenerated alternating current into a direct current and charges the battery pack 18 via the ECU 20.

[0022] The transaxle 16c includes a transmission that appropriately shifts the rotation of the motor generator 16a, a differential gear that distributes the driving force to the drive shafts connected to the left and right drive wheels 14D, and the like.

[0023] The battery pack 18 is, for example, a battery pack that combines a plurality of secondary batteries (rechargeable batteries) and can be charged and discharged. The secondary battery is, for example, a lithium-ion battery.

[0024] The ECU 20 controls the entire electric vehicle 12. Also, for example, when a charging plug 12A provided on a part of the body of the electric vehicle 12 and a charging plug BSA of an external charger BS are connected by a dedicated charging cable (not shown), the ECU 20 performs a charging process for the battery pack 18. Also, when the motor generator 16a functions as a generator and performs a regeneration operation (regenerative braking) during coasting (when the accelerator is off) or downhill driving of the electric vehicle 12, the ECU 20 performs a charging process of charging the battery pack 18 with the regenerated electric power.

[0025] The external charger BS is provided at the charging station. The external charger BS can be installed, for example, at a place where the electric vehicle 12 can park, such as a parking lot or a gas station, and can appropriately charge the electric vehicle 12.

[0026] Also, the ECU 20 causes the DC / DC converter 22 to convert the power supplied from the external charger BS, the power regenerated by the motor generator 16a, and the power supplied from the battery pack 18 to a predetermined voltage, and performs charging control so that the charge amount of the auxiliary battery 26 becomes the set charge amount. Note that the auxiliary battery 26 is used to supply power to various in-vehicle electronic devices (for example, an audio system, a navigation system, various lamps, etc.).

[0027] The ECU 20 has, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an SSD (Solid State Drive, flash memory), etc. The CPU reads out a program installed and stored in a non-volatile storage unit such as the ROM or the SSD, and realizes various modules according to the program. As shown in FIG. 2, the ECU 20 includes, as various modules, an acquisition unit 201, an estimation unit 202, a calculation unit 203, and a control unit 204. Note that some or all of the various modules may be realized by hardware.

[0028] The acquisition unit 201 acquires information from each component.

[0029] The estimation unit 202 estimates various information. For example, the estimation unit 202 estimates the current battery remaining amount (SOC) of the battery pack 18 based on the amount of power output from the battery pack 18. In that case, by taking into account the environmental temperature of the battery pack 18 and the like, the current battery remaining amount can be estimated with high accuracy.

[0030] The calculation unit 203 calculates various types of information. For example, the calculation unit 203 (corrected battery remaining amount calculation unit) corrects the current battery remaining amount based on the battery remaining amount at the previous charge, the current battery remaining amount, and the output efficiency for each size of the battery remaining amount, taking into account the current actual travelable distance, and calculates the corrected battery remaining amount.

[0031] In that case, the calculation unit 203 (corrected battery remaining amount calculation unit) calculates the corrected battery remaining amount by correcting the current battery remaining amount based on the output efficiency for each region obtained by dividing the size of the battery remaining amount into a plurality of regions, taking into account the current actual travelable distance. This will be described in detail below.

[0032] For example, assume the following representative battery efficiencies (output efficiencies) ηx when the size of the state of charge (SOC) is divided into 10 parts. SOC (0 - 10): η1 SOC (10 - 20): η2 SOC (20 - 30): η3 SOC (30 - 40): η4 SOC (40 - 50): η5 SOC (50 - 60): η6 SOC (60 - 70): η7 SOC (70 - 80): η8 SOC (80 - 90): η9 SOC (90 - 100): η10 Note that η1 < η2 < η3 < η4 < η5 < η6 < η7 < η8 < η9 < η10.

[0033] The respective capacity ratios in that case are as follows. Note that η = η1 + η2 + η3 + η4 + η5 + η6 + η7 + η8 + η9 + η10. <Capacity ratio> SOC (0 - 10) = 100×(η1 / η) SOC (10 - 20) = 100×(η2 / η) SOC (20 - 30) = 100×(η3 / η) SOC (30 - 40) = 100×(η4 / η) SOC (40 - 50) = 100×(η5 / η) SOC(50 - 60) = 100×(η6 / η) SOC(60 - 70) = 100×(η7 / η) SOC(70 - 80) = 100×(η8 / η) SOC(80 - 90) = 100×(η9 / η) SOC(90 - 100) = 100×(η10 / η)

[0034] And the corrected remaining battery capacity is as follows. <Corrected remaining battery capacity> SOC_100% = 100% SOC_90% = SOC_100% - SOC(90 - 100) SOC_80% = SOC_90% - SOC(80 - 90) SOC_70% = SOC_80% - SOC(70 - 80) SOC_60% = SOC_70% - SOC(60 - 70) SOC_50% = SOC_60% - SOC(50 - 60) SOC_40% = SOC_50% - SOC(40 - 50) SOC_30% = SOC_40% - SOC(30 - 40) SOC_20% = SOC_30% - SOC(20 - 30) SOC_10% = SOC_20% - SOC(10 - 20) SOC_0% = SOC_10% - SOC(0 - 10) = 0%

[0035] Alternatively, instead of dividing the battery remaining capacity (SOC) into 10 parts, for example, it may be divided into 2 parts to calculate the corrected battery remaining capacity. In that case, for example, the output efficiency at full charge and near battery depletion is taken into account, and weighting is performed to calculate the corrected battery remaining capacity. Specifically, for example, assume that the output efficiency from full charge (SOC 100%) to SOC 50% is 80%, and the output efficiency from SOC 50% to near battery depletion (SOC 0%) is 60%. Then, at full charge, the amount obtained by dividing 1 by 0.8 (1.25), and near battery depletion, the amount obtained by dividing 1 by 0.6 (about 1.67) are regarded as SOC 50%, and the ratio of the battery remaining capacity is set. Or, it may be calculated as a continuous function characteristic instead of by division.

[0036] <From full charge (SOC 100%) to SOC 50%> 1.25 / (1.25 + about 1.67) = SOC about 43% consumption (that is, SOC about 57%), and set the corrected battery remaining capacity to 50%.

[0037] <From SOC 50% to near battery depletion (SOC 0%)> 1.67 / (1.25 + about 1.67) = SOC about 57% consumption, and proportionally reduce the corrected battery remaining capacity from 50% (actual SOC about 57%).

[0038] In this way, by dividing the battery remaining capacity into 10 parts or 2 parts, the corrected battery remaining capacity can be calculated. Note that instead of dividing the battery remaining capacity into multiple regions, an approximate curve (function F(x)) of the output efficiency for each battery remaining capacity may be used to calculate the corrected battery remaining capacity.

[0039] Here, FIG. 3 is a graph showing the relationship between the actual SOC (horizontal axis) and the displayed SOC (corrected battery remaining capacity) (vertical axis) in the embodiment. The line L1 in FIG. 3 is a graph showing the relationship between the actual SOC and the displayed SOC of the prior art. In this case, the actual SOC and the displayed SOC are equal. For example, at point P1, both the actual SOC and the displayed SOC are 50%. The same applies to points P3 and P5.

[0040] However, as described above, when the driver estimates the current available driving distance based on this displayed SOC and the driving distance from a full charge, the actual available driving distance is shorter, so there is a possibility of running out of power due to this estimation.

[0041] On the other hand, line L2 is a graph showing the relationship between the actual SOC and the displayed SOC of the present embodiment. In this case, except when the SOC is 100% and 0%, the displayed SOC is smaller than the actual SOC. For example, at point P2, the actual SOC is about 60% and the displayed SOC is 50%. The same applies to point P4 and point P6.

[0042] In this way, the current actual SOC is corrected based on the current actual available driving distance to obtain the corrected remaining battery level, and the corrected remaining battery level (displayed SOC) is displayed. As a result, when the driver estimates the current available driving distance based on this displayed SOC and the driving distance from a full charge, it becomes equivalent to the actual available driving distance, so the possibility of running out of power due to this estimation can be eliminated.

[0043] Returning to FIGS. 1 and 2, the control unit 204 executes various controls. The control unit 204 (display control unit) causes, for example, the corrected remaining battery level to be displayed on the display unit 24.

[0044] Further, the calculation unit 203 (available driving distance calculation unit) may calculate the current actual available driving distance based on the corrected remaining battery level. In that case, the control unit 204 (display control unit) causes the current actual available driving distance to be displayed on the display unit 24.

[0045] Here, FIG. 4 is a diagram showing an example of a display screen of the prior art and the embodiment. Here, it is assumed that both the remaining battery level and the current available driving distance are displayed. In the prior art shown in FIG. 4(a), the displayed SOC (display M1) is equal to the actual SOC (line L1 in FIG. 3). Therefore, if the displayed SOC is 50% and, for example, the driving distance from a full charge is 180 km, the current available driving distance (display D1) is 180 km × (50% / 50%) = 180 km. However, the actual available driving distance is shorter.

[0046] On the other hand, in the present embodiment shown in FIG. 4(b), the display SOC (display M2) is smaller than the actual SOC (line L2 in FIG. 3). Therefore, for example, even if the actual SOC is 50%, the display SOC is 40%. Assuming that the driving distance from a full charge is 180 km, the current available driving distance (display D2) is 180 km × (40% / 60%) = 120 km. This is equivalent to the actual available driving distance. Here, the calculation method of the current available driving distance is simplified.

[0047] FIG. 5 is a flowchart showing the first process by the ECU 20 of the embodiment. Here, a case where the SOC is divided into 10 parts and the corrected remaining battery amount is calculated is taken as an example.

[0048] In step S1, the control unit 204 sets the SOC to 100% at full charge.

[0049] Next, in step S2, the control unit 204 resets the driving distance to 0 km.

[0050] Next, in step S3, the estimation unit 202 estimates the current SOC based on the amount of power output from the battery pack 18.

[0051] Next, in step S4, the control unit 204 determines whether the SOC has decreased by 10% or more. If Yes, it proceeds to step S5; if No, it proceeds to step S7.

[0052] In step S5, the calculation unit 203 corrects the current SOC based on the SOC at full charge (100%), the current SOC, and the output efficiency for each SOC level, and calculates the corrected SOC in consideration of the current actual available driving distance. Specifically, first, the corresponding subtraction amount (capacity ratio) is calculated using SOC({(x - 1)×10}-{x×10}) = 100×(ηx / η). Then, the corrected SOC is calculated using SOC_{(x - 1)×10}% = SOC_(x×10)% - SOC({(x - 1)×10}-{x×10}).

[0053] Next, in step S6, the control unit 204 displays the corrected SOC on the display unit 24 (display M2 in FIG. 4(b)).

[0054] Also, in step S7, the calculation unit 203 updates the current SOC based on the current SOC and the subtracted SOC amount.

[0055] Next, in step S8, the control unit 204 displays the current SOC on the display unit 24.

[0056] Next, FIG. 6 is a flowchart showing a second process by the ECU of the embodiment. This second process is a process for calculating and displaying the current actual travelable distance based on the corrected SOC.

[0057] In step S11, the acquisition unit 201 acquires information on the corrected SOC (XX (%)).

[0058] Next, in step S12, the acquisition unit 201 acquires information on the travel distance (YY (km)) from a full charge.

[0059] Next, in step S13, the calculation unit 203 calculates the current actual travelable distance based on the corrected SOC and the travel distance from a full charge. For example, first, the travel distance per 1% of SOC (ZZ) is calculated using ZZ = YY / (100 - XX). Next, the current actual travelable distance (A) is calculated using A = XX × ZZ.

[0060] Next, in step S14, the control unit 204 causes the current actual travelable distance (A) to be displayed on the display unit 24 (FIG. 4(b)).

[0061] Thus, according to the battery remaining amount display system of the present embodiment, by correcting the current battery remaining amount based on the output efficiency for each size of the battery remaining amount, it is possible to display the corrected battery remaining amount based on the current actual travelable distance.

[0062] Specifically, the current remaining battery level can be corrected based on the output efficiency for each of a plurality of regions obtained by dividing the magnitude of the remaining battery level into the plurality of regions.

[0063] Also, based on the corrected remaining battery level, the current actual available driving distance can be calculated and displayed (Fig. 4(b)).

[0064] In the prior art, when calculating and displaying the current available driving distance, for example, future power consumption by the air conditioner was also taken into account. Therefore, by turning the air conditioner on / off, the current available driving distance could rapidly increase or decrease, which could confuse the driver. According to this embodiment, since future power consumption by the air conditioner is not taken into account, turning the air conditioner on / off does not cause the current available driving distance to rapidly increase or decrease, and a situation where the driver is confused can be avoided. Specifically, in line L2 of Fig. 3, if the air conditioner is on, the moving speed in the left direction becomes faster, and if the air conditioner is off, the moving speed in the left direction becomes slower, but the shape of line L2 itself does not change. However, when power is generated by regenerative braking, the current available driving distance may increase.

[0065] The program executed by the ECU 20 of this embodiment can be recorded and provided on a recording medium readable by a computer device such as a CD (Compact Disc)-ROM (Read Only Memory), flexible disk (FD), CD-R (Recordable), DVD (Digital Versatile Disk), etc. in an installable format or an executable format file. Also, the program may be provided or distributed via a network such as the Internet.

[0066] Although embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

[0067] For example, the electric vehicle targeted by the present invention is not limited to an electric vehicle that runs only on electricity. Additionally, it may be an electric vehicle that runs on electricity and other fuels, such as a plug-in hybrid vehicle.

Explanation of Reference Numerals

[0068] 12... Electric vehicle, 18... Battery pack, 20... ECU, 24... Display unit, 201... Acquisition unit, 202... Estimation unit, 203... Calculation unit, 204... Control unit

Claims

1. A battery remaining amount display system for an electric vehicle equipped with a rechargeable battery, an estimation unit that estimates the current remaining battery amount of the rechargeable battery based on the amount of electric power output from the rechargeable battery; a corrected battery remaining amount calculation unit that corrects the current remaining battery amount based on the remaining battery amount at the previous charge, the current remaining battery amount, and the output efficiency for each size of the remaining battery amount, and calculates a corrected battery remaining amount in consideration of the current actual travelable distance; and a display control unit that causes the display unit to display the corrected battery remaining amount. A battery remaining amount display system comprising the same.

2. The corrected battery remaining amount calculation unit corrects the current remaining battery amount based on the output efficiency for each region obtained by dividing the size of the remaining battery amount into a plurality of regions, and calculates the corrected battery remaining amount in consideration of the current actual travelable distance. The battery remaining amount display system according to Claim 1.

3. further comprising a travelable distance calculation unit that calculates the current actual travelable distance based on the corrected battery remaining amount, and the display control unit causes the display unit to display the current actual travelable distance. The battery remaining amount display system according to Claim 1.

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