Display system

Abstract

The invention relates to a display system. The display system includes an instrument panel, a battery, a current sensor, and an ECU. The battery stores power for driving the vehicle. The current sensor detects a charge / discharge current of the battery. The ECU calculates the SOC of the battery in accordance with a detection value of the current sensor. The SOC includes a control SOC used for controlling charging and discharging of the battery, and a display SOC displayed on the dashboard and calculated in accordance with the control SOC. When an index value indicating the degree of reduction in the calculation accuracy of the control SOC exceeds a threshold value, the ECU starts calculation processing for calculating the display SOC to be lower than the control SOC.

Description

Technical Field

[0001] The present disclosure relates to a display system. Background Art

[0002] International Publication No. 2014 / 046232 discloses a charging state calculation device. The device includes a charging state calculation unit, a full charge detection unit, and a correction value calculation unit. The charging state calculation unit calculates the charging state of the battery. The full charge detection unit detects the full charge of the battery. When the correction value calculation unit detects that the battery is fully charged, it calculates a correction value for correcting the calculation result of the charging state. The correction value calculation unit updates the correction value only when the battery is fully charged, and keeps the updated correction value until the next full charge. Summary of the invention

[0003] The charge state of a power storage device such as a battery is generally expressed by the state of charge (SOC). The SOC of a power storage device mounted on an electric vehicle is basically calculated based on the detection value of a current sensor that detects the charge and discharge current of the power storage device. The SOC calculated in this way can be displayed on the display device of the vehicle.

[0004] Due to the accumulation of detection errors (such as offset errors) of the current sensor, the calculation accuracy of the SOC may decrease over time. As a result, the displayed SOC no longer correctly reflects the actual charging state of the power storage device. In this way, even if the storage capacity of the power storage device decreases, the user cannot correctly understand its meaning. Therefore, although the user realizes that the storage capacity of the power storage device has not decreased, the storage capacity decreases to zero faster than expected, and there is a possibility of accidentally causing a malfunction of the electric vehicle (such as a lack of power). According to the technology of International Publication No. 2014 / 046232, the SOC can be corrected only when the power storage device is fully charged. However, if the period during which the power storage device is not fully charged is prolonged, the SOC cannot be properly corrected, and the calculation accuracy of the SOC may decrease. As a result, there is a possibility that the above-mentioned malfunction cannot be prevented.

[0005] The present disclosure provides a display system capable of preventing a situation in which a malfunction of an electric vehicle unexpectedly occurs due to a decrease in the calculation accuracy of an SOC.

[0006] The display system disclosed in the present invention comprises:

[0007] Display device;

[0008] A power storage device that stores electricity for driving the electric vehicle;

[0009] a current sensor for detecting a charge and discharge current of the power storage device; and

[0010] The processing device calculates the SOC of the power storage device according to the detection value of the current sensor.

[0011] The SOC includes a control SOC used for charge and discharge control of the power storage device and a display SOC displayed on the display device and calculated based on the control SOC.

[0012] When the index value indicating the degree of reduction in calculation accuracy of the control SOC exceeds a threshold value, the processing device starts calculation processing for calculating the display SOC to be lower than the control SOC.

[0013] By setting the above structure, when the calculation accuracy of the control SOC decreases, the display SOC is calculated as a value lower than the control SOC and displayed on the display device. As a result, the display SOC approaches zero earlier than the actual SOC of the power storage device. This encourages the user of the electric vehicle to charge the power storage device early. Therefore, it is possible to prevent the electric vehicle from accidentally causing a fault such as a power shortage.

[0014] The display system may further include a storage device that stores the relationship between the control SOC and the OCV of the power storage device.

[0015] The processing device may correct the controlling SOC using the above relationship when the controlling SOC is equal to or greater than the first reference value or when the controlling SOC is lower than a second reference value that is smaller than the first reference value.

[0016] The index value may be calculated according to the elapsed time from the last time the control SOC was corrected using the above relationship.

[0017] The longer the time elapsed since the last correction of the control SOC, the easier it is for the calculation accuracy of the control SOC to decrease. Therefore, the elapsed time can appropriately reflect the degree of decrease in the calculation accuracy of the control SOC. By setting the above structure, the index value is calculated according to the elapsed time. Thus, it is possible to appropriately determine the decrease in the calculation accuracy of the control SOC according to the index value.

[0018] The difference between the control SOC and the display SOC may be increased as the elapsed time is longer.

[0019] By setting the above structure, the longer the time is (the lower the calculation accuracy of the control SOC is), the lower the display SOC becomes relative to the control SOC. Therefore, even if the calculation accuracy of the control SOC is greatly reduced, the display SOC is reliably displayed as lower than the actual SOC of the power storage device. As a result, the above-mentioned failure can be prevented more reliably.

[0020] When the elapsed time exceeds the threshold time, the processing device may execute display processing for causing the display device to display a screen urging a user of the electric vehicle to fully charge the power storage device.

[0021] By setting the above structure, the user is encouraged to fully charge the power storage device. When the power storage device is fully charged, the control SOC is greater than the first reference value, so the control SOC is corrected. Thus, even if the calculation accuracy of the control SOC decreases, it is restored to the original state. As a result, the above-mentioned fault can be prevented more effectively.

[0022] The index value may include the temperature of the power storage device. The index value exceeding the threshold value may include the temperature being lower than a threshold temperature serving as the threshold value.

[0023] The lower the temperature of the power storage device, the easier it is for the calculation accuracy of the control SOC to decrease. Therefore, the temperature can appropriately reflect the degree of decrease in the calculation accuracy of the control SOC. By setting the above structure, the index value is determined according to the temperature of the power storage device. As a result, it is possible to appropriately determine the decrease in the calculation accuracy of the control SOC according to the index value.

[0024] According to the present disclosure, it is possible to prevent a situation in which a failure of an electric vehicle unexpectedly occurs due to a decrease in the calculation accuracy of the SOC. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0026] Figure 1 This is a diagram for explaining the structure of a processing system equipped with the display system according to the first embodiment.

[0027] Figure 2 This is a diagram showing an example of a map stored in a storage device.

[0028] Figure 3 This is a diagram showing an example of changes in the control SOC and the display SOC.

[0029] Figure 4 This is a flowchart showing an example of processing executed by the ECU in the first embodiment.

[0030] Figure 5A The figure shows an example of a screen displayed on the display device.

[0031] Figure 5B The figure shows an example of a screen displayed on the display device.

[0032] Figure 6This is a flowchart showing an example of processing executed by the ECU in the modification of the first embodiment. DETAILED DESCRIPTION

[0033] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The same reference numerals are given to the same or corresponding parts in the drawings, and their description will not be repeated. The embodiments and their modifications may be appropriately combined with each other.

[0034] Implementation Method 1

[0035] Figure 1 1 is a diagram for explaining the configuration of a processing system equipped with a display system according to Embodiment 1. Figure 1 The processing system 1 includes a vehicle 10 , a charging device 20 , and a user terminal 30 .

[0036] The vehicle 10 is an electric vehicle, and in this example, a battery electric vehicle (BEV). The vehicle 10 includes a battery 105, a current sensor 107, a voltage sensor 108, a temperature sensor 110, a power control unit (PCU) 115, and a motor generator (MG) 120. The vehicle 10 also includes an inlet 130 and a dashboard 140. The vehicle 10 also includes a human machine interface (HMI) device 141, a gear lever 142, a storage device 145, a communication device 150, and an electronic control unit (ECU) 160.

[0037] The battery 105 stores electric power for traveling the vehicle 10. The battery 105 may be replaced by another type of power storage device such as an electric double layer capacitor.

[0038] The current sensor 107 detects the charge and discharge current of the battery 105 . The voltage sensor 108 detects the voltage of the battery 105 . The temperature sensor 110 detects the temperature of the battery 105 .

[0039] The PCU 115 is connected to the battery 105 and includes an inverter (not shown). The inverter receives the discharged power (DC power) from the battery 105, converts the DC power into AC power, and supplies it to the MG 120. The PCU 115 is used for charging and discharging control of the battery 105. The MG 120 receives the AC power from the PCU 115 and generates the driving force for the vehicle 10. During the regenerative braking of the vehicle 10, the MG 120 can function as a generator (regenerative power generation). The PCU 115 (inverter) is also configured to convert the AC power generated by the MG 120 into DC power, and supply the DC power to the battery 105 as charging power for the battery 105.

[0040] The socket 130 is configured to receive the power supplied from the charging device 20. The power supplied is used for external charging of the vehicle 10. External charging refers to charging the battery 105 using the power supplied. In this example, the power supplied is DC power, which is supplied from the charging device 20 to the battery 105 via the socket 130. The charging device 20 includes a charging start button (not shown) for the user to instruct the start of external charging. The button is pressed when the connector of the charging device 20 is inserted into the socket 130.

[0041] The instrument panel 140 functions as a display device that displays various state values ​​of the vehicle 10 , such as the measured values ​​of various meters of the vehicle 10 . The state values ​​include the value of the running speed of the vehicle 10 and the SOC of the battery 105 .

[0042] The HMI device 141 is a touch screen, and includes an input device and a display device (neither of which is shown in the figure). The input device receives an operation (user operation) performed by a user of the vehicle 10. The display device displays various screens. The screen may be a screen for car navigation or a screen indicating SOC.

[0043] The shift lever 142 is configured to be able to switch the speed range of the vehicle 10 according to a user operation. The speed range includes an N (neutral) range, an R (reverse) range, a D (drive) range, a P (parking) range, and a B (brake) range.

[0044] The storage device 145 stores various data. The data includes a mapping indicating the correspondence between the open circuit voltage (OCV) and the SOC of the battery 105. The communication device 150 wirelessly communicates with the user terminal 30 through short-distance communication or the like. The communication device 150 is also configured to exchange various information (e.g., information indicating that the charging start button is pressed by the user) with the charging device 20 through a controller area network (CAN) communication.

[0045] ECU 160 includes a memory and a processor (neither of which is shown in the figure). The memory includes a read-only memory (ROM) and a random access memory (RAM). The ROM stores programs executed by the processor. The RAM functions as a working memory. The processor is, for example, a central processing unit (CPU), which performs various calculations according to the above-mentioned programs.

[0046] ECU 160 controls various devices of vehicle 10. ECU 160 controls PCU 115, for example, to perform charge and discharge control of battery 105. When the SOC of battery 105 decreases excessively, ECU 160 controls PCU 115 to limit the discharge power of battery 105. As a result, the running speed (running acceleration) of vehicle 10 is limited.

[0047] ECU 160 receives information indicating the operation result of the shift lever 142, or receives information including the detection values ​​of various sensors. ECU 160 also functions as a processing device that performs various processes according to this information. In one example, ECU 160 calculates SOC by coulomb counting method according to the detection value of current sensor 107 (more specifically, the accumulated value of the detection value). The calculation result of SOC is used for charge and discharge control of battery 105. ECU 160 is also configured to calculate (correct) SOC according to the detection value of voltage sensor 108. This will be described in detail later.

[0048] ECU 160 starts external charging by sending a charge start command to charging device 20 via communication device 150. This command is sent in response to a user pressing a charge start button. When the SOC reaches the target SOC during external charging, a charge stop command is sent to charging device 20 via communication device 150. Thus, external charging is stopped. The target SOC is, for example, 80%.

[0049] ECU 160 is further configured to estimate the full charge capacity of battery 105 by dividing the charge amount (ΔAh) of battery 105 during external charging by the increase in SOC (ΔSOC) during external charging. ΔAh is calculated based on the detection value of current sensor 107 .

[0050] The user terminal 30 is, for example, a smartphone, and is carried by the user of the vehicle 10. The user terminal 30 includes a display device 305, a communication device 310, and a processing device 315. The display device 305 displays various screens. The communication device 310 communicates with the vehicle 10. The processing device 315 controls the display device 305 and the communication device 310 and performs various calculation processes.

[0051] Figure 2 145 is a diagram showing an example of a map stored in the storage device 145. Figure 2 , a map 400 shows a correspondence relationship between SOC and OCV (SOC-OCV curve). Each of the ranges R1, R2, and R3 shows an SOC range.

[0052] Range R1 is determined as a range in which the SOC is greater than 0 and less than Xa. Range R2 is determined as a range in which the SOC is greater than Xa and less than Xb (Xb>Xa). Range R3 is determined as a range in which the SOC is greater than Xb and less than 100. Ranges R1 and R3 are respectively SOC ranges in which the rate of change of OCV relative to SOC in map 400 is greater than a predetermined rate of change. Range R2 is an SOC range in which the rate of change is less than a predetermined rate of change. Xb is equivalent to an example of the "first reference value" of the present disclosure. Xa is equivalent to an example of the "second reference value" of the present disclosure.

[0053] ECU 160 calculates SOC according to the detection value (OCV) of voltage sensor 108 using map 400. When SOC is in range R1 or range R3, the slope of the curve is relatively steep. Therefore, ECU 160 can calculate SOC with good accuracy using map 400. On the other hand, when SOC is in range R2, the slope of the curve is relatively flat. Therefore, ECU 160 cannot calculate SOC with good accuracy using map 400.

[0054] Therefore, ECU 160 basically calculates SOC by the coulomb counting method according to the detection value of current sensor 107. Thus, the calculation accuracy of SOC can be improved compared with the comparative example in which SOC-OCV curve is always used to calculate SOC. On the other hand, when SOC is within range R1 or range R3, ECU 160 corrects SOC using map 400 at a predetermined timing. Specifically, ECU 160 corrects SOC by replacing the calculated value of SOC calculated by the coulomb counting method with the calculated value of SOC calculated using map 400. The predetermined timing when SOC is within range R1 refers to, for example, when battery 105 is fully charged by external charging.

[0055] When the SOC is calculated by the coulomb counting method as described above, the calculation result of the SOC is affected by the integrated value of the detection error (e.g., offset error) of the current sensor 107. In particular, if the period of calculating the SOC is prolonged without correcting the SOC using the map 400, the integrated value of the detection error increases to a non-negligible degree, and the calculation accuracy of the SOC may be greatly reduced.

[0056] As a result, the SOC of the battery 105 displayed on the display device such as the instrument panel 140 or the HMI device 141 no longer correctly reflects the actual charging state of the battery 105. Thus, even when the storage amount of the battery 105 is reduced, the user cannot correctly recognize that. In this case, although the user recognizes that the storage amount of the battery 105 has not decreased, the storage amount decreases to zero earlier than expected, and there is a possibility that the vehicle 10 may unexpectedly run out of power.

[0057] In the first embodiment, when the ECU 160 predicts such a possibility, it calculates the display SOC independently from the SOC described above (hereinafter also referred to as "control SOC"). As described above, the control SOC is used for charge and discharge control of the battery 105. When the calculation accuracy of the control SOC decreases, the display SOC is calculated according to the control SOC and displayed on a display device such as the instrument panel 140 or the HMI device 141. Specifically, the display SOC is calculated to be lower than the control SOC. The above situation is equivalent to the situation where the index value indicating the degree of decrease in the calculation accuracy of the control SOC exceeds a predetermined threshold. In other words, in the first embodiment, when the index value exceeds the threshold, the ECU 160 starts a calculation process to calculate the display SOC to be lower than the control SOC. This process is also referred to as "display SOC calculation process". In addition, before starting this process, it is considered that the calculation accuracy of the control SOC has not decreased much, and the control SOC is displayed on the display device as it is.

[0058] According to the display SOC calculation process, when the calculation accuracy of the control SOC decreases, the display SOC is calculated as a value lower than the control SOC and displayed on the display device. As a result, as long as the display SOC is lower than the actual SOC, the display SOC approaches zero earlier than the actual SOC of the battery 105. This prompts the user of the vehicle 10 to perform external charging earlier than usual in order to prevent power shortage. Therefore, it is possible to effectively prevent the accidental power shortage of the vehicle 10 caused by the reduction in the calculation accuracy of the control SOC. In this way, the display SOC calculation process contributes to the fault protection function for preventing the vehicle 10 from running out of power.

[0059] The index value is preferably calculated according to the elapsed time since the last correction of the control SOC using the map 400. In this example, the index value is calculated by the ECU 160 as a percentage [%] of the full charge capacity of the battery 105 of the multiplication value of the length of the elapsed time and the maximum value of the offset error of the current sensor 107. The value is calculated as a value indicating the maximum value of the error of the calculation result of the control SOC using the current sensor 107. The maximum value of the offset error is predetermined depending on the current sensor 107 and stored in the memory of the ECU 160. The index value exceeding the threshold value corresponds to the elapsed time exceeding the predetermined threshold time as the threshold value.

[0060] The longer the elapsed time is, the greater the impact of the cumulative value of the detection error on the calculation result of the control SOC is, so the calculation accuracy of the control SOC is more likely to decrease. Therefore, the elapsed time can appropriately reflect the degree of decrease in the calculation accuracy of the control SOC. By setting the above structure, the index value is determined according to the elapsed time (for example, the longer the elapsed time is, the larger the index value is). As a result, the ECU 160 can appropriately determine that the calculation accuracy of the control SOC has decreased according to the index value.

[0061] Figure 3 2 is a diagram showing an example of changes in the control SOC and the display SOC. Figure 3 , line 605 shows the change of the control SOC, and line 610 shows the change of the display SOC.

[0062] At time t0, the control SOC is X0 (>Xb), and is corrected using map 400. X0 is, for example, 100%. During the period from time t0 to time t1, the elapsed time from time t0 does not exceed the threshold time THT, so the index value does not exceed the threshold.

[0063] At time t1, the time elapsed from time t0 exceeds the threshold time THT. Therefore, the index value exceeds the threshold, so ECU 160 starts the display SOC calculation process. After time t1, ECU 160 calculates the display SOC while continuing to calculate the control SOC.

[0064] ECU 160 preferably calculates the display SOC so that the difference dif between the control SOC and the display SOC becomes larger as the elapsed time from time t0 increases. In this example, the difference dif at time tb is larger (db) than the difference dif at time ta (da).

[0065] ECU 160 calculates the display SOC in a manner such that the size of the difference dif is determined by the multiplication value of the offset error of the current sensor 107 and the length of the above-mentioned elapsed time. ECU 160 may also calculate the display SOC in a manner such that the size of the difference dif is determined by the multiplication value of the offset error and the length of the elapsed time from time t1 (the time obtained by subtracting the threshold time THT from the elapsed time from time t0). In this way, it is possible to avoid a situation where the SOC displayed on the display device drops sharply when the index value exceeds the threshold. The size of the difference dif may be determined according to the control SOC or according to the integrated value of the detection value of the current sensor 107.

[0066] When the display SOC is calculated as described above, as shown by lines 605 and 610, the longer the time from time t0 is (the lower the calculation accuracy of the control SOC is), the lower the display SOC becomes relative to the control SOC. Thus, even if a long time has passed since time t0 and the calculation accuracy of the control SOC has been greatly reduced, the display SOC is reliably displayed as being lower than the actual SOC of the battery 105. As a result, it is possible to more effectively encourage the user of the vehicle 10 to perform external charging earlier than usual. Therefore, it is possible to reliably prevent the vehicle 10 from being out of power due to the reduction in the calculation accuracy of the control SOC.

[0067] Figure 4 1 is a flowchart showing an example of processing executed by ECU 160 in Embodiment 1. This flowchart starts when correction of the control SOC is completed.

[0068] Reference Figure 4 ECU 160 calculates the index value according to the elapsed time from when the control SOC was last corrected (for example, time t0) (S105).

[0069] ECU 160 determines whether the index value exceeds the threshold value (S110). If the index value does not exceed the threshold value ("No" in S110), the process returns to S105. If the index value exceeds the threshold value ("Yes" in S110), ECU 160 determines that the calculation accuracy of the control SOC is reduced (S112), and starts the display SOC calculation process (S115). Thereafter, the process ends.

[0070] As described above, according to the first embodiment, the SOC calculated by the ECU 160 according to the detection value of the current sensor 107 includes the control SOC and the display SOC. When the index value exceeds the threshold value, the ECU 160 starts the display SOC calculation process to calculate the display SOC to be lower than the control SOC. Thus, when the calculation accuracy of the control SOC decreases, the user is prompted to perform external charging earlier than usual. Therefore, it is possible to prevent the unexpected power shortage of the vehicle 10 caused by the decrease in the calculation accuracy of the control SOC.

[0071] Modification 1 of Embodiment 1

[0072] When the indicator value exceeds the threshold (for example, Figure 3 At time t1), ECU 160 may also execute screen display processing for displaying a screen urging the user to fully charge battery 105 on the display device.

[0073] By setting such a structure, the user is urged to perform external charging in a manner that fully charges the battery 105. When the battery 105 is fully charged, the actual SOC is 100%, and the calculated value of the control SOC is also basically Xb ( Figure 2 ) or more, the control SOC is corrected by the ECU 160. Thus, even if the calculation accuracy of the control SOC decreases, it is restored to its original state. As a result, it is possible to more effectively prevent an unexpected power shortage of the vehicle 10 caused by a decrease in the calculation accuracy of the control SOC.

[0074] Figure 5A as well as Figure 5B FIG. 1 is a diagram showing an example of a screen displayed on a display device. Figure 5A In the example of FIG. 5 , the display device is the instrument panel 140. The screen display processing corresponds to the ECU 160 controlling the instrument panel 140 so as to display the screen 500. The screen 500 includes a message 505. The message 505 urges the user to perform external charging so as to fully charge the battery 105.

[0075] exist Figure 5B In the example of , the display device is the display device 305 of the user terminal 30. In this example, the screen display processing is equivalent to sending a display instruction to the user terminal 30 via the communication device 150 to display the screen 550. The processing device 315 of the user terminal 30 receives the display instruction via the communication device 310, and controls the display device 305 in a manner to display the screen 550 in response to the display instruction.

[0076] Screen 550 includes message 555, check box 560, and button 565. Message 555, like message 505, urges the user to fully charge battery 105. In order to increase the target SOC for the next external charging, the user checks check box 560. In this example, the target SOC is increased from 80% to 100% due to the user operation. In order to apply the increased target SOC, the user operates button 565.

[0077] The screen 550 may be displayed on the HMI device 141 instead of the display device 305 of the user terminal 30. In this case, the ECU 160 controls the HMI device 141 to display the screen 550 in accordance with the indicator value exceeding the threshold value. In this way, the screen display process may be a process of controlling the HMI device 141 to display the screen 550.

[0078] When the indicator value exceeds the threshold value during the running of the vehicle 10, the ECU 160 preferably performs the display SOC calculation processing and the screen display processing at the same time. For example, the screen 500 or the screen 550 preferably displays the indicator value exceeding the threshold value ( Figure 3 Before describing the advantages of executing these processes simultaneously, the following describes the cases A and B in which these processes are executed at different timings.

[0079] In case A, when the running index value of the vehicle 10 exceeds the threshold value, the display SOC calculation process is started before the screen display process. The user may feel that the storage amount of the battery 105 is likely to decrease after the start of the display SOC calculation process (specifically, during the period from the start of the process to the start of the screen display process). There is a possibility that the user misunderstands that this is caused by the deterioration of the battery 105, etc.

[0080] In case B, unlike case A, when the indicator value exceeds the threshold value during the driving of the vehicle 10, the display SOC calculation process is started after the screen display process. It is difficult to perform external charging while the vehicle 10 is driving, so it is also considered that the screen display process is preferably delayed until the end of the driving of the vehicle 10 (for example, when the gear lever 142 is switched to the P range). Therefore, in case B, there is a possibility that the display SOC calculation process is delayed until the next driving of the vehicle 10. As a result, the timing of prompting the user to fully charge the battery 105 may also be delayed. This may delay the timing of correcting the control SOC.

[0081] On the other hand, as described above, by executing the display SOC calculation process and the screen display process simultaneously, it is possible to avoid the unreasonable phenomenon caused in the cases A and B.

[0082] Figure 61 is a flowchart showing an example of processing executed by ECU 160 in this modification. Figure 6 , S205 to S215 are respectively the same as S105 to S115 of Embodiment 1 ( Figure 4 )same. Figure 6 Flowchart and Figure 4 The difference of the flowchart is that S220 is added.

[0083] ECU 160 starts the display SOC calculation process (S215), and simultaneously executes the screen display process (S220). In other words, S215 and S220 are executed simultaneously. Then, the process ends.

[0084] As described above, according to this modification, ECU 160 is further configured to execute screen display processing for displaying screens such as screen 500 on the display device. This encourages the user to perform external charging in a manner that fully charges battery 105. As a result, unexpected power shortages caused by reduced calculation accuracy of the control SOC can be more effectively prevented.

[0085] Modification 2 of Implementation Example 1

[0086] The ECU 160 preferably executes the SOC calculation process for display and the screen display process simultaneously, but may start the SOC calculation process for display before the screen display process as in case A. For example, the ECU 160 immediately starts the SOC calculation process for display when the index value during driving of the vehicle 10 exceeds a threshold value, and executes the screen display process when the driving of the vehicle 10 ends. By executing these processes in this way, the unreasonable phenomenon caused in case B can be avoided.

[0087] Alternatively, the ECU 160 may start the display SOC calculation process after the screen display process as in case B. For example, even if the index value exceeds the threshold value during the running of the vehicle 10, the ECU 160 does not start the display SOC calculation process, but executes the screen display process when the running of the vehicle 10 ends. Furthermore, the ECU 160 starts the display SOC calculation process when the next running starts (when the shift lever 142 is switched from the P range to the D range). By executing these processes in this way, the unreasonable phenomenon caused in case A can be avoided.

[0088] Implementation Method 2

[0089] The index value may also be the temperature of the battery 105 (the detection value of the temperature sensor 110). In the second embodiment, the index value exceeding the threshold value corresponds to the temperature of the battery 105 being lower than a predetermined threshold temperature as a threshold value. For example, when the temperature is lower than the threshold temperature, the ECU 160 starts the display SOC calculation process. The threshold temperature is, for example, 0°C, but is not limited thereto.

[0090] Generally speaking, the lower the battery temperature, the greater the internal resistance of the battery 105, and the more likely the calculation accuracy of the control SOC is to decrease. Therefore, the battery temperature can appropriately reflect the degree of decrease in the calculation accuracy of the control SOC. Therefore, the ECU 160 can appropriately determine that the calculation accuracy of the control SOC is reduced according to the index value.

[0091] From another point of view, the lower the battery temperature, the smaller the discharge power (output power) of the battery 105, so the driving force of the vehicle 10 is reduced. This is considered to be substantially equivalent to the fact that the storage amount of the battery 105 decreases and the running speed (running acceleration) of the vehicle 10 is limited. In this case, it can also be considered that calculating the display SOC to be lower than the control SOC helps the user recognize that a situation substantially the same as the situation in which the running speed of the vehicle 10 is limited due to the decrease in storage amount has occurred.

[0092] For example, when the battery temperature is lower than the threshold temperature during driving, the ECU 160 immediately starts the SOC calculation process for display, and executes the process for displaying a screen indicating that the battery temperature has dropped on the display device when the vehicle 10 stops driving. Alternatively, the ECU 160 may not start the SOC calculation process for display even if the battery temperature is lower than the threshold temperature. In this case, the ECU 160 may execute the process for displaying a screen indicating that the battery temperature has dropped on the display device when the vehicle 10 stops driving, and start the SOC calculation process for display when the vehicle 10 starts driving next time.

[0093] Other variations

[0094] The vehicle 10 may also be another type of electric vehicle such as a plug-in hybrid electric vehicle (PHEV). When the vehicle 10 is a PHEV, it also has an engine that can generate power for driving. The engine starts when the power storage of the battery 105 is reduced to zero. In a PHEV, when the calculation accuracy of the control SOC is reduced, although the user recognizes that the power storage of the battery 105 has not yet been reduced, the power storage is reduced to zero earlier than expected. As a result, there is a possibility that the engine is started unexpectedly. The reduction in the calculation accuracy of the control SOC means, for example, that the SOC displayed on the display device is incorrect. This may lead to reduced driving performance. On the other hand, according to the display SOC calculation process, the user is prompted to perform external charging, so that the unexpected start of the engine of the PHEV caused by the reduction of power storage can be avoided.

[0095] The power supplied from the charging facility 20 may be AC ​​power. In this case, the vehicle 10 may further include an on-board charger (not shown). The charger converts the AC power from the charging facility 20 into DC power for charging and supplies the DC power to the battery 105 .

[0096] As an example, the “display device” of the “display system” of the present disclosure may be any one of the dashboard 140 , the display device of the HMI device 141 , or the display device 305 of the user terminal 30 .

[0097] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A display system comprising: Display device; A power storage device that stores electricity for driving the electric vehicle; a current sensor for detecting a charge and discharge current of the power storage device; as well as a processing device that calculates the SOC of the power storage device according to the detection value of the current sensor, The SOC includes a control SOC used for charge and discharge control of the power storage device and a display SOC displayed on the display device and calculated based on the control SOC, The processing device starts a calculation process of calculating the display SOC to be lower than the control SOC when the index value indicating the degree of reduction in calculation accuracy of the control SOC exceeds a threshold value.

2. The display system according to claim 1, wherein: The display system further includes a storage device for storing a relationship between the control SOC and the OCV of the power storage device. The processing device corrects the controlling SOC using the relationship when the controlling SOC is equal to or greater than a first reference value or when the controlling SOC is lower than a second reference value that is smaller than the first reference value. The index value is calculated according to the elapsed time from the last time the control SOC was corrected using the relationship.

3. The display system according to claim 2, wherein: The longer the elapsed time is, the larger the difference between the control SOC and the display SOC is.

4. The display system according to claim 2 or 3, wherein: When the elapsed time exceeds a threshold time, the processing device performs a display process for displaying a screen on the display device to urge a user of the electric vehicle to fully charge the power storage device.

5. The display system according to claim 1, wherein: The index value includes the temperature of the power storage device, The indicator value exceeding a threshold value includes the temperature being lower than a threshold temperature serving as the threshold value.

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