Battery management device for electric vehicle

Abstract

To adjust a battery's SOC to suit a user's usage of an electric vehicle while suppressing battery degradation.SOLUTION: A battery management device 10 of an electric vehicle 1 includes a motor 21, a battery 28 that stores electrical energy to be supplied to the motor, and a control device 35 that controls the charging of the battery. The control device acquires information (ΔSOC) about the SOC of the battery that has decreased as the user uses the electric vehicle between battery charges, sets an upper limit SOC for the battery on the basis of the acquired ΔSOC and the battery capacity, and stops charging of the battery based on the set upper limit SOC.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed herein relates to a battery management device for an electric vehicle. [Background technology]

[0002] Patent Document 1 describes a conventional battery remaining capacity display device. The battery remaining capacity display device displays the remaining capacity of a battery installed in an electric vehicle on a predetermined scale. The battery remaining capacity display device displays the remaining battery capacity by reducing the scale according to the deterioration of the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-217692 Summary of the Invention [Problem to be solved by the invention]

[0004] Batteries installed in electric vehicles deteriorate due to repeated charging and discharging. However, it is possible to control battery charging to suppress battery deterioration. For example, repeated charging and discharging when the battery's SOC (State of Charge) is relatively high, or conversely, repeated charging and discharging when the SOC is relatively low, can easily cause battery deterioration. Battery deterioration can be suppressed if the battery is charged and discharged within an SOC range where battery deterioration is unlikely.

[0005] For example, it is conceivable to suppress battery degradation by forcibly ending battery charging according to a predetermined upper SOC limit so that the battery SOC does not become too high. However, the manner in which electric vehicles are used varies from user to user. For example, one user's battery SOC decreases relatively small during one drive, but charges frequently. Another user's battery SOC decreases relatively small during one drive, but charges infrequently. Another user's battery SOC decreases relatively large during one drive, but charges infrequently. Another user's battery SOC decreases relatively large during one drive, but charges frequently. The decrease in battery SOC (i.e., ΔSOC) caused by the user's use of the electric vehicle between battery charges differs from user to user.

[0006] Therefore, if the charging of the battery is uniformly controlled in accordance with a predetermined upper limit SOC, the SOC of the battery may become insufficient depending on the usage pattern of the user.

[0007] The technology disclosed herein suppresses battery degradation while adapting the battery's SOC to the manner in which the user uses the electric vehicle. [Means for solving the problem]

[0008] The technology disclosed herein relates to a battery management device for an electric vehicle. a motor mounted on the electric vehicle and outputting a driving force for running the electric vehicle; a battery for storing electrical energy to be supplied to the motor; a control device that controls charging of the battery, The control device acquiring information (ΔSOC) of the SOC of the battery that has decreased due to use of the electric vehicle by a user between charges of the battery; setting an upper limit SOC of the battery based on the acquired ΔSOC and the capacity of the battery; Charging of the battery is stopped according to the set upper limit SOC.

[0009] An electric vehicle runs by having a motor that receives electrical energy from a battery and outputs driving force for running. As the driving distance of an electric vehicle increases, the battery's SOC decreases. When the battery's SOC decreases, electric vehicle users charge the battery. Charging the battery increases the battery's SOC.

[0010] The control device acquires information (ΔSOC) about the battery SOC that has decreased as the user uses the electric vehicle between battery charges. ΔSOC reflects how the user uses the electric vehicle. The usage of the electric vehicle includes the distance traveled during one drive and / or the frequency of charging. For example, if the battery SOC decreases relatively little during one drive but the user charges frequently, ΔSOC will be relatively small. If the battery SOC decreases relatively much during one drive but the user charges infrequently, ΔSOC will be relatively large. Note that one drive refers to the period from when the user gets into the electric vehicle and the electric vehicle starts moving, until the electric vehicle stops and the user gets out of the electric vehicle.

[0011] The control device sets an upper limit SOC of the battery based on the acquired ΔSOC and the capacity of the battery, and also stops charging of the battery in accordance with the set upper limit SOC.

[0012] When ΔSOC is sufficiently small compared to the battery capacity, for example, the upper limit SOC of the battery is set relatively low. Even if battery charging is stopped due to the set upper limit SOC, the battery can still store the electrical energy required for the user's usage. Because the upper limit SOC of the battery is set relatively low and battery charging is stopped in accordance with the low upper limit SOC, charging and discharging of the battery at a high SOC is avoided. Battery degradation is suppressed.

[0013] The control device may store information about the acquired ΔSOC, and set the upper limit SOC based on a frequency distribution of the ΔSOC.

[0014] Based on the frequency distribution of ΔSOC acquired up to that point, the user's usage pattern can be identified with greater accuracy. By setting the upper limit SOC of the battery based on the frequency distribution of the accumulated ΔSOC, the control device can optimize battery charging and discharging for the user.

[0015] The control device may set the upper limit SOC within a first range of SOC in which deterioration of the battery is suppressed, the first range being predetermined for the battery, so that the ΔSOC is included in the first range.

[0016] If the upper limit SOC is set within the first range, the control device can charge and discharge the battery within the first SOC range in which battery degradation is suppressed. The battery management device can suppress battery degradation while maintaining the battery SOC within a range suited to the user's usage pattern.

[0017] The control device may further set the upper limit SOC within a second range of SOC such that the ΔSOC falls within the second range in which the driving force of the motor is favorable with respect to the discharge of the battery.

[0018] If the control device sets the upper limit SOC taking into consideration both the first SOC range in which battery degradation is suppressed and the second SOC range in which the motor's driving force is good, the battery SOC can be adapted to the user's usage pattern, while both suppressing battery degradation and improving the driving performance of the electric vehicle can be achieved.

[0019] The second range of the SOC may be predetermined, or may be learned and set based on the manner in which the user uses the electric vehicle.

[0020] The second SOC range in which the motor's driving force is good is predetermined depending on the type of battery, for example, as the SOC range in which a large current can be output. The second SOC range in which the motor's driving force is good also varies depending on how the user uses the electric vehicle. The second SOC range is optimized by being predetermined or learned based on how the user has used the electric vehicle in the past.

[0021] The control device may further set the upper limit SOC within a third range of SOC in which the electric vehicle has good electricity efficiency when charging the battery, so that the ΔSOC falls within the third range.

[0022] If the control device sets the upper limit SOC taking into consideration both the first range of SOC in which battery degradation is suppressed and the third range of SOC in which electricity consumption is good, the battery SOC can be adapted to the user's usage patterns, while both suppressing battery degradation and improving the electricity consumption of the electric vehicle can be achieved.

[0023] The third range of the SOC may be predetermined, or may be learned and set based on the manner in which the user uses the electric vehicle.

[0024] The third SOC range in which power consumption is good is predetermined depending on the type of battery, for example, as a range of SOC in which charging efficiency is high. The third SOC range in which power consumption is good also varies depending on how the user uses the electric vehicle. The third SOC range is optimized by being predetermined or learned based on how the user has used the electric vehicle in the past.

[0025] The battery management device for the electric vehicle further includes a display device that displays the SOC of the battery, The display device may display the set upper limit SOC as 100%.

[0026] If the set upper limit SOC is lower than the maximum SOC based on the battery capacity, the battery SOC displayed on the display device will be less than 100% even after the battery is fully charged. Therefore, the display device may display the set upper limit SOC as 100%. In other words, even if the battery SOC after fully charged is lower than the maximum SOC, the display device will display the SOC as 100%. This reduces the sense of discomfort felt by the user.

[0027] the control device sets a lower limit SOC of the battery based on the upper limit SOC and the ΔSOC; The display device may display a message urging the user to charge the battery based on the set lower limit SOC.

[0028] In other words, even if the battery SOC is sufficiently below the minimum SOC based on the battery capacity, if the battery SOC approaches the set lower limit SOC of the battery, the display device will prompt the user to charge. As a result, the battery is charged and discharged within a ΔSOC range that corresponds to the user's usage of the electric vehicle. Battery degradation is further suppressed.

[0029] The display device may display the lower limit SOC as 0%.

[0030] If the set lower limit SOC is higher than the lowest SOC based on the battery capacity, the user will be prompted to charge the battery even if the SOC is sufficiently high. To reduce the user's discomfort, the display device may display the set lower limit SOC as 0%. When the display urging the user to charge the battery is displayed, the user is informed that the battery's SOC is low, reducing the user's discomfort. [Effects of the Invention]

[0031] The battery management device for an electric vehicle described above can suppress battery degradation while adapting the battery's SOC to the manner in which the user uses the electric vehicle. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a block diagram of an electric vehicle. [Figure 2] FIG. 2 shows a flow for setting the battery's usable SOC range in accordance with the manner in which the user uses the electric vehicle. [Figure 3] FIG. 3 shows an example of a display on the display device relating to the SOC of the battery. [Figure 4] FIG. 4 shows an example of a display on the display device relating to the SOC of the battery. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, an embodiment of a battery management device for an electric vehicle will be described with reference to the drawings. The battery management device for an electric vehicle described here is an example.

[0034] (Electric vehicle configuration) 1 shows the configuration of an electric vehicle 1. The electric vehicle 1 is a so-called BEV (Battery Electric Vehicle). A battery management device 10 is mounted on the electric vehicle 1.

[0035] The electric vehicle 1 is equipped with an electric motor 21. The electric motor 21 outputs driving force for running the electric vehicle 1. The electric motor 21 is connected to the left and right drive wheels 15 via a reduction gear 17 and an axle 16. The reduction gear 17 and the axle 16 transmit the output of the electric motor 21 to the drive wheels 15.

[0036] The electric vehicle 1 includes an inverter 25. The inverter 25 is connected to the electric motor 21. The inverter 25 supplies an AC current to the electric motor 21. The electric motor 21 receives the AC current from the inverter 25 and operates.

[0037] The electric vehicle 1 includes a battery 28. The battery 28 stores electric energy to be supplied to the electric motor 21. The battery 28 is connected to an inverter 25. The inverter 25 converts the direct current from the battery 28 into alternating current.

[0038] A charger 26 is connected to the battery 28. The charger 26 has a socket 261. A charging plug 262 is inserted into the socket 261. The charger 26 receives a current supply from an external power source and charges the battery 28.

[0039] The battery management device 10 includes an SOC calculation unit 31. The SOC calculation unit 31 is connected to the battery 28 and calculates the SOC of the battery 28 based on the current / voltage of the battery 28.

[0040] The battery management device 10 has a display device 33. The display device 33 displays information related to the SOC of the battery 28. A passenger in the electric vehicle 1 can recognize the SOC of the battery 28 by looking at the display on the display device 33.

[0041] The battery management device 10 has a control device 35. The control device 35 is connected to the SOC calculation unit 31 and the display device 33. The control device 35 acquires information about the SOC of the battery 28 from the SOC calculation unit 31, and provides the information about the SOC of the battery 28 to the display device 33.

[0042] The battery management device 10 has a communication device 37. The communication device 37 performs wireless bidirectional communication with the server 4. The electric vehicle 1 is a connected car. As will be described later, the communication device 37 may transmit information about the SOC of the battery 28 to the server 4.

[0043] The battery management device 10 has a storage device 39. As will be described later, the storage device 39 stores information relating to the user's usage of the electric vehicle 1. The control device 35 reads out the information stored in the storage device 39 from the storage device 39 and uses it.

[0044] (Setting the battery SOC range) The battery management device 10 suppresses deterioration of the battery 28. More specifically, the battery management device 10 takes into consideration the manner in which the user uses the electric vehicle 1 and sets a usage range of the SOC of the battery 28 that is suited to the user and in which deterioration of the battery 28 is suppressed, and charges and discharges the battery 28 within that usage range.

[0045] FIG. 2 shows a flow for setting the operating SOC range of the battery 28. First, in step S21, the battery management device 10 acquires the SOC (i.e., ΔSOC) of the battery 28 that decreases as the user uses the electric vehicle 1 between charges of the battery 28. The battery management device 10 repeatedly acquires the ΔSOC. The acquired ΔSOC information is stored in the storage device 39. When a large number of ΔSOCs are acquired, a frequency distribution of the ΔSOC is obtained. The frequency distribution of the ΔSOC reflects the manner in which the user uses the electric vehicle 1. For example, if the SOC of the battery that decreases during one drive is relatively small, but the user charges frequently, the ΔSOC will be relatively small and the frequency of small ΔSOCs will be high. If the SOC of the battery that decreases during one drive is relatively large, but the user charges infrequently, the ΔSOC will be relatively large and the frequency of large ΔSOCs will be high.

[0046] Furthermore, even for the same user, for example, on weekdays, the electric vehicle 1 may be used for commuting, so the driving distance is relatively short and the battery SOC decrease during one drive may be relatively small, while on weekends, the electric vehicle 1 may be used for long trips, so the driving distance is relatively long and the battery SOC decrease during one drive may be relatively large. The battery management device 10 repeatedly acquires ΔSOC in association with date and time information.

[0047] Once the frequency distribution of ΔSOC is obtained, the battery management unit 10 calculates the ΔSOC required for the user based on the frequency distribution of ΔSOC in the next step S22. The required ΔSOC is a ΔSOC that satisfies the expected driving distance until the user's next charge. The required ΔSOC on weekdays and the required ΔSOC on weekends may differ.

[0048] In step S23, the battery management device 10 sets a usable SOC range in accordance with the required ΔSOC calculated in step S22. The usable SOC range refers to the range of SOC used to satisfy the user's required ΔSOC between the maximum SOC and the minimum SOC based on the capacity of the battery 28.

[0049] When setting the usable SOC range in step S23, the battery management unit 10 takes into consideration the SOC range in which deterioration of the battery 28 is suppressed (i.e., the first range) (step S24). Charging and discharging in a high SOC range (e.g., SOC 80-100%) or a low SOC range (e.g., SOC 0-20%) accelerates deterioration of the battery 28. Charging and discharging in a SOC range of 20-80% suppresses deterioration of the battery 28. In this case, the SOC range in which deterioration of the battery 28 is suppressed is the SOC range of 20-80%. The SOC range in which deterioration of the battery 28 is suppressed is determined in advance (i.e., preset) depending on, for example, the type of battery 28.

[0050] The battery management device 10 sets an upper limit SOC of the battery 28 within the SOC range that suppresses deterioration of the battery 28 so that the required ΔSOC is included in the SOC range that suppresses deterioration of the battery 28. The upper limit SOC is an SOC at which charging of the battery 28 is stopped when charging the battery 28.

[0051] The battery management device 10 also sets a lower limit SOC for the battery management device 10 based on the set upper limit SOC and the required ΔSOC. The lower limit SOC is also set within an SOC range that suppresses deterioration of the battery 28. As will be described later, the lower limit SOC is an SOC that displays a message urging the user to charge the battery 28.

[0052] When setting the usable SOC range in step S23, the battery management device 10 may also take into consideration the SOC range (i.e., the second range) in which the driving force of the electric motor 21 is good (step S25). The SOC range in which the driving force of the electric motor 21 is good is determined in advance (i.e., preset) depending on the type of battery 28, for example, as the SOC range in which a large current can be output. The SOC range in which the driving force of the electric motor 21 is good also varies depending on how the user uses the electric vehicle 1. The SOC range in which the driving force of the electric motor 21 is good may be learned and set based on how the user has used the electric vehicle 1 in the past.

[0053] The lower limit of the SOC range in which the driving force of the electric motor 21 is good may be determined, for example, by learning the acceleration range that is used frequently from the acceleration distribution of the electric vehicle 1, or by learning the speed range that is used frequently from the speed distribution of the electric vehicle 1, or by learning the temperature that is measured frequently from the temperature distribution of the battery 28 while the electric vehicle 1 is in use.

[0054] The battery management device 10 may set an upper limit SOC for the battery 28 so that the required ΔSOC is included in an SOC range that suppresses deterioration of the battery 28 and an SOC range that provides good driving force for the electric motor 21. If the upper limit SOC is set taking into consideration both the SOC range that suppresses deterioration of the battery 28 and the SOC range that provides good driving force for the electric motor 21, it is possible to both suppress deterioration of the battery 28 and improve the driving performance of the electric vehicle 1.

[0055] If the required ΔSOC cannot be included in both the SOC range in which deterioration of the battery 28 is suppressed and the SOC range in which the driving force of the electric motor 21 is good, the SOC range in which deterioration of the battery 28 is suppressed takes priority (i.e., priority 1). This is because the battery management device 10 prioritizes suppressing deterioration of the battery 28.

[0056] The battery management device 10 may further consider a range of SOC that provides good electricity efficiency (i.e., a third range) when setting the usable SOC range in step S23 (step S26). The SOC range that provides good electricity efficiency is determined in advance (i.e., preset) depending on the type of battery 28, for example, as a range of SOC that provides high charging efficiency. The SOC range that provides good electricity efficiency also varies depending on how the user uses the electric vehicle 1. The SOC range that provides good electricity efficiency may be learned and set based on how the user has used the electric vehicle 1 in the past.

[0057] The SOC range that provides good fuel economy may be determined, for example, by learning the deceleration rate that is frequently used from the distribution of deceleration rates of the electric vehicle 1, or by learning the speed range that is frequently used from the distribution of speeds of the electric vehicle 1, or by learning the temperature that is frequently measured from the temperature distribution of the battery 28 while the electric vehicle 1 is in use.

[0058] The battery management device 10 may set an upper limit SOC for the battery 28 so that the required ΔSOC is included in an SOC range that suppresses degradation of the battery 28 and an SOC range that provides good electricity efficiency. If the upper limit SOC is set taking into consideration both the SOC range that suppresses degradation of the battery 28 and the SOC range that provides good electricity efficiency, then both suppression of degradation of the battery 28 and improvement of the electricity efficiency of the electric vehicle 1 can be achieved.

[0059] In addition, if the required ΔSOC cannot be included in both the SOC range in which deterioration of battery 28 is suppressed and the SOC range in which electricity efficiency is good, the SOC range in which deterioration of battery 28 is suppressed takes priority.

[0060] The battery management device 10 may set an upper limit SOC of the battery 28 so that the required ΔSOC is within an SOC range in which deterioration of the battery 28 is suppressed, an SOC range in which the driving force of the electric motor 21 is good, and an SOC range in which the electricity consumption is good.

[0061] When comparing the SOC range in which the driving force of the electric motor 21 is good with the SOC range in which the electricity cost is good, the SOC range in which the driving force of the electric motor 21 is good has a higher priority (i.e., priority 2 and priority 3). If the required ΔSOC cannot be included in both the SOC range in which the driving force of the electric motor 21 is good and the SOC range in which the electricity cost is good, the battery management unit 10 may set the usable SOC range by prioritizing the SOC range in which the driving force of the electric motor 21 is good.

[0062] Once the usage SOC range is set in step S23, the battery management device 10 selects a weekday usage SOC range (step S27) or a weekend usage SOC range (step S28) depending on the day on which the electric vehicle 1 is used. As described above, in step S21, both the ΔSOC on weekdays and the ΔSOC on weekends are acquired, and both are reflected in the usage SOC range set in step S23.

[0063] If the day on which the electric vehicle 1 is used is a weekday, the battery management device 10 selects a weekday usage SOC range that takes into account the ΔSOC on weekdays, and if the day on which the electric vehicle 1 is used is a weekend, the battery management device 10 selects a weekend usage SOC range that takes into account the ΔSOC on weekends. The usage SOC range is optimized to the usage situation of the electric vehicle 1.

[0064] (Display of battery SOC on display device) Next, the setting of the aforementioned usable SOC range will be specifically explained with reference to FIG. 3 or 4, and the display of the battery SOC by the display device 33 according to the setting of the usable SOC range will be explained.

[0065] 301 in Fig. 3 illustrates an example of the actual capacity of the battery 28 mounted on the electric vehicle 1. The electric vehicle 1 does not charge or discharge the battery 28 within a range from the lowest SOC (i.e., 0%) to the highest SOC (i.e., 100%) based on the actual capacity of the battery 28, but charges or discharges the battery 28 with a minimum SOC that is higher than the lowest SOC based on the actual capacity (5% in the example of Fig. 3) and a maximum SOC that is lower than the highest SOC based on the actual capacity (95% in the example of Fig. 3).

[0066] 302 in FIG. 3 shows an example of a display of the battery SOC by the display device 33. "Meter SOC" refers to the display of the battery SOC by the display device 33. In display example 1 of 302 in FIG. 3, the aforementioned use SOC range is not set. The display device 33 displays the SOC of the battery 28 within the range of SOC in which charging and discharging of the battery 28 are actually performed, with the minimum SOC being 0% and the maximum SOC being 100%. Furthermore, when the SOC of the battery 28 falls below 20%, the display device 33 displays a message urging the occupant of the electric vehicle 1 to charge the battery 28 (i.e., a message indicating that charging is required).

[0067] 303 in FIG. 3 shows an example of the display of the battery SOC by the display device 33 when a usage SOC range has been set. Here, the usage SOC range is set to 60-80%, as indicated by the outlined arrow in FIG. 3. In other words, the SOC that drops due to the user's use of the electric vehicle 1 between charges (i.e., the required ΔSOC) is 20%, and here the usage SOC range is set so that the upper limit SOC is 80% and the lower limit SOC is 60%. Note that the usage SOC range that satisfies a required ΔSOC of 20% is not limited to 60-80%. The upper limit SOC may be 60% and the lower limit SOC may be 40%.

[0068] If the upper limit SOC is set to 80%, the battery management device 10 will stop charging the battery 28 if the SOC reaches 80%. As described above, the upper limit SOC is set within an SOC range that at least suppresses deterioration of the battery 28, so stopping charging of the battery 28 at an SOC of 80% suppresses deterioration of the battery 28. Even if the SOC of the battery 28 after charging is 80%, the user's required ΔSOC is 20%, so as long as the user uses the electric vehicle 1 as usual, the electric vehicle 1 will not run out of power.

[0069] When an upper limit SOC is set, the display device 33 may display a value corresponding to the actual SOC of the battery 28. That is, when charging of the battery 28 is stopped when the SOC reaches 80%, the display device 33 may display the SOC as 80%.

[0070] However, even when charging of the battery 28 is complete, if the SOC of the battery 28 displayed on the display device 33 is less than 100%, the user may feel uncomfortable. Therefore, the display device 33 may display the set upper limit SOC as 100%, as shown in display example 2. In other words, even if the SOC of the battery 28 when charging of the battery 28 is complete is lower than the highest SOC, the display device 33 displays that the SOC is 100%. This alleviates the user's discomfort.

[0071] When the battery management device 10 sets a lower limit SOC along with an upper limit SOC, the display device 33 may display a message indicating that charging is required when the SOC of the battery 28 reaches the lower limit SOC to prompt the user to charge the battery 28 (see display example 3 of 304 in FIG. 3). If the user charges the battery 28 in accordance with the message indicating that charging is required, the battery 28 is charged and discharged between the upper limit SOC and the lower limit SOC. As a result, deterioration of the battery 28 is suppressed.

[0072] The display device 33 may set the numerical value of the lower limit SOC according to a scale in which the upper limit SOC is displayed as 100%. In display example 3, the display device 33 displays 75%, which corresponds to the lower limit SOC, and also displays a message that charging is required.

[0073] If the charge-required display is displayed when the SOC of battery 28 is relatively high, as in display example 3, the user may feel uncomfortable. Therefore, display device 33 may display the set lower limit SOC as 0%, as shown in display example 4 305 of FIG. 3 . In other words, even if the actual SOC of battery 28 is not 0%, display device 33 displays that the SOC is 0%. In display example 4, the user does not feel uncomfortable even when the charge-required display is displayed.

[0074] Fig. 4 shows an example of the display on display device 33 when, for example, a weekend use SOC range is set. In this case, Fig. 3 may also show an example of the display on display device 33 when, for example, a weekday use SOC range is set. Assume that the driving distance on weekends is longer than on weekdays, and the amount of decrease in SOC of battery 28 is relatively large. The required ΔSOC for weekends is larger than the required ΔSOC for weekdays, and therefore the weekend use SOC range (30-70%) is wider than the weekday use SOC range (60-80%).

[0075] 401 and 402 in Fig. 4 are the same as 301 and 302 in Fig. 3. As shown in display example 4 of 403 in Fig. 4, if the upper limit SOC is set to 70%, the battery management unit 10 will stop charging the battery 28 when the SOC reaches 70%.

[0076] The display device 33 may display the SOC of the battery 28, or may display the upper limit SOC as 100% as shown in display example 4 403 in FIG.

[0077] 4, when the SOC of the battery 28 reaches the lower limit SOC, the display device 33 may display a message indicating that charging is required to prompt the user to charge the battery 28. Furthermore, as shown in display example 6 of 405 in FIG. 4, the display device 33 may display the set lower limit SOC as 0%.

[0078] The battery management device 10 may constantly set the usable SOC range. Alternatively, the battery management device 10 may set the usable SOC range in response to a user selection. That is, when the user selects the degradation suppression mode for the battery 28, the battery management device 10 may set the upper limit SOC, the lower limit SOC, and the usable SOC range according to the procedure shown in FIG. 2, and the display device 33 may display the SOC of the battery 28 according to 303, 304, and 305 in FIG. 3 or 403, 404, and 405 in FIG. 4. When the user does not select the degradation suppression mode for the battery 28, the battery management device 10 may not set the upper limit SOC, the lower limit SOC, and the usable SOC range, and the display device 33 may display the actual SOC of the battery 28 according to 302 in FIG. 3 or 402 in FIG. 4.

[0079] (Variation) In the battery management device 10 described above, the on-board control device 35 acquires ΔSOC information in step S21 of FIG. 2 and sets the usable SOC range in step S23. However, for example, the server 4 may acquire ΔSOC information in step S21 of FIG. 2 via the communication device 37 and set the usable SOC range in step S23. The control device 35 acquires information about the usable SOC range set by the server 4 via the communication device 37. The control device 35 controls the charging and discharging of the battery 28 based on the information about the usable SOC range set by the server 4, and also controls the display on the display device 33. The battery management device is not limited to being on-board, and the control device may be located outside the vehicle. [Explanation of symbols]

[0080] 1 Electric vehicle 21 Electric motor 28 Battery 33 Display device 35 Control device

Claims

1. a motor mounted on the electric vehicle and outputting a driving force for running the electric vehicle; a battery for storing electrical energy to be supplied to the motor; a control device that controls charging of the battery, The control device acquiring information (ΔSOC) of an SOC of the battery that has decreased due to use of the electric vehicle by a user between charges of the battery; setting an upper limit SOC of the battery based on the acquired ΔSOC and the capacity of the battery; Charging of the battery is stopped according to the set upper limit SOC. Battery management device for electric vehicles.

2. The battery management device for an electric vehicle according to claim 1, The control device accumulates the acquired information on the ΔSOC and sets the upper limit SOC based on a frequency distribution of the ΔSOC. Battery management device for electric vehicles.

3. The battery management device for an electric vehicle according to claim 1, the control device sets the upper limit SOC within a first range of SOC in which deterioration of the battery is suppressed, the first range being predetermined for the battery, so that the ΔSOC is included in the first range; Battery management device for electric vehicles.

4. The battery management device for an electric vehicle according to claim 3, The control device further sets the upper limit SOC within a second range of SOC in which the driving force of the motor is good with respect to the discharge of the battery so that the ΔSOC is included in the second range. Battery management device for electric vehicles.

5. The battery management device for an electric vehicle according to claim 4, The second range of the SOC is predetermined or is learned and set based on a usage pattern of the electric vehicle by a user. Battery management device for electric vehicles.

6. The battery management device for an electric vehicle according to claim 3 or 4, The control device further sets the upper limit SOC within a third range of SOC in which the electric vehicle has good electricity efficiency when charging the battery, so that the ΔSOC is included in the third range. Battery management device for electric vehicles.

7. The battery management device for an electric vehicle according to claim 6, The third range of the SOC is predetermined or is learned and set based on a usage pattern of the electric vehicle by a user. Battery management device for electric vehicles.

8. The battery management device for an electric vehicle according to claim 1, a display device that displays the SOC of the battery; The display device displays the set upper limit SOC as 100%. Battery management device for electric vehicles.

9. The battery management device for an electric vehicle according to claim 8, the control device sets a lower limit SOC of the battery based on the upper limit SOC and the ΔSOC; The display device displays a message urging the user to charge the battery based on the set lower limit SOC. Battery management device for electric vehicles.

10. The battery management device for an electric vehicle according to claim 9, The display device displays the lower limit SOC as 0%. Battery management device for electric vehicles.

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