Battery control device and recording medium

Abstract

The present invention performs efficient charging / discharging control without waste for an in-vehicle battery when a vehicle travels in a successive slope section including at least one upward section and at least one downward section. A battery control device according to the present disclosure performs each process of: calculating a predicted regeneration value for the amount of regenerative current through a battery in a downward section belonging to the successive slope section; temporarily determining, as an initial current value, the amount of discharge current from the battery in a non-downward section belonging to the successive slope section; and determining a limit value for the amount of discharge current in the non-downward section by adjusting the initial current value on the basis of a temperature rise value of the battery in the successive slope section in consideration of the calculated predicted regeneration value and the amount of discharge current.

Description

Battery control device and recording medium

[0001] The present disclosure relates to a battery control device and a recording medium that are applied to an electrically powered vehicle such as an electric car equipped with a battery.

[0002] A vehicle equipped with an electric motor that can be driven by power supplied from a battery (hereinafter referred to as an "electric vehicle") has a battery control device that controls the charging and discharging of the battery. The battery control device monitors the temperature of the on-board battery to ensure that it does not exceed a predetermined operating range, and if the battery temperature is about to exceed an upper temperature limit, it controls the temperature by restricting the charging and discharging as described above.

[0003] For example, on an uphill road, which requires a higher output than on a flat road or a downhill road, the amount of discharge from the battery increases, and the cells tend to become hot due to heat generated by internal resistance, etc. For this reason, for example, Patent Document 1 proposes a battery charge / discharge control device that, when it is determined based on the road conditions ahead of the vehicle that there is an uphill road, limits the battery charge / discharge to a lower upper temperature limit than normal until the vehicle enters the uphill road.

[0004] Furthermore, for example, Patent Document 2 proposes a charge / discharge control device that determines whether the temperature of an on-board battery is above a predetermined temperature while the vehicle is running, and limits charging of the battery when the battery temperature is above threshold A, and limits both charging and discharging of the battery when the battery temperature is above threshold B, which is higher than threshold A.

[0005] JP 2012-116411 A JP 2019-41460 A

[0006] However, current technologies, including those described in the above-mentioned patent documents, do not adequately meet market needs, and the following problems exist. Specifically, the charge / discharge control devices proposed in the above-mentioned patent documents can certainly control the battery temperature so that it does not reach its upper limit on uphill roads. However, the prior art, including these patent documents, only controls charge / discharge taking uphill roads into consideration, and does not attempt to maximize the amount of regenerative current on downhill roads.

[0007] For this reason, in the prior art, when a vehicle travels on a section with a continuous gradient that includes an uphill section and a downhill section, if the battery temperature reaches its upper limit after the vehicle has finished traveling on the uphill section, there is a risk that the battery will exceed the upper temperature limit due to charging by regenerative braking on the subsequent downhill section. This poses a problem in that braking by regenerative braking on the downhill section cannot be used, and the electrical energy that would have been obtained by this regenerative braking will be wasted.

[0008] The present disclosure has been made in consideration of the above-mentioned problems as an example, and aims to provide a battery control device and a recording medium, etc., that are capable of performing efficient charge and discharge control without waste for a battery mounted on a vehicle traveling on the above-mentioned continuous gradient section.

[0009] In order to solve the above problem, according to one aspect of the present disclosure, there is provided a battery control device that controls charging and discharging of a battery mounted on a vehicle in a continuous gradient section that includes at least one uphill section and at least one downhill section, the battery control device including: a processor; and a memory capable of storing a program executed by the processor, wherein the processor executes the following processes: a regeneration prediction value calculation process that calculates a regeneration prediction value of the amount of regenerative current to the battery in a downhill section that belongs to the continuous gradient section; a discharge current amount provisional determination process that provisionally determines the amount of discharge current from the battery in a non-descent section other than the downhill section that belongs to the continuous gradient section as an initial current value, which is the current value flowing from the battery before entering the continuous gradient section; and a limit current value determination process that determines a limit value of the amount of discharge current in the non-descent section by adjusting the initial current value based on the temperature rise value of the battery in the continuous gradient section taking into account the calculated regeneration prediction value and the discharge current amount.

[0010] In addition, in order to solve the above problem, according to another aspect of the present disclosure, there is provided a recording medium having recorded thereon a computer program that causes a computer to execute the following steps: calculate a regenerative prediction value of the amount of regenerative current to a battery mounted on a vehicle in a downhill section belonging to a continuous gradient section that includes at least one uphill section and at least one downhill section; provisionally determine, as an initial current value, the amount of discharge current from the battery in a non-downhill section other than the downhill section belonging to the continuous gradient section, by using the current value flowing from the battery before entering the continuous gradient section; and determine a limit value for the amount of discharge current in the non-downhill section by adjusting the initial current value based on the temperature rise value of the battery in the continuous gradient section taking into account the calculated regenerative prediction value and the discharge current amount.

[0011] According to the present disclosure, when a vehicle travels through the above-described section with continuous gradients, it is possible to perform efficient charge / discharge control of the battery mounted on the vehicle without waste.

[0012] 1 is a schematic diagram showing an example of the configuration of an electric vehicle according to an embodiment; FIG. 2 is a functional block diagram of the electric vehicle according to an embodiment; FIG. 3 is a functional block diagram of a battery control device and its peripheral devices mounted on the electric vehicle according to an embodiment; FIG. 4 is a schematic diagram showing an example of a continuous gradient section according to an embodiment; FIG. 5 is a schematic diagram showing forces acting on a vehicle traveling downhill; and FIG. 6 is a flowchart showing a battery control method according to an embodiment; FIG. 6 is a schematic diagram of a current map reflecting a predicted regeneration value received by a battery in a downhill section among continuous gradient sections; FIG. 7 is a schematic diagram of a current map further reflecting a discharge current value discharged from a battery in a non-descent section among continuous gradient sections; FIG. 8 is a schematic diagram showing a first relationship between a battery's temperature change and its upper limit temperature in a continuous gradient section taking into account a predicted regeneration value and a discharge current amount (a case in which the upper limit temperature is reached midway); FIG. 9 is a schematic diagram of a current map when a discharge current value in a non-descent section is adjusted downward; and FIG. 10 is a schematic diagram predicting a relationship between a battery's temperature change and its upper limit temperature in a continuous gradient section after adjusting a discharge current value downward. and FIG. 11 is a schematic diagram showing a second relationship between a battery's temperature change and its upper limit temperature in a continuous gradient section taking into account a predicted regeneration value and a discharge current amount (a case in which the upper limit temperature is not reached). 1 is a schematic diagram of a current map when adjusting a discharge current value upward in a non-descent section. FIG. 2 is a schematic diagram predicting the relationship between the upper limit temperature and the temperature change of the battery in a continuous gradient section after adjusting the discharge current value upward. FIG. 3 is a schematic diagram showing the force applied to a vehicle traveling in an uphill section among continuous gradient sections. FIG. 4 is a schematic diagram of a current map when adjusting a regenerative current amount (charging) downward in a downhill section. FIG. 5 is a schematic diagram showing another example of a continuous gradient section in an embodiment. FIG. 6 is a schematic diagram of a current map when adjusting a discharge current value upward in a non-descent section.

[0013] Next, preferred embodiments of the present disclosure will be described. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted. Furthermore, configurations other than those described in detail below may be implemented by appropriately supplementing elemental technologies and configurations related to publicly known electric vehicles, including those described in the above-mentioned patent documents.

[0014] 1 and 2 are schematic diagrams each showing a configuration example of an electric vehicle 100 according to this embodiment. Suitable electric vehicles 100 for this embodiment include various known electric vehicles driven by an electric motor, such as electric vehicles, hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), which can be equipped with a battery 1 (described later). Suitable battery 1 for this embodiment includes various known secondary batteries, such as a lithium-ion secondary battery and a nickel-metal hydride battery.

[0015] 1, the electric vehicle 100 is configured to be able to supply power from a battery 1 to an electric motor 50 via a known converter 20 under the control of a battery control device 10 described below. The converter 20 of this embodiment may be configured to include a known AC / DC converter or DC / AC converter that appropriately converts direct current to alternating current, as well as a known DC / DC converter that adjusts the voltage value of the direct current to a desired voltage value.

[0016] As shown in FIG. 2 , the electric vehicle 100 is configured as a four-wheel drive vehicle in which, for example, an electric motor 50 generates drive torque for the vehicle and transmits the output drive torque to a left front wheel 3LF, a right front wheel 3RF, a left rear wheel 3LR, and a right rear wheel 3RR (hereinafter, collectively referred to as "drive wheels 3" unless a distinction is required). There are no particular limitations on the electric motor 50 suitable for this embodiment, and known electric motors such as those exemplified in the patent documents mentioned above can be used. The electric motor 50 can output drive torque that is transmitted to a front drive shaft 2F and a rear drive shaft 2R via a known transmission 51 and a front wheel differential mechanism 5F and a rear wheel differential mechanism 5R, respectively.

[0017] In this embodiment, an example is shown in which a single electric motor 50 distributes drive torque to each wheel, but one electric motor 50 may be disposed on the front wheel side and one on the rear wheel side, or one electric motor 50 may be disposed on each drive wheel 3. Furthermore, while the electric vehicle 100 of this embodiment is configured as a four-wheel drive vehicle as described above, it may also be a two-wheel drive vehicle in which the electric motor described above drives either the front wheels or the rear wheels.

[0018] The electric motor 50 is electrically connected to the battery 1 via the converter 20. The battery control device 10 can execute control such that the electric power (discharge current) required to drive the electric motor 50 is supplied from the battery 1 via the converter 20, and the electric power (regenerative current) generated by the electric motor 50 during regeneration is charged to the battery 1 via the converter 20. In other words, the battery 1 of this embodiment can generate heat while the electric vehicle 100 is running by supplying the discharge current to the electric motor 50 and receiving the regenerative current from the electric motor 50 via the converter 20.

[0019] The electric vehicle 100 of this embodiment is also configured to include, as equipment used to control vehicle operation, known electric steering device 8 and brake devices 4LF, 4RF, 4LR, and 4RR (hereinafter, collectively referred to as "brake device 4" unless a distinction is required). In this embodiment, the front-wheel drive shaft 2F is provided with the electric steering device 8. The electric steering device 8 includes known motors and gears (not shown) for driving the electric steering, and is controlled by a vehicle control ECU 30 to adjust the steering angles of the left front wheel 3LF and the right front wheel 3RF. One or more vehicle control ECUs 30 may be installed in the vehicle and may be known electronic control devices (ECUs) that respectively control the driving of the electric motor 50, electric steering device 8, steering wheel 9, and brake device 4.

[0020] The battery control device 10 may be configured as another one of the above-mentioned electronic control devices (ECUs), and may be configured to include one or more processors (CPUs (Central Processing Units)) and one or more memories communicatively connected to the one or more processors. The battery control device 10 may also be configured to be connectable to a known external network NT, such as the Internet, via various known communication devices CD, such as a smartphone-mediated communication form or an in-vehicle communication device. Such a battery control device 10 is electrically connected to the above-mentioned communication device CD, sensors SR, a storage device MD, such as a known hard disk or SSD, and an alarm device PD, including a known speaker SP and display DP, directly or via in-vehicle communication means, such as a CAN (Controller Area Network) or LIN (Local Internet).

[0021] Among these, the sensors SR are the well-known voltage sensors SR capable of detecting the voltage value of the battery 1. １ , a known current sensor SR capable of detecting the current value of the battery 1 described above ２ , and a known cell temperature sensor SR capable of detecting the temperature of the battery 1 while the vehicle is running. ３ The sensors SR of this embodiment may further include known in-vehicle sensors such as a vehicle speed sensor, an image sensor, or a gyro sensor in addition to the above-mentioned sensors.

[0022] <Configuration of Battery Control Device 10> Figure 3 shows an example configuration of the battery control device 10 and peripheral devices in this embodiment. As described above, the battery 1 mounted on the electric vehicle 100 may generate heat due to charging and discharging while traveling. The operating temperature range of such a battery 1 is specified so as to ensure the designed performance. Meanwhile, the road on which the electric vehicle 100 travels may include uphill roads (uphill sections) and downhill roads (downhill sections) with a predetermined gradient. Therefore, for example, when the electric vehicle 100 travels on a section that includes both uphill sections and downhill sections, it is desirable to control the charging and discharging of the battery so as to achieve the necessary acceleration on uphill roads and efficiently obtain regenerative current on downhill sections.

[0023] Against the background described above, the battery control device 10 of this embodiment is configured to have the function of controlling the charging and discharging of the battery in sections that include uphill and downhill sections, so as to prevent the temperature of the battery 1 from reaching an upper limit while recovering maximum regenerative power when traveling on downhill sections.

[0024] In this embodiment, the above-described section along which the electric vehicle 100 including the battery control device 10 travels will be described as a "continuous gradient section GCS." The continuous gradient section GCS is defined as a section that includes at least one uphill section including an uphill road and at least one downhill section including a downhill road. Note that the above-described continuous gradient section GCS may further include a flat road section in addition to the uphill section and the downhill section.

[0025] An example of such a continuous gradient section GCS is shown in FIG. 4. The continuous gradient section GCS shown in FIG. ０ From base point L １ Uphill section X is an uphill road ０ , base point L １ From base point L ２ The flat road section up to X １ , and base point L １ From base point L ２ Downhill section X is a downhill section up to ２ It is a road that includes.

[0026] In this embodiment, an "uphill section" refers to, for example, a road having a gradient angle from the horizontal plane that is equal to or greater than a predetermined reference angle θth,up and that is approximately several tens of meters to several kilometers long. In other words, the above-mentioned "uphill section" refers to a section having an inclination angle such that the deceleration when the accelerator is released in that section exceeds a predetermined value that is determined in advance through experiments, etc. In addition, in this embodiment, a "downhill section" refers to, for example, a road having a gradient angle from the horizontal plane that is equal to or greater than a predetermined reference angle θth,down and that is approximately several tens of meters to several kilometers long. In other words, the above-mentioned "downhill section" refers to a section having an inclination angle such that the vehicle accelerates along the inclined direction even when the accelerator is not depressed.

[0027] The predetermined reference angles θth,up and θth,down may be set to different values ​​or the same value. In this embodiment, a "flat road section" refers to a road other than the uphill and downhill sections described above, where the gradient angle from the horizontal plane is less than θth,up in the uphill direction and less than θth,down in the downhill direction. Such gradient angles may be detected using a known inclination sensor, such as that described in Japanese Patent Application Laid-Open No. 2002-96721. The predetermined reference angles θth,up and θth,down and the section length may be determined appropriately through experiments or simulations. The gradient (uphill or downhill) determination method and criteria are not limited to those described above, and any known method may be used as appropriate. Hereinafter, the uphill and flat road sections within the gradient continuous section GCS are collectively referred to as "non-downhill sections."

[0028] The battery control device 10 includes a processor and a memory capable of storing programs executed by the processor. The processor is configured to execute operations including a regeneration prediction value calculation process for calculating a regeneration prediction value of the amount of regenerative current to the battery 1 in a downhill section belonging to the continuous gradient section GCS, a discharge current amount provisional determination process for provisionally determining an initial current value as the amount of discharge current from the battery 1 in a non-descent section belonging to the continuous gradient section GCS, and a limit current value determination process for determining a limit value of the amount of discharge current in a non-descent section by adjusting the initial current value based on a temperature rise value of the battery 1 in the continuous gradient section GCS taking into account the calculated regeneration prediction value and the discharge current amount. The detailed configuration of the battery control device 10 will be described below.

[0029] <Functional blocks of battery control device 10> As shown in FIG. 3, the battery control device 10 of this embodiment is configured to include a voltage measurement unit 11, a current measurement unit 12, a regenerative current amount calculation unit 13, a battery temperature estimation unit 14, a limit current value determination unit 15, a regenerative current amount adjustment unit 16, and a notification control unit 17.

[0030] (Voltage measurement unit 11) The voltage measurement unit 11 includes the voltage sensor SR １ The voltage measurement unit 11 is configured to have a function of measuring the voltage value of the battery 1 via the voltage measurement unit 11. For example, the voltage measurement unit 11 can measure the voltage value of the battery 1 at a predetermined timing in order to drive the electric motor 50 while the electric vehicle 100 is traveling.

[0031] (Current measurement unit 12) The current measurement unit 12 includes the current sensor SR ２ The current measurement unit 12 is configured to have a function of measuring the current value of the battery 1 via the current measurement unit 12. The current measurement unit 12 can measure the current value flowing through the battery 1 at a predetermined timing, for example, while the electric vehicle 100 is running.

[0032] (Regenerative current amount calculation unit 13) The regenerative current amount calculation unit 13 is configured to have a function of calculating a regenerative prediction value of the amount of regenerative current to the battery 1 in a downhill section belonging to the continuous gradient section GCS along which the electric vehicle 100 is scheduled to travel. Note that the continuous gradient section GCS along which the electric vehicle 100 is scheduled to travel may be extracted from within the route if a route has been set by an on-board navigation device, for example, or may be appropriately extracted from within a route with a substantially uniform road length, such as on a highway, if no travel route has been set.

[0033] Here, Fig. 5 shows a schematic diagram of the forces that the electric vehicle 100 receives when traveling downhill at a constant speed. In the following, for the sake of simplicity, an example in which the electric vehicle 100 travels downhill at a constant speed will be described, but other known calculation formulas or conversion formulas may be used to describe an example in which the electric vehicle 100 travels downhill at a non-constant speed. As shown in Fig. 5, when the vehicle 100 travels downhill (for example, downhill section X ２ Various forces act on the electric vehicle 100 traveling on a road such as rolling resistance Froll that the vehicle's tires receive from the road surface, air resistance Faero that the vehicle receives, and gravity Fgrav that the vehicle receives.

[0034] Therefore, the braking force Fbrake on the tires of the electric vehicle 100 required to travel downhill at a constant speed can be calculated from the following equation (1): Fbrake = |Fgrav| - |Froll| - |Faero| (1) However, in the above equation (1), it is assumed that the acceleration force due to gravity is greater than the various running resistance forces, as shown below: |Fgrav| > |Froll| + |Faero|

[0035] Then, based on the tire radius and gear ratio, which are known for the electric vehicle 100, the braking torque Tbrake required for the electric motor 50 of the electric vehicle 100 can be calculated using the following equation (2): Tbrake = Fbrake × tire radius / gear ratio (2)

[0036] Assuming that the braking torque Tbrake calculated in this manner is supplied by the electric motor 50, the current flowing to the battery 1 due to the regenerative operation via the electric motor 50 can be calculated by back-calculation using a known circuit model and battery model. Note that in addition to the above-described method, the regenerative current amount calculation unit 13 may also calculate the above-described regenerative predicted value in the downhill section belonging to the continuous gradient section GCS using a known method exemplified, for example, by Japanese Patent Application Laid-Open No. 2020-141439 or Japanese Patent Application Laid-Open No. 2021-078217.

[0037] (Battery Temperature Estimation Unit 14) The battery temperature estimation unit 14 is configured to have a function of calculating the temperature and change of the battery 1 in the gradient continuous section GCS along which the electric vehicle 100 is scheduled to travel. As an example, the battery temperature estimation unit 14 can calculate the change of the temperature Tcell of the battery 1 using the following method based on the current value (initial current value Inow and revised current value Irev) determined by the limit current value determination unit 15 described later.

[0038] That is, the battery temperature estimation unit 14 calculates the temperature change of the battery 1 when discharging the battery 1 based on the initial current value Inow in the non-downhill section of the continuous gradient section GCS, for example, using the following equation (3): Ccell × (dTcell / dt) = Qs + Qj - Qrad (3)

[0039] In this case, Qs, Qj, and Qrad can be calculated by the following equations (4) to (6), respectively: Qs = Tcell × ΔS × (I / F) (4) Qj = R × I ２ ...(5) Qrad = hcell × Acell × (Tcell-Tamb) ...(6)

[0040] In the above equations, "Ccell" represents the specific heat of the battery 1, "Qs" represents the heat generated and absorbed during the battery's chemical reaction (charging and discharging), "Qj" represents the heat generated by Joule heat during the conduction of current through the battery 1, "Qrad" represents the heat dissipated into the surroundings of the battery 1, "ΔS" represents the entropy change, "F" represents the Faraday constant, "I" represents the current value flowing through the battery 1, "R" represents the internal resistance of the battery 1, "hcell" represents the thermal conductivity coefficient, "Acell" represents the surface area of ​​the battery 1, and "Tamb" represents the ambient temperature of the battery 1. These constant values ​​relating to the physical properties of the battery 1 can be determined in advance through experiments or simulations. Variables such as the ambient temperature of the battery can also be acquired using various known sensors installed in the vehicle. In addition to the above-described methods, the battery temperature estimation unit 14 may also calculate the change in the temperature Tcell of the battery 1 using other known methods, such as those described in Japanese Patent Application Laid-Open No. 2006-139963 and Japanese Patent Application Laid-Open No. 2022-171118.

[0041] (Limit Current Value Determination Unit 15) The limit current value determination unit 15 is configured to have a function of temporarily determining, as an initial current value I now, the amount of discharge current (current value) discharged from the battery 1 in a non-descent section belonging to the continuous gradient section GCS. Note that the initial current value I now used by the limit current value determination unit 15 may be the current value flowing from the battery 1 before entering the continuous gradient section GCS, or a predetermined constant current value such as 200 A or 300 A.

[0042] In addition, the limit current value determination unit 15 is configured to have the function of determining the limit current value of the discharge current amount in the non-downhill section using a predetermined calculation formula that adjusts the above-mentioned initial current value Inow based on the regeneration prediction value calculated by the regeneration current amount calculation unit 13 and the temperature rise value of the battery 1 in the gradient continuous section GCS taking into account the discharge current amount estimated by the battery temperature estimation unit 14.

[0043] In this case, the limit current value determination unit 15 may determine the limit value of the discharge current amount in the non-downstream section by adding or subtracting a predetermined current value (ΔI described later) from the initial current value I now, as described later. Alternatively, the limit current value determination unit 15 may determine the limit value of the discharge current amount in the non-downstream section by multiplying the initial current value I now by a predetermined coefficient α, as described later.

[0044] (Regenerative current amount adjustment unit 16) When there is a section in the continuous gradient section GCS where the predicted traveling speed in the non-downhill section is less than the minimum speed specified by law, the regenerative current amount adjustment unit 16 is configured to have the function of working together with the limited current value determination unit 15 to relax the limit value of the discharge current amount in the non-downhill section and to execute control to suppress the regenerative current amount in the downhill section of this continuous gradient section GCS.

[0045] (Notification control unit 17) The notification control unit 17 executes a process of notifying various information, such as the charge / discharge state of the battery 1 in the continuous gradient section GCS, via the notification device PD including the speaker SP and display DP described above. The notification control unit 17 may present the various information to the occupant via the notification device PD mounted in the vehicle, or may control the notification by accessing an external terminal such as a smartphone carried by the occupant.

[0046] <Battery Control Method> Next, a battery control method that can be executed by the battery control device 10 in this embodiment will be described with reference to Figures 6 to 16. As described above, the battery control method in this example can also be realized in the form of a program, and the program can be stored in a known recording medium.

[0047] The following describes the charge / discharge control of the battery 1 when the electric vehicle 100 equipped with the above-described battery control device 10 passes through a continuous gradient section GCS that includes at least one uphill section and at least one downhill section, as shown in FIG. 4 .

[0048] That is, the electric vehicle 100 is driven from the base point L０ From base point L １ Uphill section X ０ After passing through the base point L １ From base point L ２ Flat road section X １ Then, run to the base point L ２ From base point L ３ Downward section X ２ At this time, the battery control device 10 may, for example, determine whether the vehicle is to travel in the gradient continuous section GCS (for example, before entering the gradient continuous section GCS) (for example, from the base point L ０ At the target location (several tens of meters to several kilometers before the target location), the processing included in the battery control method described below can be executed.

[0049] As shown in Fig. 6, in step 10, the battery control device 10 determines whether or not there is a continuous gradient section GCS ahead of the traveling electric vehicle 100. As an example, in a case where the traveling route of the electric vehicle 100 is set by a navigation device as described above, it may be determined whether or not there is a continuous gradient section GCS ahead of the electric vehicle 100 on this traveling route. Note that if it is determined in step 10 that there is no continuous gradient section GCS ahead of the electric vehicle 100 (No in step 10), the process proceeds to step 24, and if the system of the electric vehicle 100 is not turned off (No in step 24), the process returns to step 10 and is repeated.

[0050] If it is determined in step 10 that there is a continuous gradient section GCS ahead of the electric vehicle 100 (Yes in step 10), the process proceeds to step 11. Then, as described above, the regenerative current amount calculation unit 13 of the battery control device 10 calculates the downhill section X belonging to the continuous gradient section GCS. ２ At this time, the regenerative current amount calculation unit 13 calculates a regenerative predicted value of the amount of regenerative current to the battery 1 in the down section X as shown in FIG. ２ The predicted regeneration value (the value of the charging current flowing to the battery 1) is calculated to be 300 A (amperes).

[0051] Step 11: Downstream section X ２After calculating the regeneration prediction value at step 12, the limit current value determination unit 15 of the battery control device 10 determines the limit current value at step 12 for the non-downward section (in this example, the uphill section X) belonging to the gradient continuous section GCS. ０ and flat road section X １ ) is provisionally determined as an initial current value I now.

[0052] More specifically, the limiting current value determining unit 15 determines, for example, the limiting current value at a point before the vehicle enters the gradient continuous section GCS (i.e., the base point L ０ The current value flowing from the battery 1 in the continuous gradient section GCS (e.g., several tens of meters to 1 km before the start of the continuous gradient section GCS) is provisionally determined as the initial current value I now. For example, if a current of 200 A flows through the battery 1 at the time before the vehicle enters the continuous gradient section GCS, the limited current value determination unit 15 provisionally determines the initial current value I now as 200 A. As a result, as shown in FIG. 8, the current value flowing from the battery 1 in the continuous gradient section GCS (e.g., several tens of meters to 1 km before the start of the continuous gradient section GCS) is provisionally determined as 200 A. ０ and flat road section X １ The amount of discharge current discharged from the battery 1 at this time is provisionally determined to be 200 A. Note that, in addition to the above, the initial current value I now in this embodiment may also be a preset value calculated in advance by experiment or simulation, for example.

[0053] In the next step 13, the battery temperature estimation unit 14 of the battery control device 10 estimates the temperature change of the battery in the continuous gradient section GCS based on the discharge current amount in the continuous gradient section GCS and the predicted regeneration value calculated by the above-mentioned method up to step 12. In the next step 14, the battery control device 10 determines whether the temperature of the battery 1 in the continuous gradient section GCS reaches a predetermined upper limit temperature Tmax. Note that the specific value of the upper limit temperature Tmax may be determined in advance by experiment, simulation, or the like depending on the type and specifications of the battery 1 used.

[0054] <Case in which the Limited Current Value is Adjusted Downward> If it is determined in step 14 that the battery 1 will reach the upper limit temperature Tmax in the gradient continuous section GCS (for example, the case shown in FIG. 9 ), the process proceeds to step 15A, where the limited current value in the non-downward section is adjusted (restriction is strengthened) as shown below. That is, the limited current value determination unit 15 first applies the above-mentioned initial current value Inow as a reference value Ibase to the following predetermined calculation formula (7), and calculates the revised current value Irev by subtracting a predetermined amount of current value ΔI from this reference value Ibase. Irev = Ibase - ΔI (7)

[0055] 10, the limit current value determination unit 15 adjusts the discharge current amount to 180 A, which is the reference value Ibase obtained by dividing the initial current value Inow of 200 A by 20 A corresponding to ΔI. Note that the specific value of ΔI may be a predetermined fixed value such as 20 A or 15 A, or may be a variable that changes as step 15A is repeated.

[0056] After adjusting the discharge current amount in step 15A, the process returns to step 14, where the battery control device 10 again determines whether the temperature of the battery 1 reaches the upper limit temperature Tmax in the gradient continuous section GCS based on the downwardly adjusted discharge current amount. More specifically, the battery temperature estimator 14 again estimates the temperature change of the battery 1 using the discharge current value adjusted downward to 180 A.

[0057] Then, in step 14, the battery control device 10 again determines whether the battery 1 will reach the upper limit temperature Tmax at this adjusted discharge current amount (180 A). At this time, as shown by the dashed line in Figure 11, the upper limit temperature Tmax will be reached even with the discharge current amount adjusted to 180 A, so the battery control device 10 again repeats the above-mentioned processing in step 15A.

[0058] That is, the limit current value determiner 15 readjusts the discharge current amount to 160 A, which is obtained by dividing 20 A corresponding to ΔI by 180 A, the discharge current amount adjusted as the reference value Ibase, as shown by the two-dot chain line in Fig. 10. After readjusting the discharge current amount in step 15A, the process returns to step 14, where the battery control device 10 determines whether the temperature of the battery 1 will reach the upper limit temperature Tmax in the continuous gradient section GCS based on the discharge current amount (160 A in this example) that has been adjusted downward. At this time, as shown by the two-dot chain line in Fig. 11, the discharge current amount adjusted to 160 A does not reach the upper limit temperature Tmax in the continuous gradient section GCS, so the limit current value determiner 15 determines this 160 A as the limit value of the discharge current amount.

[0059] In the next step 15B, the battery control device 10 determines whether the determined limit value of the discharge current amount has been adjusted. As described above, in the example shown in Fig. 9, the discharge current amount is adjusted in steps 14 and 15A, so the battery control device 10 determines in step 15B that the limit current value has been adjusted (Yes) and proceeds to step 18.

[0060] <Case in which the Limit Current Value is Adjusted Upward> Returning now to step 14, a process will be described for a case in which it is determined that the upper limit temperature Tmax of the battery 1 will not be reached when the initial current value I now (200 A in this example) is applied to the predetermined calculation formula (7) as the reference value I base. As shown in Fig. 12 , if the temperature change of the battery 1 calculated by the above calculation formula (3) using the initial current value I now (200 A in this example) does not reach the upper limit temperature Tmax (No in step 14), the limit current value is not adjusted in the subsequent step 15B (No in step 15B), and therefore the battery control device 10 performs an adjustment process (relaxation of the limit) to relax the above-mentioned limit current value as much as possible.

[0061] That is, the battery control device 10 executes a process of adjusting upward the limit current value in the non-downstream section in the subsequent step 16. More specifically, as shown in Fig. 12, the limit current value determination unit 15 first applies the above-described initial current value Inow as a reference value Ibase to the following predetermined calculation formula (8), thereby calculating the revised current value Irev by adding a predetermined amount of current value ΔI to this reference value Ibase: Irev = Ibase + ΔI (8)

[0062] 13, the limit current value determination unit 15 adjusts the discharge current amount to 220 A, which is the reference value Ibase obtained by adding 20 A corresponding to ΔI to the initial current value Inow of 200 A. Note that the specific value of ΔI may be a predetermined fixed value such as 20 A or 15 A, or may be a variable that changes as step 15A is repeated.

[0063] After adjusting the discharge current amount in step 16, the process proceeds to step 17, where the battery control device 10 determines whether the temperature of the battery 1 reaches the upper limit temperature Tmax in the gradient continuous section GCS based on the upwardly adjusted discharge current amount. More specifically, the battery temperature estimation unit 14 estimates the temperature change of the battery 1 using the discharge current value upwardly adjusted to 220 A.

[0064] Then, in step 17, the battery control device 10 determines whether the battery 1 will reach the upper limit temperature Tmax at this adjusted discharge current amount (220 A). At this time, as shown by the dashed dotted line in Fig. 14, the upper limit temperature Tmax will not be reached even with the discharge current amount adjusted to 220 A (No in step 17), so the battery control device 10 returns to step 16 and repeats the above-mentioned processing.

[0065] That is, the limit current value determiner 15 readjusts the discharge current amount to 240 A by adding 20 A, corresponding to ΔI, from 220 A, which is the discharge current amount adjusted as the reference value Ibase, as shown by the two-dot chain line in Figure 13. After readjusting the discharge current amount in step 16, the process returns to step 17, where the battery control device 10 determines whether the temperature of the battery 1 will reach the upper limit temperature Tmax in the continuous gradient section GCS based on the discharge current amount adjusted upward again (240 A in this example). At this time, as shown by the two-dot chain line in Figure 14, the discharge current amount adjusted to 240 A will reach the upper limit temperature Tmax in the continuous gradient section GCS (Yes in step 17). Therefore, the limit current value determiner 15 proceeds to step 18 and determines the previous adjustment value (220 A in this example) as the limit value of the discharge current amount.

[0066] As described above, the battery control device 10 of this embodiment can adjust the limit value of the discharge current either upward or downward depending on whether the temperature of the battery 1 reaches the upper limit temperature Tmax in the continuous gradient section GCS. In other words, the battery control device 10 can: (a) subtract a predetermined current value from the initial current value I now to determine the limit value of the discharge current in the non-descent section within the range of the upper limit temperature Tmax when the temperature of the battery 1 exceeds a predetermined upper limit temperature Tmax in the continuous gradient section GCS; and (b) add a predetermined current value to the initial current value I now to increase the limit value in the non-descent section within the range of the upper limit temperature Tmax when the temperature of the battery 1 does not exceed the upper limit temperature Tmax in the continuous gradient section GCS.

[0067] <Case of Traveling Below the Lower Limit Speed> In the following step 19, the battery control device 10 determines whether the electric vehicle 100 is traveling below the lower limit speed in the uphill section X of the continuous gradient section GCS based on the limit value of the discharge current determined in the above step. ０ Calculate the vehicle speed when traveling.

[0068] The forces that are applied to the electric vehicle 100 traveling at a constant speed on an uphill road are shown schematically in Figure 15. Note that, for simplicity of explanation, an example in which the electric vehicle 100 travels on an uphill road at a constant speed will be described below, but an example in which the electric vehicle 100 travels on an uphill road at a non-constant speed using other known calculation formulas or conversion formulas may also be applied.

[0069] As shown in FIG. 15, the uphill section X ０ Various forces act on the electric vehicle 100 traveling uphill, such as rolling resistance Froll that the vehicle's tires receive from the road surface, air resistance Faero that the vehicle receives, and gravity Fgrav that the vehicle receives. Therefore, the driving force Ftract of the electric vehicle 100 required to travel at a constant speed on this uphill road can be calculated using the following equation (9): Ftract = |Fgrav| + |Froll| + |Faero| ... (9)

[0070] Therefore, the limit value of the discharge current (I lim The traveling speed v(t) of the electric vehicle 100 when traveling at a constant speed can be calculated from the relationship between power, speed, and force using the following equation (10): v = (η / Fract) × V × I lim　 ...(10)

[0071] In the above formula (10), it is assumed that energy loss occurs only during power conversion in the power unit, and that there is no loss in the motor rotating shaft, etc. In the above formula (10), "η" represents the power conversion efficiency in the power unit, and "V" represents the battery voltage. The value of "η" can be determined in advance by experiment or simulation. The voltage "V" of the battery 1 may be calculated from the state of charge (SOC) at the time of implementing this method using a known battery model. In addition to the above method, the battery control device 10 may also apply other known calculation formulas to calculate the limit value (I) of the discharge current determined before step 18. lim ) may be calculated.

[0072] After calculating the vehicle speed in the uphill section in step 19, the battery control device 10 determines whether the calculated vehicle speed is lower than the minimum traveling speed in that section in the following step 20. The minimum traveling speed in the uphill section can be obtained, for example, from map information in a known navigation device installed in the vehicle or from an external server.

[0073] If the vehicle speed calculated in step 19 is not less than the lower limit traveling speed for that section (No in step 20), the battery control device 10 proceeds to step 23B, where it executes charge / discharge control of the battery 1 in the continuous gradient section GCS based on the limit value of the discharge current and the predicted regeneration value calculated above. If the electric vehicle 100 has finished traveling in the continuous gradient section GCS in step 23B, it proceeds to step 24, and if the system is not turned off (No in step 24), the battery control device 10 returns to step 10 and repeats the above processing.

[0074] On the other hand, if the vehicle speed in the uphill section is less than the minimum traveling speed limit in step 20 (Yes in step 20), the battery control device 10 proceeds to step 21, where it substitutes the minimum traveling speed limit for "v" in the above-mentioned equation (10) to back-calculate the limit current value at that time.The battery control device 10 (battery temperature estimator 14) then re-estimates the temperature change of the battery 1 from the above-mentioned equation (3) based on this back-calculated limit current value.In this way, the battery control device 10 estimates the change in battery temperature when the vehicle speed in the uphill section is increased to the minimum traveling speed limit.

[0075] Next, in step 22, the battery control device 10 determines whether the battery 1 will reach the upper limit temperature Tmax based on the temperature change estimated in step 21. If the battery 1 has not reached the upper limit temperature Tmax in step 22 (No in step 22), the battery control device 10 proceeds to step 23B and executes the above-described processing.

[0076] On the other hand, if the battery 1 reaches the upper limit temperature Tmax in step 22 (Yes in step 22), the battery control device 10 proceeds to step 23A and executes the following process for adjusting the amount of regenerative current.

[0077] More specifically, as shown in FIG. 16, the battery control device 10 controls the vehicle speed in the downhill section X of the continuous gradient section GCS. ２ The battery control device 10 then executes a process to weaken the regeneration rate (specifically, a process to adjust the regeneration prediction value downward) at step 23A. As an example, the battery control device 10 executes a process to reduce the regeneration prediction value (300 A in this example) by a predetermined ampere (5 to 20 A). After step 23A, the battery control device 10 proceeds to step 21 to re-estimate the temperature change of the battery 1, and then re-determines in step 22 whether the battery 1 has reached the upper limit temperature Tmax in the same manner as above.

[0078] If the result of the re-determination in step 22 indicates that the battery 1 still reaches the upper limit temperature Tmax (Yes in step 22), the battery control device 10 determines in step 23A that the battery 1 has reached the upper limit temperature Tmax in the downhill section X of the continuous gradient section GCS. ２ On the other hand, if the result of the re-determination in step 22 is that the battery 1 has not reached the upper limit temperature Tmax (No in step 22), the battery control device 10 proceeds to step 23B and executes the above-described process.

[0079] In this way, the battery control device 10 estimates the change in battery temperature when the vehicle speed on the uphill section is increased to the lower limit speed, and when the battery 1 reaches the upper limit temperature Tmax, the battery control device 10 stops the downhill section X. ２ By performing the relaxation process of adjusting downward the predicted regeneration value at , it is possible to finally adopt a regeneration ratio within a range in which the battery 1 does not reach the upper limit temperature Tmax.

[0080] The battery control device 10 and battery control method of the present embodiment described above enable efficient charge / discharge control of the onboard battery 1 without waste when the electric vehicle 100 travels on a continuous gradient section GCS that includes at least one uphill section and at least one downhill section. In other words, in the past, when the battery temperature reached an upper operating limit on a downhill section of a continuous gradient road, the power supply (charging) process to the battery had to be interrupted, which forced the use of regenerative braking to be limited. In contrast, the method disclosed herein achieves optimal battery energy management by controlling the battery output, including the uphill section, as described above, without wasting energy that would have been recovered in the past as heat (hydraulic braking).

[0081] <Program> As described above, the battery control method can be implemented as a computer-readable battery control program. The battery control device 10 may be configured to read this battery control program. That is, the battery control program disclosed in the above-described embodiment is a computer program that causes a computer to execute the following operations: calculate a regeneration prediction value of the amount of regenerative current to a battery installed in a vehicle in a downhill section belonging to a continuous gradient section that includes at least one uphill section and at least one downhill section; temporarily determine, as an initial current value, the amount of discharge current from the battery in a non-descent section other than the downhill section belonging to the continuous gradient section, based on the current value flowing from the battery before entering the continuous gradient section; and determine a limit value for the amount of discharge current in the non-descent section by adjusting the initial current value based on the temperature rise of the battery in the continuous gradient section taking into account the calculated regeneration prediction value and the amount of discharge current. The battery control program may be downloaded to the electric vehicle 100 from a known server such as a cloud server.

[0082] <Recording Medium> As described above, a recording medium suitable for this embodiment is a non-transitory tangible recording medium having recorded thereon a battery control program for controlling charging and discharging of a battery mounted on a vehicle in a continuous gradient section that includes at least one uphill section and at least one downhill section. The battery control program includes instructions that cause a processor to execute the following operations: calculate a predicted regenerative value of the amount of regenerative current to a battery mounted on the vehicle in a downhill section that belongs to the continuous gradient section that includes at least one uphill section and at least one downhill section; provisionally determine, as an initial current value, the amount of discharge current from the battery in a non-descent section other than the downhill section that belongs to the continuous gradient section, the current value flowing from the battery before entering the continuous gradient section; and determine a limit value for the amount of discharge current in the non-descent section by adjusting the initial current value based on a temperature rise value of the battery in the continuous gradient section that takes into account the calculated predicted regenerative value and the amount of discharge current.

[0083] The recording medium for recording a computer program may be a magnetic medium such as a hard disk, a floppy disk, or a magnetic tape; an optical recording medium such as a CD-ROM (Compact Disk Read Only Memory), a DVD (Digital Versatile Disk), or a Blu-ray (registered trademark); a magneto-optical medium such as a floptical disk; a memory element such as a RAM or a ROM; a flash memory such as a USB (Universal Serial Bus) memory; an SSD (Solid State Drive); or any other medium capable of storing a program.

[0084] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art of the present disclosure may attempt further modifications to the embodiments within the scope of the technical ideas set forth in the claims, and it is understood that these modifications also fall within the technical scope of the present disclosure.

[0085] <Modifications> Preferred modifications of the battery control device and battery control method of the present disclosure are described below. [Other Continuous Gradient Sections] In the above-described embodiment, a continuous gradient section GCS (see FIG. 4) including one uphill section, one flat road section, and one downhill section was exemplified. However, the present disclosure is not limited to this embodiment, and a continuous gradient section GCS including multiple uphill sections and multiple downhill sections, as exemplified in FIG. 17, may also be applied. Furthermore, the flat road section is not essential in the continuous gradient section GCS of the present disclosure, and may be omitted.

[0086] That is, the continuous gradient section GCS shown in FIG. 17 is an uphill section X ０ , X ４ and X ６ and a downhill section X ２ , X ５ and X ７ and a flat road section X １ and X ３ Even when traveling on such a continuous gradient section GCS, the battery control device 10 can adjust the limit value of the discharge current in the uphill section and the predicted regeneration value in the downhill section in the same manner as in the above-described embodiment.

[0087] 18, when the continuous gradient section GCS includes multiple uphill sections, the battery control device 10 may adjust the limit value of the discharge current in each of these uphill sections so that the limit values ​​are different from each other. Similarly, when the continuous gradient section GCS includes multiple downhill sections, the battery control device 10 may adjust the predicted regeneration value in each of these downhill sections so that the predicted regeneration value is different from each other.

[0088] [Use of Following Vehicle Information] The battery control device 10 may acquire following vehicle information about a following vehicle traveling behind the electric vehicle 100 (host vehicle) equipped with the battery control device 10. As an example, the battery control device 10 may acquire the following vehicle information by capturing an image of the following vehicle using a known on-board camera, or may acquire the following vehicle information from the following vehicle via known vehicle-to-vehicle communication.

[0089] When there are more than a predetermined number of following vehicles traveling behind the host vehicle, the battery control device 10 may perform control (the above-described upward adjustment) to relax the limit value of the discharge current set in the non-downhill section of the continuous gradient section GCS while preventing the battery 1 from reaching the upper limit temperature Tmax. The number of following vehicles in this case can be set in advance through experiments or simulations depending on the driving performance of the host vehicle, etc. This makes it possible to perform efficient charge / discharge control of the battery 1 without waste, while taking into consideration the following vehicles traveling behind the host vehicle.

[0090] [Use of Traffic Information] The battery control device 10 may also acquire traffic information (e.g., information indicating congestion conditions such as traffic congestion forecasts) when the electric vehicle 100 (host vehicle) equipped with the battery control device 10 passes through the continuous gradient section GCS. As an example, the battery control device 10 may acquire the traffic information via an on-board communication device CD.

[0091] If the battery control device 10 predicts, based on the traffic information described above, that more than a predetermined number of vehicles will be present in the continuous gradient section GCS while the vehicle is traveling, it may execute control to strengthen the discharge current limit value set in the non-downhill section of the continuous gradient section GCS (the downward adjustment described above). The number of vehicles present in this case can be set in advance through experiments or simulations depending on the driving performance of the vehicle, etc. This enables more efficient and efficient charge / discharge control of the battery 1 while also reflecting actual traffic conditions.

[0092] 100 Electric vehicle 1 Battery 10 Battery control device 20 Converter 30 Vehicle control ECU 50 Electric motor

Claims

1. A battery control device that performs charge and discharge control of a battery mounted on a vehicle in a gradient continuous section that includes at least one ascending section and at least one descending section, the battery control device comprising: a processor; and a memory capable of storing a program executed by the processor, wherein the processor performs: a regeneration prediction value calculation process for calculating a predicted regeneration current value of the regeneration current amount to the battery in the descending section belonging to the gradient continuous section; a discharge current amount provisional determination process for provisionally determining the discharge current amount from the battery in a non-descending section other than the descending section belonging to the gradient continuous section, using the current value flowing from the battery before entering the gradient continuous section as an initial current value; and a limiting current value determination process for adjusting the initial current value based on the temperature rise value of the battery in the gradient continuous section taking into account the calculated regeneration prediction value and the discharge current amount, and determining a limiting value of the discharge current amount in the non-descending section.

2. The battery control device according to claim 1, wherein the processor determines a limiting value of the discharge current amount in the non-descending section by adding or subtracting a predetermined amount of current value to / from the initial current value.

3. The battery control device according to claim 1, wherein the processor determines a limiting value of the discharge current amount in the non-descending section by multiplying the initial current value by a predetermined coefficient α.

4. The battery control device according to claim 2 or 3, wherein the processor: (a) when the temperature of the battery exceeds a pre-specified upper limit temperature in the gradient continuous section, subtracts a predetermined amount of current value from the initial current value to determine the limiting value in the non-descending section within the range of the upper limit temperature; and (b) when the temperature of the battery does not exceed the upper limit temperature in the gradient continuous section, adds a predetermined amount of current value to the initial current value to increase the limiting value in the non-descending section within the range of the upper limit temperature.

5. The battery control device according to claim 4, wherein the processor acquires information on a following vehicle traveling behind the own vehicle on which the battery control device is mounted, and when there are more than a predetermined number of following vehicles traveling behind the own vehicle, executes control to relax the limiting value of the discharge current amount set in the non-descending section.

6. The processor acquires traffic information when the host vehicle equipped with the battery control device passes through the continuous gradient section, and when it is predicted based on the traffic information that there are more than a predetermined number of vehicles in the continuous gradient section when the host vehicle is traveling, executes control to strengthen the limit value in the non-downhill section set in the non-downhill section. The battery control device according to claim 4.

7. The processor calculates an expected traveling speed of the vehicle in the non-downhill section based on the limit value in the non-downhill section, and when there is a section where the expected traveling speed is less than the minimum speed defined by law, relaxes the limit value in the non-downhill section and suppresses the amount of regenerative current in the downhill section. The battery control device according to claim 4.

8. A recording medium recording a computer program for causing a computer to calculate a predicted regeneration value of the amount of regenerative current to a battery mounted on a vehicle in a downhill section belonging to a continuous gradient section including at least one uphill section and one downhill section, respectively, provisionally determine the discharge current amount from the battery in a non-downhill section other than the downhill section belonging to the continuous gradient section, with the current value flowing from the battery before entering the continuous gradient section as an initial current value, and based on the temperature rise value of the battery in the continuous gradient section taking into account the calculated predicted regeneration value and the discharge current amount, adjust the initial current value to determine the limit value of the discharge current amount in the non-downhill section.

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