Controller and control method

Abstract

To provide a controller and a control method that increase an amount of regeneration with increase in the temperature of a battery suppressed.SOLUTION: A controller 20 controls a vehicle Ve including: a motor generator (first motor generator 2) which brakes a drive wheel 5 and regenerates electric power; and a battery 4 to which regenerative electric power generated through regeneration is supplied. The controller comprises: a calculation unit 24 which calculates a current value at which an endothermic amount Qs of the battery 4 is equal to a heating value Qr or more during regeneration based on a resistance value R of the battery 4 and a reaction heat S per unit current value caused by electrochemical reaction of the battery 4; and a control unit 26 which controls the motor generator based on the calculated current value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device and a control method. [Background technology]

[0002] In recent years, efforts to realize a low-carbon or carbon-free society have become more active, and research and development into electrification technologies is being conducted in vehicles to reduce CO2 emissions and improve energy efficiency.

[0003] For example, Patent Document 1 listed below describes a regenerative control device that is configured to calculate the regenerative current to be flowed to the battery from a map based on the battery voltage when the battery temperature is below a threshold, and to calculate the regenerative current to be flowed to the battery from a map based on the battery's charging rate when the battery temperature is above the threshold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5724704 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the prior art, there is room for improvement in terms of increasing the amount of regeneration while suppressing the rise in battery temperature.

[0006] The present invention provides a control device and a control method that can increase the amount of regeneration while suppressing an increase in the temperature of a battery. [Means for solving the problem]

[0007] One aspect of the present invention is A control device for controlling a vehicle including a motor generator that brakes drive wheels to perform regeneration, and a battery to which the regenerated electric power is supplied, a calculation unit that calculates a current value at which the amount of heat absorbed by the battery during regeneration is equal to or greater than the amount of heat generated by the battery, based on a resistance value of the battery and heat of reaction per unit current value due to an electrochemical reaction of the battery; and a control unit that controls the motor generator based on the calculated current value.

[0008] Another aspect of the present invention is A computer that controls a vehicle equipped with a motor generator that brakes drive wheels to perform regeneration and a battery that receives the regenerated electric power, calculating a current value at which the amount of heat absorbed by the battery during regeneration is equal to or greater than the amount of heat generated by the battery, based on a resistance value of the battery and the heat of reaction per unit current value due to an electrochemical reaction of the battery; A process is executed to control the motor generator based on the calculated current value. [Effects of the Invention]

[0009] According to the present invention, it is possible to increase the amount of regeneration while suppressing an increase in the temperature of the battery, which in turn contributes to improving energy efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing the configuration of a vehicle Ve equipped with a control device 20 according to the present embodiment. [Figure 2] FIG. 10 is a diagram illustrating an example of heat generation characteristics during regeneration. [Figure 3] FIG. 2 is a block diagram showing an example of a control device 20. [Figure 4] FIG. 4 is a diagram showing an example of a map for deriving a resistance value R. [Figure 5] FIG. 2 is a diagram showing an example of a map for deriving the heat of reaction S per unit time. [Figure 6] FIG. 4 is a diagram showing an example of a map for setting a temperature rise suppression coefficient K. [Figure 7] 4 is a flowchart showing an example of processing executed by a control device 20 of the present embodiment. [Figure 8] 5A and 5B are diagrams illustrating an example of changes in battery temperature during discharging and regeneration in the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment will be described below with reference to the drawings. The following embodiment does not limit the present invention, and not all of the elements described in the following embodiment are necessarily essential to the present invention. Furthermore, two or more elements described in the following embodiment may be arbitrarily combined without departing from the spirit of the present invention. Note that, below, identical or similar elements are denoted by the same or similar reference numerals, and their description may be omitted or simplified.

[0012] The control device 20 in this embodiment is mounted on a vehicle Ve, and performs control related to regeneration of a motor having a power generating function.

[0013] [vehicle] First, a vehicle Ve equipped with the control device 20 will be described. The vehicle Ve may be, for example, a vehicle equipped with a motor having a power generation function. Therefore, the vehicle Ve may be, for example, a hybrid vehicle equipped with an engine and a motor as a drive source, or an electric vehicle equipped with only a motor as a drive source. In this embodiment, as shown in FIG. 1, a hybrid vehicle will be described as an example. The vehicle Ve includes an engine (ENG) 1, which is an example of an internal combustion engine; a first motor generator (MG1) 2, which is an example of an electric motor; a second motor generator (MG) 3, which is an example of a generator; a battery 4, which is an example of an electricity storage device; a clutch CL; a power conversion device 11; a braking device 12; various sensors 13; and a control device 20 that controls the vehicle. In FIG. 1, thick solid lines indicate mechanical connections, double dotted lines indicate electrical wiring, and thin solid arrows indicate transmission and reception of control signals or detection signals.

[0014] The engine 1 is, for example, a gasoline engine or a diesel engine, and outputs power generated by burning supplied fuel. The engine 1 is connected to a second motor generator 3 and is also connected to drive wheels 5 of the vehicle Ve via a clutch CL. The power output by the engine 1 is transmitted to the second motor generator 3 when the clutch CL is in a disengaged state, and is transmitted to the second motor generator 3 and drive wheels 5 when the clutch CL is in an engaged state (engaged state).

[0015] The first motor generator 2 is a motor generator (a so-called traction motor) used primarily as a drive source for the vehicle Ve, and is configured, for example, as an AC motor. The first motor generator 2 is electrically connected to the battery 4 and the second motor generator 3 via a power conversion device 11. The first motor generator 2 can be supplied with power from at least one of the battery 4 and the second motor generator 3. When supplied with power, the first motor generator 2 operates as an electric motor and outputs power for propelling the vehicle Ve. The first motor generator 2 is also connected to drive wheels 5, and the power output by the first motor generator 2 is transmitted to the drive wheels 5. The vehicle Ve propels by transmitting at least one of the output of the engine 1 and the output of the first motor generator 2 to the drive wheels 5.

[0016] Furthermore, the first motor generator 2 operates as a generator to generate electricity (so-called regenerative power generation) when braking the vehicle Ve (when rotated by the engine 1 or drive wheels 5). The electric power generated by the regenerative operation of the first motor generator 2 (hereinafter also referred to as "regenerative power") is supplied to the battery 4 via the power conversion device 11, for example. This allows the battery 4 to be charged with the regenerative power.

[0017] Furthermore, the regenerated power may not be supplied to the battery 4, but may be supplied to the second motor generator 3 via the power conversion device 11. By supplying the regenerated power to the second motor generator 3, it is possible to "discard" the regenerated power, consuming it without charging the battery 4. When disposing of the regenerated power, the regenerated power supplied to the second motor generator 3 is used to drive the second motor generator 3, and the power generated thereby is input to the engine 1 and consumed by mechanical friction loss of the engine 1, etc.

[0018] The second motor generator 3 is a motor generator used mainly as a power generator, and is configured, for example, by an AC motor. The second motor generator 3 is driven by the power of the engine 1 to generate electricity. The electric power generated by the second motor generator 3 is supplied to at least one of the battery 4 and the first motor generator 2 via the power conversion device 11. By supplying the electric power generated by the second motor generator 3 to the battery 4, the battery 4 can be charged with the electric power. Furthermore, by supplying the electric power generated by the second motor generator 3 to the first motor generator 2, the first motor generator 2 can be driven with the electric power.

[0019] The power conversion device 11 is a device that converts input power and outputs the converted power (also referred to as a "power control unit (PCU)"), and is connected to the first motor generator 2, the second motor generator 3, and the battery 4. For example, the power conversion device 11 is configured to include a first inverter 111, a second inverter 112, and a voltage control device 110. The first inverter 111, the second inverter 112, and the voltage control device 110 are electrically connected to each other.

[0020] The voltage control device 110 converts an input voltage and outputs the converted voltage. A DC / DC converter or the like can be used as the voltage control device 110. For example, when supplying power from the battery 4 to the first motor generator 2, the voltage control device 110 boosts the output voltage of the battery 4 and outputs it to the first inverter 111. Furthermore, for example, when regenerative power generation is performed by the first motor generator 2, the voltage control device 110 reduces the output voltage of the first motor generator 2 received via the first inverter 111 and outputs it to the battery 4. Furthermore, when power generation is performed by the second motor generator 3, the voltage control device 110 reduces the output voltage of the second motor generator 3 received via the second inverter 112 and outputs it to the battery 4.

[0021] When supplying power from the battery 4 to the first motor generator 2, the first inverter 111 converts the power (DC) of the battery 4 received via the voltage control device 110 into AC and outputs the AC to the first motor generator 2. When regenerative power is generated by the first motor generator 2, the first inverter 111 converts the power (AC) received from the first motor generator 2 into DC and outputs the DC to the voltage control device 110. When discarding the regenerative power of the first motor generator 2, the first inverter 111 converts the power (AC) received from the first motor generator 2 into DC and outputs the DC to the second inverter 112.

[0022] When power is generated by the second motor generator 3, the second inverter 112 converts the power (AC) received from the second motor generator 3 into DC and outputs the DC to the voltage control device 110. When the regenerative power of the first motor generator 2 is discarded, the second inverter 112 converts the regenerative power (DC) of the first motor generator 2 received via the first inverter 111 into AC and outputs the AC to the second motor generator 3.

[0023] The battery 4 is a chargeable and dischargeable secondary battery, and has a plurality of storage cells connected in series or series-parallel. The battery 4 is configured to be able to output a high voltage of, for example, 100 to 400 V. The storage cells of the battery 4 may be lithium-ion batteries or nickel-metal hydride batteries. The upper temperature limit of the battery 4 may be set to, for example, about 40°C, taking into consideration the durability of the battery 4.

[0024] The clutch CL can be in a connected state in which it connects (i.e., engages) the power transmission path from the engine 1 to the drive wheels 5, and a disconnected state in which it disconnects (i.e., cuts off) the power transmission path from the engine 1 to the drive wheels 5. The output of the engine 1 is transmitted to the drive wheels 5 when the clutch CL is in the connected state, and is not transmitted to the drive wheels 5 when the clutch CL is in the disconnected state.

[0025] The brake device 12 is an example of a "brake device" according to the present invention, and is used in a brake-by-wire system that applies brakes to a vehicle Ve. The brake-by-wire system is a system in which the brake device 12 applies brakes to the vehicle Ve under the control of a control device 20. A brake pedal (not shown) is not mechanically connected to the components of the brake device 12, and the brake device 12 is controlled based on an output signal from a brake position sensor, which is one of various sensors 13, to brake the vehicle Ve. The brake device 12 is configured, for example, as an electric servo brake device (ESB) including a brake caliper, a cylinder that transmits hydraulic pressure to the brake caliper, and an electric motor that generates hydraulic pressure in the cylinder (all of which are not shown). The electric servo brake applies brakes to the vehicle Ve using hydraulic pressure controlled in response to the operation of the brake pedal by the driver. The electric servo brake device controls the electric motor in response to the input amount of brake pedal operation, and outputs braking torque to each wheel in response to the braking operation.

[0026] The brake device 12 is not limited to an electric servo brake device, but may also be an electronically controlled hydraulic brake device. An electronically controlled hydraulic brake device controls an actuator in accordance with the input amount of brake pedal operation to transmit hydraulic pressure from a master cylinder to the cylinder. In addition, in this embodiment, as described above, regenerative braking force can be generated by the first motor generator 2, and therefore the control device 20 generates a desired braking force by controlling the regenerative braking force and the mechanical braking force of the brake device 12 in coordination with respect to the required braking force based on the operation of the brake pedal.

[0027] The various sensors 13 include, for example, a vehicle speed sensor that detects the traveling speed (vehicle speed) of the vehicle Ve, an accelerator position sensor that detects the amount of operation of an accelerator pedal of the vehicle Ve, a brake position sensor that detects the amount of operation of a brake pedal of the vehicle Ve, and a battery sensor that detects various information related to the battery 4 (for example, the voltage value of the battery 4, the current value during charging / discharging and regeneration, the temperature of the battery, etc.) The detection results by the various sensors 13 are transmitted to the control device 20 as detection signals.

[0028] The control device 20 is a computer that controls the entire vehicle Ve, and includes, for example, a processor that performs various calculations, a storage unit having a non-transitory storage medium that stores various information (for example, maps and programs described below), and an input / output unit that controls input and output of data between the inside and outside of the control device 20 (all of which are not shown). For example, the control device 20 is realized by one ECU (Electronic Control Unit) or by multiple ECUs working together.

[0029] Specifically, the control device 20 is provided so as to be able to communicate with the engine 1, the clutch CL, the power conversion device 11, the braking device 12, and various sensors 13. The control device 20 controls the output of the engine 1 and the power conversion device 11, thereby controlling the outputs of the first motor generator 2 and the second motor generator 3. The control device 20 also controls the first motor generator 2 and the braking device 12, thereby controlling the braking force of the vehicle Ve.

[0030] The control device 20 can control the driving mode of the vehicle Ve by controlling the output of the engine 1, the outputs of the motor generators 2 and 3, and the clutch CL. Possible driving modes of the vehicle Ve include, for example, an "engine driving mode" in which the vehicle Ve is driven mainly by the power output by the engine 1, a "hybrid driving mode" in which electric power generated by at least the second motor generator 3 is supplied to the first motor generator 2 and the vehicle Ve is driven mainly by the power output by the first motor generator 2 in response to that electric power, and an "EV driving mode" in which only electric power from the battery 4 is supplied to the first motor generator 2 and the vehicle Ve is driven by the power output by the first motor generator 2 using that electric power.

[0031] The control device 20 executes various programs stored in, for example, a memory unit. In a conventionally known battery regeneration control (for example, Patent Document 1, cited above), when the battery temperature (hereinafter also referred to as "battery temperature") rises to a predetermined temperature, the regenerative current is reduced to suppress the rise in battery temperature. On the other hand, the chemical reaction (electrochemical reaction) that occurs when a regenerative current (or charging current) flows to the battery does not necessarily increase the battery temperature. Specifically, a lithium-ion battery used in the battery generates reaction heat due to an electrochemical reaction during charging and discharging. Generally, the reaction heat generates heat during discharging and absorbs heat during charging. Focusing on the endothermic reaction during charging, the amount of heat Q generated by the entire battery during charging of the battery 4 can be expressed by the following equation (1), which is the amount of heat absorbed by the endothermic reaction Qs and the amount of heat generated when a charging current is passed through the battery 4 (i.e., Joule heat, a loss due to current flow) Qr.

[0032] Q=Qs+Qr...Equation (1)

[0033] Here, if heat generation that causes an increase in battery temperature is "positive" and heat absorption that causes a decrease in battery temperature is "negative," then when the value of equation (1) is "positive," the battery as a whole is in a heat generation state, and when the value of equation (1) is "negative," the battery as a whole is in an endothermic state. Note that when the amount of heat absorption Qs and the amount of heat generation Qr are the same value, and the value of equation (1) is "0," the battery temperature is in an equilibrium state where it does not rise.

[0034] Fig. 2 is a diagram showing an example of heat generation characteristics during charging, with the horizontal axis representing the SOC (State of Charge), which indicates the remaining charge (charging rate) of the battery, and the vertical axis representing ΔT, which indicates the temperature change of the battery 4. The example shown in Fig. 2 shows cases where charging is performed at three charging rates (i.e., charging currents) (solid line, dashed line, and dashed dotted line). In each case, the temperature of the battery 4 drops to ΔT1, ΔT2, and ΔT3, respectively, as the SOC increases from a low state to "α." In other words, it can be seen that the battery temperature can drop when regeneratively generated power is charged to the battery 4.

[0035] 2 shows an example of an event that occurs when the battery 4 is being charged, but it is assumed that such an event will also occur during regeneration. In this embodiment, it is assumed that all regenerated power is stored in the battery 4. Therefore, in the following explanation, unless otherwise specified, the current during regeneration (regenerative current) and the current during charging (charging current) will be described as being the same.

[0036] In this embodiment, regeneration control is performed by focusing on the fact that the battery temperature does not rise or drops during such regeneration.

[0037] Specifically, the control device 20 executes a regeneration control processing program, as an example of a program stored in the storage unit, for calculating a current value at which the amount of heat absorption Qs of the battery during regeneration is equal to or greater than the amount of heat generation Qr, and performing regeneration control. As shown in Fig. 3, the control device 20 includes, as functional units realized by executing the program, a resistance value derivation unit 21, a reaction heat derivation unit 22, a temperature rise suppression coefficient setting unit 23, a calculation unit 24, a regeneration permission value calculation unit 25, and a control unit 26. Note that, hereinafter, the processes described as being performed by the resistance value derivation unit 21, the reaction heat derivation unit 22, the temperature rise suppression coefficient setting unit 23, the calculation unit 24, the regeneration permission value calculation unit 25, and the control unit 26 are processes realized by the control device 20.

[0038] The resistance value derivation unit 21 derives the resistance value R of the battery 4. Here, the resistance value R is an estimated value of the internal resistance of the battery 4. Specifically, the resistance value derivation unit 21 acquires the current remaining charge (hereinafter also referred to as "SOC") of the battery 4 based on a detection value of a battery sensor, which is one of the various sensors 13. Then, the resistance value derivation unit 21 derives the resistance value R of the battery 4 based on the current SOC of the battery 4 by referring to a map that associates the acquired current SOC of the battery 4 with the resistance value R at that SOC.

[0039] FIG. 4 is an example of a map for deriving the resistance value R of the battery 4 during regeneration (charging), with the SOC plotted on the horizontal axis and the resistance value R plotted on the vertical axis. The resistance value deriving unit 21 references the map of FIG. 4 and derives the resistance value R as "R1 [Ω]" when the SOC is "β [%]," for example. From the map of FIG. 4, it can be seen that in a relatively low SOC range between "γ [%] (where γ<β)" and "β [%]," the resistance value R is "R1 [Ω]" or less, which is lower than when the SOC is relatively high, at or above "β [Ω]." The map shown in FIG. 4 indicates the resistance value R (e.g., average value) when the temperature of the battery 4 is within a predetermined temperature range (e.g., 20 to 35°C).

[0040] On the other hand, the resistance value derivation unit 21 may derive the resistance value R of the battery 4 based on each battery temperature. The resistance value R of the battery 4 may change depending on the battery temperature. Therefore, the resistance value derivation unit 21 may predetermine a map such as that shown in FIG. 4 for each battery temperature (for example, at intervals of 5°C, such as 5°C, 10°C, 15 ...

[0041] The reaction heat derivation unit 22 derives the reaction heat S per unit current value (hereinafter also referred to as "reaction heat S per unit time") due to the electrochemical reaction of the battery 4. Specifically, the reaction heat derivation unit 22 acquires the current SOC of the battery 4 based on the detection value of a battery sensor, which is one of the various sensors 13, and derives the reaction heat S per unit current value based on the acquired SOC. In this embodiment, the reaction heat derivation unit 22 derives the resistance value R of the battery 4 based on the current SOC of the battery 4 by referring to a map that associates the acquired current SOC of the battery 4 with the reaction heat S per unit current value at that SOC.

[0042] FIG. 5 shows an example of a map for deriving the reaction heat S per unit current value during regeneration (charging), with the SOC on the horizontal axis and the reaction heat S per unit current value on the vertical axis. The reaction heat derivation unit 22 references the map in FIG. 5 and derives the reaction heat S per unit current value as "S1 [W / A]" when the SOC is "δ [%]." On the other hand, the reaction heat derivation unit 22 derives the reaction heat S per unit current value as "S2 [W / A]" when the SOC is "ε [%] (where ε > δ). As can be seen from FIG. 5, the reaction heat S per unit time decreases as the SOC increases. For example, the reaction heat S decreases significantly in the SOC range from "δ [%]" to "ε [%]" compared to other regions. In the region from "δ [%]" to "ε [%]", the reaction heat S per unit time decreases significantly, but the decrease is not localized and it decreases gradually. Also, the map shown in Fig. 5 shows the reaction heat S per unit time (for example, average value) when the temperature of the battery 4 is in a predetermined temperature range (for example, 20 to 35 [°C]).

[0043] On the other hand, the reaction heat derivation unit 22 may derive the reaction heat S per unit time based on the battery temperature. The reaction heat S per unit time may vary depending on the battery temperature. Therefore, the reaction heat derivation unit 22 may determine in advance a map such as that shown in FIG. 5 for each battery temperature (for example, at 5°C intervals such as 5°C, 10°C, 15 ...

[0044] The temperature rise suppression coefficient setting unit 23 sets a temperature rise suppression coefficient K that corrects, in accordance with the battery temperature, the current value at which the amount of heat absorption Qs calculated by the calculation unit 24 described later becomes equal to or greater than the amount of heat generation Qr. When the current battery temperature is equal to or greater than a predetermined temperature (e.g., 35°C) that is close to the upper limit temperature (e.g., 40°C), it is preferable to limit the current value so that the battery temperature does not rise above the predetermined temperature. Therefore, the temperature rise suppression coefficient setting unit 23 sets the temperature rise suppression coefficient K, which is a predetermined correction coefficient according to the battery temperature.

[0045] FIG. 6 is an example of a map in which the temperature rise suppression coefficient K is associated with the battery temperature, with the horizontal axis representing the battery temperature and the vertical axis representing the temperature rise suppression coefficient K. The temperature rise suppression coefficient setting unit 23 sets the temperature rise suppression coefficient K by, for example, referring to the map of FIG. 6. As can be seen from FIG. 6, when the battery temperature is below a predetermined temperature, the temperature rise suppression coefficient K is set to "1," and when the battery temperature is equal to or higher than the predetermined temperature, the temperature rise suppression coefficient K is set to "K1," which is smaller than 1.

[0046] The calculation unit 24 calculates a current value at which the amount of heat absorption Qs of the battery 4 during regeneration is equal to or greater than the amount of heat generation Qr. That is, the calculation unit 24 calculates a current value at which the amount of heat absorption is equal to or greater than the amount of heat generation Qr, thereby preventing the battery temperature from rising or decreasing. Specifically, the calculation unit 24 calculates a current value at which the amount of heat absorption Qs of the battery 4 during regeneration is equal to or greater than the amount of heat generation Qr, based on the resistance value R of the battery 4 derived by the function of the resistance value derivation unit 21 and the reaction heat S per unit time of the battery 4 derived by the function of the reaction heat derivation unit 22. As described above, the total amount of heat generation Q of the battery 4 during regeneration satisfies the relationship (Q = Qr + Qs) shown in equation (1) based on the relationship between the amount of heat generation Qr and the amount of heat absorption Qs when current is applied. If it is estimated that the battery temperature will not rise when the amount of heat absorption Qs is equal to or greater than the amount of heat generation Qr and power application to the battery 4 is permitted, the inequality shown in equation (2) below is established.

[0047] Qr≦Qs...Equation (2)

[0048] The amount of heat generated Qr can be expressed by the following formula (3) using the resistance value R of the battery 4, the heat of reaction S per unit time, and the current value I. Similarly, the amount of heat absorbed Qs can be expressed by the following formula (4).

[0049] Qr=R×I 2 ...Equation (3) Qs=S×I...Equation (4)

[0050] Then, by substituting equations (3) and (4) into equation (2) and rearranging to calculate the current value "I" at which the amount of heat absorbed Qs of battery 4 during regeneration is equal to or greater than the amount of heat generated Qr, the relationship shown in equation (5) below is established.

[0051] I≦S / R...Equation (5)

[0052] In other words, when equation (5) is satisfied, the battery as a whole absorbs heat, and the battery temperature does not increase or decreases. In this way, the calculation unit 24 calculates the current value at which the amount of heat absorbed Qs of the battery 4 during regeneration is equal to or greater than the amount of heat generated Qr.

[0053] Furthermore, when the current battery temperature is equal to or higher than a predetermined temperature near the upper limit temperature, the calculation unit 24 multiplies the current value at which the amount of heat absorption of the battery 4 during regeneration is equal to or higher than the amount of heat generation by the temperature rise suppression coefficient K. That is, the calculation unit 24 multiplies the current value calculated by the above-mentioned equation (5) by the temperature rise suppression coefficient K set by the above-mentioned temperature rise suppression coefficient setting unit 23.

[0054] The regeneration permission value calculation unit 25 calculates the current value that permits regeneration by the first motor generator 2 according to the current state of the battery 4. The power that can be stored in the battery 4 may vary depending on the SOC state and battery temperature state. Therefore, the regeneration permission value calculation unit 25 acquires the battery temperature and SOC based on the detection value of the battery sensor. For example, if the SOC of the battery 4 is low (e.g., less than 80%) and the temperature is ideal (e.g., 15°C to 35°C) taking into account the durability and output of the battery 4, there is almost no restriction on the storage of power in the battery 4. Therefore, in this case, no regeneration restriction is imposed. On the other hand, if the SOC is 80% or higher and the battery is close to full charge, the battery capacity is low compared to full charge, so the amount of regeneration is limited. In other words, regeneration restriction is imposed. Similarly, if the battery temperature is low, e.g., 5°C, the resistance value of the battery 4 increases, so regeneration restriction is imposed. In this way, regeneration restriction may be imposed depending on the state of the battery 4. The current value that allows regeneration obtained in this manner may differ from the current value calculated by the above-described calculation unit 24. That is, the above-described calculation unit 24 calculates the current value that can be regenerated in view of heat generation and absorption during regeneration, whereas the regeneration permission value calculation unit 25 calculates the current value that can be regenerated in view of the SOC and battery temperature.

[0055] The control unit 26 controls the first motor generator 2 based on the calculated current value for regeneration. Specifically, the control unit 26 has a regeneration permission value determination unit 26a that determines the current value for regeneration. The regeneration permission value determination unit 26a determines the smaller (minimum value) of the current value at which the amount of heat absorption Qs calculated by the function of the calculation unit 24 described above is equal to or greater than the amount of heat generation Qr, and the current value calculated by the regeneration permission value calculation unit 25, as the current value that can actually be regenerated.

[0056] Furthermore, the control unit 26 calculates a regenerative braking force from the regenerative current value determined by the regeneration permission value determination unit 26a, and distributes the regenerative braking force and the mechanical braking force of the brake device 12 so that the required braking force is output by the regenerative braking force and the mechanical braking force of the brake device 12. In other words, the control unit 26 brakes the vehicle Ve by causing the brake device 12 to output the remaining regenerative braking force from the first motor generator 2 relative to the required braking force. The control unit 26 then controls the current value due to regeneration in the first motor generator 2 to generate a regenerative braking force based on the result of the distribution, and controls the hydraulic pressure of the brake device 12 and the like to generate a mechanical braking force based on the result of the distribution.

[0057] [Processing performed by the control device] Next, an example of the regeneration control process executed by the control device 20 will be described with reference to a flowchart. Fig. 7 is a flowchart showing an example of the process, which is executed, for example, while the vehicle Ve is traveling (particularly when the driver requests braking of the vehicle Ve).

[0058] First, the control device 20 acquires the battery temperature (step Sp1). That is, the control device 20 acquires the battery temperature detected by the battery sensor, which is one of the various sensors 13.

[0059] Next, the control device 20 acquires the current SOC of the battery 4 (step Sp2). Specifically, the control device 20 estimates the SOC of the battery 4 based on the voltage of the battery 4 detected by, for example, a battery sensor, thereby acquiring the SOC of the battery.

[0060] Next, the control device 20 acquires the required braking force (step Sp3). Specifically, the control device 20 acquires the required braking force based on, for example, the detection value of the brake position sensor and the vehicle speed V. Note that the processing from step Sp1 to step Sp3 described above may be performed in any order.

[0061] Next, the control device 20 acquires the resistance value R of the battery 4 (step Sp4). That is, the control device 20 uses the function of the resistance value derivation unit 21 to derive the resistance value R of the battery 4 based on the current SOC of the battery by referring to a map that associates the SOC of the battery 4 with the resistance value R at that SOC, as described above with reference to FIG.

[0062] Next, the control device 20 acquires the reaction heat S per unit time of the battery 4 (step Sp5). That is, the control device 20, using the function of the reaction heat derivation unit 22, derives the resistance value R of the battery 4 based on the current SOC of the battery 4 by referring to a map that associates the current SOC of the battery 4 with the reaction heat S per unit current value at that SOC, as described above with reference to FIG.

[0063] Next, the control device 20 calculates a regeneration permission value for the battery 4 (step Sp6). That is, the control device 20 uses the function of the regeneration permission value calculation unit 25 to calculate a current value that permits regeneration by the first motor generator 2 from the current SOC and battery temperature of the battery 4.

[0064] Next, the control device 20 acquires a temperature rise suppression coefficient, which is a correction coefficient for suppressing a rise in the temperature of the battery 4 (step Sp7). That is, the control device 20, using the function of the temperature rise suppression coefficient setting unit 23, refers to a map in which the battery temperature and the temperature rise suppression coefficient K are associated, for example, as described with reference to FIG. 6, and acquires the temperature rise suppression coefficient K corresponding to the current battery temperature. Note that the order of the processes from step Sp4 to step Sp7 described above may be random. Furthermore, as described above, the temperature rise suppression coefficient K is a value that can be set to a value smaller than the default value "1" when the battery temperature is equal to or higher than a predetermined temperature. Therefore, for example, if the battery temperature acquired in step Sp1 is lower than the predetermined temperature, step Sp7 may be skipped.

[0065] Next, the control device 20 calculates the current value at which the amount of heat absorption Qs of the battery 4 during regeneration is equal to or greater than the amount of heat generation Qr (step Sp8). That is, the control device 20 uses the function of the calculation unit 24 to calculate the current value at which the amount of heat absorption Qs is equal to or greater than the amount of heat generation Qr, based on the resistance value R of the battery 4 acquired in step Sp4 and the heat of reaction S per unit time of the battery 4 acquired in step Sp5.

[0066] Next, the control device 20 multiplies the current value calculated in step Sp8 by the temperature rise suppression coefficient K (step Sp9). Note that, as described above, this step Sp9 may be skipped when the battery temperature acquired in step Sp1 is lower than the predetermined temperature because the temperature rise suppression coefficient K is "1".

[0067] Next, the control device 20 determines a regeneration permission value (step Sp10). That is, using the function of the regeneration permission value determiner 26a, the control device 20 compares a current value based on the regeneration permission value corresponding to the state of the battery 4 calculated in step Sp6 with a current value calculated in step Sp9 (or step Sp8) at which the amount of heat absorption Qs is equal to or greater than the amount of heat generation Qr, and determines the smaller current value as the regeneration permission value. That is, the control device 20 determines the current value at which the amount of heat absorption Qs is equal to or greater than the amount of heat generation Qr, within the range of the regeneration permission value calculated in step Sp6, as the regeneration permission value.

[0068] Next, the control device 20 distributes the braking force between the first motor generator 2 and the brake device 12 based on the current value of the regeneration permission value determined in step Sp10 (step Sp11). That is, the control device 20 distributes the required braking force acquired in step Sp3 into a regenerative braking force and a mechanical braking force by the brake device 12 using the function of the control unit 26 so that the required braking force can be output as a regenerative braking force and a mechanical braking force by the brake device 12. That is, the control device 20 causes the brake device 12 to apply the remaining amount of braking by regeneration by the first motor generator 2 with respect to the required braking force. Then, based on the distribution result, the control unit 26 controls the current value by regeneration in the first motor generator 2 and controls the hydraulic pressure and the like so that the brake device 12 generates a mechanical braking force. After completing the processing of step Sp11, the control device 20 ends the processing in the flowchart of FIG. 7.

[0069] As described above, in this embodiment, the current value at which the amount of heat absorbed Qs of the battery 4 during regeneration is equal to or greater than the amount of heat generated Qr is calculated based on the resistance value R of the battery 4 and the heat of reaction S per unit current value due to the electrochemical reaction of the battery 4. The first motor-generator 2 is controlled based on the calculated current value. That is, by calculating the current value at which the amount of heat absorbed Qs is equal to or greater than the amount of heat generated Qr, it is possible to calculate a current value within a range in which the current flowing during regeneration does not result in a temperature rise in the battery 4. As a result, for example, as shown in FIG. 8 , the temperature of the battery 4 does not rise at least during the braking intervals from time t1 to time t2 and from time t3 to time t4. This allows for a greater amount of regenerated power than when regeneration is performed without taking into account the endothermic reaction that occurs during regeneration. In other words, it is possible to increase the amount of regeneration while suppressing an increase in battery temperature, which ultimately contributes to improved energy efficiency.

[0070] Increasing the amount of regeneration in this way also increases the power stored in the battery 4, making it possible to suppress a decrease in SOC and, as a result, maintain a high voltage. Furthermore, maintaining the high voltage makes it possible to reduce the current value during discharge, which in turn makes it possible to suppress heat generation in the battery 4 due to the discharge.

[0071] In this embodiment, the reaction heat S per unit current value is calculated based on the SOC of the battery 4, or based on the SOC and the battery temperature. The SOC and the battery temperature of the battery 4 can be calculated based on the detected values ​​of the battery sensor. In other words, with such a simple configuration, the reaction heat S per unit current value can be calculated, and the amount of regeneration can be increased using the reaction heat S as a parameter.

[0072] Furthermore, as shown in the map of FIG. 5 above, the reaction heat S per unit time gradually decreases from "S1" to "S2" as the SOC increases (increase between "δ [%] and ε [%]" in the example of FIG. 5). The current value during regeneration has the reaction heat S per unit time as one parameter, and therefore affects the brake feeling. That is, if the regenerative current is suddenly reduced while generating regenerative braking force, the regenerative torque decreases according to the regenerative current, resulting in so-called torque loss, which may worsen the brake feeling. However, in this embodiment, the reaction heat S per unit time gradually decreases, thereby preventing the brake feeling from being worsened by the torque loss.

[0073] Furthermore, in this embodiment, the resistance value R of the battery 4 is derived based on the SOC of the battery 4, or based on the SOC and the battery temperature, similar to the reaction heat S per unit current value. With such a simple configuration, the resistance value R of the battery 4 can be derived, and the amount of regeneration can be increased using the resistance value R as one parameter.

[0074] Furthermore, in this embodiment, when the battery temperature is equal to or higher than a predetermined temperature near the upper limit temperature, a temperature rise suppression coefficient K, which is a predetermined correction coefficient, is multiplied by the current value at which the amount of heat absorbed by the battery 4 during regeneration is equal to or greater than the amount of heat generated. This makes it possible to maximize the amount of regeneration while suppressing an increase in battery temperature, even when the battery temperature is near the upper limit temperature. Furthermore, when the battery temperature is near the upper limit temperature (e.g., 30 to 35°C), there is no regeneration restriction compared to when the battery temperature is, for example, 5°C. Therefore, maximizing the amount of regeneration in this way can further increase the amount of regeneration.

[0075] Furthermore, in this embodiment, the brake device 12 generates the remaining braking force relative to the required braking force resulting from braking by the first motor generator 2. This maximizes the amount of regeneration while allowing the brake device 12 to generate braking force that is insufficient due to the regenerative braking force, thereby suppressing deterioration of the components constituting the brake device 12, such as wear.

[0076] In this embodiment, the brake device 12 is configured as a brake-by-wire system. That is, the braking force can be electronically controlled with the brake pedal mechanically disconnected from the brake device 12. Therefore, for example, when the driver operates the brake pedal, the reaction speed for generating braking force is increased, and as a result, the braking feeling can be improved.

[0077] [Variations] Next, a modified example will be described. In the above embodiment, the control device 20 is configured to derive the resistance value R based on the map of Fig. 4 using the function of the resistance value derivation unit 21. However, instead of this, for example, the control device 20 may acquire the voltage change amount ΔV per unit time and the current change amount ΔI per unit time of the battery 4 based on the detection value of the battery sensor, and derive the resistance value R (R = ΔV / ΔI) of the battery 4 by dividing the acquired voltage change amount ΔV by the current change amount ΔI.

[0078] Furthermore, in the above-described embodiment, the temperature rise suppression coefficient K is set to "1" or "K1" depending on whether the battery temperature is equal to or higher than a predetermined temperature, as explained using FIG. 6. However, the temperature rise suppression coefficient K may be set to, for example, a value that gradually decreases as the battery temperature increases, or a value that decreases in a stepwise manner as the battery temperature increases.

[0079] [others] Although the embodiments of the present invention have been described above with reference to the drawings, it goes without saying that the present invention is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0080] The control method described in the above-described embodiment can be realized by executing a prepared control program on a computer. The control program is recorded on a computer-readable storage medium and executed by being read from the storage medium. The control program may be provided in a form stored on a non-transitory storage medium such as a flash memory, or may be provided via a network such as the Internet. The computer that executes the control program may be included in a control device, or may be included in an electronic device such as a smartphone, tablet, or personal computer that can communicate with the control device, or may be included in a server device that can communicate with these control devices and electronic devices.

[0081] This specification describes at least the following: Note that the components in parentheses correspond to those in the above-described embodiments, but are not limited to these.

[0082] (1) A control device (control device 20) for controlling a vehicle (vehicle Ve) including a motor generator (first motor generator 2) that brakes drive wheels (drive wheels 5) to perform regeneration, and a battery (battery 4) to which regenerated electric power is supplied, the control device including: a calculation unit (calculation unit 24) that calculates a current value at which the amount of heat absorbed by the battery during the regeneration is equal to or greater than the amount of heat generated, based on a resistance value (resistance value R) of the battery and a heat of reaction (heat of reaction S) per unit current value due to an electrochemical reaction of the battery; and a control unit (control unit 26) that controls the motor generator based on the calculated current value. Control device.

[0083] According to (1), the battery temperature decreases (or at least does not increase), so the amount of regenerated power can be increased compared to when power is regenerated without taking into account the endothermic reaction that occurs during regeneration. In other words, it is possible to increase the amount of regeneration while suppressing the increase in battery temperature.

[0084] (2) The control device according to (1), A reaction heat extraction section (reaction heat extraction section 22) is provided to extract the reaction heat, The reaction heat derivation unit derives the reaction heat per unit current value based on the remaining charge of the battery. Control device.

[0085] According to (2), the reaction heat per unit current value can be derived using a simple configuration based on the remaining charge of the battery, and the amount of regeneration can be increased using the reaction heat as one parameter.

[0086] (3) The control device according to (2), The reaction heat derivation unit further derives the reaction heat per unit current value based on a temperature of the battery. Control device.

[0087] According to (3), the reaction heat per unit current value can be calculated using a simple configuration based on the remaining charge of the battery and the battery temperature, and the amount of regeneration can be increased using the reaction heat as one parameter.

[0088] (4) The control device according to (1), Further provided is a resistance value derivation unit (resistance value derivation unit 21) that derives a resistance value of the battery, the resistance value deriving unit derives the resistance value of the battery based on the current remaining charge of the battery by referring to a map that associates the remaining charge of the battery with the resistance value at the corresponding remaining charge. Control device.

[0089] According to (4), the resistance value of the battery can be derived with a simple configuration based on the remaining charge of the battery, and the amount of regeneration can be increased using the resistance value as one parameter.

[0090] (5) The control device according to (4), The resistance value deriving unit further derives the resistance value of the battery based on the temperature of the battery. Control device.

[0091] According to (5), the resistance value of the battery can be derived with a simple configuration based on the remaining charge of the battery and the battery temperature, and the amount of regeneration can be increased using the resistance value as one parameter.

[0092] (6) The control device according to (1), The calculation unit When the current temperature of the battery is equal to or higher than a predetermined temperature that is close to an upper limit temperature, a predetermined correction coefficient (temperature rise suppression coefficient K) is multiplied by the current value at which the amount of heat absorbed by the battery during regeneration is equal to or higher than the amount of heat generated by the battery, the control unit controls the motor generator based on the current value multiplied by the correction coefficient. Control device.

[0093] According to (6), even if the battery temperature is near the upper limit temperature, it is possible to maximize the amount of regeneration while suppressing an increase in the battery temperature.

[0094] (7) The control device according to (1), The vehicle further includes a braking device (brake device 12) that brakes the drive wheels, The control unit The braking device is further configured to be controllable, the remaining braking force due to the regeneration of the motor generator is applied by the braking device with respect to the required braking force. Control device.

[0095] According to (7), the amount of regeneration can be maximized while the braking force that is insufficient due to the regenerative braking force can be generated by the braking device, and deterioration of components such as wear of the components that make up the braking device can be suppressed.

[0096] (8) The control device according to (7), The braking device is configured by a brake-by-wire system. Control device.

[0097] According to (8), since the braking force can be electronically controlled with the mechanical connection between the brake pedal and the braking device disconnected, for example, when the driver operates the brake pedal, the reaction speed for generating braking force becomes faster, and as a result, the braking feeling can be improved.

[0098] (9) The control device according to (1), Further provided is a resistance value derivation unit (resistance value derivation unit 21) that derives a resistance value of the battery, The resistance value derivation unit deriving a resistance value of the battery based on a voltage change amount and a current change amount of the battery; Control device.

[0099] According to (9), the resistance value of the battery can be derived with a simple configuration based on the amount of change in the voltage and current of the battery, and the amount of regeneration can be increased using the resistance value as one parameter.

[0100] (10) A computer controlling a vehicle (vehicle Ve) equipped with a motor generator (first motor generator 2) that brakes drive wheels (drive wheels 5) to perform regeneration and a battery (battery 4) to which regenerated power is supplied, calculates a current value (current value I) at which the amount of heat absorbed by the battery during regeneration is equal to or greater than the amount of heat generated, based on the resistance value (resistance value R) of the battery and the heat of reaction per unit current value (heat of reaction S) due to the electrochemical reaction of the battery, Executing a process to control the motor generator based on the calculated current value. Control method.

[0101] According to (10), the battery temperature will decrease (or at least will not increase), so the amount of regenerated power can be increased compared to when power is regenerated without taking into account the endothermic reaction that occurs during regeneration. In other words, it is possible to increase the amount of regeneration while suppressing the increase in battery temperature. [Explanation of symbols]

[0102] 2. First motor generator (MG1) 4 Battery 5 drive wheels 12 Brake device (braking device) 20 Control device 21 Resistance value derivation section 22 Reaction heat extraction section 24 Calculation section 26 Control Unit K Temperature rise suppression coefficient (correction coefficient) R resistance value S Reaction heat Vehicle

Claims

1. A control device for controlling a vehicle including a motor generator that brakes drive wheels to perform regeneration, and a battery to which the regenerated electric power is supplied, a calculation unit that calculates a current value at which the amount of heat absorbed by the battery during regeneration is equal to or greater than the amount of heat generated by the battery, based on a resistance value of the battery and heat of reaction per unit current value due to an electrochemical reaction of the battery; a control unit that controls the motor generator based on the calculated current value. Control device.

2. The control device according to claim 1, A reaction heat outlet portion for emitting the reaction heat is provided, The reaction heat derivation unit derives the reaction heat per unit current value based on the remaining charge of the battery. Control device.

3. The control device according to claim 2, The reaction heat derivation unit further derives the reaction heat per unit current value based on a temperature of the battery. Control device.

4. The control device according to claim 1, a resistance value deriving unit that derives a resistance value of the battery; the resistance value deriving unit derives the resistance value of the battery based on the current remaining charge of the battery by referring to a map that associates the remaining charge of the battery with the resistance value at the corresponding remaining charge. Control device.

5. The control device according to claim 4, The resistance value deriving unit further derives the resistance value of the battery based on the temperature of the battery. Control device.

6. The control device according to claim 1, The calculation unit When the current temperature of the battery is equal to or higher than a predetermined temperature that is close to an upper limit temperature, a predetermined correction coefficient is multiplied to the current value at which the amount of heat absorbed by the battery during regeneration is equal to or higher than the amount of heat generated by the battery; the control unit controls the motor generator based on the current value multiplied by the correction coefficient. Control device.

7. The control device according to claim 1, The vehicle further includes a braking device that brakes the drive wheels, The control unit The braking device is further configured to be controllable, the remaining braking force due to the regeneration of the motor generator is applied by the braking device with respect to the required braking force. Control device.

8. The control device according to claim 7, The braking device is configured by a brake-by-wire system. Control device.

9. The control device according to claim 1, a resistance value deriving unit that derives a resistance value of the battery; The resistance value derivation unit deriving a resistance value of the battery based on a voltage change amount and a current change amount of the battery; Control device.

10. A computer that controls a vehicle equipped with a motor generator that brakes drive wheels to perform regeneration and a battery that receives the regenerated electric power, calculating a current value at which the amount of heat absorbed by the battery during regeneration is equal to or greater than the amount of heat generated by the battery, based on a resistance value of the battery and the heat of reaction per unit current value due to an electrochemical reaction of the battery; Executing a process to control the motor generator based on the calculated current value. Control method.

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