Electric vehicle control system

Abstract

To provide a control system of a vehicle which can suppress a battery for driving from having an empty battery and charge an auxiliary battery.SOLUTION: A control system of an electric vehicle comprises: a first battery which supplies a rotation electrical machine used for a traveling vehicle with electric power; a second battery which is charged from the first battery; and a control device which controls the first battery and the second battery. The control device performs, when the first battery is a first state of charge or more, a first charge control where the second battery is charged with electric power of the first battery and the second battery is kept being a second state of charge or more, and performs, when the first battery is less than the first state of charge, a second charge control where state of charge of the first battery is kept.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a control system for an electric vehicle. [Background technology]

[0002] Automobiles such as hybrid vehicles and battery EVs are equipped with a drive battery that supplies power to the motor that drives the vehicle, and an auxiliary battery that supplies power to on-board electrical devices (see, for example, Patent Document 1). Patent Document 1 discloses a control system for an electric vehicle that charges the auxiliary battery using power from the drive battery when the voltage of the auxiliary battery drops. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-83157 Summary of the Invention [Problem to be solved by the invention]

[0004] In such an electric vehicle control system, it is preferable to charge the second battery, which mainly functions as an auxiliary battery, while preventing the first battery, which mainly functions as a drive battery, from running out of charge, in which the charge state of the first battery becomes zero. Patent Document 1 does not disclose this point.

[0005] An object of the present disclosure is to provide a vehicle control system that can charge a second battery while preventing a first battery from running out of power. [Means for solving the problem]

[0006] A control system for an electric vehicle according to the present disclosure includes a first battery that supplies power to a rotating electric machine used to run the vehicle, a second battery that receives charge from the first battery, and a control device that controls the first battery and the second battery. When the first battery is in a first state of charge or higher, the control device executes a first charge control for charging the second battery with power from the first battery and maintaining the second battery in a second state of charge or higher, and when the first battery is below the first state of charge, executes a second charge control for maintaining the state of charge of the first battery. When the second battery falls below a third state of charge which is lower than the second state of charge, a third charging control is executed to charge the second battery even if the first battery is below the first state of charge.

[0007] According to this electric vehicle control system, first charging control and second charging control are performed according to the charging states of the first battery and the second battery, so that the second battery can be charged while preventing the first battery from running out of power. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a vehicle control system that can charge a second battery while preventing a first battery from running out of power. [Brief description of the drawings]

[0009] [Figure 1] 1 is a system diagram of an electric vehicle according to an embodiment of the present disclosure. [Diagram 2] 4 is a flowchart showing a control procedure of a control device according to an embodiment of the present disclosure. [Diagram 3] FIG. 4 is a diagram showing changes in the state of charge of a driving battery and an auxiliary battery according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, the longitudinal direction of a vehicle is indicated as Q in the drawings, the front is indicated as F, the width direction of the vehicle is indicated as P in the drawings, and the right side as viewed from the rear of the vehicle is indicated as R.

[0011] 1, the control system 1 of the electric vehicle C includes an internal combustion engine (ENG) 2, a generator (GEN) 4, a front motor (FrM: an example of a rotating electric machine) 6, a drive battery (BT: an example of a first battery) 10, a transaxle 16, an inverter 18, a control device (HVECU) 20, an ignition switch (IG) 22, a DC-DC converter (DCDC) 24, electrical components 26, an auxiliary battery (an example of a second battery) 28, a charger 30, and a user terminal 32. The control system 1 for the electric vehicle of this embodiment is a control system 1 for a plug-in hybrid vehicle in which the front motor 6 drives a front-wheel drive shaft 12a of the front wheels 12 via the transaxle 16.

[0012] The inverter 18 has a generator control device (GCU) 4a that controls the generator 4, and a front motor control device (FrMCU) 6a. The front motor control device 6a receives a signal from the control device 20 and controls the regeneration and power running of the front motor 6 so that the front motor 6 is in a desired operating state.

[0013] The internal combustion engine 2 drives the generator 4 via the transaxle 16. The internal combustion engine 2 drives the generator 4 by combusting fuel supplied from a fuel tank. The transaxle 16 of this embodiment has a clutch 16a. The clutch 16a transmits and cuts off power between the internal combustion engine 2 and the front motor 6 and between the internal combustion engine 2 and the front wheel drive shaft 12a. The internal combustion engine 2 is connected to the front wheel drive shaft 12a via the clutch 16a of the transaxle 16 and drives the front wheel drive shaft 12a.

[0014] The generator 4 is connected to the internal combustion engine 2 and generates electricity by being driven by the internal combustion engine 2. The electric power generated by the generator 4 can charge the drive battery 10 and can also be supplied to each motor via an inverter 18. The generator 4 is controlled by a generator control device 4a provided in the inverter 18. The generator control device 4a is electrically connected to the control device 20, receives signals from the control device 20, and controls power generation and power running so that the generator 4 is in a desired operating state.

[0015] The drive battery 10 outputs power to each motor and the generator 4, and receives power generated by the front motor 6 and the generator 4. The drive battery 10 in this embodiment is composed of secondary batteries such as lithium-ion batteries, and has a battery module (not shown) made up of a number of battery cells. The drive battery 10 supplies power to the front motor 6 that drives the vehicle. The drive battery 10 also charges the auxiliary battery 28 via a DC-DC converter 24.

[0016] The drive battery 10 has a battery monitoring unit (BMU) 10a. The battery monitoring unit 10a calculates the state of charge (hereinafter referred to as SOC1) of the battery module as an example of the state of charge of the drive battery 10. The control device 20 may calculate the state of charge SOC1 based on the voltage Bv of the battery module. In addition, the battery monitoring unit 10a may detect the state of health (hereinafter referred to as SOH) and the battery temperature Btmp of the battery module. The battery monitoring unit 10a acquires the voltage Bv, state of charge SOC1, state of health SOH, and battery temperature Btmp of the drive battery 10 and transmits them to the control device 20. A high-voltage cable connected to the front motor 6 and the generator 4 via the inverter 18 and a high-voltage cable connected to a DC-DC converter 24 are connected to the terminal 10b of the drive battery 10.

[0017] The control device 20 controls at least the drive battery 10, the DC-DC converter 24, and the auxiliary battery 28, in addition to controlling the driving and power generation of the electric vehicle C. In this embodiment, the control device 20 controls the clutch 16a based on information such as the speed V, charging rate SOC1, and accelerator opening Th of the electric vehicle C, thereby switching the driving mode to one of the series driving mode, parallel driving mode, and EV driving mode.

[0018] The control device 20 is actually configured by a microcomputer including an arithmetic unit, a memory, an input / output buffer, etc. The control device 20 controls each device based on signals from each sensor and various devices, and maps and programs stored in the memory, so that the electric vehicle control system 1 is in a desired operating state.

[0019] The control device 20 is activated when the ignition switch 22 is turned on by the user of the electric vehicle C, and starts controlling each device. However, the control device 20 also acquires the charging rate SOC1 of the driving battery 10 from the battery monitoring unit 10a while the ignition switch 22 is off. Furthermore, the control device 20 acquires the charging rate SOC2 of the auxiliary battery 28 as an example of the charging state of the auxiliary battery 28. In this embodiment, the control device 20 acquires the voltage Sb of the auxiliary battery 28, and calculates the charging rate SOC2 of the auxiliary battery 28 based on the voltage Sb.

[0020] When the charging rate SOC2 of the auxiliary battery 28 drops, the control device 20 starts up the DC-DC converter 24 and executes a first charging control, a second charging control, and a third charging control to charge the auxiliary battery 28 from the driving battery 10 via the DC-DC converter 24.

[0021] Specifically, the control device 20 executes the first charging control when the charging rate SOC1 of the driving battery 10 is equal to or higher than a first predetermined charging rate Mb1 (an example of a first charging state). As shown by the arrows A to B and B to C in Fig. 3, the first charging control is control for charging the auxiliary battery 28 with power from the driving battery 10 to a voltage equal to or higher than the first predetermined voltage Sb1 when the voltage of the auxiliary battery 28 falls below a first predetermined voltage Sb1 (an example of a second charging state).

[0022] Furthermore, the control device 20 executes the second charging control when the charging rate SOC1 of the driving battery 10 is less than the first predetermined charging rate Mb1. As shown in D to I of Fig. 3, the second charging control is a control for maintaining the charging rate SOC1 so as to prevent the driving battery 10 from running out of power when the voltage of the auxiliary battery 28 drops below the first predetermined voltage Sb1. The second charging control includes a third charging control. As shown in F to G of Fig. 3, the third charging control is a control for charging the auxiliary battery 28 with the power of the driving battery 10 when the charging rate SOC1 of the driving battery 10 is equal to or greater than the second predetermined charging rate Mb2 (an example of a fourth charging state) and when the voltage Sb of the auxiliary battery 28 is less than the second predetermined voltage Sb2 (an example of a third charging state).

[0023] The DC-DC converter 24 is a device that reduces the direct current supplied from the generator 4 or the driving battery 10 to a voltage that can be used by the electrical components 26. The electrical components 26 are components that can be driven at a lower voltage than the front motor 6. In this embodiment, the electrical components 26 include a communication device (an example of a notification means) that turns on the ignition switch 22 of the electric vehicle C and transmits information to the user terminal 32 to prompt the start of the electric vehicle C. The user terminal 32 is a terminal such as a smartphone, tablet, or personal computer owned by the user. In addition, the electrical components 26 are devices such as audio equipment in the vehicle cabin that can be driven by a low-voltage power source (e.g., a 12V power source), and a cooling device that cools the internal combustion engine 2 and the front motor 6. The electrical components 26 may be various control devices mounted on the electric vehicle C, including the control device 20.

[0024] Some of these electrical components 26 require standby power, which is power consumed while the ignition switch 22 is off. Such standby power (or dark current) is supplied from the auxiliary battery 28. Therefore, the auxiliary battery 28 discharges the standby power even while the ignition switch 22 is off.

[0025] The auxiliary battery 28 is a device that stores the electric power converted by the DC-DC converter 24. In this embodiment, it is a battery that stores electric power of a voltage (e.g., 12 V to 14 V) that can be used by the electrical components 26. The auxiliary battery 28 is charged by the driving battery 10 via the DC-DC converter 24. The auxiliary battery 28 is provided with a voltage sensor (not shown), and the voltage is monitored by the control device 20.

[0026] The charger 30 is a device that uses an external power source to charge the drive battery 10. The charger 30 has a plug 30b to which a charging gun 30a can be connected, and charging of the drive battery 10 begins when a user of the electric vehicle C inserts the charging gun 30a into the plug 30b.

[0027] Next, the control procedure of the control device 20 of this embodiment will be described with reference to the flowchart of Fig. 2 and Fig. 3. The control device 20 starts the control procedure by activating the control device 20 at predetermined time intervals while the ignition switch 22 is off.

[0028] In step S1, the control device 20 acquires the charging rate SOC1 of the driving battery 10 and the voltage Sb of the auxiliary battery 28. After acquiring the charging rate SOC1 of the driving battery 10 and the voltage Sb of the auxiliary battery 28, the control device 20 proceeds to step S2. In step S2, the control device 20 determines whether the voltage Sb of the auxiliary battery 28 is less than a first predetermined voltage Sb1. The first predetermined voltage Sb1 may be, for example, a value (e.g., a value between 10V and 12V) that can compensate for the standby power of the electrical components 26.

[0029] If the control device 20 determines in step S2 that the voltage Sb of the auxiliary battery 28 is less than the first predetermined voltage Sb1 (YES in step S2), the process proceeds to step S3. In step S3, the control device 20 determines whether the storage rate SOC1 of the drive battery 10 is less than a first predetermined storage rate Mb1. The first predetermined storage rate Mb1 may be a storage rate SOC1 (e.g., 40%) that allows the electric vehicle C to be started and run.

[0030] If the control device 20 determines in step S3 that the charging rate SOC1 of the driving battery 10 is less than the first predetermined charging rate Mb1 (step S3 YES), the control device 20 proceeds to step S4. If the control device 20 determines in step S3 that the charging rate SOC1 of the driving battery 10 is equal to or greater than the first predetermined charging rate Mb1 (step S3 NO), the control device 20 proceeds to step S12. In step S4, the control device 20 starts the second charging control and issues a warning to the user. As shown in FIG. 3, the second charging control starts from D in FIG. 3. In step S4, the control device 20 starts the second charging control and operates the communication device to notify the user terminal 32 of information encouraging charging. The information encouraging charging includes, for example, in the case of a plug-in hybrid vehicle capable of external charging such as the electric vehicle C, turning on the ignition switch 22 to run the vehicle, inserting the charging gun 30a into the plug 30b to charge the vehicle, or starting the internal combustion engine 2 to generate electricity using the generator 4. After notifying the user terminal 32 of the information, the control device 20 advances the process to step S5.

[0031] In step S5, the control device 20 acquires information from the user terminal 32. The information from the user terminal 32 is information permitting or not permitting (denying) the information encouraging charging. When the control device 20 acquires information not permitting or determines that no information has been transmitted from the user terminal 32 for a certain period of time, the control device 20 proceeds to process step S6. When the control device 20 acquires information permitting or determines that information has been transmitted from the user terminal 32 for a certain period of time, the control device 20 proceeds to process step S12. In step S12, the first charging control is performed. As described above, the first charging control is a control for charging the auxiliary battery 28 with the power of the driving battery 10 until the voltage of the auxiliary battery 28 reaches or exceeds the first predetermined voltage Sb1 when the voltage of the auxiliary battery 28 falls below the first predetermined voltage Sb1 (an example of a second charging state). After performing the first charging control, the control device 20 returns the process to step S2.

[0032] In step S6, the control device 20 continues to monitor the voltage of the auxiliary battery 28 while updating the lower limit voltage Sbm of the auxiliary battery 28 downward. The lower limit voltage Sbm is a voltage value at which the control device 20 and communication device are started again and information is transmitted to the user terminal 32 to prompt charging. After updating the lower limit voltage Sbm downward, the control device 20 proceeds to the process of step S7. The processes from step S4 to step S7 correspond to the portion indicated by the arrow F via D to E or the arrow F to H in FIG. 3.

[0033] In step S7, the control device 20 determines whether the voltage Sb of the auxiliary battery 28 is less than a second predetermined voltage Sb2. The second predetermined voltage Sb2 is a voltage value smaller than the first predetermined voltage Sb1. The second predetermined voltage Sb2 is a voltage value at which the control device 20 cannot be started if the auxiliary battery 28 is discharged any further. If the control device 20 determines in step S7 that the voltage Sb of the auxiliary battery 28 is less than the second predetermined voltage Sb2 (YES in step S7), the control device 20 proceeds to the process of step S8. If the control device 20 determines in step S7 that the voltage Sb of the auxiliary battery 28 is equal to or greater than the second predetermined voltage Sb2 (NO in step S7), the control device 20 returns the process to step S4.

[0034] In step S8, the control device 20 determines whether the storage rate SOC1 of the drive battery 10 is less than a second predetermined storage rate Mb2. If the storage rate SOC1 is less than the second predetermined storage rate Mb2, the drive battery 10 may run out of power, for example, when the electric vehicle C is driven or when the internal combustion engine 2 is started.

[0035] When the control device 20 determines that the charging rate SOC1 of the driving battery 10 is less than the second predetermined charging rate Mb2 (YES in step S8), the control device 20 proceeds to step S9. In step S9, the control device 20 starts up the communication device and notifies the user terminal 32 of information that the device will enter a discharge reduction mode that suppresses the discharge of standby power. After notifying the user terminal 32 of the information that the device will enter the discharge reduction mode, the control device 20 proceeds to step S10. In step S10, the control device 20 executes the discharge reduction mode and proceeds to step S11. In step S11, the control device 20 finally causes the auxiliary battery 28 to run out of power before the driving battery 10, and ends the control procedure. Note that steps S8 to S11 correspond to the arrows H to I in FIG. 3.

[0036] When the control device 20 determines in step S2 that the voltage Sb of the auxiliary battery 28 is equal to or higher than the first predetermined voltage Sb1 (NO in step S2), it repeats step S2 until the voltage Sb of the auxiliary battery 28 becomes lower than the first predetermined voltage Sb1.

[0037] When the control device 20 determines that the charging rate SOC1 of the driving battery 10 is equal to or higher than the first predetermined charging rate Mb1 (step S3 NO), the control device 20 proceeds to step S12. In step S12, the control device 20 starts the first charging control. In the first charging control, the control device 20 charges the auxiliary battery 28 to the upper limit voltage Sba. Specifically, as shown by the arrows A to B in FIG. 3, the voltage Sb of the auxiliary battery 28 drops from the upper limit voltage Sba to less than the first predetermined voltage Sb1 due to standby power. As shown by the arrows B to C in FIG. 3, even in such a case, when the charging rate SOC1 of the driving battery 10 is equal to or higher than the first predetermined charging rate Mb1, the control device 20 executes the first charging control and charges the driving battery 10 to the upper limit voltage Sba. On the other hand, as shown by the arrows C to D in FIG. 3, when the charging rate SOC1 of the driving battery 10 is less than the first predetermined charging rate Mb1, the control device 20 starts the second charging control.

[0038] If the control device 20 acquires information permitting charging from the user terminal 32 in step S5 (step S5 NO), the process proceeds to step S12. In step S12, the control device 20 executes the first charging control. As shown by the arrows E to A in Fig. 3, for example, in the case of a plug-in hybrid vehicle of this embodiment, when the control device 20 obtains permission from the user terminal 32, the control device 20 starts the internal combustion engine 2 to generate power, charges the driving battery 10, and charges the auxiliary battery 28 to the upper limit voltage Sba. In addition, the control device 20 may execute the first charging control by various methods, such as the user inserting the charging gun 30a into the plug 30b to charge, or the user turning on the ignition switch 22 to run the vehicle.

[0039] When the control device 20 determines in step S7 that the voltage Sb of the auxiliary battery 28 is equal to or higher than the second predetermined voltage Sb2 (NO in step S7), the process proceeds to step S4. In step S7, the control device 20 continues to notify the user terminal 32 while updating the lower limit voltage Sbm until the voltage Sb of the auxiliary battery 28 becomes lower than the second predetermined voltage Sb2.

[0040] If the control device 20 determines in step S8 that the charging rate SOC1 of the driving battery 10 is equal to or higher than the second predetermined charging rate Mb2, the process proceeds to step S13 and executes the third charging control. The third charging control is a control for charging the auxiliary battery 28 as an emergency avoidance measure when the charging rate SOC1 of the driving battery 10 is equal to or higher than the second predetermined charging rate Mb2. As shown by the arrows F to G in Fig. 3, in this case the control device 20 charges the auxiliary battery 28 to the first predetermined voltage Sb1. This makes it possible to suppress a decrease in the charging rate SOC1 of the driving battery 10.

[0041] As described above, according to the control system 1 of the electric vehicle C disclosed herein, the first charging control and the second charging control are performed according to the charging states of the drive battery 10 and the auxiliary battery 28, so that the auxiliary battery 28 can be charged while preventing the drive battery 10 from running out of power.

[0042] <Other embodiments> Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0043] (a) In the above embodiment, a plug-in hybrid electric vehicle (PHEV) has been described as an example, but the present disclosure is not limited thereto. The electric vehicle C may be a battery EV that is not equipped with an internal combustion engine 2. The EV mode control in the above embodiment can be applied to such a battery EV. Alternatively, the electric vehicle C may be a hybrid vehicle. The electric vehicle C may also perform external power feeding, which supplies power from the driving battery 10 to the outside. In this case, the control device 20 may apply the above control in accordance with a decrease in the charging rate SOC1 of the driving battery 10 due to external power feeding.

[0044] (b) In the above embodiment, an example has been described in which information encouraging charging is notified to the user terminal 32, but the present disclosure is not limited to this. The information encouraging charging may be displayed, for example, on an instrument panel or a liquid crystal screen of the electric vehicle C.

[0045] (c) In the above embodiment, the driving battery 10 is used as an example of the first battery, and the auxiliary battery 28 is used as an example of the second battery, but the present disclosure is not limited to this. The first battery may be any battery capable of charging the second battery, and the second battery may be any battery that is charged by the first battery. Therefore, the first battery does not necessarily have to be the driving battery 10 that supplies power to each motor. Furthermore, the second battery does not necessarily have to be the auxiliary battery 28 that supplies power to the electrical components 26. [Explanation of symbols]

[0046] 1: Control system, 6: Front motor, 10: Drive battery 20: Control device, 26: Electrical components, 28: Auxiliary battery C: Electric vehicles Mb1: 1st predetermined charging rate, Mb2: 2nd predetermined charging rate SOC1: Charge rate of the drive battery SOC2: Charge rate of the auxiliary battery Sb: voltage, Sb1: first predetermined voltage, Sb2: second predetermined voltage

Claims

1. a first battery that supplies power to a rotating electric machine used to run the vehicle; a second battery that receives charge from the first battery; A control device that controls the first battery and the second battery; Equipped with The control device includes: When the first battery is at or above a first charge state, a first charge control is executed to charge the second battery with power from the first battery and maintain the second battery at or above a second charge state; When the first battery is less than the first charged state, a second charging control is executed to maintain the charged state of the first battery; when the second battery is below a third state of charge that is less than the second state of charge; a third charge control is executed to charge the second battery even when the first battery is in a state of charge less than the first state of charge; Electric vehicle control system.

2. The vehicle may further include a notification unit that notifies the driver of information that prompts the driver to start the vehicle. The control device activates the notification means when the second battery falls below the second charge state. The control system for an electric vehicle according to claim 1 .

3. the control device executes the third charging control until the second battery reaches the second charging state. The control system for an electric vehicle according to claim 1 or 2.

4. The device further includes an electrical component that consumes standby power, The second battery supplies the standby power to the electrical component, if the second battery is less than a third state of charge that is less than the second state of charge and the first battery is less than a fourth state of charge that is less than the first state of charge; Reducing the standby power; A control system for an electric vehicle according to any one of claims 1 to 3.

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