JP7700865B2 - Electric vehicles - Google Patents

Description

The present invention relates to an electric vehicle that performs traction control to suppress slippage when slippage is detected between the left and right wheels.

Conventionally, in a vehicle in which the left and right wheels are driven by an electric motor, when slippage is detected in the left or right wheels, it is known to perform traction control that limits the torque output from the electric motor to suppress the slippage, and traction control that applies a braking force to the slipping wheel.

For example, Patent Document 1 discloses that when a drive wheel slips, a traction control that limits the torque output from the motor at a predetermined rate and a brake traction control that outputs a braking force (brake torque) to the slipping wheel are performed. In Patent Document 1, the former traction control is performed by a main electronic control unit, and the latter brake traction control is performed by a brake electronic control unit. In the vehicle of Patent Document 1, if it is determined that the latter brake traction control is intervening while the former traction control is being performed, the torque output from the motor is limited at a rate with a smaller gradient than the above-mentioned predetermined rate. This is said to suppress interference between the two types of traction control and improve the driving feeling when suppressing the slip that occurs.

JP 2006-256367 A

Recently, a technology has been proposed in which a specific program is incorporated into a control device (MCU; Motor Control Unit) that controls the motor. This MCU is provided separately from an electronic control unit (ECU; Electronic Control Unit) that provides integrated control of various devices mounted on the vehicle. By incorporating the above-mentioned traction control program into the MCU, it becomes possible to control the vehicle by taking advantage of the high responsiveness of the motor. On the other hand, in such a vehicle, if the traction control performed by the MCU and the traction control that applies the above-mentioned braking force are performed separately, the two types of control may interfere with each other, leading to reduced controllability and fluctuations in driving force.

The electric vehicle of this invention was devised in consideration of these problems, and one of its objectives is to appropriately suppress slippage while taking advantage of the high responsiveness of the motor (electric motor). However, this objective is not the only objective, and another objective of this invention is to achieve an effect that cannot be obtained by conventional technology, which is derived from each configuration shown in the description of the embodiment of the invention described below.

(1) The electric vehicle disclosed herein is an electric vehicle including an electric motor for driving left and right wheels and a brake for applying a braking force to the left and right wheels, and includes a host control device that calculates a required torque of the electric vehicle, an electric motor control device that receives the required torque calculated by the host control device to control the electric motor and performs traction control to reduce the torque of the electric motor based on the rotational acceleration of the electric motor, a brake control device that performs slip suppression control to apply a braking force to the one wheel by activating the brake when slip of one of the left and right wheels is detected, and a battery management device that acquires a battery voltage of a battery that exchanges power with the electric motor . When the electric motor control device receives a signal from the brake control device indicating the execution or non-execution of the slip suppression control after the execution, the electric motor control device adjusts the amount of torque to be reduced by the traction control in accordance with the received signal. When the battery voltage received from the battery management device without going through the higher-level control device exceeds a predetermined upper limit voltage, the motor control device reduces the amount of torque reduced by the traction control, calculates a compensatory braking force to compensate for the reduced amount of torque reduced by the traction control, and transmits the calculated compensatory braking force to the brake control device. When the brake control device receives the compensatory braking force from the motor control device, the brake control device executes battery protection control to apply the compensatory braking force to both the left and right wheels by activating the brake.

(2) It is preferable that the brake control device judges whether or not the slip suppression control should be performed based on the rotation speeds of the left and right wheels, and transmits the braking force to be applied to the one wheel together with the signal to the motor control device. In this case, it is preferable that the motor control device corrects the torque amount based on the braking force received from the brake control device.

(3) It is preferable that the motor control device calculates a corrected braking force to be applied to the one wheel based on the corrected torque amount and transmits the calculated braking force to the brake control device. In this case, it is preferable that the brake control device applies the corrected braking force received from the motor control device to the one wheel.

( 4 ) When the brake control device performs both the slip suppression control and the battery protection control, it is preferable that the motor control device corrects the torque amount based on the braking force applied to one of the wheels by the slip suppression control and the braking forces applied to both the left and right wheels by the battery protection control.

The disclosed vehicle makes it possible to appropriately suppress slip while taking advantage of the high responsiveness of the motor (electric motor).

1 is a schematic diagram of a front portion of an electric vehicle according to an embodiment. FIG. FIG. 2 is a schematic diagram showing a configuration of the electric vehicle shown in FIG. 1 . 4 is a flowchart for explaining traction control performed by an electric motor control device provided in the electric vehicle shown in FIG. 1 . 4 is an example of a time chart illustrating the operation of the electric vehicle shown in FIG. 1 , showing a case in which the first control and the third control are not implemented. 4 is an example of a time chart illustrating the operation of the electric vehicle shown in FIG. 1 , showing a case where only the third control is executed. 4 is an example of a time chart illustrating the operation of the electric vehicle shown in FIG. 1 , showing a case where only the first control is executed. 4 is an example of a time chart illustrating the operation of the electric vehicle shown in FIG. 1 , showing a case where a first control and a third control are performed.

An electric vehicle as an embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and are not intended to exclude the application of various modifications or techniques not explicitly stated in the following embodiments. Each configuration of this embodiment can be modified in various ways without departing from the spirit of the embodiment. In addition, the configurations can be selected as necessary, or can be combined as appropriate.

[1. Configuration]
1 is a schematic diagram showing the front of an electric vehicle 1 (hereinafter referred to as "vehicle 1") according to this embodiment. Vehicle 1 is equipped with an electric motor 2 (electric motor) that drives left and right wheels 6 and a brake 9 (brake) that brakes the left and right wheels 6. Vehicle 1 according to this embodiment further includes an engine 3 and a generator 4, and is capable of external charging. In other words, vehicle 1 is a plug-in hybrid vehicle (hybrid vehicle) that includes the electric motor 2 and the engine 3 as drive sources.

The electric motor 2 is an electric motor/generator that has both the function of driving the left and right wheels 6 with power from the battery 7 or power generated by the generator 4, and the function of charging the battery 7 with regenerative power generated by utilizing the inertial rotation of the left and right wheels 6. The battery 7 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is a secondary battery capable of supplying a high-voltage direct current of several hundred volts.

The engine 3 is an internal combustion engine such as a gasoline engine or a diesel engine, and drives the rotating shafts of the left and right wheels 6 by burning a mixture of fuel and air in a combustion chamber. The engine 3 is capable of outputting driving force for causing the generator 4 to generate electricity and driving force for propelling the vehicle 1.

The generator 4 is a generator that generates electricity using the driving force of the engine 3. The electric motor 2, the engine 3, and the generator 4 are connected via a transaxle 5. Inside the transaxle 5, for example, a transmission gear and a clutch device are built in.

The electric motor 2, engine 3 and generator 4 are used separately or in combination depending on the operating state of the vehicle 1. For example, when starting or running at low speed, only the electric motor 2, which has a large torque at low revolutions, is used (EV mode). On the other hand, when the charging rate of the battery 7 is low or when accelerating, the vehicle runs on the driving force (motor torque) of the electric motor 2 while generating electricity in the generator 4 using the driving force of the engine 3 (series mode). Also, when running at high speeds where the engine is efficient, the driving force of the engine 3 is used as the main force, and the driving force of the electric motor 2 is used as a supplement (parallel mode, ENG mode). Each of these modes is appropriately selected and implemented by the upper control device 10, which will be described later.

The brake 9 is, for example, a hydraulic disc brake that brakes the left and right wheels 6 based on the amount of brake pedal operation BP described below. The brake 9 is not limited to this as long as it is a device capable of braking the left and right wheels 6, and may be an electric brake. The brake 9 is configured to be able to apply different amounts of braking force (brake torque) to the left wheel 6L on the left side of the vehicle and the right wheel 6R on the right side of the vehicle.

The vehicle 1 is provided with a plurality of control devices that control and monitor various devices mounted on the vehicle 1. Specifically, as shown in Fig. 2, the vehicle 1 is provided with a host control device 10 (Electronic Control Unit, hereinafter also referred to as "ECU 10") that performs integrated control of various devices mounted on the vehicle, a motor control unit 11 (Motor Control Unit, hereinafter also referred to as "MCU 11") that controls the electric motor 2, a hydraulic unit 12 (Hydraulic Unit, brake control device, hereinafter also referred to as "H/U 12") that controls the brake 9, and a battery management unit 13 (Battery Management Unit, hereinafter also referred to as "BMU 13") that manages the state of the battery 7.

Each of the control devices 10 to 13 is an electronic control device (computer) that incorporates a processor (central processing unit), memory (main memory), storage device, interface, etc. The contents of the control performed by each of the control devices 10 to 13 are recorded and stored in memory as firmware or application programs, and when a program is executed, the contents of the program are expanded in memory space and executed by the processor.

In addition to the engine 3 and generator 4, an accelerator opening sensor 21, a brake sensor 22, etc. are connected to the ECU 10. The accelerator opening sensor 21 detects an accelerator opening AP corresponding to the amount of depression of the accelerator pedal. The brake sensor 22 detects the amount of brake pedal operation BP. In addition to the electric motor 2, a resolver 23 is connected to the MCU 11. The resolver 23 detects the rotation speed of the output shaft 2s (see FIG. 1) of the electric motor 2 (hereinafter referred to as "motor rotation speed Nm"). Note that instead of the resolver 23, the motor rotation speed Nm may be detected by a hall sensor or an encoder. The MCU 11 may also include an inverter (not shown) that converts DC current and AC current, or the MCU 11 and the inverter may be provided separately.

In addition to the brake 9, a left wheel speed sensor 24L attached to the left wheel 6L and a right wheel speed sensor 24R attached to the right wheel 6R are connected to the H/U 12. The left wheel speed sensor 24L detects the rotation speed of the left wheel 6L (hereinafter referred to as "left wheel rotation speed Nwl"). The right wheel speed sensor 24R detects the rotation speed of the right wheel 6R (hereinafter referred to as "right wheel rotation speed Nwr"). A hydraulic pressure sensor 25 that detects the hydraulic pressure of the brake 9 may be connected to the H/U 12. A voltage sensor 26 that detects the battery voltage V of the battery 7 is connected to the BMU 13.

The control devices 10 to 13 are connected to each other so that they can communicate with each other via a CAN (Controller Area Network) bus 14. The MCU 11 and H/U 12 are connected to each other so that they can communicate with each other via a first bus 15. The MCU 11 and BMU 13 are connected to each other so that the MCU 11 can receive information transmitted from the BMU 13 via a second bus 16.

The first bus 15 and the second bus 16 may be included in the above-mentioned CAN bus 14, or may be configured as a communication network independent of the CAN bus 14. Furthermore, multiple CAN buses may be used to connect each of the control devices 10-13. For example, a CAN bus may be provided that connects the ECU 10 to a drive system control device (e.g., MCU 11), and a CAN bus may be provided that connects the ECU 10 to a braking system control device (e.g., H/U 12).

2. Control Configuration
The configuration of the control performed by each of the control devices 10 to 13 will be described below.
The ECU 10 performs integrated control of various devices based on information received from each of the control devices 11 to 13 and information acquired from the engine 3, generator 4, and sensors 21 and 22 connected to the ECU 10. For example, the ECU 10 sets a mode according to the operating state of the vehicle 1 based on the above information, and controls the electric motor 2, the engine 3, and the generator 4 to realize driving in the set mode.

To explain in detail an example in which the ECU 10 selects the series mode, the ECU 10 calculates a required torque Tr to be output by the electric motor 2 based on the operating state of the vehicle 1, and indirectly controls the electric motor 2 by transmitting the calculated required torque Tr to the MCU 11 via the CAN bus 14. Furthermore, the ECU 10 receives a torque command value Ti (described below) that the MCU 11 commands the electric motor 2 to have from the MCU 11 via the CAN bus 14, and controls the engine 3 and the generator 4 so that a generated power P according to the received torque command value Ti is output.

Furthermore, the ECU 10 calculates the required brake torque to be applied to the left and right wheels 6 based on the brake pedal operation amount BP and other information, and indirectly controls the brake 9 by transmitting the calculated required brake torque to the H/U 12 via the CAN bus 14. Note that the calculation method of the required torque Tr and the required brake torque is not particularly limited, and they can be calculated based on information such as the accelerator opening AP, vehicle speed (left and right wheel rotation speeds Nwl, Nwr and vehicle speed), brake pedal operation amount BP, steering angle, battery voltage V, etc.

The MCU 11 receives the required torque Tr calculated by the ECU 10 and controls the electric motor 2 to output the received required torque Tr. Specifically, the MCU 11 calculates a torque command value Ti based on the required torque Tr and controls the electric motor 2 by instructing the electric motor 2 (or the inverter if the inverter is provided separately from the MCU 11). The MCU 11 transmits information that it manages, calculates, and acquires (e.g., the torque command value Ti, the motor rotation speed Nm detected by the resolver 23, the motor temperature, the inverter temperature, etc.) to the ECU 10 via the CAN bus 14.

Furthermore, when the MCU 11 detects (determines) that at least one of the left and right wheels 6 is slipping, it implements traction control to reduce the torque output from the electric motor 2 to a value lower than the required torque Tr. Whether the left and right wheels 6 are slipping is determined, for example, based on the rotational acceleration R, which is the rate of change of the motor rotation speed Nm. Specifically, the MCU 11 calculates the rotational acceleration R based on the motor rotation speed Nm detected by the resolver 23, and determines that the left and right wheels 6 are slipping when the calculated rotational acceleration R is equal to or greater than a predetermined rotational acceleration R1. The predetermined rotational acceleration R1 is, for example, preset as a value greater than the maximum value of the rotational acceleration R obtained when the vehicle 1 is traveling without the left and right wheels 6 spinning.

To implement traction control, the MCU 11 calculates the torque amount ΔT to be subtracted from the required torque Tr, calculates the value obtained by subtracting the torque amount ΔT from the required torque Tr as a torque command value Ti, and sends the torque command value Ti to the inverter to control the electric motor 2. Since the electric motor 2 outputs a motor torque equivalent to the torque command value Ti from the MCU 11, the torque command value Ti can also be said to be the motor torque.

In addition, the MCU 11 ends the traction control when a predetermined end condition is satisfied during the implementation of the traction control. The predetermined end condition includes the elimination of slippage and the fluctuation of the required torque Tr (for example, the fluctuated required torque Tr becomes smaller than the torque command value Ti). The predetermined end condition may also include the torque reduction amount, i.e., the torque amount ΔT, becoming equal to or less than a certain value. For example, when the calculated torque amount ΔT becomes a value below the accuracy of the control torque, in other words, a value that should be recognized as 0, the MCU 11 may determine that it is okay to end the traction control and end the traction control. The MCU 11 may end the traction control when the state in which the torque amount ΔT becomes equal to or less than a certain value continues for a certain period of time or more. The predetermined end condition may also include the accelerator opening AP becoming equal to or less than a predetermined value. The predetermined value is set to a value that can be determined to be that the driver has no clear intention (request) to start or accelerate. Furthermore, the specified termination conditions may include conditions based on parameters such as the motor rotation speed Nm, rotational acceleration R, vehicle speed (left and right wheel rotation speeds Nwl, Nwr and vehicle speed), motor torque, and switch operations by the driver.

The H/U 12 receives the required brake torque calculated by the ECU 10 and controls the brake 9 to output the received required brake torque. The H/U 12 also transmits information that it manages, calculates, and acquires (e.g., left wheel rotation speed Nwl, right wheel rotation speed Nwr, hydraulic pressure, etc.) to the ECU 10 via the CAN bus 14.

In addition, when H/U 12 detects slippage of one of the left wheel 6L and right wheel 6R (one-wheel slippage), it implements slip suppression control to apply a braking force (hereinafter referred to as "first braking force F1") to the slipping wheel (left wheel 6L or right wheel 6R).

The necessity of slip suppression control is determined based on the left wheel rotation speed Nwl and the right wheel rotation speed Nwr. Specifically, when either the left wheel rotation speed Nwl or the right wheel rotation speed Nwr is extremely higher than the other, H/U 12 detects (determines) one-wheel slip and performs slip suppression control. More specifically, when the left wheel rotation speed Nwl is extremely higher than the right wheel rotation speed Nwr, H/U 12 determines that the left wheel 6L is slipping and controls the brake 9 to apply a first braking force F1 to the left wheel 6L. Conversely, when the right wheel rotation speed Nwr is extremely higher than the left wheel rotation speed Nwl, H/U 12 determines that the right wheel 6R is slipping and controls the brake 9 to apply a first braking force F1 to the right wheel 6R.

When the H/U 12 starts the slip suppression control, it starts to send a first signal (signal, for example, flag information) indicating the implementation of the slip suppression control to the MCU 11 via the first bus 15, and continues to send the signal while the slip suppression control is being implemented. In addition, the H/U 12 of this embodiment sends the braking force applied to the slipping wheel (left wheel 6L or right wheel 6R) to the MCU 11 together with the first signal. Here, the braking force applied to the slipping wheel may be the first braking force F1 (the target value of the braking force set by the H/U 12 during the implementation of the slip suppression control or the instruction value of the braking force actually sent to the brake 9), or, if a hydraulic pressure sensor 25 is connected to the H/U 12, it may be the detected hydraulic pressure (i.e., the actual measured value of the braking force actually applied to one of the wheels).

When a predetermined suppression control end condition is satisfied during the implementation of the above-mentioned slip suppression control, the H/U 12 ends the slip suppression control, stops transmitting the first signal, and stops the control. The predetermined suppression control end condition may include that one-wheel slip is eliminated (for example, that the rotation speed Nwl, Nwr of one slipping wheel becomes equal to the rotation speed Nwl, Nwr of the other wheel). The predetermined suppression control end condition may also include that the torque reduction amount of the traction control, i.e., the torque amount ΔT, becomes equal to or less than a certain value, or that the state in which the torque amount ΔT is equal to or less than a certain value continues for a certain period of time. In this case, the H/U 12 may be configured to receive the torque amount ΔT from the MCU 11. The MCU 11 may end the slip suppression control when the calculated first braking force F1 becomes a value below the accuracy of the control torque, in other words, a value that should be recognized as 0, or when this state has continued for a certain period of time. In addition, the predetermined suppression control end condition may include that the accelerator opening AP becomes equal to or less than a certain value. The predetermined value is set to a value that can determine that the driver has no clear intention (request) to start or accelerate, similar to the traction control termination condition. In addition, the predetermined value may include conditions based on parameters such as the motor rotation speed Nm, rotation acceleration R, vehicle speed (left and right wheel rotation speeds Nwl, Nwr and vehicle speed), motor torque, and switch operations by the driver.

Immediately after the end of the slip suppression control, the H/U 12 gradually reduces the first braking force F1 applied to the slipping wheel (left wheel 6L or right wheel 6R) to zero. When the H/U 12 ends the slip suppression control, the H/U 12 starts to send a second signal (signal, e.g., flag information) indicating that the slip suppression control is not being performed to the MCU 11 via the first bus 15. At this time, the H/U 12 may send the first braking force F1, which is to be gradually reduced, to the MCU 11. The H/U 12 continues to send the second signal until the traction control is ended or the slip suppression control is resumed.

The BMU 13 is a unit that monitors the state of the battery 7 (such as the charging state and temperature state), acquires the battery voltage V detected by the voltage sensor 26, and transmits the acquired battery voltage V to the ECU 10 via the CAN bus 14. The BMU 13 also calculates the charging rate (State of Charge, hereinafter also referred to as "SOC") of the battery 7 from the battery voltage V, and transmits the calculated SOC to the ECU 10 via the CAN bus 14. In this embodiment, the BMU 13 also transmits the battery voltage V to the MCU 11 via the second bus 16.

[3. Control configuration related to traction control]
As described above, the traction control for suppressing slip of the left and right wheels 6 and the slip suppression control for suppressing one-wheel slip are respectively implemented by the MCU 11 and the H/U 12. At this time, if the traction control and the slip suppression control are implemented independently, the two types of control may interfere with each other, leading to a decrease in controllability and fluctuations in driving force. Therefore, in the vehicle 1 of this embodiment, when both types of control are implemented (overlapping), the MCU 11 adjusts the control amount (torque amount ΔT) to be reduced by the traction control. Also, in the vehicle 1 of this embodiment, even when the currently implemented slip suppression control is not implemented, the MCU 11 adjusts the control amount to suppress a decrease in controllability and fluctuations in driving force.

A more specific explanation will be given. In this embodiment, when the MCU 11 receives a first signal from the H/U 12 while the traction control is being performed, the MCU 11 performs a first control that adjusts the torque amount ΔT to be reduced by the traction control so as to suppress it. In other words, when the first control is performed, the amount of reduction in the motor torque is smaller than during traction control when the first control is not performed. The torque amount ΔT is suppressed, for example, by subtracting a predetermined amount (hereinafter referred to as "first predetermined amount X") from the torque amount calculated when the traction control is performed (hereinafter referred to as "base torque amount ΔTb").

As a result, the torque command value Ti (required torque Tr minus torque amount ΔT) sent from the MCU 11 to the electric motor 2 during implementation of the first control increases by the amount obtained by subtracting the first predetermined amount X compared to during traction control in which the first control is not implemented (compared to before the torque amount ΔT is suppressed). Thus, excessive torque suppression of the left and right wheels 6 due to overlapping of the traction control and slip suppression control is prevented. The base torque amount ΔTb is a variable value calculated based on the degree of slip of the left and right wheels 6 (i.e., the rotational acceleration R), and is calculated each time traction control starts.

In addition, the MCU 11 of this embodiment receives the first braking force F1 together with the first signal, and corrects the torque amount ΔT based on the first braking force F1. For example, the MCU 11 reduces the torque amount ΔT as the first braking force F1 increases. In other words, in the above example, the first predetermined amount X is a variable value set according to the first braking force F1, and is set to a larger value as the first braking force F1 increases. As a result, the torque command value Ti sent from the MCU 11 to the electric motor 2 during the implementation of the first control increases as the first braking force F1 increases (compared to before the torque amount ΔT is suppressed) compared to during traction control in which the first control is not implemented. Therefore, when the first braking force F1 is received, excessive torque suppression of the left and right wheels 6 is more reliably prevented.

Furthermore, when MCU 11 receives a second signal from H/U 12 indicating the end (non-execution) of slip suppression control, MCU 11 implements a second control that adjusts the torque amount ΔT suppressed by the first control to increase it. In other words, when slip suppression control by H/U 12 goes from being executed to not being executed, MCU 11 implements a second control that adjusts the torque amount ΔT suppressed by the first control to return it to the original amount.

The MCU 11 increases the torque amount ΔT, for example, by adding a predetermined amount (hereinafter referred to as the "second predetermined amount X'") to the torque amount ΔT (= ΔTb - X) suppressed in the first control. As a result, the torque command value Ti (the value obtained by subtracting the torque amount ΔT from the required torque Tr) sent from the MCU 11 to the electric motor 2 during the second control is reduced by the amount obtained by adding the second predetermined amount X' compared to when the first control is being performed (compared to when the torque amount ΔT is suppressed).

In addition, when the MCU 11 of this embodiment performs the second control, it receives the first braking force F1, which is gradually reduced, and corrects the torque amount ΔT based on the first braking force F1. For example, the MCU 11 increases the torque amount ΔT as the first braking force F1 gradually decreases. That is, in the above example, the second predetermined amount X' is a variable value that is set according to the first braking force F1, which is gradually reduced, and is set to a value closer to the first predetermined amount X as the first braking force F1 is gradually reduced. As a result, slip-up of the left and right wheels 6 caused by the loss of the first braking force F1 applied to one wheel after the first control ends is suppressed.

In the above explanation, for convenience of explanation, the contents of the first control and the second control are explained separately, but the first control and the second control have something in common in that MCU11 adjusts the control amount. Also, the first signal and the second signal have something in common in that they are signals indicating whether or not slip suppression control is being performed (implemented state). Therefore, the first control and the second control may be treated as one control, or the first signal and the second signal may be treated as the same signal.

In this embodiment, the MCU 11 further performs a third control to suppress the torque amount ΔT to be reduced by the traction control when it determines that the battery voltage V received from the BMU 13 exceeds a predetermined upper limit voltage Vmax during the implementation of the traction control. The upper limit threshold Vmax is preset to a value equal to or slightly smaller than the allowable upper limit voltage of the battery 7, for example.

Here, the case where the battery voltage V exceeds the upper limit voltage Vmax will be described in detail. As described above, when the series mode is selected, the ECU 10 sets the power generation P according to the torque command value Ti (motor torque). Therefore, when the traction control is started and the torque command value Ti is suppressed, the engine 3 and the generator 4 are controlled so that the power generation P is reduced. However, since the electric motor 2 has a faster response speed than the engine 3 and the generator 4, the motor torque output by the electric motor 2 is reduced before the power generation P is reduced. As a result, the power not consumed by the electric motor 2 is transferred from the electric motor 2 to the battery 7, and the battery voltage V increases, which may exceed the upper limit voltage Vmax. The reason why the electric motor 2 has a faster response speed is that there is a communication lag caused by the CAN bus 14, and the engine 3 and the generator 4 are controlled via the ECU 10.

Therefore, in this embodiment, when the battery voltage V exceeds the upper limit voltage Vmax, the MCU 11 suppresses the torque amount ΔT to be reduced by the traction control. That is, when the third control is implemented, the reduction amount of the motor torque is smaller than during the traction control when the third control is not implemented. The torque amount ΔT is suppressed, for example, by subtracting a predetermined amount (hereinafter referred to as the "third predetermined amount Y") from the base torque amount ΔTb. As a result, the torque command value Ti sent from the MCU 11 to the electric motor 2 during the implementation of the third control is increased by the amount obtained by subtracting the third predetermined amount Y compared to during the traction control when the third control is not implemented (before the torque amount ΔT is suppressed). Therefore, the power consumed by the electric motor 2 is increased (secured), and the increase in the battery voltage V is suppressed.

Furthermore, when implementing the third control, the MCU 11 calculates a compensatory braking force that compensates for the suppression of the torque amount ΔT, in other words, a compensatory braking force equivalent to the third predetermined amount Y (hereinafter referred to as "second braking force F2"), and transmits the calculated second braking force F2 to the H/U 12 via the first bus 15. Upon receiving the second braking force F2, the H/U 12 implements battery protection control that applies the second braking force F2 to both the left wheel 6L and the right wheel 6R. As a result, the motor torque corresponding to the suppression of the torque amount ΔT by the third control is offset by the second braking force F2, thereby maintaining the stability of the vehicle 1.

Furthermore, when the third control is performed, the MCU 11 may transmit a third signal indicating that the third control is being performed to the ECU 10 via the CAN bus 14. When the ECU 10 receives the third signal, the ECU 10 may control the engine 3 and the generator 4 to reduce the generated power P. This further reduces the battery voltage V, thereby further ensuring the safety of the battery 7.

To summarize the control configuration related to the traction control described above, the first control, second control, and third control are all implemented by MCU 11 while traction control is being performed. Furthermore, the slip suppression control and battery protection control are all implemented by H/U 12. The first control and second control are controls that are implemented depending on whether or not slip suppression control is being performed, and both are not implemented simultaneously. On the other hand, the third control is a control that is implemented depending on the battery voltage V, regardless of whether or not slip suppression control is being performed, and can be implemented simultaneously with each of the first control and second control. Furthermore, the battery protection control is implemented depending on the implementation of the third control.

4. Flowchart
Fig. 3 is a flowchart for explaining the traction control performed by the MCU 11. This flowchart is executed at a predetermined calculation cycle when the MCU 11 receives the required torque Tr. Note that the initial value of a flag f in the flowchart of Fig. 3 for identifying whether or not the traction control is being performed is 0 (traction control not being performed).

In step S1, it is determined whether flag f is 0. As described above, since flag f has a value of 0 in the initial state, the flow proceeds to step S2, where it is determined whether the left and right wheels 6 are slipping (rotational acceleration R ≧ predetermined rotational acceleration R1). If it is determined in step S2 that neither the left nor right wheels 6 are slipping, traction control is deemed unnecessary, and the flow proceeds to step S15, where the required torque Tr received from the ECU 10 is set as the torque command value Ti, and in the following step S16, the torque command value Ti is sent to the electric motor 2 to control the electric motor 2, and the flow returns.

If it is determined in step S2 that the left and right wheels 6 are slipping in the next calculation cycle or later, the process proceeds to step S3, where flag f is set to a value of 1 indicating that traction control is being performed, and then in step S4, the torque amount ΔT (base torque amount ΔTb) to be reduced by traction control is calculated. Then, in steps S5, S7, and S9, it is determined whether or not the first control, second control, and third control are required.

That is, in step S5, it is determined whether or not a first signal has been received, in step S7, it is determined whether or not a second signal has been received, and in step S9, it is determined whether or not the battery voltage V exceeds the upper limit voltage Vmax. Here, if it is determined in step S5 that the first signal has not been received, in step S7 that the second signal has not been received because the first control has not been performed, and in step S9 that the battery voltage V does not exceed the upper limit voltage Vmax (i.e., if it is determined that all of steps S5, S8, and S9 are not established), the first control, the second control, and the third control are not performed, and the process proceeds to step S13.

In step S13, it is determined whether the above-mentioned traction control termination condition is satisfied. If it is determined in step S13 that the termination condition is satisfied, flag f is set to 0 in step S14 and the process proceeds to step S15. On the other hand, if it is determined in step S13 that the termination condition is not satisfied, flag f remains as it is (remains 1) and the process proceeds to step S15. Thereafter, the control process of the electric motor 2 (steps S15 and S16) is performed, and the flow returns. In this case, the torque command value Ti set in step S15 is set to a value obtained by subtracting the base torque amount ΔTb from the required torque Tr.

On the other hand, if it is determined in step S5 that the first signal has been received, the process proceeds to step S6, where the torque amount ΔT is adjusted to be suppressed (first control). At this time, the torque amount ΔT is corrected according to the first braking force F1 received from H/U 12. The torque amount ΔT is suppressed to, for example, a value obtained by subtracting a first predetermined amount X from the base torque amount ΔTb (ΔT = ΔTb - X). Thereafter, the process proceeds to step S9, where it is determined whether the battery voltage V exceeds the upper limit voltage Vmax.

If it is determined in step S9 that the battery voltage V does not exceed the upper limit voltage Vmax (the third control is not performed), the flag processing based on whether the termination condition is satisfied (steps S13 and S14) and the control processing of the electric motor 2 (steps S15 and S16) are performed in sequence, and the flow returns. In this case, the torque command value Ti set in step S15 is set to a value obtained by subtracting the torque amount ΔT (= ΔTb-X) suppressed (adjusted) by the first control from the required torque Tr.

On the other hand, if it is determined in step S9 that the battery voltage V exceeds the upper limit voltage Vmax, the flow proceeds to step S10, where the torque amount ΔT is further suppressed (third control). At this time, the torque amount ΔT is suppressed (corrected) to a value (ΔT=ΔTb-X-Y) obtained by subtracting a third predetermined amount Y from a value obtained by subtracting a first predetermined amount X from a base torque amount ΔTb. In the following step S11, the second braking force F2 is calculated, and in step S12, the second braking force F2 is transmitted to the H/U 12, and the flow proceeds to step S13. Then, flag processing based on whether the termination condition is met (steps S13 and S14) and control processing of the electric motor 2 (steps S15 and S16) are performed in order, and the flow returns. In this case, the torque command value Ti set in step S15 is set to a value obtained by subtracting the torque amount ΔT (=ΔTb-X-Y) suppressed (adjusted) by the first control and the third control from the required torque Tr.

If the termination condition is not satisfied in step S13 of the flow described above, the flag f will be 1 from the next calculation cycle onwards, so the process proceeds to step S5. Here, if it is determined in step S5 that the first signal has not been received, the process proceeds to step S7, where it is determined whether or not the second signal has been received. As described above, when the slip suppression control by the H/U 12 is changed from being performed to not being performed, the second signal is sent from the H/U 12 to the MCU 11, so step S7 is satisfied and the process proceeds to step S8. In the following step S8, the torque amount ΔT is adjusted to increase (second control). That is, the torque amount ΔT is increased, for example, to a value obtained by adding a second predetermined amount X' to the value of the torque amount suppressed by the first control (ΔT = ΔTb - X) [ΔT = (ΔTb - X) + X'].

Then, the process based on whether the third control is necessary (steps S9 to S12), the process of flag f based on whether the end condition is satisfied (steps S13 and S14), and the control process of the electric motor 2 (steps S15 and S16) are performed in order, and this flow returns. In this case, if the No route of step S9 is taken, the torque command value Ti set in step S15 is set to a value obtained by subtracting the torque amount ΔT [= (ΔTb-X) + X'] adjusted in step S8 from the required torque Tr. In addition, if the Yes route of step S9 is taken, the torque command value Ti is set to a value obtained by subtracting the torque amount ΔT [= (ΔTb-X) + X'] adjusted in step S8 by the third control from the required torque Tr.

If it is determined in steps S5, S7, and S9 whether the first control, the second control, and the third control are required, and only step S9 is satisfied, the process related to the third control is carried out in steps S10 to S12, and the process of flag f based on whether the termination condition is satisfied (steps S13 and S14) and the control process of the electric motor 2 (steps S15 and S16) are carried out in sequence, and the flow returns. In this case, the torque command value Ti set in step S15 is set to a value obtained by subtracting the torque amount ΔT (= ΔTb-Y) suppressed (adjusted) by the third control from the required torque Tr.

[5. Time Chart]
The operation of the vehicle 1 of this embodiment will be described with reference to Figures 4 to 7. The horizontal axis of each time chart represents time. Figure 4 is a time chart illustrating a case where neither the first control nor the third control is performed, and Figure 5 is a time chart illustrating a case where only the third control is performed. Figure 6 is a time chart illustrating a case where only the first control is performed, and Figure 7 is a time chart illustrating a case where both the first control and the third control are performed.

4 to 7, the torque command value Ti rises as the accelerator opening AP starts to increase at time t1, and the motor rotation speed Nm is detected to increase (rotational acceleration R≧predetermined rotational acceleration R1) at time t2. In both Figs. 4 and 5, the vehicle 1 accelerates or starts on a road surface where both the left and right wheels 6 are slippery (e.g., on ice), and in both Figs. 6 and 7, the vehicle 1 accelerates or starts on a road surface where one of the left and right wheels 6 (e.g., the right wheel 6R) is slippery (split μ road). In Figs. 4 and 6, the battery 7 has a high battery power (e.g., when the SOC is relatively low (e.g., when the SOC is less than 50%) and the battery temperature is appropriate), and in Figs. 5 and 7, the battery 7 has a low battery power (e.g., when the SOC is relatively high (e.g., when the SOC is close to 100%) or when the battery temperature is higher or lower than the appropriate temperature).

First, the operation of the vehicle 1 of this embodiment will be described with reference to the time chart of FIG. 4. At time t2, as the motor rotation speed Nm is detected to be increasing, the MCU 11 starts traction control to reduce the motor torque (torque command value Ti). As a result, the torque command value Ti becomes a value [Ti=Tr-ΔT (=ΔTb)] lower than the required torque Tr transmitted from the ECU 10, suppressing slippage (idling) of the left and right wheels 6. Therefore, the vehicle 1 is prevented from skidding, and stable acceleration or starting is achieved. In the time chart of FIG. 4, since both the left wheel 6L and the right wheel 6R slip, the above-mentioned first control is not performed, and the braking force of the left wheel 6L and the right wheel 6R is always 0.

When the ECU 10 receives a notice that traction control has started at time t2, the ECU 10 controls the engine 3 and the generator 4 so that the generated power P corresponds to the torque command value Ti. As a result, the generated power P gradually decreases from time t2 until it becomes the generated power P corresponding to the torque command value Ti. The battery voltage V increases due to the transfer of power that was not consumed by the electric motor 2 from time t2 until it becomes the generated power P corresponding to the torque command value Ti. As described above, this power transfer occurs because the electric motor 2 has a faster response speed than the engine 3 and the generator 4. However, when the battery 7 has a high battery input power, the battery voltage V fluctuates little due to the power transfer, so the battery voltage V remains in a range lower than the upper limit voltage Vmax. Therefore, the safety of the battery 7 is guaranteed.

On the other hand, as shown in the time chart of Figure 5, when the battery input power of battery 7 is low, there is little margin for battery voltage fluctuation due to power transfer. For this reason, battery voltage V rises sharply from time t2, exceeding upper limit voltage Vmax at time t3. In response to this, MCU 11 implements a third control to suppress torque amount ΔT. Therefore, torque command value Ti becomes a higher value [Ti = Tr - ΔT (= ΔTb - Y)] than when third control is not implemented (two-dot chain line for torque command value in Figure 5), and power consumed by motor 2 increases. This suppresses the rise in battery voltage V after time t3.

Furthermore, at time t3, when H/U 12 receives the second braking force F2 calculated by MCU 11, battery protection control is implemented to apply the second braking force F2 to both the left wheel 6L and the right wheel 6R. As a result, the second braking force F2 is applied to the left wheel 6L and the right wheel 6R, and the motor torque (torque command value Ti) that has increased by the amount of torque ΔT suppressed is offset by the second braking force F2, thereby maintaining the stability of the vehicle 1.

When the ECU 10 receives the third signal from the MCU 11 indicating that the third control has started at time t3, the ECU 10 controls the engine 3 and the generator 4 to reduce the generated power P compared to when the third control is not implemented (the two-dot chain line of the generated power in FIG. 5). As a result, the battery voltage V applied to the battery 7 becomes even smaller after time t3 and starts to decrease, and the battery 7 is appropriately protected.

Next, the operation of the vehicle 1 when the first control is implemented will be described with reference to the time chart of FIG. 6. In the time chart of FIG. 6, as in the time chart of FIG. 4, traction control is started at time t2 by the MCU 11 to reduce the motor torque (torque command value Ti). However, in the example of the time chart of FIG. 6, only the right wheel 6R slips, so the motor rotation speed Nm is smaller than when both the left and right wheels 6 slip (the dashed line of the motor rotation speed in FIG. 6). Accordingly, the torque amount ΔT (base torque amount ΔTb) is smaller than when both the left and right wheels 6 slip. Therefore, the torque command value Ti is larger than when both the left and right wheels 6 slip (the dashed line of the torque command value in FIG. 6).

In addition, in the time chart of FIG. 6, at time t2, when the H/U 12 detects one-wheel slip (Nwr >> Nwl), slip suppression control is implemented to apply a first braking force F1 to the slipping wheel (right wheel 6R). As a result, the first braking force F1 is applied to the right wheel 6R, and the first control is implemented by the MCU 11, which has received a first signal from the H/U 12. By implementing the first control, the torque command Ti becomes a higher value [Ti = Tr - ΔT (= ΔTb - X)] than when the first control is not implemented (two-dot chain line for the torque command value in FIG. 6). This prevents excessive torque suppression of the left and right wheels 6 even when the traction control and the slip suppression control overlap.

Furthermore, when the ECU 10 receives a signal that traction control has started at time t2, the ECU 10 controls the engine 3 and the generator 4 so that the generated power P corresponds to the torque command value Ti. As a result, the generated power P gradually decreases from time t2 until it corresponds to the generated power P corresponding to the torque command value Ti. During this time, the battery voltage V rises due to the transfer of power that is not consumed by the electric motor 2, but when the battery 7's incoming power is high, there is a large margin for the battery voltage fluctuation associated with the power transfer, so the battery voltage V remains in a range lower than the upper limit voltage Vmax.

On the other hand, as shown in the time chart of Figure 7, the battery 7 has low incoming power and little room for battery voltage fluctuations associated with power transfer, so when the battery voltage V exceeds the upper limit voltage Vmax at time t3, the MCU 11 implements a third control to suppress the torque amount ΔT in addition to the first control being implemented. Therefore, the torque command value Ti becomes a higher value [Ti = Tr - ΔT (= ΔTb - X - Y)] than when the third control is not implemented while the first control is being implemented (the two-dot chain line for the torque command value in Figure 5). This increases the power consumed by the electric motor 2, suppressing the rise in the battery voltage V.

Furthermore, at time t3, when the H/U 12 receives the second braking force F2, in addition to the slip suppression control being performed, it performs battery protection control to apply the second braking force F2 to both the left wheel 6L and the right wheel 6R. As a result, the second braking force F2 is applied to the left wheel 6L and the right wheel 6R. In detail, the second braking force F2 is applied to the left wheel 6L, and a braking force equivalent to the sum of the first braking force F1 and the second braking force F2 is applied to the right wheel 6R. As a result, the motor torque (torque command value Ti) increased by the amount of torque amount ΔT suppressed in the third control is offset by the second braking force F2, thereby maintaining the stability of the vehicle 1.

In the time chart of Figure 7, when the ECU 10 receives a third signal from the MCU 11 indicating that the third control has started at time t3, the ECU 10 controls the engine 3 and the generator 4 to reduce the generated power P compared to when the third control is not performed while the first control is being performed (the two-dot chain line of the generated power in Figure 7). As a result, the battery voltage V applied to the battery 7 becomes even smaller after time t3, and the battery 7 is appropriately protected.

Although not shown, after time t2 in the time charts of Figures 6 and 7, when a predetermined suppression control end condition is met and slip suppression control by H/U 12 is no longer performed, MCU 11, which has received a second signal from H/U 12, performs a second control. By performing the second control, the torque command value Ti becomes a value [for example, Ti = Tr - ΔT (= ΔTb - X + X')] that is lower than when the first control is performed, by the amount of the torque amount that was suppressed and the second predetermined amount X' is added to it. As a result, after the end of the first control, slip-up of the left and right wheels 6 due to the loss of the first braking force F1 applied to one wheel by the slip suppression control is suppressed.

[6. Effects]
(1) According to the above-described vehicle 1, when the MCU 11 receives a first signal indicating that slip reduction control is being performed from the H/U 12, the MCU 11 adjusts to reduce the torque amount ΔT to be reduced by the traction control. As a result, when the traction control performed by the MCU 11 and the slip reduction control performed by the H/U 12 are both performed, it is possible to prevent excessive torque reduction for reducing slip of the left and right wheels 6 due to overlapping controls without interfering with each other.

Furthermore, when MCU 11 receives a second signal indicating that slip prevention control is not being performed after slip prevention control is performed by H/U 12, MCU 11 adjusts the torque amount ΔT that was suppressed so as to increase it. This makes it possible to suppress slip-up of the left and right wheels 6 by the amount of the loss of the first braking force F1. Therefore, according to the vehicle 1 described above, by adjusting the torque amount ΔT to be reduced by traction control in response to the first signal or the second signal received from H/U 12, it is possible to appropriately suppress slip of the left and right wheels 6 and improve the stability of the acceleration or starting of vehicle 1.

In addition, since the MCU 11 receives the first and second signals directly from the H/U 12 without going through the ECU 10, it is possible to reduce communication lag and improve control responsiveness. Therefore, according to the vehicle 1 described above, it is possible to appropriately suppress slippage of the left and right wheels 6 while taking advantage of the high responsiveness of the electric motor 2.

Furthermore, in the above embodiment, MCU 11 and H/U 12 are connected to be able to communicate with each other via a first bus 15 provided separately from CAN bus 14. This allows MCU 11 to instantly receive the first and second signals from H/U 12 regardless of the communication status within CAN bus 14, thereby further improving the responsiveness of control.

(2) H/U 12 determines whether or not slip suppression control should be performed based on the left wheel rotation speed Nwl and the right wheel rotation speed Nwr. In this way, the determination of whether or not slip suppression control should be performed is made in H/U 12. In other words, the determination of whether or not slip suppression control should be performed is made without going through ECU 10, thereby further improving the responsiveness of the control.

Furthermore, MCU11 corrects the torque amount ΔT based on the first braking force F1 received from H/U12. Specifically, when MCU11 receives the first signal, the torque amount ΔT is corrected so that the greater the first braking force F1, the more the torque amount ΔT reduced by traction control is suppressed. This makes it possible to prevent excessive or insufficient suppression of one-wheel slip, and therefore to appropriately suppress one-wheel slip. Furthermore, when MCU11 receives the second signal (at the end of slip suppression control), the torque amount ΔT is corrected so that it gradually increases as the first braking force F1 is gradually reduced. This makes it possible to suppress excessive slip suppression and slip-up during the reduction of the first braking force F1, and improves the stability of acceleration or starting of the vehicle 1.

(3) In addition, the MCU 11 suppresses the torque amount ΔT when the battery voltage V received from the BMU 13 exceeds a predetermined upper limit voltage Vmax. As a result, the power consumed by the electric motor 2 is increased (secured) compared to before the torque amount ΔT is suppressed, so that the increase in the battery voltage V can be suppressed. Furthermore, since the MCU 11 receives the battery voltage V directly from the BMU 13 without going through the ECU 10, the communication lag can be reduced and the control responsiveness can be improved. In particular, in the above-mentioned embodiment, the MCU 11 and the BMU 13 are communicatively connected by a second bus 16 separate from the CAN bus 14. Therefore, regardless of the communication status within the CAN bus 14, the MCU 11 can instantly receive the battery voltage V from the BMU 13, so that the control responsiveness can be further improved.

Furthermore, when the battery voltage V exceeds the upper limit voltage Vmax, the MCU 11 calculates a second braking force F2 that compensates for the suppressed torque amount ΔT and transmits it to the H/U 12. When the H/U 12 receives the second braking force F2 from the MCU 11, it operates the brake 9 and performs battery protection control to apply the second braking force F2 to both the left and right wheels 6. As a result, the motor torque corresponding to the suppressed torque amount ΔT is offset by the second braking force F2, thereby maintaining the stability of the vehicle 1.

(4) Furthermore, when both slip suppression control and battery protection control are performed by H/U12, the torque amount ΔT is corrected to a value (ΔT = ΔTb - X - Y) obtained by subtracting a first predetermined amount X set according to the first braking force F1 from the base torque amount ΔTb, and then subtracting a third predetermined amount Y corresponding to the second braking force F2. In other words, when H/U12 performs both slip suppression control and battery protection control, MCU11 corrects the torque amount ΔT based on both the first braking force F1 and the second braking force F2. Therefore, it is possible to both suppress one-wheel slip and protect the battery 7.

[7. Modifications]
The above-described configuration of the vehicle 1 and the control performed by the vehicle 1 are examples. As the first control, the MCU 11 may not only correct the torque amount ΔT based on the first braking force F1, but also calculate a corrected braking force F3 to be applied to one of the slipping wheels (the left wheel 6L or the right wheel 6R) based on the corrected torque amount ΔT, and transmit the calculated corrected braking force F3 to the H/U 12. At this time, the H/U 12 may control the brake 9 to apply the corrected braking force F3 received from the MCU 11 to one of the slipping wheels instead of the first braking force F1, as the implementation of the slip suppression control. In this way, by configuring the traction control performed by the MCU 11 to be fed back to the slip suppression control performed by the H/U 12, it is possible to more appropriately suppress one-wheel slip. Similarly, as a second control, the MCU 11 may calculate a corrected braking force F3 to be applied to one of the wheels (the left wheel 6L or the right wheel 6R) that is slipping based on the torque amount ΔT corrected based on the first braking force F1, and transmit the calculated corrected braking force F3 to the H/U 12.

In addition to implementing slip suppression control, the H/U 12 may also implement both-wheel slip suppression control, which applies braking force to both the left and right wheels 6 when both the left and right wheels 6 are slipping (both-wheel slip). As the both-wheel slip suppression control, for example, the MCU 11 may calculate the torque amount ΔT for reducing the motor torque when slippage of the vehicle 1 is detected (after step S4 in the flowchart of FIG. 3), and then calculate the auxiliary braking force to be requested of the H/U 12 to suppress the slippage, and transmit the calculated auxiliary braking force to the H/U 12. Then, when the H/U 12 receives this auxiliary braking force, it may apply the auxiliary braking force to both the left and right wheels 6. Note that this auxiliary braking force may be calculated as an upper limit value and a lower limit value of the braking force.

The definition of "implementation or non-implementation of the slip suppression control" in the claims is not limited to the above. For example, "implementation of slip suppression control" may include a period from the time when the suppression control end condition is satisfied to the time when the first braking force F1 applied to the slipping wheel (left wheel 6L or right wheel 6R) is gradually reduced to 0. In this case, the H/U 12 may continue to transmit the second signal indicating non-implementation of the slip suppression control from the time when the first braking force F1 becomes 0 to the time when the traction control is terminated or the time when the slip suppression control is resumed. The control for adjusting the torque amount ΔT during the implementation of the slip suppression control is not limited to the first control for adjusting the torque amount ΔT so as to suppress it, but may also be a control for adjusting the torque amount ΔT so as to increase it. Furthermore, the control for adjusting the torque amount ΔT during the non-implementation of the slip suppression control is not limited to the second control for adjusting the torque amount ΔT so as to increase it, but may also be a control for adjusting the torque amount ΔT so as to suppress it.

The electric vehicle may be a so-called EV vehicle that does not have an engine 3 and a generator 4. The electric vehicle may also be a so-called four-wheel drive vehicle that has a front motor that drives the left and right wheels (front wheels) at the front of the vehicle and a rear motor that drives the left and right wheels (rear wheels) at the rear of the vehicle. In the case of a four-wheel drive vehicle, the electric vehicle may have a separate MCU that controls the front motor and a separate MCU that controls the rear motor. The above-mentioned traction control and the first control and second control performed during the traction control may be performed separately for each of the front motor and the rear motor.

The brakes 9 may also brake the left and right wheels 6 at the front and the left and right wheels at the rear of the vehicle 1. The electric vehicle may also be provided with separate front brakes for braking the front wheels and separate rear brakes for braking the rear wheels. In this case, the electric vehicle may have separate H/Us for controlling the front brakes and H/Us for controlling the rear brakes. In this case, the above-mentioned slip suppression control and battery protection control may be performed separately for each of the front brakes and the rear brakes. The brake control device is not limited to the H/U, and various brake control devices can be applied.

1. Vehicles (electric vehicles)
2 Electric motor 6 Left and right wheels 6L Left wheel 6R Right wheel 7 Battery 9 Brake device 10 Upper control unit (ECU)
11 Motor control unit (MCU)
12 Brake control unit (H/U)
13 Battery Management Unit (BMU)
F1 First braking force F2 Second braking force (supplementary braking force)
F3 Corrected braking force Nm Motor rotation speed Nwl Left wheel rotation speed Nwr Right wheel rotation speed R Rotational acceleration Ti Torque command value (motor torque)
Tr Required torque V Battery voltage Vmax Upper limit voltage ΔT Torque amount

Claims (4)

An electric vehicle including an electric motor for driving left and right wheels and a brake for applying a braking force to the left and right wheels,
A host control device that calculates a required torque of the electric vehicle;
an electric motor control device that receives the required torque calculated by the higher-level control device to control the electric motor and performs traction control to reduce the torque of the electric motor based on the rotational acceleration of the electric motor;
a brake control device that performs slip suppression control by actuating the brake to apply a braking force to one of the left and right wheels when slip of the one of the left and right wheels is detected;
a battery management device that acquires a battery voltage of a battery that exchanges electric power with the electric motor;
when receiving a signal indicating execution of the slip suppression control or non-execution after the execution from the brake control device, the motor control device adjusts an amount of torque to be reduced by the traction control in response to the received signal,
When the battery voltage received from the battery management device without going through the higher-level control device exceeds a predetermined upper limit voltage, the electric motor control device reduces an amount of torque to be reduced by the traction control, calculates a compensation braking force to compensate for the amount of torque reduced by the traction control, and transmits the compensation braking force to the brake control device;
When the brake control device receives the supplementary braking force from the electric motor control device, the brake control device operates the brake to perform battery protection control to apply the supplementary braking force to both the left and right wheels.
An electric vehicle characterized by: the brake control device determines whether or not the slip suppression control should be performed based on the rotation speeds of the left and right wheels, and transmits a braking force to be applied to the one wheel together with the signal to the electric motor control device;
2. The electric vehicle according to claim 1, wherein the electric motor control device corrects the torque amount based on the braking force received from the brake control device. the electric motor control device calculates a corrected braking force to be applied to the one wheel based on the corrected torque amount, and transmits the corrected braking force to the brake control device;
3. The electric vehicle according to claim 2, wherein the brake control device applies the corrective braking force received from the electric motor control device to the one wheel . The electric vehicle according to any one of claims 1 to 3, characterized in that, when the brake control device performs both the slip suppression control and the battery protection control, the motor control device corrects the torque amount based on the braking force applied to one of the wheels by the slip suppression control and the braking forces applied to both the left and right wheels by the battery protection control.

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