JP7389673B2 - Electric vehicle control device - Google Patents

Description

The present invention relates to a control device for an electric vehicle.

In order to support the driver's driving operations, in addition to the normal mode that controls the vehicle's acceleration/deceleration according to the driver's acceleration/deceleration operations (i.e., accelerator and brake operations), the vehicle speed is controlled independently of the driver's acceleration/deceleration operations. There is a vehicle that can execute a cruise control mode that maintains the vehicle speed at a target vehicle speed (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2008-221935

By the way, in a vehicle equipped with a drive motor as a drive source, the torque of the drive motor is controlled to be below an upper limit value. Then, the upper limit value of the torque is adjusted according to the temperature of the drive motor, etc., and the torque that the drive motor can output is limited. Here, in a hybrid vehicle (HEV) equipped with an engine in addition to a drive motor as a drive source, if the cruise control mode is executed under a situation where the output torque of the drive motor is excessively limited, the drive The engine can compensate for the lack of torque from the motor.

On the other hand, in an electric vehicle (EV) equipped with only a drive motor as a drive source, when the cruise control mode is executed under a situation where the output torque of the drive motor is excessively limited, the drive motor's torque (Specifically, the torque that accelerates the vehicle or the torque that decelerates the vehicle by regenerative braking) is insufficient with respect to the required value, which may cause the vehicle behavior to become unstable. For example, there is a risk that the vehicle will slide backwards due to insufficient torque to accelerate the vehicle while climbing a hill, and there is a risk that the vehicle will accelerate excessively due to insufficient torque to decelerate the vehicle due to regenerative braking while descending a hill. There is. In particular, the lower the target vehicle speed in cruise control mode, the more it is assumed that the vehicle will be driven on rough roads with severe ups and downs (e.g., rocky areas on riverbeds) and steep slopes. Accordingly, the torque that the drive motor can output tends to be limited, and the required torque value of the drive motor tends to increase. Therefore, the vehicle behavior tends to become unstable due to the limitation of the torque of the drive motor.

SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide a control device for an electric vehicle that can suppress instability of vehicle behavior due to limitations on the torque of the drive motor. It is said that

In order to solve the above problems, a control device for an electric vehicle according to the present invention includes a control unit that controls the operation of a drive motor that outputs driving force for the electric vehicle, and the control unit responds to acceleration and deceleration operations by the driver. It is executed by switching between a normal mode in which the electric vehicle's acceleration/deceleration is controlled by the driver, and a cruise control mode in which the electric vehicle's speed is maintained at the target speed by controlling the torque of the drive motor without the driver's acceleration/deceleration operations. The cruise control mode can be executed by switching between a high-speed cruise control mode and a low-speed cruise control mode in which a target vehicle speed lower than the target vehicle speed of the high-speed cruise control mode is used, and the upper limit of the torque of the drive motor can be executed. If the value is below the threshold, transition to low speed cruise control mode is prohibited.

The threshold value may be set to a value corresponding to the maximum value of the required torque value of the drive motor during execution of the low-speed cruise control mode.

If the upper limit value falls below the threshold value during execution of the low-speed cruise control mode, the control unit may continue the low -speed cruise control mode until the driver performs an input operation to stop the low-speed cruise control mode.

When prohibiting the transition to the low-speed cruise control mode, the control unit may cause the notification device to issue a notification indicating that the transition to the low-speed cruise control mode is prohibited.

The control unit may change the threshold value based on information regarding the travel route.

The information regarding the running route may include information indicating the slope of the running route.

The information regarding the traveling route may include information indicating the type of traveling route.

According to the present invention, it is possible to suppress vehicle behavior from becoming unstable due to the limitation of the torque of the drive motor.

1 is a schematic diagram showing a schematic configuration of a vehicle in which a control device according to an embodiment of the present invention is mounted. 1 is a block diagram showing an example of a functional configuration of a control device according to an embodiment of the present invention. 2 is a flowchart illustrating an example of the flow of processing regarding prohibition and permission of transition to low-speed cruise control mode performed by the control unit of the control device according to the embodiment of the present invention. FIG. 3 is a diagram showing an example of changes in various state quantities while the vehicle according to the embodiment of the present invention is traveling.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in these embodiments are merely illustrative to facilitate understanding of the invention, and do not limit the invention unless otherwise specified. In this specification and the drawings, elements with substantially the same functions and configurations are given the same reference numerals to omit redundant explanation, and elements not directly related to the present invention are omitted from illustration. do.

<Vehicle configuration>
The configuration of a vehicle 1 in which a control device 100 according to an embodiment of the present invention is mounted will be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle 1. As shown in FIG. In FIG. 1, the forward direction of the vehicle 1 is referred to as the forward direction, the reverse direction opposite to the forward direction is referred to as the rear direction, and the left and right sides of the vehicle 1 when facing forward are referred to as the left and right directions, respectively. It is shown.

The vehicle 1 includes a drive motor (specifically, a front wheel drive motor 15f and a rear wheel drive motor 15r in FIG. 1) as a drive source, and runs using the power output from the drive motor. It is an electric vehicle.

Note that the vehicle 1 described below is merely an example of a vehicle in which the control device according to the present invention is installed, and as described later, the configuration of the vehicle in which the control device according to the present invention is installed is the same as the configuration of the vehicle 1. Not particularly limited to.

As shown in FIG. 1, the vehicle 1 includes front wheels 11a and 11b, rear wheels 11c and 11d, a front differential device 13f, a rear differential device 13r, a front wheel drive motor 15f, and a rear wheel drive motor 15r. , inverter 17f, inverter 17r, battery 19, display device 21, control device 100, accelerator opening sensor 201, brake sensor 203, front wheel motor rotation speed sensor 205f, and rear wheel motor rotation speed sensor. 205r. The display device 21 corresponds to an example of a notification device according to the present invention that notifies the driver of information.

Hereinafter, when the front wheel 11a, the front wheel 11b, the rear wheel 11c, and the rear wheel 11d are not distinguished from each other, they are also simply referred to as wheels 11. Moreover, when the front wheel drive motor 15f and the rear wheel drive motor 15r are not distinguished, they are also simply referred to as the drive motor 15. Further, when the inverter 17f and the inverter 17r are not distinguished from each other, they are also simply referred to as the inverter 17. Further, if the front wheel motor rotation speed sensor 205f and the rear wheel motor rotation speed sensor 205r are not distinguished from each other, they are also simply referred to as the motor rotation speed sensor 205.

The front wheel drive motor 15f is a drive motor that outputs power to drive the front wheels 11a and 11b. Note that the front wheel 11a corresponds to the left front wheel, and the front wheel 11b corresponds to the right front wheel.

Specifically, the front wheel drive motor 15f is driven using electric power supplied from the battery 19. The front wheel drive motor 15f is connected to a front differential device 13f. The front differential device 13f is connected to the front wheels 11a and 11b via drive shafts, respectively. The power output from the front wheel drive motor 15f is transmitted to the front differential device 13f, and then distributed and transmitted to the front wheels 11a and 11b by the front differential device 13f.

The front wheel drive motor 15f is, for example, a polyphase AC motor, and is connected to the battery 19 via an inverter 17f. The DC power supplied from the battery 19 is converted into AC power by the inverter 17f, and is supplied to the front wheel drive motor 15f.

In addition to the function of outputting power for driving the front wheels 11a and 11b, the front wheel drive motor 15f also has a function as a generator that generates electricity using the kinetic energy of the front wheels 11a and 11b. When the front wheel drive motor 15f functions as a generator, the front wheel drive motor 15f generates electricity and applies braking force to the vehicle 1 through regenerative braking. The AC power generated by the front wheel drive motor 15f is converted to DC power by the inverter 17f, and is supplied to the battery 19. Thereby, the battery 19 is charged.

The rear wheel drive motor 15r is a drive motor that outputs power to drive the rear wheels 11c and 11d. Note that the rear wheel 11c corresponds to the left rear wheel, and the rear wheel 11d corresponds to the right rear wheel.

Specifically, the rear wheel drive motor 15r is driven using electric power supplied from the battery 19. The rear wheel drive motor 15r is connected to a rear differential device 13r. The rear differential device 13r is connected to the rear wheels 11c and 11d via drive shafts, respectively. The power output from the rear wheel drive motor 15r is transmitted to the rear differential device 13r, and then distributed and transmitted to the rear wheels 11c and 11d by the rear differential device 13r.

The rear wheel drive motor 15r is, for example, a polyphase AC motor, and is connected to the battery 19 via an inverter 17r. The DC power supplied from the battery 19 is converted into AC power by the inverter 17r, and is supplied to the rear wheel drive motor 15r.

In addition to the function of outputting power for driving the rear wheels 11c and 11d, the rear wheel drive motor 15r also functions as a generator that generates electricity using the kinetic energy of the rear wheels 11c and 11d. When the rear wheel drive motor 15r functions as a generator, the rear wheel drive motor 15r generates electricity and applies braking force to the vehicle 1 through regenerative braking. The AC power generated by the rear wheel drive motor 15r is converted to DC power by the inverter 17r, and is supplied to the battery 19. Thereby, the battery 19 is charged.

The display device 21 is a device that visually displays information, and is, for example, a liquid crystal display or a lamp. Note that the display device 21 may be any other device other than the above as long as it has a function of visually displaying information; for example, it may be a device that displays an image on the windshield of the vehicle 1. You can.

The accelerator opening sensor 201 detects the accelerator opening, which is the amount of operation of the accelerator pedal by the driver, and outputs the detection result.

The brake sensor 203 detects the amount of brake operation, which is the amount of operation of the brake pedal by the driver, and outputs the detection result.

The front wheel motor rotation speed sensor 205f detects the rotation speed of the front wheel drive motor 15f and outputs the detection result. The rear wheel motor rotation speed sensor 205r detects the rotation speed of the rear wheel drive motor 15r and outputs the detection result. The detection result of the motor rotation speed sensor 205 determines whether the power transmission shaft of the vehicle 1 (specifically, the shaft included in the power transmission system between the drive motor 15 and the wheels 11) is detected in the process performed by the control device 100. It is used as information indicating the number of rotations.

The control device 100 includes a CPU (Central Processing Unit) that is an arithmetic processing unit, a ROM (Read Only Memory) that is a storage element that stores programs used by the CPU, calculation parameters, etc., and parameters that change as appropriate during execution of the CPU. It includes a RAM (Random Access Memory), which is a storage element that temporarily stores information such as RAM.

The control device 100 communicates with each device mounted on the vehicle 1 (for example, the inverter 17, the display device 21, the accelerator opening sensor 201, the brake sensor 203, the motor rotation speed sensor 205, etc.). Communication between the control device 100 and each device is realized using, for example, CAN (Controller Area Network) communication.

FIG. 2 is a block diagram showing an example of the functional configuration of the control device 100.

For example, as shown in FIG. 2, the control device 100 includes a specifying section 110 and a control section 120.

The identification unit 110 identifies the vehicle speed of the vehicle 1 (hereinafter also simply referred to as vehicle speed) based on the rotational speed of the power transmission shaft of the vehicle 1. Information indicating the vehicle speed specified by the specifying section 110 is output to the control section 120 and used for processing performed by the control section 120.

Specifically, the identifying unit 110 identifies the vehicle speed based on the detection result of the motor rotation speed sensor 205. Note that in identifying the vehicle speed, the detection results of both the front wheel motor rotation speed sensor 205f and the rear wheel motor rotation speed sensor 205r may be used, or only one of the front wheel motor rotation speed sensor 205f and the rear wheel motor rotation speed sensor 205r is used. The detection results may be used. In determining the vehicle speed, information other than the detection result of the motor rotation speed sensor 205 (for example, the rotation speed of the drive shaft connecting the wheels 11 and the differential device) is used as information indicating the rotation speed of the power transmission shaft of the vehicle 1. information shown) may be used.

The control unit 120 controls the running of the vehicle 1 by controlling the operation of each device within the vehicle 1. For example, the control unit 120 includes a determination unit 121, a motor control unit 122, and a notification control unit 123.

The determination unit 121 performs various determinations using information transmitted from each device in the vehicle 1 to the control device 100. The determination result by the determination unit 121 is used for various processes performed by the control unit 120.

The motor control unit 122 controls the operation of each drive motor 15 by controlling the operation of each inverter 17 . Specifically, the motor control unit 122 controls the supply of electric power between the battery 19 and the front wheel drive motor 15f by controlling the operation of the switching element of the inverter 17f. Thereby, the motor control unit 122 can control the generation and power generation of power by the front wheel drive motor 15f. Further, the motor control unit 122 controls the supply of electric power between the battery 19 and the rear wheel drive motor 15r by controlling the operation of the switching element of the inverter 17r. Thereby, the motor control unit 122 can control the generation and power generation of power by the rear wheel drive motor 15r.

Note that when driving the drive motor 15 to provide driving force to the vehicle 1, the motor control unit 122 may drive both the front wheel drive motor 15f and the rear wheel drive motor 15r, Only one of the rear wheel drive motor 15f and the rear wheel drive motor 15r may be driven. The distribution of the driving force of each drive motor 15 when both the front wheel drive motor 15f and the rear wheel drive motor 15r are driven can be set as appropriate. Hereinafter, the torque of the drive motor 15 means the total value of the torques of the front wheel drive motor 15f and the rear wheel drive motor 15r.

The notification control unit 123 controls notification of information to the driver by controlling the operation of a notification device (for example, the display device 21). Specifically, the notification control unit 123 switches the display device 21 between a display state and a non-display state, or controls the content displayed by the display device 21. , to notify the driver of desired information. Note that, as described above, the display device 21 is an example of a notification device, and other notification devices (for example, a sound output device, etc.) other than the display device 21 may be used as the notification device, and multiple notification devices may be used. A device may be used.

Here, the control unit 120 can switch and execute the driving mode of the vehicle 1 between a normal mode and a cruise control mode. The normal mode is a driving mode in which the acceleration/deceleration of the vehicle 1 is controlled according to acceleration/deceleration operations (that is, accelerator operations and brake operations) by the driver. The cruise control mode is a driving mode in which the vehicle speed is maintained at the target vehicle speed by controlling the torque of the drive motor 15 without relying on acceleration/deceleration operations by the driver.

Further, the control unit 120 can switch and execute the cruise control mode between a high speed cruise control mode and a low speed cruise control mode. In the low-speed cruise control mode, a target vehicle speed lower than the target vehicle speed in the high-speed cruise control mode is used. For example, the target vehicle speed for high-speed cruise control mode is set to a speed within a range of 20 km/h to 115 km/h, and the target vehicle speed for low-speed cruise control mode is set to a speed within a range of 2 km/h to 15 km/h. is set to The target vehicle speed in the cruise control mode can be adjusted by, for example, an input operation by the driver.

For example, the vehicle 1 is provided with an input device (for example, a switch or a button) for selecting which driving mode to execute: normal mode, high-speed cruise control mode, and low-speed cruise control mode. The driver can select a driving mode by operating the input device. The control unit 120 executes the driving mode selected by the driver. Note that when the driver performs a specific operation such as a brake operation while the cruise control mode is being executed, the control unit 120 stops the cruise control mode and switches to the normal mode.

In the normal mode, the control unit 120 controls the operation of the drive motor 15 so that the driving force applied to the vehicle 1 corresponds to the accelerator opening. Thereby, the acceleration of the vehicle 1 can be controlled according to the driver's accelerator operation. Further, the control unit 120 controls the operation of a brake device such as a hydraulic brake device mounted on the vehicle 1 so that the braking force applied to the vehicle 1 is a braking force corresponding to the amount of brake operation. . Thereby, the deceleration of the vehicle 1 can be controlled in accordance with the brake operation by the driver.

In the cruise control mode, the control unit 120 calculates a torque command value for the drive motor 15 so that the vehicle speed approaches the target vehicle speed, and basically controls the torque of the drive motor 15 to the torque command value. For example, the control unit 120 controls the torque of the drive motor 15 using feedforward control based on the vehicle speed and feedback control (for example, PID control) based on the deviation between the vehicle speed and the target vehicle speed, and drives the torque. A torque command value for commanding the motor 15 is calculated. In this case, the calculated torque command value Tc is expressed, for example, by the following equation (1).

Tc=Tf+Tp+Ti+Td...(1)

In equation (1), Tf represents the torque of the feedforward control component based on the vehicle speed, Tp represents the torque of the proportional control component (that is, the P component) based on the deviation between the vehicle speed and the target vehicle speed, and Ti represents the torque of the integral control component (that is, the I component) based on the above deviation, and Td represents the torque of the differential control component (that is, the D component) that is based on the above deviation. Specifically, the P component torque Tp is obtained by multiplying the above deviation by a gain. Specifically, the I-component torque Ti is obtained by multiplying the integral value of the deviation by a gain. Specifically, the D component torque Td is obtained by multiplying the differential value of the deviation by a gain. The torque Tf, which is a component of the feedforward control, corresponds to the torque estimated to be necessary to maintain the vehicle speed at the target vehicle speed when the vehicle 1 is traveling on a flat road. Note that a flat road means a running road where the absolute value of the slope (that is, the slope with respect to the horizontal direction in the traveling direction of the vehicle 1) is equal to or less than a predetermined value.

Note that the method for calculating the torque command value Tc of the drive motor 15 is not limited to the example in which it is calculated using equation (1). For example, the feedforward control may be omitted from the above example (that is, the torque Tf may be omitted from equation (1)), and the PID control may be replaced with PI control (that is, the torque Tf may be omitted from equation (1)). ), the torque Td may be omitted from ).

As described above, in the cruise control mode, the control unit 120 basically controls the torque of the drive motor 15 to the torque command value Tc. However, the control unit 120 may control the torque of the drive motor 15 to a value different from the torque command value Tc. Specifically, the control unit 120 controls the torque of the drive motor 15 to be below the upper limit value. In addition, below, the upper limit value of the torque of the drive motor 15 is also called a torque upper limit value. When the torque command value Tc exceeds the torque upper limit value, the control unit 120 controls the torque of the drive motor 15 to the torque upper limit value.

The torque upper limit value is determined by the control unit 120 according to various parameters (for example, the temperature of the drive motor 15, the temperature of the inverter 17, the temperature of the battery 19, or the remaining capacity (SOC: State of Charge) of the battery 19). be adjusted. For example, when the temperature of the drive motor 15, inverter 17, or battery 19 exceeds the reference temperature while the temperature of the drive motor 15, inverter 17, or battery 19 increases, the control unit 120 decreases the torque upper limit value as the temperature increases. For example, when the SOC of the battery 19 falls below the reference SOC in the process of decreasing the SOC, the control unit 120 decreases the torque upper limit value as the SOC decreases. Note that the above reference temperature, reference SOC, temperature at which the output of the drive motor 15 is prohibited (that is, the temperature at which the torque upper limit value becomes 0), and SOC at which the output of the drive motor 15 is prohibited (that is, The SOC at which the upper limit torque value is 0 can be appropriately set according to the specifications of each device such as the drive motor 15, inverter 17, or battery 19.

Note that the functions of the control device 100 according to this embodiment may be partially divided by a plurality of control devices, or the plurality of functions may be realized by one control device. When the functions of the control device 100 are partially divided into a plurality of control devices, the plurality of control devices may be connected to each other via a communication bus such as CAN.

As described above, the control unit 120 of the control device 100 can execute the cruise control mode in which the vehicle speed of the vehicle 1 is maintained at the target vehicle speed by controlling the torque of the drive motor 15 without depending on acceleration/deceleration operations by the driver. It is. Here, the control unit 120 prohibits transition to the cruise control mode when the torque upper limit value is less than the threshold value. Thereby, it is possible to prevent the cruise control mode from being executed in a situation where the torque that can be output by the drive motor 15 is excessively limited. Therefore, it is possible to prevent the vehicle behavior from becoming unstable due to the limitation of the torque of the drive motor 15. Note that the details of the process performed by the control unit 120 regarding prohibition and permission of transition to the cruise control mode will be described later.

<Operation of control device>
Next, the operation of the control device 100 according to the embodiment of the present invention will be described with reference to FIGS. 3 and 4.

As described above, by prohibiting the transition to the cruise control mode when the torque upper limit value is less than the threshold value, instability of vehicle behavior due to the limitation of the torque of the drive motor 15 is suppressed. be done.

Here, as the target vehicle speed in the cruise control mode is lower, it is assumed that the vehicle will be driven more often on rough roads with severe ups and downs (for example, rocky areas on riverbeds) and steep slopes, so the temperature of the drive motor 15 will increase. As a result, the torque that can be output by the drive motor 15 tends to be limited, and the required torque value of the drive motor 15 tends to increase. As a result, the vehicle behavior tends to become unstable due to the limitation of the torque of the drive motor 15. Therefore, in the low-speed cruise control mode, compared to the high-speed cruise control mode, there is a particularly high need to suppress instability of vehicle behavior due to the limitation of the torque of the drive motor 15. Therefore, it is preferable that the control unit 120 prohibits transition to the low-speed cruise control mode when the torque upper limit value is less than the threshold value.

Although an example will be described below in which processing regarding prohibition and permission of transition to low-speed cruise control mode is performed, control unit 120 may also perform processing regarding prohibition and permission of transition to high-speed cruise control mode. For example, the low-speed cruise control mode being processed, which will be described below, may be replaced with a high-speed cruise control mode.

FIG. 3 is a flowchart illustrating an example of the flow of processing regarding prohibition and permission of transition to the low-speed cruise control mode, which is performed by the control unit 120 of the control device 100. Specifically, the control flow shown in FIG. 3 is started in a state where transition to the low-speed cruise control mode is permitted, and is repeatedly executed.

FIG. 4 is a diagram showing an example of changes in various state quantities while the vehicle 1 is traveling. Specifically, in FIG. 4, as various state quantities, the operation state of the low-speed cruise control mode (low-speed CC mode), the execution state of the low-speed cruise control mode (low-speed CC mode), and the low-speed cruise control mode (low-speed A transition prohibition flag to CC mode) is shown.

The low-speed cruise control mode switch is an input device used by the driver to perform an operation for switching between a state where the low-speed cruise control mode is being executed and a state where the mode is stopped. A series of operations of pressing and releasing the low-speed cruise control mode switch corresponds to an operation of switching between a state in which the low-speed cruise control mode is being executed and a state in which the mode is stopped. In FIG. 4, a state in which the low-speed cruise control mode switch is pressed corresponds to ON, and a state in which the low-speed cruise control mode switch is released corresponds to OFF.

Regarding the execution state of the low-speed cruise control mode, in FIG. 4, the state where the low-speed cruise control mode is executed (that is, the state where the driving mode is the low-speed cruise control mode) corresponds to ON, and the low-speed cruise control mode is A state in which the vehicle is stopped (that is, a state in which the driving mode is a driving mode other than the low-speed cruise control mode) corresponds to OFF.

The transition prohibition flag to low-speed cruise control mode becomes 1 when transition to low-speed cruise control mode is prohibited, and becomes 0 when transition to low-speed cruise control mode is permitted. The transition prohibition flag to low-speed cruise control mode is stored, for example, in a storage element of the control device 100, and is rewritten by the control unit 120.

Hereinafter, each process of the control flow shown in FIG. 3 will be explained with reference to FIG. 4 as appropriate.

Note that in FIG. 3, a part of the process related to switching the driving mode is omitted, but while the determination in step S101 continues to be NO, or while the determination in step S107 continues to be NO, the driving mode is not changed. When the driver performs an input operation to select a mode, the control unit 120 switches the driving mode to the driving mode selected by the driver.

When the control flow shown in FIG. 3 is started, first, in step S101, the determination unit 121 determines whether the torque upper limit value of the drive motor 15 has fallen below a threshold value. If it is determined that the torque upper limit value is less than the threshold value (step S101/YES), the process proceeds to step S102, and the control unit 120 prohibits transition to the low-speed cruise control mode. On the other hand, if it is determined that the torque upper limit value is not below the threshold value (step S101/NO), the determination process of step S101 is repeated.

For example, the threshold value is set to a value corresponding to the maximum value of the required torque value of the drive motor 15 that is assumed to occur during execution of the low-speed cruise control mode (for example, a value comparable to the maximum value). In other words, when the upper limit of the torque of the drive motor 15 is below the threshold, the torque of the drive motor 15 (specifically, the torque that accelerates the vehicle or the torque that decelerates the vehicle by regenerative braking) is There is a possibility that the required value will be insufficient. In this embodiment, in such a case, transition to low-speed cruise control mode is prohibited.

In the example shown in FIG. 4, the low-speed cruise control mode is stopped before time T1. Furthermore, before time T1, the torque upper limit value is greater than or equal to the threshold value, and a transition to the low-speed cruise control mode is permitted. Therefore, the transition prohibition flag to low-speed cruise control mode is set to 0. Then, at time T1, the low-speed cruise control mode switch is pressed, and the driving mode is switched to the low-speed cruise control mode. Thereafter, at time T2, as the torque upper limit value falls below the threshold value, transition to the low-speed cruise control mode is prohibited. As a result, the transition prohibition flag to low-speed cruise control mode is switched from 0 to 1.

As will be described later, in the control flow shown in FIG. 3, if the torque upper limit value falls below the threshold while the low-speed cruise control mode is being executed, the process will continue until the driver performs an input operation to stop the low-speed cruise control mode. During this time, low-speed cruise control mode continues. Therefore, in the example shown in FIG. 4, the low-speed cruise control mode continues after time T2.

As described above, in the control flow shown in FIG. 3, the condition for prohibiting transition to the low-speed cruise control mode is that the torque upper limit value is less than the threshold value. Therefore, by changing the threshold value, it is possible to change the ease with which transition to the low-speed cruise control mode is prohibited. Here, it is preferable that the control unit 120 changes the threshold value based on information regarding the driving route. Thereby, the ease with which transition to the low-speed cruise control mode is inhibited can be changed based on information regarding the travel route.

The information regarding the running route may include information indicating the gradient of the running route. It is assumed that the greater the absolute value of the slope of the traveling road, the greater the required value of the torque of the drive motor 15 during execution of the low-speed cruise control mode. Therefore, the control unit 120 may increase the threshold value so that the transition to the low-speed cruise control mode is more likely to be inhibited, for example, as the absolute value of the slope of the road increases.

Further, the information regarding the traveling route may include information indicating the type of traveling route. It is assumed that the magnitude of the required torque value of the drive motor 15 during execution of the low-speed cruise control mode differs depending on the type of travel road. Therefore, the control unit 120 can control that, for example, when the traveling road is a rough road with severe ups and downs such as a rocky area on a riverbed, the required value of the torque of the drive motor 15 is larger than when the traveling road is a paved road. Therefore, by increasing the threshold value, the transition to the low-speed cruise control mode may be more likely to be prohibited.

In step S103 following step S102 in FIG. 3, the control unit 120 causes the display device 21 to issue a notification indicating that transition to the low-speed cruise control mode is prohibited.

For example, as the notification in step S103, the control unit 120 causes the display device 21 to display an object such as letters, figures, symbols, or a combination thereof indicating that transition to the low-speed cruise control mode is prohibited. In the example shown in FIG. 4, the display device 21 provides notification at time T2. Note that the notification by the display device 21 may end when a set time has elapsed from time T2, and continues until transition to low-speed cruise control mode is permitted (specifically, until time T5, which will be described later). You may.

After step S103 in FIG. 3, in step S104, the determination unit 121 determines whether the low-speed cruise control mode is being executed. If it is determined that the low-speed cruise control mode is being executed (step S104/YES), the process advances to determination processing in step S105. On the other hand, if it is determined that the low-speed cruise control mode is not being executed (that is, it is stopped) (step S104/NO), the process proceeds to the determination process of step S107.

If the determination in step S104 in FIG. 3 is YES, in step S105, the determination unit 121 determines whether the driver has performed an input operation to stop the low-speed cruise control mode. If it is determined that an input operation to stop the low-speed cruise control mode has been performed (step S105/YES), the process proceeds to step S106, and the control unit 120 stops the low-speed cruise control mode. On the other hand, if it is determined that the input operation to stop the low-speed cruise control mode has not been performed (step S105/NO), the determination process of step S105 is repeated.

In the example shown in FIG. 4, the low-speed cruise control mode is being executed at time T2 when the torque upper limit value is less than the threshold value and the transition prohibition flag to low-speed cruise control mode is switched from 0 to 1. In this step, the determination process in step S105 in FIG. 3 is repeated. Then, at time T3 after time T2, the low-speed cruise control mode switch is pressed, and the determination unit 121 determines that the driver has performed an input operation to stop the low-speed cruise control mode. Therefore, at time T3, the low-speed cruise control mode is stopped. In the example shown in FIG. 4, the low-speed cruise control mode switch is pressed at time T4 after time T3. This operation was performed by the driver as an input operation to execute the low-speed cruise control mode, but since transition to the low-speed cruise control mode is prohibited, the low-speed cruise control mode will stop after time T4. The current state will be maintained.

Next to step S106 in FIG. 3, or when the determination is NO in step S104, in step S107, the determination unit 121 determines whether the torque upper limit value of the drive motor 15 exceeds a threshold value. . If it is determined that the torque upper limit value exceeds the threshold value (step S107/YES), the process proceeds to step S108, where the control unit 120 allows transition to the low-speed cruise control mode, and the control flow shown in FIG. 3 ends. . On the other hand, if it is determined that the torque upper limit value does not exceed the threshold value (step S107/NO), the determination process of step S107 is repeated.

In the example shown in FIG. 4, at time T5 after time T4, the torque upper limit value exceeds the threshold value, and a transition to the low-speed cruise control mode is permitted. As a result, the transition prohibition flag to low-speed cruise control mode is switched from 1 to 0. Thereafter, at time T6, the low-speed cruise control mode switch is pressed. This operation is an operation performed by the driver as an input operation to execute the low-speed cruise control mode. At time T6, unlike time T4, transition to low-speed cruise control mode is permitted, so the driving mode is switched to low-speed cruise control mode.

<Effects of control device>
Next, the effects of the control device 100 according to the embodiment of the present invention will be explained.

In the control device 100 according to the present embodiment, the control unit 120 prohibits transition to the cruise control mode when the upper limit value of the torque of the drive motor 15 (that is, the upper limit torque value) is less than the threshold value. Thereby, it is possible to prevent the cruise control mode from being executed in a situation where the torque that can be output by the drive motor 15 is excessively limited. Therefore, it is possible to prevent the vehicle behavior from becoming unstable due to the limitation of the torque of the drive motor 15. For example, a lack of torque to accelerate the vehicle 1 while climbing a slope may cause the vehicle to slide down, or a lack of torque to decelerate the vehicle 1 due to regenerative braking while descending a slope may cause the vehicle 1 to accelerate excessively. It is possible to prevent this from happening.

Further, in the control device 100 according to the present embodiment, the threshold value is preferably set to a value corresponding to the maximum value of the requested torque value of the drive motor 15 during execution of the cruise control mode. Thereby, in a situation where there is a possibility that the torque of the drive motor 15 is insufficient for the required value when the cruise control mode is executed, it is possible to appropriately prevent the cruise control mode from being executed. . Therefore, it is possible to appropriately suppress the vehicle behavior from becoming unstable due to the limitation of the torque of the drive motor 15.

In addition, in the control device 100 according to the present embodiment, when the torque upper limit value falls below the threshold while the cruise control mode is being executed, the control unit 120 controls the , it is preferable to continue the cruise control mode. Thereby, it is possible to prevent the cruise control mode from stopping at a timing unintended by the driver during execution of the cruise control mode. Therefore, if the cruise control mode suddenly stops without the driver performing acceleration/deceleration operations, the vehicle behavior may become unstable (for example, the vehicle 1 may slide down while climbing a slope, Excessive acceleration of the vehicle 1 while descending a slope can be suppressed.

In addition, in the control device 100 according to the present embodiment, when prohibiting the transition to the cruise control mode, the control unit 120 sends a notification to the notification device (for example, the display device 21) indicating that the transition to the cruise control mode is prohibited. ) is preferably executed. Thereby, the driver can be made aware that the transition to the cruise control mode is intentionally prohibited by the control device 100.

Further, in the control device 100 according to the present embodiment, the control unit 120 preferably changes the threshold value based on information regarding the travel route. Thereby, the ease with which transition to cruise control mode is inhibited can be changed based on information regarding the travel route. Therefore, it is possible to appropriately suppress the vehicle behavior from becoming unstable due to the limitation of the torque of the drive motor 15 depending on the traveling route.

Further, in the control device 100 according to the present embodiment, it is preferable that the information regarding the running path includes information indicating the gradient of the running path. Thereby, the ease with which transition to the cruise control mode is inhibited can be changed depending on the slope of the travel road. Therefore, it is possible to more appropriately suppress vehicle behavior from becoming unstable due to the limitation of the torque of the drive motor 15 depending on the traveling route.

Further, in the control device 100 according to the present embodiment, it is preferable that the information regarding the traveling route includes information indicating the type of traveling route. Thereby, the ease with which transition to the cruise control mode is inhibited can be changed depending on the type of road the vehicle is traveling on. Therefore, it is possible to more appropriately suppress vehicle behavior from becoming unstable due to the limitation of the torque of the drive motor 15 depending on the traveling route.

Further, in the control device 100 according to the present embodiment, it is preferable to prohibit transition to the low-speed cruise control mode when the torque upper limit value is less than a threshold value. As described above, in the low-speed cruise control mode, the target vehicle speed is lower than in the high-speed cruise control mode, so it is necessary to suppress instability of vehicle behavior due to the limitation of the torque of the drive motor 15. is particularly high. Therefore, by prohibiting the transition to the low-speed cruise control mode when the torque upper limit value is below the threshold value, the effect of suppressing the instability of vehicle behavior due to the limitation of the torque of the drive motor 15 is achieved. can be used effectively.

Although preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications within the scope of the claims are possible. It goes without saying that modifications and modifications also fall within the technical scope of the present invention.

For example, in the above description, the vehicle 1 is an electric vehicle that includes the front wheel drive motor 15f and the rear wheel drive motor 15r as drive sources. Not particularly limited. For example, a vehicle equipped with the control device according to the present invention may be an electric vehicle in which each wheel is provided with a different drive motor (that is, four drive motors are provided). Further, for example, a vehicle in which the control device according to the present invention is installed may be a vehicle in which components are added, changed, or deleted from the vehicle 1 described with reference to FIG. 1.

Further, for example, the processes described using flowcharts in this specification do not necessarily need to be executed in the order shown in the flowcharts. Also, additional processing steps may be employed or some processing steps may be omitted.

INDUSTRIAL APPLICATION This invention can be utilized for the control apparatus of an electric vehicle.

1 Vehicle (electric vehicle)
11a, 11b Front wheels 11c, 11d Rear wheels 13f Front differential device 13r Rear differential device 15f Front wheel drive motor (drive motor)
15r Rear wheel drive motor (drive motor)
17f Inverter 17r Inverter 19 Battery 21 Display device (notification device)
100 Control device 110 Specification section 120 Control section 121 Judgment section 122 Motor control section 123 Notification control section 201 Accelerator opening sensor 203 Brake sensor 205f Front wheel motor rotation speed sensor 205r Rear wheel motor rotation speed sensor

Claims (7)

Equipped with a control unit that controls the operation of the drive motor that outputs the driving force of the electric vehicle,
The control unit includes:
A normal mode in which the acceleration/deceleration of the electric vehicle is controlled according to acceleration/deceleration operations by the driver; and a normal mode in which the acceleration/deceleration of the electric vehicle is controlled in accordance with acceleration/deceleration operations by the driver; It is possible to switch between cruise control mode and maintain
The cruise control mode can be executed by switching between a high-speed cruise control mode and a low-speed cruise control mode in which a target vehicle speed lower than the target vehicle speed of the high-speed cruise control mode is used,
Prohibiting transition to the low-speed cruise control mode when the upper limit value of the torque of the drive motor is less than a threshold value;
Electric vehicle control device. The threshold value is set to a value corresponding to a maximum value of a required torque value of the drive motor that is assumed to occur during execution of the low-speed cruise control mode.
The control device for an electric vehicle according to claim 1. If the upper limit value falls below the threshold value during execution of the low-speed cruise control mode, the control unit controls the low-speed cruise control mode until the driver performs an input operation to stop the low-speed cruise control mode. to continue,
The control device for an electric vehicle according to claim 1 or 2. When prohibiting the transition to the low-speed cruise control mode, the control unit causes a notification device to issue a notification indicating that the transition to the low-speed cruise control mode is prohibited.
A control device for an electric vehicle according to any one of claims 1 to 3. The control unit changes the threshold value based on information regarding the driving route.
A control device for an electric vehicle according to any one of claims 1 to 4. The information regarding the running route includes information indicating the slope of the running route,
The electric vehicle control device according to claim 5. The information regarding the running route includes information indicating the type of the running route,
The electric vehicle control device according to claim 5 or 6.

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