JP2002058101A - Roll-back suppressor in electric motor car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fully suppress roll back of an electric motor car, even when it stops temporarily on a steep slope. SOLUTION: A torque-computing means 11 computes a torque command for suppressing roll back by a motor 35, on the basis of each operating state of the electric motor car and the characteristics of torque commands stored in a torque map 12. A motor controller 20 suppresses the roll back of the car, on the basis of this torque command, controls the output torque of the motor on the basis of a torque command computed separately and drives the wheels. A characteristic of the torque commands for suppressing the roll back of the car stored in the torque map 12, is a forward characteristic which has a positive torque command, when the rotational speed of the motor is zero, and increases gradually in the positive direction as the rotational speed of the motor increases in the negative direction, when the wheels are driven by the motor in the forward direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle using a motor powered by a battery and driving wheels, and when the vehicle stops on a hill, the vehicle slides down the hill without applying a brake. The present invention relates to a device that suppresses occurrence of (hereinafter, simply referred to as rollback).

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing the overall structure of an electric vehicle equipped with the present invention. The conventional electric vehicle shown in FIG. This is the same as the above except for the point that the "torque command value" characteristic is different, so that the prior art will be described with reference to FIG. In this type of conventional electric vehicle,
When the accelerator operation is performed by a manual accelerator lever or the like, the vehicle ECU (vehicle control device) 10 operates the motors 35a and 35b connected to the left and right wheels via the motor ECU (motor control device) 20 to control the electric vehicle. The vehicle is running and stopped by activating the brake.

[0003] To explain this prior art in more detail, this electric vehicle includes a vehicle ECU 10 for controlling the operation of the entire electric vehicle, and motors 35a for driving the left and right wheels based on commands from the vehicle ECU 10. The motor ECU 20 controls the operation of the motor ECU 35b. These two E
The CUs 10 and 20 are powered by a low-voltage battery 32, and the motors 35a and 35b are powered by a motor drive battery 31 via a relay 33 and an inverter 34.

The vehicle ECU 10 includes a main switch 15 of the electric vehicle and a brake sensor (brake switch) 16 which is closed when a brake operated by the user is operated.
And an accelerator sensor 17 for detecting an operation amount (opening degree) of an accelerator member such as an accelerator lever or an accelerator pedal operated by a user, and rotating the motors 35a and 35b in the forward or reverse direction to move the vehicle forward or backward. A shift position sensor 18 for detecting each shift position (forward, reverse, neutral) of a shift device (not shown) for moving backward is connected. Further, the vehicle ECU 10 determines the characteristics of the torque command values (Cd, Cr in FIG. 4) used when the wheels are driven by the motors 35a, 35b corresponding to the respective operating states of the electric vehicle.
4) and a torque map 12 storing characteristics of torque command values used for suppressing rollback (see Dd and Dr in FIG. 4), and operating states and torques of the electric vehicle detected by the sensors 16 to 18. A torque calculating means 11 is provided for calculating a torque command value for driving wheels by the motors 35a and 35b and a torque command value for suppressing rollback based on the map 12. Relay 3 in the power supply circuit to motors 35a and 35b
3 is controlled by the vehicle ECU 10.

[0005] The motor ECU 20 includes motors 35a, 3
5b generates a torque according to the torque command value calculated by the torque calculating means 11 so that the electric vehicle runs and the rollback is suppressed.
4 is controlled. The left and right wheels are connected to the left and right motors 3 without any intervening mechanism such as a clutch.
5a, 35b and are always driven at the corresponding rotational speeds. The rotational speeds (and thus the vehicle speeds) of the motors 35a, 35b are detected by the respective rotational speed sensors 36a, 36b, and are transmitted to the vehicle ECU 10 via the motor ECU 20. Is transmitted to The voltage of the motor driving battery 31 is detected by a voltage sensor 21 provided in the motor ECU 20 and transmitted to the vehicle ECU 10. Both batteries 31, 32 are
When the electric vehicle is not used, it is charged by the charger 30 connected to a 100 volt AC power supply. Alternatively, a generator driven by an internal combustion engine may be mounted, and the batteries 31 and 32 may be charged by the generator during use of the electric vehicle.

[0006] As shown in FIG.
It stores the characteristics of the torque command value with respect to the rotation speed of each of the motors 35a, 35b, and includes four characteristics Cd, Cr, D
d and Dr. Characteristic Cd and characteristic Cr are
The characteristic of the torque command value that maximizes the output possible range when the vehicle is driven by driving the wheels by the motors 35a and 35b, the characteristic Cd is the characteristic when the shift position is D (forward), and the characteristic Cr is the shift position. Is the characteristic in the case of R (reverse). Characteristic Dd and characteristic D
r is a characteristic of a torque command value for suppressing rollback when the accelerator is closed without operating the brake, a characteristic Dd is a characteristic when the shift position is D, and a characteristic Dr is a characteristic when the shift position is R. It is a characteristic in the case.

When the electric vehicle is in a normal running state, that is, when the brake sensor 16 has not detected the operation of the brake and the operation amount detected by the accelerator sensor 17 is not zero, the torque calculation means 11 determines the characteristics Cd and Characteristic C
r and a torque command value that maximizes the output possible range when the vehicle travels, based on the rotation speeds of the motors 35a and 35b detected by the rotation speed sensors 36a and 36b,
That is, a torque command value when the accelerator operation amount is the maximum is calculated, and a torque for driving wheels according to the accelerator operation amount at that time is calculated based on the torque command value and the operation amount detected by the accelerator sensor 17. Calculate the command value. The vehicle ECU 10 outputs the torque command value thus calculated to the motor ECU 20, and the motor ECU 20
As described above, based on this torque command value, each motor 35
a and 35b control the inverter 34 so as to drive each wheel. Thereby, the electric vehicle moves forward or backward according to the shift position with an output corresponding to the accelerator operation amount at that time.

In the prior art described above, when the shift position is set to the forward position and the accelerator is closed without actuating the brake, the rotational speed of the motors 35a and 35b (see the characteristic Dd in FIG. Therefore, when the vehicle speed is in the negative range, a constant positive torque command value is given to the motors 35a and 35b. Therefore, the rollback when the accelerator is closed without operating the brake in a state where the vehicle is temporarily stopped on an uphill is suppressed by the positive torque (torque for moving the electric vehicle forward) generated in the motors 35a and 35b. This makes it easy to start on a slope. In the state where the shift position is set to the reverse position and the accelerator is closed without operating the brake, the characteristic D shown in FIG.
As shown by r, since a constant negative torque command value is given to the motors 35a and 35b when the rotational speed is within the positive range, the vehicle can easily start on a sloping road in the case of reverse travel.

[0009]

However, in the above-described prior art, when the shift position is set to the forward position, the positive torque generated in the motors 35a and 35b in the negative range of the vehicle speed is constant as shown by the characteristic Dd. Since the value is a value, when the gradient of the uphill is steep, it is insufficient to suppress the rollback, and there is a problem that the speed of the electric vehicle gradually increases as the electric vehicle starts to roll down. As a countermeasure against this problem, it is conceivable to increase the height of the characteristic Dd as a whole. In such a case, the brake should be activated when the vehicle is temporarily stopped on a flat road or a gentle uphill. This causes a problem that the vehicle suddenly starts when the brake is released. A similar problem occurs when the shift position is set to the reverse position. An object of the present invention is to solve each of these problems.

[0010]

As shown in FIG. 1, a rollback suppressing device for an electric vehicle according to the present invention includes a motor driven by a motor driving battery to drive wheels, and a brake for detecting operation of a brake. Sensors and
An accelerator sensor for detecting an accelerator operation amount, and driving the wheels by the motor used in an operation state in which the brake sensor has not detected the operation of the brake and the operation amount detected by the accelerator sensor is not zero. To suppress rollback of the vehicle by the motor used in the operating state where the characteristic of the torque command value and the brake sensor does not detect the operation of the brake and the operation amount detected by the accelerator sensor is 0. The wheels are driven by the motor in accordance with the respective operating states based on the torque map storing the characteristics of the torque command values and the operating states of the electric vehicle detected by the sensors and the characteristics of the torque map. Command value for suppressing or torque command value for suppressing the rollback And a motor control device for controlling the output torque of the motor based on the torque command value calculated by the torque calculation means to drive the wheels and suppress rollback of the vehicle. In the rollback suppression device for the electric vehicle, the characteristic of the torque command value for suppressing the rollback of the vehicle stored in the torque map may be such that the motor drives the wheels in the forward direction. When the rotation speed of the motor is 0, the torque command value is a positive value, and the motor has a forward characteristic that gradually increases in the positive direction as the rotation speed increases in the negative direction.

The characteristic of the torque command value for suppressing the rollback of the vehicle stored in the torque map of the invention of the preceding paragraph is such that the motor drives the wheels in the reverse direction in addition to the forward characteristic of the preceding paragraph. In this case, when the rotation speed of the motor is 0, it is preferable that the torque command value is a negative value, and that the reverse rotation characteristic gradually increases in the negative direction as the rotation speed increases in the positive direction.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a configuration of a rollback suppression device in an electric vehicle according to the present invention, and FIG. 2 is a block diagram illustrating an overall configuration of one embodiment of a rollback suppression device in the electric vehicle according to the present invention. A diagram showing this configuration, a block diagram thereof, and the overall operation thereof are shown in a vehicle ECU.
Except that the characteristic of the torque command value for suppressing rollback stored in the torque map 12 of FIG.

Each motor 3 stored in the torque map 12
As shown in FIG. 3, the characteristics of the torque command value with respect to the rotation speeds of 5a and 35b are four characteristics Ad, Ar, Bd,
It is made of Br. The characteristic Ad and the characteristic Ar are the characteristics of the torque command value that maximizes the output possible range when the electric vehicle runs by driving the wheels by the motors 35a and 35b. There is essentially no difference from Cr.

The characteristic Bd and the characteristic Br indicate that the accelerator is closed without operating the brake, that is, the brake sensor 16 does not detect the operation of the brake and the operation amount detected by the accelerator sensor 17 is zero. The characteristic Bd is a forward characteristic when the shift position is D, and the characteristic Br is a reverse characteristic when the shift position is R. When the shift position is D, that is, when the motors 35a and 35b drive the wheels in the forward direction, the characteristic Bd of the torque command value is, as shown in FIG.
When the rotation speed of the rotation speed 35b is 0, the slope portion has a positive value and gradually increases in the positive direction as the rotation speed increases in the negative direction, and becomes considerably larger in the positive direction than the value when the rotation speed is 0. After the fixed value part. That is, the forward-side characteristic Bd of the torque command value for suppressing the rollback is different from the value when the rotation speed is 0 as the rotation speed of the motors 35a and 35b (accordingly, the vehicle speed) increases from 0 in the negative direction. At the point where the rotation speed of the motors 35a and 35b becomes a constant value in the negative range at the point where the rotation speed of the motors 35a and 35b becomes a constant value after increasing to a considerably larger value in the positive direction, the torque command of the prior art shown in FIG. It is different from the value characteristic Dd.

When the shift position is R, that is, when the motors 35a and 35b drive the wheels in the reverse direction, the characteristic Br of the torque command value is shown in FIG.
As shown in (b), when the rotation speed of the motors 35a and 35b is 0, the rotation speed is a negative value, and the rotation speed gradually increases in the negative direction as the rotation speed increases. The constant value part after the value becomes much larger in the negative direction than the value in the case of. That is, the reverse characteristic Br of the torque command value for suppressing the rollback is:
As the rotational speed of the motors 35a and 35b (and thus the vehicle speed) increases from 0 in the positive direction, the rotational speed increases in the negative direction from the value at 0 to a value substantially larger in the negative direction, and then reaches a constant value. , 35b are different from the prior art torque command value characteristic Dd shown in FIG.

According to this embodiment, when the electric vehicle closes the accelerator without operating the brake and temporarily stops on the uphill with the shift position set to D, the gradient of the uphill is steep. When the electric vehicle starts to slide down, the torque for suppressing rollback increases as the speed increases. Therefore, even when the vehicle is running on a slope having a steep slope, the vehicle does not start moving down the slope easily because the speed of the slope does not increase at an accelerated rate. In addition, since the torque that suppresses rollback at the time of stoppage is small, the brake is activated to temporarily stop on a flat road, and when the brake is released, the start of the electric vehicle due to the torque that suppresses rollback is gradual and sudden. There is no start. Similarly, even when the shift position is set to R, starting on a slope is easy, and when the vehicle is temporarily stopped on a flat road, the electric vehicle does not suddenly start when the brake is released. Therefore, an electric vehicle that is easy to handle can be obtained.

In the above-described embodiment, the characteristic Bd and the characteristic Br of the torque command value for suppressing the rollback are composed of a constant slope portion and a high constant value portion. The gradient may change according to the motor rotation speed, or the torque command value may change in a stepwise manner. Further, the fixed portion may be eliminated by extending the inclined portion, or a combination of these may be used.

[0018]

According to the present invention, the characteristic of the torque command value for suppressing the rollback of the vehicle when the motor drives the wheels in the forward direction is such that the rotational speed of the motor is zero. Sometimes, the forward side characteristic gradually increases in the positive direction as the rotation speed increases in the negative direction with a positive value, so in such a state that the electric vehicle closes the accelerator without operating the brake without operating the brake When the vehicle is temporarily stopped on an uphill, if the gradient of the uphill is steep and the electric vehicle starts to slide down, the torque for suppressing rollback increases as the speed of the electric vehicle increases. Therefore, even in the case of a steep slope, the downhill speed does not increase at an accelerating rate. In addition, since the torque that suppresses rollback at the time of stopping can be reduced, the brake is operated to temporarily stop on a flat road, and the start of the electric vehicle due to the torque that suppresses rollback when the brake is released is moderate. And does not start suddenly. This makes it possible to obtain an electric vehicle that is easy to handle.

In the invention of the preceding paragraph, the characteristic of the torque command value for suppressing the rollback of the vehicle is changed to the forward-side characteristic of the preceding paragraph, and if the motor drives the wheels in the reverse direction, When the rotation speed is 0, a negative value is added, and the rotation speed increases in the positive direction. As the rotation speed increases in the negative direction, the reverse-side characteristic is added, so that the motor drives the wheels in the reverse direction. In this case, the same effect as in the preceding paragraph can be obtained, so that an electric vehicle that is easier to handle can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a rollback suppressing device in an electric vehicle according to the present invention.

FIG. 2 is a block diagram illustrating an overall configuration of an example of a rollback suppression device in an electric vehicle according to the present invention.

FIG. 3 is a diagram illustrating an example of a characteristic of a torque command value for suppressing rollback used in the present invention.

FIG. 4 is a diagram showing an example of a characteristic of a torque command value for suppressing rollback in the related art.

[Explanation of symbols]

11: Torque calculation means, 12: Torque map, 16: Brake sensor (brake switch), 17: Accelerator sensor, 20: Motor controller (motor ECU), 31 ...
Battery for motor drive (battery for high voltage), 35 (3
5a, 35b) ... motor.

Claims (2)

[Claims] 1. A motor that is powered by a motor driving battery to drive wheels, a brake sensor that detects an operation of a brake, an accelerator sensor that detects an accelerator operation amount, and a brake sensor that detects an operation of a brake. And the characteristic of the torque command value for driving the wheels by the motor used in the operation state in which the operation amount detected by the accelerator sensor is not 0 and the brake sensor does not detect the operation of the brake. A torque map storing characteristics of a torque command value for suppressing rollback of the vehicle by the motor used in an operation state in which the operation amount detected by the accelerator sensor is 0; Each of the operating states is based on each operating state of the vehicle and each characteristic of the torque map. Torque calculating means for calculating a torque command value for driving the wheels by the motor or a torque command value for suppressing the rollback in accordance with the state, and a torque command value calculated by the torque calculating means. A rollback suppression device for an electric vehicle, comprising a motor control device that controls the output torque of the motor based on the output torque of the motor to suppress the rollback of the vehicle while driving the wheels. The characteristic of the torque command value for suppressing the back is such that when the motor drives the wheel in the forward direction, the rotational speed of the motor is 0.
In the above case, the torque command value is a positive value and the forward-side characteristic gradually increases in the positive direction as the rotational speed increases in the negative direction. 2. The characteristic of a torque command value for suppressing rollback of a vehicle stored in the torque map is such that the motor drives the wheel in a reverse direction in addition to the forward characteristic. 2. The motor according to claim 1, wherein when the rotational speed of the motor is zero, the torque command value is a negative value and the reverse side characteristic gradually increases in the negative direction as the rotational speed increases in the positive direction. 3. The rollback suppressing device in the electric vehicle according to claim 1.