JPH0442706A - Electric vehicle driving control method - Google Patents

Abstract

PURPOSE:To realize safety traveling even on a down slope by comparing a duty ratio output with an actual speed and determining the inclination angle of a travel path and then suppressing the speed of an electric vehicle below a command speed if the inclination angle is larger than a reference inclination of down slope. CONSTITUTION:When an electric vehicle travels on a steep down slope, especially when it travels reversely, travel speed V of the electric vehicle detected through an r.p.m. detecting section 21 and operated through a CPU 4 is compared with a duty ratio Y output from the CPU 4 according to travel conditions in order to determine the inclination angle of a travel path. Thus determined inclination angle is compared with a reference steep inclination angle and when the reference value is exceeded, it is judged as a steep down slope and switching is made to an automatic reverse low speed mode. Consequently, duty ratio is suppressed below a predetermined level and the electric vehicle is driven safely at low speed.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for controlling the running of an electric vehicle such as a wheelchair, and more specifically to a control method that allows the vehicle to travel safely even on a steeply sloping road. It is related to.

(Prior art) Conventionally, this type of electric vehicle has an extremely small amount of energy stored in the pantry compared to an internal combustion engine, and therefore, in order to ensure a long range, it is necessary to make the body lightweight and compact. Therefore, the stability of the aircraft is slightly inferior.

In addition, this type of electric vehicle controls the running speed by changing the duty ratio, which is the ratio of drive pulses that drive the motor, but if this operation is incorrectly performed, for example, when driving in reverse on a downhill slope or at high speed, Due to the weight of the vehicle, the speed of the vehicle is further increased, leading to the risk of colliding with an obstacle or falling over if the road surface is poor.

(Problems to be Solved by the Invention) The present invention aims to eliminate the drawbacks of the prior art as described above and to provide a method for controlling the running of an electric vehicle that can safely run downhill.

(Means for solving the problem) In an electric vehicle that controls the traveling speed by changing the duty ratio, which is the ratio of the drive signal that drives the motor with electricity, the actual speed of the electric vehicle in motion is detected and output. The duty ratio and the detected actual speed are compared and calculated to calculate the slope angle of the running road, and if the calculated slope angle is greater than the reference value for downhill slope, the speed of the electric vehicle is lower than the command speed. A driving control method for an electric vehicle is configured, which is characterized by suppressing control to a low speed.

(Function of the invention) In particular, when driving for operation, driving is performed while controlling the traveling speed by changing the duty ratio, which is the ratio of the drive signal that drives the motor with electricity, by operating the accelerator. By detecting the speed and comparing and calculating the output duty ratio and the detected actual speed, the slope angle of the running road is determined. The vehicle's speed is controlled to be lower than a constant speed so that the vehicle travels at a safe low speed.

(Effects of the Invention) According to the driving control method for an electric vehicle of the present invention, even if the user makes a mistake in operating the vehicle and attempts to travel at high speed on a dangerous steep downhill slope, the output duty ratio and the detected actual If the inclination angle of the traveling road calculated from the speed exceeds the reference value for downhill slope, the electric vehicle can travel safely by controlling the speed of the electric vehicle to be lower than the commanded speed.

(Example) An example of the control method of the present invention will be explained based on the drawings. FIG. 1 is a flowchart, and FIG. 2 is a control circuit diagram.

This electric vehicle can select three speed ranges with different upper limit speeds using a speed change switch 1 so that the vehicle speed can be selected according to the user's driving ability and road conditions, and an accelerator lever (not shown). By operating the speed command signal generator 2, the output of the speed command signal generator 2 can be adjusted, and the vehicle speed can be adjusted from stop to the upper limit speed of each speed range. 3 is a forward/reverse selector switch.

4 is the central processing unit (CPLI), and the gear shift switch 1
Based on the command input from the speed command signal generator 2, the field-effect driving transistor 6 and the braking transistor 7, which control the motor 5, are turned on.

It is configured to perform OFF control.

These transistors 6 and 7 are connected in series, and diodes 6a and 7a that operate when reverse biased are incorporated therein. The drain side of the transistor 60 is connected to the +24V power supply (+ side terminal of the battery), and the source side of the transistor 7 is connected to the ground side. Further, the gate side of the transistor 6 is connected to the drain side of a field effect transistor 8. 9 and 1O are inverters that control the bias on the gate side of transistors 8 and 7.

The wheel drive motor 5 is connected between the intermediate connection point of the transistors 6 and 7 and the ground side via contacts 13 and 14 of the forward/reverse switching relays 11 and 12 and a current detection circuit 15.

Relay contacts 13 and 14 for switching between cough and forward/backward movement each have two terminals a, b and terminals c, d. 16
is an electromagnetic brake that tightens the rotating shaft of the wheel drive motor 5 to decelerate and stop it.

The electromagnetic brake 16 is configured to release the rotating shaft of the motor 5 in an energized state, and tighten the rotating shaft of the motor 5 by a spring force in a non-energized state.

17 and 18 are transistors for two-stage amplification of the t-magnetic brake 16.

Also, 19 and 20 turn relays 11 and 12 ON and OFF.
The F-controlled inverter 21 is a rotation speed detection unit for calculating the rotation speed of the motor 5, that is, the speed of the electric vehicle, by detecting the back electromotive force generated by the wheel drive motor 5. be.

In such a drive control circuit for the electric vehicle 1, the drive state is controlled by the terminals PCI and PO2 of the CPU 4.
This is done by switching the output of , and the outputs of PO2 and PO7 (7) to rLJ level or rHJ level. PC
l and PO2 are contacts a and b of relay contacts 13 and 14
, c, and d to rotate the wheel drive motor 5 in the forward or reverse direction, or to hold it in the neutral position.

This is done by operating the forward/reverse selector switch 3 of the electric vehicle. When switching between terminals a and terminal C and rotating in the forward direction, the motor moves forward, and when switching between terminals A and D and causing the motor to rotate in reverse, the motor moves backward.

Furthermore, the PC6 and PC7 control the zero energization time, which is used to determine the vehicle speed of the electric vehicle by controlling the energization time to the wheel drive motor 5.
It is determined according to the selected range of the speed change switch 1 (high speed range H1, medium speed range M, low speed range L) and the speed command signal from the speed command signal generator 2 which detects the operation amount of the accelerator lever.

The specific energization time is controlled as follows.

That is, as shown in FIG.
and a neutral signal N are added at a predetermined number of steps according to each running condition to repeatedly output a one-cycle pulse train.

While the drive signal is being output, +24V power is supplied to the wheel drive motor 5, and the number of revolutions of the electric vehicle increases in accordance with the supply time. In addition, while the braking signal B is being output, the wheel drive motor 5 functions as a generator, and the generated electricity is returned to the motor 5 through the transistor 7 to perform dynamic braking, that is, in a pulse train of 1 cycle. When the duty ratio, which indicates the ratio of the number of steps to the drive signal, increases, the vehicle speed is accelerated, and conversely, when the duty ratio is decreased, the vehicle speed is decreased. Further, the neutral signal N is arranged at the end of the pulse train for about 2 to 3 pulses, and is used to detect the back electromotive force of the motor 5 at that time and calculate the speed of the electric vehicle.

When setting the drive signal A to the state, the terminal p of the CPU 4
Both c6 and PC7 are made to output rHJ level. P
When CB is at the rHJ level, the inverter 9 lowers the gate voltage of the transistor 8, and the transistor 8 becomes O
Becomes FF. Therefore, the voltage on the gate side of the transistor 6 becomes high, and the driving transistor 6 is turned on. Further, when PC7 is at the rHJ level, the inverter 10 lowers the gate voltage of the transistor OFF, and the transistor 7 is turned OFF. Therefore, +24V power supplied from the battery is supplied to the motor 5 via the relay contact 13 or 14, and flows to the ground side via the current detection section 15, driving the motor 5 to rotate.

When using braking signal B, PC6 and pc of CPU 4
Both outputs of 7 are at rLJ level. PC6 is “L”
'' level, the transistor 8 is turned on and the driving transistor 6 is turned off. Further, when PC7 is at rLJ level, braking transistor 7 is turned on. Therefore, power from the battery is no longer supplied to the wheel drive motor 5 through the drive transistor 6, and the motor 5 functions as a generator due to rotation due to inertia. The generated electricity is returned to the motor 5 through the relay contact 13 or 14 and the braking transistor 7 to perform dynamic braking.

To set the neutral signal to N, connect terminal PC6 of CPU 4 to
I,'' level and terminal PC7 to rHJ level.
That is, both driving and braking transistors 6 and 7 are turned off. As a result, the motor 5 is in a state where no load is applied, and by detecting the voltage generated by inertia rotation with the voltage detection circuit 21, the rotation speed of the motor 5, that is, the speed of the electric vehicle is determined, and the generated electricity is transferred to the battery. It is designed to store electricity.

In such an electric vehicle, when traveling down a steep slope, especially when going backwards, the shift switch 1 should be switched to a low speed based on the stability of the aircraft and the difficulty of maneuvering. However, if a beginner who is inexperienced with driving makes a mistake in judgment or operates the shift switch 1 at a high speed, there is a risk of collision with an obstacle or overturning the vehicle. .

This invention is intended to prevent such dangers, and will be explained according to the flowchart shown in FIG.
First, while driving, the CPII 4 determines whether the forward/reverse selector switch 3 is set to reverse, and if the vehicle is traveling in reverse, the first step is to determine whether the shift switch 1 is set to the low speed range. .

If shift switch 1 is not in the low speed range,
The running speed of the electric vehicle detected by the rotation speed detection unit 21 and calculated by the CPU 4 is compared with the duty ratio Y outputted from the CPU 4 according to each running condition, and the inclination angle of the running road is calculated. .

Calculation of this inclination angle is based on the experimental value or calculated summer value of the running speed when running on each inclined road when each duty ratio Y is output, as shown in the graph shown in Fig. 3.
This is stored in the PU 4, and the inclination angle of the running road is calculated from the output duty ratio Y and the actual speed ■.

Next, it is determined whether the electric vehicle has already been switched to the reverse automatic low-speed mode, which suppresses and controls the speed of the electric vehicle to be lower than the commanded speed, and if the reverse automatic low-speed mode has not been changed, the calculation described above is performed. The slope angle of the road being traveled is compared with a steep slope standard value (17 degrees in this example), and if it exceeds this standard value, it is determined that the slope is a steep downhill slope and reverse is automatically performed at low speed. Switch to mode.

This reverse automatic low speed mode performs the same control as switching the selector switch 3 to the low speed range, that is, even if the selector switch 3 is located in the high speed range, the maximum speed should be suppressed to a low speed equivalent to the low speed range ( , the duty ratio, which is the ratio of the drive signal A to the braking signal B in the pulse train, is suppressed to below a certain standard, and the vehicle runs safely at low speed.

Also, while driving in this reverse automatic low speed mode, if the slope angle of the road falls within the slope reference value (14 degrees in this example), it is determined that the road is a gentle slope with little danger, and the reverse automatic low speed mode is activated. cancel. Note that the reverse automatic low-speed mode may be canceled not while the vehicle is running, but when the output of the speed command signal generator 2 is stopped, that is, when the vehicle is stopped.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, in which Fig. 1 is a flowchart, Fig. 2 is a control circuit diagram, and Fig. 3 is a diagram showing the output duty ratio, the inclination angle of the running road, and the actual speed of the electric vehicle. FIG. 4 is a time chart showing the control pattern of the motor. In the figure, 1 is a speed change switch, 2 is a speed command signal generator, 3 is a forward/reverse selector switch, and 4 is a central processing unit (CPL).
I), 5 indicates a motor. Figure 3

Claims (1)

[Claims] In an electric vehicle that controls the running speed by changing the duty ratio, which is the ratio of the drive signal that drives the motor, the actual speed of the electric vehicle while it is running is detected, and the output duty ratio and the detected actual speed are The present invention is characterized in that the inclination angle of the traveling road is calculated by comparing and calculating the inclination angle of the traveling road, and if the calculated inclination angle is equal to or greater than a reference value for a downward inclination, the speed of the electric vehicle is suppressed and controlled to be lower than the commanded speed. A driving control method for electric vehicles.