JPH04236107A - Hill climbing controller for motor vehicle - Google Patents

Abstract

PURPOSE:To enhance the climbing ability of a motor vehicle while ensuring safety. CONSTITUTION:A current detector 4 is inserted into a control circuit and current supply is controlled such that the detected current does not exceed a limit level (I) being set for the purpose of protection of control machine and the limit level (I) is lowered when an inclination angle detector 5 detects a specific angle (alpha) which may cause trouble in safety traveling. Current is normally fed upto the limit level (I) which is set at a maximum level within safety range of the control machine thus realizing quick traveling. When a motor vehicle travels on a hill with the specific angle (alpha) which may cause trouble in safety traveling, the inclination angle detector 5 detects the fact and lowers the limit level (I) thus ensuring safety.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electric vehicles such as electric wheelchairs, and is intended to improve the hill-climbing performance of electric vehicles and ensure safety.

0002

2. Description of the Related Art In electric vehicles, supply current is generally limited in order to protect control equipment from overcurrent during overload. However, since the drive torque is determined by this supplied current, if this current limit value is set low, the running speed will be extremely reduced when driving uphill with an overload that exceeds the current limit value, resulting in poor running performance. can be,
In addition, if this current limit value is set to the highest value within the range that does not damage the control equipment, the running speed will not decrease when running uphill and the running performance will improve, but at the same time the maximum climbing angle will also increase, which is particularly difficult for small vehicles such as electric wheelchairs. In this case, the risk of losing the balance of the aircraft increases.

0003

[Problems to be Solved by the Invention] The present invention solves the drawbacks of the prior art as described above, and makes it possible to quickly run with less speed reduction when climbing uphill up to a certain angle that does not hinder safe driving. In addition, when the vehicle is climbing a hill at a certain angle or more, which poses a problem to safe travel due to the balance of the aircraft, control is performed to give priority to safety.

0004

[Means for Solving the Problems] In an electric vehicle that runs by applying current from a power source 1 to a motor 3 via a drive transistor 2, a current detector 4 for detecting a supplied current is provided in a control circuit to detect the current. When the detector 4 detects a current exceeding the current limit value (I) set for protection of control equipment, the duty ratio, which is the ratio of drive pulses, is lowered to control the supplied current to below the current limit value (I). At the same time, the hill climbing control device for an electric vehicle is characterized in that when the running road surface inclination angle detection device 5 detects running uphill at a certain angle (α) or more, the current limit value (I) is corrected to decrease. composition.

[0005]

Effects of the invention: During normal driving, current can be supplied up to the maximum current limit value (I) without damaging the control equipment, and the current can be supplied at a constant angle (α) that does not hinder safe driving.
) When driving uphill as described below, the vehicle is driven with a large torque and can be driven quickly with less reduction in speed.
Also, due to the balance of the aircraft, there is a certain angle (α
) When traveling uphill, the inclination angle detection device 5 detects this and corrects the current limit value (I) to a lower value, thereby reducing the traveling speed and ensuring safety. . Incidentally, the correction value of the current limit value (I) may be made extremely low to completely stop running uphill at a dangerous angle.

[0006]

[Embodiment] The illustrated example is an electric wheelchair in which the present invention is implemented, and FIG. 2 is a block diagram showing the connection state of input means and control means, and 6 is a CPU as a central processing unit.
, 7 is a speed command signal generator, specifically constituted by a variable resistor whose rotation is adjusted by an accelerator, and inputs its output voltage to the CPU 6 via an A/D converter. Reference numeral 8 denotes a speed change switch, which selects three speeds, high, medium, and low, and inputs the selected speed to the CPU 6.

The power source 1 is a DC battery, and the battery voltage is detected by a battery voltage detector 9 and sent to the CPU 6.
The data is input to the computer, the calculation is processed, and the remaining battery level is displayed on 5 LEDs.
It is displayed by a battery meter 10 consisting of: The motor 3 that drives the wheels of the electric vehicle is connected to the power source 1 via a forward/reverse switching relay 11, and the forward/reverse switching relay 11 is connected to the CPU 6 by a forward command circuit 12 and a reverse command circuit 13.
It is connected to.

The drive transistor 2 is driven by a drive pulse (A) that is input from the speed command signal generator 7 mentioned above, processed by the CPU 6, and output, and supplies current from the power source 1 to the motor drive circuit 14. . Reference numeral 16 denotes a braking transistor which is similarly driven by a braking pulse (B) outputted from the CPU 6, configures the motor drive circuit 14 into a closed circuit, and performs a dynamic braking operation.

Reference numeral 15 denotes a rotation speed detector, which measures the voltage generated by the inertial rotation of the motor 3 during the neutral pulse (N) commanded by the CPU 6, and measures the voltage generated by the inertial rotation of the motor 3.
The data is input to the CPU 6 via a converter to calculate the traveling speed. As shown in FIG. 3, one cycle of the above-mentioned pulse formation train consists of 50 steps, and one step is a drive pulse (A ), braking pulse (B),
Step by step with each neutral pulse (N). (Therefore, the time required for one cycle is 25 ms.)
The neutral signal (N) is always provided at the beginning or end of the pulse formation train, and has two to three consecutive pulses.

Further, as shown in FIG. 4, the ratio of the drive pulses (A) to the entire pulse train is called the duty ratio, and the higher the duty ratio, the higher the speed of the vehicle. Reference numeral 17 denotes a negative-actuating electromagnetic brake, which releases braking by applying electricity while the vehicle is running, and returns to its original state by spring force while the vehicle is stopped, applying braking force to the motor shaft. 18 is a temperature sensor that measures the temperature near the control section, especially the drive transistor 2, and
It is input to the CPU 6 via the D converter, and when the temperature rises, the current supplied to the motor 3 is limited or stopped to protect the motor 3 and the control section.

The current detector 4 is provided in the motor drive circuit 14 and detects the current supplied to the motor 3 and inputs it to the CPU 6 via the A/D converter to detect the load state. The inclination angle detection device 5 is a known inclination sensor provided at a suitable location on the aircraft, and inputs its detected value to the CPU 6 via an A/D converter.

Next, to explain its operation, when the command voltage of the speed command signal generator 7 is input to the CPU 6 via the A/D converter by operating the accelerator, a predetermined signal is output from the CPU 6 in accordance with the command value. A proportional drive pulse (A), a braking pulse (B), and a neutral pulse (N) are output, and the drive transistor 2 is driven by the drive pulse (A), and the current supplied from the power supply 1 is applied to the motor 3 to run. Start. Also, at the same time as this running starts, the rotation speed detector 15 detects the voltage generated by the inertial rotation of the motor 3 during the neutral pulse (N), and this detected value is input to the CPU 6 via the A/D converter to start running. The speed is calculated, the running speed is compared with the commanded speed, and the duty ratio, which is the ratio of the drive pulse (A), is changed according to the difference, and the vehicle travels at the commanded speed. In addition, the braking pulse (B) that configures the motor drive circuit 14 as a closed circuit and performs dynamic braking is particularly suitable for electric wheelchairs whose legal speed is set at 6〓/H, and is used to reduce gravitational acceleration when traveling downhill. This is important for preventing this and for driving at a constant speed.

Next, when running uphill, the running load is large and the detected actual speed decreases, so the duty ratio, which is the ratio of the drive pulse (A), is gradually adjusted by comparing it with the commanded speed. Finally, all pulses except the neutral pulse (N) are used as drive pulses (A), and in this state, a large current is supplied and consumed by the motor load. If this state continues for a long time, the control equipment and motor 3 may be damaged due to heat, etc. Therefore, when the current limit value (I) set for the purpose of preventing this is reached, the current detector 4 detects this. At the same time, the CPU via the A/D converter
The drive pulse (A
) to suppress the supplied current to below the current limit value (I). Also, this current limit value (I)
is set to the maximum value within a range that does not damage the control equipment, so during normal uphill driving, speed reduction due to load is minimized and speedy driving is possible.

[0014] Since the current limit value (I) is set relatively high in this way, it is possible for a light and small electric wheelchair to travel at a certain angle (α) or more, which would impede safe travel due to body balance. and is extremely dangerous. In such a state, the inclination angle detection device 5 detects a certain angle (α) or more and inputs it to the CPU 6 via the A/D converter.
The current limit value (I) is corrected to a lower value based on the calculation command from U6. Therefore, the current supplied to the motor 3 is limited, the drive torque is reduced, and the running speed is slowed down, allowing safe running. Incidentally, climbing at a dangerous angle can be prevented by slowing down the controlled running speed to a level that cannot be used for actual running.

The above control results are shown in FIG. 5, and for comparison, the current limit value (
(X) shows the change in running speed at full throttle when I) is set to 35A (ampere), and similarly the running speed when the current limit value (I) is set to 40A, which is an embodiment of the present invention. The change in speed is indicated by (Y), and the fixed angle (α) that hinders running is set to 18°, and the correction value of the current limit value (I) when this fixed angle (α) is exceeded is The change in running speed when set to 35A is shown by (Z).

Similarly, the change in motor supply current when the current limit value (I) is 35A is expressed as (XI), and the change in the motor supply current when the current limit value (I) is 4A.
The change in the motor supply current at 0A is shown as (YI), and the change in the motor supply current when the current limit value (I) is corrected from 40A to 35A is shown as (ZI). Similarly, changes in the duty ratio, which is the ratio of each drive pulse (A), are shown as (XD), (YD), and (ZD) and are shown in FIG.

As is clear from this result, the current limit value (
I) is set to 40A, the constant angle (α) for danger prevention is set to 18°, and the correction value of the current limit value (I) is set to 3.
Since it is set to 5A, at a certain angle (α) that does not interfere with safe driving, that is, at an inclination angle of 18° or less, a maximum current of 40A is supplied, and the large torque reduces the speed drop due to load and runs quickly. When traveling uphill with an inclination angle of 18° or more, which may impede safe travel due to aircraft balance, the current limit value (I) can be corrected to 35A to suppress the supplied current and reduce the traveling speed to ensure safety. . Figure 1 is a flowchart showing the operation of this control. is α−2
This is done when the temperature reaches 16°, and this is to prevent the hunting phenomenon.

Note that the current limitation by the temperature sensor 18 is as follows:
Even when traveling uphill with a small inclination angle, if the uphill traveling continues for a long time, there is a risk that the control equipment will generate heat even though the supplied current is relatively low, and this is used to prevent this. In addition, in the embodiment, the tilt angle detection device 5 is constituted by a tilt sensor attached to the aircraft body, but due to the relationship between the duty ratio and speed during control operation based on the current limit value (I), a constant angle (α) is used. Alternatively, the CPU 6 may calculate.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a control operation.

FIG. 2 is a control block diagram.

FIG. 3 is a diagram showing a pulse organization train.

FIG. 4 is a diagram showing a duty ratio in a pulse formation train.

FIG. 5 is a diagram showing changes in supply current and actual speed that are controlled in accordance with the inclination angle of the running road surface.

FIG. 6 is a diagram showing changes in the duty ratio that is controlled in response to the inclination angle of the road surface.

[Explanation of symbols]

1 Power supply 2 Drive transistor 3 Motor 4 Current detector 5　Inclination angle detection device I Current limit value α Fixed angle

Claims (1)

[Claims] [Claim 1] In an electric vehicle that runs by applying current from a power source (1) to a motor (3) via a drive transistor (2), a current detector (4) detects a supplied current in a control circuit. When the current detector (4) detects a current exceeding the current limit value (I) set for protection of control equipment, the duty ratio, which is the ratio of drive pulses, is lowered to reduce the supplied current to the current limit value (I). The current limit value (I) is configured to be controllable as follows, and is characterized in that when the driving road surface inclination angle detection device (5) detects running uphill by a certain angle (α) or more, the current limit value (I) is corrected to lower the current limit value (I). A hill climbing control device for electric vehicles.