JPH03198601A - Drive control method of motor-driven vehicle on-overload - Google Patents

Abstract

PURPOSE:To protect a circuit and to secure safe traveling by measuring the temperature of an electronic component by a temperature sensor, controlling to correct a duty ratio in response to the measured temperature, and performing a stopped overload control drive. CONSTITUTION:The detection signal value of a temperature sensor 24 is compared with a reference value during running of a motor-driven vehicle, and a normal drive control based on an existing duty ratio set by an operation input is performed when the signal value is lower than the reference value. An overload control drive is performed when the signal value of the sensor 24 is the reference value or higher. The overload drive is performed at a predetermined ratio which is less than 1 to the existing duty ratio. When the signal value of the sensor 24 exceeds a limit value, an output of an acceleration signal is stopped to stop running. As a result, a speed control can be performed in a stepped manner until the temperature of an electronic component arrives from a temperature required to be monitored at a dangerous temperature.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is designed to prevent an electric vehicle from running over a steep slope etc. when it continuously runs up a steep slope, resulting in overloaded operation, which causes electronic parts and motors to generate abnormal heat. The present invention relates to a control method.

[Conventional technology]

This type of electric vehicle includes a wheelchair type for physically disabled people, a tricycle type, and a work vehicle type such as a forklift. Basically, both of these systems control the driving state by intermittently controlling the rotation of the wheel drive motor in the forward and reverse directions.

The tricycle-type electric vehicle 1 shown in FIG. 2 was developed by one of the applicants and is already commercially available.

This electric vehicle 1 controls the rotation of a wheel drive motor in forward and reverse directions using a battery installed in the space below the seat 2, and drives the rear wheels 3 to move forward and backward.

The drive control circuit is as shown in the electrical schematic diagram of FIG. That is, the central processing unit (CPU) 4 controls the wheel drive motor 5 based on preset conditions.
Field-effect drive transistor 6 that controls
And the braking transistor 7 is controlled to turn on and off. These transistors 6 and 7 are connected in series, and have built-in diodes 6a and 7a that operate during reverse bias. The drain side of the transistor 6 is connected to the +24V power supply (+ side terminal of the battery), and the source side of the 1-rangistough 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 10 are inverters that control the bias on the gate side of transistors 8 and 7.

The wheel drive motor 5 has a forward/reverse switching relay 11 between the intermediate connection point of the transistors 6 and 7 and the ground side.
and 12 contacts I3 and 14 and a current detector 15. The relay contacts 13 and 14 each have two terminals a, b and a terminal C2d.

In addition, in FIG. 3, 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 releases the rotating shaft of the motor 5 in an energized state, and tightens the rotating shaft of the motor 5 by a spring force in a non-energized state.

Further, in the same figure, 17 and 18 are the electromagnetic brake 16
This is a two-stage amplification transistor. Furthermore, 19 and 20
is an inverter that controls ON and OFF of relays 11 and 12, and 21 is a rotation speed detector. This rotation speed detector 21 is for calculating the rotation speed of the motor 5 (travel speed of the electric vehicle 1) by detecting a back electromotive force generated by the wheel drive motor 5. . Furthermore, 22 is a main relay, 23 is a contact thereof, 24 is a temperature sensor that detects the temperature of electronic components, 25 is an inverter that controls ON/OFF of the main relay 22, and 26 is a light-emitting display of battery voltage using, for example, 5 LEDs. It is a display device that

In the drive circuit for such an electric vehicle I, the drive state is controlled by controlling the outputs of the terminals Pct and PC2 of CPII 4 and the outputs of PCB and PC7 to the "I7" level or "
This is done by switching to the I(" level.

PCI and PC2 are contacts a of relay contacts 13 and 14.
This is for switching the motors b, 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 of the electric vehicle 1.

When switching between terminals a and terminal C and forward rotation, the motor moves forward; when switching between terminals A and D and the motor rotates in reverse, the motor moves backward. In addition, PCB and PC7 are wheel drive motors 5
By controlling the energization time to
This is to determine the running speed of the vehicle. Control of the energization time is determined according to the opening degree of the throttle lever and the state of the speed changeover switch (high speed, medium speed, low speed).

The specific energization time is controlled as follows. That is, for example, as shown in FIG.
The time of one cycle of m5 is further divided into 50 sections, during which the accelerator signal A, the brake signal B, and the neutral signal N are outputted at a predetermined ratio according to each driving condition. In a state where the accelerator signal A is being output, +24V power is supplied to the wheel drive motor 5, and the number of revolutions of the electric tricycle 1 increases in accordance with the supply time of the power. Further, while the brake 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, so that dynamic braking is performed. In addition, the neutral signal N
In one cycle, about 2 to 3 pulses are arranged at the end, and the counter electromotive force of the motor 5 at that time is detected to detect the running speed of the electric vehicle 1.

When setting the state of the accelerator signal A, both the terminals PCB and PC7 of the CPU 4 are outputted at the "H" level.

When PC6 is at H'' level, the inverter 9 lowers the gate voltage of the transistor 8, turning the transistor 8 off.Therefore, the gate voltage of the transistor 6 increases, and the driving transistor 6 turns on.

Also, if PC7 is at “I” level, inverter 1
0, the gate voltage of the transistor 7 decreases, and the transistor 7 is turned off. This state is the case of the accelerator signal A, and +24V power supplied from the battery is supplied to the wheel drive motor 5 via the relay contact 13 or 14. The current then flows to the ground side via the current detector I5. Therefore, the wheel drive motor 5 is rotationally driven.

When setting the brake signal to B, the outputs of PC6 and PC7 of the CPU 4 are both set to the "L" level. The PC
When 6 is “L level”, transistor 8 is turned on.
Then, the driving transistor 6 is turned off. Also PC7
is at the "L" level, the braking transistor 8 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 transferred to relay contact 13 or 14.
Then, it is returned to the motor 5 side through the braking transistor 7, and a load is applied to the motor 5 to perform dynamic braking.

When setting the neutral signal to N, the terminal PCe of CPIJ4 is set to "L" level, and the terminal PC7 is set to "H" level. That is, both driving and braking transistors 6 and 7 are turned off. As a result, the wheel drive motor 5 is in a state where no load is applied, and by detecting the voltage generated by inertia rotation with the voltage detector 21, the rotation speed of the motor 5 is detected and the running speed of the electric vehicle l is determined. I have to. Then, the generated electricity is accumulated in the battery side through reverse bias transistors 6a and 7a, and so-called regenerative braking is performed.

[Problem to be solved by the invention]

Therefore, when such an electric vehicle 1 continuously runs up a steep slope, etc., the wheel drive motor 5 becomes overloaded, and the motor 5 is heated and burnt out, and the drive transistor 6 and drive control circuit of the drive control circuit are damaged. Electronic components such as the braking transistor 7 may become abnormally heated and damaged, leading to accidents such as short circuits or open breakdowns. In such a damage accident, the accelerator signal A may continue to be sent to the wheel drive motor 5, causing the vehicle to run out of control and must be avoided. Therefore,
Conventionally, the temperature of these electronic components is measured using a sensor 24.
(See Figure 3), and if the value exceeds a limit value such as 53°C, it is determined that an overload operation is occurring, and the drive control signal to be output to the wheel drive motor 5 is sent to the brake signal B. We are trying to stop the operation immediately.

As a result, the vehicle suffers a large impact when stopped, and cannot be driven continuously on steep slopes, making it extremely inconvenient to use. In addition, the driver was sometimes confused because he did not know what caused the electric vehicle 1 to stop and could not distinguish it from a malfunction.

[Means to solve the problem]

The present invention improves and eliminates the above-mentioned conventional problems, and when an overload condition occurs, the duty ratio, which is the output ratio of the accelerator signal A in one cycle, is gradually reduced. The object of the present invention is to provide a control method that reduces the load (reduces the traveling speed) by causing the vehicle to move, and stops traveling only when the load exceeds a limit value.

The means adopted by the present invention to solve the above problem is to adjust the duty ratio, which is the output ratio of the accelerator signal that drives the wheel drive motor and the other signal that cuts off the drive.
Controlling the rotation speed of the motor by changing the ratio,
In an electric vehicle that controls running conditions, if the signal value of a temperature sensor that detects the temperature of electronic components or the motor is lower than a reference value, the motor is driven and controlled at a predetermined duty ratio set by the operation input, and the Until the signal value of the temperature sensor exceeds the reference value and reaches the limit value, the motor is driven and controlled at a correction duty ratio that reduces and corrects the predetermined duty ratio in accordance with the increase in the signal value, and This method of controlling the drive of an electric vehicle during overload is characterized by stopping the output of an accelerator signal when the signal value of the temperature sensor exceeds a limit value.

[For production]

The present invention compares the detection signal value of the temperature sensor as a reference value while the electric vehicle is running.

0 If the signal value of the temperature sensor is less than the reference value, normal drive control is performed based on the predetermined duty ratio set by the operation input. Also, if the signal value of the temperature sensor is equal to or higher than the reference value, overload control operation is performed. This overload control operation is performed at a predetermined ratio less than (2) with respect to the predetermined duty ratio. If the signal value of the temperature sensor exceeds the limit value, the output of the accelerator signal A is stopped, and the vehicle stops running.

Therefore, in the electric vehicle of the present invention, the speed can be controlled step by step until the temperature of the electronic components reaches a dangerous temperature from a temperature that requires monitoring, and there is no immediate stoppage. In other words, it is possible to perform a gentle stop, and the driver can recognize that the stop is due to overload operation, and can distinguish it from a failure.

〔Example〕

The control method of the present invention will be explained below based on the flowchart shown in FIG. 1.

Regarding the drive control circuit of the electric vehicle, the present applicant ■ This is the same as the one shown in Figure 3, which was developed earlier.

As shown in FIG. 1, in this embodiment, first, while the electric vehicle 1 is running, it is detected whether or not it is in an overload operating state. To detect whether or not an overload operation is occurring, the temperature near the electronic components such as the transistors 6 and 7 is measured by the temperature sensor 24, and the measured signal value is set at 48°, for example.
This is done by comparing with standard values such as C. If the signal value is below the standard value, it is normal driving and the CPU 4
controls the rotation of the wheel drive motor 5 at a predetermined duty ratio Y that is preset according to the throttle opening degree, the position of the speed changeover switch, etc. Note that the duty ratio is the rate at which the accelerator signal A is output in one cycle (for example, 25 m5), and the unit is %.

On the other hand, if the signal value measured by the temperature sensor 24 is higher than a reference value such as 48°C, it means that the electronic components are abnormally heating up, and at the same time, the motor 5 is also heating up. Therefore, it is determined that there is an overload operation condition. As described above, if this condition is left untreated, it may lead to damage to electronic parts or burnout of the motor 5. Therefore, in this embodiment, based on the instructions from the CPU 4,
As will be explained next, overload control operation is performed.

Overload control begins by detecting the value X of the current signal value of the temperature sensor 24 within the allowable range of (limit value - reference value). In other words, we are trying to find . However, the limit value here refers to the limit temperature of electronic components, such as 53° C., for example. In this way, after finding X based on the fi1 formula, the
is substituted into the following equation (2) to obtain a newly set correction duty ratio y.

y=default duty ratio X(1-X)...(2
) After that, it is determined whether the signal value measured by the temperature sensor 24 is greater than or equal to the limit value. If the signal value is less than the limit value, the CPt 14 outputs the corrected duty ratio y obtained from equation (2) above as a control signal for the wheel drive motor 5, and gradually reduces the rotation speed. The running speed of the electric vehicle 1 is reduced. In other words, the operation is controlled to reduce the average current value flowing to the wheel drive motor 5 to gradually reduce the load, thereby reducing the heat generation temperature of the electronic components and the abnormal heat generation temperature of the motor 5.

Operation control using this corrected duty ratio y is performed until the signal value of the temperature sensor 24 reaches the limit value.

That is, it is performed within the permissible range from the reference value to the limit value. When the signal value of the temperature sensor 24 approaches the limit value, the corrected duty ratio y becomes close to 0, the average current value flowing to the wheel drive motor 5 becomes smaller, and the electric vehicle 1 gradually approaches the stopping speed. Become. In addition, when creating this corrected duty ratio y, by inputting and calculating the corrected duty ratio that was previously temperature-corrected as the default duty ratio, changes in the duty ratio due to temperature rise can be calculated in a quadratic curve. It is also possible to change it.

4 During such overload control operation, temperature sensor 2
If the signal value of No. 4 exceeds the limit value, the driving transistor 6, braking transistor 7, etc. will be short-circuited or open-circuited, resulting in a runaway state. Therefore, in this case, the correction duty ratio y is set to 0 in order to output only the brake signal B to the motor 5. Unless the driver returns the accelerator to neutral,
The above-mentioned y=o is output continuously so that the vehicle does not move even if the accelerator is opened. In other words, the system is prevented from returning to an overload operating state.

In this embodiment, the pulses in one cycle are divided into an accelerator signal A, a brake signal B, and a neutral signal N.
However, except for the brake signal B, it is also possible to operate a mechanical brake device for braking operation. Further, the pulse formation method may be an analog format in which a reference wave oscillator that outputs a sawtooth wave is compared with a command voltage from an operation input to output a drive pulse (accelerator signal). In this case, the signal from the temperature sensor 24 is 5. The command voltage may be corrected based on the value.

In this embodiment, such an overload control operating state is displayed on a display device 26 using an LED shown in FIG. 3. For example, from the moment the signal value of the temperature sensor 24 exceeds a reference value and the state shifts to the overload control operation state, all the light emitting diodes LEn of the display device 26 are made to blink to indicate that the overload control operation state is in progress. ing. If the value of the corrected duty ratio y is large, the blinking interval is increased, and if the value of y is small, the blinking interval is decreased to determine which stage the current overload control operation is in. is displayed.

Note that the display may be performed by sound, or it is also possible to use sound and light emitting display in combination.

〔Effect of the invention〕

As explained above, in the present invention, if the overloaded operation condition such as on a slope is left as it is, a short circuit accident or open failure due to abnormal heat generation of electronic components etc. will occur, resulting in a runaway condition, so it is necessary to avoid this. To achieve this, the temperature of the electronic components is measured using a temperature sensor, and the duty ratio is corrected and controlled according to the measured signal value, thereby performing stepwise overload control operation. If the signal value of the temperature sensor exceeds the limit value, only brake signal B is output, forcing the electric vehicle to stop regardless of accelerator operation, thereby protecting the circuit and ensuring safe driving. ing.

This allows the driver to know that the traveling speed is gradually decreasing due to overload, and to distinguish it from a malfunction or the like, so that the driver is not confused. Furthermore, since the running speed gradually decreases depending on the overload condition, it is possible to stop slowly and safely.

[Brief explanation of drawings]

FIG. 1 is a flow chart diagram showing overload control of the present invention;
Figures 2 to 4 relate to an electric vehicle previously developed by the applicant; Figure 2 is a perspective view showing the entire electric vehicle; Figure 3 is an electric circuit diagram showing a drive control circuit; FIG. 4 is a time chart showing the control pattern of the wheel drive motor. 1... Electric vehicle 4... CPU7 5... Wheel drive motor

Claims (1)

[Claims] 1. An accelerator signal that drives the wheel drive motor;
A signal from a temperature sensor that detects the temperature of electronic components or the motor in an electric vehicle that controls the rotational speed of the motor and controls the running state by changing the duty ratio, which is the output ratio with other signals that cut off the drive. If the value is below the reference value, the motor is driven and controlled at a predetermined duty ratio set by the operation input, and this signal value is maintained until the signal value of the temperature sensor exceeds the reference value and reaches the limit value. The motor is driven and controlled with a corrected duty ratio that reduces the predetermined duty ratio in response to an increase in temperature, and when the signal value of the temperature sensor exceeds a limit value, output of the accelerator signal is stopped. A drive control method for electric vehicles during overload.