JPS5928124B2 - Electric car speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for controlling the running speed of an electric vehicle.

Generally, electric vehicles control running speed by changing the rotational speed of the motor depending on how much the accelerator is pressed, and direction is controlled by bundle operation.

FIG. 1 shows a schematic configuration of a speed control device for a battery forklift.

DC power is supplied from battery B to DC motor DM,
The average voltage is transferred to the chopper C that forms the main circuit of the speed control device.
It is controlled by the on/off ratio (conductivity) of H.

The on/off ratio of the chopper CH is determined by obtaining a controlled timing signal from a chopper control circuit LU which receives as input the output voltage of a potentiometer POTA linked to the accelerator.

In addition, ACl is a contact that enables the chopper control port gLU to operate when the accelerator is depressed, and MT12MT2 switches the current polarity of the field winding F of the motor DM to move the vehicle forward.
The contactor MS for switching reverse movement is a contactor for directly driving the motor DM instead of the chopper CH.

Such a speed control device changes the on/off ratio of the chopper CH according to the amount of accelerator depression, and controls the motor D.
The rotational speed of M and thus the running speed of the electric vehicle are controlled.

Therefore, in conventional speed control, the speed of the electric vehicle when turning is controlled only by the amount of depression of the accelerator, so if the speed when turning is too high, there is a risk of the vehicle rolling over.

SUMMARY OF THE INVENTION An object of the present invention is to provide a speed control device that can automatically regulate the speed of an electric vehicle, particularly the turning speed, to an appropriate value and prevent accidents such as rollover.

Examples of the present invention will be described in detail below.

In FIG. 2, the AC speed generator G is directly connected to the shaft of the motor DM or to a portion that can detect the speed of the vehicle.

The diode bridge Ref and the capacitor C1 rectify and smooth the output current of the generator G, and obtain a DC voltage vN corresponding to the speed of the electric vehicle in the capacitor C1.

Note that in order to obtain the DC voltage vN, the AC speed generator G is not limited to the AC speed generator G, and may be replaced by a DC generator or a speed detector using an electronic frequency/pulse method.

Next, a potentiometer POT with center tap
The detected DC voltage vN is applied to S.

As shown in Fig. 3, this potentiometer POTs has four terminals with a center tap Tc at the midpoint of the resistance line, and its shaft is linked to the operation of the bundle (steering wheel), and the movable contact is activated when the bundle operation angle is zero. Center tap T.

The movable contact rotates in the left and right taps TA and TB directions according to the bundle operation angle (turning radius), and the output tap To connected to the movable contact generates a partial pressure ratio output according to the bundle operation angle. It is configured to obtain Vo.

In this way, the turning radius of the electric vehicle is detected by the potentiometer POTs, and the applied voltage is set to the DC voltage VN, thereby controlling the output voltage Vo of the tap To based on the vehicle speed.

As shown in FIG. 3, the potentiometer POTs is provided with conducting wires instead of resistance wires at an angle of .theta. from the center tap TC to the left and right to provide a dead zone with respect to the bundle operation angle.

Also, the center tap Tc of potentiometer POT8
is grounded via resistor Rb.

This resistor Rb applies a voltage corresponding to the traveling speed to the tap To of the potentiometer POTS even when the vehicle is traveling straight, and is also used to regulate the maximum speed when the vehicle is traveling straight.

Next, the DC amplifier Amp amplifies the output voltage VO of the potentiometer ηTs to an appropriate level,
Transistor Tr1. It has a two-stage directly connected circuit configuration of Tr2.

Note that the DC amplifier Amp has a dead zone due to the Zener diode Z1 provided in its input stage, and is configured to clarify the detection level of the output voltage VO at the tap To, but the Zener diode Z1 may be omitted.

The output voltage of the DC amplifier Amp and the output voltage of the potentiometer POTA shown in FIG. As VS, the higher voltage of both the output voltages of the DC amplifier Amp and the potentiometer POTA is selected and output.

Note that the output voltage of the potentiometer POTA decreases as the accelerator pedal is depressed.

The timing signal generator O8C controls the on/off ratio of the chopper CH according to the level of the output voltage vs, and obtains a control signal that lowers the rotational speed of the motor DM when Vs is high.

With the speed control device having such a configuration, when the bundle operation angle of the electric vehicle is near zero, the movable contact of the potentiometer POTS is located near the center tap Tc, and its output voltage Vo is proportional only to the rotational speed of the motor. At normal straight-line speed, the output voltage Vo is low and the output voltage of the DC amplifier is low, so the output voltage Vs of the transistor Tr3 matches the output voltage of the potentiometer POTA linked to the accelerator, and as a result, if the load is constant. For example, the speed of the vehicle corresponds to the amount of depression of the accelerator.

Then, during an acceleration operation in which the accelerator is depressed a lot and the output voltage of the potentiometer POTA linked to the accelerator decreases while driving straight, the increase in the vehicle speed detection voltage vN accompanying the increase in vehicle speed at this time is equal to the voltage drop across the resistor Rb. This voltage Vo appears as an increase in the output voltage Vo of the potentiometer POT8 due to the increase in voltage Vo, and this voltage Vo is amplified by the DC amplifier Amp and appears as the anode voltage of the diode DS.

The anode voltage of the diode D8 is compared with the output voltage of the potentiometer POTA by the diodes DS and DA, and the higher level voltage is taken out as the output vs of the transistor Tr3. When the anode voltage rises and the voltage becomes higher than the output voltage of the potentiometer POTA, the output voltage Vs of the transistor Tr3 is regulated by the anode voltage of the diode DS, and the acceleration of the motor is caused by the rise of the output pot of the potentiometer POTs, that is, the output of the transistor Tr3. ■The above 1 of s results in negative feedback control that controls the motor to the deceleration side, resulting in constant speed rotation control at the maximum speed determined by resistance Rb, etc., and even if the accelerator is depressed too much, the speed will exceed the critical speed. suppress.

Then, the bundle is cut to the left or right in the state of straight-line maximum speed driving, and the bundle operation angle is set by the potentiometer POT.
When θM or more is reached on s, the output voltage Vo rises in accordance with the bundle operation angle even when the detection voltage vN by the speed generator G is constant.

As a result, the output voltage Vs of the transistor Tr3 increases, so the rotational speed of the motor is decreased.

The degree to which the rotational speed of the motor is lowered corresponds to the bundle operation angle, and the maximum speed of the vehicle is regulated in accordance with the bundle operation angle regardless of the amount of depression of the accelerator.

This control characteristic is shown in FIG.

Here, even when regulating the maximum speed of the vehicle by the bundle operation angle, the factor of vehicle speed is introduced in comparison with the amount of accelerator depression. ), the output voltage Vo becomes low when the vehicle speed decreases due to the heavy load, and even though the output voltage of the potentiometer POTA decreases due to the increase in the amount of accelerator pedal depression, the motor speed control is controlled by the output voltage of the potentiometer POTS. Even under heavy loads, the amount of accelerator depression can be increased to the high speeds regulated by the bundle operation angle without being restricted by the bundle operation angle, thereby preventing a drop in driving performance under heavy loads.

In addition, in the above embodiment, the potentiometer POTs
4 shows the case where a dead zone is provided at the center tap Tc portion, but if the dead zone is not provided, the characteristics within θM also correspond to the bundle operation angle, as shown by the dotted line in FIG.

In addition, if the characteristics of the vehicle's maximum speed limit value with respect to the bundle operation angle (turning radius) are determined by a curve determined by the vehicle's maximum load capacity, center of gravity position, etc., the potentiometer i:'
The partial pressure ratio to the rotation angle of o'rs can be set to a desirable characteristic, and furthermore, the potentiometer po'rs can be replaced with an arithmetic circuit.

Furthermore, as shown in FIG. 1, a speed control device equipped with a bypass contactor MS can also control its falling off.

FIG. 5 shows one embodiment of this, in which the rise in the output voltage of the DC amplifier N exceeds the Zener voltage of the Zener diode Z2 turns on the thyristor 5CRQ and turns on the transistor Tr.

is turned on, and the thyristor 5CRD is held in the off state by the charging voltage of the capacitor C2 while the thyristor 5CRD is on.

This causes the bypass contactor MS to fall off, and this separation is maintained until the output voltage of the DC amplifier Amp drops (that is, the vehicle becomes below the regulated maximum speed).

Note that Ac1 is a contact for turning on the MS.

It can also issue a vehicle overspeed warning.

FIG. 6 shows an example of this, and the resistor Rb in FIG.
When the terminal voltage of the Zener diode Z3 becomes higher than the Zener voltage of the Zener diode Z3, the transistor Tr3 is turned on to drive a warning light or a buzzer.

Note that the input to the Zener diode Z3 is not limited to the terminal voltage of the resistor Rb, but may be the output voltage of the DC amplifier Amp.

Further, in the embodiment, the output voltage of the potentiometer POTs is changed by changing the vehicle speed feedback amount, but the feedback gain may be kept constant and the speed limit setting amount may be linked to the bundle operation using a potentiometer similar to the POTs.

Also, as explained in the battery forklift circuit,
It can be applied not only to this but also to motors powered by AC power.
The chopper can also be applied by replacing it with an inverter or the like.

As explained above, the speed control device for an electric vehicle according to the present invention automatically regulates the maximum speed of the vehicle according to the bundle operation angle, thereby preventing accidents such as vehicle rollover. It can be prevented.

Furthermore, since the vehicle speed is taken into account when comparing the bundle operation angle and the amount of accelerator depression, there is no reduction in driving performance under heavy loads.

In addition, the present invention linearly regulates the maximum speed in accordance with the turning radius, so even if the accelerator is set to maximum, the vehicle speed will increase or decrease gradually as the turning radius increases or decreases, which helps prevent cargo from collapsing and reduces driver fatigue. effective.

Furthermore, when driving at a speed below the maximum speed regulated by the turning radius, the speed can be controlled arbitrarily by changing the amount of accelerator pedal depression, making it possible to control the speed over a wide range.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram illustrating a conventional speed control device, Fig. 2 is a circuit diagram showing an embodiment of the present invention, Fig. 3 is a diagram showing the potentiometer POT8 in Fig. 2, and Fig. 4 is a diagram illustrating the present invention. A bundle operation angle-motor maximum speed characteristic diagram for explaining the invention, FIG. 5 is a circuit diagram showing an example of bypass contactor fall-off control, and FIG. 6 is an example of vehicle overspeed warning. It is a circuit diagram. G: AC speed generator, Ref: diode bridge, POTs, POTA: potentiometer, Rb: resistor, Zl, Z2.
Z3... Zener diode, Amp...
...DC amplifier, Ds, DA...diode,
O20...Dimming signal generator, Trl,
Tr2. Tr3, Tr4, Tr4, T
[, -++++ h transistor, 5CRQ, 5CRD
...Sirisk, C1, C2...Capacitor, MS...Bypass contactor, L...
...Warning light, CH...Chopper, DM...
····motor.

Claims (1)

[Claims] 1. A turning radius detector that detects the turning radius of the electric vehicle using a corresponding voltage signal.A turning radius detector that detects the traveling speed of the electric vehicle using a corresponding voltage signal to control the detection amount of the turning radius detector. When a speed detector and a voltage signal detected corresponding to the amount of accelerator depression are larger than a detection amount of the turning radius detector controlled by the speed detector, the detected amount is used to control the running speed of the electric vehicle. and a selection circuit that sets the accelerator depression amount detection signal to a traveling speed control signal of the electric vehicle when the accelerator depression amount detection signal is smaller than the detection amount, and sets the maximum speed of the electric vehicle as described above. A speed control device for an electric vehicle, comprising a control device that regulates the amount detected by a turning radius detector. 2. Claim 1, wherein the control device issues a warning when the electric vehicle reaches the maximum speed specified by mIJ.
A speed control device for an electric vehicle as described in Section 1. 3. The speed control device for an electric vehicle according to claim 1, wherein the control device controls the bypass contactor to fall off when the electric vehicle reaches a regulated maximum speed.