JPS6243404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric vehicle control device, and particularly to a control device that uses regenerative braking and plugging braking in combination, such as in a battery forklift.

In order to save power in electric vehicles such as battery lift trucks, it is desirable to adopt regenerative braking, that is, a method to obtain braking force by converting the rotational energy of the driving DC motor into electrical energy that charges the battery. . However, such regenerative braking alone cannot provide braking force at low speeds, so plugging braking, a method that switches the forward and backward contactors and supplies current in the reverse direction to obtain braking force, is often used in combination. .

An example of this braking braking system is disclosed in Japanese Patent Laid-Open No. 49-39719.

This control to shift from regenerative braking to plugging braking is performed when the flow rate of the chopper during regenerative braking is set to a certain value, approximately
The regenerative contactor was switched after detecting when the flow rate reached 70 to 100% and after reducing the chopper flow rate to 0%, that is, stopping the chipper operation. As a result, there is a period when the vehicle coasts during deceleration, making it impossible for the driver to feel a smooth deceleration.Also, since the electric braking period due to regenerative braking is short, the braking time until the vehicle speed reaches zero becomes longer. There was a drawback.

An object of the present invention is to provide an electric vehicle that can smoothly decelerate an electric vehicle and shorten the braking time by adding dynamic braking to regenerative braking to lengthen the electric braking period, while eliminating the drawbacks of the prior art described above. Provides control equipment.

To achieve this objective, the present invention provides that the flow rate of the chopper at the end of regenerative braking is a predetermined value, e.g.
After reaching 90% or more, Chiyotupa conduction rate becomes 100%.
A predetermined time beyond which the point is reached, e.g. 0.5 to 2
The present invention is characterized in that the operation of the chopper is left as it is without stopping for a second to mainly perform dynamic braking, and then it is switched to plugging braking.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 is a wiring diagram during regenerative braking in the main circuit of an electric vehicle to which the present invention is applied. The battery 1 is connected via a power line 2 and a power line 3 to a regenerative contactor 4, an armature 6 of a DC series motor 5, a current detection sensor 8, a forward contactor 9, a reverse contactor 10, a series field coil 7, and a Chiyotsupa 11
are connected in series. The regenerative contactor 4
is composed of an excitation coil 12 and a contact 13 that operates as shown by the solid line when the excitation coil 12 is energized. 14 is a freewheel diode,
15 is a plugging diode, 16 is a regeneration diode, and 17 is a pre-excitation resistor.

Now, with the forward/reverse contactors 9 and 10 switched to the solid line position shown in the figure, the regenerative contactor 4 is
When the excitation coil 12 is energized and its contact 13 is switched to the solid line position shown in the figure, when the chopper 11 is conductive, the regenerative contactor 4, pre-excitation resistor 17, reverse contactor 10, field coil 7, forward movement are connected from the battery 1 side. Contactor 9 and chipper 1
1 to the battery 1 side, the field coil 7 is energized, preliminary excitation is performed, and an induced voltage of the polarity shown is generated in the armature 6. This induced voltage causes a circuit from the armature 6 side to the armature 6 side through the current detection sensor 8, reverse contactor 10, field coil 7, forward contactor 9, chopper 11 and regeneration diode 16.
The field coil 7 is configured to promote the pre-excitation current.
A current flows through. In other words, a self-excitation effect also works.

As the induced voltage increases and the current increases in this way, the current will eventually flow only due to the self-excitation effect of the closed circuit. In this state, Chiyotsupa 11
When the current detection sensor 8, the backward contactor 10, the field coil 7, and the forward contactor are cut off, the magnetic energy stored in the induced voltage of the armature 6 and the inductance of the field coil 7 causes the current detection sensor 8, the reverse contactor 10, the field coil 7, and the forward contactor 9. Power is regenerated to the battery 1 in a circuit that passes through the freewheel diode 14, the battery 1, and the regeneration diode 16 to the armature 6 side, so that so-called regenerative braking is performed, and the electric motor 5
rotation speed decreases.

When the rotational speed of the motor 5 decreases to a certain value, even if the chopper current flow rate is increased, the current flowing through the armature 6 becomes smaller than the maximum limit value. to be held for a certain period of time. In this way, the current detection sensor 8, reverse contactor 10,
Field coil 7, forward contactor 9, chopper 11
Since current continues to flow in the circuit that passes through the regenerative diode 16 and reaches the armature 6, the energy consumed by the internal resistance of the motor 5 acts as a braking force, resulting in so-called dynamic braking. .

FIG. 2 is a block diagram for carrying out the above-described control. In FIG. 2, numerals 3, 11, and 12 are a power supply line, a chopper, and an excitation coil for a regenerative contactor, as in FIG. 1. Also, 18 is Axel,
19 is a current limiting circuit, 20 is a trigger circuit, 21 is a conductivity detection circuit, 22 is a timer circuit, 23 is a regeneration control determination circuit, 24 is a level comparison circuit, 25 is a chopper stop circuit, and 26 is a transistor.

The output signal of the accelerator 18 and the feedback signal of the current limiting circuit 19 corresponding to the signal from the current detection sensor 8 are compared, and the trigger circuit 20 is operated using this difference signal to control the chopper 11.
When the conduction rate of this chopper 11 reaches a certain value,
The conductivity detection circuit 21 detects this and outputs a detection signal to the timer circuit 22. This timer circuit 22
outputs an output signal after a certain period of time has elapsed since the detection signal is generated, and stops the regenerative braking operation. That is, the output signal of the timer circuit 22 is added as a difference to the output signal of the accelerator 18 that is input to the level comparison circuit 24, and the input signal of the level comparison circuit 24 is set to "L", and the transistor 26 is
becomes non-conductive. Therefore, the excitation coil 12 is de-energized, the contact 13 of the regenerative contactor 4 is switched to the position shown by the broken line in FIG. 1, and the regenerative braking operation is stopped.

The regeneration control determination circuit 23 is a circuit that determines whether or not to stop regeneration when the forward/reverse contactors 9 and 10 are switched.If it is determined that regeneration may be performed, the level comparison circuit 24 The input signal of the level comparison circuit 24 is kept at "H" without lowering the input output signal of the accelerator 18. Further, the chopper stop circuit 25 operates when the output signal of the level comparison circuit 24 changes from "H" to "L", outputs a signal to the trigger circuit 20, and operates the chopper until the regenerative contactor 4 is completely restored. This circuit stops the plugging operation and then performs the plugging operation.

The specific circuit configuration of the main part of the control block diagram of FIG. 2 is shown in FIG. 3. In this figure, the same reference numerals as in FIGS. 1 and 2 indicate the same or equivalent parts, and 27 is a constant voltage circuit, 28 is a constant voltage line, 29 is a D-type flip-flop, and 3
0 is a resettable monostable multivibrator, 3
1 and 32 are operational amplifiers, respectively.

Conventionally, as shown in Fig. 4a, at time _t1 when the chopper conduction rate reaches 90%, the chopper conduction rate is immediately reduced to 0%, that is, the chopper operation is stopped and the regenerative contactor is switched, and the switching is completed. Since the chipping operation was restarted at t ₂ and the plugging operation was performed, there was a period in which the vehicle coasted during deceleration, making it difficult for the driver to feel a smooth deceleration, and the electric braking period due to regenerative braking was shortened. As a result, the braking time until the vehicle speed reaches zero was longer.

On the other hand, according to the present embodiment, as shown in FIG. 4b, the current state remains unchanged even at the time point _t1 when the flow rate reaches 90%, and the predetermined time until the vehicle speed becomes almost 0 is maintained. Since the chopper operation is stopped and the regenerative contactor is switched for the first time at time t ₃ after τ has elapsed (mainly the time during which dynamic braking is performed), electric braking by dynamic braking is applied for a predetermined time τ (regenerative braking, dynamic braking is performed by plugging). The period during which the braking force is large compared to the braking becomes longer, and as a result, the braking time can be shortened. Furthermore, since the system switches to plugging at time _t3 when the vehicle speed is approximately 0, it is possible to give the driver a smooth feeling of deceleration. Thereafter, plugging braking is performed at time _t4 when switching of the regenerative contactor is completed, as in the conventional case.

As explained above, according to the present invention, regenerative braking is followed by regenerative braking to a low speed, and then plugging braking is performed, so that the electric vehicle can be decelerated smoothly and the vehicle speed can be reduced. The braking time until it reaches zero can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram during regenerative braking in the main circuit of an electric vehicle to which the present invention is applied, FIG. 2 is a block diagram of an electric vehicle control device according to an embodiment of the present invention, and FIG.
The figure is a specific circuit configuration diagram of the same control device, and FIGS. 4a and 4b are explanatory diagrams of control operations of the conventional device and the device of the present invention. DESCRIPTION OF SYMBOLS 1... Battery, 4... Regenerative contactor, 5... DC motor, 9... Forward contactor, 10... Reverse contactor, 11... Chopper, 12... Excitation coil of regenerative contactor, 18... Accelerator, 19... Current limiting circuit, 20... Trigger circuit , 21... conduction rate detection circuit,
22...Timer circuit, 23...Regeneration control circuit, 24...
Level comparison circuit, 25...Chopper stop circuit, 26
...transistor.

Claims (1)

[Claims] 1. In an electric vehicle control device that includes a driving DC motor connected in series to a DC power source, a forward/reverse switching device, and a chopper, the control device performs regenerative braking and plugging braking when switching between forward/reverse. A conduction rate detection device detects that the chopper conduction rate reaches a predetermined value at the end of braking, and a conduction rate detection device detects that the chopper conduction rate reaches a predetermined value and then stops the chopper conduction. and a device that outputs a chopper stop signal after a predetermined time period exceeding the point at which the regenerative braking rate reaches 100%, and after the chopper flow rate reaches the predetermined value at the end of regenerative braking, mainly performs dynamic braking for the predetermined time period, An electric vehicle control device characterized in that the braking is then switched to plugging braking.