JPS6120801Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an electric vehicle control device, and particularly to an electric vehicle control device suitable for preventing damage to equipment due to fault current.

Switching between forward and reverse in an electric vehicle using a DC motor as the main motor is performed by changing the direction of rotation of the main motor.There are two ways to do this: changing the direction of the armature current;
There are some that change the direction of the field current.

The present invention relates to an improvement in an electric vehicle in which the direction of armature current is switched by connecting a reverser switch to the armature in a bridge-like manner.

[Prior art]

FIG. 1 shows an example of a main circuit connection diagram for switching the direction of the armature current described above to switch the electric vehicle between forward and reverse motion.

In FIG. 1, 1 is an overhead line, 2 is a pantograph, 3 is an overcurrent relay, and 4 is a switch or disconnector that disconnects the main motor circuit from the overhead line, and has the ability to cut current. Reference numerals 5 to 8 indicate reversing switches for changing the direction of armature current, which are connected in a bridge manner to the armature 9 of the main motor. These reversing switches typically do not require current source or disconnect capabilities. 10 is a field of the main motor, 11 is a series resistor of the main motor, 12 to 14 are contactors for gradually shorting the series resistor 11, 15 is a grounding wire, 1
6 is a control circuit power supply, 17 and 18 are command switches operated by the driver, and 17 is closed during forward driving;
18 is closed during reverse driving. Reference numeral 19 indicates an operating coil for turning on the forward-side reversing gear switches 5 and 6, 20 an operating coil for turning on the reverse-side reversing gear switches 7 and 8, 21 and 22 interlocking contacts for the reversing gear, and 23 for overcurrent relay 3. An interlocking contact, 24 indicates the operating coil of the disconnector 4, and 25 indicates the control circuit ground wire.

First, when starting and accelerating an electric car in the forward direction,
Close the command switch 17. As a result, the operating coil 19 is energized and the reverser switches 5 and 6 are closed. On the other hand, since the command switch 18 is open,
The operating coil 20 is not energized and the reverser switches 7, 9 are open.

When the reversing gear is in the forward position in this way, the shroud breaker operating coil 24 is energized, the shroud breaker 4 is closed, and the current is transmitted from the overhead line 1 to the pantograph 2, the overcurrent relay 3, the shingle breaker 4, and the reversing switch. switch 5, armature 9,
Reverser switch 6, field 10, series resistor 11,
Flowing to ground 15, the electric car starts and accelerates. As the speed increases, the series resistor 11 increases the contactor 12,1
3 and 14, the voltage applied to the main motor is increased to control the speed.

Next, when starting and accelerating the electric vehicle in the reverse direction, the command switch 18 is closed. As a result, the current coil 20 is energized and the reverser switches 7, 8 are closed. On the other hand, since the command switch 17 is open, the operating coil 19 is not excited, and the reverser switches 5 and 6 are open.

Here, as in the case of forward movement, the shield breaker 4 closes, and the current flows from the overhead wire 1 to the pantograph 2, the overcurrent relay 3, the shield breaker 4, the reversing switch 7, the armature 9, the reversing switch 8, Field 10, series low resistor 1
1. The electric car starts and accelerates as it moves to the maneuvering area 15.

In this case, since the current flowing through the armature 9 flows in the opposite direction to that in the forward movement, the armature rotates in the opposite direction, and the electric vehicle starts and accelerates in the reverse direction.

As the speed increases, the series resistor 11 is gradually shorted by the contactors 12, 13, 14, increasing the voltage applied to the traction motor to control the speed.

Incidentally, such an overcurrent in the main circuit is detected by the overcurrent relay 3 and the shield breaker 4 is opened. Therefore, reverser switches 5 to 8
is considered not to require that much overcurrent capability.

However, an accident may occur in which parts of the reverser switches 5 to 8 are welded or damaged, which may adversely affect other electrical equipment.

[Purpose of invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to prevent welding and melting of a reverser switch bridge-connected to an armature, as well as the accompanying negative effects on equipment. is to provide.

[Key points of the idea]

Here, the principle of the present invention will be explained with reference to FIG.

Overcurrent in the armature circuit is caused by a sudden rise in overhead wire voltage,
This can occur due to ground faults caused by motor flashover. However, the latter causes a much larger overcurrent than the former.

Now, when the electric car is starting and accelerating forward, a flash over occurs on the commutator of the armature 9 for some reason, and eventually a ground fault occurs, which causes the electric car to be disconnected from the overhead wire 1 to the pantograph 2, to the overcurrent relay 3, to the overcurrent relay 3, etc. An excessive current flows through the disconnector 4, the reversing switch 5, and the armature 9 to the ground 15. Since the resistance between the armature 9 and the ground 15 due to a ground fault is very small, this current should bypass and flow from the armature 9 to the ground 15, and almost no current should flow to the reversing switch 6.

When the electric vehicle is accelerating backward, an excessive current flows from the overhead wire 1 through the pantograph 2, the overcurrent relay 3, the shield breaker 4, the reversing switch 7, and the armature 9 to the ground 15. In this case as well, since the current flows from the armature 9 to the ground 15, almost no current should flow to the reversing switch 8.

On the other hand, if such a ground fault accident occurs,
The breaker 4 opens the main motor circuit by the operation of the overcurrent relay 3, but it is difficult to instantly cut off the excessive current in the event of a ground fault.

Therefore, an excessive current flows only through the reversing gear switch 5 when moving forward, and only through the reversing gear switch 7 when moving backward for a considerably long time. Normally, reverser switches 5 to 8 use switches with the same so-called overcurrent withstand capacity, which prevents welding and erosion due to overcurrent, and has an overcurrent withstand capacity that can withstand the overcurrent in the event of a ground fault. It is normal to have no.

For this reason, there is a drawback that only the reversing switch 5 or 7 will be welded or damaged, and if an electric car experiences a ground fault in the main motor near a substation, only the reversing switch 5 or 7 will be damaged. Because a fault current that far exceeds the overcurrent withstand capacity flows, not only the reverser switch 5 or 7 may be welded or eroded, but also the arc generated due to the welding or erosion may damage other devices installed nearby. Even electrical equipment was burned out to the point where it could no longer be used again.

It is conceivable to simply increase the size of all the reversing switches to increase the overcurrent withstand capacity, but this would result in a larger and more expensive device.

Therefore, the present invention provides an electric vehicle equipped with a reversing device switch connected in a bridge-like manner to the armature of the traction motor, and a means for detecting overcurrent and disconnecting the armature circuit from the overhead line. Among the equipment switches, the overcurrent withstand capacity of the switch connected to the overhead line side with respect to the armature is made larger than the overcurrent withstand capacity of the switch connected to the ground side.

In this way, even if the aforementioned ground fault occurs, it is possible to prevent welding and melting of the reverser switch as well as damage to other electrical equipment.

[Example of idea]

An embodiment of the present invention will be described below with reference to FIG. In this figure, the same parts as in FIG. 1 are given the same reference numerals.

The difference from FIG. 1 is that a reversing switch 5a is provided in parallel with the reversing switch 5, which is linked to the operating coil 19 and has the same constant as the reversing switch 5a, and an operating coil 20 is provided in parallel with the reversing switch 7. A reversing device switch 7a having the same rating as the reversing device is provided which is interlocked with the reversing device.

In FIG. 2, when starting and accelerating the electric vehicle in the forward direction, the command switch 17 is closed. As a result, the operating coil 19 is excited, and the reverse operating coil 5,
5a and 6 are closed. This works in the same way as in the case of FIG. 1, without changing the direction of the current in the armature 9.

Further, when starting the electric vehicle in the reverse direction, the command switch 18 is closed. As a result, the operating coil 20 is energized and the reverser switches 7, 7a and 8 are closed. This works in the same way as in the first case without changing the current direction of the armature 9.

Here, when the main motor is in forward motion, excessive current when a ground fault occurs passes from the overhead wire 1 through the pantograph 2, the overcurrent relay 3, and the breaker 4, and the reverser switch 5, 5a. are passed in parallel to armature 9,
Flows to ground 15.

Similarly, when starting reverse, the excessive current flows from the overhead wire 1 through the pantograph 2, the overcurrent relay 3, and the breaker 4, and the reverser switch 7, 7a.
flows in parallel to the armature 9 and ground 15.

In addition, almost no current flows through the reverser switch 6 or 8 in either forward or reverse travel.

Therefore, according to this embodiment, the excessive current flows through the reversing device switches 5 and 5a in parallel when moving forward, and flows through the reversing device switches 7 and 7a in parallel when moving backward. The current flowing through the reversing switch is half that of the conventional case, and by being able to withstand twice as much fault current as the conventional case, it is possible to prevent burnout of the reverser switch.

FIG. 3 shows another embodiment of the present invention, and is a wiring diagram when main motors are connected in series and parallel. In this figure, the same parts as in FIG. 2 are given the same reference numerals, and the control circuit parts shown in the lower halves of FIGS. 1 and 2 are omitted.

The differences from Fig. 2 include the addition of a traction motor circuit B similar to the traction motor circuit in Fig. 2, the provision of a contactor 12a in parallel with the contactor 12 of the traction motor circuit B, and the addition of a traction motor circuit B similar to the traction motor circuit in Fig. 2. Circuit A and main motor circuit B
Switch 2 for switching between series and parallel
contactors 12 and 12a and changeover switches 27 and 27.
The same switches are connected in parallel.

When connecting main motor circuits A and B in series,
The changeover switch 26 is closed, and the changeover switches 27, 2
7a and 28 are open.

Also, when connecting main motor circuits A and B in parallel, selector switches 27, 27a, and 28 are closed;
The changeover switch 26 is open.

In this embodiment, when the main motor circuits A and B are connected in parallel and the contactors 12 and 12a are closed,
If the main motor of main motor circuit B causes a ground fault,
The fault current passes from the overhead wire 1 to the pantograph 2, overcurrent relay 3, and breakout switch 4, and then to the changeover switch 2.
7 and 27a in parallel, passes through the contactors 12 and 12a of the main motor circuit B in parallel, and further the field 10
The current flows through the reverser switches 5 and 5a in parallel to the armature 9 and ground 15.

Therefore, in this embodiment, when the traction motor of traction motor circuit B causes a ground fault, traction motor circuit B
In addition to the reversing switch 5, 5a, the contactor 12,
12a and the changeover switches 27, 27a can be prevented from burning out.

In addition, in FIGS. 2 and 3, reverser switches 5 and 5a, 7 and 7a, and in FIG. 3, changeover switches 27 and 27a, and contactors 12 and 12a.
may be of different overcurrent capability,
In this case as well, the same effects as described above can be obtained.

Also, reverser switches 5 and 5a, 7 and 7a, changeover switches 27 and 27a, contactors 12 and 12a
It is also possible to replace each of them with a single one having increased overcurrent resistance, and in this case, the same effect as described above can be obtained.

[Effect of idea]

As explained above, according to the present invention, it is possible to prevent the welding and erosion of the reversing gear switch and the resulting adverse effects on electrical equipment placed in the vicinity thereof, using a small and inexpensive device.

[Brief explanation of the drawing]

Figure 1 is a wiring diagram showing a conventional electric vehicle control device.
FIGS. 2 and 3 are wiring diagrams of electric vehicle control devices showing different embodiments of the present invention. 1... Overhead line, 3... Overcurrent detector (relay),
4...Shiya disconnector, 5, 5a, 6, 7, 7a, 8...
...Reverser switch, 9... Main motor armature, 1
2, 12a, 13, 14...resistance short circuit contactor,
15... Ground wire, 26, 27, 27a, 28...
Changeover switch.

Claims (1)

[Claims for Utility Model Registration] 1. A reversing switch connected to the armature of the main motor in the form of a bridge, and means for detecting overcurrent in the armature and disconnecting the armature circuit from the overhead wire. An electric vehicle control device characterized in that, of the reversing switches, the reversing switch connected to the overhead line side of the armature has a larger overcurrent withstand capacity than the reversing switch connected to the grounding side. . 2. The electric vehicle control device according to item 1, wherein the overhead line side reverser switch is comprised of two parallel sets of switches having the same rating.