JPH0445364Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of an overvoltage suppression device for an electric vehicle equipped with an overvoltage suppression device.

[Conventional technology]

So-called inverter-controlled vehicles, which use an induction motor as the main motor of a DC electric vehicle and are driven by an inverter, are on the verge of mass production.

This type of electric vehicle generally uses regenerative braking, similar to conventional Chiyotsupa trains.
However, regenerative braking loads are generally other power vehicles, auxiliary equipment, heating, etc. At night, when the density of vehicles decreases and the power running vehicle turns off during regenerative braking, the regenerative load may suddenly decrease and the voltage sent out from the regenerative vehicle may rise sharply. In this case, quickly detecting overvoltage and lowering the voltage is
This is preferable in order to prevent overvoltage accidents in the inverter and other equipment. For this reason, a thyristor-type overvoltage suppression device, which will be described below, is employed.

FIG. 2 is a simplified connection diagram of the main circuit of a conventional inverter-controlled vehicle. In the figure, 1 is a current collector, 2 is a current interrupter, and 3 is a current collector.
4 is a charging current limiting resistor for limiting the charging current of the filter capacitor, 4 is a contactor that shorts resistor 3,
5 is a filter reactor, 6 is a filter capacitor, 7 is an induction motor, 8 is an inverter, S ₁ to _{S 6}
indicates a thyristor, and D ₁ to _{D 6} indicate flywheel diodes. 9 is a current limiting resistor, 10 is a thyristor, P is the inverter high voltage side input terminal, U,
V and W are inverter output terminals, and G is a return wire.
Reference numeral 11 denotes an overvoltage suppressing device, which is composed of a resistor 9 and a thyristor 10. Control circuits for each device,
The voltage detection circuit is not shown.

In the figure, when the electric vehicle is running, current flows from the current collector 1. After closing the current interrupter 2, the current charges the filter capacitor 6 through the charging current limiting resistor 3 and the filter reactor 5. The voltage between the inverter high-voltage side input terminal P and the return line G is assumed to be _Vc . In order for the voltage V _c to become sufficiently high, ie, equal to the overhead line voltage, it is sufficient to wait approximately three times the time constant of the charging circuit. Generally, the contactor 4 is closed after waiting approximately this amount of time. The filter reactor 5 and the filter capacitor 6 prevent a large alternating current component from being included in the inflow current from the overhead contact line. Furthermore, the filter capacitor 6 prevents sudden fluctuations in the voltage _Vc for stable operation of the inverter 8. Inverter 8 is
This is called a voltage source inverter. The details of the operation are well known and will therefore be omitted.

Also, during regeneration, the inverter high voltage side input terminal P
The current flows further toward the current collector 1. When the regenerative load suddenly decreases, the voltage V _c rises rapidly. This voltage V _c is detected, the thyristor 10 of the overvoltage suppression device 11 is turned on, current is caused to flow through the current limiting resistor 9, and the voltage V _c is lowered.
The current flowing through the resistor 9 is detected to indicate that 0 is ignited, or the control circuit detects that the thyristor 10 is ignited, and the circuit breakers 2 and contactors 4 are opened, and the inverter 8 is stopped at the same time. and stop regeneration.

By stopping the inverter 8 and opening the current interrupter 2, the current flowing to the thyristor 10 decreases,
Finally, thyristor 10 disappears.

[Problem that the invention attempts to solve]

In the overvoltage suppression device for electric vehicles having such a configuration, when the residual voltage of the induction motor 7 is large, the voltage full-wave rectified by the diodes D ₁ to _{D 6} of the inverter 8 is connected to the inverter high-voltage side input terminal P and the return line G. The current applied during this period and limited by the current limiting resistor 9 of the overvoltage suppressor 11 may continue.
When the rotational speed of the induction motor 7 decreases, that is, when the speed of the electric car decreases, the residual voltage decreases, and the current that flows thereby becomes less than the holding current of the thyristor 10.
Thyristor 10 can be turned off.

By the way, a sudden decrease in regenerative load only happens occasionally and is not an accident, so even if the thyristor 10 is fired to suppress overvoltage,
If the thyristor 10 remains ignited when the current interrupter 2 is turned on again when the contactor 4 is closed, a large current will flow through the resistor 9 again after the contactor 4 is closed, which is undesirable.

To give an example, the overhead line voltage is 1500V, charging current limiting resistor 3 is 30Ω, resistor 9 is 3Ω,
The initial charging current of the filter capacitor 6 is 50A, and the current flowing to the resistor 9 when the contactor 4 is closed is 500A.

The residual voltage of the induction motor 7 varies depending on the rotation speed, but is generally several volts or less. However, since the holding current of the thyristor 10 is 0.1 to 1 A or less, the value of the resistor 9 is a value of several ohms for the purpose of lowering the voltage _Vc , so even if the residual voltage is several volts, Thyristor 10 may not self-extinguish.

Thus, the thyristor 1 of the overvoltage suppressor 11
Once 0 is activated, the current interrupter 2 is opened. Current interrupter 2
Whether to control the regenerative braking to be applied again immediately after the brake is opened, or to leave the regenerative braking unapplied until the brake is released to avoid immediate overvoltage, is a design choice and circuit configuration. Good luck, but
When I tried to power up again, thyristor 10 was still on.
It is inconvenient that the light remains lit. In lines with high traffic density, it is undesirable to force trains to slow down unnecessarily. Therefore, after the current interrupter 2 opens, there is a need for a method that can quickly extinguish the thyristor 10 with a simple additional device or without adding any additional device.

The present invention has been made for this purpose.

[Means for solving problems]

In order to achieve the above object, the present invention provides an overvoltage suppression device in which a normally closed contactor, a resistor, and a thyristor are connected in series between the DC power source and the return wire of an inverter of an inverter-controlled vehicle using an induction motor. By simply adding a small contactor with almost no short-term rated breaking capacity, it is possible to resume powering at any time even after the overvoltage suppression device has been activated.

Hereinafter, the present invention will be explained along with its operation with reference to the drawings.

〔Example〕

FIG. 1 is a simplified main circuit connection diagram showing one embodiment of the device of the present invention. In the figure, the same reference numerals as in FIG. 2 indicate the same equipment, and redundant explanation will be omitted here. 11' is an overvoltage suppression device according to the present invention;
12 is a normally closed contactor. The difference from FIG. 2 described above is that the overvoltage suppressing device 11' according to the present invention has a normally closed contactor 12 connected in series with a resistor 9 and a thyristor 10.

In the figure, if the resistor 9 of the overvoltage suppression device 11' is 3Ω as described above, and the voltage V _c at the time of overvoltage detection is 1800V, the resistor 9 and the thyristor 10 when the thyristor 10 is fired are The current flowing through the induction motor 7 is a large current of 600 A, but since the current breaker 2 is immediately opened and the inverter 8 is also stopped, the current immediately decreases to a value determined by the residual voltage of the induction motor 7. If the contactor 12 is opened at this time, the voltage and current are low, so the disconnection force is extremely light. Once the contactor 12 is opened, the residual voltage is low even if the contactor 12 is turned on again immediately, and the thyristor 10
If no gate signal is applied, the thyristor 10 remains turned off.

By making the contactor 12 normally closed, the coil of the contactor 12 only needs to be energized for a short time when the current interrupter 2 is opened and the inverter is stopped after the thyristor 10 operates, and the coil Thermal ratings for short periods of time are also sufficient. Furthermore, even if this coil is disconnected, it will not affect the overvoltage suppression function and will not affect operation when no overvoltage is detected. Both coil breakage failures and contact welding failures can be said to be fail-safe, as if this contactor had not existed.

[Effect of idea]

As mentioned above, according to the present invention, by simply adding a small contactor with almost no short-time rated breaking capacity, it is possible to restart the train at any time even after the overvoltage suppressor has activated, thereby improving the train's performance. The effect of on-time operation is enormous.

[Brief explanation of drawings]

FIG. 1 is a simplified contact diagram of the main circuit showing one embodiment of the device of the present invention, and FIG. 2 is a simplified connection diagram of the main circuit of the conventional device. 2... Current interrupter, 3... Charging current limiting resistor, 4
...Contactor, 5...Filter reactor, 6...
Filter capacitor, 7... Induction motor, 8...
Inverter, 11, 11'...overvoltage suppressor,
12... Normally closed contactor.

Claims (1)

[Claims for Utility Model Registration] Normally closed contactor 12 and resistor 9
and a thyristor 10, the electric vehicle is powered and braking controlled by an inverter 8 and an induction motor 7, and an inverted L-type filter of a filter reactor 5 and a filter capacitor 6. is connected to the front stage of the inverter 8, and is connected to the current collector 1 via the current interrupter 2, and the normally closed contactor 12 and the resistor 9.
The thyristor 10 consists of a series circuit and is connected in parallel to the filter capacitor 6. When the voltage of the filter capacitor 6 becomes excessive during regenerative braking, the thyristor 10 is fired, and then the current interrupter 2 is opened. After the normally closed contactor 1
2 is an overvoltage suppression device for electric vehicles that is opened.