JPS6310663B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration suppression circuit that suppresses vibrations occurring in a DC voltage smoothing filter provided on the input side of a power conversion device such as a chopper or an inverter.

For example, in a circuit used for a power conversion device such as a tipper or an inverter used in an electric vehicle, when a current flows from a pantograph 14 to a power conversion device 6 via a main contactor 1 as shown in FIG. In order to cope with fluctuations in voltage, a smoothing filter circuit consisting of a reactor 4 and a capacitor 5 is provided in the DC input side circuit of the power converter 6 to smooth the voltage. When voltage is applied to the circuit, or when the power supply voltage suddenly changes or is interrupted while the vehicle is operating, so-called L-C resonance occurs, and the input voltage at both ends of the capacitor 5 used in the smoothing filter, that is, the input voltage of the power converter 6, occurs. increases to nearly double the value, and as a result, there is a risk that the elements of the power converter 6 may be destroyed.

In order to suppress this type of vibration, conventionally, a resistor 3 is connected in series to the reactor 4, and an auxiliary contactor 2 is connected to the resistor 3 in parallel, so that the resistor 3 acts as a braking resistor and the capacitor 5 A method has been adopted in which vibrations are suppressed until charging, and after the capacitor 5 is charged, the auxiliary contactor 2 is closed and the resistor 3 is short-circuited.

However, using such an auxiliary contactor 2, the resistor 3
Since the operating time for closing the auxiliary contactor 2 is approximately 100 msec, the method of short-circuiting the has the disadvantage that it cannot function satisfactorily.

The present invention solves the above-mentioned drawbacks and provides a DC filter vibration suppression circuit that can effectively suppress vibrations harmful to power conversion devices such as choppers and inverters even when a momentary power supply voltage interruption occurs. According to the present invention, the reactor is connected to a series circuit of the power supply side switching means and the reactor in a DC filter circuit consisting of a capacitor, and is connected to a controllable rectifier element whose conduction is controlled during normal operation. This is achieved by connecting a resistor in parallel and controlling the controllable rectifying element to be non-conductive in advance of any vibration phenomenon that may occur in the DC filter.

Hereinafter, the invention will be explained in detail with reference to the drawings.

According to the embodiment of the invention shown in FIG.
For example, a motor for driving an electric vehicle (not shown)
It is a power conversion device such as a chopper or an inverter that supplies power to the input terminal, and controls the equivalent voltage by appropriately intermittent DC power applied to the input terminal using a known method, or converts it to AC.

A reactor 4 is connected in series to the DC side input terminal of the power conversion device 6, and a capacitor 5 is connected in parallel, so that the reactor 4 and the capacitor 5 form an LC filter.

The cathode terminal of the thyristor 7 is connected in series to the reactor 4, and the anode terminal of the thyristor 7 is connected in series to the pantograph 14 via the main contactor 1.

A resistor 3 is connected in parallel to the thyristor 7, a detector 8 for detecting the voltage of the overhead wire 15 is connected in parallel to the power supply, and a detector 9 for detecting the voltage of the capacitor 5 is connected in parallel to the capacitor 5.

Further, as shown in FIG. 5, the output signal of the detector 8 is introduced into the level detector 10, the output signal of the detector 9 is introduced into the level detector 11, and the output signals of the level detectors 10 and 11 are introduced. AND circuit 12 each
The ignition signal generated by the AND circuit 12 is supplied to the gate terminal of the thyristor 7 via the gate amplifier 13.

Next, the operation of the present invention will be explained. For example, when the main contactor 1 is closed in order to start an electric vehicle, a DC voltage as shown in FIG. 3A is supplied, and the thyristor 7 is in an off state. , DC current flows from main contactor 1 to resistor 3 and reactor 4
The voltage flows through the capacitor 5 through the capacitor 5 in the state shown in FIG. 3B, while the voltage of the capacitor 5 rises exponentially as shown in FIG. 3C.

Further, the total voltage of the resistor 3 and the reactor 4 is in the state shown in FIG.

When the main contactor 1 is closed and the power supply voltage supplied from the overhead line 15 to the pantograph 14 reaches a constant value (V _D1 ), the level detector 10 that receives the output signal of the detector 8 outputs an output signal of "1". Furthermore, when the voltage of the capacitor 5 reaches a constant value (V _D2 ), the level detector 11 that receives the output signal of the detector 9 introduces an output signal of "1" into the AND circuit 13. Therefore, the AND circuit 13 is
Upon receiving the two "1" output signals, an ignition signal is supplied to the gate terminal of the thyristor 7 via the gate amplifier 13, and the thyristor 7 is ignited and turned on.

In this way, from the time of starting until the capacitor 5 reaches a constant value, the thyristor 7 is off.
Power supply current is main contactor 1, resistor 3, reactor 4
The voltage flows through the capacitor 5 through the resistor 3, which suppresses the vibration of the filter circuit by acting as a braking resistor. After the voltage of the capacitor 5 is charged to a certain value (V _D2 ) or higher, the thyristor 7 is turned on. Short circuit resistor 3.

Next, when the power supply voltage is reapplied after a short power outage due to, for example, the overhead wire 15 and pantograph 14 coming apart due to vibration while the electric vehicle is operating, the power supply voltage temporarily drops to 0, but when it drops below a certain value (V _D1 ), the level detector 1 receives the output signal of the detector 8.
0, an output signal of "0" is introduced into the AND circuit 12 as shown in FIG.

In addition, in such a case, the input current becomes the state shown in Fig. 4 (c), and when the input current decreases and eventually becomes negative, the voltage of the capacitor 5 becomes a reverse voltage across the thyristor 7 as shown in Fig. 4 (d). is applied, and the thyristor 7 is turned off.

In general, the turn-off time of the thyristor 7 is several 100 μsec even in the case of a power thyristor.
On the other hand, the time it takes for the voltage of capacitor 5 to decay is several times
Since 10 msec is sufficient, there is no problem in recovering the forward blocking ability of the thyristor 7.

Then, when the power supply voltage is reapplied, the thyristor 7 is off, so the charging current to the capacitor 5 flows from the main contactor 1 through the resistor 3,
The vibration of the L-C filter is suppressed by the resistor 3 acting as a braking resistance.

Furthermore, when the detectors 8 and 9 detect that the power supply voltage has become above a certain value (V _D1 ) and the voltage of the capacitor 5 has become above a certain value (V _D2 ), the level detector 10 and the level detector 11 are activated. As shown in FIG. 4B and E, an output signal of "1" is introduced into the AND circuit 12, and as shown in FIG. Since a forward voltage is applied to both ends of the thyristor 7 as shown in FIG. 4, the thyristor 7 is turned on by this ignition signal, shorting the resistor 3, and thereafter entering the normal operating state.

As described above, the vibration suppression circuit for a DC filter of the present invention can be used in a device in which a filter consisting of a reactor and a capacitor is connected to the input side of a power conversion device such as a chopper or an inverter, between the power supply side switching means and the reactor. A controllable rectifying element and a resistor are connected in parallel, so it can be used not only when the power is turned on or during normal operation, but also in response to short-term power outages such as when a pantograph separates from the overhead wire. It is possible to effectively suppress vibrations caused by L-C resonance that are harmful to the power converter.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional example of a power conversion device equipped with a filter, Fig. 2 is a circuit diagram showing an embodiment of the present invention, and Figs. 3 and 4 are diagrams explaining the operation of the circuit shown in Fig. 2. , FIG. 5 is a block diagram showing the flow of signals to the thyristor. 1... Main contactor, 3... Resistor, 4... Reactor, 5... Capacitor, 6... Power converter,
7...thyristor, 8,9...detector.

Claims (1)

[Claims] 1. In a DC filter circuit consisting of a reactor and a capacitor, a parallel circuit of a controllable rectifying element such as a thyristor whose conduction is controlled during normal operation and a resistor is inserted in series in the series circuit between the power supply side switching means and the reactor. ignition of said controllable rectifier element provided that at least one of the power supply and capacitor voltages has fallen below a predetermined limit value for each, prior to an oscillatory phenomenon that may occur in the DC filter; By blocking the signal supply, this controllable rectifier is controlled to a non-conducting state,
A vibration suppression circuit for a DC filter, characterized in that the resistor acts as a control resistance to effectively suppress L-C vibration occurring in the DC filter.