JP2641162B2 - Thyristor short-circuit detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thyristor short-circuit detecting device for detecting a thyristor short-circuit in an AC thyristor switch for opening and closing a single-phase AC power line.

[0002]

2. Description of the Related Art An AC thyristor switch inserted into a single-phase AC power line opens and closes the single-phase AC power line to obtain a signal.
This is for switching and outputting power of the system (+ side and − side), and is used, for example, for supplying the output of an inverter circuit in an uninterruptible power supply on the load side or for a contactless changeover switch in a direct feed circuit. I have.

FIG. 6 shows a circuit configuration of a conventional AC thyristor switch. In this figure, an AC thyristor switch 1 includes two thyristors A and B and thyristors C and D
Are composed of two sets of switching circuits 2 and 3 connected in anti-parallel.

The switching circuits 2 and 3 are inserted into the single-phase AC power lines L1 and L2, and control the switching operations of the thyristors A and B and the thyristors C and D by a control circuit (not shown). As shown in (a) to (e), the input AC current is transmitted to the output side half-wave at a time.

[0005]

However, in such a conventional AC thyristor switch, it is difficult to detect a short circuit of the thyristor in an energized state, and the short circuit state can be detected only by the thyristor alone. There was a point.

That is, it is difficult to detect whether or not each of the thyristors A to D is short-circuited in the switching operation of each of the switching circuits 2 and 3 in an energized state. I was Since the measurement method is performed by turning off the gate electrode of the thyristor and measuring whether or not a current flows between the anode and cathode electrodes, there is a disadvantage in that it takes time to detect a short circuit.

For this reason, even if a short circuit occurs in the thyristor during energization, it cannot be detected immediately, and there is a disadvantage that a fault such as a contact with a normal thyristor of another system in the AC thyristor switch occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and uses a circuit configuration of an AC thyristor switch to detect a short circuit of a thyristor that is energized with a relatively simple circuit configuration. It is an object to provide a detection device.

[0009]

According to the first aspect of the present invention,
Two sets of switching circuits in which two thyristors are connected in anti-parallel are used, each of the switching circuits is inserted for each single-phase AC line, and the AC power input by the switching operation of each of the switching circuits is supplied to the load side. In an AC thyristor switch that outputs intermittently, current detection means for detecting a current flowing in a forward thyristor in the one switching circuit and a current flowing in a return thyristor in the other switching circuit; Comparing means for comparing each detected current value detected by the means,
And detecting a short circuit of the thyristor in each of the switching circuits based on the comparison result of the comparing means.

In this case, the current detecting means detects a total current of a half-wave AC current flowing in the outward thyristor and a half-wave AC current flowing in the return thyristor. Then, the short circuit of each of the thyristors may be detected based on the result of comparing the total detected current value by the comparing means.

Further, as described in claim 3, when a short circuit of the thyristor is detected, it is effective to provide a notifying means for notifying the short circuit of the thyristor.

[0012]

According to the invention described in claims 1 and 2,
AC thyristor that uses two sets of switching circuits in which three thyristors are connected in anti-parallel, inserts each of the switching circuits for each single-phase AC line, and intermittently outputs input AC power to the load side by switching operation. In the switch, the current detection means detects a half-wave AC current flowing in the forward thyristor in the one switching circuit and a half-wave AC current flowing in the return thyristor in the other switching circuit, and detects each detected current. Utilizing the fact that the polarity is reversed and the absolute value is the same, the result of comparing the respective detected current values by the comparing means is not zero, and a large amount of half-wave AC current flows through the short-circuit thyristor. The short-circuit state of the thyristor is detected by detecting and comparing the wave AC current values.

In the case of a thyristor short circuit that does not pass through the current detecting means, the load current is bypassed to the shorted thyristor, and the result of comparison between the detected current values of the two thyristors is not zero. The current flows,
The short-circuit of the thyristor is detected by detecting and comparing the half-wave alternating current values.

Therefore, it is possible to immediately detect a short-circuit of the energized thyristor in the AC thyristor switch, and to avoid occurrence of trouble such as contact with a normal thyristor of another system.

According to the third aspect of the present invention, when a short circuit of the thyristor during energization is detected, a notifying means for notifying the short circuit of the thyristor is provided, so that the short circuit of the thyristor is immediately notified. The replacement of the short-circuit thyristor can be prompted.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below in detail with reference to FIGS.

1 to 5 show one embodiment of a single-phase AC circuit to which a thyristor detecting device according to the present invention is applied.
In FIG. 1, the same components as those shown in FIG. 6 are denoted by the same reference numerals.

First, the configuration will be described.

FIG. 1 is a diagram showing a configuration of a thyristor short-circuit detecting device for detecting a thyristor short-circuit in an AC thyristor switch 1 inserted in the single-phase AC power lines L1 and L2. In FIG. 1, an AC thyristor switch 1 includes a switching circuit 2 inserted into a single-phase AC power line L1,
Switching circuit 3 inserted in single-phase AC power line L2
Each of the switching circuits 2 and 3 is composed of two thyristors A and B and thyristors C and D connected in antiparallel. These thyristors A to D
Each switching operation is performed by the control circuit 14
Is controlled at a predetermined timing by a switching control signal input from the controller.

In the switching circuit 2, when the thyristor A is turned on by the switching control signal, the thyristor D of the single-phase AC power line L2 is turned on, and the thyristor A passes through a load (not shown). This is a return thyristor A that transmits a half-wave alternating current having a polarity opposite to that of the load current input from the middle output side to the input side in the drawing.

In the switching circuit 2, when turned on by a switching control signal, the thyristor B transfers a half-wave AC current of the input AC current input from the input side of the single-phase AC power line L1 to the output side in the figure. This is a forward thyristor B that supplies a connected load (not shown).

In the switching circuit 3, when the thyristor C is turned on by the switching control signal, the forward thyristor B of the single-phase AC power line L1 is turned on and the load (not shown) passes through the single-phase AC power line L2.
Is a return thyristor C for transmitting a half-wave AC current of a load AC current input from an output side in the drawing to the input side in the drawing.

In the switching circuit 3, when turned on by the switching control signal, the thyristor D outputs a half-wave AC current having a polarity opposite to that of the input AC current input from the input side of the single-phase AC power line L2 in the figure. This is a forward thyristor D that supplies a load (not shown) connected to the output side.

Therefore, the forward thyristor B of the switching circuit 2 and the backward thyristor C of the switching circuit 3 are turned on at the same timing, and the backward thyristor A of the switching circuit 2 and the forward thyristor D of the switching circuit 3 are turned on.
Are turned on at the same timing.

In FIG. 1, reference numeral 10 denotes a thyristor short-circuit detecting device.
Is a current detector 11, a full-wave rectifier circuit 12, a comparator 13,
It is composed of a control circuit 14 and a short-circuit notification circuit 15.

The current detector 11 detects a total current of an input AC current flowing through the forward thyristor B of the switching circuit 2 and a load AC current flowing through the return thyristor C of the switching circuit 3, and full-wave rectifies the detected AC current. Circuit 12
Output to The current detector 11 has a function as a current detecting unit.

The full-wave rectifier circuit 12 performs full-wave rectification on the detected AC current input from the current detector 11 to convert it into a DC current, and outputs the DC current to the comparator 13.

The comparator 13 detects whether or not a short-circuit current flows through the forward thyristors B and D and the return thyristors A and C based on the DC current value input from the full-wave rectifier circuit 12, and detects the detection. The signal is output to the control circuit 14.
The comparator 13 has a function as a comparison unit.

The control circuit 14 sends a switching control signal for controlling each switching operation of the return thyristor A and the forward thyristor B of the switching circuit 2 and the return thyristor C and the forward thyristor D of the switching circuit 3 to the gate electrodes of the thyristors A to D. To the comparator 1
A notification signal for notifying that the forward thyristors B and D or the return thyristors A and C have been short-circuited is output to the short-circuit notifying unit 15 based on the detection signal input from 3.

The short-circuit notifying section 15 notifies the short-circuit of the outward thyristors B and D or the return thyristors A and C by a notification signal or a flashing lamp or the like based on a notification signal input from the control circuit 14.

Reference numeral 16 in the figure denotes a no-load compensation resistor set so that a predetermined current flows through the thyristors A to D even in a no-load state.

Next, the operation will be described.

First, the operation when the return thyristor A and the forward thyristor B of the switching circuit 2 and the return thyristor C and the forward thyristor D of the switching circuit 3 are normal will be described with reference to the timing charts of signals of the respective parts shown in FIG. explain.

FIG. 2A shows an AC input current waveform input to the single-phase AC power line L1, and the half-wave AC current is supplied to the load by turning on the forward thyristor B of the switching circuit 2. (See (c) in the figure.), When the return thyristor C of the switching circuit 3 inserted in the single-phase AC power line L2 through the load is turned on, the load current having the same absolute value at the current phase of 180 ° (see FIG. d) is returned to the input side.

The half-wave alternating current of the opposite polarity, which is input to the single-phase AC power line L2, is supplied to the load by turning on the forward thyristor D of the switching circuit 3 (see FIG. 7E) and passes through the load. When the return thyristor A of the switching circuit 2 inserted into the single-phase AC power line L1 is turned on,
A load current having the same absolute value at the current phase of 180 ° (see FIG. 13B) is returned to the input side.

Since the phases of the currents flowing through the forward thyristor B and the backward thyristor C are 180 ° and have the same absolute value, the total current detected by the current detector 11 is always zero regardless of the value of the load current. (Refer to (f) of the figure).

Therefore, when the thyristor is normal,
The DC current input from the full-wave rectifier circuit 12 to the comparator 13 is always zero, and no detection signal is output from the comparator 13 to the control circuit 14.

Next, the operation when the forward thyristor B of the switching circuit 2 is short-circuited will be described with reference to the timing chart of the signals of the respective parts shown in FIG.

When the forward thyristor B of the switching circuit 2 is short-circuited, the short-circuit impedance of the forward thyristor B becomes lower than the ON voltage of the return thyristor A, and the AC input current input to the single-phase AC power line L1 (see FIG. )), The forward and return AC currents flow through the outward thyristor B as shown in FIG.

Since the return thyristor C of the switching circuit 3 operates normally, the bipolar load current input from the output side of the single-phase AC power line L2 through the load is:
As shown in FIG. 4D, the wave is returned to the input side as a half-wave AC current.

The AC input current input from the input side of the single-phase AC power line L2 (see FIG. 7A) is the same as that of FIG. 7E because the forward thyristor D of the switching circuit 3 operates normally. As shown in (1), a half-wave alternating current of the opposite polarity flows and is supplied to the load. Then, the load current that has passed through the load tends to flow from the output side of the single-phase AC power line L1 to the return thyristor A of the switching circuit 2, but the short-circuit impedance of the forward thyristor B becomes lower than the ON voltage of the return thyristor A. Therefore, no current flows through the return thyristor A as shown in FIG. 2B, but flows through the outward thyristor B and returns to the input side as shown in FIG. 2C.

When the forward thyristor B is short-circuited in this way, currents in both the forward and return directions flow through the forward thyristor B. Therefore, the total current of the forward thyristor B and the return thyristor C passing through the current detector 11 is as shown in FIG. As shown in FIG. 7, the voltage does not become zero, and a half-wave alternating current is detected.

When this half-wave AC current is converted into a DC current by the full-wave rectifier circuit 12 and output to the comparator 13, a detection signal indicating short-circuit detection is output from the comparator 13 to the control circuit 14, and the control circuit 14 The short-circuit notification signal is output from 14 to the short-circuit notification unit 15, and the short-circuit notification unit 15 notifies that the short-circuit of the thyristor on the switching circuit 2 side has been detected.

Next, the operation when the return thyristor C of the switching circuit 3 is short-circuited will be described with reference to a timing chart of signals of respective parts shown in FIG.

When the return thyristor C of the switching circuit 3 is short-circuited, the short-circuit impedance of the return thyristor C becomes lower than the on-voltage of the forward thyristor D, and the AC input current (see FIG. As shown in
The alternating currents in the forward and return paths flow through the return thyristor C.

Since the forward thyristor B of the switching circuit 2 is normal, the input AC current input from the input side of the single-phase AC power line L1 is, as shown in FIG. And supplied to the load.

Although the forward thyristor D of the switching circuit 3 is normal, since the short-circuit impedance of the return thyristor C is lower than the on-voltage of the forward thyristor D, it is input from the input side of the single-phase AC power line L2. As shown in FIG. 3E, the AC input current (see FIG. 3A) does not flow through the outward thyristor D, and as shown in FIG. It flows to thyristor C and is supplied to the load.

The single-phase AC power line L1
The thyristor A of the return circuit of the switching circuit 2 operates normally because the bipolar load current input from the output side of
As shown in FIG. 7B, the half-wave alternating current of the opposite polarity is returned to the input side.

The AC input current input from the input side of the single-phase AC power line L1 (see (a) in FIG. 5) is transmitted to the thyristor B of the switching circuit 2 in a normal operation. As shown in (1), a half-wave alternating current flows and is supplied to the load. Then, the load current that has passed through the load flows from the output side of the single-phase AC power line L2 through the short-circuit path of the return thyristor C of the switching circuit 3 and returns to the input side.

When the return thyristor C is short-circuited in this way, both currents in the forward and return directions flow through the return thyristor C, so that the total current of the forward thyristor B and the return thyristor C passing through the current detector 11 is as shown in FIG. As shown in FIG. 7, the voltage does not become zero, and a half-wave alternating current is detected.

When this half-wave AC current is converted into a DC current by the full-wave rectifier circuit 12 and output to the comparator 13, a detection signal indicating short-circuit detection is output from the comparator 13 to the control circuit 14, and the control circuit 14 The short-circuit notification signal is output from 14 to the short-circuit notification unit 15, and the short-circuit notification unit 15 notifies that the short-circuit of the thyristor on the switching circuit 3 side has been detected.

Next, the operation when the return thyristor A of the switching circuit 2 is short-circuited will be described with reference to the timing charts of the signals shown in FIG.

When the return thyristor A of the switching circuit 2 is short-circuited, the short-circuit impedance of the return thyristor A becomes lower than the ON voltage of the forward thyristor B, and the AC input current input to the single-phase AC power line L1 (see FIG. )), As shown in FIG. 4B, the forward and return AC currents flow through the return thyristor A, and no current flows through the forward thyristor B.

Since the return thyristor C of the switching circuit 3 operates normally, the bipolar load current input from the output side of the single-phase AC power line L2 through the load is:
As shown in FIG. 4D, the wave is returned to the input side as a half-wave AC current.

The AC input current input from the input side of the single-phase AC power line L2 (see FIG. 7A) is the same as that of FIG. 7E because the forward thyristor D of the switching circuit 3 operates normally. As shown in (1), a half-wave alternating current of the opposite polarity flows and is supplied to the load. Then, the load current that has passed through the load flows from the output side of the single-phase AC power line L1 through the short-circuit path of the return thyristor A of the switching circuit 2 and is returned to the input side.

When the backward thyristor A is short-circuited in this way, currents in both the forward and backward directions flow through the backward thyristor A, so that the total current of the forward thyristor B and the backward thyristor C passing through the current detector 11 is as shown in FIG. As shown in FIG. 7, the voltage does not become zero, and a half-wave alternating current is detected.

When the half-wave AC current is converted into a DC current by the full-wave rectifier circuit 12 and output to the comparator 13, a detection signal indicating short-circuit detection is output from the comparator 13 to the control circuit 14, and the control circuit 14 The short-circuit notification signal is output from 14 to the short-circuit notification unit 15, and the short-circuit notification unit 15 notifies that the short-circuit of the thyristor on the switching circuit 2 side has been detected.

Also, when the forward thyristor D of the switching circuit 3 is short-circuited, the short-circuit impedance of the forward thyristor D becomes lower than the ON voltage of the backward thyristor C. Since the alternating current flows in both directions of the forward path and the return path, the total current of the forward path thyristor B and the return path thyristor C detected by the current detector 11 does not become zero, and the half-wave AC current of the forward path thyristor B is detected. Similarly, short-circuit notification unit 1
5 informs that a short circuit of the thyristor on the switching circuit 3 side has been detected.

As described above, by using the thyristor short-circuit detecting device 10 of the present invention for the AC thyristor switch 1, it is possible to detect short-circuits of the thyristors A to D during energization. This eliminates the need for the short-circuit detection operation, and can significantly reduce the time required for short-circuit detection.

Further, since the short-circuit of the thyristor is notified, it is possible to prompt the user to replace the short-circuited thyristor, and to prevent a trouble such as a contact between the short-circuited thyristor and a normal thyristor of another system. Can be.

In the above embodiment, the current detector 11
Detects the total current of the forward thyristor B and the return thyristor C. However, even if the total current of the return thyristor A and the forward thyristor D is detected, the short circuit of the thyristors A to D can be similarly detected. is there.

Further, by utilizing the principle of detecting the total current of the forward thyristor B and the return thyristor C flowing to the current detector 11, the open state of the forward thyristor B and the return thyristor C can be detected.

[0063]

According to the first and second aspects of the present invention, a short circuit of a thyristor in an energized state can be immediately detected in an AC thyristor switch, and a failure such as a contact with a normal thyristor of another system can be prevented. Occurrence can be avoided.

According to the third aspect of the present invention, when a short circuit of the thyristor during energization is detected, a notifying means for notifying the short circuit of the thyristor is provided, so that the short circuit of the thyristor is immediately notified and the short circuit is performed. The thyristor can be replaced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a block configuration of a single-phase AC circuit of an embodiment to which a thyristor short-circuit detection device of the present invention is applied.

FIG. 2 is a diagram showing operation waveforms of the AC thyristor switch and the current detector of FIG. 1 in a normal state.

FIG. 3 is a diagram showing operation waveforms of an AC thyristor switch and a current detector when a forward thyristor B in FIG. 1 is short-circuited.

FIG. 4 is a diagram showing operation waveforms of an AC thyristor switch and a current detector when the return thyristor C in FIG. 1 is short-circuited.

5 is a diagram showing operation waveforms of an AC thyristor switch and a current detector when a forward thyristor D in FIG. 1 is short-circuited.

FIG. 6 is a diagram showing a circuit configuration of a conventional AC thyristor switch.

FIG. 7 is a view showing operation waveforms of each part of the AC thyristor switch of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC thyristor switch 2 Switching circuit 3 Switching circuit 10 Thyristor short circuit detection device 11 Current detector 12 Full-wave rectifier circuit 13 Comparator 14 Control circuit 15 Short circuit notification section A Return thyristor B Forward thyristor C Return thyristor D Forward thyristor L1 Single phase AC Power line L2 Single-phase AC power line

Claims (3)

(57) [Claims] An AC input by a switching operation of each switching circuit is provided by using two sets of switching circuits in which two thyristors are connected in anti-parallel and each switching circuit is inserted for each single-phase AC line. In an AC thyristor switch that outputs power intermittently to a load side, current detection means for detecting a current flowing in a forward thyristor in the one switching circuit and a current flowing in a return thyristor in the other switching circuit. And comparing means for comparing the respective detected current values detected by the current detecting means, wherein a short circuit of each thyristor in each of the switching circuits is detected based on a comparison result of the comparing means. Thyristor short-circuit detection device. 2. The current detection means detects a total current of a half-wave AC current flowing through the outward thyristor and a half-wave AC current flowing through the return thyristor, and compares the total current value with the comparison means. 2. The thyristor short-circuit detecting device according to claim 1, wherein the short-circuit of each of the thyristors is detected based on the result. 3. The thyristor short-circuit detecting device according to claim 1, further comprising a notifying means for notifying the short-circuit of the thyristor when the short-circuit of the thyristor is detected.