JP2002186170A - Fault-detecting device for high-voltage switching circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of an existing fault-detecting device for a high- voltage switching circuit detects only a fault of power supply for operating a switching element and the lighting conditions of an LED is manually decided for the fault of the high-voltage switching element itself. SOLUTION: A photocoupler, which is connected to a snubber circuit 9 provided in parallel with a switch element of each stage to detect faults of the inputted power supply voltage, is provided for each stage and the photocouplers of the stages are connected in series. Thereby, the fault of the switch element of any stage or the power supply is detected with the output of the photocoupler 5 of the final stage. Accordingly, faults of the switching element and faults of the power supply can be detected using only one circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure detecting device for a high voltage switch circuit for switching a high voltage.

[0002]

2. Description of the Related Art FIG. 2 is a circuit diagram showing a conventional fault detecting device for a high voltage switch circuit. In FIG. 2, S1 to S1
Sn is a switch of each stage constituted by an FET. 1 is LE indicating the state of the first-stage switch S1
D, 2 is a photocoupler for detecting an abnormality of the input power to the first-stage switch S1, 3 is an LED indicating the state of the second-stage switch S2, and 4 is an abnormality of the input power to the second-stage switch S2. Photocoupler. Reference numeral 5 denotes a photocoupler that detects an input power supply abnormality to the last switch Sn, and reference numeral 6 denotes a detection control circuit that includes a photocoupler that controls the control power supply in response to the detection of the input power supply abnormality. Reference numeral 7 denotes a driver circuit for driving the switches S1 to Sn. Reference numeral 8 denotes a DC power supply that supplies a power supply voltage Vcc1 to the driver circuit 7. Reference numeral 9 denotes a snubber circuit connected in parallel to each of the switches S1 to Sn.

Next, the operation will be described. Switch S1
When Sn is normal, the switches S1 to Sn are simultaneously turned ON / OFF by the driver circuits 7 of the respective stages. A snubber circuit 9 is connected in parallel to the switches of each stage, and the voltage across the CR of the snubber circuit 9 is a DC voltage corresponding to the switch shared voltage. The LED 1 is connected via a resistor from the capacitor of the snubber circuit 9, and is lit when the switch S1 is normal. However, when the switch S1 becomes abnormal in the short mode, the snubber voltage becomes zero, and the LED1 is turned off. Therefore, by monitoring the state of LED1, the switch S
It can be seen that one circuit has failed. Similarly, LED
By monitoring the state of No. 3, it is found that the circuit of the switch S2 has failed.

On the other hand, the transformer T1 supplies a high-voltage power supply to the driver circuit 7 and the failure detection circuit of each stage. If the input power supply is operating normally,
Is activated, and the output of the photocoupler 2 becomes low level. Then, a current flows through the photodiode of the photocoupler 4 to operate the photodiode of the photocoupler 4. If the result is connected to the cathode of the photodiode of the detection circuit of the next stage, the photodiode of each stage is sequentially operated, and the result is finally detected by the photocoupler 5 and the detection control circuit 6. Thereby, abnormality detection of the input power to the switch can be performed. Here, if there is an abnormality in the power supply of the second stage, the photodiode of the first stage operates, but power is not supplied to the detection side of the second stage. Since no current flows, the second-stage photodiode does not operate. If the photodiode does not operate due to any abnormality, the subsequent photocoupler does not operate because it is connected to the series. As described above, by detecting the output of the photocoupler 5 at the last stage by the detection control circuit 6, it can be determined whether the output is abnormal or normal.

[0005]

In the prior art, only the abnormality of the power supply for operating the switch element is detected, and the abnormality of the high voltage switch element itself is detected by the LED.
The person was judging the lighting state of.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and includes a circuit for detecting an abnormality of a high-voltage switch and a detection circuit for detecting an abnormality of an input power supply to the high-voltage switch. It is an object of the present invention to obtain a failure detection device for a high-voltage switch circuit that can detect a switch abnormality and an input power abnormality with one circuit and control a high-voltage power supply.

[0007]

In the fault detecting apparatus for a high voltage switch circuit according to the present invention, the fault detecting apparatus is provided for each stage and detects a fault in a switch element in each stage and is used for controlling the switch element. Comprising first detection means configured to detect an abnormality of the control power supply voltage,
The first detecting means of each stage is connected in series. The control power supply voltage at which an abnormality is detected by the first detection means is formed for each stage.

The first detecting means is connected to a snubber circuit provided in parallel with the switch element at each stage. Further, a second detecting means for judging an abnormality based on an output of the first detecting means in the final stage, wherein the second detecting means outputs a signal for controlling a control power supply when the abnormality is judged. is there.

Further, there is provided a third detecting means which is constituted by using a transistor which operates in response to the input of the control power supply voltage of the first stage, and the output of the third detecting means is the first detecting means of the first stage. It is input to the means. The first detecting means is constituted by a photocoupler.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a circuit diagram showing a failure detection device for a high-voltage switch circuit according to Embodiment 1 of the present invention. In FIG. 1, S1 to Sn are switches of each stage constituted by FETs.
1 is an LED indicating the state of the first-stage switch S1, and 2 is 1
A photocoupler (first detecting means) for detecting a failure of the first-stage switch S1 and an abnormality of input power to the switch S1;
Is an LED that indicates the state of the second-stage switch S2, and 4 is a photocoupler that detects a failure in the second-stage switch S2 and an abnormality in the input power to the switch S2. Reference numeral 5 denotes a photocoupler for detecting a failure of the switch Sn at the last stage and abnormality of input power to the switch Sn, and reference numeral 6 comprises a photocoupler for controlling the power supply upon detection of failure of the switch at each stage or abnormality of the input power. When the control circuit (second detection means) detects an abnormality, it outputs a signal for controlling the control power supply. A driver circuit 7 drives each of the switches S1 to Sn, and is provided for each stage. Reference numeral 8 denotes a DC power supply provided for each stage, and supplies a power supply voltage Vcc1 to the driver circuit 7. Reference numeral 9 denotes a snubber circuit connected in parallel to each of the switches S1 to Sn. 10 is constituted by an FET whose source is grounded and controlled by the input of the power supply voltage,
A detection circuit (third detection means) for detecting an input power supply abnormality of the first-stage high-voltage switch, and a reference numeral 11 denotes a zener diode connected to the LED of each stage, which supplies a stable voltage to the circuit for detecting the input power supply abnormality. Provided to supply.

The photocoupler 2 is connected to a snubber circuit 9 of its own stage via a resistor, to which the output of the detection circuit 10 and the power supply voltage of the next stage are input. It is configured to reflect abnormalities. The photocoupler 4 is connected to a snubber circuit 9 of its own stage via a resistor similarly to the photocoupler 2, and receives the power supply voltage of the next stage and the output of the photocoupler 2.
Are configured to reflect the abnormalities of those inputs. In this manner, the photocouplers are sequentially connected so as to receive the output of the preceding photocoupler.

Next, the operation will be described. When a high voltage is applied to the entire switch, the shared voltage is applied to the snubber circuit 9 when the switches S1 to Sn are normal. A low-voltage power supply is made by connecting a resistor divider circuit to a snubber circuit. In addition, the transformer T1 supplies a power floating at a high voltage to the driver circuit 7 and the detection circuit of each stage. The driver circuit 7
The source potential of each switch element is set as a reference potential, and a potential floating by a potential from which the switch element can be operated is supplied to the gate of the switch element.

When the power supply voltage VCC1 is supplied to the detection circuit 10 and the FET switch of the detection circuit 10 is turned on, the drain potential of the FET of the detection circuit 10 decreases,
A current flows through the photodiode of the photocoupler 2, and the output circuit of the photocoupler 2 operates. The output of the photocoupler 2 becomes low level, and a current flows through the photodiode of the second-stage photocoupler 4. Therefore, the second-stage high-voltage switch S
2 and if there is no abnormality in the input power supply, as in the first stage, the LED
3 and the photodiode of the photocoupler 4 operate, and the output of the photocoupler 4 becomes low level.

If there is an abnormality in the power supply, as described in the background art, the power supply on the output side of the photocoupler 4 is lost, so that an abnormal state can be detected. Conversely, the power supply is normal,
If the switch S2 becomes abnormal in the short mode, the voltage of the snubber circuit 9 becomes zero, so that the output of the photocoupler 4 becomes abnormal even if the power supply is normal. Since the photocouplers in each stage are connected in series, the output of the photocoupler 5 in the last stage also becomes abnormal. By providing such a circuit in each stage of the high-voltage switch, if there is an abnormality in the switch or the input power supply even in one stage, the photocoupler after the stage where the abnormality occurred will not operate, and the abnormal state will be transmitted one after another. In other words, the detection by the photocoupler 5 and the detection control circuit 6 at the last stage allows the abnormality of the switch element or the abnormality of the input power supply to be detected by one circuit.

According to the first embodiment, abnormality of the switch element and the high-voltage power supply can be detected by one circuit, and control such as turning off the high-voltage power supply can be performed.

[0016]

Since the present invention is configured as described above, it has the following effects. A first detection unit is provided for each stage, and is configured to detect a failure of the switch element of each stage and to detect an abnormality of a control power supply voltage used for controlling the switch element. Since the first detecting means is connected in series, the failure of the switch element and the abnormality of the control power supply voltage can be detected only by the first detecting means.

Further, since the control power supply voltage at which the abnormality is detected by the first detection means is formed for each stage, it is possible to detect the abnormality of the control power supply voltage for each stage. Also, since the first detecting means is connected to a snubber circuit provided in parallel with the switch element of each stage,
A failure of the switch element can be detected.

Further, there is provided second detection means for judging an abnormality based on the output of the first detection means at the last stage, and the second detection means outputs a signal for controlling the control power supply when the abnormality is judged. Therefore, the control power supply can be controlled at the time of abnormality. In addition, the apparatus further includes third detection means configured using a transistor that operates by inputting a control power supply voltage of the first stage, and an output of the third detection means is input to the first detection means of the first stage. Therefore, it is possible to detect an abnormality in the first-stage control power supply voltage.

Since the first detecting means is constituted by a photocoupler, the photocoupler can detect a failure of the switch element and an abnormality of the control power supply voltage.

[Brief description of the drawings]

FIG. 1 is a diagram showing a failure detection device for a high-voltage switch circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional failure detection device for a high-voltage switch circuit.

[Explanation of symbols]

1,3 LED, 2,4,5 photo coupler, 6 detection control circuit, 7 driver circuit, 8 DC power supply, 9 snubber circuit, 10 detection circuit, 11 Zener diode.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhiro Mukai 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F-term (reference) 5G053 AA03 AA12 BA04 DA02 EA02 EB02 EC03 5H740 AA10 BA12 BB01 KK04 MM03

Claims (6)

[Claims] 1. A high voltage switch circuit failure detection device for detecting a failure of a high voltage switch circuit in which switch elements for switching a high voltage are connected in multiple stages is provided for each stage, and a switch element of each stage is provided. A first detecting means configured to detect a failure of the control power supply voltage used for controlling the switch element and to detect the failure of the switch element, and the first detecting means of each of the stages is connected in series. A fault detection device for a high-voltage switch circuit. 2. The high voltage switch circuit fault detection device according to claim 1, wherein the control power supply voltage at which the first detection means detects an abnormality is formed for each stage. 3. The high voltage switch circuit according to claim 1, wherein a snubber circuit provided in parallel with the switch element of each stage is connected to the first detection means. Failure detection device. 4. A second detecting means for determining an abnormality based on an output of the first detecting means at the last stage, wherein the second detecting means outputs a signal for controlling a control power supply when the abnormality is determined. The fault detection device for a high-voltage switch circuit according to claim 1, wherein the fault is output. 5. A method according to claim 1, further comprising a third detecting means configured by using a transistor operated by inputting a control power supply voltage of the first stage, wherein an output of the third detecting means is a first level of the first stage. The fault detection device for a high-voltage switch circuit according to any one of claims 1 to 4, wherein the fault detection device is input to a detection unit. Failure detection device. 6. The apparatus according to claim 1, wherein said first detecting means comprises a photocoupler.
The high-voltage switch circuit according to any one of