JP2003143864A - State monitor of self-extinguishing semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor the state of a switching element accurately even when an inverter is stopping while being linked with a power system. SOLUTION: A failure detection circuit 10 conventionally monitors the state of a self-extinguishing element 1' in a self-excited inverter 2 by logically judging the output from a pulse generating circuit 6 generating an on/off command, and the output from a circuit 7 for monitoring the terminal voltage of the element 1'. Since a normal element 1' may be judged erroneously as a failed element when an inverter is stopping while being linked with a power system, a counter 16 for detecting the output from the failure detection circuit 10 is provided and a decision is made that the element 1' has failed only when the failure state thereof sustains for a predetermined time or longer thus avoiding erroneous judgment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a state monitoring device for making a failure determination by utilizing the presence / absence of a terminal voltage of a self-arc-extinguishing semiconductor element (also referred to as a self-arc-extinguishing element or simply element).

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a conventional example.
As a device for converting a direct current into an alternating current, as shown in FIG. 7, for example, a voltage type inverter 2 in which a diode 2'is connected in reverse parallel to a self-extinguishing type element 1'with respect to a direct current power source 1, is used.
There is a self-excited conversion method. The voltage type inverter 2 is connected to the electric power system 4 via the reactor 3. In this voltage type inverter 2, the pulse generation circuit 6 outputs an ON / OFF pulse of the element in response to the operation signal output from the sequence signal generation circuit 12, and the signal which is actually given to the element by the gate drive circuit 5. The switching operation is performed by converting to.

In such an inverter, the collector-emitter voltage of the self-extinguishing element is measured by the element voltage monitoring circuit 7 in order to detect the abnormality of the self-extinguishing element or diode, and the element voltage is above a certain level. There is a device that has a function of monitoring the element state based on the relationship between the return signal and the ON / OFF signal, which is “H” if there is and “L” if it is below.
That is, the failure detection circuit 10 is turned on / off as shown in FIG.
If the logic of the signal and the returned signal match, count it,
If they do not match, a counter for clearing them is provided, and if this counter exceeds a certain value, it is judged as a failure. When the failure detection circuit 10 determines that there is a failure, the pulse generation circuit 6 sets the ON / OFF signal to "L" to stop the switching operation of the inverter.

[0004]

When the inverter is connected to the power system, the voltage applied to each element is the difference between the DC power supply voltage and the AC power supply voltage. Therefore, the return signal is the AC voltage as shown in FIG. Is below a certain level, it is "L", and above is "H". In the element state monitoring circuit, there is a problem that if the return signal becomes "L" while the ON / OFF signal is "L", it is judged that the element has failed. In other words, even if the element is normal, if the AC voltage is below a certain level, it is determined as an element failure (erroneous determination). In order to avoid such a situation, if the inverter is disconnected from the electric power system every time the inverter is stopped, there arises a problem that the number of times the circuit breaker (3 ') is opened is increased and the life is shortened. Therefore, an object of the present invention is to enable accurate monitoring of the state of inverter elements without disconnecting the inverter from the power system even when the inverter is stopped in a state of being connected to the power system.

[0005]

In order to solve such a problem, according to the invention of claim 1, a voltage level between both ends of a self-extinguishing type semiconductor element of a self-excited inverter connected to a power system and ON / OFF. In a state monitoring apparatus for a self-extinguishing type semiconductor device having a monitoring means for performing failure monitoring based on a command signal, a detecting means for detecting an output from the monitoring means is provided, and the self-excited inverter is connected to a power system. In the case where the output from the detection means continues for a certain time or more, it is determined that a failure has occurred.

Further, in the invention of claim 1, level detecting means for detecting an instantaneous voltage level of the electric power system is provided, and the monitoring means and the detecting means when the instantaneous voltage level of the electric power system is a predetermined value or more. It is possible to perform a failure determination by (invention of claim 2), and in the invention of claim 2, instead of detecting the instantaneous voltage level of the power system, the detection of the instantaneous voltage phase is used instead. It is possible (the invention of claim 3).

[0007]

1 is a block diagram showing a first embodiment of the present invention, and FIG. 2 is an operation explanatory diagram of FIG.
Here, the failure signal output from the failure detection circuit 10 is "H" and "L" when the element is normal as shown in FIG.
Repeat, but if there is a failure, it becomes a continuous signal of "H".
Therefore, a failure confirmation counter 1 that counts when this failure signal is "H" and clears when this failure signal is "L"
6 is provided. In this way, the counter 16 can determine that the element is destroyed when the count value becomes equal to or larger than a predetermined value (a value counted when the element is normal). The determination result is notified to the pulse generation device 6.

FIG. 3 is a block diagram showing a second embodiment of the present invention, and FIG. 4 is an operation explanatory diagram of FIG. this is,
In contrast to what is shown in FIG. 1, a signal inversion circuit 8, a signal selection circuit 9, a selection signal generation circuit 11 and a voltage level monitoring circuit 1
It is configured by adding 4 etc. Note that reference numeral 15 indicates a failure monitoring start level.

The voltage level monitoring circuit 14 compares the AC voltage detected by the voltage detector 4'with a fault monitoring start level, and outputs a signal which becomes "H" to the selection signal generating circuit 11 when the AC voltage increases. give. The selection signal generation circuit 11 receives the inverter operation signal from the sequence signal generation circuit 12 to recognize the stop and operation of the inverter.
The selection signal as shown in is output to the signal selection circuit 9.

The signal selection circuit 9 selects the return signal from the element voltage monitoring circuit 7 when the selection signal is "H",
When the signal is "L", a signal obtained by inverting the ON / OFF signal by the signal inverting circuit 8 is selected. Therefore, the signal monitored by the failure detection circuit 10 is "H" when the element is normal as shown in FIG. It becomes a continuous signal, and "L" when abnormal (fault)
Becomes Therefore, in the failure detection circuit 10, the output pulse from the pulse generator 6 and the logic of the monitoring signal from the element voltage monitoring circuit 7 match only when the element fails.
The element failure can be accurately detected.

FIG. 5 is a block diagram showing a third embodiment of the present invention, and FIG. 6 is an operation explanatory diagram of FIG. this is,
Instead of the voltage detector 4 ′ and the voltage level monitoring circuit 14 shown in FIG. 3, a zero cross level detection circuit 13 and a phase detection counter 17 are provided. The phase detection counter 17 outputs a value that changes from 0 to a constant value as shown in FIG. 6 according to the output of the zero-cross level detection circuit 13 that detects the zero-cross level of the AC voltage. The selection signal generation circuit 11 receives the inverter operation signal from the sequence signal generation circuit 12 to recognize whether the inverter is stopped or operated, and when it is stopped, the selection signal shown in FIG. The signal is output to the signal selection circuit 9. Since the subsequent steps are the same as in the case of FIG. 3, description thereof will be omitted.

[0012]

According to the present invention, even when the voltage type inverter connected to the AC power supply is stopped, the element state can be accurately monitored by monitoring the collector-emitter voltage of the self-turn-off type element. . In addition, since there is no need to disconnect from the electric power system even when stopped, there is an advantage that the number of times the circuit breaker is opened is reduced and the life is extended.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of FIG.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of FIG. 3;

FIG. 5 is a block diagram showing a third embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of FIG. 5;

FIG. 7 is a block diagram showing a conventional example.

FIG. 8 is an operation explanatory diagram of FIG. 7;

FIG. 9 is a diagram illustrating a conventional problem.

[Explanation of symbols]

1 ... DC power supply, 1 '... self-extinguishing element, 2 ... voltage type inverter, 2' ... diode, 3 ... reoutle, 3 '... circuit breaker, 4 ... AC power supply, 4' ... voltage detector, 5 ... gate Drive circuit, 6 ... Pulse generator, 7 ... Element voltage monitoring circuit,
8 ... Signal inversion circuit, 9 ... Signal selection circuit, 10 ... Failure detection circuit, 11 ... Selection signal generation circuit, 12 ... Sequence signal generation circuit, 13 ... Zero cross level detection circuit, 14 ... Voltage level monitoring circuit, 15 ... Failure monitoring Starting level, 16 ...
Failure confirmation counter, 17 ... Phase detection counter.

Claims (3)

[Claims] 1. A self-extinguishing semiconductor device having a monitoring means for performing failure monitoring based on a voltage level across both ends of a self-extinguishing semiconductor device of a self-excited inverter connected to a power system and an ON / OFF command signal. In the state monitoring device, the detection means for detecting the output from the monitoring means is provided, and when the self-excited inverter is stopped in a state of being connected to the power system, the output from the detection means is kept for a certain period of time. A state monitoring device for a self-extinguishing type semiconductor element, characterized in that it is judged as a failure when the above is continued. 2. A level detection means for detecting an instantaneous voltage level of the electric power system is provided, and when the instantaneous voltage level of the electric power system is equal to or more than a predetermined value, the monitoring means and the detection means make a failure determination. The condition monitoring apparatus for a self-extinguishing type semiconductor device according to claim 1. 3. The state monitoring apparatus for a self-arc-extinguishing semiconductor device according to claim 2, wherein an instantaneous voltage phase is detected instead of detecting the instantaneous voltage level of the power system.