JPH07123348B2 - Load sharing status monitor for multiple devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a load sharing state monitoring device for a plurality of elements.

In a thyristor excitation device, a frequency converter, etc. related to a hydraulic power generation control device, a plurality of semiconductor power devices such as high voltage / large current type thyristors or power transistors are connected in series or in parallel. These elements can be adjusted so that the voltage and current are equally shared by each element at the beginning of connection. However, each element has slightly different characteristics due to manufacturing variations,
Further, since the cooling is slightly different depending on the mounting portion in the actual machine, even if the respective elements are initially made equal in share, a particular element is deteriorated due to long-time operation. Further, deterioration of the specific element is promoted by electrical / mechanical stress applied from the outside, and it is unavoidable that the specific element is destroyed by such deterioration. Moreover, when at least one of the plurality of elements is deteriorated, the equal state in the sharing is broken, and the deterioration of the element is further promoted. When the deterioration of at least one element is extremely advanced, it is inevitable that it adversely affects the entire device.

(Problems to be Solved by the Invention) In order to determine whether each element is in an abnormal state, it is necessary to know the shared voltage / shared current of each element. For that purpose, those voltages / currents may be directly measured as voltages / currents. However, since both the voltage and the current have large values, it is unavoidable that the measuring instrument becomes large and expensive. The voltage / current can be indirectly detected from other physical quantities showing values corresponding to them. As such an indirect detector, there was a temperature detector such as a temperature fuse that focuses on the temperature showing a value according to the voltage and current, but the problem is that the temperature detector is affected by the ambient temperature. In addition, there are various problems such as a large error in the detected temperature. Also, there are temperature relays such as bimetal, thermostat and resistance temperature detector as temperature detectors, but the temperature detection points of these relays are also fixed, so they are easily affected by the ambient temperature and accurate temperature detection can be performed. There was a problem that it did not exist.

It is an object of the present invention to provide an apparatus capable of monitoring a load sharing state of a plurality of elements and detecting a deteriorated element among them.

[Structure of Invention]

(Means for Solving Problems) A load sharing state monitoring device of the present invention is a temperature sensor that detects the temperature of each of a plurality of elements that share a load based on heat radiation from those elements, and the temperature of those sensors. A reference signal generating means for generating a reference signal consisting of an average value and a standard deviation of the temperatures of the plurality of elements based on the detection signal of the sensor, and comparing each of the detection signals and the reference signal with each other. And a comparing means for selectively outputting an abnormal signal when the temperature is away from the average value by a predetermined constant multiple of the standard deviation.

(Operation) The temperature of each of the plurality of elements that share the load is detected by the temperature sensor from a remote position. A reference signal is generated by the reference signal generation means based on those detection signals. The reference signal is individually compared with a plurality of detection signals from the temperature sensor. When the comparison result of a certain detection signal and the reference signal is abnormal, for example, when the difference between the compared signals is larger than a predetermined set value,
An abnormality signal is output from the comparison means, and the abnormality of the element corresponding to the detection signal is known.

(Embodiment) FIG. 1 is a block diagram showing a monitoring device according to a first embodiment of the present invention. In the figure, 1, 1, ... Denote power semiconductor elements such as thyristors as temperature measurement targets. Reference numerals 2, 2, ... Are temperature sensors for measuring the temperatures of the semiconductor elements 1, 1 ,. As the temperature sensor 2, various elements that convert heat radiation from a semiconductor element into an electric signal according to the radiation amount, for example, an infrared sensor can be used. Next to the temperature sensors 2, 2, ..., Temperature compensation circuits 3, 3, ... And A / D converter
The digital computer 5 is connected via 4, 4, .... The temperature correction circuit 3 corrects the output from the temperature sensor 2 so that the output from the temperature sensor 2 is linear with respect to the temperature. The temperature correction circuit 3 corrects the characteristic curve of the temperature sensor 2 and the characteristics of each sensor. Correct the variation of. The digital computer 5 functions as having a reference signal generating means and a comparing means as described below. That is, the A / D converter 4,
Based on the outputs from 4, ..., The average value and standard deviation (standard signal) of all the outputs are obtained at each fixed time. The deviation between the individual output from each A / D converter 4, 4, ... And the average value is obtained. Compare each of those deviations with the standard deviation. As a result of the comparison, if one of the former signals is larger than the latter signal by more than the set value obtained by multiplying the standard deviation by a constant (for example, 1/4), an abnormal signal is output. The signals continuously input to the digital computer 5 from the A / D converters 4, 4, ... Are averaged at regular time intervals, and the signal processing as described above is performed based on the averaged signals. You can also do it.

Further, the digital computer 5 can be provided with the following functions. That is, the average value (standard signal) of all outputs of the A / D converters 4, 4, ... The individual output from each A / D converter 4, 4, ... Is compared with its average value. As a result of the comparison, if even one of the former signals is larger than the latter signal by a predetermined set value, an abnormal signal is output. Furthermore, the digital computer 5 can be provided with the following functions. That is, the individual output from each A / D converter 4, 4, ... Is compared with the above-mentioned two kinds of set values to obtain their difference signals. Differentiate their difference signals over time. An abnormal signal is output when the differentiated value is larger than a predetermined value or a value obtained from the standard deviation.

There are two kinds of abnormal signals described above, one is an alarm signal 6 indicating that one of the semiconductor elements 1, 1, ... Is in an abnormal state, and the other is which semiconductor element 1,1. Are individual abnormal signals 7, 7, ... Indicating whether or not is in an abnormal state. The alarm signal 6 is obtained as a logical sum of the individual abnormality signals 7, 7, .... The individual abnormality signals 7, 7, ... Are transmitted to the CRT 8 in the next stage, and which CRT 8 indicates which semiconductor element 1, 1 ,.

FIG. 2 is a block diagram showing a monitoring device according to the second embodiment of the present invention. In the figure, reference numerals 11, 11, ... Denote semiconductor elements as measurement targets, as in the case of the first embodiment. 1
Reference numerals 2, 12, ... Are temperature sensors similar to those in the first embodiment, and a digital computer 15 is connected to their subsequent stages via an analog switch (analog multiplexer) 13 and an A / D converter 14. The analog switch 13 is switched at high speed by the control signal from the computer 15, and the temperature sensor 12,1
The output signals from 2, ...
Send to D converter 14. The output signals from the temperature sensors 12, 12, ... Are converted into digital signals by the A / D converter 14 and then sent to the digital computer 15, and these signals are transferred to the temperature in the computer 15 in the first embodiment. The correction is performed in the same manner as the correction circuits 3, 3, .... The corrected signals are then processed in the same manner as in the case of the first embodiment to output the abnormal signal 16 and the individual abnormal signals 17, 17, ...
8 shows which semiconductor element 11, 11, ... Is abnormal.

The monitoring device of the above-described embodiment of the present invention has the following effects. That is, the load sharing state performed by the plurality of semiconductor elements 1 and 11 can be detected by the heat generated by those elements 1 and 11. In this way, the detection of the semiconductor element 1,1
Since it does not directly measure the high voltage or large current applied to 1, it has various advantages, for example, there is an advantage that no special consideration is required for dielectric strength, electric shock or noise. Since the outputs from the temperature sensors 2 and 12 are corrected by the temperature correction circuit 3 (first embodiment) having a correction function or the digital computer 15 (second embodiment), the characteristics of the temperature sensors 2 and 12 themselves. Of the temperature sensors 2 and 12 and the variation of the arrangement positions of the temperature sensors 2 and 12 with respect to the power semiconductor elements 1 and 11, and the like, and highly accurate temperature detection is possible. Furthermore, when comparing the detected values of the temperature sensors 2 and 12 to detect whether or not there is an abnormal state, the detected values are corrected as described above, and after being corrected as reference signals to be compared. Since the standard deviation (or average value) of the signal is used, it is possible to stably detect whether or not there is an abnormality without being affected by the ambient temperature. As a result, it is possible to accurately detect the deterioration state of the semiconductor elements 1 and 11 that is difficult to detect slowly over a long period of time, and to detect the progress of deterioration of these elements 1 and 11 before the failure regardless of the failure. it can. Therefore,
It is possible to detect in advance semiconductor elements that may fail, and improve the reliability and operating rate of the entire system using those semiconductor elements.

〔The invention's effect〕

As described above, according to the monitoring device of the present invention, it is possible to easily and highly accurately detect whether or not some of the plurality of elements are in a normal state.

[Brief description of drawings]

FIG. 1 is a block diagram showing a monitoring device according to a first embodiment of the present invention, and FIG. 2 is a block diagram showing a monitoring device according to a second embodiment of the present invention. 1,11 …… Semiconductor element, 2,12 …… Temperature sensor, 3 …… Temperature correction circuit, 4,14 …… A / D converter, 5,15 …… Digital calculator, 6,16 …… Alarm signal, 7,17 …… Individual abnormal signal, 8,18
…… CRT, 13 …… Analog switch.

Claims (1)

[Claims] 1. A temperature sensor for detecting the temperature of each of a plurality of elements sharing a load based on heat radiation from the elements, and a temperature sensor for detecting the temperature of the plurality of elements based on a detection signal from the temperature sensor. Reference signal generating means for generating a reference signal composed of an average value and a standard deviation, and the temperature of each element by comparing the detection signal and the reference signal respectively from a predetermined constant multiple of the standard deviation from the average value. A load sharing state monitoring device for a plurality of elements, the comparing device selectively outputting an abnormal signal when the two are apart from each other.