JP3705119B2 - Power supply abnormal waveform detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply abnormal waveform detection device, and in particular monitors commercial AC power supplies of 50 Hz and 60 Hz and captures abnormal phenomena such as instantaneous interruption, sag, impulse, small amplitude noise, waveform distortion, etc. appearing in the power supply waveform in real time. The present invention relates to a power supply abnormal waveform detection device to be displayed.
[0002]
[Prior art]
Recently, in medical practice, there is a problem that an image is disturbed while using a medical image diagnostic apparatus such as a CT scanner, and thus a diagnosis is performed again. Therefore, there is a need for a power supply abnormality waveform detection device that can easily and inexpensively monitor a power supply waveform in order to identify whether the cause of the trouble is a malfunction of the CT scanner body or the influence of a power supply abnormality. Accordingly, a wave window trigger (WWT) type power supply abnormal waveform detection apparatus has been put into practical use.
[0003]
As shown in FIG. 6, the WWT power supply abnormal waveform detection apparatus is configured to reliably capture various noises superimposed on the power supply waveform, and is not only for power supply monitoring, but also for 4 analog signals and 8 digital bits. By combining this input with this trigger, it is useful when investigating the effects of power supply abnormalities on devices and the effects of devices on power supplies.
[0004]
In addition, since this WWT system power supply abnormality waveform detection device has a 4-channel input, it can measure from a single-phase commercial power supply to a three-phase three-wire power supply with a single unit. Since it is possible to analyze up to the 40th order and measure the power phase angle, it is possible to determine harmonics.
[0005]
Furthermore, the WWT power supply abnormality waveform detector has a FAX modem as an external interface, so that immediately after a power supply abnormality occurs, power supply waveform information is sent by FAX to the central control room, etc., so that it can be understood at a glance what has happened in the field. It has become. Accordingly, it is possible to quickly respond to power supply abnormality and to save the labor of the patrol work.
[0006]
Hereinafter, the basic principle of the WWT method will be described. As shown in FIG. 7, the WWT system is smaller than the analog input signal 30 and the higher-order reference waveform signal 31 of a sine wave having a larger amplitude than the analog input signal 30 which is a commercial AC power supply of 50 or 60 cycles to be monitored. One cycle of digital data representing the lower-order reference waveform signal 32 of a sine wave having amplitude is created, and the time axis of this digital data is stored in the memory as an address. A data region surrounded by the upper and lower reference waveform signals 31 and 32 that are upper and lower sine wave signals is called a wave window 33.
[0007]
The analog input signal 30 is converted into 11-bit digital data by an A / D converter at a sampling rate of 400 kS / sec. In the WWT method, it is monitored whether the digital data at each sampling point does not deviate from the wave window stored in the wave window 33. Specifically, the instantaneous value of the analog input signal 30 at a certain time point is compared with the instantaneous values of the upper and lower reference waveform signals 31 and 32 at the same time point. If the instantaneous value of the analog input signal 30 is larger than the instantaneous value signal of the upper reference waveform signal 31 at the same time, the analog input signal 30 deviates upward from the wave window 33. If the instantaneous value of the analog input signal 30 is smaller than the instantaneous value signal of the lower-order reference waveform signal 32 at the same time, the analog input signal 30 deviates downward from the wave window 33. In either case, it is recognized that the power supply waveform is abnormal.
[0008]
When the waveform of the analog input signal 30 is normal, the measurement data for each sampling is within the data area of the wave window 33. However, the analog input signal 30 is like an instantaneous stop, sag, or impulse as indicated by an arrow in FIG. When a waveform abnormality occurs, the sampling data of the analog input signal 30 protrudes from the wave window 33. Thus, when the input data protrudes from the wave window 33, a wave window trigger is output to detect a power supply abnormality.
[0009]
The wave window trigger is monitored in units of one cycle. This trigger signal for starting monitoring in units of one cycle is called a synchronous trigger. The synchronization trigger is necessary to perform temporal association, that is, synchronization between the data of the wave window 33 and the output data of the analog input signal 30.
[0010]
The synchronization trigger is selected from a plurality of, for example, four measurement channels with the most stable waveform (referred to as a synchronization channel), and is extracted from this synchronization channel as follows.
[0011]
The synchronization trigger includes a rise type synchronization trigger that is set to be generated when the input signal of the synchronization channel becomes equal to or higher than a preset level (synchronization trigger level) value STL, and a synchronization trigger level value STL or less. There is a Fall-type synchronous trigger that is set to occur when FIG. 8 shows an example of the Fall type synchronous trigger. As shown in FIG. 8, the wave window trigger cannot be detected until the first synchronization trigger is applied after the measurement is started. However, after the first synchronization trigger is applied, the wave window trigger is monitored in the order of A, B, C,.
[0012]
A generation condition is imposed on the synchronous trigger. For example, in the Rise type synchronous trigger, the synchronous trigger is generated when the measured value becomes higher than the synchronous trigger level STL by the designated number of continuous measurements. As shown in FIG. 9, the measured value becomes larger than the synchronous trigger level value STL at the point A, but immediately after that, since the measured value becomes smaller than the synchronous trigger level value STL, no synchronous trigger is applied. The measured value again becomes larger than the synchronous trigger level value STL at the point B, and after that, the state that is higher than the synchronous trigger level value STL is maintained until the third measurement point C including the B point. A synchronization trigger is activated.
[0013]
As described above, the WWT system power supply abnormal waveform detection apparatus can monitor the continuous waveform of the analog input signal seamlessly for each cycle by starting monitoring in units of one cycle by the synchronization trigger.
[0014]
[Problems to be solved by the invention]
However, the power supply abnormality waveform detecting apparatus using the WWT method has a problem that it cannot cope with the abnormality of the power supply waveform as shown in FIG. That is, as in the case of FIG. 10A, noise of a small amplitude is superimposed on the analog input signal 30, and the analog input signal 30a that is a noise superimposed signal on which the noise is superimposed is within the wave window 33. Cannot be detected by the WWT method. Further, as shown in FIG. 10B, when the input signal is distorted, even if the analog input signal 30b having a distorted waveform is within the wave window 33, it cannot be detected by the WWT method. There's a problem.
[0015]
Accordingly, there is a problem in providing a power supply abnormality waveform detecting apparatus that eliminates the above-mentioned problems of the prior art and can detect any power supply abnormality waveform.
[0016]
[Means for Solving the Problems]
[0017]
In order to solve the above-described problems, a power supply abnormal waveform detection apparatus according to the present invention is configured as follows.
[0018]
(1) Means for storing a reference waveform signal having the same phase or substantially the same phase as an analog input signal as a power supply in a memory, and a point where the analog input signal intersects with a preset value of a synchronous trigger level signal As a synchronization trigger signal, means for accumulating the absolute value of the difference between the analog input signal between the synchronization trigger signals and the reference waveform signal stored in the memory, and the accumulated data are set in advance. A power supply abnormality waveform detecting device comprising: means for judging that the analog input signal is abnormal when a predetermined trigger setting value is exceeded.
(2) In the means for setting as the synchronization trigger signal, the detection of the point where the analog input signal intersects with the value of the synchronization trigger level intersects with the value of the synchronization trigger level when the analog input signal is in the upward direction. The power supply abnormality waveform detecting device according to (1), characterized in that it is a point.
(3) The power supply abnormal waveform detection according to (1), wherein the synchronization means includes a plurality of synchronization trigger signals between synchronization trigger signals that specify a period during which the analog input signal is accumulated. apparatus.
(4) The power supply abnormal waveform detection device according to (1), wherein the analog input signal is a commercial AC power supply of 50 or 60 Hz.
(5) In the means for determining that the analog input signal is abnormal, the signal determined to be abnormal is stored in a memory, and the stored data is appropriately displayed. The power supply abnormality waveform detection apparatus described.
(6) The power supply abnormality waveform detecting apparatus according to (1), wherein the reference waveform signal is an upper side and lower side reference waveform signal having a predetermined width with respect to the analog input signal.
[0019]
The power supply abnormality waveform detection device having such a configuration detects the waveform abnormality by comparing the analog input signal as a power supply with the reference waveform signal and accumulating the difference between the synchronization trigger signals. Small amplitude noise and distortion can be reliably detected as well as instantaneous interruption, sag, and impulse generated in the power supply.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a power supply abnormality waveform detecting apparatus according to the present invention will be described in detail with reference to the drawings.
[0021]
As shown in FIG. 1, the power supply abnormal waveform detection apparatus according to the present invention includes an amplifier 1 that amplifies an analog input signal that is a commercial AC power supply of 50 Hz or 60 Hz, and an A / A that converts the amplified analog input signal into a digital value. A D-converter 2 and a synchronization trigger detector 3 having means for setting, as a synchronization trigger signal ST, a point where the analog input signal converted into the digital value intersects a preset synchronization trigger level value STL; A memory controller 4 for reading a reference waveform signal in response to the synchronization trigger signal ST, and a reference waveform memory 5 having means for storing a reference waveform signal having the same phase or substantially the same phase as an analog input signal as a power source; The comparator 6 that compares the reference waveform signal and the analog input signal converted into the digital value, and the absolute value of the difference between the signals compared by the comparator 6 are calculated. A counter circuit 7, an accumulator 8 that accumulates the calculated absolute value, a comparator 9 that compares the accumulated data with a preset trigger setting value TL, and the accumulated data is greater than or equal to the trigger setting value TL The memory controller 10 for storing the address of the analog input signal as the abnormal waveform trigger T, the waveform memory 11 for reading the data of the analog input signal according to the abnormal waveform trigger T of the memory control 10, and the display of the accumulated waveform data The display controller 12 controls the display, the display 13 displays the abnormal waveform data of the ananlog input signal, and the sampling controller 14 samples the analog input signal between the synchronization trigger signals ST.
[0022]
An analog input signal 30 which is a commercial AC power supply of 50 or 60 cycles to be monitored is input to the amplifier 1. The amplifier 1 amplifies the analog input signal 30 with an appropriate gain and outputs the amplified signal to the A / D converter 2.
[0023]
The A / D converter 2 converts an analog input signal output from the amplifier 1 into a digital data from a sampling rate defined by the sampling controller 14, that is, an analog input signal between the synchronization trigger signals ST. The digital data output from the A / D converter 2 is supplied to the synchronization trigger detector 3, the comparator 6, and the waveform memory 11.
[0024]
As shown in FIG. 2, the synchronization trigger detector 3 outputs a synchronization trigger signal ST when the analog input signal 30 becomes equal to or higher than a preset synchronization trigger level value STL (Rise type synchronization trigger). The value STL of the synchronization trigger level is set to a value that matches the first data value of the reference waveform data stored in the reference waveform memory 5. The synchronization trigger signal ST output from the synchronization trigger detector 3 is output to the memory controller 4 and the accumulator 8.
[0025]
The memory controller 4 supplies a read signal to the reference waveform memory 5 in response to the synchronization trigger signal ST received from the synchronization trigger detector 3. This operation is performed every time the synchronization trigger signal ST is input thereafter.
[0026]
The reference waveform memory 5 stores the waveform data of the reference waveform signal 34 of one cycle as shown in FIG. 3 with the time axis as an address. When the reference signal is supplied from the memory controller 4 to the reference waveform memory 5, the waveform data is read from the first address and output to the comparator 6. Thereafter, the waveform data of the reference waveform signal 34 is sequentially read out and output to the comparator 6 at the read timing synchronized with the sampling of the analog input signal 30. As described above, the reference waveform signal 34 is formed in a waveform that is in phase or substantially in phase with the waveform of the analog input signal. The reference waveform signal 34 may be the analog input signal to be measured described in the prior art and the upper and lower reference waveform signals having a predetermined amplitude. In this case, it is very easy to add the function of the present invention to the abnormal waveform detection mechanism based on the WWT (Wave Window Trigger) method described in the prior art.
[0027]
The comparator 6 compares the output data from the A / D converter 2 with the data of the reference waveform signal 34 from the reference waveform memory 5 for each sampling point. The comparator 6 has calculation means for subtracting (reference value) − (measured value), and outputs the calculation result to the absolute value circuit 7.
[0028]
The absolute value circuit 7 has means for converting the operation result of the comparator 6 into an absolute value, and outputs this absolute value to the accumulator 8.
[0029]
The accumulator 8 has accumulating means for accumulating the absolute value received from the absolute value circuit 7. This accumulating means comprises a memory register SUM and an adder, and performs an operation of SUM = SUM + A. As a result, the absolute value A is accumulated in the SUM. The accumulator 8 outputs the contents of the memory register SUM to the comparator 9 every time the accumulation operation is completed. The accumulator 8 clears the memory register SUM to 0 each time it receives the synchronization trigger signal ST from the synchronization trigger detector 3. That is, the accumulation operation in the accumulator 8 is updated for each synchronization trigger signal ST.
[0030]
The comparator 9 compares the accumulated value SUM input from the accumulator 8 with a preset trigger setting value TL, and when the accumulated value SUM exceeds the trigger setting value TL, an abnormal waveform is recognized. A trigger T is generated and output to the memory controller 10.
[0031]
When the memory controller 10 receives the abnormal waveform trigger T from the comparator 9, it supplies this as the address of the waveform memory 11.
[0032]
The waveform memory 11 stores waveform data of a predetermined number of cycles of the analog input signal 30 output from the A / D converter 2 while sequentially updating it. The waveform memory 11 reads out abnormal waveform data according to the address received from the memory controller 10 and outputs it to the display controller 12. The abnormal waveform data is displayed on the display unit 13 under the control of the display controller 12.
[0033]
The sampling controller 14 samples the analog input signal 30 between the synchronization trigger signals ST, and a plurality of synchronization trigger signals ST may exist between the synchronization trigger signals ST. If a plurality of synchronous trigger signals ST are used, even a noise or distortion minute noise signal superimposed on the analog input signal 30 can be captured.
[0034]
The power supply abnormal waveform detection apparatus operates as follows.
When the waveform of the analog input signal 30 is not disturbed as shown in FIG. 4A, there is almost no difference between the waveform data of the analog input signal and the waveform data of the reference waveform signal at each sampling point. As shown in (B), the accumulation result SUM in the accumulator 8 does not become larger than the trigger set value TL. As a result, the abnormal waveform trigger T is not output from the comparator 9.
[0035]
However, as shown in FIG. 5A, when the analog input signal 30a is obtained by superimposing small amplitude noise on the reference waveform signal 34 (see FIG. 3), the sampling value of the input signal 30a and the corresponding value. There is a considerable difference between the data value of the reference waveform signal 34. The accumulated value SUM obtained by accumulating the absolute value of this difference with the accumulator 8 increases as time passes as shown in FIG. 5B, and exceeds the trigger set value TL at the predetermined time t1 of the synchronization trigger ST interval. It will be.
[0036]
As a result, the trigger signal T is output from the comparator 9, the waveform data is read from the waveform memory 11, and displayed on the display 13.
[0037]
The above-described operation of the power supply abnormal waveform detection apparatus according to the present invention is not limited to the analog input signal 30a on which noise is superimposed as shown in FIG. Needless to say, the present invention is applied to all abnormal waveforms such as instantaneous interruption, sag, and impulse as shown in FIG.
[0038]
As another embodiment of the power supply abnormality waveform detecting apparatus according to the present invention, the accumulation operation of the accumulator 8 may be continued for a plurality of times of the synchronization trigger signal ST. As a result, since the accumulation duration time becomes long, even when the difference between the analog input signals 30, 30a and the reference waveform signal 34 is small, the accuracy of detecting the difference is improved.
[0039]
As another embodiment, the accumulation by the accumulator 8 may be performed a plurality of times during one synchronization trigger ST.
As another embodiment, the accumulator 8 may accumulate the absolute value only when the absolute value output from the absolute value circuit 7 exceeds a predetermined value.
[0040]
The accumulator 8 may add 1 each time the absolute value exceeds a predetermined value. Further, the comparator 6 sets the sign of the difference between the input signal data and the reference waveform signal data one sample before. The accumulator 8 may accumulate the absolute value of the difference only when the sign changes alternately.
[0041]
【The invention's effect】
As described above, the power supply abnormal waveform detection apparatus according to the present invention cannot detect the instantaneous power failure, sag, and impulse generated in the input signal, and cannot be detected by the conventional power supply abnormal waveform detection apparatus using the WWT method. Therefore, it is possible to reliably detect abnormal waveforms of power input signals including small amplitude noises and small waveform distortions. Can be easily and quickly identified.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration of an embodiment of a power supply abnormality waveform detecting apparatus according to the present invention.
FIG. 2 is an explanatory diagram of the operation of the synchronous trigger detector 3 shown in FIG.
3 is an explanatory diagram of the operation of the reference waveform memory 5 shown in FIG. 1. FIG.
FIG. 4 is an explanatory diagram of the operation of the power supply abnormality waveform detection device shown in FIG. 1;
FIG. 5 is an explanatory diagram of the operation of the power supply abnormal waveform detection device shown in FIG. 1;
FIG. 6 is an explanatory diagram of a conventional power supply abnormal waveform detection device.
FIG. 7 is an explanatory diagram of WWT, which is the basic principle of a conventional power supply abnormal waveform detection device.
FIG. 8 is an explanatory diagram of a synchronization trigger in WWT.
FIG. 9 is an explanatory diagram of a synchronization trigger in WWT.
FIG. 10 is an explanatory diagram showing waveforms that cannot be detected by WWT.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Amplifier 2 A / D converter 3 Synchronous trigger detector 4 Memory controller 5 Reference waveform memory 6 Comparator 7 Absolute value circuit 8 Accumulator 9 Comparator 10 Memory controller 11 Waveform memory 12 Display controller 13 Display 14 Sampling controller 30 Input signal 31 Upper signal of wave window 32 Lower signal of wave window 33 Wave window 34 Reference waveform signal 30a Noise-loaded input signal SUM Accumulated value ST Synchronization trigger STL Synchronization trigger level value T Trigger TL Trigger setting value

Claims (6)

Means for storing a reference waveform signal in phase or substantially in phase with an analog input signal as a power supply in a memory;
Means for setting, as a synchronization trigger signal, a point where the analog input signal intersects a preset value of the synchronization trigger level;
Means for accumulating the absolute value of the difference between the analog input signal between the synchronization trigger signals and the reference waveform signal stored in the memory;
A power supply abnormality waveform detecting apparatus comprising: means for determining that the analog input signal is abnormal when the accumulated data is equal to or greater than a preset trigger setting value. In the means for setting as the synchronization trigger signal, the detection of the point where the analog input signal crosses the value of the synchronization trigger level is a point where the analog input signal crosses the value of the synchronization trigger level when the analog input signal is in the upward direction. The power supply abnormal waveform detection apparatus according to claim 1. 2. The power supply abnormality waveform detecting apparatus according to claim 1, wherein the accumulating unit includes a plurality of synchronization trigger signals between synchronization trigger signals that specify a period during which the analog input signal is accumulated. The power supply abnormal waveform detection device according to claim 1, wherein the analog input signal is a commercial AC power supply of 50 or 60 Hz. 2. The power supply according to claim 1, wherein in the means for determining that the analog input signal is abnormal, the signal determined to be abnormal is stored in a memory, and the stored data is appropriately displayed. Abnormal waveform detection device. 2. The power supply abnormality waveform detection apparatus according to claim 1, wherein the reference waveform signal is an upper side and lower side reference waveform signal having a predetermined width with respect to the analog input signal.

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