JPS5825982B2 - Corona discharge charge quantification detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for quantifying and detecting the discharge charge amount of corona discharge that occurs periodically in accordance with the cycle of the power supply voltage, such as in a flyback transformer of a television receiver, for example. The purpose is to quantify while removing noise signals.

Conventional corona discharge detection devices are equipped with a calibration pulse generation circuit to calibrate the discharge charge, and the calibration pulse generated here is applied to the impedance or coupling circuit for corona signal detection via a capacitor, and the corona signal and calibration pulse are The amount of discharged charge is calibrated by comparing the magnitude of .

When calibrating the amount of discharged charge while observing the oscilloscope, synchronize the calibration pulse with the cycle of the power supply voltage to display it as a still image, and compare the magnitude of the calibration pulse displayed on the screen with the corona signal. By doing so, the amount of discharged charge is calculated.

In this case, the calibration pulse is made to exist over the entire cycle of the power supply voltage as much as possible to increase the brightness on the screen of the oscilloscope and to prevent flickering and make it easier to see.

FIG. 1a shows the observed waveform on the cathode ray tube of the oscilloscope in such a case.

In the figure, 1 is a power supply voltage waveform, 2 is a corona signal, and 3 is a calibration pulse.The calibration pulse 3 exists at a constant phase on the power supply voltage waveform 1.

The figure shows a state in which the corona signal 2 and the calibration pulse 3 are expressed on the Lissajous figure. In this case, too, if the calibration pulse 3 is present at a fixed phase with respect to the power supply voltage waveform 1, the calibration pulse will be generated. is displayed as a still image and can be compared with the corona signal.

On the other hand, a corona signal containing noise synchronized with the cycle of the power supply voltage is converted into a digital signal, and the corona signal exists in a first cycle, e.g., an odd-numbered cycle, and a second cycle, e.g., an even-numbered cycle, synchronized with the power supply voltage. When observing the corona signal by obtaining first and second digital signals and subtracting the second digital signal from the first digital signal to eliminate the noise, it is necessary to calibrate the amount of discharged charge. Therefore, when the calibration pulse is made to exist over the entire period of the power supply voltage, the same calibration pulse will enter both the first and second digital signals, and when subtracted, the calibration pulse will disappear and calibration will not be possible. .

FIG. 2 shows the observed waveforms in such a case, where a is the waveform of the first period, b is the waveform of the second period, 2 is the corona signal, 3 is the calibration signal, and 4 is the noise synchronized with the power supply voltage.

When the waveform a of the first period and the waveform S of the second period are subtracted, the noise disappears and the calibration signal also disappears at the same time as shown in C of the figure.

The present invention aims to solve such inconveniences, and the third aspect of the present invention is to
As shown in the figure, the calibration pulse 3 is present in the first period a synchronized with the power supply voltage, but the calibration pulse 3 is not present in the second period, and the calibration pulse 3 is not present in the digital signal of either period. By setting the calibration pulse generation circuit so that only the calibration pulse exists, as shown in FIG.

FIG. 4 shows a block diagram of an embodiment of the corona discharge charge quantification detection device according to the present invention, in which 5 is a drive circuit for driving a high voltage generation transformer, 6 is a high voltage generation transformer, 7 is a sample, and the high voltage The high pressure generated in the generation transformer 6 is the sample 7.
is applied to

8 is a coupling circuit or impedance coupled to the sample 7, and the corona signal detected by the coupling circuit is sent to the amplifier 9, A-D.
The digital signal of one period is converted into a digital signal through the converter 10 and the discriminator 11 and is sent to the subtracted signal storage circuit 12.
Also, the digital signal of the other period is stored in the subtraction signal storage circuit 13.

The signals read from the memory circuits 12 and 13 are sent to the adder/subtractor 1.
4, and the result is displayed on the display unit 16 via the DA converter 15.

17 is a trigger pulse generation circuit, 18 is a control circuit, and 19 is a calibration pulse generation circuit.The calibration pulse generated by the calibration pulse generation circuit 19 is added to the coupling circuit 8, so that the calibration pulse exists only in the digital signal of one period. I'll do what I do.

FIG. 5 shows an embodiment of the above-mentioned calibration pulse generation circuit 19, in which a rectangular wave signal synchronized with the power supply voltage and having the same frequency as the power supply voltage is applied as a clock pulse to the flip-flop circuit 21 from the input terminal 20. A rectangular wave signal having half the frequency of the clock pulse is generated as an output of the pull-up circuit 21.

This output is added as an input to the monostable multi-bi break 22, and a switching pulse having a pulse width sufficient to discharge the charge stored in the capacitor 24 is applied to the base of the switching transistor 23 that constitutes the discharge circuit of the charge/discharge capacitor 24. generate.

As a result, the charging/discharging capacitor 24 is charged/discharged every other cycle with respect to the power supply voltage.

25 is a DC power supply that charges the capacitor 24.

In this way, a discharge pulse having a known discharge amount determined by the capacitor 24, the resistor 26, etc. is inputted to the corona discharge detection coupling circuit 8 of FIG. 4 through the capacitor 27.

As described above, according to the present invention, a corona signal mixed with noise synchronized with the power supply voltage is converted into a digital signal, and the first and second digital signals existing in the first and second periods synchronized with the power supply voltage are converted into digital signals. By subtracting the second digital signal from the first digital signal, it is possible to eliminate the noise and quantify the amount of discharged charge when detecting corona discharge. The present invention can be used to quantify corona discharge of a flyback transformer or the like that generates high-order harmonics of the power supply voltage, and noise caused by the high-order harmonics can be removed to perform quantitative detection of corona discharge.

[Brief explanation of the drawing]

Fig. 1 is a conventional corona discharge observed waveform, Fig. 2 is an observed corona signal waveform mixed with noise pulses synchronized with the period of the power supply voltage, Fig. 3 is a diagram explaining the principle of the present invention, and Fig. 4 is the present invention. FIG. 5 is a block diagram of a circuit according to an embodiment of the present invention, and shows an example of a calibration pulse generation circuit of the present invention. 6... High voltage transformer, 7... Sample,
8... Combination circuit, 12, 13... Memory circuit, 14... Adjuster, 16... Display unit, 19... Calibration Pulse generation circuit.

Claims (1)

[Claims] 1. By converting the corona signals generated in the first period and the second period synchronized with the power supply voltage into digital signals and storing them separately in a storage device, and reading out and calculating the two stored signals. A corona discharge detection device for detecting corona discharge, characterized in that a calibration pulse generation circuit is provided for adding a calibration pulse only to a digital signal in one of the first period and the second period. Discharge charge quantification detection device.