JPH0217470A - Tester of high-frequency breakdown strength - Google Patents

Abstract

PURPOSE:To make it possible to attain, through automatic tuning, a state of resonance of a resonant circuit formed of the inductance of a specimen coil connected to a tester and of a resonance capacity incorporated in the tester, by using a phase control loop (PLL circuit). CONSTITUTION:When a specimen coil (an inductance L) for a breakdown strength test is connected to a tester, a voltage on a point B on the output resonance element to which a resonance capacity C incorporated in the tester and the coil L are connected is separated by a pressure separating circuit and detected, and it is subjected to wave- shaping by a comparator and inputted to a phase comparator P1 constituting a PLL circuit D. A voltage at a point A on the output amplifying element side is subjected to wave-shaping and also inverted by an NOT circuit and is inputted to the comparator P1. An output of the comparator P1 corresponding to a phase difference between the points A and B is inputted to a voltage control oscillator P3 through a low-pass filter P2. Since a phase difference of a voltage generated on the primary and secondary sides of a resonant transformer T is added at the time of resonance, the oscillation frequency of the oscillator P3 is controlled so that the phase difference between the points A and B be 180 deg., and thus the uatomatic tuning of a resonant circuit is attained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is an automatic tuning method which is effective for use in interlayer voltage withstanding tests of high frequency coils such as deflection coils used in television receivers, cathode ray tube display devices, etc. The present invention relates to a high-frequency withstand voltage tester with functions.

<Prior art> Figure 5 is a block diagram showing the general configuration of a resonant type withstand voltage tester used for interlayer withstand voltage tests of high frequency coils such as deflection coils. FIG. 2 is a circuit diagram for explaining a series resonant circuit used in a tester.

As shown in Figure 2, this type of voltage tester generates a sine wave voltage obtained by resonance of a series resonant circuit consisting of the inductance (L) of the deflection coil and the resonant capacitance (C) built into the voltage tester. (Frequency: 100 & AC2~3
kV) is applied to the coil under test. Then, for the eyebrow voltage test of the coil, connect the test coil to a voltage tester, and while manually changing the oscillation frequency, tune the series resonant circuit made up of the inductance and resonance capacitance of the test coil to a synchronized state. Then, a variable resistor for adjusting the output voltage is manually adjusted, and a voltage corresponding to the inductance of the coil under test is applied to the coil.

<Problem to be solved> In the conventional voltage tester mentioned above, the operation of changing the oscillation frequency in order to tune the series resonant circuit, or the operation of adjusting the voltage applied to the test coil, cannot be performed manually. The operation is delicate and requires great skill.
If the tuning is incomplete, abnormal oscillation will occur, leading to damage to the various elements of the voltage tester. Therefore, these tuning operations take time and are difficult to operate unless you are an experienced operator. There are some problems. Furthermore, when multiple coils with different inductances are passed through the same test line, it is necessary to prepare multiple voltage testers corresponding to the inductance of each coil, making it difficult to automate the coil inspection line. The present invention has been made to eliminate these drawbacks.

<Means for solving the problem> A resonant voltage tester is configured using a phase control loop (PLL circuit), and the inductance of a test coil connected to the voltage tester and the resonant capacitance built into the voltage tester are The first configuration is that the resonant layer of the resonant circuit made of 311! The configuration is such that it can be

<Operations and Examples> In this type of resonant type withstand voltage tester, the following relationship exists during resonance in the series resonant circuit.

・E ・Resonant current I0=/ ・Voltage between coil terminals ・ , ω14 ・E a
=J E (31・Q of coil
Q=.

Therefore, if there is an insulation defect such as a layer short between the layers of the test coil, the Q of the coil becomes small, so (
As is clear from equations 3) and (4), poor insulation of the coil is confirmed when the voltage E+ to be applied between the terminals of the test coil no longer increases. Here, as can be seen from equation (3).

During resonance, a certain phase difference exists between the voltages on the output amplification section side and the output resonance section side. (In the case of Figure 2
90') Fig. 1 is a block diagram showing the configuration of a withstand voltage tester which is an embodiment of the present invention, Fig. 3 is a circuit diagram showing an example of a PLL circuit, and Fig. 4 is a circuit diagram showing an example of A (EC circuit). FIG.

In the figure, T is a resonant transformer, L is the inductance of the coil under test, and C is the resonant capacitance built into the withstand voltage tester. D has a phase ratio of 11 and a low-pass filter P2. PLL circuit consisting of voltage controlled oscillator P3 etc. (see Figure 3)
, E is the rectifier circuit P4, error term @ device P5, variable resistance element P
The AGC circuit (see Fig. 4) is composed of 6, etc.
A detailed explanation will be given below with reference to the drawings. Now, when the test coil for a withstand voltage test is connected to a withstand voltage tester, the voltage at point B on the output resonance part side, where the resonant capacitor C and the test coil are connected, is detected by a voltage divider circuit consisting of a voltage divider resistor, etc. At the same time, the signal is waveform-shaped by a comparator or the like and input to terminal 1 of the phase comparator PI constituting the I'LL circuit. On the other hand, the voltage at point A on the output amplifier side is waveform-shaped by a comparator or the like, inverted by a NOT circuit or the like, and is similarly input to the terminal 3 of the phase comparator PI. Therefore, the output from the phase comparator corresponding to the phase difference between the voltages at points A and B is input to the terminal 8 of the voltage controlled oscillator P3 via the low-pass filter P2. Since the phase difference between the voltages generated on the next side and the secondary side is added, the phase difference between points A and B is 180°.
The oscillation frequency of the voltage controlled oscillator P3 is controlled so that the resonant circuit can be automatically tuned.

The output from the automatically tuned voltage controlled oscillation @P3 is
Amplify W! It is amplified via F and drive stage G, and the resonant circuit enters a resonant state. Furthermore, in the embodiment, the voltage at point B on the output resonance part side is detected by the market voltage divider circuit, and the voltage at point B on the output resonance part side is detected by the rectifier circuit P4, the error amplifier P5, and the variable resistance element P6.
The AGC circuit port consists of! It is input to 51 of the I-flow circuit P4. The output from this rectifier path and the output voltage set in advance by the output voltage setting digital switch are inputted to the Gl and G2 terminals of the error amplifier P5 of the AGC circuit, respectively, and output the error signal. is input to the amplifier M5 via the variable resistance element P6. With this configuration, the output voltage is automatically adjusted to a voltage value determined according to the inductance of the coil. Therefore, by simply connecting the test coil to this tester and setting the output voltage value, the withstand voltage test is automatically performed.

<Effects> As explained above, according to the resonant voltage tester of the present invention, a resonant state can be obtained by automatic tuning using a one-phase control loop (PLL circuit). In addition, if the output voltage, which is determined in advance by the inductance of the coil, is set using a digital switch, the output voltage will be automatically adjusted to the set voltage value, making it possible to tune the resonant circuit, which was previously done manually. This eliminates the need for work and work for adjusting the output voltage. Furthermore, since coils with different inductances can be tested on the same line, not only is work efficiency improved, but individual differences in withstand voltage tests are eliminated, and test reliability is improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the withstand voltage tester according to the present invention, Fig. 2 is a circuit diagram for explaining a series resonant circuit used in a resonant type withstand voltage tester, and Fig. 3 is a circuit diagram used in the present invention. An example of a PLL circuit, FIG. 4 is an example of the same <AGC circuit,
FIG. 5 is a block diagram showing the configuration of a conventional voltage resistance tester. T: Resonant transformer, L: Inductance, C: Resonant capacitance, D: PLL circuit, Ej A G CID circuit, 1? :
Amplifier, G Nido 541 stage, PI: Phase comparator, P2: Low pass filter, P3: Voltage controlled oscillator, P4: Rectifier circuit, P5: Error amplifier, P6: Variable resistance element, M1 to H
5: Amplifier

Claims (1)

[Scope of Claims] 1. A resonant high-frequency withstand voltage tester used for an interlayer withstand voltage test of a high-frequency coil, consisting of an inductance of a test coil connected to the withstand voltage tester and a resonant capacitance built into the withstand voltage tester. A high frequency withstand voltage tester characterized in that it is configured to automatically tune the oscillation frequency during resonance of a resonant circuit using a phase control loop. 2. The high frequency withstand voltage tester according to claim 1, wherein the output voltage from the high frequency withstand voltage tester at the time of resonance is automatically adjusted to a preset voltage value.