JPH0843477A - Impulse generation circuit of coil withstand voltage tester and coil withstand voltage tester - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a low-cost coil withstand voltage tester with large dielectric strength between trigger transformers. A charging / discharging capacitor 17 that is charged by a high voltage through a rectifying diode 16 is provided, and a resonance capacitor 26 that is connected in parallel to a coil under test 28 to form a parallel resonance circuit is provided. A coil withstand voltage tester including field effect transistors 18 to 20 that form a discharge path of the charge and discharge capacitor 17 and are connected in series with each other, and a trigger pulse generator 24 that controls a conduction period of the field effect transistors 18 to 20. In the impulse generating circuit, the trigger pulse generator 24 has the trigger transformers 21 to 23 for each field effect transistor. The impulse generating circuit of the coil withstand voltage tester.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impulse generating circuit of a coil withstand voltage tester and a coil withstand voltage tester, and in particular, a plurality of high voltage switching elements connected in series are each provided with a trigger transformer. The present invention relates to an impulse generation circuit of a coil withstand voltage tester that triggers a high voltage switching element and a coil withstand voltage tester.

[0002]

2. Description of the Related Art A prior art example of an impulse generating circuit of a coil withstand voltage tester will be described with reference to FIG. Reference numeral 15 is a power transformer, which is supplied with power from a commercial power source or another power source to generate a high voltage. 16 is a rectifying diode,
Reference numeral 17 denotes a charge / discharge capacitor, and the rectifier diode 16 rectifies the high voltage generated by the power transformer 15 to charge the charge / discharge capacitor 17. 18 to 20
Is a field effect transistor, the number of which is determined according to the voltage generated by the power transformer 1. Reference numerals 21 to 23 are trigger transformers, and 24 is a trigger pulse generator. The trigger pulse generated by the trigger pulse generator 24 is transmitted through these trigger transformers to the field effect transistor 1.
It is supplied to the gate electrodes of 8 to 20 and simultaneously turns on these field effect transistors. The pulse generated by the trigger pulse generator 24 is synchronized with the AC voltage input to the power transformer 15, and is generated immediately after the charging / discharging of the charge / discharge capacitor 17 is completed. 25 is a reverse current blocking diode, 26 is a resonance capacitor, 27 is an input terminal, 28
Indicates a coil under test. For example, the impulse output voltage is 5
At kV, 10 field effect transistors are required.

Here, when the trigger pulse generated by the trigger pulse generator 24 is supplied to the gate electrodes of the field effect transistors 18 to 20 through the trigger transformer and these field effect transistors are simultaneously turned on,
The high voltage charged in the charge / discharge capacitor 17 is output to the input terminal 27 via the reverse current blocking diode 25 and applied to the coil under test 28. By the way, the coil under test 2
A resonance capacitor 26 is connected in parallel to 8 to form a resonance circuit. Therefore, the charging / discharging capacitor 1 is provided at both ends of the input terminal 27 for each AC cycle of the power supply.
The high voltage of 7 causes a damping vibration waveform based on the resonance circuit formed by the coil under test 28 and the resonance capacitor 26 to appear, and the coil under test 28 can be tested and inspected by observing it with an oscilloscope.

FIG. 4 shows a damping vibration waveform of the prior art. The horizontal axis represents time, and the vertical axis represents the voltage of damped oscillation that appears at both ends of the input terminal 27. Point A and point C are drive sections for driving the resonance circuit including the coil under test 28 and the resonance capacitor 26, and the rise time from point A to point B is extremely small.
At the same time, by controlling the pulse width of the trigger pulse generated by the trigger pulse generator 24, the drive section from point A to point C can be controlled to an optimum value.

Here, a coil withstand voltage tester for quantifying the characteristics of the damped vibration waveform and comparing it with a standard value to judge pass / fail of the coil will be described with reference to FIG. 1 is commercial power supply,
Reference numeral 2 is a high voltage impulse generating circuit, 3 is a resonance capacitor which constitutes a voltage divider, 4 is an output terminal, and 5 is a coil under test. The high-voltage impulse generation circuit 2 receives a commercial power supply from the commercial power supply 1, generates a high-voltage impulse, and supplies the high-voltage impulse to the coil under test 5 via the output terminal 4.

6 is a buffer amplifier, 7 is a waveform shaping circuit,
8, 10, 12 and 15 are peak hold circuits, 9,
Reference numerals 11 and 13 are analog gate circuits. The damped vibration caused by the resonance capacitor 3 and the coil under test 5 is divided by the resonance capacitor 3 which also constitutes a voltage divider, and input to the buffer amplifier 6. The damping vibration waveform whose impedance is lowered by the buffer amplifier 6 is
Then, the waveform shaping circuit 7, the peak hold circuit 8, and the analog gate circuits 9, 11, and 13 are input.

Reference numeral 14 is a high-pass filter, 16 is a cycle counter, 17 is a gate signal generation circuit, 18 is a T1 data output terminal, 19 is a V1 data output circuit, 20 is a V2 data output terminal, 21 is a V3 data output terminal, and 22 is a V4V5
This is a data output terminal. The waveform shaping circuit 7 carries out the waveform shaping shown in FIG. 6 and outputs the result to the gate signal generating circuit 1.
Send to 7. Gate signal generating circuit 17 generates timing signals G1, G2 and G3 and outputs them. The period counter 16 receives the timing signal G1, and the pulse signal of the timing signal G1, that is, T1 in FIG.
Is measured and is output to the T1 data output terminal 18.

The peak hold circuit 8 measures the maximum voltage of the attenuated signal waveform, that is, V1 in FIG.
Output to the data output circuit 19. Analog gate circuit 9
And the peak hold circuit 10 is the gate signal generation circuit 1
The V2 in FIG. 5 is peak-held by the timing signal G2 of 7 and is output to the V2 data output terminal 20. Similarly, the analog gate circuit 11 and the peak hold circuit 12 peak-hold V3 in FIG. 5 according to the timing signal G3 of the gate signal generation circuit 17 and output it to the V3 data output terminal 21.

The analog gate circuit 13 and the high-pass filter 14 have a pulse width of the timing signal G1, that is,
The voltage pulses V4 and V5 shown in FIG. 6 are formed separately from the corona pulse damped oscillation waveform within the time T1 in FIG. Then, the peak value of this voltage pulse is peak-held in the peak-hold circuit 15, and this is output to the V4V5 data output terminal 22.

The timing chart of the timing signals G1, G2 and G3 is as shown in FIG. Regarding the output form, the T1 data output terminal 18 is a digital parallel output because it is a counter output, and the other output terminals 19 to 22 are analog outputs.
The period T1 of the damping vibration of the resonance circuit, the driving pulse voltage V1 for driving the parallel resonance circuit, and the first positive peak voltage V of the damping vibration of the resonance circuit, which are the measurement results obtained as described above.
2, the second positive peak voltage V3 of the damping vibration of the resonance circuit,
Then, the coil pass / fail judgment evaluation is carried out by appropriately calculating the peak voltage V4V5 of the corona pulse (for details of the above, refer to Japanese Patent Application No. 5-37919).

[0011]

By the way, in the prior art example of the impulse generating circuit of the coil withstand voltage tester shown in FIG. 3, one field effect transistor corresponds to one trigger transformer, and a large number of independent trigger transformers are provided. In addition to this, there is another example as shown in FIG. That is, the impulse generation circuit of the coil withstand voltage tester shown in FIG. 9 is an example in which a large number of secondary coils are wound around one trigger transformer to simultaneously trigger all field effect transistors.

The above two types of circuits can be considered to simultaneously trigger the field effect transistors connected in series in the impulse generation circuit of the coil withstand voltage tester. There is no direct difference in the electrical performance characteristics between the two circuits. However, in the high-voltage switch circuit, which is the impulse generation circuit of the coil withstand voltage tester, the shape of circuit components, the way of mounting the circuit, and other conditions affect the operational stability of the high-voltage switch circuit over a long period of time. From the point of giving, along with the direct superiority of the electrical performance characteristics of the circuit,
It is important to take these into consideration. From this point of view, in the impulse generation circuit shown in FIG. 3, a small trigger transformer can be separately arranged for each of a plurality of field effect transistors at a close distance, and therefore, a uniform trigger waveform is obtained. It is possible to improve the impulse generation circuit shown in FIG. 9 in that it is possible to obtain the above, and to simply configure the arrangement of components in consideration of the withstand voltage.

The present invention provides an impulse generation circuit of a coil withstand voltage tester having a large dielectric strength between trigger transformers and improved electrical performance characteristics. A coil withstand voltage test for determining pass / fail of the coil using the impulse generation circuit 2 of the coil withstand voltage tester is described with reference to FIG. Here, the high-voltage voltage divider 3 is always connected to the output of the impulse generation circuit 2, and the damped oscillation waveform generated at the output terminal 4 is taken into the buffer amplifier 6. Since the coil to be tested 5 which is a two-terminal circuit vibrates while the impulse generating circuit is connected, the impulse generating circuit becomes a parallel load for the coil to be tested 5 during the damping vibration. Is not preferable because it has the effect of reducing

The present invention provides a coil withstand voltage tester suitable for making a pass / fail judgment of a coil by using an impulse generating circuit of the coil withstand voltage tester.

[0015]

A charging / discharging capacitor 17 charged by a high voltage through a rectifying diode 16 is provided, and a resonance capacitor 26 which is connected in parallel to a coil under test 28 to form a parallel resonance circuit is provided. The discharge path of the charging / discharging capacitor 17 for the parallel resonant circuit is provided with field effect transistors 18 to 20 connected in series, and the trigger pulse generator 24 is provided to control the conduction period of the field effect transistors 18 to 20. In the impulse generating circuit of the coil withstand voltage tester, the trigger pulse generator 24 has the trigger transformers 21 to 23 for the field effect transistors, respectively.

The core of the trigger transformer constitutes the impulse generation circuit of the coil withstand voltage tester which is formed by forming an opening in the core material. Further, the trigger transformer constitutes the impulse generation circuit of the coil withstand voltage tester including the common primary coil. Further, the primary coil of the coil under test 28 composed of two or more coils is connected to the output terminal 4 of the impulse generating circuit of the coil withstand voltage tester, and the secondary coil of the coil under test 28 is connected to the voltage divider 3. A coil withstand voltage tester that connects and processes the resonance attenuation output of the voltage divider 3 is configured.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, members common to those in FIG. 3 are designated by common reference numerals. The present invention corresponds to an impulse generator circuit of the coil withstand voltage tester shown in FIG. 3, in particular, an improved trigger transformer. FIG. 1 shows a field effect transistor 18 to 20 controlled to be turned on and off, which is a main part of the constitution of the present invention.
It is a figure which shows the trigger transformers 21-23 which carry out ON / OFF control of these field effect transistors, and the trigger pulse generator 24 which excites these trigger transformers.

The cores of the trigger transformers 21 to 23 are, for example, ring cores having holes formed in the core material. The ring core has a feature that it can be made small and can transmit a large trigger power. Moreover, as shown in the drawing, for example, two lead wires corresponding to the primary coil pass through the opening at the center of the ring core. As the two conductors penetrating this opening, thick conductors with high voltage insulation can be used.

As long as it is an impulse generating circuit of a coil withstand voltage tester, it must be constructed so that it can withstand a high voltage as a whole. In this case, for the power transformer 15, the rectifying diode 16, the charging / discharging capacitor 17, and the resonance capacitor 26, in order to have high withstand voltage, it is sufficient to select a high withstand voltage. Then, the field-effect transistors are naturally connected to the printed circuit board in series so as to be mounted, whereby a structure capable of withstanding a high voltage is realized. However, in order to make the trigger transformer have a high withstand voltage, it is necessary to configure the primary coil with a high withstand voltage. As described above, this can be easily realized by forming the core by the ring core and penetrating the central hole through the thick and high-voltage insulated conducting wire.

Next, FIG. 2 is a diagram for explaining a coil withstand voltage test for determining pass / fail of a coil using an impulse generation circuit of a coil withstand voltage tester. In FIG. 2, a coil component having two or more coils such as a transformer is connected to the voltage divider 3 when the coil withstand voltage test is performed, with the side connected to the output terminal 4 of the impulse generation circuit 2 as the primary coil. The side to be operated is the secondary coil. In most cases, the withstand voltage test of the transformer tests the interlayer withstand voltage on the side with a large number of turns, so it is rational to make such a connection. Then, the transformer 5 to be tested is connected to the impulse generating circuit 2 with the side having the smaller number of windings as the primary coil and the side having the larger number of windings as the secondary coil.
Therefore, the degree to which the impulse generation circuit 2 becomes a load can be reduced. Therefore, the load on the secondary side of the transformer 5 is only the voltage divider 3 and can be a high-impedance small-capacity load. As a result, the secondary coil of the transformer 5 becomes almost unloaded, and is damped and oscillated by the natural frequency of the secondary coil. Further, this natural vibration has a high Q vibration and therefore exists inside the secondary coil. The damped vibration waveform is likely to change due to a defect, and a suitable coil withstand voltage test can be performed.

[0021]

As described above, the impulse generation circuit of the coil withstand voltage tester of the type in which one field effect transistor corresponds to one trigger transformer and a large number of independent trigger transformers are provided. A small trigger transformer can be arranged in the closest position for each one of the field effect transistors, and a uniform trigger waveform can be obtained, and a component arrangement in consideration of withstand voltage can be simply configured.

In addition, the core of the trigger transformer is made of, for example, a ring core having holes formed in the core material, which is small in size and can transmit a large trigger power. This leads to downsizing of the entire pressure resistance tester. Further, for example, two conducting wires corresponding to the primary coil pass through the opening at the center of the ring core, and as the conducting wire, a thick and high-voltage insulated one can be used. This makes it possible to configure a low-cost coil withstand voltage tester having a large dielectric strength between a plurality of trigger transformers.

Further, by making the side connected to the output terminal of the impulse generation circuit a primary coil and the side connected to the voltage divider a secondary coil, the interlayer withstand voltage test of the transformer withstand voltage test is rationalized. It can be carried out. And
By connecting the transformer to the impulse generation circuit with the side with the smaller number of windings as the primary coil and the side with the larger number of windings as the secondary coil, a high Q characteristic vibration can be generated, and a suitable coil withstand voltage test is performed. You can

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example.

FIG. 2 is a diagram illustrating a coil withstand voltage test.

FIG. 3 is a diagram illustrating a preceding example.

FIG. 4 is a diagram showing a damping vibration waveform.

FIG. 5 is a diagram illustrating a method of determining pass / fail.

FIG. 6 is a diagram showing a corona pulse.

FIG. 7 is a diagram illustrating a coil withstand voltage test.

FIG. 8 is a timing chart of timing signals.

FIG. 9 is a diagram illustrating another prior art example.

[Explanation of symbols]

 16 Rectifier diode 17 Charging / discharging capacitor 18 to 20 Field effect transistor 21 to 23 Trigger transformer 24 Trigger pulse generator 26 Resonance capacitor 28 Coil under test

Claims (4)

[Claims] 1. A charging / discharging capacitor that is charged by a high voltage through a rectifying diode, and a resonance capacitor that is connected in parallel to a coil under test to form a parallel resonant circuit. In the impulse generation circuit of the coil withstand voltage tester, which is provided with field effect transistors which form a discharge path of the capacitor and which are connected in series with each other and which controls the conduction period of the field effect transistor, the trigger pulse generator is An impulse generation circuit for a coil withstand voltage tester, characterized in that it has a trigger transformer for each field effect transistor. 2. The impulse generation circuit for a coil withstand voltage tester according to claim 1, wherein the core of the trigger transformer is formed by forming an opening in a core material. Generator circuit. 3. The impulse generation circuit for a coil withstand voltage tester according to claim 2, wherein the trigger transformer is composed of a common primary coil. 4. One of the coils to be tested, which is composed of two or more coils, with respect to the output terminal of the impulse generation circuit of the coil withstand voltage tester according to any one of claims 1 to 3.
A coil withstand voltage tester, characterized in that a secondary coil is connected, the secondary coil of the coil under test is connected to a voltage divider, and the resonance attenuation output of the voltage divider is signal-processed.