JP2003021661A - Withstand voltage testing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize an output voltage by correcting a voltage drop occurring in a winding resistance portion of a transformer. SOLUTION: A correction voltage created from the value of a current flowing in a resistance component of a specimen is added to a reference voltage for setting the output voltage, to thereby correct an output voltage drop occurring in a copper wire resistance of secondary side winding of the transformer. In order to prevent over-correction caused by a current flowing in a capacity component of the specimen, a correction voltage from which the current flowing in the capacity component is removed is added to the reference voltage for setting the output voltage, to thereby correct the output voltage drop occurring in the copper wire resistance of the secondary side winding of the transformer. In addition, since the winding resistance value varies with temperature, a temperature change value of the winding resistance is detected, and a temperature correction voltage acquired by performing voltage conversion of the detected value, the correction voltage generated from the current value flowing in the specimen and the reference voltage for setting the output voltage are added together, to thereby correct the output voltage drop occurring in the copper wire resistance of the secondary side winding of the transformer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test apparatus for testing withstand voltage characteristics, and more particularly to stability performance of high voltage applied to a sample.

[0002]

2. Description of the Related Art Withstand voltage testers are compliant with various safety standards (JI
S standard, UL standard, CSA standard, etc.)
It is a test device that determines the withstand voltage performance of the sample by applying a high AC voltage required for those standards to the sample for a certain period of time. It is done by measuring. Then, in order to obtain a high AC voltage, a method of boosting a commercial power source of 50 Hz or 60 Hz is generally used, or a sine wave is generated in the oscillating unit 1 to amplify the power, as shown in FIGS. 9 and 10. The method has been adopted.

In the conventional feedback system shown in FIG. 9, the sine wave signal generated in the oscillating unit 1 is power-amplified by an amplifier Pr and a power amplifier Pa to excite the primary winding of a transformer T. 5 kV (rms) on the secondary winding of the transformer
The output voltage Vo boosted (hereinafter, rms is omitted) is obtained, the voltage is applied to the DUT 3, the current Io flowing through the current detector 40 is detected, and the quality of the DUT is determined. Is configured.

On the other hand, the conventional feedback system shown in FIG.
The sine wave signal generated by the oscillating unit 1 is power-amplified by the power amplifier Pa via the multiplier 7 to excite the primary side winding of the transformer T and, for example, 5 kV to the secondary side winding of the transformer. It is configured to obtain the output voltage Vo boosted in step 1, apply the voltage to the DUT 3, detect the current Io flowing through the current detector 40, and determine the quality of the DUT.

However, in any of the conventional techniques, when the feedback amount is extremely insufficient, the resistance component Rt of the DUT 3 and the winding resistance 2 of the transformer T are connected in series. The resistance 2 was set to 5 kΩ and the resistance to the sample 3 was reduced to 0.
When a large current of 1 A is applied, a voltage drop of 500 V occurs in the resistor 2, and it should be set to be applied to the DUT 5 k.
The situation occurs that V is actually applied at 4.5 kV. This error corresponds to 10%, and the operator must reset the applied voltage again.

As a countermeasure against such a voltage drop, in the prior art shown in FIG. 9, the output of the secondary winding of the transformer T is changed to a resistor Rd.
The output voltage stability is improved by dividing the voltage by R and Ra and returning to the negative terminal of the amplifier Pr. The resistor Ro and the capacitor Co are for preventing abnormal oscillation due to phase rotation in the high frequency range.

On the other hand, in the prior art shown in FIG. 10, after detecting an output voltage and appropriately attenuating it, an AC / DC converter converts an AC voltage into a DC voltage and then a comparator (COMP) compares it with a reference voltage Vref. Error voltage is obtained and negative feedback is given to the multiplier 7 to stabilize the output voltage, and the resistor R shown in FIG.
The integrating circuit composed of d and the capacitor Cd is for preventing abnormal oscillation in the low frequency range.

[0008]

However, there are the following problems in the prior art based on the above two feedback systems.

That is, in the system shown in FIG. 9, the output of the secondary winding of the transformer is divided by resistors Rd and Ra and negatively fed back to the negative terminal of the amplifier Pr to improve the stability of the output voltage, while the feedback amount is increased. Since the abnormal circuit due to the phase rotation of the amplifier Pr, the power amplifier Pa, and the transformer T section, which is caused by the increase of the power consumption, is solved by the prevention circuit composed of Ro and Co, the optimization of the feedback amount by this method is performed. There is no choice but to strike a balance between stability and prevention of abnormal oscillation. Naturally, it is difficult to always prevent abnormal oscillation under all test conditions, so it is extremely difficult to secure a permissible error necessary for practical use.

In the feedback method shown in FIG. 10, the time constant and the resistance R inside the AC / DC converter forming the feedback loop are used.
The response time of the entire circuit becomes slow due to the time constant of the integrating circuit composed of d and the capacitor Cd, and the surge voltage (overshoot or undershoot) superimposed on the output voltage Vo
As a result of being transiently added to the sample, the sample or the element forming the sample may be destroyed.

Further, in the above-mentioned two prior arts, when a sufficient feedback amount cannot be secured due to measures for preventing abnormal oscillation, the transformer T
It is impossible to solve the temperature characteristic problem peculiar to the metal resistance that the output voltage drops due to the increase of the winding resistance value 2 due to the heat generation of.

The present invention has been made to solve the drawbacks and problems of these feedback systems.

[0013]

In order to solve the above-mentioned problems, the invention of claim 1 excites a transformer with an output signal of an AC signal source to obtain a high AC output voltage and supplies the output voltage. In a withstand voltage test device for testing withstand voltage performance by a current applied to a sample and flowing through a current detector, a direct current converting means for converting the detected value detected by the current detector into direct current is provided,
A voltage setting means and a first adding means, and the direct current value from the direct current converting means and the output voltage from the voltage setting means are added by the first adding means, and the added value and the alternating current signal source It is characterized by comprising a multiplying means for multiplying the output signal of 1 to correct the output voltage.

According to a second aspect of the present invention, there is provided rectifying means for rectifying a detected value from the current detector by a signal in phase with the output signal of the AC signal source, and the output from the rectifying means is provided. It is characterized in that the direct current converting means converts the direct current into a direct current value, and the direct current value and the output voltage from the voltage setting means are added by the first adding means.

According to a third aspect of the present invention, in addition to the first and second aspects, the temperature detecting means and the temperature / voltage converting means are provided.
Of the temperature detecting means, the detected value from the temperature detecting means is converted into a voltage by the temperature / voltage converting means, and the output of the temperature / voltage converting means and the DC value from the DC converting means are added to the second adding means. Means for adding and the added value is input to the first adding means.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 7, the gist of the present invention is to generate a correction voltage .DELTA.Vc of (B) from an output current Io to correct a regulation characteristic (A) and thereby output voltage characteristic (C). And to stabilize the output voltage Vo. FIG. 7 shows the principle of this correction.
The principle will be described below. As shown in (A) of FIG. 7, the regulation characteristic shows a downward-sloping slope characteristic proportional to the amount of current Io flowing through the sample. Therefore, if the voltage characteristic having such a slope is set to -ΔVc, then -ΔVc = voltage drop of the winding resistance 2. Therefore, in order to obtain a correction characteristic such as the output voltage characteristic (C), the correction voltage ΔVc having a slope characteristic opposite to the voltage drop of the winding resistor 2 from the current Io, that is, (B).
Should be generated and added to the regulation characteristic (A).

According to the first aspect of the invention, ΔVc is generated from the current Io flowing through the sample 3 formed of only the resistance component to correct the voltage drop due to the winding resistance 2 and stabilize the output voltage Vo. The operation will be described below based on an embodiment of claim 1 shown in FIG.

In FIG. 1, a signal generator 10 generates a sine wave signal of 50 or 60 Hz. The sine wave signal and the output from the adder 11 are input to a multiplier 20, and the multiplication output is The power is amplified by the power amplifier 30, and the primary winding of the transformer T1 is excited to obtain the output voltage Vo. However, when the DUT 3 is not connected between the output terminals Ta and Tb, the output voltage Vo is set only by the output setting voltage Vi from the voltage setting device 6 input to the adder 11. In this way, the output voltage Vo can be changed by changing the voltage Vi.

Next, the DUT 3 is connected between the output terminals Ta and Tb, and when the output voltage Vo is applied, a current Io is generated, and the regulation characteristic becomes as shown in FIG. . The voltage of this current Io is detected by the current detector 40, the amplification degree of the amplifier 14 is adjusted by the variable resistor 4, and
Of the slope characteristic of (A) is obtained, and the slope of the integrator 13 is obtained.
After full-wave rectification by an absolute value conversion circuit and a low-pass filter, a correction voltage ΔVc approximated to DC, that is, (B) in FIG. 7 is generated. The current detector 40 may be a current transformer or a resistor, and the absolute value conversion circuit may be a full-wave rectification type or a half-wave rectification type.

The amplifier 14 is an amplifier which is appropriately provided when the gain for obtaining the correction voltage ΔVc is insufficient.
It may be provided not only immediately after the current detector 40 but also before and after the low-pass filter forming the integrator 13, for example. Also,
The variable resistor 4 provided between the input and output of the amplifier 14 is an adjuster for changing the gain of the amplifier 14 so as to have the inclination as shown in (B) as described above. Since it only needs to be done once, a fixed resistor can be used when the variation in the winding resistance value 2 is almost constant.
It is not necessary to provide it between the input and output of the special amplifier 14, and like the amplifier 14, the gain may be adjusted by providing it at the front and rear stages of the low-pass filter that constitutes the integrator 13.

The correction voltage ΔVc thus generated and the voltage Vi from the voltage setting unit 6 are input to the adder 11 to obtain an added value (ΔVc + Vi). Then, by multiplying the added value and the output from the signal generation source 10 by the multiplier 20, the output voltage Vo in which the voltage drop (−ΔVc) in the winding resistance 2 is corrected can be obtained. As described above, the output voltage Vo can be corrected.

FIG. 4 shows an embodiment of an absolute value conversion circuit which constitutes the integrator 13, and its operation will be described below. First, when an AC voltage waveform is input to the positive terminal of the operational amplifier Qv1, the negative side of the output voltage waveform of the operational amplifier Qv1 is input to the negative terminal of the operational amplifier Qv1 via the diode Dv1 and the resistor Rv2. It is amplified by the ratio of. Then the amplified output is a resistor R
is input to the negative terminal of the operational amplifier Qv2 via v3, It is amplified by the ratio of. In this way, a positive half-cycle output signal whose polarity is inverted is obtained from the output terminal of Qv2. Also, the diode Dv2 connected to the output of Qv1
Input the positive output waveform of Qv1 to the negative terminal of Qv1, while inputting the positive output waveform of Qv1 to the positive terminal of Qv2, the output waveform whose polarity is not inverted is Q.
It is obtained from the output of v2 and operates so as to finally obtain a positive rectified waveform. FIG. 12 shows an example of a low-pass filter that constitutes the integrator 13, but the description of its operation is omitted.

According to the second aspect of the invention, in the sample 3 formed of the resistance component Rt and the capacitance component Ct, the correction voltage ΔVc is generated by removing the current flowing in the capacitance component Ct from the current Io flowing in the sample. However, the voltage drop due to the winding resistance 2 is corrected to stabilize the output voltage Vo. That is,
As described above, when a voltage of 5 kV is applied to the sample 3 having only the resistance component and the current Io of 0.1 A flows, the winding resistance 2
Is 5 kΩ, the voltage drop across the resistor 2 is 500
It becomes V. However, when the sample 3 is formed of the resistance component Rt and the capacitance component Ct, as is well known, the current flowing through Rr (IRr) = the current flowing through Rt (IR
t), the current with respect to the capacitance component has a lead phase of 90 °, and the voltage has a lag phase of 90 °. Therefore, for convenience, Rr is shown in FIGS. 8A and 8B. The current IRr and the current ICt are The current Io is the current detector Ri as the vector composite value
Will be detected at. When the correction voltage ΔVc is generated from the vector-combined current Io, the overcorrected correction voltage ΔVc is generated as the current ICt increases. Therefore, the current ICt is removed and only the resistance component flows. The output voltage Vo must be corrected by generating the correction voltage (B) only from the current IRr.

FIG. 2 shows an embodiment of claim 2, and the parts different from claim 1 will be described below with reference to FIG. The combined current Io whose voltage is detected by the current detector 40 is amplified by the amplifier 14 and input to the phase detection circuit 15. However, this phase detection circuit 15 also has the above-mentioned absolute value conversion function. 6A shows an embodiment of the phase detection circuit 15, and FIG.
Shows the detected current waveform of 0 ° phase and 90 ° phase and the current waveform in the phase detection circuit, and also shows the timing relationship.

The operation of the phase detection circuit will be described below with reference to FIGS. 6 (A) and 6 (B). In FIG. 6 (B),
1A indicates a detection signal waveform, and 2A indicates a switch Sp1.
The control signal waveform for driving (2) is shown, and 3A shows the output signal waveform of the operational amplifier Qp1. First, when the combined current waveform detected by the current detector 40 is input to the plus terminal of the operational amplifier Qp1 via Rp3 and Rp4, 1A
As is clear from the timing relationships of the signal waveforms from 3A to 3A, when the switch Sp1 (2) is off, Qp1 operates as a follower amplifier with an amplification factor of 1, and when the switch is on, It operates as an inverting amplifier. However, the amplification degree does not have to be 1. That is, the phase detection circuit is the L3 of the transformer T1.
When the switch Sp1 is turned off / on with a signal having the same phase as the signal from, the composite waveform shown in 3A of FIG. 6B is output. The switch Sp1 is on / off controlled by a phase detector 16 described later.

In FIG. 2, the waveform indicated by 3A in FIG. 6 (B) is converted into a direct current by the integrator 13 (comprising a low-pass filter) and generated as a correction signal ΔVc of only the resistance component, and this ΔVc is added. It is added to the voltage Vi from the voltage setting device 6 in the device 11 to obtain the added value (ΔVc + Vi). Then, the multiplier 20 multiplies the added value by the output from the signal generator 10 to obtain the output voltage Vo in which the voltage drop (−ΔVc) in the winding resistance 2 is corrected. As described above, the output voltage Vo can be corrected even for the sample 3 formed of only the capacitive component.

FIG. 5 shows the switch Sp of the phase detection circuit 15.
An example of the phase detector 16 for generating a signal for driving 1 is shown and the timing relationship is shown. And
In the present embodiment, as shown in FIG. 2, the signal from the L3 winding of the transformer T1 is used for input to the phase detector 16, but the signal input to the phase detector 16 is the signal generator 10.
It is not necessary to use a special L3 winding because it only needs to be in phase with the signal from the.

According to the first and second aspects of the invention, the output current is changed from zero to the maximum current of 1 by applying 5 kV.
The voltage fluctuation rate when changed to 00 mA is within ± 0.5%.

FIG. 3 shows the invention of claim 3 or the transformer T1.
This is an embodiment for correcting the fact that the winding resistance value 2 increases and the output voltage Vo drops due to the heat generation of 1. In the following, the invention of claim 3 and constituent parts different from FIG. 1 will be described.
As is well known, since the winding resistance value 2 has a positive temperature coefficient, the resistance value may increase due to heat generation of the transformer T1 and the output voltage Vo may drop. The regulation characteristic due to the heat generation of the transformer T1 is
Assuming −ΔVt, ΔV is the same as in claim 1 and claim 2.
The output voltage Vo may be corrected by generating a correction voltage of t. According to the invention of claim 3, the temperature of the winding of the secondary winding of the transformer T1 is obtained from a current flowing through a temperature detecting element such as a thermistor to obtain a temperature correction voltage ΔVt, and this voltage ΔVt and the correction voltage ΔVc are added, Further, the output voltage is corrected by adding it to the voltage Vi.

In FIG. 3, the temperature detecting element 24 is a thermistor resistor or the like for detecting the temperature of the secondary winding of the transformer T1 and is fixed near the winding. Then, the resistance value change of the temperature detecting element 24 is detected by the temperature / voltage converter 23.
The voltage is converted to obtain the temperature correction voltage ΔVt. The adjustment circuit 22 adjusts the slope of the temperature correction voltage ΔVt and voltage amplification.
Will be done at. FIG. 11 shows an embodiment of the adjusting circuit 22, and the explanation of its operation is omitted.

In FIG. 3, the correction voltage ΔVc and the temperature correction voltage ΔVt are input to the adder 21, and the output of the adder 21 is further input to the adder 11 to obtain the added value (ΔVc + ΔV).
t + Vi) is obtained, the transformer T1 is excited by the signal from the signal generator 10 and the added value via the multiplier 20 and the amplifier 30, and the voltage drop due to the temperature change of the transformer T1 is corrected. As described above, the drop of the output voltage Vo due to the heat generation of the transformer T1 can be corrected.

【The invention's effect】

As described above, according to the present invention, the following effects can be obtained. 1) The voltage drop caused by the winding resistance of the secondary winding of the transformer T1 is detected as the current flowing through the DUT, and a correction voltage is generated according to the magnitude of the current value to reduce the output voltage drop. It is possible to realize a withstand voltage test device for correction. 2) The output voltage can be corrected regardless of the resistance component or capacitance component of the sample. 3) Even if the resistance value of the copper wire of the secondary winding of the transformer increases due to the temperature rise, it is possible to realize a stable withstand voltage test device with little output temperature dependency. 4) It is possible to avoid the problem of unstable operation due to abnormal oscillation due to the feedback method.

[Brief description of drawings]

FIG. 1 is an embodiment of the invention of claim 1;

FIG. 2 is an embodiment of the invention of claim 2;

FIG. 3 is an embodiment of the invention of claim 3;

FIG. 4 shows an embodiment of an absolute value conversion circuit.

FIG. 5: One embodiment of phase detector

FIG. 6A shows an example of a phase detection circuit.

FIG. 6B is a timing relationship diagram of detected current waveforms of 0 ° phase and 90 ° phase and current waveforms in the phase detection circuit.

[Fig. 7] Relationship between regulation characteristics and correction

FIG. 8 is an output equivalent circuit and a synthetic current Io.

FIG. 9 Prior Art 1

FIG. 10 Related Art 2

FIG. 11 is an example of a temperature detection circuit.

FIG. 12 is an example of a low-pass filter.

[Explanation of symbols]

1: Oscillator 2: Winding resistance 3: Sample 4: Variable resistor 6: Voltage setting device 7: multiplier shown in FIG. 10: Signal generator 11: first adder 13: integrator 14: Amplifier 15: Phase detection circuit 16: Phase detector 20: Multiplier 21: Second adder 22: Adjustment circuit 23: Temperature / voltage converter 24: Temperature detecting element 30: Power amplifier 40: Current detector 100: output section Vi: Output setting voltage Vo: Output voltage Io: Output current Rr: Copper wire resistance Rf: Variable feedback resistor Rg: resistor Rs: Thermistor resistor Rt: Resistance component of DUT 3 Ct: Volume component of DUT 3 T, T1: Transformer Ta, Tb: Output terminal

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[Procedure amendment]

[Submission date] September 20, 2001 (2001.9.2)
0)

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the invention of claim 1 ;

FIG. 2 is a diagram showing an embodiment of the invention of claim 2 ;

FIG. 3 is a diagram showing an embodiment of the invention of claim 3 ;

FIG. 4 is a diagram showing an embodiment of an absolute value conversion circuit .

FIG. 5 is a diagram showing an embodiment of a phase detector .

6 (A) FIG der showing an embodiment of a phase detector circuit
It (B) shows the detected current waveform of 0 ° phase and 90 ° phase and the current waveform in the phase detection circuit and the timing relationship .
It is a figure.

FIG. 7 is a diagram showing a relationship between regulation characteristics and correction .
Is.

FIG. 8 is a diagram showing an output equivalent circuit and a combined current Io .
It

FIG. 9 is a diagram showing Prior Art 1 .

FIG. 10 is a diagram showing Prior Art 2 .

FIG. 11 is a diagram showing an embodiment of a temperature detection circuit .

FIG. 12 is a diagram showing an example of a low-pass filter .
It

[Explanation of symbols] 1: Oscillator 2: Winding resistance 3: Sample 4: Variable resistor 6: Voltage setting device 7: multiplier shown in FIG. 10: Signal generator 11: first adder 13: integrator 14: Amplifier 15: Phase detection circuit 16: Phase detector 20: Multiplier 21: Second adder 22: Adjustment circuit 23: Temperature / voltage converter 24: Temperature detecting element 30: Power amplifier 40: Current detector 100: output section Vi: Output setting voltage Vo: Output voltage Io: Output current Rr: Copper wire resistance Rf: Variable feedback resistor Rg: resistor Rs: Thermistor resistor Rt: Resistance component of DUT 3 Ct: Volume component of DUT 3 T, T1: Transformer Ta, Tb: Output terminal

Claims (3)

[Claims] 1. A high output voltage of an alternating current is obtained by exciting a transformer with an output signal of an alternating current signal source, the output voltage is applied to a sample, and a withstand voltage performance is tested by a current flowing through a current detector. In the withstanding voltage test apparatus, a direct current converting means for converting the detected value detected by the current detector into a direct current is provided, a voltage setting means and a first adding means are provided, and the direct current value from the direct current converting means and the voltage A withstand voltage, characterized in that the output voltage from the setting means is added by the first adding means, and a multiplying means for correcting the output voltage by multiplying the added value by the output signal from the AC signal source is provided. Test equipment 2. The rectifying means for rectifying a detection value from the current detector by a signal in phase with the output signal of the alternating current signal source, according to claim 1, wherein the output from the rectifying means is converted into the direct current. Means for converting the direct current value and the output voltage from the voltage setting means to the first
Withstanding voltage test device characterized by adding by means of adding means 3. The method according to claim 1, further comprising: a temperature detecting unit and a temperature / voltage converting unit, a second adding unit, and a detection value from the temperature detecting unit to the temperature / voltage converting unit. Voltage conversion is performed, the output of the temperature / voltage conversion means and the DC value from the DC conversion means are added by the second addition means, and the added value is input to the first addition means. Withstanding voltage test equipment