JPS6312263B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a capacitive element loss measuring device.

Conventionally, an apparatus for measuring loss of a capacitive element has been proposed with the configuration described below with reference to FIG.

That is, e ₀ = E ₀ sinωt …(1) (where E ₀ is the amplitude, ω is the angular frequency,
It has an AC constant voltage source 1 that provides an AC constant current e ₀ (t is time), and a capacitive element 2 to be measured represented by a series equivalent circuit of a capacitance C _S and a resistance R _{S. 0} = I ₀ sinωt …(1)′ A constant current i ₀ (where I ₀ is the amplitude) flows,
At capacitive element 2 to be measured, e ₁ = i ₀ Z = I ₀ R ₀ sinωt + I ₀ /ωC _S sin (ωt-π/2) = I ₀ (R _S sinωt-1/ωC _S cosωt) ...(2) Through the constant current resistor R ₀ so as to obtain an AC voltage e ₁ which is the sum of the AC voltage inversely proportional to the capacitance C _S of the capacitive element 2 to be measured and the AC voltage proportional to the resistance R _S . It is connected.

In addition, the input side of the phase shift circuit ₅ is connected to both ends of the constant current resistor R 0 , and the AC constant voltage e ₀ obtained from the AC constant voltage source 1 is obtained at both ends of the constant current resistor R ₀ . Based on the drop voltage e ₀ ′ expressed as e ₀ ′=−i ₀ R ₀ =−I ₀ R ₀ sinωt …(1)″, from the output side of the phase shift circuit 5, e ₃ = e ₀ ′ωC ₁ R ₁ = −I ₀ R ₀ ωC ₁ R ₁ sin(ωt+π/2)…(3
), the AC voltage e ₃ having a phase difference of 90° with respect to the falling AC voltage e ₀ ' is obtained. In this case, the phase shift circuit 5 includes an operational amplifier 6 having an input terminal a, an input terminal b connected to ground and having the opposite polarity to the input terminal a, and an output terminal c having the same polarity as the input terminal a. , one end is connected to the input terminal a of the operational amplifier 6, and the other end is connected to the ground side of the constant current resistor _R0 via the polarity inversion circuit IN.
C ₁ and a resistor R ₁ connected between the output terminal c and the input terminal a of the operational amplifier 6.

The alternating current voltage _e1 obtained from both ends of the capacitive element 2 to be measured is supplied to one input terminal of a multiplier circuit 8 via an amplifier 7 as necessary, and the other input terminal of the multiplier circuit 8 is supplied to a phase shift circuit. The alternating current voltage e ₃ obtained from 5 is supplied through the amplifier 9 as necessary, and therefore, based on the alternating current voltages e ₁ and e ₃ from the multiplier circuit 8, E ₁ =K ₁ K ₃ I ₀ ² R ₀ C ₁ R ₁ /2C _S (4) A DC voltage E ₁ that is inversely proportional to the capacitance C _S of the capacitive element 2 to be measured is obtained. In this case, the multiplier circuit 8 is e ₄ =K ₁ e ₁・K ₃ e ₃ =K ₁ I ₀ (R _S sinωt−1/ωC _S cosωt)×{−K ₃ I ₀ R ₀ ω
C ₁ R ₁ sin(ωt+π/2)} =−K ₁ K ₃ I ₀ ² R _S R ₀ ωC ₁ R ₁ sin2ωt/2+K ₁ K ₃ I ₀ ² R ₀ C ₁ R ₁
(1+cos2ωt)/2C _S =K ₁ K ₃ I ₀ ² R ₀ C ₁ R ₁ /2C _S −K ₁ K ₃ I ₀ ² R ₀ ωC ₁ R ₁ /2 (R _S sin
2ωt−1/ωC _S cos2ωt)…(5) (where K ₁ and K ₃ are constants), AC voltage
Multiplier circuit main body 10 configured to obtain output e ₄ of the product of the voltage based on e ₁ and the voltage based on AC voltage e ₃
and a low frequency converter 11 configured to obtain a DC voltage E ₁ expressed by equation (4) based on the output e ₄ connected to its output side.

Further, the AC voltage _e1 obtained from both ends of the capacitive element 2 to be measured is supplied to one input terminal of another multiplier circuit 12 through the above-mentioned amplifier 7 as necessary, and a constant voltage e1 is supplied to the other input terminal of the multiplier circuit 12. Current resistance
The dropped AC voltage e ₀ ' obtained from both ends of R ₀ is supplied through an amplifier 13 with polarity reversal as required, and the AC voltages e ₀ ' and e ₁ are supplied from the multiplier circuit 12.
Based on the equation, E ₂ = K ₀ K ₁ I ₀ ² R _S R ₀ /2 (6) It is designed to obtain a DC voltage E ₂ proportional to the resistance R _S of the capacitive element 2 under test. .
In this case, the multiplication circuit 12 is e ₅ =K ₀ e ₀ ′・K ₁ e ₁ =K ₀ I ₀ R ₀ sinωt・K ₁ I ₀ (R _S sinωt−1
/ωC _S cosωt) =K ₀ K ₁ I ₀ ² R _S R ₀ (1-cos2ωt)/2-K ₀ K ₁ I ₀ ² R ₀ sin2
ωt/2ωC _S =K ₀ K ₁ I ₀ ² R _S R ₀ /2−K ₀ K ₁ I ₀ ² R ₀ /2 (R _S cos2ωt+1
/ωC _S sin2ωt)…(7) (where K ₀ and K ₁ are constants), AC voltage
Multiplier circuit main body 1 configured to obtain an output e ₅ which is the product of the output based on e ₀ ′ and the output based on the AC voltage e ₁
4, and a low frequency filter 15 connected to the output side and configured to obtain a DC voltage _E2 expressed by equation (6) based on the output _e5 .

Furthermore, the DC voltage obtained from multiplier circuits 8 and 12
E ₁ and E ₂ are supplied to the division circuit 24 of the arithmetic circuit 23, and based on the DC voltages E ₁ and E ₂ , E ₂ /E ₁ =K ₀ K ₁ I ₀ ² R _S R ₀ /2・2C _S /K ₁ K ₃ I ₀ ² R ₀ C ₁ R ₁ = K ₀ /K ₃ C ₁ R ₁・R _S C _S = ω ₀ R _S C _S = tan δ = D …(8) An output Q representing the loss D of the capacitive element 2 is obtained.

The above is a capacitive element loss measuring device that has been proposed conventionally. It is possible to determine the loss D expressed by ω ₀ R _S C _S =D, but since the output Q is the output obtained by dividing the DC voltages E ₁ and E ₂ , the DC voltage The AC voltages multiplied by the AC voltages e ₃ and e ₀ ′ for the multiplier circuits 8 and 12 obtained by E ₁ and E ₂ , respectively, are the capacitance C _S and resistance of the capacitive element 2 to be measured.
Since the AC voltage e ₁ takes a level according to the value of R _S , the DC voltages E ₁ and E ₂ are generated by the multiplier circuits 8 and 12.
It is difficult to obtain with high resolution regardless of the values of the capacitance C _S and the resistance R _S of the capacitive element 2 to be measured.
It has the disadvantage that high resolution cannot be obtained regardless of the values of C _S and resistance R _S.

Therefore, the present invention aims to propose a novel capacitive element loss measuring device free from such drawbacks, which will become clear from the detailed description below.

FIG. 2 shows an example of a loss measuring device for a capacitive element according to the present invention. Corresponding parts to those in FIG. AC constant voltage source 1 that provides an AC constant voltage e ₀
The capacitive element 2 to be measured, which is represented by a series equivalent circuit of a capacitance C _S and a resistor R _S , has a constant value expressed by equation (1)' as described above in FIG. They are connected via a constant current resistor R ₀ so that a current i ₀ flows and an alternating current voltage e ₁ expressed by the above-mentioned equation (2) is obtained at the capacitive element 2 to be measured.

In addition, an operational amplifier 6, a resistor R ₁ and a capacitor C ₁ are connected to both ends of the constant current resistor R ₀ as described above in FIG.
The output side of the phase shift circuit 5 is connected to the input side of _the phase shift circuit ₅ consisting of Thus, as described above with reference to FIG. 1, an AC voltage e ₃ having a phase difference of 90° with respect to the AC voltage e ₀ ' expressed by equation (3) described above is obtained.

The alternating current voltage _e1 obtained from both ends of the capacitive element 2 to be measured is passed through an amplifier 7 as necessary to obtain an output voltage having a substantially constant level even when the level of the input voltage changes. circuit 3
Based on the AC voltage e ₁ from this amplifier circuit 31, e ₂ =K ₂ I ₀ (R _S sinωt−1/ωC _S cosωt) …(9) (However, K ₂ is coefficient) is designed to obtain an AC voltage e ₂ having a substantially constant level. In this case, the AC voltage e ₂ has an approximately constant level, which means that This means that the absolute value of the AC voltage e ₂ expressed by |e ₂ | has _a substantially constant level.
are the capacitance C _S and resistance R _S of the capacitive element 2 to be measured.
Even if changes within the planned range, that is, even if C _S and R _S in equation (9) change within the planned range, the coefficient K ₂ (amplification degree) changes accordingly, The so-called AC voltage e ₂ is made to be obtained at a substantially constant level.
It consists of an amplifier circuit with AGC function.

Furthermore, as described above, the AC voltage _e2 having a substantially constant level obtained from the amplifier circuit 31 is applied to one side of the multiplier circuit 8 consisting of the multiplier circuit main body 10 and the low frequency converter 11 similar to those described above in FIG. The AC voltage e ₃ expressed by the equation (3) mentioned above, which is supplied to the input side of one multiplier circuit 8 and obtained from the phase shift circuit 5 to the other input side of the multiplier circuit 8, is required as described above in FIG. is supplied through the amplifier 9 accordingly, and thus the multiplier circuit 8
Based on the AC voltages e ₂ and e ₃ , E ₁ ′=K ₂ K ₃ I ₀ ² R ₀ C ₁ R ₁ /2C _S …(4)′ according to equation (4) shown in FIG. The arrangement is such that a DC voltage E ₁ ', which is inversely proportional to the capacitance C _S of the capacitive element 2 to be measured, is obtained. In this case, from the multiplier circuit main body 10 of the multiplier circuit 8, e ₄ ′=e ₂・K ₃ e ₃ =K ₂ I ₀ (R _S sinωt−1/ωC _S cosωt)×{−K ₃ I ₀ R ₀ ω
C ₁ R ₁ sin(ωt+π/2)} =K ₂ K ₃ I ₀ ² R _S R ₀ ωC ₁ R ₁ sin2ωt/2+K ₂ K ₃ I ₀ ² R ₀ C ₁ R ₁ (
1 + cos2ωt) /2C _S =K ₂ K ₃ I ₀ ² R ₀ C ₁ R ₁ /2C _S −K ₂ K ₃ I ₀ ² R ₀ ωC ₁ R ₁ /2 (R _S sin
2ωt−1/ωC _S cos2ωt)…(5)′ The alternating current voltage e ₄ ′ is obtained,
Correspondingly, the DC voltage E ₁ ' expressed by the above-mentioned equation (4)' is obtained from the low frequency converter 11.

Furthermore, the AC voltage e ₂ having a substantially constant level obtained from the amplifier circuit 31 is applied to one input side of the multiplier circuit 12 consisting of the multiplier circuit main body 14 and the low-frequency amplifier 15 similar to those described above in FIG. A constant current resistor _R0 is supplied to the other input side of the multiplier circuit 12.
The alternating current voltage e ₀ ′ expressed by the above-mentioned equation (1)″ obtained from both ends of Therefore, the alternating voltage e ₂ and
E ₂ ′=K ₀ K ₂ I ₀ ² R _S R ₀ /2 ...(6)′ according to equation (6) shown in FIG. 1 based on e ₀ ′, A DC voltage E ₂ ' proportional to the resistance R _S is obtained.
In this case, from the multiplier circuit body 14 of the multiplier circuit 12, e ₅ ′=e ₂・K ₀ e ₀ ′=K ₂ I ₀ (R _S sinωt−1/ ωC _S cosωt)
・K ₀ I ₀ R ₀ sinωt =K ₀ K ₂ I ₀ ² R _S R ₀ (1−cos2ωt)/2−K ₀ K ₂ I ₀ ² R ₀ sinω
t/2ωC _S =K ₀ K ₂ I ₀ ² R _S R ₀ /2−K ₀ K ₂ I ₀ ² R ₀ /2 (R _S cos2ωt+1
/ωC _S sin2ωt)…(7)′ The alternating current voltage e ₅ ′ is obtained,
Correspondingly, the DC voltage E ₂ ' expressed by the above-mentioned equation (6)' is obtained from the low frequency converter 15.

Also, the DC voltage obtained from multiplier circuits 8 and 12
E ₁ ′ and E ₂ ′ are connected to the arithmetic circuit 23 as in the case of FIG.
is supplied to the division circuit 24, from which the DC voltage
Based on E ₁ ′ and E ₂ ′, E ₁ ′ / E ₁ ′ = K ₀ K ₂ I ₀ ² R _S R ₀ /2・2C _S /K ₂ K ₃ I ₀ ² R ₀ C ₁ R ₁ = K ₀ /K ₃ C ₁ R ₁・R _S C _S = ω ₀ R _S C _S = tan δ=D (8)' The measured capacitive element 2 in the case of Fig. 1
The output Q' representing the loss D of the capacitive element 2 to be measured is the same as the output Q representing the loss D of the capacitive element 2 to be measured.

The above is an example of the configuration of the capacitive element loss measuring device according to the present invention. According to this configuration, the output Q' obtained from the division circuit 24 of the arithmetic circuit 23 by dividing the DC voltages E ₁ ' and E ₂ ' is the same as the output Q in the case of Fig. 1, so the output Q' can be expressed as ω ₀ R _S C _S = D as seen in the series equivalent circuit of the capacitive element 2 to be measured, as in the case of Fig. 1. It is clear that it is possible to determine the loss D that occurs.

However, in the case of the capacitive element loss measuring device according to the present invention as shown in FIG.
It is the output obtained by dividing E ₁ ′ and E ₂ ′, and the DC voltages E ₁ ′ and E ₂ ′ are multiplied by the AC voltages e ₃ and e ₀ ′ for the multiplier circuits 8 and 12, respectively. The AC voltage is the capacitance of the capacitive element 2 to be measured.
Since the AC voltage e ₂ has a substantially constant level regardless of the values of C _S and resistor R _S , the DC voltages E ₁ ′ and E ₂ ′ are applied to the static voltage of the capacitive element 2 to be measured from the multiplier circuits 8 and 12, respectively. In order to obtain high resolution regardless of the values of the capacitance C _S and the resistance R _S , the AC voltage to be multiplied by the AC voltages e ₃ and e ₀ for the multiplier circuits 8 and 12, respectively, is
This method is easier and more reliable than the conventional case described above _{in FIG .} In this way, the output Q _' can be obtained with higher resolution than the output _Q in the conventional case described above in FIG. It is something that is easy to do.

Therefore, in the case of the capacitive element loss measuring device according to the present invention described above in _FIG. and the value of the resistor R _S , the first
This method has a great feature of being able to provide higher resolution than the conventional case described above in the figure.

The above description has only shown one example of the present invention; for example, an amplifier circuit may be inserted between each of the multiplier circuits 8 and 12 and the divider circuit 24 as necessary; It is also possible to replace the circuits 8 and 12 with a synchronous detection circuit in which the multiplier circuit bodies 10 and 14 are replaced with the synchronous detection circuit body, and various other modifications and changes may be made without departing from the spirit of the present invention. will be able to do it.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a conventional capacitive element loss measuring device, and FIG. 2 is a system diagram showing an example of a capacitive element loss measuring device according to the present invention. In the figure, 1 is an AC voltage source, 2 is a capacitive element to be measured, and C _S
is capacitance, R _S is resistance, R ₀ is constant current resistance, 5
is a phase shift circuit, 8 and 12 are multiplication circuits, 10 and 1
4 is the multiplication circuit main body, 11 and 15 are low frequency devices,
Reference numeral 31 indicates an amplifier circuit.

Claims (1)

[Claims] 1. An AC voltage source, and a phase shift circuit configured to obtain a third AC voltage having a phase difference of 90° with respect to the AC voltage obtained from the AC voltage source. , Based on the first AC voltage that is the AC voltage drop across the capacitive element to be measured, which is connected to the AC voltage source so that a constant current flows from the AC voltage source side, it is approximately constant even if its level changes. 2nd with level
an amplifier circuit having an AGC function configured to obtain an alternating current voltage; and a first direct current voltage inversely proportional to the capacitance of the capacitive element to be measured based on the second and third alternating voltages. A second DC voltage proportional to the resistance of the capacitive element to be measured is calculated based on the first multiplier circuit or synchronous detection circuit, the AC voltage obtained from the AC voltage source, and the second AC voltage. a second multiplier circuit or a synchronous detection circuit designed to obtain
and an arithmetic circuit configured to obtain an output representing the loss of the capacitive element to be measured, which is obtained by dividing the DC voltage of the first DC voltage by the first DC voltage.