JPH032573A - Measuring instrument for q of coil and measuring method thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for determining the Q factor (
The present invention relates to a measuring device (hereinafter simply referred to as Q) and a measuring method therefor, and particularly to a measuring device and a measuring method thereof that can automate measurement.

[Conventional technology and its issues]

A conventional method for measuring the Q of a coil is to use a Q meter. Although this method allows for highly accurate measurements, it has the disadvantage that it is cumbersome and time-consuming to operate, making it difficult to automate.

Also, the resonant frequency is f. There is also a method of finding Q from the resonance frequency and the bandwidth by utilizing the fact that there is a relationship of 1, where B is the bandwidth. However, this method also incorporates adapters and switching relay devices in order to be able to measure a wide variety of coils, making the measurement complicated and susceptible to the effects of impedance, stray capacitance, residual inductance, etc. other than the coil being measured. , there was a problem of poor measurement accuracy.

-When fishing on a boat, set the resonant impedance of the coil to be measured to Z. ,
Inductance is 15, capacitance is C1, resonance angular frequency is ω. Then, there is the following relationship.

Q-Zo×ωoC-Zo×ωo]- Then, the resonant impedance Z. , resonant angular frequency ω. ,
It has also been conventional practice to calculate Q by measuring capacitance C or inductance. However, in this case as well, as with the above method, there is a problem in that the measurement accuracy decreases due to the influence of impedances and circuit systems other than the coil to be measured.

[Purpose of the invention]

The present invention has been made in view of these conventional drawbacks, and provides a high-precision Q measuring device and measuring method that allows easy automation of measurement, reduces errors caused by the circuit system around the coil, and provides a highly accurate Q measuring device. The purpose is to

[Means to solve the problem]

The Q measuring device and its measuring method according to the present invention provide an accurate Q measuring device and its measuring method.
Prepare two coil samples for which the value of is known, and the resonance impedance Z of each. is measured with this measuring device,
Accurate Q value and resonance impedance Z measured with this device
. A correlation equation is derived between the value of the resonant impedance Z of the coil to be measured. is measured, and the Q of the coil to be measured is approximately determined based on this formula.

〔Example〕

FIG. 1 shows the Q of a high-frequency coil (solid line in FIG. 2) as shown in FIG. 2, and the resonant impedance Z measured by the measuring device according to the present invention. FIG.

Now, Z is the resonant impedance of the coil. , the inductance and the resonant angular frequency is ω. If this is the case, ideally there would be a relationship of (1) as described above, that is, a proportional relationship as shown by the broken line in FIG.

However, in reality, it is affected by impedances and circuit systems other than the coil under test, so the characteristics will be as shown by the thick solid line in FIG. That is, except for the portions before and after the resonance impedance Z1 shown in the figure, the lower and higher resonance impedances exhibit nonlinearity.

However, if we limit ourselves to the vicinity of resonance impedance Z1,
Q and resonance impedance Z. It can be seen that there is a nearly proportional relationship as shown by the -dotted chain line.

The present invention has been made with attention to this point.

First, the proportional relationship shown by the -dotted chain line is expressed as Q = a
Set Z + b - - - - - - - - ■ (However, a and b are constants) and prepare two coil samples whose exact Q value is known by measurement with a Q meter, etc. . and the resonant impedance Z of each sample. Q of the coil according to the invention
Measure with a measuring device.

If the Q of the first sample is Qo and the resonance impedance is Z, and the Q of the second sample is Q2 and the resonance impedance is Z2, then according to the formula, Q + = a Z H + b ------- ■ Q, = a
Z2+b---■. Therefore, from the formula ■ and the formula 0, the constants a and b are as follows.
is guided.

2, -2゜ 2, -22 By substituting these into equation (2), the following equation 0 is obtained.

2, -22 Zl -Z2 ■ As described above, the constants a and b of the equation (■) have been determined, so that the resonance impedance Z in the region along the dashed line in FIG. By measuring only the Q of the coil, it is possible to approximately calculate the Q of the coil.

For example, if the Q of the coil to be measured is QX and the resonant impedance is ZX, then Qx can be obtained from equation 0 as follows by simply measuring the resonant impedance ZX.

Therefore, the Q measuring device according to the present invention has an accurate Q of (l+
, Q2 are attached, and the resonant impedance Z of the first sample is
When measuring the resonant impedance Z2 of the second sample, the values Q1, Q of the resonant impedances Z1, Z2 and Q, respectively.
2 is substituted into Equation 0 and the resonance impedance ZX of the coil under test is measured.The value of the resonance impedance ZX is substituted into Equation 0 to obtain the value Q of the coil under test.

It is configured to calculate .

Furthermore, the method for measuring Q according to the present invention provides an accurate Q value Q,
, Q2 are known, and substitute these Ql and Qz into Equation 0. At the same time, measure the resonance impedance Z1 of the first sample and the resonance impedance Z2 of the second sample in advance to form Equation 0. , measure the resonant impedance ZX of the coil under test, and set it to 0.
This method is characterized in that the Q value QX of the coil to be measured is calculated by substituting it into the equation.

Note that the Q value of the first sample, that is, Ql, is the same as that of the third sample.
As shown in the figure, if one near the center value of the Q distribution of a large number of coils to be measured is selected, half of the coils will be found, making it easy to search. In general, the standard for the Q of a coil is the center value +
It is often specified at around 20%. Therefore, it is preferable to select a second sample whose Q value, that is, Q2, is approximately -25% or +25% of Q. Then, Q2
is a value that sufficiently covers the range of +20%. If Q2 is chosen to be +25% of Q, it is difficult to extract a second sample having such a value since there are only a few among many coils. However, Q2 is approximately 125% of Ql.
The sample can be easily constructed by connecting in parallel to the sample a resistor RIH with an impedance three times the resonant impedance Z1 of the first sample, as shown by the broken line in FIG. This is because if connected in this way, a parallel circuit of Z1 and 3×C will be formed, and the combined impedance will be three-fourths of Z, that is, 75%.

Note that L and L in FIG. 2 are the capacitor and inductance of the high-frequency coil of the sample, respectively.

Two samples must be prepared for each type of coil with different characteristics. It is only necessary to measure the resonant impedance of these samples once before measuring the coil to be measured of the same type. After that, Q can be determined by replacing the coil to be measured and measuring only its resonant impedance.

In this way, according to the measuring device and measuring method of the present invention, by simply preparing two samples with known Q values, even if the capacitance, inductance, and resonant angular frequency of the coil to be measured are unknown, Q can be easily measured.

〔Effect of the invention〕

According to the present invention, automatic measurement can be easily performed because it is sufficient to measure the resonant impedance, that is, the peak value of the resonant voltage waveform of the coil. In addition, the standard measurement system such as a Q meter and the measurement system using this device must be calibrated using two samples, including the influence of impedance other than the coil to be measured and the surrounding circuit system, so Q, ±(Ql This has the effect of obtaining high measurement accuracy within the range of c.

[Brief explanation of drawings]

Fig. 1 is a characteristic diagram showing the correlation between Q measured by the reference measurement system and resonance impedance measured by the device of the present invention, Fig. 2 is a circuit diagram showing an example of the configuration of a coil sample, and Fig. 3 is the measured object. This is a distribution diagram of Q of the coil.・Q2 Coil Q factor resonance impedance

Claims (6)

[Claims] (1) Two coil samples with known accurate Q values (Q_1, Q_2) are attached, and the resonant impedance (Z_1) of the first sample and the resonant impedance (Z_2) of the second sample are During measurement, the respective resonance impedances (Z_1, Z_2) and Q values (Q_1, Q_
2) is substituted into the calculation formula below and the resonant impedance (Z_x) of the coil under test is measured. By substituting the value of the resonant impedance (Z_x) into the calculation formula, the Q( 1. A coil Q measurement device, characterized in that it is configured to calculate Q_x). ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (2) The coil Q measuring device according to claim 1, wherein the resonant impedance (Z_2) of the second sample is approximately three-fourths the value of the resonant impedance (Z_1) of the first sample. (3) A high-frequency coil is used as the first sample, and a resistor with an impedance approximately three times the resonant impedance (Z_1) of the first sample is connected to the resonant impedance (Z_1) of the first sample.
3. The coil Q measuring device according to claim 2, wherein the second sample is formed by connecting the coil in parallel with the coil. (4) Prepare two coil samples for which the exact value of Q is known, and compare the Q of the first sample (Q_1) and the Q of the second sample (
Substitute Q_2) into the formula below, measure the resonant impedance of the first sample (Z_1) and the resonant impedance of the second sample (Z_2), and substitute them into the formula to calculate the value of the coil to be measured. Resonance impedance (Z_x)
Q of a coil characterized in that the Q (Q_x) of the coil to be measured is calculated by measuring and substituting into the calculation formula.
Measuring method. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (5) The coil Q measuring method according to claim 4, wherein the resonance impedance (Z_2) of the second sample is approximately three-quarters of the resonance impedance (Z_1) of the first sample. (6) A high-frequency coil is used as the first sample, and a resistor with an impedance approximately three times the resonant impedance (Z_1) of the first sample is connected to the resonant impedance (Z_1) of the first sample.
6. The method for measuring the Q of a coil according to claim 5, wherein the second sample is formed by connecting the coil in parallel with the coil.