JP2514211B2 - Method and apparatus for measuring turns ratio of transformer - Google Patents

Description

The present invention relates to a transformer winding ratio measuring method and apparatus for accurately measuring the winding ratio of a transformer that is not magnetically completely coupled.

(Prior Art) FIG. 6 is a diagram for explaining a conventional example of a transformer winding ratio measuring method by the bridge method, and FIG. 7 is a diagram for explaining a conventional transformer winding ratio measuring method by a voltage ratio method. It is a figure. In the figure, OSC is an oscillator, D is a detector, T is a transformer under test, W ₁ and W ₂ are transformer windings, R ₁ , R ₂ , r ₁ and r ₂
Indicates a variable resistor.

In the inspection of transformers and the like, it is often a matter of whether or not the number of turns itself meets a predetermined specification. The bridge method and the voltage ratio method have been conventionally used to measure the turns ratio of a transformer that has already been commercialized.

For example, in the bridge method, as shown in FIG. 6, two transformer windings W ₁ and W ₂ are connected so as to be differential with respect to a power supply current, and variable resistors R ₁ , R ₂ , r ₁ and The bridge is balanced by adjusting r _2, and the transformation ratio n of the transformer windings W ₁ and W ₂ is calculated from the following equation.

n = n ₁ / n ₂ = R ₁ / R _{2 The} measurement frequency is basically set to 1 kHz according to JIS.

Further, the voltage ratio method to measure the transformer winding W and the primary winding W ₁ applies the output of the oscillator OSC to ₁ and the secondary winding terminal voltage V ₁ of the W _2, V ₂ as shown in FIG. 7 . Then, the turn ratio n = V ₂ / V ₁ is obtained from this voltage.

[Problems to be solved by the invention]

However, the above-mentioned conventional method has a problem that the winding ratio cannot be accurately measured because a value influenced by the coupling degree of the two coils is obtained. That is, the variation in the degree of coupling directly affects the measured value, which hinders the determination of the number of winding defects. In particular, in a switching power supply transformer or the like, a gap is often provided, but with such a transformer, the conventional method cannot provide a satisfactory result as a method for determining the number of winding defects.

The present invention solves the above problems, and
An object of the present invention is to provide a transformer winding ratio measuring method and device capable of measuring the winding ratio with high accuracy without being affected by the coupling degree of two coils.

[Means for solving problems]

Therefore, the method for measuring the turns ratio of the Tonrus of the present invention is a method for measuring the turns ratio of a transformer, in which the voltage of the primary winding of the transformer and the voltage of the secondary winding are obtained to obtain the turn ratio, and the voltage application mode is changed. According to each aspect, the voltage of the primary winding and the voltage of the secondary winding are measured, and the winding ratio is obtained by processing the measured values, and a device therefor applies an AC voltage. Oscillator, voltmeter for measuring the voltage of the primary winding and the voltage of the secondary winding, switch means for selectively connecting the oscillator and the voltmeter to the primary winding and the secondary winding, and the oscillator and the voltage for controlling the operation of the switch means. It is characterized in that it is provided with a control calculation means for obtaining the winding ratio of the transformer which reads the signal of the meter.

[Action]

In the method and apparatus for measuring the turns ratio of the transformer of the present invention, the voltage of the primary winding and the voltage of the secondary winding when the AC voltage is applied only to the primary winding, and the voltage of the primary winding when the AC voltage is applied to the secondary winding Since the voltage and the voltage of the secondary winding are measured, the influence of the degree of coupling between the two coils can be eliminated by calculating these values and obtaining the turns ratio of the transformer.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 shows a method 1 for measuring the turns ratio of a transformer according to the present invention.
FIG. 6 is a diagram for explaining an embodiment, in which OSC is an oscillator, V ₁ ,
V ₂ is a voltmeter, n ₁ and n ₂ are the number of turns, L ₁ and L ₂ are self-inductances, and M is a mutual inductance.

In the winding turns ratio measuring method according to the present invention, first,
As shown in FIG. 1 (a), the output of the oscillator OSC is applied to the primary winding and the voltage between the terminals of the winding is measured by the voltmeters V ₁ and V ₂ , and the ratio V ₂ / V ₁ is K ₁ And Next, FIG. 1 (b)
As shown in, the output of the oscillator OSC is applied to the secondary winding and the voltage between the terminals of the winding is measured by the voltages V ₁ and V ₂ , and the ratio V
Let ₁ / V ₂ be K ₂ . And as a winding ratio that is not affected by the gap Ask for. That is, turn ratio It is calculated by the relationship.

 Next, the reason will be described.

In FIG. 1 (a), Therefore, In addition, in FIG. 2 (b), Therefore, from the above Becomes

FIG. 2 is a view for explaining another embodiment of the transformer winding ratio measuring method according to the present invention. In this example, first, the voltage between terminals of the winding is measured with the voltmeters V ₁ and V ₂ by the circuit shown in FIG. 9A, and the ratio V ₂ / V ₁ is K ₁ . Next, as shown in FIG. 7B, the magnetic fluxes are connected so that the magnetic fluxes are added to each other, and the voltage between the terminals of the winding is measured by the voltmeters V ₁ and V ₂ , and the ratio V ₁ /
Let V ₂ be K ₂ . After that, the turns ratio is not affected by the gap Ask for. That is, turn ratio It asks by the relation of.

 Next, the reason will be described.

K ₁ = M / L ₁ …… From the formula, M = K ₁ L _{1 From the} formula Becomes

FIG. 3 is a view for explaining still another embodiment of the transformer winding ratio measuring method of the present invention. In this example, first, the voltage between terminals of the winding is measured with the voltmeters V ₁ and V ₂ by the circuit shown in FIG. 9A, and the ratio V ₂ / V ₁ is K ₁ . Next, the voltage between the terminals of the winding is measured by the voltmeters V ₁ and V ₂ in the circuit connection shown in FIG. 7B in which the magnetic fluxes cancel each other out, and the ratio V ₁ / V ₂ is K ₂ . . After that, the turns ratio is not affected by the gap Ask for. That is, turn ratio It asks by the relation of.

 Next, the reason will be described.

K ₁ = M / L ₁ …… From the formula, M = K ₁ L ₁ , from the formula Becomes

FIG. 4 is a diagram showing an embodiment of the present invention when there is a DC resistance. In each of the above examples, the DC resistance component of the winding wire was ignored. Actually, there is a DC resistance component in the winding, but this DC resistance component exists, but this DC resistance component is the vector voltage of another in-phase component based on the voltmeter that is not connected to the power supply. It can be ignored by multiplying.

In FIG. 4 (a), V ₂ is 90 with respect to the primary current.
° The phase is advanced. However, V ₁ becomes a voltage delayed by φ from V ₂ due to the DC resistance R. Therefore, the DC resistance component can be ignored by calculating V ₂ / V ₁ cosφ when obtaining the voltage ratio. As a simple method, an in-phase square wave may be generated from V ₂ and V ₁ may be synchronously detected. Alternatively, the vector voltage for the synchronized frequency is obtained from V ₁ and V ₂ .

FIG. 5 shows a transformer winding ratio measuring apparatus 1 according to the present invention.
It is a diagram showing a configuration of an embodiment, 11 is a transformer to be measured, 12 is a control arithmetic unit / A / D converter, 13 is an oscillator, 14 and 15
Is a vector voltmeter, 16 is an instruction circuit, 17 is a data setting circuit, and s1 to s12 are switches.

In FIG. 5, the transformer under test 11 is connected as a three-terminal structure transformer, and the oscillator 1 is connected to any transformer terminal.
3, switch so that the vector voltmeter 14 and 15 can be connected
1 to s12 are connected. Switch the control calculator / A / D converter 12 according to the procedure of the measuring method to be used.
Controls on / off of ~ s12 and vector voltmeter 14
And 15 are read and the operation using the above equation is performed to obtain the winding number cover. The data setting circuit 17 sets parameters such as range, reference value and frequency.

A case where the above-mentioned apparatus is used to perform the measurement of the method described with reference to FIG. 1 will be described.

First, when obtaining K ₁ , switches s1, s6, s7, s
Turn on 12 and read the voltage values of vector voltmeters 14 and 15. Then, by synchronously detecting the voltage V ₁ of the voltmeter 14 with the synchronous signal with respect to the voltage V ₂ of the voltmeter 15, V ₁ cos φ
Ask for. Or, when measuring the V _1, V _2, to measure the phase component and an imaginary component relative to V _1, V ₂ as V _1, V ₂ or reference to the synchronization signal to the other oscillator. After that, φ is obtained by calculating these measured values, and V
Calculate ₁ cos φ.

After obtaining V ₁ cosφ as described above, V ₂ / V ₁ cosφ is calculated to obtain K ₁ . In practice, DC resistance is ignored and cosφ is set to 1 without any problem.

Next, when obtaining K ₂ , switches s5, s10, s3,
Turn on s8 and read the voltage values of vector voltmeters 14 and 15. Then, similarly to the case of obtaining K ₁ , V ₂ / V ₁ cosφ is calculated to obtain K ₂ .

When K ₁ and K ₂ are obtained in this way, Is calculated and the instruction circuit 16 is instructed. In addition, the instruction in this case is , The value when calculating n ₂ / n ₁ is set in advance,
Further, the deviation% between the setting and the measured value and the number of turns of n ₁ and n ₂ may be set in advance, and the pass / fail judgment of the transformer or the instruction of the converted value may be performed by conversion or comparison with these values.

A case where the above-mentioned device is used to perform the measurement of the method described with reference to FIG. 2 or 3 will be described.

First, K ₁ is obtained in the same manner as the above method. However, if the pressure is increased, the measured value will be inaccurate due to the influence of the secondary load, etc. Therefore, wind down and measure, and calculate as K ₁ = 1 / K ₂ .

Next, when obtaining K ₂ , switches s1, s10, s7, s1
Turn on 2 and read the voltage values of vector voltmeters 14 and 15. And To find K ₂ . That is, the voltage across the primary winding is V ₁ -V ₂ . Whether or not the phases of the primary voltage and the secondary voltage are inverted when determining K ₁ , or K
_The arithmetic expression to be used may be selected depending on whether ₁ <K ₂ or not.

The present invention is not limited to the above embodiment, and various modifications can be made. As a method of improving the measurement accuracy, for example, in order to obtain K ₂ , the primary winding and the secondary winding must be connected in series, but in this case, the influence of the DC resistance component cannot be removed, so n ₁ > It is advantageous to have a relationship of n ₂ . When n ₁ <n ₂ , switches s1, s10, s7 and s12 are turned on and the vector voltmeter 14
When the voltage values of 15 and 15 are read, K ₂ is obtained by the method shown in FIG. ₁ as K ₁ . Then, the inverse winding number ratio may be calculated by taking the inverse of the obtained numerical value. Also,
The connection of the switches shown in FIG. 5 and other connection configurations may be appropriately modified in accordance with the above-mentioned purpose.

〔The invention's effect〕

As is clear from the above description, according to the present invention, the terminal voltages when the voltage is applied from the primary winding side and when the voltage is applied from the secondary winding side are measured. The calculation of the value can eliminate the influence of the degree of coupling. Therefore, it is possible to measure the winding ratio with high accuracy without being affected by the degree of coupling.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of the transformer winding ratio measuring method according to the present invention, and FIGS. 2 and 3 are diagrams for explaining other embodiments of the transformer winding ratio measuring method according to the present invention. FIG. 4 is a diagram showing an embodiment of the present invention when there is a direct current resistance, FIG. 5 is a diagram showing a configuration of one embodiment of a turns ratio measuring device for a transformer according to the present invention, and FIG. FIG. 7 is a diagram for explaining a conventional example of a transformer winding ratio measuring method by the bridge method, and FIG. 7 is a diagram for explaining a conventional transformer winding ratio measuring method by the voltage ratio method. OSC ...... oscillator, V _1, V ₂ ...... voltmeter, n _1, n ₂ ...... turns, L _1, L ₂ ...... self-inductance, M ...... mutual inductance, 11 ...... measured transformer, 12 ...... Control calculator / A / D converter, 13 ... Oscillator, 14 and 15 ... Vector voltmeter, 16 ... Indicator circuit, 17 ... Data setting circuit,
s1 to s12 …… Switch.

Claims (4)

(57) [Claims] 1. A winding ratio measuring method for a transformer, wherein a winding ratio is measured by measuring a voltage of a primary winding and a voltage of a secondary winding of the transformer, wherein the voltage of the primary winding is varied according to each mode by changing a voltage application mode. And a method for measuring the winding ratio of a transformer, wherein the winding ratio is obtained by measuring the voltage of the secondary winding and calculating the measured value. 2. A mode in which an AC voltage is applied only to the primary winding,
The method of claim 1, wherein the voltage of the primary winding and the voltage of the secondary winding are measured by applying an AC voltage only to the secondary winding. 3. A mode in which an AC voltage is applied only to the primary winding,
The voltage of the primary winding and the voltage of the secondary winding are measured by a mode in which the primary winding and the secondary winding are connected in series and an AC voltage is applied to the transformer. Turns ratio measurement method. 4. A turn ratio measuring device for a transformer, which measures a voltage of a primary winding and a voltage of a secondary winding according to each mode while changing a voltage application mode, and calculates a winding ratio by arithmetically processing the measured values. And an oscillator for applying an AC voltage, a voltmeter for measuring the voltage of the primary winding and the voltage of the secondary winding, a switch means for selectively connecting the oscillator and the voltmeter to the primary winding and the secondary winding, and the switch means. A winding number ratio measuring device for a transformer, comprising: a control calculating unit for controlling the operation of the device and reading a signal from an oscillator and a voltmeter to obtain a winding number ratio of the transformer.