JP3160043B2 - Apparatus and method for measuring transformer parameters - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for measuring transformer parameters such as transformer turns ratio, self-inductance, mutual inductance, and DC resistance.

[0002]

2. Description of the Related Art FIG. 3 shows an apparatus for measuring the transformer parameters. The signal source 2 for measurement is grounded, and the ungrounded terminal is connected to one winding 12 of the transformer 10 to be measured.
Terminal x. Voltmeter 6 between terminals y and the terminal y of the other winding 14 of the transformer 10 'having an input capacitance C _B
However, a voltmeter 4 having an input capacitance C _A is connected between the terminal x and the terminal x ′ of the winding 12. Input capacitance C _A, C _B is typically of the order of 100 pF. A ground ammeter 8 is connected to the terminal x '. To determine the quality of the transformer 10, it is necessary to measure the self-inductance, the DC resistance, the winding ratio, the mutual inductance, and the like of one of the windings. Terminal x 'and terminal y' can be interrupted as needed.
The DC resistance and self-inductance from the voltmeter 4 and ammeter 8 measurements, the mutual inductance from the voltmeter 6 and ammeter 8 measurements, and the winding ratio from the voltmeter 4 and voltmeter 6 measurements are calculated by the calculator 20. Is calculated.

[0003] In such parameter measurement, since which winding of the transformer 10 is connected to the signal source 2 is not particularly considered, the following measurement accuracy degradation may occur.

The ratio of the number of turns of the winding 12 to the number of turns of the winding 14 is 1
When the pair of n, the current flowing through the ammeter 8, in addition to the current through the winding 12, the current flowing through the capacitance _{C A,} and capacitance C
_B is a is converted into the winding 12 side n ² C _B there is current flowing containers <br/> amount of I table. Therefore, the error in the current measurement is substantially determined by C _A + n ² C _B , and becomes large when n is large.

[0005] The measurement error of the voltmeter 6 by partial hypotensive the series resistance and capacitance C _B of the winding 12 is predominantly. That is, the series resistance of the windings 12 and 14 is set to γ _A , γ _B
If the coupling coefficient is sufficiently large, the series resistance of the winding 14 is n ² γ _A + γ _B. When the winding resistance is proportional to the number of turns, n
^{_{2 γ A + γ B = (}} n + 1) γ B , and the increase with n, the partial pressure effect with the (n + 1) γ _B and C _B increases with n.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to eliminate the above problems by properly setting the connection between the winding and the signal source in measuring transformer parameters.

[0007]

SUMMARY OF THE INVENTION In one embodiment of the present invention, one of the transformer windings having the greater number of turns is connected to a signal source to reduce voltage and current measurement errors.

In order to perform the above setting, it is also possible to measure the winding voltage and provide a means for connecting the signal source to the high voltage side depending on the magnitude of the winding voltage.

[0009]

1 and 2 show an embodiment of the present invention.
Components having the same reference numerals and symbols as those in FIG. 3 are equivalent to each other.

1 differs from FIG. 3 in that the signal source 2 and the transformer 10 are connected via the switch 30 and the measuring apparatus 100 is controlled by the control calculation means 40. The terminal x 'and the terminal y' are connected. First, the switch 30 selects one of the windings 12 and 14 under the control of the means 40 (the winding 12 is selected in the figure). Means 40 compares the voltage readings of voltmeters 4, 6 and, if there is a difference in the voltage readings, changes the selection of switch 30 if necessary, so that the output of signal source 2 produces a higher voltage. To be introduced on the winding side.

Next, transformer parameters are calculated as necessary from the measured values of the ammeter 8 and the voltmeters 4 and 6 of the ammeter. The output of the signal source 2 may be either direct current or alternating current, and it is preferable that the voltmeters 4 and 6 ammeter 8 can also measure direct current and alternating current. Of course, the function and performance of the voltmeters 4, 6 and ammeter 8 will be selected depending on which of the transformer parameters is desired. Further, the voltmeters 4 and 6 and the ammeter 8 are connected to the signal source 2
A complex voltmeter (or a vector voltmeter) or a complex ammeter (or a vector ammeter) that can measure the absolute value and the phase with reference to the output of the above can also be used. In any case, the voltmeter and the ammeter used in the present invention are equivalent to commercially available and commercially available ones, and are easily realized.

FIG. 2 shows another embodiment, in which the voltmeter 6 is omitted from the embodiment of FIG. 1 and the voltmeter 4 is used for measurement of both windings 12 and 14. In this case, the voltmeter 4
Is switched by the switch 50 to measure the voltage between the terminals of the winding 12 or the winding 14. It is preferable to keep the input capacitance inserted in parallel to the windings 12 and 14 at the time of switching. Therefore, a buffer is used as needed. The control calculation means 60 has a function of controlling the switch 50 in addition to the same function as the control means 40. Windings 12, 14
Switch 50 according to which terminal voltage measurement is to be performed.
To switch the input of the voltmeter 4 appropriately.

The control calculation means 20, 40, 60 can be easily realized by a control computer including a microcomputer or a personal computer.

[0014]

As described in detail above, the implementation of the present invention improves the measurement accuracy because the signal source is always connected to the winding having the smaller number of turns in measuring the transformer parameters.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention.

FIG. 2 is a circuit diagram of another embodiment of the present invention.

FIG. 3 is a circuit diagram for explaining a conventional example of transformer parameters.

[Description of Signs] 2: Signal source 4, 6: Voltmeter 8: Ammeter 10: Transformer to be measured 12, 14: First and second windings 20, 40, 60: Control calculation means 30, 50: switch

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G01R 31/02-31/06 G01R 31/00 G01R 29/20 G01R 27/00-27/32

Claims (2)

(57) [Claims] A first winding having terminals x and x ';
'In the measurement method of the transformer parameters and a second winding and a terminal x' pin y and the terminal y connect the measuring signal source and between the terminal x ', the terminal by the voltage measuring means The voltage between terminal x and terminal x 'and the voltage between terminal y and terminal y' are measured, and the voltage between terminal x and terminal x 'is
When the voltage is lower than the voltage between the terminals y ′, the measurement signal source is connected to the terminal
A method for measuring transformer parameters, characterized in that it is connected between y and a terminal y ' . 2. A first winding having terminals x and x '.
A measured object having a second winding with terminals y and y '
Apparatus for measurement of transformer parameters consisting later to measure the transformer parameters constant transformer (i)及至 (f): (a) signal source and a terminal 1 and the terminal 2, (b) current meter, (c) connecting means for connecting said terminals 2 in parallel connection of 'the terminal y and' the terminal x via the ammeter, (d) the terminal 1 or the terminal x or the terminal y a switching means for alternatively connecting, (e) the terminal x 'and the first voltage and the terminal y and the terminal y between the terminal x' second voltage measuring means voltage can be measured between, and ( F ) Control calculating means connected to the ammeter, the voltage measuring means, and the switching means and having the following functions : (1) comparing the first and second voltages and when the voltage values are different By controlling the switching means, the end of the winding having the higher value of the generated voltage is A function of connecting the terminal 1 to the terminal x or the terminal y , and (2) a function of calculating the transformer parameters from the measured value of the ammeter and the measured value of the voltage measuring means.