JPH04233205A - Compound type inductive voltage divider - Google Patents

Abstract

PURPOSE:To obtain a divided voltage output having precision equal to that of a self-induction voltage divider, by detecting the error voltage of a self-induction voltage divider and a secondary winding of one side, and adding the detected voltage, which is electrostatically insulated from the input, to the voltage of the similarly insulated other side secondary winding, as a correction voltage to obtain a divided output voltage. CONSTITUTION:The comparison of corresponding tap voltages of windings 5, 6 is performed by connecting each terminal of the primary winding 81 of an auxiliary transformer 8 with corresponding taps of the windings 5, 6. When the output voltage of the secondary winding 82 of the auxiliary transformer 8 is expressed by n(V1'-V1''), the both ends voltage of a second secondary winding 7 is nV1'' which is equal to the first secondary winding 6. The output voltage V2 is obtained by adding n(V1'-V1''), which is the voltage of the secondary winding 82 of the auxiliary transformer 8, to the voltage nV1'', so that V2 is expressed by V2=n(V1'-V1'')+nV1'=nV1'. Thereby the output voltage V2 can be led out with precision approximate to the winding 5 of a self-induction voltage divider.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-wound inductive voltage divider.

0002

[Prior Art] Generally speaking, a voltage divider has a tap connected to a resistor, and by changing the position of this tap,
It is reminiscent of obtaining low voltage from high voltage. However, when considering using such a voltage divider in the power supply section,
Power consumption is large, and when used in the power supply section of measuring instruments such as wattmeters and watt-hour meters, noise from the input voltage source appears on the output side, causing a decrease in accuracy. Undesirable.

Furthermore, it is difficult to make the impedance of the voltage divider sufficiently smaller than the impedance of the measuring instrument, which deteriorates measurement accuracy.

[0004] Conventionally, therefore, a transformer has been incorporated into a voltage divider in order to reduce power consumption, electrically insulate input and output, and reduce signal source impedance. According to such a voltage divider, the current that flows is small due to the excitation impedance, and the power consumption is dramatically reduced, and the input and output are electrostatically coupled by the primary and secondary windings. , can be electrically insulated.

[0005]

[Problems to be Solved by the Invention] However, even with such a voltage divider, it is undeniable that the accuracy decreases due to ratio errors and phase angles of the transformer used.

SUMMARY OF THE INVENTION In view of these conventional problems, it is an object of the present invention to provide a compound-wound inductive voltage divider which has high voltage division accuracy and which provides electrostatic insulation between input and output voltage circuits.

[0007]

[Means for Solving the Problems] Therefore, the compound winding type inductive voltage divider of the present invention includes an excitation circuit consisting of a first iron core and an excitation winding attached to the first iron core, A second core is superimposed on the core, and a winding is attached to both the first and second cores with the same number of turns as the excitation winding, thereby forming a self-dividing type induction voltage divider. a self-induction voltage divider having the same number of windings as that of the self-induction voltage divider, and a first coil which is wound in the same manner as that of the self-induction voltage divider and is attached to both the first and second iron cores; The difference between the voltage induced in the second secondary winding, the winding of the self-induction voltage divider, and the voltage induced in the first secondary winding is input, and the voltage is electrostatically It includes a compound-turn transformer that outputs an insulated output, and an output circuit that combines the voltage induced in the second winding with the output voltage of the compound-turn transformer to produce a divided voltage output.

[0008]

[Operation] According to the present invention, a voltage is induced in the self-induction voltage divider by the magnetic flux in the first core of the excitation circuit, and
The first
, a voltage is induced by the magnetic flux of the second core using the principle of a two-stage transformer, and the error voltage between the self-induction voltage divider and one of the secondary windings is detected by a compound transformer, whose input is static electricity. It is configured to add the detected voltage, which is electrostatically isolated from the input, to the voltage of the other secondary winding, which is also electrostatically isolated from the input, as a correction voltage to create a divided output voltage, so the input is different from the input. It is possible to obtain a divided voltage output with accuracy equivalent to that of a self-induction voltage divider in an electrostatically isolated state.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a compound winding type inductive voltage divider according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a winding structure. The winding structure will be described below with reference to FIG. 1 and also to FIG. 2. In FIG. 1, 1 is a voltage source, 2 is a first iron core, and 3 is an excitation winding, and as shown in FIG. 2,
This excitation winding 3 is wound around the first iron core 2, and the voltage source 1
An excitation circuit is constructed that generates magnetic flux from the excitation winding 3 into the iron core 2 using the AC voltage V1 from the excitation winding 3. Here, the number of turns of the excitation winding 3 is assumed to be 10n.

A second iron core 4 is superimposed on the first iron core 2, and a winding 5 is wound around both the first and second iron cores 2 and 4 with the same number of turns as the excitation winding 3. A self-dividing type inductive voltage divider is constructed. That is, a bundle of 10 conductive wires with the same cross-sectional area is wound n times, and then the conductive wires are connected in series to form winding 5, and each connection point of the conductive wire is tapped Ta0.
~Ta10 is taken out to form a self-dividing type induction voltage divider, and the number of turns of the winding 5 is 10n similarly to the excitation winding 3 described above. Tap Ta0 of winding 5,
Ta10 is connected to the voltage source 1, and the same voltage V1 as the excitation winding 3 is applied thereto.

Furthermore, first and second secondary windings 6, 7 are wound around both iron cores 2, 4. These first and second secondary windings 6 and 7 have the same number of turns as the winding 5 of the self-induction voltage divider, and are wound in the same way so that they are connected to both the first and second iron cores 2. , 4. That is, these windings 6 and 7 are made by first making a bundle of 20 conductors with the same cross-sectional area and the same length and winding them n times, then connecting each 10 wires in series to form two secondary windings with a number of turns of 10n. Ten conductor connection points are taken out from each winding 6, 7 as taps Tb0 to Tb10 and Tc0 to Tc10. The tap Tb0 of the first secondary winding 6 and the tap Ta0 of the winding 5 of the self-induction voltage divider are commonly connected. Tap Tc0 of the second secondary winding 7 is connected to the output terminal.

Reference numeral 8 is a compound auxiliary transformer, and reference numerals 9 to 11 are tap changeover switches. The auxiliary transformer 8 inputs the difference between the voltage induced in the winding 5 of the self-induction voltage divider and the voltage induced in the first secondary winding 6, and electrostatically insulates the voltage. The primary winding 8
One end of the winding 81 is selectively connected to one of the taps Ta0 to Ta10 of the winding 5 of the self-induction voltage divider through the changeover switch 9, and the other end of the same winding 81 is connected to the first tap through the changeover switch 10. It is selectively connected to any one of taps Tb0 to Tb10 of the secondary winding 6. One end of the secondary winding 82 of the auxiliary transformer 8 is connected to the output terminal,
The other end of the winding 82 is selectively connected to one of the taps Tc0 to Tc10 in the second secondary winding 7 via a changeover switch 11.

The changeover switches 9 to 11 are mutually interlocked as illustrated by the dashed lines in FIG.
1st to 11th taps Ta0 to Ta1
0 (Tb0 to Tb10 /Tc0 to Tc10), if a one-to-one correspondence is established between the same numbers, the changeover switches 9 to 11 will each point to their corresponding taps. That is, for example, FIG.
As shown in FIG. 3, when the changeover switch 9 points to the tap Ta9, the other changeover switches 10 and 11 point to the corresponding taps Tb9 and Tc9 in the respective windings 6 and 7.

The compound winding induction voltage divider constructed as described above operates as follows.

First, the entire winding 5 of the self-induction voltage divider has the following:
The magnetic flux of the iron core 2 induces a voltage V1' of approximately the same magnitude as the input voltage V1. On the other hand, since the input voltage V1 is directly applied to the winding 5, the voltage difference between the input voltage V1 and the induced voltage V1' is added to the inductive impedance formed by the iron core 4 and the winding 5, and a current flows. however,
This differential voltage (V1 - V1') is a very small voltage, and at this voltage, the current flowing through the relatively large inductive impedance is extremely small, and a voltage divider with extremely high voltage division accuracy is constructed.

The first and second secondary windings 6, 7 are connected to both iron cores 2,
4, and induces a voltage V1'' that almost matches the input voltage V1 using the principle of a two-stage transformer. However, it differs slightly from the voltage V1 due to the resistance of the conducting wire and the distributed capacitance distributed between the windings. For the same reason, the voltages appearing at each tap Tb0-Tb10, Tc0-Tc10 are also not as accurate as the divided voltages appearing at taps Ta0-Ta10 of the winding 5.

However, since the 20 conductive wires of the windings 6 and 7 are bundled and wound at the same time, their geometrical shapes match well, and therefore the electrical circuit consisting of 20 conductive wires is The electromagnetic properties also match well with each other.

Therefore, if the voltages of the corresponding taps of the windings 5 and 6 are compared and the difference voltage is added to the voltage of the corresponding taps of the winding 7 as a correction voltage, the corrected voltage will be the same as that of the windings. This results in extremely good agreement with the voltage of No. 5.

Comparison of the corresponding tap voltages of the windings 5 and 6 shows that each end of the primary winding 81 of the auxiliary transformer 8 is
This is done by connecting the corresponding taps. In other words, since the potential is common at one end of windings 5 and 6,
The primary winding 81 of the auxiliary transformer 8 has n(V1'-V1''
) (0≦n≦1), and thereby a voltage approximately equal to n(V1'-V1'') is induced in the winding 82.

Here, since n(V1'-V1'') itself is a very small value, the error between the input and output of the auxiliary transformer 8 is negligible when viewed from the whole nV1. .

Therefore, ignoring this error, the output voltage of the secondary winding 82 of the auxiliary transformer 8 is calculated as n(V1'-V1'
), the voltage across the second secondary winding 7 is nV1'', which is the same as that of the first secondary winding 6, and this voltage n
V1'' is the voltage n(V
1'-V1'') is added to the output voltage V2
Therefore, V2 = n (V1'-V1'') + n
It is derived that V1'' = nV1' and that the output voltage V2 can be taken out with the same accuracy as the winding 5 of the self-inductive voltage divider.

Then, the voltage nV from the second secondary winding 7
1'' as well as the differential voltage n(
V1'-V1'') is also taken out while being electrostatically insulated by the auxiliary transformer 8.

Therefore, according to this embodiment, it is possible to realize a compound winding type inductive voltage divider with extremely high voltage division accuracy and in which the input and output voltage circuits are electrostatically isolated.

FIGS. 3 to 6 show the test results of a prototype based on the circuit of the above embodiment. Note that the output voltage of the prototype voltage divider is one-tenth of the input voltage.

First, in FIG. 3, the rated input voltage is 50 [Hz].
Figure 4 shows the frequency characteristics of the ratio error and phase angle in the winding 5 portion of a 200 [V] low-frequency compound-wound inductive voltage divider. It shows the frequency characteristics of ratio error and phase angle. Comparing both characteristics, it can be seen that they match very well.

FIG. 5 also shows that the rated input voltage is 1000 [H].
Figure 6 shows the ratio error and phase angle frequency characteristics of the winding 5 of each compound winding type inductive voltage divider for high frequency of 200 [V] at 200 [V]. It shows the frequency characteristics of ratio error and phase angle. Looking at these figures, both characteristics match very well.

In general, it is confirmed that the characteristics of the entire compound-wound induction voltage divider are in good agreement with the characteristics of the self-induction voltage divider, regardless of whether it is used for high frequencies or low frequencies.

[0028]

As explained above, according to the present invention, the self-induction voltage divider is excited by the magnetic flux in the first core of the excitation circuit, and two
The two secondary windings are excited using the principle of a two-stage transformer using the magnetic flux of the first and second cores, and the error voltage between the self-induction voltage divider and one of the secondary windings is detected using a compound transformer. , the detection voltage which is electrostatically isolated from the input is added as a correction voltage to the voltage of the other secondary winding which is also electrostatically isolated from the input to obtain a divided output voltage. Therefore, it is possible to obtain a divided voltage output with accuracy equivalent to that of a self-induction voltage divider while being electrostatically isolated from the input.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a compound-wound inductive voltage divider according to an embodiment of the present invention.

FIG. 2 is a mechanical structural diagram of the compound-wound inductive voltage divider shown in FIG. 1;

3 is a frequency characteristic diagram of a self-induction voltage divider section in a low-frequency induction voltage divider prototyped based on the embodiment shown in FIGS. 1 and 2. FIG.

FIG. 4 is a frequency characteristic diagram of the entire low-frequency inductive voltage divider that is the same as that shown in FIG. 3;

5 is a frequency characteristic diagram of a self-induction voltage divider section in a high-frequency induction voltage divider prototyped based on the embodiment shown in FIGS. 1 and 2. FIG.

FIG. 6 is a frequency characteristic diagram of the entire high-frequency inductive voltage divider that is the same as that shown in FIG. 5;

[Explanation of symbols]

2 First iron core 3 Excitation winding 4 Second iron core 5. Winding of self-induction voltage divider 6 First secondary winding 7 Second secondary winding 8 Compound winding auxiliary transformer 9 Tap changeover switch 10 Tap changeover switch 11 Tap changeover switch

Claims (1)

[Claims] Claims: 1. An excitation circuit comprising a first iron core and an excitation winding attached to the first iron core; a second iron core is superimposed on the first iron core; A self-induction voltage divider formed as a self-voltage type induction voltage divider by installing a winding over both iron cores and having the same number of turns as the excitation winding, and a winding and the number of turns of the self-induction voltage divider. first and second secondary windings that are the same and are wound in the same manner and are installed over both the first and second iron cores; and a winding of the self-induction voltage divider. and the voltage induced in the first two
a compound-turn transformer that inputs the difference between the voltage induced in the second winding and electrostatically insulates the voltage and outputs the voltage; An output circuit that synthesizes the output voltages of and outputs a divided voltage.