JPH04192402A - Autotransformer - Google Patents

Abstract

PURPOSE:To prevent unit wirings located nearest a tap from being heated abnormally even if a large load current is made to flow through the windings by a method wherein leakage magnetic path materials, through which leakage magnetic fluxes generated by the unit wirings are made to pass, are respectively provided in the vicinities of the adjacent unit wirings, which are different from each other in the directions of their currents. CONSTITUTION:An exciting current flows from a unit wiring 7 situated on the side on one side of a tap T toward a unit wiring 6 situated on the other side of the tap T and a load current flows through a load connected to the tap T from the winding 6 toward the tap T so as to cancel the exciting current. The direction of the current of the winding 6 on the side on one side of the tap T becomes reverse to the direction of the current of the winding 7 on the other side of the tape T with the tap T as a reference, leakage magnetic fluxes generated by the respective windings 6 and 7 are applied to each other between the windings 6 and 7 on both sides of the tap holding the tap T between them and a leakage flux density between the windings 6 and 7 becomes excessive. However, the leakage magnetic fluxes respectively flow in leakage magnetic path materials 12 and 12 and the leakage magnetic flux generated by the winding 6 and the leakage magnetic flux generated by the winding 7 do not affect each other. Thereby, even if the load current is increased, an abnormal heat is not generated in the windings 6 and 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an autotransformer used, for example, as a power source for a flash hat welding device.

[Conventional technology]

Autotransformers are widely used because they are smaller in size relative to transformer capacity and are less expensive than isolation transformers.

In particular, in flash hat welding equipment that performs horizontal welding of steel plates, etc., an autotransformer is used as the welding power source in order to easily provide a welding current that corresponds to the thickness and width of the steel plate to be welded. .

By the way, Flashhat? The receptionist Brosesniko is
There is a process in which heating is performed while producing a flash, in which a relatively small current is passed, and a process in which heating is carried out without a flash, in which a large current is passed. This process is necessary to prevent this, and at this time, a large current flows through the autotransformer that is the welding power source.

For this reason, autotransformers used in welding power sources are
When the load is short-circuited, the structure is such that magnetic saturation is carried out to suppress the load current to a constant value, and as a result, a large amount of leakage magnetic flux is generated.

In addition, in this autotransformer, excitation current flows from the unit winding on one side of the tap provided on the winding to the unit winding on the other side, and from the unit winding on the other side to the tap. Load current flows towards the load connected to the tap. In other words, the direction of current in the unit winding on one side and the direction of current in the unit winding on the other side are opposite to each other with respect to the tap, and generally, the current direction between the unit windings on both sides of the tap is The leakage magnetic fluxes generated by the unit windings of the taps are added together in opposite directions, and due to electromagnetic induction due to the excessive leakage magnetic flux, the current flowing in the unit windings near the tap becomes excessive, causing abnormal heating. Become.

For example, the winding of an auto-transformer has a unit winding vA of 1.2°3...
・Wound the unit windings 1.2 to each other, 3 degrees to each other, 5 degrees to each other, and
, 6, 7, 8, and 9.10 are connected in series in that order to form the winding of an autotransformer, and unit winding 6 and unit winding 7 are connected in series. When the tap T is drawn out from between the windings and a voltage is applied between the winding ends T1 and T2 of the winding 52, the current of the unit windings 6 and 7 placed between the tap T is The directions are opposite to each other, and an excessive current flows through the unit winding 6°7. Now, when the sum of the currents flowing through unit windings 9 and 10 is, for example, 1000 A, 280 OA flows through unit winding 7, and 1800 A flows through unit winding 8, and between these unit windings 7 and 8. A circulating current is generated. On the other hand, the unit winding is 5.6! The sum of the currents flowing in this case is 1500 A, but the unit winding 6 has 270 OA.
Alternatively, 120 OA flows through the unit winding 5, and a circulating current is generated between the unit windings 5 and 6. And, the power remains on for a long time! ! If this continues, there is a risk that the unit windings 6 and 7, through which excessive current flows, will be burnt out.

Therefore, in general, measures are taken to increase the conductor cross-sectional area of the unit winding, or to connect the unit windings in parallel if the shape is limited.

Alternatively, as in the voltage device of a flash hat welding device shown in Japanese Patent Publication No. 2-18194Q, multiple taps provided on the high-voltage side tertiary winding of a power transformer connected to a welding transformer can be switched. There is a method of obtaining a predetermined welding voltage in this manner and not using an autotransformer.

3. Problems to be Solved by the Invention However, even if the cross-sectional area of the conductor of the unit winding is increased, no significant improvement can be expected because the cause of abnormal heating is due to electromagnetic induction. Furthermore, if another unit winding is connected in parallel with another unit winding, there is a problem that circulating current may flow further, which may even promote heating. On the other hand, the electric power device disclosed in the above-mentioned publication S requires a power transformer with a tertiary winding, resulting in a large size and high cost.

In view of this problem, it is an object of the present invention to provide an autotransformer in which the unit winding closest to the tap does not become abnormally heated even when a large load current is applied.

Means for Solving Problem C] The autotransformer according to the present invention connects in series a plurality of unit windings wound around an iron core of a closed magnetic circuit, and a connecting part for connecting the unit windings to each other. In an autotransformer whose taps are derived from a single winding, a leakage magnetic path body for passing the leakage magnetic flux of the unit winding is provided near the unit winding in which the current direction of the adjacent unit winding is different. Features.

[Effect]

The autotransformer of the present invention excites the iron core when current flows through each unit winding. Leakage magnetic flux generated by adjacent unit windings having different current directions flows into a leakage magnetic path body provided to pass the leakage magnetic flux. Thereby, the current in the unit windings does not increase due to electromagnetic induction due to leakage magnetic flux of those unit windings.

Therefore, adjacent unit windings in the vicinity where the current directions are different from each other will not experience an abnormal temperature rise.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

FIG. 1 is a schematic perspective view of an autotransformer according to the present invention. The iron core 11 has a main leg portion 11a and a side leg portion 11b.

11b and yoke parts 11c and llc, it has a closed magnetic circuit structure. Unit windings 1, 2, 3, . . . , 10 are wound around the crown leg portion 11a in that order at predetermined distances apart. These unit windings 1, 2, 3...1
0, as shown in FIG. 3, unit winding L 2, 3
, 4 spaces, 5 and 6 spaces, 7 and 8 spaces, and 9 degrees are connected in parallel, and each circuit connected in parallel is connected in series in that order, thereby making a single winding. It makes up the windings of a transformer. A tap T is derived from the connection between the unit windings 6 and 7. One common connection part of the unit windings 1 and 2 is one winding end T1 of the winding of the autotransformer, and one common connection part of the unit winding 9.10 is the winding end T1 of the winding of the autotransformer. This is the other side winding end T2. Each of the unit windings 6 and 7 has a cross section and a leakage magnetic path body 12.12 that covers the side surface and outer peripheral surface of the unit winding 6.7. They are placed over each other separately.

The leakage magnetic path bodies 12.12 are both made of magnetic material, have the same size and shape, and have a length equal to that of the side leg portion 11b of the iron core 11.
, llb, and its height is such that when it is placed over the unit windings 6 and 7, it does not come into contact with the unit windings 6 and 7, and its lower end surface or main leg portion 11a directly The dimensions are such that they do not touch each other. And these leakage magnetic path bodies 12,
12: Two parts are disposed above the main leg part 1ia in an insulated state through a non-magnetic material (not shown). These iron core 11, unit windings 1, 2, 3... 10, and leakage magnetic path body 1
2.12 constitute an autotransformer.

In the transformer configured in this way, a load (not shown) is connected between the tap T and the winding end T1, and a load (not shown) is connected between the tap T and the winding end T1.
The iron core 11 is excited by applying a power supply voltage between + and Tz, and a voltage proportional to the voltage between the winding ends 'r, T2 is induced between the tap T and the winding end T1. do,
Supply current to the load.

In other words, an exciting current flows from the unit winding 7 on one side of the tap T toward the unit winding 6 on the other side, and from the unit winding 6 to the tap T so as to cancel the exciting current.
A load current flows toward the load connected to the tap T. The current direction of the unit winding 6 on one side and the current direction of the unit winding 7 on the other side are opposite with respect to the tap T, and between the unit windings 6 and 7 on both sides of the tap T. , the leakage magnetic fluxes generated by the unit windings 6 and 7 are added to each other, and the leakage flux between the unit windings 6 and 7 is increased. The magnetic flux density becomes excessive. Then, the current in the unit winding 6.7 tends to increase due to electromagnetic induction due to the leakage magnetic flux. However, the leakage magnetic flux flows into the leakage magnetic path body 12.12, so that the leakage magnetic flux due to the unit winding vA6 and the leakage magnetic flux due to the unit winding 7 do not influence each other. As a result, the current in the unit winding 6.7 does not increase, there is no difference between the current in the unit winding 5.6 and the current in each of the unit windings 7 and 8, and no circulating current occurs in each parallel circuit. . Therefore, even if the load current increases, the unit windings 6 and 7 will not be abnormally heated due to the circulating current, and the temperature of the unit windings 6 and 7 closest to the tap T can be maintained at an allowable temperature.

FIG. 2 is a temperature curve diagram illustrating winding temperature changes of unit windings 6 and 7 of a conventional autotransformer and a single-turning transformer of the present invention in comparison with measured values. The solid line shows the temperature change in the case of the conventional autotransformer, and the broken line shows the temperature change in the case of the autotransformer of the present invention.

In this case, the actual measured values are shown when the primary current is approximately 1500 A, the secondary current is approximately 2500 A, and the energization time is 60 seconds. As is clear from this figure, in both the conventional autotransformer and the present invention, after the unit windings 6 and 7 are energized, the winding temperature of each of the unit windings 6 and 7 rises rapidly. In the case of a conventional autotransformer, the winding temperature rises to 75°C.

On the other hand, in the case of the transformer of the present invention, it was confirmed that the temperature did not rise above 50°C. As a result, it has been found that according to the present invention, the unit winding 6.7 closest to the tap can be prevented from being abnormally heated and burnt out.

In addition, as shown in FIG. 3, the above-mentioned autotransformer has unit windings 1, 2.3, . 10 to the winding end T,
T2 is derived, and the tap T is derived from between the vertical windings vA6 and 7. The winding ends Tz, T1 are derived from the unit windings 4 and 5 located between the unit windings vA1.2゜3-...10, and the tap T is drawn from the connection between the unit windings 1 and 10. In the derived autotransformer: the current directions of the adjacent unit windings 4.5 are different from each other. Therefore, the second unit of the transformer is: the winding end T2. If a leakage magnetic path body 12.12 is provided in each of the unit windings 4.5 where T is derived from 2, abnormal heating of the unit windings 4.5 can be prevented in the same manner as described above, and its burnout can be prevented. It can be prevented.

〔Effect of the invention〕

As detailed above, according to the present invention, a leakage magnetic path body is provided in the vicinity of the unit windings in which the current direction is different, so that these unit windings are not subjected to electromagnetic induction due to the leakage magnetic flux. Even if the load current is increased, the temperature rise of the unit winding can be significantly suppressed. Therefore, even if this autotransformer is used as a power source for a flash hat welding device that repeatedly passes large currents intermittently, such as when performing flash hat welding, adjacent unit windings with different current directions will be kept at the permissible temperature. It can be maintained within the range and prevent burnout. There is no need for an increase in size or an increase in equipment costs, unlike in the case of using a double-insulated transformer. Therefore, the present invention has the excellent effect of providing a small and inexpensive transformer suitable for the power source of a flash hat welding device and whose windings are not burnt out.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic perspective view of an autotransformer according to the present invention, and FIG.
The figure is a temperature curve diagram showing the actual measurement of the winding temperature change, Figure 3 is a connection diagram showing the connection state of the windings of an autotransformer, and Figure 4 is a diagram showing other connection states of the windings of the autotransformer. FIG. 1.2.3...10...Unit winding 11...Iron core 11a...Main leg portion 11b...Side leg portion 11c...
・Yoke part 12...Leakage magnetic path body

Claims (1)

[Claims] 1. In an autotransformer, in which multiple unit windings wound around a closed magnetic circuit iron core are connected in series, and taps are derived from the joints that connect the unit windings to each other, adjacent unit windings are connected in series. 1. An autotransformer characterized in that a leakage magnetic path body for passing leakage magnetic flux of the unit winding is provided near the unit winding in which the current directions of the unit windings are different.