JPH04155907A - Transformer - Google Patents

Abstract

PURPOSE:To hold down a copper loss for preventing a temperature rise in a transformer by using a short copper wire which has a large cross section for primary and secondary coils which are wound around an amorphous metal- made core having a relatively large cross sectional magnetic path. CONSTITUTION:A transformer 10, being formed of amorphous metal, has a shell-type single-phase core 12 which has a relatively large cross sectional magnetic path. Primary coils 16a and 16b which are wound around a core 12 are connected in parallel and are located alternately in lamination with the winding of each layer of a secondary coil 18 put between the windings of each layer of the primary coils 16a and 16b. A voltage allotted to each turn (V/T) is set large and a cross section of a copper wire used for the primary coils 16 and 16b and secondary coils 18 is 1.5 times the conventional one. Therefore, the number of turns can be reduced to 1/1.5 or smaller. Consequently, a coil resistance is reduced to 1/5 or lower of the conventional one, being followed by the reduction of a copper loss to nearly 1/3 to 1/5 of the conventional one. As a result, an efficiency can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transformer, and particularly to a transformer used for example in a power supply circuit of electronic equipment or in power transmission and distribution.

(Prior Art) As a conventional general transformer, there is a transformer 1 shown in Fig. 4.In general, the transformer 1 is designed so that iron loss and copper loss are approximately equal in order to maximize efficiency. That is, the transformer 1 is designed by sequentially winding a large number of turns of a primary winding 3 and a secondary winding 4 around a core 2 made of a silicon steel plate, so that the shared voltage ( V/T) is designed to be relatively small.Specifically, at 6.6kV/220V, 10
In a kVA pole transformer, as shown in the attached table, the cross-sectional area of the core 2 is 70C11", the cross-sectional area of the copper wire used for the primary winding 3 is 1.3 m+", and the cross-sectional area of the secondary winding 4 is 70C11". The cross-sectional area of the copper wire used is 33×2, and the window size of core 2 is 3.
50 peng, and the shared voltage per turn is 2. O.V.
There was one designed in /T.

[Problem to be solved by the invention]

In the transformer 1 designed in this way, the winding resistance was relatively large, so the copper loss was large, and the temperature inside the transformer 1 increased significantly. For this reason, the structure of the transformer has become complicated and large, such as by providing heat radiation fins, in order to maintain reliability.

On the other hand, although it has recently been put into practical use to form a core using an amorphous metal to reduce iron loss, little consideration has been given to copper loss. Therefore, the use of amorphous metal cores in conventional transformers has not been very efficient.

Further, in the transformer 1, since the leakage inductance was also large, the voltage fluctuation rate was as large as 4 to 5%, together with the large winding resistance.

Therefore, the main objective of the present invention is to provide a transformer that can improve reliability and efficiency as well as improve voltage fluctuation rate.

[Means to solve the problem]

The present invention has a core formed of an amorphous metal with a relatively large magnetic path cross section, and a primary winding and a secondary winding each formed of a relatively thick and relatively short copper wire and wound around the core. It is a transformer with a wire.

[Effect]

Since copper wire with a large cross-sectional area is used for the primary winding and the secondary winding and the length thereof is short, the winding resistance and the copper loss caused by it are reduced. Furthermore, although the core is made of amorphous metal and the cross-sectional area of the magnetic path is made relatively large, iron loss is relatively reduced. Furthermore, when the secondary windings are alternately stacked so as to be sandwiched between the primary windings, the degree of magnetic coupling between the primary windings and the secondary windings can be increased, and leakage inductance can also be reduced.

〔Effect of the invention〕

According to this invention, since the winding resistance of the primary winding and the secondary winding can be reduced, heat generation in the windings, that is, copper loss, is also reduced, and efficiency is improved. Moreover, the temperature rise inside the transformer can be suppressed. Therefore, thermal deterioration of the transformer can be suppressed, and not only can improved reliability and longer lifespan be expected, but it can also be put to practical use even if the heat resistance of the insulation is lower than before.

In addition, not only copper loss but also iron loss can be reduced, resulting in a dramatic improvement in efficiency.

Furthermore, if the secondary windings are alternately stacked so as to be sandwiched between the primary windings, the leakage inductance is also reduced, which, together with the reduction in the winding resistance, can improve the voltage fluctuation rate.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

〔Example〕

Referring to FIG. 1, a transformer 10 of this embodiment includes an outer iron type single-phase core 12 formed of amorphous metal and having a relatively large magnetic path cross section.
14 includes two primary windings 1 each having a solenoid structure.
6a and 16b and one secondary winding 18 are wound thereon. That is, as can be seen from FIG. 2, the primary windings 16a, 16b wound around the core 12 are connected in parallel, and the degree of magnetic coupling between the primary windings 16a, 16b and the secondary winding 18 is The windings in each layer of the primary windings 16a and 16b are alternately stacked so as to sandwich the windings in each layer of the secondary winding 18.

What should be noted here is the shared voltage per turn (
V/T) and increase the primary winding 16a.

The cross-sectional area of the copper wire used for each of the coil 16b and the secondary winding 18 is 1.5 times or more larger than that of the conventional coil. Therefore, the number of turns can be reduced to 1/1.5 or less compared to the conventional one, so the winding resistance is reduced to 175 or less compared to the conventional one, and due to the reduction in the winding resistance, the copper loss is reduced to about 1/1/1 of the conventional one. 3-1
15, improving efficiency.

In addition, since copper loss can be significantly reduced in this way, the temperature rise inside the transformer 10 can be suppressed to 1/2 to 1/3 of the conventional temperature, suppressing thermal deterioration of the transformer 10, and improving the reliability of the transformer. It can be expected to improve performance and extend lifespan. At the same time, it becomes practical even if the heat resistance of the insulation is lower than before. Specifically, it is a resin mold that has traditionally been used in substations in basements.

In place of the urban disaster prevention type H class insulation transformer, transformer 1 of this case
0 can be insulated with a general insulating material. Further, it is not necessary to provide the transformer 10 with heat dissipation fins as in the conventional case, and the transformer can be made simple and compact.

What is further noteworthy is that the core 12 is made of Amo J Refus metal, and its magnetic path cross-sectional area is set to be relatively large, 1.5 times or more compared to the conventional one. As a result, the core 120 iron loss increases accordingly, but combined with the reduction in copper loss, the overall efficiency can be dramatically improved.

In this embodiment, the primary windings 16a and 16b are connected in parallel and alternately stacked. This results in 1
The leakage inductance of the secondary windings 15a, 16b and the secondary winding 18 can be reduced to 115 or less compared to the conventional one, and the winding resistance can be reduced (
The voltage fluctuation rate can be improved, and as shown by line A in FIG. 3, the voltage fluctuation rate can be reduced to 115 or less than the conventional value.

Incidentally, line B shows the conventional voltage fluctuation rate.

Here, the results of experiments conducted by the inventors on a 6.6 kV/220 V, 10 kVA pole transformer are shown in the attached table.

First, Experimental Example 1 in the middle column of the attached table will be compared with the conventional example in the left column. In Experimental Example 1, the cross-sectional area of the core 12 was 140CI'', and the cross-sectional area of the copper wire used for the primary windings 16a and 16b was 2.6 CI''.
The cross-sectional area of the copper wire used for the secondary winding 18 is 66 times larger than the conventional one, and the window size of the core 12 is set to 400 mm, which is larger than the conventional one. The shared voltage of 4. It is designed to be twice as OV/T as the conventional one.

As a result, compared to the conventional method, the winding resistance r can be reduced to 1/6, the copper loss Pc is reduced to 70 W (previously 270 W), and the iron loss Pi is reduced to 5
Since it can be reduced to 0W (conventionally 100W), the loss (=Pc
+Pi) can be reduced to 120W, approximately 1/3 of the conventional (370W).

In addition, the leakage reactance XL can be reduced to 1/8 of the conventional value, and combined with the reduction of the winding resistance r (1/6 of the conventional value), the voltage fluctuation rate is 0.9%, which is 115% compared to the conventional (4.5%). It can be improved.

Next, Experimental Example 2 on the right side of the attached table will be compared with the conventional example on the left side. In Experimental Example 2, the cross-sectional areas of the copper wires used for the primary windings 16a, 16b and the secondary winding 18 were the same as in Experimental Example 1, and the cross-sectional area of the core 12 was made thicker to 210 cm.
In addition, the window size of the core 12 has been set even larger to 500 mm, and the shared voltage per turn of the winding has been designed to be 6° OV/T, three times the conventional size.

As a result, the winding resistance r can be reduced to 1/11 compared to the conventional one, the copper loss Pc can be reduced to 45 W, and the iron loss Pi can be reduced to 75 W, so that the loss can be reduced to 120 W, which is about 1/3 of the conventional one. Furthermore, the leakage reactance XL can be reduced to 1/14 of the conventional value, and combined with the reduction of the winding resistance r (1/11 of the conventional value), the voltage fluctuation rate can be improved to 0.5%, 1/9 of the conventional value.

Note that the primary windings 16a and 16b are not limited to being connected in parallel, but may be connected in series depending on the required current capacity and voltage. Each connection may be made in series and parallel. Further, the dimensions of each component may be changed as appropriate depending on the use and specifications of the transformer.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an embodiment of the present invention. FIG. 2 is a circuit diagram showing an equivalent circuit of the embodiment shown in FIG. FIG. 3 is a graph showing the voltage fluctuation rate in comparison with the conventional method. FIG. 4 is a front sectional view showing the prior art. In the figure, 10 is a transformer, 12 is a core, 16a, 16
b indicates the primary winding, and 18 indicates the secondary winding. Patent Applicant Murata Manufacturing Co., Ltd. Representative Patent Attorney Yama 1) Legal Person Table 1 Figure 2

Claims (1)

[Scope of Claims] 1. A core formed of amorphous metal and having a relatively large magnetic path cross-sectional area, and a primary winding each formed of a relatively thick and relatively short copper wire and wound around the core. and a secondary winding. 2. The primary winding and the secondary winding are each formed of a plurality of layers, and the windings in each layer of the primary winding sandwich the windings in each layer of the secondary winding. The transformer according to claim 1.