JPH03217008A - Multiphase transformer - Google Patents

Abstract

PURPOSE:To obtain a transformer which can help a countermeasure to DC deviated magnetism readily without the increase in no-load loss and noises by providing a constitution wherein an iron core having (n) pieces of main legs and one or more side legs is used, a magnetism detecting means for detecting the increase in magnetic flux of the side leg is provided, and the increase in DC deviation of magnetism is detected with the detecting means. CONSTITUTION:An iron core 1 has (n) pieces of main legs 1U-1W with a natural number of 3 or more as (n) and at least one side leg 1C. Main windings 2U-2W including the primary windings and the secondary windings are wound around the main legs 1U-1W. A magnetism detecting means 3 detects the increase in magnetic flux of the side leg 1C. On the primary sides of the main windings 2U-2W, an (n)-phase balanced voltage is applied, and the (n)-phase balanced voltage is taken out of the secondary side. At the same time, the increase in DC deviation of magnetism in the iron core 1 is detected. For example, the detecting winding 3 is wound around the side leg 1C as a magnetism detecting means. When the voltage higher than a specified value is generated in the detecting winding 3, the loaded state is corrected because the DC deviation of the magnetism is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a polyphase transformer that transforms a polyphase balanced voltage.

(Prior Art) As three-phase transformers for transforming three-phase AC voltage, there are, for example, those using a core type three-phase three-leg iron core and those using a core type three-phase five-leg iron core. Among these cores, three main legs are equipped with a primary winding and a secondary winding.

Although it is desirable for this type of transformer to be used without causing DC bias, DC bias is likely to occur when applied to a three-phase inverter or the like.

Therefore, a gap is provided between each main leg to prevent direct current bias from occurring.

(Problems to be Solved by the Invention) The above-mentioned conventional three-phase transformer has the problem of large no-load loss and large noise due to the provision of a gap.

Normally, DC bias in a transformer may have to be suppressed due to the nature of the circuit, but if DC bias increases, measures should be taken to promptly reduce this DC bias. often yields the same results.

The present invention has been made to solve the above problems, and its purpose is to provide a polyphase transformer that can easily take measures against DC bias without increasing no-load loss or noise. do.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an iron core having n main legs and at least one side leg, where n is a natural number of 3 or more; A main winding that is wound and includes a primary winding and a secondary winding, and magnetic detection means that detects an increase in the magnetic flux of the side leg, and an n-phase balanced winding on the primary side of the main winding. A voltage is applied, an n-phase balanced voltage is extracted from the secondary side, and an increase in direct current bias magnetization of the iron core is detected by the magnetic detection means.

(Function) In this invention, the balanced voltage of n phase is targeted.
If an iron core is used that has at least one side leg in addition to the main legs, this technique cleverly takes advantage of the phenomenon that the magnetic flux of the side legs increases or decreases in accordance with the increase or decrease in DC bias magnetization. Measures against DC bias can be easily taken without increasing load loss or noise.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

The figure is a schematic configuration diagram of an embodiment of the present invention, and particularly illustrates a three-phase transformer that transforms a Sanwa AC voltage. In the figure, an iron core 1 is connected to main landing gears IU, IV, which are magnetically coupled by yokes IA, IB. Equipped with IW and side leg IC. Among these, main landing gears IU, IV, and IW include main windings 2U, 2V, and 2V, which include a primary winding and a secondary winding.
2W is wound around the side leg IC, and a detection winding 3 is wound around the side leg IC as a magnetic detection means.

Here, the magnetic flux of the main landing gear IU, IV, and IW due to the supply of a balanced current to a load (not shown) is expressed as a small U(1),
.about.(t) and .about.(1), these have the following relationship.

Small U(1)-φsin ωt Small V(t)-φsin (ωt −2/3) −(
1) Small v(1) -φsin (ωt -2/3) And, if the difference in the length of the magnetic path is ignored, the sum of the magnetic fluxes passing through the yokes IA and IB is small. (1) is small. (1) One small U (1) ten small v (t) ten small w (t) ten... (2
).

On the other hand, when DC bias occurs due to changes in load conditions, φ. (1) Ki0 ... (3) This magnetic flux Φ. <1) passes through the side leg 1c and the detection winding 3
generates a voltage. If the induced voltage of this detection winding 3 is ■, then V-d is small. (L)/dt...(4)
becomes.

In this way, if the load condition is corrected as if the DC bias magnetization has increased when a voltage higher than a predetermined value is generated in the detection winding 3, this is the same as making it difficult for DC bias magnetization to occur. Get results.

In the above embodiment, the detection winding 3 is wound around the side leg IC, and the increase in DC bias magnetization is detected from the voltage. However, even if a Hall element is used instead to detect the magnetic flux, the same effect as described above can be achieved. Similarly, an increase in DC bias can be determined.

Furthermore, in the above embodiment, a Sanwa transformer intended for Sanwa AC was explained, but the present invention can also be applied to a transformer intended for balanced voltage of 4 or more phases, such as 6-phase or 12-phase. I can do it.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, n
An iron core having n main legs and at least one side leg, and a main winding each wound around the main legs and including a primary winding and a secondary winding, for the balanced voltage of the phase. The magnetic detection means detects an increase in the magnetic flux of the side legs, and the magnetic detection means detects an increase in DC bias magnetization of the iron core. Countermeasures can be taken against biased magnetism.

6

[Brief explanation of drawings]

The figure is a schematic diagram of an embodiment of the present invention. 1... Iron core, 1. A, IB--Yoke, IU, I
V, IW...Main landing gear, IC...Side landing gear, 2U, 2V, 2
W...Main winding, 3...Detection winding.

Claims (1)

[Claims] An iron core having n main legs and at least one side leg, where n is a natural number of 3 or more, and a main winding that is wound around each of the main legs and includes a primary winding and a secondary winding. , magnetic detection means for detecting an increase in the magnetic flux of the side leg, applying an n-phase balanced voltage to the primary side of the main winding, extracting the n-phase balanced voltage from the secondary side, and A multiphase transformer, characterized in that an increase in direct current bias magnetization of the iron core is detected by means.