Energy saving transformer – amorphous alloy transformer

Amorphous alloy transformer is a kind of energy-saving transformer developed in the 1970s, the world’s earliest development of amorphous alloy transformer country is the United States, at that time by the United States General Electric (GE) company undertook the development of amorphous alloy transformer project. Commercial production was achieved by the end of the 1980s. Due to the use of a new soft magnetic material – amorphous alloy, the performance of amorphous alloy transformers beyond all kinds of silicon steel transformers.

Let’s start with amorphous materials. In daily life, there are generally two kinds of materials that people come into contact with: one is a crystalline material, and the other is an amorphous material. The so-called crystalline material means that the atomic arrangement inside the material follows a certain law. On the contrary, the internal atomic arrangement is in an irregular state, it is an amorphous material, and the general metal, whose internal atoms are arranged in order, belongs to the crystalline material. Scientists found that after the metal is melted, the internal atoms are active. Once the metal begins to cool, the atoms will slowly arrange themselves in an orderly manner according to certain crystalline laws as the temperature drops, forming crystals. If the cooling process is fast, the atoms are solidified before they can be rearranged, resulting in an amorphous alloy, which is prepared using a rapid solidification process. The high-temperature liquid in the molten state is sprayed onto a cooling roller rotating at high speed. The alloy liquid cools rapidly at a rate of millions of degrees per second, bringing the alloy liquid at 1300 ° C to room temperature in just one thousandth of a second to form an amorphous strip.

The physical, chemical and mechanical properties of amorphous alloys have changed significantly compared with those of crystalline alloys. Taking Fe-base amorphous alloy as an example, it has the characteristics of high saturation magnetic induction and low loss. Due to such characteristics, amorphous alloy materials have broad application space in many fields such as electronics, aviation, aerospace, machinery, microelectronics and so on. For example, in the aerospace field, it can reduce the power supply, equipment weight, and increase the payload. For civil power, electronic equipment, can greatly reduce the volume of power supply, improve efficiency, enhance anti-interference ability. Microcores can be widely used in transformers in ISDN. Amorphous strips are used to make sensor tags for anti-theft systems in supermarkets and libraries. The magical effect of amorphous alloy has broad market prospects.

After having a preliminary understanding of amorphous materials, let’s take a look at a very promising application area of amorphous strip – amorphous transformers. Amorphous alloy core transformer is a new type of magnetic conductive material – amorphous alloy made of iron core of the transformer, it than silicon steel sheet as a core transformer no-load loss (refers to the transformer secondary open circuit, in the primary measured power loss) decreased by about 50%, no-load current (transformer secondary open circuit, the primary still has a certain current, This part of the current is called no-load current) decreases by about 55%, which is a distribution transformer with ideal energy-saving effect at present, especially suitable for rural power grids and developing areas where the utilization rate of distribution transformer is low.

The biggest advantage of amorphous alloy core distribution transformers is that the no-load loss value is extremely low. Whether the final no-load loss value can be ensured is the core issue to be considered in the whole design process. When the product structure is arranged, in addition to considering the non-external force of the amorphous alloy core itself, the characteristic parameters of the amorphous alloy must be selected accurately and reasonably during calculation. In addition to the design ideas, the following three requirements must be followed:

(1) Due to the low saturation magnetic density of amorphous alloy materials, the rated magnetic flux density should not be selected too high in the product design, usually select 1.3 ~ 1.35T magnetic flux density can obtain a better no-load loss value.

(2) The single thickness of the amorphous alloy material is only 0.03mm, so the lamination coefficient can only reach 82% to 86%.

(3) In order to enable users to obtain the benefits of maintenance-free or less maintenance, the products of amorphous alloy distribution transformers are designed with a fully sealed structure.

Structure characteristics of transformer amorphous alloy

By using the amorphous alloy with outstanding magnetic permeability, it can be used as the core material of transformer, and the loss value can be very low. However, it has many characteristics, which must be guaranteed and considered in design and manufacturing. The main body reflects the following aspects:

(1) The hardness of amorphous alloy sheet material is very high, and it is difficult to cut with conventional tools, so the design should consider reducing the shear amount.

(2) The single sheet thickness of amorphous alloy is extremely thin, and the surface of the material is not very flat, so the core filling coefficient is low.

(3) Amorphous alloys are very sensitive to mechanical stress. In the structural design, the traditional design scheme with iron core as the main bearing structure must be avoided.

(4) In order to obtain excellent low loss characteristics, amorphous alloy iron chips must be annealed.

(5) From the electrical performance. In order to reduce the shear amount of the iron chip, the iron core of the whole product is composed of four separate iron core frames, and each phase winding is set on two independent frames of the magnetic circuit. In addition to fundamental magnetic flux, there are three harmonic magnetic flux in each frame, and the third harmonic magnetic flux in two coil core frames in a winding is exactly opposite in phase and equal in value, so the third harmonic magnetic flux in each set of winding is zero. If the first side is a D connection, there is a third harmonic current loop, when the induced second side voltage waveform, there will be no third harmonic voltage component.

According to the above analysis, the most reasonable structure of the three-phase amorphous alloy distribution transformer is: the iron core, composed of four separate iron core frames in the same plane, three-phase five-column type, must be annealed, and has a cross iron yoke joint, and the cross-section shape is rectangular. The winding, rectangular section, can be individually wound into a type, double or multi-layer rectangular layer type. The tank is a fully sealed, maintenance-free corrugated structure.

In the face of the current predicament of serious overcapacity in the traditional transformer industry, the state encourages the development of energy-saving and intelligent distribution transformer products. For energy-saving transformers, it is a good news, but in addition to the technical bottleneck, the fundamental reason for energy-saving transformers is that the price is too high and the cost is too large. Whether it is manufacturing enterprises or users, it is difficult to digest.

With the deepening of China’s energy-saving and consumption reduction policies, the state encourages the development of energy-saving, low-noise, intelligent distribution transformer products. High energy consumption distribution transformers are facing the demand for technological upgrading and upgrading, and will be gradually replaced by energy-saving, material saving, environmental protection and low noise transformers in the future.