Transformer is the use of electromagnetic induction principle to change the AC voltage device, refers to the online coil original edge winding and alternating voltage generated alternating flux, in the side winding inductance output voltage, so as to transmit energy, conversion voltage or signal electrical insulation isolation role. Transformers are used in electronic circuits and electronic devices as electronic transformers. High frequency electronic transformers are electronic transformers that work at frequencies higher than 20kHz. Why choose 20kHz as the limit? Because, 20kHz is the audio ceiling, more than it can not hear audible noise.
Current power products, generally with "light, thin, short, small" as the characteristics of miniaturization and portability development. Electronic transformers must be adapted to the volume and weight requirements of the power products of the user. At the same time, high-frequency electronic transformer's biggest characteristic is the high-frequency. From the principle of transformer working, it can reduce the size and weight of the transformer, realize the short and thin, and improve the unit volume or weight transmission power, high power density. Also, the price of raw material and conductive material of the electronic transformer increases. Therefore, electronic transformers need to reduce the volume and weight of light, in order to reduce costs and improve weight transmission power better development.
How to travel light in the development of the road, there are three points can be used for reference:
Overall structure optimization
In order to adapt to electronic equipment more and more frivolous and short, high-frequency electronic transformers from the three-dimensional structure to the plane structure, sheet-type structure, film structure development, thus forming a generation after generation of new High-frequency electronic transformers. For example: Planar transformers, Chip transformers, thin-film transformers. In the design aspect, we should study the electromagnetic field distribution of various new structures, how to achieve optimal optimization design, but also to study the various problems of multi-layer structure, in the production process, to study a variety of new processing methods, so as to ensure the consistency of performance and the realization of the mechanization and automation of processing technology, and also to explore the structure of hollow transformers, design methods, Manufacturing process and application characteristics. Using the computer to optimize and design the whole structure scheme, this can shorten the design time, reduce the material dosage, shorten the production cycle and reduce the cost.
II. Reducing the cost of core materials
The core is the most critical component in High-frequency electronic transformers working in the principle of electromagnetic induction. The main development direction of the core material is to reduce the loss, widen the temperature range and reduce the cost.
Soft Ferrite is now the main magnetic core material used in high-frequency electronic transformers, the development direction is to develop new varieties of better performance and reduce costs of new technology. Compared with the traditional soft magnetic ferrite and soft magnetic alloy, it can be distributed in the non conductor and other materials, so that the high-frequency loss is obviously reduced and the operating frequency is increased. Processing technology can be used hot pressing process into powder core, can also use the present plastic engineering technology, injection into complex shape of the core, with a small density, light weight, high production efficiency, low cost, product repeatability and consistency of good characteristics. can also use different ratios to change the magnetic. The example of composite materials composed of soft ferrite and Poe has been developed, and a soft magnetic composite powder core with more than 10kHz working frequency is now available, which can be used in the High-frequency filter inductor instead of the soft ferrite body.
According to the development requirement of the whole structure of high frequency electronic transformer, the development direction of the core structure is planar core, chip core and thin film core. The planar core has previously been modified with the original soft ferrite core, and now has a variety of low altitude soft ferrite cores specially used in planar transformers. In the future, a variety of low and high soft magnetic composite cores may be developed. In addition to the magnetic core of the chip transformer, there are also the chip cores made by the common firing method.
III. Development of Coil structure
The main development direction of the coil structure is the planar coil, the chip coil and the film coil.
The three-dimensional structure of high-frequency transformer coil, wire material considering the skin effect and the proximity effect of the use of stranded strands, and sometimes the use of flat copper wire and bronze belt. Insulating material with high heat-resistant grade material, in order to increase the allowable temperature rise and reduce coil volume, the use of double-layer and three-layer insulated wire, reduce the coil size. has developed a nano-technology to the mica swimming on the copper wire on the C-class insulated electromagnetic wire, has been in the power frequency motor and transformer applications, has achieved good results, estimation in High-frequency electronic transformers will also be applied.
The planar structure coil uses the copper foil wire, most uses the Single-layer and multilayer printed circuit board manufacture, also has uses the certain shape the copper foil, many folds. Insulating materials generally use B-class materials.
The membrane structure coil, the wire uses the copper, the silver and the gold thin film, makes the comb shape, the spiral shape, the sports field shape and so on the shape, the insulating material uses the H class and the C class material. The multi-layer structure or several multi-layer coils are combined, or several coils and several cores overlap.
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