Comparison and Fabrication of Power Transformers

1 What are the advantages and disadvantages of machine winding and manual winding in the manufacture of transformer?The advantages of machine wound transformer are high efficiency and beautiful appearance, but winding the ring transformer with tall and small holes is more troublesome, and it is not as reliable as manual winding in terms of insulation treatment process. Manual winding can make the magnetic leakage of the transformer very small. During the winding process, it can be adjusted at any time according to the layout of coil turns. Therefore, the real hi-end transformer must be wound purely manually. The only disadvantage of pure manual winding is low efficiency and slow speed.2 Which of the ring type, EI type, R type and C type power transformers is the best?

They have their own advantages and disadvantages, and there is no saying who is the best, so strictly speaking, any kind of transformer can be done best. In terms of structure, the ring type can minimize the magnetic flux leakage, but the EI type can do better in the sense of intermediate frequency density. In terms of magnetic saturation alone, the EI type is stronger than the ring type, but the ring type is better than the EI type in efficiency. Nevertheless, the key to the problem is whether you can give full play to their respective advantages, which is the most fundamental to do a good job of transformer.

In the current imported amplifiers, the application of ring transformer is still the mainstream, which basically explains a problem. Enthusiasts should be objective and fair about the * price of transformers. You can't refer to something that isn't done well and say it's bad. Some people say that the ring transformer is easy to magnetic saturation, so why don't you find a way to make it not easy to magnetic saturation? This could have been achieved by technical means. Without enough effort or blindly in order to save cost, it is of course prone to magnetic saturation. Similarly, as long as you make it carefully, the efficiency of EI transformer can be very high.

The quality of the transformer has a great impact on the sound, because the transmission energy of the transformer is closely related to the iron core and coil, and its transmission rate plays a decisive role in the influence of the sound. Like EI transformer, people usually think its medium frequency is thicker and high frequency is thinner. Why? Because its transmission speed is relatively slow. And the ring? The low frequency is relatively fierce, while the medium and high frequency are slightly weaker. Why? Because its transmission speed is relatively fast, but if you can make the ring type and EI type perfect through effective structural changes, the key depends on what you do.

However, at least one thing is certain that R-type transformer is not easy to do well. It can be used as the power supply of low current front-stage power amplifier and CD player. If it is used as the power supply of rear-stage power amplifier, it has serious defects. Because the structural form of R-type transformer itself is not easy to change, while ring type and EI type are relatively easy to achieve the purpose of beautiful sound by changing the structure. The power amplifier power supply made of R-type transformer usually has a hard sound and lacks aura, and the low-frequency power amplifier is often hard without bouncing force.

III. is the greater the silicon content of silicon steel sheet of transformer core, the better?It has not been found that the silicon content of silicon steel sheet has little effect on the quality of transformer, while the oriented and non oriented are related to the model of iron core. Secondly, even if the iron core of the same model is not handled well, the quality difference is also very large, and sometimes the difference is as high as 40% or 50%.For a good iron core and the same material, the heat treatment and wire winding process are very key. A good heat treatment only needs a small 10mA excitation current to reach 15000 Gauss, while a bad heat treatment may need 50mA excitation current to reach the corresponding 15000 Gauss. There is a great difference between the two. Judging whether the iron core is good or not from a professional point of view is mainly through several indicators such as excitation current, iron loss and saturation parameters.

IV. if the splicing process is adopted for the belt silicon steel sheet of the ring transformer, does it mean that the quality is certainly not good?It can not be generalized, but it is not easy to splice too many broken heads, because one more broken position will have one more magnetic flux leakage point, so it is best not to have more than 2-3 joint points. In terms of manufacturing process, all broken ends and splices shall be pickled first, but for the ring transformer manufacturing high-grade audio equipment, strictly speaking, it is best to use silicon steel without splicing, and its process quality will be more guaranteed.V. what is particular about the silicon steel sheet material in the transformer?

Because the loss of silicon steel in alternating magnetic field is very small, silicon steel sheet is mainly used as magnetic material in transformers. Silicon steel sheet can be divided into hot rolling and cold rolling. Cold rolled silicon steel strip has the advantages of small volume, light weight and high efficiency because of its high magnetic conductivity and low loss. The performance of hot rolled silicon steel strip is slightly inferior to that of cold rolled silicon steel strip.Common EI type transformers are made of silicon steel plate into E-type and I-type sheets with a thickness of 0.35-0.5mm, which are inserted into the winding package after heat treatment. Most of these iron cores use hot-rolled silicon steel sheets (the models of high-quality silicon steel sheets with high silicon content are d41, d42, d43 and D301). The iron core of ring and C-type transformers is formed by winding cold-rolled silicon steel strip. The C-type transformer is cut after heat treatment and paint dipping.The leakage inductance of the transformer is generated by the magnetic flux that does not pass through the primary and secondary coils. These magnetic fluxes pass through the air and form a closed magnetic circuit. The leakage inductance can be reduced by enhancing the coupling density between the primary and secondary of the transformer. The leakage inductance of a good transformer shall not exceed 1 / 100 of the primary coil inductance, and that of a high fidelity hi fi output transformer shall not exceed 1 / 500.