What problems exist in the application of nanocrystalline materials
In the process of applying nanocrystalline materials to inverter power supply, there have been some problems such as noise, brittleness, consistency, etc., which have an impact on the promotion and application to a certain extent and have attracted attention. Now summarize the causes and solutions of these problems. 1. Noise problem
There are many reasons for the formation of noise:
1. The reason for the magnetostriction coefficient of the material itself The magnetostriction coefficient of the ferrite material is relatively large, although the ferrite core is solid, noise sometimes occurs in use. The composition of nanocrystals is different, and the magnetostriction coefficient is different. The composition used in the past few years is a general alloy composition, so the noise problem of the transformer is more prominent. Uses Different alloy compositions are used to meet the special magnetic requirements of different devices. For example, special components have been developed as power output transformers, current transformers, common mode inductors, etc. The alloy composition adjusted according to the requirements of the power transformer reduces the magnetostrictive coefficient, and the noise problem has been greatly improved by the user's use.
2. Reasons for the tightness of the iron core winding This has a lot to do with the quality of the strip used. The deviation of the strip size and the uneven thickness will cause the iron core to not be wound tightly, which is prone to noise. After adjusting the composition, the molten steel has good fluidity, which is beneficial to the forming quality of the strip, and provides a favorable guarantee for reducing the noise of the iron core to a certain extent.
3. Problems in the inverter circuit The DC component in the circuit is large, which increases the working magnetic induction of the iron core and causes noise. Our experiments show that the noise increases with the increase of the working magnetic induction. Some manufacturers have taken DC blocking measures on the circuit, and there have been no noise problems for many years using nanocrystalline iron cores. Through the above improvements, the noise problem has been basically solved.
2. Brittleness problem The brittleness of the nanocrystalline iron core is mainly reflected in the slag loss of the iron core, which is the biggest problem reported by users. After years of practice and research, the brittleness problem has been greatly improved by adjusting the composition and process. After the adjustment of the composition, the flexibility of the strips was significantly improved. The reduction in strip thickness also reduces brittleness. In addition, in the process of manufacturing the iron core, the iron core is impregnated with stress-free glue, so that the iron core is not easily broken, and the brittleness problem of the slag drop of the iron core is completely solved. At the same time, because the stress-free glue fixes the layer gap of the iron core strip, it is not easy to generate resonance, and the generation of noise is reduced.
3. Consistency issues Consistency is related to the scale of production and the capacity of production equipment. From the point of view of the quality of the strip, a 500 kg production equipment is compared with a 50 kg production equipment, which also produces 500 kg of strip. Obviously, the consistency of the former product in terms of composition and magnetic properties is better than the latter. The same is true for the heat treatment during the production process. Therefore, large production scale and large capacity of production equipment are beneficial to consistency. The consistency of nanocrystals is mainly reflected in the large dispersion of saturation voltage and inductance in the user's use, and sometimes the difference is more than doubled. The main reason is that the effect of magnetic field heat treatment is poor, and the production inspection is not classified and screened. With the adjustment of the composition used for the power transformer, not only the brittleness is improved, but also the residual magnetic induction intensity of the material is reduced, therefore, the effect of the magnetic field heat treatment is increased, the saturation voltage of the iron core is increased, and it plays an important role in the product consistency. . There is a step-by-step process of understanding the magnetic properties required by the inverter power supply. In the past few years, due to the small amount of use, it is only necessary to emphasize the loss to meet the requirements. Therefore, the performance test only measures the loss as a parameter. For specific users, increase the test induced voltage value. With the increasing number of applications, various requirements are put forward, especially the requirements of performance consistency are particularly prominent. Since there is a recognition process for this requirement, there is some lag in terms of ingredient improvement, production organization, testing standards, etc. Therefore, it has a certain impact on the promotion and application. Now that the problem has been sufficiently recognized and a variety of effective measures have been taken, the consistency has been greatly improved.
4. The price issue The price issue is what users are most concerned about, especially those who are ready to use or just starting to use it. The price is directly related to the production volume. In recent years, as the application of nanocrystalline iron cores has become more and more extensive, it is not only used in inverter welding machines, but also widely used in electrolytic plating equipment, induction heating equipment, charging equipment, communication In the fields of power supply, UPS power supply, X-ray machine power supply, laser power supply, variable frequency speed regulation power supply, etc., the output is getting larger and larger, and the price has also been greatly reduced. The current price has dropped by about 40% compared with the original price. As the application volume continues to increase, the price will become lower and lower, and the price of nanocrystals will become closer and closer to the price of ferrite.
At present, for high-power power supplies of more than 15 kilowatts, the price of nanocrystalline iron cores is actually lower than that of ferrite iron cores. Because of the limited size of the ferrite core, the magnetic core required for high-power transformers is difficult to solve, and several cores have to be used to meet the power requirements. And a nanocrystalline iron core is enough. In terms of unit price, ferrite is much cheaper, but the total price of several iron cores is higher than the price of nanocrystalline iron cores.