What problems exist in the application of nanocrystalline materials -
In the process of applying nanocrystalline materials to inverter power supplies, some problems such as noise, brittleness, and consistency have appeared, which have affected 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, sometimes it will Noise occurs. The composition of nanocrystals is different, and the magnetostriction coefficient is different. The composition used in the past few years is a general-purpose alloy composition. Therefore, the noise problem of manufacturing transformers is more prominent. With the deepening of application and development, for different Use Different alloy components are used to meet the special requirements of different devices for magnetism. For example, dedicated components have been developed for power output transformers, current transformers, and common mode inductors. The alloy composition adjusted according to the requirements of the power transformer reduces the magnetostriction coefficient. It has been proved by users that the noise problem has been greatly improved. 2. The reason for the winding tightness of the iron core This has a lot to do with the quality of the strip used. The deviation of the strip size and uneven thickness will cause the iron core to be wound loosely and easily generate noise. After the composition is adjusted, the fluidity of molten steel is good, 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 prove that the noise increases with the increase of the working magnetic induction. Some manufacturers have adopted DC blocking measures on the circuit, and the use of nanocrystalline iron cores has not caused noise problems for many years. Through the above improvements, the noise problem has basically been solved. 2. The problem of brittleness The brittleness of the nanocrystalline iron core is mainly reflected in the slag drop of the iron core, which is the biggest problem reported by users. It is not only a headache for installation and operation, but also easily causes hidden dangers of short circuit to the circuit. After years of practice and research, the problem of brittleness has been greatly improved through the adjustment of ingredients and processes. After composition adjustment, 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, which makes the iron core not easy to break, and completely solves the brittleness problem of the iron core falling slag. At the same time, since the stress-free glue fixes the layer gap of the iron core strip, it is not easy to generate resonance and reduces the generation of noise. 3. Consistency issues Consistency is related to the scale of production and the capacity of production equipment. From the quality of the strip, comparing a 500 kg output equipment with a 50 kg output equipment, the same production of 500 kg strip, obviously, the consistency of composition and magnetic properties of the former product is better than that of the latter. The same is true for heat treatment during production. Therefore, large production scale and large production equipment capacity are beneficial to consistency. The consistency of nanocrystals is mainly manifested 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 there is no classification and screening in production inspection. With the adjustment of the components used in power transformers, not only the brittleness is improved, but also the residual magnetic induction intensity of the material is reduced. Therefore, the effect of magnetic field heat treatment is increased, and the saturation voltage of the iron core is increased, which plays an important role in product consistency. . There is a gradual understanding of the magnetic properties required by the inverter power supply. In the past few years, due to the small amount used, it is enough to only emphasize that the loss meets the requirements. Therefore, the performance test only measures the loss parameter. For specific users, increase the detection induced voltage value. With the increasing amount of applications, various requirements are put forward, especially the requirement of performance consistency is particularly prominent. Since there is a process of understanding this requirement, there is some lag in terms of composition improvement, production organization, and testing standards. Therefore, it has a certain influence on the promotion and application. Now that the problem has been sufficiently recognized and multiple effective measures have been taken, the consistency has greatly improved. 4. The price issue The price issue is the most concerned by users, especially those who are ready to use or just started using it. The price is directly related to the production volume. In recent years, with the application of nanocrystalline iron core in more and more fields, 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, frequency conversion speed regulation power supply and other fields, the output is increasing, and the price has also been greatly reduced. The current price has dropped by about 40% compared with the original price. With the With the continuous increase of application volume, the price will be lower and lower, and the price of nanocrystal will be closer and closer to the price of ferrite. At present, for high-power power supplies above 15 kilowatts, the price of nanocrystalline cores is actually lower than that of ferrite cores. Because the size of the ferrite core is limited, the magnetic core required by the high-power transformer is difficult to solve, and several cores have to be used to meet the power requirement. And one 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 that of nanocrystalline iron cores.