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Advantages and problems of using nanocrystalline in inverter power supply

Advantages and problems of using nanocrystalline in inverter power supply

2021-12-01

1. Advantages of Nanocrystalline


 Nanocrystalline magnetic rings (ultra-microcrystalline iron cores) additionally have the advantages of silicon steel, permalloy, and ferrite cores. which is:


 High magnetic induction: the saturation magnetic induction Bs=, which is twice that of permalloy and times that of ferrite cores. The power of the transformer core is large, which can exceed 15 kW to 20 kW/kg.


 High permeability: The original permeability μ0 of static data can reach 120,000 to 140,000, which is very similar to Permalloy. The magnetic permeability of the transformer coil used to output the power is ten times that of the ferrite core, which greatly reduces the output power of the excitation current and improves the high efficiency of the transformer.


 Low loss: In the frequency range of 20kHz~50kHz, the ferrite core is 1/2~1/5, which reduces the temperature of the transformer core.


 High Curie temperature: The Curie temperature of the nanocrystalline magnetic ring (ultramicrocrystalline iron core) is 570℃, and the Curie temperature of the ferrite core is only 180℃~200℃.


Because of the advantages of the left and right, the transformer produced by nanocrystalline is used in the inverter power supply, which has a great effect on the credibility of the switching power supply:


 The loss is small and the temperature of the transformer is low. The long-term specific applications of many customers have confirmed that the temperature of the nanocrystalline transformer is much lower than the temperature of the IGBT water pipe.


 The high permeability of the transformer core reduces the output power of the excitation current, reduces the copper loss, and improves the high efficiency of the transformer. The primary and secondary inductors of the transformer are large, which reduces the impact of the current on the IGBT water pipe when the power is switched on and off.


 High magnetic induction and high power during work can exceed 15Kw/kg. The volume of the transformer core is reduced. It is a power inverter power supply. The reduction of the volume promotes the expansion of the indoor space in the main box, which is beneficial to the heat dissipation of the heat pipe of the IGBT water pipe.


 The load capacity of the transformer is strong, because the magnetic induction is selected at about 40% of the saturation magnetic induction during work. When the load is generated, it is only hot because of the increase of the magnetic induction, and it is not easy to destroy the IGBT due to the saturation of the transformer core water pipe.


The Curie temperature of the nanocrystalline magnetic ring (ultramicrocrystalline iron core) is high. If the temperature exceeds about 100°C, the ferrite core transformer can no longer work, and the nanocrystalline transformer can completely work normally.


 This advantage of nanocrystalline has been understood and selected by more and more switching power supply manufacturers. A group of Chinese manufacturers have already selected nanocrystalline transformer cores and used them for many years. More and more manufacturers have just started to apply or use. At this stage, it has been widely used in industries such as inverter welding machine, power supply system, electrolytic power supply for electroplating process, induction heating equipment, charging power supply and other industries, and there will be more substantial improvements in the next two years.


2. Issues that everyone is concerned about


 In the whole process of using nanocrystalline magnetic ring (ultra-microcrystalline iron core) in inverter power supply, there have been some problems such as noise problems, ductility problems, consistency problems, etc., which harmed the application and promotion at a certain level, causing care. Now this kind of problem has been gradually dealt with.


(1) Noise problem


 There are various reasons for noise:


 1. Due to the magnetostriction index of the raw material itself, the magnetostriction index of the ferrite core raw material is relatively large. Although the ferrite core is a solid core, noise may sometimes occur in the application. The composition of nanocrystals is different, and the magnetostriction index is different. The composition used in the first two years is a universal aluminum alloy composition. Therefore, the noise problem of the production of transformers is very obvious. Followed by the application, development and design In more depth, different alloy compositions are selected for different main purposes to consider the requirements of different components for magnetization. For example, as output power output transformers, voltage transformers, common mode inductors, etc., special components have been developed and designed. The alloy composition adjusted according to the regulations of the output power transformer reduces the magnetostrictive index. The customer application has confirmed that the noise problem has been greatly improved.


2. The winding of the transformer core is tight and loose, which has a lot to do with the quality of the applied amorphous strip. The specification error and uneven thickness of the amorphous strip will cause the transformer core to be wound too loose, which is very easy to cause noise. . After adjusting the composition, the molten steel has good liquidity, which is beneficial to the forming quality of the amorphous strip. To a certain level, it is beneficial to reduce the noise of the transformer core.


 3. The problem at the rectifier circuit level is that the DC component in the power circuit is large, which causes the magnetic induction of the transformer core to increase and cause noise. People's experiments have confirmed that the noise increases with the increase of the magnetic induction during work. Some manufacturers have adopted DC-blocking countermeasures on the power supply circuit, and the application of nanocrystalline transformer cores has not caused noise problems for many years.


 According to the improvement of the left and right, the foundation of the noise problem has been dealt with.


(2) The problem of ductility


 The key to the ductility of the nanocrystalline transformer core is reflected in the slag drop of the transformer core, which is a big problem for customers. It is not only a headache for simple installation, but also very easy to cause short-circuit failure to the power circuit. After many years of practical activities and scientific research, the ductility problem has been greatly improved based on the adjustment of the composition and processing technology. After the composition is adjusted, the flexibility of the amorphous ribbon is significantly improved. The thinning of the thickness of the amorphous strip also reduces the ductility. In addition, in the process of manufacturing the transformer core, the transformer core is impregnated with non-earth-stress glue to make the transformer core not fragile and completely eliminate the problem of ductility of the transformer core. In addition, because the non-ground stress glue fixes the interlayer gaps of the transformer core amorphous strip, it is not easy to cause resonance and reduces the noise.


(3) Consistency issues


 Consistency is related to the scale of manufacturing operations and the volume of production line equipment. From the perspective of the quality of amorphous strips, a 500KG production volume of machinery and equipment is comparable to a 50KG production volume of machinery and equipment, and 500KG amorphous strips are produced in the same way. It is obvious that the consistency of the composition and magnetic energy of the previous product is better than The latter one. The same quenching and tempering treatment in the processing process is the same. Therefore, the large scale of manufacturing and operation and the large volume of production line equipment are beneficial to consistency.


 In customer applications, the consistency of nanocrystals is specifically manifested in the large dispersion of the saturated operating voltage and the amount of inductors, sometimes more than twice the distance. The key reason is that the actual effect of the electromagnetic field quenching and tempering treatment is poor, and the manufacturing inspection is not classified and selected. The subsequent adjustment of the components of the output power transformer not only improves the ductility, but also reduces the remaining magnetic induction intensity of the raw materials, thus expanding the actual effect of the electromagnetic field quenching and tempering treatment, and increasing the saturation working voltage of the transformer core , Played a key role in product consistency.


(4) Price issue


 The price problem is what customers are most concerned about. It is very important for customers who have prepared applications in advance or have just started applications. The price is immediately related to the total output. In the past two years, the industry used for nanocrystalline transformer cores has become more and more common, not only for inverter welding machines, but also for electrolytic plating equipment, intermediate frequency induction furnaces, and battery charging. Machinery and equipment, power supply systems, UPS switching power supplies, X-ray film machine switching power supplies, laser generators, AC motor speed control switching power supplies and other industries, the production volume is increasing, and the price is also greatly reduced. The price comparison at this stage is the most The initial price has already been reduced by about 40%, and as the amount of use continues to expand, the price will drop sharply, and the price of nanocrystals will become closer and closer to the price of ferrite cores.


 At this stage, for a switching power supply with a power of about 15KW, in fact, the price of nanocrystalline transformer cores is already lower than that of ferrite core transformer cores. Due to the insufficient specifications of the ferrite core transformer core, there is no way to deal with the magnetic core necessary for the power transformer. It is compelled to apply multiple transformer cores before considering the output power regulations. One nanocrystalline transformer core is sufficient. From the cost point of view, ferrite cores are much more cost-effective, but the original price of many transformer cores is higher than the price of nanocrystalline transformer cores.


3. Commodities of nanocrystalline transformers


 The nanocrystalline transformers used are basically all wound by the entire equipment manufacturer itself, because the design schemes of the rectifier circuit of each factory are different, the mastery of the nanocrystalline magnetic ring (ultra-microcrystalline iron core) is different, and the transformer is not the same. The level of mastery of electrical manufacturing and processing technology is different, and the level of transformers manufactured is also different. Manufacturing high-frequency transformers has become a key step in manufacturing. As a result, some manufacturers have clearly stated that whether high-frequency transformers can be manufactured systematically and the entire equipment manufacturers should purchase transformers immediately.


 In the original transformers in the frequency range of 20kHz~50kHz, ferrite cores are generally used as transformer coils. Transformer cores are mostly U-type or EI-type. Very few use O-type transformer cores, U-type or EI-type transformer cores. From the structure, there is no way to reduce the leakage inductance of the transformer.


 Because of the advantages of the nanocrystalline magnetic ring (ultra-microcrystalline iron core), it shows an ideal raw material for the practical and high-efficiency of high-frequency transformers. A new structure of high-frequency transformers promoted by new materials came out.


This type of transformer named "Beetle", which has been patented, was later improved by others and called it the "H" type transformer. It has also been patented. These two types of transformers flexibly use nanocrystalline magnetic rings (superfine crystals). The magnetic characteristics of high permeability, high magnetic induction, and inferior loss, as well as the small magnetic leakage characteristics of the toroidal transformer core, make the primary and secondary sides of the transformer break down and build new ones. Use the metal material maintenance box of the transformer core as the secondary coil of the transformer, which is suitable for large current output, and the primary coil is symmetrically wound on the secondary side, and the leakage inductance is not large. The fixed support point of the transformer is integrated with the confluence output, which is beneficial to heat dissipation of the heat pipe.


The advantages of this type of transformer are:


 1. Large output power: 10 kW~20kW, power can exceed 15 kW~20kW/kg


 2. The leakage inductance is small, the general level is less than 5μH, preferably less than 2μH


 3. High efficiency, more than 99%


 4. Light weight and light weight, the net weight of the 15 kW transformer is 3KG, and the volume is 160×150×95 mm


 5. The appearance design is beautiful and generous.


 The practicability of nanocrystalline transformers effectively uses the characteristics of nanocrystalline soft magnetic materials; it is beneficial to the practicability and standardization of high-voltage power transformers; it is beneficial to the high efficiency and level of transformers; it is beneficial to inverter welding machines, Electroplating process, electrolysis method and other equipment


 Increase in productivity. At this stage, there are many manufacturers that can produce this type of transformer.


 Nowadays, some of the entire equipment manufacturing has just started to use "Ω" type transformers to maintain integrated manufacturing. It is a "more, faster, better, and economical" measure.


Fourth, the conclusion


 Because of its outstanding characteristics, amorphous and nanocrystalline soft magnetic materials, in different applications, fill in the shortage of raw materials for silicon steel and ferrite cores, and raise various electronic equipment to a new level, improve high efficiency, Obtained significant actual effect of environmental protection and energy saving. The new material shows the vigorous vitality of the information.


 Nowadays, more and more people know about amorphous magnetic cores and nanocrystalline magnetic rings (ultra-microcrystalline iron cores). In addition to open transformers, amorphous magnetic cores and nanocrystalline magnetic rings (ultra-microcrystalline iron cores) can As raw materials for transformer cores of voltage transformers, series reactors, controllers, filters and other components, the scope of application also involves electrical products, smart meters, DC inverter air conditioners, leakage circuit breakers, etc. in people’s daily life. Accurate measurement of substation engineering of power supply system, power distribution equipment, remote sensing technology, etc., central air-conditioning of electric locomotives of railway line system software, inverter power supply of electric locomotives, railway signal sensing technology, etc., are also used in aerospace, aviation Companies, ships, and other military and national new technology projects have been selected for selection.


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