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The magnetic core plays an indispensable role in the electronic transformer, and a good magnetic core will affect the effectiveness of the electronic transformer. Traditional magnetic cores are made of ordinary ferrites. However, with the advancement of technology, amorphous magnetic cores have gradually emerged. Compared with traditional magnetic cores, amorphous magnetic cores are favored because of their much higher saturation magnetic density than ordinary ferrite cores, low loss and small size. Amorphous magnetic cores can be divided into strip-type magnetic cores and powder-type magnetic cores according to the shape of the material. Compared with strip-type magnetic cores, powder-type amorphous magnetic cores can achieve more diverse shapes, sizes and even colors, and are more suitable for small and lightweight electronic transformers. In 2019, 70% of transformers will be made of amorphous materials, and the market for powder amorphous magnetic cores is vast.  

Introduction to Permalloy Fe-Ni alloy is the so-called permalloy, which is a very important type of soft magnetic material. It shows high magnetic permeability and low coercive force under weak magnetic field magnetization, and has good cold working properties. By controlling the composition (changing the Ni content, adding one or several alloying elements, such as Mo, Cu, Cr and Ti, etc.) and the process, a variety of permalloys with different characteristics can be obtained. There are many, which can be regarded as the most soft magnetic materials. However, its disadvantage is that it contains more precious metal Ni. Therefore, the cost is relatively high, the production equipment is huge, the process is demanding, and the magnetism is greatly affected by the environment. The Fe-Ni alloy produced in our country has a wide range of specifications and brands, and has been issued by the Ministry of Industry and Information Technology.   Permalloy annealing process precautions Compared with the one-stage annealing (1100℃×3h) in the two-stage continuous annealing (950℃×3h→1100℃×3h), the coercive force is reduced from 217.6 A/m to 8.8A/m, and the coercive force is significantly reduced and saturated. The magnetization intensity increased slightly from 74.22 emu/g to 79.34 emu/g. This shows that the two-stage continuous annealing process is beneficial to removing impurities in the alloy, purifying the alloy, thereby improving the magnetic properties of the alloy.   Permalloy preparation 1. The two-stage continuous annealing process is beneficial to remove impurities in the alloy, purify the alloy, and at the same time improve the magnetic properties of the alloy, that is, the coercive force is reduced and the saturation magnetization is increased. 2. Prolonging the holding time is beneficial to the growth of alloy grains, reducing defects within the crystal, weakening the pinning effect on domain wall movement, and making domain wall movement easier, thus improving magnetic properties. But it’s not that the longer the heat preservation time, the better. Because at high temperatures and long holding times, the reduction and oxidation of hydrogen and impurities in the furnace pollutes the atmosphere in the furnace, and the hydrogen dew point also increases with the increase in temperature, resulting in a decrease in the magnetic properties of the alloy. Therefore, the holding time is extended to 4 hours. On the one hand, it is beneficial to improve production efficiency, and on the other hand, it also obtains better soft magnetic properties. Taking various factors into account, the optimal heat treatment process for IJ79 alloy is determined as follows: raising the temperature to 950°C in the furnace, holding it for 4 hours, then raising the temperature to 1100°C, holding it for 4 hours, and finally cooling the furnace to room temperature. 3. The effect of changes in Ni content in the alloy on its magnetic properties was studied. It was found that if the change in Ni content is too small, the effect on the magnetic properties of the alloy is not significant. Therefore, during the production process, it is only necessary to ensure that the Ni content is within the composition of the standards issued by the Ministry of Metallurgy (YB129-70). 4. Add M to the alloy. The content is beneficial to increase the saturation magnetic induction intensity and reduce the coercive force. Combining various factors, we found ultra-low H. The preferred composition of the alloy is: Ni 78.00wt%, Mo 5.00wt%, Mn 0.90wt% Si 0.40wt%, Fe balance.

1. Advantages of Nanocrystals  Nanocrystalline magnetic rings (ultramicrocrystalline iron cores) also have the advantages of silicon steel, permalloy, and ferrite cores. Right now:  High magnetic induction: saturation state magnetic induction Bs=, which is twice that of permalloy. The transformer core has high power and can exceed 15 kW ~ 20 kW/kg.  High magnetic permeability: The original magnetic permeability μ0 of static data can reach 120,000 to 140,000, which is very similar to that of permalloy. The magnetic permeability of the coil used to output power transformer is more than 10 times that of the ferrite core, which greatly reduces the excitation current output power and improves the efficiency of the transformer.    Low loss: In the frequency range of 20kHz to 50kHz, the ferrite core is 1/2 to 1/5, reducing the transformer core temperature.  High Curie temperature: The Curie temperature of the nanocrystalline magnetic ring (ultra-microcrystalline iron core) reaches 570°C, while the Curie temperature of the ferrite core is only 180°C ~ 200°C.  Because of its advantages, nanocrystalline transformers are used in inverter power supplies, which has a great effect on improving the reliability of switching power supplies:  The loss is small and the temperature of the transformer is low. The long-term practical use of many users has confirmed that the temperature of the nanocrystalline transformer is far lower than the temperature of the IGBT water pipe.  The high magnetic permeability of the transformer core reduces the excitation current output power, reduces copper loss, and improves the efficiency of the transformer. The primary and secondary inductors of the transformer are large, which reduces the impact of current on the IGBT water pipe when the power is turned on and off.  During operation, the magnetic induction is high and the power is high, which can exceed 15Kw/kg. Reduce the volume of the transformer core. Especially for power inverters, the volume reduction increases the space inside the main chassis, which is beneficial to the heat dissipation of the IGBT water pipe.  The load capacity of the transformer is strong, because the magnetic induction during operation is selected to be around 40% of the saturation induction. When the load occurs, it is only due to the increase in magnetic induction that it will become hot, and it will not damage the IGBT due to the saturation of the transformer core. water pipe.  The Curie temperature of the nanocrystalline magnetic ring (ultra-microcrystalline iron core) is high. If the temperature exceeds about 100°C, the ferrite core transformer will no longer be able to work, but the nanocrystalline transformer can work normally.  This advantage of nanocrystals has been understood and adopted by more and more switching power supply manufacturers. A group of manufacturers in China have already adopted nanocrystalline transformer cores and have used them for many years. More and more manufacturers are beginning to use or use it. At present, it has been widely used in inverter welding machines, power systems, electrolytic power supplies for electroplating processes, induction heating equipment, charging power supplies and other industries, and there will be even greater improvements in the next two years.    2. Issues that everyone is concerned about  In the process of using nanocrystalline magnetic rings (ultramicrocrystalline cores) in inverter power supplies, there have been some problems such as noise problems, ductility problems, consistency problems, etc., which have affected the application promotion to a certain extent and caused care. Now these problems have been gradually solved.   (1) Noise problem  Noise is generated for various reasons:  1. Due to the magnetostrictive index of the material itself, the magnetostrictive index of the ferrite core material is relatively large. Although the ferrite core is solid, noise sometimes occurs during use. The composition of nanocrystals is different, and the magnetostrictive index is different. The composition used in the past two years is a general aluminum alloy composition. Therefore, the noise problem in the production of transformers is very obvious, and the application, development and design More and more, different alloy compositions are used for different purposes to meet the magnetic requirements of different components. For example, special components have been developed and designed for power transformers, voltage transformers, common mode inductors, etc. The alloy composition adjusted according to the requirements of the power transformer reduces the magnetostrictive index. It has been confirmed by user applications that the noise problem has been greatly improved.  2. The reason why the transformer core is wound tightly is closely related to the quality of the amorphous strip used. The size error and uneven thickness of the amorphous strip can cause the transformer core to be wound too loosely, which can easily cause noise. . After adjusting the composition, the molten steel has good fluidity, which is beneficial to the forming quality of the amorphous strip. It provides a beneficial guarantee for reducing the noise of the transformer core to a certain extent.  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, causing noise. Our experiments have confirmed that the noise increases as the magnetic induction increases during work. Some manufacturers have adopted DC isolation measures in power circuits and have used nanocrystalline transformer cores without any noise problems for many years.  Through the improvement of left and right, the noise problem has been basically solved.   (2) Ductility problem  The ductility of the nanocrystalline transformer core is mainly reflected in the slag shedding of the transformer core, which is a major problem for users. It is not only a headache for simple installation, but also easily causes short-circuit faults in the power circuit and safety hazards. After many years of practice and research, the ductility problem has been greatly improved through adjustments to ingredients and processing techniques. After the composition is adjusted, the flexibility of the amorphous strip is significantly improved. Thinning of the amorphous ribbon also reduces ductility. In addition, in the process of manufacturing the transformer core, the transformer core is impregnated with non-stress adhesive, which makes the transformer core less fragile and completely eliminates the ductility problem of slagging in the transformer core. At the same time, because the stress-free glue fixes the gaps between the amorphous strips of the transformer core, it is less likely to cause resonance and reduces the generation of noise.    (3) Consistency issues  Consistency is related to the scale of manufacturing operations and the volume of production line equipment. Judging from the quality of amorphous strips, a 500KG production capacity machine is comparable to a 50KG production capacity machine. The same can produce 500KG amorphous strips. Obviously, the former product has better consistency in composition and magnetic energy. The latter one. The conditioning and tempering treatments during processing are the same. Therefore, large-scale manufacturing operations and large production line equipment are beneficial to consistency.  The consistency of nanocrystals in customer applications is manifested in the large discreteness of the saturation state operating voltage and inductor quantity, sometimes more than double the distance. The main reason is that the effect of electromagnetic field quenching and tempering treatment is poor and there is no classification and selection in manufacturing inspection. The subsequent adjustment of the components used in the power transformer not only improves the ductility, but also reduces the residual magnetic intensity of the material, thus increasing the effect of electromagnetic field quenching and tempering and increasing the saturation voltage of the transformer core. , plays an important role in product consistency.    3. Nanocrystalline transformer products  The nanocrystalline transformers used are almost all wound by the equipment manufacturer itself, because each factory has different designs of rectifier circuits, different understanding of nanocrystalline magnetic rings (ultra-microcrystalline iron cores), and different requirements for transformers. The level of mastery of electrical appliance manufacturing and processing technology is different, and the level of produced transformers is also different. Manufacturing high-frequency transformers has become an important step in manufacturing. Therefore, some manufacturers have raised the possibility of systematic production of high-frequency transformers and the requirement for all equipment manufacturers to directly purchase transformers.  Originally, transformers in the frequency range of 20kHz to 50kHz generally used ferrite cores as transformer coils. The most common forms of transformer cores were U-type or EI-type. O-type transformer cores, U-type or EI-type transformer cores were rarely used. There is no structural way to reduce the leakage inductance of the transformer.  Due to the advantages of nanocrystalline magnetic rings (ultra-microcrystalline iron core), it provides ideal materials for the practicality and efficiency of high-frequency transformers. New materials promote the advent of a new construction of high-frequency transformers.  This kind of patented transformer named "Beetle" was later improved by others and called "H" type transformer, which was also patented. These two transformers make full use of nanocrystalline magnetic rings (ultra-microcrystalline). The magnetic characteristics of high magnetic permeability, high magnetic induction intensity, low loss and small magnetic leakage of the toroidal transformer core have broken new ground in the primary and secondary structures of the transformer. The metal protection box of the transformer core is used as the secondary coil of the transformer, which is suitable for large current output. The primary coil is evenly wound around the secondary side, and the leakage inductance is not large. The fixed support point of the transformer is integrated with the bus output, which is beneficial to heat dissipation.    The advantages of this type of transformer are:  1. Large output power: 10 kW～20kW, power can exceed 15 kW～20kW/kg  2. Leakage inductance is small, generally less than 5μH, preferably less than 2μH  3． High efficiency, over 99%  4. 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 elegant.    The practical application of nanocrystalline transformers effectively utilizes the characteristics of nanocrystalline soft magnetic materials; it is beneficial to the practicality and standardization of high-voltage power transformers; it is beneficial to the improvement of high efficiency and level of transformers; it is beneficial to inverter welding machines, Electroplating process, electrolysis and other machinery and equipment  Productivity improvements. Currently, there are many manufacturers that can produce this type of transformer.  Nowadays, some entire equipment manufacturing has begun to use "Ω" type transformers to achieve integrated manufacturing. This is a "more, faster, better, and more economical" approach.    4. Conclusion  Due to their excellent characteristics, amorphous and nanocrystalline soft magnetic materials make up for the shortage of silicon steel and ferrite core materials in different applications, bringing various electronic devices to a new level, improving efficiency, Significant environmental protection and energy saving effects have been achieved. New materials show vigorous vitality.  Nowadays, more and more people know about amorphous magnetic cores and nanocrystalline magnetic rings (ultramicrocrystalline iron cores). In addition to transformers, amorphous magnetic cores and nanocrystalline magnetic rings (ultramicrocrystalline iron cores) can As the transformer core material for voltage transformers, series reactors, controllers, filters and other components, its application scope also involves electrical products in people's daily lives, smart meters, DC variable frequency air conditioners, leakage protection circuit breakers, etc. Transformation measurement, power distribution equipment, telemetry sensing technology of power supply system, electric locomotive central air conditioner of railway line system, inverter power supply of electric locomotive, railway signal sensing technology, etc., are also used in aerospace, aviation It has been selected and finalized in various military and national new technology projects such as companies and ships.

With the rapid development of wireless charging, wireless charging is now more and more popular in many industries such as smartphones, smart wearable devices, smart home systems, new energy vehicles, etc., and the sales market worth hundreds of billions of dollars has once again become a trend. However, there are many difficulties in wireless charging, which also cause headaches for those in the industry. The entire industry chain has been developing towards five major aspects: simplicity, fast charging, temperature control, intelligence, and playability.   Recently, mobile phone manufacturers such as Huawei have increased wireless charging power to 15W, which has greatly inspired the entire manufacturing industry. To maintain power wireless charging, wireless charging practitioners currently face many challenges, including: conversion efficiency between electromagnetic induction, increasingly tight magnetic coupling, magnetic interference, thermoelectric effects, position correction, and load adjustment. This will cause several problems such as the charging part of the wireless charging being unable to be pointed, the charging conversion efficiency being high, and the charging time being too long.   As one of the important components of wireless charging technology, Hemei Electronics plays the role of increasing the electromagnetic field and shielding the electromagnetic coil interference in wireless charging equipment. Therefore, wireless charging equipment has a certain influence on the performance and product specifications of permanent magnet materials, Credibility and other requirements are higher.   Although cross-generational products are eye-catching, being unique and fun is not the key to gaining sales. In the end, what customers still care about is their feelings.   Although wireless charging can improve the importance of user experience, it also has the problem of slow charging, so there is an urgent need to relatively increase charging power. However, the traditional ferrite core material has a serious problem of heating during wireless charging, and it can no longer meet the power charging requirements.   In comparison, nanocrystal materials contain various possibilities and have great potential for application in wireless charging in the future. Therefore, in wireless charging applications and RX module design, the advantages of nanocrystalline materials are fully demonstrated.   Nanocrystalline materials have various excellent comprehensive magnetic properties such as high saturation magnetic induction (), magnetic permeability >800, and poor high-frequency loss under high magnetic induction. They are the materials with the best comprehensive performance on the current market. Nowadays, nanocrystals rely on their advantages to excel in the testing of various important parameters of magnetic materials, gradually replacing ferrite cores and becoming the new choice of many wireless charging manufacturers.   According to statistics, the saturation magnetic induction of amorphous Nano-M-Sheet far exceeds that of ferrite cores, and its anti-saturation working ability far exceeds that of ferrite cores. The magnetic induction intensity of the Nano-M-Sheet raw material does not change greatly with temperature, it is not prone to magnetic saturation, and its temperature reliability is better than that of ferrite cores.   Aluminum alloy amorphous strip   In addition, the Nano-M-Sheet material has high saturation magnetic flux and low loss characteristics as well as excellent thermal conductivity. Under the same wireless charging working conditions, the temperature of the Nano-M-Sheet material is higher than that of ferrite. The core temperature is 7~8℃. In contrast, ferrite core materials are easy to reach saturation. When used in wireless charging, as the temperature rises, the magnetic induction decreases, the shielding properties decrease, the vortex increases, and the heating becomes more serious, resulting in polarization. The properties of the Nano-M-Sheet material are very stable below 80°C. As the temperature increases, although the magnetic induction decreases, the change is not significant.   Hemei Electronics is a technology company that integrates design, product development, manufacturing and sales of amorphous and nanocrystalline new soft magnetic materials and electronic devices. Its main business is nanocrystalline strips, ultra-microcrystalline magnetic cores, and permalloy. Magnetic cores, high-power transformer cores, nanocrystalline magnetic ring inductors, electromagnetic ring coils, switching transformers, common mode inductance coils, precision current transformers and other products have the advantages of good stability and high electrical parameters.   At this stage, the industrial production and processing technology of the company's amorphous nanocrystalline amorphous strips includes layer-by-layer processes such as smelting, tape spraying, tape feeding + inspection, and winding. At this stage, the quenching angular velocity exceeds ~30m/second. The thickness of the amorphous ribbon is 18~37um, and the total width of the amorphous ribbon is.   In order to meet new market challenges and comply with the market trend of high efficiency, low loss, and thin specifications, Hemei Electronics' next product development plan for amorphous will be in the promotion of nanocrystalline products, technological improvements, and new products. Development and design are carried out in three aspects.   In terms of research and development of nanocrystalline raw materials, Hc of soft magnetic materials is reduced and Bs is increased to improve alloy composition. For the current 18 μm thin nanocrystalline amorphous strip, we will reduce eddy current loss, increase the frequency bandwidth, and reduce the product thickness to 12~15 μm. By increasing the permeability and improving product consistency, the constant support force quenching target of nanocrystalline amorphous strips is exceeded 12,000~15,000.   According to statistics, when nanocrystalline amorphous ribbons undergo crystallization and constant support force quenching and tempering, magnetic anisotropy will occur, making the long and short directions of the ribbons become hard-to-magnetize axes, thereby controlling the magnetic permeability within a wide range. , producing nanocrystalline soft magnetic materials with different magnetic permeabilities. The characteristic of this low-permeability nanocrystalline soft magnetic material is that it has small eddy current loss and can suppress the decrease in magnetic permeability when higher frequencies coincide with electromagnetic fields. Therefore, it can be used in DC accumulation in high-frequency areas.   In terms of nanocrystalline amorphous strip free online insulation coating technology, amorphous will reduce losses, increase frequency bandwidth, and reduce product thickness to achieve technical improvements. In the future, Amorphous will also develop and design a soft magnetic powder based on cast film technology that can reduce eddy current losses, increase frequency bandwidth, and reduce product thickness to sub-μm level.

The split core current transformer has a unique advantage in terms of ease of use, especially in field measurement occasions where interruption is not allowed. It is almost a fixed choice. The split core current transformer on the market are mainly based on the Hall principle or Rogowski coil. Due to the working principle, the accuracy is generally not high, and can only achieve about 1%. In fields such as power measurement, a large number of products with an accuracy level of 0.1% or higher are required, but the current products cannot meet the performance requirements.At present, the full-scale accuracy of our SCI series of split core transformer is 0.1% and 0.02%, and the range covers 100A to 5000A. The measurement frequency range is from DC to hundreds of kHz. High-precision split core current transformer.   II. Design principle of split core current transformer Traditional split core current transformer, whether based on the Hall principle or Rogowski coil, theoretically cannot achieve high accuracy. Sensors based on the Hall principle, even the non-open-loop closed-loop Hall sensors with high accuracy, have an upper limit of only about 0.3%. If they are made into open-loop ones, the accuracy will be further reduced. The disadvantage of Rogowski coils is also low accuracy. Flexible Rogowski coils can only achieve 1%. There are other obvious disadvantages, such as inability to measure DC, poor low-frequency characteristics, poor waveform quality, and obvious phase delay. High-precision split core current sensors, which belong to a type of direct coupled current transformer (DCCT), are a new generation of isolated current measurement devices that can measure DC, AC or pulse currents and have high-level test accuracy. In addition to the advantages of isolated measurement, it also has a series of significant advantages such as wide measurement dynamic range, extremely high measurement accuracy, wide bandwidth, fast response speed, and basically not affected by external environment such as temperature. Compared with the previous generation of Hall resistance current sensors, its performance has been qualitatively improved. The basic principle of our SCI series sensors is based on the new magnetic modulation zero flux technology. By driving the feedback current to compensate for the influence of the bus current on the magnetic ring, the zero flux state in the magnetic ring is measured, and the nearly ideal bus current-output current ratio is achieved. The SCI series of high-precision split core current sensors apply the zero flux principle. Through the superior modulation and demodulation design ideas, the high performance of this series of sensors is guaranteed in principle; through efficient self-recovery logic, high reliability under complex working conditions is achieved; through the optimization of process manufacturing and processing flow, excellent product performance and ease of use are achieved.   III. High-precision open-close current sensor index test For the performance test of the SCI series of high-precision open-close current sensors, our company selected high-precision current sensors calibrated by the China Institute of Metrology and awarded with calibration certificates for comparison test. However, due to the poor intuitiveness of the comparison method, our company uses the source meter method to test it on the basis of ensuring the accuracy of the open-close current sensor, so that customers can see it at a glance. We selected the high-precision split core current sensor SCI-600 with a range of 600A and a full-scale accuracy of 0.02% for testing. As shown in Figures 3 and 4, we selected the SCS-1500AU DC large current source with a full range of 1500A and an accuracy of 0.01% independently developed by our company as the test DC current source, the eight-and-a-half-digit meter as the test meter, and the voltage range (here we selected the Vishay series resistor with a calibrated resistance of 1.000006Ω as the load resistor for testing).   IV. Advantages The SCI series split core current sensor adopts an open-close through-core structure, provides a variety of measurement apertures and ranges to choose from, and does not need to disconnect the busbar to be measured, which is convenient for installation and measurement. It is mainly used in the field of DC, AC and pulse current measurement that requires high measurement accuracy. The primary and secondary currents are isolated from each other, and the safety performance is excellent.   Performance characteristics: Open-and-close type, easy to install and measure Advanced zero-flux closed-loop current sensor Excellent linearity and accuracy Extremely low temperature drift Wide bandwidth and low response time Isolated measurement of primary and secondary sides Strong anti-interference ability

The ability to switch magnetic elements via spin-orbit-induced torque has attracted much attention recently, contributing to the realization of high-performance nonvolatile memories with low power consumption. To achieve efficient spin-orbit-based switching, new materials and novel physics are needed to obtain high charge-spin conversion efficiency, so the choice of spin source is crucial. In view of this, Professor Hyunsoo Yang of the National University of Singapore and others recently reported the observation of spin-orbit torque (SOT) switching in a bilayer consisting of 1T'-MoTe2 semi-metallic films adjacent to permalloy. Deterministic switching can be achieved at room temperature without external magnetic fields, and the current during switching is an order of magnitude smaller than the typical current in the best-performing heavy metal devices. If the contribution of the interface spin orbit is considered in addition to the overall spin Hall effect, the reason for its thickness dependence can be understood. With the help of dumbbell-shaped magnetic elements, the switching current is further reduced by a factor of three. The findings of this article show that MoTe2 has important application prospects in the field of low-power semi-metallic spin devices. Hemei Electronics is committed to the research, development, production and sales of amorphous, nanocrystalline, Permalloy cores, current transformers, and current transformer CTs. Our products have good stability and high electrical parameters. The company has multiple vacuum heat treatment furnaces, hydrogen annealing furnaces, fully automatic core winding machines, magnetic material automatic detection systems, multiple fully automatic winding machines, and other equipment and precision testing instruments. We can customize and develop microcrystalline, nanocrystalline cores, Permalloy core related products and various magnetic ring inductors for customers. Please feel free to contact us.

Inductor is one of the commonly used components in circuit design. It can form an LC filter network with capacitor C, form a freewheeling function with diodes in the buck circuit, and can also be used in LC resonant circuits. The following introduces common applications of inductors.   1. Use capacitors to form a liquid crystal filter circuit It is well known that inductors can pass DC and resist AC, because the inductance of inductors has a great relationship with the AC frequency. The higher the frequency, the greater the inductance. As shown in the figure below, it is the most commonly used circuit structure for switching power supplies, and inductors and capacitors play a filtering role. The AC ripple in the circuit will be filtered by the inductor and the capacitor C, making the back-end output smoother. This is usually used in switching power supplies or high power applications. 2. Used in DC/DC buck circuits The DC/DC buck chip has a wide input range and high conversion efficiency. The circuit principle of the DC/DC buck chip is generally realized by inductors, capacitors and diodes. As shown in the figure below, it is an ordinary DC/DC power chip, in which the inductor and diode constitute the freewheeling function. When the internal MOS tube is turned on, the inductor stores energy; when the internal MOS tube is turned off, the inductor can power the load. This is also the most commonly used PWM step-down principle at present. 3. Used in LC resonant circuit LC can form series resonance or parallel resonance, also called frequency selection, that is, among many input frequencies, only those consistent with the resonant frequency can pass. This circuit is often used in broadcasting, television and other applications. When designing an LC resonant circuit, a lot of calculations are required to determine the optimal parameters of inductance and capacitance. A magnetic ring inductor is a coil with a magnetic ring. Because the coil has an inductive reactance to alternating current after being energized, it constitutes an electronic component-inductor! Its inductance value ranges from zero point zero to ten millisin. Originally, only coils can constitute inductance, but in order to increase inductance and reduce the volume and DC resistance of the wire, a ferrite core with the smallest eddy current loss is added. For example, if a magnetic core with a magnetic permeability of 100 is added to a coil of 1 micron, the inductance theoretically increases 100 times to 100 micron. But the actual increase is not only the magnetic permeability, but also related to the shape of the magnetic core (in addition to the ring, there are also cylindrical, square, bar, Wangzi, mouth-shaped, etc.). High-frequency AC circuits generally use magnetic core inductors below tens of millimeters. The inductance of AC circuits below a few hundred hertz is above a few hundred millimeters-enjoy. It is not suitable to use magnetic cores, microcrystalline, slope film alloy, or even silicon steel sheets! The volume and weight are much larger! Do not add iron cores where the inductance quality Q is extremely high. Inductor components are mainly used in resonant circuits, bandpass filters and bandstop filters. According to the design requirements, the circuit consists of a tuning circuit, a frequency selector, a notch filter, a filter, a high-frequency and medium-frequency transformer, an anti-interference circuit, a damping circuit, a spark extinguishing circuit, an energy storage circuit, a bridge, etc. Commonly used for filtering and anti-interference!   Hemei Electronics is committed to the research and development, production and sales of amorphous, nanocrystalline, permalloy, silicon steel core, current transformers, energy harvesting CT and electromagnetic shielding shells. The products have good stability and high electrical parameters. If you need these products, please feel free to contact us.

Before figuring out the difference between common mode inductors and differential mode inductors, it is important to first figure out what common mode current and differential mode current are.   　　Differential mode current: A pair of signals of the same magnitude and opposite direction on a pair of differential signal lines is generally the working current in the circuit, and the signal line is the current flowing between the signal line and the signal ground.   　　Common mode current: the current of a pair of signals (or noise) of the same magnitude and direction on a pair of differential signal lines. In circuits, ground noise usually propagates in the form of common-mode currents, hence the term common-mode noise. 　　In addition to eliminating common mode noise from the source, there are many ways to suppress common mode noise, but a commonly used suppression method is to filter out common mode noise by means of a common mode inductor, i.e., to keep the common mode noise outside the target circuit. That is, in-line series common mode inductor device. The principle is to increase the impedance of the common-mode loop so that the common-mode current is consumed and blocked (reflected) by the choke, thus suppressing the common-mode noise on the line.   　　Principle of Common Mode Chokes and Inductors   　　If a magnetic material is used around a pair of rings that are orientated in the same direction, a magnetic flux will be generated in the coil due to electromagnetic induction when an alternating current is passed through. Since the flux generated by the differential mode signal is of the same size and in the opposite direction and cancels each other out, the differential mode impedance generated by the magnetic rings is very small; however, since the flux generated by the common-mode signal is of the same size and in the same direction and is superimposed on each other, the common-mode impedance generated by the magnetic rings is very large. This characteristic makes the common-mode choke have little effect on the differential-mode signal, and has a good filtering effect on the common-mode noise. 　　Differential mode current passes through the common mode coil, the magnetic lines of force are in opposite directions and the induced magnetic field is weakened. The direction of the magnetic lines of force can be seen from the figure below, with the solid arrows indicating the direction of the current and the dashed lines indicating the direction of the magnetic field. 　　When the common mode current passes through the common mode coil, the magnetic lines of force are in the same direction and the induced magnetic field is enhanced. The direction of the magnetic force lines can be seen from the figure below as follows:The solid line arrow indicates the direction of the current, and the dashed line indicates the direction of the magnetic field. 　　It is well known that the inductance or self-inductance coefficient of a common mode coil indicates the ability to generate a magnetic field. For common mode coils or common mode chokes, when the common mode current flows through the coil, the magnetic flux is superimposed due to the same direction of magnetic flux, which is based on the principle of mutual inductance. In the figure below, the magnetic flux generated by the red coil passes through the blue coil, and the magnetic flux generated by the blue coil passes through the red coil, creating mutual inductance. 　　In the case of inductance, the inductances are multiplied and the magnetic chain represents the total magnetic flux. In the case of common-mode inductors, when the magnetic flux is twice the original flux, the number of turns remains the same and the current is unchanged, which means that the inductance is increased by a factor of two, and the equivalent permeability is also increased by a factor of two. 　　Why is the equivalent permeability doubled? According to the inductance equation below, the cross-sectional area of the magnetic circuit and core is constant as the number of turns n remains the same and is determined by the physical dimensions of the core, so it is constant, but the permeability u is doubled so that more magnetic flux can be produced. 　　Therefore, when a common-mode current passes through a common-mode inductor, it operates in the mutual inductance mode, where the equivalent inductance is consumed more, so the impedance of the common-mode inductor increases exponentially, which gives a good filtering effect on common-mode signals, i.e., it blocks large impedance common-mode signals and prevents them from passing through the common-mode inductor, i.e., it does not pass this signal on to the next layer of the circuit, e.g., inductive impedance ZL, which is generated by the inductor. 　　To distinguish between a common mode choke and a differential mode inductor, the most important thing is that there are several windings, a common mode choke with two windings and a differential mode inductor with one winding.   Hemei electronics is committed to amorphous, nanocrystalline, permalloy core product development, production and sales, the main products are: nanocrystalline strips, ultra-microcrystalline core, ultra-microcrystalline magnetic core, permalloy core, high power transformer core, nanocrystalline magnetic ring inductors, take the electromagnetic ring coil, split core transformer, common-mode inductor coils, precision current transformers, and other products have a good stability as well as high electrical parameters and other advantages.

Current transformer is an instrument where the current at both ends affects each other. So the question is, what is the role of current transformer? Measurement? Protection? Let's take a look at it together~~   1. The role of current transformer - Introduction Current transformer, the English name is Current transformer, the symbol is TA, is an instrument that can convert a large primary current into a small secondary current based on the principle of electromagnetic induction, consisting of a closed iron core and windings. Its structure is shown in the figure below. The primary winding has fewer turns and is connected in series in the circuit that needs to measure the current, while the secondary winding has more turns and is connected in series in the measuring surface or protection circuit. When it is in working condition, the secondary circuit of the current transformer is closed (otherwise there will be safety hazards), and the impedance of the series coil of the measuring surface or protection circuit is very small, making its working condition close to short circuit.   2. The role of current transformer 1 - Used for measurement One of the functions of current transformer is to be used for measurement, which is often used for billing or measuring the current size of running equipment. When measuring large alternating currents, in order to facilitate surface measurement and reduce the danger of directly measuring high voltage electricity, it is often necessary to use a current transformer to convert it into a more uniform current. Here, the current transformer plays the role of current conversion and electrical isolation. The current transformer converts high current into low current in proportion as required. When used for measurement, the primary side of the current transformer is connected to the primary system, and the secondary side is connected to the measurement surface or relay protection equipment.   3. The second function of the current transformer - used for protection The second function of the current transformer is to be used for protection. It is often used in conjunction with relay equipment. When the line has a short circuit or overload, the current transformer sends a signal to the relay equipment to cut off the faulty circuit, thereby achieving the purpose of protecting the safety of the power supply system. The protective current transformer is different from the measuring current transformer. It can only work effectively when the current is several or dozens of times larger than the normal current, and it requires reliable insulation, a satisfactory large accuracy limit coefficient, and satisfactory thermal stability and dynamic stability.   IV. The role of current transformer - Precautions 1. During the operation of the current transformer, the secondary side is not allowed to be open and must be kept closed. Because once the secondary side is open, the magnetic flux and the secondary side voltage will far exceed the normal value (up to thousands or even tens of thousands of volts), which is extremely harmful to the safety of operators and equipment.   2. The wiring method of the current transformer should follow the series principle, that is, the primary winding is connected in series with the measured circuit, and the secondary winding is connected in series with the measuring surface or relay device.   Hemei Electronics has been professionally developing and producing current transformers for many years. If you want to know more information, please feel free to contact us!

Introduction to the characteristics of nanocrystalline magnetic cores   On the one hand, eddy currents can be isolated, and the data is suitable for higher frequencies; on the other hand, due to the gap effect between particles, the data has low permeability and constant permeability; due to the small particle size, there is basically no crusting phenomenon, and the permeability changes with frequency are relatively stable; in addition, the powder core can be made into various shapes of special-shaped parts for use in different fields; finally, the industrial broken strip is crushed into magnetic powder and then made into magnetic powder cores, which can reduce losses and improve the use value of data. The magnetic and electrical properties of magnetic powder cores mainly depend on the magnetic permeability of the powder material, the size and shape of the powder, the filling factor, the content of the insulating medium, the molding pressure and the heat treatment process. In the future, soft magnetic powder cores will continue to follow high Bs, high μ, high Tc and low Pc. Magnetic powder cores are soft magnetic materials mixed with ferromagnetic powder and insulating medium. Because the ferromagnetic particles are very small (0.55μm is used for high frequency), they are separated by non-magnetic electrical insulating films. Low Hc, high frequency, miniaturization and thinness are developing to meet the growing trend of thin film, miniaturization and even integration of magnetic components.   Characteristics and Applications of Nanocrystalline Magnetic Cores   Nanocrystalline alloys have high saturation magnetic induction intensity. Good stability, the material becomes brittle after heat treatment, and is easy to process into alloy powder. It is possible to make new ultra-fine crystal magnetic powder cores with this alloy powder. The magnetic permeability of nanocrystalline magnetic powder cores is still very low compared with nanocrystalline magnetic cores wrapped with tape, and the soft magnetic properties are unstable. Problems currently waiting to be solved: 1. Effectively control the growth of nanocrystals during heat treatment; 2. The molding problem of magnetic powder cores; 3. The influence of heat treatment specifications on the soft magnetic properties of magnetic powder cores.   Application fields of nano-magnetic cores   In many power electronic devices, noise is the main source of interference in the circuit. Various filters are needed to reduce noise. As the main component of differential mode inductors, magnetic powder cores play a key role in filters. In order to obtain better filtering effects, the magnetic powder core material is required to have the following performance characteristics: high saturation magnetic induction intensity, wide constant magnetic permeability, good frequency characteristics, good AC/DC superposition characteristics and low loss characteristics. In response to the above requirements, soft magnetic materials for inductors, such as iron powder core, notched amorphous alloy core and iron-nickel-aluminum powder core (MPP powder core), have been developed one after another. These materials have their own advantages and functions under different application conditions. At present, UP powder core occupies a major share in the high-end market. However, due to the complex manufacturing process of M powder core, high raw material prices, and high powder core prices, its scope of application is subject to certain restrictions. In recent years, iron-based nanocrystalline soft magnetic powder cores have attracted much attention due to their low price, simple preparation process and excellent performance. Its research is quite active and is expected to replace the local use of UP powder cores and be applied in high-frequency fields.

That is what a transformer is - a magnetic flux is generated, which the Permalloy core uses to induce a current in another coil. This property, called hysteresis, causes energy losses in applications such as transformers. Therefore, "soft" magnetic materials with low hysteresis, such as silicon steel, are often used in the core, rather than "hard" magnetic materials used for permanent magnets. Soft iron cores increase the strength of the magnetic field inside the transformer.   Hence the eddy current losses. The core of a transformer is usually a full ring with two coils wrapped around it. One is connected to the power source and is called the "primary coil". The other powers the load and is called the "secondary coil". Soft magnetic materials and their associated devices (inductors, transformers, and motors) are often overlooked; however, they play a key role in the conversion of energy throughout the world.   The conversion of electrical power involves the bidirectional flow of energy between source, storage, and the grid, and is accomplished through the use of power electronics. Electric machines (motors and generators) convert mechanical energy into electrical energy and vice versa. The introduction of wide bandgap (WBG) semiconductors has enabled power conversion electronics and motor controllers to operate at relatively high frequencies. This reduces the size requirements for passive components (inductors and capacitors) in power electronics and enables higher-efficiency, higher-speed motors.   Several soft magnetic materials show promise for operation at high frequencies. As oxides, soft ferrites stand out from other magnetic materials because they are insulating and therefore good at reducing losses caused by eddy currents.  

Permalloy metal core: various types of Permalloy materials have their own different, more than silicon steel materials and ferrite excellent typical magnetic properties, has a high temperature stability and aging stability. High initial permeability class of permalloy material (IU79, IJ85IJ86) core is often made current transformer, small signal transformer; high rectangularity class of permalloy material (IU51) core is often made magnetic amplifier, bi-stage pulse transformer; low remanent magnetism class of permalloy material (IJ67h) core is often made small and medium power unipolar pulse transformer.   　　Permalloy core is mainly used for power energy harvesting, energy conversion, power measurement, leakage protection and so on. Such as: in the power system used in various types of different levels of current transformers, power energy harvesting transformers, current sensors and so on. With superior magnetic properties, in the weak magnetic field has the highest permeability, the bottom of the saturation magnetic susceptibility and high resistivity, consistent performance is better. Wide range of applications.   Hemei Electronics is committed to the amorphous, nanocrystalline, permalloy core products research and development, production and sales, the main products are: nanocrystalline strips, silicon steel cores, permalloy cores, high-power transformer cores, nanocrystalline toroidal inductors, take the solenoid toroidal coils, open-close inductors, common-mode inductors, precision current transformers, and other products have a good stability as well as high electrical parameters and other advantages.   　　The company has a number of vacuum heat treatment furnace, hydrogen annealing furnace, core automatic winding machine, magnetic material automatic inspection system, automatic winding machine, and other equipment and precision testing instruments. The annual output of nanocrystalline and Permalloy cores reaches more than 80 million. We can also develop customised silicon steel, nanocrystalline cores, permalloy cores and various toroidal inductors for our customers.   　　Based on the principle of ‘special core, professional, focus’, the company has established and implemented ISO9001:2008 quality management system. We believe that the establishment and implementation of the quality management system will help the company to continuously improve the quality of product management level, to establish a good corporate image and reputation in the market competition, the long-term development of the company is of great significance, to meet the majority of customers on the variety and quality of the various requirements. In the future, we will continue to work hard to promote our products to a wider range of areas of use.