high frequency transformer are the most important components of switching power supplies. Switching power supply is generally used half-bridge power conversion circuit, the work of two switching transistor turns to produce 100kHz high-frequency pulse wave, and then through the high-frequency transformer buck, the output of low-voltage AC, high-frequency transformer winding coil The number of turns determines the number of output voltage.

Typical half-bridge transformer circuit is the most prominent three high-frequency transformers: the main transformer, drive transformers and auxiliary transformers (standby transformers), each transformer in the national regulations have their own standards, such as the main transformer, As long as the power is more than 200W, the core diameter (height) shall not be less than 35mm. The auxiliary transformer, the power supply does not exceed 300W when the core diameter of 16mm is enough.

Transformer works The transformer of high frequency transformer manufacturers is the exchange of AC voltage, current and impedance of the device, when the primary coil with AC current, the core (or core) will produce AC flux, the secondary coil induced voltage (or Current).

Transformer consists of iron core (or core) and coil, the coil has two or more than the winding, which connected to the power supply winding called the primary coil, the rest of the winding called secondary coil.

High-frequency transformer is the operating frequency of more than IF (10kHz) power transformer, mainly used for high-frequency switching power supply for high-frequency switching power supply transformers, but also for high-frequency inverter and high-frequency inverter welding machine for high-frequency reverse Variable power transformer.

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In order to reduce the power loss of the common mode choke coil during high frequency tasks, the designer must be familiar with the characters that the windings play in the loss and the appropriate choice for reducing this loss. These options include the ability to obtain inductor tasks in large ripple currents with high power levels often used to reduce the loss of the metal foil winding process used. Designers have found the best inductor design with the Litz line, which is a new thing for the design process. This kind of thing promises to use the optimized number of wires and the placement of the winding position within the appropriate skeleton window to avoid some molding process.

The inductor used as a switched-mode power supply is susceptible to high-frequency ripple currents, and high frequencies can cause large resistance values ​​for useful windings. Thus, we can think of the large copper loss in the windings. The winding resistance of the switching power supply inductor is composed of two parts, including the DC resistance value and the skin effect and the proximity effect (AC) resistance value. The power loss in any magnetic device is the sum of the losses that occur in these effects. For this reason, the design of the magnetic device becomes more difficult due to the mutual influence between these effects. For example, some common approaches to reduce AC losses, such as the use of the Litz line, can greatly reduce the cross-sectional area of ​​the conductor, but also dramatically increase the dc resistance value. Copper foil winding inductors are often used to minimize winding losses in places where large DC current is used, due to the use of favorable windings in the windings window. However, even a small number of AC current can cause great loss in these copper foil rings by common mode choke manufacturers .

As the copper foil winding can be applied to the window and the occurrence of DC resistance is very small, so the copper foil winding is often forced to use. Reference 1 leads to the development of copper foil winding forming techniques with minimal copper loss and alternating copper loss. The copper foil formed with this new technique is distributed at the air gap adjacent to the current across the air gap of the air gap, and the skin effect and the near effect are minimized. The use of forming copper foil winding technology to create the inductor like Leeds wire winding has a small AC resistance, both copper foil winding the same small DC resistance. In practice, forming copper foil winding technology for high current, large ripple inductors, can minimize the loss of the winding.

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There are special common mode choke coil that are often required to be customized, which requires the calculation of the inductance. But the calculation of the amount of inductance is more complex, the general use of empirical formula.

In addition, the relationship between the inductance and the number of turns of common mode choke manufacturers to note is:

1, the inductance and the number of turns into the square ratio of the relationship, that is, the inductance and the square of the square is proportional to the number of turns per turn inductance and core size, quality.

2, if the core in the case of the same, increase the winding turns, can provide greater inductance and more abundant power, which is the advantage, but increased the internal resistance it is a disadvantage. In the case of constant winding, the sheet core has less magnetic eddy current, lower losses, through a higher frequency. But the gap is large, magnetic circuit is also long. Many people pursue low internal resistance to get better high frequency response, the pursuit of large inductance, in order to get more current to increase the sense of low frequency. "The more heat will be small, the internal resistance will become larger, the power becomes smaller, the greater the number of laps. The greater the number of turns, the greater the amount of inductance for the exchange of obstacles, so the excessive number of turns is bound to lead to output power Down and offer high current.

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In DC-DC converters, the power inductors is the core element behind the IC. By selecting the appropriate inductor, a higher conversion efficiency can be achieved. So in the choice of inductor when the corresponding inductance of the main parameters: inductance, rated current, size, etc., in these parameters also include the unique concept of the inductor. For example: power inductor rated current there are two, what is the difference between them?

Want to know the difference between them, first of all have to understand the existence of two kinds of rated current reasons of power inductors manufacturers . Power inductor rated current "based on self-temperature rise of the rated current" and "based on the rate of change in the inductance of the rated current" two decision methods, respectively, of great significance. "Rated current based on self-temperature rise" is the rated current requirement of the element's calorific value, which may cause component damage and component failure beyond this range.

At the same time, the "rated current based on the change rate of the inductance value" is the rated current requirement of the decrease in the inductance value, and the IC control may be unstable due to the increase of the ripple current when the range is exceeded. In addition, depending on the magnetic circuit configuration of the inductor, the tendency of magnetic saturation (i.e., the tendency to decrease the inductance value) is different. The figure below shows a change in the inductance value caused by the different magnetic circuit construction. For the open magnetic circuit type, with the increase of DC current, to the specified current value until the show a relatively flat inductance value, but the specified current value for the realm of the sharp decline in inductance. On the contrary, the type of closed magnetic circuit with the DC current increases, the permeability of the value gradually reduced, so the inductance value slowly decreased.

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Inductors have a variety of ways to use, according to its use, the market also appeared in a variety of inductive products. Chip inductors in accordance with the purpose of roughly divided into three categories, namely, high-frequency circuit with the inductor, power inductors (power inductors), the general circuit with inductance.

High-frequency circuit with the power inductors , that is, high-frequency inductors.

In accordance with the use of roughly divided into three categories, namely, high-frequency circuit with inductors, power inductors (power inductors), the general circuit with inductance, we can provide customers with the needs of the chip inductors.

What does high frequency inductance work by power inductors manufacturer ?

Speaking of high-frequency circuit with the inductor, as the name suggests, is used for dozens of MHz to tens of GHz high frequency band inductance. Because the Q value (Quality factor) requirements are higher, it is generally hollow structure, mainly for mobile phones and wireless LAN and other high-frequency mobile communications equipment.

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power inductors package seen three kinds of flat, I-shaped, and square closed, these kinds of packaging in the use of what is the difference?

Flat chip inductors are now more popular, because this is the power type, with a lot of. This flat chip inductor has a lot to do with our company. Shape and structure will lead to differences in product electrical characteristics, and the use of the difference is mainly based on the electrical characteristics of the device specifications. Many kinds of inductance, the type of package is not the same. Flat is generally used for high-demand products, flat or square type are mostly power-type inductors. Patch Inductors Package with zip shielded and unshielded! Flat, I-shaped is generally not shielded! Square is closed with a shield!

power inductors manufacturers and the general role of the chip is not the same, the general chip inductors in the circuit is not shielded, used in the circuit inductor can not achieve the desired effect, shielding chip inductor can shield out Some of the circuit in the current instability, a good play a blocking role, shielding the inductance of a complete metal shield will be surrounded by a positive conductor, the inside of the shield will be induced with the same amount of charged conductor negative charge, If the metal shield is grounded, the positive charge will flow into the ground, and there will be no electric field on the outside, that is, the electric field with positive conductor is shielded in the metal shield.

Shielding inductance in the circuit also played a role in coupling, shielding chip inductance In order to reduce the alternating electric field on the sensitive circuit of the coupling interference voltage, the inductance can be between the interference source and sensitive circuit set a good conductive metal shield, and Metal shield ground. The magnitude of the coupling interference voltage of the alternating electric field to the sensitive circuit depends on the product of the alternating electric field voltage, the coupling capacitance and the grounding resistance of the metal shield. As long as the metal shield to try to make a good grounding, can make the alternating electric field on the sensitive circuit coupling interference voltage becomes very small. Electric field shielding to reflect the main, so the thickness of the shield is not too large, and the structural strength as the main consideration.

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The primary and secondary ends of the primary winding of the current transformers are denoted by L1 and L2 respectively (L2 is not marked); the head end of the secondary winding is marked with K1 and K2 (or S1, S2), respectively. L1 and KI (S1) are the same polarity; L2 and K2 (S2) are the same polarity.

(1) One-time series of current transformers of current transformers manufacturers In the circuit under test, the terminals labeled L1 should be connected with the power supply. The terminals marked with L2 should be connected with the load (electrical).

For the core-type transformer, the power cord should be marked with one end of the L1 wear, through the load after the load. Power line through the transformer center hole several times, that is, a few turns, as shown in Figure 1.

(2) current meter or power meter current loop and the current transformer secondary K1 (S1), K2 (S2) phase. When connected to the current circuit of the power meter, the K1 (S1) terminal should be connected to the end of the power meter "*" (the end is referred to as the "generator side").

(3) marked with secondary K2 (S2) terminals and cores should be reliably grounded.

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1. conditions of high frequency transformer use

The terms of use include two aspects: reliability and electromagnetic compatibility. Previously only pay attention to reliability, and now due to increased awareness of environmental protection, we must pay attention to electromagnetic compatibility.

Reliability refers to the specific conditions of use, high-frequency power transformer can work until the normal life so far. General use conditions for high frequency power transformer is the greatest impact on the ambient temperature. Some soft magnetic materials, Curie point is relatively low, sensitive to temperature. For example: manganese zinc soft ferrite, Curie point only 215 ¡æ, the magnetic flux density, permeability and loss are changing with the temperature, so in addition to the normal temperature of 25 ¡æ, but also given 60 ¡æ, 80 ¡æ, 100 ¡æ when the various reference data. Therefore, the working temperature of the Mn-Zn soft ferrite core is limited to 100 ¡ã C or lower, that is, when the ambient temperature is 40 ¡ã C, the temperature rise is only allowed to be less than 60 ¡ã C, which is equivalent to the temperature of the a-stage insulating material. And Mn-Zn soft magnetic ferrite core matching magnetic wire and insulation parts, are generally used e-class and b-class insulation materials, the use of h-class insulation of the three insulated wire and polyamide film, is not a small increase in the cost of how much Is it because the h-class insulation of the high-frequency power transformer optimization design, you can make the volume reduction of 1/2 to 1/3 of the reason? If so, please give specific examples of data. The author has developed h-class insulation frequency 50hz, 10kva dry-type transformers, and b-class insulation frequency 50hz, 10kva dry-type transformers compared to the volume reduction of 15% to 20%, has been considerable.

2. Complete the function

high frequency transformer manufacturers to complete the function of three: power transmission, voltage conversion and insulation isolation. There are two ways to power transmission. The first is the transmission mode of the transformer power, the voltage applied to the original winding, the magnetic flux in the magnetic core changes, so that the secondary winding induced voltage, so that the electrical power from the original side to the secondary side. In the power transmission process, the magnetic core is divided into one-way magnetic flux changes and two-way changes in two modes of operation. In the unidirectional change mode of operation, the flux density changes from the maximum value bm to the residual flux density br, or from br to bm. Flux density change value ¦Äb = bm-br. In order to increase ¦Äb, hope bm large, br small. The two-way change mode of operation varies from + bm to -bm, or from -bm to + bm. Magnetic flux density change value ¦Äb = 2bm, in order to improve the ¦Äb, hope bm large, but does not require br small, whether it is unidirectional change mode of operation or two-way change mode of operation, the transformer power transmission mode is not directly with the core permeability related. The second is the inductor power transmission mode, the original winding input power, so that the core excitation, into magnetic energy storage, and then by demagnetization of the secondary winding induced voltage, into the power release to the load. The transmission power is determined by the inductance core energy storage, and the energy storage is determined by the inductance of the original winding. Inductance and magnetic permeability of the core, high permeability, inductance, energy storage, and not directly related to the magnetic flux density. Although the power transfer mode is different, the required core parameters are not the same, but in the high-frequency power transformer design, the core of the material and the choice of parameters is still a major design content. In the power transformer "design points" article, unfortunately, the lack of this one main content. Only in the "exchange loss" in a proposed bac typical value of 0.04 ~ 0.075t. Obviously, the text of the high-frequency power transformer is the use of inductive power transmission, why not mention the permeability, and mention bac not clear. In the "Power Technology Application" in 2003 1/2, the same main author wrote the switching power supply "design points" article, lists the "core of choice", also did not mention the permeability, but the maximum The magnetic flux density bm is 0.275 t.

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The use of an inappropriate filter destroys the signal, which has a high differential insertion loss in the signal frequency range or does not match the transmission line impedance. Therefore, do not choose the filter that will affect the signal quality before insertion.

If the transmission line does not match the impedance characteristics of the common mode choke coil signal reflection or other phenomena will occur and affect the signal quality. Signal lines related to the requirements of the requirements: 1Gps above the speed of high-speed transmission, the impedance characteristics must match.

In order to maintain the signal quality, to avoid such as voltage fluctuations, etc., it is important to select the signal frequency in the differential mode loss of small common-mode choke coil.

When the noise level is large, it is basically transmitted in the form of common mode, said the common mode choke manufacturers .

To prevent the generation of noise, the key is to use the common frequency of the common mode insertion loss of common mode choke coil.

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The division of the derating grade usually has a best derating range. In this range, the reduction of the working stress of the component has a significant improvement in the failure rate, and the design of the device is easy to achieve and does not have to pay a heavy price for the weight, volume and cost of the equipment. The derating level shall be determined based on the reliability requirements of the equipment, the maturity of the design, the cost of maintenance and the degree of difficulty, the safety requirements, and the restrictions on the weight and size of the equipment.

Three derating levels of common mode choke coil are recommended for the best derating.

A) Class I derating Class I derating is the largest derating, with the greatest improvement in the reliability of the use of components. More than its larger derating, usually improve the reliability of components is limited, and may make the equipment design difficult to achieve. Class I derating applies to the failure of equipment to cause casualties or serious damage to equipment and safeguards facilities; The equipment has a high reliability requirements, and the use of new technologies, new technology design; due to cost and technical reasons, equipment failure can not or not maintenance; the system size and weight of the equipment has harsh restrictions.

B) Class II derating Class II derating is a medium differential mode choke coil derating, with a significant improvement in the reliability of the use of components. Level II derating is easier to implement than Grade I derating. Class II derating applies to the following: failure of the equipment may result in damage to equipment and safeguards facilities; high reliability requirements and the use of certain special designs; and higher maintenance costs.

C) The III derating III derating is the smallest derating, the relative benefit of the improvement in the reliability of the use of components, but the absolute effect of reliability improvement is not as significant as Class I and II. Class III derating is the easiest to achieve in design. Class III derating applies to equipment failure and damage and damage to personnel and facilities; equipment with mature standard design.

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It is often difficult to measure the saturation characteristics of the common-mode coil core (whole or part). Morning fly electrons show that the simplicity of the test can be seen to see how much of the attenuation of the common-mode filter is affected by the amount of inductance reduction caused by the 60Hz programming current. This test requires an oscilloscope and a differential mode suppression network (DMRN). First, monitor the line voltage with an oscilloscope. According to the following method from the oscilloscope A channel input signal, the oscilloscope time base set to 2ms / div, and then the trigger signal added to the A channel, the AC voltage reaches the peak when the cable current generated, then the filter performance degradation Is the expected thing. The input of the differential mode suppression network (DMRN) is connected to the LISN and the output is matched with 50 impedance and connected to the B channel of the oscilloscope. When the common mode choke coil operates in the linear region, the B channel monitors the transmit increase of no more than 6-10 dB during the input current fluctuation. Figure 1 shows the results of this test on the oscilloscope, the above curve for the choke coils emission; the following curve for the line voltage. During the peak voltage of the line, the bridge rectifier is conducting and conducting the charging current forward.

The demultiplexer of the common mode choke of choke coils manufacturers shown on the oscilloscope due to the 60 Hz charge current.

If the common mode choke is saturated, the emission will increase as the input surge increases. If the common mode choke reaches strong saturation, the emission intensity is the same as when the filter is not applied, that is to say it is easy to achieve more than 40dB.

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Toroidal transformer is a large type of electronic transformers, has been widely used in home appliances and other technical requirements of higher electronic equipment, it

Here is a brief introduction to the advantages of toroidal transformers

1. High efficiency of the core without air gap, stacking coefficient can be as high as 95% or more, the core permeability desirable 1.5 ~ 1.8T (laminated core can only take

1. 2 ~ 1.4T), electrical efficiency as high as 95% or more, no-load current is only 10% of laminated.

2. Small size, light weight Toroidal transformer of toroidal transformers manufacturer than the stacked-type transformer can reduce the weight of half, as long as the core to keep the same cross-sectional area, the ring

Shape transformer easy to change the core length, width, height ratio, you can design to meet the requirements of the external dimensions.

3. Small magnetic interference ring transformer core without air gap, winding evenly around the ring in the core, this structure has led to a small magnetic leakage, electricity.

4. Vibration and noise smaller core can not reduce the core air gap.

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Assuming a differential input inductance of the power supply asymmetry (that is, there are some differences in the sense of a hypothetical 100uH, a 60uH) what will be the problem? Its ability to suppress the differential mode signal is reduced?

differential mode choke coil asymmetry will produce the following situation Assumption 1: The original circuit of the differential mode inductance value of 60uH, has to meet the requirements of the circuit. (Provided that the magnetic properties of the core used, the same size specifications)

While the actual one is 100uH,

1, according to impedance theory, Z = 2 * π * F * L

The higher the inductance, the higher the impedance, the stronger the ability to suppress clutter. A high inductance value is perfectly desirable for the filtering effect.

2, according to the anti-saturation capacity calculation, H = 0.4π * N * Ie / Le

Core magnetic properties of choke coils manufacturers , size specifications under the same conditions, the core of the anti-saturation capacity needs to be considered. If the actual application conditions in the circuit, assuming that the core saturation, magnetic permeability decays to very low inductance drop is very low. Then the impedance will drop very low. On the differential mode signal can not be suppressed, or inhibit the ability to drop a lot. So that EMI detection is unable to meet the requirements.

Assumption 2: The original value of the differential mode inductance of the circuit is 100uH, has already met the requirement of the circuit. (Provided that the magnetic properties of the core used, the same size specifications) While the actual one is 60uH,

1, according to impedance theory, Z = 2 * π * F * L

The lower the inductance, the lower the impedance and the poorer the ability to suppress clutter. Then the effect of filtering the noise of the differential mode signal is deteriorated. So EMI detection is unable to meet the requirements.

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A lot of people who have not been in contact with inductance, in the differential mode choke coil and common mode inductance is always confused between the two today to simply talk about what is the differential mode inductor, what role it has, the differential mode inductance in the AC frequency of a certain Case, the greater the inductance, the greater the ability to block the AC, the smaller the inductance, the less the ability to hinder. In addition, a certain amount of inductance in the case, the higher the frequency of AC, the inductance of the obstruction of the AC capacity is also greater, the lower the frequency, the inductance of AC impede the smaller capacity. In other words, the inductor has a characteristic of preventing the passage of the alternating current and allowing the direct current to pass therethrough.

The ideal inductor is a pure common mode choke coil , it is not a capacitor component allows the AC through, there is no resistance to allow direct current through, there is no loss, then regardless of its inductance size, can completely prevent the passage of AC. Inductance has an impediment to AC. In the case of a certain frequency of AC, the greater the inductance, the greater the ability to impede the AC, the smaller the inductance, the smaller the obstruction. In addition, a certain amount of inductance in the case, the higher the frequency of AC, the inductance of the obstruction of the AC capacity is also greater, the lower the frequency, the inductance of AC impede the smaller capacity. In other words, the inductor has a characteristic of preventing the passage of the alternating current and allowing the direct current to pass therethrough.

The ideal inductor is a pure inductor, it is not a capacitor component allows the AC through, there is no resistance to allow direct current through, there is no loss, then regardless of its inductance size, can completely prevent the passage of AC.

But this inductance is not. Because of this, the inductor has been applied. We can use the inductor in the rectifier circuit, because we want to get a powerful DC power supply, you must use the rectifier circuit to AC power into the DC we need. And because the DC rectifier is not pure DC, it contains a lot of AC components, which we do not want, so we can put inductors in series rectifier circuit, the rectifier out of the DC through the inductor, the AC component It is greatly reduced.

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According to the report, since 2000, due to urban and rural power grid renovation project pulling, distribution transformer market capacity to achieve a steady growth. Distribution transformer in the proportion of the transformer has reached more than 40%. Distribution transformer annual output has increased year by year, the next few years, power grid construction and urban and rural distribution network transformation is still the primary task of China's power industry. The State Council decided to implement a new round of rural power grid upgrading project. Two-thirds of the funds will be used to purchase power transmission equipment. amorphous transformer manufacturers is expected to maintain a strong momentum of development.

amorphous transformer is the use of amorphous silicon steel sheet instead of the manufacture of the transformer. Its outstanding feature is the low no-load loss, no-load current is small, with the same type of S9 series transformer no-load loss decreased by 70% -80%, no-load current 40% -60% reduction in load loss by 20% -30 %, Therefore has the very big energy conservation effect.

In summary, energy-saving become the mainstream industry trends, such as dry-type transformers SCB10 series and amorphous alloy core and other low-loss products have shown the energy-saving potential of China's distribution transformers. Amorphous transformer energy-saving effect, economic benefits, in the distribution network applications will be able to effectively reduce the loss of the distribution network, in line with national industrial policies and power grid energy saving requirements, is expected to become the future transformer market leading products.

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①, the original transformer, the secondary coil is concentrically set in an iron core column, within the low-voltage winding, high voltage winding. (Welding machine transformer original, secondary coil were installed in two core column)

Transformer in the load operation, when the secondary current increases, the transformer core to maintain the main flux unchanged, the primary current must also be increased accordingly to achieve the balance of secondary current.

Transformer secondary active power general = transformer rated capacity (KVA) × 0.8 (transformer power factor) = KW.

②, power transformers SMPS transformers are:

A, moisture absorber (silica gel tube): Contains silica gel, oil conservator (oil pillow) in the insulating oil through the absorber and atmospheric connectivity, desiccant absorbs moisture and impurities in the air to keep the transformer internal windings good Insulation; silicone discoloration, metamorphism easily lead to blockage.

B, oil level meter: reflect the toroidal transformers for audio oil level state, generally around +20 O, too high to put oil, too low fuel; winter temperature is low, the load light little change in oil level, or a slight decline in oil level; In summer, when the load is heavy, the oil temperature rises and the oil level rises slightly; both are normal.

C, oil pillow: oil tank adjustment, to prevent excessive oxidation of transformer oil, the upper part of the oil hole.

D, explosion-proof tube: to prevent sudden accidents caused by the explosion of fuel tank pressure accumulation.

E, signal thermometer: monitor the transformer operating temperature, send a signal. Indicating the upper transformer oil temperature, transformer coil temperature higher than the upper oil temperature 10 ℃. GB standard: the limit of the transformer winding operating temperature of 105OC; (that is, the ambient temperature of 40OC), the upper temperature should not exceed 95OC, usually to monitor the temperature (upper oil temperature) set at 85OC and below appropriate.

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High-frequency transformers as the most important part of switching power supply, high-frequency transformer winding turns of each winding ratio determines the number of output voltage. It is the frequency of more than the frequency of the power transformer, mainly for high-frequency switching power supply for high-frequency switching power supply transformers.

High-frequency transformer (audio toroidal transformer )is as the most important part of switching power supply. Switching power supply is generally used half-bridge power conversion circuit, the work of two switching transistor turns on to produce 100kHz high-frequency pulse, and then through the high-frequency transformer buck, the output of low-voltage alternating current, high-frequency transformer winding coil Of the turns ratio determines the output voltage of the number.

In the high-frequency transformer design from high frequency transformer manufacturers, the transformer leakage inductance and distributed capacitance must be minimized, because the switching power supply in the high-frequency transformer is a high-frequency pulse square wave signal transmission. During transient transients, leakage inductance and distributed capacitance can cause inrush current and spike voltage, as well as top oscillation, resulting in increased losses. Usually the transformer leakage inductance, the control of the primary inductance of 1% to 3%.

The leakage inductance of the primary coil is caused by the incomplete coupling of the magnetic flux between the primary and secondary windings, between the layers and the layers, and between the turns and the turns.

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Relevant index showed last week, the PFC inductors price index showed a surprising increase, following the previous period rose 5.86%, the current index is still in the electronic components segment price increase in the "reelected" first week price index of 87.07 weeks Up 6.65, week up to 8.27%. Two weeks cumulative increase of 14.61%. Inductors "Global Electronic Components 150 Index" also shows that the global inductor listed company's current stock price index for the 603.0, the value of 5.62, up 0.94%. Industry fundamentals for the better.

In the last Tuesday has released special tips for the coil, common mode chokes price index changed in the first half of the decline in the last period of electronic components breakdown of the categories of price increases in the first week or up to 5.86%. Due to the impact of electronic components supply cycle, the inductor price index is generally in the first and second quarters of the annual low, gradually began to pick up in the third quarter. Tuesday (July 1) has entered the first quarter of the third quarter, the industry accordingly believe that the inductor price index rose sharply is a cycle price inflection point of the signal; and as supply and demand changes, the global semiconductor industry has entered the boom cycle, Inductors in the future the price or will continue to rise.

www.xp-elec.com specializes in the development, production and sales of passive electronic components such as inductors, transformers, cores and coils. Fenghua Hi-Tech 000636.SZ) has recently invested in small multi-layer ceramic capacitors, Layer ceramic capacitors, chip resistors and chip inductors of capacity upgrades and technological transformation projects.

Toroidal Transformers is mainly used as a power transformer and isolation transformers. Toroidal transformer at home and abroad have a complete series, widely used in medical equipment, telecommunications, instrumentation, photovoltaic power generation and lighting, and so on. Ring transformer because of excellent cost performance, good output characteristics and anti-jamming capability.

Large isolation transformers power high-grade toroidal transformer can be customized power transformer contact voltage regulator

toroidal transformers is based on the choice of materials in the production, based on the actual production of the majority of the actual market because of cost pressures and competitive needs, not strictly according to industry specifications, and sometimes even jerry-building, analysis of unpredictable factors more. The first is the core material quality, many enterprises with low permeability core, trimmed and even mixed with soft iron production transformer, resulting in transformer no-load current is high, iron loss is too large, no-load fever serious; this type of transformer to reduce Cost, at the same time to cover the high iron loss caused by the voltage regulation rate is too large to significantly reduce the number of primary and secondary coil turns to reduce the way the copper loss to reduce the voltage regulation, this approach further increases the no-load Current, and no-load current is too large will directly lead to increased magnetic leakage.

toroidal transformers manufacturers problems more complex. Regular ring-type transformer core is a wide-width silicon steel band from a tight winding. Or for cost reasons, the majority of low-cost ring-type transformer with several or even dozens of silicon steel stitching, and even use the edge of the uneven scraping, winding machine after the car flat, the ring transformer coil package Around the core, do not do destructive anatomy difficult to find. Mechanical processing of silicon material on the lattice, the insulation between adjacent silicon steel has serious damage, such ring-shaped transformer regardless of performance or leakage magnetic properties will be greatly reduced, even after annealing can not make up for serious quality defects .

Another need to pay attention to the interference source for the rectifier circuit. Filter capacitor in the boot into the normal state, the charge is only concentrated in the AC peak, the charge waveform is a narrow width of the strong pulse, the greater the capacity, the greater the pulse intensity, from the electromagnetic interference point of view, the filter capacitor is not the greater the more Good, rectifier and filter capacitor wiring between the lines should be shortened, while away from the amplifier circuit, PCB space is not allowed to try to use the ground line envelope.

XP Power (China) is a professional toroidal transformers manufacturer with over 20 years' experience.The official website is www.xp-elec.com

With the popularization and development of the digital circuits of switching power supply, the electromagnetic waves radiated and leaked by electronic devices not only seriously interfere with the normal operation of other electronic devices, leading to equipment malfunction, transmission errors and control failures, but also threat to human health and safety. Become an invisible pollution, not inferior to the water, air, noise and other tangible pollution hazards. Therefore, reducing the electromagnetic interference (EMI) of electronic equipment has become the world's electronics industry concerns.

Anti - interference line filters characteristics

There is a conceptual difference between an anti-jamming filter and a conventional signal filter. Signal filter in the impedance matching conditions, that is, through the filter to maintain the input and output signal amplitude does not change the premise that part of the frequency domain for the expected processing and transformation. While the EMI filter is used to suppress the electromagnetic interference from entering the equipment and from the equipment, with bidirectional suppression. So this requires the EMI filter at the port and the device to produce the greatest mismatch. So as to make the filter attenuation of electromagnetic interference equal to the attenuation of their own network coupled with the input and output ports of reflection, must follow the following rules. Where Rs is the input impedance of the grid and varies with the amount of charge; RL is the output impedance of the EMI filter, which varies with the load size.

Selection of common mode choke coil Material in EMI Filter

Reduce the electronic equipment of electromagnetic interference has become a key issue whether the electronic products market. The soft magnetic materials have become EMI filter essential components, and plays a pivotal role. Now with the soft magnetic materials made of various suppression EMI components are widely used in various electronic circuits and equipment. This is because the soft magnetic material has its unique performance, resulting in the field of anti-electromagnetic interference play a major role. However, it is unrealistic for electronics manufacturers to expect universal EMI filters to reduce interference to below standard for all electronic devices. EMI filter design should be based on the EMC standards for electronic equipment, that is, need to attenuate the EMI signal frequency range and the level of excessive levels to select, in particular, the soft magnetic materials.

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