CN103065771A - Method for increasing air gap magnetic core inductance coefficient - Google Patents
Method for increasing air gap magnetic core inductance coefficient Download PDFInfo
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Abstract
The invention discloses a method for increasing air gap magnetic core inductance coefficient. The method includes: forming a magnetic core by combining more than two magnetic core bodies, adopting the mirror surface process for a joint surface passed by magnetic flux, filling a proper quantity of magnetic liquid on mirror surfaces after a coil is wound, and assembling the coil and the magnetic core together, so that the integral magnetic core inductance coefficient can be above 80%. A transformer or an inductor made of the magnetic core using the method is small in size and is simple in winding process.
Description
Technical field
The present invention relates to magnetic core, particularly improve the method for air gap magnetic core inductance coefficent.
Background technology
Magnetic core: magnetic core refers to a kind of sintering magnetic metal oxide by various iron oxide compositions of mixtures.The purposes of magnetic core is extremely wide, since the eighties in last century, the computer power supply round Realization Switching Power Supply, take the lead in finishing the power supply replacement of computer, enter the nineties in last century Switching Power Supply and in succession enter various electronics, electric equipment field, stored-program control exchange, communication, electron detection device power supply, control appliance power supply etc. have all used Switching Power Supply widely, in the household electrical appliance, all adopt the Switching Power Supply power supply as colour TV, router, cell-phone charging etc., more promoted developing rapidly of switch power technology, magnetic core technology.
In so many Switching Power Supplies, requirement to magnetic core also is different, in the common anti exciting converter (FLY-BACK) of picture, just need to open a relatively large air gap to magnetic core and come storage power, adjusting inductance reaches designing requirement simultaneously, as some Switching Power Supplies with harmonic technology work, such as anti-sharp quasi resonant convertor, or the LLC controlled resonant converter, all need to regulate air gap and obtain suitable inductance value.
Some Switching Power Supplies and other purposes are also arranged, and magnetic core is not need air gap when work, such as the self-oscillation push-pull transistor single phase transformer DC converter of nineteen fifty-five U.S. Luo Ye (G.H.Royer) invention, also makes the Royer circuit; And nineteen fifty-seven U.S.'s auto-excitation type of looking into match (Jen Sen, some places translations " well is gloomy ") invention recommend the dual transformer circuit, after be called as self-oscillation Jensen circuit or Jensen circuit; These two kinds of circuit, the descendant is referred to as self-excited push-pull type transducer.The related work principle of self-excited push-pull type transducer has description in " principle of Switching Power Supply and the design " the 67th page to 70 pages of Electronic Industry Press, this book ISBN 7-121-00211-6.The principal mode of circuit is above-mentioned famous Royer circuit and self-oscillation Jensen circuit.
The characteristics of above-mentioned Royer, Jensen circuit are: utilize the magnetic core saturation characteristic to carry out push-pull oscillator, the transformer output waveform is approximate square wave, and the conversion efficiency of circuit is higher.Magnetic core will be at specific time instant near saturation condition, so can't adopt the magnetic core that has air gap.Above-mentioned self-excited push-pull type transducer is essential to use the magnetic saturation type magnetic core, and magnetic core to add air gap be known anti-magnetically saturated means.
Another kind does not utilize the magnetic core saturation characteristic to carry out the self-excited push-pull type transducer of push-pull oscillator, nineteen ninety publishes in the People's Telecon Publishing House, the 57th page to 70 pages of " power conversion technology " that Wang Guiying writes have description, and this book is for ISBN number 7-115-04229-2/TN353.The 3rd section second row (the third line on Fig. 2-28) of 57 page of the 3rd joint mentioned in this book: transformer is operated in unsaturated state, and the volume ratio of transformer is larger.
Self-excited push-pull type transducer is in present field of switch power, because in small-signal model, unique ac small signal input impedance is positive power supply, and the ac small signal input impedance of other Switching Power Supply is for negative, it is extremely inconvenient when ac small signal input impedance is used for negative switch power parallel, the ac small signal input impedance of self-excited push-pull type transducer is being for just, and is in parallel, cascade is extremely easy to use, so be used widely.2011, global industrial circle newly promoted in 7,000 ten thousand self-excited push-pull type transducer micropower power supply modules, almost all adopted the magnet ring coiling transformer of magnetic circuit closure.Magnetic circuit described here is closed, also makes flux closure, refers to that magnetic flux all passes in the magnetic material, does not pass through the medium as air of utmost point low permeability.
For another example, as network transformer, such as the RJ45 integrated transformer that Ethernet is used, interface transformer also is what to adopt without the magnet ring coiling of air gap.
For another example, high-quality common mode inductance (Common mode Choke) also is common mode choke, and some documents are again the conjugation inductance, also is without the magnet ring coiling of air gap, to obtaining the maximum induction amount; Common mode inductance also has pair performance requirement not high, employing minute surface magnetic core combination coiling.Fig. 1 shows the structure chart of the classical magnet ring of this class, and Fig. 2 is the square magnetic hysteresis loop of this magnetic core, wherein+and B
m,-B
mBe two saturation point of magnetic core, in fact, this curve is near rectangle, and Fig. 2 diminishes the unit scales of transverse axis H in order clearly to see curve clearly, and figure has been elongated in the transverse axis horizontal direction.
Fig. 3 shows magnetic core and opens magnetic hysteresis loop figure behind the air gap, and the solid line of " air gap is arranged " indication among Fig. 3 is the magnetic hysteresis loop after very little air gap left by magnetic core corresponding to Fig. 1; The dotted line of " without the air gap " indication among Fig. 3 is for the magnetic hysteresis loop of contrast usefulness, and is identical with Fig. 2.Common mode inductance also has employing minute surface magnetic core combination coiling, and its magnetic hysteresis loop is exactly the solid line of " air gap is arranged " indication of indication among similar Fig. 3.
In actual the use, measuring magnetic hysteresis loop is a test very time-consuming, that cost is very high.The general performance that all reflects magnetic core with inductance coefficent, inductance coefficent is denoted as AL, and inductance coefficent is the physical quantity that coil gauge produces the electromagnetic induction ability, a magnetic core, behind the conductor wire of a upper fixing turn, its inductance value=inductance coefficent * wire circle square is denoted as:
L is the inductance value that magnetic core coil is arranged, and AL is inductance coefficent, and N is wire circle, so:
Can find out from formula (2), the measurement of inductance coefficent is thing easily, when wire circle is a circle, measure the inductance value that comes and be inductance coefficent AL, certainly, the measure error of a circle coil own is larger, the general multiturn that adopts is measured, and calculates inductance coefficent AL again.
With inductance coefficent to compare, just can reflect the degree near " without air gap " magnetic hysteresis loop of the magnetic hysteresis loop that " air gap arranged " among Fig. 3 without the magnetic core of air gap and the magnetic core of opening air gap.
Known technology is thought, opened after the air gap, coercive force and saturation point are constant, but reaching the required H value of saturation point sharply increases, be the electric current increase in the coil, this needs thicker enamelled wire come the coiling transformer, otherwise original enamelled wire can't bear larger electric current, so, the cost of transformer and volume all can increase; Reach the required H value of saturation point and sharply increase, another method is that the coil institute coiling number of turn of transformer is multiplied, and same, the number of turn is multiplied, and brings internal resistance to increase, and loss increases, the decrease in efficiency of self-excited push-pull type transducer.The reason that this " power conversion technology " " transformer is operated in unsaturated state, and the volume ratio of transformer is larger " of mentioning that also be above-mentioned produces.
The shortcoming of magnet ring in above-mentioned application that Fig. 1 illustrates flux closure is the coiling difficulty:
Comprise the used transformer of Royer circuit and Jensen circuit, network transformer, high-quality common mode inductance, all be magnetic core coiling transformer or the inductance that adopts without air gap, the coiling of general employing magnet ring, because flux closure, enamelled wire all will pass the hole in the middle of the magnet ring during coiling, and this brings very large difficulty to coiling, at present coiling enamelled wire of multiturn so on less than the bead of 10mm to 35mm diameter, no matter be machine coiling or manual coiling, all have processing difficulties.
And employing has the magnetic core coiling of air gap, technique for coiling is very simple, but exist the volume ratio of transformer larger, this has description previously described " power conversion technology " the 57th page to 70 pages, from the micropower power supply module of annual nearly 7,000 ten thousand self-excited push-pull type transducers that increase newly of global industrial circle, can find out, unsaturation formula self-excited push-pull type transducer transformer is not applied owing to volume and above-mentioned reason yet.Network transformer, high-quality common mode inductance still adopt the magnet ring coiling of flux closure, and annual total amount is at several hundred million.
At present, comprise the magnet ring of flux closure and adopt the related application of minute surface magnetic core that Shortcomings all is summarized as follows:
1) shortcoming of the magnet ring of flux closure is the coiling difficulty;
2) volume ratio of the transformer of employing minute surface magnetic core, network transformer, high-quality common mode inductance is larger;
If find a kind of method, adopt air gap magnetic core coiling transformer or inductance, and its inductance coefficent approaches more than 80% of flux closure magnetic core without air gap, just can realize that transformer or inductance volume are little, coiling is simple.
Summary of the invention
In view of this, the present invention overcomes above-mentioned deficiency, and a kind of method that improves air gap magnetic core inductance coefficent is provided so that air gap magnetic core inductance coefficent approach without the flux closure magnetic core of air gap more than 80% or reach 100%, just can realize that transformer or inductance volume are little, coiling is simple.
The objective of the invention is to be achieved through the following technical solutions:
For solving the problems of the technologies described above, the invention provides a kind of method that improves air gap magnetic core inductance coefficent, it is characterized in that: magnetic core is that two above monomer magnetic materials combine, and the faying face of magnetic flux process is minute surface, minute surface combines the adhesion that produces at 4.3N/cm
2Above, minute surface junction air gap is filled up with magnetic liquid.
Preferably, above-mentioned magnetic liquid is that nano magnetic particle is dispersed in the stable colloidal solutions that forms in the carrier fluid, and the saturation flux density of magnetic liquid is more than 180 Gausses;
Preferably, the saturation flux density of above-mentioned magnetic liquid is more than 2000 Gausses.
Operation principle of the present invention is, the method in the technique scheme, and magnetic core is that two above monomer magnetic materials combine, like this, just can wind transformer at skeleton, or consist of coil with the Copper Foil cabling on the circuit board, load onto again each magnetic material from the circuit board both sides.The faying face of magnetic flux process is minute surface.Minute surface---former is the tidemark of metal cutting processing, has continued to use this vocabulary on the magnetic core, refers to that the magnetic core surface obtains extraordinary roughness, and the clear inverted image of energy goes out the magnetic material surface of article image.When the minute surface magnetic core generally is magnetic core respective surfaces roughness＜0.8um surperficial, be called the minute surface magnetic core, which kind of no matter with processing method process, always stay fine scraggly vestige at the magnetic core finished surface, the staggered peak valley phenomenon that rises and falls occurs, good minute surface combines the adhesion that produces at 4.3N/cm
2Above, this adhesion comes from the molecular attraction on both sides, minute surface junction, this is the technique upper limit of present minute surface magnetic core, the existence of molecular attraction illustrates that the magnetic domain of negligible amounts connects together, because very little, there are some magnetic fluxs to exist, this part magnetic domain that connects together will be saturated, and saturated rear this part magnetic domain that connects together and air are as broad as long, and air gap appears in magnetic core again.
From the atomic structure viewpoint of material, the interaction that causes because of spin between the interior electronics of magnet matter is very strong, and under this effect, ferromagnetics inside has formed some small spontaneous magnetization zones, is called magnetic domain.
Because realize that the saturated winding current of this magnetic domain is too little, the air gap of the magnetic core of prior art still works, its inductance coefficent AL is still lower.The minute surface degree is higher, and the gravitation of faying face is larger, but the methods such as grinding can't further strengthen this adhesion, and still there is air gap in its faying face, is still scraggly vestige after the amplification, the staggered peak valley phenomenon that rises and falls occurs, thereby produces air gap.Therefore the inductance coefficent AL of magnetic core is still lower, and the magnetic domain on both sides, minute surface junction still is in separately operating state.
The method that technical scheme of the present invention is taked: it is characterized in that: magnetic core is that two above monomer magnetic materials combine, and the faying face of magnetic flux process comprises the side, is minute surface, and minute surface combines the adhesion that produces at 4.3N/cm
2Above, magnetic core minute surface junction air gap is filled up with magnetic liquid.Magnetic liquid is that nano magnetic particle is dispersed in the stable colloidal solutions that forms in the carrier fluid, it is a kind of functional material that has simultaneously magnet magnetic and liquid fluidity, filled up minute surface junction air gap with magnetic liquid, select suitable magnetic liquid, nanoscale magnetic material in the magnetic liquid has connected the magnetic domain of air gap both sides, so that the magnetic domain quantity of interconnection is very big, also can be understood as magnetic liquid and filled up scraggly little space in the air gap, thereby so that the magnetic core after the combination can easily be realized magnetic saturation, be that magnetic core just can produce larger magnetic flux with less exciting current, its inductance coefficent AL approaches more than 80% of flux closure magnetic core without air gap, reach the effect of rectangular hysteresis loop, thereby realize realizing with Combined type magnetic core the effect of whole magnetic core.
Owing to having used two above magnetic materials to combine, it is simple that the coiling of transformer or inductance seems, after finishing, coiling is loaded on magnetic core, after further adopting magnetic liquid to fill up processing, promoted the inductance coefficent of magnetic core, making it to reach has inductance coefficent air gap, the flux closure magnetic core more than 80%, and compared with prior art, the present invention has following significant effect:
(1) coiling is simple
Owing to having used two above magnetic cores to combine, the coiling of transformer or inductance seems and simply is loaded on magnetic core after coiling is finished; Or directly design winding at circuit board, and directly load onto magnetic core after processing circuit board, so transformer winding technique is simple, save man-hour;
(2) core volume of the present invention is smaller
This has benefited from the inductance coefficent that the present invention can significantly improve magnetic core.
(3) efficient further promotes
This has benefited from the inductance coefficent that the present invention can significantly improve magnetic core, so that core volume is smaller, and iron loss smaller (iron loss is directly proportional with volume), in addition, the number of turn of coiling reduces, and the enamelled wire total length reduces, its internal resistance also reduces, and copper loss also reduces, thereby promotes overall efficiency.
Description of drawings
Fig. 1 is the magnet ring type magnetic core in the magnetic circuit closed magnetic core;
Fig. 2 is the square magnetic hysteresis loop figure of magnetic circuit closed magnetic core;
If being magnetic core corresponding to Fig. 2, Fig. 3 opens magnetic hysteresis loop and original comparison diagram behind the very little air gap;
Fig. 4 is the first embodiment magnetic core schematic diagram;
Fig. 5 is the second embodiment magnetic core schematic diagram;
Fig. 6 is the Combined type magnetic core schematic diagram of the another kind of execution mode house transformer of the second embodiment.
Embodiment
Embodiment one
Fig. 4 is the first embodiment magnetic core schematic diagram, adopts comparatively common ER7.5 magnetic core, and the magnetic material derives from the more P4 of peak electronic material limited company, outward appearance as shown in Figure 4, six faces of 22 indications are minute surfaces.
Before the coil that winds is buckled the magnetic core of Fig. 4, on 3 minute surfaces of a magnetic core, drip respectively an amount of magnetic liquid, the model of magnetic liquid is the LD2020 of golden section, and its saturation flux density is about 200 Gausses.
Simultaneously, use homemade magnetic liquid, adopted the magnetic material of high magnetic permeability, behind the sintering, grind into powder, and filter out the following magnetic of 500 orders, loud speaker is with among the magnetic liquid LD2003 preferably to sneak into flowability, and the control mixed volume makes the saturation flux density of mixed magnetic liquid get final product in 2000 Gausses.
Annotate: order refers to the empty eye number on the screen cloth per square inch, and 50 orders just refer to that every square of eyelet on the English inch is 50, and 500 orders are exactly 500, and the order number is higher, and eyelet is more.Except the eyelet of expression screen cloth, it is used for the particle diameter that expression can be passed through the particle of screen cloth simultaneously, and the order number is higher, and particle diameter is less.500 orders of our country refer to 25 microns of particle diameters.The magnet that particle diameter is 25 microns, the magnetic domain of the spontaneous magnetization that is in fact caused by the interior electron spin of a lot of magnet matter forms, and they are subjected to external force can be separated into a plurality of magnetic domains in magnetic liquid and reassemble into a large magnetic domain.
Do not have at present with the magnetic core profile whole magnetic core identical with volume that Fig. 4 combines, compare test so the implementation result of the first embodiment is bad, therefore adopt computer that whole magnetic core is carried out magnetic emulation, the emulation out inductance coefficent AL of whole magnetic core is about 5.08uH.
Beneficial effect of the present invention has been tested three kinds of circuit here identical for convenience of description, and three kinds of schemes that the magnetic core assembly method is different: the first, computer are carried out the result of magnetic emulation to whole magnetic core; The second, prior art, what does not all add in the middle of the ER7.5 magnetic core of Fig. 4, the third, one of first embodiment adopts saturation flux density to fill up the minute surface junction at 200 Gausses' magnetic liquid, the 4th kind, two of the first embodiment adopts saturation flux density to fill up the minute surface junction at 2000 Gausses' magnetic liquid.
Test result is referring to table one.
Can see from upper table, magnetic liquid is filled up the minute surface junction can realize goal of the invention really, add 200 Gauss's magnetic liquid and can realize that inductance coefficent AL reaches more than 80% of theoretical value, and after adopting 2000 Gauss's magnetic liquid, this value has further improved, be equivalent in Fig. 3, " air gap is arranged " this magnetic hysteresis loop is more near " without air gap " this magnetic hysteresis loop.
Embodiment two
Fig. 5 is the second embodiment magnetic core schematic diagram, in order to contrast conveniently, adopts comparatively common ER7.5 magnetic core and an I type magnetic core to combine, and the magnetic material derives from the P47 that gets over peak electronic material limited company, outward appearance as shown in Figure 5,4 faces of 22 indications are minute surfaces.
Before the coil that winds is buckled the magnetic core of Fig. 5, on 3 minute surfaces of a magnetic core, drip respectively an amount of magnetic liquid, the model of magnetic liquid is the LD2020 of golden section, and its saturation flux density is about 200 Gausses.
Simultaneously, use homemade magnetic liquid, adopted the magnetic material of high magnetic permeability, behind the sintering, grind into powder, and filter out the following magnetic of 500 orders, loud speaker is with among the magnetic liquid LD2003 preferably to sneak into flowability, and the control mixed volume makes the saturation flux density of mixed magnetic liquid get final product in 2000 Gausses.
Do not have at present with the magnetic core profile whole magnetic core identical with volume that Fig. 5 combines, compare test so the implementation result of the second embodiment is bad, therefore adopt computer that whole magnetic core is carried out magnetic emulation, the emulation out inductance coefficent AL of whole magnetic core is about 5.60uH.
Beneficial effect of the present invention has been tested three kinds of circuit here identical for convenience of description, and three kinds of schemes that the magnetic core assembly method is different: the first, computer are carried out the result of magnetic emulation to whole magnetic core; The second, prior art, what does not all add in the middle of the ER7.5 magnetic core of Fig. 5 and the I type magnetic core, the third, one of second embodiment adopts saturation flux density to fill up the minute surface junction at 200 Gausses' magnetic liquid, the 4th kind, two of the second embodiment adopts saturation flux density to fill up the minute surface junction at 2000 Gausses' magnetic liquid.
Test result is referring to table two.
Can see from upper table, magnetic liquid is filled up the minute surface junction can realize goal of the invention really, add 200 Gauss's magnetic liquid and can realize that inductance coefficent AL reaches more than 81% of theoretical value, and after adopting 2000 Gauss's magnetic liquid, this value has further improved, be equivalent in Fig. 3, " air gap is arranged " this magnetic hysteresis loop is more near " without air gap " this magnetic hysteresis loop.
Obviously, I type magnetic core is changed into two, or other form that changes into of ER7.5, equally can realize the object of the invention.Fig. 6 shows this application, I type magnetic core changes two a little bit smaller I type magnetic cores into, and its downward face is minute surface, and these two can be adopted different magnetic materials, press the direction of arrow among the figure and following ER magnetic core assembling gets final product, magnetic liquid can be realized the object of the invention after filling up the minute surface junction equally.
Only be preferred implementation of the present invention below, should be pointed out that above-mentioned preferred implementation should not be considered as limitation of the present invention, protection scope of the present invention should be as the criterion with the claim limited range.For those skilled in the art, without departing from the spirit and scope of the present invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (7)
1. method that improves air gap magnetic core inductance coefficent, it is characterized in that: described magnetic core is that two above magnetic cores combine, and the faying face of magnetic flux process is minute surface, and described minute surface junction air gap is filled up with magnetic liquid.
2. method according to claim 1, it is characterized in that: described magnetic liquid is that nano magnetic particle is dispersed in the stable colloidal solutions that forms in the carrier fluid.
3. method according to claim 1 and 2, it is characterized in that: the saturation flux density of described magnetic liquid is more than 180 Gausses.
4. method according to claim 1 and 2, it is characterized in that: the saturation flux density of described magnetic liquid is more than 2000 Gausses.
5. method according to claim 1 and 2 is characterized in that: wind transformer at skeleton, and then load onto described magnetic core; Or with the formation of the Copper Foil cabling on circuit board coil, load onto described magnetic core from described circuit board both sides again.
6. method according to claim 3 is characterized in that: wind transformer at skeleton, and then load onto described magnetic core; Or with the formation of the Copper Foil cabling on circuit board coil, load onto described magnetic core from described circuit board both sides again.
7. method according to claim 4 is characterized in that: wind transformer at skeleton, and then load onto described magnetic core; Or with the formation of the Copper Foil cabling on circuit board coil, load onto described magnetic core from described circuit board both sides again.
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Citations (7)
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|---|---|---|---|---|
| JPH02187006A (en) * | 1989-01-13 | 1990-07-23 | Mitsubishi Electric Corp | Magnetic circuit of transformer |
| US5204653A (en) * | 1990-01-22 | 1993-04-20 | Tabuchi Electric Co., Ltd. | Electromagnetic induction device with magnetic particles between core segments |
| US20040090300A1 (en) * | 2000-11-17 | 2004-05-13 | Epcos Ag | Ferrite cores with a new shape |
| CN201397730Y (en) * | 2009-04-14 | 2010-02-03 | 东莞市同和实业有限公司 | Network transformer for communication networks |
| CN101651017A (en) * | 2009-01-14 | 2010-02-17 | 郑州乾新电子有限公司 | Liquid-magnetism filled high-frequency transformer |
| CN201788793U (en) * | 2010-09-10 | 2011-04-06 | 郭惠成 | Inductor iron core |
| CN201893232U (en) * | 2010-08-04 | 2011-07-06 | 湖北天瑞电子有限公司 | Open type current transformer |
-
2013
- 2013-01-04 CN CN201310003062.3A patent/CN103065771B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02187006A (en) * | 1989-01-13 | 1990-07-23 | Mitsubishi Electric Corp | Magnetic circuit of transformer |
| US5204653A (en) * | 1990-01-22 | 1993-04-20 | Tabuchi Electric Co., Ltd. | Electromagnetic induction device with magnetic particles between core segments |
| US20040090300A1 (en) * | 2000-11-17 | 2004-05-13 | Epcos Ag | Ferrite cores with a new shape |
| CN101651017A (en) * | 2009-01-14 | 2010-02-17 | 郑州乾新电子有限公司 | Liquid-magnetism filled high-frequency transformer |
| CN201397730Y (en) * | 2009-04-14 | 2010-02-03 | 东莞市同和实业有限公司 | Network transformer for communication networks |
| CN201893232U (en) * | 2010-08-04 | 2011-07-06 | 湖北天瑞电子有限公司 | Open type current transformer |
| CN201788793U (en) * | 2010-09-10 | 2011-04-06 | 郭惠成 | Inductor iron core |
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