1 in all modular inductance principle

 

Introducing choke introduces first before modular inductance in all, choke is one kind uses abate circuit inside the low impedance coil of high frequency electric current. To raise its inductance choke has the core that material of one soft magnetism makes normally. In all modular choke has many same coil, electric current flows reversely in these coil, because this is in the core of choke,magnetic field offsets. In all modular choke often is used to depressive interference radiate, because such interference electric current is retrorse in different coil, raise systematic EMC. To such electric current in all the inductance of modular choke is very tall. In all the circuit graph of modular inductance is shown 1 times like the graph.

 

 

In all modular signal and wrong standard signal just are measured relatively, in all modular signal says again in all modular noise perhaps weighs right noise, show two lines are opposite respectively the noise of the ground, to the input filter of switch power source, it is 0 lines and front line are opposite respectively the telegraphic date of the earth. Although 0 lines are mixed,live wire was not linked together with the earth directly, but the parasitism capacitance that 0 lines and front line can pass circuit board to go up respectively or stray capacitance or parasitism inductance will be linked together with the earth. Wrong standard signal is the signal that shows two lines are direct the parallax is report that poor value also can weigh.

 

Have two signal V1, V2 suppose

 

In all modular signal is (V1+V2) / 2

 

Wrong standard signal is: To V1 (V1-V2) / 2; To V2 – (V1-V2) / 2

 

In all modular signal characteristic: The signal with phasic and equal, same range.

 

Differ modular signal characteristic: The signal with phasic and equal, opposite extent.

 

If the graph is shown 2 times,mix for wrong standard signal in all the sketch map of modular signal.

 

 

Graph signal of 2 wrong standards and in all modular signal sketch map

 

Noise of 2 wrong standards and in all modular noise is main origin

 

To switch power source, if after rectification bridge store can filter wave large electric capacity is ideal capacitance, namely resistor of equivalent series connection is 0 (oversight is all capacitance parasitism parameter) , the source of wrong standard noise of all likelihoods that input power source is met by this capacitance complete bypass or solution Ou, but the resistor of equivalent series connection of high capacity capacitance is not,be 0. Accordingly, the resistor of equivalent series connection that inputs capacitance is the body of the impedance Zdm that looks from wrong standard noise generator. Input capacitance works besides what bear to be flowed into from power supply cord outside electric current, offer switch to provide electricity of needs high frequency pulse even, but anyhow, inevitable generation approachs resistance of voltaic shedding classics fall, be like the resistor of equivalent series connection of capacitance, so two end meet capacitance of input filter wave appear ripple of high frequency voltage, ripple of high frequency high pressure comes from namely at needing modular electricity. It basically is source of a voltage (bring about by resistor of equivalent series connection) . Theoretic, rectification bridge guides when connecting, noise of this high frequency ripple should appear in rectification bridge to input side only. In fact, when rectification bridge closes, noise can pass the parasitism capacitance of rectification bridge diode to divulge.

 

High frequency electric current flows into housing to have a lot of accidental way. When switch power source medium advocate the leakage that switch is in charge of extremely on any account jumps when changing, the parasitism capacitance between canal of switch of voltaic shedding classics and radiator (radiator join comes crust or radiator is crust) . Rectification bridge maintains to guide in electric current of alternating current net when connecting, the noise of infuse housing encounters almost equal impedance, because the quantity such as this flows into 0 lines and front line. Accordingly, this is pure in all modular noise.

 

3 in all how is modular inductance restrained in all modular signal

 

Had known at present in all modular signal is the signal with two phasic and equal, same range, in all modular signal comes from electrified wire netting commonly, in all the regular job that modular signal can affect circuit board, also can disturb surroundings with the form of electromagnetic wave.

 

Since be to use inductance to restrain in all modular signal, so this affirmation and magnetic field are relevant. Will introduce electrify spiral feeling first, the direction of the magnetic field of generation (to project application, some circumstances are restrained for instance in all modular signal, need mensurable consideration not quite, the size of the magnetic field that inductance produces and flux, interested children’s footwear, here recommends a book to be able to consult, the magnetism in << switch power source yuan parts of an apparatus >> Mr. Zhao Xiuke) . To the magnetic field direction of electrify solenoid judgement method is, right hand handholding snail is in charge of, 4 point to point to voltaic direction, criterion big toe is pointed to is magnetic field direction. Introduce an important name next, namely magnetic flux. Hang down to pass a gross of sectional lines of force to call this sectional flux continuously, abbreviation magnetic flux. Lines of force is electrify solenoid generation, it is subsistent, just lose sight of also feel do not wear, lines of force is one shuts mixed return circuit, to electrify solenoid, lines of force should pass solenoid interior, lines of force becomes direct ratio with B of magnetic induction intensity. If the graph shows the sketch map for lines of force of electrify solenoid generation 3 times.

 

Graph 3 solenoid lines of force

 

If the graph is shown 4 times,be, cross the magnetic flux with sectional some

 

Graph 4 cross sectional magnetic flux

 

Flux expresses with F, it is a scalar quantity, the unit is Wei Bai, code name Wb. The relation of flux and B of magnetic induction intensity and cut area A is:

 

F=BA

 

Can see from relation, the lines of force that crosses cross section is more, flux is bigger. To be being circled in the coil on magnetism core, on its electrify sheds I, criterion the inductance L of coil can express to be:

 

L=NF/i

 

N is coil v/LIT all over the ground number.

 

Hereto, pass afore-mentioned brief overview, can know, the coil that is circled on magnetism core is when v/LIT all over the ground number and electric current are constant, the lines of force that crosses in magnetism core is more, so flux is bigger, corresponding inductance amount is larger also. The effect with natural inductance prevents the change that has shed the electric current on its namely, it is the change that prevents its flux character actually. This is used namely in all modular inductance will restrain in all the fundamental of modular electric current.

 

If the graph is shown 5 times,be, in all modular electric current is in the magnetic induction strength that generates on modular inductance in all, the magnetic induction strength that voltaic I1 generates is B1, the magnetic induction strength that voltaic I2 generates is B2, the lines of force that two yellow arrowhead represents voltaic I1 and I2 to arise in ferrite respectively, can see voltaic I1 and the lines of force that I2 produces are additional, reason magnetic flux also is additional, so inductance quantity is additional, inductance amount is larger, to voltaic inhibition ability is jumped over strong.

 

Graph 5 in all modular electric current is in in all the magnetic flux on modular inductance distributings

 

To in all how is modular inductance restrained in all modular electric current can explain with a word, namely in all modular inductance is genteel over- in all the magnetic flux in annulus of the magnetism when modular electric current mutual overlay, have quite large inductance amount thereby, to inhibition arriving since modular electric current in all.

 

When two coil had shed wrong standard electric current, the lines of force in ferrite magnetism annulus is contrary, bring about magnetic flux to offset each other, hardly inductance is measured, differ what modular signal can not have attenuation basically to pass so (have certain resistance considering inductance itself) . Add to the input filter of switch power source not only so in all modular inductance, also can add when taking the line that need branch in all modular inductance will restrain in all modular electric current, wait for a phenomenon in order to prevent circuit false triggering.

 

4 in all modular inductance is chosen

 

Basis in all the impedance below the rated electric current of modular inductance, dc block and rated frequency is worth a requirement, can undertake designing by measure:

 

Impedance estimation considers 1 basis the smallest inductance value

 

2 choices in all material of core of modular inductance magnetism and magnetism core dimension

 

V/LIT all over the ground number of 3 affirmatory coil

 

4 choices lead

 

In all estimation of the smallest inductance considers modular inductance formulary:

 

 

Xl is the impedance value when F for frequency

 

Choke inductance value is to use load (unit: Ohms) divide the horny frequency when beginning attenuation with signal or above frequency. For example, in the load of 50Ω , when frequency achieves 4000 Hz or above signal begins attenuation, need to use 1.99 MH (50/2π×4000) ) inductance. Its are corresponding in all modular filter is tectonic, following graphs show 6 times:

 

 

The frequency that chooses a wave needing filter paragraph, in all modular impedance has been jumped over greatly more, because this is in,the choice needs to read material of parts of an apparatus when modular inductance in all, basically choose according to impedance frequency curve.

 

After inductance measures computation to come out, mix common design inductance is same, do not spread out in detail here.

 

Oneself are being circled some of item should notice when making inductance,

 

1) circle the wire that makes core of online circle magnetism go up to want mutual insulation, what encircle in order to make sure in instantaneous overvoltage action gets offline is v/LIT all over the ground do not produce puncture short circuit.

 

2) when coil has shed instantaneous big electric current, magnetism core does not want occurrence saturation.

 

3) the magnetism core in coil should be isolated from with coil, in order to prevent both below instantaneous overvoltage action between produce puncture.

 

4) coil should be circled as far as possible make monolayer, do the parasitism electric capacity that can reduce coil so, enhance coil to be opposite of instantaneous overvoltage and give ability

 

In all of core of modular inductance magnetism when choosing magnetism core, shape size, applicable frequency paragraph, temperature rise and price want a consideration, commonly used magnetism core is U model, E and annular.

 

Relative to character, annular magnetism core is cheaper, because annular only one can be made. And the magnetism core of other form must have a pair of ability to be in all modular inductance place is used, and when shape, consider the conjugate issue of two magnetism core, still must increase ability of abrade working procedure to get taller magnetism conductance, do not need however to annular magnetism core such;

 

Have taller effective magnetism conductance than annular magnetism core with photograph of core of other appearance magnetism, when be being assembled because of core of two conjugate magnetism, no matter how work to cannot eliminate the appearance of air gap, effective magnetism conductance compares reason onefold close form magnetism core wants low. But annular magnetism core circles line cost taller, because core of other form magnetism has line of one form a complete set to wear,using, it is OK to wind a string the machine works, and annular magnetism core can make course of study or machine by hand only (speed is inferior) exercise; And magnetism annulus aperture is small, the machine wears a line hard, need is circled artificially, take time is arduous, finished cost is high, efficiency is low; Installation is disadvantageous, if increase base, criterion cost can rise. Integral performance is compared rise, magnetism annulus performance is better, the price is higher also. Because of the element of cost, magnetism annulus is used on the power source of high-power mostly.

 

Of course because volume is minor, have the small-power power supply of the requirement to bulk, can use core of magnetism annulus magnetism. To main effect it is filter divide low frequency noise in all modular inductance, the manganese zinc ferrite that ought to choose tall magnetism conductance magnetism core; Contrary, should choose apply to high frequency nickel zinc ferrite magnetism core or core of magnetism of magnetic particle core. Apply to high frequency magnetism core normally, because its have distributed air gap, reason magnetism conductance is relatively inferior, both cannot hold concurrently. Nevertheless, what differ with common inductor is, in all the action of modular inductance is to noise signal forms bigger insertion loss, in order to reduce noise interference. Manganese zinc ferrite is in high frequency when, although its are effective magnetism conductance is very small, but magnetism core loss increases along with frequency and increase, have bigger block up effect to high frequency noise, so also can abate high frequency interference, just the effect is opposite poorer. However, bigger magnetism core loss can bring about magnetism core to give out heat, and the magnetism core price with lesser loss is higher also.