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設計資料

設計公式

Ae:有效磁粉芯面積(cm2)與磁芯的橫截面積相等(cross section area)
le:有效磁路長度或稱平均磁路長度(cm)(mean magnetic path length)
V:磁芯體積:(cm3)(core volume)
OD:磁芯外徑(cm)(outside diameter of core)
ID:磁芯內徑(cm)(inside diameter of core)
Ht:磁芯高度(cm)
W:磁芯最小窗口面積(cm2
1英寸(inches)=103mil=25.4mm

磁導率是磁滯回線上任何點所對應的B與H的比值。

In magnetics,permeability is the ability of a material to conduct flux.The magnetitude of the permeability at a given induction is a measure of the ease with which a core material can be magnetized to that induction.It is defined as the ratio of the flux density Bto the magnetizing force H.

μe:有效磁導率(無量綱)permeability
B:磁通量密度(高斯Gauss)flux density(Gauss)
H:磁場強度(奧斯特Oe)magnetizing(Oe)

每種尺寸磁粉芯的額定電感量都與其有效磁導率有關,有效磁導率僅作參考環型磁芯的電感測試是依均勻分布的單層繞組作測試依據,以非均勻分布而少圈數的磁芯作測試會產生比預期要大的電感讀數。

Neu Flux Cores的電感系數值是以1000圈時為測試依據,其中電感系數偏差通常在±8%之間。

The inductance of a wound core at a given number of turns is calculated using the following formula 
L=0.4πμeN2Ae*10-2/le
Ln=Al&N<2>*10-3L:電感量(μH)1H=103mH=106μH=109nH inductance(μH)
Al:額定電感量(nH/N2)nominal Inductance(nH/N2)
μe:有效磁芯截面積  effective cores section area(cm2)
Ae:有效磁路長度 mean magnetic path length(cm)
N:線圈數: number of turns
Ln:在N圈時的電感量(μH)Inductance at N turns(μH)

安培定律揭示了磁場強度(H)與電流、圈數和磁路長度之間的關系。

Ampere's Law relates magnetizing force(H)to current,number of turns and magnetic path

length. 

H:磁場強度(Oersteds)magnetizing force(oersteds)

N:圈數 number of turns

I:電流(A)peak magnetizing current(amperes)

Le:磁路長度(cm) mean magnetic path length(cm)

1Oersted=0.7958A/cm


Q值是指電感器電抗與有效電阻的比值,它反映了該電感的質量。對于電源濾波器而言,Q值提高就意味著截止更快,衰減比更高和諧效果更好,Q值的大小主要由電感線圈的分布電容所決定。如果忽略分布電容引起的自諧振效果,可以用以下公式計算電感器Q值

The Qfactor is defined as the ratio of reactance to the effective resistance for inductor and thus indicates its quality.The Qof wound core can be calculated using the following formula,when neglecting the effects of self-resonance caused by the distributed capacitance resulting from the differential voltage between adjacent turns. 

Q:品質因數 quality factor

L:電感量(H)inductance(henries)

ω:2πf(Hz)2π frequency(hertz)

Rdc:繞線直流電阻(Ω)DC winding resistance(ohms)

Rac:由于磁粉芯損耗而產生的阻抗(Ω)resistance due to core loss(ohms)

Rcd:由于繞線中介電損耗而產生的阻抗(Ω)resistance due to winding dielectric loss(ohms)

磁通密度的大小影響磁粉芯的損耗值和磁導率。除非另有說明,本樣本中所列舉的數據都是基于正弦波形和最大磁通密度(峰值)得出的。Bpk指穿過磁粉芯橫截面各部分平均磁通密度值的最大值。事實上,通過磁粉芯內徑附近的磁通密度值高,而磁粉芯外徑附近的磁通密度值低。

The corresponding parameter for the induces magnetic field in an area perpendicular to the flux density is determined by the field strength permeability of the medium in which it is measured.

Bpk:最大磁通密度峰值(高斯Gauss)maximum flux density(gauss)
Erms:通過繞正弦電壓有效值(Vrms)sinusoidal RMS voltage across winding(Vrms)
N:圈數 number of turns
Ae:有效磁粉芯截面積(cm2)cross section area(cm2)
f:正弦波形電壓頻率(Hz)frequency(hertz)
1特斯拉(T)=104高斯()Gauss=103mT
 
 

磁芯損耗是磁芯材料內交替磁場引致的結果。磁芯損耗有三部分組成:磁滯損耗、剩磁損耗和渦流損耗。在高頻條件下,渦流損耗是主要損耗,而低頻下磁滯損耗則是主要損耗。而各種損耗形式在總損耗中所占的比例也會受到磁通密度的影響,受到高溫熱老化影響的是磁芯損耗的渦流部分。

Powder cores have low hysteres is loss,minimizing signal distoion,and low residual loss.The total core loss at low.The core loss is calculated from the following legg's equation.

Rac:由磁芯損耗產生的有效電阻(Ω)resistance due tp core loss(ohms)

μe:有效磁導率 permeability

L:電感量(H)inductance(H)

a:磁滯損耗系數 hysteresis loss coefficient

Bpk:AC磁通密度峰值(高斯Gauss)maximum flux density(gauss)

c:剩磁損耗系數 residual loss coefficient

f:頻率(Hz)frequency(hertz)

e:渦流損耗系數:eddy loss coefficient

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