磁性材料术语解释及计算公式

1、磁性材料术语解释及计算公式起始磁导率“i初始磁导率是磁性材料的磁导率（B/H）在磁化曲线始端的极限值，即(AHt O)式中“O为真空磁导率（4ttx 07 H/m）H为磁场强度的变化率（A/m）AB磁感应强度的变化率（T）有效磁导率“e在闭合磁路中，如果漏磁可忽略，可以用有效磁导率来表示磁芯的性能0式中L为装有磁芯的线圈的电感量（H）N为线圈匝数Le为有效磁路长度5）Ae为有效截面积（卅）饱和磁通密度Bs （T）磁化到饱和状态的磁通密度。见图1。图1剩余磁通密度Br (T)从饱和状态去除磁场后，剩余的磁通密度。见图1。矫顽力He (A/m)从饱和状态去除磁场后，磁芯继续被反向磁场磁化，直至磁感

2、应强度减为零，此时的磁场强度称 为矫顽力。见图1。损耗因子tan5损耗系数是磁滞损耗、涡流损耗和剩余损耗三者之和。tan”= tan d h + t an del tan dr式中tan o i.为磁滞损耗系数tan o e为涡流损耗系数tan d r为剩余损耗系数相对损耗因子 tan6/I i比损耗因子是损耗系数与与磁导率之比：tano /i (it用于材料) tano/zze (适用于磁路中含有气隙的磁芯)品质因数Q品质因数为损耗因子的倒数：Q = 1/ tan5温度系数a“( 1/K)温度系数为T1和T2范围内变化时，每变化1K相应的磁导率的相对变化量:a 口 = P 2-P 11Plt

3、2 -T式中“1为温度为T1时的磁导率“2为温度为T2时的磁导率相对温度系数a “r(l/K)温度系数和磁导率之比，即a /r =：. gt I减落系数DF在恒温条件下，完全退磁的磁芯的磁导率随时间的衰减变化，即DF =x(T2T1)“1为退磁后T1分钟的磁导率“2为退磁后T2分钟的磁导率居里温度Tc (C)在该温度时材料由铁磁性(或亚铁磁)转变为顺磁性，见图2。电阻率p(Q.m)具有单位截面积和单位长度的磁性材料的电阻。密度 d (kg/m3)单位体积材料的重量，即d =W/V式中W为磁芯的重f (kg)V为磁芯的体积(於)功率损耗Pc (kW/ms)磁芯的高磁感应强度下的单位体积损耗或单位

4、重量损耗.该磁通密度可表示为EBm =4.44 fNAe式中E为施加在线圈上的电压有效值(V)Bin为磁感应强度的峰值(T)f为频率(Hz)N为线圈匝数Ae为有效截面积（m）电感系数AL （nH/N2）电感因数定义为具有一定形状和尺寸的磁芯上每一匝线圈产生的电感量，即A l = L/N2式中L:为装有磁芯的线圈的电感量（H）N:为线圈匝数Initial permeability, fiThe initial permeability “i is the limit value at the initial magnetization curves origin point and is giv

5、en by the following formula:ABi = Ko x T H(ah T o)Wherei o:Permeability of vacuum ( 4;rx10 7/y/,w )AH:Rate of change for magnetic field strength(A/m)E： Rate of change for Magnetic flux density(T)Effective permeab 订 ity, “ eThis is usually defined as the permeability of a core forming a closed circui

6、t where leakage flux is negligibly smalLLcpe 二山 N? AeWhereL: Self-inductance of core with coil (H)N: Number of turnsLe: Effective magnetic path length (m)Ae: Effective cross-sectional area (m)Saturation flux density, Bs (T)The magnetic flux density at a magnetic field where his up to a approximate s

7、aturation magnetic field value (Fig.1)Remanence, Br (T)The value of density retained by the core when the magnetic field is reduced fromthe saturation magnetic flux density to zero. (Fig.1)Coactivity, He (A/m)The value of magnetic field strength where by the flux density becomes zero under the inten

8、sification, in the opposite direction, of the magnetic field (Fig.1)Loss factor , tan(5This is the sum of the hysteretic loss factor, eddy current loss factor and residual loss factortan(5= tan d h + tan + tan drWheretano h is the hysterias loss factor tanOc is the eddy current loss factor tano r is

9、 the residual loss factorRelative loss factor,tand/“iThis is the ratio of loss factor to permeability.tand/ii (for materials)tan5/e (for cores with gaps in the magnetic circuit)Quality factor, QThis is the reciprocal of the loss factor and is given byQ = 1/ tandTemperature coefficient, a fl (1/K)Thi

10、s is the fractional difference of permeability per IK in a temperature range of from T1 to T2.乜F I岗 T1 -TiWhere111: Permeability at temperature T1“2: Permeability at temperature T2Relative temperature coefficient, a fix (1/K)This is the temperature coefficient per unit permeability and is given by t

11、he following equation:completeWhereThisdemagnetizati 岛thefactor-Ufactor771MDFPermeability0iofrepresentingOQ1thel JcoreXtheatvariation1aT1constantminutesof(T2permeabilityT1)temperature.afterthroughcompletetimeafterdemagnetization.crossEectonaThisisresistivelytheareaelectricalXof Qresistancem)2crossEe

12、ctonaThisisresistivelytheareaelectricalXof Qresistancem)2perunitx x critical statematerialI of temperaturethe )levelCurieferromagneticis tempera-turpTcthelengthcharfeswhichandtofhea magnetic core.Density, d (kg/ms)This is the weight per unit volume of a magnetic core as expressed below d =W/VWhereW:

13、 Weight of magnetic body (kg)V: Volume of magnetic body (in)Power loss, Pc (kW/ m3)Power loss denotes the loss by an electrical transformer, such as a switching power supply, under a magnetizaticm condition featuring a high frequency and large amplitude Operating magnetic flux density is given by the fol lowing equation.EBm =4.44 fNAeWhereE: voltage effective value applied to coilBin: peak value of magnetic flux density (T)f: Frequency (Hz)N: Number of tunesAe: Effective cross-sectional arum (i )In