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L-testing of amorphous core

L-testing of amorphous core. L-testing of amorphous core Tom_huang( 黄志芳). Introduction. 具有矩形磁滞曲线的磁放大扼流圈的电感量测试方法由于磁材本身的超高磁导率限制了其测试的准确度而未被开关电源生产商认可,其磁导率及测得的电感量在很大程度上取决于 AC 及 DC 振幅.而实际测量的振幅依赖于测量仪器及测试个体…. Test of theory. 主要的测试原理如下: 安培环路定律. NI=HL. U 计算公式: u=79.6*L*lfe/N*2 ×Afe. Point(A).

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L-testing of amorphous core

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  1. L-testing of amorphous core • L-testing of amorphous core • Tom_huang(黄志芳)

  2. Introduction • 具有矩形磁滞曲线的磁放大扼流圈的电感量测试方法由于磁材本身的超高磁导率限制了其测试的准确度而未被开关电源生产商认可,其磁导率及测得的电感量在很大程度上取决于AC及DC振幅.而实际测量的振幅依赖于测量仪器及测试个体…

  3. Test of theory • 主要的测试原理如下: • 安培环路定律.NI=HL. • U计算公式:u=79.6*L*lfe/N*2×Afe.

  4. Point(A) • Point a: test procedure:L-measurement with superimposed DC-current. • Test parameters:F=100khz .Hac=4ma/cm.Hdc=1200ma/cm • Test results:15∠u∠200 • Information:1)u∠15: over spec. • 2)u〉200;over spec.

  5. Point(B) • Point b: test procedure:L-measurement without superimposed DC-current . • Test parameters:F=100khz.Hac=4ma/cm .Hdc=0ma/cm • Test results :400∠u∠8000. • Information:1)low u=high squareness. • 2)u〉8000;too high △Brs.squareness out of spec. • 3)u〈400; out of spec

  6. Point a and point b • 同时采用方法A和方法B的好处是: • A)采用方法A:可检测出由于绕线时机械应力或其它外力导致的磁芯损坏. • B)采用方法B:可检测出磁滞曲线的矩形比(低电感意味着高矩形比)

  7. Additional important notes(1): • 1)The combined test (point a and point b)gives full information.if –by the whatever reason-only one test can be made .we recommend to do point a-test rather than point b-test .

  8. Additional important notes(2): • 2)If point b-testing is done prior to point a –testing, an additional unipolar DC-pulse of〉100ma/cm needs to be applied prior to point b –testing

  9. Additional important notes(3): • Best results are achieved by using an additional DC-source equipment.however , • If no additional DC-source is available, • Point a – test can be done with smaller DC-currents form an LCR-METER with DC-option at somewhat lower accuracy . The test values need to be adapted in the following way;increase the u limit for point a with decreasing DC-current.however,make sure that the DC is strong enough for core saturation

  10. Additional important notes(4): • The accuracy of the test method decreases with increasing no.of turns due to the excessive increase of inductance L small cores(O.D.up to 12mm)and N〈10 achieve reliable results with the given test procedure • Bigger core sizes and/or higher no.of turns need further verification .

  11. Additional important notes(5): • differ materials may require different test parameters.

  12. Point A theory

  13. Point B theory

  14. Production technics

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