Winding Capacitance and Leakage Inductance

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EE Core »• \Vinding Area Core Mating Surface — *- Mutual Flux *- Window — — \ ^*- V 1EB^^^ W////M/A H~ ,- Primary ^"i | \ s \ a = Winding length, cm s, s a b = Winding build, cm 1 c = Insulation thickness, cm \ _ Insulation \ Ns/2 Secondary each b!-,|1 •4 b2 -b3 ^ c c Figure 17-6. Conventional, Transformer Configuration with Simple Interleave. EE Core *- Core Mating Surface — *- Lp= n(MLT\N2 { > " Mutual Flux »• l_^___£ Window — — n*. \ • V I If^ \ \ Ib b b b c c c X , [henrys] [17-3] ^ i \ 1 \ Np/2 Primary each a = Winding length, cm a b = Winding build, cm c = Insulation thickness, cm Insulation Ns/2 Secondary each Figure 17-7. Sectionalized, Transformer Configuration Primary and Secondary Interleave. EE Core Bobbin Winding Area • Core Mating Surface Mutual Flux Window — *• Copyright © 2004 by Marcel Dekker, Inc. All Rights Reserved. ? »• -**• s < \ 1 f -H b ... V..I / y =*= \> N ^ — ' Secondary i a \ r± a = Winding length, cm JT- c b - Winding build, cm a c = Insulation thickness, cm ^ Insulation x Primary Figure 17-8. Pot Core, Sectionalized Transformer Configuration. 4x(MLT)N 2 V ^ " (l(T 9 ), [henrys] [17-5]
EE Core Bobbin Winding Area Core Mating Surface Mutual Flux Window Secondary 0 a = Winding length, cm a b = Winding build, cm c = Insulation thickness, cm Insulation Np/2 Primary Figure 17-9. Modified, Pot Core Sectionalized, Transformer Configuration. 7r(MLT}Nl( Za\ «A Lp= V ' ' Zc + — (KT 9 ), [henrys] [17-6] b I 3 j v Minimizing Leakage Inductance Magnetic core geometry has a big influence on leakage inductance. To minimize leakage inductance, the primary winding should be wound on a long bobbin, or tube, with the secondary wound as close as possible, using a minimum of insulation. Magnetic cores can have identical rating, but one core will provide a lower leakage inductance than the other. A simple comparison would be two cores with the same window area, but one core has twice the winding length. Only half the winding build is shown in Figure 17-10. EE Cores. Bobbin \ / Secondary Primary / Special Long Tongue EE Core Standard EE Core Configuration Bobbin EE Cores Figure 17-10. Comparing a Standard EE Core and a Special Long Tongue Core. If layers must be used, the only way to reduce the leakage inductance is to divide the primary winding into sections, and then to sandwich the secondary winding between them, as shown in Figure 17-7. This can pose a real problem when designing around the European VDE specification, because of the required creepage distance and the minimum insulation requirements between the primary and secondary. Minimizing the leakage inductance on a push-pull converter design could be a big problem. A special consideration is required symmetry in both the leakage inductance and dc resistance; this is in order to get a balanced winding for the primary switching circuit to function properly. Copyright © 2004 by Marcel Dekker, Inc. All Rights Reserved.
Page 1 and 2: Copyright © 2004 by Marcel Dekker,
Page 3 and 4: Introduction Operation of transform
Page 5: However, for simplicity, leakage in
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Page 11 and 12: Transformers and inductors wound on
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Winding Capacitance and Leakage Inductance

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