Chapter 15 Transformer Design

← Back to document page

Fundamentals of Power ElectronicsChapter 15: Transformer design1Chapter 15 Transformer DesignSome more advanced Design issues, not considered in previouschapter: Inclusion of core loss Selection of operating fluxdensity to optimize total loss Multiple winding Design : as inthe coupled-inductor case,allocate the available windowarea among several windings A Transformer designprocedure How switching frequencyaffects Transformer sizen1 : n2: nkR1R2Rk+v1(t) +v2(t) +vk(t) i1(t)i2(t)ik(t)Fundamentals of Power ElectronicsChapter 15: Transformer design2Chapter 15 Transformer Transformer Design : Basic A step-by-step Transformer Design AC inductor SummaryFundamentals of Power ElectronicsChapter 15: Transformer Transformer Design :Basic ConstraintsCore lossTypical value of for ferrite materials: or B is the peak value of the ac component of B(t), , the peak ac fluxdensitySo increasing B causes core loss to increase rapidlyThis is the first constraintPfe=Kfe( B) AclmFundamentals of Power ElectronicsChapter 15: Transformer design4Flux densityConstraint #2F

Flux density Constraint #2 Flux density B(t) is related to the applied winding voltage according to Faraday’s Law. Denote the volt-seconds applied to the primary winding during the positive portion of v1(t) as 1: λ 1 = v 1 (t)dt t1 t2 This causes the flux to change from its negative peak to its positive peak. From Faraday’s law, the peak value

  Density, Flux, Flux density