Optimization of a flyback transformer winding considering two-dimensional field effects, cost and loss

Easy-to-use CAD tools for litz-wire winding optimization

“…The method chosen for implementation is the approach in [10]. It uses the squared-field-derivative (SFD) method [11] to handle different nonsinusoidal waveforms in each winding, properly accounting for mutual resistance effects [12].…”

“…The SFD method also handles two-dimensional (2-D) or three-dimensional (3-D) field effects, by combining analytical modeling of the strandlevel eddy-current loss effects with numerical calculations of the overall field shapes. In [10], the SFD method is combined with a cost analysis of litz wire [2] in order to optimize a particular flyback transformer. We have taken the method used for this example in [10] and implemented a general-purpose version of it in easy-to use software.…”

“…In [10], the SFD method is combined with a cost analysis of litz wire [2] in order to optimize a particular flyback transformer. We have taken the method used for this example in [10] and implemented a general-purpose version of it in easy-to use software. For the convenience of the reader, the method in [10] is reviewed in detail in Appendix I.…”

“…We have taken the method used for this example in [10] and implemented a general-purpose version of it in easy-to use software. For the convenience of the reader, the method in [10] is reviewed in detail in Appendix I. A brief overview of the method is provided in Section I-A.…”

“…In [10], it is shown that this method of calculating losses can be used as the basis for finding the optimal number and diameter of strands in a litz-wire winding, similar to the optimization in [2], but valid for arbitrary geometries and current waveforms. As shown in [8], it is essential to consider cost in litz-wire optimization, because the minimum-loss design, considered independent of cost, typically uses prohibitively expensive constructions with many extremely fine strands.…”