Temperature as function of frequency in multiple core magnetic assemblies with variable core size and flux density

The peak flux density of large ferrite cores needs to be derated at frequencies above 10 kHz due to the amount of heat generated inside the core material. The derating factor is a function of the available surface cooling area per volume of the core material and the permissible temperature rise of the core. An experiment for accurately measuring the temperature rise of ranges of ferrite cores as a function of peak flux density and applied frequency, is described. Temperature rise of some commonly used magnetic cores is presented. Alternative magnetic core assemblies, which use a number of smaller cores, are analysed and compared with conventional magnetic components. It is shown by example, that the distributed transformer uses materials more efficiently than an equivalent monolithic transformer or a matrix transformer