Ultra-Compact Combined Common Mode (CM)- and Differential Mode (DM)-Inductors

Abstract:
This paper describes the design and electrical validation of tape-wound combined common mode (CM) and differential mode (DM) inductors based on low relative permeability nano-crystalline core material (mur ≤ 1900). The permeability of this material is very stable up to frequencies of f ≤ 2 MHz and has a very good loss behavior in the range of ferrites. The maximum saturation flux density is around Bsat = 1T. In the course of the examination these coupled inductors were designed for three applications. In the first part the analytic modeling for CM- and DM-reluctances is conducted. As a second step the losses of the material were characterized in the range of 20 ... 300 kHz. Afterwards a pareto analysis was conducted for all three applications to figure out coupling coefficient k and the geometrical values. The inductor designs were produced in the lab and the electrical parameters were validated.