Buck regulators with magnetically coupled filters

This paper is intended to help controllers and designers of high power industrial application such as specialists of traction motor control as well as controllers and designers of very low power industrial applications such as designers of computer motherboards and other circuits using Infinity´s LX166x family of buck regulator controllers. It deals with the effect of replacing the smoothing filters without magnetic coupling used for reducing the ripple generated at the output of buck regulators by a new topology known as magnetically coupled filters. The main attention is focused on the analysis and the simulation of the two-phase parallel connection of buck regulator with magnetically coupled filters known as an interphase reactor or transformer. A comparison of the two-phase connections with smoothing filters without magnetic coupling or with magnetically coupled filters is then done. Actual criteria for comparison may be carried out from technical parameters and investment perspectives. Technical parameters are considered to be: distribution of currents into phases and harmonic content (the amount of the ripple in the load current). Investment costs depend on demands to the material needed for designing the filters. The result of using the magnetically coupled filters is a progressive reduction of the harmonic content generated at the output.