Magnetic devices are used as passive components in almost all power electronic applications. The use of active premagnetization is one way of designing these components with controllable parameters during operation. As a result, the applications in which these components are used can be further improved. The use of active premagnetization in transformers is of particular interest because they are an integral part of numerous converter topologies in order to ensure the required galvanic isolation or to enable high voltage ratios. In this article, various approaches to variable transformers are presented and discussed. Verification is carried out using 3D FEM simulation and measurements. The focus is on orthogonal biasing as the premagntization method used.
