Manfred Albach

Calculating core losses in transformers for arbitrary magnetizing currents a comparison of different approaches

This paper presents a practical method for predicting the core losses in magnetic components for an arbitrary shape of the magnetizing current. This theory is based on a weighted time derivative of the magnetic flux density and offers the possibility to use the suppliers data, normally derived from measurements with sinewave currents, also for the real current shapes occurring in switch mode power supplies. By means of a special full-bridge power converter, a test setup is developed that allows the verification of the equations derived in this paper.

Conducted interference voltage of AC-DC converters

In this article an analytical method for calculating the conducted interference voltages of the three basic ac-dc converters buck, boost and buck-boost with sinusoidal input current and unity power factor is presented. The analysis includes a simulation of the quasi-peak measurement according to CISPR (Comité International Spécial des Perturbations Radioélectriques). The influence of the different circuit parameters is investigated and the validity is confirmed by experimental results.

The minimization of magnetic stray fields from transformers with air gapped toroids

In this paper the external magnetic stray field is investigated in transformers realized on gapped toroids with a rectangular cross section. An analytical method is used in which the field distribution is calculated by means of orthogonal expansion. Based on the results, basic rules are given that need to be followed in order to optimize transformers used in flyback and load resonant converters under EMC constraints.