Electromagnetic transformer modelling including the ferromagnetic core

In order to design a power transformer it is important to understand its internal
electromagnetic behaviour. That can be obtained by measurements on physical
transformers, analytical expressions and computer simulations. One benefit with
simulations is that the transformer can be studied before it is built physically and
that the consequences of changing dimensions and parameters easily can be
assesed.
In this thesis a time-domain transformer model is presented. The model includes
core phenomena as magnetic static hysteresis, eddy current and excess losses.
Moreover, the model comprises winding phenomena as eddy currents,
capacitive effects and leakage flux. The core and windings are first modelled
separately and then connected together in a composite transformer model. This
results in a detailed transformer model.
One important result of the thesis is the feasibility to simulate dynamic
magnetization including the inhomogeneous field distribution due to eddy
currents in the magnetic core material. This is achieved by using a Cauer circuit
combined with models for static and dynamic magnetization. Thereby, all
magnetic loss components in the material can be simulated accurately. This
composite dynamic magnetization model is verified through experiments
showing very good correspondence with measurements.
Furthermore, the composite transformer model is verified through
measurements. The model is shown to yield good correspondence with
measurements in normal operation and non-normal operations like no-load,
inrush current and DC-magnetization.