A method of transformer parameters determination for power electronics applications

This paper proposes a model that adequately describes the operation of the transformer at deep saturation, suitable for power electronics applications, and a method for determining its parameters. The magnetizing branch is represented by the parallel association of a fixed resistance and a non linear inductor that can be implemented by using a current source or switched linear inductors. The parameters with linear behavior are obtained by the traditional short circuit and open circuit tests. The non linear behavior of the magnetizing inductance is obtained by processing the voltage and current waveforms measured in the open circuit test. Deep saturation condition is achieved by acquiring these waveforms during the transformer energization at nominal voltage, instead of using steady state data, which would require an oversized power supply and cause excessive thermal stress at the windings. Pre-demagnetization procedures are developed to cope with the remanent flux. Simulation and experimental results are presented to confirm the validity of the model and the method.