| Abstract |
This paper provides closed-form formulas for estimating the core losses of three-phase transformersexcited with multi-level converters for dual active bridge (DAB) applications. The formulas are derivedby applying the improved generalized Steinmetz equation with approximated flux waveforms generatedfrom one of the windings. The effect of different winding configurations on the estimated losses isstudied. The results are validated with MATLAB simulations, and their applicability for three-phasemulti-level DAB converters is investigated.It is shown that for the YY and the __ configurations, an estimation error of less than 7.5\% and 11.5\%,respectively, can be achieved for most phase shifts between 0 and 20 degrees. It is highest when thedistribution of the leakage inductance is more uniform between the primary and the secondary sides.Moreover, effect of the transition times of the bridges on the estimation error is also studied. It isestablished that estimating the losses from the winding, whose transition time is the largest, results inlower estimation error. It is demonstrated that using the parameters of the _ side results in less estimationerror for the Y_ and the _Y configurations and most of the studied designs. The maximum estimationerror for these two winding configurations is below 8.5\% for phase shifts below 20 degrees. |
