Measurement of the Transformer with Non-Unity Turns Ratio in the Dual-Active-Bridge Converter

This paper investigates the approach to measuring the transformer with non-unity turns ratio within the dual-active-bridge (DAB) converter. The regenerative DAB converter is utilized to evaluate the performance of the transformer under test, which is back-to-back connected to another identical transformer, for the purpose of using the same two power converters on both sides. Due to the power regeneration, the DC source is allowed to cover only the system loss. Through this system configuration, the transformer is expected to be measured without any problem. Unfortunately, from the preliminary test results, the oscillatory phenomenon can be observed on the high-voltage (HV) side of the transformer. In order to understand where the resonance comes from, the equivalent circuit of the developed system is derived, from which the reason can thus be clarified. Finally, the PLECS simulation platform is employed to confirm the performance, and the simulation results are performed well in accordance with the experimental results. With the help of this theoretical model, the corresponding solution may then be explored in the future.