Development of a Novel Laboratory-Scale Testbed for Measuring the Iron Loss in a DAB Converter

This paper attempts to develop a new laboratory-scale testbed for measuring the iron loss within a dual-active-bridge (DAB) converter, particularly when using the transformer with a non-unity turns ratio. The regenerative construction is utilized to estimate the transformer under test, which is back-to-back connected to another transformer with the same turns ratio, enabling the usage of identical power converters on both sides. Accordingly, the proposed testbed uses two H-bridge converters fed by a common 50 V DC source and operated at a switching frequency of 20 kHz to feed two back-to-back connected transformers with a turns ratio of 1:7.8. With the help of power regeneration, the DC source needs only to cover the power loss rather than the power rating, thus reducing the burden of experimental equipment. However, the preliminary test results reveal two key issues that influence the measurement. To identify the root causes, theoretical discussions are conducted, and potential solutions are proposed in response to these two problems. The simulated waveforms are also provided and performed well in accordance with the experimental waveforms, and the iron loss measurement results are finally summarized to highlight that the developed system performs comparably to the actual DAB converter system. The proposed testbed is thus expected to be of practical value for transformer manufacturers to preliminarily measure the total iron loss of a DAB converter.