"Magnetic Ear"-based balancing of magnetic flux in high power medium frequency dual active bridge converter transformer cores

Semiconductor switches posses non-ideal behavior which, in case of isolated DC-DC converters, can generate DC voltage components in the voltage applied to the transformer. This DC voltage component is translated into a DC flux density component in the transformer core, increasing the risk of driving the core into saturation. In this paper, a novel non invasive flux density measurement principle, called the "Magnetic Ear", based on sharing of magnetic path between the main and an auxiliary core is proposed. The active compensation of the transformer DC magnetization level using this transducer is experimentally verified. Additionally, a classification of the previously reported magnetic flux measurement and balancing concepts is performed.