Virginia Polytechnic Institute and State University
High frequency high power transformers will play a critical role in the future hybrid ac/dc grid of the future in order to provide high efficiency galvanic isolation for datacenters, distributed energy resources, and EV charging. Conventional high frequency high power transformers suffer from low cooling surface area and high loss per unit volume, negating their high frequency size reduction benefits. This work shows a 200 kHz, 100 kW transformer constructed of transformer winding building blocks and modular ferrite pieces which allows for even cooling surface area as more building blocks are stacked to achieve higher power ratings. To address current sharing issues among winding building blocks; current balancing transformers (CBX) are utilized and a CBX configuration called the “circular” configuration is shown to reduce CBX inductance value and improve current sharing. A first-of-it’s-kind N-Level CBX model is presented which accurately predicts system current sharing error and informs designers what CBX value is required for any N-Level modular magnetics system. The model is validated with experimental results and a peak current sharing error of <5% is achieved.
