Resonant Converter based DC Transformer Operation with Magnetic Control

DC transformers (DCXs) have attracted more and more attention in applications such as microgrids, data centers, and renewable energy sources. A DCX is adopted to interface between various energy sources with high power conversion efficiency. An LLC resonant converter operating at resonant frequency with a fixed voltage gain that is independent of load is a promising candidate for a DCX application. However, resonant frequency operation cannot be ensured based on the following three main reasons: 1) tolerances exist for resonant components, which makes the practical resonant frequency deviate from the theoretical one; 2) both capacitance and inductance are variables in terms of temperature and other operating conditions. Thus, under different circuit operating conditions and environments, the corresponding resonant frequency may different; 3) lastly, aging affects will change the components values. The magnetic control/variable inductor is utilized to compensate the variations of resonant frequency in this article. The proposed method is simple, effective, and low-cost. The feasibility and effectiveness of the proposed method are proved under different scenarios.