ZVS Analysis of a GaN-Based Series-Parallel Dual Transformer LLC Resonant Converter

摘要

Data center energy usage is expected to grow in the coming years with the proliferation of cloud services on daily life. The increasing energy demands that data centers will place upon the power grid necessitate the development high efficiency, high power density power supplies. The LLC resonant converter has long been utilized for data center power supplies as the dc-dc transformer to step down the voltage rectified from the ac transmission system to the rack level. As more is demanded of the data center and more information must be processed, space becomes more valuable. The use of wide bandgap materials such as Gallium Nitride (GaN) allows for much faster switching which can lead to higher power density by reducing the size of passive components. However, a higher frequency can lead to much greater switching loss. Zero-voltage switching (ZVS) can be utilized in primary side devices to greatly reduce losses. The achievement of ZVS is dependent on the magnetic design of the LLC transformer. By considering the effects of device capacitance and transformer parasitic capacitance and inductance, ZVS can be achieved to negate the turn-on losses and ensure high efficiency. This paper details the analysis of ZVS for a GaN-based LLC resonant converter with two series-parallel connected transformers.