Analysis and Optimization of an Inverse Coupled Inductor in a High Frequency LLC Converter with Current Doubler Rectifier

In this paper, a current doubler rectifier with inverse coupled inductor for use in a high frequency LLC converter with high output current is analyzed and optimized. The converter is designed to operate at an input voltage of 400V, output voltage of 36V and output power of 2kW. Since the parasitic elements of the coupled inductor are part of the commutation cell of the rectification circuit, strong efforts have to be made to minimize these parasitics in order to avoid excessive oscillations during operation. By choosing a planar approach, total stray inductance of less than 15 nH can be achieved, enabling the use of 100V-class MOSFETs with little to no snubber circuit and a total efficiency at rated power of more than 98%.