High-Frequency 12 V Regulated LLC Bus Converter With Integrated Multiphase Inverse Coupled Resonant Inductor

In the application of 48 V bus converter, the traditional multiphase regulated LLC converter has some shortcomings, such as insufficient gain range, low light-load efficiency, and difficult current sharing. In order to improve the performance, this article investigates a comprehensive design scheme of multiphase interleaved magnetic integrated LLC converter, which can extend the gain range and achieve active current sharing simultaneously. First, a new structure of multiphase inverse coupled resonant inductor and magnetic integrated transformer is proposed. Then, a high-precision magnetic circuit model is constructed to optimize the design of integrated inductor and transformer. On this basis, the three-phase interleaved magnetic-integrated LLC converter prototype is manufactured, which has a 36-75 V input voltage range and a 12 V regulated output voltage. In addition, the prototype can output 1080 W power in a quarter brick and has a power density of 716 W/in(3). The maximum efficiency at rated input voltage is 97.5% and remains above 96% over the main input voltage range. As shown by the quantitative performance comparison results, the proposed converter is superior to other state-of-the-art solutions in terms of the comprehensive performance.