A High-Efficiency and High-Power-Density Interleaved Integrated Buck-Boost-LLC Converter and Its Comprehensive Optimal Design Method

Integrated buck-boost-LLC (IBBL) dcconverter is a good solution for high efficiency and high power density applications. However, the bridge leg integration causes asymmetrical zero-voltage-switching process and asymmetrical secondary current. The method of high quality factor or symmetric phase shift modulation proposed in the existing research can improve the asymmetrical current issue under heavy load, but is ineffective for light load conditions. This article proposes a novel Interleaved IBBL converter to improve the asymmetry issue for whole load range. Interleaving makes the secondary current be symmetric naturally. In addition, a comprehensive optimal design method for phase-shift angle and choke inductor is proposed to minimize the total power loss of all primary elements. A 600 W/1 MHz prototype verifies that the proposed IIBBL converter achieves symmetric secondary current in whole load range, and it achieves 95.7% efficiency and 180 W/in³ under the proposed comprehensive optimal design method.