A High-Efficiency and High-Power-Density Partial Power Buck-Boost Converter

This article initiates a comprehensive exploration of two distinct partial power structures first, input-parallel output-series (IPOS) and input-series output-parallel (ISOP), emphasizing their specialized applications. Using efficiency and power processing models, the analysis determines the most suitable partial power topology based on specific requirements, revealing IPOS as superior for step-up applications and ISOP exceling in step-down scenarios. Beyond theoretical analysis, the research includes the development of a dedicated two-phase synchronous buck-boost converter for a broad input voltage range (38-72-V dc) and a fixed output voltage of 107-V dc. Furthermore, emphasizing efficiency maximization, this article explores various zero-voltage-switching (ZVS) control strategies, introducing an innovative hybrid control strategy that surpasses traditional critical conduction mode (CRM) control in power density and fix-frequency control in efficiency, achieving over 98% efficiency. Experimental validation using a prototype validates the effectiveness of these control strategies, providing practical support for the applicability of IPOS and ISOP structures in targeted power processing applications. Furthermore, the results highlight the strength of the hybrid control strategy, particularly in comparison with CRM control and fixed-frequency control mode (FCM).