25 kW/L 99.2% Efficiency Wide Output Three Phase PFC Based on Modular Inductive Switching Network

The modular inductive switching network (MISN) PFC converter, featuring effective modularization and a single DC bus, is a promising solution for high efficiency AC-DC conversion with improved power density. However, when applied to battery charging systems requiring wide DC bus voltage range (e.g., 550-900V), existing implementations face significant challenges that the loss and volume of the MISN module increase significantly. This study develops a mathematical model to analyze the impact of DC bus voltage on the MISN module, focusing on loss and volume. It is revealed that the MISN module's operating voltage and buffer energy is proportional to the DC bus voltage range, leading to increased switching losses and capacitor volumes. To address these issues, a modified MISN-PFC converter with 3level LF-bridge is proposed, which has lower voltage stress of the MISN module. A 10kW prototype demonstrates 99% full-load efficiency across the entire voltage range while achieving 25kW/L power density, representing more than twice improvement in power density compared to conventional MISN-PFC converter with 2level LF-bridge under similar efficiency constraints.