Design criterion and guidelines for three-phase asymmetric coupled inductors in interleaving DC/DC converter for VRM in data centres and POL

Abstract

Multiphase interleaving buck DC/DC converters (BCs) with magnetically coupled inductors (CIs) have been researched to improve the performance of voltage regulator module (VRM) and point-of-load (POL). Commercial three or more phase CIs are asymmetric CIs (ACIs) offering unequal phase self-inductance and unequal coupling between phases. By analysing the steady-state current ripple and transient current response speed of three-phase interleaving BCs with three-phase ACIs, the design criterion and design guidelines for three-phase ACIs are presented to simultaneously improve the steady-state performance and transient performance of three-phase interleaving BC with three-phase ACIs. A three-phase interleaving BC prototype with three-phase ACIs is constructed. The experimental results show that three-phase interleaving BC's steady-state phase current ripple can reduce 45%, and its transient output current response speed can increase 63.9% simultaneously by using three-phase ACIs instead of three-phase discrete inductors, and with a smaller total core volume and higher efficiency. The results of this study can be used to design VRM in data centres and POL with smaller steady-state phase current ripple, faster transient output current response speed, and higher efficiency.