An Adaptive Zero Current Switching Control Technique for Multi-Resonant Switched-Capacitor Converters

Combining energy dense capacitors with efficient switch utilization, resonant switched-capacitor (ReSC) converters have gained popularity due to their ability to simultaneously achieve high efficiencies and high power densities. Multi-phase ReSC converters, here referring to topologies that operate with more than two operating circuit states, are especially attractive as they can achieve high conversion ratios with a fewer number of capacitors and switches than conventional two-phase ReSC converters. However, the topological complexity of these converters, combined with real-world circuit non-idealities, make the phase timings required to operate at resonance challenging to estimate with precision. Here, we present an adaptive control technique that can dynamically track and converge to zero current switching (ZCS) operation to achieve high performance, and facilitate larger scale adoption of these topologies. The concept was validated on a high-performance 48-to-6 V hardware prototype, where the proposed active control technique achieved nearly 20% reduction in power loss at the highest tested load (30 A) when compared with conventional open-loop control.