UC Berkeley

Power converter topologies are continually evolving and improving especially as new applications such as space exploration mature, and new power architectures emerge. One such evolutionary branch of power converters is hybrid switched-capacitor (SC) converters which leverage capacitors as highly energy-dense components, high figure-of-merit switching devices, and small magnetics to realize high-performance power electronics. To fully exploit the benefits of this relatively new class of power converters requires investigation into control schemes. Whether using conventional switching control strategies or developing novel arrangements, this work explores the theoretical and practical intricacies of applying various switching schemes to hybrid SC converters.

Due to the reliance on capacitors for energy processing, SC converters typically suffer from charge-sharing losses when capacitors are charged/discharged into other capacitors or sources. However, adding a small inductance to the circuit and incorporating clever switching patterns can reduce or eliminate these losses. Furthermore, with an increase in the number of switching devices over traditional converters, losses associated with those switches may also increase. This work examines soft-switching techniques and how application to hybrid SC converters differs from previous works.

Finally, a hybrid SC converter is designed and tested for low-voltage automotive powertrain applications. In an industry that has strict regulations, this work seeks to demonstrate these new topologies can meet the required specifications and can do so with high performance as well. Switching techniques for mitigation of electromagnetic interference are evaluated against regulated limits and against efficiency performance.

Theory, analysis, and experimental results are expounded upon for several switching control strategies of hybrid SC converters addressing challenges of high-efficiency, low-noise, and high-density for applications to data center power delivery, space technology, and automotive powertrains.