UC Berkeley

Ac-dc (and dc-ac) power converters are the interfaces between the electrical grid and thesystems for emerging applications such as electric vehicle (EV) charging, renewable energy source integration, data center power delivery, consumer electronics and numerous other applications. In this dissertation, new circuit topologies and control techniques to improve the performance for both single-phase and three-phase grid-tied converters are explored for three major conversion scenarios: high power bidirectional single-phase ac-dc converters for EV charging and data center applications, low power single-phase ac-dc converters for consumer electronics, and high power three-phase ac-dc converters. For single-phase conversion, the challenge of twice-line frequency energy buering is addressed with active buering techniques that can signicantly reduce the required capacitor size compared to conventional solutions. Through the development of active buers with systematic multi-objective optimization methods and associated advanced digital control, the energy utilization ratios of the passive components are much improved, and the system losses are optimized. For threephase conversion, control and modulation techniques to reduce computational complexity and inductor current ripple are proposed and validated. The proposed circuit topologies and control techniques for both single-phase and three-phase are all validated with high performance hardware demonstrations. Some of the highlighted ones in this dissertation are: a 6 kW, 400 Vdc single-phase liquid-cooled EV charger with optimized series-stacked buer, achieving record power density; a 6 kW 400 Vdc three-phase multilevel rectier with advanced digital control techniques; an active single-phase buer with the smallest reported capacitor size for 2 kW, 400 Vdc inverters; a compact active buer for 65 W USB-C charger.