In this lecture, a comprehensive review of isolated bi-directional DC-DC converters was presented. The requirements of BESS on isolated bidirectional DC-DC converters with high efficiency and high power density were introduced. Two major solutions of isolated bidirectional DC-DC converters, CLLC resonance converter, and dual-active-bridge (DAB) converter, were investigated and compared, including modeling methods, control strategies and design considerations with the use of SiC and GaN devices. This lecture pointed out that both CLLC and DAB converters have their own advantages and good application prospects in future large-scale energy storage systems. Moreover, a modular multi-port CLLC converter based on high-frequency AC bus sharing was proposed to integrate multiple battery stacks, which features high efficiency, high reliability and good scalability. Speaker: Kai Sun of Tsinghua University  

In this webinar, the basic concepts of graph theory were introduced, followed by the discussion and demonstrations of electrical dual principles and emerging isomorphic theory for various power converters, in particular, voltage-source converters and current-source converters. The unique cycling phenomenon of topology transformation was also investigated. Finally, the webinar ended with discussions and further research trends in this area. Speaker: Yuzhuo Li of the University of Alberta