ABSTRACT
This chapter discuses the bidirectional three-level DC-DC converter is used to obtain good efficiency with low losses. The topologies used prior to bidirectional three-level buck-boost topology were two-level single-phase and multiphase interleaved topologies. In order to have the advantage of high-voltage operations and high-switching frequencies with reduced inductor and core loss, bidirectional three-level buck-boost topology is preferred to the previously well-known two-level single-phase topology. Zhang et al. designed a bidirectional isolated DC-DC converter controlled by phase shift and analyzed and designed the duty cycle for the fuel-cell hybrid energy system. When braking is applied, the back-emf is bypassed to the ultra-capacitor for storing via power converter module interconnection, in which the three-level buck-boost topology is used. Bidirectional DC–DC converter contains four IGBTs, inductor, and capacitors C1 and C2. By using a three-level bidirectional DC-DC converter, the operation of the converter and working of the ultra-capacitor are understood.
