Review of bidirectional DC–DC converter topologies for hybrid energy storage system of new energy vehicles

New energy vehicles play a positive role in reducing carbon emissions. To improve the dynamic performance and durability of vehicle powertrain, the hybrid energy storage system of “fuel cell/power battery plus super capacitor” is more used in new energy vehicles. Bidirectional DC–DC converters with wide voltage conversion range are essential for voltage matching and power decoupling between super capacitor and vehicle bus, helping to improve the low input voltage characteristics of super capacitors and realize the recovery of feedback energy. In recent years, the topologies of bidirectional converters have been widely investigated and optimized. Aiming to obtain bidirectional DC–DC converters with wide voltage conversion range suitable for hybrid energy storage system, a review of the research status of non-isolated converters based on impedance networks and isolated converters based on transformer are presented. Additionally, an evaluation system for bidirectional DC–DC topologies for hybrid energy storage system is constructed, providing a reference for designing bidirectional DC–DC converters. The performance of eight typical non-isolated converters and seven typical isolated converters are comprehensively evaluated by using this evaluation system. On this basis, issues about DC–DC converters for hybrid energy storage system are discussed, and some suggestions for the future research directions of DC–DC converters are proposed. The optimization of bidirectional DC–DC converters for hybrid energy storage system from the perspectives of wide bandgap device application, electromagnetic compatibility technology and converter fault diagnosis strategies is the main research direction.