The increasing photovoltaic generation in today’s grid has made DC coupled PV plus storage system a preferred solution for critical grid functionalities, where a bidirectional DC-DC converter is needed. For 1500V PV system, higher breakdown voltage SiCs are not generally available for this application therefore a three-level converter is a perfect candidate. In this study, a SiC neutral-point-clamped three-level bidirectional DC-DC converter and a three-level flying capacitor bidirectional DC-DC converter, are designed and compared in terms of operation principle, voltage balancing control, inductor design and loss analysis. Prototypes are built and verified at 1100V, 40kW with 99.4% efficiency.
