A Bidirectional Modular Multilevel Resonant DC–DC Converter for Wide Voltage Range Medium-Voltage Power Conversion

The arm inductor is found to cause the loss of soft switching in modular multilevel resonant dc–dc converters, so a full-range soft switching converter with wide voltage gain is proposed in this article. The modular multilevel structure and the
CLLC
resonant tank are utilized in the converter for isolated and bidirectional power conversion in medium-voltage applications with high efficiency. Wide and continuous voltage gain regulation can be achieved with the proposed coordinated gain control method. The submodule voltages are balanced by voltage sampling and individual gate signal controls. The requirements for full-range soft switching are explained. Finally, a laboratory prototype is constructed and the experimental results verify the theoretical analysis.