具有自然均压能力的双向隔离式模块化DC-DC变换器两级移相循环调制

A two-level phase-shift circulant modulation for bidirectional isolated modular DC-DC converter (BI-MDC) with natural-balance capability, suitable for medium-voltage DC applications, is proposed in this paper. The BI-MDC features a modular half-bridge structure on both the primary and secondary sides, which reduces the number of switching devices and eliminates the impact of arm circulating currents. This topology combines the modular multilevel DC-DC converter with the dual-active-bridge structure. Moreover, the submodule (SM) capacitor voltages are naturally balanced through circulant modulation, which ensures the safe operation of the converter. Additionally, a high operating frequency is synthesized from a low switching frequency, which effectively reduces the size of passive components and switching losses. Furthermore, bidirectional power flow is enabled based on the phase-shift control. Simulation and experimental results validate the feasibility of the proposed approach, demonstrating that the SM capacitor voltages are naturally balanced, and all power switches operate with zero-voltage switching.