Voltage Oscillation Suppression for the High-frequency bus in Modular-Multi-Active-Bridge Converter

The EMI issues, such as high-frequency oscillation (HFO) caused by the high dv/dt and parasitic elements have been becoming an challenge in the modern power electronics. Modular-multi-active-bridge (MMAB) converter, in which active bridge modules are linked with high frequency transformers (HFT), is a typical power converter with a large number of switching semiconductor and magnetic devices. The mechanism of HFO in MMAB is studied by the analysis of the oscillation tank firstly. Then, from the perspective of the oscillation tank and the excitation source itself, two suppression strategies including the passive voltage clamping method and active selected harmonic elimination general phase shift modulation (SHE-GPS) method are proposed, respectively. Finally, the effectiveness of both methods is verified and compared by experimental results. The research results in this letter can be utilized in other topologies such as dual active bridge (DAB) and may provide some inspiration to solve the similar HFO problem