Common-mode Electromagnetic Interference Mitigation for Solid-state Transformers

Solid-state transformers (SSTs) have been widely used in many areas owing to their advantages of high-frequency isolation and high power density. However, high-frequency switching causes severe electromagnetic interference (EMI) problems. Particularly, the common-mode (CM) EMI caused by the switching of the dual active bridge (DAB) converter is conducted through the parasitic capacitances in the high-frequency transformer and impacts the system reliability. With the understanding of the CM EMI model in SSTs, CM EMI mitigation methods have been studied. For passive mitigation, the coupled inductor can be integrated with the phase-shift inductor function to reduce CM EMI. For active mitigation, variations in the DAB switching frequency can help reduce the CM EMI peak. An active EMI filter can also be designed to sample and compensate for CM EMI. Using these methods, CM EMI can be reduced in SSTs.