How to suppress circulating EMI when power modules of a PCS in parallel are connected in an energy storage system?

In a PCS system with multiple power modules operating in parallel, inconsistencies in module parameters and slight differences in drive signals can lead to circulating current. This circulating current not only increases losses but also generates additional differential-mode and common-mode EMI noise. The key to suppressing circulating EMI lies in suppressing the circulating current itself and controlling its path:

1. Current sharing design: Select modules with consistent parameters, optimize the synchronization and symmetry of drive signals, and employ active current sharing control.

2. Magnetic integration: Use coupled inductors or interleaved parallel technology to naturally suppress circulating current through magnetic coupling.

3. Isolation and filtering: Configure an independent common-mode inductor for each module's output, for example, using CM-L series common-mode inductors for separate filtering to prevent circulating current from forming loops between modules.

4. Optimize interconnect impedance: The AC parallel bus between modules should be short and thick, and symmetrical to reduce unbalanced impedance.

5. Grounding strategy: Ensure that the ground reference point potential of each module is consistent to avoid ground loops becoming circulating paths.