Does the low-frequency harmonics in the PCS (Power Control System) of an energy storage system couple into an EMC (Electronic Material Control) problem?

Low-frequency harmonics (such as power frequency harmonics) generated by PCS typically do not directly cause exceedances in standard EMC conducted emissions tests (starting frequency 150kHz), but they can indirectly cause EMC problems. The main pathway is through saturation of the filter core components. For example, large-amplitude low-frequency harmonic currents can cause the common-mode inductor core to operate in the nonlinear region, resulting in a significant drop in impedance at high frequencies. This weakens the ability to suppress high-frequency switching noise, thus worsening high-frequency EMI.

Furthermore, low-frequency harmonics, as background noise, can affect the accuracy of internal analog sampling circuits or cause intermodulation with other interferences in wide-frequency immunity tests. Therefore, it is still necessary to optimize the modulation algorithm to reduce current harmonic distortion and ensure that the filtering components operate within the linear range.