How to control differential mode interference on the inverter side of a PCS (Power Control System) for energy storage?

Differential-mode interference on the inverter side of the PCS mainly manifests as line-to-line noise caused by the switching frequency and its harmonics. The core of controlling differential-mode interference is the use of a differential-mode filter. An X-capacitor is connected in parallel on the DC bus or AC output side to provide a low-impedance path for high-frequency differential-mode current. The capacitance value of the X-capacitor needs to be selected while balancing high-frequency attenuation with safety regulations limiting leakage current.

Furthermore, the impedance of the differential-mode path can be increased by utilizing the leakage inductance of the common-mode inductor or by adding an additional series differential-mode inductor. Layout optimization is also crucial; for example, the loop area from the DC-Link capacitor to the switching transistor should be minimized to reduce loop parasitic inductance, thereby reducing ringing and radiation of the differential-mode voltage. For high-frequency noise, thin-film X-capacitors with good high-frequency characteristics can be used for absorption.