How to connect the EPS shield ground and power ground?

The connection method between the shield ground (chassis and cable shielding ground) and the power ground (circuit operating ground) in an EPS (Electric Power Supply) system must consider both safety and EMC. A common and recommended approach is to connect them at a single point with low impedance, typically near the grounding point of the power filter or DC-Link capacitor. This point is called the "star ground" or "clean ground" reference point. The advantages of this connection are:

1. It provides a clear, low-impedance discharge path to the chassis for the filter's Y capacitor and common-mode noise current.

2. It avoids ground loops formed by multiple connections.

3. It meets safety grounding requirements. The connection should use short, thick conductors (copper busbars or braided tape), with a large and reliable contact area at the connection point.

For complex systems where there may be a large ground potential difference (such as multiple units in parallel), it may be necessary to connect via an RC network or discharge tube to block low-frequency high currents while maintaining high-frequency continuity.