How should carrier isolation be designed for concentrators?

The concentrator carrier communication circuit and the internal main control circuit require electrical isolation to prevent grid noise intrusion and ensure safety. Isolation design includes signal isolation and power isolation.

Signal isolation: The TX and RX signals of the carrier chip are connected to the MCU through a digital isolator (such as ADuM1401) or an optocoupler (high-speed optocoupler such as 6N137).

Power isolation: An independent isolated power supply is provided for the carrier circuit, typically using a DC/DC isolation module (such as a custom transformer winding or module), with an isolation withstand voltage ≥2.5kVrms.

Circuits on both sides of the isolation boundary should be physically separated on the PCB, maintaining sufficient creepage distance (e.g., 8mm/300V). The isolation ground (carrier-side ground) should be connected to the chassis ground through a Y capacitor (e.g., 2.2nF/Y1) to provide a discharge path for common-mode noise. With this isolation design, the carrier circuit can withstand a 4kV surge without affecting the main control system.