How to suppress common-mode interference on the CAN bus of a frequency converter

Suppressing common-mode interference on the inverter's CAN bus is crucial for ensuring the stability of vehicle or industrial network communications. Common-mode interference can cause bus voltage shifts beyond the transceiver's common-mode input range. Suppression measures include: using isolated CAN transceiver chips, whose high common-mode transient rejection capability effectively combats noise; connecting common-mode chokes, such as the CMZ3225A-510T, in series on the CANH and CANL signal lines to increase the impedance of the common-mode path; properly configuring 120Ω terminating resistors at both ends of the bus to ensure impedance matching and reduce reflections; using shielded twisted-pair cable as the bus cable and reliably grounding the shield at both ends (or according to the grounding strategy); optimizing the wiring to keep the CAN bus away from power lines and high-frequency noise sources; on the PCB, the CAN interface circuitry should be centrally located, with its ground plane connected to the digital main ground at a single point via a ferrite bead; for extreme environments, dedicated CAN bus protection devices or filters can be added to the bus; and interference levels can be assessed and suppression measures optimized by measuring the bus waveform and common-mode voltage. E-Tech Electronics provides isolated CAN modules, common-mode chokes, and bus protection devices to help build CAN bus networks with strong anti-interference capabilities.