How to meet the CISPR11 limits for frequency inverters?

Ensuring that frequency converters meet CISPR 11 standard limits requires system design tailored to the characteristics of industrial equipment. CISPR 11 applies to industrial environments and is divided into Class A and Class B, with Class B having stricter limits. Key compliance points include: source control, suppressing major noise sources, such as optimizing IGBT drives to reduce switching overshoot and oscillation, employing soft-switching technology, and connecting high-frequency absorption capacitors in parallel on the DC bus. Filtering design, installing compliant EMI filters at the input and output terminals; input filters must effectively suppress conducted emissions from 150kHz to 30MHz, and output filters (such as dv/dt filters) should reduce radiation from motor cables.

Shielding and grounding, ensuring the continuity of shielding in the frequency converter housing and mounting cabinet, properly handling gaps and cable entry points; establishing a low-impedance grounding system to provide a discharge path for noise. Cable handling, using shielded cables for all external cables whenever possible and terminating them correctly. Pre-testing and rectification, using spectrum analyzers and near-field probes during the R&D phase for pre-scanning, locating out-of-range frequencies and making targeted rectifications, such as adding ferrite cores and adjusting filter parameters. Through systematic design and iterative optimization, combined with the filtering and shielding solutions from YENTE Electronics that meet CISPR 11 requirements, frequency converter products can successfully meet the standards.