How to reduce the high-frequency grounding impedance of frequency converters

Reducing the high-frequency impedance of the inverter grounding system is crucial for discharging high-frequency noise current and improving shielding effectiveness. At high frequencies, the inductance of the grounding conductor becomes the primary impedance. Reduction measures include: using short, wide grounding conductors, such as flat copper busbars or braided copper strips, whose inductance is much smaller than that of a round wire of the same cross-sectional area. At grounding connections, use large-area metal-surface contacts, such as directly mounting the inverter base plate on a galvanized mounting beam and securing it with multiple screws to provide multiple low-inductance connections.

On the PCB, design multiple arrays of grounding vias for the power device heatsink mounting surfaces, directly connecting to the internal ground plane or metal base plate. The cabinet's grounding busbar should use copper busbars and be welded or bolted to the cabinet frame at multiple points. All grounding connection points must have their paint and oxide layers removed to ensure direct metal-to-metal contact; toothed washers can be used. For high-frequency noise, the grounding path length should be much less than 1/10 of the noise wavelength. The high-frequency performance of the grounding system can be evaluated and optimized by measuring the grounding loop impedance (e.g., using a network analyzer). Eintech provides low-impedance grounding strips and conductive pads to help build efficient inverter grounding networks.