How to suppress IGBT switching noise in frequency converters

Suppressing IGBT switching noise in inverters is a core aspect of EMC design, requiring a three-pronged approach: source mitigation, path absorption, and shielding. The dv/dt and di/dt generated by the rapid switching of IGBTs are the main noise sources. Source suppression can employ active clamping, soft-turn-off drive technology, or adjusting the gate resistance to optimize switching speed, choosing the optimal value while ensuring efficiency and heat dissipation. High-frequency absorption capacitors, such as low-ESL film capacitors or MLCC arrays, should be connected in parallel near the DC bus terminals and the IGBT collector-emitter junction to absorb switching voltage spikes. Adding an RC snubber circuit to the IGBT module can effectively dampen voltage oscillations.

In terms of path, the main power loop area should be minimized, with a compact layout of the DC bus capacitors, IGBTs, and absorption elements; using laminated busbars instead of cable connections is ideal. Simultaneously, an isolated DC-DC converter with enhanced filtering should be used for the IGBT drive power supply, for example, by adding common-mode suppression measures to the primary and secondary sides of the isolation transformer. Structurally, the IGBT power module should be mounted on a metal heatsink and grounded through a low-impedance path, using the heatsink as a shield. By comprehensively applying these technologies and combining them with capacitors and filtering solutions provided by Eternity Electronics that are suitable for high-frequency spike absorption, IGBT switching noise can be significantly suppressed, and conducted and radiated interference can be reduced.