How to optimize EMC for industrial servo IGBT/SiC drivers?

The EMC optimization priorities for IGBT and SiC MOSFET drive circuits differ. For IGBTs, the optimization focus is on mitigating turn-off dv/dt to reduce voltage spikes and radiation: a diode can be connected in parallel with the gate drive resistor to achieve asymmetrical drive (fast turn-on, slow turn-off), and active Miller clamping can be used. For faster SiC devices, the optimization focus is on controlling turn-on di/dt and suppressing parasitic parameters in the drive loop: a dedicated low-inductance packaged driver IC is used, and a ferrite bead (such as PBZ1608A-102Z0T) is connected in series with the gate to absorb ultra-high frequency oscillations.

Common measures for both include using an isolated drive power supply (such as a transformer or isolated DC-DC), and filtering the secondary power supply with a PWR4020R2R2M0T. The drive signal is transmitted using twisted-pair shielded cable, with the shield connected to the drive terminal ground. After optimization, the switching losses of SiC devices can be reduced by 15%, while suppressing the ultra-high frequency (>30MHz) radiated noise they generate by 8-10dB, meeting the stringent EMC requirements of new energy vehicles or high-end servo systems.