How to suppress interference in the EPSIGBT drive resistor?

Optimizing the drive resistor (Rg) of the IGBT in an EPS is an effective way to suppress switching interference and improve EMC. Rg directly affects the switching speed (dv/dt, di/dt). Optimization directions for suppressing interference include:

1. Reducing switching speed to decrease EMI: Appropriately increasing Rg (especially the turn-off resistor Rgoff) can slow down the switching speed, thereby reducing voltage and current spikes and oscillation amplitude, and reducing high-frequency noise spectrum energy. This comes at the cost of increased switching losses.

2. Asymmetric drive strategy: A smaller turn-on resistor (Rgon) is often used to reduce turn-on losses, while a larger turn-off resistor (Rgoff) is used to suppress turn-off overvoltage and EMI.

3. Suppressing parasitic conduction: Connecting a reverse diode in parallel with the turn-off resistor (or using a smaller turn-on resistor) ensures fast turn-off and prevents parasitic conduction caused by Miller capacitance.

The optimal Rg value needs to be found through double-pulse testing, finding the best balance between switching losses, temperature rise, and EMI spectrum.