How to optimize EMC of the PCSIGBT drive resistor in an energy storage system?

Optimizing the drive resistor (Rg) of the IGBT in the PCS is an effective and low-cost way to improve the switching waveform and control EMC. Rg directly affects the switching speed (dv/dt, di/dt). Optimization directions:

1. Reduce turn-on di/dt and turn-off dv/dt to reduce EMI: Appropriately increasing Rg (especially the turn-off resistor) can slow down the switching speed, thereby reducing voltage and current spikes and oscillations, and reducing high-frequency noise spectrum energy. However, this comes at the cost of increased switching losses and temperature rise.

2. Balance EMI and losses: Asymmetrical drive is usually used, i.e., a smaller turn-on resistor (Rgon) to reduce turn-on losses, and a larger turn-off resistor (Rgoff) to suppress turn-off overvoltage and EMI.

3. Suppress parasitic conduction caused by Miller capacitance: Connect a reverse diode in parallel with the turn-off resistor or use a smaller turn-on resistor to ensure fast turn-off. The optimal value needs to be found through double-pulse testing to find a balance between switching losses, temperature rise, and EMI spectrum.