How to suppress switching noise in inverter drive resistors

Adjusting the drive resistor of the inverter's IGBT is an important and flexible means of suppressing switching noise. The gate resistor directly affects the IGBT's switching speed: increasing the gate resistor slows down the switching process, reduces dv/dt and di/dt, thereby effectively reducing voltage overshoot, current spikes, and switching noise, but at the cost of increased switching losses and heat generation. Therefore, it is necessary to find the optimal balance between EMI and efficiency. Asymmetrical resistors are usually used, i.e., the turn-on and turn-off resistors have different values. The turn-off resistor can be slightly larger than the turn-on resistor to suppress voltage spikes during turn-off, which is particularly effective in reducing EMI.

Sometimes a fast recovery diode is connected in parallel with the gate resistor to create different turn-on and turn-off paths, achieving finer control. In addition to the main gate resistor, connecting a small capacitor in parallel between the gate and emitter can also filter high-frequency noise, but this will also increase the switching time. Optimization steps: First, determine the approximate range of the resistor based on the datasheet and loss calculations. Then, observe the switching waveform through a double-pulse test, adjust the resistor value until overshoot and oscillation are acceptable, and finally, perform a whole-machine EMC test to verify the effect. Yinte Electronics' drive solutions include gate resistor selection guidance to help customers quickly optimize their systems.