How does the dead time of the PCS in an energy storage system affect EMC?

Dead time in a PCS (Power Control System) is a common turn-off time set to prevent shoot-through between the upper and lower bridge arms. Its impact on EMC is two-sided.

Negative impacts: Dead time introduces output voltage distortion (dead-time effect), generating low-order harmonics related to the switching frequency. These harmonics can couple into the conducted and radiated spectra. Longer dead times exacerbate this distortion.

Positive impacts: A reasonable dead time ensures that the switching transistor is completely turned off before being turned on, avoiding large current pulses caused by overlapping conduction and the resulting severe di/dt noise. This helps suppress high-frequency EMI spikes.

Therefore, a trade-off is needed when setting the dead time: While ensuring safety (avoiding shoot-through), the dead time should be shortened as much as possible by optimizing the drive circuit and selecting fast components to reduce output voltage harmonics, while relying on other means (such as buffer circuits and filtering) to control the noise of the switching process itself.