What impact do industrial servo di/dt spikes have on EMC?

In servo systems, di/dt spikes are primarily caused by sudden current changes during IGBT turn-on, generating voltage noise on the parasitic inductance of the circuit and forming a differential-mode interference source. The impact of di/dt spikes is mainly manifested in two aspects:

Firstly, they generate conducted interference through power lines, affecting power grid quality; secondly, they couple to sensitive signal lines through spatial radiation. Based on the Yinte Electronics solution, a CMZ3225A-501T common-mode inductor (500μH) is first used at the DC bus to suppress common-mode current, combined with a PBZ1608A-600Z0T ferrite bead (600Ω@100MHz) to absorb high-frequency components.

Secondly, the drive resistor is optimized by connecting a 10Ω resistor in series at the gate to slow down the switching speed, reducing di/dt from 50A/μs to 20A/μs. Experimental results show that this measure can reduce conducted interference by 8-12dB in the 1-10MHz frequency band, while also reducing interference to the encoder signal.

During design, attention must be paid to the power tolerance of the drive resistor, and an ESDSR05AP should be used to protect the drive chip. The solution complies with the EN 61800-3 standard for speed-regulating electric drive systems.