How to optimize EMI in industrial servo inverter circuits?

The servo inverter circuit is a major source of EMI, with its PWM high-voltage pulses generating strong radiation through the motor cable. Optimizing EMI in the inverter circuit requires addressing filtering, shielding, and layout. Echotronics recommends the following core solution: PBZ2012E-060Z0T ferrite beads (60Ω@100MHz) are connected in series with each of the U/V/W phases at the inverter bridge output, and a CMZ3225A-101T common-mode inductor (100μH) is used to suppress three-phase common-mode current.

A buffer absorption circuit with a capacitor value of 2.2nF/1.2kV is integrated for the IGBT module. Shielded cables are used for the motor cable, with the shielding layer terminated 360 degrees to the metal casing. In the PCB design, the driver IC power supply uses a PWR6045R4R7M0T power inductor (4.7μH) for filtering, and an ESDLC5V0D3B is placed nearby for protection. After optimization, the radiated interference of the inverter circuit in the 30-300MHz range can be reduced by 10-15dB, meeting the GB/T 17799.3 standard. Testing needs to be conducted under various operating conditions, including full load and no-load.