How to optimize EMI in inverter circuit of frequency converter

Optimizing EMI in the inverter circuit of a frequency converter requires focusing on suppressing this highest-frequency noise source. The inverter circuit includes DC bus capacitors, IGBT modules, and output filtering components. Optimization strategies include: using multilayer busbars or closely parallel copper busbars to connect the DC bus capacitors and IGBT modules to minimize parasitic inductance in the power circuit, which is fundamental to reducing switching overvoltage and radiation. Configuring optimized gate drive resistors for the IGBT modules balances switching speed and EMI. Connecting multilayer ceramic or film capacitors with excellent high-frequency characteristics in parallel on the DC bus provides high-frequency current to the IGBTs nearby, absorbing switching noise.

Installing output filters, such as sine wave filters or dv/dt filters, at the inverter output can smooth the output voltage waveform and significantly reduce common-mode and differential-mode noise on motor cables. For internal radiation, the inverter power board can be covered with a metal shield and properly integrated with the heatsink. Optimizing the PCB layout, perpendicularly crossing drive signal lines and power lines, and isolating them with a ground plane. Scanning the inverter area with a near-field probe to identify hotspots and specifically enhance shielding or filtering. Eintech provides complete solutions from high-frequency bus capacitors to output filters, helping engineers systematically optimize inverter circuits and achieve better EMC performance.