Project : Solving Radiated Emissions of a Motor Drive

Timescale: One working day

Scope of Work: An electric drive unit (EDU) did not pass the radiated emission test in the EMC chamber, necessitating further investigation and troubleshooting. Initial findings indicated that the noise might originate from the SMPS on the PCB, although confirmation through experimental results is required. Additionally, the client has requested a review of the compliance aspects of this unit. The EDU is intended for use in both automotive (ECE Reg 10.06) and marine applications.

Troubleshooting Progress:

  • Current probe measurements indicate that the noise that comes from the 12V line radiates the most. 
  • Further analysis (including near-field probe measurement and cross-checking on the suppliers’ design) shows that the buck-boost converter is the noise culprit. 
  • Various methods were tried to reduce the noise. However, the noise reduction was not significant enough to give us a confident pass.
  • At this stage, it is clear that the bad layout practice of the buck-boost converter contributed to the high level of noise we see. Often, we need a re-design to fix issues such as these. It is also found that the ground-to-chassis connection on the current design has had no impact in reducing the EMI noise in the hundreds of MHz range.