On the Use of the Delay Compensation Technique to Reduce the Volume of Traction Inverter EMI Filters

The mitigation of conducted EMI is a major challenge in traction inverters, as bulky input filters are often required. Targeting the reduction of the filter volume, this work combines the four-leg topology with the delay compensation technique to maximize the cancellation of the common-mode current at the inverter output during switching transients. An iterative algorithm allows one to find the optimal delays for the switching legs for each commutation, resulting in around 30 dB EMI reduction in the 150 kHz-1MHz range. By relaxing the required insertion loss of the input filter, a conventional twostage EMI filter can be replaced by single-stage solution with reduced inductance, resulting in a 70 % lower filter volume.