Wiener Filtering Applied to Conducted EMI Estimation in Soft Switching Inverter

This paper presents an estimation method of the conducted electromagnetic interference EMI emissions in soft switching inverters. Estimation process is carried out by a number of Wiener filters, which represent different operation conditions as reflected through subsequent power converter states determined by initial commutation event conditions and propagation paths layout. Filters are fed by a semiconductor power switch voltage or current waveforms regarded as sources of perturbation. The EMI emissions are measured on the line impedance stabilization network LISN terminals. Optimal filter adaptation is effected in the frequency domain by measuring input and cross power signal spectra. Analysis of parallel quasi resonant dc link voltage inverter PQRDCLI is outlined to distinguish filters assigned for inverter operation and those for an external DC/DC converter interaction. Experimental results are given to illustrate the Wiener filtering estimation quality. Possibility of detailed decomposition of the LISN-EMI waveforms is depicted in both time and frequency domain. Comparative analysis of frequency responses for PQRDCLI link voltage changes is given.