Modeling and design of common-mode inductor for conductive EMI noise suppression in DC-fed motor drive system

Single and three-phase common-mode (CM) inductors play a vital role in conductive CM noise suppression for motor drive system. In this paper, the CM conductive noise propagation path in the dc-fed motor drive system is analyzed. One measurement-based characterization method is discussed for determining the noise propagation path. Meanwhile, modeling methods for the impedance of both single and three-phase CM inductors are reviewed and verified experimentally. With the CM inductor impedance model and CM propagation path characterization, the suppression of both DC and AC CM noise is accurately predicted to be within a 5 dBμA design margin from 10 kHz to 30 MHz. Based on the modeling and verification, this paper also proposes a practical method for high density CM inductors design using MATLAB Optimization Toolbox^®.