EMI filter design of DC-fed motor-drives using behavioral EMI models

Behavioral EMI models for the prediction of common-mode (CM) and differential-mode (DM) noise based on Thevenin equivalents were developed earlier for a dc-fed motor-drive system. It was shown that beyond the switching frequency of the drive, the CM noise model behaved like a two-port linear network and could predict changes in the input-side EMI due to any changes in the load-side parameters or vice versa. This CM model was then complemented with linear one-port DM behavioral models to predict the total noise at both the input and the output side of the motor-drive up to 30 MHz. The work presented here proposes a method to use these behavioral EMI models for simultaneous design and optimization of EMI filters on both the input and the output side of the motor-drive system, such that the total size of all filters is minimum. All filter designs are experimentally validated against the DO-160 standards for aerospace applications up to 30 MHz. The problems limiting the accuracy of the proposed method are clearly discussed.