EMI noise splitting into common and differential modes in PWM inverter drive system

Separating conducted EMI noise into different, common- and differential- mode (CM and DM) HF current, components is important to the appropriate spectral analysis and the application of EMI mitigation techniques. In this paper an analytical approach to decomposition of total phase EMI noises through algebraic calculations and the Fourier trans- form has been presented. The results of calculations have been compared to EMI currents measured on the motor side of the PWM drive system. The proposed approach can be useful in a comparative analysis of the influence of inverter control algo- rithms onto spectra of CM currents in a given drive system.