Assessment of Conductive EMI of Nonlinear Consumers of Common DC Bus with PWM

The assessment method of the DC-circuit analogues for the voltage and current THD values is here generalized to an arbitrary number of nonlinear loads. This technique is based on the method of the differential equations algebraization, and it makes it possible not only to predict the quality of power supply at the design stage for the power supply system with known analytical descriptions of nonlinear consumers' currents, but also to assess their individual relative share contributions in the overall distortion of power quality. The analytical expression for the DC-circuit arbitrary order integrated signal harmonics factor's dependence on the amplitude modulation index is obtained for the PWM-modulated pulse signal by using the infinite series harmonic synthesis formulae. The lowest orders' DC-circuit harmonic factors' dependences on the amplitude modulation index are presented and verified through PSIM computer simulations. The ripples of the supply voltage at the filter output generated by two common DC bus nonlinear loads in the form of PWM-modulated current sources at varied phase shifts of the PWM carrier triangle signals are estimated for the PSIM model particular parametres.