Black-box Modeling of Common-mode Interference in Motor Drive Systems and Transfer Function Analysis Method for Near-field Radiated Interference

Motor drive devices are widely used in multi-electric systems and constitute major sources of interference. However, quantitative analysis of their conducted and radiated electromagnetic interference remains challenging. This paper constructs a common-mode conducted interference black-box model of the power converter based on external characteristic measurement data using the Thévenin equivalent method. Based on this model, the near-field radiated interference of motor drive cables on sensitive equipment is quantitatively predicted by combining the common-mode black-box model with the cable coupling transfer function method. The analysis results show that the proposed black-box model can accurately predict the common-mode interference current of the device. Moreover, when the common-mode current fluctuates due to filter insertion or load variations, the transfer function method eliminates the need for repeated three-dimensional electromagnetic simulations to obtain the interference voltage at the sensitive device port, thereby improving prediction efficiency. Experimental results verify that the proposed method can be effectively applied to the quantitative analysis of near-field radiated electromagnetic interference in motor drive systems.