Inverter-Motor System EMI Reduction by Impedance Balancing

This work is concerned with conducted common-mode (CM) electromagnetic interference (EMI) emission of inverter-motor drive systems fed from a dc source. Conducted CM EMI behavior of such drive systems is analyzed by a simplified CM equivalent circuit model, from which a new method is developed to reduce CM current emission by creating a balanced Wheatstone impedance bridge around the CM voltage source. Such impedance balancing method reduces CM current filtering requirements, which usually dominates the EMI attenuation requirements in airborne motor drive systems, and can result in more compact overall system design in terms of volume and weight.