Design and Assessment of a New Active CM Filtering Architecture for PWM Inverter-Fed Motor Drive Systems

The stepwise common-mode (CM) voltage at the output of inverters causes electromagnetic interference (EMI) and damage to motor bearings. This article proposed a new output active CM filter (ACF) to compensate for the steep rising/falling edges of CM voltage for EMI reduction and bearing protection. An input ACF is also necessary to attenuate the CM noise injected into the grid. Hence, a holistic assessment of input and output ACFs for inverter-fed motor drive systems has been demonstrated. The motor drive system satisfies the CM EMI standard with this new active CM filtering architecture. Ferrite materials and winding configurations of the CM transformer used in the output ACF have been investigated. Moreover, the relationship between the input and output ACFs has been discussed. This article aims to provide new perspectives and implementation guidelines for the ACFs in motor drive systems.