Design of Grid-Side Electromagnetic Interference Filters in AC Motor Drives With Motor-Side Common Mode Active Compensation

The aim of this paper is to analyze how the introduction of a motor-side common mode (CM) active filter, in a power drive system, influences the CM disturbance propagation. A circuit model of the whole drive, including the active filter, is used as an investigation tool. The accuracy of all simulated results is validated by experimental measurements. Both the electromagnetic interference (EMI) toward the grid and the internal CM disturbance propagation are analyzed. These phenomena are compared when the power drive system is operated both with and without the active filter at the inverter output. An additional effect of the motor-side CM active filter is a slight reduction of EMI toward the grid at lower frequencies. This condition allows a reduction in the size of the power grid CM EMI filter necessary to achieve electromagnetic compatibility requirements compliance for the drive.