A novel three-phase inverter for common-mode voltage reduction in electric drives

This paper presents an active solution for the elimination of the leakage current, in a three-phase PWM inverter drive. With respect to a traditional three-phase bridge, the proposed solution reduces the common-mode voltage variations, both in amplitude and frequency. A novel architecture for the inverter is presented. Between the DC source and the traditional three-phase bridge, two active DC-decoupling devices and a voltage-clamping network have been added. A dedicated control strategy was developed adopting a modified Space Vector PWM modulation, oriented to the reduction of the common-mode voltage variations in the proposed topology. Simulations showing the good performance of the solution are presented. A preliminary prototype was developed and experimental results are presented.