Active common-mode voltage cancellation for three-phase PWM rectifier/inverter systems based on a new topology

After giving a summary of investigated passive and active schemes to mitigate common mode problems a modeling approach for the common mode voltage (CM voltage) is presented for three-level rectifiers. A novel active common-mode voltage cancellation (ACC) scheme is proposed, utilizing the reconstructed CM voltage to derive a simpler driving scheme as presented by previous contributions. The ACC scheme function based on switched mode operation is explained, modeling and design of the power circuitry including a 5-winding transformer is outlined and simulation results prove its viability and effectiveness in eliminating CM voltage in a 3-phase/3-level rectifier for telecom systems. A verification of the physical implemented circuitry is obtained from selected measured results on the mentioned overall system.