Active common-mode filter for inverter power supplies with unbalanced and nonlinear load

A conventional three-phase four-leg inverter power supply is modified in the neutral leg in order to reduce common-mode high-frequency noise due to the modulation of the inverter. Meanwhile, low frequency common-mode components, which are basically zero-sequence due to unbalanced and nonlinear load, can still be controlled by the neutral leg with a proposed three-dimensional space vector modulation (3D-SVM) strategy and a modified 0-axis control design. It is demonstrated that the proposed active common-mode filter solution is effective at both high and low frequencies.