Reduced common-mode noise modulation strategies for gradient driver with cascaded H-bridge multilevel structure

This work presents detailed analysis for the Common Mode Voltage (CMV) in a two stages cascaded gradient driver system. The vector modulation method is proposed to eliminate or reduce the CM voltage in a cascaded system without a neutral or ground point. The method is demonstrated through two stages example but can be extended to topology with more stages in cascaded. Meanwhile, the power stage output ringing caused by the stray parameters is analyzed in detail and proper damping method is proposed. A hardware prototype is fabricated and tested to validate the analysis.