Winding capacitance cancellation for three-phase EMC input filters

Techniques have been presented in the literature for canceling stray capacitances for inductors in single-phase power filters. With the same aim, the alternatives provided by three-phase systems are explored here. A thorough theoretical analysis is presented, where pros and cons of parasitic capacitance cancellation networks are highlighted and improvements are proposed. A systematic mathematical procedure to evaluate impedances for different noise modes in three-phase circuits is presented. The influence of parasitic effects is accessed and asymmetric capacitance cancellation is proposed, facilitating applications in switched power circuits. Experimental results are shown demonstrating the effectiveness of the presented techniques in an electromagnetic compatibility filtering application.