Design and development of a single CM filter for bearing current and ground current reduction in a dual two level inverter fed open end winding induction motor drive

A dual two-level inverter with an open-end winding induction motor can realise a three/four level voltage space vector. High switching frequency coupled with the use of such multilevel inversion system can produce good motor drive performance. This however can generate immense machine shaft voltage and bearing currents apart from large leakage ground currents that are deleterious to the motor drive system and add to the malfunctioning of many safety equipment. To circumvent the above problems, this work presents the design and development of a single common mode (CM) passive filter for the above power circuit. With the application of the suggested single CM filter, both the bearing currents and the common mode currents are successfully attenuated. The proposed CM filter requires less hardware compared to the use of two CM filters reported in the literature. Simulations using MATLAB/Simulink is used to demonstrate the efficacy of a single CM filter. Also, the single CM filter is experimentally verified with an open-end winding motor fed from two inverters on both sides.