High frequency modeling of bearing currents and shaft voltage on electrical motors

The paper proposes a general method to investigate the common mode high frequency current components flowing through electrical motors supplied by electronic converters, especially focusing on bearing currents. An innovative model is defined able to address a wide frequency range (50 kHz/3 MHz) for EMI/EMC issues. By connecting the obtained model with an appropriate model of the whole electric drive, prediction of HF phenomena occurring at the addressed frequency becomes possible using a standard simulator such as Spice. A detailed analysis on a standard 3.5 kW induction motor is carried out and simulation and experimental results are presented