Research on electrostatic shield for discharge bearing currents suppression in variable-frequency motors

High frequency current activity in the bearings of variable-frequency motors coupled to their shaft is presently a common issue, ultimately shortening the bearings lifetime. This paper presents a method for suppressing high-frequency discharge bearing currents. This method provides a stator partial electrostatic shield to reduce the capacitive coupling between the stator windings and the rotor within the motor. From the perspective of electromagnetic field, electrostatic shield layer can block electromagnetic coupling produced by the common mode voltage. In this paper, the theory of suppression techniques is analyzed, implemented. And, the starting performance of the motor is also analyzed. In order to verify the shielded result, the experimental platform is built.