Patent attributes
An electric motor includes a case, a stator having stator windings, a rotor having a rotor shaft, and at least one main rotor bearing coupling the rotor shaft to the case. Common mode charge builds up on the rotor due to imbalances of the stator. The at least one main rotor bearing has a first electrical resistance between the rotor shaft and the case. The electric motor further includes a rotor discharge bearing coupling the rotor shaft to the case. The rotor discharge bearing has a second electrical resistance between the rotor shaft and the case that is less than the first electrical resistance, causing the common mode charge to discharge through the rotor discharge bearing. In a differing embodiment, a rotor discharge brush coupled between the case and the rotor shaft along the longitudinal axis of the rotor shaft discharges the common mode charge.
