Electric drive system with brush polarity flip control

A vehicle comprising:

• an electric motor having a stator assembly, and a rotor assembly with a rotor shaft;
• a base plate, a first slip ring and a second slip ring operatively connected to an outer side of the rotor shaft, the first slip ring and the second slip ring being rotatable relative to a longitudinal axis of the rotor shaft;
• a first set of brushes mounted on a first side of the base plate, the first set of brushes being adapted to establish an electrical connection with the rotor assembly through contact with the first slip ring;
• a second set of brushes mounted on a second side of the base plate, the second set of brushes being adapted to establish the electrical connection with the rotor assembly through contact with the second slip ring;
• and
• a controller having a processor and tangible, non-transitory memory on which instructions are recorded, the controller being adapted to selectively apply a respective brush break-in mode during an initialization period;
• and
• wherein the controller is adapted to exit the respective brush break-in mode when at least one exit condition is met, the brush break-in mode permitting the first set of brushes and the second set of brushes to experience positive polarity at various rotor current levels.

A vehicle comprising:

• an electric motor having a stator assembly, and a rotor assembly with a rotor shaft;
• a base plate, a first slip ring and a second slip ring operatively connected to an outer side of the rotor shaft, the first slip ring and the second slip ring being rotatable relative to a longitudinal axis of the rotor shaft;
• a first set of brushes mounted on a first side of the base plate, the first set of brushes being adapted to establish an electrical connection with the rotor assembly through contact with the first slip ring;
• a second set of brushes mounted on a second side of the base plate, the second set of brushes being adapted to establish the electrical connection with the rotor assembly through contact with the second slip ring;
• and
• a controller having a processor and tangible, non-transitory memory on which instructions are recorded, the controller being adapted to selectively apply a respective brush break-in mode during an initialization period;
• wherein the controller is adapted to exit the respective brush break-in mode when at least one exit condition is met, the respective brush break-in mode permitting the first set of brushes and the second set of brushes to experience positive polarity at various rotor current levels;
• wherein the controller is adapted to apply the respective brush break-in mode with torque generation, including maintaining a baseline DC rotor current, maintaining a non-zero stator current, and maintaining an AC rotor current at a relatively constant value;
• and
• control a power input to the electric motor such that a peak-to-peak value of the AC rotor current is greater than twice the baseline DC rotor current.