Rotor for a permanent magnet electric machine

An electrified drivetrain for a vehicle, comprising:

• a DC power source, a multi-phase power inverter, a multi-phase rotary electric machine, and a torque actuator;
• wherein the multi-phase rotary electric machine includes a rotor assembly and a stator;
• wherein the rotor assembly includes a plurality of first disc-shaped laminates, a plurality of second disc-shaped laminates, a wrap;
• and a rotor shaft;
• wherein the plurality of first disc-shaped laminates and the plurality of second disc-shaped laminates are arranged in a stack on the rotor shaft;
• wherein the wrap is annular and arranged to encapsulate an outer surface of the rotor assembly defined by the plurality of first disc-shaped laminates and the plurality of second disc-shaped laminates;
• wherein the wrap does not cover respective ends of the stack;
• wherein an air gap is formed between the wrap and an inner peripheral surface of the stator;
• wherein each of the plurality of first disc-shaped laminates includes first inner portions and a plurality of first outer portions, the first inner portions and the plurality of first outer portions defining a plurality of first cavities;
• wherein the plurality of first outer portions are secured to the first inner portions via a first web and a plurality of bridges;
• wherein each of the plurality of second disc-shaped laminates includes second inner portions and a plurality of second outer portions, the second inner portions and the plurality of second outer portions defining a plurality of second cavities;
• wherein the plurality of second outer portions are secured to the second inner portions via a plurality of second webs and are absent a bridge;
• wherein a first of the plurality of first disc-shaped laminates is disposed at a first end of the stack, a second of the plurality of first disc-shaped laminates is disposed at a second end of the stack, and a third of the plurality of first disc-shaped laminates is disposed at a middle portion of the stack;
• and
• wherein a fourth of the plurality of first disc-shaped laminates is disposed at a first quarter portion of the stack, a fifth of the plurality of first disc-shaped laminates is disposed at a third quarter portion of the stack, and remaining portions of the stack are populated by the plurality of second disc-shaped laminates.