Electric drive module having motor with heat sink insert in rotor shaft

A motor drive system comprising:

• an electric motor having a stator and a rotor assembly that is received in the stator and rotatable about a rotational axis, the rotor assembly having a rotor shaft and single fin set, the rotor shaft defining a bore that is disposed longitudinally along the rotational axis, the bore defining an inner circumferential surface, the single fin set being unitarily and integrally formed and having a hub and a plurality of fin members and, wherein a central hole is formed through the hub along the rotational axis, the fin members being fixedly coupled to the hub and extending radially outwardly therefrom, the fin members cooperating to define an outer circumferential surface of the single fin set, the fin members being spaced circumferentially apart from one another about the rotational axis to define a plurality of longitudinally extending slots, the single fin set being received into the bore in the rotor shaft such that the outer circumferential surface of the single fin set engages the inner circumferential surface of the bore in the rotor shaft, and wherein each of the longitudinally extending slots is bounded on a radially outer side by the inner circumferential surface of the bore in the rotor shaft, wherein the central hole forms a first fluid passage that is configured to transmit cooling fluid through the single fin set in a first direction along the rotational axis, and wherein the longitudinally extending slots form a plurality of second fluid passages that are configured to transmit cooling fluid through the single fin set in a second direction along the rotational axis that is opposite the first direction.