DRIVE UNIT

A drive unit includes an electric motor for propulsion and a cooling system. The electric motor includes a stator assembly and a rotor assembly, the stator assembly including a housing, a core with grooves, and a winding assembly. The winding assembly extends through the grooves. The housing includes a housing inlet and outlet. The cooling system includes a first cooling circuit to enable a direct cooling of the winding assembly. The first cooling circuit includes an expansion tank assembly, including a tank, a tank inlet and outlet, and a volume change assembly. The volume change assembly enables change of the total volume of the first cooling circuit as a function of pressure in the first cooling circuit such that, as the pressure in the first cooling circuit increases, a first volume is increased and, as the pressure in the first cooling circuit decreases, the first volume is reduced.