A motor-generator for converting between electrical and rotational energy includes a rotor mounted for rotation about an axis of rotation relative to a stationary a stator that magnetically interacts with the rotor. The rotor has two spaced apart rotor portions that define therebetween an armature airgap. Magnetic poles on the rotor portions drive magnetic flux across the airgap. An air core armature is located in the airgap, such that opposite sides of the air core armature face the two opposed rotating surfaces of the rotor. The air core armature has windings in which AC voltage is induced as the rotor rotates. The windings are wound with multiple individually insulated strand conductor wire wrapped with a wrapping of a thin dielectric tape film over the multiple individually insulated strand conductor wire.