Expandable rotor

An electric machine, comprising:

• a stator and a rotor positioned in operational engagement with one another and defining a radial gap extending circumferentially between the stator and the rotor;
• the rotor including a plurality of rotor segments defining a plurality of segment gaps between adjacent pairs of the plurality of rotor segments, the plurality of rotor segments radially moveable relative to the stator and flexibly held in position relative to one another such that when the rotor spins, centrifugal forces cause the plurality of rotor segments to move radially outward expanding the radial gap between the rotor and the stator and the segment gaps between adjacent pairs of the plurality of rotor segments;
• and
• a sleeve extending circumferentially around the plurality of rotor segments, the sleeve adapted to stop movement of the plurality of rotor segments radially outward to limit further expansion of the radial gap and including a plurality of ferrous wedges extending radially inward, one ferrous wedge extending into the segment gap between each adjacent pair of rotor segments and adapted to provide a continuous conductive connection between each adjacent pair of rotor segments as the plurality of rotor segments move radially outward and the segment gap between each adjacent pair of rotor segments increases.