Ufa University of Science and Technology has received a patent for an electric machine design in which the rotor winding is held by metal rings instead of traditional slot wedges. Developers expect this to increase the proportion of conductive material in the slots and enhance the specific power of synchronous electric machines.
In a conventional rotor, wedges fix the excitation winding, preventing it from shifting under the action of centrifugal forces during rotation. However, the fasteners themselves occupy part of the space in the magnetic core slots. In the proposed design, this task is solved by rings installed on sections of the magnetic core with a reduced diameter. They overlap the slots around the rotor circumference and form a continuous retaining surface.
A protective gasket 0.5–1 mm thick is provided between the rings and the winding. It is proposed to make it from fiberglass laminate, electrical cardboard, or polymer film. The gasket should protect the conductor insulation from abrasion and mechanical damage under loads during rotation.
Increasing the useful cross-section of the slots allows more conductive material to be placed. If the machine's nominal power remains the same, the increased slot fill factor will make it possible to reduce the current density in the conductors, and with it, the thermal load on the winding. According to the developers, this will also increase the overload capacity of the electric machine.
The proposed design can be useful in synchronous electric motors and generators where the rotor winding must withstand significant centrifugal loads. The potential gain is the ability to increase power with the same dimensions or reduce winding heating without changing the nominal power.