Abstract: An improved homopolar motor-generator having a hollow rotor, or a plurality of nested hollow rotors connected in series, with one magnetic pole of the stator located inside the rotor. This enables both sliding electrical contacts to be located close to the axis of rotation and thus decreases the linear velocity at the sliding contact. An alternative design of this invention comprises a hollow magnetized stator with an annular slot through which one or several ?-shaped current-carrying rods are free to rotate. The rods can also be embedded in a single cylindrical rotor. This design also enables the sliding electrical contacts to be located near the ends of the rods, and therefore close to the axis of rotation, and similarly decreases the linear velocity at the sliding contact.

Abstract: The main disadvantage of homopolar generators, motors and engines is a small working voltage and a high working current which make it difficult to change parameters of the generators, motors, and engines such as torque, which is important, for example, in motor vehicles where the starting torque is very large. Therefore decreasing the working current (or equivalently increasing the working voltage) at given homopolar generator (motor, engine) power is very important for homopolar devices. The proposed multi-frames (cylinders) generator-motor solves this problem by using a rotor consisting of two or more conductors electrically connected in series. Also, in difference of other homopolar devices, where some continuously-sliding electrical contacts (collectors) are located at the outer edge of rotor that can lead to overheating of the contacts, in the proposed designs all sliding electrical contacts are located at the inner edges of the rotor discs (cylinders) that preventing their overheating.