Design and Testing of a New Linear Topology for Electric Machines

A new linear topology is proposed in this paper for rotating electric machines. The design presented consists of an outer permanent-magnet rotor featuring the same structure as a flexible chain or track made of a sequence of ferromagnetic links connected together by hinges. Toothed wheels are used to convert the linear motion of the track-like rotor into a rotary torque to be transferred to the shaft. The stator portion is the same as for a double-sided linear electric machine. The proposed linear topology makes the electric machine suitable for installation in long thin compartments. A perspective application can be envisioned to direct drive wind generators: the linear machine topology makes the generator suitable for installation inside the wind tower, while conventional cylindrical generators need to be fit into the nacelle. The proposed design has been investigated by finite element analysis simulations and has been implemented into a technology demonstrator for experimental validation.