Compensating a non-uniform air gap of an electric machine by varying the flux density across the gap

摘要

Arrangement to compensate a non-uniform air gap (119) in an electric machine is disclosed. The non-uniform air gap allows compensation and absorption of: gravity-forces, which act on the components of the rotor; aerodynamic loads, which are induced from the hub via the shaft to the generator; mass-inertia created by the rotating elements of the generator; magnetic forces, which act on the elements of the generator; or vibrations. Since the cross section of the air gap changes along its length the air gap is not uniform. To compensate for this non-uniformity the magnetic flux density of the magnets varies dependent on the cross section of the air-gap; the wider the gap the stronger the magnet. The electrical machine this applies to contains a stator arrangement and a rotor arrangement. The stator contains a lamination stack (110), which is constructed to support at least one winding of a stator-coil (111). The rotor rotates around a longitudinal axis and has a plurality of permanent magnets (118). The magnets of the rotor interact with the winding(s) of the stator arrangement to generate electrical power. The air gap is located between the permanent magnets and the winding(s), the winding being supported by the lamination stack of the stator. The permanent magnets are arranged opposite to the lamination stack and winding(s) of the stator along at least part of the length of the air gap.