Design and Simulation of a Slotless Aircored PM Synchronous Generator

Abstract: This thesis is a study on an unconventional slow speed direct drive permanent magnet (PM) generator. Unlike a standard permanent magnet synchronous generator (PMSG) which has the copper coils wound around iron teeth, the work in this thesis will present a generator where the copper coils are directly mounted on the stator which eliminates the slots and teeth in the generator. By having a slotless design it is possible to eliminate cogging torque, iron losses in teeth and achieve a lightweight design. These characteristics can prove useful when developing generators for an application such as wind turbines, or more specifically vertical axis wind turbines (VAWTs) in remote areas where weight and serviceability is of concern. This thesis consists of two main parts where the main focus was on the design and simulation of slotless generators. The second part of the thesis was to investigate an available slotless axial flux machine. For the simulations, three different models were created in 2D using CAD software. Two of the models were double-rotor slotless generators and one was a single rotor variant. The electromagnetic properties of these models were analysed using FEMM and COMSOL. The results showed that the double rotor variant with the smaller magnets were more favourable considering the price of magnets and no iron core losses. The experimental results of the axial flux machine gave insight into the construction of commercially available axial slotless generators which could be used to further analyse these types of machines.