Axial Flux Permanent Magnet Machines: Electromagnetic Design and Advanced Modeling

The interest in axial flux machines has grown in the last few years because of their high-power density and modularity. Due to their geometry, a 3D or quasi-3D finite element model is necessary to simulate their behavior; the analysis of such models is time - consuming, and the iterations needed to derive the final design require much time. This thesis describes a heuristic model based on simple expressions that can be used for a preliminary machine design. Starting from the commonly adopted design constraints, the model derives the main geometric dimensions of the machine, the airgap magnetic flux density produced by the permanent magnets, and the consequent value of the ampere-turns needed to develop the requested torque. Moreover, the thesis presents analytical approaches to derive the electric constant and the efficiency map of the device by analyzing its operative region. Despite the simplifying hypotheses used to derive the model, it is characterized by good accuracy and robustness. The model has been used to design four machines for three different purposes. In each case, Finite Element (FE) simulations of the configuration determined with the heuristic model have been performed to verify the algorithm's effectiveness, assessing that the initial specifications are respected. Furthermore, in two of the three analyzed applications, a prototype was built and tested; the measured values of the no-load airgap magnetic flux density, the induced voltages, and the efficiency map were compared to the ones estimated by the proposed model, highlighting a good consistency between heuristic, FE, and experimental results.