This paper describes a hybrid method for calculating the performance of a coreless stator axial flux permanent-magnet (AFPM) generator. The method uses a combination of finite-element analysis and theoretical analysis. The method is then incorporated into a multidimensional optimization procedure to optimally design a large power coreless stator AFPM generator. The measured performance of the manufactured prototype compares favorably with the predicted results. The design approach can be applied successfully to optimize the design of the coreless stator AFPM machine.

In this paper, the performance of air-cored (ironless) stator axial flux permanent magnet machines with different types of concentrated-coil nonoverlapping windings is evaluated. The evaluation is based on theoretical analysis and is confirmed by finite-element analysis and measurements. It is shown that concentrated-coil winding machines can have a similar performance as that of normal overlapping winding machines using less copper.

Direct drive wave energy converters are attractive due to the elimination of intermediate mechanical power conversion stages. Longitudinal flux (LF) linear generators with iron-cored stators have so far been dominant in experimental direct drive WECs, but suffer from high bearing loads and unwanted end effects. A novel linear air-cored topology is presented in this paper which eliminates most of the end effects associated with LF iron-cored machines as well as the attraction forces between iron-cored stators and magnet translators. The attraction forces between the opposing sides of the translators of double-sided air-cored machines are also ideally eliminated. An analytical model and an exhaustive optimization procedure for finding the minimum active mass subject to certain performance specifications are developed for the novel topology. Finite element analysis is used to verify and further analyze the model. First test results from a 1 kW experimental machine correspond well with designed values and confirm the feasibility of implementing the novel topology on a small scale.