This paper deals with the design and optimization of a 2.1 MW rim-driven electric thruster for ship propulsion. For this purpose, a double stator ironless rotor axial flux permanent magnet (AFPM) motor is considered as the propulsion motor. The analytical model of the selected AFPM motor is presented. The magnetic field in the AFPM machine is calculated using the 3D magnetic charge concept in combination with image theory and permeance functions to take into account the stator slotting effects, and a simple thermal model is used to evaluate the heat dissipation capabilities of the machine and the thermal dependence of the main electromagnetic losses. To optimally design the AFPM, an optimization process based on genetic algorithms is applied to minimize the cost of the active motor materials. An appropriate objective function has been constructed, and different constraints related to the main electrical, geometrical, and mechanical parameters have been taken into account. The achieved results are compared with the performance of a podded radial flux permanent magnet (RFPM) motor, which is considered a reference propulsion motor. The obtained results show a fairly satisfactory improvement in the cost and masses of the active motor materials. Finally, the accuracy of the obtained optimum solution is validated by performing 3D finite element analysis (3D-FEA) simulations.

This paper presents a 3D calculation method of magnetic flux density in fully ironless axial flux permanent magnet (AFPM) machine. The method is based on the 3D magnetic charge representation of the permanent magnet. The real geometry of the coils and Biot-Savard law are used to model the stator windings. This modeling method allows computing with very good accuracy the main electromagnetic specifications of such unconventional machines such as magnetic flux, back Electromotive Force (EMF), electromagnetic torque, and inductances. This calculation method is applied to a prototype of a single-sided Fully Axial Flux Permanent Magnet Machine for validation purposes. Calculation results are in good agreement with those obtained with experimental measurements. This method appears to be very suitable to be used in systematic design process for such structures.

This paper aims to determine the airgap magnetic flux density of a surface-mounted Permanent Magnet Vernier Machine (PMVM) by considering both rotor and armature Magneto-Motive Forces (MMFs). The calculation method relies on permeance and MMF concepts to predict the mid-airgap flux density. Two Magnetomotive-Permeance Function (MMF-PF) methods are applied and compared: the first one is based a predefine flux lines permeance function model, while the second one employs a conformal transformation approach to evaluate the airgap permeance function. A square waveform is chosen for the MMF in both models. The effectiveness of these methods is assessed using Finite Element Analysis (FEA), focusing on an outer rotor PMVM as a case study. Results indicate that the first method is more accurate in calculating the armature magnetic field, whereas the second method proves more efficient for predicting the rotor magnetic field. The combined approach leveraging both methods offers a reliable and expedient alternative to FEA, particularly useful during the initial design phases of PMVMs.