The development of a new generation of energy efficient, high torque and power density electrical machines is part of a solution toward the global energy problem. An important step in improving electrical machine performance involves optimization of the machine geometry, winding configuration, and overcoming limitations within traditional magnetic materials. In electrical machine, the magnetic iron core accounts for a significant portion of its weight and size. Under a rotating magnetic field, conventional iron cores are subjected to a nonuniform magnetic field distribution. This leads to uneven saturation distribution, extra core loss, and sub-optimal utilization of the permeability at certain regions within the iron cores. Deploying materials with non-homogeneous magnetic permeability can lead to a more uniform magnetic flux density distribution and potentially better power density. Additionally, a multi-permeability iron core, where the permeability is tuned as a function of both position and electrical machine performance, can lead to a more efficient use of the core and an additional degree of freedom for core design. This work evaluates the use of iron cores with non-homogeneous magnetic permeability for electrical machines. It is numerically demonstrated that an iron core with spatially tuned permeability can be used to manipulate the airgap flux density waveform, torque, and iron loss in electrical machines.Exploration and exploitation of non-homogeneous iron cores for electrical machines requires an accurate, low cost modelling technique. Finite element analysis can be used to model non-homogeneous iron cores but it can lead to an expensive computational requirement. Traditional magnetic equivalent circuits can provide quick estimation of the electrical machine performance in comparison to finite elements. However, this technique typically models just the main flux path and/or ignores the permeability in the iron cores. In this work, a technique is developed to model non-homogeneous, multi permeability iron cores in electrical machines. It is shown that the proposed technique closely approximates finite element results and reduces the simulation time nearly 80%. It is also demonstrated that the modelling technique can be integrated into a multi-objective optimization problem for development of novel iron cores.Additive manufacturing, also known as 3D-printing, is a layer-based manufacturing technique which can fabricate unique, complex shapes. It also has the potential to fabricate non-homogeneous iron cores. Adoption of these complex iron cores for development of high performance electrical machines requires understanding of the magnetic properties and demonstration that printed iron cores can reach variable levels of permeability. In this work, the B-H characteristics are experimentally extracted using conventional magnetic characterization techniques. A simplified magnetic anisotropy test bed was developed to quantify levels of magnetic anisotropy. It is shown that 3D-printed iron cores can achieve different levels of relative permeability and low levels of magnetic anisotropy.
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