It is well known that multi-phase machines exhibit better performance (efficiency, torque density, fault tolerance, etc.) than 3-phase machines. From the manufacturing point of view, it is interesting to have the possibility of improving a machine design by just conducting minor changes in the production process. In this regard, 6-phase machines emerge as the natural choice to improve a design without modifying the active parts. This paper presents an optimal procedure to shift from a 3-phase to a 6-phase induction motor design by just rearranging the coil connections. By starting from a 3-phase winding design, different 6-phase winding arrangements are analyzed. A methodology to define all the possible 6-phase winding arrangements is presented. Discard criteria based on balanced radial forces and impedances are defined. Afterwards, selected winding candidates are compared in terms of analytical calculations and later on, based on FE simulations for a 690 V, 1 MW induction machine design. Different possible configurations are evaluated in terms of stator Joule losses, torque ripple, power factor and electromagnetic efficiency both under healthy and faulted inverter conditions. Finally, a 6-phase machine prototype is tested in order to verify the improvement in machine characteristics, thus validating the proposed method.

This paper proposes loss & thermally optimised copper and aluminium structures for automotive electrical machines. A first batch of multiphysics optimisation is performed parametrically for 6 different electrical conductor topologies. Then, a multiphysics – thermal and electromagnetic – hybrid parametric and topology optimisation coupled with Multi Objective Differential Evolution (MODE) and with an additional step of Local Search (LS) is proposed. The introduced Topology Optimisation (TO) algorithm is explained in detail and applied to optimise electrical conductor geometries of pure Cu and AlSi10Mg. After that, the manufacturing by Additive Manufacturing (AM) of the most promising model is presented. The produced topology is benchmarked against a well-known fully rectangular structure. The proposed topology optimised geometry has been found to improve conventionally manufactured electrical conductors at intermediate frequencies, around 600-800 Hz, and improves considerably at high frequencies, achieving a reduction in losses of 58% at 2000 Hz comparing to a conventional rectangular copper structure.

This paper proposes a combined electromagnetic and mechanical topology optimization for weight reduction in electrical machines based on Finite Element Analysis (FEA) and Evolutionary Structural Optimization (ESO). The devised method is an on- off-type algorithm with adaptative mesh in which low flux density and low Von Mises stress cells are removed successively from a first machine design. With this approach, the weight of the machine can be considerably reduced without compromising the electromagnetic performance of the machine, with a reduced computation time compared to other topology optimization methods. A case study involving a 1.2 MW low-speed, permanent magnet motor is analyzed under different conditions (algorithm parameters, initial mesh, rotational speed) and used to compare the proposed method with two other topology optimization approaches.

This paper studies the feasibility of using synchronous reluctance machines (SynRM) for low speed–high torque applications. The challenge lies in obtaining low torque ripple values, high power factor, and, especially, high torque density values, comparable to those of permanent magnet synchronous machines (PMSMs), but without resorting to use permanent magnets. A design and calculation procedure based on multistatic finite element analysis is developed and experimentally validated via a 200 Nm, 160 rpm prototype SynRM. After that, machine designs with different rotor pole and stator slot number combinations are studied, together with different winding types: integral-slot distributed-windings (ISDW), fractional-slot distributed-windings (FSDW) and fractional-slot concentrated-windings (FSCW). Some design criteria for low-speed SynRM are drawn from the results of the study. Finally, a performance comparison between a PMSM and a SynRM is performed for the same application and the conclusions of the study are summarized.

In the last few years, the reduction of the dependency on rare‐earth magnets has been one of the main concerns for electrical machine manufacturers. Synchronous reluctance machines (SynRMs) and ferrite permanent magnet‐assisted synchronous reluctance machines (PMa‐SynRMs) are emerging as alternatives to permanent magnet synchronous machines (PMSMs) in several applications. In low‐speed high‐torque applications, PMSMs with large amounts of rare‐earth magnets are commonly employed. Thus, it is of particular interest to replace PMSMs by SynRMs or PMa‐SynRMs. This article studies the feasibility of using SynRMs and ferrite PMa‐SynRMs for a direct‐drive elevator system. The challenge lies in obtaining performance characteristics comparable to those of PMSMs, but without resorting to the use of rare‐earth permanent magnets. The main criteria for designing SynRMs and PMa‐SynRMs for low‐speed high‐torque applications are presented. Afterwards, a SynRM and a ferrite PMa‐SynRM are designed for 160 rpm 200 Nm rated conditions, and a performance and cost comparison between these machines and a commercial PMSM is conducted.

Losses created by skin and proximity effects can be significant in medium to high-speed ac machine designs. These have been extensively studied for form wound coil machines, but regarding randomly-placed round-wire windings, bundle-level proximity losses have been either neglected, computed via finite element (FE) simulations or estimated analytically by methods that require to know the location of each strand within the slot. This article presents a practical, yet accurate method to estimate bundle-level proximity losses in random-wound ac machines without having to specify the location of each individual conductor. The method consists on approximating the turn size and the arrangement of the conductors within the slot from the overall dimensions of the slot and the winding via simple expressions. This procedure is successfully validated via FE simulations and by constructing and experimentally testing two Interior Permanent Magnet Synchronous Machine prototypes with different winding characteristics.