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This paper aims to find the optimal winding topology for a 14‐pole permanent magnet synchronous motor (PMSM) to be used as an in‐wheel motor in automotive applications.

Comparison is first performed among lap windings with different combinations of slot numbers and pole numbers. A general method for calculating the winding factors using only these numbers is proposed, thus the preferable slot numbers resulting in relatively large winding factors for this 14‐pole PMSM are found. With these slot numbers, the Joule losses of armature windings are further investigated, where the impacts of different end‐winding lengths are considered. By this means, the optimal slot number that causes the least Joule loss is obtained. On the other hand, as a competitor to lap windings, toroidal windings are also discussed. The thermal performances of these two types of windings are compared by performing a finite element analysis (FEA) on their 2‐D thermal models.

For the 14‐pole in‐wheel PMSM discussed in this paper, the preferable slot numbers leading to relatively large winding factors are 12, 15 and 18. However, with the specified geometry constraints, the optimal choice of slot number is 15, which results in the least Joule loss and thus the highest efficiency. On the other hand, by implementing the toroidal winding topology, the armature windings of this machine can be effectively cooled and thus allow a larger electrical loading than the lap windings do.

This work can be continued with investigating the impacts of different combinations of slot number and pole number on harmonics and cogging torques.

This paper proposes a general method for calculating the winding factor of PMSMs using only the phase number, the slot number, and the pole number. With this method, the calculation procedure can be easily programmed and repeated.

This paper is aimed at investigating the potential advantages of flux‐switching machines (FSM) compared to permanent magnet synchronous machines (PMSM), particularly for the applications of electric vehicle traction.

A 12‐slot 14‐pole PMSM designed for an in‐wheel traction application is chosen for the comparison. With the same volume constraint, three 12/14 FSM structures are created. Both the PMSM and the three FSM structures are modeled using the software Flux. Based on these models, finite element analyses (FEA) are performed, and the results are compared in terms of open‐circuit back electromotive force (EMF), electrical loading capability, and thermal conditions.

Within the same volume constraint, a 12/14 FSMs can achieve the maximum torque higher than the one of 12/14 PMSM. This conclusion is drawn based on the observed facts that at the same rotor speed, a larger open‐circuit back EMF is induced in the FSM, while a larger electrical loading is also allowed in this machine, compared to the PMSM. In addition, the risk of demagnetization during the process of field weakening proves to be lower in FSMs than PMSMs. This advantage suggests a potentially wide constant power speed range (CPSR) of FSMs, which is especially beneficial in automotive applications.

This research can be continued with investigating the field weakening capability and iron losses of FSMs.

This paper proposed two optional structures of FSMs to reduce the amount of permanent magnets. It also highlighted the effectiveness of FSMs in cooling these magnets.

Today's brushless permanent magnet (PM) drive systems usually adopt motors including the advancements in magnet technology, e.g. better thermal characteristics and higher magnetic strength. By this means, they become capable in the roughest applications yet maintain a high accuracy at competitive prices. These drive systems are not only appreciated for their high performance, but they are also advantageous for the applications requiring tough, dependable, and continuous‐duty operations, e.g. hybrid or complete electrical vehicles, extruders, wire drawers, winders, cranes, conveyors, and roll formers. The purpose of this paper is to provide an extended comparative study of the different motor configurations for the hybrid electric drive application, aiming at a compromise between high power density and extended speed capability.

To suit strict design requirements, such as the very limited volumetric envelope, high‐output power, wide constant power speed range, and pre‐selected in‐direct cooling system, the constraint variants of possible motor types are researched.

Considerably, high torque density and an extended speed range limit the options of PM rotor configurations for this motor design. The considered rotor configurations are the surface PM (SPM) and interior PM (IPM) types. The advantage of the (non‐salient) SPM configuration is its applicability with higher levels of magnetic flux densities without causing significant saturation in the rotor. On the other hand, an IPM rotor, which places the magnets in special rotor slots, open or closed (by saturation bridges), can operate on both the reluctance torque and the magnet alignment torque. This generally leads to a better performance in a wide speed range. However, this advantage can be eliminated by severe iron saturation resulting from the required high‐specific power.

The most appropriate rotor configuration will finally be selected between the two considered types, depending on detailed electromagnetic and thermal analysis. This paper usefully studies the correlation between the motor parameters required for high power density and field‐weakening performance.

The purpose of this paper is to give a simple, fast and universal inductance calculation approach of slotless-winding machines and comparison of inductances of toroidal, concentrated and helical-winding machines, since these winding types are widely used among low-power PM machines.

Harmonic modeling approach is applied to model the magnetic field of the windings in order to calculate the synchronous inductances. The method is based on distinction between electromagnetic properties of different regions in the machine where each region is represented by its own governing equation describing the magnetic field. The governing equations are obtained from Maxwell’s equations by introducing vector potential in order to simplify the calculations.

Results of the inductances of toroidal, concentrated and helical-winding slotless PM machines, which have the same torque and dimensions, obtained by the proposed analytical method are in good agreement with 3D FEM, where the relative difference is smaller than 15 percent. However, the calculation time of the analytical method is significantly less than in 3D FEM: seconds vs hours. Additionally, from the results it is concluded that the toroidal-winding machine has the highest inductance and DC resistance values among considered machines. Helical-winding machine has lowest inductance and DC resistance values. Inductance of concentrated-winding machine is between inductance of helical and toroidal windings; however, DC resistance of the concentrated windings is comparable with resistance toroidal windings.

In this paper the inductance calculation based on harmonic modeling approach is extended for toroidal and helical-winding machines which makes the method applicable for most of the slotless machine types.

The space‐mapping (SM) optimization technique, with its input, implicit or output mapping‐based implementations, provides a basis for computationally efficient engineering optimization. Various algorithms and design optimization problems, related to microwave devices, antennas and electronic circuits, are presented in numerous publications. However, a new application area for SM optimization is currently expanding, i.e. the design of electromechanical actuators. The purpose of this paper is to present an overview of the recent developments.

New algorithm variants and their application to design problems in electromechanics and related fields are briefly summarized.

The paper finds that SM optimization offers a significant speed‐up of the optimization procedures for the design of electromechanical actuators. Its true potential in the area of magnetic systems and actuator design is still rather unexplored.

This overview is complementary to the previous published reviews and shows that the application of SM optimization has also extended to the design of electromechanical devices.

The purpose of this paper is to study the performance and efficiency of two different permanent magnet (PM) machine rotor configurations under magnetic core saturation conditions.

Since the accuracy of conventional analytical methods is limited under saturation conditions, a finite element model of the machine is built; which is used to predict the various losses over its operating range such as eddy current, hysteresis, copper and magnet losses. Using this model, the efficiency map of the machine is derived which is used to investigate its efficiency corresponding to a heavy vehicle drive cycle. The performance of two different rotor designs are studied and the efficiency of each design is compared under the considered drive cycle.

It has also been proved that the performance advantage due to reluctance torque in the v-shaped interior PM (IPM) machine is offset by its core steel saturation at higher current/torque levels. The magnitude of iron losses in the IPM is higher than that in the surface PM (SPM) machine, however, the magnet loss in the SPM is higher than in the IPM.

An investigation of the performance of the IPM design in comparison with the SPM∼design under magnetic saturation conditions is not known to the authors. Hence, in this paper, it will be determined if the assumed performance advantage of the IPM over the SPM still holds true under these conditions.