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The purpose of this paper is to investigate advantages of multiphase permanent magnet synchronous motors (PMSM) with fractional slot concentrated windings (FSCW). The investigation is based on comparative analysis and assessment of FSCW PMSM wound as 3, 6, 9 and 12 phase machines suited for low speed applications.

The investigations are focussed on distortions of back electromotive (emf) and magnetomotive force (mmf) with the torque ripples and motors’ performance taken into account. The finite element models with the aid of customized computer code have been adopted for motor winding design and back emf, mmf and motor performance analyses.

The novel multiphase winding layouts were found to offer lower content of sub-harmonics in the mmf waveforms compared with the traditional three-phase machine designs. Moreover, the investigated multiphase machines exhibited higher average value of the electromagnetic torque, while the multiphase PMSM machines with FSCW were further characterized by significantly lower torque pulsations.

The analyses presented in this paper demonstrate that PMSM with FSCW are advantageous to their counterpart three-phase machines. Specifically, they offer higher performance and are more suitable to work with multiple drives supplying segmented winding system. This ability of using multi-drive supply for one motor offers flexibility and cost reduction while increasing fault tolerant power train system.

The purpose of this paper is to analyse and compare the functional parameters of three- and six-phase permanent magnet synchronous motors (PMSM) with fractional-slot concentrated windings (FSCW).

The investigations are focused on the comparison of the distortions of back electromotive force (emf) and magnetomotive force (mmf) waveforms, as well as torque ripples, radial force spatial harmonics and motor performance studies. The finite element models of the test machine and a personally developed computer code have been used to calculate motor characteristics and analyse and synthesise multiphase winding layouts, respectively.

Compared with the traditional three-phase PMSM designs, the proposed six-phase machines are characterized by a significantly lower content of sub-harmonics in mmf waveform distribution. Moreover, the investigated six-phase machines exhibited a higher average value of electromagnetic torque, significantly lower torque ripples and a reduced value of low-order harmonics of the radial component of the electromagnetic force in the air-gap of the machine.

The analyses presented in this paper show that six-phase PMSM with FSCWs are advantageous to their counterpart three-phase machines. Specifically, they are more suited to working with multiple drives supplying a segmented winding system while simultaneously offering higher performance. This suitability to the use of a multi-drive supply for one motor offers flexibility and cost reduction while increasing the fault tolerance of a power train system.

The purpose of this paper is to analyse the stray losses in the windings of permanent magnet synchronous machines (PMSM).

The 2D field model, based on the edge element method (EEM) and

-V formulation, has been developed and utilized for the determination and analysis of stray losses in the PMSM with concentrated windings made of strip conductors. The influence of the supply frequency as well as the slot opening width on the losses caused by eddy currents has been examined. The different arrangements of the conductors in the tape wound coils have been studied. The obtained results have been compared to the reference case when the eddy current effect is neglected.

The usefulness of the proposed methodology of the stray losses evaluation has been tested on the case study problem. It has been observed that the stray losses in the windings of the considered machine can be reduced by choosing the proper value of the slot opening. The dependence of the stray losses on the frequency of the supply currents has been examined. The obtained results show that with the increase of frequency the stray losses caused by the eddy currents in the strip conductors increase.

The proposed 2D field numerical model makes it possible to analyse the stray losses in the tape wound concentrated windings of the PMSM motor. The presented model can be utilized for the optimization of the magnetic circuit of the machine with the aim of minimizing eddy current losses.

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.

More electric aircraft (MEA) is defined as the extensive usage of electric power in aircraft. The demand for electric power in new generation aircraft rises due to environmental and economic considerations. Hence, efficient and reliable starter/generators (SGs) are trending nowadays. The conventional main engine starting system and power generation system can be replaced with an individual SG. The constraints of the SG should be investigated to handle the aviation requirements. Even though the SG is basically an electric machine, it requires a multidisciplinary study consisting of electromagnetic, thermal and mechanical works to cope with aviation demands. This study aims to review conventional and new-generation aircraft SGs from the perspective of electric drive applications.

First of all, the importance of the MEA concept has been briefly explained. Also, the historical development and the need for higher electrical power in aircraft have been indicated quantitatively. Considering aviation requirements, the candidate electrical machines for aircraft SG have been determined by the method of scoring. Those machines are compared over 14 criteria, and the most predominant of them are specified as efficiency, power density, rotor thermal tolerance, high-speed capability and machine complexity. The features of the most suitable electrical machine are pointed out with data gathered from empirical studies. Finally, the trending technologies related to efficient SG design have been explained with numeric datasets.

The induction motor, switched reluctance motor and permanent magnet synchronous motor (PMSM) are selected as the candidate machines for SGs. It has been seen that the PMSM is the most preferable machine type due to its efficient operation in a wide range of constant power and speed. It is computationally proven that the using amorphous magnetic alloys in SG cores increases the machine efficiency more. Also, the benefits of high voltage direct current (HVDC) use in aircraft have been explained by a comparison of different aircraft power generation standards. It is concluded that the HVDC use in aircraft decreases total cable weight and increases aircraft operation efficiency. The thermal and mechanical tolerance of the SG is also vital. It has been stated that the liquid cooling techniques are suitable for SGs.

The demand for electrical power in new generation aircraft is increasing. The SG can be used effectively and efficiently instead of conventional systems. To define requirements, constraints and suggestions, this study investigates the SGs from the perspective of electric drive applications.

The purpose of this paper is to minimize the torque pulsation in Halbach array permanent magnet synchronous machines (PMSMs).

Because of its specific structure, the cogging torque influences the main part of the torque pulsation in a Halbach array PMSM. In this paper, first it is shown that the conventional magnet skewing method does not have a significant effect on the torque pulsation in this motor, and then an improved skewing method with fewer skewing steps is proposed. In this method permanent magnet segments are placed sinusoidally, with two‐step skewing along the rotor. Generalization with different combinations of slots and poles is considered for a Halbach array PMSM.

Using a detailed finite element method (FEM) it was found that with the proposed technique the cogging torque factor is reduced to as low as 8 percent, while the average value of the torque is maintained near the machine nominal average torque.

Halbach array PMSMs are very good candidates for high dynamic performance applications such as aerospace applications due to their high acceleration and deceleration features. This technique also resolves the mechanical vibration and acoustic noise issues, which are caused by torque pulsation and significantly affect machine performance.

The originality of this paper lies in the FEM results. Since Halbach array PMSMs have a special structure it was shown that the conventional skewing method does not work well for this machine. The new proposed technique has a significant effect on the torque pulsation.

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.

Electromagnetic noise of permanent magnet synchronous motor (PMSM) seriously affects the sound quality of electric vehicles (EVs). This paper aims to present a comprehensive process for the electromagnetic noise analysis and optimization of a water-cooled PMSM.

First, the noises of an eight-pole 48-slot PMSM in at speeds up to 10,000 rpm are measured. Furthermore, an electromagnetic-structural-acoustic model of the PMSM is established for multi-field coupling simulations of electromagnetic noises. Finally, the electromagnetic noise of the PMSM is optimized by using the multi-objective genetic algorithm, where a multi-objective function related to the slot width of PMSM stator is defined for radial electromagnetic force (REF) optimization.

The experimental results show that main electromagnetic noises are the 8n-order (n = 1, 2, 3, …) and 12-order noises. The simulated results show that the REFs are mainly generated by the 8n-order (n = 1, 2, 3, 4, 5, 6) vibrations, especially those of the 8th, 16th, 24th and 32th orders. The 12-order noise is a mechanical noise, which might be caused by the bearings and other structures of the PMSM. Comparing the simulated results before and after optimization, both the REFs and electromagnetic noises are effectively reduced, which suggests that an appropriate design of stator slot is important for reducing electromagnetic noise of the PMSM.

In view of applications, the methods proposed in this paper can be applied to other types of PMSM for generation mechanism analysis of electromagnetic noise, optimal design of PMSM and thereby noise improvement of EVs.

The purpose of this paper is to consider thermal analysis as part of an automated sizing and design process. The temperature estimation at characteristic points of the machine, and in particular in permanent magnets, is essential to accurately simulate the electromagnetic behavior and avoid irreversible demagnetization.

In this paper, an electromagnetic dimensioning model, parameterized by finite element analysis, is coupled to a thermal lumped‐parameter model to constitute a fast and efficient design tool for electrical machines.

A parameterized and hybrid FE‐analytical electromagnetic model, which combines analytical and numerical advantages, to archive a fast and accurate electromagnetic simulation results is combined with a thermal lumped‐parameter model for water‐cooled and passive air‐cooled surface mounted permanent magnet synchronous machines (PMSM).

Sizing, electromagnetic and thermal modeling aspects are integrated into an automated design process. The whole design process is demonstrated on two standard industrial servo motors for passive and active water cooling and afterwards compared with available measurements.

The proposed method allows considering thermal aspects during the iterative automated electromagnetic design process of PMSM.