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The purpose of this study is to develop a novel mechanical flux-weakening topology for the switched flux permanent magnet (SFPM) machine to extend the speed range, which will be suitable for the electric vehicles and hybrid electric vehicles.

The 3 dimensional mechanical flux-weakening model with flux adjusters (FAs) in the end-cap is established. Subsequently, the electromagnetic performance is compared between the SFPM machine with FAs in the end-cap and without FAs. The open circuit flux-linkage is calculated by finite element analysis (FEA) to investigate the influence of this mechanical flux-weakening topology together with the d/q-axis inductance. The flux-weakening capability and torque-speed curve is also calculated.

The proposed topology decreases the permanent magnet flux-linkage and increases the d-axis inductance, which improve the flux-weakening capability simultaneously. Subsequently, the speed range and constant power region are much wider than those without FAs. Finally, the prototype is fabricated and the measured result of the open circuit back electromotive force has good agreement with the FEA result.

This paper provides a novel mechanical flux-weakening topology with FAs in the end-cap for the SFPM machine, whose volume is smaller than another mechanical flux-weakening topology with FAs at the stator outside. Thus, higher torque and power density can be obtained compared with the SFPM machine with FAs at the stator outside.

The purpose of this paper is to comparatively study the conventional, i.e. single magnet, and novel hybrid-magnet switched-flux permanent-magnet (HMSFPM) machines.

The HMSFPM machines utilize two magnet types, i.e. low-cost ferrites and NdFeB. Thus, a set of magnet ratios (?), defined as the quotient of the NdFeB volume to the total PM volume, is introduced. This allows any desired performance and cost trade-off to be designed. Series- and parallel-excited magnet configurations are investigated using 2-dimensional finite element analysis.

The torque of the HMSFPM machines is lower than the NdFeB SFPM machine but the flux-weakening performance is improved for similar machine efficiency. If the machine dimensions are unconstrained, the HMSFPM machines can have the same torque for reduced material costs and a moderate increase in machine dimensions. Ferrite SFPM machines have the lowest cost for the same torque but a significant increase in machine dimensions is required. Finally, the series-excited HMSFPM machine is the preferred over the parallel-excited HMSFPM machine because it has superior demagnetization withstand capability.

Mechanical and winding eddy current losses are not considered in the efficiency map calculations.

The NdFeB SFPM, ferrite SFPM, series-excited HMSFPM, and the parallel-excited HMSFPM machines are compared for their electromagnetic performance, flux-weakening, PM demagnetization, efficiency, and material costs.

The purpose of this paper is to investigate the influence of end‐effect and cross‐coupling on the torque‐speed characteristics of switched flux permanent magnet (SFPM) machines.

The torque‐speed characteristics are predicted using two different methods. These are direct and indirect finite element methods, at different cross‐coupling levels, namely, full cross‐coupling on both PM flux linkage and dq‐axis inductances, partial cross‐coupling on the PM flux linkage only and without cross‐coupling.

The influence of the cross‐coupling on dq‐axis inductances of the studied machine is relatively small. However, it is more significant on the PM flux linkage. Therefore, the partial cross‐coupling model, which is much easier and faster, exhibits almost the same accuracy as the full cross‐coupling model. Furthermore, the end‐effect causes a large reduction in torque‐speed characteristics. However, such a reduction is more significant in the flux weakening operation region.

This is the first time that the influence of end‐effect of SFPM machines on the torque‐speed characteristics, especially in flux weakening region, and on the dq‐axis inductances has been investigated.

The purpose of this paper is to investigate and compare the influence of end-effect on the torque-speed characteristics of three conventional switched flux permanent magnet (SFPM) machines having different stator/rotor pole combinations, i.e. 12/10, 12/13 and 12/14 as well as three novel topologies with less permanent magnets (PMs), i.e. multi-tooth, E-core and C-core.

SFPM machines combine the advantages of simple and robust rotor and easy management of the temperature due to the location of the PMs and armature windings on the stator. However, due to spoke location of the PMs a large flux leakage in the end region, i.e. end-effect, can be observed which could result in a large reduction in the electromagnetic performance. Therefore, the influence of end-effect on the torque-speed characteristics is investigated. 3D-finite element analyses (FEA) results are compared with their 2D-FEA counterparts in order to account for the end-effect influence.

It has been concluded that due to end flux leakage, lower torque capability in the constant torque region is observed in the six machines. However, improved flux-weakening capability in the conventional machines can be exhibited at high current levels, whereas due to the large inductance lower power capability in the multi-tooth, E-core and C-core machines is obtained.

The influence of temperature rise on the performance is not included.

This paper has analysed the influence of end-effect on the torque-speed characteristics of several SFPM machines.

Due to linear structure, linear switched flux permanent magnet machines (LSFPMMs) also may have odd pole primary, such as 9, 15, 21, etc., without unbalanced magnetic force in equivalent rotary machines. The paper aims to discuss these issues.

In order to increase the thrust force density, the influence of some major design parameters, including split ratio, PM thickness, primary slot width and secondary pole width, are investigated by finite element analysis. For reducing the thrust force ripple under on-load condition, the end auxiliary teeth are adopted and their positions are also optimized.

This novel 9/10 primary/secondary poles LSFPMM has high average thrust force and low thrust force ripple by optimization. The results demonstrate that the odd pole primary may be a good candidate for long-stroke linear direct drive application.

A novel 9/10 primary/secondary poles linear switched flux permanent magnet machine is developed in this paper. The similar conclusions could be obtained for other LSFPMMs with odd pole primary.

The purpose of this paper is to propose the design concepts of external rotor switched flux hybrid magnet memory machine (SFHMMM) to further increase the torque capability while keeping the merits of internal rotor SFHMMM, such as adjustable back-EMF, and good flux weakening performance, etc.

The torque enhancing principle of external rotor SFHMMM, and the design considerations such as feasible stator and rotor pole numbers (N_s/N_r ) are discussed by equations. Then, the performances such as back-EMF, dq-axis inductances, torque and flux weakening performances are calculated and compared with the aid of finite element analysis software.

The external rotor SFHMMMs have obviously larger torque capabilities compared with the internal rotor ones under the same copper loss and machine size. The main reason is that the external SFHMMs could fully utilize the inner space of stator, which offers higher slot area, larger split ratio and consequently the higher average torque. For the external rotor machines with larger rotor pole number N_r , the back-EMF adjust ratio as well as the maxim torque are better. However, leakage flux and losses also increase with Nr due to limited machine size and higher operation frequency. Considering torque capability and flux weakening performance (efficiency map), the external SFHMMM with N_r =2N_s +1, e.g. 6/13 N_s/N_r stator/rotor pole machine, is the optimal choice.

This paper introduces the design concept and design considerations of external SFHMMM for the first time. The proposed machine could be a competent candidate for direct-drive electric vehicle applications.

The paper purposes a novel SFPM machine topology with radial and circumferential permanent magnets (PMs). The paper aims to discuss this issue.

In order to reduce the flux leakage in the stator-outer region and consequently achieve higher magnetic material utilization in switched flux permanent magnet (SFPM) machine, a novel topology with radial and circumferential PMs is proposed. This topology (SFRCPM) has the same structure as conventional SFPM (CSFPM) machine except of the additional set of radially magnetized PMs located around the back iron and surrounded by a laminated ring frame. Using finite element analysis (FEA) the influence of the design parameters on the performance is investigated in order to obtain an effective optimization procedure. Internal and external rotor SFRCPM machines with either NdFeB or ferrite magnets are investigated, optimized and compared with the CSFPM machine having the same size, copper loss and stator/rotor pole combination.

It is concluded that comparing SFRCPM with its CSFPM machine counterpart, internal rotor SFRCPM machine can achieve high PM flux-linkage per magnet volume, however reduced slot area leads to low output torque, whereas external rotor SFRCPM machine can produce higher torque and torque per magnet volume.

This paper proposes a novel SFPM machine topology.

The paper aims to propose and compare two new structures of a three-phase wound field salient rotor (WFSR) switched-flux motor (SFM) with 24 stator slots and 10 or 14 rotor poles, respectively, for high-speed operation.

The paper outlines the motor general construction and design concept of proposed machines. Flux linkage, average torque, rotor mechanical strength and torque–speed characteristics of both machines were analyzed and compared by two-dimensional finite element analysis (2D-FEA). Deterministic optimization method was adopted to enhance the characteristics of 24Slot-10Pole WFSR SFM.

The paper provides simulation results and discusses how 24Slot-10Pole WFSR SFM structure is superior to the 24Slot-14Pole in the aspects of flux linkage, average torque and power. It further concludes that the optimized design of 24Slot-10P has achieved 58 and 72 per cent higher average torque and power compared to initial design, as well as high average torque and power compared to 24Slot-14P design.

Optimized structure of the 24Slot-10Pole WFSR SFM with non-overlapping windings has been proposed.

The purpose of this paper is to propose a novel type of switched flux PM machines with two separate stators.

2D-FEA is employed to analyze the electromagnetic performance of the proposed machines. Moreover, the results are validated by experiments.

The proposed machine has higher torque density, less unbalanced magnetic force on the modulating steel piece and uses less PM volume.

The proposed machine is a low-cost novel topology with different rotor pole combinations.

The purpose of this paper is to compare the performance of conventional, novel E‐ and C‐core switched‐flux permanent magnet (SFPM) machines having different combinations of stator and rotor pole numbers, with particular reference to the conductor and magnet eddy current loss and iron loss.

The electromagnetic performance of the analysed machines is compared using the finite element (FE) analysis.

Both iron and conductor eddy current losses increase with the rotor pole number, while the 11‐ and 13‐rotor pole machine always exhibit lower magnet eddy current loss than those of the 10‐ and 14‐rotor pole machines, respectively. The E‐ and C‐core machines use half the number and volume of magnets and also exhibit higher efficiency than those of the conventional SFPM machine.

Investigation of the influence of stator and rotor pole combinations on the performances of conventional, novel E‐ and C‐core SFPM machines, include losses and efficiency.