Performance Enhancement of Flux Switching Motor for Electric Vehicle Applications: An Overview

Saeidabadi S., Parsa L., Corzine K., Kovacs C., Haugan T.J.

Madanzadeh S., Gruber W., Jastrzebski R.P.

Mugyema M., Kamper M.J., Wang R.

Zhu D., Peng B., Wang C.

Ertan H.B., Siddique M.S., Koushan S., Azuaje-Berbeci B.J.

Mendonça G.A., Galo D.P., Sales L.C., Cardoso Filho B.J., Maia T.A.

Restrictive regulations regarding emissions and fossil fuel consumption lead to the electric vehicle being an alternative to replace conventional internal combustion engine vehicles. The pure electric powertrain technology and the charging infrastructure are still immature in some markets, where increasing the overall vehicle efficiency by energy harvesting means can be a more viable solution. This paper presents the design and experimental validation of an in-wheel flux-switching machine for regenerative braking in a light passenger vehicle. Later, the energy can be used for fuel handling and reforming, performance enhancement, increasing efficiency, and reducing emissions. Feasibility and technological challenges are also discussed. The Maxwell–Fourier method and a novel steady-state equivalent circuit presented in this paper are used for geometry sensitivity analysis and optimization routine.

Udosen D., Kalengo K., Akuru U.B., Popoola O., Munda J.L.

Global industrialization, population explosion and the advent of a technology-enabled society have placed dire constraints on energy resources. Furthermore, evident climatic concerns have placed boundaries on deployable energy options, compounding an already regrettable situation. It becomes apparent for modern renewable energy technologies, including wind generators, to possess qualities of robustness, high efficiency, and cost effectiveness. To this end, direct-drive permanent magnet (PM) wind generators, which eliminate the need for gearboxes and improve wind turbine drivetrain reliability, are trending. Though rare-earth PM-based wind generators possess the highly sought qualities of high-power density and high efficiency for direct-drive wind systems, the limited supply chain and expensive pricing of the vital raw materials, as well as existent demagnetization risks, make them unsustainable. This paper is used to provide an overview on alternative and viable non-conventional wind generators based on the so-called non-PM (wound-field) stator-mounted flux modulation machines, with prospects for competing with PM machine variants currently being used in the niche direct-drive wind power generation industry.

Idoko H.C., Akuru U.B., Wang R., Popoola O.

Brushless stator-mounted traction motors, which are new and emerging, have many potential applications in the electrified transport industry. Brushless stator-mounted machines (BSSMs), with the so-called flux modulation (FM) effects, use asynchronous field harmonics to realize energy conversion by altering the basic principle for conventional machine design which requires the stator and rotor to have the same pole number. The machines show promise of meeting the challenging requirements of electric vehicle (EV) traction motors. Therefore, in this paper, a review is undertaken on the state-of-the-art and potentials of the BSSMs for EV drives. The focus on BSSMs is due to their suitability for high-speed high torque density performance, as well as possessing suitable heat dissipation and flux weakening capabilities. The study is used to first rehash and discuss the design and excitation topologies, operating principles, and some emerging trends based on the basic BSSM variants, e.g., the doubly salient machine, flux reversal machine, and flux switching machine, while also undertaking a bibliometric synthesis on relevant studies highlighting the design and performance candidature of these niche BSSMs in EV applications, especially when compared to the well-developed Prius–IPM motor.

Okada T., Saito M., Kosaka T., Matsumori H., Matsui N.

This paper focuses on a hybrid excitation flux switching motor (HEFSM) using variably magnetizable permanent magnets (VM-PMs) as variable flux motors for EV/HEV propulsion. The HEFSM makes an energization of field excitation coil unnecessary for most of the operating conditions so that it enlarges high efficiency operating area thanks to reductions of both copper and iron losses by adequately controlling magnetization state of the VM-PMs according to given operating conditions. In this paper, a new HEFSM design is proposed, which employs a novel PM arrangement as well as a flat motor shape with an optimum L/D ratio aiming at total PM usage reduction and the variable flux capability and maximum torque improvement. FEA-based simulation results show that the motor efficiency and variable flux capability of the proposed HEFSM are comparable with those of a previous PM-rich HEFSM while satisfying the target maximum torque and demagnetization tolerability of PMs under the total PM usage limitation.

Akuru U.B.

Sharouni S., Naderi P., Hedayati M., Hajihosseini P.

Herein, a novel study on outer rotor flux-switching permanent magnet (OR-FSPM) machines for motor/generator applications is presented. An improved magnetic equivalent circuit (MEC) is used for saturable machine model, and the performance analysis is presented in both dynamic and steady-state cases. A flexible MEC-based method is used, where the machines with arbitrary properties can be analysed. Moreover, the model accuracy can be tuned by selective parameters in the proposed method. It is shown that the machine can be used as a high efficiency 400 Hz Ground Power Unit (GPU) for aircraft application. Furthermore, the machine usage for in-wheel application in the hybrid and electric vehicles (HVs and EVs) is analysed. Comparison with 2D and 3D finite-element-method (FEM) shows the effectiveness and accuracy of the proposed MEC method, where shorter processing time is obtained compared with FEM.

Chen H., EL-Refaie A.M., Demerdash N.A.

Flux-switching permanent magnet (FSPM) machines have been gaining interest over the last few decades. This is due to the several advantages that this type of machines provides. These advantages include high torque density due to the flux-focusing effects, favorable thermal management due to the location of PMs on the stator, passive and hence robust rotor structure which is suitable for high-speed applications, etc. The two-part companion articles are going to provide a comprehensive analysis of FSPM machines in terms of opportunities and challenges. In the first part of these two-part series, it covers the principle theory, computation methods, various topologies of FSPM machines, and the comparison with other PM machines. Meanwhile, the basic performance characteristics and design requirements, viz. torque density, over-load torque capability, flux-weakening capability, fault-tolerance capability, as well as the latest development, are also provided.

Chen H., EL-Refaie A.M., Demerdash N.A.

Flux-switching permanent magnet (FSPM) machines have received an intense amount of research interest in recent years, due to their advantages of high torque/power density, favorable thermal management, as well as passive and robust rotor structure. The purpose of this two-part companion articles is to provide a comprehensive overview of FSPM machines in terms of opportunities and challenges. In the early part of this two-part series, the operating principle, the modeling methods, the various machine topologies of FSPM machines, as well as the comparison with other PM machines, have been analyzed and investigated. Building upon Part (I), this article covers the analysis and design of winding configurations, the practical techniques to minimize the cogging torque and torque ripple, the control strategies, the technical challenges, as well as the emerging trends of FSPM machines. Moreover, the key features of the FSPM machines, including the merits and demerits of such machines as well as their associated techniques, are highlighted and summarized.

Ding H., Liu M., Sarlioglu B.

The purpose of this paper is to propose a novel flux-switching permanent magnet machine (FSPM) with a conical rotor. The conical rotor has two degree-of-freedom movement, including axial and radial movements. The axial movement is realized by controlling the axial force generated by the d-axis current. During the positive axial movements, the air gap length is reduced and leads to higher air gap flux density to increase the torque production capability. During the negative axial movements, the air gap flux density is reduced due to the increase of air gap length, which creates an opportunity for the improved flux-weakening compared with normal FSPM machines. In this paper, the design parameters of the conical FSPM are provided. The axial force and torque production capability are investigated by analytical equations and 3-D finite element analysis (FEA). Flux-weakening is also evaluated at various axial positions and d-axis currents.

Li L., Li D., Qu R.

A novel partitioned stator dual-PM Flux-switching permanent magnet (PM) machine with mechanically continuously flux adjusting capability is proposed and analyzed for applications which demand large speed range and high efficiency. This is a novel concept of mechanically adjusted variable-flux (MVF) for flux-switching permanent magnet (FSPM) machines, and it can achieve the same effect as the flux-weakening control in electric vehicles. Two arrays of PMs are inserted into the outer stator and inner stator respectively, and the only one set of winding is placed in the outer stator. The outer stator is fixed while the inner stator is rotatable, and the PM flux could be regulated continuously by adjusting the relative position of inner stator and outer stator. The flux weakening capability and other electromagnetic performances of the proposed machine are investigated by 2D-FEA analysis.

Mamashli M., Jamil M.

Enhancing the dynamic response of Flux-Switching Permanent Magnet Synchronous Machines (FSPMSMs) is crucial for high-performance applications such as electric vehicles, renewable energy systems, and industrial automation. Conventional Proportional Integral (PI) controllers within model predictive current control (MPCC) frameworks often struggle to meet the demands of rapid transient response and precise speed tracking, particularly under dynamic operating conditions. To address these challenges, this paper presents a hybrid control strategy that integrates Sliding Mode Control (SMC) into the speed loop of MPCC, aiming to significantly improve the dynamic response and control robustness of FSPMSMs. The feasibility and effectiveness of the proposed approach are validated through high-fidelity real-time simulations using OPAL-RT Technologies’ OP5707XG simulator. Two control schemes are compared: MPCC with a PI controller in the speed loop (MPCC-PI) and MPCC with SMC in the speed loop (MPCC-SMC). Testing was conducted under various operating scenarios, including starting tests, load variations, speed ramping, and speed reversals. The results demonstrate that the MPCC-SMC strategy achieves superior dynamic performance, faster settling times, smoother transitions, and enhanced steady-state precision compared to the MPCC-PI scheme. The comparative results confirm that the MPCC-SMC method outperforms conventional MPCC strategies, making it a compelling solution for advanced motor drive applications requiring enhanced dynamic control.

Awad E.H., Tahoun S.M., ElShanawany M.M., Tawfiq K.B.