I. Introduction Hybrid-excited (HE) machine and fault-tolerant (FT) machine have attracted wide attention due to their several advantages, such as easy adjustment of air-gap magnetic field, high power density and high efficiency in wide speed range of HE machine, and reliability of FT machine [1]-[2]. Nowadays, multi-tooth field modulated (MTFM) machines have become a research hotspot thanks to their capability of sufficiently utilizing harmonics to promote the average output torque [3]. In this paper, to apply the advantages of HE machine and FT machine to MTFM machine, a novel hybrid-excited fault-tolerant multi-tooth field modulated (HEFT-MTFM) machine is proposed. The topology of proposed machine is shown in Fig. 1. To have lower demagnetization risk, parallel-hybrid-excited structure is adopted in the machine. II. Electromagnetic Performance The electromagnetic performances of HEFT-MTFM machine are presented in Fig. 2. It can be seen that regulating the magnitude of air-gap field by excitation windings can change the magnitudes of flux linkage, back-EMF and electromagnetic torque, and keep flux linkage and back-EMF good sinusoidal and also keep the magnitude of cogging torque and torque ripple small. In terms of the fault-tolerant capability, It can be observed from Fig. 2 (e) that the self-inductance of HEFT-MTFM machine is larger than that of traditional fault-tolerant field modulated machine by same motor size. Overall, the proposed HEFT-MTFM machine exhibit good flux regulation capability, sinusoidal flux linkage and back-EMF, small cogging torque and torque ripple, short-circuit current restrained capability due to high self-inductance and magnetically isolated capability due to low mutual-inductance. The operation principle, machine optimization and more detailed performances including the loss of PMs and operation efficiency will be further discussed in the full paper.

A Novel Fault Tolerant Multi

I. Introduction Flux-switching permanent-magnet (FSPM) machine has been received much attention due to its advantages of high torque density and easy heat management, etc. [1]. In order to enhance the torque/power capability, FSPM machine with multi-tooth structure (MFSPM) has been proposed [2]. However, not only high power density but also high reliability and good fault-tolerance capability are required for PM machine and hence three novel fault-tolerant MFSPM (FT-MFSPM) machines are proposed in this paper based on the MFSPM machine in [2]. The topologies of proposed machines are shown in Fig. 1. To increase the torque density, a new outer rotor FT-MFSPM (Model I) shown in Fig. 1 (a) is proposed based on [2]. To further increase the output torque, a middle PM is added in each dummy slot (Model II) as shown in Fig. 1 (b). Employing more PMs is an effective method to improve the toque without consuming the operating energy and thus the dual PM modulated FT-MFSPM machine (Model III) is proposed and shown in Fig. 1 (c). II. Performance comparisons The electromagnetic performances of three FT-MFSPM machines are presented in Fig. 2. It can be seen that though Model III exhibits the highest value of flux linkage, back-EMF and electromagnetic torque, it also exhibits the highest value of cogging torque and torque ripple and the most distorted back-EMF. In terms of the fault-tolerant capability, it can be observed from Fig. 2 (e) that the self-inductance of Model I and Model II is almost the same, which is higher than that of Model III. Overall, Model II is superior to Model I and Model III since Model II has greater output torque and smaller torque ripple than Model I with a few increase of PMs and has greater short-circuit current restrained capability due to higher self-inductance and smaller torque ripple with less PMs. The machine optimization and more detailed comparisons including the losses and efficiency will be further discussed in the full paper.

Comparative Analysis of Three Novel Fault Tolerant Multi

I. Introduction Hybrid excited machines have attracted wide attention due to several advantages, such as easy adjustment of air gap magnetic field, high power density and high efficiency in wide speed range [1]. Nowadays, hybrid excited multitooth flux-switching permanent magnet (HE-MFSPM) machines have become a research hotspot [2]. Based on the literature [3], three novel HE-MFSPM machines are proposed in this paper. Fig. 1 shows the topologies of the proposed three HE-MFSPM machines, called Model I, Model II and Model III respectively. The three models are basically the same except that PM with radial magnetization is added in each dummy slot in Model II, while a fault tolerant tooth is employed and wound with field winding in Model III. Significantly, the amount of PM of the Model I is the least, and the amount of PM of Model II is equal to that of Model III. II. Performance comparisons Fig. 2 (a) presents the overload capability of three proposed HE-MFSPM machines supplied with the same excitation current density (Jf), i.e., 5A/mm2. It can be seen that when the current density of armature winding (Ja) increases from 2A/mm2 to 10A/mm2, the torque of Model III increases the most, showing the best saturation characteristics. Fig. 2 (b) shows the speed range of the three proposed HE-MFSPM machines. It should be noted that all the three structures run at the same speed and the same rated voltage, i.e., 700r/min and 380V. It can be observed that Model III has the highest average torque in the constant torque region and has the widest speed range in the constant power region. Overall, all the proposed three HE-MFSPM machines exhibit good ability of flux regulation. But Model III is superior to Model I and Model II since it exhibits best overload capability, highest average torque and widest speed range. Moreover, fault-tolerant ability and modularity exist in Model III because of the existence of fault-tolerant teeth. The other performance, such as back-EMF, cogging torque and electromagnetic torque, will be further discussed in the full paper.

![](https://assets.underline.io/uploads/markdown_image/1/image/2dadc16756df96c8c823592f1ae3ce2c.jpg)

Fig.1. Topologies of three HE-MFSPM machines. (a) Model I. (b) Model II. (c) Model III.


![](https://assets.underline.io/uploads/markdown_image/1/image/4adae74452ff0be4d22d493315020533.jpg)

Fig.2. Performance comparisons of three models. (a)Overload capability. (b) Speed range

Comparative Study on Three Novel Hybrid Excited Multitooth Flux-switching Permanent Magnet Machines

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**Session Chair:** Mattia Butta, *Czech Technical University in Prague*

OPB: Motors, Actuators and Related

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MMM 2022

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**Session chair:** Weimin Guan, Wuhan University


JPM - Design Optimization of Electrical Machines

The 15th Joint MMM-INTERMAG Conference (2022 Joint) is sponsored jointly by AIP Publishing and the IEEE Magnetics Society. Members of the international scientific and engineering communities interested in recent developments in fundamental and applied magnetism are invited to attend and contribute to the technical sessions. The technical program will include invited and contributed papers in oral and poster sessions, invited symposia, a plenary session, and an evening session, with about 1500 presentations overall. This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

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Zichen Jin

3

SHORT BIO

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A Novel Fault Tolerant Multi

Comparative Analysis of Three Novel Fault Tolerant Multi

Comparative Study on Three Novel Hybrid Excited Multitooth Flux-switching Permanent Magnet Machines

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