United States

This work presents an approach to detect the inter-turn short circuit (ITSC) and demagnetization faults of permanent magnet synchronous machines (PMSMs) using maching learning. PMSMs possess advantages such as compact size, lightweight, high efficiency, high power density, and easy control. Therefore, they are a popular choice for traction motors of modern electric vehicles (EVs) and many high-performance industrial applications. With the widespread applications of PMSMs, their development should not be only focused on efficiency enhancement but also on fault detection to secure operation safety and cost. Therefore, preventive detection of motor failures is key to improve reliability and reduce damage or maintenance costs. Based on the research of Industry Applications Society (IAS) [1], the stator fault of electric motors is taking up to 37% of all sorts of faults, where ITSC fault occurs the most commonly. Demagnetization is also one of the major fault types in PMSMs. Taking EVs as an example, the high-power density and stochastic load conditions would risk the traction motors in potential ITSC or demagnetization.&lt;br/&gt;&lt;br/&gt;Among the previous studies regarding fault detection systems for PMSMs, the most frequently applied methods are mathematical modeling combined with the measurement of current or voltage signals. The drawback of these methods is that they are often not able to identify minor variations precisely and classify fault types and levels. Machine learning can be a good tool to improve fault classification capability.&lt;br/&gt;&lt;br/&gt;With the help of machine learning [2], this work is capable of detecting faults of ITSC and demagnetization in a preventive way so that the system can be ensured in healthy operation. Thus, the motors or components can be replaced before any collapses occur. The proposed algorithm has been trained with both simulation and test data (Fig. 1) with data collected from around 10000 tests. The effectiveness has also been tested with experimental data, and the results show a 97% - 99% accuracy (Fig 2).

![](https://assets.underline.io/uploads/markdown_image/1/image/a94c6021f9b8ff7a1b5885c9293721ea.jpg)

![](https://assets.underline.io/uploads/markdown_image/1/image/6fc14da33b5f47434b542280f0b00bce.jpg)

2022 Joint MMM-INTERMAG

Machine learning for fault detection in permanent magnet synchronous 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.

The 2022 Joint Conference will offer both in-person and prerecorded on-demand content.

For tickets to the event, please register at the following link: https://magnetism.org/register

Please register for the Joint MMM-Intermag conference to join the event.

This work presents an approach to detect the inter-turn short circuit (ITSC) and demagnetization faults of permanent magnet synchronous machines (PMSMs) using maching learning. PMSMs possess advantages such as compact size, lightweight, high efficiency, high power density, and easy control. Therefore, they are a popular choice for traction motors of modern electric vehicles (EVs) and many high-performance industrial applications. With the widespread applications of PMSMs, their development should not be only focused on efficiency enhancement but also on fault detection to secure operation safety and cost. Therefore, preventive detection of motor failures is key to improve reliability and reduce damage or maintenance costs. Based on the research of Industry Applications Society (IAS) [1], the stator fault of electric motors is taking up to 37% of all sorts of faults, where ITSC fault occurs the most commonly. Demagnetization is also one of the major fault types in PMSMs. Taking EVs as an example, the high-power density and stochastic load conditions would risk the traction motors in potential ITSC or demagnetization. Among the previous studies regarding fault detection systems for PMSMs, the most frequently applied methods are mathematical modeling combined with the measurement of current or voltage signals. The drawback of these methods is that they are often not able to identify minor variations precisely and classify fault types and levels. Machine learning can be a good tool to improve fault classification capability. With the help of machine learning [2], this work is capable of detecting faults of ITSC and demagnetization in a preventive way so that the system can be ensured in healthy operation. Thus, the motors or components can be replaced before any collapses occur. The proposed algorithm has been trained with both simulation and test data (Fig. 1) with data collected from around 10000 tests. The effectiveness has also been tested with experimental data, and the results show a 97% - 99% accuracy (Fig 2).

![](https://assets.underline.io/uploads/markdown_image/1/image/a94c6021f9b8ff7a1b5885c9293721ea.jpg)

![](https://assets.underline.io/uploads/markdown_image/1/image/6fc14da33b5f47434b542280f0b00bce.jpg)

poster

Introduction Doubly-Salient machines (DSMs) have simple structure which provides high mechanical robustness and control flexibility, thus are suitable for wind power application [1-2]. However, due to the shortage of rare-earth resources, the rare-earth PM material becomes more and more expensive. In order to reduce the machine cost, decreasing the usage of rare-earth PMs without sacrificing steady torque becomes a hot topic. Consequent pole concept, which uses only half of the PMs with the same magnetization direction, is proposed to save the dosage of PMs [3-4]. Furthermore, rare-earth PMs are replaced with ferrite PMs to avoid the usage of rare earth resources. In this paper, slot-PM-assisted consequent-pole-PM doubly-salient machine (SPMA-CPM-DSM) is proposed. The key is that the consequent-pole ferrite PMs are employed in the stator yoke to reduce the cost and small amount of tangential magnetized rare-earth PMs is placed in the slot opening to improve the torque production. This proposed hybrid magnet design can greatly enhance the PM utilization ratio and reduce PM cost without sacrificing the steady torque. Machine configuration Fig. 1 shows the configuration of three machines. For the conventional DSM, the polarity of yoke ferrite PMs alternates around the circle. For CPM-DSM, the yoke ferrite PMs of one polarity remain while the yoke ferrite PMs of another polarity are replaced with iron core. For SPMA-CPM-DSM, based on the structure of CPM-DSM, tangential magnetized slot rare-earth PMs are added to further enhance the steady torque. Electromagnetic performance Fig. 2 shows the electromagnetic performance of three machines. It can be seen that the flux linkage amplitude, back-EMF amplitude, as well as average torque of CPM-DSM is almost the same as that of conventional DSM. Since the PM usage of CPM-DSM is half of that of conventional DSM, consequent pole structure can reduce the ferrite PM usage without sacrificing the electromagnetic performance of the machine. In addition, with the employment of slot rare-earth PMs, the flux linkage amplitude, back-EMF amplitude, as well as average torque of SPMA-CPM-DSM is 79% higher than that of CPM-DSM, denoting the torque enhancing ability of slot PMs.

![](https://assets.underline.io/uploads/markdown_image/1/image/964ca993a62a1567900765fc831a59cd.jpg)

Fig. 1

![](https://assets.underline.io/uploads/markdown_image/1/image/ae7daf792625dd6c76f646e027562fb1.jpg)

Fig. 2

A Novel Slot-PM-assisted Consequent-pole-PM Doubly-salient Machine with Hybrid Magnets of Ferrite PMs and Rare-earth PMs

Abstract—This paper proposes a novel stator-PM consequent-pole dual stator/rotor armature winding flux modulated machine with the dc-biased current. Due to both armature windings and consequent-pole stator-PM interact with each other, this proposed machine contains six torque components. Compared with traditional stator permanent magnet machines and flux modulated machines, this machine makes full use of the space in the rotor cavity and giving full play to the flux modulation effect. Keywords—Hybrid excitation, DC-biased current, dual armature winding vernier machine. I. Introduction Recently, stator permanent magnet machines are gaining more and more research attention for their benefit of a robust rotor structure[1]. In the meantime, the flux modulated machines due to the natural high torque density characteristic are gaining more research interest, too [2]. Combining the advantages of both machines, the DC-biased hybrid excitation stator PM vernier machines (HEPMVMs) are proposed [3]. Compared with the stator PM machines, the DC-biased HEPMVMs improve the shortcomings of the inherent limited magnetic field adjustment ability, meanwhile, improve the torque density. However, these machines don't make full use of the space in the rotor cavity, and the reliability of torque output is poor, due to only contain stator armature winding. In this paper, the topology of DC-biased hybrid excitation consequent-pole stator-PM dual stator/rotor armature winding vernier machine (DAWVM) is proposed. As shown In Fig. 1, the stator has two-phase DC-biased winding and the teeth located PMs alternately, the rotor has three-phase winding. Therefore, high torque will be generated. The drive circuit, operation principle, and electromagnetic characteristics will be illustrated in the full paper. II. Electromagnetic Performance Evaluation The simulation results of flux density, back-EMF, and electromagnetic torque are analyzed by finite element analysis (FEA). The no-load flux distribution is shown in Fig. 2. The back-EMF and electromagnetic torque with various excitation modes are shown in Fig. 3. This machine exhibits larger torque due to containing six torque components, which will be illustrated in the full paper.

![](https://assets.underline.io/uploads/markdown_image/1/image/6a78d3406fe7674c0daab8e134f646e0.jpg)


![](https://assets.underline.io/uploads/markdown_image/1/image/89a7a0023c13e288322e39b060ae88ef.jpg)

A Novel Stator-PM Consequent-pole Dual Stator/Rotor Armature Winding Flux Modulated Machine for Multi-Torque Components

Abstract—This paper proposes a novel dual armature winding vernier reluctance machine (DAWVRM) with stator five-phase DC-biased current. Due to the dual stator/rotor armature winding, this proposed machine can produce four different torque components which make the machine has a larger torque density and high fault-tolerant. Meanwhile, due to the five-phase DC-biased current of the stator winding, the fault-tolerant ability of the machine is further improved. Index Terms—Dual armature winding, Five-phase DC-biased current, Multi-torque components, Vernier reluctance machine. I. Introduction To improve the torque density and realize better rotor space utilization, flux reversal machines (FRM) with armature windings wound on both stator and rotor teeth were proposed in [1], [2]. Compared with conventional FRM, that machine can yield 60% higher torque density. Meanwhile, the three-phase DC-biased current vernier reluctance machine (DC-biased VRM) is proposed and studied due to the higher torque density compared with the conventional VRM [3]. To satisfy both the high torque density and high fault-tolerant, the method of multi-torque components output can be adopted. In this paper, the topology of DAWVRM with stator five-phase DC-biased current is proposed. As shown In Fig. 1, the stator has five-phase DC-biased winding and the rotor has three-phase winding. As a result, four different torque components will be generated. The operation principle and electromagnetic analysis will be illustrated in the full paper. II.Electromagnetic Performance Evaluation The electromagnetic performance of the machine is predicted by FEA. The no-load flux distribution is shown in Fig. 2, and the maximum magnetic density in the yoke is 1.4T. The back-EMF of stator and rotor windings are shown in Fig. 3, and the output torque is shown in Fig. 4. When the stator rotor windings are excited simultaneously, the output torque (torque ripple) is 5.42Nm (0.116). When the stator/rotor is excited separately, the output torque is 1.61Nm/1.55Nm. This machine exhibits a larger torque density and high fault-tolerant due to containing four torque components, which will be illustrated in the full paper.

A Dual Armature Winding Vernier Reluctance Machine with Stator Five-phase DC-biased Current

In field modulation machine (FMM), the high speed armature magnetic field is modulated to couple with a low speed magnetic field generated by rotor with multiple pole-pair number of permanent magnets (PMs) for high output torque [1]. In order to increase torque production furtherly, dual stator FMM (DSFMM) is proposed, which can fully utilize space and PMs [2]. Another approach to enhance torque production is to increase airgap flux density by using interior PM (IPM) or bilateral PM (BPM) arrangements in DSFMMs [3]. However, DSFMM excited by IPM or BPM alone can not achieve high sinusoidal airgap magnetic field. This paper proposes a new staggered DSFMM with O-shape PM arrangement (ODSFMM), which provides high sinusoidal airgap magnetic field for high quality torque production. Two radially magnetized PMs with opposite polarity are sandwiched between two tangentially magnetized PMs with opposite polarity, which forms the proposed O-shape PM arrangement for high sinusoidal airgap magnetic field with high flux density. The inner stator is rotated along shaft to form staggered DS structure for flux leakage reduction. The angle between the central axes of inner and outer stator teeth (α) is 15°. The open stator teeth play the role of modulation poles to modulate the magnetic field excited by O-shape PMs. The stator of the proposed machine employs three-phase 12-slot/2-pole single layer integral-slot distributed windings for high slot utilization and back electromotive force (EMF). To verify the merits of the proposed ODSFMM that is simply referred as Model I, the DSFMM with BPM excitation (simply referred as Model II) and with unrotated inner stator (simply referred as Model III) are designed, which share identical key design parameters, such as the volume of PM, outer radius, airgap length, and active stack length. The back-EMF, cogging torque, steady torque at rated state and steady torque at different current angles of the proposed designs are analyzed using finite element analysis (FEA). The FEA-predicted results show that the proposed ODSFMM can provide high sinusoidal back-EMF waveforms with high amplitude and high torque production with low torque ripple, which is desirable for accuracy operation applications.

![](https://assets.underline.io/uploads/markdown_image/1/image/4a299bd1b2fb9bb0314cc366b9ec1f6a.jpg)

![](https://assets.underline.io/uploads/markdown_image/1/image/661dc67f894efd034b2b9f2e2da0db0d.jpg)

A New Staggered Dual Stator Field Modulation Machine with O-Shape Permanent Magnet Excitation

Field modulation machine (FMM) operates based on magnetic gear effect, which has the merit of high torque production at low operating speed [1]. Thus, FMM is suitable in direct-drive applications such as astronomical telescope and robot arms [2]. Hybrid magnet dual stator FMM (HMDSFMM) is developed for increasing output torque furtherly and obtaining high power factor [3]. Generally, the multiple-tooth stator is employed to increase split ratio for high torque density [4]. Nevertheless, the existing DSFMM with the same split ratio of inner and outer stators can not achieve the best electromagnetic performances. This paper proposes a new HMDSFMM with different split ratios of stators (DSR-HMDSFMM), which can achieve high quality torque production. The split tooth numbers of the outer and inner stators of the proposed DSR-HMDSFMM are designed as 2 and 3, respectively, which is expressed as K1=[2,3]. The inner and outer stators using different split ratios take the advantage of reducing flux leakage and increasing torque quality. The total tooth numbers of inner stator is equal to that of outer stator because the same armature windings and PM excitation are used. The consequent pole rotor with NdFeB magnets establishes the main magnetic circuit for high PM utilization. Ferrite magnets are embedded between split teeth, which aim to enhance the airgap flux density and suppress the harmonic distortion. In order to find out the optimal combination of split ratios of stators, the proposed DSR-HMDSFMMs with K2=[1,2], K3=[1,3] and K4=[2,2] are analyzed, which are simply referred as Model II, III, IV, respectively. Both of the inner and outer stators employ the three-phase 12-slot/2-pole integral-slot distributed double layer windings which can fully utilize slot space and high back electromagnetic force (EMF). The electromagnetic performances of proposed designs are analyzed by finite element analysis, including back-EMF, cogging torque, steady torque at rated condition and steady torque characteristics against current angle. The calculated results show that the proposed DSR-HMDSFMM with K1=[2,3] exhibits the highest back-EMF and high quality torque production, which is suitable for the accuracy operation applications.

![](https://assets.underline.io/uploads/markdown_image/1/image/f5d728ef165e4b4ddea0b681d5bc7748.jpg)

![](https://assets.underline.io/uploads/markdown_image/1/image/fa1be802d3861975e606af95295eb2b1.png)

A New Hybrid Magnet Dual Stator Field Modulation Machine With Different Split Ratios of Stators

Permanent magnet vernier machine (PMVM), as one novel embranchment of low speed large torque permanent magnet synchronous machine (PMSM) based on flux modulation principle, which has broad application prospects in wind power generation, electric vehicles and other fields [1]. The flux modulation pole (FMP) is introduced into the stator tooth of the magnetic gear motor as the magnetic modulation ring in the magnetic gear motor [2], which makes the motor structure more complex, as shown in Fig. 1(a). Although the finite element method (FEM) has the advantages of high calculation accuracy, the modeling of complex geometric structure of the motor is time-consuming, and the solution speed is slow [3]. Fast and accurate calculation of the magnetic field of the PMVM, which is conducive to the rapid initial design and optimization of the PMVM. This paper proposes a sub-domain model for accurate calculation of PMVM magnetic field, which based on Schwarz-Christoffel mapping technique. Schwarz-Christoffel mapping is the transformation of a continuous line segment on the real axis of the w plane to the boundary of a polygon in the z plane and the upper half plane of the w plane to the interior of the polygon [4]. Through twice Schwarz-Christoffel mapping to get regular magnetic field graphics. Firstly, the z plane is transformed into the w plane; then the w plane is transformed to the t plane by the logarithmic transformation. The z-w-t plane correspondence is shown in Fig.2. The detailed derivation process will be presented in the full paper. In order to verify the correctness of the proposed PMVM magnetic field accurate subdomain model, the magnetic field calculation results of the FEM and the analytical model are compared. Fig.3 shows the FEM results of the radial component of air gap flux density under no-load and load conditions. The complete calculation results of the accurate subdomain model will be given in the full paper.

![](https://assets.underline.io/uploads/markdown_image/1/image/9fc8db832b702cd9b69d22fd0a2d775e.jpg)



![](https://assets.underline.io/uploads/markdown_image/1/image/e3632689ba6f63ec6a5508814ad28b6b.jpg)

Accurate Analytical Calculation of Magnetic Field of Permanent Magnet Vernier Motor

I. Introduction Recently, flux modulated permanent magnet machines (FMPMMs) have attracted considerable attention due to the high torque density [1] [2]. However, the constant power speed range of FMPMMs is limited because of the uncontrollable PM flux, which restricts their applications. To solve the problem, this paper proposes a new hybrid-excited partitioned stator flux modulated machine with dual-PM (HE-PSFMDPMM). The proposed machine employs the PMs on both the inner stator and rotor to enhance the torque capability. Meanwhile, the field windings are placed in the inner stator to achieve the flux regulation. II. Machine Topology and Operation Principle Fig. 1 shows the topology of the proposed HE-PSFMDPMM, in which a rotor is sandwiched by the inner and outer stators. The non-overlapping concentrated armature windings and field windings are wound on the teeth of outer and inner stators, respectively, which provide the advantages of short end length and low copper loss. Besides, the PMs and iron poles are alternatively placed on the top of inner stator teeth, which composes a consequent-pole PM configuration. The rotor of HE-PSFMDPMM is simply made up of the alternatively PMs and iron poles, and the PMs on the rotor are arranged as the Halbach array. The magnetization directions of PMs on the inner stator and rotor are marked in Fig. 1. The operation principle of the proposed HE-PSFMDPMM is based on the flux modulation effect [1], and the torque of machine is generated by taking advantage of the modulated air-gap field harmonics. III. Electromagnetic Performance Evaluation As shown in Fig. 2 (b) and (c), compared with using stator-PM only and rotor-PM only, the use of dual-PM can enjoy more abundant air-gap flux density working harmonics, which contributes to a high flux linkage. As shown in Fig. 2 (d), the maximum average torque is obtained when the dual-PM is used. According to Fig. 2 (e), the phase flux linkage can be effectively regulated by changing dc current density (Jdc). Moreover, the average torque increases with the increase of Jdc, as illustrated in Fig. 2(f). More detailed design considerations and electromagnetic performance analysis results will be presented in the full paper.

![](https://assets.underline.io/uploads/markdown_image/1/image/29a9d0b172a613f8a68cac42c853140f.jpg)

Fig. 1

![](https://assets.underline.io/uploads/markdown_image/1/image/b56cdf9e2bba109bb5998cc8759761c2.jpg)

Fig. 2

A New Hybrid-Excited Partitioned Stator Flux Modulated Machine With Dual-PM

Nowadays, permanent magnet synchronous machine (PMSM) has attracted more and more attention in wind power application with its inherent merits such as high-torque density and high efficiency [1-2]. However, with the fixed PM excitation, it is not easy for the PMSM to provide controllable airgap flux and extend speed range to capture more wind energy [3-4]. To extend the constant-power speed range and improve the machine efficiency, a new slot-PM-assisted hybrid magnet memory machine (SPMA-HMMM) is proposed, in which hybrid PMs, namely high coercive force (HCF) PMs and low coercive force (LCF) are artificially combined and inset into both stator yoke and slot opening. Especially, one pole of yoke PMs are made of HCF PMs, and the other pole of yoke PMs are composed of LCF PMs with flexible flux regulation ability. LCF PMs can be freely magnetized or demagnetized through DC current pulses supplied by the DC magnetizing coils wound on the LCF PMs. Therefore, during the high-speed operation, high efficiency of machine can be achieved with negligible field excitation loss. In addition, the HCF slot PMs can further enhance the torque/power density of machine with parallel excitation. Machine configuration Fig. 1 shows the configuration of SPMA-HMMM. It is composed of 28-pole outer rotor and 24-slot inner stator as denoted in Fig. 1. The rotor consists of only iron core, hence providing mechanical robustness. The stator comprises all excitation sources, including 3 pole-pair slot PMs, 3 pole-pair yoke PMs, armature winding and DC magnetizing coils. It is worth noting that the yoke PMs are formed by both HCF PMs and LCF PMs. Electromagnetic performance Fig. 2 shows electromagnetic performance of proposed SPMA-HMMM. As denoted in Fig. 2(a) and Fig. 2(b), the open-circuit flux-linkage and back-EMF can be effectively enhanced or weakened at different magnetization states via different DC magnetizing current pulses applying to LCF yoke PMs. Therefore, flexible flux regulation can be realized. As shown in Fig. 2(c), with the employment of slot PMs, the average torque is enhanced by 30.9% under flux-enhancing magnetization state.

![](https://assets.underline.io/uploads/markdown_image/1/image/056114d44fdf9028abfb9f3df5172d82.jpg)

Fig. 1. Configuration of SPMA-HMMM.

![](https://assets.underline.io/uploads/markdown_image/1/image/ee505f33e75ea49d09085daf20b05238.jpg)

Fig. 2. Electromagnetic performance of SPMA-HMMM.

A Novel Slot-PM-assisted Hybrid Magnet Memory Machine for Wind Power Generation

I.Introduction Recently, a variety of wave energy converters have been proposed with increasing concerns on low carbon electricity, of which direct drive wave energy converter (DD-WEC) requires fewer moving parts since the translator of the generator is coupled with the wave energy converter directly [1]. Permanent magnet linear generator (PMLG) is widely used for DD-WEC and permanent magnet transverse flux linear machine is a member of the variable reluctance PM linear machines family which are known to achieve high thrust density. So permanent magnet transverse flux linear generator (PMTFLG) is a good candidate in DD-WEC which is a typical low-speed high thrust application. Also, the air-gap flux can be adjusted by variable reluctance to extend the working range. Hence, in order to balance between extending the working range and achieving high thrust, more research should be done on PM positioning, number and shape of PMs and magnet material [2]. In this paper, a field-modulated transverse flux linear generator is proposed. By adjusting the machine topology and PM position, the generator can operate in a wide working range without sacrificing too much thrust density. II.Machine Topology and Operation Principle As shown in Fig. 1, the generator consists of outer stator, inner stator and moving translator. Some PMs and direct current field coils are placed in the inner stator, while the armature coils are placed in the outer stator slot and some PMs are inserted between the adjacent outer stator shoes. The moving part of the generator is translator and the moving direction is along z-axis. Silicon steel sheets and nonmagnetic sheets are arranged in the moving translator. The PMs which are inserted between the adjacent outer stator shoes can reduce the harmonics of back electromotive force (EMF). Fig. 1 III.Results Fig. 2 IV.conclusion Simulation results show that the air-gap flux can be adjusted by variable reluctance to extend the working range. The generator can operate in a wide working range without sacrificing too much thrust density.

![](https://assets.underline.io/uploads/markdown_image/1/image/93a8770a3fe2c80a6e7b3bdd2fa7f88e.jpg)

Fig. 1. Configuration of the proposed PMTFLG.

![](https://assets.underline.io/uploads/markdown_image/1/image/25ba2b9a683651ea55dcea34b5f1d0ec.jpg)

Fig. 2. Thrust of variable reluctance and variable reluctance and PM.

Analysis of a Variable Reluctance Field-modulated Transverse Flux Linear Generator

I. Introduction In recent years, dc excited multitooth flux-switching machines (DC-MFSMs) have attracted wide attention due to their excellent flux regulation capability and high reliability [1]. In this paper, a novel DC-MFSM is proposed by changing the winding configuration of the existing machine in literature [2]. Fig. 1 shows the topologies of the proposed and the existing DC-MFSMs, called model I and model II. The field winding of model I and model II employ concentrated winding on the same and adjacent stator, respectively. Corresponding, the magnetic polarities due to field windings of model I and model II close to the air gap can be respectively regarded as “N-S-S-N” and “N-N-S-S”. The two models are the same except for the configuration of field windings. II. Performance comparisons Fig. 2(a) and (b) present no-load back electromotive force (back-EMF) of two DC-MFSMs at the speed of 1500N/min and the corresponding finite-element analysis (FFT) results. It can be seen that the amplitude of fundamental back-EMFs of the model I is nearly 78% higher than that of model II. In terms of the total harmonic distortion (THD) of the back-EMF waveform, the model I is slightly larger than model II. Furthermore, Fig. 2(c) shows the torque waveforms when the armature current density (Ja) and excitation current density (Jf) of the two machines are both 5A/mm2. It can be observed that the average torque of model I and model II are 2.43 Nm and 2.29 Nm, respectively. Meanwhile, the torque ripple of model I is smaller. Due to unequal multitoothed distribution is adopted in model II during optimization, the peak-to-peak amplitude of model I (0.15Nm) is greater than that of model II (0.025 Nm), as shown in Fig. 2(d). Overall, the proposed novel DC-MFSM is superior to the conventional one since it exhibits much higher no-load back EMF and average torque, smaller torque ripple, and lower copper loss. The other performance, such as winding inductance, and efficiency, will be shown in the full paper.

![](https://assets.underline.io/uploads/markdown_image/1/image/36407c7e7ac02df9b479d3ef5d3388ed.jpg)

Fig.1. Topology of two dc excited MFSMs. (a) model I. (b) model II.

![](https://assets.underline.io/uploads/markdown_image/1/image/0c0c9bb24f9da7e35c459e4ee80b49f9.jpg)

Fig.2. Performance comparisons of two models. (a) Back-EMF waveforms at 1500r/min. (b) Harmonics of back-EMF. (c) Average torque. (d) Cogging torque.

Machine learning for fault detection in permanent magnet synchronous machines

Next from 2022 Joint MMM-INTERMAG

A Novel Slot-PM-assisted Consequent-pole-PM Doubly-salient Machine with Hybrid Magnets of Ferrite PMs and Rare-earth PMs

Similar lecture

Milli volt class spin motive force due to domain wall motion in GdFeCo magnetic wire

Stay up to date with the latest Underline news!

PRESENTATIONS

CONFERENCES

COMPANY

RESOURCES