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The consequent pole permanent magnet (CPM) machine is well known for its high magnet utilization ratio and poor vibration performance. This article focuses on electromagnetic vibration and its reduction design in CPM machines, and the conventional surface-mounted permanent magnet (SPM) machine is used as a benchmark. First, the asymmetrical magnetic field and unbalanced radial force of the CPM machine are investigated with emphasis. The slot-pole combination and force modulation effect are the two reasons for the unbalanced radial force generation. Afterward, two new designs to reduce the vibration caused by the unbalanced radial force are proposed, and the reduction principles are described in detail. Finally, the prototypes of the 12-slot/10-pole SPM and proposed CPM machines are manufactured. The tests are conducted to validate the theoretical analysis and proposed vibration reduction design. [ABSTRACT FROM AUTHOR]

Motor current signature analysis (MCSA) has been widely used for fault diagnosis of induction motors (IMs) because of its non-invasiveness and comparatively low cost. However, the spectral leakage of the fundamental supply frequency can obscure the fault characteristic component when IMs operating at no-load or low-load conditions. In this paper, a broken rotor bar (BRB) fault diagnosis approach based on the third-order energy operator (TOEO) demodulated current signals is presented. The TOEO approach performs effectively in reducing the negative impact of the fundamental supply frequency spectral leakage and enhancing the BRB fault features. Theoretical and experimental results show that the TOEO approach can excellently reveal the fault characteristic frequency, instead of the sideband frequencies. Besides, the results are compared with the Teager-Kaiser energy operator (TKEO). The capability of the presented approach has several advantages over the TKEO, especially when the IMs are fed by an inverter. [ABSTRACT FROM AUTHOR]

This article aims to analyze and design a fault-tolerant permanent magnet Vernier (FTPMV) machine with improved power factor. Different from the existing FTPMV machine with uniform distributed split-teeth stator, hybrid stator and multiple working harmonics designs are adopted in this proposed machine. With these designs, the proposed machine can obtain not only improved power factor but also higher torque and good fault-tolerant performance. First, the topologies, fault-tolerant design and working principle of the proposed machine are introduced. Then, accurate permeance and equivalent magnetic circuit analytical models are established for investigating the mechanism of power factor improvement. And the influences of some key design parameters on power factor and torque of the proposed machine are analyzed by finite element analysis. Finally, a FTPMV prototype is manufactured and tested to validate the designs and analyses. [ABSTRACT FROM AUTHOR]

To suppress the disturbance caused by the parameter mismatch, this article proposes an adjustable model predictive control (AMPC) strategy for an interior permanent-magnet synchronous motor (IPMSM) drives. The key of the proposed method is that an improved model reference adaptive system (IMRAS) is applied to identify online parameters. The traditional proportional-integral (PI) controller in the adaptive law of IMRAS is replaced by a fuzzy logic controller, it can improve the identification accuracy and enhance the robustness of sudden variations in speed reference and load torque. Then, the identified parameters can be used in the AMPC to replace constant parameters. Compared with the traditional model predictive control, the AMPC strategy can effectively decrease motor system current distortion and torque ripple when parameter mismatch occurs. Moreover, the maximum torque per ampere control (MTPA) control strategy based on the formula solution is adopted. And the optimal MTPA operation points can be found automatically by online parameter identification to achieve the minimum amplitudes of the phase current. Finally, the validity and correctness of the proposed method are verified by experiments. [ABSTRACT FROM AUTHOR]

This article focuses on the electromagnetic vibration source and its reduction design in fractional-slot concentrated-windings (FSCWs) permanent magnet (PM) machines. First, the electromagnetic force and vibration characteristics of a 12-slot/10-pole FSCW PM machine are investigated. Then, four electromagnetic vibration sources are investigated and compared, in which the machine operating state is considered. The result shows that the electromagnetic force modulation and stator magnetomotive force (MMF) harmonics are the two sources that contribute most to the vibration underrated and heavy load condition, respectively. Afterward, two new designs to reduce the vibration caused by the electromagnetic force modulation and stator MMF harmonics are proposed, and the reduction principles are described in detail. Finally, the prototypes of the existing and proposed 12-slot/10-pole FSCW PM machines are manufactured. The tests are conducted to validate the theoretical analysis and proposed vibration reduction design. [ABSTRACT FROM AUTHOR]

This article proposes a new hybrid analytical model combining subdomain model and equivalent magnetic network for permanent magnet vernier machines, which are easy to get saturated due to the air-gap field modulation effect. The key is representing saturation effect by iterating equivalent surface current as part of interface conditions in the proposed subdomain model. First, five subdomains are divided to calculate magnetic field distribution. The equivalent surface current is utilized as the boundary constraint between subdomains and iron core. Second, the equivalent magnetic network is established based on stator structure, and the fluxes flowing into flux modulation poles are equivalent as the magnetic flux sources. Node magnetic potentials can be achieved with the application of Kirchhoff's law of current. Then, the equivalent surface current is updated for convergence by node magnetic potential to accurately predict saturated performance. Finally, a prototype is manufactured, and the effectiveness of the proposed hybrid model is verified by the finite-element analysis (FEA) and experimental results. The hybrid model combines the subdomain model and the equivalent magnetic network model to complement each other and it is demonstrated to be more efficient than the FEA model while maintaining high accuracy. [ABSTRACT FROM AUTHOR]

The parameter mismatch in model predictive control (MPC), especially in fault-tolerant control, will lead to degradation of output performance. This article presents a new robust predictive current control based on online d-q inductance identification for a five-phase permanent-magnet (PM) motor under open-circuit fault. First, the MPC of the five-phase motor under the fault-tolerant operation of A-phase open-circuit is built, and then, the parameter mismatch caused by the d-q-axis inductance and the stator resistance is analyzed and discussed. Afterward, the real-time d-q-axis inductance identified by a fault-tolerance model reference adaptive system is used to replace the original parameters in MPC. Moreover, the flux linkage parameter mismatch can be rejected by the incremental predictive model in the proposed method. Therefore, the proposed method can eliminate almost all parameter mismatches, thereby improving output performance and enhancing parameter robustness under open-circuit fault. Finally, the validity and effectiveness of the proposed method are verified by experiments. [ABSTRACT FROM AUTHOR]

This article investigates a multiharmonics linear primary permanent magnet vernier machine. With the adoption of nonuniformly distributed PM arrays along the air gap, richer harmonics are achieved and make its performance superior to the conventional linear primary permanent magnet vernier machine. First, the structures are described and compared. Then, their operation principles are analyzed by the flux modulation theory. The electromagnetic performances of two machines are analyzed and compared through the finite element method and theoretical analysis. The results show that the multiharmonics linear primary permanent magnet vernier machine offers 15% higher thrust force density compared with the conventional linear primary permanent magnet vernier machine. Finally, the experiments on a prototype of the multiharmonics linear primary permanent magnet vernier machine are carried out for validation. [ABSTRACT FROM AUTHOR]

This article tackles the design problem for a permanent magnet Vernier machine with hybrid stator to achieve a high structure robustness, enhanced torque and improved power factor simultaneously. The key of the solution is divided into two parts. One is to solve the conflict between torque and power factor by deterministic optimization. The other is to optimize its robustness with the help of robust optimization. Firstly, sensitivity analysis is adopted to stratify design parameters. Afterwards, a multi-objective deterministic optimization is applied to achieve an optimal balancing design between the two competing objectives, torque and power factor. However, the deterministic optimization ignores the size deviation in actual production, which most likely results in the poor structure robustness. Therefore, robustness analysis is employed to check its robustness. Then, through the robustness optimization, the robustness of this machine is further improved on the basis of the deterministic optimization. Finally, a prototype machine is built and the experiments on the prototype machine are carried out to verify the validity of the robust optimization. [ABSTRACT FROM AUTHOR]

Ferrite permanent magnet (FPM) has been employed in the spoke-type motors because of the low cost, stable supplement, and acceptable magnetic energy production. Especially, when the fractional slot concentrated winding (FSCW) is adopted, the torque ripple will be reduced. However, the torque ripple caused by the slot harmonics is difficult to be reduced in the FSCW FPM motors. Because the winding factors of the slot harmonics and the main harmonic are the same, the reduction of the slot harmonics from the stator or winding will lead to a significant torque loss. In this article, a new spoke-type rotor with assisted poles is proposed for the FSCW FPM motors. Due to these assisted poles, asymmetrical assisted poles can be realized along the circumferential direction to reduce the corresponding rotor magnetomotive forces (MMFs), which produce the torque ripple by interacting with the slot harmonics. The interaction of the harmonics that contribute to the torque ripple between the stator-MMF and rotor-MMF is first developed. Additionally, the relationship between the unequal angles and the orders of the torque ripple is obtained. Moreover, the principle to reduce the torque ripple in the FSCW spoke-type FPM motors is revealed. Finally, two prototypes are manufactured to evaluate the effectiveness of the theoretical analysis. [ABSTRACT FROM AUTHOR]

Owing to bidirectional field modulation effect, dual-permanent-magnet-excited (DPME) machine could offer improved torque capability, which has attracted increasing attention in recent years. However, conventional DPME machine only utilizes a small amount of abundant field harmonics to yield torque, which leads to limited torque enhancement. To solve this issue, a novel DPME machine with enriched working harmonics is proposed in this paper. The key of the proposed DPME machine is to design some non-uniformly distributed permanent-magnets and flux modulation poles on the stator. Thus, increased field harmonics are produced to produce effective torque, offering the potential to enhance torque. Firstly, the topology and feature of the machine are introduced. Moreover, operating principle is analyzed by using air gap field modulation theory. Then, the operating principle and torque enhancement are verified and evaluated by using finite-element method. At last, a corresponding principle machine is fabricated, and some experiments are performed for validation. [ABSTRACT FROM AUTHOR]

This article proposes a new equivalent magnetic network (EMN) model for predicting the performances of interior permanent magnet (IPM) machines. The proposed EMN model incorporates the features of high accuracy and low time consumption in the reluctance network model and the magnetic equivalent circuit model, respectively, to achieve a tradeoff between the time consumption and calculation accuracy. A new air-gap model is also presented to make the dynamic analysis of the machine more efficient and easier. Moreover, the modeling approach of the rotor provides a standard for the modeling of IPM machines with permanent magnets (PMs) at different locations and of different shapes. In addition, the proposed EMN model takes into consideration the influence of flux leakage and iron saturation. Finally, the example machine is chosen, and the effectiveness of the EMN model is verified by comparison with the finite-element analysis and experimental tests. [ABSTRACT FROM AUTHOR]

This paper proposes a new torque analytical method (AM) for five-phase interior permanent magnet synchronous machine (IPMSM) with shifted asymmetrical rotor pole. The key of this method is to consider the permanent magnet (PM) torque and the reluctance torque simultaneously, by using the Lorenz force law. The analytical expressions, including stator magnetomotive force (MMF), rotor MMF generated by PMs and rotor MMF generated by stator MMF, are first derived. Then, Lorentz force law is used to calculate PM torque and reluctance torque, respectively. In order to improve the precision of electromagnetic torque calculation, stator slotting effect under shifted asymmetrical rotor pole is taken into consideration. Finally, the AM is verified by finite element method and experiment. The results show that proposed AM is good enough to predict the torque performance of IPMSM with shifted asymmetrical rotor pole. [ABSTRACT FROM AUTHOR]

Permanent-magnet vernier machine has an excellent potential for electric vehicles due to its desirable features of a simple mechanical structure and high torque density, whereas the poor power factor is its main drawback. In this paper, a spoke-type permanent-magnet vernier machine is designed and optimized for torque density and power factor improvement. First, the machine structure, operation principle, and sizing equation are introduced. Then, the machine is optimized by a multi-objective genetic algorithm. To enhance the optimization efficiency and accuracy, multi-level, sensitivity analysis, and approximate model technologies are employed in the optimization. It is shown that the improved torque density and power factor are achieved in the optimized machine as compared to the initial one. Finally, a prototype machine is built, and the experiments on the prototype machine are carried out to verify the design optimization. [ABSTRACT FROM AUTHOR]

Torque ripple is one of the important issues for ferrite assisted synchronous reluctance motors (FASRMs). In this paper, an asymmetrical stator is proposed for the FASRM to reduce its torque ripple. In the proposed FASRM, an asymmetrical stator is designed by appropriately choosing the angle of the slot-opening shift. Meanwhile, its analytical torque expressions are derived. The results show that the proposed FASRM has an effective reduction in the cogging torque, reluctance torque ripple and total torque ripple. Moreover, it is easy to implement while the average torque is not sacrificed. [ABSTRACT FROM AUTHOR]

A nonlinear equivalent magnetic network (EMN) model is proposed for a linear permanent magnet vernier (LPMV) machine. The meshing method is employed to solve the problem of the modeling of complex flux paths in stator teeth tips. Especially, an end-region model based on the electromagnetic principle is developed to consider the longitudinal end effect of the LPMV machine. The key contribution of this paper is to present a faster and simpler approach to separate the detent force (end force component and cogging force component) than finite-element analysis (FEA). Besides, taking the iron saturation and air-gap flux leakage into account, the proposed model is used to predict the electromagnetic performances of the LPMV machine, such as air-gap flux density, back-electromotive force, cogging force, and thrust force. Finally, through comparisons among the FEA simulations, experimental measurements and EMN analyses, the accuracy and effectiveness of the proposed model are verified. [ABSTRACT FROM PUBLISHER]

This paper presents an online maximum torque per ampere (MTPA) control strategy for interior permanent magnet synchronous motor (IPMSM) drives based on a space vector signal injection (SVSI) method. The key of the proposed method is that the high-frequency signal is injected into the space vector directly. Then, the MTPA operational point is analyzed by the variation in the stator flux linkage amplitude and stator current magnitude. Since the high-frequency signal is injected into the voltage space vector, there is no need to consider the bandwidth of the speed loop and current loop for the frequency selection of the injection signal. In addition, the SVSI method is easy to realize because the injected signal does not need to be modulated. This method can track the MTPA points accurately and it is parameters-independent. The effectiveness of the proposed method is verified by simulation and experimental results under various operation conditions. [ABSTRACT FROM AUTHOR]

In this paper, a new hybrid stator developed from conventional open-slot and split-tooth stators is proposed for a fault-tolerant permanent-magnet (PM) vernier (FTPMV) machine to improve its performance. The design considerations of the new hybrid stator for FTPMV machines are presented. Afterward, on the basis of the designed hybrid stator, new FTPMV machines with surface-mounted and spoke-array PMs are proposed and analyzed, respectively. Comparative evaluation of the proposed FTPMV, conventional FTPMV, and the conventional PM machines are performed by using finite-element (FE) analysis. It is found that the proposed FTPMV machines with the new hybrid stator definitely offer the improved performances such as higher torque density, higher power factor, and lower iron core loss as compared to that of the conventional FTPMV machines. Finally, the experiments on the prototype machines are conducted, verifying the FE analysis results and effectiveness of the proposed hybrid stator design for FTPMV machines. [ABSTRACT FROM PUBLISHER]

In this paper, a new linear wound-field flux reversal (LWFFR) machine for low-cost linear direct-drive applications is proposed. Similar to the conventional LWFFR machine, the proposed machine possesses the merit of a simple and compact long stator structure, a low cost, and a high flux adjustment ability. The novelty of the proposed machine is to be designed based on the magnetic gear effect. Hence, its force capability can be significantly improved without increasing the structural complexity and manufacturing cost. Meanwhile, the feasible combinations of mover pole and stator pole numbers for the LWFFR machines are extended, and thus provide a more flexible design choice. The operation principle and electromagnetic characteristic of a new optimal LWFFR machine are analyzed by means of the time-stepping finite-element method, verifying the effectiveness of the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a high force density tubular permanent-magnet (PM) motor, termed as tubular stator-PM venier motor, for artificial hearts. The novelty of the proposed motor is to artfully integrate two different magnetization directions of PMs and ferromagnetic poles together. The proposed motor incorporates the merits of vernier PM motors and stator-PM motors, offering high back electromotive force, improved force density, minimized cogging force, and reduced PM volume. The influence of the magnet pole ratio on the performance is investigated. The proposed motor is designed and compared with an existing vernier PM motor by using the time-stepping finite-element method, verifying the validation and the advantageous performance of the proposed motor. [ABSTRACT FROM PUBLISHER]

A new linear permanent-magnet (PM) motor, termed as modular linear flux-reversal PM (M-LFRPM) motor, is proposed. This is particularly attractive for high reliability urban rail transit. Its PM materials and armature windings are set in the mover (train), while the long stator (rail) is composed of irons, hence improving efficiency and reducing cost. The key of the proposed motor incorporates the concept of fault-tolerant teeth to provide the desired decoupling among phases. The structure and features of the proposed motor are presented, and an optimal design is performed. By using finite element method, the advantages and validity of the proposed motor are verified. The analysis results show that the proposed M-LFRPM motor not only retains the advantages of the conventional LFRPM motor, but also improves its fault-tolerant capability. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel linear permanent-magnet (PM) motor, termed as double-stator tubular PM (DSTPM) motor, for artificial hearts. The key of the proposed DSTPM motor is to design the appropriate size of the inner and the outer stators so that the inner and the outer cogging forces can be counteracted by each other, thus minimizing the motor cogging force. To achieve this purpose, two stators are designed to have a special angle difference of 90 electrical degrees. Since one stator is located inside the mover, the inner space is fully used. Hence, the thrust density is enhanced and the axial direction length is reduced. Also, the PMs and the redundant windings are set in the stators, and the moving parts have only solid-iron salient poles. The electromagnetic characteristics of the proposed motor are analyzed by using the time-stepping finite-element method, confirming the validity of the proposed motor. [ABSTRACT FROM AUTHOR]

This paper proposes and designs a new five-phase modular flux-switching permanent-magnet (M-FSPM) machine for high reliability applications. The key is the new machine topology which incorporates the concept of fault-tolerant teeth (FTT) to provide the desired decoupling among phases. The electromagnetic performances of the newly designed M-FSPM machines having 18 and 19 rotor poles are quantitatively analyzed including the flux, back-EMF, cogging torque as well as unbalanced magnetic force (UMF). The results show that the proposed M-FSPM machine not only retains the merits of stator-PM machines and multiphase machines, but also offers lower cost and higher fault-tolerant capability. Especially, the 10/19-pole one incorporates the merits of symmetric back-EMF and reduced cogging torque, while suffers from UMF. Two experimental M-FSPM machines are designed and built for exemplification. Experimental results of the prototypes are given to confirm the validity of the proposed machines. [ABSTRACT FROM AUTHOR]

This paper proposes a new fault-tolerant permanent-magnet (PM) brushless machine for four-wheel independently driven electric vehicles (EVs). The key of the proposed machine is to make tooth widths unequal of inner stator, hence, offering more trapezoidal back-EMF waveform. Due to the fact that the radial PMs are embedded in the outer rotor, the proposed machine incorporates the merits of high torque-to-weight ratio, mechanical robustness, and high air-gap flux density. In addition, multiphase and single-layer fractional slot concentrated windings are employed to improve the reliability. The electromagnetic characteristics of the proposed machine are analyzed by using the time-stepping finite-element method (FEM) and field-circuit cosimulation method, such as magnetic field distribution, flux destiny, flux linkage, and torque, verifying the effectiveness of the theoretical analysis. [ABSTRACT FROM AUTHOR]