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In this article, a targeted step skewing of rotor segments scheme is proposed to reveal the modulated vibration reduction mechanism in integral-slot interior permanent magnet synchronous machines (IPMSMs). First, the vibration characteristics of a 72-slot/12-pole integral-slot IPMSM are investigated. The dominant vibration at specific frequency band is introduced. Then, in order to analyze the main source of vibration, the magnetic field modulation effect and radial force modulation effect are investigated in detail. The results show that the high-order radial force can excite large vibration by radial force modulation effect. This kind of vibration is defined as modulated vibration. Afterwards, the optimal shift angle and number of rotor segments are determined by comparison. Finally, the conventional and proposed 72-slot/12-pole integral-slot IPMSMs are manufactured to validate the theoretical analysis. The experimental results verify that the proposed method can effectively reduce the modulated vibration of the 72-slot/12-pole integral-slot IPMSM. [ABSTRACT FROM AUTHOR]

This article proposes a modified flux observer for sensorless direct torque control (DTC) of the dual three-phase permanent-magnet synchronous motor. The proposed method can improve torque performance without a position sensor. The flux observer is proposed to obtain the stator fluxes and rotor fluxes. The stator fluxes can be utilized to calculate the amplitude of torque and flux for DTC system. Meanwhile, the position information can be detected from the rotor fluxes by using a normalized phase-locked loop. This new flux observer can overcome the disadvantages due to the dc bias, initial value, and harmonic components. The stability of the proposed observer is also analyzed in this article. In addition, a fault-tolerant DTC scheme for open-circuit fault is introduced. The performances of torque control and position estimation are evaluated under healthy, open-circuit fault, and fault-tolerant conditions. Simulation and experimental evaluation are carried out to confirm the effectiveness of the proposed sensorless DTC scheme. [ABSTRACT FROM AUTHOR]

A new partitioned stator hybrid excitation (HE) with an internal magnetic ring machine was proposed in this article. The key of the design is to adopt an inner magnetic ring to reduce the inside stator magnetic reluctance. As a result, the working magnetic field harmonics can be improved, which in turn improve the torque and flux regulation abilities. Besides, by following the design of partition stator, the space competition of permanent magnet, armature winding, and field winding can be effectively alleviated as compared with a single stator HE machine. The structure and operation principle of the conventional and proposed machines are described. Moreover, electromagnetic performances of both machines are compared by using finite element method. Theoretical and simulation analysis results show that the proposed machine can exhibit higher torque and enhanced flux regulation ability than the conventional one. [ABSTRACT FROM AUTHOR]

In this article, a novel parallel hybrid excitation field modulated machine with efficient utilization of multiworking harmonics is proposed. The key of the proposed machine is to efficiently integrate the parallel hybrid excitation and multiworking harmonics to enhance average output torque and flux regulation capability. First, operation principle and air-gap magnetic field harmonics of the machine are investigated by using field modulated principle, which reveals the contribution of each working harmonic to flux linkage and torque. Then, performances of the machine are analyzed, such as open-circuit back-EMF, flux regulation capability, torque-speed characteristics, etc. Also, the proposed machine is compared to conventional ones for evaluation. Finally, a prototype is manufactured and tested to validate the theoretical and simulated results. [ABSTRACT FROM AUTHOR]

In this article, the efficiency function of the permanent-magnet (PM) machines is reconstructed by the quantitative loss expressions. Then, the efficiency function is used to quantitatively analyze the maximum efficiency point and the specific high-efficiency region. General principles of improving the maximum efficiency and the regulation of the specific high-efficiency region for PM machines are investigated. First, the loss expressions of PM machines, which vary with the speed and the current, are presented. Moreover, an accurate efficiency function is established to calculate the efficiency map of PM machines quickly. Furthermore, the maximum efficiency point and the specific high-efficiency region of PM machines are derived, as well as their variation principles with loss distributions are studied. Furthermore, a 12-slots 10-poles PM machine and a 48-slots 22-poles PM machine are designed to verify the analytical results. Subsequently, their electromagnetic performances and the efficiency maps are calculated and compared by the finite-element method. Finally, both PM machines are prototyped and experimental results are given for validations. [ABSTRACT FROM AUTHOR]

This article investigates the effects of phase shift on the inductance and short-circuit current (SCC) in permanent-magnet (PM) machines with dual three-phase winding configurations. First, the relationship between the phase shifts and slot/pole combinations, for the dual three-phase winding configurations, is discussed. Second, analytical expressions of the inductance are derived for the 48-slot/22-pole PM machines with different phase shifts based on the winding function theory. Afterwards, the SCC amplitude of different phase shifts is comparatively analyzed. The investigation reveals that the 7.5° and 30° configurations have great significance to improve the self-inductance value. Thereby, the 30° configuration has comparable SCC amplitude compared to the 7.5° counterpart, while being lower than the 15° configuration one. Moreover, the 30° configuration exhibits lower eddy-current loss and preferable torque performance than its counterparts. Furthermore, the finite-element method is used to calculate electromagnetic performances for evaluation. Finally, some experiments on the prototype machine are carried out for validation. [ABSTRACT FROM AUTHOR]

In this article, a new equivalent thermal network (ETN) model for surface-mounted permanent magnet machines is proposed by applying a mesh-based method with bidirectional coupled winding solution. The key is to couple the winding temperature distributions with thermal network meshes in stator dynamically. First, the meshing method is proposed and combined in the lumped parameter thermal model to obtain temperature distributions instead of the average temperature. The mesh elements have identical shapes and unified thermal conductivity, which can greatly enhance the modeling flexibility and efficiency. Second, the slot winding is established by a 2-D analytical solution method under segmented boundaries with a temperature gradient. Then, the winding solution is coupled with mesh nodes and integrated in the ETN model to accurately predict the temperature distributions in slot including the maximum temperature and position offset. Finally, the effectiveness of the proposed ETN model is verified by comparison with the finite-element analysis and experimental results. [ABSTRACT FROM AUTHOR]

In order to reduce thrust force and stator flux ripples, this article proposes a simplified three-vector-based model predictive thrust force control method for a double-side linear vernier permanent magnet motor. First, a simplified control set is designed to select two active voltage vectors (VVs) in the prediction stage, instead of evaluating redundant VVs. Null VVs are applied to adjust the amplitude of the modified VV, which can realize a full-range modulation by the predefined cost function. To simplify the tuning work of the weighting factor, the variables in the cost function only consider the stator flux term. Then, the duration time of the selected VVs is distributed reasonably through a novel cascaded optimization process. Also, the deadbeat principle is adopted to calculate the duty cycle. With the proposed method, the thrust force and stator flux ripples can be considerably minimized. The simulated and experimental results are conducted to verify the proposed control method. [ABSTRACT FROM AUTHOR]

This paper proposes a design technique for electric ship traction machines to achieve high torque density and low torque ripple by adopting dual m-phase windings with an appropriate phase shift. Firstly, the general relationship between the slot number and the phase number for dual m-phase windings is investigated. Secondly, the uniform analytical expressions of torque with different phase shifts are derived. Also, the optimal phase shift angle is summarized from the perspective of improving torque performance. Then, the 48-slot and 22-pole permanent-magnet machines for electric ship with different windings configurations are designed. The finite-element method is used to calculate their electromagnetic performances, such as back electromotive force, torque capability, stator magnetic motive force and radial force. Finally, some experiments on the prototype machine for electric ship are carried out for validation. [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 paper designs a double-side linear vernier permanent-magnet motor, which incorporates the merits of high thrust force capability, high power factor, and high efficiency. Since the parameters of the motor are very sensitive and the high thrust force capability comes along with the high force ripple, a framework of multiobjective optimization is proposed to improve the overall motor performances. The sensitivity analysis is used to select significant variables and the multiobjective differential evolution with ranking-based mutation operator is conducted with the response surface models to generate the Pareto solution set. The electromagnetic performances of the optimal motor are compared with the initial motor by simulating step by step based on finite-element analysis. Finally, a prototype motor is manufactured and the experimental results validate the improved motor performances. [ABSTRACT FROM AUTHOR]

The linear vernier permanent magnet (LVPM) motor incorporates the merits of high efficiency, simple mechanism, and low cost, which have a bright future in urban rail transportation. This paper proposes a new sensorless direct thrust force control (DTFC) for the LVPM motor. The novelty is the introduction of a modified flux linkage observer, which has strong robustness against the interferences, no phase lag, and no attenuation. Compared with conventional flux linkage calculation methods, the proposed observer can provide desirable flux linkages, which increases the robustness of the sensorless DTFC system. Simulation and experimental results based on an LVPM motor drive demonstrate the accuracy and robustness. The validations in the aspect of the robustness to parameter errors, measurement errors, and noise show the superiorities of the modified flux linkage observer. [ABSTRACT FROM AUTHOR]

Cost-effective and high-performance linear motors attract more and more attention for many applications. This paper proposes a novel double-side linear flux-modulation permanent-magnet (DS-LFMPM) motor with low cost, high thrust force density, and high power factor. The novelty of the proposed DS-LFMPM motor is to improve power factor by using double-side topology. Its topology is presented, and its operation principle is investigated. From the harmonic spectrums of the flux density in the air gap before and after the modulation of the mover teeth and the stator teeth, it can be concluded that the proposed motor has good flux-modulation effect. Also, the expression of the orders of the harmonic spectrums is given. The design process of sizes and structure is particularly explained. The electromagnetic performances are predicted by using the finite-element method and the proposed motor is prototyped for verification. The results show that the proposed DS-LFMPM motor can produce high thrust force density and high power factor. [ABSTRACT FROM AUTHOR]

Fractional-slot concentrated-winding (FSCW) permanent magnet (PM) machines have been widely studied in recent years. This is mainly due to the several advantages, including high power density, high efficiency, short end turns, high fill factor, low cogging torque, good flux-weakening and fault-tolerant performance. However, the key challenges of utilizing FSCW-PM machines are the abundant stator magnetomotive force (MMF) harmonics. In this paper, the multiphase star–delta hybrid connection (SDHC) windings configuration that can eliminate some stator MMF harmonics is systematically studied. First, the general relationship between the number of slots and phases which are appropriate for the SDHC windings configuration is derived. In addition, the particular principle of the MMF harmonics elimination by the SDHC windings configuration is researched. In order to verify the analysis results, four three-phase SDHC FSCW-PM machines with different slot–pole combinations are built and calculated by the finite-element method. Finally, experiments on a prototype three-phase 12-slot ten-pole FSCW-PM machine are carried out for validation. [ABSTRACT FROM AUTHOR]

Linear magnetic-field modulated (LMFM) motor exhibits high thrust force by effectively employing the magnetic-field modulation effect. In this paper, a new mover separated LMFM (MS-LMFM) motor is proposed, which successfully alleviates the space confliction between permanent magnets (PMs) and windings in the existing LMFM motor. The structure and the operation principle of the existing and proposed motor are described, and the major design parameters are optimized for maximum thrust force. Moreover, electromagnetic performances of both motors are compared by finite-element method. Theoretical and simulation analysis shows that the proposed motor can exhibit enhanced force performance than the existing one under fixed copper loss. Simultaneously, reduced iron and PM losses can also be obtained by proposed motor. Finally, a 3-D modeling MS-LMFM motor is built for a global observation of motor structure and further verification of the 2-D analysis. [ABSTRACT FROM AUTHOR]

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]

In this paper, a linear permanent-magnet vernier machine is proposed, in which both magnets and armature windings are placed in the short mover, while the long stator consists of an iron core only. Hence, it is suitable for long-stroke applications such as urban rail transit. The proposed machine integrates two magnetization directions of magnets together, which can reduce leakage flux and enhance flux density. Meanwhile, since different topologies and different slot/pole number combinations have an effect on the winding factor, several general rules are established. It is revealed that the thrust force ripple of the proposed machine is lower than its cogging force ripple, which is explained by a built analytical model. Both the analytical model and the finite-element results are validated by experiments based on a prototype machine. [ABSTRACT FROM AUTHOR]

This paper proposes a new linear hybrid excited flux reversal motor with inset permanent magnets (PMs). The proposed motor adopts the excitation windings in the primary, hence offering the desired flux control capability. The novelty of the proposed motor is to design a modular primary structure. Then, it has very symmetrical and sinusoidal back electromotive force (back-EMF) and smooth thrust even at various excitation currents. In addition, because of the inset PMs, the proposed motor is free from PM irreversible demagnetization. The electromagnetic performances of the proposed motor are analyzed using the time-stepping finite-element method, such as magnetic field distribution, back-EMF, and thrust, verifying the effectiveness of the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a new fault-tolerant linear permanent-magnet (PM) motor, termed as fault-tolerant primary PM (FT-PPM) motor. The proposed motor offers high power density, high efficiency, high fault tolerance and low cost, suitable for maglev transportation applications. Both PMs and windings are set at the steering device of the train, while the only iron stator is fixed between two rails along the whole line. Meanwhile, the new motor topology incorporates the concept of fault-tolerant teeth (FTT) to provide the desired decoupling among phases. The electromagnetic performances are analyzed such as field distributions, inductances, back-EMFs and thrust force. Moreover, by adopting assistant mover teeth, two methods are proposed to reduce the end-effect. Furthermore, the short-circuit current is analytically derived and predicted. The finite-element analysis (FEA) and transient co-simulated results are given for verification. [ABSTRACT FROM PUBLISHER]