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As rare-earth permanent magnet prices continue to fluctuate, interest in non-rare-earth permanent magnet-assisted synchronous reluctance motors (PMa-SynRMs) is increasing. However, non-rare-earth PMa-SynRMs have a multi-layer structure with interior permanent magnets to compensate for the low magnetic fields. Therefore, the rotor has several design parameters, and electromagnetic analysis is time-consuming. To overcome these challenges, magnetic equivalent circuit analysis was used to perform fast electromagnetic analysis of non-rare-earth PMa-SynRMs. In addition, the validity of the proposed method was confirmed through a comparison of the obtained results with those of finite element analysis. [ABSTRACT FROM AUTHOR]

For some propulsion motors that can utilize reluctance torque, the structure of d- and q-axis is different, resulting in more motor parameters and longer design cycle. To improve the design efficiency, the relationship between the spectrum characteristics of the magnetic field and the spatial distribution of silicon sheet in propulsion motor is researched and analyzed. A new design process is proposed based on researching this influence. By analyzing the spectrum characteristics of existing motor structures, the range of parameter optimization to achieve the final design is reduced. Finally, a simple example is given to verify the feasibility of the method by finite element method (FEM) and analyze the existing problems. [ABSTRACT FROM AUTHOR]

The development of dual phase soft magnetic laminate for advanced electric machines at General Electric is summarized, including alloy development, properties, manufacturing trials, prototype experience, potential applications, and future material development. Dual phase soft magnetic laminates provide the flexibility to tune magnetic/non-magnetic state at the desired locations, using solution nitriding treatment with protective mask/coating. This enabling material technology benefits electric machine performance by reducing flux leakage in the laminates. It also decouples the electromagnetic and mechanical design, which opens up the design space for advanced electric machines. Magnetic and mechanical properties of dual phase laminates were compared to commercial FeSi and FeCo soft magnetic laminates. Driven by the market needs for high power density and high-speed electric machines, a synchronous reluctance (SynRel) machine without PMs using dual phase soft magnetic laminates was assessed in machine electromagnetic performance as well as rotor stress analysis by finite element simulation. Successful prototype build and testing further retired manufacturing risks and advanced the technology maturity level. Future material development with higher mechanical strength, higher saturation magnetization, higher permeability, and lower loss are highly desired for ground and air transportation electrification. [ABSTRACT FROM AUTHOR]

In order to overcome the disadvantages of 12/8 pole bearingless switched reluctance motors (BSRMs), such as high commutation frequency, more stator windings, and more power devices, a 6/4 pole BSRM with half the commutation frequency and number of windings is studied. The structure characteristics and operation characteristics of the 6/4 pole BSRM are investigated through modeling, simulation, and prototype experiment, and the main performance indices, such as suspension force, inductance performance, and air-gap flux density, are evaluated to reveal the levitation control mechanism of the 6/4 pole BSRM with permanent magnets in its stator yoke. The motor can suspend stably in the radial direction, and the correctness and feasibility of the theoretical analysis are verified. [ABSTRACT FROM AUTHOR]

Because a rotor has no permanent magnet and low manufacturing cost, a bearingless switched reluctance motor (BSRM) has unique advantages in medical and health, biochemical reactions, and other applications that need to be abandoned after single use or require the system to deal with high-temperature fluid. By analyzing the topological characteristics of a BSRM, rotor suspension and the mechanism of operation were described. A finite element model of a BSRM with a permanent magnet in the stator yoke (BSRM-PMSY) was established. The performance analysis of the BSRM was emphasized. The airgap flux distribution, no-load permanent magnet flux linkage, and torque of the motor were analyzed under zero load back-electromagnetic flow signals and levitation forces. The results verify that the optimization effect of the new motor on the levitation force is correct and a favorable decoupling control effect is found between the torque and levitation force, which provides the basis for efficient control of the subsequent prototype. [ABSTRACT FROM AUTHOR]

To solve the magnetic field coupling problem in the traditional bearingless permanent-magnet motor, which has magnets on the rotor, we propose two topologies of bearingless switched reluctance motors (BLSRMs) with magnets on the stator yoke. The first is a six/four-pole BLSRM with three pairs of permanent magnets on the stator and the second is a six/four-pole BLSRM with one pair of stator yoke magnets. First, the working principle of BLSRMs is introduced, including the structure and winding configuration, and the mechanism of generating levitation force is analyzed in detail. Based on 2D finite element analysis, the electromagnetic characteristics of the prototype are compared, including torque, suspension force, no-load back EMF, and no-load permanent magnet linkage. The calculation results show that at high speeds, the coupling between the levitation force winding and the torque winding of the BLSRM with one magnet pair is low, which allows for better decoupling performance and greater levitation force. In addition, although the motor with three pairs of permanent magnets in the stator yoke shows better torque performance, the loss of the motor is higher at a high speed. The research results lay a theoretical foundation for further research on a new type of bearingless motors. [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]

Low-energy permanent magnet (PM) such as ferrite is usually adopted in a PM-assisted reluctance (PMAREL) motor to enhance the output torque and reduce costs. However, the relatively lowmagnetic energy product and remanence in such PMs may lead to the risk of demagnetization. By using two types of materials of rare-earth NdFeB and nonrare- earth ferrite PM, a new less-rare-earth hybrid PMAREL motor is proposed in this paper, where the output torque and the power factor can be improved obviously, and meanwhile the risk of irreversible demagnetization in ferrite PMs can be reduced significantly due to the existence of NdFeB PMs. To verify the validity of the proposed motor, the operating principles of the motor and the positive interaction influences between the two involved types of PMs are analyzed. Moreover, by using the finite element method, the torque characteristics and anti-demagnetization capabilities are also investigated in details. Both the theoretical analysis and simulated results confirm the advantages of the proposed motor. [ABSTRACT FROM AUTHOR]

According to the strong nonlinear electromagnetic characteristics of switched reluctance machine (SRM), a novel accurate modeling method is proposed based on hybrid trained wavelet neural network (WNN) which combines improved genetic algorithm (GA) with gradient descent (GD) method to train the network. In the novel method, WNN is trained by GD method based on the initial weights obtained per improved GA optimization, and the global parallel searching capability of stochastic algorithm and local convergence speed of deterministic algorithm are combined to enhance the training accuracy, stability and speed. Based on the measured electromagnetic characteristics of a 3-phase 12/8-pole SRM, the nonlinear simulation model is built by hybrid trained WNN in Matlab. The phase current and mechanical characteristics from simulation under different working conditions meet well with those from experiments, which indicates the accuracy of the model for dynamic and static performance evaluation of SRM and verifies the effectiveness of the proposed modeling method. [ABSTRACT FROM AUTHOR]