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The mass production of the motors causes tolerance of shape and dimension, deviation of permanent magnet remanence and rotor eccentricity error, which affect the cogging torque and torque ripple amplitude and performance consistency. In order to reduce the torque ripple of the motor in the actual condition, the robustness optimization is performed in the paper. Firstly, an improving convex arc type permanent magnet structure is adopted to improve air gap flux density and suppress the cogging torque. Secondly, the structure parameters of the magnetic pole are selected as optimization variables, and the magnetization angle, remanence and position of the permanent magnet, static and dynamic rotor eccentricity are considered as noise factors. To improve the overall robustness of the motor under different operating conditions, the dynamic Taguchi method is used to optimize the robustness of the motor, and the test data is processed through the relation analysis method to obtain the optimal combination of control factors. Finally, the prototype is manufactured for the experiment. Compared with the single‐operating conditions robust optimization results, the robust optimization method improves the robustness of the motor. The cogging torque amplitude is reduced by 39.2%. The torque ripple is 38.4% lower than that before optimization. [ABSTRACT FROM AUTHOR]

In this article, a suspension‐guided permanent magnet synchronous linear motor (SG‐PMSLM) for ropeless elevator is proposed, which can meet the requirements of high thrust and high thrust density for ropeless elevator, and reduce vibration noise and wheel‐rail wear during motor operation. The structure, working principle and electromagnetic characteristics of SG‐PMSLM are analysed. In order to improve the overall performance of SG‐PMSLM, this article aims at improving the average thrust and thrust density, reducing the thrust fluctuation of SG‐PMSLM. Firstly, the sensitivity analysis of the key structural parameters of SG‐PMSLM is conducted, and the parameters that have significant influence on the three optimisation objectives are selected as the optimisation variables. Secondly, the response surface model of three optimisation objectives is built, and the Particle Swarm Optimisation algorithm is combined to conduct the multi‐objective optimisation design for SG‐PMSLM. Thirdly, the optimised solution set is obtained for three objectives. Finite Element Analysis is used to verify that the optimised solution set has better diversity and can effectively improve SG‐PMSLM overall performance compared with the initial design. Finally, the electromagnetic performance of SG‐PMSLM is verified by experiments. [ABSTRACT FROM AUTHOR]

Permanent magnet linear synchronous motor (PMLSM) is one of the ideal driving sources of ropeless elevators. However, such motors, whether moving magnetic or moving coil, will produce the problem of excessive cost under long travel. The permanent magnet flux switched linear motor (PMFSLM) with permanent magnets (PMs) and copper coils on the mover side greatly reduces the cost. A U‐type PMFSLM is proposed in the paper. First, a PMFSLM is proposed and investigated, quantitatively comparing with PMLSM for the ropeless elevator system. Second, aiming at the problem of flux leakage at the top of PMFSLM, a U‐type PM (UPM) structure is presented. The electromagnetic performance of PMFSLM and UPM‐FSLM have been compared and summarised. The comparison results show that UPM‐FSLM solves the defect of top flux leakage, increases thrust by 4.34%, reduces thrust ripple by 28.10%, and has better electromagnetic performance than PMFSLM. Afterwards, the elevator passenger capacity of PMFSLM and UPM‐FSLM are simulated and calculated and the feasibility is analysed. Finally, a prototype of PMFSLM has been built and measured. [ABSTRACT FROM AUTHOR]

Two degree‐of‐freedom direct drive induction motor (2DoFDDIM), capable of rotary, linear and helical motion, has widespread application. A new mover structure is proposed, which is made from a hollow cylinder with copper cast in the axial slots and the circumferential slots on its surface. Then, three‐dimensional finite element models of 2DoFDDIM are used to determine the performances of rotary, linear and helical motion developed by the motor. The results show that the new mover has a great improvement on the motor performances of all modes of motions compared with the initial mover. The researches on mover structure and characteristics of 2DoFDDIM present a new path of optimisation on 2DoFIM. [ABSTRACT FROM AUTHOR]

This study presents a fault coil localisation approach for a direct‐drive permanent magnet synchronous motor (DDPMSM) with inter‐turn short‐circuit fault (ISF) using the search coil (SC) array. The SCs are wound around specific stator tooth of DDPMSM through the proposed SC array arrangement principle, which reduces the invasiveness of the fault coil localisation method. The SCs are classified as several search coil groups (SCGs), the differential between SC back electromotive forces (EMFs) in the same SCGs (δ1) and SC residual back EMF (δ2) are used as fault indicators for ISF localisation. The peak values extracted from δ1 and δ2 are the basis for diagnosing ISF. Hence, the proposed approach does not need a complicated signal processing algorithm, and it is less complex. First, the SC back EMF analytical model is developed to investigate the mapping relationship between the back EMF of each SC and fault coil location. Second, fault coil localisation indicators for ISF are analysed based on the proposed analytical model, and the exact ISF localisation approach is presented. Finally, two basic installation units and the arrangement principle of SC array in DDPMSM are proposed. Simulation and experimental results justify the effectiveness of the selected fault indicators and the feasibility of the proposed SC array for diagnosing ISF. [ABSTRACT FROM AUTHOR]

This paper studies a superconducting maglev submersible cryogenic liquid pump (CLP) using superconducting magnetic bearing (SMB). A new structure is proposed for the self‐stability of high‐temperature superconducting magnetic levitation, and the compact structure of disk motor‐pump. The rotor of the axial‐flux disk motor is connected with a centrifugal impeller to form an impeller‐rotor of the proposed superconducting CLP. Supported by a SMB system, the impeller‐rotor rotates frictionlessly with self‐stabilisation as a suspension rotor. The SMB system includes a radial‐type SMB, an auxiliary permanent magnet bearing, and an electromagnetic bearing composed of the stator and the rotor of disk motor. Theoretical calculations and experimental measurements are performed to examine the axial and radial levitation force behaviours of the SMB system. Then, a kinetic model of the suspension rotor is established and analysed to assure force balance and stable levitation. Finally, a prototype pump is fabricated and an experimental setup for liquid nitrogen transmission is constructed for validation purposes. The experimental tests on the pump head and the flow rate are carried out, which demonstrate the effectiveness of the proposed superconducting maglev submersible CLP. [ABSTRACT FROM AUTHOR]

A permanent magnet synchronous motor (PMSM) is introduced with 120° phase belts toroidal windings (PBTWs) (120°PBTWPMSM), in which its armature reaction field principle is elaborated. Then, the experiment concerning the 120°PBTWPMSM is conducted to verify the validity of the related analysis and the feasibility of the 120°PBTWPMSM. In addition, a method of shifting the magnetic poles (SMP) is adopted to suppress the cogging torque and the torque ripple. After this, the 120°PBTWPMSM after SMP is further optimised by the Taguchi method to obtain the structural parameters of the motor with optimal comprehensive performance. Finally, the performance of the original motor, the 120°PBTWPMSM after SMP and the optimal motor are compared, which verify the effectiveness of the optimization methods. [ABSTRACT FROM AUTHOR]

Inter‐turn short‐circuit fault (ISF) degrades its reliability and may cause serious catastrophes for direct‐drive permanent magnet synchronous motor (DDPMSM). Fault location technology can reduce maintenance time, increase the mean time between failure (MTBF), and then improve the reliability of DDPMSM. Hence, an intelligent fault locating system for DDPMSM is proposed in this paper. This system proposes a knowledge graph (KG) based diagnostic tool for detection and location of the fault coil. First, the fault model of the DDPMSM with multiple branches parallel winding is established, which is used to analyze the fault characteristics of motor. Second, the BDC and BRC are proposed as the fault indicator. The effectiveness and robustness of fault indicator are analyzed. Then, the KG system are designed and established according to the relationship between fault indicator and location of fault coil. Finally, the system is tested by data under different fault and operation conditions. The test results showed that the proposed fault locating system can detect and locate the fault coil in early stage. The minimum ratio of shorted turns to branch turns that can be detected is 0.52%. The minimum ratio of shorted turns to branch turns that can be located is 6.25%. [ABSTRACT FROM AUTHOR]

Owing to its many benefits, including convenient and short computing time, the analytical model (AM) is widely used in the performance analyse of the permanent magnet synchronous motor (PMSM). The existing analytical models based on phase winding cannot sufficiently speculate about the contribution of the coil to the performances of direct‐drive PMSM (DDPMSM) with series coils and multiple branches. Hence, in this work, a novel AM for the DDPMSM is proposed. This model, which is based on the winding sub‐element, can analyse the influence of coil on motor performance. First, the structure and key parameters of the DDPMSM are reported. Second, an inductance matrix, which considers the spatial disposition of coils and the characteristics of large self‐inductance and small mutual inductance, is constructed. Then, the influence of the coil on motor performance is analysed based on the proposed AM. Finally, the results of AM, finite‐element model and experiment are compared. The results validate the correctness of the proposed AM. Furthermore, the proposed AM can speculate about the contribution of a coil in the DDPMSM performances with satisfactory accuracy. [ABSTRACT FROM AUTHOR]

This study presents a composite multilayer method (CMM) to evaluate the performance of a two‐degree‐of‐freedom (2DoF) direct drive induction motor (2DoFDDIM) whose solid rotor is coated with a copper layer. It includes a rotary part and a linear part. Based on the traditional multilayer theory, a complete 2DoFDDIM CMM computer program importing propagation constants is built. Due to the complex magnetic field in a 2DoFDDIM, this study mainly analyses it from the perspective of a single DOF motor. An equivalent circuit for the rotary part of the 2DoFDDIM is then derived applying CMM and the 2D magnetic field distribution is obtained by solving Maxwell's equations in motor layers. The developed torques, power factors and stator currents of the rotary part with different slips and the latter two of the linear part at zero speed are calculated by CMM, which are then compared with results from the finite element method (FEM) and experimental results. The computation time of the CMM is far less than that of the FEM. The acceptable accuracy confirms the effectiveness of the CMM for analysis and performance calculations of the 2DoFDDIM. [ABSTRACT FROM AUTHOR]