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This paper compares the machine learning algorithm‐based prediction methods for the traction characteristics in linear traction induction motors operating at common working conditions, i.e. different slip and running velocity, with a symmetric or asymmetric secondary. These models provide a method for obtaining the dynamic characteristics in the motor that considers nonlinear effects. First, some analytical results for the prototype machine under different working conditions is calculated. Second, classification and feature extraction of traction characteristics results including thrust, transversal and vertical forces is made according to the different slip, running speed and lateral secondary displacement, and the results set is divided into training sets and test sets. Third, the prediction model established by different machine learning algorithms are analyzed and compared in principle. These algorithms in this paper mainly contain: artificial neural networks (ANNs), linear regression (LR), symbolic regression using GP, k‐Nearest Neighbour (kNN), random forests (RFRs). The machine learning algorithm‐based prediction methods are trained with the training set, and then the verified with the test set. Finally, this paper discusses the most optimal model for predicting traction characteristics. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Since the linear induction motor commonly work with a laterally asymmetric secondary as it is applied to pull rail vehicles, this paper presents a complete equivalent circuit model considering the asymmetry to predict thrust, vertical and transversal forces. First, six correction factors are presented to quantify the variations in the air-gap magnetic flux and secondary induced current as the linear induction motor operating with a laterally asymmetric secondary. Second, it develops a circuit model based on the existing T-model for the rotary induction motor and two correction factors for the magnetizing branch, which is used to indicate the electromagnetic variations in the air-gap flux and secondary plate due to the asymmetry. Third, the mathematical expressions for the thrust, vertical and transversal forces are derived by applying the equivalent circuit model. Then, the six correction factors are calculated with a prototype motor, and the results of them are comprehensively analyzed. Finally, the characteristics in the prototype motor are calculated with the mathematical expressions in a range of rated speed, and validated by the experimental measurements carried out on a test rig and line for linear motors. [ABSTRACT FROM AUTHOR]

Since single-sided linear induction motors working with a lateral asymmetric cap secondary is a frequent operating condition, this paper develops an equivalent circuit model considering the asymmetric condition. First, an analysis model, which takes the longitudinal end effect and skin effect into consideration, is proposed. Second, a transversal analysis model considering the laterally asymmetric cap secondary is developed to derive its correction factors. Then, the influence of lamination eddy current on the effective air gap to transversely directed flux is contrastively analyzed. Third, the traction characteristics of a prototype motor with symmetric and asymmetric cap secondary are calculated by the equivalent circuit. Finally, these calculated results are verified by measurements carried out by a test rig of the linear motor. [ABSTRACT FROM AUTHOR]

This study investigates the influence of the composite secondary with the solid and laminated back iron on the thrust, vertical force, secondary losses and efficiency in the prototype single-sided linear induction motor for metro by space harmonic method. First, a 3-D space harmonic analytical model, which can consider the skin effects, secondary constructions as well as end and edge effects, is proposed. Second, the air-gap flux and secondary eddy current density distributions along longitudinal and transverse directions are presented. Then, variations of secondary losses and efficiency with a specific number of secondary back iron laminations are comprehensively compared in the full slip, and the optimal number of laminations is obtained. Third, the propulsive and vertical forces are analytically calculated under full slip, and the efficiency in a range of rated speed is presented. Finally, these results are verified by measurements on an experimental rig of the linear motor. [ABSTRACT FROM AUTHOR]

This paper develops a novel magnetomotive forces (mmfs) distribution model along the transverse direction for the 3-D analysis of linear induction motor, and it investigates the influence of a laterally asymmetric cap-secondary on the thrust, vertical force, lateral force, and efficiency in a prototype single-sided linear induction motor for linear metro. First, the mmf distribution model and its working conditions are defined, and the model is transferred into a mathematical model. Second, the air-gap flux and secondary eddy current in a prototype linear motor with a cap-secondary are obtained by a 3-D space harmonic analytical method. Third, the thrust, vertical force, lateral force, and efficiency of the test motor are analyzed with various lateral deflection, and the power factor in secondary is also presented. Finally, these results are experimentally verified by measurements on the test rig of the linear motor, and the comprehensive effect on the operating performance can be accurately calculated by the mmf model. [ABSTRACT FROM PUBLISHER]

Presents corrections to funding information from the above named paper. [ABSTRACT FROM AUTHOR]

A quasi-three-dimensional (3-D) analytic method is presented for calculating the performance of single-sided linear induction motor with the ladder secondary. To simplify the analytic model, the ladder aluminum plate is equivalent to the flat-solid one, and the equivalent conductivity is derived and given. In the direction of the motion, the finite primary length and end effect are considered by the method of the Fourier transform and Residue theorem. In the transverse direction, considering finite width of the primary core and the region between the overhang of the primary windings and the secondary, the equivalent integral length is given. Finally, the thrust, vertical force and secondary efficiency are calculated and compared with the results of the 3-D finite-element method and experiment, it is shown that the method presented in the paper is much simpler and the accuracy of the analytic method is verified. [ABSTRACT FROM AUTHOR]

This study mainly investigates the key secondary parameter effecting on transverse force and the changing trend of its components, which include the repulsive and restoring components. Firstly, considering the transverse displacements, skin effect and end effects, the full 3D finite element models of the single‐sided linear induction motor (SLIM) are built. Secondly, when the width of the secondary varies, the transverse force and its two components are presented and analysed. At the same time, the air‐gap flux densities and the eddy currents along the transverse directions are calculated. Then when the topological transform of aluminium plate (e.g. Al‐cap type) and back‐iron plate (e.g. laminated type) are applied, the transverse force and its components are given. Finally, the transverse force, thrust and efficiencies are compared in the SLIMs with different secondaries as well as some experiments are given. It is shown that the width of the secondary is the main factor influencing the transverse force. [ABSTRACT FROM AUTHOR]

In this paper, the influence of the flat and cap secondary, which are usually applied in the linear metro system on transverse forces of linear induction motors, is calculated and analyzed. First, the cap-aluminum plate and lamination back iron of the cap secondary caused relative difficulty in the analytical calculation. Then, the equivalent of the cap-aluminum plate and lamination back iron is presented, and two equivalent coefficients are obtained. The two types of the asymmetry are discussed and the different magnetic motive forces are presented. Second, the analytical model and the method of the linear induction motor are presented. Third, for a cap secondary in practice, the two equivalent coefficients are calculated and discussed. Then, the flat and cap secondary are applied, and the different transverse forces are calculated and analyzed. For two types of the secondaries, the different eddy currents and air-gap flux densities are compared. Finally, the test workbench is built and the analytical result of the transverse force is experimentally validated. It shows that cap secondary has less influence on the railcar when the transverse displacement occurs. [ABSTRACT FROM AUTHOR]

Owing to the larger total harmonic distortion (HD) of the air‐gap magnetic field in the linear induction motors with the flat‐solid and direct‐slit secondary, the construction of V‐type secondary is proposed and investigated, to reduce the harmonic components. First, a skew factor is presented to indicate the influence of the tooth harmonic on the air‐gap magnetic field. The skew distance is a key point for the design of the V‐type secondary, and the influence of the different skew distances on the thrusts, HD, and efficiencies are analysed by the three‐dimensional finite‐element method. Finally, the eddy currents, the air‐gap flux densities, and electromagnetic forces are calculated in the linear induction motors with the V‐type secondary. It shows that the V‐type secondary can reduce the harmonic components and improve the performance. [ABSTRACT FROM AUTHOR]

Due to the influence of the switch and rail equipment, the secondary cannot be laid continuously in the linear metro. An equivalent circuit of the single‐sided linear induction motor (SLIM) is presented to consider the discontinuity of the secondary plate, and the electromagnetic characteristics of the motor with the discontinuous secondary are obtained. First, the analysis model of the SLIM considering the missing part of the secondary plate is proposed. Second, the variation of the length of the coupled region between the primary and secondary are considered by the method of approximate linearisation to correct the parameters including the primary leakage inductance, magnetising inductance, secondary resistance and secondary leakage inductance. Third, three typical cases of the relative position between the primary and discontinuous secondary are analysed, and the equivalent circuit in each case is deduced according to the distribution of the secondary magnetic motive force and air gap flux density. Then, two coefficients considering the longitudinal end effect, on the basis of the corrected secondary time constant, are proposed to correct the magnetising inductance and secondary resistance. Finally, the analytical results are verified by the results measured on the test rig of an SLIM. [ABSTRACT FROM AUTHOR]

In order to improve the performance of linear induction motors for urban rail transit, the ladder-slit secondary is designed, and the performance of linear induction motors with the ladder-slit and flat-solid secondary is calculated and compared. First, for the ladder-slit secondary, the slot combination, widths of the secondary conductor, and side bar are designed. Second, the finite-element model of the linear induction motor with the ladder-slit secondary is developed, and the influence of vertical forces on widths of secondary conductors is presented. Third, the eddy current and the transversal air-gap flux density are compared when the ladder-slit and flat-solid secondaries are applied, respectively. Finally, experiments are carried out by test lines to validate the calculated results of the force and efficiency. It shows that the ladder-slit secondary can reduce the edge effect and improve the performance. [ABSTRACT FROM PUBLISHER]

The secondary is an important design factor of single‐sided linear induction motors (SLIMs), as well as has influence on the cost and performance of SLIMs. In this study, the cap‐lamination secondary is designed and relations of the secondary parameter and performance of SLIMs are calculated. First, the aluminium (Al) cap and lamination back iron of the cap‐lamination secondary are designed and discussed. Then, improvements in performance caused by two potentially significant effects of the cap‐lamination secondary, i.e. the thick cap edge and lamination, are identified. Second, a flat‐solid secondary is applied and two SLIMs, which are the same primary and two different secondaries, are calculated by three‐dimensional finite‐element method. Eddy current densities in the Al and back iron plate, which are two parts of the secondary, are analysed. Owing to different transverse edge effects, variations of the air‐gap flux density are calculated with different secondaries. Finally, the numerical results of the thrust, power factor, and efficiency are experimentally validated by measurements on test rig of SLIMs. It shows that the SLIM with cap‐lamination secondary, which has higher performance, is affected greatly by the conductor structure of the secondary and the lamination of the iron back plate. [ABSTRACT FROM AUTHOR]

This paper introduces a sensorless control strategy of permanent magnet synchronous motors, termed the fast super twisting algorithm-based sliding mode improved model reference adaptive system observer (FSTA-SM-IMRASO). The proposed observer builds upon the conventional model reference adaptive system observer (MRASO) by incorporating a feedback correction term. Additionally, an adaptive feedback gain is devised to accommodate varying system operating conditions, thereby significantly enhancing the convergence speed of the error between the reference model and the adjustable model. Furthermore, a fast super twisting algorithm featuring an enhanced exponential term is devised and integrated with the model reference adaptive system theory, replacing the conventional PI controller used in MRASO. This integration leads to notable improvements in the system dynamic and static capabilities. Finally, the effectiveness of the proposed strategy is verified by simulation. [ABSTRACT FROM AUTHOR]

A key factor concerning the superconducting application of HTS tapes is the volume of current they can carry. The resistivity of the HTS tape is theoretically zero if lower than the critical temperature, but it cannot carry an infinitely large current. Therefore, the critical current of different HTS tapes must be evaluated to determine their maximum current carrying capacity. First, this study proposed an experimental structure based on controllable dc current ramp rate (R-value) and the critical current of three kinds of tapes were measured, respectively. Finally, this research provides new insight into the understanding of HTS tapes with the magnetic substrates and the nonmagnetic substrates. [ABSTRACT FROM AUTHOR]