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The axial overhang of the permanent magnet (PM) has widely been used to enhance the thrust per loss, particularly in air-core structure where the radial flux density is low. This communication investigates PM overhang effects in coreless-type PM linear machines. To analyze the structure where the magnet length exceeds the active length of the mover coil, a new approach using the conductor separation method is introduced and developed to calculate the electromagnetic thrust of the linear machine designed with the overhang magnet. The proposed method is based on an extended 3-D winding factor and a lumped parameter magnetic circuit model to take end effects into account. It is noted that presented overhang analysis can be applicable to any configurations of wound copper coil. The validity of analytical results derived by the proposed method is confirmed by 3-D finite element and experimental results. [ABSTRACT FROM AUTHOR]

Four modular permanent magnet linear machines (PMLMs) with E-core and C-core primary segments and 12-slot/13-pole (12s/13p) and 12-slot/14-pole (12s/14p) slot/pole combinations are compared in this paper. The influences of flux gap width on the electromagnetic performances and power losses have been investigated based on 2-D finite-element modeling. It has been found that, by choosing proper flux gap width, not only the average thrust force can be improved but also the force ripple and iron losses can be reduced for all the machines. Also, the E-core modular PMLM has higher thrust force and lower detent force compared with the C-core modular PMLM with respect to the same slot/pole combination. Moreover, the 12s/13p modular PMLMs can achieve better electromagnetic performances than the 12s/14p ones regardless of E-core or C-core primary structures. Finally, by shaping the end teeth, the detent force and force ripple of the four modular PMLMs are further mitigated. The 12s/13p E-core modular PMLM is proven to be the best type among these four modular machines. [ABSTRACT FROM AUTHOR]

In this paper, an approach combining current pulses injection and fuzzy logic observer to measure the air gap length of linear machines is proposed. A polymer enclosed by a coil is produced and selected as the test object. The characteristics and production process for the polymer is introduced and its magnetic feature has been studied. Injecting current pulses is used to calculate the self-inductance of the coil fixed on the cores that is directly influenced by the air gap length from the polymer. By using a fuzzy logic observer, the air gap length can be estimated precisely according to the variations of the self-inductance. Experimental results show the effectiveness of the proposed measurement method and the results prove that the proposed method is suitable for the air gap measurement for linear machines. [ABSTRACT FROM AUTHOR]

In this paper, a high-temperature superconductor dual-stator spoke-type linear vernier machine (HTS-DSSLVM) is proposed for wave energy extraction, which offers high-thrust force density and better power factor due to leakage flux reduction. HTS bulks are introduced in between the split flux modulation teeth to shield the leakage flux and hence improve the force density and power factor. The electromagnetic characteristics of the machine are comprehensively investigated and compared with that of a recently presented dual-stator spoke-type linear vernier machine (DSSLVM). The results show that the proposed machine yields higher thrust force and better power factor than the DSSLVM due to reduced leakage flux in the proposed machine. [ABSTRACT FROM AUTHOR]

This paper proposes a novel dc-excited flux-modulated linear machine with a new primary structure for utilizing amorphous core. Although amorphous core is regarded as a good candidate in highly efficient electric machines, and is being investigated for decades, it has not been widely used in electric machines yet. The key challenge is the difficulty in slotting. For the new structure, the difficulty in slotting is avoided. Furthermore, the proposed machine is economical and has a robust double salient structure without any permanent magnets, and both single-toothed field and armature windings are located together in the primary core. By regulating the field excitation, the machine can operate at a wide speed range. Due to the low loss of amorphous core, this machine shows high efficiency at high speed. [ABSTRACT FROM AUTHOR]

In order to fully utilize the high-energy nature of permanent magnet (PM) material, the stator-PM structure and the mover-PM structure of linear machines are integrated into one doubly salient PM machine topology, leading to a new class of doubly salient dual-PM linear machines. In essence, PMs are mounted on both the stator and mover iron cores while avoiding magnetic saturation, hence offering the high force density and high power density. Meanwhile, it consists of a fault-tolerant tooth stator and a consequent-pole mover, which can provide the fault-tolerant capability and exert the salient effect, respectively. By using finite-element analysis, the proposed machine is optimized for application to regenerative shock absorbers which can provide on-board renewable energy harvesting in vehicles. The machine performances are analyzed and quantitatively compared with that of its counterparts including the stator-PM linear machine and the mover-PM linear machine. Moreover, both the flat and tubular morphologies of the proposed machine are quantitatively compared and discussed. [ABSTRACT FROM AUTHOR]

The aim of this paper is to propose an efficient and unique reluctance network (RN) model for all translator displacements of a linear hybrid motor. This model has to consider several translator positions to analyze the linear motor performances. The proposed RN model takes into account the magnetic characteristic and the flux leakage. Consequently, the proposed model gives precise results of the electromagnetic characteristic. The RN model considers an interesting solution to deal quickly with an optimization task of a large number of constraints and parameters. The developed model is coupled with sequential quadrating programming method for an optimization process of the linear machine. The obtained results confirm the efficiency of this method for modeling and optimization of the linear machine. [ABSTRACT FROM AUTHOR]

A new flux reversal permanent magnet (FRPM) linear machine known as the partitioned stator FRPM (PS-FRPM) linear machine is proposed. The structure and the operation principle of the machine are described, and the major design parameters are optimized for maximum thrust force. A periodic model is also used in the analysis in order to highlight the significant effect of the longitudinal end effect on the machine performance, particularly in terms of unbalanced magnetic circuit and cogging force. Furthermore, the proposed machine is compared with the conventional FRPM linear machine. It is concluded that higher thrust force, less cogging force, and consequently less thrust force ripple can be obtained by the proposed machine. [ABSTRACT FROM PUBLISHER]

Permanent magnet (PM) tubular machines have been applied to many applications, since they offer high force density with no end winding and no net attractive force between the mover and the stator. In this paper, two novel PM tubular machines named partitioned stator interior PM (PS-IPM) and partitioned stator surface-mounted PM (PS-SPM) tubular machines are proposed. Both the proposed machines are optimized for maximum thrust force, and their electromagnetic performance has been compared. It is found that the PS-IPM tubular machine has higher thrust force capability and better magnet utilization compared with the PS-SPM tubular machine. However, due to lower cogging force, the PS-SPM tubular machine has fewer thrust force ripples. Furthermore, the effect of the cross-coupling magnetic saturation on PM flux linkage, and the $d$ -axis and $q$ -axis inductances for both the proposed machines is investigated. It is demonstrated that the PM flux linkage and the $d$ -axis and $q$ -axis inductances are affected by the cross-coupling magnetic saturation. Moreover, the force–velocity characteristics of the proposed machines are calculated and compared. It is observed that both the machines have good constant power operation capability. [ABSTRACT FROM PUBLISHER]

A novel tubular staggered-tooth transverse-flux permanent magnet linear synchronous machine is proposed. The machine is characterized by simple structure and low flux leakage. First, the structure and the operational principle are introduced. Second, the 3-D equivalent magnetic circuit model of the machine is built, and the analytical expression of the electromagnetic force is derived. Last, the force density and the force ripple are optimized with respect to three key dimensional ratios by the 3-D finite-element method. An optimized scheme with the high force density of 2.697 \times 10^5 N/ \textm^3 and the low force ripple of 2.78% is achieved. In addition, the characteristics of the proposed machine are compared with other topologies of linear machines. [ABSTRACT FROM AUTHOR]

A novel permanent-magnet linear machine that consists of several isolated movers and one single stator is proposed in this paper. It is especially suitable for tasks requiring multiple drive machines. Each mover can produce independent thrust and flexible motions by interacting with the stator poles. Compared with conventional multimotor driven system, it helps to achieve more compact size, and thus improve the system working efficiency. The design concept is presented, and the magnetic field distribution in the machine is formulated analytically. The influence of magnetization patterns and back iron is included in the analysis. The research result indicates that the employment of same-magnetization pattern helps to improve the magnetic flux density and thus the thrust output of the system. A research prototype of the linear machine with two isolated movers is developed. Numerical computation and experiment measurement are carried out to verify the analytical models. Comparison shows that the analytical model fits with finite-element analysis and experimental results well, and the influence between the mover motions is negligible. The similar design concept of multimover and single-stator can be implemented into other rotary electromagnetic machines. [ABSTRACT FROM AUTHOR]

An integrated rotary–linear machine based on switched reluctance principle is investigated. The characteristics of the motor are analyzed by finite-element methods, with particular emphasis on the coupled magnetic paths. Results from numerical calculation are verified by the hardware experiment. The simple yet effective decoupling algorithm for the independent position control of both rotary and linear axes is proposed. Implemented with the proportional–integral-differential algorithm, the motor is capable of high-precision rotary and linear position tracking with the steady error within 0.3^\circ and 10~\mum, respectively. [ABSTRACT FROM AUTHOR]

The permanent magnet linear vernier (PMLV) machine is becoming attractive for low-speed and direct-drive applications. Due to its vernier structure and multipole configuration, the flux leakage especially the tooth-tip flux leakage is severe. In order to analyze its leakage flux, the magnetic equivalent network of the PMLV machine is applied for analytical modeling. During modeling, the fringing effect in the air-gap is taken into consideration. The key for the flux leakage calculation is to calculate the permeances at different tooth positions. Finally, in order to evaluate the proposed analytical model of the PMLV machine, the finite element method is employed for numerical calculation. The comparison between the analytical and numerical results verifies that the proposed analytical modeling approach is valid and accurate. [ABSTRACT FROM AUTHOR]

We have developed a permanent magnetic pavement marking tape. Sections of varying magnetization wavelength were installed in a 230-m linear array. Magnetic field profiles were determined at lateral displacements from the tape out to 0.9 m. Calculations based on a surface pole model with no adjustable parameters gave excellent agreement with the experimental results. [ABSTRACT FROM PUBLISHER]

This paper will provide an optimal pole arrangement design scheme of a switched-reluctance machine that is applicable for magnetic levitated vehicle (MAGLEV) system. The proposed low-cost machine structure will be able to supply both the levitation and the propulsion forces simultaneously. Minimum torque generation and smooth switch operation in the entire operation range have been selected as the design objectives subjected to the available machine bogie and electromagnet sizes. Comparison studies on the system electromagnetic and electromechanical characteristics will be provided to verify the adequacy of the proposed design scheme. [ABSTRACT FROM PUBLISHER]

In this paper, examination of the limiting value of the thrust constant of a linear DC motor (LDM) is described. The LDM under consideration is a moving coil unipolar type. We deduce a relation between the limiting value of the thrust constant LDM and the dimensions of the yokes. By comparison of the measured thrust and the magnetic field analysis (finite element method), the validity of the thrust constant limit equation is confirmed. The thrust constant limit equation qualitatively agrees with the observed result, and its maximum error is 26.0 percent. It also agrees well with the result of the magnetic field analysis. [ABSTRACT FROM PUBLISHER]

The use of field weakening in the control of linear brushless AC machines is investigated using finite element modelling and is shown to be viable. The results are validated using a practical machine. [ABSTRACT FROM PUBLISHER]