Qiang Tan

To solve slot temperature accumulation in high thrust density permanent magnet linear synchronous motors (PMLSMs), this paper proposes an additive manufacturing (AM)-based variable cross-section winding design for coating-cooled tapered PMLSMs. Integrating the magnetic circuit features of tapered PMLSMs and AM windings’ technical merits, the motor’s operating mechanism and electromagnetic distribution are analyzed. With the coating cooling structure as the thermal management foundation, simulation reveals the motor’s temperature distribution under water cooling, defining core slot thermal management requirements. A novel cross-section winding design is then presented: first, a lumped-parameter thermal network model quantifies the coupling between the winding cross-sectional area and slot heat source distribution; second, a greedy algorithm optimizes the winding cross-section globally to reduce the slot hot-spot temperature and suppress temperature rise. Validated by a fabricated tapered PMLSM stator prototype and static temperature-rise experiments, the results confirm that winding cross-section reconstruction optimizes heat distribution effectively, offering a new approach for temperature rise suppression in high thrust density PMLSMs.

Additive manufacturing (AM) enables advanced winding geometries with improved electromagnetic properties, making it well suited for coreless motor applications. Understanding the loss mechanisms and thermal behavior of AM windings is critical for reliable motor operation. This paper investigates the relationship between winding loss, conductivity, and frequency in coreless permanent magnet synchronous linear motors (PMSLMs). An anisotropic equivalent thermal conductivity model for rectangular conductors is developed based on heat-flow distribution. Analytical expressions are derived from key winding parameters and validated through finite element method (FEM). A three-dimensional FEM thermal model is established to analyze winding thermal behavior. It considers structural dimensions, operating conditions, material properties, and high ampere-turns scenarios. The results demonstrate that AM windings significantly improve thermal performance, enabling a 10.8 % increase in ampere-turns capacity and a 34.2 % improvement in thrust density for coreless PMSLMs. Finally, AM winding samples and a motor prototype are fabricated. Experimental results confirm the simulation.

For permanent magnet synchronous motor (PMSM), additively manufactured (AM) windings with variable cross-sectional shapes offer significant advantages in enhancing the slot fill factor and thermal properties, thereby contributing to an increase in power density. This article presents a thermal model for AM windings of PMSM that accounts for the anisotropy of the equivalent insulation thermal conductivity at various locations within the slot. This model improves the accuracy of the predicted winding temperature rise. The physical parameters of AM windings can be controlled by modifying the printing parameters and postprocessing conditions. The impact of electrical conductivity, thermal conductivity, and winding insulation parameters on the losses and temperature rise of PMSMs at various frequencies is then investigated. Finally, the temperature rise characteristics of the prototype PMSMs with the AM windings and the conventional windings are tested and compared, thereby confirming the validity of the thermal model for AM windings as well as their superior thermal properties.

This article proposes a design based on grooved trapezoidal pole for surface-mounted permanent magnet synchronous machines (PMSMs). This design effectively suppresses $2f_{\text {e}}$ vibration while maintaining torque performance. First, the air-gap flux density and radial electromagnetic force are analytically calculated, clarifying the phase relationships of the radial electromagnetic forces. The modulation effect of the stator teeth is explained, highlighting the significant impact of the low-order electromagnetic force generated by this modulation on vibration. Based on these findings, an optimized design using a grooved trapezoidal pole is proposed. This design can modify the amplitude and phase of air-gap flux density harmonics, thereby reducing ( $2p$ , $2f_{\text {e}}$ ) radial electromagnetic force and $2f_{\text {e}}$ vibration. A 12-slot/10-pole PMSM is used as an example for simulation, and the results show that the proposed design effectively suppresses $2f_{\text {e}}$ vibration while maintaining torque performance. Finally, two prototypes are developed, and the experimental results validate the effectiveness of the proposed design.

As additive manufacturing (AM) technologies rapidly advance, their application in fabricating structural components for motors has received significant attention. This paper presents the design of two concentrated winding structures with variable cross-sectional shapes based on AM, which can significantly improve the slot fill factor. Achieving a high slot fill factor significantly enhances the motor's output torque. However, AM windings exhibit increased sensitivity to frequency variations, leading to higher winding losses. An analysis of the loss distribution in AM windings reveals that losses primarily concentrate in the conductors near the slot opening. To minimize these losses, this paper proposes a loss suppression strategy for AM windings that does not compromise the slot fill factor. The optimized windings demonstrate a 26.5% reduction in losses and a 13% decrease in winding temperature. Finally, two distinct prototypes are developed: one utilizing AM windings and the other conventional windings. Both prototypes are tested to assess their electromagnetic and thermal performance.

This paper proposes a double-side long primary permanent magnet linear synchronous motor (PMLSM) that can operate in suspension. In this motor, the levitation subsystem and propulsion subsystem are decoupled in terms of both “electrical circuit” and “magnetic circuit”, resulting in lower system control complexity. For this motor, the normal force between the primary and secondary components is a major component of the motor's levitation force. The normal force ripple can hinder improvements in system positioning accuracy and operational stability. This paper investigates the characteristics of normal force ripple in this motor, establishes a model for local normal force calculation and simulation analysis, and reveals the influence mechanism of end effects and armature reactions on the normal force ripple. Based on this, an optimized design solution for split-ended magnetic pole is proposed, effectively suppressing normal force ripple, both locally and whole. Finally, for a 24-slot 8-pole prototype, finite element simulation and experimental tests are conducted. The results show that no normal force ripple in both local and whole aspects of the motor, validating the theoretical research presented in this paper.

There is not only thrust but also normal force between the primary and secondary components for the single‐side flat plate permanent magnet linear synchronous motor (PMLSM). The normal force will fluctuate periodically, which will cause friction perturbation and finally affect the positioning accuracy of linear feed system. For the single‐side flat plate PMLSM, the variation law of normal force ripple under the coupling effect of multiple effects is studied, and the method of primary component segmental design to suppress it is proposed. Firstly, the influence of the cogging effect, the end effect and the armature reaction on the normal force ripple is analysed. Meanwhile the mathematical model of normal force ripple is established. Secondly, the PMLSM with segmental primary component is introduced and its suppression mechanism to the normal force ripple is expounded. On this basis, a scheme combining the non‐integer pole slot matching with the primary component segmental design is proposed to further suppress the normal force ripple. Finally, an 18‐slot 96/5‐pole prototype is taken as an example to carry out the finite element simulation and experimental test, of which the results verify the research theory in this paper.

The implications of the end effect for flux linkage and thrust ripple in a slot-less long-stator permanent magnet linear synchronous motor (LSPMLSM), are analyzed in this paper. Since it is affected by the end effect, the air-gap magnetic field density under the end permanent magnet is different from that under the non-end permanent magnet, leading to asymmetry in the thrust ripple. For this reason, we establish a dynamic permanent magnet flux linkage model, which proves that the end effect leads to sub-harmonics in the permanent magnet flux linkage. The motor’s magnetic field distribution in the left and right parts is symmetrical. A thrust model taking into account the flux linkage sub-harmonics is established, from which the amplitude and period of the thrust ripple caused by the end effect can be calculated. There is no detent force for the slot-less LSPMLSM, and the end effect is the primary origin of the motor thrust ripple. In order to suppress the end effect, a method of increasing the end iron length is proposed, as a result of which the sub-harmonics in the flux linkage and the motor thrust ripple are effectively suppressed. Experimental and simulation results verify the results of this paper.