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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>Research on the Control of Magnetic Weakening Scheme for the Voltage
     Utilization Rate of Hybrid Transmission</title>
      <link>https://trid.trb.org/View/2742518</link>
      <description><![CDATA[This paper proposes a field-weakening control method for permanent magnet                     synchronous motor (PMSM) current regulators based on the ratio of                     voltage-frequency ratio and voltage utilization rate when the motor speed                     exceeds the field-weakening speed; that is, the direct-axis offset current id is                     generated through the action of field-weakening feedforward and field-weakening                     PI regulator, and the control of field-weakening speed can directly adjust the                     demagnetization effect of id to achieve field-weakening control of PMSM. The                     field-weakening control method of PMSM current regulators with the outer loop of                     voltage utilization rate is adopted. It is proposed to use the phase-locked loop                     control method to decode the motor position signal in a closed loop and                     calculate the motor speed. The fluctuation of the position signal is reduced and                     the signal is more stable. This paper realizes constant power speed regulation                     based on high voltage utilization rate and field-weakening control method at                     high-speed operation above the base speed, which greatly improves the dynamic                     performance and system efficiency of the system.]]></description>
      <pubDate>Thu, 13 Aug 2026 17:00:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2742518</guid>
    </item>
    <item>
      <title>Rotor Electromagnetic Structure Optimization for Improving the Efficiency of Permanent-Magnet Synchronous Motors in New Energy Vehicles</title>
      <link>https://trid.trb.org/View/2732064</link>
      <description><![CDATA[Rotor electromagnetic structure optimization (RESO) has emerged as a key approach for improving the efficiency of permanent-magnet synchronous motors (PMSMs), resulting in a substantial volume of published studies. This paper systematically reviews the major RESO strategies targeting efficiency improvement. The rotor electromagnetic-structure characteristics and efficiency evaluation indicators are identified. Then, according to the different optimization mechanisms of the rotor structure, RESO techniques are classified into several classic categories. The most popular optimization methods are summarized in terms of their mechanisms, characteristics, and complexities. Finally, current research limitations and future directions are highlighted. This review indicates that RESO is an important pathway for improving efficiency, but its effectiveness depends on motor topology, operating conditions, performance requirements, manufacturing feasibility, and cost constraints. It is expected that this review will provide useful guidelines for designers and researchers seeking to enhance PMSM efficiency and offer insightful prospects, indicating where extra efforts are needed.]]></description>
      <pubDate>Wed, 12 Aug 2026 15:14:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2732064</guid>
    </item>
    <item>
      <title>A Novel Double Stator Consequent-Pole Transverse-Flux Motor with Trapezoidal Teeth and Permanent Magnets</title>
      <link>https://trid.trb.org/View/2735085</link>
      <description><![CDATA[As a low-speed, high-torque motor, the transverse-flux motor (TFM) holds significant potential for direct-drive applications. First, this article proposes a novel double stator consequent-pole transverse-flux motor (DSCP-TFM) to enhance torque density and motor space utilization. The DSCP-TFM features the tooth and permanent magnets (PMs) distributed on both stators and the rotor. Second, the magnetic saturation phenomenon at the tooth tips is explained using the saturation leakage-flux equivalent magnetic circuit model (SLF-EMCM). It provides a different perspective for analysis. Third, a new structure of the trapezoidal PMs and tooth is proposed. It can reduce magnetic saturation at the tooth tips, further reduce cogging torque, and flux linkage harmonics. Additionally, a 3-D finite element analysis (3D-FEA) is conducted to verify the theoretical analysis and to assess the impact of different tooth and PM shapes on motor performance. The effects of trapezoidal tooth angle and air-gap length are also evaluated. Finally, a prototype is manufactured, and experiments are conducted. The experimental results demonstrate that the DSCP-TFM exhibits higher torque output and lower harmonics in the coil flux linkage than existing TFMs, thereby validating the design and analysis.]]></description>
      <pubDate>Thu, 06 Aug 2026 09:22:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2735085</guid>
    </item>
    <item>
      <title>Key Modeling Considerations for Reliable FEM-Based Demagnetization Evaluation of IPMSM</title>
      <link>https://trid.trb.org/View/2724711</link>
      <description><![CDATA[The reduction of heavy rare earth elements such as dysprosium and terbium, which are associated with high cost, geopolitical risk, and sustainability concerns, is a key objective in the electromagnetic design of interior permanent magnet synchronous machines (IPMSM) for traction applications. Since these elements are the primary contributors to magnet intrinsic coercivity, their minimization increases the risk of irreversible demagnetization of the permanent magnets. In IPMSM designs with reduced heavy rare earth content, it is therefore necessary to operate close to the demagnetization limit of the permanent magnets and accurately identify them. Consequently, a precise and reliable finite element method (FEM) based prediction of demagnetization robustness is essential for systematic and material efficient machine design. This paper investigates the key factors required for reliable assessment of demagnetization robustness in IPMSM using electromagnetic FEM. Unlike existing literature, which typically neglects the accuracy of magnet material data, evaluates only a single worst-case operating point, and relies predominantly on two-dimensional models, the presented analysis highlights the relevance of accurate magnet material characterization, multiple dynamic operating points, and three-dimensional effects. The impact of magnet material characterization is examined by comparing nominal and minimum material properties as well as open-circuit and closed-circuit measurement data, demonstrating the importance of capturing the knee point of the demagnetization curve. A sensitivity study further shows that small deviations in assumed recoil permeability can substantially affect predicted demagnetization behavior. Since demagnetization is not a binary phenomenon, different evaluation approaches are discussed, including demagnetized area thresholds and back-EMF loss. Relevant worst-case operating conditions are examined, considering maximum demagnetizing field, elevated magnet temperatures, and short circuit scenarios. Finally, the relevance of three-dimensional effects is demonstrated, showing that rotor step skew can significantly influence demagnetization behavior compared to two-dimensional models. The findings form the methodological basis for subsequent electromagnetic optimization and design studies of IPMSM with explicitly considered and enhanced demagnetization robustness.]]></description>
      <pubDate>Tue, 28 Jul 2026 12:27:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/2724711</guid>
    </item>
    <item>
      <title>Model-based fault detection for an electrohydraulic braking system with cooperative regenerative braking management</title>
      <link>https://trid.trb.org/View/2666867</link>
      <description><![CDATA[This paper presents a model-based fault detection method for an electrohydraulic braking system with cooperative regenerative braking management. The regenerative braking system can save energy and improve endurance in electric vehicles. However, failure of the regenerative system may result in the system being unable to fully convert the recovered energy into stored electrical energy, with a large portion of the energy being dissipated as heat. Meanwhile, the motor braking torque output is limited, and the range of battery state of charge is affected. In this paper, a Carsim/Simulink co-simulation was developed to model the operating conditions and failure modes of the regenerative braking system in an electric vehicle. A three-stage dynamic equation was derived to model the piston movement in the wheel cylinder of the electrohydraulic braking system. A vector control using coordinate transformation was developed for the permanent magnet synchronous motor to control the current and torque. Since various system components have been built, the advantage of model-based methods can perform predictive maintenance compared with the current corrective and preventive maintenance. Therefore, this paper proposed a three-layer systematic model (torque distribution layer, execution layer, and actuation layer) of electric vehicle regenerative braking system to detect and diagnose various fault conditions. Various parameters were compared with the normal braking mode in order to provide systematic guidance on fault detection.]]></description>
      <pubDate>Mon, 27 Jul 2026 09:46:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/2666867</guid>
    </item>
    <item>
      <title>Analytical Magnetic Circuit Modeling and Parameter Estimation of a PMSM for Spatial Harmonics and Radial Forces Characterization</title>
      <link>https://trid.trb.org/View/2717280</link>
      <description><![CDATA[This paper presents an analytical model for three-phase Permanent Magnet Synchronous Motors (PMSMs) based on Magnetic Equivalent Circuits (MECs). The approach combines a reduced magnetic network, formulated in the complex domain to simplify the mathematical development, with an offline parameter estimation procedure systematically applied for different harmonic orders. This enables the model to capture the spatial dependence of permeance variations and reproduce inductance and magnetic flux nonlinearities, while maintaining generality, physical interpretability, and computational efficiency. Numerical simulations are compared with Finite Element (FE) results to validate the model’s ability to predict current and torque harmonics and the resulting radial electromagnetic forces, demonstrating its suitability for fast Noise, Vibration, and Harshness (NVH) analysis and vibroacoustic optimization.]]></description>
      <pubDate>Tue, 30 Jun 2026 08:51:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717280</guid>
    </item>
    <item>
      <title>Intelligent Control of Automobile Spiral Bevel Gear Grinding Process Based on Force Feedback</title>
      <link>https://trid.trb.org/View/2706233</link>
      <description><![CDATA[To enhance the grinding quality of spiral bevel gears, an intelligent control model for the grinding process of automotive helical conical gears based on force feedback has been designed. This model outputs the control voltage for the machine tool's permanent magnet synchronous motor (PMSM), ensuring that the motor speed constantly tracks the desired value. By adjusting the grinding generating speed, the grinding force is controlled, and the tooth surface roughness is reduced. Firstly, the state equation of a permanent magnet synchronous AC servo motor is established. By employing the second method of Lyapunov, an RM adaptive control algorithm is developed. It is found that the model output can efficiently track the reference model (RM) and adjust to variations in torque due to load. To further enhance the controller, a generalized regression neural network (GRNN) was developed; subsequently, training data were generated using the output voltage of the RM self-adjusting controller to achieve velocity regulation of the machine tool's servo motor. Finally, the results indicate that the GRNN controller is superior. It uses RM self-adjusting control data as samples for regression analysis, outputs control signals, and controls the angular velocities of each axis of the machine tool to control the grinding force within a reasonable threshold range, reducing the complexity of the controller and achieving lightweight. At the same time, the feasibility of the controller has been experimentally verified. This improves the roughness of the tooth surface during the grinding of spiral bevel gears and enhances the quality of vehicle operation.]]></description>
      <pubDate>Mon, 22 Jun 2026 07:29:01 GMT</pubDate>
      <guid>https://trid.trb.org/View/2706233</guid>
    </item>
    <item>
      <title>Development of Next Generation Sustainable Electric Traction Motors</title>
      <link>https://trid.trb.org/View/2581599</link>
      <description><![CDATA[The development of traction motors with easily recyclable rare-earth permanent magnets (PMs) is studied. The primary objective is to find means and technologies that enable the reuse of the PMs without extracting their elements. Both the motor design and PM assembly need to be aligned with this target. Especially, we are focusing on metallic encapsulation of the PMs to make them strong enough to tolerate the disassembly forces. First, we discuss the design, addressing the positioning of the encapsulated PMs to balance between the mechanical and electromagnetic requirements. Second, we present the first results on the encapsulation of the PMs for intact disassembly, elaborating on the materials, manufacturing via direct energy deposition, and visual inspection of the results. We aim to contribute to the emergence of the next generation less rare-earth-element-dependent, compact, and energy-efficient electric traction motors.]]></description>
      <pubDate>Thu, 18 Jun 2026 08:54:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2581599</guid>
    </item>
    <item>
      <title>High-Precision Nonlinear Semi-Analytical Model of High Torque Density 3-D Magnetic Circuit Permanent Magnet Motor in Aircraft Electric Propulsion Application</title>
      <link>https://trid.trb.org/View/2665607</link>
      <description><![CDATA[This article proposes a novel high-precision nonlinear semi-analytical model for the magnetic fields and the electromagnetic performance calculation of 3-D magnetic circuit permanent magnet motor (3DMCPMM) in aircraft electric propulsion applications, which can take the effects of the magnetic saturation nonlinearity and the permanent magnet (PM) end-leakage flux into account. The high torque density 3DMCPMM topology is first proposed, which can improve the output torque per unit weight via the 3-D magnetic circuit coupling. To simplify the computation, the 3-D magnetic circuit equivalent decoupling method is proposed for 3DMCPMM, which can convert the 3-D magnetic circuit into dual 2-D magnetic circuits. The 3DMCPMM analytic model is then proposed based on the harmonic subdomain approach, which can accurately predict the magnetic field distribution and the electromagnetic performance. Furthermore, using the equivalent magnetic circuit (EMC) model, the PM end leakage flux coefficient is proposed for the 3DMCPMM analytic model, which can eliminate the calculation error due to the PM end-leakage flux effect. The nonlinear iteration-based magnetic permeability is proposed for the 3DMCPMM analytic model, which can improve the analytic calculation accuracy by considering the magnetic saturation nonlinearity. A 630-N ⋅ m 3DMCPMM is designed and manufactured with the torque density of 25.37 N ⋅ m/kg. Simulation and experimental results show that the proposed semi-analytic model has an excellent electromagnetic prediction performance with a maximum calculation error of 4.62%, which can achieve the analytic calculation of 3-D magnetic circuit motor. The 3DMCPMM semi-analytical model is proposed for the first time, which lays the foundation for the 3DMCPMM rapid design and iterative optimization.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:13:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665607</guid>
    </item>
    <item>
      <title>Magnet Arrangement Design and Comprehensive Analysis of a Split-Tooth Permanent Magnet Arc Motor Based on Poynting Theory</title>
      <link>https://trid.trb.org/View/2665589</link>
      <description><![CDATA[This article proposes a new split-tooth permanent magnet (PM) arc motor with dual PM excitation. The property of the slot-PMs allows the motor to have good overload capacity, while the flux-reversal PMs can compensate for the torque in slot-PM motors under light load. This PM combination ensures that the proposed motors have high torque under different load conditions. Two different magnet arrangements with different rotor poles are investigated through flux harmonic analysis to obtain higher output torque. Two optimal motor types are selected and compared with two benchmark motors that only have flux-reversal PMs. In order to analyze the torque components of the four motors, a Poynting theory-based torque calculation method is proposed, and a more detailed derivation is carried out. After optimization and comprehensive torque performance comparison, the proposed motor with five rotor poles in a single motor unit is manufactured and tested. The finite element and experimental results validate the superiority of the proposed motor.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:13:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665589</guid>
    </item>
    <item>
      <title>Optimized Slot Design of PMVM Aiming for Reduced Back EMF Total Harmonic Distortion</title>
      <link>https://trid.trb.org/View/2665572</link>
      <description><![CDATA[Permanent magnet vernier machine (PMVM) are known for high torque density enabled by magnetic field modulation, making them suitable for electric vehicle (EV) applications. However, harmonics in the back electromotive force (EMF) have been shown to degrade torque quality and increase the peak-to-peak torque ripple. In this study, the back EMF of PMVM is analyzed to achieve low total harmonic distortion (THD). The operating principle is examined, and the relationship between the fundamental and harmonic components is derived. The conflict between fundamental enhancement and harmonic suppression is revealed, requiring a trade-off design strategy. Reduced slot opening is found to increase the slot-opening factor, which in turn amplifies both fundamental and high-order harmonics. To address this, a new topology is adopted capable of suppressing high-order harmonics while maintaining high fundamental component. Magnetic field modulator with an inverted trapezoidal slot and a multidegree-of-freedom tooth structure is proposed. With appropriate topology selection, the fundamental can be enhanced while harmonics are minimized, reducing back EMF THD. The effectiveness of the proposed method is validated through experiments on two prototypes.]]></description>
      <pubDate>Wed, 10 Jun 2026 13:40:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665572</guid>
    </item>
    <item>
      <title>Tradeoff Between Radial Force and Tangential Force for Multiphase Permanent Magnet Machines With Harmonic Current Injection</title>
      <link>https://trid.trb.org/View/2665566</link>
      <description><![CDATA[Harmonic currents are commonly employed in multiphase permanent magnet (PM) machines to enhance the output torque, which essentially improves the tangential force. However, as the radial force (RF) is also affected by the harmonic currents, high noise and vibration may be induced. This article systematically investigates the dual impacts of harmonic currents on both radial and tangential force characteristics. Analytical derivations reveal that armature-induced RFs correlate with current phase, enabling antiphase compensation between current-induced and inherent RFs to suppress vibrations. However, the optimal phase angles for vibration minimization and torque maximization are inherently mismatched. A detailed parametric analysis is performed through finite element simulations on a five-phase PM machine with a ten-slot/eight-pole configuration, employing third-harmonic current injection with varying amplitudes. The amplitude–phase relationships of both tangential and RF components are quantitatively examined. Results demonstrate the fundamental compromise between torque improvement and vibration reduction in current injection strategies. Experimental validation is subsequently conducted through prototype testing, with measured vibration acceleration and output torque data confirming the analytical findings.]]></description>
      <pubDate>Tue, 09 Jun 2026 14:43:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665566</guid>
    </item>
    <item>
      <title>No-Load Analytical Model of STPM Motor With Asymmetric Modular Rotor Under Mixed Eccentricity for In-Wheel Traction Applications</title>
      <link>https://trid.trb.org/View/2665564</link>
      <description><![CDATA[To reduce the usage of rare-earth permanent magnet (PM), this article proposes a novel asymmetric modular rotor spoke-type PM (MR-STPM) motor for in-wheel lightweight traction applications. The analytical model is established to investigate the operation principle and the no-load performance of this type of motor. First, the evolution process of the geometric topology of the STPM motor is introduced. Then, the analytical models of cogging torque and open-circuit back-electromotive force (back EMF) for symmetric/asymmetric MR-STPM motors are developed based on the general airgap field modulation theory (AFMT). Furthermore, the effect of mixed eccentricity (ME) on the aforementioned performances, attributable to manufacturing tolerances, is also investigated. With the help of analytical models and finite element analysis (FEA), the harmonic behaviors are revealed comprehensively. Finally, a prototype motor is manufactured and tested, and the measured results have a good agreement with the analytical models and FEA predicted results.]]></description>
      <pubDate>Tue, 09 Jun 2026 14:43:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665564</guid>
    </item>
    <item>
      <title>Optimization of Amorphous Alloy Axial-Modular Flux-Switching Permanent Magnet Machine Considering Edge Degradation Uncertainty</title>
      <link>https://trid.trb.org/View/2665544</link>
      <description><![CDATA[This article proposes a multiobjective optimization considering edge degradation uncertainty design methodology for amorphous alloy axial-modular flux-switching permanent magnet (AM-FSPM) machines. To eliminate the uncertainty effects associated with edge degradation, the harmonic distributions of the air-gap magnetic field are deduced with an effect factor for edge degradation. Based on the stochastic characteristics of edge degradation, an optimization function considering edge degradation uncertainty is established and optimized with the standard deviations of torque and torque ripple as the objective functions. Then, a comparison between the optimization design considering edge degradation uncertainty and the optimization design only considering edge degradation shows that the proposed method effectively mitigates the impact of edge degradation uncertainty. Finally, a prototype is manufactured and tested to further validate the effectiveness of the proposed approach.]]></description>
      <pubDate>Fri, 05 Jun 2026 16:41:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665544</guid>
    </item>
    <item>
      <title>A Novel Compound Fast Nonsingular Terminal Sliding Mode Disturbance Rejection Control for Multiunit Distributed Permanent Magnet Arc Motor</title>
      <link>https://trid.trb.org/View/2665535</link>
      <description><![CDATA[This article proposes a novel compound fast nonsingular terminal sliding mode disturbance rejection control strategy for permanent magnet arc motors (PMAMs), which simultaneously enhances speed tracking accuracy and disturbance rejection performance. The primary contribution of this study lies in the development of a multilayer fast nonsingular terminal sliding mode controller (MFNTSMC) that effectively addresses the slow convergence issues associated with conventional terminal sliding mode control (SMC) when it is far from the equilibrium point, and eliminates chattering through the introduction of innovative multilayer terminal attraction factors. The proposed MFNTSMC guarantees finite-time convergence of the speed tracking error, regardless of initial conditions. In addition, in order to combat high-frequency nonlinear unmodeled disturbances inherent in PMAMs, which are caused by high pole-pair configurations and end effects induced by segmented structures, a novel high-order global fast-convergent nonlinear disturbance observer (HGFNDO) is integrated with MFNTSMC for accurate lumped disturbance estimation. The main innovation is the novel switching mechanism incorporated into both the controller and the observer, which significantly enhances convergence speed and can be extended to any order without imposing a substantial computational burden. The closed-loop stability of the system is rigorously proven using the Lyapunov theory. Experimental results verify the effectiveness and superiority of the proposed strategy.]]></description>
      <pubDate>Thu, 04 Jun 2026 11:57:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665535</guid>
    </item>
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