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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" />
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    <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>
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    <item>
      <title>Investigation of Spline-Induced Excitation Forces in Electric Drive Units via Flexible Multibody Dynamic Simulation</title>
      <link>https://trid.trb.org/View/2717286</link>
      <description><![CDATA[This study investigates the noise, vibration, and harshness (NVH) characteristics of the spline coupling that connects the motor and reducer shafts in an electric drive unit, using flexible multibody dynamics simulations. Focusing on the source stage of the NVH analysis process, the excitation force magnitude and spline trajectory are examined under various spline design conditions. The study compares spline fit types (side fit vs. major fit), clearance vs. interference conditions, and variations in tooth number and module size. This study analyzes the overall behavior of spline excitation forces under various design conditions, complementing prior research focused mainly on specific causes or manufacturing improvements. Side fit splines exhibit lower first-order excitation forces compared to major fit splines, but significantly higher excitation forces at higher orders. This leads to increased spline trajectory amplitude and amplified whirling of the input shaft. Since the input gear is directly coupled to the input shaft, this whirling behavior increases the gear center-distance variation, which in turn amplifies the cumulative pitch error. In particular, clearance fit conditions result in greater higher-order excitation forces and gear eccentricity than interference fits. Major fit splines, on the other hand, show more stable trajectories and lower higher-order excitation forces, minimizing their impact on the overall system. The analysis of tooth number variation reveals that increasing the number of teeth reduces first-order excitation forces while increasing higher-order components, indicating that force distribution within the spline can be tuned. Tooth number adjustment does not affect the rest of the system, suggesting it is a practical strategy for achieving desired NVH characteristics. In conclusion, spline design parameters such as fit type and tooth number significantly influence the magnitude and directional behavior of excitation force, leading to system-level phenomena.]]></description>
      <pubDate>Tue, 30 Jun 2026 17:02:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717286</guid>
    </item>
    <item>
      <title>Railway Train Main Power Converter:
Model Predictive Current Control of a
Modular Multilevel Converter</title>
      <link>https://trid.trb.org/View/2671076</link>
      <description><![CDATA[In electric railway trains two main power systems can be distinguished: The system of the power propulsion and the system of the auxiliary power services. Consequently, since the train is supplied from the catenary in AC, the use of an AC to DC power converter is indispensable. This paper proposes the application of a modular multilevel converter (MMC) as main power converter (i.e., interfacing the AC catenary and the DC link inside the train). The operation of the MMC is ensured by a model predictive current controller, which controls its input AC current according to specific power requirements. The MMC and the model predictive current control are validated recurring to computer simulations. Based on the developed simulation models, the presented results permit to verify the advantages associated with the modularity of the converter and with the performance of the model predictive current control.]]></description>
      <pubDate>Tue, 30 Jun 2026 09:45:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/2671076</guid>
    </item>
    <item>
      <title>Different Facets of Artificial Intelligence-Based Predictive Maintenance for Electric Powertrains</title>
      <link>https://trid.trb.org/View/2670983</link>
      <description><![CDATA[Maintenance, traditionally perceived as a reactive cost and a hindrance, poses challenges to efficiency when components succumb to unforeseen breakdowns. In addition to the financial implications, the repair process also incurs substantial time wastage. To overcome these obstacles and achieve enhanced efficiency and cost savings within the manufacturing sector, this paper presents a conceptual study of a technologically advanced predictive maintenance (PdM) approach, particularly in the realm of artificial intelligence-powered digital twins. The effectiveness of these solutions hinges on their data-driven nature, technical feasibility, and acceptance by industry stakeholders.]]></description>
      <pubDate>Tue, 30 Jun 2026 09:45:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2670983</guid>
    </item>
    <item>
      <title>The Evolution of Power Unit Development Process through MBD (sixth Report)</title>
      <link>https://trid.trb.org/View/2684160</link>
      <description><![CDATA[To achieve a carbon-neutral society, improving hybrid vehicle fuel efficiency is essential. This study developed a 1D thermal model enabling thermal flow design of the drive unit based on vehicle system performance. The model accurately simulates internal heat behavior and supports design guidelines aligned with overall vehicle performance. Using this model, specifications were designed and validated through hybrid unit testing, confirming predicted fuel efficiency. This approach offers a new method for fuel efficiency improvement starting from thermal design and is expected to be effective in future electrified vehicle development.]]></description>
      <pubDate>Wed, 24 Jun 2026 13:28:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2684160</guid>
    </item>
    <item>
      <title>A novel electric drive description to bridge the gap between energetic and equivalent-circuit models</title>
      <link>https://trid.trb.org/View/2680772</link>
      <description><![CDATA[A novel electric drive modeling approach is introduced to bridge the gap between computationally efficient energetic methods and highly detailed equivalent-circuit models. Unlike existing energetic models, which lack the granularity to capture motor currents and voltages, or equivalent-circuit models, which are computationally expensive, the proposed methodology achieves a balance of accuracy and efficiency. This is accomplished by combining an equivalent-circuit motor description with a phenomenological inverter model, supported by stator current reference lookup tables and a torque saturation process. These innovations enable accurate simulations with minimal input data requirements, making the model well-suited for electric vehicle early-stage design. Validation against experimental data from a Tesla Model 3 demonstrates the effectiveness of this approach for both single-motor and multiple-motor electric vehicle architectures.]]></description>
      <pubDate>Wed, 24 Jun 2026 11:29:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2680772</guid>
    </item>
    <item>
      <title>High Performance Inverter for Electric Vehicle with Newly Developed Double-sided Cooling Power Module</title>
      <link>https://trid.trb.org/View/2684146</link>
      <description><![CDATA[This paper describes the specifications of the newly developed inverter system, as well as the features and effects of the technologies employed. New technologies such as a double-sided cooling power module utilizing thermosetting thermal interface material, a split-arrangement DC bus capacitor, a 3-in-1 structure - where the inverter shares its housing with the motor and reducer - have been implemented to enhance current performance and reduce losses without increasing the mass, compared to the previous model.]]></description>
      <pubDate>Tue, 23 Jun 2026 13:53:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2684146</guid>
    </item>
    <item>
      <title>Hybridized Diesel Powertrains - An Important Enabler for Commercial Applications on the Long Journey towards Full Electrification</title>
      <link>https://trid.trb.org/View/2717227</link>
      <description><![CDATA[The ongoing efforts for reduction of the traffic-related greenhouse gas emissions and, at the same time, the mitigation of harmful pollutant emissions from vehicle exhaust emissions are important development tasks for the entire automotive industry worldwide according to demand to provide clean and efficient products. Further tightened fleet average FE standards and ultra-low limits for exhaust emissions require the continuous development of new propulsion system types. Due to the given reluctance of the end customer and corresponding low acceptance of fully electrified vehicles, especially in the commercial vehicle segment, new and innovative topologies are needed to meet regulatory requirements and maintain the high versatility of today’s dominating solutions. For further optimization of operating conditions with enhanced fuel efficiency, the technical strategy is also determined by uplifting the attractiveness of electric driving incl. the avoidance of areas with poor ICE efficiency and as well as the coverage of emission-critical operations by electric propulsion. In this context, the support provided by an electric drive on board the vehicle in a combined drive system is becoming increasingly important. This article discusses accordingly various platform strategies for hybridized Diesel powertrains in different sectors of commercial vehicle applications and delivers a comprehensive comparative analysis of different hybrid drive concepts. Specifically, several hybrid powertrain configurations that extend an electric drive platform (hybridized BEVs), such as series and parallel-series topologies, are compared with traditional parallel hybrid powertrain topologies based on internal combustion engines (ICE). The study focuses mainly on two different cornerstone applications: a large light commercial vehicle, ranging from 3,5 to 6,5 to. and a heavy-duty long-haul truck with 40…44 to. gross vehicle weight. It evaluates the advantages in terms of CO2 emissions and Diesel fuel savings and investigates the effects on emission controls aspects. In addition to technical comparisons, the paper addresses also regulatory demands and end customer merits, assessing the integrational effort and commonalities in components with pure ICE and battery electric topologies. Furthermore, it explores the additional impact of advanced operational strategies for Hybrid Diesel powertrains, incorporating insights from innovative observations from executed hybrid technology demonstrator vehicles.]]></description>
      <pubDate>Tue, 23 Jun 2026 10:34:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717227</guid>
    </item>
    <item>
      <title>Vibroacoustic Analysis and Optimisation of an Electric Refrigerant Scroll Compressor</title>
      <link>https://trid.trb.org/View/2717325</link>
      <description><![CDATA[In electrified vehicles, auxiliary components can represent a dominant source of noise, one of which is the refrigerant scroll compressor. Compared with vehicles equipped with internal combustion engines, electrified vehicles require larger refrigerant compressors, as thermal management is needed not only for the passenger compartment but also for the battery and electric drive components. Excitation mechanisms within the compressor, arising from the cyclic compression process and the eccentric motion of the scroll, induce housing vibrations and result in airborne sound radiation. To investigate the vibroacoustic noise generation mechanisms of a scroll compressor, operational vibrations were analysed using accelerometers and three-dimensional laser scanning vibrometry. In addition, the radiated sound was characterised using microphones and near-field sound intensity measurements. The results demonstrate a strong correlation between surface vibrations and airborne sound radiation, with the vibroacoustic behaviour being dominated by speed-dependent tonal components. Pronounced vibration and sound radiation levels occur when excitation orders coincide with rigid-body modes of the mounting system or structural eigenmodes of the compressor housing. Based on these findings, a constrained-layer damping treatment was applied to selected, highly sound-radiating regions of the compressor housing. Although the overall reduction in sound power was limited due to the high stiffness and predominantly rigid-body behaviour of the housing, local vibration and sound radiation reductions were achieved for structurally flexible components, resulting in a perceptible improvement in subjective sound quality. These results highlight the importance of spatially resolved vibroacoustic analysis for understanding noise generation mechanisms and for guiding targeted optimisation measures for refrigerant compressors.]]></description>
      <pubDate>Tue, 23 Jun 2026 10:30:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717325</guid>
    </item>
    <item>
      <title>High-Fidelity NVH Analysis Model Development Process for EV Traction Motors Based on Experimental Correlation</title>
      <link>https://trid.trb.org/View/2717307</link>
      <description><![CDATA[This study presents a high-fidelity NVH (Noise, Vibration, Harshness) analysis model development process for EV traction motors. The proposed process consists of two main components: Path advancement through structural stiffness tuning, and Source advancement, focused on the motor’s excitation mechanisms. Model accuracy was validated through comparison of simulation results with dyno experiment data, with particular focus on the 24th-order electromagnetic vibration observed in an 8-pole, 48-slot motor. Path advancement was achieved through modal correlation between experimental results and finite element (FE) analysis. Nine modal experiment and simulation stages were conducted, ranging from individual components to the complete motor assembly. Mode shapes were compared using the Modal Assurance Criterion (MAC), and natural frequencies were matched within a 5% error margin by adjusting FE material properties. For the 24th-order electromagnetic vibration, simulation results agreed with experiment data within a 7% error margin for natural frequency. However, notable discrepancies remained in vibration amplitude. To resolve these discrepancies, Source advancement was performed. The initial excitation source was derived from idealized electromagnetic analysis, considering radial and tangential force as well as torque ripple. However, rotor eccentricity caused by mechanical assembly tolerances is commonly observed in actual motors. Therefore, the advanced source accounted for rotor–stator eccentricity in the electromagnetic analysis. As a result, the NVH simulation incorporating the advanced source matched the vibration amplitude within a 1% error margin compared to experimental results. The proposed NVH model development process enables more accurate vibration prediction in the early design phase of electric drive motors and is expected to significantly improve NVH performance in future electric drive systems.]]></description>
      <pubDate>Tue, 23 Jun 2026 10:30:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717307</guid>
    </item>
    <item>
      <title>Rib Design of Electric Drive Unit Housings for Reduced Noise Radiation</title>
      <link>https://trid.trb.org/View/2717305</link>
      <description><![CDATA[Although propulsion noise often constitutes a minority of the overall noise in electric vehicles, it remains an important quality indicator due to its high-frequency tonal character, which is undesirable even at low levels.There are many factors that influence the interior car levels of propulsion noise, i.e. gear whine and electric motor whine. The primary ones to consider are the electric drive units (EDU) internal forces, but also secondary properties such as EDU housing design and encapsulation, vehicle sound pack and mount isolation play important roles.This work focuses on EDU housing design and more particularly on the housing ribs that enables attachment point stiffness and housing strength, but which can also cause problems in terms of noise radiation. Numerical parameter studies on geometrical properties such as length dimensions, thickness and curvature were performed on single ribs of different types. For each design iteration, the key performance indicators radiated sound power, squared velocity and radiation efficiency were studied.The outcome of this work provides insights into which characteristics of ribs that are central for radiated noise. For instance, it was proven that a rather small curvature of the outer edge of a rib can decrease the radiated noise but also that certain rib dimensions can result in extensive noise due to the interaction of the first bending mode with the peak in radiation efficiency.]]></description>
      <pubDate>Tue, 23 Jun 2026 10:30:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717305</guid>
    </item>
    <item>
      <title>Methodology Development for Electric Drive Module Vibro-Acoustic Assessment Using Simulation Measurement Comparison and Root Cause Analysis</title>
      <link>https://trid.trb.org/View/2717288</link>
      <description><![CDATA[The virtual development of Electric Drive Modules (EDMs) for Battery Electric Vehicles (BEVs) requires proven and predictive methodologies. One part of the development investigates the vibro-acoustic assessment for the low- and high-frequency ranges within the targeted operating range. The efficient use of such a methodology requires an understanding of the accuracy and validity of the achievable results, as well as the derivation of suitable improvement measures for goals that have not been achieved. The use of reference data from experimental investigations and a detailed root cause analysis (RCA), to directly link a specific response and behavior to the excitations, modal content, and transfer functions, is an essential and non-trivial part of the methodology development.This paper describes the development of such a methodology using the example of a new EDM virtual model for Noise, Vibration and Harshness (NVH) analysis, including the simulation approach, validation, and evaluation procedure. It discusses how RCA can be applied to different observed phenomena in EDM NVH behavior and detected deviations between the initial model and the measurements, the main influencing parameters, and the identified improvement potential for simulation models.]]></description>
      <pubDate>Tue, 23 Jun 2026 10:30:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717288</guid>
    </item>
    <item>
      <title>Influence of Common-Mode Voltage Reduction Techniques on High-Frequency Sideband Vibrations in IPMSM Drives for EVs</title>
      <link>https://trid.trb.org/View/2717284</link>
      <description><![CDATA[Space vector pulse width modulation (SVPWM) induces common-mode voltage (CMV) in three-phase voltage-source inverters, producing steep voltage edges that can lead to high leakage currents. In electric drive applications, these currents accelerate motor bearing degradation and may cause winding insulation failure. Active-zero-state PWM (AZSPWM) and near-state PWM (NSPWM) have been proposed as alternative modulation strategies to mitigate CMV and reduce drive degradation. This paper investigates the noise, vibration, and harshness performance of AZSPWM and NSPWM in comparison with conventional SVPWM. The proposed CMV reduction schemes are evaluated in terms of both CMV mitigation and their impact on high-frequency sideband vibration harmonics. Experimental results demonstrate that the CMV reduction strategies are highly effective in lowering CMV levels relative to SVPWM; however, this benefit is accompanied by an increase in vibration levels, which may adversely affect the mechanical integrity of the drive system despite the reduction in bearing leakage currents.]]></description>
      <pubDate>Tue, 23 Jun 2026 10:30:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717284</guid>
    </item>
    <item>
      <title>Best-in-Class NVH Optimisation for Electric Powertrains, Holistic Front-Loading Approaches</title>
      <link>https://trid.trb.org/View/2717282</link>
      <description><![CDATA[Achieving best-in-class Noise, Vibration, and Harshness (NVH) in electric powertrains demands a paradigm shift in development methodology. This paper presents a practice-oriented overview of simulation methods in NVH development methodology for electric drive units. This includes target cascading and multi-objective optimisation, and by attacking NVH at the source using KPIs early in the design cycle, significant reductions in development time and reliance on traditional testbed loops are realised. Machine learning (Neural Network) algorithms are utilized to find the best-in-class design, using multi-objective optimisation as well as refining simulation accuracy by adding tolerance effects while target cascading ensures alignment of system-level performance objectives down to subsystem contributions. Combined, these strategies enable rapid and robust NVH optimisation, using simulation for next-generation electric powertrain development. Several applications and real-life examples demonstrate how simulation helped with NVH issue identification or improvement.]]></description>
      <pubDate>Tue, 23 Jun 2026 10:30:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717282</guid>
    </item>
    <item>
      <title>Energy Efficiency Improvement Framework for Regenerative Braking System in Electric Vehicles</title>
      <link>https://trid.trb.org/View/2665608</link>
      <description><![CDATA[Electric vehicles (EVs) face challenges in enhancing regenerative braking (RB) efficiency, particularly at low speeds, where the traction motor’s back-electromotive force is insufficient for energy regeneration. Below a certain dynamic low-speed threshold, energy is extracted from the battery instead of being returned, exacerbating electrical losses in the drive. A model-based approach is proposed to analytically determine this dynamic low-speed threshold, alongside a loss minimization framework based on a variable flux approach to enhance energy recovery. The simulation results using a vector-controlled induction motor (IM) drive indicate a significant reduction in total system losses during braking in the high-speed, low-torque region. The loss reduction effectively lowers the low-speed threshold by 5%, depending on the specific driving conditions, for the considered target vehicle’s drive system. However, the optimal flux point varies depending on machine parameters. Hence, the effect of temperature-induced variations in stator and rotor resistances and magnetic saturation on loss minimization is also explored, showing that optimal flux point sensitivity is particularly impacted by resistance changes. The experimental validation on representative drive cycles corroborates the simulation results, showing a 13% reduction in system losses under the modified Indian driving cycle and 7% under the U.S. EPA highway cycle.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:13:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665608</guid>
    </item>
    <item>
      <title>An Energy-Efficient Torque Optimization Strategy With Field Weakening for a State Feedback Controller With Synchronous Reluctance Motor Drive</title>
      <link>https://trid.trb.org/View/2665596</link>
      <description><![CDATA[A trend for developing synchronous reluctance motors (SynRMs)-based drive systems is observed in the industry due to their simple and robust construction, with no rare Earth elements (REEs). These machines offer high efficiency and are based on easily available materials. Designing an energy-efficient control strategy is nontrivial because of the magnetic saturation phenomenon in the iron-based rotor. Outstanding dynamic drive performance can be achieved by applying a constrained full-state feedback controller (SFC). However, this structure cannot employ classical torque maximization strategies, leading to poor efficiency. Thus, a customized torque maximization strategy has to be designed for SFC-based angular velocity control systems to enable energy-efficient operation. An original torque maximization strategy for a SynRM drive is proposed for the SFC structure. Maximum torque operation is ensured by applying a customized torque maximization unit (TMU) with maximum torque per ampere (MTPA) and field weakening (FW) operation. MTPA is based on a precalculated trajectory using the machine’s model, implemented using an offline-trained artificial neural network; meanwhile, FW is based on a machine parameter-free approach with current phase shifting (CPS). The robustness of the CPS was analytically confirmed based on a small-signal analysis. The experimental results obtained confirm energy-efficient and stable operation of the system for both the MTPA and the FW operations. The proposed SFC-TMU structure is compared to a state-of-the-art lookup table (LUT)-based field-oriented control (FOC) cascade control structure (CCS). The given torque maximization trajectory is properly tracked and reveals superior efficiency, outperforming a classical LUT-based FOC-CCS strategy.]]></description>
      <pubDate>Wed, 17 Jun 2026 16:13:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2665596</guid>
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