Browse Topic: Electric motors

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Research on the Control of Magnetic Weakening Scheme for the Voltage Utilization Rate of Hybrid Transmission2026-01-5049To be published on 07/31/2026
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.
Jing, Junchao, Zhang, Junzhi, Yan, Xiaoqian, Liu, Yiqiang, Sun, Fengjiao, Dai, Zhengxing
Study on the Electromechanical Coupling Torsional Vibration Characteristics of Electric Drive Transmission Systems under Motor Harmonic Excitation2026-99-0229To be published on 07/31/2026
Considering the spatial harmonic and time harmonic excitation of the permanent magnet synchronous motor, and the dynamic meshing excitation of gear pairs, this paper constructs one electromechanical coupling torsional vibration model. The torsional vibration characteristics of the electric drive transmission system in pure electric vehicles are investigated. Key electromechanical parameters are obtained by numerical calculations, and the electromechanical coupling system model is solved using the Runge-Kutta method. Finally, the system dynamic response characteristics at rated speed of 3000 r/min are analyzed. The results indicate that the significant bidirectional coupling exists between the electromagnetic excitation of the motor and the mechanical excitation of the gear transmission system. The current spectrum contains fundamental and harmonic components, along with components of gear meshing frequencies and their modulated sideband characteristics relative to the electrical frequency. The electromagnetic torque spectrum exhibits components of gear meshing frequencies, and gear angular velocity fluctuations are influenced by motor harmonic excitation. Under multi-source excitation, this study reveals the frequency modulation mechanism of torsional vibrations in electromechanical coupling drive systems, providing a theoretical basis for vibration and noise suppression.
Luo, Yaou, Zhao, Kaihua, Fu, Shengping
Development and Technical Verification of A Lunar Dust Environment Simulation Mechanism2026-99-0175To be published on 07/31/2026
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Xu, Menglong, Lv, Shizeng, Li, Guohua, Gong, Jie
Design and Optimization of Hollow Rotating Traveling Wave Ultrasonic Motor Based on Laser Beam Expander2026-99-0154To be published on 07/31/2026
To meet the critical need for rapid response and miniaturization in laser beam expander drive systems, this study proposes an innovative actuation solution based on a hollow rotary traveling-wave ultrasonic motor. By thoroughly analyzing the optical adjustment mechanism of laser beam expanders and the electromechanical coupling behavior of ultrasonic motors, the motor structure was systematically optimized. Using a multiphysics coupling approach, the performance of stators fabricated from three distinct materials was compared, and parametric optimization was conducted. Experimental verification confirms that the developed ultrasonic motor precisely matches the load characteristics of beam-expanding optics while fulfilling the stringent requirements for both fast response and compact design. This research provides a reference for the miniaturization drive of high-precision optical systems, with promising applications in space optics and precision instrumentation.
Qiu, Haihui, Niu, Chuanhu, Xiao, Zhong, Xu, Zhangfan, Li, Jialiang, Pan, Song
Research and Development of Wheelchair Assisted Intelligent Boarding and Landing Device for Barrier-Free Bus Based on TRIZ Theory2026-99-0147To be published on 07/31/2026
With the intensifying global trend of population aging, enhancing public-transport accessibility for seniors and people with disabilities has become critical. Current wheelchair-assist boarding devices on low-floor buses suffer from cumbersome operation, excessive space occupation, poor adaptation to varying curb heights, and an inability to modulate power output dynamically, all of which compromise travel convenience. This study applies TRIZ theory to solve these problems. Functional analysis, causal-chain analysis, and the nine-screen method were used to identify key issues: excessive space use, insufficient dynamic power adjustment, poor curb-height adaptability, and the lack of self-service capability. TRIZ tools— including the contradiction matrix, substance-field models, and the Ideal Final Result (IFR)—generated conceptual solutions such as a foldable ramp, an adaptive tilting mechanism, an intelligent power-assist system, and an automatic extension device. The resulting integrated unit employs a planetary-gear train combined with a four-bar linkage for compact folding, a servo motor with torque-limiting springs for adaptive height adjustment, torque sensors for real-time power modulation, and a scissor-type telescoping mechanism for automatic stowage. Experimental validation through 50 trials showed that the device completes extension/folding in 7 s, achieves angle adjustment within 3.5 s, covers a pitch range of 0°–43°, and attains a 100 % extension success rate. These features significantly increase automation, adaptability, and user independence, thereby improving the quality of accessible bus services.
Zhu, Zongchuang, Hu, Zhiyong, Liu, Zeshuo, Liu, Yijia, Zhang, Ziqian
Research on Integrated Design and Optimization Method of High Speed Shuttle UUV Rudder and Propeller2026-99-08647/30/2026
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Wei, Jiaguang, Feng, Xiaowei, Zhao, Fuchen, Wang, Xingke, Xu, Shanzhi, He, Wenxuan
Fuel Savings from Predictive Charge Control Based on Short-Trip Duration in Series Hybrid Electric Vehicles14-15-03-00157/10/2026
Series hybrid electric vehicles (HEVs) employ an electric motor for propulsion, while the internal combustion engine operates solely as a generator under energy-efficient speed and load conditions. Owing to this architecture, series HEVs can achieve high fuel efficiency with a relatively simple control structure. However, conventional energy management systems (EMSs) often prioritize battery state-of-charge (SOC) stabilization, which can lead to frequent engine start–stop operations and unnecessary fuel consumption, particularly in short-trip driving. This study aims to enhance energy management performance in series HEVs by optimizing engine power generation timing based on predicted short-trip duration. A computationally efficient, rule-based prediction model is developed using real-world driving data, in which short-trip duration is estimated from vehicle speed and acceleration. Due to its low computational load, the proposed model is suitable for implementation in an onboard electronic control unit (ECU). The proposed control strategy initiates engine power generation when the battery SOC is low and the predicted trip duration is long, and suppresses generation when the SOC is sufficiently high or the predicted trip is short. A detailed vehicle model incorporating an engine, generator, electric motor, inverter, and battery is developed in Modelica to evaluate the proposed strategy. Simulation results demonstrate that the proposed EMS significantly reduces the frequency of engine start–stop events, leading to fuel economy improvements of 3.6% under the WLTC (excluding the extra-high phase) and 13.4% in a real-world urban–rural driving cycle, compared with a commercialized baseline vehicle. These results confirm the effectiveness and practical applicability of the proposed EMS for passenger vehicle applications.
Mizushima, Norifumi, Sato, Akira, Kuboyama, Tatsuya, Moriyoshi, Yasuo
A Multiphysics Approach to Mitigate Pulse-Width-Modulation-Induced Acoustic Noise in Permanent Magnet Synchronous Motor Drives for Electric Vehicles14-15-03-00147/3/2026
This article investigates high-frequency noise in permanent magnet synchronous motors (PMSMs) for electric vehicles, originating from pulse width modulation (PWM). A theoretical model is developed to formulate the phase voltage under space vector PWM (SVPWM), explicitly accounting for the additional harmonic components generated by the discrete-time voltage update in digital control systems. This derived voltage waveform serves as the excitation source in an electromagnetic finite-element model, from which the PWM current harmonics and their resulting high-frequency electromagnetic forces are computed. Critical components of the electromagnetic force are then extracted through two-dimensional Fourier transform. A structural model of the motor, incorporating practical assembly constraints, is established and validated by experimental modal tests on a fully assembled motor unit. To enable rapid noise prediction over the wide speed range, vibro-acoustic transfer functions are introduced. The predicted noise shows good agreement with experimental data. Leveraging this multiphysics model, the influence of switching frequency on noise characteristics is analyzed. The study identifies that avoiding excitation of the motor’s zero-order mode is critical for noise suppression. Accordingly, an optimal frequency-hopping strategy is proposed. Experimental validation confirms the strategy’s effectiveness in reducing noise over the wide speed range.
Lin, Fu, Chen, Yihui
Multiphysical Modeling of a Direct-Cooled Litz Wire Winding for a PMSM Using Surrogate Models2026-01-07317/1/2026
In permanent magnet synchronous machines (PMSMs) ohmic losses occur in the stator windings. Reducing these losses contributes to a higher efficiency and increases the vehicles range. An effective approach to reduce frequency-dependent AC conduction loss is the use of litz wires. In addition, direct cooling helps to reduce DC conduction loss and winding temperatures. Therefore, this work presents a multiphysical modeling approach of a direct-cooled litz wire winding in a PMSM. It combines loss modeling of the winding with novel thermal and hydraulic calculation methods. AC conduction loss due to skin and proximity effect and DC conduction loss are modeled temperature dependent. Scaled-down conjugate heat transfer simulations are used to determine the heat transfer coefficient (HTC) between wires and coolant. Additionally, the pressure drop is derived and converted into parameters for use in a porous media model. The derived parameters are used to generate surrogate models to enable computationally efficient predictions. Using the developed methods a case study is carried out. The influence of the number of turns per slot, litz wire diameter and number of parallel litz wires is investigated. In order to isolate the influence of the winding configuration, the geometry of the PMSM and the coolant volume flow remain constant. Performance indicators are energy consumption during a duty cycle, winding mass and pressure drop. Based on this study it is shown that the stator winding design is a multiphysical compromise. The method enables a targeted design of the winding configuration with respect to various objectives and facilitates the assessment of their influencing factors on the overall machine characteristics under conflicting performance requirements.
Blaschke, Wolfgang Maximilian, Mengoni, Leonard, List, Adrian, Kulzer, André Casal
Improved Thermal Management for Operating a Battery Electric City Bus under Real Driving Conditions2026-01-07587/1/2026
The goal of reducing global CO2 emissions requires actions especially for the transportation sector. To achieve the goal, electric traction motors are frequently implemented in passenger vehicles, as well as in commercial vehicles like heavy-duty trucks or buses. Particularly electric city buses have the potential to reduce the local emissions in urban areas and provide local exhaust-emission-free mobility. While their number of registrations rises, research focusses on the improvement of the overall system in order to increase energy efficiency. High importance is gained by the thermal management of the whole system. This research investigates a simulative approach to improve the thermal management and therefore the energy efficiency of an electric city bus. The different thermal components of an electric city bus like drive system, battery system and heating, ventilation and air conditioning system (HVAC system) are modelled. Their thermal behavior has been validated in previous research. Based on the validated model, this study proposes an improved thermal management that, state-dependent, combines the thermal circuits of the single components to reduce the overall energy demand. Cooling or heating is provided by the HVAC system. Furthermore, the simulation utilizes real driving cycles of a city bus in the Hamburg area. Measurement data from an entire year are examined by a cluster analysis that results in typical application profiles for urban bus traffic. These profiles are used as basis for further research. An operating strategy for the thermal management of an electric city bus under real driving conditions is developed using the simulation model. Results are presented, which show that the overall energy demand decreases due to an improved, application profile-dependent thermal management system.
Schäfer, Henrik, Hellberg, Tobias, Meywerk, Martin
A Comprehensive CFD-Driven Approach to Battery Thermal Modeling and Cooling System Optimization2026-01-07527/1/2026
With the continued expansion of electric mobility, liquid-cooled thermal management systems have become indispensable for ensuring the performance, durability, and safety of automotive battery packs. This work presents a novel cooling-plate design that integrates offset strip-fin turbulators to enhance convective heat transfer between lithium-ion cells and the circulating coolant. A comprehensive multi-region CFD model of the full battery pack is developed, incorporating an implicit lumped-parameter representation of cell heat generation. The numerical predictions are validated against dedicated experimental measurements available in the literature. Subsequently, a parametric study is conducted in which the number of hydraulic sub-modules and the inlet/outlet configurations are systematically varied to generate all feasible design permutations. The resulting configurations are compared to assess thermal performance and to quantify the benefits—as well as the potential penalties—introduced by the turbulators relative to the experimentally validated baseline.
Montenegro, Gianluca, Onorati, Angelo, Della Torre, Augusto, Tariq, Muhammad Hasnain, Bonetti, Elisa
Rib Design of Electric Drive Unit Housings for Reduced Noise Radiation2026-01-06876/20/2026
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.
Lennström, David, Malm, Oskar, wurzinger, Jakob, Cederlund, Johan
Application of Tone-to-Noise Ratio for Early Diagnosis and Control of Electric Drive Whine2026-01-06866/20/2026
High-frequency whine from electric drive systems has become a critical issue restricting the improvement of vehicle sound quality. Traditional evaluation methods struggle to accurately identify masked whine risks in the early research and development (R&D) phase, due to incomplete hardware of prototype vehicles and high interior background noise. This often leads to problems being delayed until the mass production stage, resulting in high rectification costs. To address this issue, this paper proposes and validates an early risk assessment method based on the Tone-to-Noise Ratio (TNR). First, the generation mechanism of Electric Drive (E-Drive) whine is systematically analyzed, identifying the electromagnetic noise of the electric motor and the gear whine of the reducer as the two dominant noise sources. To address this bottleneck, the TNR psychoacoustic metric is introduced to quantify the perceptual salience of tonal noise relative to background noise, which effectively mitigates the masking effect caused by high background noise in early prototype vehicles. Combined with an engineering case of a Plug-in Hybrid Electric Vehicle (PHEV), the study confirms that the TNR method can accurately identify potential high-risk whine orders in the Verification Prototype (VP) phase and enable reliable forward prediction of risks in the Mass Production (MP) stage. On this basis, a multi-dimensional noise reduction strategy covering harmonic current injection, gear microgeometry optimization, and transfer path optimization is developed for the identified risk orders. Full vehicle validation shows that the noise of key whine orders is reduced by 5–10 dB(A) after optimization, while the TNR value decreases significantly, and the vehicle NVH performance reaches industry-leading levels. This research forms a complete technical path from TNR-based early identification to targeted closed-loop control, providing a theoretical basis and practical engineering example for the proactive management and efficient solution of E-Drive whine risks in various new energy vehicles.
Yun, Zhao, Hui, Hui, Gao, Pan, Xiao, Zhongdi, Zan, Chen, Teng, Charlie
Vibroacoustic Analysis and Optimisation of an Electric Refrigerant Scroll Compressor2026-01-07226/20/2026
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.
Saur, Lukas, Beer, Gabriel, Fritzsche, Marco, Becker, Stefan
A High-Performance Computing Strategy for Acoustic Encapsulation Modeling of Electric Vehicle Subsystems Using Coupled BEM–PEM–FEM Methods2026-01-06946/20/2026
Electric vehicle subsystems, including powertrains, electric motors, and gearboxes, pose new challenges in achieving stringent acoustic performance targets for both interior and exterior noise. These challenges are intensified by increasingly demanding customer expectations regarding interior acoustic comfort, which encompasses the reduction of intrusive noise sources and the enhancement of overall sound quality across a broad frequency spectrum. A primary concern associated with electric vehicles subsystems is the generation of high-frequency tonal noise, commonly referred to as whine noise, which can significantly impact acoustic performance and passenger comfort. High-frequency whine noise propagates through multiple transmission paths and can be effectively attenuated at the source through encapsulation strategies, which also contribute to broadband noise reduction across a wide frequency spectrum. To predict the acoustic performance of encapsulation, a coupled simulation approach combining the Boundary Element Method (BEM), the Finite Element Method (FEM) and the Poroelastic Finite Element Method (PEM) has been developed. This methodology has been already presented and validated through experimental measurements, demonstrating its acoustic effectiveness in the encapsulation of a generic electric motor housing. While BEM is well-suited for modeling exterior acoustic propagation, standard implementations encounter limitations at high frequencies due to mesh density requirements and computational cost. This work presents hybrid parallelization strategies that integrate frequency-domain decomposition with multi-threading to accelerate BEM H-matrix computations. Frequency decomposition enables parallel processing by distributing independent frequency tasks across multiple processes, while multi-threading enhances performance for fine-grained operations such as matrix assembly and H-matrix compression within each frequency. The processes and improvements enabled by these strategies are discussed and presented within an adapted high-performance computing (HPC) environment.
Amichi, Kamel, Calloni, Massimiliano
Influence of Common-Mode Voltage Reduction Techniques on High-Frequency Sideband Vibrations in IPMSM Drives for EVs2026-01-06956/20/2026
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.
Khamis, Mahmoud Aly, Tatar, Andrei Alexandru, Repecho, Victor, Doria-Cerezo, Arnau
High-Fidelity NVH Analysis Model Development Process for EV Traction Motors Based on Experimental Correlation2026-01-06856/20/2026
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.
Kim, Donghee, Kim, Dong-Jun, Lee, SangHan, Kim, Seon Hyeong, Hwang, Seung Gyu, Valente, Giorgio, Parisouz, Shahriar, Halse, Christopher
Analytical Magnetic Circuit Modeling and Parameter Estimation of a PMSM for Spatial Harmonics and Radial Forces Characterization2026-01-06776/20/2026
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.
Luciano, Ludovica, Doria-Cerezo, Arnau, Salamone, Nicolò
Development of a Load Responsive Mechanical Shifting Mechanism and its Benefits for Battery Electric Vehicles2026-37-00266/9/2026
Many high-end electric vehicles use an automatic two-speed transmission. The ability of the drivetrain to switch between two gear ratios improves vehicle performance and increases driving range. The aim of the presented research work is to transfer these advantages to small and lightweight battery-electric vehicles, which face significant cost and weight constraints and therefore cannot rely on highly sophisticated electric motors. Direct-drive systems are widely used in this vehicle class due to their simplicity and high baseline efficiency. However, they offer limited flexibility in adapting the operating point of the electric motor under varying load conditions. A two-speed transmission can overcome this limitation by enabling load point shifting, allowing the motor to operate closer to its optimal efficiency region during both urban and extra-urban driving. This results in improved energy consumption without adding substantial system complexity. Currently, only actuated transmissions are offered on the market, with automation adding a high degree of complexity and representing a major cost driver. Therefore, the focus during the concept development phase was on designing a fully mechanical, self-shifting system to meet the cost pressures of the targeted vehicle classes. Hence, the team at ITnA developed and patented a solution that enables automatic gear changes solely based on output torque, which reflects the motor load and the current driving situation. In the present work, both the operating principle of the technology and the advantages regarding the performance and efficiency of electric vehicles are described. Owing to its simple architecture and the absence of electronics, the transmission is inherently robust and durable, making it a significant contribution to the development of sustainable and affordable e-mobility for the mass market.
Napetschnig, Christof, Tromayer, Juergen, Stückler, David
Low-Voltage Electric Vehicle with a Reconfigurable Powertrain Architecture for Urban and Extra-Urban Mobility2026-37-00256/9/2026
This paper presents a novel concept for battery electric vehicles (BEVs), referred to as the low-voltage reconfigurable electric vehicle (LVREV). The LVREV is designed to bridge the gap between L- and M-class vehicles by adopting a <60 V multi-phase powertrain combined with a swappable battery system, maintaining the overall vehicle mass below one ton. This configuration enables adaptable driving range, optimized energy consumption in urban environments, and enhanced safety. The LVREV features two distinct operating modes. Frugal mode is intended for urban use and employs a smaller battery pack to maximize efficiency and reduce vehicle mass, while Dual mode is tailored for longer extra-urban trips through the use of a dual-battery configuration. The key innovations of the LVREV concept include a reconfigurable vehicle architecture capable of meeting both urban and extra-urban mobility requirements, thus providing a highly versatile transportation solution. In addition, the low-voltage powertrain improves safety and lowers system costs, facilitating manual battery replacement and compatibility with domestic charging infrastructure. By integrating these technological solutions, the LVREV expands the potential of low-voltage electric vehicles and supports the development of more flexible, efficient, and user-oriented mobility concepts. Experimental and simulation results demonstrate the feasibility of the proposed solution and provide initial validation of the reconfigurable powertrain and battery architecture.
Tramacere, Eugenio, Favelli, Stefano, Galluzzi, Renato, Tonoli, Andrea
DDPG-Based Energy-Optimal Torque Split Strategy for Dual-Motor Electric Vehicles10-10-04-00335/22/2026
This study presents a torque distribution strategy for dual-motor electric vehicles utilizing a Deep Deterministic Policy Gradient reinforcement learning algorithm designed to optimize energy consumption. By using a simplified architecture and replicable reward functions, the proposed agents rely exclusively on standard CAN bus signals, commanded longitudinal force, and the motors’ velocities, eliminating the need for specialized sensors or complex plant models. Two reinforcement agents are trained using two different reward functions: power-based and State of Charge-based. These agents are validated through high-fidelity CarSim–Simulink co-simulations across soft, medium, and severe acceleration scenarios, in which they demonstrate superior performance to traditional adaptive methods. In the most demanding scenario, a typical adaptive strategy achieves an additional 7.8% of power consumption and 85% of optimal energy recovery, while the proposed reinforcement learning strategies reach 0.6% more consumption and 95% energy recovery during braking compared to the theoretical optimum. These results highlight a practical, reliable solution for maximizing efficiency in dual-motor powertrains without significant computational burden on existing electronic control units.
Meléndez-Useros, Miguel, Viadero-Monasterio, Fernando, López-Boada, María Jesús, López-Boada, Beatriz
Intelligent Control of Automobile Spiral Bevel Gear Grinding Process Based on Force Feedback2026-99-07245/15/2026
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.
Liu, Nan, Han, Jiang, Tian, Xiaoqing, Li, Minglei, Xue, Rui
NASA Dragonfly Mission &ndash; Rotor Blade Design and OptimizationF-0082-2026-01265/5/2026
The objective of NASA's 4th New Frontiers Mission, Dragonfly, is to explore the surface chemistry and habitability of Saturn's largest moon, Titan. With its thick nitrogen atmosphere, liquid methane cycle, and rich, organic surface materials, Titan holds clues to prebiotic chemistry to answer fundamental scientific questions about the building blocks of life. The combination of high fluid density (4.4x) and low gravity (1/7th) compared to Earth makes exploration of this cryogenic ocean world in the outer solar system feasible by means of a relocatable lander - this is Dragonfly, a multi-rotor vehicle designed for the unique atmospheric conditions and environment at Titan. Dragonfly enables flight in a quad-rotor configuration with two counter-rotating, canted rotors mounted on each of four sting arms. All eight rotors are three-bladed, stiff metal rotors that are controlled by variable-speed electric motors. The objective of this paper is to tell the story of Dragonfly's rotor blade design and optimization, starting with the conceptual design based on flight requirements for Titan, preliminary design iterations of the rotor blades, and detailed design and optimization of the final configuration. Details are given with respect to design constraints driven by the cryogenic Titan environment, resulting from scientific instruments located on Dragonfly, and the overall mission flight profile. Design tools ranged from momentum theory to free-wake methods, hybrid computational fluid dynamics (CFD), and blade-resolved CFD analyses compared to wind tunnel measurements of rotor and lander combinations.
Schmitz, Sven, Cornelius, Jason, Lorber, Peter, Modarres, Ramin, Bowles, Patrick, Ruiz, Felipe, Allred, Gracelyne, Gruber, Kate
Shape Optimization of a Single-Stator Dual-Rotor Axial Flux Motor for eVTOL AircraftF-0082-2026-02935/5/2026
Emerging technologies in the field of electrified propulsion systems offer a promising solution to reduce the dependence on fossil fuels and improve efficiency. However, the design of high-power density electric machines introduces new challenges, including limited passive cooling potential and the issue of the weight of electric motors. To address these challenges, this paper considers analysis and design methods for high torque-to-weight ratio axial flux motors. A magnetic equivalent circuit model coupled with a lumped parameter thermal network is developed for design space exploration and optimization. This inexpensive analytical model predicts the performance of a single-stator dual-rotor axial flux motor based on geometry, loading condition, and slot and pole pair combination. To enable comparisons against real-world data, the optimization study was demonstrated using the hover mission requirements from the Research Aircraft for eVTOL Enabling techNologies (RAVEN) vehicle to minimize the mass of the motor. In tandem with the analytical model, a higher-fidelity finite element model was also developed, and good agreement between predicted power and efficiency was demonstrated across a range of axial flux motor designs. The lightest weight design that satisfied the hover mission requirements was the 12 pole pair 27 slot (12PP 27S) configuration with a fixed weight of 9.28 kg. The analytic model undersized the output power of the electric motor by approximately 9% across a range of slot and pole pair combinations.
Arulampalam, Seiyon, German, Brian, Kennedy, Graeme, Smith, Cameron, Gutknecht, Jonathan
Optimizing Ride Comfort and Stability in In-Wheel Motor Drive Electric Vehicles: A Correlated Semi-Active Suspension System with Kalman Filter and Spring-Type Analysis10-10-04-00304/24/2026
This research provides a unique contribution to the field of in-wheel motor drive (IWMD) electric vehicles (EVs) by addressing the challenges associated with the use of permanent magnet synchronous motors (PMSMs) for traction. These motors, integrated into the unsprung masses, increase the wheels’ rotational inertia, reducing ride smoothness on uneven roads. To mitigate this issue, we present an optimal Kalman filter for a magnetorheological (MR) control suspension system that correlates road inputs between the front and rear wheels. This filter significantly improves the estimation accuracy of state variables by incorporating the motor’s vertical motion, along with potential enhancements from wheelbase preview. To determine the most suitable coil spring types for use with MR dampers, we used the WDW-600 computer-controlled electronic universal testing machine to evaluate three coil spring types: constant-pitch (model A), variable-pitch (model B), and conical (model C). To assess the impact of controlled vibration on dynamic performance, we compared the dynamic characteristics of IWMD EVs equipped with passive, uncorrelated, and correlated suspension systems, all of which have controlled inverters integrated into their design. The results indicate that motor vertical acceleration and dynamic tire load are the primary factors influencing the dynamic behavior of EVs. Additionally, the vehicle’s vibration performance metrics are negatively impacted by the in-wheel motor driving system in both passive and uncorrelated suspension systems. However, the MR-controlled suspension system with a conical spring significantly enhances ride comfort and dynamic stability by addressing complex stiffness and evaluating the effects of different coil spring types on the structural response of EVs. This analysis is based on a correlated-suspension-system scenario.
Gad, Ahmed Shehata, Jabeen, Syeda Darakhshan, El-Zomor, Haytham M., Tolba, Mohamed, Elamy, Mamdouh I.
Development of a Model-Aware Data-Driven Control Algorithm for a Drive-by-Wire System for a Level 4 Automated Vehicle2026-01-00434/7/2026
Precision control in Level 4 Automated Vehicles is essential for enhancing operational efficiency, accuracy, and safety. This work, conducted as part of ARPA-E’s NEXTCAR program, focuses on developing a robust hardware and software control solution to enable drive-by-wire functionality. A previous publication by the authors presented the hardware solutions for overtaking stock vehicle controls. This paper focuses on a model-based and data-driven control algorithm to enable drive-by-wire functionality for longitudinal and lateral motion control for a 2021 Honda Clarity Plug-In Hybrid Electric Vehicle. This vehicle was equipped with a set of sensors and an onboard processing unit to enable Level 4 automation. For lateral controls, an algorithm was developed to command steering torque to the electronic power steering module, ensuring the vehicle could attain the desired steering angle position at varying speeds. The system leveraged feedforward and feedback mechanisms. Feedback controller gains were identified through frequency response analysis of the steering torque assist electric motor and were further refined during track testing. To optimize the controller’s response time, a feedforward function was developed using a physics-aware model of the vehicle's steering system. The independent feature selection for the model was guided by using the physics of the system. For longitudinal control, the control inputs included the positions of the brake and accelerator pedals sent to the stock ECU, with the desired speed as the setpoint. The setup used a combination of feedforward and feedback control to achieve the target acceleration or deceleration. These algorithms underwent extensive dynamometer and track testing to perform various maneuvers in conjunction with the automated driving system.
Adsule, Kartik, Bhagdikar, Piyush, Drallmeier, Joseph, Alden, Joshua, Gankov, Stanislav
Embedded Real-Time Control of a Distributed Trailer Propulsion System with Regenerative Braking for Net Neutral Load Towing2026-01-00654/7/2026
Towing imposes substantial efficiency penalties on both battery-electric vehicles (BEVs) and internal combustion engine (ICE) vehicles, reducing range by 30-50%. This paper presents a proof-of-concept embedded control architecture for distributed trailer propulsion that actively regulates drawbar force to reduce towing loads. Unlike proprietary e-trailer systems requiring specialized hardware, the proposed implementation demonstrates feasibility using commercial off-the-shelf (COTS) components and open-source software. The distributed architecture employs dual Raspberry Pi 4B single-board computers communicating via ROS 2 at 20 Hz. The trailer-mounted controller executes a Simulink-generated control node coordinating load cell acquisition (HX711 ADC), motor CAN bus telemetry, and throttle commands to a 5 kW BLDC traction motor powered by a 5 kWh LiFePO4 battery pack. A vehicle-mounted controller logs OBD-II/CAN validation data. The control pipeline implements cascaded EWMA/Hampel digital filtering with intentional phase lag for hitch-force regulation. The system was validated through on-road testing with an ICE towing vehicle pulling a 1,000-lb trailer over standardized 2.1 km segments following SAE J1321 Type II procedures. Preliminary trials demonstrated stable control performance with drawbar force regulation with no oscillatory behavior. Fuel consumption measurements showed promising improvements (9.4% lower fuel consumption in assisted vs. baseline conditions), though limited sample size precludes definitive causal claims. The primary contribution is establishing technical feasibility of cost-effective COTS implementation (USD 5,000 hardware cost) for trailer propulsion control, providing a foundation for expanded validation studies and commercial deployment pathways.
Joshi, Gaurav, Adelman, Ian, Liu, Jun, Donnaway, Ruthie
Physical Test Validated Multi-Level Power Electronics for Next-Generation Electrified Vehicles Charging & Efficiency Improvement2026-01-04354/7/2026
Improving the energy efficiency of electrified vehicles remains a central objective in modern electric powertrains. Multi-level converters (MLCs) are widely recognised for lowering conversion losses relative to two-level inverters and improving total harmonic distortion (THD) in the sinusoidal supply to motors with a consequent reduction in motor losses. Despite this, sustained production-oriented validation at the integrated system level remains limited. This work introduces a multi-level converter architecture of the Battery Integrated Modular Multi-Level Converter (BIMMC) topology using Cascaded H-Bridge (CHB) architecture. It offers improvements in all key metrics of performance, cost, package size, mass and robustness compared to the current state-of-the-art two-level inverter system with distributed functions for charging available in the market today. The overall solution is highly functionally integrated. It supports four major functions required in electric vehicles without the need for additional hardware. Firstly, supply to and control of a three-phase electric motor without the need for a separate, standalone inverter. Secondly, all usual battery management system (BMS) functionality including energy and State of Charge (SOC) management to module level enabling usable energy and robustness improvements. Thirdly, the ability to charge from both alternating current (AC) (single phase and three-phase) and direct current (DC) sources without the need for separate on-board charger (OBC) hardware whilst also enabling an innovative pulse charging approach which benefits both charging time and battery ageing compared to conventional DC charging. Finally, the ability to deliver a controlled DC supply to non-traction loads on the vehicle with high efficiency and redundancy. The BIMMC topology proposed has been designed, built at prototype level and tested in order to collect performance data to empirically validate empirical study of the performance and functional benefits of the approach for traction motor drive, battery stored energy management and charging. Measured results demonstrate that improved inverter waveform quality correlates with lower motor harmonic losses and measurable drive-cycle efficiency gains, consistent with prior MLC assessments. Battery SOC depletion can be managed actively within the complete battery yielding increased usable energy and further driving range gains. Pulse charging shortens charge time whilst maintaining battery health metrics within acceptable limits, aligning with experimental evidence on pulse-based fast charging. The topology has also demonstrated the ability to pulse charge cells in a complete battery pack whilst consuming incoming DC supply current from a standard commercially available DC charger (Electric Vehicle Supply Equipment - EVSE). This potential to offer the benefits associated with pulse charging without requiring change to existing deployed charging infrastructure. Overall, proposed CHB-BIMMC architecture offers a practical blueprint for next-generation electric vehicles (EVs), and is compatible with ongoing integration trends that converge traction, charging and battery management functions within a unified power electronics and control platform.
Bao, Ran, Kalaiselvan, Prashanth, Rener, Kristof, Hallam, Philip, Shi PhD, Kai, Yue, William, Ma, He, Grimshaw, Andrew, Patel, Simon
Real-Time Observations of the Effect of Fuel Dilution in an Engine Transient Friction Rig. Along with Real-Time Observations of Fuel Entering and Leaving Internal Combustion Engine Oil, over Both Standard Engine, ICE and Plug-In Hybrid, PHEV Dynamic Drive Cycles2026-01-03514/7/2026
Hybrid electric vehicles (HEVs) with an increasing level of electrification, are becoming a major part of the global energy transition. To achieve lower engine tailpipe exhaust emissions and improve total fuel consumption, typically the HEV control system expertly and frequently switches between the internal combustion engine and electric motor drive, with multiple stops and restarts of the internal combustion engine (ICE). As a consequential result of this switching, are typically slower or even incomplete engine warm-up times, depending on the engine speed, load pattern and run time of the vehicle drive cycle. Along with the speed and load transient control, the engine stop and start processes are also challenging to control, with respect to cold start fuel and combustion by-products entering the oil. Consequently, contamination enters the engine oil but may not completely leave. These effects are highly transient over the drive cycle. Contaminants and in particular, fuel dilution, will affect the engine oil viscosity. To demonstrate this whilst yielding insights, a precisely controlled engine test cell, running the cold start Worldwide Harmonized Light Duty Transient Cycle (WLTC) for both, a non-hybridized ICE only vehicle and a HEV in charge sustaining mode operation is described. This also has on-line viscosity sensing and oil sampling. Typical data is shared along with engine oil comparisons. For complimentary insights, the impact of the fuel dilution on engine friction was investigated using a novel, precise, fully transient engine friction test rig, which measures gasoline direct injection high pressure fuel-pump friction and engine oil viscosity accurately. The cycle is based on measured data from vehicles tested on a chassis dynamometer. On-line friction data, with oil comparisons is used to show real-time data of the effect of fuel dilution on the frictional energy required, thus CO2 over the full WLTC.
Butcher, Richard, Bradley, Nathan, Thedering, Dennis
Propulsion System Design Considerations for HEV Versus EV Applications2026-01-06414/7/2026
The design and development of EVs and HEVs has become a growing issue recently due to concerns about pollution and dependence on non-renewable fossil fuels. Accordingly, General Motors (GM) has an evolving vehicle electrification plan over the past several decades and into the future to deliver low-cost and efficient EVs and HEVs. Propulsion system requirements for the applications of EV and HEVs are quite different and therefore, the design principles and directions are also distinct between these cases. From micro-hybrid and full plug-in hybrid applications to full EV applications, design requirements, strategies and outcomes can widely vary. Continuous and peak duty are substantially different depending on the application of the vehicle. Motor operational duty is significantly higher for EV compared to the electric motor of a hybrid electric vehicle. Motor torque, power and efficiency requirements are also higher for EV motors, which greatly influences the choice of motor type and its thermal and electromagnetic design. Issues like NVH and thermal can be less significant in designing motors for HEV because of engine masking and lower duty cycle of operation. Motor design requirements, optimization process and results for two different motors intended to be used in EV versus HEV applications are discussed in this paper. Moreover, traction inverter requirements differ significantly across electric vehicles and various hybrid architectures. Each configuration presents distinct challenges—ranging from packaging and thermal management to vibration and electrical constraints. Despite these differences, the design and requirements are harmonized to reduce complexity and ensure seamless performance. This paper outlines the design strategies employed to achieve these objectives.
Momen, Faizul, Jensen, William, Das, Shuvajit, Chowdhury, Mazharul, Alam, Khorshed, Anwar, Mohammad, Reinhart, Timothy
Electrified Propulsion System Balancing for Light Duty Full Size Truck and Sport Utility Vehicles: A 2026 North American Market Perspective2026-01-04124/7/2026
Achieving the stringent EPA CAFE 2032 standards for light-duty full-size trucks and sport-utility vehicles (SUVs) in North American poses significant challenges. While Battery Electric Vehicles (BEVs) offer a clear path to zero tailpipe emissions, their widespread adoption in this segment faces hurdles including range anxiety, payload/towing capabilities, and traditional truck/SUV use cases. This paper investigates a balanced approach, focusing on optimizing propulsion system design with appropriate hardware content, can effectively meet future fuel economy and emissions standards. This investigation examines advanced BEVs and hybrid electric vehicle architectures, including full hybrids (HEVs), and plug-in hybrids (PHEVs) tailored for full-size trucks and SUVs. Considerations include the optimal sizing of internal combustion engines, electric motors, and battery packs to deliver robust performance while maximizing energy efficiency. This paper analyzes the integration of technologies such as electrified transmissions, electric motor configurations, and battery size. Trade-offs between electric motor capabilities, battery pack sizing and emissions reduction across different hybridization levels are investigated. The AMESim Hybrid Optimization Tool (HOT) is used to evaluate multiple propulsion system configurations and drive cycles for energy efficiency. Vehicle selection was performed by evaluating the payload/towing capabilities, propulsion system architecture, and vehicle model year. Drive cycles were selected from truck standards and real-world driving scenarios. The objective is to demonstrate a balanced approach for electrification pathways that satisfy consumer preferences for capability and range, ensuring CAFE 2032 compliance through a diversified powertrain portfolio.
Babcock, Dillon, Robinette, Darrell
A Comprehensive Modelling Tool for Heavy-Duty Hybrid Fuel Cell/Battery Powertrains2026-01-04304/7/2026
The global transition towards sustainable transportation is driving the development of efficient, low-emission propulsion systems. Battery-electric solutions are effective in urban contexts, but face limitations in heavy-duty and long-haul applications due to the size and weight of the required energy storage. Hybrid battery/fuel cell powertrains offer a promising alternative for such use cases, reducing vehicle mass and charging times while maintaining high energy efficiency. This study presents an original zero-dimensional MATLAB/Simulink model, named HyPoST (Hydrogen Powertrain Simulation Tool), for a parallel hybrid fuel cell/battery system, here applied to heavy-duty vehicles. The model encompasses the main vehicle sub-systems, including the fuel cell stack with auxiliaries, battery pack, electric drive, transmission and the vehicle longitudinal dynamics, coordinated through a rule-based energy management strategy. Two representative heavy-duty vehicle configurations were analysed: a Group 5 long-haul truck, and a Group 2 urban delivery vehicle. A model-to-model validation strategy was performed using VECTO as a reference, the reference European Union’s tool for estimating energy consumption in heavy-duty vehicles. A graphical user interface (GUI) enables users to modify vehicle parameters and run customized simulations, and the model is made available to the scientific community in open and editable version upon request to the authors. The results demonstrate that HyPoST accurately reproduces heavy-duty vehicle behaviour for both truck models, as revealed by the analysis of gear selection, electric motor, and battery telemetries, providing a scalable and accessible tool for engineers, researchers and students.
Montecchi, Gianluca, Martoccia, Lorenzo, D'Adamo, Alessandro
Effective Prediction of the Mechanical Properties of Glue-Laminated Motor Stator Core with Consideration of Glue Disposition2026-01-01774/7/2026
This study presents an effective predictive methodology for determining the mechanical properties of glue-laminated motor cores, with explicit consideration of glue disposition, including bonding pattern, configuration, location, and coverage. In laminated stator cores, glue bonding and stacking processes jointly govern the mechanical integrity of the lamination stack. Practical production bonding schemes are typically nonuniform and localized, leading to spatial variations in stiffness and to locally anisotropic, orthotropic material behavior. These effects influence both the in-plane and through-thickness stiffness of the stator core. They can significantly affect the accuracy of structural simulations, such as NVH responses of high-speed traction motors and e-drive systems. Given the constituent material properties of the electrical steel laminations and the glue, this work distinguishes the governing mechanisms underlying the equivalent core properties. The in-plane stiffness is primarily controlled by the stacking factor, which statistically characterizes the glue contribution in the axial direction. In contrast, out-of-plane properties (e.g., elastic modulus and shear modulus in the stack direction) are determined jointly by the glue’s axial thickness contribution and its in-plane spatial distribution. To capture these coupled effects, an enhanced homogenization framework is developed using a representative volume element (RVE) formulation implemented through finite element analysis (FEA). The laminated structure is represented as an equivalent orthotropic material, enabling directional stiffness variation induced by nonuniform bonding and lamination material. Parametric simulations establish quantitative relationships between macroscopic core properties and glue configuration, bonding pattern, and stacking factors. A closed-form analytical solution is also derived for simplified cases to support verification. The predicted effective properties show good agreement with experimentally correlated values from production cores, and with analytical solutions under simplified bonding assumptions as well. The proposed methodology enables practical inclusion of glue-disposition effects in early-stage predictive models, thereby improving the fidelity of laminated motor-core NVH assessments and generic structural analysis.
Nie, Zifeng
Novel Air System for 300 kW Heavy Duty Fuel Cell2026-01-04344/7/2026
Hydrogen fuel cell powered vehicles for heavy duty trucking are a promising path for reducing future vehicle emissions due to their reduced mass for storage and faster refueling compared to battery electric trucks. These benefits come at the cost of increased system complexity stemming from the fact that fuel cells generate electricity through a chemical reaction which must be tightly controlled. The air handling system delivers the proper amount of air (oxygen) to react with fuel (hydrogen) in the fuel cell to produce power. Air delivery requires significant power and is the largest parasitic loss for a 300 kW fuel cell. Today’s systems use an electric motor driving an air compressor to supply pressurized air to the fuel cell stack. By operating at elevated pressure levels, fuel cells can achieve higher power density, which is important for vehicle powertrains. In addition to parasitic power loss, hydrogen fuel cell systems often have reliability issues associated with the air handling system. Reliability is of significant concern for heavy duty applications (especially long-haul applications). This project aims to improve both the electrical power consumption and reliability of hydrogen fuel cell air handling systems to meet the needs of heavy duty on-highway vehicle applications. The air handling is provided by a twin vortices series (TVS) compressor in addition to adding a TVS expander to recover waste heat energy back into the compressor. The final configuration includes a 600 V, 39 kW motor connected with a single shaft to the compressor and expander. This configuration reduced the total electrical power consumption from 48.6 kW to 37 kW at full load, 13.1 kW to 9 kW at half load and 0.44 kW to 0.22 kW at idle. The response time requirement was to be less than 2 sec while the final demonstration yielded 0.62 sec. Additional design changes, including water dosing into the compressor, addition of a recuperator, and elimination of the intercooler, were made to increase the energy efficiency of the air system.
Reich, Evan, Swartzlander, Matthew, Wine, Jonathan, McCarthy, Jr., James, Miller, Eric, Akhtar, Saad, Reddy, Sharan, Lawy, TJ
Development of Honda S+ Shift Utilizing e:HEV System2026-01-04184/7/2026
Honda is promoting mobility electrification to realize a carbon-neutral society by 2050. Hybrid vehicles will remain advantageous over electric vehicles in terms of manufacturing cost and driving range until renewable energy usage increases, charging infrastructure is sufficiently developed, and battery costs are reduced. In response to this situation, Honda has developed a new control system, “Honda S+ Shift”, which further enhances the “emotional value of driving pleasure” inherent to the e:HEV system and creates new value for hybrid vehicles. Honda S+ Shift synchronizes the engine and vehicle speed and selects a virtual gear position according to the driver's operation such as acceleration, cornering, and deceleration. Subsequently, the system achieves the required system output in cooperation with a dedicated energy management system. It also works with each vehicle system, such as drive force control, sound control, and meter cluster, to stimulate all five senses of the driver, greatly enhancing synchronization between the driver's senses and vehicle behavior. This paper explains how the concept of Honda S+ Shift is realized with the e:HEV system. Since there are no mechanical gear restrictions, Honda S+ Shift can select each gear ratio freely and enables fast shifting. On the other hand, there are difficulties in realizing realistic shifting behavior without direct connection between an engine and tires. Furthermore, e:HEV has three specific operation modes: EV, Hybrid and Engine, and Honda S+ Shift has to utilize them to keep its high efficiency. The first part of this paper describes the setting of the gear ratios, drive force and deceleration. Next, it explains engine speed control to realize sharp shifting and traction motor control to produce a realistic shift feel. Then, it describes how Honda S+ Shift utilizes three modes of e:HEV. It also refers to cooperation with sound and meter cluster control to maximize its effects.
Murata, Naoya, Narimoto, Ryosuke, Saito, Masatoshi, Ishida, Daichi, Gunji, Hiroki, Mitogawa, Terumasa, Ukai, Yohei, Kurachi, Shinobu, Nagakura, Akari, Shiki, Kazuki, Maeda, Sadaharu
New Inverter Switching Control Method to Enhance Sound Quality for Electric Vehicles2026-01-04374/7/2026
Conventional inverter control uses a fixed switching frequency, which leads to high-pitched switching noise in electric vehicles (EVs) that does not vary with vehicle speed. Although EVs are much quieter than traditional internal combustion engine (ICE) vehicles, some EV owners complain about the lack of dynamic driving sound feedback. A new patented technology has been developed to enhance EV sound quality by dynamically controlling the inverter switching frequencies. This technology generates dynamic propulsion sound with new "switching order" features at multiple harmonics, with the pitch proportional to vehicle speed. A constant pulse ratio between the switching frequency and the electric motor RPM is implemented to control the switching order. This reduces switching losses during low-speed operation and provides boosted acoustic feedback to the driver during acceleration, which enhances driving experience during sports driving. Furthermore, a special "EV shifting" sound that mimics the sound of gear shifting is generated by controlling different pulse ratios at each shifting RPM zone. High switching orders are dropped between neighboring zones to boost lower frequencies for an enhanced dynamic driving experience. These new switching sound features have been validated through electric drive unit and electric vehicle tests. Jury tests confirm the new EV sound with switching orders is authentically generated from electric propulsion system and can be tuned by controlling the switching pulse ratio. This technology has been successfully implemented in the "Watts-to-Freedom" drive mode of the Hummer EV, providing enhanced EV sound feedback, and improving the driver's experience during high-acceleration events.
He, Song, Gagas, Brent, Welchko, Brian, Ball, Kerrie, Gong, Cheng
NVH Characterization of New Pulse Width Modulation Strategies2026-01-02244/7/2026
Pulse Width Modulation (PWM) is needed to supply AC motors from DC voltages, but it creates high-frequency sideband harmonics that contribute negatively to sound quality. Several strategies were developed in the last decades to reduce the total harmonic distortion and switching losses, including discontinuous PWM. A new formulation of discontinuous PWM waveforms is proposed. It eases the implementation of PWM in simulation models and on experimental platforms, but it also enables the creation of new strategies. This study aims at assessing the NVH performance of six new strategies proposed by the authors. The goal is not to enhance the electrical performance but to seek new sound attributes, to change the sound quality of the machine. All strategies were tested on a test bench to characterize their current, vibration, and noise level on the full modulation index range. The measurements performed with the new strategies present some contrast. Semi-discontinuous strategies, which present a constant segment twice as short as that of existing discontinuous strategies, allow new sound attributes to appear. They also reduce the number of commutations compared to the classic sinusoidal strategy. The method adopted therefore seems relevant for creating new strategies but requires a complete characterization to assess the compromise between electrical and acoustic performance.
Wanty, Salomé, Delpoux, Romain, Glesser, Martin, Totaro, Nicolas, Parizet, Etienne, Degrendele, Karine
Impact of Manufacturing Variability on Motor Material Properties and Its NVH Behavior2026-01-04394/7/2026
This study investigates the influence of glue coverage and stacking factors on the effective macroscopic mechanical properties of dot-glue adhesively laminated stator cores and the impact of these manufacturing-related attributes on the motor and the electric drive system's structural performance, particularly in terms of noise, vibration, and harshness (NVH). A homogenization framework based on the unit-cell method was developed to model glue-laminated stacks as orthotropic materials suitable for finite-element analysis (FEA) of partially bonded cores. Also, a closed-form analytical solution is proposed to predict the macro-mechanical properties of a core composed of isotropic constituents with the consideration of glue coverage. The approach enables systematic quantification of variations in glue coverage and stacking factor to predict the effective in-plane and out-of-plane elastic and shear moduli of the stator core. For modeling simplicity, glue is assumed to be uniformly distributed across the lamination plane at a specified coverage rate, and the adhesive layer thickness is calculated statistically as the average of the estimated values from the stacking factor. Numerical predictions from the unit-cell approach are compared with experimentally correlated material properties from production cores and with theoretical results, demonstrating excellent agreement among simulated, analytical, and measured values. Results reveal that these manufacturing parameters significantly affect NVH performance of the motor and e-drive system, underscoring the need to incorporate them into CAE predictive models to enhance reliability and accuracy. The proposed method provides a validated analytical framework and a practical design tool for integrating manufacturing variability into the mechanical evaluation of electric motors and drive systems.
Nie, Zifeng
EV Propulsion Drive Converter SiC Power Device Over-Temperature Protection under Low Motor Speed Operation2026-01-04364/7/2026
Monitoring power device temperature in an electric vehicle propulsion drive converter is extremely important to achieve full power delivery within the maximum power capability envelope. Usually, on-die temperature sensors are installed on Si-IGBT power devices in electric vehicle propulsion drive converters to enable monitoring device temperature and achieve over-temperature protection. Currently, SiC MOSFET is a promising power device in power converters of electric drives because of its lower loss, higher switching speed, higher voltage capability, and higher junction temperature limit in comparison with the widely used Si-IGBT. However, SiC MOSFET is a more expensive device, installation of an on-die temperature sensor on SiC MOSFET will significantly increase its cost and complexity. So presently, there is no junction temperature sensor installed in SiC MOSFET due to which there is great difficulty protecting SiC MOSFET from over temperature. When a junction temperature estimation method is used to monitor SiC MOSFET temperature, the power loss computation of SiC MOSFET is a key factor. However, the existing loss calculation method assumes electric motors operate at high speed and power loss is computed/estimated with rms current. When the motor operates at low speed, the existing method is not practical because of a long fundamental period of phase current. The instantaneous power losses and hence the junction temperatures of the six power converter switches are not the same under such operating conditions. Hence, the junction temperature obtained with the loss computed from the rms current value does not reflect the actual device junction temperature, which may result in a failure of power device over-temperature (OT). This paper proposes a converter power device OT protection method under low motor speed to solve the above issues. The proposed method allows system cost and complexity reduction. It computes/estimates instantaneous loss and junction temperature for each individual power device of the power converter, which enables the OT detection at the motor low speed and/or imbalance phase operation. The paper presents the technical principle of the proposed instantaneous power loss and junction temperature estimation method, and OT protection for SiC MOSFET. Its model details, simulation, and experimental test results verify the new method.
Thongam, Jogendra Singh, Ge, Baoming, Bradford, Steven, Kulkarni, Milind
Advancing Sustainable Electric Vehicles: A Simulation-Driven Study on Rare Earth-Free Motors and Battery Technologies2026-01-02424/7/2026
The increasing adoption of electric vehicles (EVs) introduces critical vulnerabilities associated with dependence on rare earth elements used in traction motors and battery systems, impacting supply chain stability, environmental sustainability, and cost scalability. This investigation focuses on simulation-optimized rare earth-free EV propulsion components, including induction-based and wound rotor electric motors employing ferrite and iron-nitride magnetic materials, in combination with lithium iron phosphate (LFP) battery chemistry recognized for enhanced safety and extended cycle life. An integrated multi-physics simulation framework coupled with targeted experimental validation is employed to evaluate efficiency, thermal behavior, and durability of the proposed motor–battery systems. The optimized configurations demonstrate automotive-grade performance, with motor efficiencies ranging from 90–96% and LFP batteries retaining over 84% of nominal capacity after 5,000 charge–discharge cycles. Simulation predictions exhibit strong correlation with experimental measurements within ±5%, confirming model fidelity. The findings indicate that rare earth-free propulsion systems and LFP batteries can meet EV performance and safety requirements while significantly reducing reliance on critical materials, supporting sustainable EV development.
Saraswat, Shubham, Vishe, Prashant
Development and Comparison of Benchmarking Methods for Electric Vehicle Drive Units2026-01-01984/7/2026
At the U.S. Environmental Protection Agency’s National Vehicle and Fuel Emissions Laboratory, a development project was implemented to compare various test methods for benchmarking the operation of vehicle electric drive units (EDUs). In earlier research, several test methods were identified, of which two were used to test a Chevrolet Bolt EDU: (a) in-vehicle testing of the complete EDU on a chassis hub dynamometer and (b) stand-alone testing of the EDU’s electric motor and inverter in a dedicated test cell after removal from the vehicle. The resulting data sets were compared with each other and with similar data previously published by GM. In this paper, additional EDU test methods are explored. First, the stand-alone testing of the EDU and its subcomponents is expanded to include testing both with and without the EDU gearing. This testing allows the electric motor, inverter, and gearbox to be characterized separately and the EDU to be characterized as a complete unit. Second, in-vehicle testing of the complete EDU is performed on a roll dynamometer. EDU efficiency and losses are determined using data obtained from wheel hub torque sensors; these results are compared to estimated values based on the force and speed data collected by the roll dynamometer. Finally, the relative difficulty of implementation and the robustness of the resulting data for each of the benchmarking methods developed is analyzed and compared to methods developed and described in earlier research. Metrics used for comparison include the cost and level of effort of the implementation, complexity of the setup, repeatability of the test conditions, safety considerations, ability to separate EDU components, completeness of the data set produced, and the variability, quality and accuracy of the resulting data.
Moskalik, Andrew, Schauer, Ethan, Barba, Daniel
Comparative Analysis of Flux Linkage Characterization Methods for Automotive Permanent Magnet Traction Motors: A Critical Review and Performance Evaluation Framework2026-01-04414/7/2026
Accurate flux linkage characterization is essential for the design, control, performance and efficiency optimization of permanent magnet (PM) traction motors in automotive applications. Precise knowledge of flux linkage across varying load, speed, and temperature conditions directly impacts torque production, field-weakening capability, overall drive system efficiency and torque security. This paper presents a critical review and classification of flux-linkage characterization methods, encompassing offline laboratory mapping, standstill signal injection, self-commissioning inverter-only routines, and online real-time estimation. Each method exhibits distinct trade-offs in terms of accuracy, robustness to inverter nonlinearities, temperature adaptability, cost, and scalability for production and in-vehicle use. With the increasing complexity of automotive traction systems, understanding these trade-offs is crucial for optimal motor design and control. To enable systematic comparison, a performance evaluation framework is introduced based on key performance indicators (KPIs), including accuracy (below base speed, field weakening, and regeneration conditions), robustness to stator resistance variations and inverter nonlinearity, thermal adaptability, test complexity, time efficiency, cost, and applicability across the motor development lifecycle. These KPIs were selected based on their direct impact on motor performance, manufacturability, and suitability for various stages of automotive traction motor development, ensuring that analytical, dyno testing, and in-vehicle considerations are addressed.
Khan, Ahmad Arshan, Haddad, Reemon, Kim, Jay, Hermann, Justin, Mohamadian, Mustafa
Assessing Energy Use, Cost, and Emissions of Small Regional Rail Vehicles: Methodology and Case Study on a German Track2026-01-04194/7/2026
This work evaluates a standardized 30-ton, 16 m railbus platform optimized for unelectrified regional service, focusing on propulsion system design and trade-offs between range, cost, and emissions. A MATLAB/Simulink drive-cycle model was developed to simulate energy consumption and component performance under realistic operating conditions. The Erfurt–Rennsteig route in Germany (130 km round trip, gradients up to 6 %) was selected as a representative case study. The model incorporates detailed sub-models for traction motors, lithium-ion batteries (LFP and LTO), fuel storage, fuel cells, and ICE gensets across multiple fuel options (diesel, gasoline, methane, ethanol, methanol, HVO, FAME, and hydrogen). Battery lifetime is estimated using a combined cycle- and calendar-aging model using the rainflow algorithm to extract charge cycles, while cost models include capital, fuel, maintenance, track fees, and staffing. Results show that battery-electric configurations achieve 1 kWh/km energy use, while hybrid systems range from 2–4 kWh/km depending on fuel and secondary power unit. Control strategies that enable deeper cycling of the traction battery reduce fuel consumption by 7–18 %, with further savings possible from larger battery or genset capacities. Well-to-wheel greenhouse gas emissions vary widely: from near-zero for renewable fuels and clean electricity mixes to over 1,000 gCO2/kWh for fossil-based options. Lifecycle cost analysis indicates that while fuel may represent up to 25 % of total costs, track and station fees dominate operational expenses. Autonomous operation could eliminate oboard staffing costs, amounting to 25–35 %.
Ahrling, Christoffer, Tuner, Martin, Gainey, Brian, Torkiharchegani, Amir, Scharmach, Marcel, Hertel, Benedikt, Alaküla, Mats
Lightweight Bubble Sheet Panel To Reduce Inverter Noise and Vibration for Electric Vehicles2026-01-04424/7/2026
Inverters are typically integrated into electric drive units for electric vehicles (EVs) to reduce packaging size and cost. However, coupled vibrations from the electric motor and gears are transmitted to the inverter, which can become a dominant noise source due to its large radiative panel. Metal panels are required for electromagnetic interference (EMI) compliance, yet these covers usually lack sufficient stiffness or damping for noise control. Adding ribs and applying damping treatments result in excessive mass, cost, and packaging challenges. A new bubble sheet panel design has been developed to enhance the structural strength and damping performance of the inverter cover while significantly reducing its mass. A thin sheet of aluminum is welded onto the cover in an optimized pattern that enhances stiffness and damping performance while accommodating packaging requirements. The welding pattern can include logos or artistic designs to improve the panel’s appearance. The metal sheets are blown apart between the welds to form a 3D structure that is three times stiffer and twice as strong as a flat monolithic sheet of the same thickness. The composite dual bubble sheets can effectively reduce structural vibration. Damping materials, such as liquid-applied sound deadener (LASD), can be injected into the bubble sheet cavities to significantly improve its damping performance. Prototype bubble sheets have been designed, analyzed, and tested for an integrated inverter used in front-wheel-drive (FWD) electric drive unit for EV applications. Analysis and modal tests show a reduction of 10 to 15 dB at panel resonances with close to 30% reduction in mass. The bubble sheet panel is installed on an integrated inverter and tested in the electric drive unit. Sound power measurements confirm a reduction of up to 10 dB in inverter panel vibration.
He, Song, Bobel, Andrew, Naismith, Gregory, Yi, Wenwen, Patruni, Pavan Kumar
Optimizing Custom Hybrid Solutions for Low-Volume Specialist Equipment2026-01-04794/7/2026
Off-road vehicles are typically powered by diesel engines, sized to cover the highest peak loads in their dutycycles. Such applications can be designed with downsized engines, using hybridization to supplement engine power with electrical power for short periods. However, many applications are low-volume and specialized, making it impractical to deploy heavy engineering resources to optimize each one. For this reason, manufacturers tend to produce maid-of-all-work vehicles to cover every situation. This paper demonstrates the benefits of custom hybridization for specialist applications, and addresses the lack of accessible software tools for evaluating such opportunities. Analysis is applied with a fast, low-cost, Concept-based software tool named “ePOP Concept”, suited to original equipment manufacturers (OEMs) who seek to provide custom low-volume vehicles. It allows many different powertrain architectures to be evaluated rapidly at the product planning stage, and can be quickly set up and used by non-specialists in simulation. Agricultural load cases are analyzed, showing the benefits of adding hybridization through electric motors and stored energy, supplementing engine power for demand peaks to enable engine downsizing. Use cases for four Fendt diesel tractors were taken from a dataset generated by Götz et al, at the agricultural facilities of the Technical University of Munich, which has been made publicly available by the authors to address the absence of standard load cycle data for the analysis of tractor electrification. The results show benefits for a customizable hybridization architecture to accommodate specific use cases, and the benefits of quick, accessible analysis methods for small engineering teams, to support early product decisions and what-if analyses.
De Salis, Rupert, Fons, Daniel
Methods of Highly Repeatable Lubricant Testing for Electrified Vehicles: Universal Motor Control and Statistical Test-Variation Analysis2026-01-04214/7/2026
This paper describes a systematic approach to evaluate lubricants for hybrid and electric vehicles (xEVs) that can detect impacts on efficiency as low as 0.1 percentage points. Two testing methods were developed to evaluate lubricants’ efficiency effects: (1) on a complete vehicle (using the manufacturer’s hardware and motor control) and (2) on a standalone drive unit (using custom power electronics and control). A Monte Carlo simulation was used to analyze the resulting data to determine the detection limits of the vehicle test method. To evaluate the effectiveness of the test stands and the data-analysis method, a Tesla Model 3 electric drive unit and a Chevrolet Bolt battery electric vehicle (BEV) were characterized for system efficiency. For the Bolt mounted on a hub driven chassis dynamometer, this method is capable of detecting a change in the drive unit’s electromechanical efficiency between baseline and candidate fluids of <0.4 percentage point (pp) with 95% confidence at most of the operating points analyzed. This method can be applied to high-precision testing applications, such as lubricants or additives, cooling systems, gear trains, dynamic seals, bearings, or electric motor designs.
Luo, Yilun, Gross, Michael, Kostan, Travis
Control Strategy Optimization to Improve Energy Efficiency of Electric Wheel Loader Wheel Drive System02-19-02-00113/27/2026
Driven by the dual-carbon goals of “peak carbon emissions” and “carbon neutrality,” improving energy efficiency in electric construction machinery has become a key focus. This study proposes an energy-saving torque control strategy for the traction motor of electric wheel loaders, aiming to reduce drive system energy consumption. The innovation lies in coupling parameter optimization of the pedal–torque mapping and regenerative braking to enhance overall efficiency. An electric model was built using Cruise and validated against real-world V-cycle test data, showing good agreement with an average relative error of 4.08%. Based on the model, two optimized control strategies were developed and evaluated through simulations and field tests. The results showed energy savings of 7.08% and 16.18% in simulation, and 6.83% and 15.51% in tests, respectively, demonstrating the effectiveness and practical value of the proposed method.
Ming, Qiaohong, Wang, Yangyang, Wang, Feng
Aumovio's remote temp sensor far more accurate for e-mobility26AUTP03_123/1/2026
At the U.S. headquarters for Aumovio SE (formerly Continental Auto Group), the company showed its new remote temperature sensor for EV motors as part of its post-CES tech day presentations. The tech, which provides a more accurate reading of the rotor temperature of an EV motor, could lead to more sustainable motor designs by reducing the amount of rare earth materials used to increase the heat resistance of magnets. It can also improve potential motor performance. The e-motor rotor temperature sensor (e-RTS) is placed directly near the rotor, improving its tolerance range from 15 degrees C (59 F) to 3 degrees C (37 F). It communicates wirelessly to a wired transceiver elsewhere on the motor module (it can be moved around for better packaging).
Clonts, Chris
On the Modal Characteristics of Motor Stators under Different Interlaminate Fastening Conditions14-15-01-00052/14/2026
The increasing demand for quiet and efficient electric vehicles has highlighted the importance of understanding vibration and noise characteristics of motor stators. Previous studies have extensively modeled electromagnetic excitation and laminated structures, but there has been little experimental evidence clarifying how different interlaminate fastening methods affect vibration modes under comparable conditions. This knowledge gap limits the ability to optimize fastening strategies for noise and vibration control in practical motor design. In this study, laminated stator cores were fabricated with different fastening conditions—bolting, clinching, and welding—and subjected to vibration testing and experimental modal analysis. Natural frequencies, damping ratios, and mode shapes were identified for torsional, circumferential, and breathing modes. The results revealed that the in-plane torsional natural frequencies increase with bolt axial force, while clinching provides additional resistance to interlaminate movement but shows only a minor dependence on the number of clinching points. In contrast, the circumferential modes and the breathing-type (0,0) mode remain largely unaffected by these fastening variations. Welding points did not exhibit a consistent trend across the tested conditions, indicating that their influence on the modal properties is less systematic compared with bolting and clinching. The findings contribute not only to fundamental understanding of laminated stack vibration behavior but also to practical guidelines for designing fastening strategies that enhance vibration robustness and acoustic performance in automotive electric motors.
Matsubara, Masami, Saito, Akira, Shimada, Shogo, Oishi, Taizan, Furuya, Kohei, Kawamura, Shozo, Tajiri, Daiki
Computational Study on Dynamic Handling Performance of a Retro Fitted Electric Two-Wheeler Using 125cc Powered ICE Reference2026-28-00472/12/2026
With the development in motor technology and battery technologies, the scope for a low-cost EV has been increasing in India. There remains an after-mark potential for conversion of an ICE powered two-wheeler to an EV power train. Such a move reduces the carbon footprint from the vehicle drastically and is still being explored. This study investigates the effect of replacing the ICE with an electric motor in a 125cc motorcycle, with a particular focus on vehicle handling performance using Slalom test. The two wheelers were modelled using calculated mass properties and estimated / calculated moments of inertia using CAD for both ICE and electric powertrains. The electric propulsion system took into consideration the role of a battery pack in the mass and MI calculation. The framework with degrees of freedom is well established in BIKESIMTM simulation environment. A slalom test with automatic gear shift and throttle to maintain speed of the vehicle was set-up to estimate the handling performance. The speeds of the vehicle were computed for 60kmph condition. The output parameters of interest were the steering angle, steering torque, yaw rate, lateral acceleration and lean angle. Within the assumptions of this work, the results from the simulations indicated that handling performance of the retrofitted EV power train was comparable to that of an ICE vehicle and rider may not feel it to be drastically different.
Sankarasubramanian, Hariharan, M, Shaghasra, V, Ramprathap
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