Electric Drivetrain Research Articles

Reduced order modelling method for electromagnetic analysis of electrical machines

AbstractThis paper presents a workflow to create a reduced order model for the electromagnetic analysis of electrical machines over its operating range so that the stator forces can be exported for mechanical analysis. A permanent magnet synchronous motor developed within the EDISON (Electric Drivetrain Integration by Simulation and OptimizatioN) project is used as a model to validate the workflow. The response surface model approximation method is used to generate the reduced order model, which is then validated by comparing with the results from finite element analyses.

Exploring Differing Perspectives on Sustainability and Corresponding Strategies in German Automotive Companies

In addition to acute crises dominating the societal discourse, such as the global consequences of the COVID-19 pandemic and the Russian invasion of Ukraine, the world continues to face the ongoing challenge of limiting climate change and achieving a sustainable transformation. Yet, in public discourse, the widely used terms “sustainability” and “transformation” are not clearly defined, and the understanding varies greatly depending on the industry and the stakeholders considered. One important transformation arena lies within the German automotive industry, as it is one of the country’s biggest industrial sectors by revenue and the number of employees. In addition, the German automotive industry is currently going through a transition period due to the switch to electric drivetrains as the main propulsion technology opposed to combustion engines. Therefore, the following paper identifies the differing understandings of sustainability and according actions in the German automotive industry. Moreover, possible conflicts and prioritizations along the economic, ecological, and social dimensions of sustainability are presented based on an expert interview study. To do so, a structuring qualitative content analysis in combination with a descriptive approach was used focusing on the differing perspectives on sustainability of both the interviewees and their companies. The gathered data then allows to compare the aggregated individual and corporate sustainability perspectives in the German automotive industry, as well as comparing the sustainability perspectives of the interviewees and their respective companies case by case. The results suggest that there is a considerable discrepancy between individual and corporate understandings of sustainability. These differences can mainly be attributed to the companies’ economically driven views in contrast to the individuals’, mostly ecologically driven sustainability perspective. Moreover, several barriers and conflicts, rooted in the prioritization of economic gains, can be traced back to conflicts in the supplier pyramid. The identification of common transformation goals and measures among companies is necessary to enable a collaborative, sustainable transformation in the German automotive industry, which benefits all societal stakeholders in or attached to this sector.

Greening Your Drive: A Method of Effective Conversion from IC Engine Based Vehicle to EV

This research presents the most efficient method for turning vehicles with internal combustion engines (IC engines) into electric vehicles (EVs). With an emphasis on reducing the environmental footprint and optimizing energy efficiency, our strategy includes cutting-edge technology in electric powertrain parts, power electronics, and battery storage systems. This paper assesses performance indicators by thoroughly analyzing the integration of new electric drivetrain components and the retrofitting of old ones, including motor starting and energy usage. To produce energy-efficient EVs, we suggest a supercapacitor bank and an effective battery cooling system. The recommended approach, Safety concerns, environmental advantages, and economic viability are also covered. The suggested approach shows promise in terms of lower production of greenhouse gases, increased range, and cost-effectiveness. The results provide an efficient way of battery cooling system and efficient use of battery storage by integrating a supercapacitor bank. The outcomes support the worldwide trend towards environmentally sound methods of transportation by providing important insights that will accelerate the widespread use of sustainable EVs.

Study on the Low-noise Design of Gears Applied in an Electric Drivetrain

Study on the Low-noise Design of Gears Applied in an Electric Drivetrain

Satyadarshan Technologies & Services: revolutionizing urban mobility?

Learning outcomes After reading and analyzing this case study, students will be able to describe the challenges of creating an electric vehicle (EV) start-up with the objective of zero-carbon emissions, identify opportunities and challenges for Satyadarshan Technologies & Services (STS) in enhancing the B2B customer base and sales volumes in the EV market, identify and assess government incentives to reinforce STS’s existing EV business and compose an understanding of and determine an ability to use various industrial marketing and promotion strategies for STS in the present environment. Case overview/synopsis STS was launched in 2020 to provide environmentally conscious urban commuting. Himanshu Purohit, the founder of STS, commenced an e-bicycle assembly unit and produced the first advanced electric drivetrain technology. The vision was to transform how people viewed mobility and make EVs the standard for a healthier globe. Nurturing a start-up with zero-carbon emissions was tedious due to limited infrastructure, high costs, low market acceptance and supply chain constraints. With the relentless pursuit of excellence, STS constantly pushed the boundaries and crossed the break-even ceiling in the year 2022. As a budding player in the souk, the company expected to gain a strong presence in the EV market with particular attention to the B2B customer segment. At the same time, the company aimed to ensure business sustainability by leveraging government incentives. The company needed to expand its corporate sales volume and craft a sustainable competitive advantage. Purohit recognized various challenges to the sustainability of STS that stood between the company's goals and their realization, particularly in achieving a sustainable move in the EV segment. Consequently, Purohit found himself at a critical juncture to pave the path toward the growth of the start-up. Eventually, analysis of the company's business challenges, industrial marketing and promotional strategies required strategic planning to appraise and evaluate the business model. Complexity academic level This case study is designed for new-age Master of Business Administration and executive management programs. It should be used in entrepreneurship and strategic management courses to discuss small innovative e-bike start-ups. This includes conducting a competitive analysis and self-assessing a firm's market-oriented strategies. Prima facie, undergraduate and postgraduate students are beneficiaries of this case. This case study may also be conducive to teaching how to initiate a sustainable and green vehicle business. This case study guides students entering the EV business, addressing industry-specific challenges and conducting market analysis. Supplementary materials Teaching notes are available for educators only. Subject code CSS 3: Entrepreneurship.

Investment Value Analysis of BYD: An Integrated PEST and Financial Approach

This paper presents a detailed investigation into BYD Company Limited's investment value, incorporating a comprehensive Political, Economic, Social, and Technological (PEST) analysis with an in-depth financial evaluation. Findings from the PEST analysis underscore BYD's adept navigation of supportive government policies and its proactive stance against international trade challenges, affirming its strong domestic market position and readiness for global expansion. Economically, BYD has shown resilience through effective pricing strategies and market diversification, maintaining profitability amidst global financial fluctuations. Socially, the company's alignment with environmental sustainability trends has strengthened its brand and customer loyalty. Technologically, BYD’s advancements in battery technology and electric drivetrains position it as an industry leader. Financial findings highlight a robust year-over-year revenue increase of 42.04%, an impressive gross profit rise by 42.42%, and a significant leap in operating profit by 360.53%. Despite slight contractions in net profit margins, the company’s financial health remains strong with promising prospects for future profitability. Together, these analyses depict BYD as a compelling investment, poised for sustained growth within the NEV sector.

Simulating Noise, Vibration, and Harshness Advances in Electric Vehicle Powertrains: Strategies and Challenges

This study examines the management of noise, vibration, and harshness (NVH) in electric vehicle (EV) powertrains, considering the challenges of the automotive industry’s transition to electric drivetrains. The growing popularity of electric vehicles brings new NVH challenges as the lack of internal combustion engine noise makes drivetrain noise more prominent. The key to managing NVH in electric vehicle powertrains is understanding the noise from electric motors, inverters, and gear systems. Noise from electric motors, mainly resulting from electromagnetic forces and high-frequency noise generated by inverters, significantly impacts overall NVH performance. This article details sources of mechanical noise and vibration, including gear defects in gear systems and shaft imbalances. The methods presented in the publication include simulation and modeling techniques that help identify and solve NVH difficulties. Tools like multi-body dynamics, the finite element method, and multi-domain simulation are crucial for understanding the dynamic behavior of complex systems. With the support of simulations, engineers can predict noise and vibration challenges and develop effective solutions during the design phase. This study emphasizes the importance of a system-level approach in NVH management, where the entire drivetrain is modeled and analyzed together, not just individual components.

Correction: Selema, A. Material Tradeoff of Rotor Architecture for Lightweight Low-Loss Cost-Effective Sustainable Electric Drivetrains. Sustainability 2023, 15, 14413

The author would like to make the following corrections to the published paper [...]

CFD simulation and geometric optimization of a novel baffle heat sink for power electronics cooling

The electric drivetrain of an electric vehicle typically has two fluid circuits: an oil circuit for lubrication and a water-glycol circuit for cooling. Eliminating the water-glycol circuit can result in a more compact and lighter drivetrain. However, this requires the drivetrain components to be cooled with oil as coolant, which has inferior heat transfer properties compared to water-glycol mixtures. This is particularly challenging for the power modules in the power electronics unit, which exhibit some of the highest heat fluxes in the drivetrain. This study focusses on the design and optimization of a novel type of heat sink for laminar flows with baffles to guide the flow in four different directions. This has two main advantages: the baffles act as fins and increase the heat transfer area and they introduce a swirling motion in the oil thereby disturbing the boundary layers continuously. Computational fluid dynamics simulations using Ansys Fluent are performed to evaluate the thermohydraulic performance of the heat sink. The influence of design parameters such as the height and thickness of both fins and baffles and the baffle spacing in horizontal, upward and downward direction was evaluated by simulations with several combinations of the design space, considering manufacturing constraints. The optimization of the design showed that the fin thickness, horizontal baffle spacing and baffle length should be as small as possible, while there were optimal values for fin height, upward and downward baffle spacing, streamwise baffle spacing and baffle thickness. The simulations show that the thermal resistance of the baffle heat sink can be 19% lower than that of a benchmark pin fin heat sink at equal pumping power.

An Investigation of Representative Customer Load Collectives in the Development of Electric Vehicle Drivetrain Durability

To ensure the precise dimensioning and effective testing of drivetrain components, it is crucial to have a thorough understanding of customer requirements, with a particular emphasis on customer stress on these components. An accurate interpretation of customer data is essential for determining representative customer requirements, such as load collectives. The automobile industry has faced challenges in analyzing large amounts of customer driving data to obtain representative load collectives as target values in durability design. However, due to technical limitations and cost constraints, collecting data from a large sample size is not feasible. The ongoing digitalization of the automotive industry, driven by an increasing number of connected vehicles, enhances data-based and customer-oriented development. This paper investigates representative customer load collectives using cloud data from over 40,000 customer vehicles to lay the groundwork for realizing robust requirement engineering. A systematic method for analyzing big data on the cloud was introduced. The derived component-specific damage distribution from these collectives adopts a unique approach, utilizing the 1% vehicle term instead of the common 1% customer term to represent typical customer stress. This study shows that the driven mileage and the number of vehicles are crucial factors in 1% vehicle analysis. An analysis of the characteristics of the 1% vehicle is conducted, followed by an exploration to determine the required vehicle quantity for obtaining stable results. The shape parameter of the damage distribution determines the necessary number of vehicles for a reliable conclusion. Additionally, a comparative analysis of market-specific customer requirements between the US and Europe is presented, and real usage differences in customer operations are explained using an operating point frequency heatmap. The information presented in this paper provides valuable input for optimizing durability design and conducting efficient, customer-oriented tests, resulting in significant reductions in development time and costs.

Analyzing Safety Factors and Predicting Fatigue Life of Weak Points in an Electrically Driven, Multi-Purpose Cultivation Tractor

The advancement of agriculture and a shortage of labor have led to an increased use of agricultural machinery. However, the resulting environmental issues have prompted a shift from internal combustion engines to electric drivetrains. The electric drivetrain includes the installation of batteries, which can lead to decreased energy efficiency and significant loads on the vehicle due to their heavy weight. Consequently, the importance of ensuring the safety of agricultural machinery is being increasingly emphasized. The load on the frame of agricultural machinery is not consistent during off-road driving, and the accumulation of load cycles can lead to the destruction and failure of components. Therefore, it is necessary to ensure a level of safety and to predict the fatigue life. In this study, we estimate the safety factor and predict the fatigue life of weak points in an electrically driven, multi-purpose cultivation tractor based on working conditions (width, soil, and drive). Strain gauges were attached to these weak points to measure the strain, which was then converted to von Mises stress. Fatigue life was predicted using the rainflow counting method and the Palmgren–Miner rule. The results showed that the safety factor measured under various working conditions was greater than 1. The estimated minimum fatigue life was 124,176 years. Considering that the cultivator is used for 29.7 h annually and has a durability lifespan of 5 years, it is expected to be safely usable throughout its service life.

Investigation of Low-Frequency Data Significance in Electric Vehicle Drivetrain Durability Development

The digitalization of the automotive industry presents significant potential for technical advantages, such as the online collection of customer driving data. These data can be used for customer-oriented development to improve the durability of components or systems. However, due to current limitations in data transfer, the sampling frequency is typically lower than that of classic dataloggers. This paper examines the importance of low-frequency data in the development of drivetrain durability and investigates the extent to which these data can be utilized for a drivetrain durability analysis. Real driving data were utilized as a database to demonstrate the impact of downsampling on data significance, with the deviation in damage serving as the criteria. The findings suggest that low-frequency data, when available in sufficient quantities, can provide valuable information for predicting durability in rollover and time at level classification. The deviation in the damage prediction is less than 2% for distances exceeding 5000 km. However, low-frequency data are not suitable for rainflow analysis. Finally, the database size was adjusted to assess the statistical stability of the durability prediction. A larger dataset typically reduces variance. The paper presents evidence for the quality and usability of cloud data in drivetrain durability design. Cloud data from a significant number of customer vehicles can be used for certain analyses of representative customer load collectives, which can reduce development time and costs.

Mechanical engineering in automotive innovation: A review of electric vehicles and future trends

This paper provides a succinct overview of the extensive landscape of automotive innovation within the realm of mechanical engineering, focusing on the transformative emergence of electric vehicles (EVs) and the anticipated future trends in this dynamic field. As the automotive industry undergoes a paradigm shift towards sustainable and eco-friendly transportation solutions, the role of mechanical engineering in shaping the future of mobility becomes increasingly pivotal. The review begins by delving into the evolution of electric vehicles, tracing their historical development and highlighting key milestones that have propelled them from niche alternatives to mainstream contenders in the automotive market. A comprehensive examination of the underlying mechanical engineering principles governing EV design and performance is presented, emphasizing advancements in battery technology, electric drivetrains, and energy management systems. The document scrutinizes current challenges and opportunities associated with electric vehicles, addressing issues such as range anxiety, charging infrastructure, and the environmental impact of battery production and disposal. It explores ongoing research efforts within the field of mechanical engineering aimed at overcoming these challenges and enhancing the overall efficiency, safety, and sustainability of electric vehicles. Furthermore, the paper outlines the anticipated future trends in automotive innovation, providing insights into cutting-edge technologies and methodologies poised to shape the next generation of electric vehicles. Topics include advancements in materials science for lightweight construction, artificial intelligence integration for autonomous driving, and the integration of renewable energy sources to further enhance the environmental footprint of EVs. This review underscores the pivotal role of mechanical engineering in the ongoing revolution of automotive technology, emphasizing the transformative impact of electric vehicles and offering a glimpse into the exciting future trends that will define the landscape of sustainable mobility.

Numerical hazard analysis of torque vectoring system for electric drivetrain considering handling uncertainty

Numerical hazard analysis of torque vectoring system for electric drivetrain considering handling uncertainty

(Invited) Advanced Design Concepts for Vertical Gallium Nitride MOSFETs

Wide-bandgap semiconductors have a significant advantage over conventional Si-based electronics by leveraging materials properties to achieve higher breakdown voltage, lower on-resistance, and high-frequency operation. Gallium nitride (GaN) is of interest for vertical device architectures but directly competes with the already established silicon carbide (SiC) power devices. In the case of vertical GaN rectifiers which are unipolar figure-of-merit limited, the materials advantage of GaN provides a modest gain in terms of critical electric field and very slight gains in bulk mobility and saturation velocity, while being at a disadvantage in terms of thermal conductivity compared to SiC. However, despite still being a very immature technology, vertical GaN MOSFETs have demonstrated channel mobilities upwards of 200 cm2/V·s, over three times that of SiC-based MOSFETs. For 1200V-class devices, channel mobility directly contributes to a significant portion of device on-resistance, and it is therefore expected that vertical GaN MOSFETs would offer a substantial performance advantage compared to SiC MOSFETs. Despite this, the development of vertical GaN devices that demonstrate this theoretical potential faces many challenges. Several fundamental limitations exist within the manufacturing process that prohibit GaN devices from directly mirroring the design rules for similar SiC devices. In this talk, we will discuss several key design concepts recently developed for vertical GaN MOSFETs which serve to address several critical issues for GaN.Limitations in selective-area doping for GaN provide an additional challenge in designing edge termination structures, advanced features that protect the gate dielectric during the blocking state, and provides restrictions on minimizing cell pitch. Proper edge termination design is required to reach an avalanche voltage near the theoretical limit and avoid early breakdown. We present an optimized design point for the edge termination with a good match between theoretical and experimental data using a step-etched junction termination extension. Despite a well-designed edge termination, early breakdown will occur in the gate dielectric at the bottom of the gate trench due to field crowding in the dielectric at high blocking voltages. We propose a new method for protecting the gate dielectric by means of a buried field shield formed by an etch-and-regrowth process. Experimental data shows this gate dielectric failure can occur as early as 1/3rd of the designed blocking voltage. The field shield design is shown in simulation to sufficiently reduce the electric field in the gate dielectric to below 4 MV/cm with minimal or no derating of the device depending on geometry of the shield. Additional methods will be presented on new techniques to minimize cell pitch, a critical factor necessary to compete against SiC. Cell pitch minimization not only reduces on-resistance and gate-charge trade-offs, but it is also a driving factor to reduce cost and increase die density on wafer. Finally, techniques have been developed for advanced metal contact designs specific to the trench MOSFET, which further aid in reducing cell pitch. This work was supported by the Electric Drivetrain Consortium managed by Susan Rogers of DOE’s Vehicle Technologies Office. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Combined Electromagnetic and Mechanical Design Optimization of Interior Permanent Magnet Rotors for Electric Vehicle Drivetrains

In many high-speed electrical machines, centrifugal forces within the rotor can be first-order constraints on electromagnetic optimization. This can be particularly acute in interior permanent magnet (IPM) machines in which magnets are usually retained entirely by the rotor core with no additional mechanical containment. This study investigates the nature of the trade-off between mechanical and electromagnetic requirements within the context of an eight-pole, 100 kW IPM machine with a base speed of 4000 rpm and an extended speed range up to 12,000 rpm. A series of mechanical and electromagnetic models are used to estimate the level of shaft interference, mechanical stress in critical regions of the rotor and the impact of various features and dimensions within the machine on electromagnetic torque. A systematic exploration of the design space is undertaken for rotor diameters from 120 mm to 180 mm, with optimal designs in terms of torque per unit length established at each diameter while meeting the constraints imposed on mechanical stress. The final preferred design has a rotor of 165 mm and an axial length of 103 mm long with a fractional slot winding in a 30-slot stator. The overall machine has an active mass of 42.3 kg, which corresponds to ~2.4 kW/kg. This paper describes the optimization study in detail and draws on the results to explore the nature of the design trade-offs in such rotors and the impact of core properties.

Retrofitting of an Existing Garbage Tipper Truck with an Electric Powertrain and its Renewable Charging Station Concept Based on On-Grid Solar Charging

To tackle the pollution problem the best way is to switch to electric vehicles but when we look at the statistical figures of India’s electric vehicle market we can observe the truth that the electric 2 and 3-wheeler market is good in India but the electric 4-wheeler market is not very good. Policymakers' worries about the growing importance of the Climate Change issue have contributed to India's rising levels of air pollution. There are a lot of gasoline and diesel automobiles on the road that is to blame for the severe pollution. 25 of the 100 most polluted cities in the world, or 14 of the list, are in India, according to a search for the 100 most polluted cities worldwide. Petrol and diesel vehicles continue to run in large numbers in India, causing extremely high pollution. The most harmful pollutants emitted into the environment are PM 2.5, SO2, CO, NOx, and PM 10, and they are also the primary pollutants. Since there are so many vehicles on the highways in Indian cities, we know that the cities are crowded. In such a situation, numerous electric vehicle manufacturers are traveling the nation to display their electric automobiles. Additionally, in India, if an electric vehicle's motor output is less than 250W, neither registration nor a driver's license is necessary to operate one of these vehicles. The category for EVs over 500W is the same as that for gasoline and diesel vehicles. The government will electrify all two-wheelers by the years 2024–2025, and all four-wheelers will be electrified by the years 2030–2040. The difficulty now is that many OEMs, auto-ancillaries, and automobile manufacturers intend to enter the market for electric cars in response to these encouraging moves. And when we discuss any vehicle, the mileage or the distance traveled is a key issue. Additionally, electric vehicles, such as 4-wheelers, will compete with conventional cars powered by internal combustion engines, which today give excellent mileage. However, reducing pollution is a crucial issue, and I think electric automobiles can do it more effectively. The transformation of an existing diesel tipper truck into an electric and on-grid-based solar renewable charger is described in this research. This paper discusses the creation and evaluation of various car parts and accessories. This outlines how to go from a mechanical drivetrain to an electric drivetrain. And the charger works on the on-grid solar-based renewable charger.

Improvement of electrical and mechanical properties of laser welded lap joints via dimensional optimization

With the proliferation of electric drivetrains, the development and optimization of joining techniques for the fabrication of battery packs became a prime manufacturing topic. Decreasing the electrical resistance and increasing the mechanical strength of the welds at the individual cell level are of great importance not only for productivity and efficiency but also for safety and sustainability purposes. Lasers offer an advanced, highly automatable solution for battery cell joining. Usually, the optimization focuses on the laser parameters or the scanning speed. However, the most widespread battery welding geometry, the so-called lap geometry, allows alternative possibilities for joint property optimization. The novelty of our approach is that we focus on systematic experimental investigation of the effects of dimensional parameters and the layout of the weld pattern. Systematic experiments reveal that the shape and size of the weld area have substantial effect on the properties of the laser welded joint. Our results prove that a rather substantial gain can be achieved in both the electrical and mechanical properties when the weld consists of at least two parallel bead segments. We also show that it is beneficial by both means if the segments have the greatest individual length and placed apart at the maximum feasible distance. The orientation of the straight segments affects the mechanical and electrical behavior differently: strongest welds consist of weld segments oriented in parallel, while the smallest resistance can be achieved using segments oriented perpendicular to the direction of current flow, respectively.

Strategies for green industrial and innovation policy–an analysis of policy alignment, misalignment, and realignment around dominant designs in the EV sector *

Governments in industrialized as well as emerging economies are racing to implement policies to accelerate clean energy innovation and capture the economic benefits of decarbonization. This paper explores which combination of technology-push and demand-pull policies best situates a country to lead in clean energy innovation, as new or dominant designs emerge and replace older technologies. A new analytical framework for green industrial policy is introduced regarding the alignment, misalignment, and deliberate misalignment of policies. This framework is applied to battery electric vehicle drivetrain technology to examine the use of policy alignment and misalignment by countries with big automakers as they pursue strategic green industrial policy. We find that countries that achieved early and sustained (not inconsistent) policy alignment gained a first-mover advantage compared with countries that deliberately or accidentally misaligned their policies. We also find that first-mover advantage can be lost due to deliberate misalignment of policies caused by an inability of governments to effectively incentivize their firms to develop and deploy cleaner and more efficient technologies. In situations where governments adopt misaligned or conflicting policies, incumbent industries tend to pursue their prior comparative advantage and maximize return from investments in prior technologies. We also find that deliberate misalignment of policies can be an effective catching-up strategy.

Electric Vehicle Drivetrain Efficiency and the Multi-Speed Transmission Question

The availability of high-fidelity energy consumption estimates and the ability to evaluate drivetrain efficiency are crucial for effectively planning a large-scale transition to electric vehicles. For both new and retrofitted electric vehicles, a key question is the transmission type—single-speed or multi-speed—and the resulting impact on the vehicle’s overall efficiency. This paper presents a comprehensive simulation-based methodology for evaluating the impact of transmission selection on vehicle efficiency using high-fidelity driving cycle data. The method can be used for new vehicles and retrofit applications where a transmission is already present. The efficiency of a single-speed reduction gearbox was compared to that of a five-speed multi-speed transmission in a retrofitted vehicle, of which the impact of the manual transmission on the vehicle dynamics and efficiency was examined. The manual transmission proved to be more efficient for a perfect gear-shifting strategy.