Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In the present paper, there is an attempt to present the design and construction of a high-efficiency electric powertrain developed for a Shell Eco-Marathon Urban Concept vehicle. To validate the system's performance, a Simulink-based vehicle dynamics model was developed. The findings validate the feasibility of a lightweight, cost-effective powertrain for competition and real-world low-speed electric vehicles. The paper concludes with design insights, simulation validation, and recommendations for future optimization and control strategy development.

There are some comments and proposed changes.

Comments

• The paper complies with the journal subject area.
• while the described solution is supported by the provided results.
• Verbally enhance the abstract section in order to highlight the objectives and novelty of the paper.
• There are repetitions within the introduction. Try to improve that section in order to describe in a clearer manner the scope and the methodology that is proposed.
• No need for aim and objectives section. Merge it with the introductory section.
• Avoid providing the same information multiple times within sections 2 and 3.
• Merge validation and discussion sections (7 and 8).
• Lastly, enhance the conclusion section to strengthen the novelty of the described solution and the scientific importance of the obtained results.
• In general, the paper is hard to follow due to repetitions of the information provided. (Excessive length of manuscript)

Comments on the Quality of English Language

Typos/editing

• Please check the abbreviations (especially RES, PV, EV, V2G, GHG, HEDNO). They have to be stated in their first occurrence in the text and used thereafter in the whole document.
• line 14 -> define CNC acronym
• line 12-> Eco-marathon (use lowercase m)
• line 35->no need for new paragraph
• line 40-> define acronym EV
• line 41->attempts to address
• line 42->this gap
• limes 44-55-> meaning repetition
• line 73-> existing literature
• line 77, 84, 91-> replace figure 1 with a corresponding table
• line 74, 745-> EV use acronym
• line 80, 88, 96-> define PMSM acronym in the first occurrence
• line 199-> modeling with one l
• line 231, 234, 239, 241, 243, 245, 250, 252, 254, 256, 260, 880, 882, 884, 886, 902, 908, 912, 929, 931-> no need to assign number to equations (not mentioned afterwards within the text)
• line 283-> define SoC acronym
• line 463, 591, 606->check reference
• don’t use bold writing within text
• line 536-> no need for material type column
• line 579-> no new line
• line 636-> define EDM acronym

Author Response

Thank you very much for taking the time to review this manuscript.

Please find detailed responses below file attached.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents the design, construction, and Simulink-based validation of a high-efficiency electric powertrain tailored for a Shell Eco-Marathon Urban Concept vehicle. The system includes a 1500 W BLDC motor, a two-stage chain drive, and a custom 12S8P lithium-ion battery pack. The authors have emphasized manufacturability, cost, and rule compliance. This paper is well-designed within a clear logical flow. Here are some comments.

1. Have the authors conducted any empirical validation to benchmark the simulation results against hardware tests or competition data?
2. Could the authors elaborate on the motor controller architecture and whether field-oriented control (FOC) or trapezoidal control was employed or considered?
3. Have the authors considered a continuously variable transmission (CVT) or sliding chain mechanism for real-time adaptability?
4. The literature review part could be strengthened to further highlight the advantage of the presented paper by supplementing the following references.

[1] Tsirogiannis, E.C.; Stavroulakis, G.E.; Makridis, S.S. Electric Car Chassis for Shell Eco Marathon Competition: Design, Modelling and Finite Element Analysis. World Electr. Veh. J. 2019, 10, 8. https://doi.org/10.3390/wevj10010008

[2] H. Wang, J. Sun and K. W. E. Cheng, "An Inductive Power Transfer System With Multiple Receivers Utilizing Diverted Magnetic Field and Two Transmitters for IoT-Level Automatic Catering Vehicles," in IEEE Transactions on Magnetics, vol. 59, no. 11, pp. 1-6, Nov. 2023

5. Could the authors contextualize this energy performance with respect to similar Shell Eco-Marathon teams or vehicles?

Author Response

Thank you very much for taking the time to review this manuscript.

Please find detailed responses below file attached.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The article submitted for review contains a well-documented, comprehensive integration of existing technologies (BLDC, chain drive, Molicel cells, Simulink). The authors propose practical design innovations, such as a two-stage chain drive optimized for gear shifting, a lightweight design with CNC components, and the adaptation of an off-the-shelf Peerless differential. The article also includes simulation-based confirmation of energy efficiency of 20.95 Wh/lap and comprehensive documentation (CAD, BOM, build instructions), which is rare in academic works of this type. However, most of the technologies used (BLDC, chain, 18650 cells, PID controllers) are well-known and widely used solutions. The authors do not introduce entirely new technical concepts due to the constraints of the Shell Marathon. The article may be valuable as a reference for teams designing fuel-efficient EVs under limited conditions, but not as an example of implementing groundbreaking technologies.

Before publication, the authors should make the following corrections to improve the scientific quality of the article:
1) The literature review is insufficient. Although the article claims to reference the 2024 IEA report, most of the cited works are from 2014–2022. The authors did not include, for example, open-source EV platforms (e.g., OSVehicle, EVmod), which are important for low-cost EV designers. Comparisons with modern low-voltage platforms used in real-world applications (e.g., autonomous vehicles, delivery trucks) are missing.
2) The article should be shortened to a maximum of 30 pages. Redundant figures (e.g., Figure 5, Figure 6) should be removed, as they do not contribute anything valuable to the research and analysis and are well-known design solutions.
3) Figures 11 and 12 should be presented side by side. Figure 13 does not contribute anything interesting and should be removed.
4) Line 606. Error! Reference source not found.
5) Figure 18 is redundant. The bearing method is shown in Figure 17.
6) Figure 21 is unnecessary. The manufacturer's website should be referenced in the text. This is a well-known commercial solution.
7) 6.2. Simulation Results. This subsection contains only one graph, a time series of the SoC. With such an advanced model in Simulink, more interesting graphs can be generated. For example, a graph of the power consumed by the drive system versus driving speed.

Author Response

Thank you very much for taking the time to review this manuscript.

Please find detailed responses below file attached.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors took into account all the reviewer's recommendations, which improved the scientific quality of the article. It now meets the requirements of the MDPI Hardware publishing house.