Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Firstly, I would like to congratulate the authors on this comprehensive study.

For me, it is unclear: the stator has 12 slots or 12 slots/quarter, resulting in 48 total stator slots?

I believe there is a discrepancy between D9 and D10 (lines 152-156, and Fig. 8).

You say "loaded runs", but do not explain how the loading was considered. It is commendable to specify this. It would also be good to briefly present the conditions under which finite element analyses are performed.

Can the authors explain, at this point, whether the best motor option can be selected? If so, how is this done?

Author Response

Thank you for your overall positive evaluation of our paper. We respond to your comments below. Your feedback has greatly helped us clarify the study, and we trust that the revisions appropriately address the points raised. The changes are highlighted in bright blue in the revised manuscript.

You can find our point-by-point responses below.

Comment:
For me, it is unclear: the stator has 12 slots or 12 slots/quarter, resulting in 48 total stator slots?

Answer:
The discrepancy between the description and the first figure may have caused the misunderstanding: a 48-slot stator was used for general illustration instead of the 12-slot topology used in the simulations. Thank you for bringing this to our attention.

Improvement:
Figure 1 was modified to better reflect the paper’s content.

 

Comment:
I believe there is a discrepancy between D9 and D10 (lines 152–156, and Fig. 8).

Answer:
This is correct. We switched the symbols of the design variables between D9 and D10 in the text to improve consistency, but Figure 8 was not updated accordingly. We also checked Figure 9 and confirmed that no modification is needed there.

Improvement:
Figure 8 was corrected to align with the paper’s content.

Comment:
You say “loaded runs”, but do not explain how the loading was considered. It is commendable to specify this. It would also be good to briefly present the conditions under which finite element analyses are performed.
Answer:
The loaded condition is 30 A/mm², star-connected three-phase, with series connection between the slots. This represents a peak-current scenario inherited from our previous study [1]. It may be feasible in practice with an appropriate number of turns per slot. The manufacturing effort has focused on the rotor—specifically, achieving accurate control of the magnet displacement and the magnet-flux-barrier extension (first prototype under investigation). This may lead to stator changes in the future. We believe using nominal load instead would not materially affect our conclusions, as the study compares closely related models and the load condition does not influence cogging torque.

The FEA conditions were previously incomplete regarding material properties and torque resolution. Material properties are based on laboratory measurements of the reused stator steel and the Fe–6.5 wt% Si alloy intended for the 3D-printed rotor (second prototype to be built). For further details on the simulations, please see [1]; for the measurement method, see [2].
Improvement:
We extended the description of the simulation conditions and added references to prior work to fully document the study settings.

Comment:
Can the authors explain, at this point, whether the best motor option can be selected? If so, how is this done?
Answer:
The present paper provides generalized insights into how magnet displacement and magnet-flux-barrier extension affect torque, with emphasis on cogging torque. Selecting a single “optimal” machine is beyond the scope here. For optimal topology selection, please see our previous work [1], where SPOTIS and TOPSIS multi-criteria decision-making methods were applied and robustness of the optimal design was investigated.

Improvement:
We added an explicit reference to our previous work.

References
[1] Mihály Katona, Tamás Orosz, Robustness of a flux-intensifying permanent magnet-assisted synchronous reluctance machine focusing on shifted surface-inset ferrite magnets, Computers & Structures, 316 (2025) 107845. https://doi.org/10.1016/j.compstruc.2025.107845
[2] Katona, M.; Bányai, D.G.; Németh, Z.; Kuczmann, M.; Orosz, T. Remanufacturing a Synchronous Reluctance Machine with Aluminum Winding: An Open Benchmark Problem for FEM Analysis. Electronics 2024, 13, 727. https://doi.org/10.3390/electronics13040727

Reviewer 2 Report

Comments and Suggestions for Authors

This paper investigates the influences of PM displacement & flux barrier designs on cogging torque. Although some work have been presented in the manuscript, there are main concerns as follows:

(1) The method used to simualte/evaluate cogging torque has not been revealed. It is difficult to justify the results in this case.

(2) Lack of information on design parameters of the motor

(3) A lot of contents have been involved with optimization method, which shows minor relating to the main topic.

(4) There is little discussion on the influences of design on cogging torque, particularly for summaries of trends/principles/mechanism.

(5) No experimental results for verification.

In this case, I believe this manuscript may be interested t readers but complete reorganisation and redrafting are essential.

Author Response

Dear Reviewer,

Thank you for evaluating our paper. We would like to answer your questions below. Your comments have greatly helped us to clarify the study. We trust that the changes made in the article appropriately address the questions raised. The changes are highlighted in bright blue in the revised manuscript.

Comment:
The method used to simulate/evaluate cogging torque has not been revealed. It is difficult to justify the results in this case.
Answer:
Thank you for highlighting that the finite element simulation might need to be extended. We added a description of the material properties and the resolution for torque evaluation, in addition to the existing topology description and boundary condition definition.
Improvement:
The description of the finite element simulation was extended.

Comment:
Lack of information on design parameters of the motor.
Answer:
We respectfully believe Section 2.1 — Models for Comparison provides sufficient information about the design variables, including a table summarising the symbols of the design variables, their meaning, and their optimisation range with measurement units, as well as a figure depicting their meaning and their distribution in the optimisation history.
Improvement:
The table caption was extended with the meaning of abbreviations to further clarify the design variables.

Comment:
A lot of contents have been involved with optimization method, which shows minor relating to the main topic.
Answer:
We respectfully believe that the manuscript covers the relevant parts of the study and contains no unnecessary information.
Improvement:
No changes were made.

Comment:
There is little discussion on the influences of design on cogging torque, particularly for summaries of trends/principles/mechanisms.
Answer:
Thank you for highlighting that the discussion might need to be extended. We provided a comprehensive description and figures illustrating how the magnet-flux-barrier extension affects tangential stress, the tangential forces acting upon the stator teeth, the leakage flux, and the main flux, thereby contributing to cogging torque and explaining the mechanism of cogging-torque reduction.
Improvement:
The discussion was extended.

Comment:
No experimental results for verification.
Answer:
The study aims to formulate a general conclusion on the effect of magnet displacement and magnet-flux-barrier extension on the torque output of four different rotor configurations of approximately 20,000 models each, focusing on cogging torque. Even manufacturing a small sample of the ~80,000 models would impose a substantial financial burden that cannot be addressed at present. Furthermore, this unique topology presents manufacturing challenges that we are currently evaluating; therefore, we are in the process of creating the first prototype. Its completion date is uncertain.
Improvement:
No changes were made.

Thank you for your consideration. We look forward to your response.

Sincerely,
Mihály Katona and Tamás Orosz
Széchenyi István University, Hungary

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I do not have further comments.