Thermal and Mechanical Analysis of a 72/48 Switched Reluctance Motor for Low-Speed Direct-Drive Mining Applications
Round 1
Reviewer 1 Report
The authors present the thermal and mechanical analysis of a SR motor for mining applications. What the authors want to present is quite good, but the way they present is not very impressive. The manuscript can be improved a lot.
Some comments and suggestions about the content of the paper
line 34: Noise and mechanical vibrations are of the main sources that may lead to a breakdown of an electric motor --> is it? Mechanical vibrations yes, but noise is the result of the vibration.
It is not clear why the author chose 4 different cooling channel configurations for the numerical analysis? Explain the reason behind choosing 1 channel, 5 channels, 9 channels and 17 channels?
Table 5 shows something different than what is mentioned in the Table Title. The title says "Values of essential angles" but the table shows the dimension of the cooling channel.
line 232: Table 6 includes a comparison between the values of the heat transfer coefficient obtained by the numerical and analytical solution. What is the point of placing Table 6 here? In my opinion, Table 6 should be placed at the beginning of the analysis. Also, if you are doing a numerical analysis, what is the significance of the comparison with the coefficients calculated analytically?
The numerical thermal analysis has been validated by experimental results. Can you also include a picture of the full experimental set-up and explain?
Also, the numerical results of the mechanical analysis are not validated by the experimentation. Can you add a validation, for example, a hammer test to calculate the natural frequencies?
check the caption of Figure 15.
Check the Units: for example, degree C (without bold C); Torque: Nm or kNm.
line 286: From the data in Table 6--> Shouldn't it be Table 9?
page 8, second sentence: the variable Ts is defined but nowhere seen in the equations.
In addition, the English language should be improved extensively. The paper has a lot of grammatical mistakes, and incorrect and incomplete sentences. Some observations here:
line 70: The temperature rises analysis of SRM is implemented in this paper --> rewrite this sentence.
line 75: Change the word "predestine".
page 4, first sentence: "Conduction occurs between to touch bodies"--> what does this mean?
line 105: SRM fed by an asymmetric asymmetrical half-bridge power converter--> repeated word?
line 194: In[39] was presenting of an 825 kW water jacket cooled induction motor--> rewrite the sentence.
line 209: The inlet side of the end winding is cooled (78C), however, the outlet of end winding is exposed (94C) to significantly reduce cooling.--> This sentence is very confusing.
line 269: compared with the CDF results--> CFD??
Author Response
1
Response to Editor’s and Reviewer’s Comments
Manuscript ID: applsci-529835
Jun, 2019
Dear Editor and Reviewers
Thank you very much for your invaluable comments on our manuscript. We have accommodated these
and revised our paper accordingly (highlighted). Please find attached the new version for your
consideration. In addition, we also respond to the comments point to point as follows.
Response to Reviewer A: Comments
Comments and Suggestions for Authors
The authors present the thermal and mechanical analysis of a SR motor for mining applications. What the
authors want to present is quite good, but the way they present is not very impressive. The manuscript
can be improved a lot.
Some comments and suggestions about the content of the paper
Point 1: Line 34: Noise and mechanical vibrations are of the main sources that may lead to a breakdown
of an electric motor --> is it? Mechanical vibrations yes, but noise is the result of the vibration.
Response 1: Thank you. Yes, noise can be the result of the vibration. We clarified this on page 2， lines
34 to 35.
Mechanical vibration is one of the major mechanical faults to cause a breakdown of electric machines.
Point 2: It is not clear why the author chose 4 different cooling channel configurations for the
numerical analysis? Explain the reason behind choosing 1 channel, 5 channels, 9 channels and 17
channels?
Response 2: We have followed the reviewer suggestion and included a more comprehensive shown on
pages 10 to 11， lines 175 to 188， and Table 5.
From Table 5, the convection heat transfer coefficient ( ) value for 17 channels is the highest
realistic value, whilst in 19 channels the fluid loss would be significantly higher. For this reason, 9
channels chosen as the value is nearly half of the 17 channels and 5 channels chosen as a quarter.
1 channel is also used as a benchmark. 2
Point 3: Table 5 shows something different than what is mentioned in the Table Title. The title says
"Values of essential angles" but the table shows the dimension of the cooling channel.
Response 3: Sorry for this mistake; we have corrected it in the revised paper, on page 11. (Table 5 is
now Table 6).
Point 4: line 232: Table 6 includes a comparison between the values of the heat transfer
coefficient obtained by the numerical and analytical solution. What is the point of placing Table 6 here? In
my opinion, Table 6 should be placed at the beginning of the analysis. Also, if you are doing a numerical
analysis, what is the significance of the comparison with the coefficients calculated analytically?
Response 4: Thank you for the suggestion. We have followed your suggestion accordingly, on page 14,
lines 236 to 239. (Table 6 is now Table 7).
The reason for a comparison is that analytical results can provide approximate coefficients while
numerical methods are far more accurate and time-consuming. That is, this comparison is used to
verify the coefficient of the water jacket- based on the cooling system.
Point 5: The numerical thermal analysis has been validated by experimental results. Can you also
include a picture of the full experimental set-up and explain?
Response 5: Thank you for the suggestion. We have added Figure 21. Details of testing are given on
pages 20 to 21, lines 306 to 318.
Point 6: Also, the numerical results of the mechanical analysis are not validated by the experimentation.
Can you add a validation, for example, a hammer test to calculate the natural frequencies?
Response 6: Thank you for the suggestion. We have carried out some mechanical tests and results are
given in Table (12) on page 23.
Point 7: check the caption of Figure 15.
Response 7: Sorry for the mistake . We have revised the caption of Figure 15 on pages 18 .
Point 8: Check the Units: for example, degree C (without bold C); Torque: Nm or kNm.
Response 8: Thank you for spotting the inconsistency. We have corrected these accordingly, on pages
12, line 204 .
Point 9: line 286: From the data in Table 6 --> Shouldn't it be Table 9?
Response 9: Sorry for the mistake . The correction has been made in the revised version, on pages 21 to
22, lines 323 to 335. (Table 9 is now Table 11). 3
Point 10: page 8, second sentence: the variable Ts is defined but nowhere seen in the equations.
Response 10: Sorry for the typo. This is T max and it is in Equations (10) and (12). We have corrected it
accordingly, on page 8.
Point 11: In addition, the English language should be improved extensively. The paper has a lot of
grammatical mistakes, and incorrect and incomplete sentences. Some observations here:
Point 11: Sorry for the mistake. We have conducted a proofread by an English Professor in the field of
the work. We also respond to the English language comments point to point as follows.
Point 11-1: line 71: The temperature rises analysis of SRM is implemented in this paper --> rewrite
this sentence.
Point 11-1: Sorry for the mistake, we have corrected the sentence, on page 2, lines. 69 to 70
The temperature rise in the SRM is analyzed in this paper.
Point 11-2: line 75: Change the word "predestine".
Response 11-2: Sorry for the mistake, we have changed the word "predestine" in the revised version, on
page 2, lines 74 to 75.
Then, the radial forces were applied to the 72/48 SRM for a harmonic analysis using 3D FEA so that
the total deformation of the machine can be visualized and analyzed.
Point 11-3: page 4, first sentence: "Conduction occurs between to touch bodies"--> what does this mean?
Response 11-3: Sorry for the confusion. We have corrected it in the new revision, on page 4.
The heat transfer conduction is heat transferring through direct contact of materials. Whereas, the
heat transfer convection is heat transferred by a gas or fluid. The heat transfer radiation is when the
heat energy travels in actual waves.
Point 11-4: line 105: SRM fed by an asymmetric asymmetrical half-bridge power converter--> repeated
word?
Response 11-4: Thank you for pointing out this mistake, we have corrected the sentence, on page 4,
line 106.
It evaluates the core losses in the SRM fed by an asymmetrical half-bridge power converter circuit
and control circuit, which is modeled in SIMPLORER as presented previously.
Point 11-5: line 194: In [39] was presenting of an 825 kW water jacket cooled induction motor--> rewrite
the sentence.
Response 11-5: Sorry for the mistake, we have corrected the sentence , on page 12, lines 213 to 215 .
WJ is widely used for the high-power induction motor (IM) and interior permanent synchronous
motor (IPMSM) [39, 40]. Based on the same principle an analytical method and numerical method
are used in this work to obtain the machines temperature rise.
Point 11-6: line 209: The inlet side of the end winding is cooled (78C), however, the outlet of end winding
is exposed (94C) to significantly reduce cooling.--> This sentence is very confusing.
Response 11-6: Sorry for the confusion, we have corrected the sentence, on page 12, lines 227 to 229.
The temperatures of the two sides of end windings near the inlet and outlet are 78 ◦ C and 94 ◦ C,
respectively. This situation can be explained based on water flow behavior in the casing of the water
jacket for 1 channel.
Point 11-7: line 269: compared with the CDF results--> CFD??
Response 11-7: Sorry for the mistake, we have corrected the sentence , on page 20, lines 293 to 294 .
The measurement results are compared with the CFD results to verify the previous calculations.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper describes thermal and mechanical performance of a 72/48 switched reluctance motor. A thermal analysis model is created and its effectiveness is verified using a prototype. In addition, the deformation mode of the rotor shaft is analyzed. My comments are as follow.
1. The natural frequency of the analysis model is compared with that of the prototype. The deformation mode of the prototype should be compared. The results of an experimental modal analysis is needed.
2. A unit (Hz) should be added in Table 7.
3. The spelling of the x-axis in Figure 14 (b) should be corrected.
Author Response
Response to Editor’s and Reviewer’s Comments
Manuscript ID: applsci-529835
Jun, 2019
Dear Editor and Reviewers
Thank you very much for your invaluable comments on our manuscript. We have accommodated these
and revised our paper accordingly (highlighted). Please find attached the new version for your
consideration. In addition, we also respond to the comments point to point as follows.
Response to Reviewer B: Comments
This paper describes thermal and mechanical performance of a 72/48 switched reluctance motor. A
thermal analysis model is created and its effectiveness is verified using a prototype. In addition, the
deformation mode of the rotor shaft is analyzed. My comments are as follow.
Point 1: The natural frequency of the analysis model is compared with that of the prototype. The
deformation mode of the prototype should be compared. The results of an experimental modal analysis is
needed.
Response 1: Thank you for the suggestion. We have followed the reviewer suggestion and included a
more comprehensive comparison shown on pages 16 to 17 lines 267 to 278, and Table 9 .
In addition to a comparison of the natural frequency, another comparison between the two different
structures is presented in Table 9.
Moreover, an experimental test is carried out, and test results are given in section 5, Table (12).
Point 2: A unit (Hz) should be added in Table 7.
Response 2: Thank you for pointing out this mistake. We have modified Table 8 accordingly, on page 17.
(Table 7 is now Table 8).
Point 3: The spelling of the x-axis in Figure 14 (b) should be corrected.
Response 3: Sorry for the mistake, we have modified Figure 14 (b) accordingly, on page 17.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
All the comments have been addressed. The language could still be improved a bit.
There are small English mistakes still.
Reviewer 2 Report
The paper is well revised.
