Review Reports - Performance Analysis and Modeling of a Multiphase Switched Reluctance Generator Under Fault Conditions for Wind Energy Applications

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper discussed the performance analysis and modeling of a multiphase switched reluctance generator under fault conditions. The detailed comments are as follows:

The torque ripple reduction is claimed but not quantitatively compared with baseline models or existing methods.
The paper uses “SRM” and “SRG” interchangeably, which may confuse readers about operating modes.
The conclusion does not summarize limitations or suggest future research directions clearly.
It is necessary to mention other advanced motor control methods in introduction is uesful, such as composite adaptive super-twisting sliding mode control using barrier function for PM motor drives and modified fixed-time extended state observer based fixed-time sliding mode control.
The fault-tolerant performance is claimed but not validated under dynamic wind speed conditions.
The conclusion does not summarize limitations or suggest future research directions clearly.

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Reviewer 1:

This paper discussed the performance analysis and modeling of a multiphase switched reluctance generator under fault conditions. The detailed comments are as follows:

Comment 1: The torque ripple reduction is claimed but not quantitatively compared with baseline models or existing methods.

Response

Thank you for this valuable comment. We agree that the original manuscript did not provide a quantitative comparison to support the claim of torque-ripple reduction. Therefore, we have revised the manuscript to remove the unsupported claim of a specific reduction in torque ripple. The revised manuscript now presents the torque waveform objectively and discusses the observed torque oscillations under the investigated operating conditions.

Revision

In Section 3.2, the following sentences were removed:

"In this simulation, sophisticated control strategies led to a decrease in torque ripple."
"The current study has produced a considerable reduction in torque ripple compared to the standard SRMs."

The following text is added for explanation:

"The electromagnetic torque exhibits periodic oscillations associated with phase excitation and commutation. The resulting torque waveform is presented in Figure 7. The observed torque response is used to evaluate the generator behavior under the investigated operating conditions."

Comment 2: The paper uses "SRM" and "SRG" interchangeably, which may confuse readers about operating modes.

Response

We thank the reviewer for pointing this out. The manuscript has been carefully revised to distinguish between the general switched reluctance machine (SRM) concept and the switched reluctance generator (SRG) investigated in this study. The term SRG is now used consistently when referring to the generator under investigation.

Revision

When referring to the generator, the term is changed from SRM to SRG and in the Introduction section SRM is used while discussing some reference work.

A few lines have been edited for clarity in the revised version as follows:

“SRM is used in the variable-speed wind energy conversion as generator, that is, switched reluctance generator (SRG) for their brushless, magnet-free construction which give them high robustness, low manufacturing cost, and strong fault tolerance, as alternative to induction and PM machines.”

Comment 3: The conclusion does not summarize limitations or suggest future research directions clearly.

Response

We agree with the reviewer. The conclusion has been revised to clearly state the limitations of the present simulation-based investigation and to identify possible directions for future research.

Revision

The conclusion section has been extended to include the following lines about the extent of this study and the future work.

"The present study is limited to MATLAB/Simulink-based analysis, two representative operating-speed conditions, and a single-phase exclusion fault. Experimental validation, dynamic wind-speed operation, multiple-phase faults, and converter fault conditions were not considered. Future research can therefore focus on experimental validation, more comprehensive fault scenarios, and advanced fault-tolerant control strategies for multiphase SRG systems."

Comment 4: It is necessary to mention other advanced motor control methods in the introduction, such as composite adaptive super-twisting sliding-mode control using barrier function and modified fixed-time extended-state-observer-based fixed-time sliding-mode control.

Response

Thank you for this suggestion. Recent advanced nonlinear and robust control approaches have been added to the Introduction to provide a broader perspective of recent developments in electric-machine control. Their relevance to robust operation of electric-machine drives is also briefly discussed.

Revision

The following paragraph has been added in the Introduction section.

"Recent research has also investigated advanced nonlinear and robust control techniques for electric-machine drives. Composite adaptive super-twisting sliding-mode control using barrier functions has been investigated to improve robustness and tracking performance in PM motor drives [35]. In addition, modified fixed-time extended-state-observer-based fixed-time sliding-mode control has been proposed to improve disturbance rejection and convergence characteristics in PMSM position servo systems [36]. These developments demonstrate the increasing use of robust nonlinear control techniques in electric-machine applications. However, the present study focuses on the modeling and fault-performance analysis of a multiphase SRG rather than the development of a new nonlinear control algorithm."

Comment 5: The fault-tolerant performance is claimed but not validated under dynamic wind speed conditions.

Response

We appreciate this comment. We agree that the present manuscript does not investigate continuously varying wind-speed conditions. To avoid overstating the scope of the study, the manuscript has been revised to clearly state that the analysis is based on the operating conditions considered in the presented simulations. Dynamic wind-speed operation is now identified as a limitation and a potential topic for future investigation.

Revision

In the Abstract, the following text is modified to remove any confusions.

“under the investigated operating-speed conditions and phase-exclusion fault. The present work considers representative operating-speed conditions rather than a continuously varying wind-speed profile."

Comment 6: The conclusion does not summarize limitations or suggest future research directions clearly.

Response

Thank you for the comment. The Conclusion has been revised to include the limitations of the current simulation-based study and specific future research directions, including experimental validation, dynamic wind conditions, and additional fault scenarios.

Revision

The conclusion section has been extended to include the following lines about the extent of this study and the future work.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper carries out modeling and performance analysis under fault conditions for the Multiphase Switched Reluctance Generator (SRG) used in wind energy conversion systems. A MATLAB/Simulink simulation model consisting of a wind turbine, converter, controller and SRG is established, and the variation characteristics of voltage, current, torque, rotational speed and flux linkage of the system under normal operation and single-phase fault conditions are analyzed. The research object of this paper has certain engineering application value. Multiphase SRGs feature permanent-magnet-free structure, high reliability and certain fault tolerance, so they have potential application prospects in the field of new energy power generation. The overall structure of the paper is relatively complete, covering system modeling, simulation analysis and discussion of fault operation. Nevertheless, the manuscript still has obvious deficiencies at present, and its innovation, theoretical contributions and experimental verification cannot sufficiently support the research value claimed in the paper. Major revisions are suggested before reassessment.

The originality of this paper is severely insufficient. It only reproduces the single-phase open-circuit simulation analysis of four-phase SRGs that has already been completed in existing literature, and no novel fault-tolerant control, motor topology or fault identification scheme is proposed. There is no effective incremental innovation, and the research work is highly repetitive.
The overall workload is inadequate. Only two sets of fixed steady-state rotational speeds and only single-phase fault simulations are set up, without comparative analysis of dynamic variable wind speed conditions, multi-gradient excitation angles and multiple types of motor faults. The whole paper only relies on qualitative description of single-run simulation waveforms, lacking quantitative calculation of indicators such as torque ripple, loss and efficiency.
The mathematical model of the paper needs further improvement. Although the SRG mathematical model including voltage equations, electromagnetic torque equations and mechanical motion equations is established and the torque formula conforms to the basic theory of switched reluctance machines, the model description is relatively simplistic. Further explanation on the acquisition method of the inductance model, the relationship among flux linkage, current and rotor position, whether nonlinear magnetic saturation characteristics are considered, and the sources of simulation parameters are required. The paper mentions that flux linkage, co-energy and static torque data are adopted as model inputs, yet the sources and acquisition methods of such data need more detailed elaboration.
Inconsistent terminology exists and unification is required. The research object of this paper is switched reluctance generator (SRG), but SRM is repeatedly used to refer to the research object in the main text. For instance, the statement "The SRM will show a brief response during startup" appears in the result analysis section, while the discussion here actually targets the generator system, which should be uniformly revised to SRG. It is recommended to check the use of terms including SRM, SRG, generator and machine throughout the full text to avoid conceptual confusion.
Insufficient information is provided in figures and tables, reducing readability. The paper contains multiple simulation result plots, yet some figures only display waveforms without necessary explanations, such as missing description of simulation operating conditions and labeling of key parameters, as well as absence of summary of performance indicators. It is suggested to add comprehensive performance tables listing average torque, torque ripple, peak current, output power and other indicators under each operating condition to deepen the analysis of results.
Generalized descriptions are present in the abstract and conclusions, and quantitative results should be supplemented to strengthen persuasiveness. The abstract and conclusions extensively adopt adjectives such as reliable, robust, suitable and sustainable without supporting specific data. For example, there is no statement of the degradation degree of performance, change of torque ripple and variation of output power after faults. It is recommended to add key simulation indicators to the abstract and conclusions to clarify contributions.
The English expression requires further polishing. Although the general meaning can be conveyed, the manuscript still suffers from overlong sentences, unclear logical levels, massive template-style expressions, inconsistent use of partial professional terms, and redundant wording in figure captions and main text. For example, expressions like "making them suitable for remote and offshore wind farm applications where high reliability and reduced maintenance are essential" are promotional and should be replaced with more objective academic wording. Professional English editing is recommended.

Author Response

Reviewer 2

Comment 1: The originality of this paper is severely insufficient. It only reproduces the single-phase open-circuit simulation analysis of four-phase SRGs that has already been completed in existing literature, and no novel fault-tolerant control, motor topology or fault identification scheme is proposed. There is no effective incremental innovation, and the research work is highly repetitive.

Response

Thank you for this important comment. We acknowledge that the original manuscript did not sufficiently clarify the specific contribution of the study. The revised manuscript therefore avoids presenting the work as a new fault-tolerant control algorithm or new machine topology. Instead, the contribution is clarified as a simulation-based performance analysis of a four-phase SRG under healthy and single-phase exclusion conditions. The Introduction has been revised to better distinguish the scope of the present work from previous studies.

Revision

The following paragraph has been added to the end of the Introduction for clarity.

"The objective of this work is to investigate the modeling and operating characteristics of a four-phase switched reluctance generator under normal and single-phase exclusion conditions for wind-energy conversion. The study focuses on the integration of the SRG, converter, controller, and wind-energy system within a common MATLAB/Simulink framework and examines the resulting voltage, current, torque, speed, and flux-linkage responses. The work is intended as a system-level assessment of the effect of phase exclusion rather than as the proposal of a new machine topology, fault-diagnosis algorithm, or advanced fault-tolerant controller."

Comment 2: The overall workload is inadequate. Only two sets of fixed steady-state rotational speeds and only single-phase fault simulations are set up, without comparative analysis of dynamic variable wind speed conditions, multi-gradient excitation angles and multiple types of motor faults. The whole paper only relies on qualitative description of single-run simulation waveforms, lacking quantitative calculation of indicators such as torque ripple, loss and efficiency.

Response

We appreciate the reviewer’s comment. We agree that the present study is limited to two representative operating-speed conditions and a single-phase exclusion fault. Since these conditions define the scope of the present investigation, the manuscript has been revised to clearly state this limitation and to avoid generalizing the results to other wind-speed or fault conditions. The discussion has also been revised to emphasize the physical behavior observed in the existing simulation results rather than claiming comprehensive fault analysis.

Revision

The discussion in the revised version is given as follows.

"The simulation study is limited to two representative operating-speed conditions and the investigated single-phase exclusion fault. Therefore, the results should be interpreted as a focused assessment of phase-exclusion behavior rather than a comprehensive evaluation of all possible wind-speed and fault conditions."

Comment 3: The mathematical model of the paper needs further improvement. Although the SRG mathematical model including voltage equations, electromagnetic torque equations and mechanical motion equations is established and the torque formula conforms to the basic theory of switched reluctance machines, the model description is relatively simplistic. Further explanation on the acquisition method of the inductance model, the relationship among flux linkage, current and rotor position, whether nonlinear magnetic saturation characteristics are considered, and the sources of simulation parameters are required. The paper mentions that flux linkage, co-energy and static torque data are adopted as model inputs, yet the sources and acquisition methods of such data need more detailed elaboration.

Response

Thank you for carefully identifying the inconsistencies in the mathematical formulation. We have re-examined the electrical and mechanical equations and corrected the formulation in the revised manuscript. In particular, the factor of (1/2) has been included in the electromagnetic torque expression derived under the linear inductance assumption. The mechanical dynamic equation has also been expressed consistently with respect to time, with the mechanical torque, electromagnetic torque, inertia, and damping terms clearly defined. Furthermore, because the simulation employs nonlinear magnetic characteristics, the revised manuscript presents the co-energy-based torque expression as the principal electromagnetic torque formulation and clearly distinguishes it from the simplified linear approximation.

Revision

The following paragraph and equations have been modified in the revised version.

"The nonlinear magnetic characteristics used in the simulation are represented through the relationship ψ=ψ (ⅈ, θ), the phase flux linkage, which depends on ⅈ the phase current, and θ the rotor position. The flux-linkage, co-energy, and static-torque data used in the model were adopted from the published SRM input-data set reported in [40]. These data are incorporated into the simulation as magnetic characteristic inputs and are used to determine the electromagnetic response as a function of current and rotor position. Thus, the model accounts for the nonlinear magnetic characteristics represented by the supplied data rather than assuming a constant inductance."

For the linear magnetic approximation, the electromagnetic torque is expressed as

where is phase current, is phase inductance, and is rotor position. For the mechanical dynamics of the generator,

Where is combined rotational inertia of the generator and mechanical system, is rotor angular speed, is time, is applied mechanical torque, and is viscous damping coefficient. To represent the nonlinear magnetic behavior of the SRG, the flux linkage is expressed as

For the nonlinear magnetic model, the magnetic co-energy is given by

The electromagnetic torque can then be obtained from

where the derivative is taken with respect to rotor position while keeping the phase current constant.

Comment 4: Inconsistent terminology exists and unification is required. The research object of this paper is switched reluctance generator (SRG), but SRM is repeatedly used to refer to the research object in the main text. For instance, the statement "The SRM will show a brief response during startup" appears in the result analysis section, while the discussion here actually targets the generator system, which should be uniformly revised to SRG. It is recommended to check the use of terms including SRM, SRG, generator and machine throughout the full text to avoid conceptual confusion.

Response

We agree with the reviewer. The terminology has been checked throughout the manuscript. SRG is now used when referring specifically to the generator studied in this work, while SRM is retained only when discussing the general machine technology or previous literature.

Revision

When referring to the generator, the term is changed from SRM to SRG and in the Introduction section SRM is used while discussing some reference work. A few lines have been edited for clarity in the revised version as follows:

Comment 5: Insufficient information is provided in figures and tables, reducing readability. The paper contains multiple simulation result plots, yet some figures only display waveforms without necessary explanations, such as missing description of simulation operating conditions and labeling of key parameters, as well as absence of summary of performance indicators. It is suggested to add comprehensive performance tables listing average torque, torque ripple, peak current, output power and other indicators under each operating condition to deepen the analysis of results.

Response

Thank you for the suggestion. The figure captions and associated discussions have been revised to provide clearer descriptions of the operating conditions and plotted quantities. A concise summary table has also been added using the performance quantities already available from the presented simulation results.

Revision

Figures 5, 6, 7, and 9 have been replaced with clear waveforms and readability enhancement. Table 2 has been added.

Table 2. Performance parameters of SRG under normal and fault condition

Parameter	Normal Value	Fault Condition Value	Unit
Operating / reference speed	800 and 1500	800 and 1500	rpm
Rotor speed (actual, steady state)	220–330	220–330	rpm
Power Output	61	12	W
Steady-state peak phase current	40	75	A
Torque transient peak (startup)	−97	-	Nm
Steady-state torque ripple band	0 to −75	−0.6 to +0.16 per active phase	Nm
WEC total torque	80	-	%
Generator total torque ripple	65	-	%
Applied phase / switched voltage	±200	±100	V
Average torque (WEC-side)	6.5	Reduced and less stable during transient	Nm
Average torque (generator-side)	−1.9	−0.4 per phase	Nm
Active phases	4	3	-

Comment 6: Generalized descriptions are present in the abstract and conclusions, and quantitative results should be supplemented to strengthen persuasiveness. The abstract and conclusions extensively adopt adjectives such as reliable, robust, suitable and sustainable without supporting specific data. For example, there is no statement of the degradation degree of performance, change of torque ripple and variation of output power after faults. It is recommended to add key simulation indicators to the abstract and conclusions to clarify contributions.

Response

We agree with the reviewer. The Abstract and Conclusion have been revised to reduce generalized and promotional statements. Claims that cannot be directly supported by the presented results have been removed or moderated.

Revision

Modified text in the Abstract is given as follows:

“The implemented excitation and converter control strategies maintain system stability and acceptable performance under the investigated operating-speed conditions and phase-exclusion fault. The present work considers representative operating-speed conditions rather than a continuously varying wind-speed profile.”

Added lines in the last paragraph of Conclusion are given as follows:

“The present study is limited to MATLAB/Simulink-based analysis, two representative operating-speed conditions, and a single-phase exclusion fault. Experimental validation, dynamic wind-speed operation, multiple-phase faults, and converter fault conditions were not considered. Future research can therefore focus on experimental validation, more comprehensive fault scenarios, and advanced fault-tolerant control strategies for multi-phase SRG systems.”

Comment 7: The English expression requires further polishing. Although the general meaning can be conveyed, the manuscript still suffers from overlong sentences, unclear logical levels, massive template-style expressions, inconsistent use of partial professional terms, and redundant wording in figure captions and main text. For example, expressions like "making them suitable for remote and offshore wind farm applications where high reliability and reduced maintenance are essential" are promotional and should be replaced with more objective academic wording. Professional English editing is recommended.

Response

Thank you for this comment. The manuscript has been carefully revised for grammar, sentence structure, technical terminology, clarity, and redundancy. Promotional statements have also been replaced with objective scientific descriptions.

Revision

In particular, we have replaced the sentence "making them suitable for remote and offshore wind farm applications where high reliability and reduced maintenance are essential"

Modified text at the end of Abstract: "These characteristics make SRGs a potential option for wind-energy conversion applications."

The manuscript has been proofread again and possible mistakes have been corrected in the revised version.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

1. The novelty and specific contributions of this study are not sufficiently clarified. Although the fault-tolerant capability of multiphase SRGs has been investigated, the differences between this work and existing studies should be clearly highlighted.

2. The references should be more carefully selected and discussed. Some references related to IPMSM and PM machines occupy a large proportion in the introduction, while the direct relationship with multiphase SRG fault-tolerant operation is limited.

3. The mathematical modeling of the SRG should be improved. More details about the magnetic characteristics, lookup table construction, and parameter acquisition method should be provided.

4. Experimental validation is strongly recommended. The current results are only obtained through MATLAB/Simulink simulations, and the effectiveness of the proposed analysis under practical operating conditions has not been verified.

5. Only single-phase exclusion fault is considered in this manuscript. More comprehensive fault scenarios, such as different failed phases, multiple-phase faults, and converter faults, should be investigated.

6. The control strategy of the SRG converter is insufficiently described. The design principle and parameter selection of the excitation control and current control should be explained in detail.

7. The simulation results are mainly presented by waveform comparison, while quantitative analysis is insufficient. More performance indexes, such as torque ripple ratio, output power variation, and efficiency degradation under fault conditions, should be provided.

8. The quality of Figures 5–12 should be further improved. Some axis labels, legends, and annotations are difficult to read, particularly those in Figures 5–7. It is recommended that these figures be redrawn with higher resolution and appropriately enlarged fonts to improve readability.

Author Response

Reviewer 3

Comment 1: The novelty and specific contributions of this study are not sufficiently clarified. Although the fault-tolerant capability of multiphase SRGs has been investigated, the differences between this work and existing studies should be clearly highlighted.

Response

Thank you for this comment. The Introduction has been revised to clearly define the objective and contribution of the study. The revised manuscript now emphasizes that the work focuses on system-level modeling and performance analysis of a four-phase SRG under healthy and single-phase exclusion conditions rather than proposing a new machine topology or control algorithm.

Revision

The following paragraph has been added to the end of the Introduction for clarity.

Comment 2: The references should be more carefully selected and discussed. Some references related to IPMSM and PM machines occupy a large proportion in the introduction, while the direct relationship with multiphase SRG fault-tolerant operation is limited.

Response

We agree with the reviewer. The Introduction has been revised to reduce the emphasis on IPMSM and PM-machine studies and to give greater attention to literature directly related to SRGs, multiphase machines, fault tolerance, wind-energy conversion, and SRG control.

Revision

The following paragraph has been added in the Introduction section to include more recent and relevant work.

Other less relevant references have been removed.

Comment 3: The mathematical modeling of the SRG should be improved. More details about the magnetic characteristics, lookup table construction, and parameter acquisition method should be provided.

Response

Thank you for this suggestion. The modeling section has been expanded to explain the magnetic characteristics used in the simulation and their relationship with current and rotor position. The source of the flux-linkage, co-energy, and static-torque data has also been explicitly stated.

Revision

The following paragraph and equations have been modified in the revised version.

For the linear magnetic approximation, the electromagnetic torque is expressed as

where is phase current, is phase inductance, and is rotor position. For the mechanical dynamics of the generator,

For the nonlinear magnetic model, the magnetic co-energy is given by

The electromagnetic torque can then be obtained from

where the derivative is taken with respect to rotor position while keeping the phase current constant.

Comment 4: Experimental validation is strongly recommended. The current results are only obtained through MATLAB/Simulink simulations, and the effectiveness of the proposed analysis under practical operating conditions has not been verified.

Response

We appreciate the reviewer’s suggestion. We agree that experimental validation would strengthen the study. However, the present work is limited to MATLAB/Simulink simulation and does not include an experimental prototype. We have therefore clarified this limitation and removed any wording that could imply experimental validation. Experimental implementation is identified as future work.

Revision

It is clarified in the Conclusion section that the scope of this work so far is on simulation studies. The extension work including experiment is described as future work.

Comment 5: Only single-phase exclusion fault is considered in this manuscript. More comprehensive fault scenarios, such as different failed phases, multiple-phase faults, and converter faults, should be investigated.

Response

We agree that the present investigation is limited to single-phase exclusion. To maintain the scope of the current study, we have clarified this limitation rather than claiming comprehensive fault coverage. Additional phase, multiple-phase, and converter faults are identified as possible future research directions.

Revision

The following text as second paragraph of the section 3 clarifies the limited study scope:

“Investigated single-phase exclusion fault. Therefore, the results should be interpreted as a focused assessment of phase-exclusion behavior rather than a comprehensive evaluation of all possible wind-speed and fault conditions.”

Comment 6: The control strategy of the SRG converter is insufficiently described. The design principle and parameter selection of the excitation control and current control should be explained in detail.

Response

Thank you for this observation. The description of the converter-control system has been expanded to explain the function of the speed-control loop, excitation control, and phase-current regulation. The purpose of the control blocks and their relationship with the SRG operating condition are now described more clearly.

Revision

At the end of section 2, we have described in addition about the control strategy as following.

"The converter control regulates the generator excitation according to the rotor operating condition. The speed-control loop compares the reference and measured rotor speeds and generates the corresponding current/excitation reference. The phase-current control regulates the excitation current of the active phases, while the excitation-angle control determines the appropriate switching interval for each phase. During the investigated phase-exclusion condition, the faulty phase is removed from excitation and the remaining phases continue to operate through the converter control system."

Comment 7: The simulation results are mainly presented by waveform comparison, while quantitative analysis is insufficient. More performance indexes, such as torque ripple ratio, output power variation, and efficiency degradation under fault conditions, should be provided.

Response

We appreciate this suggestion. The results section has been revised to provide a more quantitative description wherever values can be directly obtained from the existing simulation results. At the same time, efficiency degradation has not been claimed because a complete loss model and corresponding efficiency calculation were not included in the present study. The manuscript now identifies this as a limitation.

Revision

Table 2 has been added as summarizing the performance results.

More description has been added in section 3 in the revised version.

Comment 8: The quality of Figures 5–12 should be further improved. Some axis labels, legends, and annotations are difficult to read, particularly those in Figures 5–7. It is recommended that these figures be redrawn with higher resolution and appropriately enlarged fonts to improve readability.

Response

Thank you for this helpful comment. Figures 5–12 have been reformatted using the existing simulation results. The font sizes, line widths, legends, axis labels, and resolution have been improved to enhance readability.

Revision

Figures 5, 6, 7, and 9 have been replaced with clear waveforms and readability enhancement.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Review_Report

The manuscript entitled “Performance Analysis and Modeling of a Multiphase Switched Reluctance Generator under Fault Conditions for Wind Energy Applications” presents the modeling and performance analysis of a multiphase switched reluctance generator for wind-energy applications under normal and phase-fault conditions. The investigation of phase exclusion and the resulting changes in current, torque, voltage, and flux characteristics is relevant to the reliability of wind-energy conversion systems. The manuscript is generally suitable for publication; however, several issues should be addressed before acceptance. In particular, the presentation and quality of the figures require substantial improvement.

In Figures 5–12, many axis labels, tick values, legends, and annotations are too small to read comfortably at the manuscript's normal viewing size. This is particularly evident in the multi-panel figures. The authors should regenerate these figures with larger fonts, thicker lines where appropriate, clearer legends, and higher resolution. All labels and numerical values should remain easily readable.
Particularly, figure 5 (c) is difficult to read. Figure 12 (b), the x and y labels are missing. The authors should work on the representation of the figures.
Another issue I noticed that the simulation methodology is not discussed, I suggest it should be described in greater detail to ensure reproducibility. Moreover, the authors should provide proper details regarding the numerical implementation, including the MATLAB/Simulink solver, time-step size, and whether the obtained transient results are independent of the selected time step.
The fault-condition analysis is an important part of the manuscript. The authors show that phase exclusion increases the current demand in the remaining phases and produces noticeable torque ripple while continuous operation is maintained. It would strengthen the paper if the authors provided a concise quantitative comparison between healthy and faulty operation, for example in a table showing torque ripple, average torque, peak/RMS current, speed deviation, or other relevant performance indicators.
The mathematical formulation should be carefully rechecked. In particular, Equations (5) and (6) appear to omit the factor 1/2 in the electromagnetic energy-conversion and torque terms. For a linear SRM model, the electromagnetic torque is conventionally expressed as Te=21i2(dL/dθ). In addition, Equation (7) is written in terms of dω/dθ, whereas the conventional mechanical dynamics are expressed as J(dω/dt)=Te−TL (with an additional damping term if considered). The authors should rederive these equations and clarify the assumptions used, particularly because SRG flux linkage is generally nonlinear and depends on both current and rotor position.

The manuscript requires careful English-language editing. There are several awkward or unclear sentences throughout the text, particularly in the discussion of fault conditions. For example, the explanation of recovery following phase exclusion is difficult to follow. The authors should thoroughly proofread the manuscript for grammar, sentence structure, and technical clarity.
The Conclusion should be strengthened by reporting the principal quantitative findings rather than mainly providing general statements regarding the benefits and potential applications of multiphase SR machines. The authors should summarize the numerical effects of phase exclusion on torque, current, speed, and other important performance parameters and briefly state the limitations of the present simulation study.

Author Response

Reviewer 4

The manuscript entitled “Performance Analysis and Modeling of a Multiphase Switched Reluctance Generator under Fault Conditions for Wind Energy Applications” presents the modeling and performance analysis of a multiphase switched reluctance generator for wind-energy applications under normal and phase-fault conditions. The investigation of phase exclusion and the resulting changes in current, torque, voltage, and flux characteristics is relevant to the reliability of wind-energy conversion systems. The manuscript is generally suitable for publication; however, several issues should be addressed before acceptance. In particular, the presentation and quality of the figures require substantial improvement.

Comment 1: In Figures 5–12, many axis labels, tick values, legends, and annotations are too small to read comfortably at the manuscript's normal viewing size. This is particularly evident in the multi-panel figures. The authors should regenerate these figures with larger fonts, thicker lines where appropriate, clearer legends, and higher resolution. All labels and numerical values should remain easily readable.

Response

Thank you for pointing out these presentation issues. The figures have been reformatted using the existing simulation results with larger fonts, clearer legends, improved line widths, and higher resolution.

Revision

Figures 5, 6, 7, and 9 have been replaced with clear waveforms and readability enhancement.

Comment 2: Particularly, figure 5 (c) is difficult to read. Figure 12 (b), the x and y labels are missing. The authors should work on the representation of the figures.

Response

We agree with the reviewer. Figure 5(c) has been enlarged and reformatted for improved readability.

Revision

Figures 5, 6, 7, and 9 have been replaced with clear waveforms and readability enhancement.

Comment 3: Another issue I noticed that the simulation methodology is not discussed, I suggest it should be described in greater detail to ensure reproducibility. Moreover, the authors should provide proper details regarding the numerical implementation, including the MATLAB/Simulink solver, time-step size, and whether the obtained transient results are independent of the selected time step.

Response

Thank you for this suggestion. The simulation methodology has been expanded to provide the available information regarding the MATLAB/Simulink implementation, simulation conditions, model initialization, and numerical settings. The manuscript now clearly identifies the simulation-based nature of the results. A separate time-step sensitivity analysis was not performed in the present study and has therefore not been claimed.

Revision

The following description explaining the simulation condition has been added at the starting of section 3:

The SRG system was implemented and simulated in MATLAB/Simulink. The simulation includes the wind-energy conversion system, converter, excitation control, and nonlinear SRG model. The initial conditions and operating conditions were selected according to the machine and system parameters listed in Table 1. The simulation results presented in this study were obtained using the numerical settings implemented in the developed Simulink model. Since a separate numerical time-step sensitivity study was not performed, numerical independence from the selected time step is not claimed.

Comment 4: The fault-condition analysis is an important part of the manuscript. The authors show that phase exclusion increases the current demand in the remaining phases and produces noticeable torque ripple while continuous operation is maintained. It would strengthen the paper if the authors provided a concise quantitative comparison between healthy and faulty operation, for example in a table showing torque ripple, average torque, peak/RMS current, speed deviation, or other relevant performance indicators.

Response

Thank you for this useful suggestion. A concise comparison of healthy and faulty operation has been added using the performance quantities available from the existing simulation results. The table provides a direct comparison of the operating speed, torque, current, and output-power characteristics without introducing additional simulation cases.

Revision

Added Table 2 in this regard to summarize the results and such parameters as mentioned in this comment.

Comment 5:

The mathematical formulation should be carefully rechecked. In particular, Equations (5) and (6) appear to omit the factor 1/2 in the electromagnetic energy-conversion and torque terms. For a linear SRM model, the electromagnetic torque is conventionally expressed as Te=21i2(dL/dθ). In addition, Equation (7) is written in terms of dω/dθ, whereas the conventional mechanical dynamics are expressed as J(dω/dt)=Te−TL (with an additional damping term if considered). The authors should rederive these equations and clarify the assumptions used, particularly because SRG flux linkage is generally nonlinear and depends on both current and rotor position.

Response

Thank you for carefully identifying these issues. The mathematical formulation has been rechecked and corrected. The factor has been included in the electromagnetic torque expression for the linear inductance model, and the mechanical equation has been written with respect to time. The nonlinear magnetic characteristics used in the simulation are also clarified through the flux-linkage relationship with current and rotor position.

Revision

The equations have been corrected in the revised version of the manuscript. The following co-energy model can be explained in this regard.

For the linear magnetic approximation, the electromagnetic torque is expressed as

where is phase current, is phase inductance, and is rotor position. For the mechanical dynamics of the generator,

For the nonlinear magnetic model, the magnetic co-energy is given by

The electromagnetic torque can then be obtained from

where the derivative is taken with respect to rotor position while keeping the phase current constant.

The revised manuscript also includes the following after for explanation.

“The nonlinear magnetic characteristics used in the simulation are represented through the relationship ψ=ψ (ⅈ, θ), the phase flux linkage, which depends on ⅈ the phase current. The flux-linkage, co-energy, and static-torque data used in the model were adopted from the published SRM input-data set reported in [40]. These data are incorporated into the simulation as magnetic characteristic inputs and are used to determine the electromagnetic response as a function of current and rotor position. Thus, the model accounts for the nonlinear magnetic characteristics represented by the supplied data rather than assuming a constant inductance.”

Comment 6: The manuscript requires careful English-language editing. There are several awkward or unclear sentences throughout the text, particularly in the discussion of fault conditions. For example, the explanation of recovery following phase exclusion is difficult to follow. The authors should thoroughly proofread the manuscript for grammar, sentence structure, and technical clarity.

Response

Thank you for this comment. The manuscript has been thoroughly proofread to improve grammar, sentence structure, technical clarity, terminology, and logical flow. Redundant and promotional expressions have been removed, particularly from the discussion of fault operation.

Revision

Following are the revised parts.

Section 5.1, paragraph 1: “It is simple to see that the machine initially struggles to maintain a steady torque with a noticeable ripple during phase loss transients.”

Revise to: “Following phase exclusion, the generator exhibits a transient change in electromagnetic torque and torque ripple as the remaining active phases respond to the loss of one phase.”

Section 5, last paragraph: “One of the key conclusions from this result is that, because of SRM's unique design, which allows for independent control of each phase and increases operational flexibility, a well recovery time taking into account the phase exclusion caused by fault and torque becomes stable in addition to speed at times very close to fault times.”

Revise to: “Following phase exclusion, the generator exhibits a transient change in torque and speed before reaching a new operating condition. The independent phase structure allows the remaining phases to continue excitation after the fault.”

Section 5.1, second paragraph: “In the absence of this, the converter's lifespan would be severely shortened and the windings would be strained.”

The sentence has been deleted which was redundant.

Section 4, first paragraph: “The results show that adding the SRM to wind energy systems offers some great insights into output voltage and current characteristics.”

Revise to: “The simulation results characterize the output voltage and current of the SRG-based wind-energy conversion system.”

Section 6, first paragraph: “The study highlights shortcomings in the designs that are already in use and shows how multi-phase layouts enhance performance, paving the way for the development of even more dependable and efficient energy conversion systems.”

Revise to: “The results characterize the changes in generator current, torque, speed, and voltage following single-phase exclusion.”

Comment 7: The Conclusion should be strengthened by reporting the principal quantitative findings rather than mainly providing general statements regarding the benefits and potential applications of multiphase SR machines. The authors should summarize the numerical effects of phase exclusion on torque, current, speed, and other important performance parameters and briefly state the limitations of the present simulation study.

Response

We agree with the reviewer. Thank you for the valuable comment. The manuscript has been revised to provide a clearer comparison of the SRG performance under healthy and single-phase exclusion conditions. A comparison table (Table 2) has been added to summarize the main performance parameters obtained from the existing simulation results. The Conclusion has also been revised to focus on the observed results and to clearly state the limitations of the present study. General statements regarding the benefits of the proposed system have been reduced.

Revision

Following Table has been added as Table 2 in the revised version.

Table 2. Performance parameters of SRG under normal and fault condition

Parameter	Normal Value	Fault Condition Value	Unit
Operating / reference speed	800 and 1500	800 and 1500	rpm
Rotor speed (actual, steady state)	220–330	220–330	rpm
Power Output	61	12	W
Steady-state peak phase current	40	75	A
Torque transient peak (startup)	−97	-	Nm
Steady-state torque ripple band	0 to −75	−0.6 to +0.16 per active phase	Nm
WEC total torque	80	-	%
Generator total torque ripple	65	-	%
Applied phase / switched voltage	±200	±100	V
Average torque (WEC-side)	6.5	Reduced and less stable during transient	Nm
Average torque (generator-side)	−1.9	−0.4 per phase	Nm
Active phases	4	3	-

Added text in the revised paragraph of the Conclusion section is given below.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I think this manuscript can be considered to be published.

Author Response

Comment: I think this manuscript can be considered to be published.

Response: We sincerely thank the reviewers for the careful evaluation of our manuscript and for providing valuable comments and suggestions.

Reviewer 2 Report

Comments and Suggestions for Authors

The paper is acceptable.

Author Response

Comment: The paper is acceptable.

Response: We sincerely thank the reviewers for the careful evaluation of our manuscript and for providing valuable comments and suggestions.

Reviewer 3 Report

Comments and Suggestions for Authors

I have no further comments

Author Response

Comment: I have no further comments

Response: We sincerely thank the reviewers for the careful evaluation of our manuscript and for providing valuable comments and suggestions.

Reviewer 4 Report

Comments and Suggestions for Authors

I did not see any significant improvement in the figures. The author needs to take this as a major comment. Still, it's difficult to read the x and y axis labels and numbers in most of the figures.

Also, figure 12 (b) is missing the x- and y-axis labels. Figure font size should be readable without zooming in too much. I suggest the authors fix these issues before publication.

Author Response

Comment: I did not see any significant improvement in the figures. The author needs to take this as a major comment. Still, it's difficult to read the x and y axis labels and numbers in most of the figures. Also, figure 12 (b) is missing the x- and y-axis labels. Figure font size should be readable without zooming in too much. I suggest the authors fix these issues before publication.

Response:
Thank you for this important comment. We have carefully revised all figures showing results from Figure 5 to 12 to improve their readability and presentation. The axis labels, numerical scales, font sizes, line widths, and legends have been adjusted throughout the manuscript. In particular, the missing x- and y-axis labels in Fig. 12(b) have been added. These revisions have been made to ensure that the figures can be clearly read without excessive zooming.

Revision:
Figures 5 to 12 have been revised accordingly, including Fig. 12(b) for improved clarity and readability.