A Unified Approach to the Analysis of DC/AC Converters, Based on the Study of Electromagnetic Processes in a Series RLC Circuit

Round 1

Reviewer 1 Report

Some typo correction

line 316 reference with comma 

308 there is a not clear symbol

figure 4 must be resized

the eqs must be all in the same font and size

Author Response

Answers to reviewers

First of all, I would like to thank you for your thorough review of my paper (electronics-2168444) and helpful comments to improve it.

 Reviewer 1

Comments to the Authors
Some typo correction

1. line 316 reference with comma
2. 308 there is a not clear symbol
3. figure 4 must be resized
4. the eqs must be all in the same font and size

 

To Reviewer 1:

            Thank you very much for your review and valuable remarks.

 

1. line 316 reference with comma.

- Thank you very much for the remark. The necessary correction has been made.

2. 308 there is a not clear symbol.

- Thank you very much. The necessary correction has been made. 

3. figure 4 must be resized.

- The figure has been redrawn.

4. the eqs must be all in the same font and size.

- All formulas have been revised and reformatted.

 Thank you very much for your remarks and comments. They were very useful for me to emphasize the main tasks and contributions of the manuscript, and also to focus the attention of the readers on the new and unique elements.

Reviewer 2 Report

In the paper there are a lot of equations whose analysis of correctness would require a very long time to check them. In my opinion, the author should illustrate the presented solutions by appropriately selected laboratory or simulation tests. There is a bit of a mess in the markings, for example UC(0)=(2К-1)Ud (line 241) is illegible for mines. In line 241 "K" is written italic and once standard font? There are a lot of such examples. In my opinion, all equations need to be corrected.

Line 257 and 376 – contains strange characters

The List of Abbreviations and Symbols would also be helpful.

Paper has potential, but it needs big changes.

Author Response

Answers to reviewers

First of all, I would like to thank you for your thorough review of my paper (electronics-2168444) and helpful comments to improve it.

Reviewer 2

Comments to the Authors

In the paper there are a lot of equations whose analysis of correctness would require a very long time to check them. In my opinion, the author should illustrate the presented solutions by appropriately selected laboratory or simulation tests. There is a bit of a mess in the markings, for example UC(0)=(2К-1)Ud (line 241) is illegible for mines. In line 241 "K" is written italic and once standard font? There are a lot of such examples. In my opinion, all equations need to be corrected.

Line 257 and 376 – contains strange characters

The List of Abbreviations and Symbols would also be helpful.

Paper has potential, but it needs big changes.

 

To Reviewer 2:

            Thank you for your review and valuable remarks.

 

1. In the paper there are a lot of equations whose analysis of correctness would require a very long time to check them. In my opinion, the author should illustrate the presented solutions by appropriately selected laboratory or simulation tests.?

- Thank you very much for your comment and suggestion. A new section has been added to the manuscript where several computational examples are presented. The emphasis of the present work is the formulation, presentation and verification of a generalized approach for the analysis of the main types of inverters, which allows to unify and formalize their design methodologies. This is the main contribution of the manuscript. The topic of a unified design methodology based on this approach will be the subject of my next manuscript, which I am currently preparing. In this regard, I am also preparing a monograph dedicated to the analysis, modeling and design of autonomous inverters, where rational methodologies for engineering design of the basic power circuits of DC/AC converters will be presented.

2. There is a bit of a mess in the markings, for example UC(0)=(2К-1)Ud (line 241) is illegible for mines. In line 241 "K" is written italic and once standard font? There are a lot of such examples. In my opinion, all equations need to be corrected.

- Thank you very much for your comment. All equations and coefficients have been reviewed, formatted and corrected.

3. Line 257 and 376 – contains strange characters

- Thank you very much. Necessary corrections have been made. 

4. The List of Abbreviations and Symbols would also be helpful.

- Thank you very much for the recommendation. Such a list has been added at the end of the manuscript.

5. Paper has potential, but it needs big changes.

- Thank you very much for the positive evaluation of my idea. The manuscript has been substantially revised, and I have tried to emphasize the new and original elements.

 Thank you very much for your remarks and comments. They were very useful for me to emphasize the main tasks and contributions of the manuscript, and also to focus the attention of the readers on the new and unique elements.

Reviewer 3 Report

Dear authors

The paper presents a Unified Approach to the Analysis of DC/AC Converters. However, much work must be done to present the idea. The comments are:

1.     The idea of the paper is not clear. List the actual contributions of the work.

2.     What are the benefits of this analysis?

3.     How is it compared to other techniques of analysis? Please provide case studies and numerical results.

4.     Simulations and numerical results are mandatory to verify the analysis. Or experimental work to support the idea.

 

5.     The sentence "As a result of the author's long-term research [22, 25, 29] " in the conclusion may be written in a CV, not in a research paper.

Author Response

Answers to reviewers

First of all, I would like to thank you for your thorough review of my paper (electronics-2168444) and helpful comments to improve it.

Reviewer 3

Comments to the Authors

Dear authors

The paper presents a Unified Approach to the Analysis of DC/AC Converters. However, much work must be done to present the idea. The comments are:

1. The idea of the paper is not clear. List the actual contributions of the work.
2. What are the benefits of this analysis?
3. How is it compared to other techniques of analysis? Please provide case studies and numerical results.
4. Simulations and numerical results are mandatory to verify the analysis. Or experimental work to support the idea.
5. The sentence "As a result of the author's long-term research [22, 25, 29] " in the conclusion may be written in a CV, not in a research paper.

 

 

To Reviewer 3:

            Thank you for your review and valuable remarks.

 

1. The idea of the paper is not clear. List the actual contributions of the work.

- Thank you very much for your comment. The main idea of the present work is the formulation, presentation and verification of a unified approach for the analysis of the main types of inverters, based on the study of electromagnetic processes in a series RLC circuit. The use of a generalized representation allows to unify and formalize their design methodologies as well. This is the main contribution of the manuscript. My next manuscript, which I am currently preparing, will be devoted to the topic of creating a unified methodology for designing the basic circuits of DC/AC converters, by using the presented approach. In this regard, I am preparing a monograph dedicated to the analysis, modeling and design of autonomous inverters, where rational methodologies for engineering design of the basic power circuits of DC/AC converters will be presented.

2. What are the benefits of this analysis?

- Thank you very much for the question. Based on the formulated generalized approach for the analysis of DC/AC converters, rational methods for designing the basic power circuits have been prepared. They allow relatively simple design ratios to be used while maintaining the required accuracy. In addition, the general description of the electromagnetic processes in a series RLC circuit makes it possible to unify the principle of operation of different power circuits, which is also useful in order to intensify and improve the teaching of power electronics.

3. How is it compared to other techniques of analysis? Please provide case studies and numerical results.

- Thank you very much for the suggestion. A new section has been added to the manuscript where several computational examples are presented. The emphasis of the present work is the formulation, presentation and verification of a generalized approach for the analysis of the main types of inverters, which allows to unify and formalize their design methodologies.

4. Simulations and numerical results are mandatory to verify the analysis. Or experimental work to support the idea.

- Thank you very much for the suggestion. A new section has been added to the manuscript where several computational examples are presented.

5. The sentence "As a result of the author's long-term research [22, 25, 29] " in the conclusion may be written in a CV, not in a research paper.

- I totally agree with your comment. I have inappropriately emphasized that this manuscript presents and summarizes my many years of research in the field of analysis of power electronic devices and systems. This passage has been edited.

 Thank you very much for your remarks and comments. They were very useful for me to emphasize the main tasks and contributions of the manuscript, and also to focus the attention of the readers on the new and unique elements.

Reviewer 4 Report

This paper developed a unified method to analysis of several types of DC-AC inverters. The reviewers has the following concerns.

 

1. The unified method mentioned in the title seems to represent the AC circuit as a series RLC circuit. It is better to make the title clearer by including this information in the title.

2. It is better to further include one paragraph at the end of the introduction section, which descirbes brifely the contents of the following sections.

3.  In equation (2), the letter d should be at the subscript.

4. The single-phase DC-AC inverters are studied in this paper. It is better to discuss if the proposed unified method is applicable for three-phase DC-AC inverters or not.

5. The verification of the unification method developed in Section 3 is missing. It is better to further have simulation or experimental verifications after Section 3.

6. What is purpose of the proposed unified method. Please provide some application scenarios.

Author Response

Answers to reviewers

First of all, I would like to thank you for your thorough review of my paper (electronics-2168444) and helpful comments to improve it.

Reviewer 4

Comments to the Authors

This paper developed a unified method to analysis of several types of DC-AC inverters. The reviewers has the following concerns.

1. The unified method mentioned in the title seems to represent the AC circuit as a series RLC circuit. It is better to make the title clearer by including this information in the title.
2. It is better to further include one paragraph at the end of the introduction section, which descirbes brifely the contents of the following sections.
3. In equation (2), the letter d should be at the subscript.
4. The single-phase DC-AC inverters are studied in this paper. It is better to discuss if the proposed unified method is applicable for three-phase DC-AC inverters or not.
5. The verification of the unification method developed in Section 3 is missing. It is better to further have simulation or experimental verifications after Section 3.
6. What is purpose of the proposed unified method. Please provide some application scenarios..

 

 

To Reviewer 4:

 

Thank you for your review and valuable remarks.

 

1. The unified method mentioned in the title seems to represent the AC circuit as a series RLC circuit. It is better to make the title clearer by including this information in the title.

- Thank you very much for your comment and suggestion. The title of the manuscript has been amended as follows: „A Unified Approach to the Analysis of DC/AC Converters, Based on the Study of Electromagnetic Processes in a Series RLC Circuit“

2. It is better to further include one paragraph at the end of the introduction section, which descirbes brifely the contents of the following sections.

– Thank you very much for the suggestion. Added a paragraph that describes the content of the manuscript.

3. In equation (2), the letter d should be at the subscript.

- Thank you very much for the remark. Corrected.

4. The single-phase DC-AC inverters are studied in this paper. It is better to discuss if the proposed unified method is applicable for three-phase DC-AC inverters or not.

- Thank you very much for the suggestion and the good idea! The proposed analysis approach is also applicable to three-phase DC/AC inverters. Of course, taking into account the specificity of the presence of three phases and, accordingly, their mutual influence in the formation of the output currents and voltages. A passage with similar content is included in the conclusion section of the manuscript.

5. The verification of the unification method developed in Section 3 is missing. It is better to further have simulation or experimental verifications after Section 3.

- Thank you very much for the suggestion. A new section has been added to the manuscript where several computational examples are presented. The emphasis of the present work is the formulation, presentation and verification of a generalized approach for the analysis of the main types of inverters, which allows to unify and formalize their design methodologies. This is also important with a view to achieving automation of the design process.

6. What is purpose of the proposed unified method. Please provide some application scenarios.

- Thank you very much for your comment. The main idea of the present work is the formulation, presentation and verification of a generalized approach for the analysis of the main types of inverters. This makes it possible to unify and formalize their design methodologies, which is important both from the point of view of power electronics training, and from the point of view of using automated design of power electronic devices, including based on the application of artificial intelligence techniques.

 Thank you very much for your remarks and comments. They were very useful for me to emphasize the main tasks and contributions of the manuscript, and also to focus the attention of the readers on the new and unique elements.

Reviewer 5 Report

Dear Authors,

 This paper developed a unified approach based on the generalized presentation of the AC circuit for analyzing DC/AC converters. Following are my comments.

 What ratio are you referring to in the introduction? Please clarify.

 The idea of the unified approach supporting the analysis of the electromagnetic processes seems to be the main theme of the paper. However, the idea is not clearly explained. Please provide more information in the introduction. Maybe you can compare the existing methodologies for analyzing the electromagnetic processes with the one using the unified approach.

 The following statement in the introduction is not clear. Please rewrite.

A country is more developed, the greater part of the electricity it consumes is converted with parameters.

 In the introduction paragraph, you mentioned AC/DC converter. Are you referring to AC/DC or DC/AC in this work or both?

 The following spelling on page-2 must be corrected.

“inductor tivity”

 You might want to replace the word “analyzes” with “analysis”

 In section-2 what coefficients are you referring to?

 What do you mean by the output diagonal of the inverter in section-2?

 In section-2, it has been mentioned that, that the load of the parallel inverter is capacitive in nature for industrial applications. But the load is mostly inductive for industrial applications. Please clarify.

 What do you mean by control frequency? Are you referring to switching frequency?

 How did you come up with the circuits in figure 2? Why does a resonant dc/ac converter with/without reverse diodes consists of series RLC? Please clarify.

 The applications and importance of resonant DC/AC converters are not established properly.

 On page 5, what do you mean by the coefficient ‘ν e’? It is not clear. Please clarify.

 If possible, explain the application of the unified approach for grid forming and grid following converters.

 Please compare the proposed unified approach with the existing methodologies in a tabular format.

 The advantages of the unified approach for power electronics education must be clearly explained.

 Please provide more details regarding the computational efficiency of the unified approach.

 More details must be provided regarding how the mathematical software based on the unified approach speeds up the process.

 If possible, provide simulation results to demonstrate the advantages of the unified approach.

Author Response

Answers to reviewers

First of all, I would like to thank you for your thorough review of my paper (electronics-2168444) and helpful comments to improve it.

Reviewer 5

Comments to the Authors

Dear Authors,

 This paper developed a unified approach based on the generalized presentation of the AC circuit for analyzing DC/AC converters. Following are my comments.

 What ratio are you referring to in the introduction? Please clarify.

 The idea of the unified approach supporting the analysis of the electromagnetic processes seems to be the main theme of the paper. However, the idea is not clearly explained. Please provide more information in the introduction. Maybe you can compare the existing methodologies for analyzing the electromagnetic processes with the one using the unified approach.

 The following statement in the introduction is not clear. Please rewrite.

A country is more developed, the greater part of the electricity it consumes is converted with parameters.

 In the introduction paragraph, you mentioned AC/DC converter. Are you referring to AC/DC or DC/AC in this work or both?

 The following spelling on page-2 must be corrected.

“inductor tivity”

 You might want to replace the word “analyzes” with “analysis”

 In section-2 what coefficients are you referring to?

 What do you mean by the output diagonal of the inverter in section-2?

 In section-2, it has been mentioned that, that the load of the parallel inverter is capacitive in nature for industrial applications. But the load is mostly inductive for industrial applications. Please clarify.

What do you mean by control frequency? Are you referring to switching frequency?

 How did you come up with the circuits in figure 2? Why does a resonant dc/ac converter with/without reverse diodes consists of series RLC? Please clarify.

 The applications and importance of resonant DC/AC converters are not established properly.

 On page 5, what do you mean by the coefficient ‘ν e’? It is not clear. Please clarify.

 If possible, explain the application of the unified approach for grid forming and grid following converters.

 Please compare the proposed unified approach with the existing methodologies in a tabular format.

 The advantages of the unified approach for power electronics education must be clearly explained.

 Please provide more details regarding the computational efficiency of the unified approach.

 More details must be provided regarding how the mathematical software based on the unified approach speeds up the process.

 If possible, provide simulation results to demonstrate the advantages of the unified approach.

To Reviewer 5:

 

Thank you for your review and valuable remarks.

 

1. What ratio are you referring to in the introduction? Please clarify.

- Thank you very much for your comment. With this passage, I wanted to emphasize that the basic ratios found are also useful with a view to creating engineering methodologies for design, in which the values of all circuit elements are determined with relatively simplified calculation procedures.

2. The idea of the unified approach supporting the analysis of the electromagnetic processes seems to be the main theme of the paper. However, the idea is not clearly explained. Please provide more information in the introduction. Maybe you can compare the existing methodologies for analyzing the electromagnetic processes with the one using the unified approach.

- Thank you very much for your comment. In the introduction section, a comment has been added regarding the main idea of the manuscript and a comparison with existing design methodologies has been added. The main advantage of the proposed unified approach is that, unlike other analysis methods, it describes the current through the AC circuit with its actual form.

3. The following statement in the introduction is not clear. Please rewrite.

A country is more developed, the greater part of the electricity it consumes is converted with parameters.

- Thank you very much for your comment. This text has been edited. The idea of this text was to emphasize the importance of energy conversion by means of power electronics in ensuring the well-being and prosperity of the individual and society as a whole.

4. In the introduction paragraph, you mentioned AC/DC converter. Are you referring to AC/DC or DC/AC in this work or both?

- Thank you very much for the remark. A technical error occurred and has been corrected. Only DC/AC converters are considered in the manuscript.

5. The following spelling on page-2 must be corrected.

“inductor tivity”

- Thank you very much for the remark. The text has been corrected.

6. You might want to replace the word “analyzes” with “analysis”

- Thank you very much for the remark. The text has been corrected.

7. In section-2 what coefficients are you referring to?

- Thank you very much for the remark. I mean the coefficients used in the analysis of the main types of DC/AC converters.

8. What do you mean by the output diagonal of the inverter in section-2?

- Thank you very much for the remark. I mean the AC circuit of the DC/AC converter. The text has been edited.

9. In section-2, it has been mentioned that, that the load of the parallel inverter is capacitive in nature for industrial applications. But the load is mostly inductive for industrial applications. Please clarify.

- Thank you very much for your comment. The load has a highly active-inductive nature (inductor and body that is heated). For this reason, parallel compensation with a load capacitor is required. In this way a parallel load circuit is formed which can be set to operate at resonance or out of tune. Typically, for thyristor turn-off considerations, this parallel resonant circuit is capacitive tuned.

10. What do you mean by control frequency? Are you referring to switching frequency?

- Thank you very much for your comment. That's right, the control frequency is actually the frequency at which semiconductor devices are switched. This is also reflected in the list of notations used, which was added during the editing of the manuscript.

11. How did you come up with the circuits in figure 2? Why does a resonant dc/ac converter with/without reverse diodes consists of series RLC? Please clarify.

- The idea of the unified approach is to be demonstrated on the basis of the most frequently studied power circuits, therefore for the resonant DC/AC converters it was chosen to be with series RLC circuits. Of course, it is also possible for this type of DC/AC converters to have a parallel load circuit, as in the case of the current inverter. My aim was to cover more representative topologies in this way because the parallel load loop structure is already discussed in the current source inverter analysis section.

12. The applications and importance of resonant DC/AC converters are not established properly.

- Thank you very much for your comment. The text has been edited.

13. On page 5, what do you mean by the coefficient ‘ν e’? It is not clear. Please clarify.

- Thank you very much for the remark. This is my spelling mistake. A correction has been made.

14. If possible, explain the application of the unified approach for grid forming and grid following converters.

- Thank you very much for your comment. The unified approach does not cover converters that inject energy into the grid. This clarification has been added in the introduction and conclusion sections.

15. Please compare the proposed unified approach with the existing methodologies in a tabular format.

- Thank you very much for your comment. Your idea is very good! Unfortunately, this is difficult to implement in the current manuscript, as it implies a large computational effort for the same starting data. I will include such a comparison in my next manuscript, which will be devoted to the development of engineering methodologies for designing the basic circuits of DC/AC converters.

16. The advantages of the unified approach for power electronics education must be clearly explained.

- Thank you very much for the suggestion. The main advantages are related to the fact that starting from the solution of the same differential equation (expression 2) with the use of different initial conditions and applying a different meaning to the same coefficients, all the basic circuits of DC/AC converters are described. Text with similar content has been added to the conclusion section.

17. Please provide more details regarding the computational efficiency of the unified approach.

- The unified approach does not claim to be more computationally efficient than other analysis methods. Its main advantage is the possibility to describe the electromagnetic processes in all basic schemes of DC/AC converters from single positions through the solution of the same system of differential equations.

18. More details must be provided regarding how the mathematical software based on the unified approach speeds up the process.

- Thank you very much for the question! The unified approach allows formalization of the computational process and on this basis, the application of automated design through mathematical software. A corresponding edit has been made in the text to emphasize this advantage of the proposed analysis approach.

19. If possible, provide simulation results to demonstrate the advantages of the unified approach.

 - Thank you very much for the suggestion. A new section has been added to the manuscript where several computational examples are presented and computer simulation results are summarized accordingly. The emphasis of the present work is the formulation, presentation and verification of a generalized approach for the analysis of the main types of inverters, which allows to unify and formalize their design methodologies.

Thank you very much for your remarks and comments. They were very useful for me to emphasize the main tasks and contributions of the manuscript, and also to focus the attention of the readers on the new and unique elements.

Round 2

Reviewer 2 Report

The paper has been revised by the author but I have to say that it is still bad.   The equations are still messy, for example equation 12. It is generally accepted that variables in equations are written in italic font, while in the paper it is different.   The added simulation studies using the LTSPICE program do not contain a simulation scheme. There are also no sample simulation results.   Therefore, in my opinion, the paper is still not ready for publication.

Author Response

Reviewer 2

Comments to the Authors

The paper has been revised by the author but I have to say that it is still bad.   The equations are still messy, for example equation 12. It is generally accepted that variables in equations are written in italic font, while in the paper it is different.   The added simulation studies using the LTSPICE program do not contain a simulation scheme. There are also no sample simulation results.   Therefore, in my opinion, the paper is still not ready for publication.

 

To Reviewer 2:

            Thank you for your review and valuable remarks.

 The equations are still messy, for example equation 12. It is generally accepted that variables in equations are written in italic font, while in the paper it is different.

- Thank you very much for your comment. All formulas and variables have been reviewed and edited.

2. The added simulation studies using the LTSPICE program do not contain a simulation scheme. There are also no sample simulation results.

- Thank you very much for the remark. Additionally, simulation results of all designed examples are presented. The simulation models of all DC/AC converters are also given in Appendix A.

 Thank you for your review and valuable remarks! Your comments, remarks and suggestions have been very helpful to me and have greatly improved the quality of the manuscript.

Reviewer 3 Report

Dear authors

Thanks for the improvements, however, some graphical simulation results must be added to the manuscript.

Author Response

Reviewer 3

Comments to the Authors
Dear authors

Thanks for the improvements, however, some graphical simulation results must be added to the manuscript.

  To Reviewer 3:

            Thank you for your review and valuable remarks.

 Thanks for the improvements, however, some graphical simulation results must be added to the manuscript.

- Thank you very much for the remark. Additionally, simulation results of all designed examples are presented. The simulation models of all DC/AC converters are also given in Appendix A.

 Thank you for your review and valuable remarks! Your comments, remarks and suggestions have been very helpful to me and have greatly improved the quality of the manuscript.

Reviewer 4 Report

Very well done! The paper can be published in the current form.

Author Response

Reviewer 4

Comments to the Authors
Very well done! The paper can be published in the current form.

To Reviewer 4:

Thank you for your review and valuable remarks! Your comments, remarks and suggestions have been very helpful to me and have greatly improved the quality of the manuscript.

Reviewer 5 Report

Dear Authors,

Thank you for answering all my queries.

 

Author Response

Reviewer 5

Comments to the Authors
Thank you for answering all my queries.

 To Reviewer 5:

Thank you for your review and valuable remarks! Your comments, remarks and suggestions have been very helpful to me and have greatly improved the quality of the manuscript.