Optimization of the Relay Coil Compensation Capacitor for the Three-Coil Wireless Power Transmission System
and Pengcheng Du 3,*
Round 1
Reviewer 1 Report
The paper proposes the optimization design of the compensation capacitor of the relay coil in a three-coil wireless power transfer system to improve the system. The argument is topical and the paper may be of interest. I have a mandatory comment: there is not any figure relating the geometry of the system in which the various geometrical parameters can be observed. It is necessary to add one or more precise figures in which these parameters are reported for the various configurations of the coils (please, refer to section 2). How are the mutual coupling coefficients (M_ij and k_ij) computed? Is the load purely resistive and why? How are equations (1), (3-6) obtained? Mathematical development supporting the various equations (9-17) should be briefly explained and reported in an Appendix. Explanation about the computing of scattering parameters should be added. In fig. 10 ideal L-C components are depicted: are the resistive/parasitic effects of real components and of interconnects negligible? If not, how do they influence the real performance of the system?
Minor editing of English language required.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper explores the optimization of compensation capacitor values for relay coils in a three-coil wireless power transmission system. It discovers that three-coil systems differ from two-coil ones, achieving maximum power and efficiency with compensation capacitors smaller than but not equal to the resonant capacitor. The paper derives optimal capacitor values for relay coils, proposes a design method based on dynamic loads, and addresses coil displacement issues with a variable compensation capacitor circuit. This article may be considered for publication with minor revisions.
1- Consider breaking the introduction section into smaller paragraphs to improve readability.
2- The importance of relay coils is well-explained, but you might consider adding a brief sentence or two about their applications in practical scenarios to illustrate their significance more vividly.
3- Provide a bit more detail on the mathematical challenges faced by researchers in this area?
4- Consider explicitly stating what makes three-coil systems novel or superior in addressing the challenges you've mentioned.
5- When discussing the increase in electromagnetic radiation due to relay coils, consider elaborating on the potential consequences. Does this radiation pose health risks, interfere with other electronic devices, or have regulatory implications? Providing more context here would be valuable.
6- Mention briefly about coil array in WPT systems (refer to DOI: 10.3390/en15228643)
7- It's essential to explain why cross-coupling is significant and how it affects the system's performance.
8- You mention that cross-coupling cannot be ignored when the distance (h1) between the transmit coil and the relay coil is not large enough. Can you define what constitutes a "large enough" distance in practical terms?
9- Clarify the purpose of the optimization process for the compensation capacitor (C2).
10- Consider discussing the sensitivity of the system's performance to changes in the compensation capacitor and load resistance RL.
11- Elaborate on the significance of the 2% improvement in transmission efficiency compared to the highest theoretical value.
The English writing in this text is clear and technically sound, but it could be improved for readability and conciseness.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 3 Report
The manuscript presents research related to improving the performance of a wireless power transmission (WPT) system based on the application of an optimization procedure. In this aspect, the work is useful and has a great impact on the development of these systems, which are increasingly being used in various fields. The main advantages of the presented engineering development are related to improving the efficiency of the device under consideration. The manuscript is on a current topic and has great potential for development. My main observations and comments are as follows:
- it would be useful, in addition to the advantages in the conclusion section, for the authors to comment on the disadvantages of the proposed optimization method and the system used in general. In this way, a complete picture of its qualities, capabilities and application limitations will be obtained;
- as many symbols and abbreviations are used in the text, I recommend authors to add a list of symbols used at the beginning or end of the manuscript.
- I recommend adding a discussion section, where a thorough analysis and conclusions can be made based on the presented results;
- I recommend presenting the results of experiments with a laboratory prototype. In this way, the presented analytical ratios used in modeling and optimization will be verified.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The author have successfully improved the paper that, in my opinion, can be now considered for publication. Thank you.
Reviewer 3 Report
The authors revised the manuscript according to my recommendations and comments. I have no further comments.
