Implementation of an Accurate Measurement Method for the Spatial Distribution of the Electromagnetic Field in a WPT System
Round 1
Reviewer 1 Report
In this paper, a method is proposed to estimate the EMF value between each measured point by measuring enough points combined with linear spatial interpolation method, so as to realize the measurement of the spatial magnetic field generated by the transmitting coil, and the corresponding calibration scheme is proposed for the measurement. There are some questions and suggestions:
1. In the case of measuring enough points, will the fitting method be more accurate and advantageous than the linear spatial interpolation method ?
2. When the receiving coil exists, will the excitation change, and will the H vector direction of any point near the transmission space remain unchanged ?
Author Response
Hello,
thanks very much for your valuable time spending on reviewing this manuscript and I and both co-authors appreciate your comments, which help us to improve the manuscript.
We have carefully studied your comments, and a number of necessary changes were made in the revised manuscript based on your comments.
We believe that these changes fulfill the recommendations from reviews.
In the next, we provide point-by-point responses to your comments and remarks.
- The final goal of this research is the development a system for measuring the configuration of the electromagnetic field generated by the WPT emitter coil, which will help at the WPT coils design (emitter and receiver). For this, it is necessary to determine the field values at each points in the neighboring space (see the attached screenshot - field distribution.pdf). No matter how many points the measurement is made, the approximation for the intermediate points is still necessary. It is debatable whether linear spatial interpolation is the most suitable for this. In our experiment we achieved about 5 measured points per second, with a total time of the scanning process of about 6 hours. If we reduce the distance between the measured points by half, then the total scanning time would increase eight times (48 hours). The distance between points remains to be estimated for each system.
- The presence of the receiver coil influences the field structure (module and direction of the H vector) both due to the ferrite base and due to the current value in the receiver. As we confirmed above, the actual (in real time) determination of this is the final goal. However, these aspects are beyond the scope of this work at this stage.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper focuses on the development of a high-precision magnetic field measurement path for wireless power transmission (WPT) systems. The authors consider possible sources of error in a path consisting of a sensor, amplifier, RMS-DC converter, and ADC, and introduce corrections to improve the accuracy of the entire measurements. Although the study appears to be a subject of an urgent applied research, there some questions and remarks appear.
1.The introduction is an abstract of papers [1]-[13], with the role of the authors' current work and contributions presented in one sentence. I believe that the introduction needs to be substantially revised, focusing on the relevance of the research. The authors' contributions need to be strengthened. I would offer a list of 3 items, reflecting the novelty and significance of this work.
2.It is difficult to make a conclusion about the significance of the obtained results, because: a) the authors do not give a circuit diagram of the analog part of the measuring path; b) the authors do not present the correction algorithm in the form of a clear block diagram; c) the authors do not compare their results with the sensor accuracy before correction, and also with the accuracy of alternative sensors presented in the works of other authors or existing in the market as ready-made devices (for example, MEMS chips QMC5883L and other). This should be done in the Discussion section.
3.Figures 19 and 20 show data supposedly "before and after correction", but only one line is shown. The second curves should be added.
4.Also, the quality of the bench photo (Fig. 22b) does not meet my seeing of an illustration quality for a current-date highly rated scientific journal. Similar CNC measurement systems have been presented in lots of recent papers on electromagnetic field research for WPT and sensors with much better photos quality, e.g.: 10.3390/en15165764, 10.3390/s22145212, 10.1109/ACCESS.2020.3015176.
5. Also, of the 17 papers in the references, only 4 have been published in the last 3 years. I recommend expanding this list with newer works, such as selecting from those listed above, to strength the contribuion.
Author Response
Hello,
thank you very much for your valuable time on reviewing this manuscript and we appreciate your comments which help us to improve the proposal.
We have carefully read your comments and observations, and based on your recommendations, we have made the necessary corrections in the revised manuscript.
We believe that these changes fully meet all the comments in the reviews. In what follows, we provide point-by-point answers to your comments.
1.The introduction has been modified by removing the less relevant references to our paper. Also, in the introduction, our different approaches have been highlighted and in the Discussion section we have shown the improvements made by our research.
2.a. The analog processing of the signals is done according to the block diagrams shown in figures 2, 4, 8 and 15. The circuit diagram used is not relevant for the paper. This is based on the typical usage schemes presented in the datasheets of the integrated circuits AD823 for amplification and filtering, 4052 for analog multiplexing and AD636 for rms-to-dc conversion. We specified these in the paper.
2.b. The measurement algorithm involves initial calibration and corrections applied to the measured data, is presented in detail in subsections 3.1 – 3.6. The sequence of operations can be found in fig. 23.
2.c. Linearity corrections and compensation of slow variations are inherent in the measurement process. If the geometric correction was not applied, the results would be erroneous. The size of these errors can be found in figures 19 and 20. In the Discussion section we introduced a reference to the QMC5883L chip.
- The data presented in figures 19 and 20 represent statistically the errors corrected by applying the algorithm. According to it, the titles of these figures have been modified.
- The bench photo (Fig. 22b) have been replaced with a more adequate one.
- We expanded the References with the recommended papers.
Reviewer 3 Report
The manuscript presents research related to improving the efficiency of systems for wireless transmission of electrical energy, based on the application of a new method for determining the spatial distribution of the emitter's electromagnetic field. The advantages of the proposed measurement method are proven by results of research on a prototype. The topic of the manuscript is topical. Overall, the work is well written and structured and my overall rating is positive. My main observations and comments are as follows:
- I would recommend the authors, on the basis of the dependences obtained through measurements, to create and implement in a suitable program environment the mathematical model of the investigated device. Thus, by applying an optimization procedure to a certain objective function, optimal values needed for the design of the emitter and receiver would be obtained;
- an in-depth analysis and commentary of the obtained results should be made and the effects of the research should be emphasized. In this sense, I recommend adding a conclusion section to summarize and analyze the obtained results;
- it would be useful, in addition to the advantages in the conclusion section, for the authors to comment on the disadvantages of the proposed diagnostic method. In this way, a complete picture of its qualities, capabilities and application limitations will be obtained.
Author Response
Hello,
thank you very much for your valuable time spending to review this manuscript and we appreciate your recommendations which help us to improve the proposal.
We have carefully read your comments, and based on your observations, we have made the necessary corrections in the revised manuscript.
We believe that these changes fully meet all the comments in the reviews. In what follows, we provide pointed answers to your remarks.
– The development of a system to facilitate the transmitter and receiver design of an WPT system is the final goal of our research. In this paper, the researches carried out in this regard are not presented, they go beyond the framework of the paper, because it is focused on the in-situ measurement method.
- The measurement method developed by us can be used for many WPT systems with inductive power transfer. The obtained results refer to the measurements in many points. For some points, the data are presented in Table 1. In order to exemplify the measurements in the case of a WPT emitter coil, we presented the values of the electromagnetic field from a plane in the figure 25. These, together with those presented in the Discussion section, demonstrate the validity of the method. A presentation of the measurement results for the entire scanned space is difficult to achieve in this paper. (see attached picture)
- In the Discussion section, we introduced some of the identified problems and the ways to solve them in further research.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Dear authors, thank you very much for your work on the correction of your article. Most of the comments have been taken into account in the revised version of the paper. Unfortunately, there are still some issues there.
1. The introduction is still a bit loose text without a clear narrative vector, despite significant improvements and, particularly, a clear indication of the contribution were made. While reading, the attention leaps from one article you describe to another. I recommend shortening the introduction by one page. The descriptions of most articles should be reduced as much as possible, and only the most relevant ones should remain unchanged.
2. In the section on improving accuracy, you write: "If the geometric correction were not applied, the results would be incorrect. " But this is a trivial point. I would recommend you quantifying it, e.g. by describing the results shown in Figures 19 and 20. Moreover, I would suggest you to add a "Conclusion" section, in which you briefly list the results you've obtained and quantify them in the main.
3. I do not agree that the circuit diagram of the measurement system is not relevant to your work. For me personally, and I am sure for many readers, it is relevant. It would allow readers to clearly see which stages of the signal processing are done in an analogue way, and which coefficients and filter parameters are used for this.
I also recommend working on the English language and grammar. There are some problematic passages.
Author Response
Many thanks for your relevant / valuable suggestions to improve the proposed contribution.
1. We have significantly shortened (with ca.1 page) the introduction and focused it strictly on the topics related to our research (following the narrative vector related to EMF measurement concepts). We have kept two most recent standards in the field [5], [6] to have reference principles and we have added the works recommended by you [3], [14] and [15]. For each invoked/cited contribution we have inserted similarities and differences with our proposed concept.
- According to your recommendation, the subsection 3.6 has been modified by:
- addition of a sentence explaining the reason for the geometric correction
- a description of the results shown in Figures 19 and 20.
In section 4 has been added a reference/comment to the circuit diagram.
Also added with a “Conclusions” section.
3.We recognize the importance of the electronic schematics in detail, so to allow readers to clearly see the stages/path of signal processing performed in analog mode, as well as the values of the components we have inserted the analog diagram at the end of our paper. (Addition of Appendix B)
For edification we have added two sets of measurements (excel tables) obtained at the stand described in the paper (sequences with numerical values in two perpendicular planes yOz and xOz - through the center of the plane coil).
Measurements are taken by precisely determined points at 2 mm intervals. The volume scanned in space consists of 100x100x80 mm. The measured data files (Table *) contain the values delivered by 3D-sensor, captured in the vertical slice (plane). The measurements are in a meta file that contains points from the whole half-space, i.e. 51 slices at 2mm.
A data sheet of the investigated planar coil is also attached. (photos inclusive)
The authors.
Author Response File: Author Response.pdf
Reviewer 3 Report
The authors have responded to my remarks and recommendations. I have no further comments.
Author Response
Hello,
thank you for your suggestions and appreciation as well as for the positive review
