Development of Magnetic Hysteresis Loop Measurement System for Characterization of 3D-Printed Magnetic Cores

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The quality of the figures is ridicuously low, even the BJT on schematic are not correctly drawn.

 

The following questions should be addresed in the text:

• why the authors try to build discrete amplifier, despite good integrated solutions exist
• indeed 2N3055  is ancient bjt developed in sixties or early 70 and is terribly slow. These makes the amplifier much worse than any integrated current solution.
• from the scientific point - there is nothing new in that circuit. It looks like a school project from the eighties.
• they could have used current source to drive the inductor
• what is the benefit of arbitrary voltage patterns. It is not needed for anything.

Comments on the Quality of English Language

The language is possible to understand, though numerous errors and omissions in the text are present.

Author Response

Dear Reviewer,

 Thank you for your work and comments, which helped us improve our paper's quality. You can find your questions and answers below: 

Q: The quality of the figures is ridicuously low, even the BJT on schematic are not correctly drawn.

A: Thank you for your comment, we have changed many figures and the schematic in the paper.

The following questions should be addresed in the text:

why the authors try to build discrete amplifier, despite good integrated solutions exist
indeed 2N3055  is ancient bjt developed in sixties or early 70 and is terribly slow. These makes the amplifier much worse than any integrated current solution.
from the scientific point - there is nothing new in that circuit. It looks like a school project from the eighties.
they could have used current source to drive the inductor
what is the benefit of arbitrary voltage patterns. It is not needed for anything.

A:
We appreciate the reviewer's observation regarding the use of discrete components, particularly the 2N3055 BJT, in our BH curve measurement device. We are indeed aware of more modern integrated amplifier solutions that offer higher bandwidth and improved linearity.

However, our design choices were guided by several practical and application-specific considerations:

    Power Handling and Simplicity:
    The BH curve measurement setup requires driving inductive loads with relatively high current levels in a controlled and predictable manner. The 2N3055, while an older component, remains a robust and inexpensive power transistor that is well suited for low- to mid-frequency applications involving inductive loads. In our case, its speed and gain characteristics are sufficient for the waveform frequencies involved in BH characterization.

    Thermal and Electrical Robustness:
    Compared to some integrated solutions, discrete power stages allow us to better manage thermal dissipation and component-level protections. This has contributed to a stable, long-term operation of the system without performance degradation.

    Design Transparency and Debuggability:
    Using a discrete design allowed us to have full visibility and control over each amplification stage. This was particularly helpful during development and calibration, where we needed to fine-tune driving conditions to match different core materials and excitation profiles.

    Arbitrary Voltage Patterns:
    While the reviewer notes that arbitrary voltage control is not strictly necessary, in our context, it provides flexibility in generating custom magnetization profiles for testing purposes, including non-sinusoidal or stepped waveforms. This has proven useful in exploring hysteresis behavior under non-standard excitation.

    Demonstrated Performance:
    Ultimately, the implemented design has shown reliable and repeatable performance in generating accurate BH curves. This confirms that despite the conservative component choices, the system fulfills its intended purpose effectively.

Reviewer 2 Report

Comments and Suggestions for Authors

This work presents the Development of a magnetic hysteresis loop measurement
system for characterization of 3D printed magnetic cores. The paper is acceptable for publication in the present form but some suggestions should be considered by the authors:
As the authors mentioned the several technical issues have to be solved:
- the operational amplifier circuits do not have a separate stabilized power supply;
- the offset and gain potentiometers are not precision;
Taking in mind these technical problems, in the future the authors will make the measurement system more precise.

Author Response

Thank you for your positive response.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors developed a hysteresis measurement system, aiming at reducing costs and with simple use, while maintaining the reproducibility of the measurement results. The manuscript is interesting for the advancement in the area of ​​monitored instrumentation. In addition, the manuscript is well written, with minor revisions for publication:

>The abstract must end by presenting the main conclusions or findings, indicating potential application;

>Page 2/3. Authors must clearly comment on the main intended contribution of the manuscript, the advances in the experimental area for monitoring magnetic behavior, the feasibility and potential for application in the electrical sector;

>Page 3. 1.1. Industrial equipment for hysteresis measurement of magnetic cores. I believe the authors should better address the materials used and recent advances in 3D printing, especially with ferrites that are not widely used;

>Page 5/6. Authors should make clear the criteria adopted for the parameters reported in the tables. Although some are known, I believe that making them explicit to readers would be beneficial;

>Page 8. “the output voltage of the amplifier follows Equation 2: an excitation signal of 1V results in an output voltage of 7.54V.” Discuss the practical importance of the result obtained;

> Results and discussion. Authors should provide a better basis for the discussion, detailing the meaning of the parameters analyzed, especially whether the results are comparable to commercial results, if possible, or whether they can be compared with other results in the literature;

Author Response

Dear Reviewer,

 Thank you for your time and comments, which helped us improve our paper's quality.  

Our changes indicated by blue colour in our paper, while you can find our point by point answers below: 

The authors developed a hysteresis measurement system, aiming at reducing costs and with simple use, while maintaining the reproducibility of the measurement results. The manuscript is interesting because of the advances in the area of monitored instrumentation. In addition, the manuscript is well written, with minor revisions for publication.

Q: The abstract must end by presenting the main conclusions or findings, indicating potential application;

A: Thank you for your question, the main goal during the research and development was to create a reliable and cheap measurement system for B-H curves, it is still mentioned at the end of the abstract, moreover it was extended to refer the applicability of the proposed electrical circuit.

Q: Page 2/3. Authors must clearly comment on the main intended contribution of the manuscript, the advances in the experimental area for monitoring magnetic behavior, the feasibility and potential for application in the electrical sector;

A: The goal of the paper is to present a low-cost, improved magnetic hysteresis measurement system tailored for characterizing 3D printed magnetic cores \cite{printedcore}, offering a simpler alternative to conventional complex setups. The design incorporates targeted circuit enhancements—such as improved amplifier stability, active current limiting with feedback, and optimized frequency response—making it suitable for reliable B-H curve acquisition in research and prototyping environments. This work addresses the practical need for accessible instrumentation in the testing of novel magnetic materials.

Q: Page 3. 1.1. Industrial equipment for hysteresis measurement of magnetic cores. I believe the authors should better address the materials used and recent advances in 3D printing, especially with ferrites that are not widely used;

A: The magnetic behaviour of the examined 3D printed iron cores was presented in a previous study, and their applicability remains an active area of academic research. This study contributes to that effort by introducing and validating a dedicated measurement system tailored to their characterization.

Q: Page 5/6. Authors should make clear the criteria adopted for the parameters reported in the tables. Although some are known, I believe that making them explicit to readers would be beneficial;

A: This has been corrected in the article (in blue letters). Thank you for your feedback!

Q: Page 8. “the output voltage of the amplifier follows Equation 2: an excitation signal of 1V results in an output voltage of 7.54V.” Discuss the practical importance of the result obtained;

A: When choosing the gain, the maximum value is determined by the circuit and the supply voltage. The gain value is set based on the original circuit. It should be noted that this value can be changed at any time by feedback if necessary.

> Results and discussion. Authors should provide a better basis for the discussion, detailing the meaning of the parameters analyzed, especially whether the results are comparable to commercial results, if possible, or whether they can be compared with other results in the literature;

A:

 Thank you for your suggestion, we have  improved the results and discussion section, you can find our changes on page 14, they are indicated by blue color.

Reviewer 4 Report

Comments and Suggestions for Authors

This paper presents the development of a cost-effective, open measurement system designed to record the hysteresis properties of 3D-printed iron cores. The work addresses the limitations of existing commercial systems, which are often expensive and lack transparency, hindering research and development. The authors provide a comprehensive overview of the design process, circuitry, and simulations, and validate the prototype's performance through measurements.  The topic is highly relevant to the field of electrical machines and additive manufacturing. The ability to accurately characterize the magnetic properties of 3D-printed cores is crucial for optimizing machine design and performance. The paper is well-structured and clearly written. The block diagrams and circuit schematics are easy to follow. The design and implementation of the measurement system appear to be technically sound. The authors have considered important factors such as power supply design, amplifier circuitry, and current sensing.   Finally, the inclusion of simulation results and experimental validation strengthens the credibility of the work.   Therefore, I recommend accepting the manuscript after the authors fixing these issues:

1- Literature Review: While the authors provide a good overview of existing measurement techniques, the literature review could be expanded to include more recent work on magnetic material characterization and modeling, particularly in the context of additive manufacturing.  

2- Detailed Design Choices: The authors explain their design choices well, but could provide more detail on component selection (e.g., why specific op-amps or transistors were chosen) and the reasoning behind certain circuit parameter values.  

3- Measurement Uncertainty: The paper would benefit from a discussion of the measurement uncertainty of the proposed system. This could include an analysis of potential error sources and how they were minimized.

4- Comparison with Commercial Systems: A more detailed comparison of the proposed system's performance with that of commercial systems would be valuable. This could include a comparison of accuracy, frequency range, and other relevant parameters.  

5- 3D Printing Details: Additional information about the 3D printing process used to create the iron cores would be helpful. This could include the specific printing technology, materials used, and printing parameters.  

6- Figure prsentations: I recommend the authors chang the color of Figure 2, is hardly seen. Also, it will be great if the authors used suitable fond size and colors for Figures 8 and 9. For Figure 11, I recommend to add description of the realized hysteresis measurement circuit in Altium Designer.

Author Response

Dear Reviewer,

 Thank you for your work and your suggestions; they helped us improve the quality of the paper.  

Our changes indicated by blue color in the paper, while you can find our point-by-point answers below:

This paper presents the development of a cost-effective, open measurement system designed to record the hysteresis properties of 3D-printed iron cores. The work addresses the limitations of existing commercial systems, which are often expensive and lack transparency, hindering research and development. The authors provide a comprehensive overview of the design process, circuitry, and simulations, and validate the prototype's performance through measurements.  The topic is highly relevant to the field of electrical machines and additive manufacturing. The ability to accurately characterize the magnetic properties of 3D-printed cores is crucial for optimizing machine design and performance. The paper is well-structured and clearly written. The block diagrams and circuit schematics are easy to follow. The design and implementation of the measurement system appear to be technically sound. The authors have considered important factors such as power supply design, amplifier circuitry, and current sensing.   Finally, the inclusion of simulation results and experimental validation strengthens the credibility of the work.   Therefore, I recommend accepting the manuscript after the authors fixing these issues:

Q: 1- Literature Review: While the authors provide a good overview of existing measurement techniques, the literature review could be expanded to include more recent work on magnetic material characterization and modeling, particularly in the context of additive manufacturing.

A: Our 3D printed iron cores and their magnetic properties have been discussed in a previous article. We feel that the focus of this article is not on this area of science, but on the cheapness and technical solution of measurement with low cost implementation.

Q: 2- Detailed Design Choices: The authors explain their design choices well, but could provide more detail on component selection (e.g., why specific op-amps or transistors were chosen) and the reasoning behind certain circuit parameter values.

A: Thank you for your comment! The choice of components (semiconductor, current meter, encapsulation, etc.) is described in detail, highlighted in blue in the article.  

Q: 3- Measurement Uncertainty: The paper would benefit from a discussion of the measurement uncertainty of the proposed system. This could include an analysis of potential error sources and how they were minimized.

A: We appreciate the reviewer’s suggestion regarding measurement uncertainty. In the revised manuscript, we have clarified that the main sources of error—such as phase shift, sensor sensitivity, and component tolerances—were identified and minimized through compensation techniques and circuit improvements. Based on comparisons with a reference system, the relative uncertainty of the loss measurements is estimated to be within ±3\%, which is acceptable for the intended research and prototyping applications.

Q4 – Comparison with Commercial Systems:
A more detailed comparison of the proposed system's performance with that of commercial systems would be valuable. This could include a comparison of accuracy, frequency range, and other relevant parameters.

A: This need was also recognized during the project. Accordingly, we carried out preliminary investigations into key performance parameters such as gain, distortion, and phase delay. The system is currently in the testing phase, during which we are gathering practical experience to support future refinements. These efforts will form the basis for a more comprehensive comparison with commercial systems in terms of accuracy, operating frequency range, and overall performance.

Q5 – 3D Printing Details:
Additional information about the 3D printing process used to create the iron cores would be helpful. This could include the specific printing technology, materials used, and printing parameters.

A: The details of the 3D printing process and the magnetic properties of the fabricated iron cores have been presented in a previous publication. As the primary focus of the current work is on the development of a cost-effective and technically sound measurement system, we have chosen to limit the discussion of material fabrication in this article. We believe this allows for a more targeted presentation of the measurement methodology.

Q6 – Figure Presentation:
I recommend the authors change the color of Figure 2, as it is hardly visible. Also, it would be helpful to use suitable font sizes and colors for Figures 8 and 9. For Figure 11, I recommend adding a description of the realized hysteresis measurement circuit in Altium Designer.

A: The figures have been revised as requested. In Figure 2, the yellow background has been removed, and the color scheme (e.g., Graetz Bridge) has been adjusted for improved visibility. In Figures 4, 5, and 6, the yellow background has also been removed, image quality has been enhanced, and caption font sizes have been increased for better readability. Additionally, the quality of LTspice-based simulation schematics and result plots (Figures 7–10) has been improved. A detailed description of the realized hysteresis measurement circuit has now been added to Figure 11 to provide better clarity.

Reviewer 5 Report

Comments and Suggestions for Authors

1. The paper effectively addresses the need for a low-cost, open-source hysteresis measurement system for 3D-printed magnetic cores. However, the innovation compared to prior work could be better emphasized. While improvements such as emitter resistors for current balancing and active short-circuit protection are mentioned, a quantitative comparison with existing systems would strengthen the novelty claim.

2. Additionally, the 36.2% loss increase due to phase shift is significant; a deeper discussion on mitigating this error would enhance the practical value of the findings.

3.The manuscript contains minor grammatical errors.

4.The reference formatting is inconsistent.

Author Response

Dear Reviewer,

 Thank you for your work and your suggestions; they helped us improve the quality of the paper.  

Our changes indicated by blue color in the paper, while you can find our point-by-point answers below:

Q1: The paper effectively addresses the need for a low-cost, open-source hysteresis measurement system for 3D-printed magnetic cores. However, the innovation compared to prior work could be better emphasized. While improvements such as emitter resistors for current balancing and active short-circuit protection are mentioned, a quantitative comparison with existing systems would strengthen the novelty claim.

A: Thank you for this valuable suggestion. In the revised manuscript, we have clarified the specific innovations over prior designs, particularly highlighting the practical impact of implementing emitter resistors for current balancing, active short-circuit protection, and phase compensation. While direct quantitative benchmarking with commercial systems is beyond the current scope, we have emphasized that the proposed system achieves loss measurement accuracy within 1\% of a trusted reference setup. This performance, achieved with a significantly simplified and low-cost architecture, reinforces the novelty and applicability of our approach.

Q2: Additionally, the 36.2\% loss increase due to phase shift is significant; a deeper discussion on mitigating this error would enhance the practical value of the findings.

A: We agree that phase shift is a critical factor affecting measurement accuracy. The revised manuscript now includes an expanded discussion on this point, including how phase compensation was implemented and how it effectively reduced the error from 36.2\% to under 1\%. We also elaborate on possible future improvements, such as integrating a voltage-controlled current source to further stabilize the phase relationship between current and voltage.

Q3: The manuscript contains minor grammatical errors.

A: Thank you for pointing this out. The manuscript has been thoroughly revised to correct grammatical issues and improve overall clarity and readability.

Q4: The reference formatting is inconsistent.

A: We appreciate the comment. The reference list has been reviewed and corrected to ensure consistent formatting throughout the manuscript, in line with the journal’s style requirements.