Study on the Mechanism and Suppression of Harmonic Vibration of AMB-Rotor System

Round 1

Reviewer 1 Report (Previous Reviewer 1)

The authors have revised their paper in line with the suggestions. This reviewer would like to recommend the publication of this paper.

English presentation seems fine.

Author Response

Please permit us to show great gratitude for your positive comments.

Reviewer 2 Report (Previous Reviewer 2)

Many thanks for working on my questions. The quality of the paper is increased significantly. However, I would still recoment to work on this question:

15) The results of Figure 6、7、8、9 are obtained by directly performing FFT transformation.

The FFT preserves the unit of the quantity. Thus, a force of 1N @ 100Hz in time domain will still be a force with magnitude 1N at the 100Hz frequency line in frequency domain.

If the magnitude is prtesented in dB, it mattres, if the RMS value has been normalized by 1e-6N or by an other reference value, such as

20*log10( (100N/sqrt(2) / 1e-6N).

For this reason I would like to ask again what is the reference by calaulating the dB plots?

Kind regards,

....

Author Response

Please permit us to show great gratitude for your positive comments.

Here we would like to explain that we have redone the simulation and experiments in the previous manuscript, and removed the original Figure 6、7、8、9. The FFT analysis of AX channel displacement signal and control current in Figure 14、15、16、17 are now directly obtained from the oscilloscope.

Once again, we acknowledge your comments and constructive suggestions sincerely, which are especially valuable in improving the quality of our manuscript.

Reviewer 3 Report (Previous Reviewer 3)

1.  The article mainly focuses on harmonic mechanisms and their suppression, yet retains the previous microvibration content in the summary without clarifying its exact significance.

2.  When SR first appears in the main text, its full name is not written.

3.  The meaning of the parameters in Equation 17 is lacking explanation, it is best to explain it when it first appears for readers to understand.

4.  The article mentions multi-source disturbances, but does not provide various forms of multi-source disturbances. Instead, it directly transitions to residual imbalances and sensor jumps. The uncertainty, time delay characteristics, noise interference, and other factors within the system are all within the scope of multi-source disturbances. It is recommended to mention them and explain the reasons for not considering these factors, making the analysis in the article more reasonable.

5.  The adaptability of the notch filter in the article requires a certain amount of time to estimate accurately. Will the speed of the acceleration process affect the control effect of this control method.

Author Response

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This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This paper studies the mathematical and physical relationship between the mechanism of disturbance generation and the inducement. The residual unbalance of rotor and sensor runout are respectively modeled to obtain the propagation path and vibration form of different micro-vibration excitation sources.  The vibration mechanisms will be used for developing micro-vibration control strategies.  While this paper presents some good results, the quality of this paper should be improved for its possible publication in this journal. Some comments and suggestions are given below:

1)     In this paper, the authors use the term “magnetically suspended rotor system”, while in early research, this was referred to as “rotor-magnetic bearing system”. The research on “active magnetic bearings or rotor-magnetic bearing systems” can be dated in the year 2000. A number of original research papers were published in 2000 to 2005 (mainly with the author JC Ji). However, the authors have overlooked these original papers, instead they cited some papers that are less relevant to “rotor-magnetic bearing systems”.

2)     Figure 1 shows four electromagnets while an original research considering two electromagnets can be found in the paper: Non-linear oscillations of a rotor in active magnetic bearings, in Journal of Sound and Vibration 240(4), 599-612.  In this paper, the nonlinear vibration of the rotor is analysed. The authors should read this paper and also cite this paper.

3)     In Figure 2, is the rotor considered as rigid?

4)     In Figure 4, the sensor runout is shown. More explanation should be provided, as it is hard to understand why there are three “circles”.

5)     How to obtain the magnetic force? Is it feedback control used?

The English Language is okay, but could be further improved.

Author Response

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Reviewer 2 Report

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Comments for author File: Comments.pdf

Author Response

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Reviewer 3 Report

1. This article adopts a four degree of freedom magnetically suspended rotor system as the object, but during the analysis, only the vibration force is considered, and the four circuits are equivalent to a consistent closed-loop system. Therefore, the setting of this object with four degrees of freedom seems unreasonable.

2. This article extensively introduces the basic principles of residual unbalance and sensor runout, while the verification process only involves simulation analysis and lacks experimental verification. And the content of synchronous current suppression algorithm, synchronous displacement suppression algorithm, and harmonic current suppression algorithm is based on the methods cited in the literature, without providing a certain explanation of their principles. Suggest reducing some basic content on residual imbalance and sensor jumping, and adding a brief explanation of these three algorithms to make the content more reasonable.

3. The object of this article is a four degree of freedom magnetically suspended rotor system, but there is no schematic diagram of the rotor structure, as well as some important content such as magnetic levitation bearing distribution, sensor distribution, critical speed, etc. in the entire article.

4. The simulation significance of sensor runout needs to be discussed. The harmonic interference added to the sensor runout is obtained through the mathematical analysis mentioned earlier, and the added position is in the external loop of the system (current loop). Therefore, adding relevant suppression algorithms to the current loop can naturally suppress the interference effect. But if we want to prove that the sensor runout is caused by odd harmonic interference, we should use experiments to prove it. Similarly, relevant algorithms should be used in experiments to prove that the source of its vibration force is only the current stiffness force.

Author Response

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Round 2

Reviewer 1 Report

The authors have addressed the issues raised in the last review and this reviewer would like to recommend the publication of this paper in this journal.

Some sentences could be improved. 

Reviewer 2 Report

Many thnanks, alls questions are answered.