Nonlinear Effects of Three-Level Neutral-Point Clamped Inverter on Speed Sensorless Control of Induction Motor

Round 1

Reviewer 1 Report

This paper presents Nonlinear Effects of Three-level Neutral-point Clamped Inverter on Speed Sensorless Control of Induction Motor. The quality of the paper is good. However, there are some important issues which need to be considered.

1. The structure of the introduction needs to be modified. Please add the structure of the paper in the introduction and extend the literature review according to the last published paper in terms of nonlinear effects of Three-level Neutral-point of control of Induction motor.

2. Please add more information regarding the experimental result (the test case, such as figure) in section 5.

3. Please add the rate of the error (nRMSE result) between the actual speed and observed speed in a table and explain the advantage of the proposed method.

4. Please extend the conclusion to be clear for the reader of the journal which shows the exact novelty of the proposed method.

5. Please add a flowchart to show the whole procedure of the proposed method in section 4.

Author Response

Dear reviewer,

I have reply the review report as in the Word file.

Author Response File: Author Response.pdf

Reviewer 2 Report

The reviewed paper deals with the topic which isn’t new but fairly interesting. The authors don’t present any “super new” method which leads to revolutionary results or anything new at all. That’s good. They present the method how to compensate the some of the nonlinearities that are evinced by a multilevel converter when it supplies an induction machine. The goal is to get the proper actual data of mechanical rotational speed without speed measurement. Their method is described and then implemented. In the end, the measured date and the comparison between two situations (with compensation and without it) are shown. Their measured results are consistent with their theoretical analysis. So, the point isn’t that their method of compensation is suitable for a control algorithm. I think it is very useful to publish such interesting and “normal” papers.

I have several different remarks to the paper:

Line 10 (abstract)

What is the “actual system”? Explain it clearly, please!

Line 26 (chapter I)

It is written “in recent years”, but the references are form 2017 and 1981. Year 1981 isn’t  “recent year”! It is the origin paper about NPC.

Introduction (chapter I)

It is written “hot research question” with the reference to the year 1998. I don’t agree…

References

The unified cited style has to be kept!

Line 65

The phases of NPC cannot be considered the same because they have the common neutral point!!!! All three phases are connected together and an action in one phase influences the other phases! It is the wrong precondition.

Chapter 2.2

It is written that the voltage uf cannot be ignored. Then that the voltage drop across all semiconductor devices is the same. However, it isn’t true! The IGBTs have maybe three-times higher voltage drop that the diodes!!

Chapter 2

There are mentioned only two nonlinearities. However, there are more nonlinearities in an inverter.

The equations – all equations should have their number in the middle of the vertical direction.

Fig. 7

The description isn’t consistent with the text and equation. The transfer functions GΔud and GΔuq aren’t defined anywhere.

Fig. 10  

It refers to equations 2 and 3, however, it isn’t explicitly stressed that the dependence is expressed with help of characteristic from the datasheet.

Line 181

Explain how the torque of the motor can be 0 Nm during the motor operation state!

Line 182

It isn’t table of motor parameters, but the table of nonlinear effects.

Author Response

Dear reviewer,

Thank you for your careful review, we have reply the reviewer report as a Word file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Please, update references.

It needs proofread. there is some problem in English writing of the paper, please, correct them.

Author Response

Dear reviewer,

Thank you for your careful review, we have reply the review report as a Word file.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank you for answering all comments. The reviewer believes the quality of paper after revision is good and it should be accepted in present form for publishing in Electronics Journal.