Control and Implementation of the Parallel Enhanced Commutation Integrated Nested Multilevel Inverter Topology
Round 1
Reviewer 1 Report
In the article under review, the authors present a description of a new topology of a cascaded multilevel inverter applied to battery electric vehicles. In order to reduce switching losses, reduce harmonics and increase efficiency, the authors proposed the parallel enhanced commutation integrated nested (PECIN) multilevel inverter.
In the Introduction and literature review, the prerequisites for conducting research are considered, and the purpose of the paper is formulated. In the main parts of the paper, a description of the authors' idea is presented, a complete description of the PECIN switching function is given, and the optimization of the switching function is considered. The proposed algorithms were verified on a specially designed test stand.
The paper can be interesting and useful to scientists and researchers, specialists in the field of power electronics.
However, during the review, I drew attention to the following minor shortcomings, the correction of which would improve the quality of the paper:
- The paper presents a description of the idea and its implementation. However, there are no studies of specific advantages and disadvantages in comparison with other multilevel inverter topologies.
- The authors claim but do not present, the results of studies of high energy efficiency of their proposed multilevel inverter topology.
- The authors also keep silent and do not consider the problem of uneven discharge of batteries. I ask the authors to clarify this.
In general, the authors presented their idea in an accessible way and provided experimental confirmation of its implementation. However, the paper is essentially descriptive and has a weak research part. Nevertheless, I could recommend it for publication after making the above additions.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The article called "Control and Implementation of the Parallel Enhanced Com mutation Integrated Nested Multilevel Inverter Topology" is interesting, well written and deserves publication as a science publication.
Its practical application seems distant to me, and it will take a lot of time to use it. I separate my impressions based on formal aspects of what is written in the paper, and then request what has not been defined.
Formal aspects related to what is written:
An MLI is used, with levels equal to 2N+1, on page 3 I would specify in line 123 that N is equal to 4, which implies the presence of 12 battery packs or single cells, for use in traction (recharge).
Figure 1 clarifies the intentions, but case c is not discussed as for a and b, it is understood that it relates to recharging.
Figure 2 has parameters such as n (speed) undefined (whereas M is with B).
The indexes of paragraphs 3.3 and 3.4 and 3.4.1 are confusing, shouldn't they be 3.3.1 3.3.2 3.3.3 (and others...)?
In Figure 4, the SP6 state should be marked as a non-operating state, as the caption reads valid switching patterns.
The demonstrator works at 17 levels (N=8), I wonder if the system is a three-phase one, as present in the article or is it a single-phase application?
The abstract promised a 31-level system (N=15) but there is no reference to this in the paper.
Research questions.
1) Has the reduction of the harmonic content been evaluated on the basis of the implemented logic?
2) The use of multilevel sees the use of Deadtimes that condition the growth of levels as a hidden difficulty, for 17 levels or 31 levels have these deadtimes been taken into account when commanding the change of SP? Since the dynamic change could be dangerous and perhaps better to do it with the inverter not connected.
3) The applicability is difficult, modern cars have contactors to keep the high voltage line off, while with this architecture it would seem that the battery and the inverter are closely connected to each other. The SP6 state could be used to keep the battery disconnected.
4) The BMS should make sure that all the cells are used for the power they can yield, but in the most apical points (highest levels) the cells could be used less, the system can provide for a rotation of the SPs to uniformly discharge the cells with a slight addition of new lookuptables?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
1. The Authors' article is of great importance related to the development of electric vehicles with the controlled battery supply. The article presents an interesting idea of the battery cascaded Multi Level Inverter (MLI). The focus is directed to the special design of MLI, called as Parallel Enhanced Commutation Integrated Nested Multilevel Inverter (PECIN MLI).
2. The article can be considered as clearly written and well organized. The presented descriptions of the issues are very detailed and precise.
3. But the article contains a small number of editorial errors, that should be corrected for educational reasons.
4. In the list of Keywords, the terms: “MLI” and “ PECIN” should be removed, because they are presented in short way. For MLI the full name is given and the shortage MLI is not necessary. The term PECIN should be presented as the full name. In the list of Keywords the term: “Switching Function” should be added.
5. The list of References includes 31 position. Most of the References are cited only one, sometimes 2-4 times. But the Reference 3 is cited 17 times, and Reference 2, 9 times. These two References are written by the Authors of the manuscript.
6. It seems purposeful to present a mathematical description of PECIN MLI with the simplifying assumptions taken in theoretical and simulation considerations.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors provided responses to my comments. Despite this, I still cannot give a high assessment of the research part of the manuscript, but nevertheless I can recommend this article for publication.
Reviewer 2 Report
the authors responded very well to my comments, the article can be published
