Electrochemical Cell Loss Minimization in Modular Multilevel Converters Based on Half-Bridge Modules

Round 1

Reviewer 1 Report

In the manuscript titled “Electrochemical cell losses minimization in modular multilevel converters based on half bridge modules”, the authors present a novel analytical investigation of electrochemical cell power losses in MMCs and their dependence on the injected common mode voltage, which can be used to minimize the cell power losses, and validate the effectiveness of the proposed strategy experimentally. This study provides the promising perspectives to make MMCs more attractive with respect to conventional power converters. I recommend the publication of this paper to the journal of Energies after some minor revision. Detailed comments and questions are as following,

 

1. The abbreviation of PWM is first given in Line 64 on Page 2, what does it stand for? The same question for the abbreviation of MOSFETs in Line 70 on Page 2.
2. Give the physical meaning of x and y axis in each graph of Figure 2 and 4.
3. Does the number of modules (N) connected in series play the key role in the effectiveness of optimization strategy? How about the number of arms? Considering that experimental validation just discussed two-arm case.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript describes an optimal common mode voltage injection wareform for Modular Multilevel Converters to have reduction in cell losses. The authors paid their attention to the statement of problem and noted that there are still some fundamental concerns. The work also shows detailed analysis of the problem and justified approaches and methods with description of the Modular Multilevel Converter features, providing of minimum switching losses, conduction losses. Obviously, the problem is considered comprehensively.

The main strengths of this paper are that it addresses an interesting and actual question, finds an innovation based on a carefully selected approaches and methods, suggests the collaboration of industry and science (page 9). The manuscript is well-written and nicely presented, with a good balance of descriptive text and discourse and practical illustration of package usage.

There were the following minor questions:

1. Why did you use only RL-load? If we consider RLE-load, can we also see about 17.5% reduction in cell losses?
2. What do you think about voltage DC cell balancing based on your optimal common mode voltage injection wareform?
3. Industrial problem of MMC links with non-sinusoidal load currents - how your method will work on such conditions?
4. Is there limitation for low swathing switching frequency for this modulation method?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf