Parallel Power Sharing Control of Multi-Controllable Rectifiers in a High-Power DC Fast Charging Station

Round 1

Reviewer 1 Report

The literature review covers the power electronics background well, but the authors could improve it by including some papers on power sharing controls for charging stations. Many of these papers will not cover the dynamics impacts, but they are still related to the authors' work.

The method/analysis sections should be modified to acknowledge that DC fast charging is not a constant current load. When fast charging, EV batteries experience thermal limits and fluctuations, causing fluctuations in current. The batteries may be considered constant current if undergoing level 2 charging between about 15-80% State of Charge, but when DC fast charging, the current will fluctuate. At 180kW this is DC fast charging and cannot assume a constant current. If the authors wish to maintain their work and analysis, they could modify the setup such that a DC bus supplies multiple level 2 chargers at once, and specify that they are only charging the vehicles to 80% SOC at level 2. Otherwise, they should modify the methods and analysis to account for fluctuations in current when DC fast charging.

The authors state: "EV generally uses the method of "constant current first, then constant voltage" for charging." This is true for level1 and level2 charging but the while, the EV attempts to get a constant current for DCFC, thermal limits in the battery cause large fluctuations. The dynamic analysis in this paper may still be valid, but the authors should specify that the dynamic responses will occur before the battery experiences thermal limitations and current fluctuations.

The English in this paper is very good, but there are just a couple spots where a noun is singular and should be plural or where a noun is plural and should be singular. For example, the authors write: ". . . there are few researches . . ." when it should be: " . . . there is little research . . . "

Also, the authors should be sure to spell out acronyms the first time they are used.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Electromobility is a global trend. An increasing number of electric vehicles need fast charging stations for their batteries. Scientists are developing and implementing various techniques to control the battery charging current in order to ensure the highest charging power but also its stability. This paper studies the power sharing control method of high-power DC fast charging station with three controllable rectifier modules connected in parallel. By designing the current loop and voltage loop PI controller parameters and virtual impedance, the dynamic and steady-state power sharing of different modules is realized.

Modeling of the energy system components was done correctly and with the use of appropriate software. The research objects have been accurately and correctly described. The experiment was planned and performed correctly. The research results were presented in an interesting way. The diagrams and drawings were made in sufficiently good resolution. The most important part of the article is chapter 5 . The method of battery charging were described and presented in the correct way. All conclusions are based on the research made. The discussion of the obtained test results was carried out correctly. The article is very interesting and can be of great practical use.

The following corrections should be considered:

11)      The bibliography includes only 18 literature items and has been carefully prepared. The number of cited literature should be increased to 50 items. The latest publications of European scientists are missing.

22)      At the end of the article there should be an explanation of all abbreviations in the content.

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Author Response

Please see the attachment.

Author Response File: Author Response.docx