Design of an Highly Efficient AC-DC-AC Three-Phase Converter Using SiC for UPS Applications

Round 1

Reviewer 1 Report

Well organized and nicely written paper.

No comments.

Author Response

Dear Reviewer,

We would like to thank you for reviewing our paper.

Reviewer 2 Report

The paper developed a UPS system using SiC switches. 

The paper demonstrated a significant reduction of the volume and mass of the UPS compared to a conventional system. 

However, the reviewer think that the comparison was not fair and the comparison does not support the focus of the paper.

The proposed system was designed for 100 kHz operation while the conventional UPS system that was compared with the proposed system was operated at 15 kHz. The reduction of the size and volume of the inductors and capacitors were not coming from the SiCs but from the high switching frequency. For a fair comparison, the proposed system must be designed for 15 kHz operation or the authors need to find a conventional system that operates at 100 kHz. 

Furthermore, the comparison in Table 7 is not appropriate. As shown in Figure 8, IGBT-based UPS is in a steel case and it looks like having relays, and other auxiliary control devices. The proposed system does not have any of these. It is not a fair result that the proposed system has a -94 % reduced total mass and volume compared to the IGBT-system.

In order to support the main focus of the paper, the reviewer recommend to compare the proposed system with a 100 kHz UPS system, without the case and other aux. devices. 

Also, the reviewer think that a reader can understand the graph in Fig. 6 if the properties of XFlux, High Flux, Mu and other magnetic materials are explained or tabularized in the paper.

Also, there were some typos that need to be corrected.

ex. p.7, line 145: flow -> flux

Author Response

Dear Reviewer,

We would like to thank you for reviewing our paper. You`ve made very pertinent comments, our replies are in the file attached.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper presents the Design of an AC-DC-AC
three pahse converter for an UPS, made with SiC.
The topic is interesting and fall within the scope of the Journal.
The quality of the paper is high and the structure of the paper is good.

A criticism is presented in the experimental results, because more informations
must be introduced for the control adopted:
Which is the goal of the control? Is it adopted a Power Factor Control Strategy?

Author Response

Dear Reviewer,

We would like to thank you for reviewing our paper. You`ve made very pertinent comments.

We agree that the reader can better understand our work if more informations about the control are given, so we've added a small section about the control strategy applied to the converter. Yes, a power factor correction strategy is used. The goals of the control are:

- Power factor correction;

- Keep the input current and output voltage at low THD (< 15%);

- Regulate output voltage;

- Rejection of load disturbances;

- Synchronize input and output voltages;

- Regulate DC link voltage at 400 V.

Round 2

Reviewer 2 Report

The revised paper has reflected all the reviewer's comments.