An Optimized H5 Hysteresis Current Control with Clamped Diodes in Transformer-Less Grid-PV Inverter

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper presents optimized H5 hysteresis current control with two clamping diodes to reduce the leakage current in grid-tied solar inverters. I have the following questions about the manuscript:

1. Regarding the leakage current or circulating current, it is suggested to read observer-based control like Active Disturbance Rejection Control.

[Ref] Active Disturbance Rejection Control Scheme for Reducing Mutual Current and Harmonics in Multi-Parallel Grid-Connected Inverters. https://doi.org/10.3390/en12224363

2. The proposed hardware-based leakage current reduction can reduce the reliability and may increase cost. Can you please comment on this?

3. Can you please do FFT analysis to see the harmonic contents in the current with conventional and proposed method? 

4. How the proposed method will behave when there is grid impedance?

5. Furthermore, the reference section can be updated to recent paper to support the novelity of the idea.  

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1.Is the V_AN mentioned by the author referring to the voltage between point A and point N? Based on equations (1) and (2), V_AN seems more like the voltage difference between point A and the ground.

2.The author states that in Mode 2, "all the switches, except Q₁, are turned on." However, Figure 6 shows that at this time, all switches except Q₁ are turned off.

3.If the author could mark the parasitic capacitances in the circuit during the modal analysis, it would make it easier for readers to understand the voltage variations of the parasitic capacitances.

4.It is recommended that the author indicate the flow directions of both differential-mode current and common-mode current in the diagrams during modal analysis to help readers better understand the variations in common-mode current.

5.According to the author, when the proposed system is connected to the grid, only the d-axis current is controlled, while the q-axis current is not. Could the author explain the rationale behind this control strategy?

6.Compared to the existing H5 topology, what are the advantages of the topology proposed by the author?

7.It is recommended to add the following references, such as:

[1]. Xiaoqiang Guo, Ran He, Xiaoyu Jia and C. A. Rojas, "Leakage current reduction of transformerless three-phase cascaded multilevel PV inverter," 2015 IEEE 24th International Symposium on Industrial Electronics (ISIE), Buzios, 2015, pp. 1110-1114, doi: 10.1109/ISIE.2015.7281627

[2]. Sun, Jiaqi.; Sun, Haoran.; Jiang, Jiahui. An improved modulation method for low common-mode current non-isolated series simultaneous power supply dual-input inverters for new energy generation applications. Electrical Engineering 2024. https://doi.org/10.1007/s00202-024-02285-z

[3]. B. Wei, X. Guo, J. M. Guerrero and M. Savaghebi, "Leakage current suppression with a novel six-switch photovoltaic grid-connected inverter," 2015 IEEE 10th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED), Guarda, Portugal, 2015, pp. 22-26, doi: 10.1109/DEMPED.2015.7303664

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

This paper has been improved considerably by addressing the comments of reviewers. I have no further comments. 

 

I wish good luck to authors. 

Reviewer 2 Report

Comments and Suggestions for Authors   I have no further comments.