Digital Implementation Method for Synchronous PWM Control of GaN Transistor at Zero-Crossing of Totem-Pole PFC in Energy Storage Applications
Round 1
Reviewer 1 Report
I propose to modify the introduction and results.
The goal is specifically described in the introduction, but I do not understand why this goal.
What a later or bigger idea, part of a concept.
Perhaps Figure 7b. it should be indicated what OVP (Over Voltage Protection( means and OVP status.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors of the paper proposed an original digital driving method for a GaN transistor-based totem-pole PFC (representing bridgeless PFC topology). The method is quite clearly presented and well documented. At the first stage, the basic operating characteristics of the totem-pole PFC are analyzed, which is followed by a formulation of a digital control technique using a digital signal processor (DSP). The purpose of the authors is to provide an optimal PWM control solution to prevent the reverse operation due to the DCM current at the zero crossing. It is an important step towards increased efficiency and reliability. The proposed digital control technique was verified with a digital controller application to a 1 kW totem-pole PFC. My only suggestion would be to develop and improve the Introduction, as the transition from general introduction issues to a very specific totem pole PFC circuit description comes quite suddenly. Moreover, I would recommend adding some adequate references to present state of knowledge in a more systematic way. For example, the authors mentioned that "The solution to the current spike problem has been reported in many previous papers [17,18]" (line 55) but give only 2 references. Similarly, the authors claim that 'Based on these advantages, various studies using digital controllers for GaN-based totem-pole PFC control are conducted' (line 47-48) but no references are provided. In general, I have read an interesting article, which just needs some final touch.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The proposal presented by the authors, although well written, does not seem novel to me.
The Totem Pole topology is quite well known and there are many published works on it. Some are cited by the author and some are not. In fact, some of the company technical documents that the document cites are from companies that directly sell this topology with a preconfigured control that is easily corrected or modified. In these same journals data are provided to tune / design the control in a simple way.
On the other hand, in recent years improvements to this converter have been published to eliminate the effects of parasites and improve its performance, including two additional diodes that are not mentioned or compared by the authors.
Furthermore, the proposed linear control with double ramp PWM is not new. Other publications, such as https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8249782, include it adding even more functionality to the system than the authors' proposal.
Lastly, GaN is an interesting new technology compared to Mosfet. But this is not the first time that performance data comparing both technologies has been presented.
What is the actual contribution of the authors compared to other articles?
Regarding formal aspects, some terms are not well written. For example, acronyms do not need to include periods between letters.
In the last figure (Fig. 11) it is not compared with the conventional structure. In this figure, in view of the current waveform, what THD does it have? It seems well above 4.7%.
Another interesting aspect that does not appear in the document is the frequency of switching of the converter. The switching frequency is not the same to work with Mosfect than to work with GaN. However, this is not referenced. Typically with GaN, FPGAs are used. Why have you chosen that sample rate and work with DSP?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The authors have answered my questions and the document is correct.
