A Reduced-Order Small-Signal Model for Four-Switch Buck–Boost Under Soft-Switching Current Shaping Control Strategy
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsA reduced-order small-signal model based on the digital high frequency soft-switching current shaping control algorithm of four switch Buck-Boost topology is proposed in this manuscript. The precision and dynamic performance of this model is validated by analysis and experiment. I have some questions and suggestions as below:
[1] In Section III experiment verifications, the detail parameter and power circuit and controller should be given.
[2] The detail input condition should be give in Figure 19 and Figure 20. Is the dynamic response same during Buck, Boost, and Buck-Boost mode?
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Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper proposes an average-switching model and a first-order small-signal model for a four-switch buck-boost (FSBB) converter with step-up and step-down capabilities. This model is used for the design of a PI controller, simplifying the system design. The FSBB converter has two duty cycles controlling two modulations and a phase-shift between these modulations. A high-frequency soft switching strategy is performed that reduces the inductor RMS current and the switching loss.
On line 77, you said “for the IBA converter” … the acronym IBA is not defined.
Lines 105 -106 talk about mode (a), mode (b), mode (c) and mode (g). But there is no further information and it could not be followed. Looking to Fig. 4 it could be understood. However, this text is far away from the figure. Could you make this explanation closer to the figure?
After you introduce eq. (1)-(4). Could you try to explain better all this part?
Line 132, you said “the digital controller sample”….it should be “The digital…”
In Fig. 7 you show the current detection scheme and waveforms. However, usually, in the switching transitions are induced oscillations and overshoots that could affect the detection. Please comment how you handle this situation and the possible impact in the operation of the converter.
Line 169 … you said “shadow aera” …. “area”
Line 172 … “switch1” … do you mean “switching” ???
Foot of Fig. 9, the text should start by capita letter … “The inductor …”
The same happens for Fig. 11. And for a lot of figures, please check them all.
Foot of fig. 10 it lack of a description in the foot?
Head text of section 2.3 “small signal” should be “small-signal”
Line 213 appears “ Figure 10(b). in order“ You miss to put “In” in capital letter.
Line 244 “zero. so does the” ..please, fix.
Comments on the Quality of English LanguageThe English should be improved.
Author Response
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Reviewer 3 Report
Comments and Suggestions for AuthorsIn this paper, ta investigation related to modelling a four-switch Buck-Boost under soft-switching current shaping control methodology is presented. In my opinion, the paper is well organized. However, there are some comments to improve the quality of the paper which are given as follows:
1. The abstract does not sound well. The objectives of the paper are not correctly stated and there is a confusion to understand what is really new in this contribution.
2. The introduction has to be improved a lot since the existing recent literature on the
subject has not been well analyzed, for example like [1].
3. Also, in the introduction, I appreciate the effort of the authors to motivate the paper, but the figure 1 is unclear and not consistent with figure 4 and others. Moreover, with the established state-of-art and developed techniques for those aforementioned topics, is mot clear what are the innovations and challenges brought about by its methodology and application to control of the four-switch buck-boost converter.
4. Considering the limitations of the averaging method and discrete iterative mapping method, researchers are actively seeking new mathematical models for power converters. The theory of switched system has been incorporated into the modeling of power converters. What are the advantages of the modeling method presented in this paper compared with the model of switched systems?
5. In section 2 is related to theory, but for me is not easy to understand the rational of the authors, in particular what are the major difficulties you have met and how to overcome them?
6. The modeling hypotheses used are unclear. When do the assumptions for reducing the order of the model become invalid? This converter does not have zero dynamics? Are the zero dynamics always stable?
7. Also, some parts of mathematical derivations are not given in detail. For example, in equations 10 to 20. I suggest the authors carefully checking and give all the necessary manipulations for the derived results.
8. The experimental part is interesting, however it is important to give more details about the prototype and full list of values and parameters include the snubbers, PI parameters, etc. The quality of figure 14 and 20 should be improved.
9. The experimentation done lacks robustness verification, raising the question of how to demonstrate the efficacy of the designed robustness algorithm to Vin?
10. The instrumentation has to be better described with key data.
[1] F. Yang, W. Guo, D. Zheng, X. Ruan, K. Yao and L. Gu, "A Constant Switching Frequency Real-Time Digital Control for ZVS Four-Switch-Buck-Boost Converter," in IEEE Transactions on Power Electronics, vol. 40, no. 7, pp. 9649-9659, July 2025, doi: 10.1109/TPEL.2025.3547755.
Author Response
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Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsI appreciate the efforts done by the authors. I guess that now the manuscript is almost ready to move ahead. I would like to suggest to the authors two minor comments:
i) Fig8, the representation of power converter should be consistent in the other figures.
ii) Now, the rational for the modeling simplification is more clear, however in order to be fair with readers I would like to suggest to the authors to cite reference [1] as a example to give readers paths to other works in which there was no such simplification.
[1] - "A Nonlinear Control Allocation Strategy for Dual Half Bridge Power Converters," in IEEE Transactions on Automation Science and Engineering, vol. 22, pp. 16091-16107, 2025, doi: 10.1109/TASE.2024.3442078.
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