Dynamic Sliding Mode Control of DC-DC Converter to Extract the Maximum Power of Photovoltaic System Using Dual Sliding Observer

Round 1

Reviewer 1 Report

The authors of the paper present a dynamic sliding mode controller (SMC) to regulate the DC-DC converter (buck) for a photovoltaic generator system. The main purpose of the SMC is maximum power point tracking (MPPT) and eliminating the chattering of the duty cycle, which plagues the classic SMC. The authors propose a dual sliding observer to estimate the values of the uncertainties in the photovoltaic generator system. The stability of the Dynamic SMC was tested using the theory of Lyapunov stability. The paper includes the results of the simulation of the system using Dynamic SMC and the system using classic SMC. The results clearly present that the chattering, present in the system using classic SMC is not present in the system using the proposed Dynamic SMC.

The paper presents only simulation results. The reviewer would like from authors to include experimental results, which would verify the theory behind the proposed system control scheme, if possible. Tests in order to confirm the proposed control system could be implemented on the system on a smaller scale. The simulation results could also be improved with tables, describing the rise and fall times, static error, chattering, etc.

Comments for author File: Comments.pdf

Author Response

Response to Reviewers

Manuscript ID: electronics-1843391

Dynamic Sliding Mode Control of DC-DC Converter to Extract the Maximum Power of Photovoltaic System Using Dual Sliding Observer

Authors: Ali Karami-Mollaee and Oscar Barambones

 

First of all, the authors would like to thank the associate editor and the respected reviewers, who gave us many constructive comments and valuable suggestions in order to improve this paper. The authors have revised the paper according to the reviewers’ comments. The responses to the reviewer comments can be found below their respective comments and the changes made in the paper are marked in red color.

Moreover, based on the editor’ comment, references 8, 9 and 11 are removed.

Sincerely Yours,

The corresponding author,

Reviewers' comments and our responses:

Reviewer #1:

The authors of the paper present a dynamic sliding mode controller (SMC) to regulate the DC-DC converter (buck) for a photovoltaic generator system. The main purpose of the SMC is maximum power point tracking (MPPT) and eliminating the chattering of the duty cycle, which plagues the classic SMC. The authors propose a dual sliding observer to estimate the values of the uncertainties in the photovoltaic generator system. The stability of the Dynamic SMC was tested using the theory of Lyapunov stability. The paper includes the results of the simulation of the system using Dynamic SMC and the system using classic SMC. The results clearly present that the chattering, present in the system using classic SMC is not present in the system using the proposed Dynamic SMC.

 

COMMENTS FOR THE AUTHOR:

1. The paper presents only simulation results. The reviewer would like from authors to include experimental results, which would verify the theory behind the proposed system control scheme, if possible. Tests in order to confirm the proposed control system could be implemented on the system on a smaller scale. The simulation results could also be improved with tables, describing the rise and fall times, static error, chattering, etc

Response to the reviewer:

• We agree with the reviewer that the inclusion of a real application of the proposed method could be very interesting, however unfortunately at this moment I do not have the infrastructure necessary to develop real experiments. However, we think that the advantages of this approach (like the chattering elimination and observer performance) is promising for practical applications. Moreover, it is not possible for us to develop an experimental setup within 7 days, that is the deadline to submit the revision. Moreover, it should be noted that there are many papers that only presents simulation results [6, 15, 17, 21].
• The purpose of the proposed approach is chattering elimination. We show that dynamic SMC can remove the chattering, but in conventional SMC chattering occurs. As the simulation results show, the steady state of two approaches are zero. This is added to the paper in simulation section.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper examines photovoltaic energy harvesting (PGS) using maximum power point tracking MPPT.  A converter is inserted after the PGS and its duty cycle is adjusted using a smooth control signal. PGS/converter issues include uncertainty. Dynamic sliding mode control SMC controls duty cycle and eliminates unpredictability. Low-pass integrator reduces SMC chatter. Integrator increases system states, hence DSO is recommended to estimate them. Dynamic and classic SMC were compared using the same DSO. Proposed dynamic SMC outperforms classic SMC in chattering reduction and practical implementation. The paper is quite good but here are my comments:

1. Since the results are purely simulations, please describe what platform do the authors simulate their work, e.g. MATLAB, Simulink, Simplis, etc. ? Explain in detail how the authors input the characteristics of the PV/solar panel model used. Did they used SPICE or Simulink model for the PV?

2. Since we are talking of MPPTs here, could you describe the tracking efficiencies for both the proposed and conventional SMCs? Did the performance exhibited by the proposed technique affects the performance metrics of the the MPPT as a whole?

3. Could the authors explain in detail the SMC principle whose purpose is to regulate the duty cycle? Please compare it with other algorithms such as P&O, ripple correlation control, incremental conductance, etc. Apparently, some new reference such as the following below describe in detail their proposed MPPT techniques (P&O, RCC, IC, etc.) highlighting the advantages/strengths and disadvantages/weaknesses. The authors should highlight SMC over the said techniques comparing the prior works below and other latest references not mentioned by the authors.

a. C.-C. Wang, et al. "An adaptive constant current and voltage mode P&O-based Maximum Power Point Tracking controller IC using 0.5-μm HV CMOS." Microelectronics Journal 118 (2021): 105295.

b. Batarseh, M. G., & Za'ter, M. E. (2018). Hybrid maximum power point tracking techniques: A comparative survey, suggested classification and uninvestigated combinations. Solar Energy, 169, 535-555.

c. Tolentino, L. K. S., Cruz, F. R. G., Garcia, R. G., & Chung, W. Y. (2015, December). Maximum power point tracking controller IC based on ripple correlation control algorithm. In 2015 International Conference on Humanoid, Nanotechnology, Information Technology, Communication and Control, Environment and Management (HNICEM) (pp. 1-6). IEEE.

Author Response

Response to Reviewers

Manuscript ID: electronics-1843391

Dynamic Sliding Mode Control of DC-DC Converter to Extract the Maximum Power of Photovoltaic System Using Dual Sliding Observer

Authors: Ali Karami-Mollaee and Oscar Barambones

 

First of all, the authors would like to thank the associate editor and the respected reviewers, who gave us many constructive comments and valuable suggestions in order to improve this paper. The authors have revised the paper according to the reviewers’ comments. The responses to the reviewer comments can be found below their respective comments and the changes made in the paper are marked in red color.

Moreover, based on the editor’ comment, references 8, 9 and 11 are removed.

Sincerely Yours,

The corresponding author,

Reviewers' comments and our responses:

 

Reviewer #2:

This paper examines photovoltaic energy harvesting (PGS) using maximum power point tracking MPPT.  A converter is inserted after the PGS and its duty cycle is adjusted using a smooth control signal. PGS/converter issues include uncertainty. Dynamic sliding mode control SMC controls duty cycle and eliminates unpredictability. Low-pass integrator reduces SMC chatter. Integrator increases system states, hence DSO is recommended to estimate them. Dynamic and classic SMC were compared using the same DSO. Proposed dynamic SMC outperforms classic SMC in chattering reduction and practical implementation. The paper is quite good but here are my comments:

 

COMMENTS FOR THE AUTHOR:

1. Since the results are purely simulations, please describe what platform do the authors simulate their work, e.g. MATLAB, Simulink, Simplis, etc. ? Explain in detail how the authors input the characteristics of the PV/solar panel model used. Did they used SPICE or Simulink model for the PV?

Response to the reviewer:

• Both simulation results are done with Matlab using step size of 0.001.
• For calculation of input control duty cycle, we first calculate variables in equations (32), (33) and (34) using the observer (21). Then input can be obtained from equation (35) for dynamic SMC and equation (40) for conventional SMC. This is added to the paper as the remark 2.

2. Since we are talking of MPPTs here, could you describe the tracking efficiencies for both the proposed and conventional SMCs? Did the performance exhibit by the proposed technique affects the performance metrics of the MPPT as a whole?

Response to the reviewer:

• Thanks to this reviewer’s comment, as the simulation results show, the steady state error of the both approaches are zero. Please see figures (9) and (13), which are depicted sliding surfaces. The chattering can be observed from figure (13).This is added to the paper in simulation section.

3. Could the authors explain in detail the SMC principle whose purpose is to regulate the duty cycle? Please compare it with other algorithms such as P&O, ripple correlation control, incremental conductance, etc. Apparently, some new reference such as the following below describe in detail their proposed MPPT techniques (P&O, RCC, IC, etc.) highlighting the advantages/strengths and disadvantages/weaknesses. The authors should highlight SMC over the said techniques comparing the prior works below and other latest references not mentioned by the authors.
4. C.-C. Wang, et al. "An adaptive constant current and voltage mode P&O-based Maximum Power Point Tracking controller IC using 0.5-μm HV CMOS." Microelectronics Journal, 118 (2021): 105295.
5. Batarseh, M. G., & Za'ter, M. E. (2018). Hybrid maximum power point tracking techniques: A comparative survey, suggested classification and uninvestigated combinations, Solar Energy, 169, 535-555.
6. Tolentino, L. K. S., Cruz, F. R. G., Garcia, R. G., & Chung, W. Y. (2015, December). Maximum power point tracking controller IC based on ripple correlation control algorithm. In 2015 International Conference on Humanoid, Nanotechnology, Information Technology, Communication and Control, Environment and Management (HNICEM) (pp. 1-6). IEEE.

Response to the reviewer:

• Thanks to this reviewer’s comment, but comparison of SMS with other approach such as P&O cannot be suitable because, as it is well known, in these methods the system is oscillating around the MPP. We think similar methods should be compare as we do in this paper. As it is clear, our focused is on chattering in sliding mode control. Then, we try to proposed an approach to have a smooth and without chattering duty cycle.
• Moreover, according to the associate editor’s comment, we should not to add unnecessary references. Anyway based on this comment, reference (a) is added to the paper. Please see the reference 11.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Authors answered every question and corrected the paper accordingly.a

Reviewer 2 Report

The authors have already revised their paper based on my comments. I am satisfied with their replies to my queries.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.