Non-Inverting Quadratic Buck–Boost Converter with Common Ground Configuration for Supercapacitor Applications

Round 1

Reviewer 1 Report

The manuscript by Khan et al. presents a buck-boost converter-based topology suitable for supercapacitors and grid connected solar PV system applications. The result is interesting. However, a minor revision is needed before publishing.

1. The author is required to clear the novelty in the manuscript.

2. How about the size of the final device? Is it possible to make the device smaller and more portable?

3. Some of the figures are not clear enough. The higher resolution is required. 

4. The writing need to be improved. 

Author Response

Comment 1. The author is required to clear the novelty in the manuscript.

Response #1: The authors are thankful to the reviewer for the suggestions, the proposed converter itself is a novel converter suitable for wide input voltage range application.

Comment 2. How about the size of the final device? Is it possible to make the device smaller and more portable?

Response #2: The authors are thankful to the reviewer for the question, yes it is possible to reduce the size and weight of the system we have added a few sentences in the conclusion section of the paper as follows:

The developed prototype presented in this article looks bulky and large this is because it is developed for testing purposes only. For actual application, the weight and size of the converter can be reduced to a very small size by using high-frequency components such as SiC switches. For aerospace applications it is recommended to use high-frequency components as the weight of the converter is also added to the overall system.

Comment 3. Some of the figures are not clear enough. The higher resolution is required.

Response #3: The authors are thankful to the reviewer for the suggestion, we used high-resolution pictures however in figure 6 equivalent circuit for DCM the non-conducting elements are shown with a very light colour due to which it appears as a low-resolution figure. We have updated figures 4, 5 and 6 and added a voltage loop in figure 6 as shown below:

Figure 4. Switch ON mode of operation.

Figure 5. Switch OFF mode of operation.

(a)	(b)

 

(c)

Figure 6. Equivalent circuit for DCM (a) L1 enters to DCM (b) L2 enters to DCM (c) L1 and L2 both enter to DCM

Comment 4. The writing need to be improved.

Response #4: The authors are thankful to the reviewer for the suggestions, we have tried to improve the manuscript as suggested.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

1. All variables with subscripts should be correctly given in the equations.

2. In addition to voltage gain, it is difficult for readers to know what advantages/advances can be found in the proposed converter.

3. In Table 2, how to determine all the values of the parameters?

4. How about the values of the parameters for DCM? Are there reasons for the DCM of the proposed converter? From (25), (28), (29), and (30), I cannot find the advantages of the DCM converter.

5. In Fig. 8, the green line is missing.

Author Response

Comment 1. All variables with subscripts should be correctly given in the equations.

Response #1: The authors are thankful to the reviewer for the suggestions, we found a typo in an equation which is updated as follows:

(4)

 

Comment 2. In addition to voltage gain, it is difficult for readers to know what advantages/advances can be found in the proposed converter.

Response #2: The authors are thankful to the reviewer for the suggestion, the advantages of the converter are explained in the section proposed converter we also added a few more sentences to make it easier for the reader to understand. The addition is given below:

This circuit has the advantage of having only two switches (S1 and S2) operated together that is same control signal is used to control the converter output with lower complexity, continuous input current, and engaging energy with a single input DC source. The proposed buck-boost converter is capable to provide a non-inverting output voltage.

Comment 3. In Table 2, how to determine all the values of the parameters.

Response #3: The authors are thankful to the reviewer for the query, The values of the parameters can be selected based on the equations presented in section 2.1.3 Selection of Passive Components, however in this paper, we selected overrated components based on the availability in the lab, but for proper design, it is recommended to calculate these values to enhance the efficiency.

Comment 4. How about the values of the parameters for DCM? Are there reasons for the DCM of the proposed converter? From (25), (28), (29), and (30), I cannot find the advantages of the DCM converter.

Response #4: The authors are thankful to the reviewer for the query, we have calculated the gain for DCM but it is not recommended to operate the converter in DCM as it makes the control complex.

Comment 4. In Fig. 8, the green line is missing.

Response #4: The authors are thankful to the reviewer for the query, we are extremely sorry it was a format error now it is correct as follows:

(a)	(b)

Figure 8. Comparison with other converters (a) Voltage gain (b) Switch voltage stress.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

About the response to comment #3:

a) Table II shows that the parameter values of C2, C3, and C4 are the same. However, from (20)-(22) we can find that the requested voltage ripples are not the same under the same parameter values. This is why I need to know how to determine the parameters values in the experimental work.

b) Also, the value of C1 is larger than C2 and C3. Is this due to the request of the same voltage ripple?

Author Response

Reviewer#2

About the response to comment #3:

a) Table II shows that the parameter values of C2, C3, and C4 are the same. However, from (20)-(22) we can find that the requested voltage ripples are not the same under the same parameter values. This is why I need to know how to determine the parameters values in the experimental work.

b) Also, the value of C1 is larger than C2 and C3. Is this due to the request of the same voltage ripple?

Response: The authors are thankful to the reviewer for the clarification of the comments, (a) authors do agree that the voltage ripple is not the same under the same parameters for C2, C3 and C4. C4 is chosen at higher values than the calculated because we need less ripple at the output. The calculated value of capacitances is the minimum value required for maintaining the ripple below the desired value. The higher values of the capacitances are taken in our prototype just to ensure that the ripple is reduced further. (b) We need to consider the voltage rating of the capacitor as well to prevent the breakdown of the capacitor, so a higher voltage rating is selected for C2 and C3 as compared to C1. We have added some extra lines in the capacitor selection section as well as in the hardware verification section as follows:

The selection of the capacitors could be done based on the permissible ripple in the voltage across them as well as the magnitude of the voltage across the capacitor. Therefore, the selection of a capacitor should be done by considering a range of the duty ratio so that the selected capacitor does not burst that is the voltage rating of the capacitor should be high enough to support the maximum voltage across it.

 

The calculated value of capacitances is the minimum value required for maintaining the ripple below the desired value. The higher values of the capacitances are taken in our prototype just to ensure that the ripple is reduced further. We need to consider the voltage rating of the capacitor as well to prevent the breakdown of the capacitor, so a higher voltage rating is selected for C2 and C3 as compared to C1.

Author Response File: Author Response.pdf