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Battery Degradation Minimization-Oriented Hybrid Energy Storage System for Electric Vehicles

Energies 2020, 13(1), 246; https://doi.org/10.3390/en13010246

by Cong Zhang¹

, Dai Wang^1,2,*, Bin Wang¹ and Fan Tong¹

Reviewer 1: Anonymous

Reviewer 2:

Christophe Savard

Reviewer 3: Anonymous

Energies 2020, 13(1), 246; https://doi.org/10.3390/en13010246

Submission received: 4 November 2019 / Revised: 31 December 2019 / Accepted: 2 January 2020 / Published: 3 January 2020

(This article belongs to the Section E: Electric Vehicles)

Round 1

Reviewer 1 Report

The submitted manuscript has a few serious drawbacks. You don't explain numerous abbreviations, e.g., ESS, PWM. Reference [20] in not the one mentioned in the line 74. I don't know what "un-directional" means. Line 123: "Full" should be replaced by "Fully". Line 61/62 "the other two other" should be changed.

The discussion and the Figures 1-10 is unclear to me.

Figure 11 is without any serious value. We can report different results. The same problem is with table 1. Different cars will have different values.

The proposed control strategy diagram is very detailed. I suppose that for another case/car we should get different scheme.

Figure 13 - you see very intense fluctuations in both cases. How can you compare these values? You should apply some statistical parameters.

Figure 15 - I don't understand where is "degradation"

Author Response

Question 1：

The submitted manuscript has a few serious drawbacks. You don't explain numerous

abbreviations, e.g., ESS, PWM.

Reply 1:

Thanks for the comment. We add the explanation for the missing abbreviations.

Question 2：

Reference [20] in not the one mentioned in the line 74.

Reply 2:

Thanks for your comment. After double checking, the reference [20] is the reasonable. Please check the section

III. ANALYSIS OF THE PROPOSED RBS

Control strategy of the proposed RBS

3) The PI controller

In order to avoid the potential confusion, we revised the original description as following:

In order to improve the regenerative braking energy, Naseri et al. improved an improved regenerative braking system. The PI controller is used to adjust the braking torque by regulating the duty-cycle of the PWM algorithm. The features of the improved regenerative braking system can achieve constant torque regenerative braking for realizing comfort and security purposes. [20].

Question 3:

I don't know what "un-directional" means. Line 123: "Full" should be replaced by

"Fully".

Reply 3: This is a typo. Thanks for pointing it out. We have corrected the phase from “undirectional” to “unidirectional” across the whole manuscript. The “Full” is changed to “fully” across to the whole manuscript, too.

Question 4:

Line 61/62 "the other two other" should be changed.

Reply 4: Corrected now. Thanks for your comment.

Question 5:

The discussion and the Figures 1-10 is unclear to me.

Reply 5:

Figure 1 and figure 2 are the typical HESS topologies. As a reference, many other literatures introduce the HESS by using the similar diagram. Such as:

Figure 3 is the overall structure for the proposed topology. In this diagram, the dotted box shows the DC/DC converter. The switch S1 and S2, which control the current direction, build the whole HESS structure together with the DCDC converter, battery, and supercapacitor. In order to show the direction of current clearly, the red arrow shows the driving power flow. In contrast, the green arrow shows the regenerative energy flow in the energy storage system. Figure 4 to figures 9 shows the modes that the battery and supercapacitor work during the driving or breaking.

Question 6:

Figure 11 is without any serious value. We can report different results. The same problem

is with table 1. Different cars will have different values.

Reply 6:

Exactly as you said, different cars will have different values. In this research, we adopt one kind of battery and supercapacitor unit(Table 1), which is also used in other research:

Shen, Junyi, Serkan Dusmez, and Alireza Khaligh. "Optimization of sizing and battery cycle life in battery/ultracapacitor hybrid energy storage systems for electric vehicle applications." IEEE Transactions on industrial informatics4 (2014): 2112-2121.

In our research, we are exploring a controlled hybrid energy storage system, and picking the passenger care-Nissan Leaf as example. After analyzing the driving features, we extract the typical driving requirements as shown in figure 11. You can also refer to the another reference for the details:

Zhang, Cong, et al. "Using CPE function to size capacitor storage for electric vehicles and quantifying battery degradation during different driving cycles." Energies11 (2016): 903.

Question 7:

The proposed control strategy diagram is very detailed. I suppose that for another case/car

we should get different scheme.

Reply 7:

Exactly as you said, different vehicles will have different configuration. In this paper, we came up with a hardware topology and the control strategy. Of course, this method can also work on other vehicles, such as the medium heavy-duty vehicles. Though the configuration parameters will change, the methodology is applicable across different vehicles. Such as the other literatures as following, the similar method are used.

Cao, Jian, and Ali Emadi. "A new battery/ultracapacitor hybrid energy storage system for electric, hybrid, and plug-in hybrid electric vehicles." IEEE Transactions on power electronics1 (2011): 122-132. Song, Ziyou, et al. "Multi-objective optimization of a semi-active battery/supercapacitor energy storage system for electric vehicles." Applied Energy135 (2014): 212-224. Shen, Junyi, Serkan Dusmez, and Alireza Khaligh. "Optimization of sizing and battery cycle life in battery/ultracapacitor hybrid energy storage systems for electric vehicle applications." IEEE Transactions on industrial informatics4 (2014): 2112-2121.

Question 8:

Figure 13 - you see very intense fluctuations in both cases. How can you compare these

values? You should apply some statistical parameters.

Reply 8:

Thanks for your comments. In Table 4, Figure 16, and Table 5, the battery degradation result is compared. Especially for Table 4, the column of HWFET matches the Figure 13. From Table 4, the battery degradation result can be seen across different topologies. Figure 13 shows that: compared to the battery solely case, the peak discharging can be avoided in the HESS case. In this research, the battery degradation is used to evaluate the benefit of the optimized HESS. According to the battery degradation model (reference followed), the larger current flow lead to a larger battery degradation rate. As a supplementary material, Figure 14 shows the battery current distribution between the battery solely and optimized HESS cases. In figure 14, it shows the distribution of electric current could remove the aggressive battery discharging.

Wang, John, et al. "Degradation of lithium ion batteries employing graphite negatives and nickel–cobalt–manganese oxide+ spinel manganese oxide positives: Part 1, aging mechanisms and life estimation." Journal of Power Sources269 (2014): 937-948.

Question 9:

Figure 15 - I don't understand where is "degradation

Reply 9:

Thanks for pointing it out. We labeled the incorrect title for Figure 15. Now it is revised: The combined driving cycle.

Author Response File: Author Response.docx

Reviewer 2 Report

The article presents a battery-supercapacitor (SC) association associated with a control algorithm based on different SC load thresholds, without adding additional power electronics circuits compared to existing solutions. The results presented show that the proposal succeeds in competing with the most effective current solutions for an advertised installation as less expensive.

If the article is written in a classic way, it needs to be significantly improved in order to be published. It lacks many references. Most of the terms used are not defined when they first occur. Links between the parts are missing as well as between the equations and the text. The plan is missing. The level of English does not appear sufficient. Some blunders in the terms are to correct (example: bidirectional diode). Some simplifications (temperature not taken into account, impact on the SC aging because of decrease of the battery aging) are neither specified nor justified nor referenced. The curiosity of the reader is sometimes solicited but unanswered (how does the proposed system behave when the requested power is greater than what can be provided ?)

The subject of this article has the potential to be published, but for this, its content will have to be expanded, completed and present a patina more scientific, adding more points of the state of the art (especially on aggravating factors of battery aging).

Points to be developed or added to make paper fall within the scope of acceptability:

Rows 42 and others: add references respectively for each of these points: strong discharge currents accelerate the degradation; cycling frequency; deep of discharge.

Row 43, reference [8]: is there not, in addition, more recent references?

Row 83: was there a cost / benefit analysis done in a review or elsewhere?

Row 122: why? There are no references justifying this statement.

Row 145: Ditto (for the influence of Deep Of Discharge, certainly).

Row 160: what is a "bidirectional diode"? If, in the text, the description is correct (bidirectional switch), why represent this by a diode which, by definition, is unidirectional?

Row 161: a summary with the most and least of the 8 solutions and a classification proposal would be welcome and would introduce point 2.

Row 162: the plan of the article should be present (here, for example).

Row 167: give a quick overview of useful features for the use that is made of it.

Row 169: why 4 diodes? Two switches (thus MOS) + a MOS + 1 diode are visible in the diagram.

Row 170: the reader expects to find a description of the driving phases associated with the different modes. What driving phases? A summary of modes, charging and discharging modes for batteries and SC, S1 and S2 states, corresponding driving phase for the EV, in a table would synthesize the presentation effectively.

Row 172: the parameter "K0" appears without having been presented before. The reader wonders what this parameter represents and means. He finds the answer (twice) too far in the text. It's a pity not to give this equation (which should be numbered so that it can be referenced in these lines) for the first time so late in the paper, at row 292.

Row 294: similarly, all this should have been presented before.

Row 196: Ditto for P threshold.

Row 228: Ditto for ma, mg, A, B, v ...

Row 245: what is Ebat, Eall and Esc? Why choose Ecap and not Esc?

Row 256: same for A, B, C.

Row 345: Ditto for all parameters used in this formula.

Row 355: same with these settings.

Row 174: is the relationship between SoC and Vsc linear? If so, say it and give the equation, if not rewrite the sentence.

Row 190: at a time, in the article, it will be necessary to specify how are controlled S1 and S2.

Row 223: so where does the excess energy go if the engine still brakes and the battery is fully charged?

Row 243: specify how the value of 76 is obtained, without the reader having to re-read all previous articles.

Row 349: explain in a few words what is "calendar aging".

Row 351: not only! Explain why temperature is not considered in the study. On the other hand, the high densities of current lead to an accelerated aging, does the addition of SC make it possible to reduce the influence of this parameter on the aging? Cite classical references and justify approximations made for the study.

Row 354: in the end, does the SC aging compensate this of the battery?

Rows 366-368: the reader remains unsatisfied: how is the case dealt with when the demand for power is greater than what can be provided?

Row 377: specify this value, especially why not go below a SoC <0.5. Specify one or more references.

Row 384: reference?

Row 385: describe what the "infinite SC case" is.

+ This study is presented in the form of a simulation, will it be followed by an experimental part?

+ Some possible tracks (non-exhaustive list) for references:

Redondo-Iglesias, E.; Venet, P.; Pelissier, S. Global Model for Self-Discharge and Capacity Fade in Lithium-Ion Batteries Based on the Generalized Eyring Relationship. IEEE Transactions on Vehicular Technology, 2018, 67.

Xu, B.; Ondalov, A.; Ulbig, A.; Andersson, G.; Kirschen, D.S. Modeling of Lithium-Ion Battery Degradation for Cell Life Assessment. IEEE Trans. Smart Grid 2018, 9, 1131–1140.

Savard C.; Venet, P.; Niel, E.; Pietrac, L.; Sari, A. Comparison of Battery Architecture Dependability. Batteries, 2018, 4.

Broussely, M.; Biensan, P.; Bonhomme, F.; Blanchard, P.; Herreyre, S.; Nechev, K.; Staniewicz, R.J. Main aging mechanisms in Li ion batteries. J. Power Sources 2005, 146, 90–96.

Savard C.; Iakovleva E.V, A Suggested Improvement for Small Autonomous Energy System Reliability by Reducing Heat and Excess Charges. Batteries, 2019, 5.

Zhang, Y.; Xiong, R.; He, H.; Pecht, M. Lithium-ion battery remaining useful life prediction with Box-Cox transformation and Monte Carlo simulation. IEEE Trans. Ind. Electron. 2018, 99.

German, R.; Venet, P.; Sari, A.; Briat, O. & Vinassa, J. Improved Supercapacitor Floating Aging Interpretation Through Multipore Impedance Model Parameters Evolution. IEEE Tranasctions on Power Electronics, 2014, 29, 3669-3678.

Points to be corrected or improved:

Row 10-11: the sentence is strange and cryptic.

Row 21: specify at the first occurrence (at least in the text) the meaning of these acronyms.

Rows 20 and 442: the introduction and the conclusion are redundant. It would be better to give a desire to read the article in the introduction, to find the results quantified and commented in the penultimate part and to summarize the results in the conclusion.

Row 34: a logical link between the two sentences is missing.

Row 39: clarify the meaning of the term ESS.

Rpw 48: what does "Importing ... not only help to avoid" mean?

Row 80: "According to the previous literature, the full function of battery / SC topology and the DC / DC cost are contradictory". So the reader concludes that achieving the full function is not expensive.

Row 85: this has already told row 43 and 51. Would not it be wiser to just announce it here in conclusion?

Row 100: it misses the link with the following equations.

Row 110-111: incomprehensible sentence.

Row 145: what is a "discharge overload", a deep discharge or something else?

Row 164: so, Figure 3 draws on what previous scheme?

Row 229: what is "down curve"?

Row 231: universally or for this study?

Row 236: present rather according to international standards, so in kilometers.

Row 338: "According to the previous research", which one?

Row 348: but only with the scheme proposed in point 3?

Row 415: Ditto kilometers rather than miles.

Row 415: 123%. Why ?

Row 434: what does (10-4) mean?

Form points:

Row 17: "minimum" or "minimize"?

+ Presentation of references and formulas: leave a space before each reference and each parenthesis (eg References 1 to 9, "HESS", row 50, "figure1 (b)" row 109, row 407 ...

Row 49: "the previous study" which one? The referenced [11]?

Row 59: the effects on what?

Row 105: "topology than that in other topologies". "That": is this correct?

Row 112: the potential of what?

Row 113: "in case that the SC", idem row 105.

Row 184: if the legend of Mode 1 is written in active form in the present, the same must be true for all legends of other Modes.

Row 225: verb?

Rows 227, 240: "the demanded power +Pdemand+ as following".

Row 338-339: what does this sentence mean?

Row 388: : instead of - .

Row 430: rewrite the legend, evolution of the speed during the test rather?

Author Response

Points to be developed or added to make paper fall within the scope of acceptability:

Rows 42 and others: add references respectively for each of these points: strong discharge currents accelerate the degradation; cycling frequency; deep of discharge.

Reply: add reference[1,4,7]

Row 43, reference [8]: is there not, in addition, more recent references?

Reply: add reference[1,4,6-8]

Row 83: was there a cost / benefit analysis done in a review or elsewhere?

Reply: add reference[10,16]

Row 122: why? There are no references justifying this statement.

Reply: add reference[10,11,16]

Row 145: Ditto (for the influence of Deep Of Discharge, certainly).

Reply: Revise the original content accordingly.

Row 160: what is a "bidirectional diode"? If, in the text, the description is correct (bidirectional switch), why represent this by a diode which, by definition, is unidirectional?

Reply: Thanks for pointing it out. It is a typo. In the figure 2c, it should be “semi-active configuration incorporated (bidirectional)”. In this research, we are using the unidirectional converter. Compared to the bidirectional converter, the cost of unidirectional converter is much cheaper.

Row 161: a summary with the most and least of the 8 solutions and a classification proposal would be welcome and would introduce point 2.

Reply: For the summary context from 1.1 to 1.7, it matches these 7 HESS structures, respectively. As to the the proposed HESS in this paper, it matches the section 2, including 4 driving modes, and 3 breaking modes.

Row 162: the plan of the article should be present (here, for example).

Reply: This article supplies an improved semi-activate HESS topology, and contributes a method to determine the threshold of key controlled parameters. By using the battery degradation as evaluation factor, the proposed HESS has advantages on mitigating the battery degradation.

Row 167: give a quick overview of useful features for the use that is made of it.

Reply: newly added: All driving situations can be divided into one of seven driving modes. It covers 3 modes in driving condition, and 3 modes in breaking condition.

Row 169: why 4 diodes? Two switches (thus MOS) + a MOS + 1 diode are visible in the diagram.

Reply: Thanks for pointing it out. We update the title of figure 3 to “Proposed HESS topology.” In this system, there two switches and 1 diode.

Reply: I guess you are indicating the driving condition. In total, there are two diving conditions: driving and breaking, including 4 driving modes, and 3 breaking modes, respectively. When selecting the individual mode, the control strategy analyzes the power demand, SOC, and deactivate or activate the switches. The article is organized based on each mode.

Reply: update the description of K0, K1, and K2 are the thresholds, and move the description to beginning of section 2.

Row 294: similarly, all this should have been presented before.

Reply: Similar to the previous comment. It is moved to the beginning of section 2.

Row 196: Ditto for P threshold.

Reply: Uniformed the threshold of power - P_threshold

Row 228: Ditto for ma, mg, A, B, v ...

Reply: Added the description for equation 3 and 4.

Row 245: what is Ebat, Eall and Esc? Why choose Ecap and not Esc?

Reply: represents the configured battery package capacity.represents the total energy requirement for the vehicle energy supply source. represents the configured supercapacitor package capacity. Also, replaced the Ecap by using Esc.

Row 256: same for A, B, C.

Reply: We add the description for A,B,C.

Row 345: Ditto for all parameters used in this formula.

Reply: updated.

Row 355: same with these settings.

Reply: updated.

Row 174: is the relationship between SoC and Vsc linear? If so, say it and give the equation, if not rewrite the sentence.

Reply: updated. The is equal to the ratio between the voltage square and the maximum voltage square.

Row 190: at a time, in the article, it will be necessary to specify how are controlled S1 and S2.

Reply: the switch S1 is the connection between the battery and motor. Once the energy flow transfer between the battery and motor, S1 will be connected. In contrast, switch S2 is the connection between the supercapacitor and motor. Once the energy flow transfer between the battery and motor, S2 will be connected.

Row 223: so where does the excess energy go if the engine still brakes and the battery is fully charged?

Reply: Generally speaking, this situation is not a frequent mode. But there is an exception when the vehicle is charged to full, and the vehicle is driving downhill. In this case, both S1 and S2 are disconnected. In battery management system, there is protection function for the battery to avoid the overcharging.

Row 243: specify how the value of 76 is obtained, without the reader having to re-read all previous articles.

Reply: There are 3 steps:

Calculate the overall energy requirement for power supply system Using the extreme acceleration driving mode to calculate the energy requirement for the SC Get the energy requirement for battery, and divided by the battery cell parameters

Row 349: explain in a few words what is "calendar aging".

Reply: The battery degradation results from time going.

Reply: This is a quite good question. However, we are using the energy requirement to configure the battery and SC size. The temperature is a complicated factor. For car with same configuration, the vehicle’s mileage is various across the different driving situation, including the temperature. We prefer to use the security factor to adjust the size of power system. Similar research as following:

In terms of the academic research, the addition of SC makes it possible to reduce the influence of this parameter on the aging. However, it is not worthwhile to keep increasing the size of SC. Besides the benefit, the cost, weight and volume are important factors affect the SC size configuration. Refer to our earlier publication:

Zhang, Cong, Haitao Min, Yuanbin Yu, Qingnian Wang, and Huanli Sun. "A new method to optimize semiactive hybrid energy storage system for hybrid electrical vehicle by using pe function." Mathematical Problems in Engineering2015 (2015).

Row 354: in the end, does the SC aging compensate this of the battery?

Reply: The result shows the SC could mitigate the battery aging largely. This is an effective method to configure the battery and SC for the passenger cars.

Rows 366-368: the reader remains unsatisfied: how is the case dealt with when the demand for power is greater than what can be provided?

Reply: This is an excellent question. Honestly speaking, majority vehicles has the potential issues that the demand for power is greater than what can be provided. In this research, we are using the Nissan Leaf as a comparable model to supply the power demand. For the EV, the reason of this issue is usually from the motor, rather than the battery. If the customer wants to get better power supply, they have to spend more money to upgrade their vehicle components, such as the motor, power system.

Row 377: specify this value, especially why not go below a SoC <0.5. Specify one or more references.

Reply: Thanks, the following reference are cited.

Cao, Jian, and Ali Emadi. "A new battery/ultracapacitor hybrid energy storage system for electric, hybrid, and plug-in hybrid electric vehicles." IEEE Transactions on power electronics1 (2011): 122-132. Shen, Junyi, Serkan Dusmez, and Alireza Khaligh. "Optimization of sizing and battery cycle life in battery/ultracapacitor hybrid energy storage systems for electric vehicle applications." IEEE Transactions on industrial informatics4 (2014): 2112-2121.

Row 384: reference?

Reply: Thanks, the following reference are cited.

Row 385: describe what the "infinite SC case" is.

Reply: The infinite SC case means that the SC is configured large enough and the SC can supply unlimited power. In reality, the infinite SC case cannot be realized because of the actual cost constraint.

+ This study is presented in the form of a simulation, will it be followed by an experimental part?

Reply: Thanks for this question. Yes, we plan to do the experimental validation in future work.

+ Some possible tracks (non-exhaustive list) for references:

Redondo-Iglesias, E.; Venet, P.; Pelissier, S. Global Model for Self-Discharge and Capacity Fade in Lithium-Ion Batteries Based on the Generalized Eyring Relationship. IEEE Transactions on Vehicular Technology, 2018, 67.

Xu, B.; Ondalov, A.; Ulbig, A.; Andersson, G.; Kirschen, D.S. Modeling of Lithium-Ion Battery Degradation for Cell Life Assessment. IEEE Trans. Smart Grid 2018, 9, 1131–1140.

Savard C.; Venet, P.; Niel, E.; Pietrac, L.; Sari, A. Comparison of Battery Architecture Dependability. Batteries, 2018, 4.

Broussely, M.; Biensan, P.; Bonhomme, F.; Blanchard, P.; Herreyre, S.; Nechev, K.; Staniewicz, R.J. Main aging mechanisms in Li ion batteries. J. Power Sources 2005, 146, 90–96.

Savard C.; Iakovleva E.V, A Suggested Improvement for Small Autonomous Energy System Reliability by Reducing Heat and Excess Charges. Batteries, 2019, 5.

Zhang, Y.; Xiong, R.; He, H.; Pecht, M. Lithium-ion battery remaining useful life prediction with Box-Cox transformation and Monte Carlo simulation. IEEE Trans. Ind. Electron. 2018, 99.

German, R.; Venet, P.; Sari, A.; Briat, O. & Vinassa, J. Improved Supercapacitor Floating Aging Interpretation Through Multipore Impedance Model Parameters Evolution. IEEE Tranasctions on Power Electronics, 2014, 29, 3669-3678.

Reply: Thank you very much for the literature recommendation.

Points to be corrected or improved:

Row 10-11: the sentence is strange and cryptic.

Reply: When coordinating the battery and supercapacitor, the proposed system avoids using the large bidirectional DC/DC.

Row 21: specify at the first occurrence (at least in the text) the meaning of these acronyms.

Reply: updated.

In abstract, avoid presenting the exact number

In the penultimate part, keep its original shape.

in the conclusion: Avoid the redundant description.

Row 34: a logical link between the two sentences is missing.

Reply: updated.

However, there are two concerns in the lithium battery application, including the expensive energy capacity and the limited driving environment, which limits the promotion of electric cars.

Row 39: clarify the meaning of the term ESS.

Reply: updated. In the energy storage system (ESS) configuration, the charging mileage requirement should be met firstly

Rpw 48: what does "Importing ... not only help to avoid" mean?

Reply: updated.

As the power source, the SC can supply higher power. Adding the supercapacitor to the energy storage system, the frequent discharging and charging flow across the battery can be avoided [10,11].

Reply: updated.

According to the previous literature, the fully function of battery/SC topology and the DC/DC cost are expensive and complicated

Row 85: this has already told row 43 and 51. Would not it be wiser to just announce it here in conclusion?

Reply: Appreciate the comments. We remove the duplicated description in Row 85.

Row 100: it misses the link with the following equations.

Reply: updated.

The SOC of SC is calculated as following:

Row 110-111: incomprehensible sentence.

Reply: updated.

Because of the bidirectional DC/DC converter, the working voltage range of SC is much wider than that in basic passive topology.

Row 145: what is a "discharge overload", a deep discharge or something else?

Reply: updated.

According to the battery chemical principle, the deep discharge damages battery health seriously, including the influence of deep of discharge, certainly.

Row 164: so, Figure 3 draws on what previous scheme?

Reply: updated.

On purpose of improving the current topology, this study comes up with a new semi-active HESS topology (Figure 3).

Row 229: what is "down curve"?

Reply: updated.

Coast down is one of the most frequent tests for mot or vehicles and consists in vehicle launch from a certain speed with the engine ungeared, simultaneously recording the speed and travelled distance until vehicle stops. This can be done for different reasons, mainly targeting to obtain valuable information about the general condition of the vehicle and about its interaction with the environment.

Row 231: universally or for this study?

Reply: For this research. However, some other literature also use this battery cell for research.

Row 236: present rather according to international standards, so in kilometers.

Reply: updated.

Row 338: "According to the previous research", which one?

Reply: updated.

According to the previous literature, the battery cycle degradation rate is influenced by the cumulative integral of circuit and instant discharging value[31].

Wang, Dai, Jonathan Coignard, Teng Zeng, Cong Zhang, and Samveg Saxena. "Quantifying electric vehicle battery degradation from driving vs. vehicle-to-grid services." Journal of Power Sources332 (2016): 193-203.

Row 348: but only with the scheme proposed in point 3?

Reply: Yes. Only the cycle degradation is related to the HESS topology, which matches the section 3.

Row 415: Ditto kilometers rather than miles.

Reply: updated.

Row 415: 123%. Why ?

Reply: updated.

The Table 4 failed to show the unit of degradation. Unit: Battery degradation (10^-4)

Row 434: what does (10-4) mean?

Reply: updated. It should be (10^-4).

Form points:

Row 17: "minimum" or "minimize"?

Reply: updated.

+ Presentation of references and formulas: leave a space before each reference and each parenthesis (eg References 1 to 9, "HESS", row 50, "figure1 (b)" row 109, row 407 ...

Reply: updated.

Row 49: "the previous study" which one? The referenced [11]?

Reply: updated.

The literatures describe the advantages of the hybrid energy storage system(HESS) [12].

Row 59: the effects on what?

Reply: updated.

The passive topology is simple, inexpensive, and the effect on protecting the battery is also the least[15].

Row 105: "topology than that in other topologies". "That": is this correct?

Reply: updated.

Equally, in order to realize the same usable energy in SC, the SC size requirement will be higher in the basic passive parallel topology than other topologies which use DC/DC converter.

Row 112: the potential of what?

Reply: updated.

A wider SC voltage range is conducive to the potential charging/discharging capacity of the SC.

Row 113: "in case that the SC", idem row 105.

Reply: updated.

In case that the SC does not have enough usable energy stored, the DC/DC converter has to be set big enough to supply high power from the battery to the motor.

Row 184: if the legend of Mode 1 is written in active form in the present, the same must be true for all legends of other Modes.

Reply: All models are revised to active form in the present

Row 225: verb?

Reply: Tt is “vehicle model specification”. Not verb.

Rows 227, 240: "the demanded power +Pdemand+ as following".

Reply: updated.

Row 338-339: what does this sentence mean?

Reply: updated.

In HESS, the lithium battery contributes the majority needed energy.

Row 388: : instead of - .

Reply: updated.

Row 430: rewrite the legend, evolution of the speed during the test rather?

Reply: updated.

Author Response File: Author Response.docx

Reviewer 3 Report

The paper is interesting but some issues must be improved:

The use of english language should be improved in all the paper. Parameters in Equations (3) and (4) must be clarified. Figure 11 reference is needed. Parameters in equations (10-12) must be clarified. In line 369 authors claim that "the algorithm uses the automatically searching strategy to explore the optimized configuration for the parameters" but do not explain the optimization strategy. Authors must explain the searching strategy. In line 410 say that "after searching, four parameters sets are calculated". What does searching mean? Authors must clarify how the parameters are calculated. The battery degradation quantification calculations are not clear in the paper. What does refer 1a, refer 1b, refer 2a, refer 2c mean in figure 16?

Author Response

Question：

The paper is interesting but some issues must be improved:

1.The use of english language should be improved in all the paper. 2.Parameters in Equations (3) and (4) must be clarified. 3.Figure 11 reference is needed. 4.Parameters in equations (10-12) must be clarified. 5. In line 369 authors claim that "the algorithm uses the automatically searching strategy to explore the optimized configuration for the parameters" but do not explain the optimization strategy. 6. Authors must explain the searching strategy. In line 410 say that "after searching, four parameters sets are calculated". What does searching mean? Authors must clarify how the parameters are calculated. 7. The battery degradation quantification calculations are not clear in the paper. What does refer 1a, refer 1b, refer 2a, refer 2c mean in figure 16?

Reply:

Thank you for your comment very much. Our replies are as following:

The English is edited thoroughly across the whole manuscript. Equation 3 and 4 are the driving resistance and coast down curve. We added the detailed description in the manuscript.is the vehicle weight, unit: is the acceleration of vehicle, unit: m/s². is the gravitational acceleration, equal to 9.8 m/s². is the coast down curve for the vehicle, including the rolling resistance and the aerodynamic resistance. is the empirical resistance equation for vehicle. A/B/C are the fitted parameters of the coast down curve. A: unit is N, B: unit is N·s/m, C: unit is N·s²/m². The original reference resource is from 2009 National Household Travel Survey. In another publication, we converted the raw survey data to the bar figure. The reference has been added to the manuscript. Zhang, Cong, et al. "Using CPE function to size capacitor storage for electric vehicles and quantifying battery degradation during different driving cycles." Energies11 (2016): 903. The detailed description for equation 10-12 has bee added to the manuscript.

where and are pre-exponential factors, T is the absolute temperature, / are fitted from curve, is the current C rate, represents the amount of charge delivered by the battery during cycling, T is the days, is the activation energy in J·mol−1, and R is the gas constant. These parameters values are listed in [31].

Wang, Dai, Jonathan Coignard, Teng Zeng, Cong Zhang, and Samveg Saxena. "Quantifying electric vehicle battery degradation from driving vs. vehicle-to-grid services." Journal of Power Sources 332 (2016): 193-203. We failed to refer to Table 3 for the searching method. It is an itinerate loop to find the optimized parameters set for the thresholds. It has been updated in the manuscript. To avoid the confusion, we revise the description as following:

After launching the searching algorithm, four parameters sets can be deduced for any specific driving cycle. The “searching” means the process of looking for the best parameter set for K0/K/K2 and P_threshold. Table 3 is the diagram of searching method.

The battery degradation model is based on our previous model in reference[31]. Wang, Dai, Jonathan Coignard, Teng Zeng, Cong Zhang, and Samveg Saxena. "Quantifying electric vehicle battery degradation from driving vs. vehicle-to-grid services." Journal of Power Sources 332 (2016): 193-203.

refer 1a indicates the HESS structure which is shown in Figure 1(a).

refer 1b indicates the HESS structure which is shown in Figure 1(b).

refer 2a indicates the HESS structure which is shown in Figure 2(a).

refer 2c indicates the HESS structure which is shown in Figure 2(c).

These four topologies represent the common structures that the HESS are using now. We built the power system model and got the current profiles, then launched the battery degradation model and estimated the battery degradation. The final battery degradation profiles are shown in Figure 16. Compared with the other common HESS structures, it is clearly to see the proposed HESS has advantages on the battery degradation mitigation.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The manuscript can be published in the present form.

Author Response

Thank you for reviewing this paper. In the updated file,

1) checked the grammar across the full-text thoroughly.

2) corrected a few typos across the full text thoroughly.

3) add a paragraph to describe the paper structure.

Reviewer 2 Report

Points to be developed or added to make paper fall within the scope of acceptability:

Rows 42 and others: add references respectively for each of these points: strong discharge currents accelerate the degradation; cycling frequency; deep of discharge.

Reply: add reference[1,4,7]

Review 2 : Mention of already mentioned references does not bring much improvement. The main causes of aging aggravation should be mentioned (strong discharge, high currents, deep of discharge...) and specific references for these points should be added.

Row 43, reference [8]: is there not, in addition, more recent references?

Reply: add reference[1,4,6-8]

Review 2 : 1999 is not a recent date.

Row 145: Ditto (for the influence of Deep Of Discharge, certainly).

Reply: Revise the original content accordingly.

Review 2 : If I was written "certainly" in my remark, it is to point out that the DoD was perhaps not the only cause. This term has nothing to do in a scientific paper.

Row 162: the plan of the article should be present (here, for example).

Review 2 : Plan is still missing. It is normal to find after the introductory part, a plan specifying as the article is written, so as to identify the conventional parts, such as the state of the art, the method, the results...

Review 2 : Hence the usefulness of an introductory sentence at the beginning of the chapter 2.1.

Points to be corrected or improved:

Row 355: same with these settings.

Reply: updated.

Review 2 : Eta-DC and Eta-SC still seem to lack.

Row 190: at a time, in the article, it will be necessary to specify how are controlled S1 and S2.

Review 2 : The text has not been modified in this way.

Row 223: so where does the excess energy go if the engine still brakes and the battery is fully charged?

Review 2 : The text has not been modified in this way.

Row 243: specify how the value of 76 is obtained, without the reader having to re-read all previous articles.

Reply: There are 3 steps:

Review 2 : The text has not been modified in this way.

Row 349: explain in a few words what is "calendar aging".

Reply: The battery degradation results from time going.

Review 2 : The text has not been modified in this way.

Review 2 : The text has not been modified in this way. If a reviewer has asked the question, a reader will be able to ask it himself. Add a short paragraph specifying your answer.

Form points:

Presentation of references and formulas: leave a space before each reference and each parenthesis (eg References 1 to 9, "HESS", row 50, "figure1 (b)" row 109, row 407 …

Review 2 : This has not been corrected everywhere, for example on rows 33, 43, 44...

Author Response

We appreciate your detailed comments. Our reply is in a different color as following. Also, the revised content is highlighted(in cyan) in the manuscript.

Points to be developed or added to make paper fall within the scope of acceptability:

Question 1:

Rows 42 and others: add references respectively for each of these points: strong discharge currents accelerate the degradation; cycling frequency; deep of discharge.

Reply: add reference[1,4,7]

Review 2: Mention of already mentioned references does not bring much improvement. The main causes of aging aggravation should be mentioned (strong discharge, high currents, deep of discharge...) and specific references for these points should be added.

Reply(round 2): Thanks for your guidance. Here is our update for this item.

As a result, the battery suffers high discharging current which accelerates the capacity degradation rate, that is to say, the strong discharge current accelerates the degradation [7]. Besides, frequent charging and discharging are harmful to battery life[8][9]. In some extreme driving situations, the battery may be overcharged and discharged, which reduces the battery lifecycle seriously [10][11].

Following reference:

[7] D. Wang, J. Coignard, T. Zeng, C. Zhang, S. Saxena, Quantifying electric vehicle battery degradation from driving vs. vehicle-to-grid services, J. Power Sources. 332 (2016) 193–203. https://doi.org/10.1016/j.jpowsour.2016.09.116.

[8] B.G. Carkhuff, P.A. Demirev, R. Srinivasan, Impedance-Based Battery Management System for Safety Monitoring of Lithium-Ion Batteries, IEEE Trans. Ind. Electron. 65 (2018) 6497–6504. https://doi.org/10.1109/TIE.2017.2786199.

[9] W. Zhang, J. Nie, F. Li, Z.L. Wang, C. Sun, A durable and safe solid-state lithium battery with a hybrid electrolyte membrane, Nano Energy. 45 (2018) 413–419. https://doi.org/10.1016/j.nanoen.2018.01.028.

[10] H.A. Serhan, E.M. Ahmed, Effect of the different charging techniques on battery life-time: Review, in: 2018 Int. Conf. Innov. Trends Comput. Eng. ITCE, 2018: pp. 421–426. https://doi.org/10.1109/ITCE.2018.8316661.

[11] M.S.H. Lipu, M.A. Hannan, A. Hussain, M.M. Hoque, P.J. Ker, M.H.M. Saad, A. Ayob, A review of state of health and remaining useful life estimation methods for lithium-ion battery in electric vehicles: Challenges and recommendations, J. Clean. Prod. 205 (2018) 115–133. https://doi.org/10.1016/j.jclepro.2018.09.065.

Question 2:

Row 43, reference [8]: is there not, in addition, more recent references?

Reply: add reference[1,4,6-8]

Review 2 : 1999 is not a recent date.

Reply(round 2): Reference is updated.

To solve the problem, the supercapacitor (SC) is usually configured to assist the peak power demand [12][13][14].

[12] M. Shadman, V.S. Raj, R. Dave, A. Pal, Hybrid energy storage system containing Bidirectional DC Convertor, Battery, Super capacitor, Solar Panel for increasing the performance of Electric Vehicles, in: 2018 Fourth Int. Conf. Adv. Electr. Electron. Inf. Commun. Bio-Inform. AEEICB, 2018: pp. 1–6. https://doi.org/10.1109/AEEICB.2018.8480910.

[13] L.H. Saw, H.M. Poon, W.T. Chong, C.-T. Wang, M.C. Yew, M.K. Yew, T.C. Ng, Numerical modeling of hybrid supercapacitor battery energy storage system for electric vehicles, Energy Procedia. 158 (2019) 2750–2755. https://doi.org/10.1016/j.egypro.2019.02.033.

[14] C. Zhang, H. Min, Y. Yu, Q. Wang, H. Sun, A new method to optimize semiactive hybrid energy storage system for hybrid electrical vehicle by using pe function, Math. Probl. Eng. 2015 (2015).

Question 3:

Row 145: Ditto (for the influence of Deep Of Discharge, certainly).

Reply: Revise the original content accordingly.

Review 2 : If I was written "certainly" in my remark, it is to point out that the DoD was perhaps not the only cause. This term has nothing to do in a scientific paper.

Reply(round 2): Thanks for your comments. We consider this question and think it looks appropriate to move this discussion to the introduction section. Combining with the other influence factors, e.g. strong discharge currents accelerate the degradation; cycling frequency; deep of discharge, all these contents are described in the introduction now. Also, we update the reference as suggested.

Question 4:

Row 162: the plan of the article should be present (here, for example).

Reply(round 2): New paragraph is added to chapter 1.

This paper is organized as follows. Section 2 stresses the topology structure of the proposed HESS, describes the working modes in both driving condition and braking condition. The strategy is presented in Section 3. It is a rule-based control strategy, which matches the proposed HESS closely. In Section 4, we explain the battery degradation model, which is chosen as the objective function of searching for the key parameters of the control strategy. Simulation results are shown in Section 5. Conclusions and future work are in Section 6.

Question 5:

Review 2 : Hence the usefulness of an introductory sentence at the beginning of the chapter 2.1.

Reply(round 2): We add the following paragraph to chapter 2.1.

The driving condition is the most frequent action for vehicles. During the driving conditions, 4 modes of HESS are divided. When selecting each individual mode, the control strategy and topology deactivate or activate the switches status by analyzing the power demand, battery, and SC SOC.

Points to be corrected or improved:

Question 6:

Row 355: same with these settings.

Reply: updated.

Review 2 : Eta-DC and Eta-SC still seem to lack.

Reply(round 2): New description is added in row 411- row 413.

Here, Eta-DC and Eta-SC are the DC/DC converter efficiency and SC coulombic efficiency, respectively. In this research, the DC/DC converter efficiency is set as 95%, and the SC coulombic efficiency is set as 92%[32,33].

Question 7:

Row 190: at a time, in the article, it will be necessary to specify how are controlled S1 and S2.

Review 2 : The text has not been modified in this way.

Reply(round 2): We add an extra paragraph at the end of section 2.2.

Across the above 7 modes, the switch S1 and S2 are the key components to control the current flow direction and route. In summary, the switch S1 is the connection between the battery and motor. Once the energy flow transfer between the battery and motor, S1 will be connected. In contrast, switch S2 is the connection between the supercapacitor and motor. Once the energy flow transfer between the battery and motor, S2 will be connected.

Question 8:

Row 223: so where does the excess energy go if the engine still brakes and the battery is fully charged?

Review 2 : The text has not been modified in this way.

Reply(round 2): We add an extra paragraph at the end of section 2.2.3 - mode 7.

There is an extreme situation when the battery driving downhill at a long distance. Because of the regenerative braking, the battery can be fully charged. In this situation, both S1 and S2 are disconnected.

Question 9:

ow 243: specify how the value of 76 is obtained, without the reader having to re-read all previous articles.

Reply: There are 3 steps:

Review 2: The text has not been modified in this way.

Reply(round 2): We add an extra paragraph in section 2.3.

According to the previous studying, the supercapacitor units can be set as 76[15]. Here is a brief introduction to the calculation process: first, the overall energy requirement for the power supply system is calculated by vehicle model and mileage requirement. Secondly, using the extreme acceleration driving mode to calculate the energy requirement for SC. Thirdly, Get the energy requirement for battery, and divided by the battery cell parameters.

Question 10:

Row 349: explain in a few words what is "calendar aging".

Reply: The battery degradation results from time going.

Review 2 : The text has not been modified in this way.

Reply(round 2): We add an extra paragraph in section 4.

The main object of this research is to explore the SC influence on battery degradation. There are two kinds of battery degradation: calendar degradation and cycle degradation. The calendar degradation results from time going, there is no much difference for different usage cases. In this paper, only the battery cycle loss is considered. From the above equations, the battery degradation loss can be concluded that the greater the battery discharge power, the faster the battery decaying.

Question 11:

Cao, Jian, and Ali Emadi. "A new battery/ultracapacitor hybrid energy storage system for electric, hybrid, and plug-in hybrid electric vehicles." IEEE Transactions on power electronics1 (2011): 122-132. Song, Ziyou, et al. "Multi-objective optimization of a semi-active battery/supercapacitor energy storage system for electric vehicles." Applied Energy135 (2014): 212-224. Shen, Junyi, Serkan Dusmez, and Alireza Khaligh. "Optimization of sizing and battery cycle life in battery/ultracapacitor hybrid energy storage systems for electric vehicle applications." IEEE Transactions on industrial informatics4 (2014): 2112-2121.

Review 2: The text has not been modified in this way. If a reviewer has asked the question, a reader will be able to ask it himself. Add a short paragraph specifying your answer.

Reply(round 2): We add the following description in section 2.3.

Besides, the temperature is an important factor that affects the HESS system. However, the temperature influence on the driving range is complicated. For a car with the same configuration, the vehicle’s mileage is various across the different driving situation, including the temperature. In this paper, we calculate the energy requirement and configure the battery and SC size under the room temperature environment.

Reviewer 3 Report

Thank you, all my comments have been addressed.

Author Response

Thank you for reviewing this paper. In the updated file,

1) checked the grammar across the full-text thoroughly.

2) corrected a few typos across the full text thoroughly.

3) add a paragraph to describe the paper structure.

Round 3

Reviewer 2 Report

Alright.

Author Response

Thank you very much for your review.

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Battery Degradation Minimization-Oriented Hybrid Energy Storage System for Electric Vehicles

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