KR20230046645A - EV battery performance evaluation method - Google Patents

EV battery performance evaluation method Download PDF

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KR20230046645A
KR20230046645A KR1020210129864A KR20210129864A KR20230046645A KR 20230046645 A KR20230046645 A KR 20230046645A KR 1020210129864 A KR1020210129864 A KR 1020210129864A KR 20210129864 A KR20210129864 A KR 20210129864A KR 20230046645 A KR20230046645 A KR 20230046645A
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battery
soc
discharge
state
residual value
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장석호
김형진
고용제
강일영
박형민
고현주
장소현
홍정현
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재단법인 제주테크노파크
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/392—Determining battery ageing or deterioration, e.g. state of health
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/16—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
    • G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
    • G01R19/16542—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies for batteries
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

Disclosed is a method of evaluating a residual value of an EV battery. Provided is a method, in which in order to shorten a process time, SOH is calculated under partial discharge which occurs in the (state of charge, SOC) of the battery rather than complete discharge, in evaluating a residual value of an EV battery by calculating (state of health, SOH) of the battery, (state of available power capability, SOP) of the battery, and cell voltage deviation (state of balance, SOB).

Description

전기차 배터리 잔존가치 평가 방법{EV battery performance evaluation method}EV battery residual value evaluation method {EV battery performance evaluation method}

본 발명은 배터리 평가 방법에 관한 것으로, 특히 전기차 사용 후에 배터리의 잔존가치를 평가하는 방법에 관한 것이다.The present invention relates to a method for evaluating a battery, and more particularly, to a method for evaluating a residual value of a battery after use of an electric vehicle.

국내등록특허공보 제10-2289155호에는 사용 후 배터리 등급 분류 공정 및 이를 제공하는 시스템에 대해 개시되어 있다. 이 공정 및 시스템은 전기차 또는 에너지저장장치로 사용된 배터리의 재사용·재제조를 위한 기술로서, 수거된 사용 후 배터리의 외관 검사, 전기 절연 검사, 성능 및 잔존수명 검사를 수행하고 이를 기반으로 재사용·재제조 등급을 분류함으로써, 사용 후 배터리를 신속하고 효율적이며 용이하게 재사용·재제조할 수 있게 한다.Korean Patent Registration No. 10-2289155 discloses a used battery classifying process and a system providing the same. This process and system is a technology for reuse/remanufacture of batteries used as electric vehicles or energy storage devices. By classifying remanufacturing grades, it is possible to quickly, efficiently and easily reuse and remanufacture batteries after use.

한편, 전기차(electric vehicle, EV) 사용 후의 배터리에 대해서는 용량(state of charge), 용량수명(state of health), 파워수명(state of available power capability), 셀 전압편차(state of balance) 등의 검사를 통해 상태 확인이 이루어지며, 이러한 상태 확인을 통해 배터리의 잔존가치가 평가된다. 그런데 배터리 잔존가치를 평가하기 위해서는 많은 시간이 소요되는 문제가 있다. 특히, 기존에 SOH를 검사하는 방법으로는 표 1에서와 같이 HPPC(Hybrid Pulse Power Characterization), 완전방전, 교류방전이 잘 알려져 있다.On the other hand, for batteries after using an electric vehicle (EV), tests such as state of charge, state of health, state of available power capability, and cell voltage deviation (state of balance) are conducted. Through this, the state is checked, and the residual value of the battery is evaluated through this state check. However, there is a problem in that it takes a lot of time to evaluate the residual value of the battery. In particular, HPPC (Hybrid Pulse Power Characterization), full discharge, and alternating discharge are well known as methods for inspecting SOH in the past, as shown in Table 1.

Figure pat00001
Figure pat00001

HPPC 방법과 교류 임피던스 방법은 측정 시간이 짧은 반면에 정확도가 떨어지기 때문에 정확도가 높은 완전방전 방법이나 부분방전 방법이 이용되고 있는데, 상대적으로 측정 시간이 짧으면서 정확도 측면에서 크게 문제가 없는 부분방전 방법이 선호된다. 하지만 부분방전 방법 역시 역시 24시간 정도의 긴 측정 시간이 요구되며, 이는 결국 전기차 사용 후의 배터리 산업 활성화에 장애 요소가 된다. 따라서, 배터리 잔존가치를 평가하기 위한 공정 시간을 단축할 필요가 있다.The HPPC method and the AC impedance method have a short measurement time but low accuracy, so a full discharge method or a partial discharge method with high accuracy is used. this is preferred However, the partial discharge method also requires a long measurement time of about 24 hours, which eventually becomes an obstacle to vitalizing the battery industry after using electric vehicles. Therefore, it is necessary to shorten the process time for evaluating the residual value of the battery.

국내등록특허공보 제10-2289155호 (2021년 8월 11일 공고)Korean Registered Patent Publication No. 10-2289155 (Announced on August 11, 2021)

본 발명은 EV 배터리 잔존가치를 평가하기 위한 공정 시간을 단축할 수 있는 기술적 방안을 제공함을 목적으로 한다.An object of the present invention is to provide a technical solution capable of reducing the process time for evaluating the residual value of an EV battery.

일 양상에 따른 전기차 배터리 잔존가치 평가 방법은 배터리의 용량수명(state of health, SOH)과 파워수명(state of available power capability, SOP) 및 셀 전압편차(state of balance, SOB)를 산출하여 전기차 배터리의 잔존가치를 평가함에 있어서, 공정 시간의 단축을 위해 완전방전이 아닌 소정의 배터리 용량(state of charge, SOC) 구간에서 이루어지는 부분방전 하에 SOH를 산출할 수 있다.An electric vehicle battery residual value evaluation method according to one aspect calculates the state of health (SOH), power life (state of available power capability, SOP), and cell voltage deviation (state of balance (SOB)) of the electric vehicle battery In evaluating the residual value of , SOH may be calculated under partial discharge in a predetermined battery capacity (state of charge, SOC) section rather than complete discharge to shorten the process time.

본 발명은 EV 배터리 잔존가치를 평가하기 위한 공정 시간을 대폭 단축시킬 수 있는 효과를 창출한다. 구체적으로, 본 발명은 SOH 측정 결과를 신뢰할 수 있으면서도 짧은 방전구간을 찾아내어 공정 시간의 단축을 가능하게 하며, 공정 과정을 줄이면서도 배터리 잔존가치에 대한 평가 결과를 신뢰할 수 있게 하여 공정 시간의 단축을 가능하게 한다.The present invention creates the effect of significantly reducing the process time for evaluating the EV battery residual value. Specifically, the present invention makes it possible to shorten the process time by finding a short discharge period while making the SOH measurement result reliable, and shortening the process time by making the evaluation result of the battery residual value reliable while reducing the process process. make it possible

도 1은 일 실시예에 따른 전기차 사용 후의 배터리 잔존가치 평가 프로세스를 나타낸다.
도 2는 일 실시예에 따른 방치 시간(Rest time) 개선을 위한 휴지 시간에 따른 열평형 분석 결과 그래프이다.
도 3은 일 실시예에 따른 SOH별 배터리 방전 전압 - Ah SOC 그래프이다.
도 4는 부분방전 구간별 시험 결과를 나타낸다.
도 5는 부분방전을 위한 전류 1/3C-rate와 1/2C-rate 시험 결과 그래프이다.
도 6은 도 5의 1/3C-rate 시험 결과를 일차함수로 보정한 결과 그래프이다.1 shows a battery residual value evaluation process after using an electric vehicle according to an embodiment.
2 is a graph of a thermal equilibrium analysis result according to rest time for rest time improvement according to an embodiment.
3 is a graph of battery discharge voltage per SOH - Ah SOC according to an embodiment.
4 shows test results for each partial discharge section.
5 is a graph of current 1/3C-rate and 1/2C-rate test results for partial discharge.
6 is a graph showing the result of correcting the 1/3C-rate test result of FIG. 5 with a linear function.

전술한, 그리고 추가적인 본 발명의 양상들은 첨부된 도면을 참조하여 설명되는 바람직한 실시예들을 통하여 더욱 명백해질 것이다. 이하에서는 본 발명을 이러한 실시예를 통해 통상의 기술자가 용이하게 이해하고 재현할 수 있도록 상세히 설명하기로 한다.The foregoing and further aspects of the present invention will become more apparent through preferred embodiments described with reference to the accompanying drawings. Hereinafter, the present invention will be described in detail so that those skilled in the art can easily understand and reproduce the present invention through these embodiments.

도 1은 일 실시예에 따른 전기차 사용 후의 배터리 잔존가치 평가 프로세스를 나타낸 도면이다. 배터리 잔존가치 평가 프로세스(공정)는 배터리 충방전 시험 장치에 의해 수행되는 것으로, 내부에 탑재된 프로세서에 의해 자동으로 수행될 수 있다. 그리고 배터리 잔존가치 평가 프로세스에 따른 각 단계별 측정 시간은 표 2와 같을 수 있다.1 is a diagram illustrating a battery residual value evaluation process after using an electric vehicle according to an embodiment. The battery residual value evaluation process (process) is performed by the battery charge/discharge test device, and may be automatically performed by a processor installed therein. In addition, the measurement time for each step according to the battery residual value evaluation process may be as shown in Table 2.

단계step 시험조건Exam conditions 시간(분)time (minutes) 1One 방치(Rest)Rest 1One 22 충/방전(Charge/Discharge)Charge/Discharge 6060 33 방치(Rest)Rest 4040 44 방전(Discharge)Discharge 1010 55 방치(Rest)Rest 4040 66 충전(Charge)Charge 1One 77 방치(Rest)Rest 1010 88 방전(Discharge)Discharge 1010 99 방치(Rest)Rest 4040 합계Sum 212212

제 1 단계(S100)는 배터리의 잔존가치를 평가하기 위한 예비 시험조건으로 기존에 이미 잘 알려진 초기 단계와 동일하다. 제 2 단계(S200)는 충전 또는 방전 시험 공정으로, SOB와 SOP 및 SOH를 측정하기 위해 SOC를 50% 상태로 만들기 위한 단계이다. 예를 들어, 배터리 입고시 SOC 100%일 경우에는 SOC 50%가 되도록 방전하고, 입고시 SOC 0%일 경우에는 SOC 50%가 되도록 충전한다. 표 2에서 소요되는 시간은 60분으로 되어 있으나, 배터리 입고상태에 따라 소요 시간은 달라진다. 즉, 제 2 단계 소요시간은 60분보다 줄어들 수 있다.The first step (S100) is a preliminary test condition for evaluating the residual value of the battery and is the same as the previously well-known initial step. The second step (S200) is a charge or discharge test process, which is a step for making SOC 50% in order to measure SOB, SOP, and SOH. For example, if the SOC is 100% when the battery is warehousing, it is discharged to 50% SOC, and when the SOC is 0% when warehousing, it is charged so that the SOC is 50%. In Table 2, the time required is 60 minutes, but the time required varies depending on the storage condition of the battery. That is, the time required for the second step may be less than 60 minutes.

제 3 단계(S300)는 제 2 단계의 충/방전 이후 배터리를 초기 안정화(열평형) 상태로 회복시키기 위한 과정이다. 일 실시예에 있어서, 제 3 단계의 소요 시간은 40분으로 설정된다. 이는 배터리 휴지 시간에 따른 열평형 분석을 통해 얻어진 결과값이다. 구체적으로, 휴지 반복성 시험을 통해 배터리 충/방전 이후 초기 안정화 상태로 회복되는 시간을 도 2와 같이 데이터로 확보하였으며, 분석 결과 10분 방치시에는 ±1.5% 오차범위에서 측정이 이루어졌고 26분에는 ±1% 오차범위에서 측정이 이루어져 40분의 방치 시간을 가지면 초기 안정화 상태로 회복이 가능한 것으로 확인되었다.The third step (S300) is a process for restoring the battery to an initial stabilization (thermal equilibrium) state after the charging/discharging of the second step. In one embodiment, the duration of the third step is set to 40 minutes. This is the result obtained through thermal equilibrium analysis according to the battery idle time. Specifically, through the rest repeatability test, the time to recover to the initial stable state after battery charge/discharge was obtained as data as shown in FIG. Measurements were made within the error range of ±1%, and it was confirmed that recovery to the initial stabilization state was possible with a standing time of 40 minutes.

제 4 단계(S400)에서는 배터리 SOC 50%에서 SOP 측정이 이루어진다. SOP는 DCIR(Direct Curent Internal Resistance) 측정법으로 측정이 이루어질 수 있다. 일 실시예에 있어서, SOP(DCIR)는 제 4 단계(S400)에서 다음의 과정을 통해 얻어진다.In the fourth step (S400), SOP measurement is performed at 50% of the battery SOC. SOP may be measured by DCIR (Direct Current Internal Resistance) measurement method. In one embodiment, SOP (DCIR) is obtained through the following process in the fourth step (S400).

① 제 4 단계 방전시 SOC 50%에서 1/3C-rate로 전압(V1) 측정함① Measure voltage (V 1 ) at 1/3C-rate at 50% of SOC during the 4th stage discharge

② 10초 동안 추가 방전 후 5/3C-rate로 전압(V2) 측정함② Measure voltage (V 2 ) at 5/3C-rate after additional discharge for 10 seconds

③ 수학식 1을 이용하여 SOP를 산출함③ Calculate SOP using Equation 1

Figure pat00002
Figure pat00002

제 5 단계(S500)는 제 4 단계의 방전 이후 배터리를 안정화(열평형) 상태로 회복시키기 위한 과정이다. 일 실시예에 있어서, 제 4 단계의 소요 시간은 10분으로 설정된다. 이 시간값 역시 배터리 휴지 시간에 따른 열평형 분석을 통해 얻어질 수 있다. 제 6 단계(S600)는 배터리 SOC 60%를 만들기 위한 충전 과정으로서, 충전 소요 시간은 10분으로 설정될 수 있다. 그리고 제 7 단계(S700)는 제 6 단계에 따른 배터리 충전 후에 안정화(열평형)를 위한 과정이다. 제 7 단계의 방치 시간은 40분으로 설정될 수 있으며, 이 시간값 역시 배터리 휴지 시간에 따른 열평형 분석을 통해 얻어질 수 있다.A fifth step (S500) is a process for restoring the battery to a stable (thermal equilibrium) state after discharging in the fourth step. In one embodiment, the duration of the fourth step is set to 10 minutes. This time value can also be obtained through thermal equilibrium analysis according to the battery idle time. The sixth step (S600) is a charging process for making the battery SOC 60%, and the charging time may be set to 10 minutes. And the seventh step (S700) is a process for stabilization (thermal equilibrium) after charging the battery according to the sixth step. The leaving time of the seventh step may be set to 40 minutes, and this time value may also be obtained through thermal equilibrium analysis according to the battery idle time.

제 8 단계(S800)에서는 SOH 평가를 위해 부분방전이 이루어진다. 일 실시예에 있어서, 부분방전 시험 조건은 다음과 같다.In the eighth step (S800), partial discharge is performed for SOH evaluation. In one embodiment, the partial discharge test conditions are as follows.

ⓐ 부분방전 구간 : SOC 60% → SOC 50% (10% 구간 부분방전 시험)ⓐ Partial discharge section: SOC 60% → SOC 50% (10% section partial discharge test)

ⓑ 부분방전 회귀식 산출(시험을 활용한 데이터 확보)ⓑ Calculation of partial discharge regression equation (acquisition of data using test)

⇒ 입력변수 X(부분방전 용량_Ah), 출력변수 Y(완전방전 용량_Ah) 데이터를 확보해 회귀식 산출(MINITAB) ⇒ Securing input variable X (capacity of partial discharge_Ah) and output variable Y (capacity of complete discharge_Ah) and calculating the regression formula (MINITAB)

⇒ 회귀식 : Y = 18.4 + 6.68X ⇒ Regression: Y = 18.4 + 6.68X

ⓒ 시험전류 : 1/2C-rate 측정ⓒ Test current: 1/2C-rate measurement

⇒ 1/2C-rate와 1/3C-rate 시험시 1.4% 차이 보정함 ⇒ Compensation of 1.4% difference in 1/2C-rate and 1/3C-rate tests

부분방전 구간을 ⓐ와 같이 결정한 이유에 대해 설명한다. 도 3은 시험을 통해 얻어진 SOH별 배터리 방전 전압 - Ah SOC 그래프 및 SOH 95%에서의 SOC 테이블을 나타낸 것이다. 도 3을 통해 SOC 50% 구간부터 전압편차가 발생하는 것이 확인되었다. 따라서, 부분방전 구간은 전압편차가 발생하지 않는 SOC 100%부터 SOC 50%까지의 구간 내에서 정해짐이 바람직하다. 이에 도 4에서와 같이 SOC 50%를 기준(방전 종료값)으로 두고 5% 구간(SOC 55%부터 SOC 50%까지), 10% 구간(SOC 60%부터 SOC 50%까지), 20% 구간(SOC 70%부터 SOC 50%까지), 30% 구간(SOC 80%부터 SOC 50%까지), 40% 구간(SOC 90%부터 SOC 50%까지), 50% 구간(SOC 100%부터 SOC 50%까지)에 대해 부분방전을 시험해 본 결과 표 3의 결과가 도출되었다.The reason why the partial discharge section was determined as ⓐ will be explained. 3 shows a battery discharge voltage-Ah SOC graph for each SOH obtained through the test and a SOC table at 95% SOH. It was confirmed through FIG. 3 that a voltage deviation occurs from the SOC 50% section. Therefore, the partial discharge section is preferably determined within a section from SOC 100% to SOC 50% in which voltage deviation does not occur. Accordingly, as shown in FIG. 4, with SOC 50% as a reference (discharge end value), 5% interval (SOC 55% to SOC 50%), 10% interval (SOC 60% to SOC 50%), 20% interval ( SOC 70% to SOC 50%), 30% interval (SOC 80% to SOC 50%), 40% interval (SOC 90% to SOC 50%), 50% interval (SOC 100% to SOC 50%) ), the results of Table 3 were obtained as a result of the partial discharge test.

5%5% 10%10% 20%20% 30%30% 40%40% 50%50% 측정시간measurement time 3:593:59 8:128:12 19:3419:34 30:2530:25 41:2241:22 47:3647:36 용량(Ah)Capacity (Ah) 2.592.59 5.385.38 12.8912.89 20.2120.21 27.1627.16 31.2431.24 용량계수capacity factor 27.6927.69 13.8313.83 5.565.56 3.553.55 2.642.64 2.302.30 오차율error rate 54.41%54.41% 0.03%0.03% 6.92%6.92% 0%0% 1.63%1.63% 0%0% * 오차율(정확성) : 완전방전대비 3% 차이를 벗어나는 시료가 발생하는 빈도율
* 용량계수는 완전방전용량(74.4Ah) 대비 비례상수(10%방전용량/71.71 = 13.33Ah)* Error rate (accuracy): Frequency rate at which samples out of 3% from complete discharge occur
* The capacity factor is the proportional constant (10% discharge capacity/71.71 = 13.33Ah) compared to the full discharge capacity (74.4Ah)

표 3을 통해 10% 구간이 측정시간이 짧으면서도 완전방전 대비 오차율이 매우 낮은 것으로 확인되었다. 즉, SOC 용량 10% 방전시 측정시간 및 정확성이 가장 효율적인 것으로 나타났으며, 이에 따라 SOH 평가를 위한 부분방전 구간은 SOC 10% 구간으로 결정되었다. 여기서, SOC 10% 구간은 SOC 60%부터 SOC 50%까지일 수도 있지만 아닐 수도 있다. 즉, SOC 100%부터 SOC 50%까지의 구간 내에서 다른 SOC 10% 구간일 수도 있다. 예를 들어, SOC 65%부터 SOC 55%까지일 수도 있는 것이다.Through Table 3, it was confirmed that the 10% section had a very low error rate compared to complete discharge even though the measurement time was short. That is, the measurement time and accuracy were found to be the most efficient when the SOC capacity was discharged by 10%, and accordingly, the partial discharge section for SOH evaluation was determined as the SOC 10% section. Here, the SOC 10% section may be from SOC 60% to SOC 50%, but may not be. That is, it may be another SOC 10% section within the section from SOC 100% to SOC 50%. For example, it may be from SOC 65% to SOC 55%.

한편, 시험전류를 1/2C-rate로 정한 이유는 공정 시간을 더욱 단축하기 위함이다. 이전에는 시험전류가 1/3C-rate이었으나 이를 1/2C-rate로 조정한 것이다. 도 5에 부분방전을 위한 전류 1/3C-rate와 1/2C-rate 비교 시험 그래프가 도시되어 있으며, 그 결과는 표 4와 같다.Meanwhile, the reason why the test current is set at 1/2C-rate is to further shorten the process time. Previously, the test current was 1/3C-rate, but it was adjusted to 1/2C-rate. 5 shows a current 1/3C-rate and 1/2C-rate comparison test graph for partial discharge, and the results are shown in Table 4.

구분division 1/2C1/2C 1/3C1/3C 용량Volume 74.732(Ah)74.732 (Ah) 74.994(Ah)74.994 (Ah) 소요시간time taken 8시간 52분8 hours 52 minutes 10시간 32분10 hours 32 minutes 용량 값 (38V)Capacity value (38V) 51.679(Ah)51.679 (Ah) 50.54(A)50.54(A) 편차Deviation 1.445%1.445%

1/2C와 1/3C 시험 결과 약 1.4%의 차이가 발생하지만, 1/3C를 일차함수로 보정한 결과 도 6과 같이 일치하는 것으로 확인되었다. 따라서, 시험전류를 1/2C로 하여 공정 시간을 단축할 수 있으면서도 일차함수 보정을 통해 1/3C 대비 오차율이 없거나 매우 낮은 결과를 얻을 수 있게 된다.As a result of the 1/2C and 1/3C tests, a difference of about 1.4% occurred, but as a result of correcting 1/3C with a linear function, it was confirmed as shown in FIG. 6. Therefore, while the process time can be shortened by setting the test current to 1/2C, it is possible to obtain a result with no or very low error rate compared to 1/3C through linear function correction.

한편, 제 8 단계에서의 방전시 전류-시간(Ah) 용량을 기준으로 SOC를 산출할 수 있으며, 수학식 2를 이용하여 SOH를 산출할 수 있다.Meanwhile, SOC can be calculated based on the current-time (Ah) capacity during discharging in the eighth step, and SOH can be calculated using Equation 2.

Figure pat00003
Figure pat00003

CAPACITY Origin은 제조사 제안(초기 용량)이며, CAPACITY Now의 값은 앞서의 회귀식을 통해 구해진 Y 값일 수 있다.CAPACITY Origin is the manufacturer's proposal (initial capacity), and the value of CAPACITY Now may be the Y value obtained through the previous regression equation.

그리고 제 8 단계에서의 방전시 SOC 50%에서 최대전압(MAX VOLTAGE), 최소전압(MIN VOLTAGE)를 도출하고, 수학식 3을 이용하여 SOH를 산출할 수 있다.In addition, when discharging in the eighth step, the maximum voltage (MAX VOLTAGE) and the minimum voltage (MIN VOLTAGE) can be derived at SOC 50%, and SOH can be calculated using Equation 3.

Figure pat00004
Figure pat00004

Figure pat00005
Figure pat00005

Pack내 Cell 중 최대/최소값을 선정하며, Module내 Cell중 최대/최소값 선정한다.Select the maximum/minimum value among the cells in the pack, and select the maximum/minimum value among the cells in the module.

마지막으로, 아래의 수학식 4를 이용하여 배터리 잔존가치를 나타내는 배터리 등급을 산출할 수 있다.Finally, a battery grade representing a residual value of a battery may be calculated using Equation 4 below.

Figure pat00006
Figure pat00006

여기서, W는 가중치를 나타내는 것으로, SOB : SOH : SOP = 4 : 4: 2의 가중치가 적용될 수 있다.Here, W represents a weight, and a weight of SOB:SOH:SOP = 4:4:2 may be applied.

이제까지 본 발명에 대하여 그 바람직한 실시예들을 중심으로 살펴보았다. 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자는 본 발명이 본 발명의 본질적인 특성에서 벗어나지 않는 범위에서 변형된 형태로 구현될 수 있음을 이해할 수 있을 것이다. 그러므로 개시된 실시예들은 한정적인 관점이 아니라 설명적인 관점에서 고려되어야 한다. 본 발명의 범위는 전술한 설명이 아니라 청구범위에 나타나 있으며, 그와 동등한 범위 내에 있는 모든 차이점은 본 발명에 포함된 것으로 해석되어야 할 것이다.So far, the present invention has been looked at with respect to its preferred embodiments. Those skilled in the art to which the present invention pertains will be able to understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent range should be construed as being included in the present invention.

Claims (5)

배터리의 용량수명(state of health, SOH)과 파워수명(state of available power capability, SOP) 및 셀 전압편차(state of balance, SOB)를 산출하여 전기차 배터리의 잔존가치를 평가하는 방법에 있어서,
공정 시간의 단축을 위해 완전방전이 아닌 소정의 배터리 용량(state of charge, SOC) 구간에서 이루어지는 부분방전 하에 SOH를 산출하는 전기차 배터리 잔존가치 평가 방법.In a method for evaluating the residual value of an electric vehicle battery by calculating the battery's state of health (SOH), power life (state of available power capability, SOP), and cell voltage deviation (state of balance, SOB),
An EV battery residual value evaluation method that calculates SOH under partial discharge in a predetermined battery capacity (state of charge, SOC) section instead of complete discharge to shorten the process time. 제 1 항에 있어서,
SOH 측정을 위한 부분방전 구간은 SOC 60%부터 SOC 50%까지의 10% 구간인 전기차 배터리 잔존가치 평가 방법.According to claim 1,
The partial discharge section for SOH measurement is the 10% section from SOC 60% to SOC 50%. Method for evaluating residual value of electric vehicle battery. 제 1 항 또는 제 2 항에 있어서,
공정 시간의 단축을 위해 배터리 평가 공정은 1단계 방치 → 2 단계 충전 또는 방전 → 3단계 방치 → 4단계 방전 → 5단계 방치 → 6단계 충전 → 7단계 방치 → 8단계 방전 → 9단계 방치로 이루어지며, SOH 측정을 위한 부분방전은 8단계 방전인 전기차 배터리 잔존가치 평가 방법.According to claim 1 or 2,
To shorten the process time, the battery evaluation process consists of 1st step leaving → 2nd step charging or discharging → 3rd step leaving → 4th step discharging → 5th step leaving → 6th step charging → 7th step leaving → 8th step discharging → 9th step leaving , Partial discharge for SOH measurement is an 8-stage discharge method for evaluating the residual value of an electric vehicle battery. 제 3 항에 있어서,
4단계 방전시 SOC 50%에서 1/3C-rate로 전압 V1을 측정하고, 추가 방전 후에 5/3C-rate로 전압 V2를 측정하며, 하기 수학식을 통해 SOP를 산출하는 전기차 배터리 잔존가치 평가 방법.
Figure pat00007
According to claim 3,
Voltage V 1 is measured at 1/3C-rate at SOC 50% during step 4 discharge, voltage V 2 is measured at 5/3C-rate after additional discharge, and SOP is calculated through the following equation Residual value of EV battery Assessment Methods.
Figure pat00007
 제 3 항에 있어서,
2단계의 충전 또는 방전 이후에 배터리의 열평형 상태로의 회복을 위한 3단계 방치 시간은 40분으로 설정되는 전기차 배터리 잔존가치 평가 방법.According to claim 3,
A method for evaluating the remaining value of an electric vehicle battery in which the third step of leaving the battery for recovery to thermal equilibrium after the second step of charging or discharging is set to 40 minutes.
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