CN107422265A - A kind of detection method of cell uniformity - Google Patents

Abstract

The invention discloses a detection method for the consistency of single cells, which comprises the steps of: performing standard charge and discharge on a plurality of qualified single cells, detecting the actual capacities of the plurality of single cells, and classifying the plurality of cells according to the capacity difference standard. Carry out the DC impedance test of normal temperature, high temperature and low temperature respectively, and classify the single battery; carry out the current conversion test of normal temperature, high temperature and low temperature respectively, and the current pulse test for multiple single batteries in the same class. file; select single cells in the same file to form a battery pack. This method can more directly identify the consistency of the battery, thereby reducing the harm caused by the inconsistency of the battery to the battery module, improving the life and operating conditions of the battery pack, and solving the problem that the current single battery consistency detection system is not comprehensive and accurate. It is widely used in the field of energy storage.

Description

A detection method for the consistency of a single battery

technical field

The invention relates to the field of electric vehicles and new energy power generation and energy storage, in particular to a detection method for the consistency of a single battery.

Background technique

The current economic development leads to energy shortage, lack of fossil energy and pollution to the environment. The utilization of solar energy and wind energy has become a trend, but solar energy and wind energy require energy storage. Batteries are a good option for energy storage, but due to their low energy density, pollution, and expensive recycling costs, battery energy storage has not been well applied.

Since single cells cannot meet the requirements of power, energy, and capacity, it is necessary to increase the voltage of single cells through series connection, and increase the capacity through parallel connection, so as to increase the overall energy. However, the initial performance of each single cell in the battery pack is inconsistent, and the difference between the single cells increases during continuous charge and discharge cycles, which greatly reduces the performance of the battery pack. Therefore, it is extremely important to test the consistency of the single battery before assembling the module. However, the consistency test of the existing single battery is relatively simple, the DC internal resistance test is not comprehensive enough, and the test of the voltage change during the charging and discharging process is not comprehensive and detailed enough. Therefore it is necessary to improve.

Contents of the invention

In order to solve the above technical problems, the purpose of the present invention is to provide a more comprehensive detection method for testing the consistency of a single battery.

The technical scheme adopted in the present invention is:

The invention provides a method for detecting the consistency of a single battery, comprising the steps of:

Carry out standard charging and discharging of multiple qualified single batteries, detect the actual capacity of multiple single batteries, and classify multiple batteries according to the standard of capacity difference;

Carry out the DC impedance test of normal temperature, high temperature and low temperature on multiple single batteries of the same grade, and classify the single batteries according to the difference standard of the DC internal resistance of the tested batteries;

Carry out the current conversion test of normal temperature, high temperature and low temperature on multiple single batteries of the same level, and classify the single batteries according to the voltage deviation standard of the tested batteries;

Carry out the current pulse test of normal temperature, high temperature and low temperature on multiple single batteries of the same level, and classify the single batteries according to the voltage deviation standard of the tested batteries;

Select single cells located in the same gear to form a battery pack.

As an improvement of the technical solution, before testing a plurality of qualified single batteries, the multiple single batteries are sequentially subjected to formation treatment for a period of time and the qualified single batteries are selected.

As an improvement of the technical solution, the step is to perform a DC internal resistance test on a plurality of single cells in the same file, which also includes:

Perform DCIR tests on multiple single batteries in the initial state to obtain the DC discharge internal resistance and DC charging internal resistance in the initial state;

Discharge multiple single cells to the standard discharge cut-off voltage of the single cell, and perform DCIR test in the empty state, and obtain the DC discharge internal resistance and DC charging internal resistance in the empty state;

Charge multiple single batteries, charge with constant current to a fixed SOC state s1, and perform a fixed number of DCIR tests in the fixed SOC state s1 to obtain the DC discharge internal resistance and DC charging internal resistance in the fixed SOC state s1;

Charge multiple single batteries, charge with constant current to a fixed SOC state s2, and perform a fixed number of DCIR tests in the fixed SOC state s2, and obtain the DC discharge internal resistance value and the DC charging internal resistance value in the fixed SOC state s2;

Charge multiple single batteries, charge with constant current to a fixed SOC state s3, and perform a fixed number of DCIR tests in the fixed SOC state s3, and obtain the DC discharge internal resistance and DC charging internal resistance value in the fixed SOC state s3;

Statistics of the deviation values of DC discharge internal resistance and DC charging internal resistance of multiple single batteries under different SOC states;

Wherein, the states s1, s2, and s3 are all between 0% SOC and 100% SOC.

As an improvement of this technical solution, the step is to conduct a current conversion test on multiple single cells of the same level, which includes performing xC constant current charging and xC constant current discharge on multiple single cells, and then charging with 2xC constant current , 2xC constant current discharge, where x represents the charge and discharge rate, and xC represents the charge and discharge current.

Further, the step is to conduct a current pulse test on a plurality of single cells of the same level, which includes charging the multiple single cells with xC constant current and standing for a period of time; Discharge and stand for a while, and cycle many times.

Further, the temperature in the low temperature zone is -30°C to 0°C.

Further, the temperature in the high temperature zone is 40°C to 60°C.

Further, the amplitude value of the DC charging and discharging internal resistance deviation is 10%.

Further, the voltage deviation amplitude values in the current conversion consistency and current pulse consistency tests are both 1%.

Further, the single battery is a lithium ion single battery.

The beneficial effects of the present invention are: the detection method for the consistency of the single battery provided by the present invention, by setting different SOC states to conduct DCIR tests, counting the DC internal resistance in different SOC states, performing analysis and calculation, and comparing to obtain the internal resistance of the single battery The consistency analysis results of the resistance, and the voltage change of the single battery is monitored through the current conversion and the current pulse, and the consistency of the single battery is evaluated through the change of the voltage. At the same time, the present invention comprehensively considers the working characteristics of lithium-ion batteries in the high-temperature zone and low-temperature zone, and can understand the consistency of the battery more systematically by analyzing the charging and discharging process of the single battery in different states, thereby reducing the impact of the inconsistency of the battery on the battery. damage to the battery pack and increase the life of the battery pack. This method can more directly identify the consistency of the battery, thereby reducing the harm caused by the inconsistency of the battery to the battery module, improving the life and operating conditions of the battery pack, and solving the problem that the current single battery consistency detection system is not comprehensive and accurate. question.

Description of drawings

The specific embodiment of the present invention will be further described below in conjunction with accompanying drawing:

Figure 1 is a graph of the current-voltage deviation amplitude curve obtained from the consistency test of the current conversion of the single battery;

Fig. 2 is a graph of the current-voltage deviation amplitude curve obtained from the current pulse consistency test of the single battery.

detailed description

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

A method for detecting the consistency of a single battery, comprising:

Carry out standard charging and discharging of multiple qualified single batteries, detect the actual capacity of multiple single batteries, and classify multiple batteries according to the standard of capacity difference;

Carry out the DC impedance test of normal temperature, high temperature and low temperature on multiple single batteries of the same grade, and classify the single batteries according to the difference standard of the DC impedance of the tested batteries;

Carry out the current conversion test of normal temperature, high temperature and low temperature on multiple single batteries of the same level, and classify the single batteries according to the voltage deviation standard of the tested batteries;

Carry out the current pulse test of normal temperature, high temperature and low temperature on multiple single batteries of the same level, and classify the single batteries according to the voltage deviation standard of the tested batteries;

Select single cells located in the same gear to form a battery pack.

Wherein, the capacity difference value is that the discharge capacity should not be lower than the rated capacity and not exceed 10% of the rated capacity, and the initial capacity difference of a single cell is not greater than 5% of the average initial capacity.

As an improvement of the technical solution, the step of performing a DC internal resistance test on multiple single cells of the same level includes:

a) Carry out DCIR test in the initial state on a plurality of monomer batteries, and obtain the DC discharge internal resistance and the DC charging internal resistance in the initial state;

b) After the test in a) is completed, discharge a plurality of single cells to the standard discharge cut-off voltage of the single cells, and perform a DCIR test in the empty state, and obtain the DC discharge internal resistance and the DC charging internal resistance in the empty state;

c) After the b) test, charge multiple single cells, charge them with a constant current to a fixed SOC state s1, and perform a fixed number of DCIR tests in the fixed SOC state s1 state to obtain the DC discharge internal resistance value in the fixed SOC state s1 and DC charging internal resistance;

d) After the test in c), charge multiple single cells, charge them with constant current to the fixed SOC state s2, and perform a fixed number of DCIR tests in the fixed SOC state s2 state, and obtain the DC discharge internal resistance value under the fixed SOC state s2 and DC charging internal resistance;

e) After the test in b) is completed, charge multiple single batteries, charge them to a fixed SOC state s3 at a constant current, and perform a fixed number of DCIR tests in a fixed SOC state s3 to obtain the DC discharge internal resistance and DC charging internal resistance value; finally count the deviation values of DC discharging internal resistance and DC charging internal resistance of multiple single batteries under different SOC states; the DCIR current values are 0.5C current and 1C current respectively, and the time is 5s respectively and 10s. Wherein, the states s1, s2, and s3 are all between 0% SOC and 100% SOC.

As an improvement of this technical solution, the test process of performing the current conversion test on multiple single cells of the same level is to charge multiple single cells with xC constant current for a period of time, discharge with xC constant current for a period of time, and then use 2xC constant current charge for a period of time, 2xC constant current discharge for a period of time, where x represents the charge and discharge rate, and the xC represents the charge and discharge current.

Further, the test process of performing a current pulse test on multiple single cells of the same level is to charge multiple single cells with xC constant current for a period of time, leave them for a period of time, and continue to charge them with xC constant current for a period of time , after many cycles, discharge at xC constant current for a period of time, let it stand for a period of time, continue to discharge at xC constant current for a period of time, and cycle many times.

Further, the amplitude value of the DC charging and discharging internal resistance deviation is 10%.

Further, the voltage deviation amplitude value in the current transformation consistency and current pulse consistency test is 1%.

Wherein, the temperature in the low temperature region is -30°C to 0°C.

Wherein, the temperature in the high temperature region is 40°C to 60°C.

The method further includes: prior to testing the multiple qualified single batteries, selecting qualified single batteries after undergoing formation treatment for a period of time on the multiple single batteries.

The single battery is a lithium ion single battery.

Referring to Figure 1-2, it shows the voltage changes of the four cells during charging and discharging at different currents and the voltage deviation of different cells.

Example one

Multiple 60Ah single batteries are formed first, stored for 7 days, and then divided into capacity. Select 4 batteries with a capacity of 60Ah to 65Ah, and connect them to the battery test equipment with a current and voltage accuracy of four digits after the decimal point. The single battery is tested at room temperature, and the test steps are as follows:

1. For the DCIR test in the initial state, the DCIR test current is 30A and 60A, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

2. Constant current discharge to discharge cut-off voltage, under this state, perform DCIR test, DCIR test current is 30A and 60A, test time is 5s and 10s, cycle DCIR test 10 times;

3. Charge with a constant current until the capacity cut-off is 18Ah. In this state, perform a DCIR test. The DCIR test current is 30A and 60A, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

4. Constant current charging until the capacity cut-off is 18Ah, in this state, DCIR test is carried out, the DCIR test current is 30A and 60A, the test time is 5s and 10s, respectively, and the DCIR test is cycled 10 times;

5. Constant current charging to the charging cut-off voltage, in this state, DCIR test is carried out, the DCIR test current is 30A and 60A, the test time is 5s and 10s, respectively, and the DCIR test is cycled 10 times;

6. After pretreatment, let it stand for 10 minutes, and conduct a current conversion test. First, charge at a constant current of 30A for 5 minutes, then discharge at a constant current of 30A for 5 minutes, then charge at a constant current of 60A for 5 minutes, and finally discharge at a constant current of 60A for 5 minutes. The current conversion test cycle is 3 Second-rate;

7. Constant current discharge to the discharge cut-off voltage, stand still for 10min, conduct current pulse test, first charge with 60A constant current for 5min, rest for 5min, repeat charging 11 times, then discharge with 60A constant current for 5min, finally stand for 5min, discharge Repeat 11 times;

8. Statistical current and voltage DC internal resistance data, respectively calculate the DC charging internal resistance deviation amplitude, DC discharge internal resistance deviation amplitude, current conversion voltage change deviation amplitude, current pulse voltage change deviation amplitude.

Example two

For a number of qualified 60Ah single batteries, first form them, store them for 7 days, and then divide them into capacity. Select 4 batteries with a capacity of 60Ah to 65Ah, and connect them to the battery testing equipment with a current and voltage accuracy of four digits after the decimal point. For 4 A single battery is tested at room temperature, and the test steps are as follows:

1. For the DCIR test in the initial state, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

2. Constant current discharge to discharge cut-off voltage, under this state, DCIR test is carried out, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

3. Charge with a constant current until the capacity cut-off is 24Ah. In this state, perform a DCIR test. The DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

4. Charge with a constant current until the capacity cut-off is 24Ah. In this state, perform a DCIR test. The DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

5. Constant current charging to the charging cut-off voltage, in this state, DCIR test is carried out, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

6. After pretreatment, let it stand for 10 minutes, and conduct a current conversion test. First, charge at a constant current of 30A for 5 minutes, then discharge at a constant current of 30A for 5 minutes, then charge at a constant current of 60A for 5 minutes, and finally discharge at a constant current of 60A for 5 minutes. The current conversion test cycle is 3 Second-rate;

7. Constant current discharge to the discharge cut-off voltage, stand still for 10 minutes, conduct current pulse test, first charge with 60A constant current for 5 minutes, stand for 5 minutes, repeat charging 11 times, then discharge with 60A constant current for 5 minutes, finally stand for 5 minutes, discharge Repeat 11 times;

8. Statistical current and voltage DC internal resistance data, respectively calculate the DC charging internal resistance deviation amplitude, DC discharge internal resistance deviation amplitude, current conversion voltage change deviation amplitude, current pulse voltage change deviation amplitude.

Example three

For a number of qualified 60Ah single batteries, first form them, store them for 7 days, and then divide them into capacity. Select 4 batteries with a capacity of 60Ah to 65Ah, and connect them to the battery testing equipment with a current and voltage accuracy of four digits after the decimal point. For 4 A single battery is tested at room temperature, and the test steps are as follows:

1. For the DCIR test in the initial state, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

2. Constant current charging to the charging cut-off voltage, in this state, DCIR test is carried out, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

3. Constant current discharge until the capacity cut-off is 18Ah. Under this state, DCIR test is carried out. The DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

4. Constant current discharge until the capacity cut-off is 18Ah. Under this state, DCIR test is carried out. The DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

5. Constant current discharge to discharge cut-off voltage, under this state, DCIR test is performed, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

6. After pretreatment, let it stand for 10 minutes, and conduct a current conversion test. First, charge at a constant current of 30A for 5 minutes, then discharge at a constant current of 30A for 5 minutes, then charge at a constant current of 60A for 5 minutes, and finally discharge at a constant current of 60A for 5 minutes. The current conversion test cycle is 3 Second-rate;

7. Constant current discharge to the discharge cut-off voltage, stand still for 10min, conduct current pulse test, first charge with 60A constant current for 5min, rest for 5min, repeat charging 11 times, then discharge with 60A constant current for 5min, finally stand for 5min, discharge Repeat 11 times;

8. Statistical current and voltage DC internal resistance data, respectively calculate the DC charging internal resistance deviation amplitude, DC discharge internal resistance deviation amplitude, current conversion voltage change deviation amplitude, current pulse voltage change deviation amplitude.

Example four

For a number of qualified 60Ah single batteries, first form them, store them for 7 days, and then divide them into capacity. Select 4 batteries with a capacity of 60Ah to 65Ah, and connect them to the battery testing equipment with a current and voltage accuracy of four digits after the decimal point. For 4 A single battery is tested at a high temperature and a constant temperature of 55°C. The test steps are as follows:

1. For the DCIR test in the initial state, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

2. Constant current discharge to discharge cut-off voltage, under this state, DCIR test is carried out, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

3. Constant current charging until the capacity cut-off is 18Ah, and DCIR test is carried out in this state, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

4. Charge with a constant current until the capacity cut-off is 18Ah. In this state, perform a DCIR test. The DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

5. Constant current charging to the charging cut-off voltage, in this state, DCIR test is carried out, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

6. After pretreatment, let it stand for 10 minutes, and conduct a current conversion test. First, charge at a constant current of 30A for 5 minutes, then discharge at a constant current of 30A for 5 minutes, then charge at a constant current of 60A for 5 minutes, and finally discharge at a constant current of 60A for 5 minutes. The current conversion test cycle is 3 Second-rate;

7. Constant current discharge to the discharge cut-off voltage, stand still for 10min, conduct current pulse test, first charge with 60A constant current for 5min, rest for 5min, repeat charging 11 times, then discharge with 60A constant current for 5min, finally stand for 5min, discharge Repeat 11 times;

8. Statistical current and voltage DC internal resistance data, respectively calculate the DC charging internal resistance deviation amplitude, DC discharge internal resistance deviation amplitude, current conversion voltage change deviation amplitude, current pulse voltage change deviation amplitude.

Example five

For a number of qualified 60Ah single batteries, first form them, store them for 7 days, and then divide them into capacity. Select 4 batteries with a capacity of 60Ah to 65Ah, and connect them to the battery testing equipment with a current and voltage accuracy of four digits after the decimal point. For 4 A single battery is tested at a low temperature and constant temperature at -20°C. The test steps are as follows:

1. For the DCIR test in the initial state, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

2. Constant current discharge to discharge cut-off voltage, under this state, DCIR test is carried out, the DCIR test current is 30A and 60Ah, the test time is 4s and 8s respectively, and the DCIR test is cycled 10 times;

3. Constant current charging until the capacity cut-off is 18Ah, and DCIR test is carried out in this state, the DCIR test current is 30A and 60Ah, the test time is 4s and 8s respectively, and the DCIR test is cycled 10 times;

4. Charge with a constant current until the capacity cut-off is 18Ah. In this state, perform a DCIR test. The DCIR test current is 30A and 60Ah, the test time is 4s and 8s, and the DCIR test is cycled 10 times;

5. Constant current charging to the charging cut-off voltage, in this state, DCIR test is carried out, the DCIR test current is 30A and 60Ah, the test time is 4s and 8s, respectively, and the DCIR test is cycled 10 times;

6. After pretreatment, let it stand for 10 minutes, and conduct a current conversion test. First, charge at a constant current of 30A for 5 minutes, then discharge at a constant current of 30A for 5 minutes, then charge at a constant current of 60A for 5 minutes, and finally discharge at a constant current of 60A for 5 minutes. The current conversion test cycle is 3 Second-rate;

7. Constant current discharge to the discharge cut-off voltage, stand still for 10min, conduct current pulse test, first charge with 60A constant current for 5min, rest for 5min, repeat charging 11 times, then discharge with 60A constant current for 5min, finally stand for 5min, discharge Repeat 11 times;

8. Statistical current and voltage DC internal resistance data, respectively calculate the DC charging internal resistance deviation amplitude, DC discharge internal resistance deviation amplitude, current conversion voltage change deviation amplitude, current pulse voltage change deviation amplitude.

Example six

Multiple qualified 20Ah single batteries are formed first, stored for 7 days, and then divided into capacity. Select 4 batteries with a capacity of 20Ah to 22Ah, and connect them to the battery testing equipment with a current and voltage accuracy of four decimal places. For 4 A single battery is tested at room temperature, and the test steps are as follows:

1. DCIR test in the initial state, the DCIR test current is 10A and 20Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

2. Constant current discharge to discharge cut-off voltage, under this state, DCIR test is performed, the DCIR test current is 10A and 20Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

3. Charge with a constant current until the capacity cut-off is 18Ah. In this state, perform a DCIR test. The DCIR test current is 10A and 20Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

4. Charge with a constant current until the capacity cut-off is 18Ah. In this state, perform a DCIR test. The DCIR test current is 10A and 20Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

5. Constant current charging to the charging cut-off voltage, in this state, DCIR test is carried out, the DCIR test current is 10A and 20Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 10 times;

6. After pretreatment, let it stand for 10 minutes, and conduct a current conversion test. First, charge at a constant current of 10A for 5 minutes, then discharge at a constant current of 10A for 5 minutes, then charge at a constant current of 20A for 5 minutes, and finally discharge at a constant current of 20A for 5 minutes. The current conversion test cycle is 3 Second-rate;

7. Constant current discharge to the discharge cut-off voltage, stand still for 10min, conduct current pulse test, first charge with 20A constant current for 5min, rest for 5min, repeat charging 11 times, then discharge with 20A constant current for 5min, stand for 5min, discharge repeatedly 11 times;

8. Statistical current and voltage DC internal resistance data, respectively calculate the DC charging internal resistance deviation amplitude, DC discharge internal resistance deviation amplitude, current conversion voltage change deviation amplitude, current pulse voltage change deviation amplitude.

Example seven

For a number of qualified 60Ah single batteries, first form them, store them for 7 days, and then divide them into capacity. Select 4 batteries with a capacity of 60Ah to 65Ah, and connect them to the battery testing equipment with a current and voltage accuracy of four digits after the decimal point. For 4 A single battery is tested at room temperature, and the test steps are as follows:

1. For the DCIR test in the initial state, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 10 times;

2. Constant current discharge to discharge cut-off voltage, under this state, DCIR test is carried out, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 7 times;

3. Charge with a constant current until the capacity cut-off is 18Ah. In this state, perform a DCIR test. The DCIR test current is 30A and 60Ah, the test time is 5s and 10s, and the DCIR test is cycled 7 times;

4. Constant current charging until the capacity cut-off is 18Ah, and DCIR test is carried out in this state, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 7 times;

5. Constant current charging to the charging cut-off voltage, DCIR test is carried out in this state, the DCIR test current is 30A and 60Ah, the test time is 5s and 10s respectively, and the DCIR test is cycled 7 times;

6. After pretreatment, let it stand for 10 minutes, and conduct a current conversion test. First, charge at a constant current of 30A for 5 minutes, then discharge at a constant current of 30A for 5 minutes, then charge at a constant current of 60A for 5 minutes, and finally discharge at a constant current of 60A for 5 minutes. The current conversion test cycle is 3 Second-rate;

7. Constant current discharge to the discharge cut-off voltage, stand still for 10 minutes, conduct current pulse test, first charge with 30A constant current for 10 minutes, stand for 10 minutes, repeat charging 4 times, then discharge with 30A constant current for 10 minutes, finally stand for 10 minutes, discharge Repeat 4 times;

8. Statistical current and voltage DC internal resistance data, respectively calculate the DC charging internal resistance deviation amplitude, DC discharge internal resistance deviation amplitude, current conversion voltage change deviation amplitude, current pulse voltage change deviation amplitude.

In the present invention, the output ends of the voltage sensor and the current sensor of the battery testing equipment for charging performance and discharging performance are respectively connected to the input ends of the corresponding monomers, so as to charge and discharge a plurality of qualified single batteries. Perform DCIR test by setting different SOC states, count the DC internal resistance under different SOC states, analyze and calculate, compare and obtain the consistency analysis results of the internal resistance of the single battery, and monitor the voltage of the single battery through current conversion and current pulse Changes, the consistency of the single battery is evaluated by the change of the voltage, and the larger the deviation amplitude is, the worse the consistency is. At the same time, the present invention comprehensively considers the working characteristics of lithium-ion batteries in the high-temperature zone and low-temperature zone, and can understand the consistency of the battery more systematically by analyzing the charging and discharging process of the single battery in different states, thereby reducing the impact of the inconsistency of the battery on the battery. damage to the battery pack and increase the life of the battery pack. This method can more directly identify the consistency of the battery, thereby reducing the harm caused by the inconsistency of the battery to the battery module, improving the life and operating conditions of the battery pack, and solving the problem that the current single battery consistency detection system is not comprehensive and accurate. question.

The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the described embodiments, those skilled in the art can also make various equivalent deformations or replacements without violating the spirit of the present invention , these equivalent modifications or replacements are all within the scope defined by the claims of the present application.

Claims (10)

1. A detection method for the consistency of a single battery, comprising the steps of: Carry out standard charging and discharging of multiple qualified single batteries, detect the actual capacity of multiple single batteries, and classify multiple batteries according to the standard of capacity difference; Carry out the DC impedance test of normal temperature, high temperature and low temperature on multiple single batteries of the same grade, and classify the single batteries according to the difference standard of the DC internal resistance of the tested batteries; Carry out the current conversion test of normal temperature, high temperature and low temperature on multiple single batteries of the same level, and classify the single batteries according to the voltage deviation standard of the tested batteries; Carry out the current pulse test of normal temperature, high temperature and low temperature on multiple single batteries of the same level, and classify the single batteries according to the voltage deviation standard of the tested batteries; Select single cells located in the same gear to form a battery pack. 2. The detection method for the consistency of a single battery according to claim 1, characterized in that: before testing a plurality of qualified single batteries, a plurality of single batteries are sequentially subjected to chemical formation treatment for a period of time and selected Out of the above-mentioned qualified single battery. 3. The method for detecting the consistency of a single battery according to claim 1 or 2, wherein the step is to perform a DC internal resistance test on a plurality of single batteries of the same level, which also includes: Perform DCIR tests on multiple single batteries in the initial state to obtain the DC discharge internal resistance and DC charging internal resistance in the initial state; Discharge multiple single cells to the standard discharge cut-off voltage of the single cell, and perform DCIR test in the empty state, and obtain the DC discharge internal resistance and DC charging internal resistance in the empty state; Charge multiple single batteries, charge with constant current to a fixed SOC state s1, and perform a fixed number of DCIR tests in the fixed SOC state s1 to obtain the DC discharge internal resistance and DC charging internal resistance in the fixed SOC state s1; Charge multiple single batteries, charge with constant current to a fixed SOC state s2, and perform a fixed number of DCIR tests in the fixed SOC state s2, and obtain the DC discharge internal resistance value and the DC charging internal resistance value in the fixed SOC state s2; Charge multiple single batteries, charge with constant current to a fixed SOC state s3, and perform a fixed number of DCIR tests in the fixed SOC state s3, and obtain the DC discharge internal resistance and DC charging internal resistance value in the fixed SOC state s3; Statistics of the deviation values of DC discharge internal resistance and DC charging internal resistance of multiple single batteries under different SOC states; Wherein, the states s1, s2, and s3 are all between 0% SOC and 100% SOC. 4. The detection method for the consistency of a single battery according to claim 1 or 2, characterized in that: the step is to perform a current conversion test on a plurality of single batteries in the same file, which includes separately testing the multiple single batteries Carry out xC constant current charging, xC constant current discharge, and then 2xC constant current charging, 2xC constant current discharge, where x represents the charge and discharge rate, and xC represents the charge and discharge current. 5. The detection method for the consistency of a single battery according to claim 1 or 2, characterized in that: the step is to perform a current pulse test on a plurality of single batteries of the same file, which includes separately testing the multiple single batteries Carry out xC constant current charge and stand for a while; after many cycles, discharge with xC constant current and stand for a while, and cycle for many times. 6 . The method for detecting the consistency of a single battery according to claim 1 , wherein the temperature in the low temperature region is -30° C. to 0° C. 7. The method for detecting the consistency of a single battery according to claim 1, characterized in that: the temperature in the high temperature region is 40°C-60°C. 8 . The method for detecting the consistency of a single battery according to claim 1 , wherein the amplitude value of the DC charging and discharging internal resistance deviation is 10%. 9 . The detection method for the consistency of a single battery according to claim 1 , wherein the deviation amplitude value of the voltage in the current conversion consistency test and the current pulse consistency test is both 1%. 10 . The method for detecting the consistency of a single battery according to claim 1 , wherein the single battery is a lithium ion single battery. 11 .