A method for determining low-temperature discharge capability of a new energy vehicle

Abstract

The application discloses a method for determining the low-temperature discharge capacity of a new energy vehicle, comprising the following steps: step 1, vehicle invasion process: allowing the vehicle to sufficiently reduce the temperature at a set temperature; step 2, cold start process: starting the vehicle; step 3, discharge process: recording parameter information while performing vehicle acceleration operation; and step 4, obtaining the low-temperature discharge capacity result of the new energy vehicle. The application can reliably determine the low-temperature discharge capacity of the new energy vehicle, improves the reliability of the vehicle in cold regions, is convenient for vehicle enterprises to verify the related performance of the vehicle, and can edit more accurate vehicle use instructions.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicles. Background Technology

[0002] The power battery of a new energy vehicle determines the overall performance of the vehicle, especially its range, reliability, and charging speed. In terms of reliability, it is currently necessary to ensure that the power battery (lithium battery) of a new energy vehicle can reliably discharge in low-temperature environments. This not only enables the vehicle to start, but also uses the discharge to heat the battery and improve its performance. If it cannot generate electricity, the vehicle will be at risk of breaking down. Therefore, the low-temperature discharge capability of new energy vehicles needs to be determined before they leave the factory.

[0003] For example, the patent publication CN112834937A, published on May 25, 2021, entitled "A Method for Detecting Battery Life Through Low-Temperature Discharge," discloses a method for detecting battery life through low-temperature discharge, which follows these steps: The battery to be tested is placed in a low-temperature environment of -18℃ to -22℃ and discharged at 0.2C10A for 2 hours, followed by current-limited charging at 0.1C10A with a constant voltage of 2.3-2.4V / cell for 10 hours, constituting one cycle; this cycle is repeated 30 times. The battery to be tested is then placed in an environment of -8℃ to -12℃ and discharged at 0.2C10A for 2 hours. One cycle consists of discharging at C10A for 2 hours and charging at a constant voltage of 2.3-2.4V / cell with a current-limited setting of 0.1C10A for 10 hours, repeated 20 times. The battery under test is then discharged at 0.1C10A to 1.8V / cell and charged at a constant voltage of 2.35V / cell with a current-limited setting of 0.1C10A for 24 hours. The battery capacity is then tested. If it is less than 80% of the rated capacity, the battery's lifespan is terminated. If the tested battery's rated capacity is greater than 80%, steps a, b, c, and d are repeated six times. Batteries that pass six cycles are considered qualified. This method can only verify the reliable performance and stable operation of lead-acid batteries in cold regions, but it cannot determine the reliability of lithium batteries' low-temperature discharge capability.

[0004] Currently, there is a lack of a convenient method to determine whether the low-temperature discharge capability of new energy vehicles is reliable. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for determining whether the low-temperature discharge capability of new energy vehicles is reliable.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for determining the low-temperature discharge capability of new energy vehicles, comprising the following steps:

[0007] Step 1, Vehicle intrusion process: Allow the vehicle to cool down sufficiently at the set temperature;

[0008] Step 2, Cold Start Process: Start the vehicle;

[0009] Step 3, Discharge process: While accelerating the vehicle, record the parameter information;

[0010] Step 4: Obtain the results of the low-temperature discharge capability of new energy vehicles.

[0011] In step 1, the vehicle windows and doors are opened, and the vehicle is parked at an ambient temperature equal to the set ambient temperature for 8-12 hours or more.

[0012] In step 1, before the vehicle intrusion process ends, the lowest temperature of the power battery cell is obtained. The lowest temperature of the power battery cell must be lower than the set cell temperature; otherwise, the vehicle intrusion process continues.

[0013] The set ambient temperature is lower than the set cell temperature, and the difference between the set ambient temperature and the set cell temperature is constant. The set ambient temperature for the initial experiment is -25℃, and the set cell temperature for the initial experiment is -20℃.

[0014] Three scenarios may occur during step 2:

[0015] Situation 1: The vehicle's instrument panel displays abnormally, reporting vehicle malfunction and power battery malfunction, and cold start fails;

[0016] Scenario 2: The vehicle's instrument panel displays normally with no fault indication, but the vehicle cannot be driven normally and cold start fails;

[0017] Scenario 3: The vehicle's instrument panel displays normally with no fault indication. When the vehicle is engaged in forward and reverse gears, it can be driven normally, indicating a successful cold start.

[0018] Step 3 includes the following steps:

[0019] 1) If the first measurement meets condition 1 or 2, then gradually increase the set ambient temperature and execute step 1 at the increased set ambient temperature until condition 3 is met. Then proceed to the next step, record the current set ambient temperature as the minimum start temperature, and proceed to the next step.

[0020] If the first measurement meets condition 3, then gradually lower the set ambient temperature and execute step 1 at the lowered set ambient temperature until condition 1 or condition 2 occurs. Record the last set ambient temperature as the lowest start temperature and execute the next step.

[0021] 2) After obtaining the lowest start-up temperature, repeat steps 1 and 2 using the lowest start-up temperature as the set ambient temperature. If condition 3 is met again, proceed to the next step; otherwise, return feedback that the experiment failed and end the experiment.

[0022] 3) Perform a full accelerator pedal opening acceleration test to 100 km / h and measure the data parameters.

[0023] 4) Based on the previous set ambient temperature, increase the set temperature value as the new set ambient temperature, and repeat steps 1-3 again, where step 3 is directly executed until the corresponding data parameters are obtained and the acceleration performance is the same or close to that under the standard ambient temperature. Record the currently executed set ambient temperature as the lowest value of the ambient temperature in the optimal performance state.

[0024] The data parameters include acceleration time, peak discharge current, and total voltage; the set temperature increase value is 2-5℃, and the standard ambient temperature is 20℃.

[0025] In step 3, if the measurement satisfies condition 1, the ambient temperature is increased by 5°C; if the measurement satisfies condition 2, the ambient temperature is increased by 2°C; and if the measurement satisfies condition 3, the ambient temperature is decreased by 2°C.

[0026] In step 4, the data parameters obtained from the ambient temperature for different parking conditions in step 3 are recorded in the vehicle user manual, and the minimum starting temperature and the minimum ambient temperature for optimal performance are also recorded.

[0027] If the vehicle being tested has a preset minimum starting temperature, the measured minimum starting temperature is compared with this value to determine whether the preset minimum starting temperature is correct.

[0028] When the experimental vehicle has a preset minimum ambient temperature for optimal performance, the measured minimum ambient temperature for optimal performance is compared with this value to determine whether the preset minimum ambient temperature for optimal performance is correct.

[0029] If no preset minimum start-up temperature or minimum ambient temperature for optimal performance is specified, the measured minimum start-up temperature and minimum ambient temperature for optimal performance will be used directly.

[0030] This invention can reliably determine the low-temperature discharge capability of new energy vehicles, improve the reliability of vehicles in cold regions, facilitate vehicle manufacturers in verifying vehicle performance, and enable them to edit more accurate vehicle user manuals. Attached Figure Description

[0031] The following is a brief explanation of the content represented by each figure in this specification:

[0032] Figure 1 A flowchart illustrating the method for determining the low-temperature discharge capability of new energy vehicles. Detailed Implementation

[0033] The following description, with reference to the accompanying drawings, details the specific implementation of the present invention, including the shape and structure of each component, the relative positions and connections between the parts, the function and working principle of each part, the manufacturing process, and the operation and use methods, to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0034] like Figure 1 As shown, the method for determining the low-temperature discharge capability of new energy vehicles includes the following steps:

[0035] Step 1, Vehicle Immersion Process: Open the vehicle windows and doors, and park the vehicle in an environment with a temperature lower than the set ambient temperature for immersion (parking in an environment with a constant temperature) for at least 8-12 hours. Monitor whether the minimum temperature of the individual battery cells is lower than the set cell temperature (in conventional electric vehicles, under BMS control, if the individual cell temperature is lower than the set cell temperature, the battery is in protection mode and the vehicle cannot operate normally); allow the vehicle to cool down sufficiently at the set temperature; if the minimum temperature of the individual battery cells is not lower than the set cell temperature, continue the immersion process until the minimum temperature of the individual battery cells reaches the set cell temperature.

[0036] The ambient temperature and the battery cell temperature can be set as needed, but the ambient temperature must be lower than the battery cell temperature, and the difference between the ambient temperature and the battery cell temperature must be constant, such as 55℃. For example, the ambient temperature set for the initial experiment is -25℃, and the battery cell temperature set for the initial experiment is -20℃.

[0037] Step 2, Cold Start Process: When starting the vehicle, if the temperature of a single battery cell is lower than the set cell temperature, the following three situations may occur:

[0038] Situation 1: The vehicle's instrument panel displays abnormally, reporting vehicle malfunction and power battery malfunction, and cold start fails;

[0039] Scenario 2: The vehicle's instrument panel displays normally with no fault indication, but the vehicle cannot be driven normally and cold start fails;

[0040] Scenario 3: If the vehicle's instrument panel displays normally and there are no fault indications, and the vehicle can be driven normally when engaged in both forward and reverse gears, then the cold start was successful.

[0041] Step 3, Discharge Process: When the lowest temperature of a single battery cell is -20℃ (or the single cell is at the minimum allowable driving temperature), perform a 100km / h acceleration test with the accelerator pedal fully open, and measure the acceleration time, peak discharge current, and total voltage. During vehicle operation, the temperature of the battery cells will gradually increase. Following the above test method, perform a 100km / h acceleration test at every -5℃ interval. As the battery temperature increases, the 100km / h acceleration time and peak discharge current will increase accordingly. Ultimately, the optimal battery temperature for achieving the acceleration performance under standard environmental conditions (20℃) can be determined.

[0042] Specifically, temperature testing can be varied as needed to obtain the lowest and optimal temperature values. This involves the following steps:

[0043] 1) If the first measurement meets condition 1 or condition 2, then gradually increase the set ambient temperature and execute step 1 at the increased set ambient temperature until condition 3 is met. Then proceed to the next step, record the current set ambient temperature as the minimum start temperature, and proceed to the next step.

[0044] If the first measurement meets condition 3, then gradually lower the set ambient temperature and execute step 1 at the lowered set ambient temperature until condition 1 or condition 2 occurs. Record the last set ambient temperature as the lowest start temperature and execute the next step.

[0045] Because each vehicle intrusion process takes a long time, in order to speed up the experiment, if the measurement meets condition 1, the ambient temperature is increased by 5°C; if the measurement meets condition 2, the ambient temperature is increased by 2°C; if the measurement meets condition 3, the ambient temperature is decreased by 2°C. Therefore, condition 1 is far from being able to use the vehicle, so the temperature increase can be appropriately increased to speed up the experiment.

[0046] 2) After obtaining the lowest start-up temperature, repeat steps 1 and 2 using the lowest start-up temperature as the set ambient temperature. If condition 3 is met again, proceed to the next step; otherwise, return feedback that the experiment failed and end the experiment.

[0047] 3) After obtaining the lowest starting temperature, perform an acceleration test based on this temperature, and perform a full accelerator pedal opening 0-100 km / h acceleration (full throttle acceleration), and measure the data parameters, including acceleration time, peak discharge current, and total voltage.

[0048] 4) Based on the previous set ambient temperature, increase the set temperature value as the new set ambient temperature. For example, each time the temperature value is increased by 2-5℃. Based on the new set ambient temperature, repeat steps 1-3 again. In step 3, directly execute 3), skipping steps 1) and 2) in step 3, and directly conduct 0-100 km / h acceleration tests at different temperatures until the corresponding data parameters are obtained and the acceleration performance is the same as or close to that under the standard ambient temperature. Record the current set ambient temperature as the lowest value of the ambient temperature under the optimal performance state. The standard ambient temperature is the optimal temperature for vehicle design and use, which is generally 20℃.

[0049] Step 4: Obtain the results of the low-temperature discharge capability of the new energy vehicle. That is, record the data parameters obtained from different parking conditions in Step 3 at different ambient temperatures in the vehicle's user manual, and record the minimum starting temperature and the minimum ambient temperature of the optimal performance state.

[0050] Generally, when a test vehicle is subjected to low-temperature immersion, the following two situations will occur: (1) if the vehicle's design minimum starting temperature is confirmed, the vehicle will be immersed to a temperature 2-3°C below the design temperature; (2) if the vehicle's design minimum starting temperature is not confirmed, the vehicle will be immersed to the lowest achievable temperature. Based on these two situations, a cold start test will be conducted, resulting in the following two outcomes: (1) confirming whether the actual cold start temperature of the vehicle matches the design temperature; (2) accurately determining the vehicle's cold start temperature. Based on these two situations, low-temperature discharge (100 km / h acceleration at different temperatures) will be performed, and the strength of the vehicle's discharge capacity at each temperature point will be measured. Finally, it will be determined at what battery temperature the vehicle can achieve the acceleration performance under standard environmental conditions (20°C).

[0051] The analysis results can be used to verify the original design or to find the actual temperature parameters of the vehicle:

[0052] If the vehicle being tested has a preset minimum starting temperature, the measured minimum starting temperature is compared with this value to determine whether the preset minimum starting temperature is correct.

[0053] When the experimental vehicle has a preset minimum ambient temperature for optimal performance, the measured minimum ambient temperature for optimal performance is compared with this value to determine whether the preset minimum ambient temperature for optimal performance is correct.

[0054] If no preset minimum start-up temperature or minimum ambient temperature for optimal performance is specified, the measured minimum start-up temperature and minimum ambient temperature for optimal performance will be used directly.

[0055] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for determining the low-temperature discharge capability of new energy vehicles, characterized in that, Includes the following steps: Step 1, Immersion process: Allow the vehicle to cool down sufficiently at the set temperature; Step 2, Cold Start Process: Start the vehicle; Step 3, Discharge process: While accelerating the vehicle, record the parameter information; Step 4: Obtain the results of the low-temperature discharge capability of new energy vehicles; Three scenarios may occur during step 2: Situation 1: The vehicle's instrument panel displays abnormally, reporting vehicle malfunction and power battery malfunction, and cold start fails; Scenario 2: The vehicle's instrument panel displays normally with no fault indication, but the vehicle cannot be driven normally and cold start fails; Scenario 3: The vehicle's instrument panel displays normally with no fault indication. The vehicle can be driven normally when engaged in both forward and reverse gears, indicating a successful cold start. Step 3 includes the following steps: 1) If the first measurement meets condition 1 or 2, then gradually increase the set ambient temperature and execute step 1 at the increased set ambient temperature until condition 3 is met. Then proceed to the next step, record the current set ambient temperature as the minimum start temperature, and proceed to the next step. If the first measurement meets condition 3, then gradually lower the set ambient temperature and execute step 1 at the lowered set ambient temperature until condition 1 or condition 2 occurs. Record the last set ambient temperature as the lowest start temperature and execute the next step. 2) After obtaining the lowest start-up temperature, repeat steps 1 and 2 using the lowest start-up temperature as the set ambient temperature. If condition 3 is met again, proceed to the next step; otherwise, return feedback that the experiment failed and end the experiment. 3) Perform a full accelerator pedal opening acceleration test to 100 km / h and measure the data parameters. 4) Based on the previous set ambient temperature, increase the set temperature value as the new set ambient temperature, and repeat steps 1-3 again, where step 3 is directly executed (3) until the corresponding data parameters are obtained and the acceleration performance is the same or close to that under the standard ambient temperature. Record the currently executed set ambient temperature as the lowest value of the ambient temperature in the optimal performance state.

2. The method for determining the low-temperature discharge capability of new energy vehicles according to claim 1, characterized in that: In step 1, the vehicle windows and doors are opened, and the vehicle is parked in an environment where the ambient temperature is equal to the set ambient temperature, and soaked for 8-12 hours or more.

3. The method for determining the low-temperature discharge capability of new energy vehicles according to claim 2, characterized in that: In step 1, before the immersion process ends, the lowest temperature of the power battery cell is obtained. The lowest temperature of the power battery cell must be lower than the set cell temperature; otherwise, the immersion process continues.

4. The method for determining the low-temperature discharge capability of new energy vehicles according to claim 3, characterized in that: The set ambient temperature is lower than the set cell temperature, and the difference between the set ambient temperature and the set cell temperature is constant. The set ambient temperature for the initial experiment is -25℃, and the set cell temperature for the initial experiment is -20℃.

5. The method for determining the low-temperature discharge capability of new energy vehicles according to claim 4, characterized in that: The data parameters include acceleration time, peak discharge current, and total voltage; the set temperature increase value is 2-5℃, and the standard ambient temperature is 20℃.

6. The method for determining the low-temperature discharge capability of new energy vehicles according to claim 5, characterized in that: In step 3, if the measurement satisfies condition 1, the ambient temperature is increased by 5°C; if the measurement satisfies condition 2, the ambient temperature is increased by 2°C; and if the measurement satisfies condition 3, the ambient temperature is decreased by 2°C.

7. The method for determining the low-temperature discharge capability of new energy vehicles according to claim 6, characterized in that: In step 4, the data parameters obtained from the ambient temperature for different parking conditions in step 3 are recorded in the vehicle user manual, and the minimum starting temperature and the minimum ambient temperature for optimal performance are also recorded.

8. The method for determining the low-temperature discharge capability of new energy vehicles according to claim 7, characterized in that: If the vehicle being tested has a preset minimum starting temperature, the measured minimum starting temperature is compared with this value to determine whether the preset minimum starting temperature is correct. When the experimental vehicle has a preset minimum ambient temperature for optimal performance, the measured minimum ambient temperature for optimal performance is compared with this value to determine whether the preset minimum ambient temperature for optimal performance is correct. If no preset minimum start-up temperature or minimum ambient temperature for optimal performance is specified, the measured minimum start-up temperature and minimum ambient temperature for optimal performance will be used directly.

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