A test method, device and system for the endurance mileage of an electric vehicle in a cold region

Abstract

This invention provides a method, apparatus, and system for testing the driving range of electric vehicles in cold regions. The method includes: adjusting the temperature inside a temperature chamber to the test temperature; conducting cyclic tests on the vehicle under test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating conditions at the test temperature; after the test, acquiring the driving mileage and energy change of the vehicle under test for each test cycle; determining the actual driving range of the vehicle under test based on the driving mileage and battery data. Thus, based on the characteristics of cold-region scenarios, the method determines the test temperature, driving speed range, and driving resistance suitable for cold-region scenarios, providing test conditions that are more closely aligned with the actual environment. This comprehensively and accurately simulates and adapts to actual driving scenarios in cold regions, thereby effectively improving the accuracy of driving range testing in cold-region scenarios. Furthermore, this invention utilizes a temperature chamber to provide the test temperature, allowing for repeated testing and further improving test accuracy.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and in particular to a method, apparatus and system for testing the driving range of electric vehicles in cold regions. Background Technology

[0002] Testing of pure electric passenger vehicles involves the evaluation and verification of multiple performance aspects, such as energy consumption and driving range.

[0003] In related technologies, pure electric passenger vehicles are generally tested under normal conditions according to national standard testing standards. However, cold-region scenarios mainly involve low temperatures, localized snow, and are primarily located in urban and suburban areas. In cold-region scenarios, low temperatures, snowfall, or snow-covered roads persist for most of winter, spring, and autumn, resulting in different road resistance and driving speed patterns compared to typical areas. Under these scenarios, the driving range of pure electric vehicles differs significantly from that tested under normal conditions according to national standard testing standards, and the degree of difference varies depending on the vehicle's characteristics.

[0004] Therefore, there is an urgent need for a method to test the driving range of pure electric vehicles in cold-weather scenarios, so as to improve the accuracy of the driving range test for pure electric vehicles in cold-weather scenarios. Summary of the Invention

[0005] To address the problems existing in the prior art, embodiments of the present invention provide a method, apparatus, and system for testing the driving range of electric vehicles in cold regions, so as to solve or partially solve the technical problem that the prior art cannot accurately test the driving range of electric vehicles in cold-region scenarios.

[0006] A first aspect of the present invention provides a method for testing the cold-weather driving range of an electric vehicle, the method comprising:

[0007] When the fully charged vehicle under test is placed in the temperature chamber, the temperature inside the temperature chamber is adjusted to the test temperature.

[0008] Obtain the driving speed range corresponding to the cold region scenario and the driving resistance corresponding to the working condition type of the cold region scenario;

[0009] At the test temperature, the vehicle under test is subjected to cyclic testing based on the driving speed range corresponding to the cold region scenario and the driving resistance corresponding to the cold region scenario working condition type. After the test, the driving mileage of the vehicle under test and the change in electrical energy of the vehicle under test in each test cycle are obtained.

[0010] The actual driving range of the vehicle under test is determined based on the mileage of the vehicle under test in each test cycle and the change in the electrical energy of the vehicle under test in each test cycle.

[0011] In the above solution, obtaining the driving speed range corresponding to the cold-region scenario includes:

[0012] Obtain the first M speed segments in the test standard, where M is greater than 9 and is a positive integer;

[0013] The Nth driving speed segment, the idle driving speed segment, and the Mth driving speed segment from the first M driving speed segments are combined to obtain a combined driving speed segment; where N is less than M.

[0014] The combined driving speed segment is combined again with the first M driving speed segments to obtain the driving speed segment corresponding to the cold region scenario.

[0015] In the above solution, obtaining the driving resistance corresponding to the cold-region scenario operating condition type includes:

[0016] When the operating condition is a slipping condition, according to the formula Determine the slip resistance corresponding to the stationary slip condition. ;

[0017] Among them, the The coefficient of friction for sliding on hard snow is... The mass of the vehicle under test, the g This is the gravity coefficient.

[0018] In the above solution, obtaining the driving resistance corresponding to the cold-region scenario operating condition type includes:

[0019] When the working condition is a snow-covered road surface, according to the formula... Determine the driving resistance on the snow-covered road surface corresponding to the snow-covered road surface condition. ;

[0020] Among them, the The mass of the vehicle under test, the The rolling resistance coefficient of the snow-covered road surface is... The width of the vehicle under test, the The height of the vehicle to be measured, the The acceleration of the vehicle under test, the The speed of the vehicle under test is denoted as .

[0021] In the above scheme, the step of performing cyclic testing on the vehicle under test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating condition type includes:

[0022] Determine the slip speed threshold corresponding to the stationary slip condition, and determine the slip period in each driving speed segment based on the slip speed threshold; during the cyclic test, apply slip driving resistance to the vehicle under test during the slip period of each driving speed segment.

[0023] During the non-slipping periods in the target low-speed and target medium-speed segments of the driving speed range corresponding to the cold-region scenario, apply the snow-covered road surface driving resistance to the vehicle under test.

[0024] During the remaining time period within the remaining driving speed range, apply low-temperature driving resistance to the vehicle under test until the test termination condition is met.

[0025] In the above scheme, determining the slip speed threshold corresponding to the in-situ slip condition includes:

[0026] According to the formula Determine the slippage speed threshold ;in,

[0027] The The relative speed between the vehicle and the road surface during acceleration and skidding in place, the The probability of slipping during acceleration in place, the To determine the probability of skidding during rapid acceleration, the following... The relative speed between the vehicle under test and the road surface during rapid acceleration and skidding.

[0028] In the above scheme, determining the slippage period in each driving speed segment based on the slippage speed threshold includes:

[0029] The speed values ​​in the head speed range of each driving speed segment that are less than the target speed threshold are assigned as the slippage speed threshold, and the speed values ​​in the tail speed range of each driving speed segment that are less than the target speed threshold are assigned as the slippage speed threshold; the target speed threshold is preset.

[0030] The system determines the first duration from the initial acceleration to reaching the last slip speed threshold in the head speed range of each driving speed segment, and the second duration corresponding to a speed greater than 0 and less than or equal to the first slip speed threshold in the tail speed range of each driving speed segment; the head speed range is the speed range corresponding to the beginning period of the driving speed segment, and the tail speed range is the speed range corresponding to the end period of the driving speed segment.

[0031] The sum of the first duration corresponding to each driving speed segment, the second duration corresponding to each driving speed segment, and the preset duration before the initial moment of each driving speed segment is taken as the slippage period of each driving speed segment; wherein, there is a transition period between two adjacent driving speed segments.

[0032] In the above scheme, obtaining the mileage of the vehicle under test in each test cycle includes:

[0033] Determine the slippage period for each speed segment in each test cycle, and determine the total slippage period in the test cycle based on the slippage period for each speed segment;

[0034] The actual driving time period is determined based on the time period corresponding to each test cycle and the total slippage time period;

[0035] The speed is integrated based on the actual driving time period to obtain the driving distance for each test cycle.

[0036] A second aspect of the present invention provides a testing device for the cold-weather driving range of an electric vehicle, the device comprising:

[0037] The adjustment unit is used to adjust the temperature inside the temperature chamber to the test temperature when the fully charged vehicle under test is placed inside the temperature chamber.

[0038] The acquisition unit is used to acquire the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the working condition type of the cold-region scenario.

[0039] The testing unit is used to perform cyclic testing on the vehicle under test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario working condition type at the test temperature. After the test, the unit obtains the driving mileage of the vehicle under test and the change in electrical energy of the vehicle under test in each test cycle.

[0040] The determining unit is used to determine the actual driving range of the vehicle under test based on the driving mileage of the vehicle under test in each test cycle and the change in electrical energy of the vehicle under test in each test cycle.

[0041] A third aspect of the present invention provides a testing system for the cold-weather driving range of an electric vehicle, the system comprising: a temperature chamber, a temperature regulating device, a drum dynamometer, a drum dynamometer control device, an energy consumption acquisition and processing device, and the testing device described in the second aspect; wherein the temperature regulating device, the drum dynamometer control device, and the energy consumption acquisition and processing device are electrically connected to the testing device.

[0042] The temperature chamber is used to house the vehicle to be tested;

[0043] The temperature regulating device is controlled by the testing device and is used to regulate the temperature inside the temperature chamber to the testing temperature.

[0044] The rotary drum dynamometer control device, controlled by the testing device, is used to control the rotary drum dynamometer to provide the driving resistance required by the vehicle under test;

[0045] The energy consumption acquisition and processing device, controlled by the testing device, is used to determine the change in electrical energy of the vehicle under test.

[0046] The testing device is used to place a fully charged vehicle under test in a temperature chamber and adjust the temperature inside the chamber to the test temperature; acquire the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating condition type; perform cyclic testing on the vehicle under test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating condition type at the test temperature; after the test, acquire the driving mileage of the vehicle under test in each test cycle and the change in the vehicle's electrical energy in each test cycle; and determine the actual driving range of the vehicle under test based on the driving mileage of the vehicle under test in each test cycle and the change in the vehicle's electrical energy in each test cycle.

[0047] This invention provides a method, apparatus, and system for testing the cold-weather driving range of an electric vehicle. The method includes: placing a fully charged vehicle under test in a temperature chamber and adjusting the temperature inside the chamber to the test temperature; obtaining the driving speed range corresponding to the cold-weather scenario and the driving resistance corresponding to the cold-weather scenario operating condition type; performing a cyclic test on the vehicle under test based on the driving speed range and driving resistance corresponding to the cold-weather scenario operating condition type at the test temperature; and after the test, obtaining the driving range and energy change of the vehicle under test in each test cycle. The actual driving range of the vehicle under test is determined based on the mileage and energy change of the vehicle under test in each test cycle. Thus, according to the characteristics of cold-region scenarios, the test temperature, driving speed range, and driving resistance suitable for cold-region scenarios are determined, providing test conditions that are more in line with the actual environment. This comprehensively and accurately simulates and adapts to actual driving scenarios in cold regions, thereby effectively improving the accuracy of driving range testing in cold-region scenarios. Furthermore, this invention utilizes a temperature chamber to provide the test temperature, allowing for repeated testing and further improving test accuracy. Attached Figure Description

[0048] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0049] Figure 1 A schematic diagram of a test system for the cold-weather driving range of an electric vehicle according to an embodiment of the present invention is shown;

[0050] Figure 2 A schematic flowchart of a method for testing the cold-weather driving range of an electric vehicle according to an embodiment of the present invention is shown.

[0051] Figure 3 A schematic diagram showing the speed and resistance distribution for each driving speed segment within a test cycle according to an embodiment of the present invention is shown;

[0052] Figure 4 A schematic diagram of a test apparatus for measuring the cold-weather driving range of an electric vehicle according to an embodiment of the present invention is shown. Detailed Implementation

[0053] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0054] To better understand the technical solution of this invention, a testing system for the cold-weather driving range of electric vehicles will be introduced first, such as... Figure 1 As shown, the system includes: a temperature chamber 1, a temperature regulating device 2, a drum dynamometer 3, a drum dynamometer control device 4, an energy consumption acquisition and processing device 5, and a testing device (not shown in the figure); wherein, the temperature regulating device 2, the drum dynamometer control device 4, and the energy consumption acquisition and processing device 5 are electrically connected to the testing device.

[0055] Temperature chamber 1, used to accommodate the vehicle to be tested 6;

[0056] Temperature regulation device 2, controlled by the testing device, is used to regulate the temperature inside temperature chamber 1 to the testing temperature.

[0057] The drum dynamometer control device 4, controlled by the testing device, is used to control the drum dynamometer 3 to provide the driving resistance required by the vehicle under test 6.

[0058] The energy consumption acquisition and processing device 5 is controlled by the testing device and is used to determine the change in electrical energy of the vehicle under test 6.

[0059] The testing device is used to place a fully charged vehicle under test (V2T) 6 in a temperature chamber 1, adjust the temperature of the chamber 1 to the test temperature, and immerse the vehicle for 12 hours. It then acquires the driving speed range corresponding to the cold-weather scenario and the driving resistance corresponding to the cold-weather scenario operating conditions. At the test temperature, it performs cyclic testing on the V2T based on the driving speed range and driving resistance corresponding to the cold-weather scenario operating conditions. After the test, it acquires the mileage of the V2T in each test cycle and the change in electrical energy of the V2T in each test cycle. Based on the mileage and the change in electrical energy of the V2T in each test cycle, it determines the actual driving range of the V2T. Immersion refers to placing the V2T 6 in a specific temperature environment for a period of time to allow the power battery of the V2T 6 to reach a stable temperature state.

[0060] In addition, the system also includes: a fan 7; used to simulate the airflow field when the vehicle under test 6 is in motion, to restore the environment in which cold air cools the vehicle during actual driving, and to ensure that the test conditions are consistent with the heat exchange conditions between the vehicle's inner and outer boundaries in real road scenarios.

[0061] The specific implementation principle of the testing device can be found in the detailed description of the subsequent test device implementation examples, and will not be repeated here.

[0062] Based on the same inventive concept as described above, this invention also provides a method for testing the cold-weather driving range of electric vehicles, which is applied in a testing device, such as... Figure 2 As shown, the method includes the following steps:

[0063] S210, when the fully charged vehicle under test is placed in the temperature chamber, the temperature inside the temperature chamber is adjusted to the test temperature.

[0064] As mentioned above, this invention tests the driving range of the vehicle under test in an experimental scenario. Therefore, the vehicle to be fully charged needs to be placed in a temperature chamber, the temperature inside the temperature chamber is adjusted to the test temperature, and the test begins after immersing the vehicle for 12 hours.

[0065] The test temperature for cold-region scenarios needs to be determined in advance. In one implementation, before adjusting the temperature inside the temperature chamber to the test temperature, the method further includes:

[0066] The historical temperature during driving time in cold-region scenarios is obtained, and the historical temperatures are sorted in a preset order to obtain a temperature distribution sequence.

[0067] Determine the cumulative probability corresponding to each temperature in the temperature distribution sequence;

[0068] Find the target temperature that meets the preset probability threshold in the cumulative probability, and determine the target temperature as the test temperature.

[0069] Specifically, it can obtain hourly historical temperatures during the main driving periods in winter (e.g., 6:00-22:00) in cold-region scenarios, sort the obtained historical temperatures in ascending order to obtain a temperature distribution sequence; then, for each historical temperature in the temperature distribution sequence... According to formula (1), the temperature is lower than Cumulative probability :

[0070] (1)

[0071] In formula (1), For temperatures below The cumulative duration, Total duration of all historical temperatures.

[0072] Then according to the formula Determine the corresponding target temperature ; As a probability threshold, For historical temperatures below The cumulative probability. Among them, The range is 5% to 50%, for example, it can be 38%; The range of values ​​is .

[0073] For example, suppose If it is 38%, then the corresponding for The test temperature is However, in actual testing, the test temperature can be... That is, when for The test temperature can be .

[0074] This determined the appropriate test temperature for cold-region scenarios.

[0075] S211, obtain the driving speed range corresponding to the cold region scenario and the driving resistance corresponding to the working condition type of the cold region scenario.

[0076] In order to provide the test vehicle with test conditions that are more in line with the actual environment and to accurately simulate and adapt to the actual driving scenarios in cold regions in all aspects, this invention also needs to obtain the driving speed range corresponding to the cold region scenario and the driving resistance corresponding to the working condition type of the cold region scenario.

[0077] In one implementation, obtaining the driving speed range corresponding to the cold-region scenario includes:

[0078] Obtain the first M speed segments in the test standard, where M is greater than and is a positive integer;

[0079] Combine the Nth speed segment, the idle speed segment, and the Mth speed segment from the first M speed segments to obtain a combined speed segment; N is less than M;

[0080] The combined driving speed segment is then combined with the first M driving speed segments to obtain the driving speed segment corresponding to the cold region scenario.

[0081] The testing standard is the China Light Vehicle Driving Condition (Passenger Car Version) Test Standard (CLTC_P).

[0082] The China Light-duty Vehicle Test Cycle (Passenger car) standard specifies a test duration of 1800 seconds (one test cycle is 1800 seconds). One test cycle includes three speed ranges: low speed, medium speed, and high speed. The low speed range lasts 674 seconds, the medium speed range lasts 693 seconds, and the high speed range lasts 433 seconds. The low speed range contains seven speed segments, the medium speed range contains three speed segments, and the high speed range contains one speed segment.

[0083] Due to the environmental characteristics of cold-region scenarios, vehicles generally travel at low or medium speeds. Therefore, this invention obtains the first M speed segments in the test standard, where M can be 10. The 8th speed segment, the 8-second idle segment (an 8-second segment with a speed value of 0 km / h), and the 10th speed segment from the first 10 speed segments are combined to obtain a combined speed segment. Then, the combined speed segment replaces the 11th speed segment in the test standard. Finally, the combined speed segment is combined with the first 10 speed segments to obtain a total of 12 speed segments that conform to cold-region scenarios, which are the first 10 speed segments, the 8th speed segment, and the 10th speed segment in the test standard, respectively. There will be an idle segment (also called a transition period) of a corresponding length between two adjacent speed segments.

[0084] Similarly, since cold-region scenarios mainly include three types of operating conditions: normal operating conditions, stationary slipping conditions, and snowy road conditions, this invention also needs to obtain the driving resistance corresponding to each type of cold-region scenario operating condition in order to conform to the actual scenario.

[0085] In one implementation, obtaining the driving resistance corresponding to the cold-region scenario operating condition type includes:

[0086] When the working condition is stationary slippage, the slippage resistance corresponding to the stationary slippage condition is determined according to formula (2). :

[0087] (2)

[0088] In formula (2), The coefficient of friction for sliding on hard snow is typically between 0.03 and 0.2, and can be as low as 0.06. For the mass of the vehicle under test, is the gravity coefficient. Wherein, It can be determined based on vehicle sliding friction resistance tests on hard snow surfaces at road test tracks; for example, it can be calculated based on the tension force experienced by a vehicle when its wheels are braked and it is being dragged at a constant speed on hard snow; or it can be calculated by measuring the torque at the time of slippage using torque patches on the vehicle's drive shaft when the wheels slip due to sudden acceleration while stationary on hard snow. There are no restrictions on this.

[0089] In one implementation, obtaining the driving resistance corresponding to the cold-region scenario operating condition type includes:

[0090] When the working condition is a loose snow road surface, the driving resistance of the loose snow road surface corresponding to the loose snow road surface working condition is determined according to formula (3). :

[0091] (3)

[0092] In formula (3), For the mass of the vehicle under test, The rolling resistance coefficient of the snow-covered road surface. The width of the vehicle to be measured is in meters (m). The height of the vehicle to be measured is in meters (m). For acceleration, The speed of the vehicle under test is expressed in km / h.

[0093] The rolling resistance coefficient of the snow-covered road surface can be obtained by testing the vehicle under test: for example, when the vehicle under test is traveling at a constant speed (low speed) on a horizontal snow cover. When driving on loose snow, the snow thickness can be 8cm. The rolling resistance coefficient on loose snow is determined by obtaining the torque measured by the torque patch on the drive shaft, combined with the tire outer diameter and the transmission ratio between the wheel and the drive shaft.

[0094] (4)

[0095] In formula (4), For the torque of the drive motor, The transmission ratio is... For the transmission mechanical efficiency, the The outer diameter of the tire, the For the mass of the vehicle under test, the This is the gravity coefficient (gravitational acceleration).

[0096] The rolling resistance coefficient of the snow-covered road surface ranges from 0.03 to 0.1, for example, it can be 0.5.

[0097] When the operating condition is normal, the corresponding resistance is determined to be the conventional low-temperature driving resistance. Specifically, the conventional low-temperature driving resistance... It can be determined according to formula (5):

[0098] (5)

[0099] In formula (5), This is a driving resistance correction factor commonly used in cold-region scenarios, for example, it can be 1.1~1.2; This refers to the driving resistance in the standard test at room temperature.

[0100] This determined the corresponding driving speed range and driving resistance under different operating conditions in cold-region scenarios, laying the foundation for subsequent testing.

[0101] S212, at the test temperature, the vehicle under test is subjected to a cyclic test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating condition type. After the test, the driving mileage of the vehicle under test and the change in electrical energy of the vehicle under test in each test cycle are obtained.

[0102] In one implementation, the vehicle under test is subjected to cyclic testing based on the driving speed range corresponding to the cold-weather scenario and the driving resistance corresponding to the operating condition type of the cold-weather scenario, including:

[0103] Determine the slip speed threshold corresponding to the stationary slip condition, and determine the slip period in each driving speed segment based on the slip speed threshold; during the cyclic test, apply slip driving resistance to the vehicle under test during the slip period in each driving speed segment;

[0104] During the non-slipping periods in the second and ninth speed segments of the driving speed range corresponding to the cold region scenario, the driving resistance of the snow-covered road surface is applied to the vehicle under test.

[0105] During the remaining time period within the remaining driving speed range, apply the usual low-temperature driving resistance to the vehicle under test until the test termination condition is met. The test termination condition can be that the battery charge of the vehicle under test decreases to the point where the real-time wheel-end speed is 2 km / h lower than the set speed value.

[0106] Specifically, the operating conditions for each speed range may be different. Therefore, it is necessary to determine the duration of each operating condition in each speed range so that the appropriate driving resistance can be applied accurately to the operating condition of each speed range during the cyclic test.

[0107] Each speed range includes a stationary slippage condition; therefore, this invention requires determining the total duration of the stationary slippage condition within a test cycle. It can be determined according to formula (6):

[0108] (6)

[0109] In formula (6), This represents the probability of slipping on the spot. The value range is generally 135~145s.

[0110] The probability of slipping in place can be determined according to formula (7):

[0111] (7)

[0112] In formula (7), The proportion of aggressive acceleration by pressing the accelerator during the entire driving process. This represents the weighted average number of days throughout the year when snow (not yet cleared or sprayed with de-icing agents, and already compacted into solid snow by the wheels of previously passed vehicles) remains on urban and highway roads in cold-region scenarios. This refers to the number of days in a year when the average daily temperature in a cold region is lower than the target temperature.

[0113] For example, when the probability of slipping in place is 7.5%, the total duration of slipping in place is 135 seconds, that is, the slipping period is 135 seconds.

[0114] Once the total duration of the stationary slippage condition is determined, it needs to be allocated to each speed range. First, the slippage speed threshold needs to be determined, and then the duration of the stationary slippage condition within each driving speed range needs to be determined based on the slippage speed threshold.

[0115] In one implementation, determining the slip speed threshold corresponding to the in-situ slip condition includes:

[0116] The slippage speed threshold is determined according to formula (8). :

[0117] (8)

[0118] In formula (8), The relative speed between the vehicle and the road surface when accelerating and skidding in place. To determine the probability of slipping while accelerating in place. To increase the probability of skidding during rapid acceleration, This refers to the relative speed between the vehicle and the road surface during rapid acceleration and skidding. For example, the skidding speed threshold could be 6 km / h.

[0119] Once the slippage speed threshold is determined, the speed values ​​in the initial speed range of each driving speed segment (speed gradually increases from 0) that are less than the target speed threshold are reassigned as the slippage speed threshold. Similarly, the speed values ​​in the final speed range of each driving speed segment that are less than the target speed threshold (excluding 0) are also reassigned as the slippage speed threshold. The target speed threshold can be preset according to actual conditions, for example, it could be 12 km / h.

[0120] Taking the head speed range of a certain driving speed segment as an example, suppose the speed at 1 second is 1 km / h, the speed at 2 seconds is 2 km / h, the speed at 3 seconds is 4 km / h, the speed at 4 seconds is 6 km / h, the speed at 5 seconds is 9 km / h, the speed at 6 seconds is 11 km / h, and the speed at 7 seconds is 12 km / h; then the speeds from 1 to 6 seconds are reassigned to the slippage speed threshold (6 km / h).

[0121] Taking the speed range at the end of a certain driving speed segment as an example, suppose the speed at 20s is 12km / h, the speed at 21s is 10km / h, the speed at 22s is 8km / h, the speed at 23s is 7km / h, the speed at 24s is 5km / h, the speed at 25s is 4km / h, the speed at 26s is 3km / h, and the speed at 27s is 0km / h; then the speeds from 21s to 26s are reassigned to the slippage speed threshold (6km / h).

[0122] In one implementation, determining the slippage period in each driving speed segment based on a slippage speed threshold includes:

[0123] The speed values ​​in the head speed range of each driving speed segment that are less than the target speed threshold are assigned as the slip speed threshold, and the speed values ​​in the tail speed range of each driving speed segment that are less than the target speed threshold are assigned as the slip speed threshold; the head speed range is the speed range corresponding to the beginning of the driving speed segment, and the tail speed range is the speed range corresponding to the end of the driving speed segment;

[0124] Determine the first duration from the initial acceleration to the speed reaching the last slip speed threshold in the head speed range of each driving speed segment, and determine the second duration corresponding to the tail speed range of each driving speed segment that is greater than 0 and less than or equal to the first slip speed threshold.

[0125] The sum of the first duration corresponding to each driving speed segment, the second duration corresponding to each driving speed segment, and the preset duration before the initial moment of each driving speed segment is taken as the slippage period of each driving speed segment; wherein, there is a transition period between two adjacent driving speed segments.

[0126] Continuing with the example of the head speed range in a certain driving speed range, the time corresponding to the last slip speed threshold in the head speed range is 6 seconds. Therefore, the first time taken from the initial acceleration to the speed reaching the last slip speed threshold in the head speed range is 6 seconds.

[0127] It should be noted that the last slip speed threshold and the first slip speed threshold mentioned in this invention are described in terms of the order of the test time from beginning to end.

[0128] Taking the tail speed range of a certain driving speed segment as an example, the time corresponding to the first slip speed threshold in the tail speed range is 21s, and the time corresponding to 0 speed is 27s. Then, the second duration corresponding to the tail speed range when it is less than or equal to the first slip speed threshold and greater than 0 is 6s.

[0129] However, in actual testing, the sum of the first and second durations of all driving speed segments may still be less than the total duration corresponding to the stationary slip condition. Since there is usually a transition period between two adjacent driving speed segments, this invention also needs to determine the preset duration before the initial moment of each driving speed segment based on the total duration corresponding to the stationary slip condition (equivalent to borrowing the preset duration during the transition period), and also use the preset duration before the initial moment of each driving speed segment as the duration corresponding to the stationary slip condition.

[0130] For example, the total duration of the stationary slippage condition can be subtracted from the sum of the first and second durations of all speed segments to obtain the duration difference. The quotient of this duration difference and the number of speed segments can then be used as a preset duration, which is evenly distributed before the initial time of each speed segment. For example, the preset duration before the initial time of each speed segment could be 3 seconds.

[0131] After each preset duration is determined, the original speed value within the preset duration range also needs to be assigned as the slippage speed threshold.

[0132] In another implementation, determining the slippage period within each driving speed segment based on a slippage speed threshold includes:

[0133] The duration of the initial period of each driving speed segment that is less than the target speed threshold is determined as the first duration, and the duration of the final period of each driving speed segment that is less than the target speed threshold is determined as the second duration.

[0134] The sum of the first duration corresponding to each driving speed segment, the second duration corresponding to each driving speed segment, and the preset duration before the initial moment of each driving speed segment is taken as the slippage period of each driving speed segment; wherein, there is a transition period between two adjacent driving speed segments.

[0135] For example, if the target speed threshold is 12 km / h, the duration corresponding to speeds less than 12 km / h at the beginning of a certain driving speed segment will be taken as the first duration.

[0136] Assuming that the speed at the beginning of the travel period is 1 km / h at 1 second, 2 km / h at 2 seconds, 4 km / h at 3 seconds, 6 km / h at 4 seconds, 9 km / h at 5 seconds, 11 km / h at 6 seconds, and 12 km / h at 7 seconds, then the first duration is 6 seconds.

[0137] After determining the slippage period, the original speed values ​​within the first duration, the second duration, and the preset duration before the initial moment of each speed segment need to be assigned as the slippage speed threshold.

[0138] In addition, this invention requires applying snow-covered road surface resistance in the target low-speed and target medium-speed driving segments of each test cycle; the target low-speed segment can be the second driving speed segment, and the target medium-speed segment can be the ninth driving speed segment. It is also necessary to determine the effective duration of the snow-covered road surface resistance. We can first determine it according to formula (9):

[0139] (9)

[0140] In formula (9), This represents the probability of a snowy road surface condition occurring.

[0141] The probability of a snow-covered road surface condition occurring can be determined using formula (10):

[0142] (10)

[0143] In formula (10), The ratio of the total duration of snowfall and subsequent snow retention to the number of snowfall hours (snowfall duration), for example, can be 1.2; The duration of snowfall on the day it snowed (in hours). This represents the total number of snowfall days in a year.

[0144] Assuming the probability of a snow-covered road surface condition occurring is 16%~17%, then the effective duration of the snow-covered road surface driving resistance is 288~306s. Excluding the slippage time in the second and ninth speed ranges, the remaining time in the second and ninth speed ranges requires the application of snow-covered road surface driving resistance.

[0145] The conventional low-temperature driving resistance is applied for the remainder of the remaining speed range. The conventional low-temperature driving resistance can be determined according to the above formula (5).

[0146] In this way, different resistances are determined for different driving times at different speeds in a test cycle, making the entire test conditions more closely resemble cold-weather scenarios, thereby improving the accuracy of the driving range.

[0147] During testing, the drum dynamometer control unit, controlled by the testing device, sends resistance commands to the drum dynamometer. Based on these commands, the drum dynamometer provides the required driving resistance to the vehicle under test at each speed range. The resistance command includes the required driving resistance for each speed range and the effective duration of the driving resistance at each speed range. Meanwhile, the settings for other test conditions during testing (such as the operation of the heating system and air conditioning) can refer to the testing standards. For example, it can be operated according to the test conditions specified in the test method standards for electric vehicle energy consumption and driving range, which will not be elaborated further here.

[0148] Within a single test cycle (1800s), the speed and resistance distribution for each driving speed segment of this invention can be referenced. Figure 3 As shown. In Figure 3 In the diagram, 31 represents the speed distribution for each speed range, 32 represents the driving resistance on snowy roads, 33 represents the commonly used low-temperature driving resistance, and 34 represents the slippage driving resistance.

[0149] The test vehicle, fully charged and immersed at the test temperature for 12 hours, was subjected to multiple test cycles at the speed and resistance conditions described above until the test termination condition was met. The test termination condition could be that the battery charge of the test vehicle degraded to the point that the real-time wheel-end speed was 2 km / h lower than the set speed value.

[0150] During the test, the testing device can acquire the mileage and energy change of the vehicle under test in each test cycle. The mileage in each test cycle can be calculated by the testing device itself or sent to the testing device by a dynamometer. The energy change in each test cycle is determined by the energy consumption acquisition and processing device, which can determine the energy change based on the acquired battery data, including the battery bus current and battery voltage.

[0151] In one implementation, obtaining the mileage for each test cycle includes:

[0152] Determine the slip duration for each speed segment in each test cycle, and determine the total slip duration for the test cycle based on the slip duration for each speed segment.

[0153] The actual driving time is determined based on the duration of each test cycle and the total slippage duration; the actual driving time is the difference between the duration of each test cycle and the total slippage duration.

[0154] The speed is integrated over the actual driving time to obtain the driving distance for each test cycle.

[0155] In other words, since skidding in place does not change the distance during actual driving, in order to improve the accuracy of determining the driving mileage, the speed value during the skidding period is not included in the speed integration operation. Therefore, the determined driving mileage will be more accurate and more in line with the actual situation in cold regions.

[0156] S213, based on the mileage of the vehicle under test in each test cycle and the change in electrical energy of the vehicle under test in each test cycle.

[0157] In one implementation, the actual driving range of the vehicle under test is determined based on the mileage traveled by the vehicle under test in each test cycle and the change in the vehicle's electrical energy in each test cycle, including:

[0158] According to the formula Determine the first Energy consumption per test cycle ;

[0159] According to the formula Determine the energy consumption of all test cycles. ;

[0160] According to the formula Determine the actual driving range of the vehicle under test ;in,

[0161] For the first The mileage of the vehicle under test in each test cycle. For the first The change in electrical energy of the vehicle under test in one test cycle, in watt-hours; To test the total number of loops, For the first Weighting coefficients for each test loop To measure the change in electrical energy of the vehicle under test before and after testing.

[0162] Among them, the The change in electrical energy in the first test cycle can be determined according to the first... The battery data for each test cycle was determined as follows:

[0163] According to the formula Determine the first The change in electrical energy of each battery cell;

[0164] According to the formula Determine the first Change in electrical energy over one test cycle .

[0165] in, For the first In the nth test loop The voltage of each battery cell For the first In the nth test loop The current of each battery cell For the first The start time of each test loop, For the first The end time of each test loop.

[0166] This determines the actual driving range of the vehicle under test in cold-region scenarios.

[0167] As can be seen, this invention determines the test temperature, driving speed range, and driving resistance that are suitable for cold-region scenarios based on their characteristics, providing test conditions that are more in line with the actual environment. It comprehensively and accurately simulates and adapts to the actual driving scenarios in cold regions, thereby effectively improving the accuracy of the driving range test in cold-region scenarios. Furthermore, this invention uses a temperature chamber to provide the test temperature and a dynamometer to provide the required driving resistance, thus enabling repeatable tests and further improving the accuracy of the test.

[0168] Based on the same inventive concept as in the foregoing embodiments, the present invention also provides a testing device for the cold-weather driving range of electric vehicles, such as... Figure 4 As shown, the device includes:

[0169] Adjustment unit 41 is used to adjust the temperature inside the temperature chamber to the test temperature when the vehicle under test is placed inside the temperature chamber.

[0170] Acquisition unit 42 is used to acquire the driving speed range corresponding to the cold region scenario and the driving resistance corresponding to the working condition type of the cold region scenario;

[0171] Test unit 43 is used to perform cyclic testing on the vehicle under test based on the driving speed range corresponding to the cold region scenario and the driving resistance corresponding to the cold region scenario working condition type at the test temperature, and to obtain the driving mileage of the vehicle under test and the change in electrical energy of the vehicle under test in each test cycle.

[0172] The determining unit 44 is used to determine the actual driving range of the vehicle under test based on the driving mileage of the vehicle under test in each test cycle and the change in electrical energy of the vehicle under test in each test cycle.

[0173] Since the apparatus described in the embodiments of this invention is used to implement the method for extending the driving range of electric vehicles in cold regions according to the embodiments of this invention, those skilled in the art can understand the specific structure and variations of the apparatus based on the method described in the embodiments of this invention, and therefore will not be described in detail here. All apparatuses used in the methods of the embodiments of this invention fall within the scope of protection of this invention.

[0174] Through one or more embodiments of the present invention, the present invention has the following beneficial effects or advantages:

[0175] This invention provides a method, apparatus, and system for testing the cold-weather driving range of electric vehicles. The method includes: placing the vehicle under test in a temperature chamber and adjusting the temperature of the chamber to the test temperature; obtaining the driving speed range corresponding to the cold-weather scenario and the driving resistance corresponding to the cold-weather scenario operating condition type; performing a cyclic test on the vehicle under test based on the driving speed range and driving resistance corresponding to the cold-weather scenario operating condition type at the test temperature; after the test, obtaining the driving mileage and energy change of the vehicle under test in each test cycle; determining the actual driving range of the vehicle under test based on the driving mileage and energy change of the vehicle under test in each test cycle. Thus, based on the characteristics of the cold-weather scenario, a test temperature, driving speed range, and driving resistance suitable for the cold-weather scenario are determined, providing test conditions that are more closely aligned with the actual environment. This comprehensively and accurately simulates and adapts to the actual driving scenario in cold-weather conditions, thereby effectively improving the accuracy of the driving range test in cold-weather scenarios. Furthermore, this invention utilizes a temperature chamber to provide the test temperature, allowing for repeated testing and further improving the accuracy of the test.

[0176] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0177] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for testing the cold-weather driving range of an electric vehicle, characterized in that, The method includes: When the fully charged vehicle under test is placed in the temperature chamber, the temperature inside the chamber is adjusted to the test temperature; the test temperature is the test temperature corresponding to a cold-region scenario, and the test temperature is greater than -19°C. And less than -7 ; Obtain the driving speed range corresponding to the cold region scenario and the driving resistance corresponding to the working condition type of the cold region scenario; At the test temperature, the vehicle under test is subjected to cyclic testing based on the driving speed range corresponding to the cold region scenario and the driving resistance corresponding to the cold region scenario working condition type. After the test, the driving mileage of the vehicle under test and the change in electrical energy of the vehicle under test in each test cycle are obtained. The actual driving range of the vehicle under test is determined based on the mileage traveled by the vehicle under test in each test cycle and the change in the vehicle's electrical energy in each test cycle; wherein, The acquisition of the driving speed range corresponding to the cold region scenario includes: Obtain the first M driving speed segments in the test standard, where M is 10; one test cycle in the test standard contains 3 speed ranges, namely low speed range, medium speed range and high speed range; the low speed range contains 7 driving speed segments, the medium speed range contains 3 driving speed segments, and the high speed range contains 1 driving speed segment. The 8th driving speed segment, the 8-second idle segment, and the 10th driving speed segment from the first 10 driving speed segments are combined to obtain a combined driving speed segment. The combined driving speed segment replaces the 11th driving speed segment in the test standard. Finally, the combined driving speed segment is combined with the first 10 driving speed segments to obtain a driving speed segment that conforms to the cold-region scenario. The cyclic testing of the vehicle under test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating condition type includes: Determine the slip speed threshold corresponding to the stationary slip condition, and determine the slip period in each driving speed segment based on the slip speed threshold; during the cyclic test, apply slip driving resistance to the vehicle under test during the slip period of each driving speed segment. During the non-slipping periods in the target low-speed and target medium-speed segments of the driving speed range corresponding to the cold-region scenario, apply the snow-covered road surface driving resistance to the vehicle under test. During the remaining time period within the remaining driving speed range, apply low-temperature driving resistance to the vehicle under test until the test termination condition is met.

2. The method as described in claim 1, characterized in that, The method of obtaining the driving resistance corresponding to the cold-region scenario operating condition type includes: When the operating condition is a slipping condition, according to the formula Determine the slip resistance corresponding to the stationary slip condition. ; Among them, the The coefficient of friction for sliding on hard snow is... The mass of the vehicle under test, the This is the gravity coefficient.

3. The method as described in claim 1, characterized in that, The method of obtaining the driving resistance corresponding to the cold-region scenario operating condition type includes: When the working condition is a snow-covered road surface, according to the formula... Determine the driving resistance on the snow-covered road surface corresponding to the snow-covered road surface condition. ; Among them, the The mass of the vehicle under test, the The rolling resistance coefficient of the snow-covered road surface is... The width of the vehicle under test, the The height of the vehicle to be measured, The acceleration of the vehicle under test, the The speed of the vehicle under test is denoted as .

4. The method as described in claim 1, characterized in that, Determining the slip speed threshold corresponding to the in-situ slip condition includes: According to the formula Determine the slippage speed threshold ;in, The The relative speed between the vehicle and the road surface during acceleration and skidding in place, the The probability of slipping during acceleration in place, the To determine the probability of skidding during rapid acceleration, the following... The relative speed between the vehicle under test and the road surface during rapid acceleration and skidding.

5. The method as described in claim 1, characterized in that, The step of determining the slippage period in each driving speed segment based on the slippage speed threshold includes: The speed values ​​in the head speed range of each driving speed segment that are less than the target speed threshold are assigned as the slip speed threshold, and the speed values ​​in the tail speed range of each driving speed segment that are less than the target speed threshold are assigned as the slip speed threshold; the target speed threshold is preset; the head speed range is the speed range corresponding to the beginning period of the driving speed segment, and the tail speed range is the speed range corresponding to the end period of the driving speed segment; Determine the first duration from the initial acceleration to the speed reaching the last slip speed threshold in the head speed range of each driving speed segment, and determine the second duration corresponding to the tail speed range of each driving speed segment that is greater than 0 and less than or equal to the first slip speed threshold. The sum of the first duration corresponding to each driving speed segment, the second duration corresponding to each driving speed segment, and the preset duration before the initial moment of each driving speed segment is taken as the slippage period of each driving speed segment; wherein, there is a transition period between two adjacent driving speed segments.

6. The method as described in claim 1, characterized in that, The process of obtaining the mileage of the vehicle under test in each test cycle includes: Determine the slippage period for each speed segment in each test cycle, and determine the total slippage period in the test cycle based on the slippage period for each speed segment; The actual driving time period is determined based on the time period corresponding to each test cycle and the total slippage time period; The speed is integrated based on the actual driving time period to obtain the driving distance for each test cycle.

7. A testing device for the cold-weather driving range of electric vehicles, characterized in that, The device includes: The adjustment unit is used to adjust the temperature inside the temperature chamber to the test temperature when the fully charged vehicle under test is placed inside the temperature chamber; the test temperature is the test temperature corresponding to a cold-region scenario, and the test temperature is greater than -19°C. And less than -7 ; The acquisition unit is used to acquire the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the working condition type of the cold-region scenario. The testing unit is used to perform cyclic testing on the vehicle under test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario working condition type at the test temperature. After the test, the unit obtains the driving mileage of the vehicle under test and the change in electrical energy of the vehicle under test in each test cycle. The determining unit is used to determine the actual driving range of the vehicle under test based on the mileage traveled by the vehicle under test in each test cycle and the change in electrical energy of the vehicle under test in each test cycle; wherein, The acquisition of the driving speed range corresponding to the cold region scenario includes: Obtain the first M driving speed segments in the test standard, where M is 10; one test cycle in the test standard contains 3 speed ranges, namely low speed range, medium speed range and high speed range; the low speed range contains 7 driving speed segments, the medium speed range contains 3 driving speed segments, and the high speed range contains 1 driving speed segment. The 8th driving speed segment, the 8-second idle segment, and the 10th driving speed segment from the first 10 driving speed segments are combined to obtain a combined driving speed segment. The combined driving speed segment replaces the 11th driving speed segment in the test standard. Finally, the combined driving speed segment is combined with the first 10 driving speed segments to obtain a driving speed segment that conforms to the cold-region scenario. The cyclic testing of the vehicle under test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating condition type includes: Determine the slip speed threshold corresponding to the stationary slip condition, and determine the slip period in each driving speed segment based on the slip speed threshold; during the cyclic test, apply slip driving resistance to the vehicle under test during the slip period of each driving speed segment. During the non-slipping periods in the target low-speed and target medium-speed segments of the driving speed range corresponding to the cold-region scenario, apply the snow-covered road surface driving resistance to the vehicle under test. During the remaining time period within the remaining driving speed range, apply low-temperature driving resistance to the vehicle under test until the test termination condition is met.

8. A testing system for the cold-weather driving range of electric vehicles, characterized in that, The system includes: a temperature chamber, a temperature regulating device, a drum dynamometer, a drum dynamometer control device, an energy consumption acquisition and processing device, and the testing device as described in claim 7; wherein the temperature regulating device, the drum dynamometer control device, and the energy consumption acquisition and processing device are electrically connected to the testing device. The temperature chamber is used to house the vehicle to be tested; The temperature regulation device, controlled by the testing device, is used to adjust the temperature inside the temperature chamber to the testing temperature; the testing temperature is the testing temperature corresponding to a cold-region scenario, and the testing temperature is greater than -19°C. And less than -7 ; The rotary drum dynamometer control device, controlled by the testing device, is used to control the rotary drum dynamometer to provide the driving resistance required by the vehicle under test; The energy consumption acquisition and processing device, controlled by the testing device, is used to determine the change in electrical energy of the vehicle under test. The testing device is used to adjust the temperature inside a temperature chamber to the test temperature when a fully charged vehicle under test is placed inside the chamber; to acquire the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating condition type; to perform cyclic testing on the vehicle under test based on the driving speed range and driving resistance corresponding to the cold-region scenario operating condition type at the test temperature; after the test, to acquire the mileage and energy change of the vehicle under test in each test cycle; and to determine the actual driving range of the vehicle under test based on the mileage and energy change of the vehicle under test in each test cycle. The acquisition of the driving speed range corresponding to the cold region scenario includes: Obtain the first M driving speed segments in the test standard, where M is 10; one test cycle in the test standard contains 3 speed ranges, namely low speed range, medium speed range and high speed range; the low speed range contains 7 driving speed segments, the medium speed range contains 3 driving speed segments, and the high speed range contains 1 driving speed segment. The 8th driving speed segment, the 8-second idle segment, and the 10th driving speed segment from the first 10 driving speed segments are combined to obtain a combined driving speed segment. The combined driving speed segment replaces the 11th driving speed segment in the test standard. Finally, the combined driving speed segment is combined with the first 10 driving speed segments to obtain a driving speed segment that conforms to the cold-region scenario. The cyclic testing of the vehicle under test based on the driving speed range corresponding to the cold-region scenario and the driving resistance corresponding to the cold-region scenario operating condition type includes: Determine the slip speed threshold corresponding to the stationary slip condition, and determine the slip period in each driving speed segment based on the slip speed threshold; during the cyclic test, apply slip driving resistance to the vehicle under test during the slip period of each driving speed segment. During the non-slipping periods in the target low-speed and target medium-speed segments of the driving speed range corresponding to the cold-region scenario, apply the snow-covered road surface driving resistance to the vehicle under test. During the remaining time period within the remaining driving speed range, apply low-temperature driving resistance to the vehicle under test until the test termination condition is met.

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