Vehicle torque estimation method, system, vehicle and storage medium

Abstract

The present application discloses a vehicle torque estimation method, system, vehicle and storage medium, belonging to the field of vehicle technology. The present application obtains the permitted total driving power that the power battery can provide to the drive motor, the permitted driving power of each drive motor, the permitted torque of each drive motor, the whole vehicle torque of the vehicle and the current vehicle speed, wherein the current vehicle speed is one of the real-time vehicle speed and the reference vehicle speed; based on the permitted total driving power, the permitted driving power of each drive motor, the permitted torque of each drive motor and the current vehicle speed, the whole vehicle torque is limited according to the power consumption minimization logic to obtain the whole vehicle torque limit value of the vehicle, that is, the present application selects the real-time vehicle speed or the reference vehicle speed as the current vehicle speed, realizes the correction of the estimation of the whole vehicle torque limit value of the vehicle under unstable driving conditions, and improves the accuracy of the estimation of the whole vehicle torque limit value of the vehicle.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to a vehicle torque estimation method, system, vehicle and storage medium. Background Art

[0002] In the prior art, the estimation of the vehicle's whole vehicle torque limit value directly affects the size of the final torque output value of each drive motor. When the vehicle's whole vehicle torque limit value is estimated to be too large, the total driving power of the vehicle will exceed the permitted total driving power. When the vehicle's whole vehicle torque limit value is estimated to be too small, it will affect the power demand for vehicle driving. Therefore, the estimation of the vehicle's whole vehicle torque limit value has a great impact on maintaining the balance between the torque economic output and the vehicle's driving power demand. That is, how to improve the estimation accuracy of the vehicle's whole vehicle torque limit is a problem that needs to be solved.

[0003] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0004] The main purpose of the present application is to provide a vehicle torque estimation method, system, vehicle and storage medium, aiming to solve the technical problem that the prior art cannot accurately estimate the vehicle's entire vehicle torque limit value.

[0005] To achieve the above object, the present application provides a vehicle torque estimation method, which is applied to a vehicle including a power battery and at least two drive motors. The vehicle torque estimation method includes the following steps:

[0006] Obtaining the permitted total driving power that the power battery can provide to the driving motor, the permitted driving power of each driving motor, the permitted torque of each driving motor, the whole vehicle torque of the vehicle, and the current vehicle speed, wherein the current vehicle speed is one of a real-time vehicle speed and a reference vehicle speed;

[0007] Based on the permitted total drive power, the permitted drive power of each drive motor, the permitted torque of each drive motor and the current vehicle speed, the vehicle torque is limited according to the power consumption minimization logic to obtain the vehicle torque limit value.

[0008] Optionally, the step of limiting the vehicle torque according to the power consumption minimization logic based on the permitted total drive power, the permitted drive power of each drive motor, the permitted torque of each drive motor and the current vehicle speed to obtain the vehicle torque limit value of the vehicle includes:

[0009] Determining the speed corresponding to each drive motor based on the current vehicle speed;

[0010] Based on the permitted total drive power and the speeds corresponding to the drive motors, a preset third MAP table is queried to determine a first torque limit value corresponding to each drive motor, wherein the first torque limit value is used to characterize the output permitted torque corresponding to the drive motor under the limitation of the power battery capacity, and the third MAP table is used to characterize the mapping relationship between the permitted total drive power-the speeds of each drive motor-the torque of each drive motor;

[0011] Determine a second torque limit value corresponding to each drive motor based on the permitted driving power of each drive motor and the permitted torque of each drive motor, wherein the second torque limit value is used to represent the output permitted torque corresponding to the drive motor under its own capacity limitation;

[0012] A vehicle torque limit value of the vehicle is determined based on the first torque limit value and the second torque limit value.

[0013] Optionally, the step of determining the vehicle torque limit value of the vehicle based on the first torque limit value and the second torque limit value comprises:

[0014] Comparing the first torque limit value corresponding to each drive motor with the second torque limit value corresponding to the drive motor;

[0015] In the case of output torque, the smallest of the first torque limit value and the second torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor;

[0016] In the case of torque recovery, the maximum of the first torque limit value and the second torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor;

[0017] The sum of the torque limit values ​​corresponding to the drive motors is calculated as the vehicle torque limit value of the vehicle.

[0018] Optionally, the step of obtaining the current vehicle speed includes:

[0019] When the vehicle is in a stable driving condition, obtaining the real-time vehicle speed of the vehicle as the current vehicle speed;

[0020] When the vehicle is in an unstable driving condition, a reference vehicle speed corresponding to the vehicle is obtained as the current vehicle speed.

[0021] Optionally, before the step of obtaining the real-time speed of the vehicle as the current speed when the vehicle is in a stable driving condition, the method further includes:

[0022] Obtaining the front drive motor speed, the rear drive motor speed, the speed change rate of the front drive motor and the speed change rate of the rear drive motor;

[0023] If the difference between the front drive motor speed and the rear drive motor speed is greater than a first preset threshold, or the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor is greater than a second preset threshold, the vehicle is in an unstable driving condition.

[0024] Optionally, the step of obtaining a reference vehicle speed corresponding to the vehicle as the current vehicle speed includes:

[0025] A reference vehicle speed corresponding to the vehicle is determined based on a maximum value of the front drive motor speed and the rear drive motor speed.

[0026] Optionally, the step of obtaining a reference speed corresponding to the vehicle as the current speed further includes:

[0027] The reference vehicle speed is corrected based on the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor, and the corrected reference vehicle speed is used as the current vehicle speed.

[0028] In addition, to achieve the above purpose, the present application also provides a vehicle torque estimation system, the vehicle torque estimation system comprising:

[0029] an energy management module, used to obtain the permitted total driving power that the power battery can provide to the driving motor, the permitted driving power of each driving motor, the permitted torque of each driving motor, the whole vehicle torque of the vehicle, and the current vehicle speed, wherein the current vehicle speed is one of a real-time vehicle speed and a reference vehicle speed;

[0030] The torque limiting module is used to limit the vehicle torque based on the permitted total driving power, the permitted driving power of each driving motor, the permitted torque of each driving motor and the current vehicle speed according to the power consumption minimization logic to obtain the vehicle torque limit value of the vehicle.

[0031] In addition, to achieve the above-mentioned objectives, the present application also provides a vehicle, which includes a power battery, at least two drive motors and the vehicle torque estimation system as described above.

[0032] In addition, to achieve the above-mentioned purpose, the present application also provides a storage medium, on which a vehicle torque estimation program is stored. When the vehicle torque estimation program is executed by a processor, the steps of the vehicle torque estimation method as described above are implemented.

[0033] The present application discloses a vehicle torque estimation method, system, vehicle and storage medium. Compared with the prior art that cannot accurately estimate the vehicle's whole vehicle torque limit value, the present application obtains the permitted total driving power that the power battery can provide to the drive motor, the permitted driving power of each drive motor, the permitted torque of each drive motor, the whole vehicle torque of the vehicle and the current vehicle speed, wherein the current vehicle speed is one of the real-time vehicle speed and the reference vehicle speed; based on the permitted total driving power, the permitted driving power of each drive motor, the permitted torque of each drive motor and the current vehicle speed, the whole vehicle torque is limited in accordance with the power consumption minimization logic to obtain the whole vehicle torque limit value of the vehicle, that is, the present application selects the real-time vehicle speed or the reference vehicle speed as the current vehicle speed, thereby realizing the correction of the estimation of the vehicle's whole vehicle torque limit value under unstable driving conditions, thereby improving the accuracy of the estimation of the vehicle's whole vehicle torque limit value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0035] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0036] Figure 1 This is a flow chart of a first embodiment of a vehicle torque estimation method of the present application;

[0037] Figure 2 This is the third MAP table for this application;

[0038] Figure 3 A schematic flow chart of a vehicle torque control method of the present application;

[0039] Figure 4 This is the second MAP table for this application;

[0040] Figure 5 This is the first MAP table of this application;

[0041] Figure 6 This is a schematic diagram of the process of making the MAP table for this application;

[0042] Figure 7 This is a schematic diagram of the functional modules of the first embodiment of the vehicle torque estimation system of the present application.

[0043] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0044] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0045] The present application embodiment provides a vehicle torque estimation method, referring to Figure 1 , Figure 1 This is a flow chart of the first embodiment of the vehicle torque estimation method of the present application.

[0046] In this embodiment, the vehicle torque estimation method includes:

[0047] Step S10, obtaining the permitted total driving power that the power battery can provide to the driving motor, the permitted driving power of each driving motor, the permitted torque of each driving motor, the whole vehicle torque of the vehicle and the current vehicle speed, wherein the current vehicle speed is one of the real-time vehicle speed and the reference vehicle speed.

[0048] The total permissible driving power that the power battery can provide to the driving motor is the sum of the permissible driving powers of the driving motors.

[0049] Among them, the vehicle's whole vehicle torque refers to the sum of the torques output by its various drive motors during the vehicle's driving process. The torques output by each drive motor act on each wheel end of the vehicle. Therefore, the vehicle's whole vehicle demand torque can also refer to the sum of the torques required by its various wheel ends during the vehicle's driving process. The torques and sums of the torques required by each wheel end of the vehicle are different under different driving states and under different driving road conditions. Therefore, the vehicle's current whole vehicle demand torque can be determined based on the vehicle's driving state information and driving road condition information. The vehicle's driving state information includes, but is not limited to, the vehicle's driving speed, the depth of the brake pedal, the opening and closing of the accelerator pedal, the steering angle of each wheel of the vehicle, etc. The vehicle's driving road condition information includes, but is not limited to, the type of road surface the vehicle is currently on (e.g., asphalt road, muddy ground, mountain road, etc.), weather information (e.g., slippery, snowy, icy, etc.), congestion, etc.

[0050] Step S20: Based on the permitted total driving power, the permitted driving power of each driving motor, the permitted torque of each driving motor and the current vehicle speed, the whole vehicle torque is limited according to the power consumption minimization logic to obtain the whole vehicle torque limit value of the vehicle.

[0051] Specifically, the above step S20 includes:

[0052] Step S21: determining the rotation speed corresponding to each drive motor based on the current vehicle speed.

[0053] Specifically, the rotation speed corresponding to each drive motor is calculated based on the current vehicle speed and the wheel rolling radius.

[0054] Step S22, based on the permitted total drive power and the speed corresponding to each drive motor, query the preset third MAP table to determine the first torque limit value corresponding to each drive motor, wherein the first torque limit value is used to characterize the output permitted torque corresponding to the drive motor under the limitation of the power battery capacity, and the third MAP table is used to characterize the mapping relationship between the permitted total drive power-the speed of each drive motor-the torque of each drive motor.

[0055] Among them, the preset third MAP table can refer to Figure 2 , Figure 2 The third MAP table of the present application has a horizontal axis representing the rotation speed of each drive motor and a vertical axis representing the torque of each drive motor. That is, based on the permitted total drive power and the rotation speed corresponding to each drive motor, the process of querying the preset third MAP table to determine the first torque limit value corresponding to each drive motor may be as follows: based on the permitted total drive power and the rotation speed corresponding to each drive motor, determining the torque corresponding to each drive motor under the permitted total drive power, querying the third MAP table according to the rotation speed and torque corresponding to each drive motor to obtain the motor efficiency corresponding to each drive motor, and determining the first torque limit value corresponding to each drive motor based on the motor efficiency corresponding to each drive motor obtained from the query and the permitted torque of each drive motor.

[0056] The process of making the preset third MAP table can refer to Figure 6 , Figure 6 This is a schematic diagram of the process of making the MAP table for this application.

[0057] The process of making the preset third MAP table includes:

[0058] 1) The efficiency MAP table of each drive motor under different voltages is obtained through the motor bench test, where the horizontal axis is the speed of each drive motor and the vertical axis is the torque of each drive motor. Under different voltages, the motor efficiency corresponding to different speeds and torques is tested;

[0059] 2) Correct the motor efficiency corresponding to zero torque at different speeds in the efficiency MAP table. Considering that there may be large deviations in the experimental values ​​near the zero torque point, the torque coordinate point at this point is eliminated. For the zero torque point itself, there is no driving efficiency. In order to transition between positive and negative torques, and considering that the driving torque is used more frequently than the recovery torque, the motor efficiency corresponding to the adjacent effective positive torque is used to fill it. In addition, the efficiency is inaccurate within the range of the precision torque at the motor end (such as ±3nm, basically around 30nm to the shaft end), and this area needs to be avoided. For example, it is more reasonable to use the test data starting from 50nm, and the efficiency is obtained through linear difference in the lower torque area under control;

[0060] Considering that all the electric power is used for heat generation at the zero speed point, a separate replacement strategy is generally used in actual use (for example, when the vehicle starts, it is allowed to output at the maximum capacity after combining the battery and motor capabilities, so the third MAP table is designed not to list the zero speed point separately, that is, from the perspective of the table, the efficiency calculation is performed at the low speed point by default when the point is close to 0);

[0061] 3) Fill the NAN data in the efficiency MAP table to obtain a complete third MAP table. Since some data points are beyond the power range and have NAN data, the NAN data at the upper and lower ends are replaced with the efficiency of the adjacent longitudinal direction (when the efficiency data value is equal to NAN, the power has reached the upper limit, the torque cannot continue to increase, and the efficiency remains unchanged) to obtain a complete third MAP table.

[0062] Step S23: determining a second torque limit value corresponding to each drive motor based on the permitted driving power of each drive motor and the permitted torque of each drive motor, wherein the second torque limit value is used to characterize the output permitted torque corresponding to the drive motor under its own capacity limitation.

[0063] Specifically, the permissible torque of the drive motor is usually the permissible torque of the drive motor shaft end. Since a reducer is provided between the drive motor and the wheel, the permissible torque of the drive motor can be converted into the second torque limit value corresponding to the drive motor based on the reduction ratio of the reducer and the conversion loss of the permissible drive power of the drive motor to the mechanical power. The conversion loss of the permissible drive power of the drive motor to the mechanical power can be estimated based on the bus voltage, temperature and rotation speed of the drive motor.

[0064] It should be noted that the estimation of the conversion loss from the permissible driving power of the driving motor to the mechanical power may be carried out in any appropriate manner commonly used in the art, which will not be described in detail in the embodiments of the present application.

[0065] Step S24: Determine a vehicle torque limit value of the vehicle based on the first torque limit value and the second torque limit value.

[0066] Specifically, the above step S24 may include:

[0067] Step a1: compare the first torque limit value corresponding to each drive motor with its corresponding second torque limit value.

[0068] Step a2: In the case of output torque, the smallest of the first torque limit value and the second torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor.

[0069] Specifically, if the first torque limit value corresponding to each drive motor is less than or equal to its corresponding second torque limit value, the first torque limit value corresponding to each drive motor is used as the torque limit value corresponding to each drive motor; if the first torque limit value corresponding to each drive motor is greater than its corresponding second torque limit value, the second torque limit value corresponding to each drive motor is used as the torque limit value corresponding to each drive motor.

[0070] Step a3: In the case of torque recovery, the maximum value of the first torque limit value and the second torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor.

[0071] Specifically, if the first torque limit value corresponding to each drive motor is less than its corresponding second torque limit value, the second torque limit value corresponding to each drive motor is used as the torque limit value corresponding to each drive motor; if the first torque limit value corresponding to each drive motor is greater than or equal to its corresponding second torque limit value, the first torque limit value corresponding to each drive motor is used as the torque limit value corresponding to each drive motor.

[0072] Step a4, comparing the torque limit values ​​corresponding to each drive motor, if the difference between the torque limit values ​​corresponding to each drive motor is greater than a preset difference threshold, performing torque transfer on the torque limit values ​​corresponding to each drive motor to obtain the torque limit values ​​corresponding to each drive motor after the torque transfer.

[0073] Specifically, in the present embodiment, the number of drive motors is 2, namely, the first drive motor and the second drive motor, and the difference between the torque limit value corresponding to the first drive motor and the torque limit value corresponding to the second drive motor is calculated. If the torque limit value corresponding to the first drive motor is greater than the torque limit value corresponding to the second drive motor, and the difference value is greater than the first preset difference threshold, the torque limit value corresponding to the first drive motor is subjected to a torque transfer operation, that is, the reduction amount of the torque limit value corresponding to the first drive motor is equal to the increase amount of the torque limit value corresponding to the second drive motor, so that the difference between the torque limit value corresponding to the first drive motor after the torque transfer and the torque limit value corresponding to the second drive motor after the torque transfer is less than the second preset difference threshold. It should be noted that the first preset difference threshold and the second preset difference threshold can be set according to actual needs, and the first preset difference threshold is greater than the second preset difference threshold.

[0074] Step a5: Calculate the sum of the torque limit values ​​corresponding to each drive motor after the torque transfer as the vehicle torque limit value of the vehicle.

[0075] Furthermore, in this embodiment, the step of obtaining the current vehicle speed includes:

[0076] Step A1, obtaining the front drive motor speed, the rear drive motor speed, the speed change rate of the front drive motor and the speed change rate of the rear drive motor;

[0077] Step A2: If the difference between the speed of the front drive motor and the speed of the rear drive motor is greater than a first preset threshold, or the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor is greater than a second preset threshold, the vehicle is in an unstable driving condition; otherwise, the vehicle is in a stable driving condition;

[0078] Step A3: when the vehicle is in a stable driving condition, obtaining the real-time speed of the vehicle as the current speed;

[0079] Step A4: When the vehicle is in an unstable driving condition, a reference vehicle speed corresponding to the vehicle is obtained as the current vehicle speed.

[0080] It should be noted that the first preset threshold and the second preset threshold in step A2 can be set according to actual needs and are not specifically limited in this embodiment.

[0081] Specifically, the step of obtaining the reference speed corresponding to the vehicle as the current speed may include:

[0082] Step A41: Determine a reference speed corresponding to the vehicle based on the maximum value of the front drive motor speed and the rear drive motor speed.

[0083] In this embodiment, the wheel speeds corresponding to the four wheels of the vehicle are calculated according to the front drive motor speed, the rear drive motor speed and the wheel rolling radius of the vehicle, and the maximum value thereof is taken as the reference speed corresponding to the vehicle.

[0084] Step A42: Based on the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor, the reference vehicle speed is corrected, and the corrected reference vehicle speed is used as the current vehicle speed.

[0085] In this embodiment, the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor is proportional to the reference vehicle speed. The larger the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor, the higher the corrected reference vehicle speed.

[0086] Furthermore, in the present embodiment, when the driving condition of the vehicle enters a stable state from an unstable state, or vice versa, there is a gap between the reference vehicle speed and the real-time vehicle speed, and a smooth transition between the reference vehicle speed and the real-time vehicle speed cannot be achieved. At this time, the reference vehicle speed and the real-time vehicle speed can be connected with a filtering slope to ensure a smooth transition between the reference vehicle speed and the real-time vehicle speed.

[0087] In this embodiment, the estimation of the vehicle's whole vehicle torque limit value directly affects the size of the final torque output value of each drive motor. When the vehicle's whole vehicle torque limit value is estimated to be too large, the total driving power of the vehicle will exceed the permitted total driving power. When the vehicle's whole vehicle torque limit value is estimated to be too small, it will affect the power demand for vehicle driving. In this embodiment, through the change of stable and unstable driving conditions, the real-time vehicle speed or the reference vehicle speed is selected as the current vehicle speed, and the estimation of the vehicle's whole vehicle torque limit value is corrected under unstable driving conditions, thereby improving the accuracy of the estimation of the vehicle's whole vehicle torque limit value, further ensuring that the torque economic distribution output is achieved while satisfying the power demand for vehicle driving to the greatest extent.

[0088] It should be noted that the steps of the vehicle torque estimation method in this embodiment can be applied to the vehicle torque control method.

[0089] refer to Figure 3 , Figure 3 The following is a flow chart of the vehicle torque control method of the present application. In the vehicle torque control method, based on the above vehicle torque estimation method, the following steps are also included:

[0090] Step S30: determining a target torque distribution coefficient based on the vehicle torque limit value and the current vehicle speed.

[0091] Specifically, the above step S30 may include:

[0092] Step S31: determining the rotation speed corresponding to each drive motor based on the current vehicle speed.

[0093] Specifically, the rotation speed corresponding to each drive motor is calculated based on the current vehicle speed and the wheel rolling radius.

[0094] Step S32, based on the vehicle torque limit value and the rotational speed corresponding to each drive motor, query a preset second MAP table to determine the torque distribution coefficient corresponding to each drive motor, wherein the second MAP table is used to characterize the mapping relationship between the torque corresponding to each drive motor-the rotational speed corresponding to each drive motor-the torque distribution coefficient.

[0095] Among them, the preset second MAP table can refer to Figure 4 , Figure 4 This is the second MAP table of the present application, the horizontal axis is the speed corresponding to each drive motor, and the vertical axis is the torque corresponding to each drive motor. In this embodiment, the vehicle's whole vehicle torque limit value is the sum of the torque limit values ​​corresponding to each drive motor after the torque transfer, that is, based on the whole vehicle torque limit value and the speed corresponding to each drive motor, querying the preset second MAP table to determine the torque distribution coefficient corresponding to each drive motor includes:

[0096] The torque limit value corresponding to each drive motor is determined based on the vehicle torque limit, and the second MAP table is looked up based on the torque limit value corresponding to each drive motor and the speed corresponding to each drive motor to determine the torque distribution coefficient corresponding to each drive motor.

[0097] The process of making the preset second MAP table can refer to Figure 6 , Figure 6 This is a schematic diagram of the process of making the MAP table for this application.

[0098] The process of making the preset second MAP table includes:

[0099] 1) Obtain the power external characteristic data and torque external characteristic data of each drive motor through motor bench test;

[0100] 2) Based on the efficiency MAP table obtained by correcting the motor efficiency corresponding to zero torque at different speeds in the efficiency MAP table through the steps in the process of making the third MAP table, the MAP table of each drive motor is calculated respectively (the horizontal axis in the table is the speed of each drive motor, and the vertical axis is the torque of each drive motor), wherein the MAP table of each drive motor needs to meet the principle that the electric power is divided by the efficiency when the mechanical power is reversed during discharge, and the electric power is multiplied by the efficiency when the mechanical power is reversed during charging; and the NAN data in the MAP table is filled (using the adjacent longitudinal power for filling, or using the corresponding power external characteristic value at the same speed for filling), to obtain a complete MAP table;

[0101] 3) setting the total torque value, traversing the distribution coefficients, and obtaining the power of each drive motor under each distribution coefficient through the MAP table difference in step 2), wherein after distributing the torque of each drive motor based on the distribution coefficient, if the torque of one of the drive motors after distribution exceeds the torque external characteristic of the drive motor, the distribution coefficient is used by default, and NAN is used as the power of each drive motor under the distribution coefficient; otherwise, the sum of the powers of each drive motor under the distribution coefficient is obtained based on the MAP table interpolation of each drive motor;

[0102] 4) Obtain the minimum MAP table corresponding to each total torque value and speed, where if the distribution coefficient is set with low accuracy, the boundary torque value always has a single drive motor torque exceeding the torque external characteristic, and the minimum power has NAN;

[0103] 5) Obtain a distribution coefficient table corresponding to the minimum MAP table corresponding to each total torque value and speed, and fill in the NAN data, zero speed point and zero torque point in the distribution coefficient table to obtain a complete second MAP table.

[0104] Among them, near zero torque, if the negative torque area is 1, it is replaced by the distribution coefficient 0, and the positive torque area is replaced by the distribution coefficient 1+. The purpose of this treatment is to avoid the local point distribution coefficient jumping between 0 and 1, so that it presents a continuous distribution change, so as to help achieve the continuous transfer change of torque.

[0105] The distribution coefficient NAN is filled. The main reason for the appearance of the NAN area is that there will always be a single torque exceeding the limit of the two motors according to the distribution coefficient. This is related to the accuracy of the traversed distribution coefficient, and may not match the external characteristic torque ratio of the two motors. However, it can be processed through NAN filling later, that is, the distribution coefficient at the maximum torque achievable at a uniform speed is used as the filling coefficient of the NAN area (that is, the distribution coefficient obtained by the external characteristic torque ratio is used for filling), where the zero torque point coefficient is filled according to the positive torque (the driving back to zero condition is more common than the recovery condition), and the zero speed point is defaulted to be consistent with the adjacent low speed (such as 50rpm) to avoid transitional changes in the distribution coefficient at low speed (the zero speed point is not reflected in the table, and the actual search defaults to the value at 50rpm).

[0106] More specifically, after obtaining the vehicle torque limit value, the vehicle torque limit value is subjected to wheel-end basic filtering, and the target torque distribution coefficient corresponding to the vehicle in economic mode is determined by combining the filtered vehicle torque limit value, the corresponding speed of each drive motor and the preset second MAP table.

[0107] Step S40: determining the expected torque corresponding to each drive motor based on the vehicle torque limit value and the target torque distribution coefficient.

[0108] Among them, the target torque distribution coefficient includes multiple ones, that is, each drive motor has a corresponding target torque distribution coefficient, and the target torque distribution coefficient corresponding to each drive motor is multiplied by the vehicle torque limit value, and the obtained value is the expected torque corresponding to each drive motor.

[0109] Step S50: Determine the expected total power of the vehicle based on the expected torque corresponding to each drive motor and the rotation speed of each drive motor.

[0110] Specifically, based on the calculation formula of power=n×rotation speed×expected torque, the expected power corresponding to each drive motor is calculated, and the expected total power of the vehicle can be obtained by adding the expected power corresponding to each drive motor.

[0111] Furthermore, the expected torque corresponding to each driving motor in step S50 is a filtered expected torque obtained after filtering.

[0112] Step S60: Compare the expected total power with the permitted total driving power, and select a corresponding distribution strategy to distribute torque to each driving motor according to the comparison result.

[0113] Specifically, step S60 may include:

[0114] Step S610: If the difference between the expected total power and the permitted total driving power is greater than a preset threshold, the expected torque corresponding to each driving motor is limited based on the permitted driving power and permitted torque of each driving motor, and the target torque corresponding to each driving motor is obtained, and torque is distributed to each driving motor based on the target torque.

[0115] Specifically, based on the permitted driving power and permitted torque of each driving motor, limiting the expected torque corresponding to each driving motor includes:

[0116] When a vehicle has two drive motors, when calculating the expected torque corresponding to one of the drive motors, the permitted total drive power minus the actual power consumption of the other drive motor is used as the drive power of the drive motor under the limitation of the power battery capacity, and based on the drive power and the drive motor, a preset first MAP table is queried to determine the torque of the drive motor under the limitation of the power battery capacity as the first permitted torque.

[0117] Among them, the preset first MAP table can refer to Figure 5 , Figure 5 This is the first MAP table of the present application, wherein the horizontal axis is the rotational speed corresponding to each drive motor, and the vertical axis is the torque corresponding to each drive motor.

[0118] The process of making the preset first MAP table can refer to Figure 6 , Figure 6 This is a schematic diagram of the process of making the MAP table for this application.

[0119] The process of making the preset first MAP table includes:

[0120] 1) According to the power external characteristic data and torque external characteristic data of each driving motor, the power external characteristic data and torque external characteristic data of the vehicle four-wheel drive are obtained;

[0121] 2) Convert the minimum MAP table corresponding to each total torque value and speed into a first transition list, wherein the first column of the first transition list is power, the second column is speed, and the third column is torque, and convert the first transition list into a two-dimensional MAP table with power and speed as table headers by means of scattered point interpolation, wherein the NAN row data in the first transition list needs to be removed before conversion, and the NAN data in the two-dimensional MAP table is filled with the torque external characteristic data of the vehicle four-wheel drive at the corresponding speed, so as to obtain a power-speed-to-total torque table;

[0122] 3) Convert the minimum MAP table corresponding to each total torque value and speed and the corresponding distribution coefficient table into a second transition table, wherein the first column of the second transition table is power, the second column is speed, and the third column is distribution coefficient, and convert the second transition table into a power-speed distribution coefficient table by scatter point interpolation, wherein the NAN row data in the second transition table needs to be removed before conversion, and during the conversion process, the generated NAN data needs to be filled with the distribution coefficient obtained by the torque external characteristic number ratio of the vehicle four-wheel drive at the same speed;

[0123] 4) Multiply the power-speed-to-total-torque table and the power-speed-to-distribution-coefficient table to obtain the power-speed-to-torque table (first MAP table) of each drive motor.

[0124] Specifically, the permissible torque of the drive motor is usually the permissible torque of the drive motor shaft end. Since a reducer is provided between the drive motor and the wheel, the permissible torque of the drive motor can be converted into the second permissible torque corresponding to the drive motor based on the reduction ratio of the reducer and the conversion loss of the permissible drive power of the drive motor to the mechanical power. The conversion loss of the permissible drive power of the drive motor to the mechanical power can be estimated based on the bus voltage, temperature and rotation speed of the drive motor.

[0125] It should be noted that the estimation of the conversion loss from the permissible driving power of the driving motor to the mechanical power may be carried out in any appropriate manner commonly used in the art, which will not be described in detail in the embodiments of the present application.

[0126] The target torque corresponding to the drive motor is obtained by adding the first permissible torque to the second permissible torque.

[0127] Step S620: If the difference between the expected total power and the permitted total driving power is less than or equal to a preset threshold, the vehicle torque is limited according to preset conditions to obtain the vehicle torque limit value, and the step of determining the expected torque corresponding to each driving motor based on the vehicle torque limit value and the target torque distribution coefficient is returned.

[0128] Specifically, the step of limiting the vehicle torque according to the preset conditions to obtain the vehicle torque limit value of the vehicle includes:

[0129] Based on the expected torque corresponding to each driving motor, a torque distribution coefficient of each driving motor is determined.

[0130] The expected torques corresponding to the various drive motors are added together to obtain the expected total torque of the vehicle, and the expected torques corresponding to the various drive motors are divided by the expected total torque of the vehicle to obtain the torque distribution coefficients of the various drive motors.

[0131] A second permissible driving power of each driving motor is calculated based on the torque distribution coefficient and the permissible total driving power.

[0132] The second permissible driving power of each driving motor can be obtained by multiplying the torque distribution coefficient of each driving motor by the permissible total driving power.

[0133] Based on the second permitted driving power and the current vehicle speed, the vehicle torque is limited to obtain a vehicle torque limit value of the vehicle.

[0134] Based on the second permissible driving power and the current vehicle speed, the second permissible driving torque of each driving motor is determined; and based on the reduction ratio of the reducer and the conversion loss of the second permissible driving power of the driving motor to the mechanical power under the power battery capacity limitation, the second permissible driving torque of the driving motor is converted into a third torque limit value corresponding to the driving motor. The conversion loss of the second permissible driving power of the driving motor to the mechanical power under the power battery capacity limitation can also be estimated based on the bus voltage, temperature and speed of the driving motor.

[0135] Secondly, the permissible torque of the drive motor is usually the permissible torque of the drive motor shaft end. Since a reducer is provided between the drive motor and the wheel, the permissible torque of the drive motor can be converted into the fourth torque limit value corresponding to the drive motor based on the reduction ratio of the reducer and the conversion loss of the permissible drive power of the drive motor to the mechanical power. The conversion loss of the permissible drive power of the drive motor to the mechanical power can be estimated based on the bus voltage, temperature and rotation speed of the drive motor.

[0136] It should be noted that the estimation of the conversion loss from the permissible driving power of the driving motor to the mechanical power may be carried out in any appropriate manner commonly used in the art, which will not be described in detail in the embodiments of the present application.

[0137] The third torque limit value corresponding to each drive motor is compared with the fourth torque limit value corresponding to the drive motor.

[0138] In the case of output torque, the smallest one of the third torque limit value and the fourth torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor.

[0139] In the case of torque recovery, the maximum value of the third torque limit value and the fourth torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor.

[0140] The sum of the torque limit values ​​corresponding to the drive motors is calculated as the vehicle torque limit value of the vehicle.

[0141] The above-mentioned vehicle torque control method obtains the permitted total driving power that the power battery can provide to the drive motors, the permitted driving power of each drive motor, the permitted torque of each drive motor, the whole vehicle torque of the vehicle and the current vehicle speed; based on the permitted driving power of each drive motor, the permitted torque of each drive motor and the current vehicle speed, the whole vehicle torque is limited in accordance with the power consumption minimization logic to obtain the whole vehicle torque limit value and the target torque distribution coefficient of the vehicle; based on the whole vehicle torque limit value and the target torque distribution coefficient, the expected torque corresponding to each drive motor is determined; based on the expected torque corresponding to each drive motor and the rotational speed of each drive motor, the expected total power of the vehicle is determined; the expected total power is compared with the permitted total driving power, and according to the comparison result, the corresponding distribution strategy is selected to distribute the torque to each drive motor, so as to achieve economical distribution output of torque while meeting the power demand of vehicle driving to the greatest extent.

[0142] The present application also provides a vehicle torque estimation system, referring to Figure 3 , Figure 3 This is a schematic diagram of the functional modules of the first embodiment of the vehicle torque estimation system of the present application.

[0143] In this embodiment, the vehicle torque control system includes:

[0144] The energy management module 10 is used to obtain the permitted total driving power that the power battery can provide to the driving motor, the permitted driving power of each driving motor, the permitted torque of each driving motor, the vehicle torque and the current vehicle speed, wherein the current vehicle speed is one of the real-time vehicle speed and the reference vehicle speed.

[0145] The torque limiting module 20 is used to limit the vehicle torque based on the permitted total driving power, the permitted driving power of each driving motor, the permitted torque of each driving motor and the current vehicle speed according to the power consumption minimization logic to obtain the vehicle torque limit value of the vehicle.

[0146] Optionally, the torque limiting module is used to implement:

[0147] Determining the speed corresponding to each drive motor based on the current vehicle speed;

[0148] Based on the permitted total drive power and the speeds corresponding to the drive motors, a preset third MAP table is queried to determine a first torque limit value corresponding to each drive motor, wherein the first torque limit value is used to characterize the output permitted torque corresponding to the drive motor under the limitation of the power battery capacity, and the third MAP table is used to characterize the mapping relationship between the permitted total drive power-the speeds of each drive motor-the torque of each drive motor;

[0149] Determine a second torque limit value corresponding to each drive motor based on the permitted driving power of each drive motor and the permitted torque of each drive motor, wherein the second torque limit value is used to represent the output permitted torque corresponding to the drive motor under its own capacity limitation;

[0150] A vehicle torque limit value of the vehicle is determined based on the first torque limit value and the second torque limit value.

[0151] Optionally, the torque limiting module is further used to implement:

[0152] Comparing the first torque limit value corresponding to each drive motor with the second torque limit value corresponding to the drive motor;

[0153] In the case of output torque, the smallest of the first torque limit value and the second torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor;

[0154] In the case of torque recovery, the maximum of the first torque limit value and the second torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor;

[0155] The sum of the torque limit values ​​corresponding to the drive motors is calculated as the vehicle torque limit value of the vehicle.

[0156] Optionally, the energy management module includes:

[0157] The current vehicle speed acquisition submodule is used to acquire the real-time vehicle speed of the vehicle as the current vehicle speed when the vehicle is in a stable driving condition, and to acquire the reference vehicle speed corresponding to the vehicle as the current vehicle speed when the vehicle is in an unstable driving condition.

[0158] Optionally, the current vehicle speed acquisition submodule is further used to implement:

[0159] Obtaining the front drive motor speed, the rear drive motor speed, the speed change rate of the front drive motor and the speed change rate of the rear drive motor;

[0160] If the difference between the front drive motor speed and the rear drive motor speed is greater than a first preset threshold, or the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor is greater than a second preset threshold, the vehicle is in an unstable driving condition.

[0161] Optionally, the current vehicle speed acquisition submodule is further used to implement:

[0162] Determining a reference vehicle speed corresponding to the vehicle based on a maximum value of the front drive motor speed and the rear drive motor speed;

[0163] The reference vehicle speed is corrected based on the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor, and the corrected reference vehicle speed is used as the current vehicle speed.

[0164] The specific implementation of the vehicle torque estimation system of the present application is basically the same as the various embodiments of the above-mentioned vehicle torque estimation method, and will not be repeated here.

[0165] An embodiment of the present application also provides a vehicle, which includes a power battery, at least two drive motors, and the vehicle torque estimation system as described above.

[0166] An embodiment of the present application further provides a storage medium, on which a vehicle torque estimation program is stored. When the vehicle torque estimation program is executed by a processor, the steps of the vehicle torque estimation method as described above are implemented.

[0167] The specific implementation of the storage medium of the present application is basically the same as the above-mentioned embodiments of the vehicle torque control method, and will not be repeated here.

[0168] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0169] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0170] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0171] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A vehicle torque estimation method, characterized in that: Applied to a vehicle including a power battery and at least two drive motors, the vehicle torque estimation method comprises the following steps: Obtaining the permitted total driving power that the power battery can provide to the driving motor, the permitted driving power of each driving motor, the permitted torque of each driving motor, the whole vehicle torque of the vehicle, and the current vehicle speed, wherein the current vehicle speed is one of a real-time vehicle speed and a reference vehicle speed; Based on the permitted total drive power, the permitted drive power of each drive motor, the permitted torque of each drive motor and the current vehicle speed, the vehicle torque is limited according to the power consumption minimization logic to obtain a vehicle torque limit value of the vehicle; The step of limiting the vehicle torque according to the power consumption minimization logic based on the permitted total drive power, the permitted drive power of each drive motor, the permitted torque of each drive motor and the current vehicle speed to obtain the vehicle torque limit value of the vehicle includes: Determining the speed corresponding to each drive motor based on the current vehicle speed; Based on the permitted total driving power and the speeds corresponding to the driving motors, querying a preset third MAP table to determine a first torque limit value corresponding to each driving motor; Determining a second torque limit value corresponding to each drive motor based on the permissible drive power of each drive motor and the permissible torque of each drive motor; Comparing the first torque limit value corresponding to each drive motor with the second torque limit value corresponding to the drive motor; In the case of output torque, the smallest of the first torque limit value and the second torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor; In the case of torque recovery, the maximum of the first torque limit value and the second torque limit value corresponding to each drive motor is taken as the torque limit value corresponding to each drive motor; The sum of the torque limit values ​​corresponding to the drive motors is calculated as the vehicle torque limit value of the vehicle.

2. The vehicle torque estimation method according to claim 1, characterized in that: The first torque limit value is used to represent the output allowable torque corresponding to the drive motor under the limitation of the power battery capacity; The third MAP table is used to represent the mapping relationship between the permitted total driving power, the speed of each driving motor, and the torque of each driving motor; The second torque limit value is used to represent the output allowable torque corresponding to the drive motor under its own capacity limitation.

3. The vehicle torque estimation method according to claim 1, characterized in that: The step of obtaining the current vehicle speed includes: When the vehicle is in a stable driving condition, obtaining the real-time vehicle speed of the vehicle as the current vehicle speed; When the vehicle is in an unstable driving condition, a reference vehicle speed corresponding to the vehicle is obtained as the current vehicle speed.

4. The vehicle torque estimation method according to claim 3, characterized in that: Before the step of obtaining the real-time speed of the vehicle as the current speed when the vehicle is in a stable driving condition, the method further includes: Obtaining the front drive motor speed, the rear drive motor speed, the speed change rate of the front drive motor and the speed change rate of the rear drive motor; If the difference between the front drive motor speed and the rear drive motor speed is greater than a first preset threshold, or the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor is greater than a second preset threshold, the vehicle is in an unstable driving condition.

5. The vehicle torque estimation method according to claim 4, characterized in that: The step of obtaining a reference speed corresponding to the vehicle as the current speed includes: A reference vehicle speed corresponding to the vehicle is determined based on a maximum value of the front drive motor speed and the rear drive motor speed.

6. The vehicle torque estimation method according to claim 5, characterized in that: The step of obtaining a reference speed corresponding to the vehicle as the current speed also includes: The reference vehicle speed is corrected based on the maximum value of the speed change rate of the front drive motor and the speed change rate of the rear drive motor, and the corrected reference vehicle speed is used as the current vehicle speed.

7. A vehicle torque estimation system, characterized in that: The vehicle torque estimation system comprises: an energy management module, used to obtain the permitted total driving power that the power battery can provide to the driving motor, the permitted driving power of each driving motor, the permitted torque of each driving motor, the whole vehicle torque of the vehicle, and the current vehicle speed, wherein the current vehicle speed is one of a real-time vehicle speed and a reference vehicle speed; a torque limiting module, configured to limit the vehicle torque according to a power consumption minimization logic based on the permitted total drive power, the permitted drive power of each drive motor, the permitted torque of each drive motor and the current vehicle speed, so as to obtain a vehicle torque limit value of the vehicle; The torque limiting module is also used to determine the rotational speed corresponding to each drive motor based on the current vehicle speed; based on the permitted total drive power and the rotational speed corresponding to each drive motor, query a preset third MAP table to determine the first torque limit value corresponding to each drive motor; based on the permitted drive power of each drive motor and the permitted torque of each drive motor, determine the second torque limit value corresponding to each drive motor; compare the first torque limit value corresponding to each drive motor with its corresponding second torque limit value; in the case of output torque, take the smallest of the first torque limit value and the second torque limit value corresponding to each drive motor as the torque limit value corresponding to each drive motor; in the case of recovery torque, take the largest of the first torque limit value and the second torque limit value corresponding to each drive motor as the torque limit value corresponding to each drive motor; calculate the sum of the torque limit values ​​corresponding to each drive motor as the vehicle torque limit value of the vehicle.

8. A vehicle, characterized in that: The vehicle includes a power battery, at least two drive motors and the vehicle torque estimation system as claimed in claim 7.

9. A storage medium, characterized in that: The storage medium stores a vehicle torque estimation program, and when the vehicle torque estimation program is executed by the processor, the steps of the vehicle torque estimation method according to any one of claims 1 to 6 are implemented.

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