Winter driving index calculation method and system for electric vehicle in winter driving environment

Abstract

The application discloses a winter driving index calculation method and system for an electric vehicle in a winter driving environment, wherein the method comprises determining a driving road condition, determining a thermal control index, a chassis control index and a road friction force index; the thermal control index, the chassis control index and the road friction force index are fused and calculated to generate a winter driving index, and driving torque is optimized according to the winter driving index; the application improves the accuracy and reliability of road friction force calculation in the electric vehicle control system; the road friction force calculation in the control strategy is started under more stable and conservative conditions to ensure high numerical reliability and accuracy; the application uses a more comprehensive calculation method to calculate the winter driving index, and road noise in a short time can be filtered out to prevent misjudgment of the road friction force or excessive reaction of the control system to the estimated road friction force value; the winter driving index is not only beneficial to optimizing braking force, but also beneficial to optimizing driving force of a transmission system.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle driving control technology, and in particular to a method and system for calculating the winter driving index of electric vehicles in winter driving environments. Background Technology

[0002] Existing technologies include methods for estimating the friction coefficient between tires and the road surface. These methods measure the friction coefficient between the tires and the road surface for safe distance control and calculate the road friction coefficient using steering and braking forces. However, road friction is variable throughout a driving cycle, making it difficult to estimate. Furthermore, even if the controller can estimate the friction coefficient, the road surface changes continuously within a short period during the same driving cycle, leading to inconsistent calculation conditions and inaccurate results. In winter driving environments for electric vehicles, inaccurate road friction calculations cause errors in braking control, particularly in reducing braking distance. This can result in miscalculation of road friction or overreaction of the control system to the estimated road friction value. These problems urgently need to be addressed. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for calculating the winter driving index of electric vehicles in winter driving environments, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for calculating the winter driving index of an electric vehicle in a winter driving environment, comprising:

[0005] The ambient temperature of the electric vehicle is detected, and the driving road conditions under winter driving conditions are determined based on the ambient temperature. The thermal control index is determined based on the driving road conditions. The driving road conditions include the first driving condition, the second driving condition, and the third driving condition. Under winter driving conditions, the road friction of the first driving condition is greater than that of the second driving condition, and the road friction of the second driving condition is greater than that of the third driving condition.

[0006] The driving road conditions are determined based on the frequency of intervention and control of the chassis by the chassis control system, and the chassis control index is determined based on the driving road conditions.

[0007] When the coasting regenerative braking mode is activated, the number of wheel slips is detected, and the road conditions are determined by the coasting torque, road friction and the number of wheel slips. The road friction index is determined based on the road conditions.

[0008] The winter driving index is generated by integrating the thermal control index, chassis control index and road friction index, and the driving torque is optimized based on the winter driving index.

[0009] Furthermore, detecting the ambient temperature of the electric vehicle, determining the driving road conditions based on the ambient temperature, and determining the thermal control index based on the driving road conditions also includes:

[0010] The thermal control index includes the first thermal control index, the second thermal control index, and the third thermal control index;

[0011] Set a first temperature threshold and a second temperature threshold for the ambient temperature, wherein the first temperature threshold is greater than the second temperature threshold;

[0012] When the ambient temperature is greater than the first temperature threshold, the corresponding driving road condition is the first driving condition, and the determined thermal control index is the first thermal control index.

[0013] When the ambient temperature is between the first temperature threshold and the second temperature threshold, the corresponding driving road condition is the second driving condition, and the determined thermal control index is the second thermal control index.

[0014] When the ambient temperature is lower than the second temperature threshold, the corresponding driving road condition is the third driving condition, and the determined thermal control index is the third thermal control index.

[0015] Furthermore, it also includes:

[0016] Detecting the temperature of the high-voltage battery in an electric vehicle;

[0017] The delay time is set, and the greater the temperature difference between the high-voltage battery temperature and the ambient temperature, the longer the delay time. The delay time is used to control the time for the thermal control index to switch between each other.

[0018] Furthermore, the driving road conditions are determined based on the frequency of intervention and control of the chassis by the chassis control system, and the chassis control index is determined based on the driving road conditions. This also includes:

[0019] Set a frequency threshold for chassis intervention control activation frequency, and detect the activation frequency of chassis intervention control;

[0020] Determine whether the frequency of chassis intervention control activation exceeds the frequency threshold;

[0021] When the frequency of chassis intervention control activation exceeds the frequency threshold, the driving road conditions are determined, and the chassis control index is determined based on the driving road conditions.

[0022] Furthermore, when the frequency of chassis intervention control activation exceeds a frequency threshold, the driving road conditions are determined, and the chassis control index is determined based on these conditions. This also includes:

[0023] Set the weighted time for chassis intervention, detect the intervention duration of any chassis intervention control activation, and determine the weighting number based on the ratio of intervention duration to weighted time. The weighting number is an integer multiple of the ratio of intervention duration to weighted time.

[0024] Set the chassis control value, which is the sum of the chassis intervention control activation frequency and the weighted number;

[0025] A first control threshold and a second control threshold are set. The chassis control index includes a first control index, a second control index, and a third control index, wherein the first control threshold is less than the second control threshold.

[0026] When the chassis control value is less than the first control threshold, the driving road condition is determined as the first driving condition, and the corresponding chassis control index is the first chassis control index.

[0027] When the chassis control value is greater than the first control threshold and less than the second control threshold, the driving road condition is determined to be the second driving condition, and the corresponding chassis control index is the second chassis control index.

[0028] When the chassis control value is greater than the second control threshold, the driving road condition is determined to be the third driving condition, and the corresponding chassis control index is the third chassis control index.

[0029] Furthermore, setting a frequency threshold for chassis intervention control activation and detecting the activation frequency of chassis intervention control also includes:

[0030] Set a frequency and time threshold for chassis intervention control activation. If the time between two adjacent chassis intervention control activations is greater than the frequency and time threshold, reduce the frequency of chassis intervention control activations counted by detecting chassis intervention control activations.

[0031] Furthermore, when the coasting regenerative braking mode is activated, the number of wheel slippages is detected, and the road conditions are determined by the coasting torque, road friction, and number of wheel slippages. Based on these road conditions, the road friction index is determined. This also includes:

[0032] Detect the coasting torque and determine the deceleration of the electric vehicle based on the coasting torque and road friction.

[0033] The road friction index is determined based on the deceleration of electric vehicles and the number of wheel slippages.

[0034] Furthermore, the road friction index, generated based on the deceleration of electric vehicles and the number of wheel slippages, also includes:

[0035] The road friction index includes the first friction index, the second friction index, and the third friction index;

[0036] Set a slip threshold between the front wheel speed and the rear wheel speed. If the difference between the front wheel speed and the rear wheel speed is greater than the slip threshold, the wheel is determined to be slipping. If the difference is less than the slip threshold, the wheel is determined not to be slipping.

[0037] When the coasting regenerative braking mode is activated and the wheels slip, the road friction index is determined based on the deceleration of the electric vehicle.

[0038] A first deceleration threshold and a second deceleration threshold are set for the deceleration of electric vehicles, wherein the first deceleration threshold is greater than the second deceleration threshold;

[0039] When the deceleration value of the electric vehicle is less than the second deceleration threshold, the driving road condition is determined as the first driving condition, and the road friction index is the first friction index.

[0040] When the deceleration value of an electric vehicle is between the first deceleration threshold and the second deceleration threshold, the driving road condition is determined as the second driving condition, and the road friction index is determined as the second friction index.

[0041] When the deceleration value of the electric vehicle is between zero and the first deceleration threshold, the driving road condition is determined to be the third driving condition, and the road friction index is the first friction index.

[0042] When the coasting regenerative braking mode is not activated and / or the wheels do not slip, the driving road condition is determined to be the first driving condition, and the road friction index is the first friction index.

[0043] Furthermore, it also includes the formula for calculating the deceleration of electric vehicles:

[0044]

[0045]

[0046] Where f1 is the sliding friction force, T is the sliding torque, R is the wheel radius, f2 is the road friction force, m is the weight of the electric vehicle, and a is the deceleration of the electric vehicle.

[0047] On the other hand, a winter driving index calculation system for electric vehicles in winter driving environments is provided, for executing the winter driving index calculation method for electric vehicles in winter driving environments as described in any of the above claims, including:

[0048] Thermal control determination module, used to determine thermal control index;

[0049] The chassis control determination module is used to determine the chassis control index;

[0050] The friction determination module is used to determine the road friction index;

[0051] The calculation module integrates the thermal control index, chassis control index, and road friction index to generate winter driving index information.

[0052] The winter driving module generates winter driving signals based on the winter driving index information generated by the calculation module.

[0053] The control module is used to receive the winter driving signal generated by the winter driving module and generate winter driving instructions based on the winter driving signal;

[0054] The driving torque output module is used to receive winter driving commands generated by the control module, so that the driving torque output module can optimize the driving torque according to the winter driving commands.

[0055] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention adopts a friction calculation method to improve the accuracy and reliability of road friction calculation in electric vehicle control systems. In the control strategy of this invention, road friction calculation is only initiated under more stable and conservative conditions to ensure high reliability and accuracy of the numerical values. This invention will use a more comprehensive calculation method to calculate the winter driving index, rather than simply calculating road friction based on the real-time driving environment. This method can filter out road noise in a short period of time to avoid mismeasurement of road friction or overreaction of the control system to the estimated road friction value. The calculation of the winter driving index is not only beneficial for optimizing braking force, but also for optimizing the driving force of the transmission system. Attached Figure Description

[0056] Figure 1 This is a flowchart of the method for calculating the winter driving index of electric vehicles in winter driving environment in an embodiment of the present invention;

[0057] Figure 2 This is a logic block diagram of the method for calculating the winter driving index of electric vehicles in winter driving environment in an embodiment of the present invention;

[0058] Figure 3 This is a schematic diagram of the curve between driving road conditions and road friction force in an embodiment of the present invention;

[0059] Figure 4 Here are the logic block diagram (a) for measuring the thermal control index and the curve diagram (b) showing the driving road conditions and temperature difference in this embodiment of the invention;

[0060] Figure 5 Figure (a) shows the thermal control index determined by ambient temperature in this embodiment of the invention, and Figure (b) shows the filtered thermal control index.

[0061] Figure 6 This is a control flowchart for determining the chassis control index in an embodiment of the present invention;

[0062] Figure 7This is a graph showing the control strategy and recovery strategy of the chassis control activation counter in an embodiment of the present invention;

[0063] Figure 8 This is a flowchart of the road friction index control strategy in an embodiment of the present invention;

[0064] Figure 9 This is a graph showing the relationship between deceleration and road friction index in an embodiment of the present invention;

[0065] Figure 10 This is a block diagram showing the calculation of the winter driving index for electric vehicles in winter driving environments according to an embodiment of the present invention. Detailed Implementation

[0066] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0068] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0069] Please refer to the accompanying drawings in the specification. This invention provides a technical solution: such as... Figure 1 and 2 As shown, a method for calculating the winter driving index of an electric vehicle in winter driving environment includes the following steps:

[0070] S102. Detect the ambient temperature of the electric vehicle, determine the driving road conditions under winter driving conditions based on the ambient temperature, and determine the thermal control index based on the driving road conditions. The driving road conditions include the first driving condition, the second driving condition, and the third driving condition. The road friction in the first driving condition under winter driving conditions is greater than that in the second driving condition, and the road friction in the second driving condition is greater than that in the third driving condition.

[0071] Among them, such as Figure 3 As shown, the preferred first driving condition is a regular road surface without ice or snow in winter driving conditions, where the friction is greatest. The second driving condition is a snow-covered road surface, where the friction is less than that of a regular road surface. The third driving condition is an icy road surface, where the friction is less than that of a snow-covered road surface.

[0072] Specifically, such as Figure 4 As shown in Figure a, the thermal control index includes a first thermal control index, a second thermal control index, and a third thermal control index. Preferably, the calibration values ​​of the thermal control index are set as follows: the first thermal control index is 0, the second thermal control index is 1, and the third thermal control index is 2. A first temperature threshold and a second temperature threshold are set for the ambient temperature, wherein the first temperature threshold is greater than the second temperature threshold. When the ambient temperature is greater than the first temperature threshold, the corresponding driving road condition is the first driving condition, and the determined thermal control index is the first thermal control index, i.e., the output value is 0. When the ambient temperature is between the first temperature threshold and the second temperature threshold, the corresponding driving road condition is the second driving condition, and the determined thermal control index is the second thermal control index, i.e., the output value is 1. When the ambient temperature is less than the second temperature threshold, the corresponding driving road condition is the third driving condition, and the determined thermal control index is the third thermal control index, i.e., the output value is 2.

[0073] Among these, ambient temperature is a short-term temperature and changes relatively quickly. For example, if a vehicle is parked overnight in an underground parking lot, there will be a temperature difference between the parking lot's ambient temperature and the outdoor temperature. If the driver then drives the vehicle out of the parking lot, the temperature of the ambient sensor will change rapidly. Therefore, if... Figure 5 The thermal control index in Figure (a) should first be determined by the ambient temperature and a control threshold should be set. The ambient temperature is divided into three temperature ranges according to the first and second temperature thresholds. The three driving road conditions are respectively corresponding to the temperature from high to low. A calibration value of the corresponding thermal control index is set for each condition.

[0074] Specifically, the temperature of the high-voltage battery of the electric vehicle is detected; a delay time is set, and the greater the temperature difference between the high-voltage battery temperature and the ambient temperature, the longer the delay time. The delay time is used to control the time for the thermal control index to switch between each other.

[0075] It is understandable that, such as Figure 4 Figure (b) shows the calibration graph of the temperature difference and delay time measurement of the delay device. The high-voltage battery temperature represents the long-term temperature, which is almost unaffected by rapid changes in the external temperature in the short term. Therefore, the first and second temperature difference thresholds can be set by the difference between the high-voltage battery temperature and the ambient temperature. That is, the difference between the high-voltage battery temperature and the first temperature threshold is the first temperature difference threshold, and the difference between the high-voltage battery temperature and the second temperature threshold is the second temperature difference threshold. The first temperature threshold is less than the second temperature difference threshold. Therefore, when the temperature difference is less than the first temperature threshold, the road condition is a normal road, and when the temperature difference is greater than the second temperature threshold, the road condition is an icy road. Figure 5 Figure (b) shows the filtered thermal control index. Due to the temperature difference between the high-voltage battery and the ambient temperature, the update of the thermal control index is delayed to prevent frequent changes in the thermal control index. The greater the temperature difference between the ambient temperature and the high-voltage battery temperature, the longer the delay time should be. The thermal control index is finally determined by a delay timer, which can be controlled by comparing the temperature difference between the ambient temperature and the high-voltage battery temperature. The thermal control index can be used to compensate for the chassis control index and the road friction index to ensure that the winter driving index is generated only in winter conditions.

[0076] S104. Determine the driving road conditions based on the frequency of intervention control of the chassis by the chassis control system, and determine the chassis control index based on the driving road conditions.

[0077] Understandably, in winter driving environments and on winter roads, the chassis control system can intervene during acceleration and braking to prevent wheel slippage. Electric vehicle control requires determining the chassis control index to determine the frequency of chassis intervention control, such as ABS, TCS, and ESP. If chassis control occurs frequently, it indicates that the vehicle is being driven on a slippery winter road surface. The more frequently the chassis control system intervenes in the chassis, the more slippery the road surface is. Therefore, the corresponding road conditions can be determined based on the frequency of chassis control system intervention, and the corresponding chassis control index can be set accordingly.

[0078] Specifically, a frequency threshold for chassis intervention control activation is set, and the frequency of chassis intervention control activation is detected; it is determined whether the frequency of chassis intervention control activation is greater than the frequency threshold; when the frequency of chassis intervention control activation is greater than the frequency threshold, the driving road conditions are determined, and the chassis control index is determined based on the driving road conditions.

[0079] It is understandable that the more frequently the chassis intervention control is activated, the more slippery the road is. If the chassis control system frequently intervenes in the chassis, a frequency threshold can be set. When the frequency of chassis intervention control activation exceeds the frequency threshold, it means that the electric vehicle is driving on a winter road in a winter driving environment. The system then begins to judge the road conditions and determines the chassis control index based on the road conditions.

[0080] Optionally, such as Figure 6 As shown, a weighted time t is set for chassis intervention. The intervention duration of any chassis intervention control activation is detected. A weighting factor B is determined based on the ratio of intervention duration to weighted time; that is, a weighting factor B is generated when the intervention duration is greater than the weighted time t. The weighting factor B is an integer multiple of the ratio of intervention duration to weighted time. A chassis control value is set, which is the sum of the chassis intervention control activation frequency and the weighting factor. A first control threshold and a second control threshold are set. The chassis control index includes a first control index, a second control index, and a third control index. In this embodiment, preferably, the first control index is set to 0, the second control index to 1, and the third control index to 2. When the chassis control value is less than the first control threshold, the driving road condition is determined to be the first driving condition, and the corresponding chassis control index is the first chassis control index, i.e., the output of the first chassis control index is 0; when the chassis control value is greater than the first control threshold and less than the second control threshold, the driving road condition is determined to be the second driving condition, and the corresponding chassis control index is the second chassis control index, i.e., the output of the second chassis control index is 1; when the chassis control value is greater than the second control threshold, the driving road condition is determined to be the third driving condition, and the corresponding chassis control index is the third chassis control index, i.e., the output of the third chassis control index is 2.

[0081] The chassis index should be determined by two indices: one is the chassis control activation counter, denoted as A, representing the frequency of chassis intervention control activation; the other is the duration of chassis intervention control activation, which indicates the duration of chassis intervention control intervention. The longer the duration of chassis control intervention, the greater the chassis index becomes with the weighting factor. Therefore, chassis intervention control should be determined by the frequency of chassis intervention control activation and the duration of chassis intervention to assess the driving conditions of the electric vehicle. The control frequency can be determined by the control activation counter, and any chassis control activation should be included in this calculation. If any chassis control is active, the electric vehicle control should monitor the control duration and define long-term control compensation based on the control duration. If the control duration is greater than the weighted time, a long-term control compensation record should be added to the chassis counter, i.e., the value of the chassis counter should be A+B.

[0082] Optionally, a frequency time threshold for chassis intervention control activation can be set. If the time between two adjacent chassis intervention control activations is greater than the frequency time threshold, the frequency of chassis intervention control activation counted by detecting chassis intervention control activations will be reduced.

[0083] Among them, such as Figure 7 As shown, if no chassis control activation is detected during the monitoring period, the stored chassis control activation counter should be restored to ensure that the chassis control index can be accurately determined through chassis intervention control when the driving road conditions change, thereby reducing errors.

[0084] S106. When the coasting regenerative braking mode is activated, the number of wheel slips is detected, and the road conditions are determined by the coasting torque, road friction and the number of wheel slips. The road friction index is determined based on the road conditions.

[0085] Understandably, only when the electric vehicle is in a coasting state does the electric vehicle control system need to determine the driving road conditions based on the coasting torque, road friction, and the number of wheel slippages, and determine the road friction index based on the driving road conditions.

[0086] Specifically, the coasting torque is detected, and the deceleration of the electric vehicle is determined based on the coasting torque and road friction; the road friction index is determined based on the deceleration of the electric vehicle and the number of wheel slippages.

[0087] Optionally, it also includes a formula for calculating the deceleration of electric vehicles:

[0088]

[0089]

[0090] Where f1 is the sliding friction force, T is the sliding torque, R is the wheel radius, f2 is the road friction force, m is the weight of the electric vehicle, and a is the deceleration of the electric vehicle.

[0091] Specifically, such as Figure 8 As shown, the road friction index includes a first friction index, a second friction index, and a third friction index. In this embodiment, the first friction index is preferably set to 0, the second friction index to 1, and the third friction index to 2. The road friction index is thus defined as follows: Figure 7 The road friction force is estimated in the middle, and the friction force estimate is one of 0, 1, and 2 in the corresponding output;

[0092] Set a slip threshold between the front wheel speed and the rear wheel speed. If the difference between the front wheel speed and the rear wheel speed is greater than the slip threshold, the wheel is determined to be slipping. If the difference is less than the slip threshold, the wheel is determined not to be slipping.

[0093] When the coasting regenerative braking mode is activated and the wheels slip, the road friction coefficient is determined based on the deceleration of the electric vehicle.

[0094] Set a first deceleration threshold and a second deceleration threshold for the deceleration of the electric vehicle, where the first deceleration threshold is greater than the second deceleration threshold.

[0095] When the deceleration value of the electric vehicle is less than the second deceleration threshold, it is determined that the driving road condition is the first driving condition, and the road friction coefficient is the first friction coefficient, that is, the output value is 0.

[0096] When the deceleration value of the electric vehicle is between the first deceleration threshold and the second deceleration threshold, it is determined that the driving road condition is the second driving condition, and the road friction coefficient is the second friction coefficient, that is, the output value is 1.

[0097] When the deceleration value of the electric vehicle is between zero and the first deceleration threshold, it is determined that the driving road condition is the third driving condition, and the road friction coefficient is the third friction coefficient, that is, the output value is 2.

[0098] When the coasting regenerative braking mode is not activated and / or the wheels do not slip, it is determined that the driving road condition is the first driving condition, and the road friction coefficient is the first friction coefficient, that is, the output value is 0.

[0099] Among them, the electric vehicle control should determine whether the coasting mode is activated according to the driver's pedal control and the drive motor torque. If the accelerator pedal = 0 && the brake pedal = 0 && the motor torque < C [Nm], the coasting mode is activated; the electric vehicle control should determine whether the wheels slip by comparing the speeds of the driving wheels and the non-driving wheels. If the difference between the driving wheel speed and the non-driving wheel speed is greater than the slip threshold, the wheel slip state is activated. As Figure 9 shown, for example: in the calibration map, the first deceleration threshold is -1.5 m / s 2 , the second deceleration threshold is -2.5 m / s 2 , then when the deceleration is less than zero and greater than the first deceleration threshold of -1.5 m / s 2 , the road friction coefficient is the third friction coefficient 2. When the deceleration is between the first deceleration threshold of -1.5 m / s 2 and the second deceleration threshold of -2.5 m / s 2 , the road friction coefficient is the second friction coefficient 1. When the deceleration is less than the second deceleration threshold of -2.5 m / s 2 , the road friction coefficient is the first friction coefficient 0.

[0100] S108. Integrate and calculate the thermal control index, the chassis control index and the road friction coefficient to generate a winter driving index, and optimize the driving torque according to the winter driving index.

[0101] Specifically, the winter driving index for electric vehicles should be defined using three key control inputs and their corresponding control algorithms: thermal control index, chassis control index, and road friction index. The chassis control index and road friction index can be optimized and compensated using the thermal control index to ensure that the winter driving index is generated only in winter environments. The winter driving index generates a winter driving signal, and based on the winter driving signal, a winter driving control command is generated. The driving torque is then optimized based on the winter driving control command. The winter driving torque should be optimized and compensated with reference to the winter driving index, and the electric vehicle control should optimize the winter driving torque with reference to the winter driving index. Both the maximum driving torque and the torque slope should be optimized to provide stronger driving stability and higher driving efficiency. This control algorithm has high reliability, and this highly reliable winter driving index can be applied to optimize both acceleration torque and braking torque.

[0102] On the other hand, such as Figure 10 As shown, a winter driving index calculation system for electric vehicles in winter driving environments is provided, used to execute the winter driving index calculation method for electric vehicles in winter driving environments described in any of the above-mentioned embodiments, including:

[0103] Thermal control determination module, used to determine thermal control index;

[0104] The chassis control determination module is used to determine the chassis control index;

[0105] The friction determination module is used to determine the road friction index;

[0106] The calculation module integrates the thermal control index, chassis control index, and road friction index to generate winter driving index information.

[0107] The winter driving module generates winter driving signals based on the winter driving index information generated by the calculation module.

[0108] The control module is used to receive the winter driving signal generated by the winter driving module and generate winter driving instructions based on the winter driving signal;

[0109] The driving torque output module is used to receive winter driving commands generated by the control module, so that the driving torque output module can optimize the driving torque according to the winter driving commands.

[0110] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for calculating the winter driving index of electric vehicles in winter driving environments, characterized in that, include: The ambient temperature of the electric vehicle is detected, and the driving road conditions under winter driving conditions are determined based on the ambient temperature. The thermal control index is determined based on the driving road conditions. The driving road conditions include the first driving condition, the second driving condition, and the third driving condition. Under winter driving conditions, the road friction of the first driving condition is greater than that of the second driving condition, and the road friction of the second driving condition is greater than that of the third driving condition. The driving road conditions are determined based on the frequency of intervention and control of the chassis by the chassis control system, and the chassis control index is determined based on the driving road conditions. When the coasting regenerative braking mode is activated, the number of wheel slips is detected, and the road conditions are determined by the coasting torque, road friction and the number of wheel slips. The road friction index is determined based on the road conditions. The winter driving index is generated by integrating the thermal control index, chassis control index and road friction index, and the driving torque is optimized based on the winter driving index.

2. The method for calculating the winter driving index of an electric vehicle in winter driving environment according to claim 1, characterized in that, The process includes detecting the ambient temperature of the electric vehicle, determining the driving conditions based on the ambient temperature, and determining the thermal control index based on the driving conditions. It also includes: The thermal control index includes the first thermal control index, the second thermal control index, and the third thermal control index; Set a first temperature threshold and a second temperature threshold for the ambient temperature, wherein the first temperature threshold is greater than the second temperature threshold; When the ambient temperature is greater than the first temperature threshold, the corresponding driving road condition is the first driving condition, and the determined thermal control index is the first thermal control index. When the ambient temperature is between the first temperature threshold and the second temperature threshold, the corresponding driving road condition is the second driving condition, and the determined thermal control index is the second thermal control index. When the ambient temperature is lower than the second temperature threshold, the corresponding driving road condition is the third driving condition, and the determined thermal control index is the third thermal control index.

3. The method for calculating the winter driving index of an electric vehicle in winter driving environment according to claim 2, characterized in that, Also includes: Detecting the temperature of the high-voltage battery in an electric vehicle; The delay time is set, and the greater the temperature difference between the high-voltage battery temperature and the ambient temperature, the longer the delay time. The delay time is used to control the time for the thermal control index to switch between each other.

4. The method for calculating the winter driving index of an electric vehicle in winter driving environment according to claim 1, characterized in that, The driving road conditions are determined based on the frequency of intervention and control of the chassis by the chassis control system. The chassis control index is then determined based on these driving road conditions. Other aspects include: Set a frequency threshold for chassis intervention control activation frequency, and detect the activation frequency of chassis intervention control; Determine whether the frequency of chassis intervention control activation exceeds the frequency threshold; When the frequency of chassis intervention control activation exceeds the frequency threshold, the driving road conditions are determined, and the chassis control index is determined based on the driving road conditions.

5. The method for calculating the winter driving index of an electric vehicle in winter driving environment according to claim 4, characterized in that, When the frequency of chassis intervention control activation exceeds a frequency threshold, the driving road conditions are determined, and the chassis control index is determined based on these conditions. This also includes: Set the weighted time for chassis intervention, detect the intervention duration of any chassis intervention control activation, and determine the weighting number based on the ratio of intervention duration to weighted time. The weighting number is an integer multiple of the ratio of intervention duration to weighted time. Set the chassis control value, which is the sum of the chassis intervention control activation frequency and the weighted number; A first control threshold and a second control threshold are set. The chassis control index includes a first control index, a second control index, and a third control index, wherein the first control threshold is less than the second control threshold. When the chassis control value is less than the first control threshold, the driving road condition is determined as the first driving condition, and the corresponding chassis control index is the first chassis control index. When the chassis control value is greater than the first control threshold and less than the second control threshold, the driving road condition is determined to be the second driving condition, and the corresponding chassis control index is the second chassis control index. When the chassis control value is greater than the second control threshold, the driving road condition is determined to be the third driving condition, and the corresponding chassis control index is the third chassis control index.

6. The method for calculating the winter driving index of an electric vehicle in winter driving environment according to claim 4, characterized in that, Setting a frequency threshold for chassis intervention control activation, and detecting the activation frequency of chassis intervention control, also includes: Set a frequency and time threshold for chassis intervention control activation. If the time between two adjacent chassis intervention control activations is greater than the frequency and time threshold, reduce the frequency of chassis intervention control activations counted by detecting chassis intervention control activations.

7. The method for calculating the winter driving index of an electric vehicle in winter driving environment according to claim 1, characterized in that, When the coasting regenerative braking mode is activated, the number of wheel slippages is detected. The road conditions are determined by the coasting torque, road friction, and the number of wheel slippages. Based on these road conditions, the road friction index is determined. Other features include: Detect the coasting torque and determine the deceleration of the electric vehicle based on the coasting torque and road friction. The road friction index is determined based on the deceleration of electric vehicles and the number of wheel slippages.

8. The method for calculating the winter driving index of an electric vehicle in winter driving environment according to claim 7, characterized in that, The road friction index is generated based on the deceleration of electric vehicles and the number of wheel slippages, and also includes: The road friction index includes the first friction index, the second friction index, and the third friction index; Set a slip threshold between the front wheel speed and the rear wheel speed. If the difference between the front wheel speed and the rear wheel speed is greater than the slip threshold, the wheel is determined to be slipping. If the difference is less than the slip threshold, the wheel is determined not to be slipping. When the coasting regenerative braking mode is activated and the wheels slip, the road friction index is determined based on the deceleration of the electric vehicle. A first deceleration threshold and a second deceleration threshold are set for the deceleration of electric vehicles, wherein the first deceleration threshold is greater than the second deceleration threshold; When the deceleration value of the electric vehicle is less than the second deceleration threshold, the driving road condition is determined as the first driving condition, and the road friction index is the first friction index. When the deceleration value of an electric vehicle is between the first deceleration threshold and the second deceleration threshold, the driving road condition is determined as the second driving condition, and the road friction index is determined as the second friction index. When the deceleration value of the electric vehicle is between zero and the first deceleration threshold, the driving road condition is determined to be the third driving condition, and the road friction index is the first friction index. When the coasting regenerative braking mode is not activated and / or the wheels do not slip, the driving road condition is determined to be the first driving condition, and the road friction index is the first friction index.

9. The method for calculating the winter driving index of an electric vehicle in winter driving environment according to claim 8, characterized in that, It also includes the formula for calculating the deceleration of electric vehicles: Where f1 is the sliding friction force, T is the sliding torque, R is the wheel radius, f2 is the road friction force, m is the weight of the electric vehicle, and a is the deceleration of the electric vehicle.

10. A winter driving index calculation system for electric vehicles in winter driving environments, used to execute the winter driving index calculation method for electric vehicles in winter driving environments according to any one of claims 1 to 9, characterized in that, include: Thermal control determination module, used to determine thermal control index; The chassis control determination module is used to determine the chassis control index; The friction determination module is used to determine the road friction index; The calculation module integrates the thermal control index, chassis control index, and road friction index to generate winter driving index information. The winter driving module generates winter driving signals based on the winter driving index information generated by the calculation module. The control module is used to receive the winter driving signal generated by the winter driving module and generate winter driving instructions based on the winter driving signal; The driving torque output module is used to receive winter driving commands generated by the control module, so that the driving torque output module can optimize the driving torque according to the winter driving commands.

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