A performance calibration method for pure electric vehicles

Abstract

The present invention relates to a performance calibration method for a pure electric vehicle, comprising: calibrating the driving coefficient corresponding to the accelerator pedal opening according to the driving torque under a specific accelerator pedal opening during normal vehicle driving, under the premise of smooth driving; calibrating the electric brake torque according to the current vehicle speed and brake pedal opening; during vehicle driving, according to the magnitude relationship between different gears, target torque and actual torque, looking up a table to obtain a torque change value, and then filtering the torque request; according to the driving conditions, altitude, ambient temperature and other different market segments of pure electric vehicles, the vehicle driving force, energy recovery capability and torque filter calibration can be quickly completed, and the software development efficiency of the vehicle controller can be improved. At the same time, an effective balance between driving safety, comfort and economy of pure electric vehicles can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a performance calibration method for a pure electric vehicle. Background Art

[0002] During the investigation of the market operation of new energy vehicles, especially pure electric vehicles, it was found that the driving conditions in different market segments are not the same, so the user feedback issues are different: 1. In plain areas, the requirements for vehicle power are not high, but the vehicle economy / power mode (economic mode: more emphasis on vehicle economy, slower power response, slower acceleration; power mode: more emphasis on acceleration, fast power response, weakened economy) is expected to be clearly differentiated; at the same time, it is also expected that energy can be recovered during braking according to the braking demand; 2. There are many mountainous conditions in the southwest region, but the requirements for vehicle power are high, and it is expected that the normal driving requirements of the vehicle can be met in the E mode (economic mode); at the same time, it is also expected that the energy recovery during the gliding process will be increased during the downhill process, and after the vehicle speed exceeds the maximum design speed during the downhill process, energy can be recovered during both gliding and braking;

[0003] However, no matter what the working conditions are, vehicle smoothness is the biggest prerequisite for vehicle safety, and the requested torque filtering during vehicle driving is particularly critical.

[0004] Therefore, in order to increase the applicability of pure electric vehicles of vehicle manufacturers and expand market share, it is imperative to carry out specific working condition calibration work according to the needs of different market segments such as driving conditions, altitude, and ambient temperature. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and to propose a performance calibration method for a pure electric vehicle, which can quickly complete the vehicle driving force, energy recovery capability and torque filter calibration, improve the efficiency of vehicle controller software development, and at the same time achieve an effective balance between the driving safety, comfort and economy of the pure electric vehicle.

[0006] In order to solve the problems in the above background technology, the present invention is implemented by the following technical solutions:

[0007] A performance calibration method for a pure electric vehicle, comprising:

[0008] Driving performance calibration: Based on the driving torque at a specific accelerator pedal opening during normal vehicle driving, the driving coefficient corresponding to the accelerator pedal opening is calibrated on the premise of smooth driving;

[0009] Braking performance calibration: Calibrate the electric braking torque according to the vehicle's current speed and brake pedal opening;

[0010] Request torque filtering: During vehicle driving, the torque change value is obtained by looking up the table according to the relationship between different gears, requested torque and actual motor torque. , and then the requested torque is filtered.

[0011] Preferably, the driving torque at the specific accelerator pedal opening is:

[0012] T Drv _cmd=k Drv *T(n) ;

[0013] in, T Drv is the motor drive torque, T(n) The maximum allowable output motor torque is obtained according to the motor external characteristic curve and different motor speeds. k Drv is the driving coefficient under the driving condition demand mode.

[0014] Preferably, in the braking performance calibration, based on the vehicle speed distribution map and brake pedal opening distribution map under different driving conditions, the common vehicle speed range and common brake pedal opening range of the specific driving condition are extracted for calibration, wherein the driving conditions include plains, mountainous areas and urban comprehensive;

[0015] The deceleration generated when the vehicle brakes is composed of three parts: the deceleration caused by the sliding resistance, the mechanical braking deceleration, and the electric braking deceleration. The resistance of the vehicle sliding under the braking force is the sliding resistance:

[0016] ;

[0017] in F 滑 For sliding resistance, F w is the air resistance, F f is the rolling resistance, is the slope resistance, F j For acceleration resistance, M For the vehicle operation quality, g is the acceleration due to gravity, f is the tire rolling resistance coefficient, C D is the air resistance coefficient, A is the frontal area of ​​the vehicle, For vehicle speed, δ is the vehicle rotation mass conversion factor, The vehicle acceleration, is the road ramp angle.

[0018] The deceleration during braking is:

[0019] ;

[0020] in, is the deceleration during braking, F 滑 / M is the deceleration caused by sliding resistance, is the deceleration caused by mechanical braking, is the electric brake deceleration.

[0021] Preferably, when the vehicle braking system has no brake pedal opening, that is, the braking system is an air brake system, the braking energy recovery torque associated with the braking time is calibrated:

[0022] a. Calibrate the lower limit of the braking energy recovery torque at different vehicle speeds according to the vehicle's no-load state;

[0023] b. According to the historical vehicle terminal data, calibrate the effective braking time of the corresponding vehicle model;

[0024] c. According to the braking demand, calibrate the upper limit of the braking energy recovery torque at different vehicle speeds during the maximum braking effective time;

[0025] The braking energy recovery torque is:

[0026] ;

[0027] Where: T BK_ cmd For braking energy recovery torque, t BK is the braking time, T BKmax is the maximum effective braking time, T BK_low The lower limit of the braking torque. T BK_up Braking torque energy recovery torque upper limit.

[0028] Preferably, in combination with vehicle ride comfort and economy, the braking energy recovery torque calibration process includes the following constraints:

[0029] Constraint 1: Maximum regenerative torque is determined by the maximum efficiency of the motor:

[0030] ;

[0031] Where: P e is the maximum power of the motor, nis the motor speed, T tq is the motor torque, which is constrained according to the maximum power of the motor;

[0032] Constraint 2: The vehicle deceleration is too large, which not only affects the driver's driving experience, but also may activate the anti-lock braking system ABS, thereby exiting energy recovery. Therefore, the electric brake deceleration There is an upper limit:

[0033] ;

[0034] Where: is the electric brake deceleration, T Erk _cmd For energy recovery torque, M For the vehicle operation quality, r is the tire radius, is the transmission ratio of the transmission; The transmission ratio of the main reducer.

[0035] Preferably, since there are multiple operating modes during the operation of the vehicle, different operating modes correspond to different torque outputs, and the requested torque will jump during the switching of each operating mode, therefore, the requested torque needs to be filtered;

[0036] The operating modes include a D gear driving mode, an R gear driving mode, an energy recovery mode, a creep mode, an anti-slope mode, and a cruise control mode.

[0037] Preferably, the torque change value of a task scheduling cycle is determined according to the relationship between the different gears, the target torque and the actual torque. size:

[0038] When the D gear driving mode is on and the target torque is greater than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ;

[0039] When the D gear driving mode is on and the target torque is less than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ;

[0040] When the R gear driving mode is on and the target torque is less than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ;

[0041] When the R gear driving mode is on and the target torque is greater than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ;

[0042] When energy recovery is performed in D gear driving mode, the requested torque is a negative value, so and When obtained from a table lookup, the actual torque can range from negative to positive values.

[0043] Preferably, the torque change value Perform filtering:

[0044] ;

[0045] In the formula, Tq_cmd(k) Request torque for time k, Tq(k) is the target torque at time k, is the torque change at time k.

[0046] Compared with the prior art, the present invention has the following beneficial technical effects:

[0047] According to the different market segments such as pure electric vehicle driving conditions, altitude, ambient temperature, etc., it can quickly complete the vehicle driving force, energy recovery capability and torque filter calibration, improve the efficiency of vehicle controller software development, and achieve an effective balance between pure electric vehicle driving safety, comfort and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the external characteristic curve of a motor of a certain vehicle model of the present invention;

[0049] Figure 2 is the driving coefficient of a certain vehicle model of the present invention under different market segment operation modes;

[0050] Figure 3 The brake torque calibration curve for different vehicle speeds and different brake pedal openings of a certain vehicle model of the present invention;

[0051] Figure 4 It is the energy recovery torque calibration curve of a vehicle model without brake pedal opening of the present invention;

[0052] Figure 5 This is a flow chart of torque filtering request according to the present invention. DETAILED DESCRIPTION

[0053] Pure electric vehicle driving performance calibration: In different market segments, driving performance requirements are inconsistent, so different driving performance needs to be achieved for different operating modes. The driving capacity of the vehicle is determined by the power of the motor. The same configuration model has the same driving capacity in different market segments and is determined by the external characteristics of the motor. The part that can be calibrated during the vehicle controller software development process is to output the appropriate torque coefficient based on different accelerator pedal openings, combined with market demand, and on the premise of meeting the smoothness of the vehicle.

[0054] Braking performance calibration of pure electric vehicles: There are two types of braking for pure electric vehicles: coasting braking and braking by stepping on the brakes. In both braking modes, energy recovery strategies can be formulated through the vehicle controller software to recover as much energy as possible while ensuring the vehicle's stability and braking performance, so as to improve the economy of the vehicle. In the needs of different market segments, according to the speed distribution during vehicle operation, a relatively large speed range is extracted, and calibration is focused within this range to output appropriate braking torque.

[0055] Request torque filtering: There are different operating mode switches during vehicle operation. If the requested torque changes too much during the switching process, it will affect the vehicle's smoothness. In the case of driving and braking, the torque change value of a task scheduling cycle is determined based on the relationship between the target torque and the actual torque. According to the relationship between the current target torque and the previous target torque, an adaptive filtering method is introduced to filter the final requested torque.

[0056] A performance calibration method for a pure electric vehicle, comprising:

[0057] Driving performance calibration: Based on the driving torque at a specific accelerator pedal opening during normal vehicle driving, the driving coefficient corresponding to the accelerator pedal opening is calibrated on the premise of smooth driving;

[0058] Braking performance calibration: Calibrate the electric braking torque according to the vehicle's current speed and brake pedal opening;

[0059] Request torque filtering: During vehicle driving, the torque change value is obtained by looking up the table according to the relationship between different gears, requested torque and actual motor torque. , and then the requested torque is filtered.

[0060] like Figure 1-Figure 2 As shown, the driving torque at the specific accelerator pedal opening is:

[0061] T Drv _cmd=k Drv *T(n) ;

[0062] in, T Drv is the motor drive torque, T(n) The maximum allowable output motor torque is obtained according to the motor external characteristic curve and different motor speeds. k Drv is the driving coefficient under the driving condition demand mode.

[0063] like Figure 3As shown, in the braking performance calibration, according to the vehicle speed distribution map and brake pedal opening distribution map under different driving conditions, the common vehicle speed range and common brake pedal opening range of the specific driving conditions are extracted for calibration, wherein the driving conditions include plain, mountainous area and urban comprehensive;

[0064] The deceleration generated when the vehicle brakes is composed of three parts: the deceleration caused by the sliding resistance, the mechanical braking deceleration, and the electric braking deceleration. The resistance of the vehicle sliding under the braking force is the sliding resistance:

[0065] ;

[0066] in F 滑 For sliding resistance, F w is the air resistance, F f is the rolling resistance, is the slope resistance, F j For acceleration resistance, M For the vehicle operation quality, g is the acceleration due to gravity, f is the tire rolling resistance coefficient, C D is the air resistance coefficient, A is the frontal area of ​​the vehicle, v For vehicle speed, δ is the vehicle rotation mass conversion factor, The vehicle acceleration, is the road ramp angle.

[0067] The deceleration during braking is:

[0068] ;

[0069] in, is the deceleration during braking, F 滑 / M is the deceleration caused by sliding resistance, is the deceleration caused by mechanical braking, is the electric brake deceleration.

[0070] like Figure 4 As shown, when the vehicle braking system has no brake pedal opening, that is, the braking system is an air brake system, the braking energy recovery torque associated with the braking time is calibrated:

[0071] a. Calibrate the lower limit of the braking energy recovery torque at different vehicle speeds according to the vehicle's no-load state;

[0072] b. According to the historical vehicle terminal data, calibrate the effective braking time of the corresponding vehicle model;

[0073] c. According to the braking demand, calibrate the upper limit of the braking energy recovery torque at different vehicle speeds during the maximum braking effective time;

[0074] The braking energy recovery torque is:

[0075] ;

[0076] Where: T BK_ cmd For braking energy recovery torque, t BK is the braking time, T BKmax is the maximum effective braking time, T BK_low The lower limit of the braking torque. T BK_up Braking torque energy recovery torque upper limit.

[0077] Considering vehicle smoothness and economy, the calibration process of braking energy recovery torque includes the following constraints:

[0078] Constraint 1: Maximum regenerative torque is determined by the maximum efficiency of the motor:

[0079] ;

[0080] Where: P e is the maximum power of the motor, n is the motor speed, T tq is the motor torque, which is constrained according to the maximum power of the motor;

[0081] Constraint 2: The vehicle deceleration is too large, which not only affects the driver's driving experience, but also may activate the anti-lock braking system ABS, thereby exiting energy recovery. Therefore, the electric brake deceleration There is an upper limit:

[0082] ;

[0083] Where: is the electric brake deceleration, T Erk _cmd For energy recovery torque, M For the vehicle operation quality, r is the tire radius, is the transmission ratio of the transmission; The transmission ratio of the main reducer.

[0084] like Figure 5 As shown, since there are multiple operating modes during vehicle operation, different operating modes correspond to different torque outputs, and the requested torque will jump during the switching of each operating mode. Therefore, the requested torque needs to be filtered;

[0085] The operating modes include a D gear driving mode, an R gear driving mode, an energy recovery mode, a creep mode, an anti-slope mode, and a cruise control mode.

[0086] According to the relationship between different gears, target torque and actual torque, determine the torque change value of a task scheduling cycle size:

[0087] When the D gear driving mode is on and the target torque is greater than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ;

[0088] When the D gear driving mode is on and the target torque is less than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ;

[0089] When the R gear driving mode is on and the target torque is less than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ;

[0090] When the R gear driving mode is on and the target torque is greater than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ;

[0091] When energy recovery is performed in D gear driving mode, the requested torque is a negative value, so and When obtained from a table lookup, the actual torque can range from negative to positive values.

[0092] The torque change value Perform filtering:

[0093] ;

[0094] In the formula, Tq_cmd(k) Request torque for time k, Tq(k) is the target torque at time k, is the torque change at time k.

Claims

1. A performance calibration method for a pure electric vehicle, characterized in that: include: Driving performance calibration: Based on the driving torque at a specific accelerator pedal opening during normal vehicle driving, the driving coefficient corresponding to the accelerator pedal opening is calibrated on the premise of smooth driving; Braking performance calibration: Calibrate the electric braking torque according to the vehicle's current speed and brake pedal opening; Request torque filtering: During vehicle driving, the torque change value is obtained by looking up the table according to the relationship between different gears, requested torque and actual motor torque. , and then filter the requested torque; In the braking performance calibration, based on the vehicle speed distribution map and brake pedal opening distribution map under different driving conditions, the common vehicle speed range and common brake pedal opening range of the specific driving conditions are extracted for calibration, wherein the driving conditions include plains, mountainous areas and urban comprehensive; The deceleration generated when the vehicle brakes is composed of three parts: the deceleration caused by the sliding resistance, the mechanical braking deceleration, and the electric braking deceleration. The resistance of the vehicle sliding under the braking force is the sliding resistance: ； in F 滑 For sliding resistance, F w is the air resistance, F f is the rolling resistance, is the slope resistance, F j For acceleration resistance, M For the vehicle operation quality, g is the acceleration due to gravity, f is the tire rolling resistance coefficient, C D is the air resistance coefficient, A is the frontal area of ​​the vehicle, v For vehicle speed, δ is the vehicle rotation mass conversion factor, The vehicle acceleration, is the road ramp angle; The deceleration during braking is: ； in, is the deceleration during braking, F 滑 / M is the deceleration caused by sliding resistance, is the deceleration caused by mechanical braking, is the electric brake deceleration; When the vehicle braking system has no brake pedal opening, that is, the braking system is an air brake system, the braking energy recovery torque associated with the braking time is calibrated: a. Calibrate the lower limit of the braking energy recovery torque at different vehicle speeds according to the vehicle's no-load state; b. According to the historical vehicle terminal data, calibrate the effective braking time of the corresponding vehicle model; c. According to the braking demand, calibrate the upper limit of the braking energy recovery torque at different vehicle speeds during the maximum braking effective time; The braking energy recovery torque is: ； Where: T BK_ cmd For braking energy recovery torque, t BK is the braking time, T BKmax is the maximum effective braking time, T BK_low The lower limit of the braking torque. T BK_up Braking torque energy recovery torque upper limit; Considering vehicle smoothness and economy, the calibration process of braking energy recovery torque includes the following constraints: Constraint 1: Maximum regenerative torque is determined by the maximum efficiency of the motor: ； Where: P e is the maximum power of the motor, n is the motor speed, T tq is the motor torque, which is constrained according to the maximum power of the motor; Constraint 2: The vehicle deceleration is too large, which not only affects the driver's driving experience, but also may activate the anti-lock braking system ABS, thereby exiting energy recovery. Therefore, the electric brake deceleration There is an upper limit: ； Where: is the electric brake deceleration, T Erk _cmd For energy recovery torque, M For the vehicle operation quality, r is the tire radius, is the transmission ratio of the transmission; The transmission ratio of the main reducer.

2. The performance calibration method of a pure electric vehicle according to claim 1, characterized in that: The driving torque at the specific accelerator pedal opening is: T Drv _cmd=k Drv *T(n) ； in, T Drv is the motor drive torque, T(n) The maximum allowable output motor torque is obtained according to the motor external characteristic curve and different motor speeds. k Drv is the driving coefficient under the driving condition demand mode.

3. The performance calibration method of a pure electric vehicle according to claim 1, characterized in that ,Since there are multiple operating modes during vehicle operation, different ,operating modes correspond to different torque outputs, the requested torque will jump during ,switching of the operating modes, therefore, the requested torque needs to be ,filtered; The operating modes include a D gear driving mode, an R gear driving mode, an energy recovery mode, a creep mode, an anti-slope mode, and a cruise control mode.

4. The performance calibration method of a pure electric vehicle according to claim 1, characterized in that: According to the relationship between different gears, target torque and actual torque, determine the torque change value of a task scheduling cycle size: When the D gear driving mode is on and the target torque is greater than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ; When the D gear driving mode is on and the target torque is less than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ; When the R gear driving mode is on and the target torque is less than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ; When the R gear driving mode is on and the target torque is greater than the actual torque, the torque change value is obtained by looking up the table according to the accelerator pedal opening and the actual torque. ; When energy recovery is performed in D gear driving mode, the requested torque is a negative value, so and When obtained from a table lookup, the actual torque can range from negative to positive values.

5. The performance calibration method of a pure electric vehicle according to claim 1, characterized in that: The torque change value Perform filtering: ； In the formula, Tq_cmd(k) Request torque for time k, Tq(k) is the target torque at time k, is the torque change at time k.

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