Low gear holding control method for 6-speed AMT of pure electric vehicle based on mass estimation

Abstract

The present invention relates to the field of electric air compressor control technology, and discloses a method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation, including a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, the motor controller is used for speed regulation during the gear shifting process and calculation output of the required torque, the gearbox controller is used for controlling the gear shifting, load mass estimation and low gear holding control, obtaining parameters for least squares mass estimation, and then dividing the low gear holding mode according to the estimated mass, and finally the gearbox controller performs low gear holding control according to the ramp sensor signal, the motor speed, and the vehicle speed signal. The method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation of the present invention adopts the least squares method to realize the load estimation of the engineering vehicle, and solves the problem of low gear holding control caused by different loads due to large load changes of actual working vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle gear control, and in particular to a method for controlling a 6-speed AMT low gear holding of a pure electric vehicle based on mass estimation. Background Art

[0002] For engineering vehicles, due to the harsh operating conditions of the vehicles, the complex road conditions, and the large changes in the cargo weight, the AMT shifting is too fast for high load and large slope conditions, and there is a phenomenon of inconsistency with the actual gear demand of the driver. The main difference between the AMT system structure of the current pure electric engineering vehicles and the AMT system structure of traditional vehicles is that there is no clutch, and the speed control is performed by the motor. Compared with the engine speed control, the speed control is faster and more accurate. The low gear control for pure electric AMT in the existing patents is still achieved by combining the throttle and ramp sensor signals with the calibrated shift map to achieve low gear control, and usually for a six-speed gearbox, the default initial low gear is 2nd gear, and manual switching is required when a lower gear is required on some sections of the road. Due to the increase in load, the 2nd or 1st gear needs to be maintained continuously under high throttle conditions, and the unexpected upshift leads to difficulty in climbing. Therefore, it is difficult to accurately estimate the load of the engineering vehicle and use the estimated mass for the low gear maintenance control of the gearbox.

[0003] A Chinese patent (publication date: April 4, 2023, publication number: CN115899238A) discloses a mining mode control method for a pure electric power system, which includes real-time acquisition of the real-time speed V1 of the vehicle in the 1st gear or the 2nd gear; according to the real-time speed V1 of the vehicle in the 1st gear or the 2nd gear, the real-time speed V1 of the vehicle in the 1st gear is controlled to be less than or equal to the maximum speed limit of 10km / h in the 1st gear, and the real-time speed V1 of the vehicle in the 2nd gear is controlled to be less than or equal to the maximum speed limit of 20km / h in the 2nd gear; and the position state of the gear is monitored in real time; according to the position state of the gear, if the gear position changes by more than 8%, air is introduced through the pneumatic shift mechanism to restore the gear position to a normal state. The present invention is simple to operate, not only can the gearbox be locked in the 1st gear or the 2nd gear, but also through the graded protection under different working modes, it can avoid entering the unexpected gear position and improve the reliability of the vehicle. However, it does not take into account the cargo weight, and it is difficult to achieve the control of the low gear position of the gearbox.

[0004] A Chinese patent (publication date: March 7, 2023, publication number: CN115750783A) discloses a multi-gear AMT shift control method and system for a pure electric mining truck, comprising the following steps: 1) When the mining truck is working, obtain the current slope β, the current accelerator pedal opening α, and record the corresponding collection time; 2) If the current slope β is greater than or equal to the first slope threshold a, the current accelerator pedal opening α is greater than the pedal opening threshold c, and the driving exceeds the first time threshold in this state, then enter the slope-based shift mode, otherwise maintain the speed-based shift mode; in the slope-based shift mode, the gear position is determined according to the current slope β, the accelerator pedal opening α, and the corresponding duration of each. Therefore, the present invention solves the problem of low power, safety and economy of mining trucks when driving on complex road conditions in the prior art. However, the invention still does not take into account the cargo weight, and it is difficult to achieve low gear control of the gearbox. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned technology and to provide a method for low-gear holding control of a 6-speed AMT of a pure electric vehicle based on mass estimation. The least squares method is used to realize the load estimation of the engineering vehicle, thereby solving the problem of low-gear holding control caused by different loads due to large load changes in actual operating vehicles.

[0006] To achieve the above-mentioned purpose, the present invention is a method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation, including a transmission controller and its corresponding transmission, a motor controller and its corresponding motor actuator, the motor controller is used for speed regulation during the gear shifting process and calculation output of the required torque, the transmission controller is used for controlling gear shifting, load mass estimation and low gear holding control, obtaining vehicle acceleration sensor signal, gear signal, vehicle speed, transmission ratio, rear axle ratio and motor torque parameters for least squares mass estimation, and then dividing the low gear holding mode according to the estimated mass, and finally the transmission controller performs low gear holding control according to the ramp sensor signal, motor speed and vehicle speed signal.

[0007] Preferably, the formula for the recursive least squares method is as follows:

[0008]

[0009] In the formula, y(k) is the system observation value, and are the estimated values ​​of system parameters, is the parameter to be identified, and the forgetting factor is introduced to weaken the influence of past information on the current parameter estimation, where λ is the forgetting factor, and its iterative formula is as follows:

[0010]

[0011]

[0012]

[0013] Where K(k) is the recursive gain matrix and P(k) is the covariance matrix.

[0014] Preferably, the longitudinal dynamics of the vehicle are simplified to F t =ma, combined with the recursive least squares method, it can be equivalent to the following formula:

[0015] y(k)=a(k)

[0016]

[0017]

[0018] Where a is the acceleration value, i g represents the gearbox transmission ratio, i0 represents the rear axle transmission ratio, η represents the transmission efficiency, r represents the wheel radius, m represents the vehicle mass, and T(k) represents the motor torque.

[0019] Preferably, the acceleration includes the vehicle's own acceleration a v and the drag acceleration a caused by other drag n , the vehicle is in neutral state, F(k) is 0, and the acceleration value measured by the acceleration sensor is a, which includes the vehicle's own acceleration a v and the gravitational acceleration component a g , where α is the component of gravity acceleration in the direction of travel:

[0020] a=a v +a g sinα

[0021]

[0022] Resistance acceleration caused by other resistances a n , remains unchanged for a period of time before and after the gear shift, a n is the acceleration sensor signal value when in neutral or without torque output, and the vehicle mass m is then calculated.

[0023] Preferably, when the vehicle gear is greater than or equal to 3rd gear, the vehicle enters a normal gear shift mode, and when the vehicle gear is lower than 3rd gear, the vehicle enters a low gear mode.

[0024] Preferably, the load is divided into three levels according to the calculated vehicle mass: M1 when the vehicle mass is less than or equal to 20t, M2 when the vehicle mass is between 20t and 30t, and M3 when the vehicle mass is greater than 30t.

[0025] Preferably, in the low gear mode, the default starting gear is 2nd gear.

[0026] Preferably, when the vehicle load is at level M1, the vehicle does not maintain a low gear, and performs normal gear shifting according to the vehicle speed and throttle.

[0027] Preferably, when the vehicle load is at level M2, the vehicle enters a low gear and is maintained. When the throttle exceeds 80% and the motor speed exceeds 2200r / min, the TCU does not actively shift up, but maintains the throttle at a torque value of 80%. When the speed exceeds the limit of 2600r / min, the upshift operation is performed.

[0028] Preferably, when the vehicle load is at level M3, the ramp is identified by the ramp sensor signal. When the slope exceeds 5%, the TCU automatically switches the starting gear to 1st gear when the vehicle speed is lower than 2km / h, and starts from 1st gear, taking the motor speed as the limit value. When the motor speed exceeds 2800r / min, the gear is shifted from 1st gear to 2nd gear, and when the motor speed exceeds 2600r / min, the gear is shifted from 2nd gear to 3rd gear.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. Use the least square method to estimate the load of engineering vehicles and solve the problem of low gear holding control caused by different loads due to large load changes in actual working vehicles;

[0031] 2. Solve the problem of unexpected low-gear upshifting in pure electric engineering vehicles under low load and high torque demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of a method for controlling a 6-speed AMT low gear holding of a pure electric vehicle based on mass estimation according to the present invention. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Example 1

[0037] A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation comprises a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, wherein the motor controller is used for speed regulation during gear shifting and calculation output of required torque, and the gearbox controller is used for controlling gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform mass estimation using the least square method, and then a low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs low gear holding control according to a ramp sensor signal, motor speed and vehicle speed signal.

[0038] Example 2

[0039] A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation comprises a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, wherein the motor controller is used for speed regulation during gear shifting and calculation output of required torque, and the gearbox controller is used for controlling gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform mass estimation using the least square method, and then a low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs low gear holding control according to a ramp sensor signal, motor speed and vehicle speed signal.

[0040] Among them, the formula of recursive least squares method is as follows:

[0041]

[0042] In the formula, y(k) is the system observation value, and are the estimated values ​​of system parameters, is the parameter to be identified, and the forgetting factor is introduced to weaken the influence of past information on the current parameter estimation, where λ is the forgetting factor, and its iterative formula is as follows:

[0043]

[0044]

[0045]

[0046] Where K(k) is the recursive gain matrix and P(k) is the covariance matrix.

[0047] Example 3

[0048] A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation comprises a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, wherein the motor controller is used for speed regulation during gear shifting and calculation output of required torque, and the gearbox controller is used for controlling gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform mass estimation using the least square method, and then a low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs low gear holding control according to a ramp sensor signal, motor speed and vehicle speed signal.

[0049] Among them, the formula of recursive least squares method is as follows:

[0050]

[0051] In the formula, y(k) is the system observation value, and are the estimated values ​​of system parameters, is the parameter to be identified, and the forgetting factor is introduced to weaken the influence of past information on the current parameter estimation, where λ is the forgetting factor, and its iterative formula is as follows:

[0052]

[0053]

[0054]

[0055] Where K(k) is the recursive gain matrix and P(k) is the covariance matrix.

[0056] In addition, the longitudinal dynamics of the vehicle are simplified to F t =ma, combined with the recursive least squares method, it can be equivalent to the following formula:

[0057] y(k)=a(k)

[0058]

[0059]

[0060] Where a is the acceleration value, i g represents the gearbox transmission ratio, i0 represents the rear axle transmission ratio, η represents the transmission efficiency, r represents the wheel radius, m represents the vehicle mass, and T(k) represents the motor torque.

[0061] Example 4

[0062] A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation comprises a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, wherein the motor controller is used for speed regulation during gear shifting and calculation output of required torque, and the gearbox controller is used for controlling gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform mass estimation using the least square method, and then a low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs low gear holding control according to a ramp sensor signal, motor speed and vehicle speed signal.

[0063] Among them, the formula of recursive least squares method is as follows:

[0064]

[0065] In the formula, y(k) is the system observation value, and are the estimated values ​​of system parameters, is the parameter to be identified, and the forgetting factor is introduced to weaken the influence of past information on the current parameter estimation, where λ is the forgetting factor, and its iterative formula is as follows:

[0066]

[0067]

[0068]

[0069] Where K(k) is the recursive gain matrix and P(k) is the covariance matrix.

[0070] In addition, the longitudinal dynamics of the vehicle are simplified to Ft =ma, combined with the recursive least squares method, it can be equivalent to the following formula:

[0071] y(k)=a(k)

[0072]

[0073]

[0074] Where a is the acceleration value, i g represents the gearbox transmission ratio, i0 represents the rear axle transmission ratio, η represents the transmission efficiency, r represents the wheel radius, m represents the vehicle mass, and T(k) represents the motor torque.

[0075] Finally, the acceleration includes the vehicle's own acceleration a v and the drag acceleration a caused by other drag n , the vehicle is in neutral state, F(k) is 0, and the acceleration value measured by the acceleration sensor is a, which includes the vehicle's own acceleration a v and the gravitational acceleration component a g , where α is the component of gravity acceleration in the direction of travel:

[0076] a=a v +a g sinα

[0077]

[0078] Resistance acceleration caused by other resistances a n , remains unchanged for a period of time before and after the gear shift, a n is the acceleration sensor signal value when in neutral or without torque output, and the vehicle mass m is then calculated.

[0079] Example 5

[0080] A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation comprises a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, wherein the motor controller is used for speed regulation during gear shifting and calculation output of required torque, and the gearbox controller is used for controlling gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform mass estimation using the least square method, and then a low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs low gear holding control according to a ramp sensor signal, motor speed and vehicle speed signal.

[0081] When the vehicle gear is greater than or equal to 3rd gear, the vehicle enters the normal gear shift mode, and when the vehicle gear is lower than 3rd gear, it enters the low gear mode. In the low gear mode, the default starting gear is 2nd gear.

[0082] According to the calculated vehicle mass, the load is divided into three levels: when the vehicle mass is less than or equal to 20t, it is M1; when the vehicle mass is between 20t and 30t, it is M2; when the vehicle mass is greater than 30t, it is M3.

[0083] When the vehicle load is at level M1, the vehicle does not maintain a low gear and performs normal gear shifting according to the vehicle speed and throttle.

[0084] When the vehicle load is at level M2, the vehicle enters low gear and holds it. When the throttle exceeds 80% and the motor speed exceeds 2200r / min, the TCU does not actively shift up, but keeps the throttle at 80% of the torque value. When the speed exceeds the limit of 2600r / min, the upshift operation is performed.

[0085] When the vehicle load is at level M3, the slope is identified by the slope sensor signal. When the slope exceeds 5%, the TCU automatically switches to 1st gear when the vehicle speed is lower than 2km / h. Starting from 1st gear, the motor speed is used as the limit value. When the motor speed exceeds 2800r / min, it shifts from 1st gear to 2nd gear. When the motor speed exceeds 2600r / min, it shifts from 2nd gear to 3rd gear.

[0086] Example 6

[0087] A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation comprises a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, wherein the motor controller is used for speed regulation during gear shifting and calculation output of required torque, and the gearbox controller is used for controlling gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform mass estimation using the least square method, and then a low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs low gear holding control according to a ramp sensor signal, motor speed and vehicle speed signal.

[0088] When the vehicle gear is greater than or equal to 3rd gear, the vehicle enters the normal gear shift mode, and when the vehicle gear is lower than 3rd gear, it enters the low gear mode. In the low gear mode, the default starting gear is 2nd gear.

[0089] According to the calculated vehicle mass, the load is divided into three levels: when the vehicle mass is less than or equal to 20t, it is M1; when the vehicle mass is between 20t and 30t, it is M2; when the vehicle mass is greater than 30t, it is M3.

[0090] When the vehicle load is at level M1, the vehicle does not maintain a low gear and performs normal gear shifting according to the vehicle speed and throttle.

[0091] When the vehicle load is at level M2, the vehicle enters low gear and holds it. When the throttle exceeds 80% and the motor speed exceeds 2200r / min, the TCU does not actively shift up, but keeps the throttle at 80% of the torque value. When the speed exceeds the limit of 2600r / min, the upshift operation is performed.

[0092] When the vehicle load is at level M3, the slope is identified by the slope sensor signal. When the slope exceeds 5%, the TCU automatically switches to 1st gear when the vehicle speed is lower than 2km / h. Starting from 1st gear, the motor speed is used as the limit value. When the motor speed exceeds 2800r / min, it shifts from 1st gear to 2nd gear. When the motor speed exceeds 2600r / min, it shifts from 2nd gear to 3rd gear.

[0093] Among them, the formula of recursive least squares method is as follows:

[0094]

[0095] In the formula, y(k) is the system observation value, and are the estimated values ​​of system parameters, is the parameter to be identified, and the forgetting factor is introduced to weaken the influence of past information on the current parameter estimation, where λ is the forgetting factor, and its iterative formula is as follows:

[0096]

[0097]

[0098]

[0099] Where K(k) is the recursive gain matrix and P(k) is the covariance matrix.

[0100] Example 7

[0101] A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation comprises a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, wherein the motor controller is used for speed regulation during gear shifting and calculation output of required torque, and the gearbox controller is used for controlling gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform mass estimation using the least square method, and then a low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs low gear holding control according to a ramp sensor signal, motor speed and vehicle speed signal.

[0102] When the vehicle gear is greater than or equal to 3rd gear, the vehicle enters the normal gear shift mode, and when the vehicle gear is lower than 3rd gear, it enters the low gear mode. In the low gear mode, the default starting gear is 2nd gear.

[0103] According to the calculated vehicle mass, the load is divided into three levels: when the vehicle mass is less than or equal to 20t, it is M1; when the vehicle mass is between 20t and 30t, it is M2; when the vehicle mass is greater than 30t, it is M3.

[0104] When the vehicle load is at level M1, the vehicle does not maintain a low gear and performs normal gear shifting according to the vehicle speed and throttle.

[0105] When the vehicle load is at level M2, the vehicle enters low gear and holds it. When the throttle exceeds 80% and the motor speed exceeds 2200r / min, the TCU does not actively shift up, but keeps the throttle at 80% of the torque value. When the speed exceeds the limit of 2600r / min, the upshift operation is performed.

[0106] When the vehicle load is at level M3, the slope is identified by the slope sensor signal. When the slope exceeds 5%, the TCU automatically switches to 1st gear when the vehicle speed is lower than 2km / h. Starting from 1st gear, the motor speed is used as the limit value. When the motor speed exceeds 2800r / min, it shifts from 1st gear to 2nd gear. When the motor speed exceeds 2600r / min, it shifts from 2nd gear to 3rd gear.

[0107] Among them, the formula of recursive least squares method is as follows:

[0108]

[0109] In the formula, y(k) is the system observation value, and are the estimated values ​​of system parameters, is the parameter to be identified, and the forgetting factor is introduced to weaken the influence of past information on the current parameter estimation, where λ is the forgetting factor, and its iterative formula is as follows:

[0110]

[0111]

[0112]

[0113] Where K(k) is the recursive gain matrix and P(k) is the covariance matrix.

[0114] Simplify the longitudinal dynamics of the vehicle into F t =ma, combined with the recursive least squares method, it can be equivalent to the following formula:

[0115] y(k)=a(k)

[0116]

[0117]

[0118] Where a is the acceleration value, i g represents the gearbox transmission ratio, i0 represents the rear axle transmission ratio, η represents the transmission efficiency, r represents the wheel radius, m represents the vehicle mass, and T(k) represents the motor torque.

[0119] Example 8

[0120] A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation comprises a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator, wherein the motor controller is used for speed regulation during gear shifting and calculation output of required torque, and the gearbox controller is used for controlling gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform mass estimation using the least square method, and then a low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs low gear holding control according to a ramp sensor signal, motor speed and vehicle speed signal.

[0121] When the vehicle gear is greater than or equal to 3rd gear, the vehicle enters the normal gear shift mode, and when the vehicle gear is lower than 3rd gear, it enters the low gear mode. In the low gear mode, the default starting gear is 2nd gear.

[0122] According to the calculated vehicle mass, the load is divided into three levels: when the vehicle mass is less than or equal to 20t, it is M1; when the vehicle mass is between 20t and 30t, it is M2; when the vehicle mass is greater than 30t, it is M3.

[0123] When the vehicle load is at level M1, the vehicle does not maintain a low gear and performs normal gear shifting according to the vehicle speed and throttle.

[0124] When the vehicle load is at level M2, the vehicle enters low gear and holds it. When the throttle exceeds 80% and the motor speed exceeds 2200r / min, the TCU does not actively shift up, but keeps the throttle at 80% of the torque value. When the speed exceeds the limit of 2600r / min, the upshift operation is performed.

[0125] When the vehicle load is at level M3, the slope is identified by the slope sensor signal. When the slope exceeds 5%, the TCU automatically switches to 1st gear when the vehicle speed is lower than 2km / h. Starting from 1st gear, the motor speed is used as the limit value. When the motor speed exceeds 2800r / min, it shifts from 1st gear to 2nd gear. When the motor speed exceeds 2600r / min, it shifts from 2nd gear to 3rd gear.

[0126] Among them, the formula of recursive least squares method is as follows:

[0127]

[0128] In the formula, y(k) is the system observation value, and are the estimated values ​​of system parameters, is the parameter to be identified, and the forgetting factor is introduced to weaken the influence of past information on the current parameter estimation, where λ is the forgetting factor, and its iterative formula is as follows:

[0129]

[0130]

[0131]

[0132] Where K(k) is the recursive gain matrix and P(k) is the covariance matrix.

[0133] Simplify the longitudinal dynamics of the vehicle into F t =ma, combined with the recursive least squares method, it can be equivalent to the following formula:

[0134] y(k)=a(k)

[0135]

[0136]

[0137] Where a is the acceleration value, i g represents the gearbox transmission ratio, i0 represents the rear axle transmission ratio, η represents the transmission efficiency, r represents the wheel radius, m represents the vehicle mass, and T(k) represents the motor torque.

[0138] The acceleration includes the vehicle's own acceleration a v and the drag acceleration a caused by other drag n , the vehicle is in neutral state, F(k) is 0, and the acceleration value measured by the acceleration sensor is a, which includes the vehicle's own acceleration a v and the gravitational acceleration component a g , where α is the component of gravity acceleration in the direction of travel:

[0139] a=a v +a g sinα

[0140]

[0141] Resistance acceleration caused by other resistances a n, remains unchanged for a period of time before and after the gear shift, a n is the acceleration sensor signal value when in neutral or without torque output, and the vehicle mass m is then calculated.

[0142] The present invention discloses a method for controlling a 6-speed AMT in low gear of a pure electric vehicle based on mass estimation, and adopts the least square method to realize load estimation of the engineering vehicle, so as to solve the problem of controlling a low gear caused by different loads due to large load fluctuations of the actual working vehicle; and solves the problem of unexpected upshifting in low gear of the pure electric engineering vehicle when the load is low and the torque is large.

[0143] It should be noted that the description of the above technical solutions is exemplary, and this specification can be embodied in different forms and should not be interpreted as being limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are limited only by the scope of the claims.

[0144] The various aspects disclosed for describing the present specification and claims are merely examples, and therefore, the present specification and claims are not limited to the details shown. In the above description, when the detailed description of the related known functions or configurations is determined to be unnecessary to obscure the focus of the present specification and claims, the detailed description will be omitted.

[0145] In the case of using “including”, “having” and “comprising” described in the present specification, unless otherwise used, there may also be another part or other parts, and the terms used may generally be in the singular but may also represent the plural form.

[0146] Finally, it should be pointed out that the above content is a further detailed description of the invention in combination with specific implementation methods. It cannot be considered that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, simple replacements made without departing from the concept of the present invention should be regarded as belonging to the protection scope of the present invention. The above embodiments are only more representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments, and there can be many variations. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention should be considered to belong to the protection scope of the present invention.

[0147] At the same time, it should be noted that the description of the above technical solutions is exemplary, and this specification can be embodied in different forms and should not be construed as being limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are limited only by the scope of the claims. The features of the various embodiments of the present invention may be partially or completely combined or spliced ​​with each other, and may be performed in various different configurations as those skilled in the art may fully understand. The embodiments of the present invention may be performed independently of each other, or may be performed together in a mutually dependent relationship.

[0148] For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and the above structures should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for controlling low gear holding of a 6-speed AMT of a pure electric vehicle based on mass estimation, characterized in that: It includes a gearbox controller and its corresponding gearbox, a motor controller and its corresponding motor actuator. The motor controller is used for speed regulation during the gear shifting process and calculation output of the required torque. The gearbox controller is used for controlling the gear shifting, load mass estimation and low gear holding control. The vehicle acceleration sensor signal, gear signal, vehicle speed, gearbox transmission ratio, rear axle transmission ratio and motor torque parameters are obtained to perform the least squares method mass estimation, and then the low gear holding mode is divided according to the estimated mass. Finally, the gearbox controller performs the low gear holding control according to the ramp sensor signal, motor speed and vehicle speed signal; When the vehicle gear is greater than or equal to 3rd gear, the vehicle enters the normal gear shift mode, and when the vehicle gear is less than 3rd gear, it enters the low gear mode. According to the calculated vehicle mass, the load is divided into three levels, from small to large, namely M1, M2 and M3; When the vehicle load is at level M1, the vehicle does not hold a low gear and performs normal gear shifting according to the vehicle speed and throttle. When the vehicle load is at the M2 level, the vehicle enters the low gear and holds it. When the throttle exceeds 80% and the motor speed exceeds 2200r / min, the TCU does not actively shift up, but keeps the throttle at 80% of the torque value. When the speed exceeds the 2600r / min limit, the upshift operation is performed. When the vehicle load is at level M3, the slope is identified by the slope sensor signal. When the slope exceeds 5%, the TCU automatically switches to 1st gear when the vehicle speed is lower than 2km / h. Starting from 1st gear, the motor speed is used as the limit value. When the motor speed exceeds 2800r / min, it shifts from 1st gear to 2nd gear. When the motor speed exceeds 2600r / min, it shifts from 2nd gear to 3rd gear.

2. The method for controlling the low gear position of a 6-speed AMT of a pure electric vehicle based on mass estimation according to claim 1 is characterized in that: The formula for recursive least squares is as follows: In the formula, y(k) is the system observation value, and are the estimated values ​​of system parameters, is the parameter to be identified, and the forgetting factor is introduced to weaken the influence of past information on the current parameter estimation, where λ is the forgetting factor, and its iterative formula is as follows: Where K(k) is the recursive gain matrix and P(k) is the covariance matrix.

3. The method for controlling the low gear position of a 6-speed AMT of a pure electric vehicle based on mass estimation according to claim 2 is characterized in that: Simplify the longitudinal dynamics of the vehicle into F t =ma, combined with the recursive least squares method, it can be equivalent to the following formula: y(k)=a(k) Where a is the acceleration value, i g represents the gearbox transmission ratio, i0 represents the rear axle transmission ratio, η represents the transmission efficiency, r represents the wheel radius, m represents the vehicle mass, and T(k) represents the motor torque.

4. The method for controlling the low gear position of a 6-speed AMT of a pure electric vehicle based on mass estimation according to claim 3 is characterized in that: The acceleration includes the vehicle's own acceleration a v and the drag acceleration a caused by other drag n , the vehicle is in neutral state, F(k) is 0, and the acceleration value measured by the acceleration sensor is a, which includes the vehicle's own acceleration a v and the gravitational acceleration component a g , where α is the component of gravity acceleration in the direction of travel: a=a v +a g sinα Resistance acceleration caused by other resistances a n , remains unchanged for a period of time before and after the gear shift, a n is the acceleration sensor signal value when in neutral or without torque output, and the vehicle mass m is then calculated.

5. The method for controlling the low gear position of a 6-speed AMT of a pure electric vehicle based on mass estimation according to claim 1 is characterized in that: When the vehicle mass is less than or equal to 20t, it is class M1; when the vehicle mass is between 20t and 30t, it is class M2; when the vehicle mass is greater than 30t, it is class M3.

6. The method for controlling the low gear position of a 6-speed AMT of a pure electric vehicle based on mass estimation according to claim 1 is characterized in that: In low gear mode, the default starting gear is 2nd gear.

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