Motor torque control method and system and vehicle

Abstract

The invention discloses a motor torque control method and system and a vehicle, and the method comprises the steps: determining the target angular velocity omega em of a motor based on the obtained actual angular velocity omega em of the motor, the actual angular velocity omega w of a wheel and the actual torque Tem of the motor; processing the target angular velocity omega em of the motor and the actual angular velocity omega em of the motor to obtain an angular velocity error omega err of the motor; and when the motor torque is reversed, double closed-loop adjustment is performed on an external request torque Treq based on the motor angular velocity error omegaerr and the motor angular acceleration error to obtain a double closed-loop motor torque Tdcl, and the double closed-loop motor torque Tdcl is output as a motor target torque Ttar. According to the invention, quick response can be realized during motor torque reversing, motor shaking is reduced, smooth transition of gear clearance during torque reversing is ensured, and driving experience is improved.

Description

Technical Field

[0001] This invention belongs to the field of drive motor control for new energy vehicles, specifically relating to a motor torque control method, system, and vehicle. Background Technology

[0002] During vehicle operation, the drive motor involves switching between positive and negative torque, i.e., the transition between driving and braking / coasting energy recovery states. When the motor switches between positive and negative torque (i.e., the motor torque reverses direction, the motor torque crosses zero), the meshing surface of the reducer gears will change. Due to the presence of transmission backlash, during the meshing surface transition, the motor torque drives the motor rotor and the driving gear to accelerate or decelerate. This creates a speed difference between the driving and driven gears, resulting in an impact at the moment of meshing, causing vibration and affecting the driving experience.

[0003] There are two main existing methods for motor torque control. The first method controls the motor according to a calibrated zero-crossing torque curve during torque commutation, outputting the corresponding target torque. This is essentially feedforward control, with limited adaptability to different vehicle operating conditions and service life. The second method uses a closed-loop angular velocity adjustment (control) based on the motor's angular velocity. However, during torque commutation, the motor's angular velocity changes rapidly, resulting in a slow response and poor actual control performance due to jitter. Summary of the Invention

[0004] The purpose of this invention is to provide a motor torque control method, system, and vehicle to respond quickly during motor torque commutation, reduce motor vibration, ensure a smooth transition of gear backlash during torque commutation, and improve the driving experience.

[0005] In a first aspect, the present invention provides a motor torque control method, comprising:

[0006] Based on the obtained actual angular velocity ω of the motor em The actual angular velocity ω of the wheel w Actual motor torque T em Determine the target angular velocity Ω of the motor em .

[0007] For the target angular velocity Ω of the motor em The actual angular velocity ω of the motor em The process is performed to obtain the motor angular velocity error ω. err .

[0008] For the motor angular velocity error ω err Differentiate to obtain the motor angular acceleration error.

[0009] When the motor torque reverses, based on the motor angular velocity error ω err Motor angular acceleration error external requested torque T re double closed loop regulation to obtain double closed loop motor torque T dcl double closed loop motor torque T dcl as motor target torque T tar output.

[0010] Preferably, during the double closed loop regulation, if motor angular velocity error ω err is less than preset angular velocity error threshold, and motor angular acceleration error is less than preset angular acceleration error threshold (i.e. when motor angular velocity error converges to a certain degree and motor angular acceleration error converges to a certain degree), exit the double closed loop regulation, and restore motor target torque T tar double closed loop motor torque T dcl to external requested torque T req . This can prevent insufficient dynamic response (such as speed fluctuation caused by torque mutation) due to exiting the double closed loop regulation too early, or system delay (such as unnecessary closed loop regulation continuously consuming computing resources) due to exiting the double closed loop regulation too late.

[0011] Preferably, when motor torque is not commutated, external requested torque T req is output as motor target torque T tar (i.e. without double closed loop regulation). When motor torque is not commutated (i.e. when motor torque direction is not changed), there is basically no jitter, and at this time, external requested torque T req is directly output as motor target torque T tar , reducing control level delay and improving response speed.

[0012] Preferably, the method for determining motor target angular velocity Ω em is as follows:

[0013] The obtained motor actual angular velocity ω em , wheel actual angular velocity ω w , and motor actual torque T em are input into a Luenberger observer to calculate and output wheel estimated angular velocity The Luenberger observer is as follows:

[0014]

[0015] denotes a state variable matrix, denotes half shaft torsion estimated angle, denotes motor estimated angular velocity, denotes wheel estimated angular velocity, denotes half shaft torsion estimated angular velocity, represents an estimated angular acceleration of the motor, represents an estimated angular acceleration of the wheel, u represents a control variable matrix, u = [0 T em 0] T , y represents a correction term matrix, y = [0 ω em ω w ], represents an output variable matrix, C represents a preset mapping relationship matrix, L represents a preset correction coefficient matrix, and A and B represent system structure parameter matrices determined according to vehicle hardware parameters.

[0016] If there is no gap in the system, there is no speed difference between the driving gear and the driven gear of the reducer, and the angular velocity of the driving gear (that is, the angular velocity of the motor) is equal to the angular velocity of the driven gear (that is, the angular velocity of the wheel) multiplied by the speed ratio of the reducer. Therefore, the motor target angular velocity (that is, the ideal angular velocity of the motor) Ω em is calculated by using the formula:

[0017] The motor, half shaft and wheel end load are regarded as a double-mass torsional vibration system. A Luenberger observer is built, which captures the elastic deformation of the transmission system by estimating the angle of the half shaft torsion, compensates for the instantaneous difference between the wheel and motor angular velocities caused by the flexibility of the half shaft, and improves the accuracy of the wheel estimated angular velocity ; and avoids the errors caused by directly using the actual angular velocity of the wheel ω w (may be distorted due to sensor noise or slipping) or the actual angular velocity of the motor ω em (not considering the reduction ratio and transmission loss). The state estimation is corrected in real time through the feedback term , which reduces the influence of model mismatch on the wheel estimated angular velocity. High-precision, anti-disturbance and low-delay wheel angular velocity estimation is achieved, and then the motor target angular velocity with better robustness is obtained.

[0018] Preferably, the system structure parameter matrices A and B are respectively:

[0019]

[0020] wherein k represents the stiffness of the half shaft (unit: Nm / rad), J em represents the inertia of the motor and the reducer (unit: kg·m 2 ), R represents the radius of the wheel tire (unit: m), m represents the mass of the whole vehicle (unit: kg), and c represents the damping of the half shaft (unit: Nm·s / rad). k, J em , R, m, c and i all belong to known vehicle hardware parameters.

[0021] ​Preferably, the preset mapping relationship matrix C = [0 1 1], and the preset correction coefficient matrix L = [0 l1 l2] T . Wherein, l1 represents a preset first correction coefficient, l2 represents a preset second correction coefficient, and values of l1 and l2 make a real part of a characteristic root of the matrix A-L*C negative (i.e. the characteristic root of the matrix A-L*C is located in a left half of a complex plane, and a real part is negative). C reflects a mapping relationship from a state variable matrix to an output variable matrix , l1 reflects a correction amplitude of a motor estimated angular velocity output by the Luenberger observer using an actual angular velocity of the motor, the larger the value of l1 is, the closer the motor estimated angular velocity output by the Luenberger observer is to a real motor angular velocity, and l2 reflects a correction amplitude of a wheel estimated angular velocity output by the Luenberger observer using an actual angular velocity of the wheel, the larger the value of l2 is, the closer the wheel estimated angular velocity output by the Luenberger observer is to a real wheel angular velocity.

[0022] Preferably, a method for obtaining a motor angular velocity error ω err includes:

[0023] An original angular velocity error Err is calculated by using a formula: Err = ω em - ω em .

[0024] A current step filtered error Err fil [t] is calculated by using a formula: Err fil [t] = α * Err + (1-α) * Err fil [t-1], wherein α represents a preset filtering coefficient, Err fil [t-1] represents a previous step filtered error, and an initial value of the filtered error is 0.

[0025] The motor angular velocity error ω err is calculated by using a formula: ω fil = Err - Err err [t].

[0026] Err fil [t] = α * Err + (1-α) * Err fil[t-1] is equivalent to a filter, which filters out the component of the error term that is not needed to be concerned. This component may be caused by the error of the parameter setting of the Luenberger observer (such as the error of the wheel tire radius R or the speed ratio i of the reducer from the true parameter), that is, the parameters of the Luenberger observer inevitably differ from the true system, which causes a stable deviation between the estimated angular velocity of the motor and the actual angular velocity of the motor, resulting in a stable deviation between the motor compensation torque value and the external request torque and the actual response of the motor. By filtering, this deviation (but not filtering the motor jitter) can be filtered out, so that the low-frequency component of the motor angular velocity error can converge to zero, so that the motor angular velocity error ω err can reflect the true situation of the motor angular velocity.

[0027] Preferably, the double closed-loop regulation includes proportional regulation (i.e. P regulation) of the angular velocity loop and proportional integral regulation (i.e. PI regulation) of the angular acceleration loop.

[0028] The double closed-loop motor torque

[0029] wherein k p1 represents a preset first proportional regulation coefficient, k p2 represents a preset second proportional regulation coefficient, and k i represents a preset integral regulation coefficient.

[0030] When the motor torque commutates (i.e. the motor torque crosses zero), the motor angular velocity changes very quickly. Through the double closed-loop regulation of the angular velocity loop and the angular acceleration loop, the motor angular velocity and the motor angular acceleration can both be smoothly transitioned, the torque response is fast, the motor jitter is reduced, the smooth transition of the gear over the gap is ensured when the torque commutates, and the driving experience is improved.

[0031] Preferably, when the double closed-loop regulation is exited, the motor target torque T tar is switched to the external request torque T dcl in accordance with a preset gradient ΔT. req Avoids the instantaneous switching impact (such as torque step change) caused by directly switching T dcl to T req , and improves the driving smoothness.

[0032] In a second aspect, the present application provides a motor torque control system, which comprises a controller configured to perform the above motor torque control method.

[0033] In a third aspect, the present application provides a vehicle comprising the above motor torque control system.

[0034] The motor torque control method of the embodiment of the present application can realize fast response of motor torque commutation, weaken torque impact when the gear meshing surface of the reducer switches, reduce motor jitter, ensure smooth transition of gear over clearance when torque commutation, and improve driving experience. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The figure is a motor torque control principle diagram in the embodiment of the present application.

[0036] Figure 2 The figure is a motor torque control method flow chart in the embodiment of the present application.

[0037] Figure 3 The figure is a method flow chart for determining motor target angular velocity Ω em in the embodiment of the present application.

[0038] Figure 4 The figure is a method flow chart for obtaining motor angular velocity error ω err in the embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to be able to understand the features and technical contents of the embodiments of the present application more thoroughly, the implementation of the embodiments of the present application will be described in detail below with reference to the accompanying drawings, which are only used for reference and are not intended to limit the embodiments of the present application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0041] In the following description, "some embodiments" are related to a subset of all possible embodiments, but it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0042] As shown in Figure 1 , Figure 2 , the motor torque control method in the embodiment of the present application comprises:

[0043] S1, based on the obtained motor actual angular velocity ω em , wheel actual angular velocity ω w , motor actual torque T em , determine the motor target angular velocity Ω em , and then execute S2.

[0044] As shown in Figure 3 , in some embodiments, the method for determining the motor target angular velocity Ω em is:

[0045] S11, the acquired motor actual angular velocity ω em , wheel actual angular velocity ω w , motor actual torque T em input the Luenberger observer, calculate and output the wheel estimated angular velocity

[0046] wherein the Luenberger observer is:

[0047]

[0048] denotes a state variable matrix, denotes a half shaft torsion estimated angle, denotes a motor estimated angular velocity, denotes a wheel estimated angular velocity, denotes a half shaft torsion estimated angular velocity, denotes a motor estimated angular acceleration, denotes a wheel estimated angular acceleration, u denotes a control variable matrix, u = [0 T em 0] T , y denotes a correction term matrix, y = [0 ω em ω w ], denotes an output variable matrix, C denotes a preset mapping relationship matrix, L denotes a preset correction coefficient matrix, A and B denote system structure parameter matrices determined according to vehicle hardware parameters.

[0049] In some embodiments, the system structure parameter matrices A and B are respectively:

[0050]

[0051] wherein k denotes half shaft stiffness (unit: Nm / rad), J em denotes motor and reducer inertia (unit: kg·m 2 ), R denotes wheel tire radius (unit: m), m denotes vehicle mass (unit: kg), c denotes half shaft damping (unit: Nm·s / rad), and i denotes reducer speed ratio. k, J em , R, m, c, and i all belong to known vehicle hardware parameters.

[0052] The preset mapping relationship matrix C = [0 1 1], and the preset correction coefficient matrix L = [0 l1 l2] T .

[0053] Wherein, l1 represents a preset first correction coefficient, l2 represents a preset second correction coefficient, and the values of l1 and l2 make the real part of the eigenvalue of the matrix A-L*C negative (that is, the eigenvalue of the matrix A-L*C is located in the left half of the complex plane, and the real part is negative).

[0054] S12, the formula is used: The motor target angular velocity (that is, the ideal angular velocity of the motor) Ω em .

[0055] S2, the motor target angular velocity Ω em , the actual angular velocity of the motor ω em is processed to obtain the motor angular velocity error ω err , and then S3 is executed.

[0056] As Figure 4 shown, in some embodiments, the method of obtaining the motor angular velocity error ω err includes:

[0057] S21, the formula is used: Err=Ω em -ω em , and the original angular velocity error Err is calculated.

[0058] S22, the formula is used: Err fil [t]=α*Err+(1-α)*Err fil [t-1] is calculated to obtain the error Err fil [t] filtered at the current step. Wherein, α represents a preset filtering coefficient, Err fil [t-1] represents the error filtered at the previous step, and the initial value of the filtered error is 0, that is, Err fil [0]=0.

[0059] S23, the formula is used: ω err =Err-Err fil [t] is calculated to obtain the motor angular velocity error ω err .

[0060] S3, the motor angular velocity error ω err is derived to obtain the motor angular acceleration error , and then S4 is executed.

[0061] S4, it is judged whether the motor torque is reversed (judged according to the actual torque of the motor, such as the actual torque of the motor changes from positive to negative, or the actual torque of the motor changes from negative to positive), if yes, S6 is executed, otherwise S5 is executed.

[0062] S5, the external request torque T req is taken as the motor target torque Ttar output (i.e., T tar req ), and then end.

[0063] S6, based on the motor angular velocity error ω err , the motor angular acceleration error double closed loop regulation on the external request torque T req (e.g., the motor torque requested by the vehicle controller), to obtain a double closed loop motor torque T dcl , and then perform S7.

[0064] In some embodiments, the double closed loop regulation includes: proportional regulation (i.e., P regulation) of the angular velocity loop and proportional integral regulation (i.e., PI regulation) of the angular acceleration loop.

[0065] double closed loop motor torque T

[0066] wherein k p1 represents a preset first proportional regulation coefficient, k p2 represents a preset second proportional regulation coefficient, and k i represents a preset integral regulation coefficient.

[0067] S7, taking the double closed loop motor torque T dcl as the motor target torque T tar output (i.e., T tar = T dcl ), and then perform S8.

[0068] S8, judge whether the motor angular velocity error ω err < Δω ert and the motor angular acceleration error If yes, perform S9, otherwise return to perform S7. Wherein Δω ert represents a preset angular velocity error threshold, represents a preset angular acceleration error threshold.

[0069] S9, exit the double closed loop regulation, so that the motor target torque T tar restored from the double closed loop motor torque T dcl to the external request torque T req , and then end.

[0070] In some embodiments, when exiting the double closed loop regulation, the motor target torque T tar is gradually restored from the double closed loop motor torque T dcl to the external request torque T req according to a preset gradient ΔT.

[0071] ​In addition, the embodiment of the present application further provides a motor torque control system, which comprises a controller configured to execute the motor torque control method.

[0072] In addition, the embodiment of the present application further provides a vehicle comprising the motor torque control system.

[0073] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method of motor torque control, characterized by, Comprising: Based on the acquired motor actual angular velocity ω em , wheel actual angular velocity ω w , motor actual torque T em , determine motor target angular velocity Ω em ; processing the motor target angular velocity Ω em , the motor actual angular velocity ω em , to obtain the motor angular velocity error ω err ; The motor angular velocity error ω err derivation, the motor angular acceleration error When the motor torque reverses, based on the motor angular velocity error ω err , the motor angular acceleration error The external request torque T req is double closed loop regulated to obtain the double closed loop motor torque T dcl , the double closed loop motor torque T dcl is output as the motor target torque T tar .

2. The motor torque control method according to claim 1, characterized in that: During the dual closed-loop regulation process, if the motor angular velocity error ω err Less than the preset angular velocity error threshold, and the motor angular acceleration error If the angular acceleration error is less than the preset threshold, the dual closed-loop regulation is exited, and the target torque T of the motor is achieved. tar Torque T of the dual closed-loop motor dcl Restore to externally requested torque T req ; When the motor torque is not commutated, the external requested torque T req As the motor target torque T tar Output.

3. The electric motor torque control method of claim 2, wherein, Determine the target angular velocity Ω of the motor em The method is as follows: The acquired motor actual angular velocity ω em , wheel actual angular velocity ω w , motor actual torque T em The input Luenberger observer, calculates and outputs the wheel estimated angular velocity The Luenberger observer is: represents a state variable matrix, represents a half shaft torsion estimated angle, represents a motor estimated angular velocity, represents a wheel estimated angular velocity, represents a half shaft torsion estimated angular velocity, represents a motor estimated angular acceleration, represents a wheel estimated angular acceleration, u represents a control variable matrix, u = [0 T em 0] T , y represents a correction term matrix, y = [0 ω em ω w ], represents an output variable matrix, C represents a preset mapping relationship matrix, L represents a preset correction coefficient matrix, A and B represent system structure parameter matrices determined according to vehicle hardware parameters; The motor target angular velocity Ω is calculated by using the formula: em ; wherein i represents the speed ratio of the reducer.​ 4. The motor torque control method according to claim 3, characterized in that: The system structure parameter matrices A, B are respectively: where k represents the half shaft stiffness, J em represents the motor and reducer inertia, R represents the wheel tire radius, m represents the vehicle mass, and c represents the half shaft damping.

5. The motor torque control method according to claim 4, characterized in that: The preset mapping relationship matrix C = [0 1 1]; The preset correction coefficient matrix L = [0 l1 l2] T ; Wherein, l1 represents a preset first correction coefficient, l2 represents a preset second correction coefficient, the values of l1, l2 make the real part of the eigenvalue of the matrix A-L*C negative.

6. The electric motor torque control method according to any one of claims 1 to 5, characterized by, A method of obtaining an electrical motor angular velocity error ω err comprises: The original angular velocity error Err is calculated using the formula: Err = Ω em - ω em , using the formula: Err fil [t] = a * Err + (1 - a) * Err fil [t-1], the error Err fil [t] filtered at the current step is calculated; where a represents a preset filter coefficient, Err fil [t-1] represents the error filtered at the previous step, and the initial value of the filtered error is 0. Using the formula: ω err = Err - Err fil [t], the motor angular velocity error ω err is calculated.

7. The motor torque control method according to any one of claims 1 to 5, characterized in that: The double closed-loop regulation includes proportional regulation of the angular velocity loop and proportional integral regulation of the angular acceleration loop; The double closed loop motor torque wherein k p1 represents a preset first proportional adjustment coefficient, k p2 represents a preset second proportional adjustment coefficient, k i represents a preset integral adjustment coefficient.

8. The electric motor torque control method according to any one of claims 2 to 5, characterized by: When exiting the double closed loop regulation, the motor target torque T tar is set to the external requested torque T dcl in steps of a preset gradient ΔT req .

9. An electric machine torque control system comprising a controller, characterized by: The controller is configured to perform the motor torque control method according to any one of claims 1 to 8.

10. A vehicle characterized by: The motor torque control system according to claim 9. The motor torque control system according to claim 9.

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