A method for driving slip control of a p4 configuration hybrid vehicle

Abstract

The application provides a driving anti-skid control method for a P4 configuration hybrid vehicle, aiming at solving the slip problem caused by the inconsistent speed of the middle and rear axles of the P4 configuration hybrid vehicle due to the double axle and double redundant power source and other factors. The control method comprises the following steps: S1, driving anti-skid entering condition judgment; S2, initialization of slip correction torque; S3, motor torque adjustment; S4, output torque compensation result acquisition demand torque. The input control quantity of the application includes: front and rear axle speed signal, slip confirmation signal, torque increase and decrease timing signal and motor step adjustment torque signal; the whole algorithm can improve the driving stability and safety of the P4 configuration hybrid vehicle, and help to prolong the tire life and fully exert the advantages of double axle and double power source driving.

Description

Technical Field

[0001] This invention relates to the field of hybrid vehicle control, and more specifically to a method for anti-skid control of P4 configuration hybrid vehicles. Background Technology

[0002] Traditional gasoline-powered commercial vehicles have poor adaptability to various operating conditions. Drive wheel slippage frequently occurs on soft, muddy roads and in mountainous areas, affecting not only the vehicle's passability and stability but also increasing fuel consumption and deteriorating emissions. P4 parallel hybrid vehicles, with their dual-axle, dual-power drive, offer stronger overall performance and are widely used in heavy-duty trucks and other commercial applications. However, during actual vehicle operation, slippage of the motor drive shaft is frequently observed in P4 configurations at low speeds, particularly during low-speed starts and turns. This slippage shortens the lifespan of components such as tires and affects driving reliability and stability. For heavy-duty commercial vehicles, drive wheel slippage poses a significant threat to overall vehicle safety. Therefore, there is an urgent need to develop a drive anti-slip control algorithm to adjust torque and prevent slippage without altering the P4 configuration.

[0003] Currently available technologies include, for example, the invention patent published on December 10, 2021, publication number: CN113771833A, "A P4 configuration hybrid vehicle power domain system and its control method." This invention patent uses a CAN communication gateway method to replace traditional distributed control, making up for the shortcomings of traditional methods in coordinating the dual power sources and AMT of P4 configuration hybrid vehicles. However, it does not propose a related control method for drive anti-slip. Another example is the invention patent published on April 14, 2020, publication number: CN109624732A, "A multi-layer drive anti-slip control method suitable for electric wheel drive vehicles." This invention patent adopts a multi-layer drive anti-slip strategy and discusses the entry conditions and control methods for each layer of drive anti-slip. However, it only addresses multi-motor wheel-side drive. For P4 configurations with only a single motor, there is no hardware foundation for multi-layer control, so it cannot be used to solve the problem of easy slippage in P4 configuration hybrid vehicles. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention presents a drive anti-slip control method for P4 configuration hybrid vehicles. Employing a feedforward-predicting and feedback control approach, it addresses the single-axle slippage phenomenon that often occurs during driving due to the redundant arrangement of the drive axles and the different power sources of the two drive axles caused by the mismatch in speed between the two drive axles. By real-time acquisition of vehicle speed, load, and road surface adhesion information via CAN communication, the maximum adhesion limit of the slipping axle is calculated as a constraint variable. Then, slip confirmation information is collected to determine whether torque compensation control should be implemented. Finally, the required torque and the compensation torque are combined to minimize or eliminate drive slippage and ensure vehicle driving stability.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] Step 1: Determining the Conditions for Driving Anti-Slip Entry

[0007] The control algorithm monitors the rotational speed of each wheel on the front and rear axles. It uses the larger of the rotational speeds of the rear axle wheels relative to the front axle wheels as a criterion. If the relative speed exceeds the calibrated value, it indicates that the difference in rotational speed between the front and rear axles is too large, requiring anti-skid control intervention. Considering that turning, obstacle crossing, and slight changes in tire pressure can also cause differences in rotational speed between the front and rear axles, the criterion is modified to the average rotational speed of the left and right rear axles wheels. When the relative average rotational speed n... relative Greater than the rated slip speed n calibration When the slip confirmation signal is set to 1, the drive anti-slip function is activated, and the rear axle speed is adjusted by increasing or decreasing the motor torque until the relative average speed n is reached. relative Less than the rated slip speed n calibration The specific judgment conditions are expressed as follows:

[0008]

[0009] In equation (1) n front_axle n is the front axle speed. relative n is the average speed of the rear axle. rear_left n rear-right These correspond to the speeds of the left and right wheels of the rear axle, respectively, n calibration The calibrated slip speed is the P4 configuration motor drive shaft, which is prone to slippage, but the possibility of engine drive shaft slippage cannot be ruled out. Therefore, the above speeds are all absolute values, corresponding to the two situations of torque increase and torque decrease. In addition to judging whether the slip confirmation signal is valid, it is also necessary to monitor the vehicle status. The vehicle must be in drive mode, the clutch must be engaged, and the gearbox must not be shifting gears at the same time. If any of the above conditions are not met, the drive anti-slip cannot be entered.

[0010] Step 2: Initialize slip correction torque

[0011] After the anti-slip entry conditions are met, the initial slip correction torque T com (0) Set to 0 Nm and perform step increase or step decrease torque control; when the slip confirmation signal is 0, the initial slip correction torque T com (0) is also reset to 0Nm, indicating that anti-slip control is not needed at this time and the anti-slip function is not working;

[0012] Step 3: Adjusting the motor torque

[0013] After initialization, the torque boosting module activates when the rear axle speed is lower than the front axle speed, the slip confirmation signal is 1, and the initial slip correction torque T is set. com (0) Assign a value of 10 Nm, set the initial value of the torque timer t(0) to 0, and adjust the torque T by sliding it at the previous moment for each simulation step. com Based on (t-1), add a motor stepping torque ΔT. com_rise ; Based on the torque increment time t(t-1) of the previous moment, add a step time Δt, as shown in equation (2), until the slip correction torque T com (t) reaches the upper limit of torque T com_high Or the torque increase time t exceeds the torque increase duration limit t. rise_lim Then stop increasing torque, step torque ΔT com_rise The value is read from the table according to the vehicle speed PID control, as shown in equation (3);

[0014] T com (t)=T com (t-1)+ΔT com_rise (2)

[0015]

[0016] In equation (2), K p K i K d These are the proportional coefficient, integral coefficient, and differential coefficient, respectively, where u is the current relative wheel speed;

[0017] The torque reduction function is activated when the rear axle speed is higher than the front axle speed, and the slip confirmation signal is also 1. The initial slip correction torque T com (0) is assigned a value of -10 Nm, the initial value of the torque reduction timer t(0) is set to 0, and then the torque reduction process is performed. Each simulation step will slide and correct the torque T at the previous moment. com Based on (t-1), subtract one step reduction torque ΔT. com_decuction As shown in equation (4), a step time Δt is added to the torque reduction timer t(t-1) at the previous moment until the torque reduction timer t exceeds the upper limit of the torque reduction duration or the slip correction torque T. com(t) reaches the lower limit of torque T com_low Then exit torque reduction, step reduce torque ΔT com_decuction The value is read from a table based on the vehicle speed PID control, as shown in equation (5):

[0018] T com (t)=T com (t-1)-ΔT com_deduction (4)

[0019]

[0020] In equation (5), K p K i K d These are the proportional coefficient, integral coefficient, and differential coefficient, respectively, where u is the current relative wheel speed;

[0021] Step 4: Obtain the required torque by outputting the torque compensation result.

[0022] The control method uses the motor compensation torque T obtained from the torque increase / decrease module. com With the required torque T of the motor ISG The actual torque T is obtained by adding them together. req Furthermore, to improve driving safety, the required torque T of the motor is increased. ISG To implement amplitude limiting control, T is required. req The maximum adhesion torque of the road surface must not be exceeded. As shown in equation (6);

[0023]

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention proposes a drive anti-slip control method for P4 configuration hybrid vehicles. It establishes a reasonable drive anti-slip entry condition judgment. The judgment criterion is selected as the relative value of the average speed of the rear axle and the speed of the front axle, which avoids wheel speed inconsistency caused by other reasons. The whole algorithm adopts a dual approach of feedforward prediction and feedback control to adjust the motor compensation torque, making the actual torque output result more reliable. In this way, it can reduce or eliminate slippage caused by the characteristics of the motor itself, and improve the driving stability and safety of the whole vehicle.

[0026] 2. The anti-slip control method for P4 configuration hybrid vehicles proposed in this invention comprehensively considers both torque increase and torque decrease. It can not only solve the problem of motor shaft slippage, but also the slip problem. It uses PID control to adjust and update the step increase and step decrease torque values ​​to reduce the sudden power changes of the power source. Furthermore, it uses hysteresis elements such as wheel speed bandwidth to reduce the number of times the working mode is switched. While solving the slip problem, it ensures the smoothness of driving and further explores the application potential of P4 configuration. Attached Figure Description

[0027] The following description of the embodiments, taken in conjunction with the accompanying drawings, will make the embodiments readily understood, wherein:

[0028] Figure 1 A flowchart illustrating the anti-skid control method and control steps for a P4 configuration parallel hybrid drive vehicle according to an embodiment of the present invention:

[0029] Figure 2 This is a schematic diagram of a P4 configuration parallel hybrid drive vehicle according to an embodiment of the present invention;

[0030] Figure 2 Explanation of the reference numerals: 1-Front axle steering wheel, 2-Power domain controller PDU, 3-Central axle drive wheel, 4-Rear axle drive wheel, 5-Drive motor, 6-Rear axle two-speed automatic transmission, 7-Final reducer and differential assembly, 8-Power battery, 9-Final reducer and differential assembly, 10-Universal joint, 11-Central axle twelve-speed automatic transmission, 12-Engine. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0032] A steady-state control method for the power domain of a hub-and-wheel hydraulic hybrid vehicle is described below with reference to the accompanying drawings, but the invention is not limited to these embodiments.

[0033] Step 1: Determining the Conditions for Driving Anti-Slip Entry

[0034] Reference Appendix Figure 1Step 1: The control algorithm monitors the rotational speed of each wheel on the front and rear axles. The larger of the rotational speeds of the rear axle wheels relative to the front axle wheels is used as the judgment criterion. If the relative speed exceeds the calibrated value, it indicates that the difference in rotational speed between the front and rear axles is too large, requiring anti-skid control intervention. Considering that turning, obstacle crossing, and slight changes in tire pressure can also cause differences in rotational speed between the front and rear axles, the condition is modified to the average rotational speed of the left and right rear axles wheels. When the relative average rotational speed n... relative Greater than the rated slip speed n calibration When the slip confirmation signal is set to 1, the drive anti-slip function is activated, and the rear axle speed is adjusted by increasing or decreasing the motor torque until the relative average speed n is reached. relative Less than the rated slip speed n calibration The specific judgment conditions are expressed as follows:

[0035]

[0036] In equation (1) n front_axle n is the front axle speed. relative n is the average speed of the rear axle. rear_left n rear-right These correspond to the speeds of the left and right wheels of the rear axle, respectively, n calibration This refers to the calibrated slip speed, see attached document. Figure 2 The P4 configuration motor drive shaft is prone to slippage, but the possibility of engine drive shaft slippage cannot be ruled out. Therefore, the above speeds are all absolute values, corresponding to the two situations of increasing torque and decreasing torque. In addition to judging whether the slip confirmation signal is valid, it is also necessary to monitor the overall vehicle status. The vehicle must be in drive mode, the clutch must be engaged, and the gearbox must not be shifted at the same time. If any of the above conditions are not met, the drive anti-slip cannot be entered.

[0037] Step 2: Initialize slip correction torque

[0038] Reference Appendix Figure 1 Step 2, after the anti-slip entry conditions are met, the initial slip correction torque T com (0) Set to 0 Nm and perform step increase or step decrease torque control; when the slip confirmation signal is 0, the initial slip correction torque T com (0) is also reset to 0Nm, indicating that anti-slip control is not needed at this time and the anti-slip function is not working;

[0039] Step 3: Adjusting the motor torque

[0040] Reference Appendix Figure 1 Step 3: After initialization, the torque boosting module activates when the rear axle speed is lower than the front axle speed, the slip confirmation signal is 1, and the initial slip correction torque T is set. com(0) Assign a value of 10 Nm, set the initial value of the torque timer t(0) to 0, and adjust the torque T by sliding it at the previous moment for each simulation step. com Based on (t-1), add a motor stepping torque ΔT. com_rise ; Based on the torque increment time t(t-1) of the previous moment, add a step time Δt, as shown in equation (2), until the slip correction torque T com (t) reaches the upper limit of torque T com_high Or the torque increase time t exceeds the torque increase duration limit t. rise_lim Then stop increasing torque, step torque ΔT com_rise The value is read from the table according to the vehicle speed PID control, as shown in equation (3);

[0041] T com (t)=T com (t-1)+ΔT com_rise (2)

[0042]

[0043] In equation (2), K p K i K d These are the proportional coefficient, integral coefficient, and differential coefficient, respectively, where u is the current relative wheel speed;

[0044] The torque reduction function is activated when the rear axle speed is higher than the front axle speed, and the slip confirmation signal is also 1. The initial slip correction torque T com (0) is assigned a value of -10 Nm, the initial value of the torque reduction timer t(0) is set to 0, and then the torque reduction process is performed. Each simulation step will slide and correct the torque T at the previous moment. com Based on (t-1), subtract one step reduction torque ΔT. com_decuction As shown in equation (4), a step time Δt is added to the torque reduction timer t(t-1) at the previous moment until the torque reduction timer t exceeds the upper limit of the torque reduction duration or the slip correction torque T. com (t) reaches the lower limit of torque T com_low Then exit torque reduction, step reduce torque ΔT com_decuction The value is read from a table based on the vehicle speed PID control, as shown in equation (5):

[0045] T com (t)=T com (t-1)-ΔT com_deduction (4)

[0046]

[0047] In equation (5), K p K i Kd These are the proportional coefficient, integral coefficient, and differential coefficient, respectively, where u is the current relative wheel speed;

[0048] Step 4: Obtain the required torque by outputting the torque compensation result.

[0049] Reference Appendix Figure 1 Step 4, the control method uses the motor compensation torque T obtained from the torque increase / decrease module. com With the required torque T of the motor ISG The actual torque T is obtained by adding them together. req Furthermore, to improve driving safety, the required torque T of the motor is increased. ISG To implement amplitude limiting control, T is required. req The maximum adhesion torque of the road surface must not be exceeded. As shown in equation (6);

[0050]

Claims

1. A method for anti-slip control of P4 configuration hybrid vehicles, characterized in that, Includes the following steps: Step 1: Determining the Conditions for Driving Anti-Slip Entry The control method monitors the rotational speed of each wheel on the front and rear axles. It uses the larger of the rotational speeds of the rear axle wheels relative to the front axle wheels as a criterion. If the relative speed exceeds the calibrated value, it indicates that the difference in rotational speed between the front and rear axles is too large, requiring anti-skid control intervention. Considering that turning, obstacle crossing, and changes in tire pressure can also cause differences in rotational speed between the front and rear axles, the criterion is modified to the average rotational speed of the left and right rear axles wheels. When the relative average rotational speed... greater than the rated slip speed When the slip confirmation signal is set to 1, the drive anti-slip function is activated, and the rear axle speed is adjusted by increasing or decreasing the motor torque until the relative average speed is reached. Less than the rated slip speed The specific judgment conditions are expressed as follows: （1） In formula (1) This refers to the front axle speed. , These correspond to the speeds of the left and right wheels on the rear axle, respectively. It is the calibrated slip speed. All the speeds mentioned above are absolute values, corresponding to the two cases of increasing torque and decreasing torque. In addition to judging whether the slip confirmation signal is valid, it is also necessary to monitor the vehicle status. The vehicle must be in drive mode, the clutch must be engaged, and the gearbox must not be shifting. If any of the above conditions are not met, the drive anti-slip cannot be entered. Step 2: Initialize slip correction torque After the drive anti-slip entry conditions are met, the initial slip correction torque Set to 0 Nm for step-increase or step-decrease torque control; when the slip confirmation signal is 0, the initial slip correction torque is... It is also reset to 0 Nm, indicating that anti-slip control is not needed at this time and the anti-slip function is not working; Step 3: Adjusting the motor torque After initialization, the torque boosting module activates when the rear axle speed is lower than the front axle speed, the slip confirmation signal is 1, and the initial slip correction torque is set. The value is assigned to 10 Nm, and the initial value of the torque timer t(0) is set to 0. Each simulation step will adjust the torque by sliding it from the previous moment. Add a motor stepping torque to the base Increase torque at the previous moment. Add a step time to the base As shown in equation (2), until the slip correction torque Reaching the upper limit of torque Or the torque boosting time t exceeds the torque boosting duration limit. Stop increasing torque, step torque The value is read from the table according to the vehicle speed PID control, as shown in equation (3); （2） （3） In equation (2), K p K i K d These are the proportional coefficient, integral coefficient, and differential coefficient, respectively, where u is the current relative wheel speed; The torque reduction function is activated when the rear axle speed is higher than the front axle speed, and the slip confirmation signal is also 1, indicating the initial slip correction torque. The value is assigned to -10 Nm, the initial value of the torque reduction timer t(0) is set to 0, and then the torque reduction process is performed. Each simulation step size will slide and correct the torque at the previous moment. Based on the reduction of torque by one step As shown in equation (4), the torque timer decreases at the previous moment. Add a step time to the base Until the torque reduction time t exceeds the upper limit of the torque reduction duration or the slip correction torque is reached. Reaching the lower limit of torque Then exit torque reduction, step reduce torque. The value is read from a table based on the vehicle speed PID control, as shown in equation (5): （4） （5） In equation (5), K p K i K d These are the proportional coefficient, integral coefficient, and differential coefficient, respectively, where u is the current relative wheel speed; Step 4: Obtain the required torque by outputting the torque compensation result. The control method uses the motor compensation torque T obtained from the torque increase / decrease module. com With the required torque T of the motor ISG The actual torque T is obtained by adding them together. req Furthermore, to improve driving safety, the required torque T of the motor is increased. ISG To implement amplitude limiting control, T is required. req The maximum adhesion torque T on the road surface must not be exceeded. φ As shown in equation (6); （6）。

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