Torque reduction control method for active skid resistance of dual-motor vehicle

Abstract

The invention discloses a torque reduction control method for active skid resistance of a dual-motor vehicle, which is different from the conventional TCS (Triggering Control System) which obtains a vehicle speed difference value delta V between a vehicle speed corresponding to a wheel rotating speed and an actual vehicle speed of the vehicle and intervenes in control to realize torque reduction and skid resistance when the delta V is greater than a vehicle speed difference threshold value delta V1. According to the method, torque reduction is conducted on the motor in advance at the initial stage when the vehicle does not have the obvious slip condition by introducing the variable, namely the rotating speed change rate of the motor; the torque reduction control is performed on the motor to a certain degree before the TCS intervenes, so that the torque of the corresponding wheel can be reduced gently, and the situations of vehicle impact, vehicle shaking and influence on vehicle driving caused by step and sudden change of the torque of the wheel due to quick intervention and quit of the TCS are avoided; and the torque reduction control of the vehicle on the motor can be more timely, so that the slipping degree of the vehicle is reduced, and the controllability of the vehicle is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle driving stability control, and particularly relates to a torque reduction control method for active anti-skid of a dual-motor vehicle. Background Art

[0002] At present, most new energy vehicles adopt dual-motor drive, which has the advantages of stronger power performance, no power interruption, higher drive efficiency and braking energy recovery rate compared with single-motor drive; although the dual motors working together can provide higher total power and torque output, in the absence of effective control, dual-motor vehicles are more likely to slip when starting, accelerating suddenly and driving on low-adhesion roads (such as wet, muddy and icy roads). Therefore, in order to avoid slipping, improve the driving stability of the vehicle and improve the acceleration performance, dual-motor vehicles are generally equipped with TCS (Traction Control System), whose working principle is to monitor the rotational speed of the wheels in real time through devices such as wheel speed sensors. When the vehicle speed corresponding to the wheel rotational speed does not match the actual vehicle speed, and the difference reaches the vehicle speed difference threshold, it is determined that the corresponding wheel is slipping, and TCS intervenes to control, reducing the torque of the corresponding motor and braking the slipping wheel, so as to avoid excessive slipping of the wheels and improve the traction and stability of the vehicle.

[0003] Although dual-motor vehicles can achieve torque reduction and anti-skid by relying on TCS, there are still drawbacks. Specifically, when the wheels suddenly slip, TCS will quickly reduce the torque to prevent the slipping from intensifying, and when the adhesion of the wheels is restored and TCS no longer needs to intervene, the torque will quickly return to the normal level. This rapid intervention and withdrawal of TCS will cause the torque of the wheels to have a step change and mutation, that is, the torque suddenly jumps from one value to another or changes violently in a short time. This rapid change in torque will not only cause vehicle shock and vehicle jitter, but may also affect the driver's driving of the vehicle. Therefore, it is necessary to design a torque reduction control method for active anti-skid of dual-motor vehicles that can reduce torque mutation and improve vehicle stability. Summary of the Invention

[0004] Aiming at the above deficiencies of the prior art, the purpose of the present invention is to provide a torque reduction control method for active anti-skid of dual-motor vehicles, to solve the technical problem that the vehicle is prone to vehicle jitter due to torque mutation during torque reduction and anti-skid at present, and to achieve the effect of improving the driving stability of the vehicle.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: A torque reduction control method for active anti-skid of a dual-motor vehicle, comprising the following steps: 1) Obtain the rotational speed change rate Nrate1 of the front axle motor and the rotational speed change rate Nrate2 of the rear axle motor, and preset the rotational speed change rate Nrate3 for enabling torque reduction control; obtain the vehicle speed differences ΔV between the vehicle speeds corresponding to the rotational speeds of each wheel and the actual vehicle speed of the vehicle, and the vehicle speed difference threshold value ΔV1 for TCS intervention control. 2) Before TCS intervention control when each ΔV is less than ΔV1, determine whether to enable torque reduction control for the front axle motor or operate according to the torque allocated by the VCU based on the magnitude relationship between Nrate1 and Nrate3, and determine whether to enable torque reduction control for the rear axle motor or operate according to the torque allocated by the VCU based on the magnitude relationship between Nrate2 and Nrate3.

[0006] Furthermore, in step 2), if the magnitude relationship between Nrate1 and Nrate3 is Nrate1 > Nrate3, then enable torque reduction control for the front axle motor; otherwise, the front axle motor operates according to the torque allocated by the VCU. If the magnitude relationship between Nrate2 and Nrate3 is Nrate2 > Nrate3, then enable torque reduction control for the rear axle motor; otherwise, the rear axle motor operates according to the torque allocated by the VCU.

[0007] Furthermore, in step 2), enabling torque reduction control for the front axle motor means: calculate the anti-slip torque T of the front axle motor 前防滑 and make the front axle motor operate according to T 前防滑 The calculation formula is T 前防滑 = T 前当前 × K 前轴 , where T 前当前 is the current torque of the front axle motor, and K 前轴 is the torque anti-slip coefficient of the front axle motor. Enabling torque reduction control for the rear axle motor means: calculate the anti-slip torque T of the rear axle motor 后防滑 and make the rear axle motor operate according to T 后防滑 The calculation formula is T 后防滑 = T 后当前 × K 后轴 , where T 后当前 is the current torque of the rear axle motor, and K 后轴 is the torque anti-slip coefficient of the rear axle motor.

[0008] Furthermore, in step 1), the preset rotational speed change rate Nrate3 for enabling torque reduction control is 3000 rpm / s, and the vehicle speed difference threshold value ΔV1 for TCS intervention control is 10 kph.

[0009] Furthermore, in step 2), if 3000 rpm / s < Nrate1 < 4000 rpm / s, then K 前轴 is taken as K1. If 4000 rpm / s < Nrate1 < 5000 rpm / s, then K 前轴Take K2. If 5000 rpm / s < Nrate1 < 6000 rpm / s, then K 前轴 Take K3. If 6000 rpm / s < Nrate1 < 7000 rpm / s, then K 前轴 Take K4; if 3000 rpm / s < Nrate2 < 4000 rpm / s, then K 后轴 Take it as K1. If 4000 rpm / s < Nrate2 < 5000 rpm / s, then K 后轴 Take K2. If 5000 rpm / s < Nrate2 < 6000 rpm / s, then K 后轴 Take K3. If 6000 rpm / s < Nrate2 < 7000 rpm / s, then K 后轴 Take K4; K1 > K2 > K3 > K4.

[0010] Further, in step 2), the value of K1 is 0.5, the value of K2 is 0.4, the value of K3 is 0.3, and the value of K4 is 0.2.

[0011] Further, the torque reduction control method further includes step 3). If Nrate1 > Nrate3, Nrate2 < Nrate3, and for any front wheel driven by the front axle motor, ΔV > ΔV1, then make the front axle motor operate at the smaller torque of the torque distributed by TCS and T 前防滑 and make the rear axle motor operate at the torque distributed by VCU; if Nrate1 < Nrate3, Nrate2 > Nrate3, and for any rear wheel driven by the rear axle motor, ΔV > ΔV1, then make the rear axle motor operate at the smaller torque of the torque distributed by TCS and T 后防滑 and make the front axle motor operate at the torque distributed by VCU; if Nrate1 > Nrate3, Nrate2 > Nrate3, and for any front wheel driven by the front axle motor, ΔV > ΔV1, and for any rear wheel driven by the rear axle motor, ΔV > ΔV1, then make the front axle motor operate at the smaller torque of the torque distributed by TCS and T 前防滑 and make the rear axle motor operate at the smaller torque of the torque distributed by TCS and T 后防滑 and make the rear axle motor operate at the smaller torque of the torque distributed by TCS and T.

[0012] Further, the torque reduction control method further includes step 4). If Nrate1 < Nrate3 and Nrate2 < Nrate3, then make the front axle motor and the rear axle motor operate at the torque distributed by VCU respectively.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The torque reduction control method for active anti-skid of dual-motor vehicles according to the present invention is different from the existing TCS that obtains the vehicle speed difference ΔV between the vehicle speed corresponding to the wheel speed and the actual vehicle speed of the vehicle, and intervenes in the control to achieve torque reduction and anti-skid when ΔV is greater than the vehicle speed difference threshold value ΔV1. The present invention advances the torque reduction of the motor at the initial stage when the vehicle does not show obvious skidding by introducing a variable of the motor speed change rate. Performing a certain degree of torque reduction control on the motor before the TCS intervenes can not only make the torque of the corresponding wheel decrease smoothly, thus avoiding the step and mutation of the wheel torque caused by the rapid intervention and withdrawal of the TCS, which in turn causes vehicle impact, vehicle jitter and affects vehicle driving, but also make the vehicle's torque reduction control of the motor more timely, which is beneficial to reducing the degree of vehicle skidding and improving the vehicle's controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flowchart of the torque reduction control method for active anti-skid of dual-motor vehicles described in the embodiment; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0016] Embodiment: Please refer to Figure 1 , a torque reduction control method for active anti-skid of dual-motor vehicles, which relies on the vehicle-mounted computer, sensors and controllers on the vehicle, and includes the following steps: 1) Obtain the rotational speed change rate Nrate1 of the front axle motor and the rotational speed change rate Nrate2 of the rear axle motor, and preset the rotational speed change rate Nrate3 for enabling torque reduction control; obtain the vehicle speed difference ΔV between the vehicle speed corresponding to the rotational speed of each wheel and the actual vehicle speed of the vehicle, and the vehicle speed difference threshold value ΔV1 for TCS intervention control; the unit of the rotational speed change rate is rpm / s, which is a composite unit based on the rotational speed (rpm) and is used to represent the change amount of the rotational speed per second. For example, if the motor rotational speed increases from 1000 rpm to 1200 rpm in 5 seconds, then the rotational speed change rate is (1200 - 1000) / 5 = 40 rpm / s; in this embodiment, the preset rotational speed change rate Nrate3 for enabling torque reduction control is 3000 rpm / s, and the vehicle speed difference threshold value ΔV1 for TCS intervention control is 10 kph.

[0017] 2) Before TCS intervenes in control when each ΔV is less than ΔV1, determine whether to enable torque reduction control for the front axle motor or operate at the torque allocated by the VCU according to the magnitude relationship between Nrate1 and Nrate3, and determine whether to enable torque reduction control for the rear axle motor or operate at the torque allocated by the VCU according to the magnitude relationship between Nrate2 and Nrate3; VCU (Vehicle Control Unit) is the vehicle control unit in an automobile and is one of the core components of new energy vehicles (especially electric vehicles). It is equivalent to the "brain" of the vehicle and is mainly responsible for the control and management of the entire vehicle. It can control the rotational speed and torque output of the motor to make the vehicle accelerate according to the driver's intention.

[0018] The torque reduction control method for active anti-skid of a dual-motor vehicle according to the present invention is different from the existing method where TCS obtains the vehicle speed difference ΔV between the vehicle speed corresponding to the wheel rotational speed and the actual vehicle speed, and intervenes in control when ΔV is greater than the vehicle speed difference threshold ΔV1 to achieve torque reduction and anti-skid. The present invention pre-controls the torque reduction of the motor in advance by introducing a variable of the rotational speed change rate of the motor; when the wheels of the vehicle slip, the rotational speed change rate of the corresponding motor will suddenly increase due to a significant reduction in load, and the rotational speed change of the wheels will lag behind the change of the rotational speed change rate of the motor due to the inertia of the wheels and the transmission structure between the wheels and the motor. The change of the rotational speed change rate of the motor precedes the occurrence of the situation where ΔV is greater than the vehicle speed difference threshold ΔV1. Therefore, when the vehicle is traveling, the present invention real-time obtains the rotational speed change rate Nrate1 of the front axle motor and the rotational speed change rate Nrate2 of the rear axle motor, and preset the rotational speed change rate Nrate3 for enabling torque reduction control. Before each ΔV is less than ΔV1 and before the condition for TCS to intervene in control is reached, when Nrate1 > Nrate3, enable torque reduction control for the front axle motor, and when Nrate2 > Nrate3, enable torque reduction control for the rear axle motor, so as to pre-control the torque reduction of the motor at the initial stage when the vehicle does not show obvious slipping conditions; performing a certain degree of torque reduction control on the motor before TCS intervenes can not only make the torque of the corresponding wheel decrease smoothly, thus avoiding the occurrence of step and mutation of the wheel torque caused by the rapid intervention and withdrawal of TCS, which in turn causes vehicle impact, vehicle jitter and affects vehicle driving, but also make the vehicle's torque reduction control for the motor more timely, which is beneficial to reducing the degree of vehicle slipping and improving the vehicle's controllability; the present invention can effectively solve the problem that the vehicle is prone to vehicle jitter caused by torque mutation during torque reduction and anti-skid, which is beneficial to improving the stability of vehicle driving.

[0019] Please refer to Figure 1, in step 2), if the relationship between Nrate1 and Nrate3 is Nrate1 > Nrate3, the front axle motor enables torque reduction control; otherwise, the front axle motor operates according to the torque allocated by the VCU. If the relationship between Nrate2 and Nrate3 is Nrate2 > Nrate3, the rear axle motor enables torque reduction control; otherwise, the rear axle motor operates according to the torque allocated by the VCU.

[0020] Specifically, in step 2), enabling torque reduction control for the front axle motor means: calculating the anti-slip torque T of the front axle motor 前防滑 and making the front axle motor operate according to T 前防滑 The calculation formula is T 前防滑 =T 前当前 ×K 前轴 , where T 前当前 is the current torque of the front axle motor, and K 前轴 is the torque anti-slip coefficient of the front axle motor. If 3000 rpm / s < Nrate1 < 4000 rpm / s, then K 前轴 is taken as K1. If 4000 rpm / s < Nrate1 < 5000 rpm / s, then K 前轴 is taken as K2. If 5000 rpm / s < Nrate1 < 6000 rpm / s, then K 前轴 is taken as K3. If 6000 rpm / s < Nrate1 < 7000 rpm / s, then K 前轴 is taken as K4; Enabling torque reduction control for the rear axle motor means: calculating the anti-slip torque T of the rear axle motor 后防滑 and making the rear axle motor operate according to T 后防滑 The calculation formula is T 后防滑 =T 后当前 ×K 后轴 , where T 后当前 is the current torque of the rear axle motor, and K 后轴 is the torque anti-slip coefficient of the rear axle motor. If 3000 rpm / s < Nrate2 < 4000 rpm / s, then K 后轴 is taken as K1. If 4000 rpm / s < Nrate2 < 5000 rpm / s, then K 后轴 is taken as K2. If 5000 rpm / s < Nrate2 < 6000 rpm / s, then K 后轴 is taken as K3. If 6000 rpm / s < Nrate2 < 7000 rpm / s, then K 后轴 is taken as K4; In this embodiment, the value of K1 is 0.5, the value of K2 is 0.4, the value of K3 is 0.3, and the value of K4 is 0.2.

[0021] Please refer toFigure 1 , after the motor with wheel slip is torque-reduced before TCS intervenes, the ΔV corresponding to the wheel may continue to increase and reach ΔV>ΔV1, so the torque-reduction control method also includes step 3 connected with step 2), step 3) is: if Nrate1>Nrate3, Nrate2<Nrate3, and the ΔV corresponding to any front wheel driven by the front axle motor>ΔV1, then the front axle motor is driven according to the torque allocated by TCS and T 前防滑 The smaller torque of the two is used to operate, and the rear axle motor operates according to the torque allocated by VCU; if Nrate1<Nrate3, Nrate2>Nrate3, and the ΔV corresponding to any rear wheel driven by the rear axle motor is>ΔV1, the rear axle motor is operated according to the torque allocated by TCS and T 后防滑 The front axle motor operates at the smaller torque of the two, and the front axle motor operates at the torque allocated by VCU; if Nrate1>Nrate3, Nrate2>Nrate3, and the ΔV corresponding to any front wheel driven by the front axle motor>ΔV1, and the ΔV corresponding to any rear wheel driven by the rear axle motor>ΔV1, then the front axle motor operates at the torque allocated by TCS and T 前防滑 The smaller torque of the two is operated, so that the rear axle motor can operate according to the torque and T distributed by TCS. 后防滑 The lesser torque operation of the two; In this way, when the motor torque reduction control in advance still cannot prevent the wheel from slipping, the motor is controlled according to the torque and T allocated by TCS. 前防滑 The smaller of the two continues to operate with the torque to avoid slip as much as possible and to get the wheels out of the slipping condition.

[0022] Furthermore, after getting rid of slipping and the speed change rate is reduced to Nrate1<Nrate3 and Nrate2<Nrate3, the front axle motor and the rear axle motor are restored to a normal driving state in which they respectively operate according to the torque allocated by the VCU.

[0023] When the TCS function quickly intervenes in and exits torque control when the wheel slips, a large torque step or torque mutation will occur in the wheel-end torque, which will cause the vehicle to impact and shake, and the driver's driving experience will become poor; the present invention provides a torque reduction control method for active anti-skid of dual-motor vehicles, which introduces the variable of the motor speed change rate to achieve early torque reduction control of the motor, and can reduce the difference between the corresponding wheel speed and the actual vehicle speed in advance, maintain vehicle stability and reduce the impact of torque mutation on the vehicle, thereby improving the stability of the vehicle form.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions should be covered within the scope of the claims of the present invention.

Claims

1. A torque reduction control method for active anti-skid of a dual-motor vehicle, characterized in that: It includes the following steps: 1) Obtain the rotational speed change rate Nrate1 of the front axle motor, the rotational speed change rate Nrate2 of the rear axle motor, and preset the rotational speed change rate Nrate3 for enabling torque reduction control; obtain the vehicle speed differences ΔV between the vehicle speeds corresponding to the rotational speeds of each wheel and the actual vehicle speed of the vehicle, and the vehicle speed difference threshold value ΔV1 for TCS intervention control; 2) Before TCS intervention control when each ΔV is less than ΔV1, determine whether the front axle motor enables torque reduction control or operates according to the torque allocated by the VCU based on the magnitude relationship between Nrate1 and Nrate3, and determine whether the rear axle motor enables torque reduction control or operates according to the torque allocated by the VCU based on the magnitude relationship between Nrate2 and Nrate3.

2. The torque reduction control method for active anti-skid of a dual-motor vehicle according to claim 1, characterized in that: In step 2), if the magnitude relationship between Nrate1 and Nrate3 is Nrate1 > Nrate3, the front axle motor enables torque reduction control; otherwise, the front axle motor operates according to the torque allocated by the VCU. If the magnitude relationship between Nrate2 and Nrate3 is Nrate2 > Nrate3, the rear axle motor enables torque reduction control; otherwise, the rear axle motor operates according to the torque allocated by the VCU.

3. The torque reduction control method for active anti-skid of a dual-motor vehicle according to claim 2, wherein: In step 2), enabling torque reduction control for the front axle motor means: calculating the anti-skid torque T of the front axle motor 前防滑 and making the front axle motor operate according to T 前防滑 . The calculation formula is T 前防滑 =T 前当前 ×K 前轴 , where T 前当前 is the current torque of the front axle motor, and K 前轴 is the torque anti-skid coefficient of the front axle motor; enabling torque reduction control for the rear axle motor means: calculating the anti-skid torque T 后防滑 of the rear axle motor and making the rear axle motor operate according to T 后防滑 . The calculation formula is T 后防滑 =T 后当前 ×K 后轴 , where T 后当前 is the current torque of the rear axle motor, and K 后轴 is the torque anti-skid coefficient of the rear axle motor.

4. The torque reduction control method for active anti-skid of a dual-motor vehicle according to claim 3, wherein: In step 1), the preset rotational speed change rate Nrate3 for enabling torque reduction control is 3000 rpm / s, and the vehicle speed difference threshold value ΔV1 for TCS intervention control is 10 kph.

5. The torque reduction control method for active anti-skid of a dual-motor vehicle according to claim 3, characterized in that: In step 2), if 3000 rpm / s < Nrate1 < 4000 rpm / s, then K 前轴 is taken as K1. If 4000 rpm / s < Nrate1 < 5000 rpm / s, then K 前轴 is taken as K2. If 5000 rpm / s < Nrate1 < 6000 rpm / s, then K 前轴 is taken as K3. If 6000 rpm / s < Nrate1 < 7000 rpm / s, then K 前轴 is taken as K4. If 3000 rpm / s < Nrate2 < 4000 rpm / s, then K 后轴 is taken as K1. If 4000 rpm / s < Nrate2 < 5000 rpm / s, then K 后轴 is taken as K2. If 5000 rpm / s < Nrate2 < 6000 rpm / s, then K 后轴 is taken as K3. If 6000 rpm / s < Nrate2 < 7000 rpm / s, then K 后轴 is taken as K4; K1 > K2 > K3 > K4.

6. The torque reduction control method for active anti-skid of a dual-motor vehicle according to claim 5, wherein: In step 2), the value of K1 is 0.5, the value of K2 is 0.4, the value of K3 is 0.3, and the value of K4 is 0.

2.

7. The torque reduction control method for active anti-skid of a dual-motor vehicle according to claim 3, characterized in that: It further includes step 3). If Nrate1 > Nrate3, Nrate2 < Nrate3, and for any front wheel driven by the front axle motor, ΔV > ΔV1, then the front axle motor operates at the smaller torque of the torque distributed by TCS and T 前防滑 and the rear axle motor operates at the torque distributed by VCU; If Nrate1 < Nrate3, Nrate2 > Nrate3, and for any rear wheel driven by the rear axle motor, ΔV > ΔV1, then make the rear axle motor operate at the smaller torque of the torque distributed by TCS and T 后防滑 and make the front axle motor operate at the torque distributed by VCU; if Nrate1 > Nrate3, Nrate2 > Nrate3, and for any front wheel driven by the front axle motor, ΔV > ΔV1, and for any rear wheel driven by the rear axle motor, ΔV > ΔV1, then make the front axle motor operate at the smaller torque of the torque distributed by TCS and T 前防滑 and make the rear axle motor operate at the smaller torque of the torque distributed by TCS and T 后防滑 and make the rear axle motor operate at the smaller torque of the torque distributed by TCS and T 8. The torque reduction control method for active anti-skid of a dual-motor vehicle according to claim 1, characterized in that: It further includes step 4), if Nrate1 < Nrate3 and Nrate2 < Nrate3, the front axle motor and the rear axle motor respectively operate according to the torque allocated by the VCU.

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