Electric vehicles, methods of controlling electric vehicle motors, tools and storage intermediaries.

Abstract

Invention details;

Description

Electric vehicle and motor control method, device and storage medium thereof Technical Field

[0001] The present application relates to the field of electric vehicles, and in particular to an electric vehicle and a motor control method, device, and storage medium thereof. Background Art

[0002] With the advancement of electric vehicle technology, their application is becoming increasingly widespread. For users, driving comfort is one of the main reasons for choosing an electric vehicle. However, when the motor's output torque changes between positive and negative, the direction of the motor's gear meshing shifts, causing gear rattling. This produces noticeable vibration and noise, affecting driving comfort. Furthermore, gear rattling can damage transmission mechanisms such as gears and splines.

[0003] Currently, to address this issue, filtering (e.g., torque smoothing) is typically used to reduce vibration and noise when the motor's output torque is switched between positive and negative. However, this approach still results in significant vibration and noise, resulting in a poor driving experience.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide an electric vehicle and a motor control method, device and storage medium thereof, which are used to solve the problem of large vibration and noise in the motor and its transmission system during the driving of the electric vehicle.

[0006] In a first aspect, an embodiment of the present application provides a motor control method for an electric vehicle, comprising: detecting a relative deformation amount of a transmission system between a driving tooth and a wheel end of the motor; when the relative deformation amount is a first threshold value, determining a first speed difference between a first driving tooth rotational speed and a first wheel end converted rotational speed, wherein the relative deformation amount being the first threshold value is used to indicate that the driving tooth and the passive tooth of the transmission system begin to disengage, the first driving tooth rotational speed is the rotational speed of the driving tooth at the moment when the driving tooth and the passive tooth disengage, and the first wheel end converted rotational speed is the rotational speed of the wheel end of the electric vehicle obtained by converting the speed ratio at the moment of disengagement; determining the output torque of the motor based on the first speed difference; and controlling the driving tooth to perform a tooth-leaning operation relative to the passive tooth based on the output torque.

[0007] In one possible embodiment, the output torque of the motor is determined based on the first speed difference, including: determining the product of the first speed difference and the first time length as a first product, where the first time length is the duration from the disengagement moment to the contact moment of the active tooth and the passive tooth; if the first product is less than a preset tooth gap value, then determining that the output torque includes a first torque and a second torque, wherein the directions of the first torque and the second torque are opposite, the first torque is the torque required in the time interval from the disengagement moment to the transition moment of the motor to the acceleration and deceleration state, and the second torque is the torque required in the time interval from the transition moment to the contact moment.

[0008] In a possible embodiment, the first torque and the second torque are determined in the following manner: at the transition moment, the second speed difference between the current driving gear speed and the second wheel-end converted speed is determined by presetting the tooth gap value, the first speed difference and the first time duration, the second wheel-end converted speed being the speed obtained by converting the wheel-end speed of the electric vehicle through the speed ratio at the transition moment; the second driving gear speed is determined based on the second speed difference and the second wheel-end converted speed, the second driving gear speed being the speed of the driving gear at the transition moment; the first torque is determined based on the second driving gear speed, the first driving gear speed, the duration between the disengagement moment and the transition moment, and the sliding friction of the driving gear at the second driving gear speed; the second torque is determined based on the second driving gear speed, the third driving gear speed, the duration between the transition moment and the contact moment, and the sliding friction of the driving gear at the third driving gear speed, the third driving gear speed being the speed of the driving gear at the contact moment.

[0009] In one possible embodiment, determining the output torque of the motor based on the first speed difference also includes: if the first product is greater than or equal to the preset tooth gap value, determining the product of the first speed difference and the second time length as the second product, and the second time length is the duration from the disengagement moment to the transition moment; if the second product is less than the preset tooth gap value, determining that the output torque includes the first torque and the second torque, wherein the directions of the first torque and the second torque are the same.

[0010] In one possible embodiment, the output torque of the motor is determined based on the first speed difference, and the further step includes: if the second product is greater than or equal to a preset tooth gap value, then at the target moment, a third wheel-end converted speed is determined, the third wheel-end converted speed being the speed obtained by converting the wheel-end speed of the electric vehicle after speed ratio conversion at the target moment, and the target moment being the moment when the driving tooth and the passive tooth contact again within the second time period; a third torque is determined based on the third wheel-end converted speed, the first driving tooth speed, and the duration between the disengagement moment and the target moment, the third torque being the torque required in the time interval from the disengagement moment to the target moment, and the output torque including the third torque.

[0011] In one possible embodiment, determining the relative deformation of the transmission system between the driving tooth of the motor and the wheel end further includes: determining a third speed difference between the current driving tooth rotation speed and the passive tooth rotation speed when a change in the output torque of the motor is detected; determining the relative displacement of the driving tooth and the passive tooth based on the third speed difference; and determining the relative deformation based on the relative displacement.

[0012] In a second aspect, an embodiment of the present application provides a motor control device for an electric vehicle, comprising: a detection module for detecting a relative deformation amount of a transmission system between a driving tooth of a motor and a wheel end; a determination module for determining a first speed difference between a first driving tooth rotational speed and a first wheel end conversion rotational speed when the relative deformation amount is a first threshold value, wherein the relative deformation amount being the first threshold value is used to indicate that the driving tooth and the passive tooth of the transmission system begin to disengage, the first driving tooth rotational speed is the rotational speed of the driving tooth at the moment when the driving tooth and the passive tooth disengage, and the first wheel end conversion rotational speed is the rotational speed of the wheel end of the electric vehicle obtained by converting the speed ratio at the moment of disengagement; a processing module for determining the output torque of the motor according to the first speed difference; and a control module for controlling the driving tooth to perform a tooth-leaning operation relative to the passive tooth according to the output torque.

[0013] In a third aspect, an embodiment of the present application provides an electric vehicle, comprising: a processor, and a memory communicatively connected to the processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the motor control method of the electric vehicle as in the first aspect.

[0014] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the motor control method of the electric vehicle according to the first aspect.

[0015] In a fifth aspect, an embodiment of the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the motor control method of an electric vehicle as in the first aspect.

[0016] The electric vehicle and its motor control method, device, and storage medium provided by the embodiments of the present application analyze the dynamic process of the motor's active teeth when the meshing direction changes, combined with the motor's high-precision active tooth position and speed measurement and the motor's rapid torque adjustment characteristics. When it is detected that the direction of the motor's output torque is about to change, the torque of the active teeth is controlled to perform active tooth-engaging operation, reducing the speed difference between the active and passive teeth when they disengage and re-engage, thereby reducing or even eliminating the vibration and noise between the active and passive teeth caused by inertial impact. Moreover, the present application does not require changes to the original hardware of the electric vehicle or the addition of new sensors. Gear-engaging control can be achieved by simply calculating the wheel end speed, the motor active tooth speed, and the tooth gap. At the same time, the present application can maximize the release of the motor's output torque when the direction of the output torque is about to change. The restriction on the output torque of the motor is about to change, so that the motor's output torque can follow the user's operation and expectations, can avoid the problem of a sense of acceleration after releasing the accelerator or poor response of the electric vehicle when the accelerator is pressed due to the restriction on the output torque of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following is a brief introduction to the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0018] FIG1 is a curve diagram of a torque filtering method provided by related art;

[0019] FIG2 is a schematic structural diagram of an electric vehicle provided in an embodiment of the present application;

[0020] FIG3 is a flow chart of a motor control method for an electric vehicle provided in an embodiment of the present application;

[0021] FIG4 is a schematic diagram of the motion process of the active tooth and the passive tooth provided in an embodiment of the present application;

[0022] FIG5 is a schematic diagram of a curve for controlling the active gear relative to the gear provided in an embodiment of the present application;

[0023] FIG6 is a schematic diagram of a first embodiment of geometric model simplification processing for the shaded area in FIG5 according to an embodiment of the present application;

[0024] FIG7 is a schematic diagram of a second embodiment of geometric model simplification processing for the shaded area in FIG5 according to an embodiment of the present application;

[0025] FIG8 is a schematic diagram of a curve of motor output torque corresponding to FIG7 provided in an embodiment of the present application;

[0026] FIG9 is a schematic diagram of a third embodiment of geometric model simplification processing for the shaded area in FIG5 according to an embodiment of the present application;

[0027] FIG10 is a schematic diagram of a curve of motor output torque corresponding to FIG9 provided in an embodiment of the present application;

[0028] FIG11 is a schematic structural diagram of a motor control device for an electric vehicle provided in an embodiment of the present application;

[0029] FIG12 is a block diagram of an electric vehicle according to an exemplary embodiment. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments made by ordinary technicians in this field based on the inspiration of these embodiments fall within the scope of protection of this application.

[0031] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the numbers used in this way are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] The following first explains the terms involved in this application.

[0033] Torque: A special moment of force that causes an object to rotate. Motor torque is the output torque of the motor.

[0034] Backlash: The gap between the tooth surfaces of a pair of meshing gears. Backlash is a parameter necessary for smooth meshing and operation.

[0035] Relative deformation: The deformation of a non-rigid material when subjected to force, including but not limited to torsion and deflection.

[0036] The related technologies provided in the background technology have at least the following technical problems:

[0037] As countries around the world tighten their control over carbon emissions, set carbon peak and carbon neutrality targets, and plan to ban the sale of fuel-powered vehicles, they are also vigorously encouraging and supporting new energy vehicles, or electric vehicles. Given the current trend of expanding new energy applications, the research and development, production, and deployment of electric vehicles are expected to grow rapidly. Electric vehicles are driven by controlling the motor's output torque based on a target torque determined by the vehicle controller or motor controller. When the motor's positive and negative torque shifts—that is, when the direction of the motor's output torque changes—the meshing direction of the motor's gears changes, resulting in inconsistent force directions and causing gear rattling. This can cause noticeable vibration and noise, affecting driving comfort. Furthermore, gear rattling can damage transmission mechanisms such as gears and splines.

[0038] In response to the above problems, in the related art, when the output torque of the motor is changed from positive to negative torque, the output torque is processed by a filtering method to reduce vibration and noise. The filtering method can be a torque smoothing method. As shown in Figure 1, taking the process of the output torque of the motor changing from positive torque to negative torque as an example, the speed difference between the rotational speed of the active tooth and the rotational speed of the passive tooth in the process of the active tooth crossing the tooth gap is integrated over time, which is the shaded area in the figure, and the shaded area is the tooth gap value. In Figure 1, the relative motion of the active tooth and the passive tooth can be divided into four stages, namely ①, ②, ③ and ④ in Figure 1, among which stage ① is the stage of positive torque decrease and elastic pressure release; stage ② is the process of the active tooth leaning on the tooth; stage ③ is the process of contact and compression between the active tooth and the passive tooth; stage ④ is the stage of negative torque increase and elastic pressure compression of the motor. ΔN1 in Figure 1 can be used to represent the speed difference between the wheel end conversion speed and the active tooth speed at the moment of disengagement of the active tooth and the passive tooth.

[0039] The above-mentioned related technologies have the following problems: 1) By smoothing the output torque, the active tooth is slowly passed through the tooth gap with a small torque or zero torque output, resulting in a long time for the active tooth to pass through the tooth gap and a long time for the positive and negative torque to change. The user experiences discontinuous and interrupted output torque response of the motor in the driving experience, thereby perceiving a power output delay and a poor driving experience; 2) When the active tooth and the passive tooth contact at the maximum speed difference, inertial impact and collision noise will still be generated, and the improvement of vibration and noise is not obvious; 3) The torque slope of the active tooth and the passive tooth in the elastic pressure release stage is too large, so ΔN1 is large, resulting in an excessive initial velocity of the active tooth when passing through the tooth gap, resulting in an excessive speed difference when the active tooth and the passive tooth contact again, resulting in severe impact and continuous shaking of the electric vehicle. Therefore, the torque slope decreases or increases during the elastic pressure release stage, resulting in the electric vehicle still accelerating after the user releases the accelerator, or the electric vehicle does not accelerate when the user steps on the accelerator, thereby resulting in poor dynamic response of the electric vehicle.

[0040] The present application proposes a motor control method for an electric vehicle. By analyzing the dynamic process of the driving teeth of the motor in the transmission system when the meshing direction changes, combined with the high-precision measurement of the position and speed of the driving teeth of the motor and the characteristics of the motor's rapid torque adjustment, when it is detected that the direction of the motor's output torque has changed, the driving teeth are controlled to perform a tooth-engaging operation, thereby reducing the speed difference between the driving and driven teeth when they disengage and re-contact, thereby reducing or even eliminating the vibration and noise between the driving and driven teeth caused by inertial impact.

[0041] In one embodiment, the motor control method of the electric vehicle can be applied in an application scenario. Figure 2 is a structural schematic diagram of the electric vehicle provided in an embodiment of the present application. As shown in Figure 2, the electric vehicle may include an electronic control unit (ECU), a left front wheel, a left front wheel speed sensor, a left front drive shaft, a front motor resolver, a front motor, a front motor control and driver, a front motor reduction differential, a right front drive shaft, a right front wheel speed sensor, a right front wheel, a high-voltage battery, a left rear wheel, a left rear wheel speed sensor, a rear motor resolver, a rear motor, a rear motor control and driver, a rear motor reduction differential, a left rear transmission shaft, a right rear drive shaft, a right rear wheel speed sensor, and a right rear wheel.

[0042] In the above scenario, the output torque of the front motor is transmitted to the left front wheel and the right front wheel through the front motor reduction differential; the output torque of the rear motor is transmitted to the left rear wheel and the right rear wheel through the rear motor reduction differential, and then the wheel speeds of the corresponding wheels are collected respectively by the left front wheel speed sensor, the right front wheel speed sensor, the left rear wheel speed sensor and the right rear wheel speed sensor. The speed values ​​detected by the left front wheel speed sensor, the right front wheel speed sensor, the left rear wheel speed sensor and the right rear wheel speed sensor are all collected and processed by the ECU. The ECU determines whether the torque direction of the output torque of the front motor and the rear motor has changed through the acquired wheel speed, and when the torque direction changes, controls the active gear to perform gear-dependent operation, thereby actively controlling the speed of the active gear. This can reduce or even avoid the problem of high initial velocity and long time consumption when the active gear crosses the tooth gap. Therefore, it can reduce or even avoid the problems of power output delay, vibration and noise.

[0043] In combination with the above scenarios, the technical solution of the motor control method for an electric vehicle provided by this application is described in detail through several specific embodiments below.

[0044] The present application provides a motor control method for an electric vehicle. FIG3 is a flow chart of the motor control method for an electric vehicle provided in an embodiment of the present application. As shown in FIG3 , the method includes the following steps:

[0045] S301: Detecting the relative deformation of the transmission system between the driving gear of the motor and the wheel end.

[0046] In this step, when the direction of the output torque of the motor is about to change, it can be determined whether the meshing direction of the motor driving teeth and the passive teeth of the transmission system is about to change. That is, when the direction of the output torque of the motor changes, it indicates that the driving teeth and the passive teeth are about to disengage, that is, the elastic force between the driving teeth and the passive teeth will be released, so that the elastic force is reduced, and the relative deformation of the transmission system between the driving teeth and the wheel end is also reduced.

[0047] Optionally, the meshing direction of the driving teeth and the driven teeth of the motor can be continuously detected during the operation of the motor, and the relative deformation of the transmission system between the driving teeth and the wheel end can be continuously calculated, so that when it is detected that the direction of the output torque of the motor is about to change, the relative deformation of the transmission system between the driving teeth and the wheel end can be determined.

[0048] Optionally, the relative deformation of the transmission system between the driving gear and the wheel end may include gear deformation and shaft deformation.

[0049] S302: When the relative deformation amount is a first threshold, determining a first speed difference between a first driving gear rotational speed and a first wheel end converted rotational speed.

[0050] In this step, the relative deformation amount being a first threshold value indicates that the driving gear and the passive gear of the transmission system have begun to disengage. The first driving gear speed is the speed of the driving gear at the moment of disengagement from the passive gear. The first wheel-end converted speed is the speed of the electric vehicle's wheel-end speed converted by the speed ratio at the moment of disengagement. The relative deformation amount being the first threshold value can be when the relative deformation amount is equal to zero, which is the moment when the driving gear and the passive gear begin to disengage. The process of disengagement and re-contact of the active tooth and the passive tooth can be shown in Figure 4, which is a schematic diagram of the motion process of the active tooth and the passive tooth provided in an embodiment of the present application. In Figure 4, the motion process can be a motion decomposition process between the active tooth and the passive tooth after the fixed coordinate system is converted into the rotating coordinate system through a coordinate (park) transformation, wherein the frequency of the rotating coordinate system is obtained by converting the wheel speed (the wheel speed is relatively stable, and a relatively stable coordinate system frequency can be obtained). The relative motion between the active tooth and the passive tooth can be equivalent to the following 6 stages or moments: the elastic release stage, the moment when the active tooth and the passive tooth start to disengage, the free rotation stage of the active tooth, the moment when the active tooth and the passive tooth start to re-engage, the moment when the active tooth and the passive tooth start to contact, and the elastic compression stage.

[0051] Optionally, the start of disengagement of the active tooth and the passive tooth may also be determined in the following manner: during the recovery process of the elastic deformation between the active tooth and the passive tooth, the relative deformation recovery amount is equal to the elastic deformation amount.

[0052] Optionally, when the relative deformation reaches a first threshold, i.e., when the driving tooth and the driven tooth begin to disengage, the speed difference between the first driving tooth rotational speed and the first wheel end converted rotational speed at that moment can be determined and recorded as a first speed difference. The output torque required by the motor can then be determined based on the first speed difference.

[0053] S303: Determine the output torque of the motor according to the first speed difference.

[0054] In this step, after determining the first speed difference, the output torque of the motor can be calculated by the first speed difference, as shown in Figure 5, which is a curve diagram of controlling the active tooth to lean against the tooth provided by the embodiment of the present application. In Figure 5, taking the output torque of the motor changing from positive torque to negative torque as an example, the relative motion of the active tooth and the passive tooth can be decomposed into three stages, wherein stage ① can be the positive torque decrease and elastic release stage, stage ② can be the active tooth to lean against the tooth stage, and stage ③ can be the negative torque increase and elastic compression stage. In Figure 5:

[0055] T 12 It can be used to indicate the first torque required to actively control the driving gear to engage the gear. Its function is to accelerate the motor rotor (driving gear) so that the motor shaft quickly passes through the gear gap area.

[0056] T 12 It can be used to indicate the second torque required to actively control the active gear to engage the gear. Its function is to reduce the speed difference when the gear meshing surfaces are in contact, thereby reducing the inertial impact caused by the speed difference.

[0057] t0 can be used to indicate the moment when the motor's output torque begins to decrease when the user releases the accelerator;

[0058] t1 can be used to indicate the moment when the active gear and the passive gear begin to disengage;

[0059] t2 can be used to represent T 12 The first torque action ends at a moment when the rotation speed of the active gear changes from acceleration to deceleration, which may be a preset time point;

[0060] t3 can be used to represent T 23 The second torque ends, i.e., the moment when the driving tooth and the driven tooth come into contact again;

[0061] t 01 It can be used to indicate the duration from the time the user releases the accelerator to the time the active and passive gears begin to disengage.

[0062] t 12 Can be used to represent T 12 first torque action duration;

[0063] t23 Can be used to represent T 23 The duration of the second torque action;

[0064] t 13 Can be used to represent t 12 +t 23 The total time of the active control gear is the time duration of the active control gear against the gear;

[0065] N O It can be used to indicate the speed converted from the wheel end speed by the speed ratio, referred to as the wheel end converted speed;

[0066] N O1 It can be used to indicate the wheel end conversion speed at time t1;

[0067] N O2 It can be used to indicate the wheel end conversion speed at time t2;

[0068] N O3 It can be used to indicate the wheel end conversion speed at time t3;

[0069] N R It can be used to indicate the motor rotor speed, that is, the driving gear speed;

[0070] N R1 Can be used to represent t 01 At the end, the driving gear speed is the driving gear speed at time t1;

[0071] N R2 Can be used to represent t 12 At the end, the driving gear speed is the driving gear speed at time t2;

[0072] ΔN1 can be used to represent N at time t1 O1 With N R1 The speed difference is the speed difference between the wheel end conversion speed and the driving gear speed at the moment when the driving gear and the driven gear are disengaged;

[0073] ΔN2 can be used to represent N at time t2 O2 With N R2 The speed difference, T 12 The speed difference between the wheel end converted speed and the driving gear speed at the time when the first torque ends.

[0074] Optionally, the speed difference between the active tooth and the passive tooth during the process of the active tooth passing through the tooth gap can be integrated over time, which is the shaded area in Figure 5. The shaded area is the tooth gap value. By determining the first speed difference, that is, ΔN1, the output torque of the motor, that is, T 12 and T 23 .

[0075] Optionally, in stage ① of FIG5 , the integral range of the elastic release deformation can be: from the time the passive gear follows and disengages after the user releases the accelerator, to the time when the motor's output torque reaches 0 or the integral value of the elastic release deformation equals the preset elastic deformation value. The preset elastic deformation value can be represented by a mapping table of output torque and elastic release deformation. When the cumulative integral value of the elastic release deformation reaches the preset elastic deformation value, the elastic release deformation is considered to have ended. The mapping table can be preset by applying different stall torques to the motor on the vehicle or transmission assembly in a static state and measuring the angle of rotation of the motor shaft under these stall torques.

[0076] In stage ② in FIG5 , the backlash integral range can be: from the end of elastic release deformation to the time when the backlash integral value reaches the preset backlash value S or the self-learning backlash value S.

[0077] In stage ③ of FIG5 , the integral range of the elastic compression deformation can be: from the end of the tooth gap integral to the re-engagement of the active tooth and the passive tooth.

[0078] Alternatively, the integral calculation formula can be expressed as follows:

[0079] L=ΣΔω

[0080] Δω=ΔN×2π / 60

[0081] When the sampling frequency is Δt

[0082] L t =L t-1 +Δω×Δt

[0083] Among them, L can be used to represent the integral of the relative position difference between the driving tooth and the driven tooth. Both the elastic deformation integral and the tooth gap integral can be expressed by this value, and the unit is radian rad; ΔN can be used to represent the speed difference between the driving tooth and the driven tooth, and the unit is rpm; ω can be used to represent the speed difference between the driving tooth and the driven tooth after unit conversion, and the unit is rad / s.

[0084] S304: Control the driving gear to perform a gear-engaging operation relative to the driven gear according to the output torque.

[0085] In this step, since the active control of the driving tooth speed is achieved by controlling the output torque of the motor, the output torque of the motor can be controlled to control the driving tooth to perform a tooth-to-tooth operation relative to the passive tooth, thereby reducing the speed difference between the driving tooth and the passive tooth when the teeth are in contact, thereby reducing the inertial impact when the teeth are in contact, and thus eliminating vibration and noise.

[0086] The electric vehicle motor control method provided in this embodiment incorporates elastic deformation when the motor output torque changes, calculates the elastic deformation, and identifies the relative initial velocity caused by the elastic deformation. Based on the initial velocity, a corresponding motor output torque control strategy is implemented to control the active tooth to actively engage the gear. This effectively reduces, or even avoids or resolves, inertial impact during tooth contact, thereby eliminating vibration and noise. Furthermore, by actively controlling the active tooth engagement, the contact and compression phases of the torque smoothing solution are eliminated, reducing the time it takes for the active tooth to pass through the tooth gap and shortening the tooth meshing surface change process. This reduces the time it takes to change between positive and negative torques, improving torque response and resulting in superior driving performance.

[0087] In one embodiment, the output torque of the motor is determined based on the first speed difference, including: determining the product of the first speed difference and the first time length as a first product, where the first time length is the duration from the disengagement moment to the contact moment of the active tooth and the passive tooth; if the first product is less than a preset tooth gap value, then determining that the output torque includes a first torque and a second torque, wherein the directions of the first torque and the second torque are opposite, the first torque is the torque required in the time interval from the disengagement moment to the transition moment of the motor to the acceleration and deceleration state, and the second torque is the torque required in the time interval from the transition moment to the contact moment.

[0088] In this solution, when determining the output torque of the motor according to the first speed difference, the product of the first speed difference and the first time length can be determined first, that is, ΔN1×(t 12 +t 23 ), when ΔN1×(t 12 +t 23 )<2S (where S can be used to represent the default backlash value. When the preset backlash value is 2S, it is the optimal solution), the first torque T calculated by the first speed difference is 12 and the second torque T 23 The direction is opposite to that of the load. At this time, the output torque curve can be shown as shown in Figure 5.

[0089] Optionally, by determining the output torque of the motor, the speed of the active tooth can be actively controlled, that is, the torque control is first decelerated and then accelerated (or first accelerated and then decelerated, depending on the direction of change of the output torque of the motor), reducing the time taken for the active tooth to pass through the tooth gap, reducing or even avoiding the problem of slow power response; by controlling the speed of the active tooth, the speed difference between the active tooth and the passive tooth when they re-contact is reduced. Under ideal conditions, the speed difference can be reduced to zero, and vibration and noise can be completely eliminated.

[0090] In one embodiment, the first torque and the second torque are determined in the following manner: at the transition moment, a second speed difference between a current driving gear speed and a second wheel-end converted speed is determined by a preset tooth gap value, a first speed difference, and a first duration, where the second wheel-end converted speed is the speed obtained by converting the wheel-end speed of the electric vehicle through the speed ratio at the transition moment; the second driving gear speed is determined based on the second speed difference and the second wheel-end converted speed, where the second driving gear speed is the speed of the driving gear at the transition moment; the first torque is determined based on the second driving gear speed, the first driving gear speed, the duration between the disengagement moment and the transition moment, and the sliding friction of the driving gear at the second driving gear speed; the second torque is determined based on the second driving gear speed, the third driving gear speed, the duration between the transition moment and the contact moment, and the sliding friction of the driving gear at the third driving gear speed, where the third driving gear speed is the speed of the driving gear at the contact moment.

[0091] In this solution, the shaded area in Figure 5 can be geometrically simplified, as shown in Figure 6. Through the simplified model shown in Figure 6, the output torque of the motor can be determined:

[0092] From the simplified model, we can see that when N O1 、N R1 , t 12 , t 23 When confirmed, N O2 、N O3 To determine the value, N R2 The time component of is a fixed value. And N O1 、N O3 、N R1 、N R2 The tooth clearance value S of the enclosed area is also a fixed value.

[0093] According to the above conditions, ΔN2 and N R2 The velocity component of the line segment N R1 N R2 Taking the derivative, we can get the velocity change rate a 12 , for line segment N R2 N O3 Taking the derivative, we can get the velocity change rate a 23 , according to the speed change rate a 12 and a 23 , the first torque T can be determined 12 and the second torque T 23 . It can be expressed as follows:

[0094] 2S=ΔN1×t 12 +ΔN2×(t 12 +t 23 )

[0095] ΔN2=(2S-ΔN1×t 12 ) / (t 12 +t 23 )

[0096] N R2 =N O2 -ΔN2=N O2 -(2S-ΔN1×t 12 ) / (t 12 +t 23 )

[0097] a 12 =(N R2 -N R1 ) / t 12

[0098] a 23 =(N O3 -N R2 ) / t 23

[0099] The first torque T can be calculated based on the moment of inertia of the motor rotor I. 12 and the second torque T 23 , which can be expressed as follows:

[0100] T 12 =I×a 12 +T F

[0101] T 23 =I×a 23 +T F

[0102] Among them, one or more tables can be determined according to different driving modes of electric vehicles, and the table can store the driving gear speed (or vehicle speed) and t 12 , t 23 Therefore, t 12 , t 23 Can be obtained through the query table; T F It can be used to indicate the sliding friction force of the active gear at the current active gear speed and temperature, and can be obtained through bench testing.

[0103] Optionally, the wheel end converted speed N O It can be determined by the following formula:

[0104] N O =N*i

[0105] The vehicle speed prediction formula can be determined by the following formula:

[0106] V=V1+a×Δt=V1+aF ×Δt-sinθ×g×Δt+F / m×Δt

[0107] =(N O1 +a O ×Δt)×2πr / K / i

[0108] K=N1×2πr / V1

[0109] The vehicle speed acceleration formula can be determined by the following formula:

[0110] a=a F -sinθ×g+F / m

[0111] Then a F ×Δt-sinθ×g×Δt+F / m×Δt=a O ×Δt×2πr / K / i

[0112] Wheel speed acceleration formula:

[0113] a O =a / (Δt×2πr×K)=(-a F -sinθ×g+F / m) / (2πr / K / i)

[0114] Wheel speed prediction formula:

[0115] N OΔt =N O1 +a O ×Δt=N O1 +(-a F -sinθ×g+F / m)×Δt / (2πr / K / i)

[0116] Among them, K can be used to represent the tire slip coefficient; N can be used to represent the wheel speed; N1 can be used to represent the wheel speed at a certain moment; N O It can be used to indicate the wheel-end conversion speed; V can be used to indicate the speed of the electric vehicle; V1 can be used to indicate the speed of the electric vehicle at a certain moment; a can be used to indicate the acceleration of the speed; F can be used to indicate the wheel-end torque. When the active tooth passes through the tooth gap, F = 0; a F It can be used to represent the deceleration caused by the vehicle's sliding resistance (wind resistance + wheel end friction + transmission system mechanical friction), which can be obtained through the sliding curve; a O It can be used to represent the acceleration of wheel speed; r can be used to represent the radius of the wheel; θ can be used to represent the slope; i can be used to represent the speed ratio between the wheel and the motor rotor; Δt can be used to represent the length of a certain time period; g can be used to represent the acceleration due to gravity; and m can be used to represent the mass of the electric vehicle.

[0117] Optionally, in addition to determining t12 , t 23 In addition to determining the output torque of the motor to control the active gear to complete the gear operation, the given T 12 and T 23 The value of T is used to complete the gear action of the active gear. One or more tables can be determined according to different driving modes. The table stores the active gear speed (or vehicle speed) and T 12 、T 23 The mapping relationship, that is, T 12 、T 23 It can be obtained by querying the table, then T 12 、T 23 The corresponding time can complete the tooth-engaging action of the active tooth, which can be expressed by the following formula:

[0118] a 12 =I / T 12

[0119] a 23 =I / T 23

[0120] 2S=ΔN1×t 12 +ΔN2×(t 12 +t 23 )

[0121] ΔN2=ΔN1-a 13 ×t 12 +a 12 ×t 12

[0122] ΔN1+a 12 ×t 12 =a 23 ×t 23 +a 13 ×(t12+t23)

[0123] t 23 =(ΔN1+a 12 ×t 12 -a 13 ×t 12 ) / (a 13 +a 23 )

[0124] 2S=ΔN1×t 12 +(ΔN1-a 13 ×t 12 +a 12 ×t 12 )×(t 12 +(ΔN1+a 12 ×t 12 -a 13 ×t12 ) / (a 13 +a 23 ))

[0125] Among them, a 13 Can be used to represent line segment N O1 N O3 Derivatively obtain the rate of change of velocity.

[0126] The first torque T can be determined by the above formula 12 The corresponding time t 12 and the second torque T 23 The corresponding time t 23 , that is, determine the entire tooth-adjusting process.

[0127] Optionally, in N O1 、N O3 、N R1 、N R2 When the enclosed area is determined as the tooth gap S, N O1 and N R1 OK, you can also determine T 12 、T 23 , t 12 , t 23 , t 13 Any two quantities in the equation can be used to determine the entire gear-aligning process.

[0128] Optionally, by actively controlling the speed of the driving tooth, that is, by first decelerating and then accelerating (or first accelerating and then decelerating, depending on the direction in which the output torque of the motor is to change), the time taken for the driving tooth to pass through the tooth gap is reduced, and the problem of slow power response is reduced or even avoided; by controlling the speed of the driving tooth, the speed difference between the driving tooth and the passive tooth when they re-contact is reduced. Ideally, the speed difference can be reduced to zero, and vibration and noise can be completely eliminated.

[0129] In one embodiment, the output torque of the motor is determined based on the first speed difference, and the method further includes: if the first product is greater than or equal to a preset tooth gap value, then the product of the first speed difference and the second time length is determined to be the second product, and the second time length is the duration from the disengagement moment to the transition moment; if the second product is less than the preset tooth gap value, then the output torque is determined to include the first torque and the second torque, wherein the directions of the first torque and the second torque are the same.

[0130] In this solution, when the calculated first product is greater than or equal to the preset backlash value 2S, it is necessary to determine the product of the first speed difference and the second time length, that is, when ΔN1×(t 12 +t 23 )≥2S, it is necessary to calculate ΔN1×t 12 .

[0131] Alternatively, if ΔN1×t 12 <2S, then the shaded area in FIG5 can be simplified geometrically to obtain the simplified model shown in FIG7. At this time, the first torque T is determined. 12 and the second torque T 23 The formula is the same as the above ΔN1×(t 12 +t 23 )<2S, but in ΔN1×t 12 <2S, the first torque T 12 and the second torque T 23 The direction is the same as that of , and the output torque curve can be shown as Figure 8.

[0132] Optionally, in FIG8 , the dotted line T1 can be used to represent a possible torque curve in the output torque decreasing stage. The torque curve depends on the torque decreasing slope u, the moment t1 when the driving tooth and the driven tooth disengage, and the initial speed difference ΔN1 when the driving tooth and the driven tooth disengage. Among them, u can be used to represent the average slope of the torque decrease from the moment when the user releases the throttle and the output torque begins to decrease to the moment when the driving tooth and the driven tooth begin to disengage (t0 to t1), that is, the torque decreasing slope.

[0133] Optionally, by actively controlling the speed of the driving tooth, that is, by first decelerating and then accelerating (or first accelerating and then decelerating, depending on the direction of change of the output torque of the motor), the time taken for the driving tooth to pass through the tooth gap is reduced, and the problem of slow power response is reduced or even avoided; by controlling the speed of the driving tooth, the speed difference between the driving tooth and the passive tooth when they contact again is reduced. Under ideal circumstances, the speed difference can be reduced to zero, and vibration and noise can be completely eliminated.

[0134] In one embodiment, the output torque of the motor is determined based on the first speed difference, and the further step includes: if the second product is greater than or equal to a preset tooth gap value, then at the target moment, a third wheel-end converted speed is determined, the third wheel-end converted speed being the speed obtained by converting the wheel-end speed of the electric vehicle through the speed ratio at the target moment, and the target moment being the moment when the active tooth and the passive tooth contact again within the second time period; a third torque is determined based on the third wheel-end converted speed, the first active tooth speed, and the duration between the disengagement moment and the target moment, the third torque being the torque required in the time interval from the disengagement moment to the target moment, and the output torque including the third torque.

[0135] In this solution, if the second product is greater than or equal to the preset backlash value, that is, ΔN1×t 12 ≥2S, the shaded area in Figure 5 can be simplified to obtain the simplified model shown in Figure 9. In this case, only the time from t1 to t 2′ The required torque within the time is t 2′This is the target time, and also the time when the active tooth and the passive tooth come into contact again within the time period from t1 to t2.

[0136] Alternatively, ΔN1×t 12 The output torque (third torque) of the motor when ≥2S can be expressed by the following formula:

[0137] ΔN1×t 12′ =2S

[0138] t 12′ =2S / ΔN1

[0139] N O2′ =N O1 -a 13 ×t 12′

[0140] a 12′ =(N O2′ -N R1 ) / t 12′

[0141] T 12′ =I×a 12′

[0142] Among them, t 12′ Can be used to represent t1 to t 2′ Length of time; N O2′ Can be used to represent t 2′ The wheel speed conversion speed when the driving gear and the driven gear contact again; a 12′ Can be used to represent line segment N O1 N O2′ The velocity change rate obtained by derivation; T 12′ Can be used to represent the third torque.

[0143] Alternatively, in ΔN1×t 12 ≥2S, the output torque curve can be shown in Figure 10. In Figure 10, the dotted line T1 can be used to represent the possible torque curve of the output torque reduction stage. The torque curve depends on the torque reduction slope u, the time t1 when the active tooth and the passive tooth disengage, and the initial speed difference ΔN1 when the active tooth and the passive tooth disengage. The dotted line T2 can be used to represent the torque curve at t 12′ After a certain time, the torque curve can be selected.

[0144] Optionally, by actively controlling the speed of the driving tooth, that is, by first decelerating and then accelerating (or first accelerating and then decelerating, depending on the direction of change of the output torque of the motor), the time taken for the driving tooth to pass through the tooth gap is reduced, and the problem of slow power response is reduced or even avoided; by controlling the speed of the driving tooth, the speed difference between the driving tooth and the passive tooth when they contact again is reduced. Under ideal circumstances, the speed difference can be reduced to zero, and vibration and noise can be completely eliminated.

[0145] In one embodiment, detecting the relative deformation amount of the transmission system between the driving teeth of the motor and the wheel end includes: determining whether the direction of the output torque of the motor is about to change; when the direction of the output torque is about to change, determining whether the meshing direction of the driving teeth and the passive teeth of the motor is about to change; when the meshing direction of the driving teeth and the passive teeth is about to change, determining the relative deformation amount.

[0146] In this solution, the torque transmitted by the transmission system between the active gear and the wheel will cause relative deformation of the transmission system between the active gear and the wheel end. The elastic force generated by the deformation of the transmission system between the active gear and the wheel end will cause a relative speed difference between the active gear rotational speed and the wheel end converted rotational speed during the output torque change process. By identifying the relative speed difference and implementing different output torque control strategies for different relative speed differences, the problem existing in related technologies of "causing the vehicle to still accelerate after releasing the accelerator or the vehicle to not accelerate when the accelerator is pressed, and poor vehicle dynamic response" can be effectively reduced or even avoided. Since this solution allows a larger torque slope in the elastic release stage, it can achieve rapid changes in positive and negative torques, thereby optimizing the dynamic response of electric vehicles.

[0147] Optionally, it is possible to determine whether the direction of the output torque of the motor is about to change. The direction of the output torque is about to change, which may include various situations such as the direction of the output torque changing from positive to negative, from negative to positive, zero positive, zero negative, etc.; when the direction of the output torque is about to change, it is possible to determine whether the meshing direction of the driving teeth and the driven teeth of the motor is about to change, and when the meshing direction of the driving teeth and the driven teeth is about to change, determine the relative deformation of the transmission system between the driving teeth of the motor and the wheel end.

[0148] In one embodiment, determining the relative deformation of the transmission system between the driving tooth of the motor and the wheel end further includes: determining a third speed difference between the current driving tooth rotation speed and the passive tooth rotation speed when a change in the direction of the output torque of the motor is detected; determining the relative displacement of the driving tooth and the passive tooth based on the third speed difference; and determining the relative deformation based on the relative displacement.

[0149] In this scheme, if the output torque changes, the third speed difference between the rotational speed of the driving tooth and the rotational speed of the passive tooth can be calculated in real time during the subsequent movement of the driving tooth and the passive tooth. The speed difference in each time period of multiple consecutive time periods can be determined, and then the relative displacement of the driving tooth and the passive tooth can be calculated by the speed difference in each time period and the duration of the corresponding time period, thereby obtaining the relative deformation of the driving tooth and the passive tooth.

[0150] Optionally, different relative deformation amounts cause different relative initial velocities of the driving teeth. Therefore, different output torque control strategies can be implemented for different initial velocities, thereby achieving rapid changes in positive and negative torques and optimizing the dynamic response of the electric vehicle.

[0151] The motor control method of the electric vehicle provided by the present application actively controls the output torque of the motor when the meshing direction of the active tooth and the passive tooth changes, thereby reducing the time consumed by the active tooth and the passive tooth to re-contact, accelerating the change of positive and negative torques, shortening the power output delay, and optimizing drivability; and actively controls the output torque of the motor when the meshing direction of the active tooth and the passive tooth changes, thereby eliminating the speed difference when the active tooth and the passive tooth contact, and eliminating the noise and impact caused by inertial impact; in addition, by applying a deceleration torque to reduce or eliminate the speed difference when the active tooth and the passive tooth contact, the torque slope in the elastic release stage can be increased, and a rapid change of positive and negative torque can be achieved, reducing or even avoiding the problem that the vehicle still accelerates after the accelerator is released or the vehicle does not accelerate when the accelerator is pressed, thereby optimizing the dynamic response of the vehicle.

[0152] Generally speaking, the technical solution provided by this application is a technical method that can not only optimize the driving performance of electric vehicles, but also eliminate the noise and impact caused by inertial collisions.

[0153] The present application also provides a motor control device for an electric vehicle. FIG11 is a schematic structural diagram of the motor control device for an electric vehicle provided in an embodiment of the present application. As shown in FIG11 , the motor control device 1100 for an electric vehicle includes:

[0154] A detection module 1101 is used to detect the relative deformation of the transmission system between the driving gear and the wheel end of the motor;

[0155] Determining module 1102, configured to determine a first speed difference between a first driving gear rotational speed and a first wheel-end converted rotational speed when the relative deformation amount reaches a first threshold value, wherein the relative deformation amount reaching the first threshold value indicates that the driving gear and the passive gear of the transmission system have begun to disengage, the first driving gear rotational speed being the rotational speed of the driving gear at the moment the driving gear and the passive gear disengage, and the first wheel-end converted rotational speed being the rotational speed of the wheel end of the electric vehicle at the moment of disengagement, after conversion of the speed ratio;

[0156] A processing module 1103 is configured to determine an output torque of the motor according to the first speed difference;

[0157] The control module 1104 is used to control the driving gear to perform a gear-engaging operation relative to the driven gear according to the output torque.

[0158] Optionally, when determining the output torque of the motor based on the first speed difference, the processing module 1103 is specifically used to: determine the product of the first speed difference and the first time length as a first product, where the first time length is the duration from the disengagement moment to the contact moment of the active tooth and the passive tooth; if the first product is less than the preset tooth gap value, then determine that the output torque includes a first torque and a second torque, wherein the directions of the first torque and the second torque are opposite, the first torque is the torque required in the time interval from the disengagement moment to the transition moment of the motor to the acceleration and deceleration state, and the second torque is the torque required in the time interval from the transition moment to the contact moment.

[0159] Optionally, the motor control device 1100 of the electric vehicle may further include a third determination module (not shown), which may be specifically used to determine the first torque and the second torque in the following manner: at the transition moment, determining the second speed difference between the current active gear speed and the second wheel-end converted speed by presetting the tooth gap value, the first speed difference, and the first duration, where the second wheel-end converted speed is the speed obtained by converting the wheel-end speed of the electric vehicle through the speed ratio at the transition moment; determining the second active gear speed based on the second speed difference and the second wheel-end converted speed, where the second active gear speed is the speed of the active gear at the transition moment; determining the first torque based on the second active gear speed, the first active gear speed, the duration between the disengagement moment and the transition moment, and the sliding friction of the active gear at the second active gear speed; determining the second torque based on the second active gear speed, the third active gear speed, the duration between the transition moment and the contact moment, and the sliding friction of the active gear at the third active gear speed, where the third active gear speed is the speed of the active gear at the contact moment.

[0160] Optionally, when determining the output torque of the motor based on the first speed difference, the processing module 1103 is further specifically used to: if the first product is greater than or equal to the preset tooth gap value, determine the product of the first speed difference and the second time length as the second product, and the second time length is the duration from the disengagement moment to the transition moment; if the second product is less than the preset tooth gap value, determine that the output torque includes the first torque and the second torque, wherein the directions of the first torque and the second torque are the same.

[0161] Optionally, when determining the output torque of the motor based on the first speed difference, the processing module 1103 is further specifically used to: if the second product is greater than or equal to the preset tooth gap value, then at the target moment, determine the third wheel-end converted speed, the third wheel-end converted speed being the speed obtained by converting the wheel-end speed of the electric vehicle after speed ratio conversion at the target moment, and the target moment being the moment when the active tooth and the passive tooth contact again within the second time length; determine the third torque based on the third wheel-end converted speed, the first active tooth speed, and the duration between the disengagement moment and the target moment, the third torque being the torque required in the time interval from the disengagement moment to the target moment, and the output torque including the third torque.

[0162] Optionally, when determining the relative deformation of the transmission system between the driving tooth and the wheel end of the motor, the first determination module 1101 can also be specifically used to: determine the third speed difference between the current driving tooth speed and the passive tooth speed when a change in the output torque of the motor is detected; determine the relative displacement of the driving tooth and the passive tooth based on the third speed difference; and determine the relative deformation based on the relative displacement.

[0163] The motor control device of an electric vehicle provided in this embodiment is used to execute the technical solution of the motor control method of an electric vehicle in the aforementioned method embodiment. Its implementation principle and technical effects are similar and will not be described in detail here.

[0164] The present application also provides an electric vehicle. FIG12 is a schematic diagram of the structure of an electric vehicle according to an exemplary embodiment. As shown in FIG12 , the electric vehicle 1200 includes:

[0165] Processor 1211, memory 1212, and interactive interface 1213;

[0166] The processor 1211 is in communication with the memory 1212; the memory 1212 is used to store computer-executable instructions that can be executed by the processor 1211;

[0167] The processor 1211 is configured to execute the technical solution in the aforementioned motor control method for an electric vehicle by executing computer executable instructions.

[0168] Optionally, the memory 1212 may be independent or integrated with the processor 1211 .

[0169] Optionally, when the memory 1212 is a device independent of the processor 1211 , the electronic device 1200 may further include: a bus for connecting the above devices.

[0170] Optionally, the memory may be, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The memory is used to store programs, and the processor executes the programs after receiving an execution instruction. Furthermore, the software programs and modules in the above-mentioned memory may also include an operating system, which may include various software components and / or drivers for managing system tasks (such as memory management, storage device control, power management, etc.), and may communicate with various hardware or software components to provide an operating environment for other software components.

[0171] Alternatively, the processor may be an integrated circuit chip having signal processing capabilities. The aforementioned processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc. The disclosed methods, steps, and logic block diagrams in the embodiments of this application may be implemented or executed. The general-purpose processor may be a microprocessor or any conventional processor.

[0172] An embodiment of the present application also provides a computer-readable storage medium, which stores computer-executable instructions. When the computer-executable instructions are executed by a processor, they are used to implement the technical solution of the electric vehicle motor control method provided in the aforementioned method embodiment.

[0173] An embodiment of the present application further provides a computer program product, including a computer program, which, when executed by a processor, implements the technical solution of the motor control method for an electric vehicle provided in the method embodiment.

[0174] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

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