A control method and device of an electric power steering system and a vehicle

Abstract

The application provides a control method and device of an electric power steering system and a vehicle, relates to the technical field of vehicle control, and obtains target working condition information of a vehicle at present, wherein the target working condition information comprises a current vehicle speed, a rotating speed, a steering wheel rotating angle and a steering wheel torque; the rotating speed comprises a rotating speed of a steering wheel and a rotating speed of a motor in the electric power steering system; based on the target working condition information, it is determined whether the vehicle satisfies a first condition; based on the target working condition information, it is determined whether the vehicle is in a preparation stage of an abuse working condition; when the vehicle is in the preparation stage of the abuse working condition, it is determined whether the vehicle satisfies a second condition; if one of the target conditions of the first condition and the second condition is satisfied, a current of the motor is limited to a target preset current corresponding to the target condition; and if both the first condition and the second condition are satisfied, the current of the motor is limited to a second preset current. By adopting the control method provided by the application, the EPS is prevented or delayed from entering an overheating protection state, and the performance of the EPS is improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, and in particular to a control method, device, and vehicle for an electric power steering system. Background Technology

[0002] Electric Power Steering (EPS) is a new type of power steering device that uses an electric motor as its power source. An EPS system includes an EPS controller (also known as an Electronic Control Unit, ECU), a motor, a reduction gear mechanism, and a rack and pinion assembly. The EPS controller is connected to the motor, the motor is connected to the reduction gear mechanism, and the reduction gear mechanism is connected to the rack and pinion assembly. When the vehicle speed is low and the steering wheels are stuck, the EPS will continuously output a large current. If no intervention is taken, the EPS will quickly enter an overheat protection state, which can severely damage the EPS electronic hardware. Summary of the Invention

[0003] To address the aforementioned problems, in a first aspect, the present invention provides a control method for an electric power steering system, the control method comprising the following steps:

[0004] Obtain vehicle's current target operating condition information, which includes current vehicle speed, engine speed, steering wheel angle, and steering wheel torque; the engine speed includes steering wheel speed and the speed of the motor in the electric power steering system.

[0005] Based on the target operating condition information, it is determined whether the vehicle meets the first condition; wherein, the first condition is used to trigger rack end protection;

[0006] Based on the target operating condition information, it is determined whether the vehicle is in the abuse condition preparation stage; when the vehicle is in the abuse condition preparation stage, it is determined whether the vehicle meets the second condition; wherein, the second condition is used to trigger abuse protection.

[0007] If one of the first and second conditions is met, the current of the motor is limited to the target preset current corresponding to the target condition; wherein, the second preset current corresponding to the second condition is less than the first preset current corresponding to the first condition.

[0008] If both the first condition and the second condition are met, then the current of the motor is limited to the second preset current.

[0009] Preferably, determining whether the vehicle is in the abuse condition preparation stage based on the target operating condition information; when the vehicle is in the abuse condition preparation stage, determining whether the vehicle meets the second condition includes:

[0010] Based on the vehicle speed, the rotational speed, and the steering wheel torque, determine whether the vehicle is in the abuse condition preparation stage;

[0011] When the vehicle is in the abuse condition preparation phase, the current duration of the vehicle is determined;

[0012] Based on the vehicle speed, the engine speed, the steering wheel torque, and the duration, it is determined whether the vehicle meets the second condition.

[0013] Preferably, determining whether the vehicle meets the second condition based on the vehicle speed, the engine speed, the steering wheel torque, and the duration includes:

[0014] Based on whether the absolute value of the vehicle speed is less than a vehicle speed threshold;

[0015] Furthermore, whether the absolute value of the rotational speed is less than a rotational speed threshold;

[0016] Furthermore, whether the absolute value of the steering wheel torque is greater than the steering wheel torque threshold;

[0017] Furthermore, whether the duration is greater than the preset duration determines whether the vehicle meets the second condition.

[0018] Preferably, the step of limiting the motor current to a target preset current corresponding to the target condition if one of the first condition and the second condition is met includes:

[0019] If the target condition is the first condition, then the current of the motor is limited to the first preset current in real time;

[0020] If the target condition is the second condition, then the current of the motor will be limited to the second preset current during the first preset time period.

[0021] Preferably, the step of limiting the motor current to the second preset current if both the first condition and the second condition are satisfied includes:

[0022] If it is determined that the target operating condition information first reaches the first condition and then the second condition, in response to the triggered first condition, the current of the motor is limited to a third preset current in real time; wherein the third preset current is greater than the first preset current;

[0023] After limiting the current of the motor to the third preset current, in response to the triggering of the second condition, the current of the motor is limited to the second preset current for a first preset time period.

[0024] Preferably, when the current of the motor is limited to the second preset current during a first preset time period, the control method includes:

[0025] Obtain the current current of the motor;

[0026] Based on the current current and the first preset time period, determine the slope at which the current current decreases to the second preset current;

[0027] Based on the slope, the current is reduced to the second preset current.

[0028] Preferably, after limiting the current of the motor to the second preset current, the control method includes:

[0029] Based on the current vehicle speed, engine speed, and steering wheel torque, determine whether the vehicle has exited the second condition;

[0030] If so, the current of the motor will be increased from the second preset current within the second preset time period.

[0031] Preferably, increasing the motor current from the second preset current within the second preset time period includes:

[0032] Determine whether the first condition is met when the vehicle exits the operating condition corresponding to the second condition;

[0033] If so, then during the second preset time period, the current of the motor will be increased from the second preset current to the first preset current;

[0034] If not, then within the second preset time period, the motor current will be increased from the second preset current to the target current value; wherein the target current value is the motor current determined based on the current operating conditions of the vehicle.

[0035] In a second aspect, the present invention provides a control device for an electric power steering system, the control device comprising:

[0036] The acquisition module is used to acquire the vehicle's current target operating condition information, which includes the current vehicle speed, engine speed, steering wheel angle, and steering wheel torque; the engine speed includes the steering wheel speed and the speed of the motor in the electric power steering system.

[0037] The first input signal processing module is used to determine whether the vehicle meets a first condition based on the target operating condition information; wherein the first condition is used to trigger rack end protection.

[0038] The second input signal processing module is used to determine whether the vehicle is in the abuse condition preparation stage based on the target operating condition information; when the vehicle is in the abuse condition preparation stage, it is used to determine whether the vehicle meets a second condition; wherein the second condition is used to trigger abuse protection.

[0039] A current control module is used to limit the current of the motor to a target preset current corresponding to the target condition if one of the first condition and the second condition is met; wherein, the second preset current corresponding to the second condition is less than the first preset current corresponding to the first condition;

[0040] The current control module is further configured to limit the current of the motor to the second preset current if both the first condition and the second condition are met.

[0041] Thirdly, the present invention provides a vehicle comprising: a controller for implementing the control method of the electric power steering system as described in the first aspect above.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] This invention provides a control method, device, and vehicle for an electric power steering system (EPS), relating to the field of vehicle control technology. The method acquires vehicle information under current target operating conditions, including current vehicle speed, engine speed, steering wheel angle, and steering wheel torque. Engine speed includes steering wheel speed and the speed of the motor in the EPS system. Based on the target operating condition information, the method determines whether the vehicle meets a first condition. Based on the target operating condition information, the method determines whether the vehicle is in an abuse-prepared operating condition phase. When the vehicle is in the abuse-prepared operating condition phase, the method determines whether the vehicle meets a second condition. If either the first or second condition is met, the motor current is limited to a target preset current corresponding to the target condition. If both the first and second conditions are met, the motor current is limited to a second preset current. Using the control method provided by this invention prevents or delays the EPS from entering an overheat protection state, thus improving the performance of the EPS.

[0044] In this embodiment of the invention, current target operating condition information is obtained. Based on this information, it is determined whether the conditions for rack end protection and / or abuse protection are met. If so, a first preset current or a second preset current is used to limit the motor current, thereby preventing or delaying the EPS from continuously outputting a large current and rapidly entering the overheat protection state, effectively avoiding severe damage to the EPS electronic hardware caused by entering overheat protection. In this invention, by limiting the motor current to a smaller second preset current, the EPS outputs a smaller current under abuse protection, thus delaying the EPS from entering the overheat protection state and improving the EPS performance. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a flowchart illustrating the steps of the control method for the electric power steering system according to an embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram of the electric power steering system according to an embodiment of the present invention;

[0048] Figure 3 This is a flowchart illustrating the steps of a current limiting method according to an embodiment of the present invention;

[0049] Figure 4 This is a diagram showing the variation of the limiting current of the motor in an embodiment of the present invention;

[0050] Figure 5 This is a flowchart of the control method for the electric power steering system according to an embodiment of the present invention;

[0051] Figure 6 This is a flowchart of the method for outputting the abuse protection control state according to an embodiment of the present invention;

[0052] Figure 7 This is a flowchart of the method for the second current control module to output current in an embodiment of the present invention;

[0053] Figure 8 This is a schematic diagram of the control device of the electric power steering system according to an embodiment of the present invention. Detailed Implementation

[0054] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0055] The first aspect of the present invention provides an embodiment, with reference to Figure 1 , Figure 1 This is a flowchart illustrating the steps of a control method for an electric power steering system according to an embodiment of the present invention. The present invention provides a control method for an electric power steering system, the control method comprising the following steps:

[0056] S1, obtain the vehicle's current target operating condition information, which includes the current vehicle speed, engine speed, steering wheel angle, and steering wheel torque; the engine speed includes the steering wheel speed and the speed of the motor in the electric power steering system;

[0057] like Figure 2 As shown, the Electric Power Steering System (EPS) consists of a torque sensor, EPS controller, motor, reduction mechanism, and rack and pinion assembly. The working principle of EPS is as follows: when the driver does not turn the steering wheel, the EPS controller does not output current commands to the motor, the motor is not working, and the EPS is in standby mode. When the driver turns the steering wheel, it acquires vehicle operating condition information such as current vehicle speed, engine speed, steering wheel angle, and steering wheel torque, and inputs this information to the EPS controller. The EPS controller combines the detected actual motor current with the vehicle operating condition information to calculate and process the current control algorithm, obtaining the current of the power steering motor and the corresponding magnitude and direction of torque. The EPS controller controls the motor to output the power steering motor current. The torque generated by the motor is amplified by the reduction mechanism and then applied to the rack and pinion assembly, thereby obtaining a steering force suitable for the operating conditions and achieving vehicle steering.

[0058] The EPS controller can obtain the current vehicle speed and steering wheel speed via the CAN bus; the motor's rotor position sensor transmits the collected steering angle to the EPS controller, which analyzes and calculates to obtain the motor speed; the EPS controller can also directly obtain the steering wheel angle through the motor's rotor position sensor, and can also obtain the steering wheel torque through a torque sensor. The steering wheel torque can be used to determine the driver's hand force.

[0059] S2, based on the target operating condition information, determine whether the vehicle meets the first condition; wherein, the first condition is used to trigger the rack end protection;

[0060] It is understandable that when determining whether the vehicle meets the first condition, that is, when determining whether the vehicle enters rack end protection, the target operating condition information includes vehicle speed, engine speed, steering wheel angle and steering wheel torque. The embodiments of this application can determine whether the vehicle activates rack end protection based on conditions such as vehicle speed, engine speed, steering wheel angle and steering wheel torque.

[0061] Specifically, when the absolute value of the vehicle speed in the target operating condition information is less than the vehicle speed threshold, the absolute value of the engine speed is greater than the engine speed threshold, and the direction of the steering wheel angle is the same as the direction of the steering wheel torque, the first condition is met, triggering the rack end protection. For example, when the vehicle meets the first condition, the actual vehicle situation is that the steering wheel is turned to its end.

[0062] S3, based on the target operating condition information, determine whether the vehicle is in the abuse condition preparation stage; when the vehicle is in the abuse condition preparation stage, determine whether the vehicle meets the second condition; wherein, the second condition is used to trigger abuse protection.

[0063] In some embodiments, based on target operating condition information, it is determined whether the vehicle is in the abuse condition preparation stage; when the vehicle enters the abuse condition preparation stage, it is determined whether the vehicle meets a second condition, including: determining whether the vehicle is in the abuse condition preparation stage based on vehicle speed, engine speed, and steering wheel torque; when the vehicle is in the abuse condition preparation stage, determining the current duration of the vehicle; and determining whether the vehicle meets the second condition based on vehicle speed, engine speed, steering wheel torque, and duration.

[0064] In this embodiment of the application, determining whether a vehicle meets the second condition based on vehicle speed, engine speed, steering wheel torque, and duration includes: determining whether the absolute value of the vehicle speed is less than a vehicle speed threshold; whether the absolute value of the engine speed is less than an engine speed threshold; whether the absolute value of the steering wheel torque is greater than a steering wheel torque threshold; and whether the duration is greater than a preset duration.

[0065] Specifically, when determining whether a vehicle meets the second condition, the target operating condition information includes vehicle speed, engine speed, and steering wheel torque. If the absolute value of the vehicle speed is less than a vehicle speed threshold, the absolute value of the engine speed is less than an engine speed threshold, and the absolute value of the steering wheel torque is greater than a steering wheel torque threshold, it indicates that the actual vehicle is in the preparation phase for abuse protection. When the duration of this preparation phase reaches a preset duration (i.e., the duration is longer than the preset duration), the vehicle is in an abuse condition, which can trigger abuse protection, limiting the motor current to prevent or delay the EPS from continuously outputting a large current and rapidly entering the overheat protection state. Simultaneously, it can accurately identify the abuse protection condition. For example, an abuse condition can refer to: the vehicle being at a low speed and the steering wheel being turned to the end where the wheels are stuck, or the vehicle being at a low speed and the steering wheel not being turned to the end where the wheels are stuck.

[0066] Under abusive operating conditions, the EPS will continuously output a large current, which not only wastes power but also generates heat, causing the EPS to quickly enter overheat protection mode and potentially damaging its electronic hardware. Therefore, it is necessary to limit the motor current under abusive conditions, ensuring it operates at a lower current.

[0067] Among them, the vehicle speed threshold, engine speed threshold, steering wheel torque threshold, and preset duration can be calibrated according to the actual situation; in this embodiment, the target working condition information and preset duration are set as calibrable quantities, so as to be adaptable to different vehicle models.

[0068] S4. If the target condition of one of the first condition and the second condition is met, the current of the motor is limited to the target preset current corresponding to the target condition; wherein, the second preset current corresponding to the second condition is less than the first preset current corresponding to the first condition.

[0069] This can be understood as follows: when the first condition is met but the second condition is not, the rack end protection can be triggered, but the abuse protection cannot. Through the rack end protection function, the first current control module limits the motor current to a first preset current, thereby limiting the motor current and preventing or delaying the EPS from continuously outputting a large current and quickly entering the overheat protection state. At the same time, the rack end protection function can also extend the service life of the EPS: due to the current limitation, it can reduce the speed at which the driver turns the steering wheel, reduce the impact force at the end of the rack, reduce the impact force between the tie rod connected to the end of the rack and the rack housing, reduce mechanical wear, and thus extend the service life of the EPS.

[0070] When the second condition is met but the first condition is not met, abuse protection can be triggered, but rack end protection cannot. Through the abuse protection function, the second current control module limits the motor current to a smaller second preset current, thereby limiting the motor current and preventing or delaying the EPS from continuously outputting a large current and quickly entering the overheat protection state.

[0071] The first preset current and the second preset current can be calibrated according to the actual situation, that is, the magnitude of the first preset current and the second preset current is determined according to the actual working conditions.

[0072] S5. If both the first and second conditions are met, then the motor current is limited to the second preset current.

[0073] Specifically, when both the first and second conditions are met simultaneously, the rack end protection triggered under the first condition is used to extend the lifespan of the EPS, and no longer addresses the overheat protection issue. Therefore, limiting the motor current to the second preset current corresponding to the second condition allows the motor to operate at a lower current, achieving a lower degree of current limitation on the motor. This prevents or delays the EPS from continuously outputting a large current and rapidly entering the overheat protection state, effectively avoiding severe damage to the EPS electronic hardware caused by entering overheat protection.

[0074] When one of the first and second conditions is met, the motor current is limited to either the first or second preset current. This solves the problem of the EPS continuously outputting a large current and rapidly entering the overheat protection state under conditions of low vehicle speed and stuck steering wheels. At the same time, when the first condition for triggering rack end protection is not met, the motor current can be limited by the abuse protection triggered by the second condition, making the applicable operating conditions for preventing or delaying the EPS from continuously outputting a large current and rapidly entering the overheat protection state wider. When both the first and second conditions are met, the motor current is limited to the second preset current. This solves the problem that the EPS may also rapidly enter the overheat protection state if the rack end protection function alone cannot reduce the current to a relatively low level. This better prevents or delays the EPS from continuously outputting a large current and rapidly entering the overheat protection state.

[0075] In this embodiment of the invention, current target operating condition information is obtained. Based on this target operating condition information and its duration, it is determined whether the conditions for rack end protection and / or abuse protection are met. If met, a first preset current or a second preset current is used to limit the motor current, thereby preventing or delaying the EPS from continuously outputting a large current and rapidly entering the overheat protection state, effectively avoiding severe damage to the EPS electronic hardware caused by entering the overheat protection state. In this invention, by limiting the motor current to a smaller second preset current, the EPS outputs a smaller current under abuse protection, thereby delaying the EPS from entering the overheat protection state and improving the EPS performance.

[0076] In yet another embodiment of the present invention, in addition to including the steps in the embodiments described above,

[0077] Also includes:

[0078] In some implementations, if one of the first and second conditions is met, the motor current is limited to a target preset current corresponding to the target condition, including:

[0079] If the target condition is the first condition, then the motor current will be limited to the first preset current in real time;

[0080] If the target condition is the second condition, then the motor current will be limited to the second preset current during the first preset time period.

[0081] When the target condition is the first condition, it means that the condition for triggering abuse protection is not met, but the condition for triggering rack end protection is met. Therefore, rack end protection is triggered, and the motor current is limited to the first preset current in real time. This can reduce the impact force on the rack end, reduce the impact force between the tie rod connected to the rack end and the rack housing, reduce mechanical wear, and thus extend the service life of EPS.

[0082] When the target condition is the second condition, it means that the rack end protection cannot be triggered, but the condition for triggering abuse protection is met. Therefore, abuse protection is triggered. Figure 4 As shown, the motor current is limited to the second preset current within the first preset time period △t1, thereby solving the problem that the rack end protection cannot prevent overheating protection.

[0083] For example, if the actual vehicle situation is that the steering wheel is not turned to the end and the rack end protection cannot be triggered, it is determined whether the current vehicle is at a low speed and the wheels are stuck. If so, abuse protection is triggered, and the second preset current is used to prevent or delay the EPS from continuously outputting a large current and quickly entering the overheat protection state, so as to solve the working condition that the rack end protection cannot prevent overheat protection.

[0084] When the target condition is the second condition, the first preset time period can be set to a calibrable quantity, so as to adapt to different vehicle models.

[0085] For example, vehicle model 1 is in a state of heavy load, where the driver will use a lot of force to turn the steering wheel when stuck on a curb. The criteria for determining whether vehicle model 1 is in an abuse condition are: the absolute value of the vehicle speed is less than the calibrated value (determined according to the actual working conditions, such as a calibrated value of 2 km / h), the absolute value of the steering wheel torque is greater than the calibrated value (this calibrated value is a value that exceeds the range of the torque sensor; if the range of the torque sensor is 7 Nm, this calibrated value can be 7 Nm or greater than 7 Nm), and the absolute value of the steering wheel speed is less than the calibrated value (depending on the actual situation; since the vehicle is stuck on a curb, the calibrated value of the steering wheel speed is basically zero or a few degrees per second), with a preset duration of 10 seconds.

[0086] For example, vehicle model 2 is in a state where the load is slightly lighter than that of vehicle model 1, and the driver will use a lot of force to turn the steering wheel when stuck on a curb. The criteria for determining whether vehicle model 2 is in an abuse condition are: the absolute value of the vehicle speed is less than the calibrated value (determined according to the actual operating conditions, such as a calibrated value of 3 km / h), the absolute value of the steering wheel torque is greater than the calibrated value (the calibrated value is within the range of the torque sensor; if the range of the torque sensor is 7 Nm, the calibrated value can be 6.5 Nm), and the absolute value of the steering wheel speed is less than the calibrated value (depending on the actual situation; since the vehicle is stuck on a curb, the calibrated value of the steering wheel speed is basically zero or a few degrees per second), with a preset duration of 8 seconds.

[0087] It should be noted that due to differences in driver habits, steering feel, and vehicle conditions (e.g., different models have different axle loads and require different rack forces), all calibration values ​​and preset durations are based on actual vehicle conditions. For example, if the vehicle load is light, calibration can be performed using forces within the torque sensor's range; that is, when the torque sensor's range is 7 Nm, the steering wheel torque threshold can be 6.5 Nm. If the vehicle is heavy, the driver will apply more force, and calibration can be performed using values ​​exceeding the torque sensor's range. For heavy vehicles, the preset duration can be slightly longer, meaning the time spent stuck on the curb will be longer before entering the abuse protection function; for light vehicles, the preset duration can be slightly shorter, allowing the abuse protection function to be activated earlier.

[0088] In some implementations, if neither the first condition nor the second condition is met, the overheat protection function is triggered to limit the motor current.

[0089] In this embodiment, the specific steps are not limited by the present invention.

[0090] In some implementations, such as Figure 3 A flowchart illustrating the steps of a current limiting method is provided. If both a first condition and a second condition are met, the motor current is limited to a second preset current, including:

[0091] S51, if it is determined that the target working condition information first reaches the first condition and then the second condition, in response to the triggered first condition, the motor current is limited to the third preset current in real time; wherein the third preset current is greater than the first preset current.

[0092] S52, after limiting the motor current to a third preset current, in response to the triggering of the second condition, limits the motor current to a second preset current for a first preset time period.

[0093] Because only the first preset current under rack end protection is triggered, it is not enough to reduce the motor current to a relatively low level. This will still cause the EPS to quickly enter the overheat protection state. If the first preset current is limited to a very small value, the driver will feel a bouncy sensation when the wheel reaches the end, affecting the user's feel. If the first preset current is increased, it will not limit the motor current, and the EPS will quickly enter the overheat protection state. In severe cases, it will damage the EPS electronic hardware. As a result, when the wheels return to normal, the EPS performance cannot be restored immediately, thus affecting the vehicle's performance.

[0094] In this embodiment, the rack end protection function triggered by the first condition and the abuse protection function triggered by the second condition work together to improve the performance of the EPS. Since the abuse protection function triggered by the second condition is specifically designed to prevent or delay the EPS from continuously outputting large currents under abuse conditions and entering overheat protection, thus curbing rapid overheating of the EPS, the rack end protection function triggered by the first condition in this embodiment no longer addresses the overheat protection issue but is only used to extend the EPS's service life. Consequently, the motor current protected by the rack end is no longer limited to a very small setting and can be adjusted using the rack end protection function. Therefore, the third preset current under the simultaneous triggering condition can be set slightly larger than the first preset current under the condition where only the rack end protection is triggered, thus preventing a jolting sensation and facilitating driver feel adjustment.

[0095] Specifically, once the target operating condition information meets the first condition, the rack end protection is immediately triggered, limiting the motor current to the third preset current. At this time, the rack end protection is used to extend the EPS service life and also serves as an overheat protection function. As the target operating condition information accumulates, the abuse protection is triggered only after the target operating condition information reaches a preset duration. The second preset current is less than the third preset current. At this time, the abuse protection triggered limits the motor current to the second preset current within the first preset time period △t1 to prevent or delay the EPS from entering the overheat protection. The rack end protection no longer takes into account the problem of rapid overheat protection under the condition of large load and large current at the rack end. The rack end protection is only used to extend the EPS service life.

[0096] For example, in actual vehicle conditions, when the steering wheel is turned to the end, the EPS immediately triggers rack end protection, limiting the motor current to a third preset current, thereby extending the EPS's service life and preventing overheating protection; as the vehicle speed, RPM, and steering wheel torque accumulate, when the vehicle is at a low speed and the steering wheel is turned to the end, causing the tires to be stuck, and after 8 seconds, abuse protection is triggered, and within a first preset time period △t1, the motor current is slowly reduced to a second preset current.

[0097] In some implementations, when the motor current is limited to a second preset current during a first preset time period, the control method includes:

[0098] Get the current current of the motor;

[0099] Based on the current current and the first preset time period, determine the slope at which the current current decreases to the second preset current;

[0100] Based on the slope, the current is reduced to a second preset current.

[0101] The first preset time period △t1 can be calibrated according to the actual situation, and the second preset current can also be calibrated according to the actual situation.

[0102] In this embodiment, the slope is determined by a calibrated first preset time period Δt1 and a calibrated second preset current. Based on this slope, the motor limiting current can be gradually reduced to the calibrated second preset current, thereby achieving driver's feel adjustment after the abuse protection function is triggered. If no slope is set, the motor limiting current will drop instantly from the current to a lower second preset current, which will inevitably cause fluctuations in hand force, thus greatly affecting the driver's feel.

[0103] like Figure 4 As shown, the motor limiting current decreases from the current to the second preset current within the first preset time period Δt1. After the motor limiting current decreases to the second preset current, the motor limiting current remains stable at the second preset current for a constant time period, indicating that the abuse protection is always in the triggered state, thereby effectively preventing or delaying the EPS from continuously outputting a large current and entering the overheat protection.

[0104] In some implementations, after limiting the motor current to a second preset current, the control method includes:

[0105] Determine whether the vehicle has exited the second condition based on the current vehicle speed, engine speed, and steering wheel torque;

[0106] If so, the motor current will be increased from the second preset current within the second preset time period.

[0107] When it is determined that any of the current vehicle speed, engine speed, or steering wheel torque values ​​does not meet the second condition, the second current control module will increase the motor current from the second preset current to a value greater than the second preset current, thereby enabling the abuse protection to be deactivated.

[0108] Specifically, the rising slope is determined based on the current second preset current and the second preset time period Δt2; based on the rising slope, the motor current is increased from the current second preset current.

[0109] In some implementations, increasing the motor current from a second preset current within a second preset time period includes:

[0110] Determine whether the first condition is met when the vehicle exits the operating condition corresponding to the second condition;

[0111] If so, the motor current will be increased from the second preset current to the first preset current within the second preset time period.

[0112] If not, the motor current will be increased from the second preset current to the target current value within the second preset time period; wherein the target current value is the motor current determined based on the current operating conditions of the vehicle.

[0113] The second preset time period △t2 can be calibrated according to the actual situation, and the second preset current can also be calibrated according to the actual situation; the target current value can also be calibrated according to the actual situation.

[0114] Because the second preset time period Δt2 and the second preset current have been calibrated, the motor current rises from the second preset current to the first preset current or the target current value at a certain slope, thus enabling the driver to adjust the feel after the abuse protection function is deactivated. If the second preset time period Δt2 and the second preset current cannot be calibrated, the motor limiting current will drop instantaneously, inevitably causing fluctuations in hand force, which will greatly affect the driver's feel.

[0115] For example, when the vehicle exits the operating condition of the second condition, it is determined that the first condition is met, and the motor current is increased from the second preset current to the first preset current.

[0116] For example, when it is determined that the first condition is not met when the vehicle exits the operating condition of the second condition, the motor current is increased from the second preset current to the motor current determined by the current operating condition of the vehicle. At this time, the motor current determined by the current operating condition of the vehicle is exactly the current current before the rack end protection and abuse protection are triggered. Figure 4 As shown, within the second preset time period △t2, the motor current rises from the second preset current to the current current at a certain slope.

[0117] The first aspect of the present invention provides an embodiment, with reference to Figure 5 ,like Figure 5 A flowchart of a control method for an electric power steering system is shown. The control method includes:

[0118] When the vehicle gets stuck on a curb, or the steering wheel is not turned to the end and the steering wheel is stuck, the current vehicle speed, steering wheel speed, and steering wheel torque are acquired and transmitted to the second input signal processing module.

[0119] The second input signal processing module determines whether the vehicle is in the abuse condition preparation stage based on the current vehicle speed, steering wheel speed, and steering wheel torque; when the vehicle is in the abuse condition preparation stage, it determines whether the vehicle meets the second condition; wherein, the second condition is used to trigger abuse protection.

[0120] Specifically, when the absolute value of vehicle speed in the target operating condition information is less than the vehicle speed threshold, the absolute value of steering wheel speed is less than the speed threshold, and the absolute value of steering wheel torque is greater than the steering wheel torque threshold, it indicates that the actual vehicle is in the preparation stage of abuse protection.

[0121] When a vehicle is in the abusive condition preparation phase, determine the current duration of the vehicle's operation; then, based on the vehicle speed, steering wheel speed, steering wheel torque, and duration, determine whether the vehicle meets the second condition.

[0122] If the vehicle meets the second condition, it means that the vehicle meets the conditions for triggering abuse protection. Figure 6 The flowchart shown illustrates the method for outputting the abuse protection control state. After the second input signal processing module sets the abuse protection control state to 1, it outputs the abuse protection control state to the second current control module.

[0123] like Figure 7 The flowchart shown illustrates the method of the second current control module outputting current. The second current control module responds to the abuse protection control state set to 1 and outputs a limiting current for the motor according to a calibrated second preset current to limit the current of the motor.

[0124] If the second condition is not met, it means that the condition for triggering abuse protection is not met. Then, the second input signal processing module sets the abuse protection control state to 0 and outputs the abuse protection control state to the second current control module. In response to the abuse protection control state being set to 0, the second current control module does not output the limiting current.

[0125] Secondly, such as Figure 8 As shown, the present invention provides a control device for an electric power steering system, the control device comprising:

[0126] The acquisition module is used to acquire the vehicle's current target operating condition information, which includes the current vehicle speed, engine speed, steering wheel angle, and steering wheel torque; the engine speed includes the steering wheel speed and the speed of the motor in the electric power steering system.

[0127] The first input signal processing module is used to determine whether the vehicle meets a first condition based on the target operating condition information; wherein the first condition is used to trigger rack end protection.

[0128] The second input signal processing module is used to determine whether the vehicle is in the abuse condition preparation stage based on the target operating condition information; when the vehicle is in the abuse condition preparation stage, it is used to determine whether the vehicle meets a second condition; wherein the second condition is used to trigger abuse protection.

[0129] The current control module is used to limit the motor current to the target preset current corresponding to the target condition if one of the first condition and the second condition is met; wherein, the second preset current corresponding to the second condition is less than the first preset current corresponding to the first condition.

[0130] The current control module is also used to limit the motor current to a second preset current if both the first and second conditions are met.

[0131] In this embodiment of the invention, an input signal processing module is used to determine that the current vehicle operating condition meets the conditions for rack end protection and / or abuse protection, and a current control module is used to limit the motor current, thereby preventing or delaying the EPS from continuously outputting a large current under the target operating condition and quickly entering the overheat protection state, so as to effectively avoid serious damage to the EPS electronic hardware caused by entering the overheat protection.

[0132] The acquisition module includes a first acquisition module and a second acquisition module. The first acquisition module is used to acquire the target operating condition information required for the first condition, and the second acquisition module is used to acquire the target operating condition information required for the second condition. The current control module includes a first current control module and a second current control module. The first current control module is used to limit the current of the motor in the electric power steering system to a first preset current after the first condition is met. The second current control module is used to limit the current of the motor to a second preset current after the second condition is met, or after both the first and second conditions are met.

[0133] In some implementations, the second input signal processing module can be used to determine whether the vehicle is in an abuse condition preparation phase based on the vehicle speed, the rotational speed, and the steering wheel torque; when the vehicle is in the abuse condition preparation phase, determine the current duration of the vehicle; and determine whether the vehicle meets a second condition based on the vehicle speed, the rotational speed, the steering wheel torque, and the duration.

[0134] In some implementations, the second input signal processing module can be used to determine whether the vehicle meets the second condition based on whether the absolute value of the vehicle speed is less than a vehicle speed threshold; whether the absolute value of the rotational speed is less than a rotational speed threshold; whether the absolute value of the steering wheel torque is greater than a steering wheel torque threshold; and whether the duration is greater than a preset duration.

[0135] In some implementations, the first current control module can be used to limit the motor current to a first preset current or a third preset current in real time in response to a first triggered condition.

[0136] The second current control module can be used to limit the motor current to a second preset current within a first preset time period in response to the triggering of the second condition.

[0137] In some implementations, the second current control module can be used to determine, based on the current current and a first preset time period, the slope at which the current current decreases to a second preset current; and based on the slope, to decrease the current current to the second preset current.

[0138] In some implementations, the second input signal processing module can be used to determine whether the vehicle has exited the second condition based on the current vehicle speed, engine speed, and steering wheel torque.

[0139] The second current control module can be used to increase the motor current from the second preset current within a second preset time period.

[0140] In some implementations, the first input signal processing module can be used to determine whether the first condition is met when the vehicle exits the operating condition corresponding to the second condition;

[0141] The first current control module can be used to increase the motor current from the second preset current to the first preset current within a second preset time period.

[0142] It can also be used to increase the motor current from a second preset current to a target current value within a second preset time period; wherein the target current value is the motor current determined based on the current operating conditions of the vehicle.

[0143] Thirdly, the present invention provides a vehicle comprising: a controller for implementing a control method for an electric power steering system as described in the first aspect above.

[0144] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0145] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0146] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0147] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not describe the various possible combinations separately.

[0148] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A control method for an electric power steering system, characterized in that, The control method includes: The system acquires the vehicle's current target operating condition information, which includes the current vehicle speed, engine speed, steering wheel angle, and steering wheel torque; the engine speed includes the steering wheel speed and the speed of the motor in the electric power steering system. Based on the target operating condition information, it is determined whether the vehicle meets the first condition; wherein, the first condition is used to trigger rack end protection; Based on the target operating condition information, it is determined whether the vehicle is in the abuse condition preparation stage; when the vehicle is in the abuse condition preparation stage, it is determined whether the vehicle meets the second condition; wherein, the second condition is used to trigger abuse protection. If one of the first and second conditions is met, the current of the motor is limited to the target preset current corresponding to the target condition; wherein, the second preset current corresponding to the second condition is less than the first preset current corresponding to the first condition. If both the first condition and the second condition are met, then the current of the motor is limited to the second preset current; The step of determining whether the vehicle meets the first condition based on the target operating condition information includes: Based on whether the absolute value of the vehicle speed is less than a vehicle speed threshold; Furthermore, whether the absolute value of the rotational speed is greater than a rotational speed threshold; Furthermore, whether the direction of the steering wheel angle is the same as the direction of the steering wheel torque determines whether the vehicle meets the first condition; Specifically, determining whether the vehicle is in the abuse condition preparation stage based on the target operating condition information; and determining whether the vehicle meets the second condition when it is in the abuse condition preparation stage, including: Based on the vehicle speed, the rotational speed, and the steering wheel torque, determine whether the vehicle is in the abuse condition preparation stage; When the vehicle is in the abuse condition preparation phase, the current duration of the vehicle is determined; Based on the vehicle speed, the engine speed, the steering wheel torque, and the duration, determine whether the vehicle meets the second condition; The determination of whether the vehicle meets the second condition based on the vehicle speed, the engine speed, the steering wheel torque, and the duration includes: Based on whether the absolute value of the vehicle speed is less than a vehicle speed threshold; Furthermore, whether the absolute value of the rotational speed is less than a rotational speed threshold; Furthermore, whether the absolute value of the steering wheel torque is greater than the steering wheel torque threshold; Furthermore, whether the duration is greater than the preset duration determines whether the vehicle meets the second condition.

2. The control method according to claim 1, characterized in that, The step of limiting the motor current to a target preset current corresponding to the target condition if either the first condition or the second condition is met includes: If the target condition is the first condition, then the current of the motor is limited to the first preset current in real time; If the target condition is the second condition, then the current of the motor will be limited to the second preset current during the first preset time period.

3. The control method according to claim 1, characterized in that, If both the first condition and the second condition are met, then limiting the current of the motor to the second preset current includes: If it is determined that the target operating condition information first reaches the first condition and then the second condition, in response to the triggered first condition, the current of the motor is limited to a third preset current in real time; wherein the third preset current is greater than the first preset current; After limiting the current of the motor to the third preset current, in response to the triggering of the second condition, the current of the motor is limited to the second preset current for a first preset time period.

4. The control method according to claim 3, characterized in that, When the current of the motor is limited to the second preset current during a first preset time period, the control method includes: Obtain the current current of the motor; Based on the current current and the first preset time period, determine the slope at which the current current decreases to the second preset current; Based on the slope, the current is reduced to the second preset current.

5. The control method according to claim 1, characterized in that, After limiting the current of the motor to the second preset current, the control method includes: Based on the current vehicle speed, engine speed, and steering wheel torque, determine whether the vehicle has exited the second condition; If so, the current of the motor will be increased from the second preset current within the second preset time period.

6. The control method according to claim 5, characterized in that, The step of increasing the motor current from the second preset current within the second preset time period includes: Determine whether the first condition is met when the vehicle exits the operating condition corresponding to the second condition; If so, then during the second preset time period, the current of the motor will be increased from the second preset current to the first preset current; If not, then within the second preset time period, the motor current will be increased from the second preset current to the target current value; wherein the target current value is the motor current determined based on the current operating conditions of the vehicle.

7. A control device for an electric power steering system, characterized in that, The control device includes: The acquisition module is used to acquire the vehicle's current target operating condition information, which includes the current vehicle speed, engine speed, steering wheel angle, and steering wheel torque; the engine speed includes the steering wheel speed and the speed of the motor in the electric power steering system. The first input signal processing module is used to determine whether the vehicle meets a first condition based on the target operating condition information; wherein the first condition is used to trigger rack end protection. The second input signal processing module is used to determine whether the vehicle is in the abuse condition preparation stage based on the target operating condition information; when the vehicle is in the abuse condition preparation stage, it is used to determine whether the vehicle meets a second condition; wherein the second condition is used to trigger abuse protection. A current control module is used to limit the current of the motor to a target preset current corresponding to the target condition if one of the first condition and the second condition is met; wherein, the second preset current corresponding to the second condition is less than the first preset current corresponding to the first condition; The current control module is also used to limit the current of the motor to the second preset current if both the first condition and the second condition are met. The step of determining whether the vehicle meets the first condition based on the target operating condition information includes: Based on whether the absolute value of the vehicle speed is less than a vehicle speed threshold; Furthermore, whether the absolute value of the rotational speed is greater than a rotational speed threshold; Furthermore, whether the direction of the steering wheel angle is the same as the direction of the steering wheel torque determines whether the vehicle meets the first condition; The second input signal processing module is used to determine whether the vehicle is in the abuse condition preparation stage based on the vehicle speed, the rotational speed, and the steering wheel torque; when the vehicle is in the abuse condition preparation stage, it determines the current duration of the vehicle; and based on the vehicle speed, the rotational speed, the steering wheel torque, and the duration, it determines whether the vehicle meets the second condition. The second input signal processing module is used to determine whether the vehicle meets the second condition based on whether the absolute value of the vehicle speed is less than a vehicle speed threshold; whether the absolute value of the rotational speed is less than a rotational speed threshold; whether the absolute value of the steering wheel torque is greater than a steering wheel torque threshold; and whether the duration is greater than a preset duration.

8. A vehicle, characterized in that, include: A controller for implementing the control method of the electric power steering system as described in any one of claims 1-6.

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