Transient high current suppression method for electric power steering system under mechanical impact working condition

Abstract

The present application belongs to the technical field of automobile steering system, especially relates to a method for suppressing instantaneous high current under mechanical impact working condition of electric power steering system, comprising obtaining first, second, third and fourth voltage limits, and performing weighted summation to obtain target voltage limit; obtaining rated assist motor maximum terminal voltage of electric power steering system. The present application combines the four voltage limits to calculate the target voltage limit, obtains the real-time allowed maximum motor voltage through calculation, and obtains the PWM waveform output to the motor after inverse Park transformation and inverse Clarke, which can limit the motor terminal voltage, thereby reducing the risk of instantaneous high current and power supply voltage drop in the steering process, and preventing damage to the electric power steering system.

Description

Technical Field

[0001] This invention belongs to the field of automotive steering system technology, and in particular relates to a method for suppressing instantaneous high current under mechanical impact conditions in an electric power steering system. Background Technology

[0002] Stand-on reach trucks are core material handling equipment in warehousing, logistics, distribution centers, and manufacturing. They are primarily used for frequent cargo transfers and high-level stacking, and their operational efficiency and safety directly impact the efficiency of the logistics process. Considering their operational characteristics, the steering system must meet two core requirements: first, light and flexible steering to reduce the physical exertion of operators from frequent turning over long periods and improve operational comfort; second, sufficient steering angle, with some products offering steering angles exceeding 90° to adapt to narrow working spaces and improve space utilization.

[0003] To prevent oversteering from damaging steering components or causing vehicle instability, existing stand-on reach trucks generally use mechanical limit devices to restrict the steering angle. This solution is simple in structure and low in cost, making it the mainstream limit method in the industry. However, due to the design constraints of light and flexible steering, in actual operation, when the driver makes a rapid turn, the steering mechanism is prone to high-speed impact with the mechanical limit, leading to a sudden stop of the power steering motor. At this time, the voltage difference across the motor is entirely converted into a high instantaneous current. If the equipment uses DC power supply, this high instantaneous current may cause a DC voltage drop, which not only affects the normal operation of the electric power steering system (EPS) but may also damage the EPS system and other on-board electronic equipment, reducing the operational reliability and service life of the equipment.

[0004] Currently, the electric power steering systems used in stand-on reach stackers primarily employ two types of protection schemes against impacts at the end of the steering stroke: one is to limit the power assist current at the end of the steering stroke to reduce the impact force; the other is to detect the motor speed and increase the reverse damping force as the steering approaches the end, achieving buffer deceleration. However, both of these schemes have significant drawbacks, resulting in a heavier steering feel at the end of the stroke, which contradicts the core requirement of "light and flexible steering" for the equipment.

[0005] The key issue is that these forklifts require frequent large-angle steering. Existing electric power steering systems have limited assist current reduction and reverse damping force at the end of the steering stroke, failing to provide effective buffering and making it difficult to prevent high-speed impacts of the steering mechanism against the mechanical limit switch. Furthermore, under complex operating conditions (such as steering mechanism jamming or the presence of raised obstacles on the ground), the steering mechanism may not have reached the end-protection angle before a high-speed impact occurs, causing the motor to stop abruptly. In this situation, existing protection schemes completely fail, further exacerbating the risks of instantaneous high current and DC voltage drops. This can easily damage the electric power steering system and other electronic equipment, increasing equipment maintenance costs and downtime losses.

[0006] In summary, the existing electric power steering system of the stand-on reach stacker truck still cannot effectively solve the problems of instantaneous high current and DC voltage drop caused by sudden stop of the power steering motor. It is difficult to adapt to special working conditions such as narrow spaces and frequent large-angle turns, and has drawbacks such as high risk of equipment damage and insufficient operational reliability. Summary of the Invention

[0007] In view of this, the present invention aims to provide a method for suppressing instantaneous high current under mechanical impact conditions in an electric power steering system, in order to at least overcome one of the problems in the prior art.

[0008] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions includes: Get the current steering wheel angle of the vehicle Steering wheel torque Assist motor speed Bus current from vehicle power supply to electric power steering system The power supply voltage from the vehicle's power source to the electric power steering system ; According to the steering wheel angle and steering wheel torque The first voltage limiting segment is calculated based on preset angle and torque determination rules. ; According to the speed of the assist motor and steering wheel torque The second voltage limit is calculated based on the preset motor speed determination rules. ; Based on the bus current from the vehicle power supply to the electric power steering system The third voltage limit is calculated based on the preset bus current determination rule. ; Based on the power supply voltage from the vehicle's power source to the electric power steering system The fourth voltage limit is calculated based on the preset power supply voltage determination rules. ; Obtain the first voltage limit Second stage voltage limiting Third stage voltage limiting Fourth stage voltage limiting For the first stage of voltage limiting Second stage voltage limiting Third stage voltage limiting Fourth stage voltage limiting The target voltage limit is obtained by assigning weight coefficients to each component and then performing a weighted summation. Among them, the sum of all weight coefficients is less than or equal to 1; Obtain the rated maximum terminal voltage of the power steering motor of the electric power steering system. and And limit according to the target voltage The current allowable motor terminal voltage is calculated based on the preset motor terminal voltage determination rules. and Utilizing the current allowable motor terminal pressure and Implement terminal voltage limiting to suppress instantaneous peak current.

[0009] Compared with existing technologies, the instantaneous high current suppression method for electric power steering systems under mechanical impact conditions described in this invention has the following advantages: (1) The instantaneous high current suppression method for electric power steering systems under mechanical impact conditions described in this invention has the following advantages: First, the first stage of voltage limiting plays a preventative role. When the electric power steering system detects a potential impact, it begins to reduce the power assist output, thus weakening the impact force. Second, the second stage of voltage limiting further restricts the maximum motor terminal voltage when an impact occurs, suppressing the current increase and keeping the current within a controllable range. Third, the third stage of voltage limiting identifies an impact and indicates that the current has deviated from the normal operating range, further limiting the maximum motor terminal voltage to minimize the current height and reduce the risk of damage to the electric power steering system and other electronic equipment due to high current. Fourth, the fourth stage of voltage limiting suppresses the voltage drop after a voltage dip is detected, preventing the equipment from restarting due to low voltage. Therefore, this instantaneous high current suppression method helps avoid restarting of electric power steering equipment or other equipment, thereby reducing the risk to the system and equipment.

[0010] (2) The instantaneous high current suppression method for electric power steering system under mechanical impact conditions described in this invention, by adjusting... , , , These four voltage limit calculation coefficients can adjust the starting speed of each voltage limit according to the vehicle model, thereby adapting to different electric power steering systems, power supplies, and vehicle models.

[0011] (3) The instantaneous high current suppression method for electric power steering system under mechanical impact conditions described in this invention, by adjusting... , , , The weights of these four voltage limits allow each voltage limit to be adjusted according to the vehicle as a whole, thus adapting to different electric power steering systems, power supplies, and vehicle models.

[0012] (4) The instantaneous high current suppression method of electric power steering system under mechanical impact conditions described in this invention can achieve real-time dynamic adjustment, avoid affecting the normal use of the product, and play a role at critical moments.

[0013] (5) The instantaneous high current suppression method of electric power steering system under mechanical impact condition described in this invention is often used with a DC power supply when the product is powered by DC to prevent the possible instantaneous high current from causing the DC power supply to malfunction. This function can greatly reduce the possible instantaneous high current, thereby reducing the DC power requirement.

[0014] (6) The instantaneous high current suppression method of electric power steering system under mechanical impact condition described in this invention can effectively suppress the instantaneous high current when the product is using DC power supply, prevent the instantaneous high current from affecting the DC power supply, and help reduce the requirements for DC power.

[0015] (7) The instantaneous high current suppression method of electric power steering system under mechanical impact conditions described in this invention, wherein the four voltage limiting segments operate independently and autonomously, and can adapt to various sudden conditions. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of a method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions, as described in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the calculation process for a method to suppress instantaneous high current under mechanical impact conditions in an electric power steering system, as described in Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the instantaneous high current suppression system under mechanical impact conditions in the electric power steering system according to Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the structure of an electronic terminal according to Embodiment 3 of the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0018] Example 1 Figure 1 This is a flowchart of a method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions, as described in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram illustrating the calculation process of a method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions, as described in Embodiment 1 of the present invention. (See also...) Figure 1 and Figure 2 This method specifically includes the following steps: Step 101: Obtain the vehicle's current steering wheel angle, steering wheel torque, power steering motor speed, bus current from the vehicle power supply to the electric power steering system, and power supply voltage from the vehicle power supply to the electric power steering system.

[0019] Step 102: Calculate the first voltage limit based on the steering wheel angle and steering wheel torque, and based on the preset angle and torque determination rules.

[0020] Step 103: Calculate the second voltage limit based on the power assist motor speed and steering wheel torque, and based on the preset motor speed determination rules.

[0021] Step 104: Calculate the third voltage limit based on the bus current from the vehicle power supply to the electric power steering system and the preset bus current determination rules.

[0022] Step 105: Calculate the fourth voltage limit based on the power supply voltage from the vehicle power supply to the electric power steering system and the preset power supply voltage determination rule.

[0023] Step 106: Obtain the first voltage limit, the second voltage limit, the third voltage limit, and the fourth voltage limit; assign weight coefficients to the first voltage limit, the second voltage limit, the third voltage limit, and the fourth voltage limit, and perform a weighted summation to obtain the target voltage limit; wherein the sum of each weight coefficient is less than or equal to 1.

[0024] Step 107: Obtain the rated maximum terminal voltage of the electric power steering system's power steering motor, and calculate the current allowable motor terminal voltage based on the preset motor terminal voltage determination rule according to the target voltage limit. Use the current allowable motor terminal voltage to achieve terminal voltage limitation in order to suppress instantaneous peak current.

[0025] Step 108: Obtain the current allowed motor terminal voltage, and after inverse Park transform and inverse Clarke transform, obtain the PWM waveform and output it to the motor. Use the PWM waveform to control the motor terminal voltage. Limitations are used to suppress instantaneous peak current.

[0026] In practical applications, this method, by analyzing the steering wheel angle, steering wheel torque, motor speed, bus current, and supply voltage of the electric power steering system, enables the limitation and control of the motor voltage under specific conditions. Specifically, it involves... male As can be seen from the formula, when an impact occurs during a rapid turn, the motor speed... Gradually decreasing to 0, due to the motor's internal resistance Motor structural constants ,magnetic flux It will not produce sudden and uncontrollable changes, and the pressure at the motor end will not be affected. If the motor speed remains constant, the energy generated by the reduced speed will be entirely converted into current, resulting in a momentary high current. At this time, through... , , , Four-segment voltage limiting is used to identify the occurrence of impact conditions and to limit the motor terminal voltage. This method can reduce the magnitude of the current increase and the potential voltage drop, which helps to reduce the risk of damage to the electric power steering system and other electronic equipment caused by instantaneous high current and voltage drop.

[0027] The method provided in this embodiment, in addition to calculating the first-segment end voltage limit through steering wheel angle and steering wheel torque, also includes... Furthermore, the second-stage end voltage limit is obtained by differentiating the motor speed and steering wheel torque. Furthermore, by differentiating the current, the rate of change of the current is obtained, and combined with the current, the voltage limit at the end of the third segment is calculated. Simultaneously, the voltage rate of change is obtained by differentiating the voltage, and the fourth voltage limiting is calculated by combining this with the current voltage. .

[0028] Then combine , , , The target voltage limit is obtained from the four-segment voltage limiting calculation. Limit the target voltage The rated maximum voltage of the power steering motor in the electric power steering system programming and The above method involves multiplying the target voltage limit by the maximum motor voltage designed in the program to obtain the real-time maximum motor voltage, thus yielding the real-time allowable maximum motor voltage. and ,Will and After inverse Park transform and inverse Clarke transform, the PWM waveform output to the motor is obtained, thereby limiting the motor terminal voltage. This reduces the risk of instantaneous high current and voltage drop during steering, thus reducing the risk of damage to the electric power steering system and other electronic equipment.

[0029] Using the above-described configuration, the instantaneous high current suppression method for electric power steering systems under mechanical impact conditions provided in this embodiment can suppress instantaneous high current and the voltage drop of the power supply, thereby reducing the risk of damage to the electric power steering system and other electronic equipment under impact conditions. It is applicable to electric power steering systems.

[0030] In one embodiment of this example, the first segment voltage limiting is based on preset angle and torque determination rules. The calculation formula is as follows:

[0031] in, The activation angle for counter-clockwise impact protection is... The angle at which counter-clockwise impact protection reaches its maximum; The activation angle for impact protection is clockwise. The angle at which clockwise impact protection reaches its maximum; secondly, To protect the starting torque in case of impact, The maximum steering wheel torque value collected; again, The calculation coefficient for the first voltage limiting segment should satisfy the following range: .

[0032] For example, , The corresponding steering wheel angles all differ from the maximum steering wheel angle by 0°-2°. The corresponding steering wheel angles differ by 10°-20°. and The corresponding steering wheel angles differ by 10°-20°, and the impact protection transition angles in both directions should remain consistent. and The angle difference is equal to and The angles differ.

[0033] It should be noted that in the above formula and the following formula, counterclockwise rotation is a positive value, and clockwise rotation is a negative value.

[0034] In practical applications, the angle at which the impact protection reaches its maximum differs from the maximum steering angle of the steering wheels by 0°-2°, ensuring that the steering angles designed for the entire vehicle can be used normally. The difference between the steering wheel angle when the impact protection is activated and the steering wheel angle at which the impact protection reaches its maximum is 10°-20°, providing a transition range for the protection and preventing sudden changes in power assist. However, the difference should not be too large to avoid affecting the feel during normal steering. The starting torque for impact protection can be referenced from the steering wheel torque value collected during normal steering. This is the maximum steering wheel torque value collected by the controller.

[0035] In one embodiment of this example, the second voltage limiting is based on a preset motor speed determination rule. The calculation formula is as follows:

[0036] in, Motor speed versus time Perform differentiation, Steering wheel torque versus time Perform differentiation, The threshold value for identifying impact conditions is determined by referencing the values ​​calculated when a normal steering maneuver collides with a mechanical limit switch or a bumpy road surface. value; In the above formula, The calculation coefficient for the second voltage limiting stage is given by the following formula:

[0037] in, To prevent the electric power steering system from rapidly impacting the mechanical limit switch when unloaded, The calculated maximum value.

[0038] Specifically, step 103 includes the following steps: When the driver is working on a smooth road, the direction of the motor speed signal is the same as the direction of the steering wheel torque. When the power steering motor comes to an abrupt stop due to an impact, the motor speed decreases and the steering wheel torque increases. The increase and decrease of the two satisfy the following formula: ; Because on bumpy roads, there may be a discrepancy between the motor speed signal direction and the steering wheel torque, it is necessary to... The results are filtered, and the following conditions are used to identify impact conditions, as shown in Formula 2: ; When both Formula 1 and Formula 2 are satisfied, the second voltage limit can be calculated. .

[0039] It should be noted that, The threshold for identifying impact conditions can be determined by referring to the values ​​calculated when a normal steering maneuver collides with a mechanical limit switch or a bumpy road surface. Value. Additionally... When the protection function of this method is not activated, the electric power steering system will rapidly impact the mechanical limit switch under no-load conditions. The calculated maximum value.

[0040] In one embodiment of this example, the third-stage voltage limiting is based on a preset bus current determination rule. The calculation formula is as follows:

[0041] in, Bus current versus time Perform differentiation, The threshold value for bus current impact protection is taken with reference to the bus current when the electric power steering system provides maximum assistance. In the above formula, The calculation coefficient for the third voltage limiting stage is given by the following formula:

[0042] in, To prevent the electric power steering system from rapidly impacting the mechanical limit switch when unloaded (e.g., with the steering wheels suspended in the air), The calculated maximum value, This is the maximum bus current collected at this time.

[0043] It should be noted that, The threshold value for bus current impact protection is taken with reference to the electric power steering system, providing the bus current at maximum assist. When this protection function is not activated, the electric power steering system will rapidly impact the mechanical limit switch under no-load conditions. The calculated maximum value, The maximum bus current collected under this condition should be referenced if DC power is used.

[0044] In one embodiment of this example, the fourth voltage limiting is based on a preset power supply voltage determination rule. The calculation formula is as follows:

[0045] in, The voltage supplied to the electric power steering system in relation to time Perform differentiation, The impact protection voltage activation threshold is designed with reference to the power supply voltage fluctuation under normal operating conditions, and is generally designed to be the minimum power supply voltage value collected during normal turning. In the above formula, The calculation coefficient for the third voltage limiting stage is given by the following formula:

[0046] in, When the vehicle's power is directly turned off, The calculated maximum value, The minimum operating voltage required to provide assistance to an electric power steering system varies depending on the voltage system.

[0047] It should be noted that, The impact protection voltage activation threshold can be designed with reference to the power supply voltage fluctuation under normal operating conditions. It is generally designed to be the minimum power supply voltage value collected during normal turning.

[0048] In one embodiment of this method, the method further includes the following steps: When the calculated second voltage limit When the voltage is greater than 100, the second voltage limit is applied. Take 100. Specifically, because... , The size and changes are uncontrollable, so The value should be too large, and the calculated value should be too high. If the value is greater than 100, it will be used as 100 in subsequent calculations.

[0049] When the calculated third voltage limit When the voltage is greater than 100, the third voltage limit is applied. Set the value to 100. Specifically, when the third voltage limit occurs... At that time, the situation proved to be quite serious, so the voltage limiting calculation coefficient for the third stage needed to be larger to enable the protection to start faster. Simultaneously, the calculated... When the value is greater than 100, it will be used as 100 in subsequent calculations.

[0050] When the calculated fourth segment voltage limit When the voltage is greater than 100, the fourth voltage segment is limited. Set the value to 100. Specifically, when the fourth voltage limit occurs... At that time, the situation proved to be quite serious, and under different voltage systems, the rate of voltage drop might not change much, but the difference between the maximum and minimum operating voltage of the electric power steering system would vary significantly. Therefore, the fourth stage of voltage limiting... The calculation coefficients need to be set according to different voltage systems to enable faster protection activation. Therefore, the calculated fourth voltage limit... When the value is greater than 100, it will be used as 100 in subsequent calculations.

[0051] In one embodiment of this example, the target voltage is limited. The formula for calculating the weighted sum is as follows:

[0052] in, , , , They are respectively , , , The weighting coefficients for the four-segment voltage limiting , , , All four weighting coefficients are greater than 0, and It should be noted that the weighting coefficients for the four-stage voltage limiting need to be designed according to the actual vehicle, for example... and While maintaining a good feel, the current should be adjusted as high as possible. For example, in a real vehicle, the greater the current increase during a high-speed cornering collision and sudden stop, the better. It also needs to be adjusted more significantly; correspondingly, the greater the voltage drop, the more... It also needs to be adjusted significantly.

[0053] Furthermore, in the event of a high-speed collision and sudden stop during a real-world vehicle's steering maneuver, if... yes If the current is less than twice that of the electric power steering system and its power supply, and is within the normal operating current range of the electric power steering system and its power supply, then ,otherwise , This refers to the maximum bus current collected when the electric power steering system rapidly impacts the mechanical limit switch under no-load conditions. This is the bus current impact protection activation threshold; if, under no-load impact, the minimum supply voltage of the electric power steering system is greater than... ,but ,otherwise , The minimum operating voltage required to provide assistance to an electric power steering system varies depending on the voltage of the system. This is the threshold voltage for triggering the impact protection. For example, the minimum operating voltage for a 48V system is 32V.

[0054] In practical applications, the first stage of voltage limiting... Its main function is to prevent potential impacts by limiting the maximum motor terminal voltage when a collision is detected, thereby reducing the impact force. The second stage is voltage limiting. The main function is to further limit the maximum motor terminal voltage and reduce the current increase after identifying the impact condition; the third stage is voltage limiting. The main purpose is to further limit the current increase after recognizing that the current has deviated from the normal operating range, thereby reducing the risk of equipment damage due to high current; the fourth stage is voltage limiting. The main function is to detect a drop in power supply voltage, reduce the magnitude of the voltage drop, and prevent the device from restarting.

[0055] Using the above settings, the four voltage limiting segments can operate independently and autonomously to adapt to various emergency conditions, limiting the maximum current by limiting the maximum voltage. Examples include: 1) a collision occurring before reaching the end of a turn due to external factors during a rapid turn; 2) a large increase in current but a small drop in voltage; and 3) a voltage drop due to power consumption by other equipment, but a limited increase in current.

[0056] In one embodiment of this example, the current allowed motor terminal voltage is determined based on a preset motor terminal voltage determination rule. and The calculation formula is: .

[0057] The electric power steering systems used in different car models can vary significantly, and some parameters need to be adjusted according to the car model. Those skilled in the art can adjust them according to actual needs, which will not be elaborated here.

[0058] The following example illustrates this: For instance, in a stand-on forklift with an 80V power supply system, two 360W DC power supplies are connected in parallel to convert the voltage to 48V to power the electric power steering system. The controller collects the maximum steering wheel torque value. During normal steering, the collected steering wheel torque The steering wheel angle is -90° to 90°. The conversion ratio between the angle used for the first voltage limiting stage and the steering wheel angle is 10:1. , , , The brushless three-phase motor used in the power assist motor rotates counterclockwise and hits the mechanical limit for 10ms.

[0059] At this time, the steering wheel angle , Calculations yielded , here settings = 0.15, based on the first voltage limiting segment The calculation formula yields: .

[0060] The motor speed before impact mechanical limit is Steering wheel torque 10ms after impact, the motor speed The calculation shows that the vehicle collided with the mechanical limit switch during normal steering. ,test Calculations yielded , here settings .

[0061] To reduce the instability caused by fluctuations in motor speed and steering wheel torque, resulting in second-stage motor limiting... To mitigate fluctuations, filtering is needed to assess the changes in motor speed and steering wheel torque. Data sets mspd

[10] and trq

[10] of length 10 are defined, storing motor speed and steering wheel torque every 100µs. The average value of the changes in motor speed and steering wheel torque is calculated, assuming a linear change. The change is based on a 1ms time interval. , According to the second voltage limiting The calculation formula yields: .

[0062] The bus current before impact mechanical limit is 10ms after impact, bus current ,test , , , , here settings .

[0063] To reduce the voltage limiting in the third stage caused by unstable bus current fluctuations. Fluctuations require filtering of the bus current variation amplitude. A data mcut

[10] with a length of 10 is defined, and the bus current value is stored every 100us. The average value of the bus current variation is calculated. Here, the calculation is based on the linear change of the bus current, and the variation amplitude is based on a time of 1ms. According to the third voltage limiting The calculation formula yields: .

[0064] Electric power steering system power supply voltage before impact mechanical limit Five milliseconds after the impact, the power supply voltage of the electric power steering system began to drop; ten milliseconds after the impact, the power supply voltage of the electric power steering system... The test results , , , , here settings To reduce the voltage limiting in the fourth stage caused by unstable power supply voltage fluctuations in the electric power steering system. Fluctuations require filtering of the change amplitude of the power supply voltage of the electric power steering system. A data pvolt

[10] with a length of 10 is defined, and the power supply voltage of the electric power steering system is stored once every 100us. The average change of the power supply voltage of the electric power steering system is calculated. Here, the power supply voltage of the electric power steering system is calculated as a linear change within 5ms to 10ms after the impact, and the change amplitude is based on 1ms. According to the fourth voltage limiting The calculation formula yields: .

[0065] Because this vehicle model experiences a large instantaneous high current during a collision, and there is a risk of voltage drop, therefore it is designed with... , , , Calculations were made 10 ms after the impact. , , , According to the target voltage limit The weighted summation formula can be obtained as follows: .

[0066] set up , Calculations were made 10 ms after the impact. According to the current allowable motor terminal pressure and The calculation formula can be obtained as follows:

[0067] Finally, and After inverse Park transform and inverse Clarke transform, the PWM waveform output to the motor can be obtained.

[0068] Example 2 Figure 3 This is a schematic diagram of the instantaneous high current suppression system under mechanical impact conditions in the electric power steering system according to Embodiment 2 of the present invention. (See also...) Figure 3 This system includes: Module 201 is used to obtain the current steering wheel angle of the vehicle. Steering wheel torque Assist motor speed Bus current from vehicle power supply to electric power steering system The power supply voltage from the vehicle's power source to the electric power steering system .

[0069] The first calculation module 202 is used to calculate based on the steering wheel angle. and the steering wheel torque The first voltage limiting segment is calculated based on preset angle and torque determination rules. .

[0070] The second calculation module 203 is used to calculate based on the speed of the assist motor. and the steering wheel torque The second voltage limit is calculated based on the preset motor speed determination rules. .

[0071] The third calculation module 204 is used to calculate the bus current from the vehicle power supply to the electric power steering system. The third voltage limit is calculated based on the preset bus current determination rule. .

[0072] The fourth calculation module 205 is used to calculate the power supply voltage from the vehicle power source to the electric power steering system. The fourth voltage limit is calculated based on the preset power supply voltage determination rules. .

[0073] The weighted summation module 206 is used to obtain the first voltage limiting segment. The second stage voltage limiting The third voltage limiting The fourth voltage limiting segment For the first segment voltage limiting The second stage voltage limiting The third voltage limiting The fourth voltage limiting segment The target voltage limit is obtained by assigning weight coefficients to each component and then performing a weighted summation. Wherein, the sum of all the weight coefficients is less than or equal to 1.

[0074] Terminal voltage calculation module 207 is used to obtain the rated maximum terminal voltage of the power steering motor of the electric power steering system. and And based on the target voltage limit The current allowable motor terminal voltage is calculated based on the preset motor terminal voltage determination rules. and Using the currently allowed motor terminal pressure and Implement terminal voltage limiting to suppress instantaneous peak current.

[0075] Transformation module 208 is used to obtain the current allowed motor terminal voltage. and After undergoing inverse Park transform and inverse Clarke transform to obtain the PWM waveform, it is output to the motor. The PWM waveform is used to control the motor terminal voltage. Limitations are used to suppress instantaneous peak current.

[0076] The instantaneous high current suppression system for electric power steering systems under mechanical impact conditions provided in this embodiment of the invention can execute the instantaneous high current suppression method for electric power steering systems under mechanical impact conditions provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0077] Example 3 Figure 4 This is a schematic diagram of the structure of a terminal according to Embodiment 3 of the present invention; Figure 4 A block diagram of an exemplary terminal system suitable for implementing embodiments of the present invention is shown. Figure 4 The terminal system shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of the present invention.

[0078] like Figure 4 As shown, terminal 12 is presented in the form of a general-purpose computing device. The components of terminal 12 may include, but are not limited to: one or more processors or processing units 16, memory 28, and a bus 18 connecting different system components (including memory 28 and processing unit 16).

[0079] Bus 18 represents one or more of several bus architectures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any of the various bus architectures. For example, these architectures include, but are not limited to, the Industry Standard Architecture (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnect (PCI) bus.

[0080] Terminal 12 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by terminal 12, including volatile and non-volatile media, removable and non-removable media.

[0081] Memory 28 may include computer system readable media in the form of volatile memory, such as RAM 30 and / or cache 32. Terminal 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 34 may be used to read and write non-removable, non-volatile magnetic media (… Figure 4 Not shown; usually referred to as a "hard drive"). Although Figure 4 As not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) may be provided. In these cases, each drive may be connected to bus 18 via one or more data media interfaces. Memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of the present invention.

[0082] A program / utility 40 having a set (at least one) of program modules 42 may be stored, for example, in memory 28. Such program modules 42 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. Program modules 42 typically perform the functions and / or methods described in the embodiments of the present invention.

[0083] Terminal 12 can also communicate with one or more external devices 14 (e.g., keyboard, pointing device, display 24, etc.), and with one or more devices that enable a user to interact with terminal 12, and / or with any device that enables terminal 12 to communicate with one or more other computing devices (e.g., network card, modem, etc.). This communication can be performed via I / O interface 22. Furthermore, terminal 12 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via network adapter 20. As shown, network adapter 20 communicates with other modules of terminal 12 via bus 18. It should be understood that, although not shown in the figures, other hardware and / or software modules can be used in conjunction with terminal 12, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0084] The processing unit 16 executes various functional applications and data processing by running programs stored in memory 28, such as implementing the instantaneous high current suppression method for electric power steering system under mechanical impact conditions provided in the embodiments of the present invention.

[0085] Example 4 Embodiment 4 of the present invention also provides a storage medium containing computer-executable instructions, which, when executed by a computer processor, are used to perform the instantaneous high current suppression method for an electric power steering system under mechanical impact conditions as described in any of the above embodiments.

[0086] The computer storage medium of this invention can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0087] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0088] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including—but not limited to—wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0089] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0090] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions, characterized in that, include: Get the current steering wheel angle of the vehicle Steering wheel torque Assist motor speed Bus current from vehicle power supply to electric power steering system The power supply voltage from the vehicle's power source to the electric power steering system ; According to the steering wheel angle and the steering wheel torque The first voltage limiting segment is calculated based on preset angle and torque determination rules. ; According to the speed of the power assist motor and the steering wheel torque The second voltage limit is calculated based on the preset motor speed determination rules. ; According to the bus current from the vehicle power supply to the electric power steering system The third voltage limit is calculated based on the preset bus current determination rule. ; According to the power supply voltage from the vehicle power source to the electric power steering system The fourth voltage limit is calculated based on the preset power supply voltage determination rules. ; Obtain the first segment voltage limit The second stage voltage limiting The third voltage limiting The fourth voltage limiting segment For the first segment voltage limiting The second stage voltage limiting The third voltage limiting The fourth voltage limiting segment The target voltage limit is obtained by assigning weight coefficients to each component and then performing a weighted summation. Wherein, the sum of all the weighting coefficients is less than or equal to 1; Obtain the rated maximum terminal voltage of the power steering motor of the electric power steering system. and And based on the target voltage limit The current allowable motor terminal voltage is calculated based on the preset motor terminal voltage determination rules. and Using the currently allowed motor terminal pressure and Implement terminal voltage limiting to suppress instantaneous peak current.

2. The method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 1, characterized in that, The rated maximum terminal voltage of the power steering motor of the electric power steering system is obtained. and And based on the target voltage limit The current allowable motor terminal voltage is calculated based on the preset motor terminal voltage determination rules. and Using the currently allowed motor terminal pressure and After implementing terminal voltage limiting to suppress instantaneous peak current, the method further includes: Obtain the current allowed motor terminal pressure and After undergoing inverse Park transform and inverse Clarke transform to obtain the PWM waveform, it is output to the motor. The PWM waveform is used to control the motor terminal voltage. Limitations are used to suppress instantaneous peak current.

3. A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 1 or 2, characterized in that, The first voltage limiting segment based on the preset angle and torque determination rules The calculation formula is as follows: ； in, The activation angle for counter-clockwise impact protection is... The angle at which counter-clockwise impact protection reaches its maximum; The activation angle for impact protection is clockwise. The angle at which clockwise impact protection reaches its maximum; secondly, To protect the starting torque in case of impact, The maximum steering wheel torque value collected; again, The calculation coefficient for the first voltage limiting segment should satisfy the following range: .

4. The method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 3, characterized in that: The , The corresponding steering wheel angles all differ from the maximum steering wheel angle by 0°-2°. and The corresponding steering wheel angles differ by 10°-20°. and The corresponding steering wheel angles differ by 10°-20°, and and The angle difference is equal to and The angles differ.

5. A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 1 or 2, characterized in that, The second voltage limit based on the preset motor speed determination rule The calculation formula is as follows: ； in, Motor speed versus time Perform differentiation, Steering wheel torque versus time Perform differentiation, Thresholds for identifying impact conditions; In the above formula, The calculation coefficient for the second voltage limiting stage is given by the following formula: ； in, To prevent the electric power steering system from rapidly impacting the mechanical limit switch when unloaded, The calculated maximum value.

6. A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 1 or 2, characterized in that, The third voltage limiting based on the preset bus current determination rule The calculation formula is as follows: ； in, Bus current versus time Perform differentiation, The threshold value for starting the bus current impact protection; In the above formula, The calculation coefficient for the third voltage limiting stage is given by the following formula: ; in, To prevent the electric power steering system from rapidly impacting the mechanical limit switch when unloaded, The calculated maximum value, This is the maximum bus current collected at this time.

7. A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 1 or 2, characterized in that, The fourth voltage limiting based on the preset power supply voltage determination rule The calculation formula is as follows: ； in, The voltage supplied to the electric power steering system in relation to time Perform differentiation, The threshold voltage for impact protection activation; In the above formula, The calculation coefficient for the third voltage limiting stage is given by the following formula: ; in, When the vehicle's power is directly turned off, The calculated maximum value, The minimum operating voltage required to provide assistance to an electric power steering system.

8. A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 1 or 2, characterized in that, The method further includes: When the calculated second voltage limit When the voltage is greater than 100, the second voltage limit is applied. Take 100; When the calculated third voltage limit When the voltage is greater than 100, the third voltage limit is applied. Take 100; When the calculated fourth segment voltage limit When the voltage is greater than 100, the fourth voltage segment is limited. Take 100.

9. A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 1 or 2, characterized in that, The target voltage limit The formula for calculating the weighted sum is as follows: ； in, , , , They are respectively , , , The weighting coefficients for the four-segment voltage limiting , , , All four weighting coefficients are greater than 0, and ;like yes If the current is less than twice that of the electric power steering system and its power supply, and is within the normal operating current range of the electric power steering system and its power supply, then ,otherwise , This refers to the maximum bus current collected when the electric power steering system rapidly impacts the mechanical limit switch under no-load conditions. This is the bus current impact protection activation threshold; if, under no-load impact, the minimum supply voltage of the electric power steering system is greater than... ,but ,otherwise , The minimum operating voltage that provides assistance to the electric power steering system. The threshold voltage for impact protection activation.

10. A method for suppressing instantaneous high current in an electric power steering system under mechanical impact conditions according to claim 1 or 2, characterized in that: The current allowed motor terminal voltage based on the preset motor terminal voltage determination rule. and The calculation formula is: 。

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