Limp vehicle speed control method, device, equipment and storage medium

Abstract

The present invention relates to the field of vehicle control technology, and discloses a limp home speed control method, device, equipment and storage medium, the method comprising: obtaining a MAP curve between motor speed and back electromotive force; obtaining a limp home speed threshold, and determining a limp home speed range based on the limp home speed threshold; determining a back electromotive force range according to the MAP curve and the limp home speed range; obtaining a voltage range of a power battery of the whole vehicle, and determining a limp home speed voltage range according to the voltage range and the back electromotive force range; when the vehicle enters the limp home mode, controlling the limp home speed of the vehicle according to the limp home speed voltage range. The present invention determines the back electromotive force range according to the MAP curve and the speed range, thereby determining the limp home speed voltage range and controlling the limp home speed of the vehicle, thereby solving the problem that the limp home speed is too low and cannot be dynamically adjusted, thereby increasing the limp home speed, realizing adaptive adjustment, and improving driving safety.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control technology, and in particular to a limp home vehicle speed control method, device, equipment and storage medium. Background Art

[0002] The electric drive system is one of the core systems of new energy vehicles. Due to the complexity of the working environment, electric drive failures often occur. After the failure occurs, it will be manifested as power loss and the whole vehicle will break down, which poses a serious threat to the driver's safety and the reputation of the manufacturer. Therefore, how to ensure that the whole vehicle can still maintain high-speed stable limp without secondary damage after the electric drive failure occurs is a key technical issue for new energy vehicles. For single-electric two-wheel drive vehicles, the failure of one motor means that the vehicle breaks down; for dual-electric four-wheel drive vehicles, after one motor fails, the other normal electric drive can support the vehicle to continue limp at a low speed. At present, after the whole vehicle enters the limp mode, the speed limit of the whole vehicle is 40km / h, and the maximum output torque of the normal motor in the limp mode is 120Nm. However, the limp speed of 40km / h is too low, and sudden deceleration on the road is easy to cause rear-end collisions and other accidents; the limp speed cannot be adjusted dynamically, and 40km / h is difficult to support the driver to move the vehicle to the maintenance site. Summary of the invention

[0003] The main purpose of the present invention is to provide a limp home vehicle speed control method, device, equipment and storage medium, aiming to solve the technical problem in the prior art that the limp home vehicle speed is too low and cannot be dynamically adjusted.

[0004] To achieve the above object, the present invention provides a limp home vehicle speed control method, the method comprising the following steps:

[0005] Get the MAP curve between motor speed and back EMF;

[0006] acquiring a limp speed threshold, and determining a limp speed range based on the limp speed threshold;

[0007] determining a back electromotive force range according to the MAP curve and the limp home speed range;

[0008] Obtaining a voltage range of a power battery of the entire vehicle, and determining a limp home speed voltage range according to the voltage range and the back electromotive force range;

[0009] When the vehicle enters the limp home mode, the limp home speed of the vehicle is controlled according to the limp home speed voltage range.

[0010] Optionally, obtaining a MAP curve between the motor speed and the back electromotive force includes:

[0011] The induced back electromotive force of the motor at different speeds is simulated and bench tested to obtain the test results;

[0012] Determine the proportional relationship between the motor speed and the back electromotive force based on the test results;

[0013] A MAP curve between the motor speed and the back electromotive force is determined according to the proportional relationship between the motor speed and the back electromotive force.

[0014] Optionally, the limp speed threshold comprises a first limp speed threshold and a second limp speed threshold, and acquiring the limp speed threshold and determining the limp speed range based on the limp speed threshold comprises:

[0015] Determine a first limp speed threshold by bench testing, wherein the first limp speed threshold is a speed that will not cause damage to the motor controller;

[0016] obtaining a predefined second limp speed threshold;

[0017] A limp speed range is determined according to the first limp speed threshold and the second limp speed threshold, wherein the first limp speed threshold is greater than the second limp speed threshold.

[0018] Optionally, determining the back electromotive force range according to the MAP curve and the limp home speed range includes:

[0019] querying the MAP curve according to the first limp speed threshold and the second limp speed threshold to obtain corresponding first back electromotive force threshold and second back electromotive force threshold;

[0020] A back electromotive force range is determined according to the first back electromotive force threshold and the second back electromotive force threshold, wherein the first back electromotive force threshold is greater than the second back electromotive force threshold.

[0021] Optionally, the acquiring a voltage range of a power battery of the entire vehicle, and determining a limp home speed voltage range according to the voltage range and the back electromotive force range, includes:

[0022] Acquire a first battery voltage threshold and a second battery voltage threshold, wherein the first battery voltage threshold is greater than the second battery voltage threshold;

[0023] Determining a voltage range of a power battery of the vehicle according to the first battery voltage threshold and the second battery voltage threshold;

[0024] determining a first limp home speed threshold and a second limp home speed threshold according to the voltage range and the back electromotive force range, wherein the first limp home speed threshold is greater than the second limp home speed threshold;

[0025] A limp home speed voltage range is determined according to the first limp home speed threshold and the second limp home speed threshold.

[0026] Optionally, when the vehicle enters the limp home mode, controlling the limp home speed of the vehicle according to the limp home speed voltage range includes:

[0027] When a motor failure is detected, the vehicle is controlled to enter limp home mode;

[0028] Reading a current power battery voltage, and determining a current limp home back electromotive force according to the current power battery voltage and the limp home speed voltage range;

[0029] The MAP curve is queried according to the current limp home back electromotive force to obtain the limp home speed of the vehicle.

[0030] Optionally, the reading the current power battery voltage and determining the current limp home back electromotive force according to the current power battery voltage and the limp home speed voltage range includes:

[0031] comparing the current power battery voltage with a voltage corresponding to a first limp home speed threshold in the limp home speed voltage range;

[0032] If the current power battery voltage is greater than or equal to the voltage corresponding to the first limp home speed threshold, the voltage corresponding to the first limp home speed threshold is used as the current limp home back electromotive force;

[0033] If the current power battery voltage is less than the voltage corresponding to the first limp home speed threshold, determining whether the current power battery voltage is greater than or equal to the voltage corresponding to the second limp home speed threshold in the limp home speed voltage range and less than the voltage corresponding to the first limp home speed threshold;

[0034] If it is satisfied, the current power battery voltage is used as the current limp home back electromotive force.

[0035] In addition, to achieve the above-mentioned purpose, the present invention further provides a limp home vehicle speed control device, the limp home vehicle speed control device comprising:

[0036] An acquisition module is used to obtain a MAP curve between motor speed and back electromotive force;

[0037] a determination module, configured to obtain a limp speed threshold, and determine a limp speed range based on the limp speed threshold;

[0038] The determination module is further used to determine a back electromotive force range according to the MAP curve and the limp home speed range;

[0039] The determination module is further used to obtain a voltage range of the vehicle power battery, and determine a limp home speed voltage range according to the voltage range and the back electromotive force range;

[0040] The control module is used for controlling the limp home speed of the vehicle according to the limp home speed voltage range when the vehicle enters the limp home mode.

[0041] In addition, to achieve the above-mentioned purpose, the present invention also proposes a limp home speed control device, which includes: a memory, a processor, and a limp home speed control program stored in the memory and executable on the processor, and the limp home speed control program is configured to implement the steps of the limp home speed control method described above.

[0042] In addition, to achieve the above-mentioned purpose, the present invention further proposes a storage medium, on which a limp home speed control program is stored, and when the limp home speed control program is executed by a processor, the steps of the limp home speed control method as described above are implemented.

[0043] The present invention obtains the MAP curve between the motor speed and the back electromotive force; obtains the limp speed threshold, and determines the limp speed range based on the limp speed threshold; determines the back electromotive force range according to the MAP curve and the limp speed range; obtains the voltage range of the vehicle power battery, and determines the limp speed voltage range according to the voltage range and the back electromotive force range; when the vehicle enters the limp mode, controls the limp speed of the vehicle according to the limp speed voltage range. In the above manner, by determining the back electromotive force range according to the MAP curve and the speed range, the limp speed voltage range is determined and the limp speed of the vehicle is controlled, which solves the problem that the limp speed is too low and cannot be dynamically adjusted, increases the limp speed, realizes adaptive adjustment, and improves driving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of a limp home vehicle speed control device in a hardware operating environment involved in an embodiment of the present invention;

[0045] Figure 2 It is a flowchart of a first embodiment of a limp home vehicle speed control method of the present invention;

[0046] Figure 3 A schematic diagram of a MAP curve of an embodiment of a limp home vehicle speed control method of the present invention;

[0047] Figure 4 A schematic diagram of a limp home speed voltage range according to an embodiment of a limp home speed control method of the present invention;

[0048] Figure 5 It is a flow chart of a second embodiment of a limp home vehicle speed control method of the present invention;

[0049] Figure 6 A flow chart of faulty motor analysis according to an embodiment of a limp home vehicle speed control method of the present invention;

[0050] Figure 7 A normal motor analysis flow chart of an embodiment of a limp home vehicle speed control method of the present invention;

[0051] Figure 8 A current limp home vehicle speed control method adaptive control flow chart of a method according to an embodiment of the present invention;

[0052] Fig. 9 It is a structural block diagram of the first embodiment of the limp home vehicle speed control device of the present invention.

[0053] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0054] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0055] Reference Figure 1 , Figure 1 It is a schematic diagram of the structure of a limp home vehicle speed control device in a hardware operating environment involved in an embodiment of the present invention.

[0056] like Figure 1 As shown, the limp home speed control device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a wireless fidelity (Wireless-Fidelity, Wi-Fi) interface). The memory 1005 may be a high-speed random access memory (Random Access Memory, RAM), or a stable non-volatile memory (Non-Volatile Memory, NVM), such as a disk storage. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0057] Those skilled in the art will understand that Figure 1 The structure shown in the figure does not constitute a limitation on the limp home speed control device, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0058] like Figure 1As shown, the memory 1005 as a storage medium may include an operating system, a network communication module, a user interface module, and a limp home speed control program.

[0059] exist Figure 1 In the limp home speed control device shown, the network interface 1004 is mainly used for data communication with a network server; the user interface 1003 is mainly used for data interaction with a user; the processor 1001 and the memory 1005 in the limp home speed control device of the present invention can be arranged in the limp home speed control device, and the limp home speed control device calls the limp home speed control program stored in the memory 1005 through the processor 1001, and executes the limp home speed control method provided in an embodiment of the present invention.

[0060] The embodiment of the present invention provides a limp home vehicle speed control method, referring to Figure 2 , Figure 2 FIG. 4 is a flow chart of a first embodiment of a limp home vehicle speed control method according to the present invention.

[0061] In this embodiment, the limp home vehicle speed control method comprises the following steps:

[0062] Step S10: Obtaining a MAP curve between the motor speed and the back electromotive force.

[0063] It should be noted that the execution subject in this embodiment is the limp home speed control device, and may also be other devices with the same or similar functions. This embodiment does not impose any specific limitation on this. This embodiment is described by taking the limp home speed control device as an example.

[0064] It can be understood that the MAP curve refers to the motor characteristic curve (Motor Characteristic Curve), which describes the relationship between the motor speed and the back electromotive force.

[0065] Furthermore, obtaining the MAP curve between the motor speed and the back electromotive force includes: simulating and bench testing the induced back electromotive force at different motor speeds to obtain test results; determining the proportional relationship between the motor speed and the back electromotive force based on the test results; and determining the MAP curve between the motor speed and the back electromotive force based on the proportional relationship between the motor speed and the back electromotive force.

[0066] It should be noted that by simulating and testing the induced back EMF at different motor speeds, it can be found that the DC bus induced back EMF is roughly proportional to the speed, so that the MAP curve between the motor speed and back EMF can be drawn, such as Figure 3 As shown, Figure 3 It is a schematic diagram of the MAP curve. The horizontal axis of the MAP curve is the motor speed, and the vertical axis is the induced back electromotive force.

[0067] Step S20: acquiring a limp home speed threshold, and determining a limp home speed range based on the limp home speed threshold.

[0068] It should be noted that the limp speed threshold includes a first limp speed threshold and a second limp speed threshold, namely the maximum limp speed Rmotor-max and the minimum limp speed Rmotor-min, wherein the first limp speed threshold is the maximum limp speed Rmotor-max, and the second limp speed threshold is the minimum limp speed Rmotor-min.

[0069] It can be understood that the limp home speed range can be determined as [Rmotor-min, Rmotor-max] according to the maximum limp home speed Rmotor-max and the minimum limp home speed Rmotor-min.

[0070] Further, the limp speed threshold includes a first limp speed threshold and a second limp speed threshold, and obtaining the limp speed threshold and determining the limp speed range based on the limp speed threshold includes: determining the first limp speed threshold through a bench test, wherein the first limp speed threshold is a speed that will not cause damage to the motor controller; obtaining a predefined second limp speed threshold; determining the limp speed range based on the first limp speed threshold and the second limp speed threshold, wherein the first limp speed threshold is greater than the second limp speed threshold.

[0071] It should be noted that the factors that affect the maximum limp homeostasis capability of the motor are that the motor can safely enter the ASC mode when the speed is above the maximum limp homeostasis speed, and can safely switch from the ASC mode to the FW mode when the speed is close to the limp homeostasis speed.

[0072] It is understandable that at high vehicle speeds, when the motor switches directly from the normal open-tube state to the ASC state during operation, a large impact phase current Iu, Iv, and Iw will be generated. This impact current will impact and damage the power devices, thereby damaging the MCU (motor controller). At high vehicle speeds, when the motor switches from the normal open-tube state to the FW state, an instantaneous spike voltage will be generated. This impact voltage will also impact and damage the power devices, thereby damaging the MCU (motor controller). Therefore, it is necessary to conduct a preliminary test on the bench in advance to determine the maximum limp speed that will not cause damage to the MCU (motor controller), which will be used as the first limp speed threshold, that is, the maximum limp speed Rmotor-max.

[0073] It is worth noting that the second limp home speed threshold, namely the minimum limp home speed Rmotor-min, is determined based on the minimum limp home speed defined for the entire vehicle.

[0074] Step S30: determining a back electromotive force range according to the MAP curve and the limp home speed range.

[0075] It should be noted that the back electromotive force is the electromotive force generated inside the motor and is proportional to the speed of the motor.

[0076] Further, determining the back electromotive force range according to the MAP curve and the limp speed range includes: querying the MAP curve according to the first limp speed threshold and the second limp speed threshold to obtain the corresponding first back electromotive force threshold and second back electromotive force threshold; determining the back electromotive force range according to the first back electromotive force threshold and the second back electromotive force threshold, wherein the first back electromotive force threshold is greater than the second back electromotive force threshold.

[0077] It should be noted that the back EMFs corresponding to the highest limp speed Rmotor-max and the lowest limp speed Rmotor-min on the MAP curve are obtained to obtain a first back EMF threshold and a second back EMF threshold, wherein the first back EMF threshold is the back EMF corresponding to the highest limp speed Rmotor-max, that is, the highest limp speed back EMF Vmotor-max, and the second back EMF threshold is the back EMF corresponding to the lowest limp speed Rmotor-min, that is, the lowest limp speed back EMF Vmotor-min.

[0078] It can be understood that the back electromotive force range [Vmotor-min, Vmotor-max] can be determined according to the maximum limp home speed back electromotive force Vmotor-max and the minimum limp home speed back electromotive force Vmotor-min.

[0079] Step S40: obtaining a voltage range of the vehicle power battery, and determining a limp home speed voltage range according to the voltage range and the back electromotive force range.

[0080] It should be noted that the voltage range of the vehicle power battery is determined, that is, the minimum battery voltage Vbms-min and the maximum battery voltage Vbms-max. The voltage range of the limp home speed can be determined by matching the power battery and the electric drive parameters.

[0081] Furthermore, the method of obtaining the voltage range of the power battery of the whole vehicle and determining the limp home speed voltage range according to the voltage range and the back electromotive force range includes: obtaining a first battery voltage threshold and a second battery voltage threshold, wherein the first battery voltage threshold is greater than the second battery voltage threshold; determining the voltage range of the power battery of the whole vehicle according to the first battery voltage threshold and the second battery voltage threshold; determining a first limp home speed threshold and a second limp home speed threshold according to the voltage range and the back electromotive force range, wherein the first limp home speed threshold is greater than the second limp home speed threshold; determining the limp home speed voltage range according to the first limp home speed threshold and the second limp home speed threshold.

[0082] It should be noted that the first battery voltage threshold is the maximum battery voltage Vbms-max, and the second battery voltage threshold is the minimum battery voltage Vbms-min. The voltage range [Vbms-min, Vbms-max] of the vehicle power battery can be determined based on the minimum battery voltage Vbms-min and the maximum battery voltage Vbms-max.

[0083] It can be understood that the lowest limp speed back electromotive force Vmotor-min is taken from the lowest battery voltage Vbms-min and the lowest limp speed back electromotive force Vmotor-min, and the lowest limp speed back electromotive force is set to the second limp speed threshold, that is, the voltage Vmin corresponding to the lowest limp speed, and it is necessary to ensure that Vmotor-min<Vbms-min. The highest battery voltage Vbms-max and the highest limp speed back electromotive force Vmotor-max take the smaller value and set it to the first limp speed threshold, that is, Vmax corresponding to the highest limp speed. The limp speed voltage range [Vmin, Vmax] can be determined based on the voltage Vmin corresponding to the lowest limp speed and the voltage Vmax corresponding to the highest limp speed.

[0084] like Figure 4 As shown, Figure 4 This is a schematic diagram of the limp home speed voltage range. The limp home speed voltage range [Vmin, Vmax] can be determined based on the limp home speed back electromotive force range [Vmotor-min, Vmotor-max] and the power battery voltage range [Vbms-min, Vbms-max].

[0085] Step S50: When the vehicle enters the limp home mode, controlling the limp home speed of the vehicle according to the limp home speed voltage range.

[0086] It should be noted that after a single electric drive fails, the entire vehicle will determine that it needs to enter limp home mode and control the vehicle's limp home speed.

[0087] This embodiment obtains the MAP curve between the motor speed and the back electromotive force; obtains the limp speed threshold, and determines the limp speed range based on the limp speed threshold; determines the back electromotive force range according to the MAP curve and the limp speed range; obtains the voltage range of the vehicle power battery, and determines the limp speed voltage range according to the voltage range and the back electromotive force range; when the vehicle enters the limp mode, controls the limp speed of the vehicle according to the limp speed voltage range. In the above manner, by determining the back electromotive force range according to the MAP curve and the speed range, the limp speed voltage range is determined and the limp speed of the vehicle is controlled, which solves the problem that the limp speed is too low and cannot be dynamically adjusted, increases the limp speed, realizes adaptive adjustment, and improves driving safety.

[0088] refer to Figure 5 , Figure 5 FIG. 4 is a flow chart of a second embodiment of a limp home vehicle speed control method according to the present invention.

[0089] Based on the first embodiment, step S50 in the limp home vehicle speed control method of this embodiment includes:

[0090] Step S501: When a motor failure is detected, the vehicle is controlled to enter a limp home mode.

[0091] It should be noted that after a single electric drive fails, the entire vehicle needs to enter limp home mode. Analyze the faulty motor and find that the motor needs to be in FW state in the limp home state to avoid rapid temperature rise. The power battery voltage needs to be continuously greater than the motor back electromotive force to avoid uncontrollable passive rectification.

[0092] like Figure 6 As shown, Figure 6 This is the faulty motor analysis flow chart. After the limp vehicle speed increases, the speed of the faulty motor increases. If the electric drive runs stably inside and there is no abnormal heating of the electric drive, the motor is in the FW state. If the electric drive runs stably outside and there is no uncontrollable energy exchange between the electric drive and the outside, the power battery voltage is greater than the back electromotive force.

[0093] It is understandable that, when analyzing a normal motor, in a normal electric drive limp state, the motor needs to be in torque mode and respond normally to the VCU (vehicle control unit) torque. The electric drive exchanges energy for driving and feedback with the power battery according to the requirements of the VCU (vehicle control unit).

[0094] like Figure 7 As shown, Figure 7 This is a normal motor analysis flow chart. After the limp vehicle speed increases, the normal motor speed increases. If the electric drive operates stably inside, the electric drive outputs the required torque and the motor is in torque mode. If the electric drive operates stably outside, there is controllable energy exchange between the electric drive and the outside, and the exchange is actively performed according to the requirements of the VCU (vehicle control unit).

[0095] Step S502: reading the current power battery voltage, and determining the current limp home back electromotive force according to the current power battery voltage and the limp home vehicle speed voltage range.

[0096] It should be noted that after the vehicle enters the limp home mode, the current power battery voltage Vbms is read, and the power battery voltage Vbms is compared with the voltage Vmin corresponding to the lowest limp home speed in the limp home speed voltage range and the voltage Vmax corresponding to the highest limp home speed to obtain the current limp home back electromotive force voltage V-limp.

[0097] Further, the reading of the current power battery voltage and the determination of the current limp homeopathic back electromotive force based on the current power battery voltage and the limp homeopathic speed voltage range include: comparing the current power battery voltage with the voltage corresponding to a first limp homeopathic speed threshold in the limp homeopathic speed voltage range; if the current power battery voltage is greater than or equal to the voltage corresponding to the first limp homeopathic speed threshold, using the voltage corresponding to the first limp homeopathic speed threshold as the current limp homeopathic back electromotive force; if the current power battery voltage is less than the voltage corresponding to the first limp homeopathic speed threshold, determining whether the current power battery voltage is greater than or equal to the voltage corresponding to the second limp homeopathic speed threshold in the limp homeopathic speed voltage range and less than the voltage corresponding to the first limp homeopathic speed threshold; if so, using the current power battery voltage as the current limp homeopathic back electromotive force.

[0098] It should be noted that it is necessary to judge whether Vbms≥Vmax. If so, V-limp=Vmax. If not, it is necessary to judge whether Vmin≤Vbms<Vmax. If so, V-limp=Vbms. If Vbms<Vmin, it indicates that Vbms is abnormal and the vehicle cannot continue to limp.

[0099] like Figure 8 As shown, Figure 8 This is the current limp back-electromotive force adaptive control flow chart. After the vehicle enters the limp mode, the current power battery voltage Vbms is read to determine whether Vbms≥Vmax is satisfied. If so, V-limp=Vmax. If not, determine whether Vmin≤Vbms<Vmax is satisfied. If so, V-limp=Vbms. If not, it indicates that Vbms<Vmin and limp mode is prohibited.

[0100] Step S503: query the MAP curve according to the current limp home back electromotive force to obtain the limp home speed of the vehicle.

[0101] It should be noted that the speed corresponding to the current limp back EMF in the MAP curve is the current limp speed R-limp. Since the current limp speed R-limp is proportional to the limp speed S-limp, the limp speed S-limp can be obtained synchronously.

[0102] It is understandable that the power battery voltage Vbms is not fixed, but changes in real time as the vehicle travels. Through calculation, the limp home speed S-limp also changes in real time, thereby achieving adaptive adjustment of the limp home speed according to the vehicle status.

[0103] This embodiment controls the vehicle to enter the limp home mode when a motor failure is detected; reads the current power battery voltage, determines the current limp home back electromotive force according to the current power battery voltage and the limp home speed voltage range; queries the MAP curve according to the current limp home back electromotive force to obtain the vehicle limp home speed. In the above manner, the current limp home back electromotive force is determined by the current power battery voltage, thereby obtaining the vehicle limp home speed for vehicle control, thereby achieving adaptive adjustment of the limp home speed with the vehicle state, and improving vehicle driving safety.

[0104] Reference Fig. 9 , Fig. 9 It is a structural block diagram of the first embodiment of the limp home vehicle speed control device of the present invention.

[0105] like Fig. 9 As shown, the limp home vehicle speed control device provided in the embodiment of the present invention comprises:

[0106] The acquisition module 10 is used to acquire a MAP curve between the motor speed and the back electromotive force.

[0107] The determination module 20 is configured to obtain a limp home speed threshold and determine a limp home speed range based on the limp home speed threshold.

[0108] The determination module 20 is further configured to determine a back electromotive force range according to the MAP curve and the limp home speed range.

[0109] The determination module 20 is further configured to obtain a voltage range of a power battery of the entire vehicle, and determine a limp home speed voltage range according to the voltage range and the back electromotive force range.

[0110] The control module 30 is used to control the limp home speed of the vehicle according to the limp home speed voltage range when the vehicle enters the limp home mode.

[0111] This embodiment obtains the MAP curve between the motor speed and the back electromotive force; obtains the limp speed threshold, and determines the limp speed range based on the limp speed threshold; determines the back electromotive force range according to the MAP curve and the limp speed range; obtains the voltage range of the vehicle power battery, and determines the limp speed voltage range according to the voltage range and the back electromotive force range; when the vehicle enters the limp mode, controls the limp speed of the vehicle according to the limp speed voltage range. In the above manner, by determining the back electromotive force range according to the MAP curve and the speed range, the limp speed voltage range is determined and the limp speed of the vehicle is controlled, which solves the problem that the limp speed is too low and cannot be dynamically adjusted, increases the limp speed, realizes adaptive adjustment, and improves driving safety.

[0112] In one embodiment, the acquisition module 10 is also used to simulate and bench test the induced back electromotive force of the motor at different speeds to obtain test results; determine the proportional relationship between the motor speed and the back electromotive force based on the test results; and determine the MAP curve between the motor speed and the back electromotive force based on the proportional relationship between the motor speed and the back electromotive force.

[0113] In one embodiment, the limp speed threshold includes a first limp speed threshold and a second limp speed threshold, and the determination module 20 is further used to determine the first limp speed threshold through a bench test, wherein the first limp speed threshold is a speed that will not cause damage to the motor controller; obtain a predefined second limp speed threshold; determine a limp speed range based on the first limp speed threshold and the second limp speed threshold, wherein the first limp speed threshold is greater than the second limp speed threshold.

[0114] In one embodiment, the determination module 20 is further used to query the MAP curve according to the first limp speed threshold and the second limp speed threshold to obtain the corresponding first back electromotive force threshold and second back electromotive force threshold; determine the back electromotive force range according to the first back electromotive force threshold and the second back electromotive force threshold, wherein the first back electromotive force threshold is greater than the second back electromotive force threshold.

[0115] In one embodiment, the determination module 20 is also used to obtain a first battery voltage threshold and a second battery voltage threshold, wherein the first battery voltage threshold is greater than the second battery voltage threshold; determine the voltage range of the vehicle power battery according to the first battery voltage threshold and the second battery voltage threshold; determine a first limp speed threshold and a second limp speed threshold according to the voltage range and the back electromotive force range, wherein the first limp speed threshold is greater than the second limp speed threshold; determine the limp speed voltage range according to the first limp speed threshold and the second limp speed threshold.

[0116] In one embodiment, the control module 30 is also used to control the vehicle to enter a limp home mode when a motor failure is detected; read the current power battery voltage, and determine the current limp home back electromotive force based on the current power battery voltage and the limp home speed voltage range; query the MAP curve based on the current limp home back electromotive force to obtain the vehicle limp home speed.

[0117] In one embodiment, the current power battery voltage is compared with the voltage corresponding to the first limp speed threshold in the limp speed voltage range; if the current power battery voltage is greater than or equal to the voltage corresponding to the first limp speed threshold, the voltage corresponding to the first limp speed threshold is used as the current limp back electromotive force; if the current power battery voltage is less than the voltage corresponding to the first limp speed threshold, it is determined whether the current power battery voltage is greater than or equal to the voltage corresponding to the second limp speed threshold in the limp speed voltage range and less than the voltage corresponding to the first limp speed threshold; if so, the current power battery voltage is used as the current limp back electromotive force.

[0118] In addition, to achieve the above-mentioned purpose, the present invention also proposes a limp home speed control device, which includes: a memory, a processor, and a limp home speed control program stored in the memory and executable on the processor, and the limp home speed control program is configured to implement the steps of the limp home speed control method described above.

[0119] Since the limp home vehicle speed control device adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0120] In addition, an embodiment of the present invention further provides a storage medium, on which a limp home speed control program is stored. When the limp home speed control program is executed by a processor, the steps of the limp home speed control method described above are implemented.

[0121] Since the storage medium adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0122] It should be understood that the above is only an example and does not constitute any limitation on the technical solution of the present invention. In specific applications, technicians in this field can make settings as needed, and the present invention does not limit this.

[0123] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of the present invention. In practical applications, technicians in this field can select part or all of them according to actual needs to achieve the purpose of the present embodiment, and no limitation is made here.

[0124] In addition, for technical details not fully described in this embodiment, reference can be made to the limp home speed control method provided in any embodiment of the present invention, and will not be repeated here.

[0125] In addition, it should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0126] It should be understood that, although the various steps in the flowchart in the embodiment of the present application are displayed in sequence according to the indication of the arrows, these steps are not necessarily performed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and it can be performed in other orders. Moreover, at least a portion of the steps in the figure may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and their execution order is not necessarily performed in sequence, but can be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0127] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0128] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as a read-only memory (ROM) / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0129] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A limp home vehicle speed control method, characterized in that: The method comprises: Obtaining a MAP curve between the motor speed and the back electromotive force, wherein the MAP curve is used to characterize the relationship between the motor speed and the back electromotive force; acquiring a limp speed threshold, and determining a limp speed range based on the limp speed threshold; determining a back electromotive force range according to the MAP curve and the limp home speed range; Obtaining a voltage range of a power battery of the entire vehicle, and determining a limp home speed voltage range according to the voltage range and the back electromotive force range; When the vehicle enters the limp home mode, the limp home speed of the vehicle is controlled according to the limp home speed voltage range.

2. The method according to claim 1, characterized in that The step of obtaining a MAP curve between the motor speed and the back electromotive force includes: The induced back electromotive force of the motor at different speeds is simulated and bench tested to obtain the test results; Determine the proportional relationship between the motor speed and the back electromotive force based on the test results; A MAP curve between the motor speed and the back electromotive force is determined according to the proportional relationship between the motor speed and the back electromotive force.

3. The method according to claim 1, characterized in that The limp speed threshold comprises a first limp speed threshold and a second limp speed threshold, and obtaining the limp speed threshold and determining the limp speed range based on the limp speed threshold comprises: Determine a first limp speed threshold by bench testing, wherein the first limp speed threshold is a speed that will not cause damage to the motor controller; obtaining a predefined second limp speed threshold; A limp speed range is determined according to the first limp speed threshold and the second limp speed threshold, wherein the first limp speed threshold is greater than the second limp speed threshold.

4. The method according to claim 3, characterized in that The determining of the back electromotive force range according to the MAP curve and the limp home speed range includes: querying the MAP curve according to the first limp speed threshold and the second limp speed threshold to obtain corresponding first back electromotive force threshold and second back electromotive force threshold; A back electromotive force range is determined according to the first back electromotive force threshold and the second back electromotive force threshold, wherein the first back electromotive force threshold is greater than the second back electromotive force threshold.

5. The method according to claim 1, characterized in that The obtaining of the voltage range of the vehicle power battery and determining the limp home speed voltage range according to the voltage range and the back electromotive force range includes: Acquire a first battery voltage threshold and a second battery voltage threshold, wherein the first battery voltage threshold is greater than the second battery voltage threshold; Determining a voltage range of a power battery of the vehicle according to the first battery voltage threshold and the second battery voltage threshold; determining a first limp home speed threshold and a second limp home speed threshold according to the voltage range and the back electromotive force range, wherein the first limp home speed threshold is greater than the second limp home speed threshold; A limp home speed voltage range is determined according to the first limp home speed threshold and the second limp home speed threshold.

6. The method according to claim 1, characterized in that When the vehicle enters the limp home mode, controlling the limp home speed of the vehicle according to the limp home speed voltage range includes: When a motor failure is detected, the vehicle is controlled to enter limp home mode; Reading a current power battery voltage, and determining a current limp home back electromotive force according to the current power battery voltage and the limp home speed voltage range; The MAP curve is queried according to the current limp home back electromotive force to obtain the limp home speed of the vehicle.

7. The method according to claim 6, characterized in that The reading of the current power battery voltage and determining the current limp home back electromotive force according to the current power battery voltage and the limp home speed voltage range includes: comparing the current power battery voltage with a voltage corresponding to a first limp home speed threshold in the limp home speed voltage range; If the current power battery voltage is greater than or equal to the voltage corresponding to the first limp home speed threshold, the voltage corresponding to the first limp home speed threshold is used as the current limp home back electromotive force; If the current power battery voltage is less than the voltage corresponding to the first limp home speed threshold, determining whether the current power battery voltage is greater than or equal to the voltage corresponding to the second limp home speed threshold in the limp home speed voltage range and less than the voltage corresponding to the first limp home speed threshold; If it is satisfied, the current power battery voltage is used as the current limp home back electromotive force.

8. A limp home vehicle speed control device, characterized in that: The limp home vehicle speed control device comprises: An acquisition module, used to acquire a MAP curve between the motor speed and the back electromotive force, wherein the MAP curve is used to characterize the relationship between the motor speed and the back electromotive force; a determination module, configured to obtain a limp speed threshold, and determine a limp speed range based on the limp speed threshold; The determination module is further used to determine a back electromotive force range according to the MAP curve and the limp home speed range; The determination module is further used to obtain a voltage range of the vehicle power battery, and determine a limp home speed voltage range according to the voltage range and the back electromotive force range; The control module is used for controlling the limp home speed of the vehicle according to the limp home speed voltage range when the vehicle enters the limp home mode.

9. A limp home vehicle speed control device, characterized in that: The limp home speed control device comprises: a memory, a processor and a limp home speed control program stored in the memory and executable on the processor, wherein the limp home speed control program is configured to implement the limp home speed control method according to any one of claims 1 to 7.

10. A storage medium, characterized in that: The storage medium stores a limp home speed control program, which, when executed by a processor, implements the limp home speed control method according to any one of claims 1 to 7.

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