Control strategy and control system when electric drive system brake function fails

Abstract

The embodiment of the application provides a control strategy and a control system when a braking function of an electric drive system fails, and belongs to the technical field of electric vehicles. The control strategy comprises the following steps: obtaining a brake master cylinder stroke effectiveness signal of a vehicle; judging whether the brake master cylinder stroke effectiveness signal is effective; in the case that the brake master cylinder stroke effectiveness signal is judged to be effective, performing a drive torque limiting operation or a feedback torque limiting operation; in the case that the brake master cylinder stroke effectiveness signal is judged to be ineffective, performing a torque limiting operation; judging whether a brake fault occurs in the vehicle; and in the case that the vehicle is judged to have a brake fault, controlling the motor to enter an ASC mode or an FW mode. The control strategy and the control system can make the motor enter a safe state in time when the braking function of the vehicle fails, and ensure the safety of the vehicle driving.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and more specifically to a control strategy and control system for when the braking function of an electric drive system fails. Background Technology

[0002] With the continuous development of new energy vehicles, their safety has received increasing attention. The core requirements of the public for new energy vehicles are safety and stability, hoping that they can fundamentally protect the lives and property of drivers and passengers during operation. In this process, the braking system of new energy vehicles plays a crucial role. Specifically, the braking system is mainly used to maintain the slip ratio between the car wheels and the ground within the optimal range of 5% to 20% when braking is required due to a sudden event during normal driving, preventing the vehicle from swinging sideways due to excessive speed.

[0003] Ensuring vehicle safety in the event of brake failure is crucial. While the requirements for braking function are clearly defined, its implementation cannot be guaranteed. Therefore, a functional safety control system needs to be designed to ensure that the vehicle can stop safely in the event of brake failure, thus guaranteeing driving safety. Summary of the Invention

[0004] The purpose of this invention is to provide a control strategy and control system for when the braking function of an electric drive system fails. This control strategy and control system can enable the motor to enter a safe state in a timely manner when the vehicle's braking function fails, thereby ensuring the safety of vehicle driving.

[0005] To achieve the above objectives, embodiments of the present invention provide a control strategy for when the braking function of an electric drive system fails, including:

[0006] Obtain the validity signal of the vehicle's master cylinder stroke;

[0007] Determine whether the brake master cylinder stroke validity signal is valid;

[0008] If the brake master cylinder stroke validity signal is deemed valid, the operation of limiting drive torque or limiting regenerative torque is performed.

[0009] If the signal indicating the validity of the brake master cylinder stroke is invalid, a torque limiting operation is performed.

[0010] Determine whether the vehicle has a braking malfunction;

[0011] If a braking malfunction is detected in the vehicle, the control motor will enter either ASC mode or FW mode.

[0012] Optionally, limiting drive torque or limiting regenerative torque operations may be performed, including:

[0013] Obtain the master cylinder stroke of the vehicle;

[0014] Determine whether the stroke of the brake master cylinder is greater than a preset first distance threshold;

[0015] If it is determined that the stroke of the brake master cylinder is greater than the first distance threshold, the torque signal of the vehicle is acquired;

[0016] Determine the current vehicle's gear mode;

[0017] When the vehicle is in drive, determine whether the torque signal is greater than 0;

[0018] If the vehicle is in drive and the torque signal is greater than 0, the current torque is determined to be the drive torque.

[0019] If the current torque is the driving torque, perform a driving torque limiting operation;

[0020] After a preset first duration of performing the limited drive torque operation, it is determined whether the absolute value of the torque signal is greater than a preset first torque threshold.

[0021] If the absolute value of the torque signal is greater than the first torque threshold, it is determined that the vehicle has a torque abnormality.

[0022] Optionally, limiting drive torque or limiting regenerative torque operations may be performed, including:

[0023] When the vehicle is in reverse gear, determine whether the torque signal is less than 0;

[0024] If the vehicle is in reverse gear and the torque signal is less than 0, the current torque is determined to be the driving torque.

[0025] Optionally, limiting drive torque or limiting regenerative torque operations may be performed, including:

[0026] If the absolute value of the torque signal is less than or equal to the first torque threshold, it is determined that the vehicle has not experienced any torque abnormality.

[0027] Optionally, limiting drive torque or limiting regenerative torque operations may be performed, including:

[0028] If it is determined that the brake master cylinder stroke is less than or equal to the first distance threshold, it is determined whether the brake master cylinder stroke is less than a preset second distance threshold;

[0029] If it is determined that the stroke of the brake master cylinder is less than the second distance threshold, the torque signal of the vehicle is acquired;

[0030] Determine the current vehicle's gear mode;

[0031] Determine whether the vehicle is in a forward gear and whether the torque signal is less than 0;

[0032] If the vehicle is in forward gear and the torque signal is less than 0, the current torque is determined to be feedback torque.

[0033] If the current torque is the feedback torque, perform a torque limiting operation;

[0034] After a preset first duration of performing the limited feedback torque operation, it is determined whether the torque signal is less than a preset second torque threshold.

[0035] If the torque signal is determined to be less than the second torque threshold, it is determined that the vehicle has a torque abnormality.

[0036] Optionally, limiting drive torque or limiting regenerative torque operations may be performed, including:

[0037] If the torque signal is determined to be greater than or equal to the second torque threshold, it is determined that the vehicle does not have a torque abnormality.

[0038] Optionally, a torque limiting operation is performed, including:

[0039] Perform a torque limiting operation on the vehicle;

[0040] Obtain the torque signal of the vehicle;

[0041] After a preset first duration of performing the torque limiting operation on the vehicle, it is determined whether the absolute value of the torque signal is greater than a preset third torque threshold.

[0042] If the absolute value of the torque signal is greater than the third torque threshold, it is determined that the vehicle has a torque abnormality.

[0043] Optionally, a torque limiting operation is performed, including:

[0044] If the absolute value of the torque signal is less than or equal to the third torque threshold, it is determined that the vehicle does not have a torque abnormality.

[0045] Optionally, determining whether the vehicle has a braking malfunction includes:

[0046] In the event of abnormal torque in the vehicle, the first continuous sampling time at which the abnormal torque occurs is determined;

[0047] Determine whether the first continuous sampling time is greater than or equal to a preset first time threshold;

[0048] If the first continuous sampling time is greater than or equal to the first time threshold, it is determined that the vehicle has a braking failure.

[0049] On the other hand, the present invention also provides a control system for when the braking function of an electric drive system fails, the control system including a controller for executing the control strategy as described above.

[0050] Through the above technical solution, the control strategy and control system provided by the present invention for the failure of the braking function of the electric drive system obtains the validity signal of the brake master cylinder stroke of the vehicle, determines whether the validity signal of the brake master cylinder stroke validity signal is valid, and decides to perform the operation of limiting drive torque or limiting feedback torque or performing the operation of limiting torque. Based on the execution result, it is determined whether the vehicle has a braking failure. In the case of a braking failure, the motor is controlled to enter a safe state, that is, to enter ASC mode or FW mode, so as to enable the motor to enter a safe state in time when the braking function fails, thereby ensuring the safety of vehicle driving.

[0051] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0052] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0053] Figure 1 This is a flowchart of a control strategy and control system for an electric drive system when the braking function fails, according to an embodiment of the present invention.

[0054] Figure 2 This is a flowchart of a control strategy and control system for limiting drive torque or limiting feedback torque when the braking function of an electric drive system fails, according to an embodiment of the present invention.

[0055] Figure 3 This is a flowchart of the control strategy and the execution of torque limiting operation of the control system when the braking function of an electric drive system fails according to an embodiment of the present invention.

[0056] Figure 4 This is a flowchart illustrating the control strategy and control system for determining whether a vehicle has experienced a braking failure when the braking function of an electric drive system fails, according to an embodiment of the present invention.

[0057] Figure 5This is a detailed flowchart of the control strategy and control system for an electric drive system when the braking function fails, according to one embodiment of the present invention. Detailed Implementation

[0058] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0059] Figure 1 This is a flowchart of a control strategy and control system for an electric drive system when the braking function fails, according to an embodiment of the present invention. Figure 1 The specific steps of this control strategy may include:

[0060] In step S10, the validity signal of the vehicle's brake master cylinder stroke is obtained;

[0061] The brake master cylinder stroke validity signal is used to determine whether the vehicle is in a normal driving state. If an abnormal situation occurs, such as a collision, the acquired brake master cylinder stroke data will be invalid, and the brake master cylinder stroke validity signal will be invalid. The validity of the acquired brake master cylinder stroke data can be determined based on the brake master cylinder stroke validity signal.

[0062] In step S11, it is determined whether the brake master cylinder stroke validity signal is valid;

[0063] In step S12, if the brake master cylinder stroke validity signal is valid, the operation of limiting drive torque or limiting feedback torque is performed.

[0064] The conditions for determining whether the current torque is driving torque or regenerative torque are as follows: When the vehicle is in forward gear, if the torque signal is greater than 0, it is driving torque, and the vehicle is in forward electric mode; if the torque signal is less than 0, it is regenerative torque, and the vehicle is in forward generator mode, with the motor generating electricity. When the vehicle is in reverse gear, if the torque signal is less than 0, it is driving torque, and the vehicle is in reverse electric mode. Since the vehicle does not have a reverse generator mode, there is no condition for determining if the torque signal is greater than 0.

[0065] In step S13, if the brake master cylinder stroke validity signal is invalid, a torque limiting operation is performed;

[0066] In step S14, it is determined whether the vehicle has a braking malfunction;

[0067] In step S15, if it is determined that the vehicle has a braking failure, the control motor is put into ASC mode or FW mode.

[0068] Figure 2This is a flowchart illustrating the control strategy and control system for limiting drive torque or limiting regenerative torque in the event of braking failure in an electric drive system according to an embodiment of the present invention. In this embodiment, the specific steps for performing the limiting drive torque or limiting regenerative torque operation can be various steps known to those skilled in the art. In a preferred example of the present invention, performing the limiting drive torque or limiting regenerative torque operation can be as follows: Figure 2 The steps are shown. In this Figure 2 In this context, methods for performing operations that limit drive torque or limit regenerative torque may include:

[0069] In step S121, the stroke of the vehicle's brake master cylinder is obtained;

[0070] In step S122, it is determined whether the stroke of the brake master cylinder is greater than a preset first distance threshold.

[0071] In step S1201, if it is determined that the stroke of the brake master cylinder is greater than the first distance threshold, the torque signal of the vehicle is acquired;

[0072] If the master cylinder stroke exceeds the first distance threshold, it is determined that the master cylinder stroke is too large, and the vehicle's drive torque needs to be limited.

[0073] In step S1202, the current vehicle's gear mode is determined;

[0074] In step S1203, when the vehicle is in forward gear, it is determined whether the torque signal is greater than 0; when the vehicle is in reverse gear, it is determined whether the torque signal is less than 0. The purpose of this step is to determine whether the current torque is the driving torque.

[0075] In step S1204, if the vehicle is in drive gear and the torque signal is greater than 0, the current torque is determined to be the drive torque; if the vehicle is in reverse gear and the torque signal is less than 0, the current torque is determined to be the drive torque.

[0076] Conversely, if the vehicle is determined to be in forward gear and the torque signal is less than 0, the process can return to the step of determining whether the current torque is the driving torque, i.e., step S1203.

[0077] In step S1205, if the current torque is the driving torque, a driving torque limiting operation is performed;

[0078] In step S1206, after a preset first duration of the operation to limit the drive torque, it is determined whether the absolute value of the torque signal is greater than a preset first torque threshold.

[0079] The effect of limiting the drive torque is judged only after the limiting effect has been applied for a period of time.

[0080] In step S1207, if the absolute value of the torque signal is greater than the first torque threshold, it is determined that the vehicle has an abnormal torque.

[0081] In step S1208, if the absolute value of the torque signal is less than or equal to the first torque threshold, it is determined that the vehicle has not experienced torque abnormality.

[0082] In step S1211, if it is determined that the stroke of the brake master cylinder is less than or equal to the first distance threshold, it is determined whether the stroke of the brake master cylinder is less than the preset second distance threshold.

[0083] In step S1212, if it is determined that the stroke of the brake master cylinder is less than the second distance threshold, the torque signal of the vehicle is acquired;

[0084] If the master cylinder stroke is less than the second distance threshold, it is determined that the master cylinder stroke is too small, and the feedback torque needs to be limited.

[0085] In step S1213, the current vehicle's gear mode is determined;

[0086] In step S1214, it is determined whether the vehicle is in forward gear and whether the torque signal is less than 0. The purpose of this step is to determine whether the current torque is feedback torque.

[0087] In step S1215, if it is determined that the vehicle is in forward gear and the torque signal is less than 0, the current torque is determined to be the feedback torque.

[0088] Conversely, if the vehicle is in forward gear and the torque signal is greater than 0, or the vehicle is in reverse gear and the torque signal is less than 0, the process can return to the step of determining whether the current torque is feedback torque, i.e., execute step S1214.

[0089] In step S1216, if the current torque is the feedback torque, the feedback torque limiting operation is performed;

[0090] In step S1217, after a preset first duration of performing the limited feedback torque operation, it is determined whether the torque signal is less than a preset second torque threshold.

[0091] The effect of limiting the feedback torque is judged only after the limiting torque has been applied for a period of time.

[0092] In step S1218, if the torque signal is determined to be less than the second torque threshold, it is determined that the vehicle has a torque abnormality.

[0093] In step S1219, if the torque signal is greater than or equal to the second torque threshold, it is determined that the vehicle has not experienced torque abnormality.

[0094] Figure 3This is a flowchart illustrating the control strategy and control system's execution of torque-limiting operations when the braking function of an electric drive system fails, according to one embodiment of the present invention. In this embodiment, the specific steps for performing the torque-limiting operation can be various steps known to those skilled in the art. In a preferred example of the present invention, performing the torque-limiting operation can be as follows: Figure 3 The steps are shown. In this Figure 3 In this context, methods for performing torque-limiting operations may include:

[0095] In step S131, a torque limiting operation is performed on the vehicle;

[0096] In step S132, the vehicle's torque signal is acquired;

[0097] In step S133, after a preset first duration of performing the torque limiting operation on the vehicle, it is determined whether the absolute value of the torque signal is greater than a preset third torque threshold.

[0098] The effectiveness of the torque limiting is assessed only after the torque has been limited for a period of time.

[0099] In step S134, if the absolute value of the torque signal is greater than the third torque threshold, it is determined that the vehicle has an abnormal torque.

[0100] In step S135, if the absolute value of the torque signal is less than or equal to the third torque threshold, it is determined that the vehicle has not experienced torque abnormality.

[0101] Figure 4 This is a flowchart illustrating the control strategy and control system for determining whether a vehicle has experienced a braking malfunction when the braking function of an electric drive system fails, according to one embodiment of the present invention. In this embodiment, the specific steps for determining whether a vehicle has experienced a braking malfunction can be various steps known to those skilled in the art. In a preferred example of the present invention, determining whether a vehicle has experienced a braking malfunction can be as follows: Figure 4 The steps are shown. In this Figure 4 In this context, methods for determining whether a vehicle has a braking malfunction may include:

[0102] In step S141, when the vehicle experiences abnormal torque, the first continuous sampling time of the abnormal torque is determined, and the duration of the abnormality needs to be determined.

[0103] In step S142, it is determined whether the first continuous sampling time is greater than or equal to a preset first time threshold.

[0104] In step S143, if the first continuous sampling time is greater than or equal to the first time threshold, it is determined that the vehicle has a braking failure.

[0105] In step S144, if the first continuous sampling time is less than the first time threshold, it is determined that the vehicle has not experienced a braking failure.

[0106] Figure 5 This is a detailed flowchart of the control strategy and control system for an electric drive system when the braking function fails, according to an embodiment of the present invention. The detailed steps of the control strategy for an electric drive system when the braking function fails are as follows: Figure 5 As shown.

[0107] On the other hand, the present invention also provides a control system for when the braking function of an electric drive system fails, the control system including a controller for executing the control strategy as described above. The control strategy is specifically as follows... Figures 1 to 5 As shown.

[0108] Figure 1 This is a flowchart of a control strategy and control system for an electric drive system when the braking function fails, according to an embodiment of the present invention. Figure 1 The specific steps of this control strategy may include:

[0109] In step S10, the validity signal of the vehicle's brake master cylinder stroke is obtained;

[0110] The brake master cylinder stroke validity signal is used to determine whether the vehicle is in a normal driving state. If an abnormal situation occurs, such as a collision, the acquired brake master cylinder stroke data will be invalid, and the brake master cylinder stroke validity signal will be invalid. The validity of the acquired brake master cylinder stroke data can be determined based on the brake master cylinder stroke validity signal.

[0111] In step S11, it is determined whether the brake master cylinder stroke validity signal is valid;

[0112] In step S12, if the brake master cylinder stroke validity signal is valid, the operation of limiting drive torque or limiting feedback torque is performed.

[0113] The conditions for determining whether the current torque is driving torque or regenerative torque are as follows: When the vehicle is in forward gear, if the torque signal is greater than 0, it is driving torque, and the vehicle is in forward electric mode; if the torque signal is less than 0, it is regenerative torque, and the vehicle is in forward generator mode, with the motor generating electricity. When the vehicle is in reverse gear, if the torque signal is less than 0, it is driving torque, and the vehicle is in reverse electric mode. Since the vehicle does not have a reverse generator mode, there is no condition for determining if the torque signal is greater than 0.

[0114] In step S13, if the brake master cylinder stroke validity signal is invalid, a torque limiting operation is performed;

[0115] In step S14, it is determined whether the vehicle has a braking malfunction;

[0116] In step S15, if it is determined that the vehicle has a braking failure, the control motor is put into ASC mode or FW mode.

[0117] Figure 2 This is a flowchart illustrating the control strategy and control system for limiting drive torque or limiting regenerative torque in the event of braking failure in an electric drive system according to an embodiment of the present invention. In this embodiment, the specific steps for performing the limiting drive torque or limiting regenerative torque operation can be various steps known to those skilled in the art. In a preferred example of the present invention, performing the limiting drive torque or limiting regenerative torque operation can be as follows: Figure 2 The steps are shown. In this Figure 2 In this context, methods for performing operations that limit drive torque or limit regenerative torque may include:

[0118] In step S121, the stroke of the vehicle's brake master cylinder is obtained;

[0119] In step S122, it is determined whether the stroke of the brake master cylinder is greater than a preset first distance threshold.

[0120] In step S1201, if it is determined that the stroke of the brake master cylinder is greater than the first distance threshold, the torque signal of the vehicle is acquired;

[0121] If the master cylinder stroke exceeds the first distance threshold, it is determined that the master cylinder stroke is too large, and the vehicle's drive torque needs to be limited.

[0122] In step S1202, the current vehicle's gear mode is determined;

[0123] In step S1203, when the vehicle is in forward gear, it is determined whether the torque signal is greater than 0; when the vehicle is in reverse gear, it is determined whether the torque signal is less than 0. The purpose of this step is to determine whether the current torque is the driving torque.

[0124] In step S1204, if the vehicle is in drive gear and the torque signal is greater than 0, the current torque is determined to be the drive torque; if the vehicle is in reverse gear and the torque signal is less than 0, the current torque is determined to be the drive torque.

[0125] Conversely, if the vehicle is determined to be in forward gear and the torque signal is less than 0, the process can return to the step of determining whether the current torque is the driving torque, i.e., step S1203.

[0126] In step S1205, if the current torque is the driving torque, a driving torque limiting operation is performed;

[0127] In step S1206, after a preset first duration of the operation to limit the drive torque, it is determined whether the absolute value of the torque signal is greater than a preset first torque threshold.

[0128] The effect of limiting the drive torque is judged only after the limiting effect has been applied for a period of time.

[0129] In step S1207, if the absolute value of the torque signal is greater than the first torque threshold, it is determined that the vehicle has an abnormal torque.

[0130] In step S1208, if the absolute value of the torque signal is less than or equal to the first torque threshold, it is determined that the vehicle has not experienced torque abnormality.

[0131] In step S1211, if it is determined that the stroke of the brake master cylinder is less than or equal to the first distance threshold, it is determined whether the stroke of the brake master cylinder is less than the preset second distance threshold.

[0132] In step S1212, if it is determined that the stroke of the brake master cylinder is less than the second distance threshold, the torque signal of the vehicle is acquired;

[0133] If the master cylinder stroke is less than the second distance threshold, it is determined that the master cylinder stroke is too small, and the feedback torque needs to be limited.

[0134] In step S1213, the current vehicle's gear mode is determined;

[0135] In step S1214, it is determined whether the vehicle is in forward gear and whether the torque signal is less than 0. The purpose of this step is to determine whether the current torque is feedback torque.

[0136] In step S1215, if it is determined that the vehicle is in forward gear and the torque signal is less than 0, the current torque is determined to be the feedback torque.

[0137] Conversely, if the vehicle is in forward gear and the torque signal is greater than 0, or the vehicle is in reverse gear and the torque signal is less than 0, the process can return to the step of determining whether the current torque is feedback torque, i.e., execute step S1214.

[0138] In step S1216, if the current torque is the feedback torque, the feedback torque limiting operation is performed;

[0139] In step S1217, after a preset first duration of performing the limited feedback torque operation, it is determined whether the torque signal is less than a preset second torque threshold.

[0140] The effect of limiting the feedback torque is judged only after the limiting torque has been applied for a period of time.

[0141] In step S1218, if the torque signal is determined to be less than the second torque threshold, it is determined that the vehicle has a torque abnormality.

[0142] In step S1219, if the torque signal is greater than or equal to the second torque threshold, it is determined that the vehicle has not experienced torque abnormality.

[0143] Figure 3 This is a flowchart illustrating the control strategy and control system's execution of torque-limiting operations when the braking function of an electric drive system fails, according to one embodiment of the present invention. In this embodiment, the specific steps for performing the torque-limiting operation can be various steps known to those skilled in the art. In a preferred example of the present invention, performing the torque-limiting operation can be as follows: Figure 3 The steps are shown. In this Figure 3 In this context, methods for performing torque-limiting operations may include:

[0144] In step S131, a torque limiting operation is performed on the vehicle;

[0145] In step S132, the vehicle's torque signal is acquired;

[0146] In step S133, after a preset first duration of performing the torque limiting operation on the vehicle, it is determined whether the absolute value of the torque signal is greater than a preset third torque threshold.

[0147] The effectiveness of the torque limiting is assessed only after the torque has been limited for a period of time.

[0148] In step S134, if the absolute value of the torque signal is greater than the third torque threshold, it is determined that the vehicle has an abnormal torque.

[0149] In step S135, if the absolute value of the torque signal is less than or equal to the third torque threshold, it is determined that the vehicle has not experienced torque abnormality.

[0150] Figure 4 This is a flowchart illustrating the control strategy and control system for determining whether a vehicle has experienced a braking malfunction when the braking function of an electric drive system fails, according to one embodiment of the present invention. In this embodiment, the specific steps for determining whether a vehicle has experienced a braking malfunction can be various steps known to those skilled in the art. In a preferred example of the present invention, determining whether a vehicle has experienced a braking malfunction can be as follows: Figure 4 The steps are shown. In this Figure 4 In this context, methods for determining whether a vehicle has a braking malfunction may include:

[0151] In step S141, when the vehicle experiences abnormal torque, the first continuous sampling time of the abnormal torque is determined, and the duration of the abnormality needs to be determined.

[0152] In step S142, it is determined whether the first continuous sampling time is greater than or equal to a preset first time threshold.

[0153] In step S143, if the first continuous sampling time is greater than or equal to the first time threshold, it is determined that the vehicle has a braking failure.

[0154] In step S144, if the first continuous sampling time is less than the first time threshold, it is determined that the vehicle has not experienced a braking failure.

[0155] Figure 5 This is a detailed flowchart of the control strategy and control system for an electric drive system when the braking function fails, according to an embodiment of the present invention. The detailed steps of the control strategy for an electric drive system when the braking function fails are as follows: Figure 5 As shown.

[0156] Through the above technical solution, the control strategy and control system provided by the present invention for the failure of the braking function of the electric drive system obtains the validity signal of the brake master cylinder stroke of the vehicle, determines whether the validity signal of the brake master cylinder stroke validity signal is valid, and decides to perform the operation of limiting drive torque or limiting feedback torque or performing the operation of limiting torque. Based on the execution result, it is determined whether the vehicle has a braking failure. In the case of a braking failure, the motor is controlled to enter a safe state, that is, to enter ASC mode or FW mode, so as to enable the motor to enter a safe state in time when the braking function fails, thereby ensuring the safety of vehicle driving.

[0157] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0158] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1A device that provides the functions specified in one or more boxes.

[0159] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0160] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0161] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0162] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0163] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0164] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0165] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A control strategy for when the braking function of an electric drive system fails, characterized in that, The control strategy includes: Obtain the validity signal of the vehicle's master cylinder stroke; Determine whether the brake master cylinder stroke validity signal is valid; If the brake master cylinder stroke validity signal is deemed valid, the operation of limiting drive torque or limiting regenerative torque is performed. If the signal indicating the validity of the brake master cylinder stroke is invalid, a torque limiting operation is performed. Determine whether the vehicle has a braking malfunction; If a braking failure is detected in the vehicle, the control motor is switched to ASC mode or FW mode. Perform operations to limit drive torque or limit regenerative torque, including: Obtain the master cylinder stroke of the vehicle; Determine whether the stroke of the brake master cylinder is greater than a preset first distance threshold; If it is determined that the stroke of the brake master cylinder is greater than the first distance threshold, the torque signal of the vehicle is acquired; Determine the current vehicle's gear mode; When the vehicle is in drive, determine whether the torque signal is greater than 0; If the vehicle is in drive and the torque signal is greater than 0, the current torque is determined to be the drive torque. If the current torque is the driving torque, perform a driving torque limiting operation; After a preset first duration of performing the limited drive torque operation, it is determined whether the absolute value of the torque signal is greater than a preset first torque threshold. If the absolute value of the torque signal is greater than the first torque threshold, it is determined that the vehicle has a torque abnormality. Perform operations to limit drive torque or limit regenerative torque, including: If it is determined that the brake master cylinder stroke is less than or equal to the first distance threshold, it is determined whether the brake master cylinder stroke is less than a preset second distance threshold; If it is determined that the stroke of the brake master cylinder is less than the second distance threshold, the torque signal of the vehicle is acquired; Determine the current vehicle's gear mode; Determine whether the vehicle is in a forward gear and whether the torque signal is less than 0; If the vehicle is in forward gear and the torque signal is less than 0, the current torque is determined to be feedback torque. When the current torque is the feedback torque, a feedback torque limiting operation is performed; after a preset first duration of the feedback torque limiting operation, it is determined whether the torque signal is less than a preset second torque threshold. If the torque signal is determined to be less than the second torque threshold, it is determined that the vehicle has an abnormal torque. Determining whether the vehicle has a braking malfunction includes: In the event of abnormal torque in the vehicle, the first continuous sampling time at which the abnormal torque occurs is determined; Determine whether the first continuous sampling time is greater than or equal to a preset first time threshold; If the first continuous sampling time is greater than or equal to the first time threshold, it is determined that the vehicle has a braking failure.

2. The control strategy according to claim 1, characterized in that, Perform operations to limit drive torque or limit regenerative torque, including: When the vehicle is in reverse gear, determine whether the torque signal is less than 0; If the vehicle is in reverse gear and the torque signal is less than 0, the current torque is determined to be the driving torque.

3. The control strategy according to claim 1, characterized in that, Perform operations to limit drive torque or limit regenerative torque, including: If the absolute value of the torque signal is less than or equal to the first torque threshold, it is determined that the vehicle has not experienced any torque abnormality.

4. The control strategy according to claim 3, characterized in that, Perform operations to limit drive torque or limit regenerative torque, including: If the torque signal is determined to be greater than or equal to the second torque threshold, it is determined that the vehicle does not have a torque abnormality.

5. The control strategy according to claim 1, characterized in that, Perform torque limiting operations, including: Perform a torque limiting operation on the vehicle; Obtain the torque signal of the vehicle; After a preset first duration of performing the torque limiting operation on the vehicle, it is determined whether the absolute value of the torque signal is greater than a preset third torque threshold. If the absolute value of the torque signal is greater than the third torque threshold, it is determined that the vehicle has a torque abnormality.

6. The control strategy according to claim 5, characterized in that, Perform torque limiting operations, including: If the absolute value of the torque signal is less than or equal to the third torque threshold, it is determined that the vehicle does not have a torque abnormality.

7. A control system for when the braking function of an electric drive system fails, characterized in that, The control system includes a controller for executing the control strategy as described in any one of claims 1 to 6.

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