A control method and system for electric vehicle drive motor with front-stage fault tolerance

Abstract

The present invention provides a control method and system for an electric vehicle drive motor during front-stage fault tolerance, which belongs to the technical field of electric vehicles. The method comprises: determining the current working condition of the electric vehicle and determining the maximum output power of the motor of the electric vehicle according to the working condition, then determining the maximum output power of the electric vehicle according to the working condition, and adjusting the control method of the electric vehicle during front-stage fault tolerance, so that all power switching devices in the drive inverter of the electric vehicle do not flow during front-stage fault tolerance, thereby improving the safety of the electric vehicle. At the same time, it can also ensure the flow performance of the drive motor of the electric vehicle during front-stage fault tolerance, and ensure the safety and smoothness of the vehicle during driving.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicles, and in particular to a control method and system for a driving motor of an electric vehicle in a front-stage fault-tolerant manner. Background Art

[0002] At present, electric vehicle drive motors usually use non-isolated drive inverters, which cannot achieve high-voltage electrical isolation, increasing the safety risks of electric vehicles. Isolated drive inverters can improve electrical safety, but the structure of a front-stage isolated DC / DC converter plus a rear-stage DC / AC inverter has circuit unreliability, especially when the front-stage isolated DC / DC converter fails, the drive inverter will not work. The fault-tolerant dual-winding coupled DC / DC converter can achieve fault tolerance without redundant component switching and can be applied to the front stage, but the output power will be reduced when it is fault-tolerant. At this time, if the rear stage can work at full power, it will cause overcurrent in the front stage, resulting in safety hazards. Summary of the invention

[0003] The purpose of the embodiment of the present invention is to provide a control method and system for an electric vehicle drive motor during front-stage fault tolerance. The method and system respectively explore the control method during front-stage fault tolerance for the ports of the drive motor and the three working conditions of the maximum power required by the motor to ensure the safety of the vehicle.

[0004] In order to achieve the above object, the present invention provides a control method for a driving motor of an electric vehicle in a front-stage fault-tolerant manner, the control method comprising:

[0005] Determine the current operating condition of the electric vehicle, the operating condition including: the electric vehicle is in a maximum power demand condition at the highest speed on a horizontal road, the electric vehicle is in a maximum power demand condition at a fixed speed climbing a slope, and the electric vehicle is in a fixed acceleration condition;

[0006] Determine the maximum output power of the motor according to the operating conditions corresponding to the electric vehicle;

[0007] The control method is adjusted according to the maximum output power to ensure that all power switch devices in the drive converter of the electric vehicle do not over-current when the front-stage fault tolerance is in effect. Optionally, determining the maximum output power of the motor of the electric vehicle according to the working condition includes:

[0008] When the electric vehicle is in a maximum power demand condition at the highest speed on a horizontal road, the maximum output power of the motor of the electric vehicle is determined according to formula (1):

[0009] P max1 =v max (A 1 +A 2 v max2 ), (1)

[0010] Among them, P max1 is the maximum output power of the motor of the electric vehicle when it is in the maximum power demand condition at the highest speed on a horizontal road, v max is the maximum vehicle speed in fault-tolerant mode, A 1 , A 2 It is the coefficient of the relevant variables when the electric vehicle is in the maximum power demand condition with the highest speed in the horizontal direction.

[0011] Optionally, determining the maximum output power of the motor of the electric vehicle according to formula (1) includes:

[0012] Determine the coefficient A according to formula (2): 1 ,

[0013]

[0014] Determine the coefficient A according to formula (3): 2 ,

[0015]

[0016] Among them, η T is the mechanical efficiency of the transmission system, m is the vehicle curb weight, g is the acceleration of gravity, g = 9.8 m / s 2 , f is the rolling friction coefficient, C D is the air resistance coefficient, and A is the frontal area of ​​the vehicle.

[0017] Optionally, determining the maximum output power of the motor of the electric vehicle according to the working condition includes:

[0018] When the electric vehicle is in a maximum power demand condition of climbing a hill at a fixed speed, the maximum output power of the motor of the electric vehicle is determined according to formula (4):

[0019] P max2 =v a (A 3 +A 4 v a 2 ), (4)

[0020] Among them, P max2 is the maximum output power of the motor of the electric vehicle when it is in the maximum power demand condition of climbing at a fixed speed, v a is the climbing speed in fault-tolerant mode, A 3 , A 4 is the coefficient of the variable composition when the electric vehicle is in the maximum required power condition of climbing at a fixed speed.

[0021] Optionally, determining the maximum output power of the motor of the electric vehicle according to formula (4) includes:

[0022] Determine the coefficient A according to formula (5): 3 ,

[0023]

[0024] Determine the coefficient A according to formula (6): 4 ,

[0025] A 4 =A 2 , (6)

[0026] Among them, η T is the mechanical efficiency of the transmission system, m is the vehicle curb weight, g is the acceleration of gravity, g = 9.8 m / s 2 , f is the rolling friction coefficient, C D is the air resistance coefficient, A is the frontal area of ​​the vehicle, and α is the maximum climbing grade.

[0027] Optionally, determining the maximum output power of the motor of the electric vehicle according to the working condition includes:

[0028] When the electric vehicle is in a fixed acceleration condition, the maximum output power of the motor of the electric vehicle is determined according to formula (7):

[0029]

[0030] Among them, P max3 is the maximum output power of the motor under the fixed acceleration condition, t acc is the acceleration time in fault-tolerant mode, A 5 , A 6 is the coefficient of the variable composition under the fixed acceleration condition.

[0031] Optionally, determining the maximum output power of the motor of the electric vehicle according to formula (7) includes:

[0032] Determine the coefficient A according to formula (8): 5 ,

[0033]

[0034] Determine the coefficient A according to formula (9): 6 ,

[0035]

[0036] Among them, η Tis the mechanical efficiency of the transmission system, m is the vehicle curb weight, g is the acceleration of gravity, g = 9.8 m / s 2 , f is the rolling friction coefficient, C D is the air resistance coefficient, δ is the electric vehicle rotation mass conversion coefficient, u m The target speed to be achieved during the acceleration process.

[0037] On the other hand, an embodiment of the present invention provides a control system for a drive motor of an electric vehicle in a front-stage fault-tolerant manner. The system includes a controller, and the controller is configured to execute any of the control methods described above.

[0038] On the other hand, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions, wherein the instructions are used to be read by a machine so that the machine executes any of the control methods described above.

[0039] Through the above technical scheme, the present invention provides a control method and system for an electric vehicle drive motor during front-stage fault tolerance, which confirms the working condition of the maximum power required by the electric vehicle, determines the maximum output power of the electric vehicle according to the working condition, and adjusts the control method during front-stage fault tolerance. It can ensure that all power switching devices in the drive inverter of the electric vehicle do not pass current during front-stage fault tolerance, thereby improving the safety of the electric vehicle. At the same time, it can also ensure the flow performance of the drive motor of the electric vehicle during front-stage fault tolerance, and ensure the safety and smoothness of the vehicle during driving.

[0040] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a schematic diagram of a control method for a driving motor of an electric vehicle during front-stage fault tolerance according to an embodiment of the present invention;

[0042] Figure 2 is a schematic diagram of a control system of a driving motor of an electric vehicle during front-stage fault tolerance according to an embodiment of the present invention;

[0043] Figure 3 A motor torque and power curve diagram of a control method for a driving motor of an electric vehicle in a front-stage fault-tolerant state according to an embodiment of the present invention, when the electric vehicle is in a maximum power demand condition at the highest speed on a horizontal road;

[0044] Figure 4 It is a constraint relationship curve diagram of the current when the electric vehicle is in a maximum required power condition of fixed speed climbing and the electric vehicle is in a fixed acceleration condition in a control method of a drive motor of an electric vehicle during a front-stage fault tolerance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0046] In the embodiments of the present application, unless otherwise specified, directional words such as "up, down, top, bottom" are usually used with reference to the directions shown in the drawings or are used to describe the relative positional relationships of components in the vertical, perpendicular or gravity direction.

[0047] In addition, if there are descriptions involving "first", "second", etc. in the implementation methods of this application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various implementation methods can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0048] In one embodiment of the present invention, Figure 2 As shown, the Figure 2 This is a schematic diagram of a control system of an electric vehicle drive motor in a front-stage fault-tolerant state in one embodiment of the present invention. Considering that the current drive motor of an electric vehicle usually adopts a non-isolated drive converter, it is impossible to achieve high-voltage electrical isolation, which increases the safety hazard of the electric vehicle. Therefore, the present invention adopts an isolated converter to improve the electrical safety. However, considering that the structure of the front-stage isolated DC / DC converter plus the rear-stage DC / AC inverter is adopted, there is unreliability of the circuit, especially when the front-stage isolated DC / DC converter fails, it will cause the drive converter to fail to work. Therefore, the present invention adopts a fault-tolerant dual-winding coupled DC / DC converter to achieve fault tolerance without redundant component switching, which can be applied to the front stage, but the power that can be output during fault tolerance will be reduced. At this time, if the rear stage can work at full power, it will cause the front stage to overcurrent, resulting in safety hazards. Therefore, the present invention provides a control method for the electric vehicle drive motor in the front-stage fault-tolerant state, by first determining the current working condition of the electric vehicle, then determining the maximum output power of the motor of the electric vehicle according to the working condition, and finally adjusting the electric vehicle under the working condition, so that the safety of the electric vehicle can be improved.

[0049] like Figure 1The figure is a schematic diagram of a control method for a driving motor of an electric vehicle in a front-stage fault-tolerant manner according to an embodiment of the present invention. Figure 1 In, the method comprises:

[0050] In step S1 , the current operating condition of the electric vehicle is determined.

[0051] In step S2, the maximum output power of the motor of the electric vehicle when the electric vehicle is in a maximum power demand condition at the highest speed on a horizontal road is determined according to formula (1).

[0052] In step S3, the maximum output power of the motor of the electric vehicle when the electric vehicle is in a maximum required power condition of climbing a hill at a fixed speed is determined according to formula (4).

[0053] In step S4, formula (7) determines the maximum output power of the motor of the electric vehicle when the electric vehicle is in a fixed acceleration condition.

[0054] In one embodiment of the present invention, for the drive motor port, the three working conditions of the maximum power required by the integrated motor are: the maximum power required working condition of the electric vehicle at the highest speed in the horizontal plane, the maximum power required working condition of the electric vehicle at a fixed speed climbing, and the electric vehicle at a fixed acceleration working condition. Discussing these three working conditions respectively, when the front stage is fault-tolerant, its output power will be reduced. At this time, if the rear stage can work at full power, it will cause overcurrent in the front stage, so the power of the rear stage when working should be reduced.

[0055] In one embodiment of the present invention, in the normal working mode of the electric vehicle, the maximum power of the motor is equal to the maximum power of the converter. In the case of the front-stage fault tolerance, the power of the converter will be reduced, and the motor cannot operate at the maximum power P max Instead, it works in the drive converter fault tolerance mode with the maximum power P fau , otherwise it will cause overload of converter current stress, where P max is the maximum power of the motor under three working conditions.

[0056] When the electric vehicle is in the maximum power demand condition at the highest speed in the horizontal direction, the maximum output power of the electric vehicle's motor is determined as shown in the following formula (1):

[0057] P max1 =v max (A 1 +A 2 v max 2 ), (1)

[0058] Where P max1is the maximum output power of the motor when the electric vehicle is in the maximum power demand condition at the highest speed in the horizontal direction, v max is the maximum vehicle speed in the fault-tolerant mode (i.e., the current state of the electric vehicle executing the control method), A 1 , A 2 It is the coefficient of the relevant variables when the electric vehicle is in the maximum power demand condition at the highest speed on a horizontal road.

[0059] When the electric vehicle is in the maximum power demand condition at the highest speed in the horizontal direction, A 1 is the coefficient determined by formula (2), A 2 is the coefficient determined by formula (3),

[0060]

[0061] Where ηT is the mechanical efficiency of the transmission system, m is the vehicle's curb weight, and g is the acceleration of gravity, g = 9.8 m / s 2 , f is the rolling friction coefficient, C D is the air resistance coefficient, and A is the frontal area of ​​the vehicle.

[0062] In one embodiment of the present invention, the maximum power requirement condition of the electric vehicle at the highest speed on a horizontal road is considered. In this condition, the maximum speed of the electric vehicle is related to the maximum power requirement of the electric vehicle. Figure 3 As shown, the Figure 3 It is a motor torque and power curve diagram of a control method of an electric vehicle driving motor in a front-stage fault-tolerant manner according to an embodiment of the present invention under the maximum power requirement condition of the electric vehicle at the highest speed on a horizontal road. Formula (10) determines the rated power PN of the motor under the maximum power requirement condition of the electric vehicle at the highest speed on a horizontal road, and formula (11) determines the maximum power P allowed in the front-stage fault-tolerant mode under the maximum power requirement condition of the electric vehicle at the highest speed on a horizontal road. fau By comparing the rated power of the motor with the maximum power allowed in the fault-tolerant mode, it is determined whether the front-stage fault tolerance has an impact on the maximum speed of horizontal road driving.

[0063]

[0064] P fau =kP max , (11)

[0065] Where λ is the overload factor, usually λ is 2 to 3, then P N <0.5P maxIn the fault-tolerant mode, the power of the motor needs to be limited to the maximum required power condition of the electric vehicle at the highest speed on a horizontal road to determine the maximum power P allowed in the front-stage fault-tolerant mode. fau , k is the reduction coefficient of the previous stage power. Since the matching coefficient is greater than 0.5, P fau >0.5P max Therefore, the maximum power P allowed in the front-stage fault-tolerant mode is determined when the electric vehicle is on a horizontal road with the highest speed and the maximum required power condition. fau Greater than the rated power P of the motor under the maximum power requirement condition of the electric vehicle at the highest speed on a horizontal road N , that is, P fau >P N ,According to these data, it can be concluded that under the condition of front-stage fault tolerance, there is no effect on the maximum vehicle speed on horizontal roads.

[0066] When the electric vehicle is in the maximum power demand condition of climbing at a fixed speed, determine the maximum output power P of the electric vehicle's motor. max2 , as shown in formula (4),

[0067] P max2 =v a (A 3 +A 4 v a 2 ), (4)

[0068] Among them, P max2 is the maximum output power of the motor of the electric vehicle when it is in the maximum power demand condition of climbing at a fixed speed, v a is the climbing speed in fault-tolerant mode, A 3 , A 4 It is the coefficient of the variable composition when the electric vehicle is in the maximum power demand condition of climbing at a fixed speed.

[0069] When the electric vehicle is in the maximum power demand condition of climbing at a fixed speed, A 3 Determined by formula (5), A 4 Determined by formula (6),

[0070]

[0071] A 4 =A 2 , (6)

[0072] Among them, η T is the mechanical efficiency of the transmission system, m is the vehicle curb weight, g is the acceleration of gravity, g = 9.8 m / s 2 , f is the rolling friction coefficient, C Dis the air resistance coefficient, A is the frontal area of ​​the vehicle, and α is the maximum climbing grade.

[0073] When the electric vehicle is in a fixed acceleration condition, determine the maximum output power P of the electric vehicle's motor. max3 , as shown in formula (7),

[0074]

[0075] Among them, P max3 is the maximum output power of the motor under fixed acceleration conditions, t acc is the acceleration time in fault-tolerant mode, A 5 , A 6 is the coefficient of the variable composition under fixed acceleration conditions.

[0076] When the electric vehicle is in a fixed acceleration condition, A 5 A is determined by formula (8). 6 Determined by formula (9),

[0077]

[0078] Among them, ηT is the mechanical efficiency of the transmission when the electric vehicle is in a fixed acceleration condition, m is the curb weight of the vehicle, and g is the acceleration of gravity, g = 9.8m / s 2 , f is the rolling friction coefficient, C D is the air resistance coefficient, δ is the electric vehicle rotation mass conversion coefficient, u m The target speed to be achieved during the acceleration process.

[0079] In one embodiment of the present invention, the electric vehicle is considered to be in a maximum power demand condition of fixed speed climbing and a fixed acceleration condition. The maximum power demand condition of the electric vehicle in fixed speed climbing is related to the climbing speed of fixed speed climbing, and the fixed acceleration condition is related to the acceleration time. Figure 4 As shown, the Figure 4 It is a constraint relationship curve diagram of the current when the electric vehicle is in a fixed speed climbing maximum required power condition and the electric vehicle is in a fixed acceleration condition in a control method of an electric vehicle driving motor in a front-stage fault-tolerant manner according to an embodiment of the present invention. For both conditions, it is possible that the maximum power allowed when the electric vehicle is in these two conditions to determine the front-stage fault tolerance is less than the maximum power of the motor. In theory, as long as the climbing speed is low enough and the acceleration time is long enough, the motor power during climbing and acceleration can be controlled below the maximum power allowed in the front-stage fault-tolerant mode. However, in the normal working mode, climbing and acceleration are usually controlled by the maximum torque current ratio. In Figure 4, the speed ω corresponding to the intersection of the MTPA curve and the current limit circle curvemin is the minimum speed allowed by the motor. The current limit circle is determined by the subsequent DC / AC converter. If only the previous stage is fault-tolerant, the current limit circle remains unchanged, but is limited by the electromagnetic power of the motor. The AC and DC axis current i d and i q Need to satisfy formula (12),

[0080]

[0081] Considering the variables that can be controlled by the converter, equation (12) can be simplified to equation (13),

[0082]

[0083] Among them, P e is the rated power of the motor when the electric vehicle is in the maximum power demand condition of fixed speed climbing and fixed acceleration condition, ω m is the motor speed, n p is the number of motor pole pairs, i d and i q is the AC and DC axis current, L d and L q is the AC-axis inductance, ψ f is the stator flux, B 1 and B 2 It is the coefficient of the relevant variables composed of the maximum required power condition of the electric vehicle in a fixed speed climbing condition and the electric vehicle in a fixed acceleration condition.

[0084] B 1 Determined by formula (14), B 2 Determined by formula (15),

[0085]

[0086] Among them, n p is the number of motor pole pairs, ψ f is the stator flux, L d and L q is the AC-axis inductance.

[0087] In one embodiment of the present invention, the current constraint relationship can be obtained from formula (12) to formula (15), such as Figure 4 As shown, when point A is the limit point in normal mode, it corresponds to the maximum torque within the current constraint range, and the speed at this time is ω 1 , in the previous stage fault tolerance, the constraint conditions shown in formula (16) are added,

[0088] P e =P fau (ω m=ω 1 ), (16)

[0089] At this time, point A does not meet the constraint conditions of formula (16) and can be changed to point D to maintain the speed, but the torque will decrease. If it is changed to point E to reduce the speed and increase the torque, the maximum torque cannot be reached. When point E falls on the limit circle, the corresponding torque is the maximum torque that can be achieved during the previous fault tolerance. When the electric vehicle is in the maximum required power condition of fixed speed climbing and the electric vehicle is in a fixed acceleration condition in the control method of the electric vehicle drive motor, the maximum power allowed during the previous fault tolerance is greater than the maximum power of the motor, so that the previous fault tolerance has no effect on the two conditions of the maximum required power of the electric vehicle in the control method of the electric vehicle drive motor and the electric vehicle in a fixed acceleration.

[0090] In one embodiment of the present invention, the current constraint relationship can be obtained from formula (12) to formula (15), such as Figure 4 As shown, when point B is the limit point in normal mode, the speed at this time is ω 2 , in the previous stage fault tolerance, the constraint conditions shown in formula (17) are added,

[0091] P e =P fau (ω m =ω 2 ), (17)

[0092] At this time, point B does not meet the constraint condition of formula (17), so it can be changed to point F to reduce the speed and maintain the torque, so that in the control method of the electric vehicle drive motor, when the electric vehicle is in the maximum required power condition of fixed speed climbing and the electric vehicle is in the fixed acceleration condition, the maximum power allowed by the front-stage fault tolerance is greater than the maximum power of the motor, so that the front-stage fault tolerance has no effect on the two conditions of the maximum required power of the electric vehicle in the control method of the electric vehicle drive motor and the electric vehicle in the fixed acceleration condition.

[0093] In one embodiment of the present invention, the current constraint relationship can be obtained from formula (12) to formula (15), such as Figure 4 As shown, when point C is the limit point in normal mode, the speed at this time is ω 3 , in the previous stage fault tolerance, the constraint conditions shown in formula (18) are added,

[0094] P e =P fau (ω m =ω 3 ), (18)

[0095] At this time, point C satisfies the constraint condition of formula (18) and can continue to be maintained at point C during the previous stage fault tolerance, so that in the control method of the electric vehicle drive motor, when the electric vehicle is in the maximum required power condition of fixed speed climbing and the electric vehicle is in the fixed acceleration condition, the maximum power allowed during the previous stage fault tolerance is greater than the maximum power of the motor, so that the previous stage fault tolerance has no effect on the two conditions of the maximum required power of the electric vehicle in the control method of the electric vehicle drive motor when the electric vehicle is in the fixed speed climbing and the electric vehicle is in the fixed acceleration.

[0096] On the other hand, the present invention further provides a control system for a drive motor of an electric vehicle with front-stage fault tolerance, the system comprising a controller, and the controller is configured to execute any of the above control methods.

[0097] On the other hand, the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions, and the instructions are used to be read by a machine so that the machine executes any of the above methods.

[0098] Through the above technical scheme, the present invention provides a control method and system for an electric vehicle drive motor during front-stage fault tolerance, which confirms the working condition of the maximum power required by the electric vehicle, determines the maximum output power of the electric vehicle according to the working condition, and adjusts the control method during front-stage fault tolerance. It can ensure that all power switching devices in the drive inverter of the electric vehicle do not pass current during front-stage fault tolerance, thereby improving the safety of the electric vehicle. At the same time, it can also ensure the flow performance of the drive motor of the electric vehicle during front-stage fault tolerance, and ensure the safety and smoothness of the vehicle during driving.

[0099] The optional implementation modes of the examples of the present invention are described in detail above in conjunction with the accompanying drawings; however, the implementation modes of the present invention are not limited to the specific details in the above implementation modes; within the technical concept of the implementation modes of the present invention, a variety of simple modifications can be made to the technical solutions of the implementation modes of the present invention, and these simple modifications all belong to the protection scope of the implementation modes of the present invention.

[0100] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0101] Those skilled in the art can understand that all or part of the steps in the above-mentioned implementation method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions to enable a (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to execute all or part of the steps of each implementation method of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0102] In addition, various different embodiments of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A control method for a driving motor of an electric vehicle with front-stage fault tolerance, characterized in that: The control method comprises: Determine the current operating condition of the electric vehicle, the operating condition including: the electric vehicle is in a maximum power demand condition at the highest speed on a horizontal road, the electric vehicle is in a maximum power demand condition at a fixed speed climbing a slope, and the electric vehicle is in a fixed acceleration condition; Determine the maximum output power of the motor according to the operating conditions corresponding to the electric vehicle; The control method is adjusted according to the maximum output power to ensure that all power switch devices in the drive converter of the electric vehicle do not over-current during the previous stage fault tolerance.

2. The control method according to claim 1, characterized in that: Determining the maximum output power of the motor of the electric vehicle according to the working condition includes: When the electric vehicle is in a maximum power demand condition at the highest speed on a horizontal road, the maximum output power of the motor of the electric vehicle is determined according to formula (1): P max1 =in max (A1+A2v max 2 ), (1) Among them, P max1 is the maximum output power of the motor of the electric vehicle when it is in the maximum power demand condition at the highest speed on a horizontal road, v max is the maximum vehicle speed in the fault-tolerant mode, and A1 and A2 are coefficients of related variables when the electric vehicle is in a maximum required power condition with the highest vehicle speed in the horizontal direction.

3. The control method according to claim 2, characterized in that: Determining the maximum output power of the motor of the electric vehicle according to formula (1) includes: Determine the coefficient A1 according to formula (2): Determine the coefficient A2 according to formula (3): Among them, η T is the mechanical efficiency of the transmission system, m is the vehicle curb weight, g is the acceleration of gravity, g = 9.8 m / s 2 , f is the rolling friction coefficient, C D is the air resistance coefficient, and A is the frontal area of ​​the vehicle.

4. The control method according to claim 1, characterized in that: Determining the maximum output power of the motor of the electric vehicle according to the working condition includes: When the electric vehicle is in a maximum power demand condition of climbing a hill at a fixed speed, the maximum output power of the motor of the electric vehicle is determined according to formula (4): P max2 =v a (A3+A4v a 2 ), (4) Among them, P max2 is the maximum output power of the motor of the electric vehicle when it is in the maximum power demand condition of climbing at a fixed speed, v a is the climbing speed in the fault-tolerant mode, and A3 and A4 are coefficients of variable composition when the electric vehicle is in a maximum required power condition of climbing at a fixed speed.

5. The control method according to claim 4, characterized in that: Determining the maximum output power of the motor of the electric vehicle according to formula (4) includes: Determine the coefficient A3 according to formula (5): Determine the coefficient A4 according to formula (6): A4=A2, (6) Among them, η T is the mechanical efficiency of the transmission system, m is the vehicle curb weight, g is the acceleration of gravity, g = 9.8 m / s 2 , f is the rolling friction coefficient, C D is the air resistance coefficient, A is the frontal area of ​​the vehicle, and α is the maximum climbing grade.

6. The control method according to claim 1, characterized in that: Determining the maximum output power of the motor of the electric vehicle according to the working condition includes: When the electric vehicle is in a fixed acceleration condition, the maximum output power of the motor of the electric vehicle is determined according to formula (7): Among them, P max3 is the maximum output power of the motor under the fixed acceleration condition, t acc is the acceleration time in the fault-tolerant mode, and A5 and A6 are the coefficients of the variable composition under the fixed acceleration condition.

7. The control method according to claim 6, characterized in that: Determining the maximum output power of the motor of the electric vehicle according to formula (7) includes: Determine the coefficient A5 according to formula (8): Determine the coefficient A6 according to formula (9): Among them, η T is the mechanical efficiency of the transmission system, m is the vehicle curb weight, g is the acceleration of gravity, g = 9.8 m / s 2 , f is the rolling friction coefficient, C D is the air resistance coefficient, δ is the electric vehicle rotation mass conversion coefficient, u m The target speed to be achieved during the acceleration process.

8. A control system for a drive motor of an electric vehicle with front-stage fault tolerance, characterized in that: The system comprises a controller configured to execute the control method according to any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and the instructions are used to be read by a machine so that the machine executes the control method according to any one of claims 1 to 7.

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