Multi-motor drive vehicle system capability estimation and protection control method and system

Abstract

The application discloses a kind of multi-motor drive vehicle system capacity estimation and protection control method, it is related to vehicle design technical field, the method first respectively calculates the maximum driving power of protection battery allowed driving system, driving system maximum driving torque, driving system external characteristic torque, the maximum driving power and driving torque of current allowed each axle driving system of front / rear in driving system, the power loss characteristic of electric drive system in different driving demand torque-speed-distribution coefficient;Then after driving demand torque module resolves driving demand torque, total torque protection of driving system is carried out before torque distribution, front axle driving torque protection and driving total power protection are carried out in distribution process.The system capacity protection before distribution and distribution process is realized, without secondary distribution, guaranteeing that front axle torque distribution is carried out in electric drive system capacity range, and then the improvement of economy or power is realized.

Description

Technical Field

[0001] This invention relates to the field of vehicle design technology, and specifically to a method and system for capacity estimation and protection control of a multi-motor drive vehicle system. Background Technology

[0002] To prevent battery failures or lifespan degradation caused by over-discharge, overheating, or excessive voltage difference in the battery system, as well as motor and motor controller overheating failures or lifespan degradation caused by continuous over-power operation of the electric drive system, electric vehicles typically require capacity estimation and system protection for the battery and electric drive system.

[0003] For single-motor drive systems, protection of the battery and electric drive system can be achieved simply by comparing the driving torque demand with the battery system capacity limit and the motor capacity limit, and taking the smaller value. However, for multi-motor drive electric vehicles, based on economic or stability considerations, it is often necessary to distribute the driving torque demand among different motors in vehicle drive control. Due to the different efficiency of the electric drive system caused by different distribution ratios, it is impossible to protect the battery's allowable power by limiting the total driving torque demand before distribution. If protection is implemented after distribution, the torque distribution ratio based on economic or stability considerations is changed, and the control effect of improving economy or stability cannot be achieved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method and system for estimating and protecting the capabilities of multi-motor driven vehicle systems. This method and system are intended to solve the problem in existing technologies where the power output of the battery and the torque protection of multiple drive motors cannot be simultaneously considered during the analysis and distribution of drive torque in electric vehicles.

[0005] A first aspect of the present invention is to provide a method for capability estimation and protection control of a multi-motor driven vehicle system, the method comprising:

[0006] Calculate the allowable total power of the drive system, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system;

[0007] The driving signals currently received by the car are analyzed to calculate the total torque required for driving under the current vehicle conditions.

[0008] Based on the total torque required for driving, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, the allowable torque of the rear drive system and the maximum drive power limit of the drive system, the total torque required for the drive system is calculated, and the total mechanical power required is calculated based on the total torque required for the drive system.

[0009] Calculate the allowable power loss of the drive system based on the maximum drive power limit allowed by the battery and the total mechanical power required.

[0010] The range of values ​​for the torque distribution coefficient is calculated based on the allowable torque of the front-drive system, the allowable torque of the rear-drive system, and the allowable power loss of the drive system.

[0011] Within the range of the torque distribution coefficient, the performance objective function is calculated based on the current vehicle state to find the target distribution coefficient with optimal performance, and the output torque of the front and rear drive shafts is calculated based on the target distribution coefficient.

[0012] According to one aspect of the above technical solution, the step of calculating the allowable total power of the drive system, the total external characteristic torque of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system specifically includes:

[0013] Based on the torque external characteristic curve of the front-wheel drive system, the torque external characteristic curve of the rear-wheel drive system, and the efficiency characteristic curve, calculate the peak torque characteristic and peak power characteristic of the drive system respectively.

[0014] Based on the external torque characteristic curves of the front-wheel drive system and the rear-wheel drive system, as well as the speed ratios of the front-wheel drive axle reducer and the rear-wheel drive axle reducer, different drive torques, vehicle speeds, front-wheel drive axle distribution coefficients, and rear-wheel drive axle distribution coefficients are selected to calculate the corresponding torque-vehicle speed-distribution coefficient-electric drive system power loss characteristics.

[0015] The vehicle controller allocates the maximum allowable drive power limit of the drive system based on the maximum allowable discharge power of the battery and the power requests from the DCDC / PTC / AC / PTC issued by the battery management module.

[0016] The front drive shaft microcontroller unit calculates the maximum allowable output power limit of the front drive shaft motor and the maximum allowable drive torque of the front drive shaft motor based on the maximum allowable drive electric power of the front drive shaft allowed by the battery distribution drive system and the front electric drive status data of the front electric drive system.

[0017] The rear drive shaft microcontroller unit calculates the maximum power limit of the rear drive shaft motor and the maximum drive torque of the rear drive shaft motor that are currently allowed to be output by the rear drive shaft motor, based on the maximum drive electric power allowed by the battery distribution drive system and the rear electric drive status data of the rear electric drive system.

[0018] The voltage control unit calculates the maximum allowable drive torque of the front drive shaft system based on the maximum allowable drive torque of the front drive shaft motor, and calculates the maximum allowable drive torque of the rear drive shaft system based on the maximum allowable drive torque of the rear drive shaft motor.

[0019] The voltage control unit calculates the maximum allowable drive power of the front drive system based on the maximum allowable drive power of the drive system, the sum of the current available power of the front drive shaft motor and the available power of the rear drive shaft motor, and the smaller value of the external characteristics of the front drive shaft drive power.

[0020] According to one aspect of the above technical solution, in the step of selecting different driving torques, vehicle speeds, front-wheel drive axle distribution coefficients, and rear-wheel drive axle distribution coefficients based on the external torque characteristic curves of the front-wheel drive system, the external torque characteristic curves of the rear-wheel drive system, the speed ratios of the front-wheel drive axle reducer and the rear-wheel drive axle reducer, and calculating the corresponding torque-vehicle speed-distribution coefficient-electric drive system power loss characteristics:

[0021] Based on the efficiency characteristic curves of the front and rear drive systems, the speed ratio of the front and rear axle reducers, and by selecting different drive torques, vehicle speeds, and front and rear axle distribution coefficients, the corresponding torque-vehicle speed-distribution coefficient-electric drive system power loss characteristic MAP is calculated. The calculation formula is as follows:

[0022]

[0023] Let the front axle torque distribution coefficient k be, and the front and rear axle torques be distributed according to the following formula:

[0024]

[0025] Then we have:

[0026]

[0027] in, This is the maximum torque limit for the front axle. Torque distribution coefficient in the range of 0-1 ( (The usage ratio of the maximum torque limit of the front axle) The front axle deceleration ratio, The speed ratio of the rear axle reducer. For vehicle speed, To drive the system's required total torque, The radius of the wheel's rolling motion. The efficiency of the front-drive system is obtained by looking up a table based on the torque and speed distribution of the front axle motor. The efficiency of the rear-drive system is obtained by looking up a table based on the torque and speed distribution of the rear axle motor. This refers to the mechanical transmission efficiency of the drive shaft.

[0028] According to one aspect of the above technical solution, in the steps of the voltage control unit calculating the maximum allowable drive torque of the front drive shaft system based on the maximum allowable drive torque of the front drive shaft motor, and calculating the maximum allowable drive torque of the rear drive shaft system based on the maximum allowable drive torque of the rear drive shaft motor:

[0029] The formula for calculating the maximum permissible drive torque of the front drive axle system is as follows:

[0030]

[0031] The formula for calculating the maximum permissible drive torque of the rear drive axle system is as follows:

[0032]

[0033] In the formula, This represents the current maximum permissible drive torque for the front axle motor. This represents the maximum permissible drive torque for the rear axle motor. The front axle deceleration ratio, This refers to the speed ratio of the rear axle reducer.

[0034] According to one aspect of the above technical solution, in the step of the voltage control unit calculating the maximum allowable drive power of the front drive system based on the maximum allowable drive power of the drive system, the sum of the current available power of the front drive shaft motor and the available power of the rear drive shaft motor, and taking the smaller value of the external characteristics of the front drive shaft drive power:

[0035] The maximum allowable drive power of the front-drive system The calculation formula is:

[0036]

[0037] In the formula, This is the maximum permissible drive power limit for the drive system. This represents the current available power of the front drive shaft motor. This represents the current available power of the rear drive shaft motor. This represents the peak power of the front and rear drive motors as the external characteristic of their driving power.

[0038] According to one aspect of the above technical solution, in the step of calculating the total torque required by the drive system based on the total torque required for driving, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, the allowable torque of the rear drive system, and the maximum drive power limit of the drive system, and calculating the total mechanical power required based on the total torque required by the drive system:

[0039] The formula for calculating the total torque required by the drive system is as follows:

[0040]

[0041] In the formula, The preset efficiency of the electric drive system in converting electrical energy into mechanical energy;

[0042] The formula for calculating the total mechanical power required is:

[0043]

[0044] In the formula, To drive the system's required total torque, Current vehicle speed This is the tire's rolling radius.

[0045] According to one aspect of the above technical solution, in the step of calculating the allowable power loss of the drive system based on the maximum drive power limit of the battery-allowed drive system and the total required mechanical power:

[0046] Permissible power loss The calculation formula is:

[0047] .

[0048] According to one aspect of the above technical solution, in the step of the voltage control unit calculating the maximum allowable drive power of the front drive system based on the maximum allowable drive power of the drive system, the sum of the current available power of the front drive shaft motor and the available power of the rear drive shaft motor, and taking the smaller value of the external characteristics of the front drive shaft drive power:

[0049] Torque distribution coefficient The formula for calculating the range of values ​​is:

[0050] .

[0051] A second aspect of the present invention is to provide a capability estimation and protection control system for a multi-motor driven vehicle system, the system comprising:

[0052] The first calculation module is used to calculate the allowable total power of the drive system, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system.

[0053] The second calculation module is used to analyze the driving signals currently received by the car and calculate the total torque required for driving under the current vehicle condition.

[0054] The third calculation module is used to calculate the total torque required by the drive system based on the total torque required for driving, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, the allowable torque of the rear drive system and the maximum drive power limit of the drive system, and to calculate the total mechanical power required based on the total torque required by the drive system.

[0055] The fourth calculation module is used to calculate the allowable power loss of the drive system based on the maximum drive power limit of the battery-allowed drive system and the total mechanical power required.

[0056] The fifth calculation module is used to calculate the range of values ​​for the torque distribution coefficient based on the allowable torque of the front drive system, the allowable torque of the rear drive system, and the allowable power loss of the drive system.

[0057] The sixth calculation module is used to calculate the performance objective function based on the current vehicle state within the range of the torque distribution coefficient to find the target distribution coefficient with optimal performance, and to calculate the output torque of the front and rear drive shafts based on the target distribution coefficient.

[0058] Compared with existing technologies, the advantages of the multi-motor drive vehicle system capability estimation and protection control method and system shown in this invention are as follows:

[0059] By calculating the maximum drive power, maximum drive torque, external characteristic torque, and current maximum allowable drive power and torque for each axle (front and rear), as well as the power loss characteristics of the electric drive system under different drive demand torque-vehicle speed-distribution coefficients, the system performs the following: After the driving demand torque is parsed from the driving demand torque module, total drive system torque protection is implemented before torque distribution, and front and rear axle drive torque and total drive power protection are implemented during distribution. This achieves system capacity protection before and during distribution, eliminating the need for secondary distribution and ensuring front and rear axle torque distribution within the electric drive system's capabilities, thereby improving economy or power performance. Attached Figure Description

[0060] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0061] Figure 1 This is a flowchart illustrating the capability estimation and protection control method for a multi-motor driven vehicle system in the first embodiment of the present invention.

[0062] Figure 2 This is a schematic diagram of the peak torque external characteristic and peak power external characteristic curves of the drive system in the first embodiment of the present invention;

[0063] Figure 3 This is a schematic diagram of the power loss characteristics (MAP) of the drive system under different torque distribution coefficients in the first embodiment of the present invention.

[0064] Figure 4 This is a block diagram of the capability estimation and protection control system for a multi-motor driven vehicle system in the second embodiment of the present invention. Detailed Implementation

[0065] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0066] Example 1

[0067] Please see Figure 1 The first embodiment of the present invention provides a method for capability estimation and protection control of a multi-motor driven vehicle system, the method comprising steps S1-S6:

[0068] Step S1: Calculate the allowable total power of the drive system, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system.

[0069] Step S2: Analyze the driving signals currently received by the car and calculate the total torque required for driving under the current vehicle condition;

[0070] Step S3: Calculate the total torque required by the drive system based on the total torque required for driving, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, the allowable torque of the rear drive system and the maximum drive power limit of the drive system, and calculate the total mechanical power required based on the total torque required by the drive system.

[0071] Step S4: Calculate the allowable power loss of the drive system based on the maximum drive power limit allowed by the battery and the total mechanical power required.

[0072] Step S5: Calculate the range of values ​​for the torque distribution coefficient based on the allowable torque of the front drive system, the allowable torque of the rear drive system, and the allowable power loss of the drive system.

[0073] Step S6: Within the range of the torque distribution coefficient, calculate the performance objective function based on the current vehicle state to find the target distribution coefficient with optimal performance, and calculate the output torque of the front and rear drive shafts based on the target distribution coefficient.

[0074] In this embodiment, the steps of calculating the allowable total power of the drive system, the total external characteristic torque of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system specifically include steps S11-S17:

[0075] Step S11: Calculate the peak torque characteristic and peak power characteristic of the drive system based on the torque external characteristic curve of the front drive system, the torque external characteristic curve of the rear drive system, and the efficiency characteristic curve.

[0076] Step S12: Based on the external torque characteristic curve of the front drive system, the external torque characteristic curve of the rear drive system, the speed ratio of the front drive shaft reducer and the speed ratio of the rear drive shaft reducer, select different driving torques, vehicle speeds, front drive shaft distribution coefficients and rear drive shaft distribution coefficients, and calculate the corresponding torque-vehicle speed-distribution coefficient-electric drive system power loss characteristics.

[0077] Step S13: The vehicle controller allocates the maximum allowable drive power limit of the drive system based on the maximum allowable discharge power of the battery and the power requests of DC-DC / PTC / AC / PTC issued by the battery management module.

[0078] Step S14: The front drive shaft microcontroller unit calculates the maximum power limit of the front drive shaft motor and the maximum drive torque of the front drive shaft motor that are currently allowed to be output by the front drive shaft motor based on the maximum drive electric power allowed by the battery distribution drive system and the front electric drive status data of the front electric drive system.

[0079] Step S15: The rear drive shaft microcontroller unit calculates the maximum power limit of the rear drive shaft motor that is allowed to be output by the rear drive shaft motor and the maximum drive torque that is currently allowed to be output by the rear drive shaft motor based on the maximum drive electric power allowed by the battery distribution drive system and the rear electric drive status data of the rear electric drive system.

[0080] Step S16: The voltage control unit calculates the maximum drive torque that the front drive shaft system can currently output based on the maximum drive torque that the front drive shaft motor can currently output, and calculates the maximum drive torque that the rear drive shaft system can currently output based on the maximum drive torque that the rear drive shaft motor can currently output.

[0081] Step S17: The voltage control unit calculates the maximum allowable drive power of the front drive system based on the maximum allowable drive power of the drive system, the sum of the current available power of the front drive shaft motor and the available power of the rear drive shaft motor, and the minimum value of the external characteristics of the front drive shaft drive power.

[0082] In step S12, based on the efficiency characteristic curves of the front and rear drive systems, the speed ratio of the front and rear axle reducers, different drive torques, vehicle speeds, and front and rear axle distribution coefficients, the corresponding torque-vehicle speed-distribution coefficient-electric drive system power loss characteristic MAP is calculated. The calculation formula is as follows:

[0083]

[0084] Let the front axle torque distribution coefficient be set. The torque distribution between the front and rear axles is calculated according to the following formula:

[0085]

[0086] Then we have:

[0087]

[0088] in, This is the maximum torque limit for the front axle. Torque distribution coefficient in the range of 0-1 ( (The proportion of the maximum torque limit for the front axle) The front axle deceleration ratio, The speed ratio of the rear axle reducer. For vehicle speed, To drive the system's required total torque, The radius of the wheel's rolling motion. The efficiency of the front-drive system is obtained by looking up a table based on the torque and speed distribution of the front axle motor. The efficiency of the rear-drive system is obtained by looking up a table based on the torque and speed distribution of the rear axle motor. This refers to the mechanical transmission efficiency of the drive shaft.

[0089] In step S16, the formula for calculating the maximum allowable drive torque of the front drive axle system is as follows:

[0090]

[0091] The formula for calculating the maximum permissible drive torque of the rear drive axle system is as follows:

[0092]

[0093] In the formula, This represents the current maximum permissible drive torque for the front axle motor. This represents the maximum permissible drive torque for the rear axle motor. The front axle deceleration ratio, This refers to the speed ratio of the rear axle reducer.

[0094] In step S17, the maximum allowable drive power of the front drive system is determined. The calculation formula is:

[0095]

[0096] In the formula, This is the maximum permissible drive power limit for the drive system. This represents the current available power of the front drive shaft motor. This represents the current available power of the rear drive shaft motor. This represents the peak power of the front and rear drive motors as the external characteristic of their driving power.

[0097] Furthermore, torque distribution coefficient The formula for calculating the range of values ​​is:

[0098]

[0099] Furthermore, in step S3 of this embodiment, the formula for calculating the total torque required by the drive system is as follows:

[0100]

[0101] In the formula, The preset efficiency of the electric drive system in converting electrical energy into mechanical energy;

[0102] The formula for calculating the total mechanical power required is:

[0103]

[0104] In the formula, To drive the system's required total torque, Current vehicle speed This is the tire's rolling radius.

[0105] In step S4 of this embodiment, the allowable power loss The calculation formula is:

[0106] .

[0107] In a preferred embodiment of the present invention, the method includes steps S1-S7:

[0108] Step S1 includes steps S11-S17, specifically:

[0109] Step S11: Calculate the torque external characteristic curve and power external characteristic curve of the drive system based on the torque external characteristic curve and efficiency characteristic curve of the front and rear drive systems, respectively. Figure 2 As shown.

[0110] like Figure 2 As shown, based on this torque external characteristic curve, the peak torque currently available from the drive system can be found for each vehicle speed point. and peak power For example, at a vehicle speed of 60 kW / h, =6000 Nm, =250kW.

[0111] Step S12: Based on the efficiency characteristic curves of the front and rear drive systems, the speed ratio of the front and rear axle reducers, and by selecting different drive torques, vehicle speeds, and front and rear axle distribution coefficients, calculate the power loss characteristics of the electric drive system under different torque / vehicle speed operating points and distribution coefficients. ,like Figure 3 As shown.

[0112] The calculation formula is:

[0113] .

[0114] Step S13: The vehicle controller allocates the maximum drive power limit of the drive system based on the maximum allowable discharge power of the battery and the power requests from the DCDC / PTC / AC converters issued by the battery management module. .

[0115] For example, if the battery's maximum allowable discharge power is 200kW, and considering the reserved power of 10kW for DC-DC / PTC / AC, then the maximum drive power limit allocated to the drive system is... It is 190kW.

[0116] Step S14: The front axle motor controller (FMCU) calculates the maximum allowable drive power of the battery distribution drive system based on the value calculated in step S13. Based on the state of the front electric drive system itself, calculate the current maximum allowable output power limit of the front drive system. and the maximum permissible drive torque of the front-wheel drive system. .

[0117] For example, if the maximum drive power limit of the drive system is 190kW, and the front drive motor's allowable input power is 100kW due to overheating, then the FMCU calculates the current maximum allowable power of the front drive system. The power output is 100kW, and is determined based on the current vehicle speed and the maximum permissible power output. The maximum allowable drive torque of the motor before calculation It is 200 Nm.

[0118] Step S15, similar to step S14, involves the rear axle motor controller calculating the maximum allowable electrical power of the rear drive system as 120kW and the maximum allowable drive torque of the rear motor. It is 300 Nm.

[0119] Step S16: The vehicle controller calculates the maximum torque that the front and rear axle drive systems can provide.

[0120] The maximum torque limit that the front-wheel drive system can provide is: The maximum torque limit that the rear-wheel drive system can provide: .

[0121] Step S17: Calculate the maximum allowable drive power of the drive system.

[0122] The calculation formula is:

[0123]

[0124] Step S2, Driving demand analysis: Based on throttle opening and vehicle speed, analyze the total torque required for driving demand using a lookup table. The required mechanical power is calculated based on the total torque required for driving and the current vehicle speed. .

[0125] For example, if a driver presses the accelerator to 80% of its maximum speed at 60 km / h, the total torque required for acceleration is calculated to be 5000 Nm.

[0126] Step S3, Driving Demand Torque Limit: Based on the total driving demand torque Total torque of external characteristics of the drive system Allowable torque for front-wheel drive system Allowable torque for rear-wheel drive system Maximum drive power limit of the drive system Calculate the total torque required by the drive system.

[0127] The calculation formula is:

[0128] in, This represents the calibrable average efficiency of the electric drive system.

[0129] And based on the total torque required by the drive system Calculate the total mechanical power required by the drive system.

[0130] The calculation formula is:

[0131] .

[0132] Step S4, Battery System Power Protection: Based on the battery's maximum allowable driving power of the system. and driving requirements mechanical power Calculate the allowable power loss .

[0133] The calculation formula is:

[0134] .

[0135] Step S5, Electric drive system capacity protection (including torque protection and power protection): Based on the allowable torque of the front drive system Allowable torque for rear-wheel drive system Permissible power loss of the drive system The range of possible allocation coefficients k can be calculated.

[0136] Distribute front axle torque: ;

[0137] Distribute rear axle torque:

[0138] Drive system power loss: .

[0139] Substitute the following two formulas into the calculations performed in steps S11-S17 and S2-S4. , , ,and Calculate the distribution coefficient Optional range:

[0140]

[0141] The torque distribution coefficient is calculated based on the above formula. The range of values ​​for: .

[0142] Step S6, in torque distribution coefficient Within the range, calculate the performance objective function based on the current vehicle state. Finding the optimal allocation coefficient And calculate the front and rear axle output torque based on this distribution coefficient.

[0143] For example, a value can be selected within the range of [0.13, 0.26]. smallest The value is chosen to optimize the overall vehicle economy; for example, when the axle load ratio of the front and rear axles of the vehicle changes, an appropriate distribution coefficient can be selected within the range of [0.13, 0.26] based on the front and rear axle load ratio to enable the vehicle to achieve better acceleration performance.

[0144] In addition, it should be noted that this embodiment only describes the case of two motors in an electric vehicle. Those skilled in the art can also apply this method to the power distribution of three, four or more motors to improve economy and power.

[0145] In summary, the multi-motor drive vehicle system capability estimation and protection control method described in this invention can solve the problem of not being able to simultaneously consider the power battery's electrical output and the torque protection of multiple drive motors during drive torque analysis and distribution. Specifically, it calculates the maximum drive power allowed by the battery, the maximum drive torque of the drive system, the external characteristic torque of the drive system, the current maximum allowed drive power and drive torque of each axle (front / rear), and the power loss characteristics of the electric drive system under different drive demand torque-vehicle speed-distribution coefficients. Then, after the drive demand torque is analyzed by the drive demand torque module, total drive system torque protection is performed before torque distribution, and front and rear axle drive torque protection and total drive power protection are performed during distribution. This achieves system capability protection before and during distribution, eliminating the need for secondary distribution and ensuring that the front and rear axle torque distribution is within the capability range of the electric drive system, thereby improving economy or power.

[0146] Example 2

[0147] Please see Figure 4 The second embodiment of the present invention provides a capability estimation and protection control system for a multi-motor driven vehicle system, the system comprising: a first calculation module 10, a second calculation module 20, a third calculation module 30, a fourth calculation module 40, a fifth calculation module 50 and a sixth calculation module 60.

[0148] The first calculation module 10 is used to calculate the allowable total power of the drive system, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system.

[0149] The second calculation module 20 is used to analyze the driving signals currently received by the vehicle and calculate the total torque required for driving under the current vehicle condition.

[0150] The third calculation module 30 is used to calculate the total torque required by the drive system based on the total torque required for driving, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, the allowable torque of the rear drive system and the maximum drive power limit of the drive system, and to calculate the total mechanical power required based on the total torque required by the drive system.

[0151] The fourth calculation module 40 is used to calculate the allowable power loss of the drive system based on the maximum drive power limit of the battery-allowed drive system and the total mechanical power required.

[0152] The fifth calculation module 50 is used to calculate the range of values ​​for the torque distribution coefficient based on the allowable torque of the front drive system, the allowable torque of the rear drive system, and the allowable power loss of the drive system.

[0153] The sixth calculation module 60 is used to calculate the performance objective function based on the current vehicle state within the range of the torque distribution coefficient to find the target distribution coefficient with optimal performance, and to calculate the output torque of the front and rear drive shafts based on the target distribution coefficient.

[0154] Compared with existing technologies, the advantages of using the multi-motor drive vehicle system capability estimation and protection control system shown in this invention are as follows:

[0155] By calculating the maximum drive power, maximum drive torque, external characteristic torque, and current maximum allowable drive power and torque for each axle (front and rear), as well as the power loss characteristics of the electric drive system under different drive demand torque-vehicle speed-distribution coefficients, the system performs the following: After the driving demand torque is parsed from the driving demand torque module, total drive system torque protection is implemented before torque distribution, and front and rear axle drive torque and total drive power protection are implemented during distribution. This achieves system capacity protection before and during distribution, eliminating the need for secondary distribution and ensuring front and rear axle torque distribution within the electric drive system's capabilities, thereby improving economy or power performance.

[0156] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for capacity estimation and protective control of a multi-motor driven vehicle system, characterized in that, The method includes: Calculate the maximum allowable drive power of the drive system, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system; The driving signals currently received by the car are analyzed to calculate the total torque required for driving under the current vehicle conditions. Based on the total torque required for driving, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, the allowable torque of the rear drive system, and the maximum allowable drive power of the drive system, the total torque required for the drive system is calculated, and the total mechanical power required is calculated based on the total torque required for the drive system. Calculate the allowable power loss of the drive system based on the maximum allowable drive power of the drive system and the total mechanical power required; The range of values ​​for the torque distribution coefficient is calculated based on the allowable torque of the front-drive system, the allowable torque of the rear-drive system, and the allowable power loss of the drive system. Within the range of the torque distribution coefficient, the performance objective function is calculated based on the current vehicle state to find the target distribution coefficient with optimal performance, and the output torque of the front and rear drive shafts is calculated based on the target distribution coefficient.

2. The method for capability estimation and protection control of a multi-motor drive vehicle system according to claim 1, characterized in that, The steps for calculating the maximum allowable drive power of the drive system, the total external characteristic torque of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system specifically include: Based on the torque external characteristic curve of the front-wheel drive system, the torque external characteristic curve of the rear-wheel drive system, and the efficiency characteristic curve, calculate the peak torque characteristic and peak power characteristic of the drive system respectively. Based on the external torque characteristic curves of the front-wheel drive system and the rear-wheel drive system, as well as the speed ratios of the front-wheel drive shaft reducer and the rear-wheel drive shaft reducer, different drive torques, vehicle speeds, and torque distribution coefficients are selected to calculate the corresponding torque-vehicle speed-distribution coefficient-electric drive system power loss characteristics. The vehicle controller allocates the maximum allowable drive power of the battery system to the drive system based on the maximum allowable discharge power of the battery and the power requests from the DCDC / PTC / AC / PTC sent by the battery management module. The front drive axle microcontroller unit calculates the current available power of the front drive axle motor and the current maximum allowable drive torque of the front drive axle motor based on the maximum allowable drive power of the battery system and the front electric drive status data of the front electric drive system. The rear drive axle microcontroller unit calculates the current available power of the rear drive axle motor and the current maximum allowable drive torque of the rear drive axle motor based on the maximum allowable drive power of the battery system and the rear electric drive status data of the rear electric drive system. The voltage control unit calculates the maximum allowable drive torque of the front drive shaft system based on the maximum allowable drive torque of the front axle motor, and calculates the maximum allowable drive torque of the rear drive shaft system based on the maximum allowable drive torque of the rear axle motor. The voltage control unit calculates the maximum allowable drive power of the drive system based on the minimum of the maximum allowable drive power of the battery system, the sum of the current available power of the front drive shaft motor and the current available power of the rear drive shaft motor, and the peak power of the drive system's power external characteristic.

3. The method for capability estimation and protection control of a multi-motor drive vehicle system according to claim 2, characterized in that, In the step of selecting different drive torques, vehicle speeds, and torque distribution coefficients based on the external torque characteristic curves of the front-wheel drive system, the external torque characteristic curves of the rear-wheel drive system, the speed ratios of the front-wheel drive axle reducer and the rear-wheel drive axle reducer, and calculating the corresponding torque-vehicle speed-distribution coefficient-electric drive system power loss characteristics: Based on the efficiency characteristic curves of the front and rear drive systems, the speed ratio of the front and rear axle reducers, and by selecting different drive torques, vehicle speeds, and front and rear axle distribution coefficients, the corresponding torque-vehicle speed-distribution coefficient-electric drive system power loss characteristic MAP is calculated. The calculation formula is as follows: Let the torque distribution coefficient be defined as k. The torque distribution between the front and rear axles is calculated according to the following formula: Then we have: in, This represents the maximum allowable drive torque output of the front-drive axle system. Torque distribution coefficient in the range of 0-1 (The proportion of the maximum torque limit for the front axle) The front axle deceleration ratio, The speed ratio of the rear axle reducer. For vehicle speed, To drive the system's required total torque, The radius of the wheel's rolling motion. The efficiency of the front-drive system is obtained by looking up a table based on the torque and speed distribution of the front axle motor. The efficiency of the rear-drive system is obtained by looking up a table based on the torque and speed distribution of the rear axle motor. This refers to the mechanical transmission efficiency of the drive shaft.

4. The method for capability estimation and protection control of a multi-motor drive vehicle system according to claim 2, characterized in that, In the steps of the voltage control unit calculating the maximum allowable drive torque of the front drive shaft system based on the maximum allowable drive torque of the front axle motor, and calculating the maximum allowable drive torque of the rear drive shaft system based on the maximum allowable drive torque of the rear axle motor: The formula for calculating the maximum permissible drive torque of the front drive axle system is as follows: The formula for calculating the maximum permissible drive torque of the rear drive axle system is as follows: In the formula, This represents the current maximum permissible drive torque for the front axle motor. This represents the maximum permissible drive torque for the rear axle motor. The front axle deceleration ratio, This refers to the speed ratio of the rear axle reducer.

5. The method for capability estimation and protection control of a multi-motor drive vehicle system according to claim 2, characterized in that, In the step of calculating the maximum allowable drive power of the drive system based on the battery system's maximum allowable drive power, the sum of the current available power of the front drive shaft motor and the current available power of the rear drive shaft motor, and the smaller of the peak power of the drive system's power external characteristics: The drive system allows a maximum drive power. The calculation formula is: In the formula, For the maximum allowable drive power of the battery system, This represents the current available power of the front drive shaft motor. This represents the current available power of the rear drive shaft motor. This refers to the peak power of the drive system's power external characteristics.

6. The method for capability estimation and protection control of a multi-motor drive vehicle system according to claim 1, characterized in that, In the steps of calculating the total torque required by the drive system based on the total torque required for driving, the total torque of the external characteristics of the drive system, the allowable torque of the front-wheel drive system, the allowable torque of the rear-wheel drive system, and the maximum drive power limit of the drive system, and calculating the total mechanical power required based on the total torque required by the drive system: The formula for calculating the total torque required by the drive system is as follows: In the formula, The preset efficiency of the electric drive system in converting electrical energy into mechanical energy; The formula for calculating the total mechanical power required is: In the formula, To drive the system's required total torque, Current vehicle speed This is the tire's rolling radius.

7. The method for capability estimation and protection control of a multi-motor drive vehicle system according to claim 1, characterized in that, In the step of calculating the allowable power loss of the drive system based on the maximum allowable drive power of the drive system and the total required mechanical power: Permissible power loss of the drive system The calculation formula is: 。 8. The method for capability estimation and protection control of a multi-motor drive vehicle system according to claim 3, characterized in that: Torque distribution coefficient The formula for calculating the range of values ​​is: In the formula, Tr is the rear axle distributed torque, Tr_Lmt is the maximum allowable drive torque of the rear drive axle system, P_Loss is the power loss of the electric drive system, and P_lossLmt is the allowable power loss of the drive system.

9. A capability estimation and protection control system for a multi-motor driven vehicle system, characterized in that, The system includes: The first calculation module is used to calculate the maximum allowable driving power of the drive system, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, and the allowable torque of the rear drive system. The second calculation module is used to analyze the driving signals currently received by the car and calculate the total torque required for driving under the current vehicle condition. The third calculation module is used to calculate the total torque required by the drive system based on the total torque required for driving, the total torque of the external characteristics of the drive system, the allowable torque of the front drive system, the allowable torque of the rear drive system and the maximum drive power limit of the drive system, and to calculate the total mechanical power required based on the total torque required by the drive system. The fourth calculation module is used to calculate the allowable power loss of the drive system based on the maximum allowable drive power of the drive system and the total mechanical power required. The fifth calculation module is used to calculate the range of values ​​for the torque distribution coefficient based on the allowable torque of the front drive system, the allowable torque of the rear drive system, and the allowable power loss of the drive system. The sixth calculation module is used to calculate the performance objective function based on the current vehicle state within the range of the torque distribution coefficient to find the target distribution coefficient with optimal performance, and to calculate the output torque of the front and rear drive shafts based on the target distribution coefficient.

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