A motor control method, readable storage medium and vehicle

Abstract

The application provides a motor control method, a readable storage medium and a vehicle, and applies to the technical field of vehicle control. The method comprises the following steps: in the case that the vehicle is in a direct drive mode and a braking working condition, if a first torque deviation between an actual driving torque of an engine and a target driving torque exceeds a torque compensation boundary, determining a compensation torque of a front axle motor according to the torque compensation boundary, determining a front axle target torque required to be output by the front axle motor according to the compensation torque, and determining a rear axle target torque required to be output by a rear axle motor according to the front axle target torque and an allowed recovery torque of a power battery at present. The motor control method provided by the application can limit the compensation torque of the front axle motor for the engine within a smaller range through the torque compensation boundary, so that the fluctuation of the actual braking torque can be reduced, the fluctuation of the vehicle deceleration can be reduced, and the stability of the vehicle can be improved.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and more specifically, to a motor control method, a readable storage medium, and a vehicle within the field of vehicle control technology. Background Technology

[0002] Currently, some hybrid vehicles adopt a series-parallel hybrid architecture, equipped with a P2 motor, a P4 motor, and an engine. These vehicles offer multiple driving modes, including series mode, direct drive mode, and series-parallel mode. In direct drive mode, the engine directly drives the vehicle, with the P2 and P4 motors providing assistance. When in direct drive mode, the deceleration of these vehicles may fluctuate during braking, resulting in relatively poor vehicle stability. Summary of the Invention

[0003] This application provides a motor control method, a readable storage medium, and a vehicle, which can reduce the risk of vehicle stalling.

[0004] In a first aspect, a motor control method is provided, wherein the vehicle includes an engine, a power battery, a front axle motor, and a rear axle motor, the method comprising: When the vehicle is in direct drive mode and braking condition, if the first torque deviation between the current actual driving torque of the engine and the target driving torque exceeds the torque compensation boundary, the compensation torque that the front axle motor needs to output for the engine is determined according to the torque compensation boundary. Based on the compensation torque and the base braking torque allocated to the front axle motor, determine the target front axle torque that the front axle motor needs to output; The target torque to be output by the rear axle motor is determined based on the target torque of the front axle and the current allowable regeneration torque of the power battery. The front axle motor is controlled according to the target torque of the front axle, and the rear axle motor is controlled according to the target torque of the rear axle.

[0005] In this embodiment, when the vehicle is in direct drive mode and braking condition, if the first torque deviation between the engine's current actual driving torque and the target driving torque exceeds the torque compensation boundary, the compensation torque that the front axle motor needs to output to the engine is determined based on the torque compensation boundary. Based on the compensation torque and the base braking torque allocated to the front axle motor, the target front axle torque that the front axle motor needs to output is determined. Based on the target front axle torque and the current allowable regenerative braking torque of the power battery, the target rear axle torque that the rear axle motor needs to output is determined. The front axle motor is controlled based on the target front axle torque, and the rear axle motor is controlled based on the target rear axle torque. By limiting the compensation torque output by the front axle motor to the engine through the torque compensation boundary, the compensation torque output by the front axle motor to the engine can be limited to a small range. When the compensation torque output by the front axle motor to the engine is small, the deviation between the target front axle torque and the actual front axle torque, as well as the deviation between the target rear axle torque and the actual rear axle torque, can be reduced. This reduces the deviation between the vehicle's actual braking torque and the target braking torque, thereby reducing the fluctuation of the actual braking torque, reducing the fluctuation of vehicle deceleration, and improving vehicle stability.

[0006] Optionally, before determining the compensation torque that the front axle motor needs to output to the engine based on the torque compensation boundary if the first torque deviation between the engine's current actual driving torque and the target driving torque exceeds the torque compensation boundary, the method further includes: determining the vehicle's current speed; and determining the torque compensation boundary based on the engine's wheel-end torque at the current vehicle speed.

[0007] In this embodiment, before determining whether the first torque deviation exceeds the torque compensation boundary, the wheel-end torque of the engine at the current vehicle speed is determined, and the torque compensation boundary is determined based on the wheel-end torque. This allows the torque compensation boundary to be matched with the vehicle speed, ensuring that the limitation on the compensation torque is matched with the vehicle speed when limiting the compensation torque according to the torque compensation boundary, thereby improving the vehicle's stability at different speeds.

[0008] Optionally, determining the torque compensation boundary based on the wheel-end torque of the engine at the current vehicle speed includes: determining a proportionality coefficient corresponding to the recovery capacity value of the power battery, wherein the recovery capacity value is positively correlated with the proportionality coefficient; and determining the torque compensation boundary based on the product of the wheel-end torque and the proportionality coefficient.

[0009] In this embodiment, when the battery's power recovery capability is large, a larger proportional coefficient can be selected to adjust the wheel-end torque to obtain the torque compensation boundary. This allows for the use of a larger torque compensation boundary when the power battery's power recovery capability is large, enabling the front axle motor to provide greater compensation for the engine's torque, thereby ensuring the vehicle's braking force and, consequently, its braking efficiency.

[0010] Optionally, the step of determining the compensation torque that the front axle motor needs to output for the engine if the first torque deviation between the current actual driving torque of the engine and the target driving torque exceeds the torque compensation boundary includes: if the recovery capacity value of the power battery is less than a preset preset capacity threshold, then determining the compensation torque according to the torque compensation boundary when the first torque deviation exceeds the torque compensation boundary; or, if the recovery capacity value is less than the preset capacity threshold, then determining the compensation torque according to the first torque deviation when the first torque deviation does not exceed the torque compensation boundary; or, if the recovery capacity value is greater than or equal to the preset capacity threshold, then determining the compensation torque according to the first torque deviation.

[0011] In this embodiment of the application, when the recovery capacity of the power battery is less than the preset capacity threshold, the compensation torque is determined according to the torque compensation boundary, which can reduce the fluctuation of the actual braking torque, thereby reducing the fluctuation of vehicle deceleration and improving vehicle stability.

[0012] Optionally, determining the compensation torque based on the torque compensation boundary when the first torque deviation exceeds the torque compensation boundary includes: determining the target braking torque currently required by the vehicle when the first torque deviation exceeds the torque compensation boundary; and determining the compensation torque based on the torque compensation boundary when the target braking torque is greater than or equal to a preset braking torque threshold.

[0013] In this embodiment, when the target braking torque of the vehicle is greater than or equal to a preset braking torque threshold, it is determined that the target braking torque of the vehicle is large. The compensation torque is determined according to the torque compensation boundary, which can reduce the fluctuation of deceleration when the vehicle deceleration is large, thereby improving the stability of the vehicle.

[0014] Optionally, determining the compensation torque based on the torque compensation boundary includes: if the target braking torque currently required by the vehicle is less than the allowable regenerative torque, determining a second torque deviation between the target braking torque and the allowable regenerative torque; if the second torque deviation is less than the first torque deviation, determining the compensation torque based on the torque compensation boundary; and if the second torque deviation is greater than or equal to the first torque deviation, determining the compensation torque based on the first torque deviation.

[0015] In this embodiment, during the process of determining the compensation torque based on the torque compensation boundary, when the target braking torque is less than the allowable regenerative torque and the second torque deviation between the target braking torque and the allowable regenerative torque is less than the first torque deviation, the compensation torque is determined based on the torque compensation boundary. When the second torque compensation boundary is greater than or equal to the first torque compensation boundary, the compensation torque is determined based on the first torque deviation. This allows for the determination of the compensation torque based on the torque compensation boundary when the front axle motor is taking a share of the regenerative torque from the rear axle motor, thereby reducing fluctuations in the vehicle's actual braking torque and deceleration. Conversely, when the front axle motor does not take a share of the regenerative torque from the rear axle motor, determining the compensation torque based on the first torque deviation ensures torque compensation from the engine by the front axle motor, thus improving the vehicle's braking efficiency.

[0016] Optionally, determining the compensation torque based on the torque compensation boundary when the second torque deviation is less than the first torque deviation includes: determining a third torque deviation between the second torque deviation and the first torque deviation when the second torque deviation is less than the first torque deviation; and determining the compensation torque based on the torque compensation boundary when the third torque deviation is greater than a preset deviation threshold.

[0017] In this embodiment of the application, when the third torque deviation is greater than the preset deviation threshold, the compensation torque is determined according to the torque compensation boundary. When the front axle motor has a large share of the regenerative torque of the rear axle motor, the compensation torque is determined according to the torque compensation boundary, and the compensation torque is limited to a small range. This limits the front axle motor's share of the regenerative torque of the rear axle motor, thereby reducing the fluctuation of the vehicle's actual braking torque and deceleration, and improving the vehicle's stability.

[0018] Optionally, determining the compensation torque based on the first torque deviation when the second torque deviation is greater than or equal to the first torque deviation includes: If the second torque deviation is greater than or equal to the first torque deviation, determine whether the vehicle is on a downhill road. If the vehicle is on a downhill road, the compensation torque is determined according to the torque compensation boundary; If the vehicle is not on a downhill road, the compensation torque is determined based on the first torque deviation.

[0019] In this embodiment, when the front axle motor takes up a share of the regenerative torque from the rear axle motor, a compensation torque can be determined based on the torque compensation boundary to reduce fluctuations in the vehicle's actual braking torque and deceleration. When the front axle motor does not take up a share of the regenerative torque from the rear axle motor, a compensation torque can be determined based on the first torque deviation to ensure torque compensation from the engine by the front axle motor, thereby improving the vehicle's braking efficiency.

[0020] In a second aspect, a controller is provided, disposed in a vehicle, the vehicle including an engine, a power battery, a front axle motor, and a rear axle motor, the controller comprising: The determination module is configured to, when the vehicle is in direct drive mode and braking condition, determine the compensation torque that the front axle motor needs to output for the engine based on the torque compensation boundary if the first torque deviation between the current actual driving torque of the engine and the target driving torque exceeds the torque compensation boundary; determine the front axle target torque that the front axle motor needs to output based on the compensation torque and the base braking torque allocated to the front axle motor; and determine the rear axle target torque that the rear axle motor needs to output based on the front axle target torque and the current allowable regenerative torque of the power battery. A control module is used to control the front axle motor according to the target torque of the front axle, and to control the rear axle motor according to the target torque of the rear axle.

[0021] Thirdly, a vehicle is provided, the vehicle comprising: Memory, used to store executable program code; A processor is configured to call and run the executable program code from the memory, causing the vehicle to perform the method in any possible implementation of the first aspect described above.

[0022] Fourthly, a program product is provided, comprising: executable program code, which, when run on a vehicle, causes the vehicle to perform the method in any possible implementation of the first aspect described above.

[0023] Fifthly, a readable storage medium is provided that stores executable program code, which, when run on a vehicle, causes the vehicle to perform the method in any possible implementation of the first aspect described above. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the steps of a motor control method provided in an embodiment of this application; Figure 2 This is a schematic flowchart of a motor control method provided in an embodiment of this application; Figure 3 This is a schematic flowchart of another motor control method provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a controller provided in an embodiment of this application; Figure 5 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0025] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0026] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0027] Currently, some hybrid vehicles adopt a series-parallel hybrid architecture, equipped with a P2 motor, a P4 motor, and an engine. The engine and the P2 motor are located on the front axle of the vehicle and are used to drive the front wheels of the vehicle. The P2 motor is also called the front axle motor or front axle motor. The P4 motor is located on the rear axle of the vehicle and is used to drive the rear wheels of the vehicle. The P4 motor is also called the rear axle motor or rear axle motor.

[0028] These vehicles offer multiple power modes, including series drive, direct drive, and hybrid drive. In direct drive mode, the engine drives the vehicle, with P2 and P4 motors acting as auxiliary motors. The P2 motor compensates for the engine's torque, addressing its slow torque response. The P2 and P4 motors also provide braking torque during braking, simultaneously charging the vehicle's battery.

[0029] In direct-drive mode, the torque calculation methods for motors P2 and P4 after braking are as follows: First, determine the required braking torque (hereinafter referred to as the target braking torque) and the total recyclable torque of the power battery (hereinafter referred to as the allowable recyclable torque). Distribute the target braking torque to the front and rear axles of the vehicle in a certain proportion. The torque allocated to the front axle is called the front axle braking torque, and the torque allocated to the rear axle is called the rear axle braking torque. Then, for motor P2, based on the front axle braking torque and the engine's target drive torque, determine the base braking torque of motor P2 and the compensation torque that motor P2 needs to output to the engine. Summing the base braking torque and the compensation torque yields the total torque that motor P2 needs to output (hereinafter referred to as the front axle target torque).

[0030] Next, for the P4 motor, when the deviation between the allowable regenerative torque and the front axle target torque is greater than or equal to the rear axle braking torque, the total torque that the P4 motor needs to output (hereinafter referred to as the rear axle target torque) is determined to be equal to the rear axle braking torque. When the deviation between the allowable regenerative torque and the front axle target torque is less than the rear axle braking torque, the rear axle target torque is determined to be equal to the difference between the allowable regenerative torque and the front axle target torque. Wherein, when the deviation between the allowable regenerative torque and the front axle target torque is less than the rear axle braking torque, the rear axle braking torque is provided jointly by the P4 motor and the vehicle's braking system.

[0031] For example, the target torque for the front axle can be expressed as: A - B + (BC), where A is the front axle braking torque, B is the engine's target drive torque, AB is the basic braking torque of the P2 motor, C is the engine's actual drive torque, and BC is the engine's torque deviation, which is the compensation torque that the P2 motor needs to output from the engine. When the deviation between the allowable regenerative braking torque and the target torque for the front axle is less than the rear axle braking torque, the target torque for the rear axle can be expressed as: EF, where E is the allowable regenerative braking torque and F is the target torque for the front axle. When the deviation between the allowable regenerative braking torque and the target torque for the front axle is greater than or equal to the rear axle braking torque, the target torque for the rear axle is equal to the rear axle braking torque.

[0032] The torques mentioned above are vectors. For example, if the target braking torque is -200 Nm, the engine's current actual driving torque is +80 Nm, the target driving torque is +20 Nm, and the allowable regenerative braking torque is -240 Nm, then the target braking torque of -200 Nm is distributed to the front and rear axles at a 50% ratio. The front axle braking torque is -100 Nm, and the rear axle braking torque is also -100 Nm. For the P2 motor, the target torque for the front axle is -100 - (+20) + (+20 - (+80)) = -180 Nm. For the P4 motor, the deviation between the allowable regenerative braking torque of -240 Nm and the target torque for the front axle of -180 Nm is -60 Nm, which is less than the rear axle braking torque of -100 Nm. Therefore, the target torque for the rear axle is -60 Nm. Conversely, if the deviation between the regenerative braking torque and the target torque for the front axle is greater than or equal to the rear axle braking torque of -100 Nm, then the target torque for the rear axle is -100 Nm.

[0033] It can be seen that when the vehicle is in direct drive mode and braking condition, the target drive torque and actual drive torque of the engine, as well as the target torque of the front axle and the target torque of the rear axle, are closely related. The target torque of the front axle is determined based on the target drive torque and actual drive torque of the engine, and the target torque of the rear axle is determined based on the target torque of the front axle.

[0034] In actual control, the torque responses of the engine, P2 motor, and P4 motor are not synchronized. The motor torque response is fast, while the engine torque response is slow. The response speed refers to the time it takes for the actual torque to reach the target torque. For example, at time N, the engine's target torque is 20 Nm, the P2 motor's target torque is -120 Nm, and the P4 motor's target torque is -100 Nm; the front axle target torque is -100 Nm, and the rear axle target torque is -100 Nm. After time N+1, the engine's target torque is 20 Nm, and the actual torque is 80 Nm; the P2 motor's target torque is -180 Nm, and the actual torque is -120 Nm; the P4 motor's target torque is -60 Nm, and the actual torque is -100 Nm. Therefore, the rear axle target torque becomes the P4 motor's target torque of -60 Nm, and the front axle target torque becomes the target braking torque of -200 Nm - (rear axle target torque -60 Nm) = -140 Nm. At time N+2, since the target torque of the front axle changed from -100Nm to -140Nm, the target torque of the engine also changed to 10Nm (the engine's target torque changes with the target torque of the front axle, generally increasing and decreasing simultaneously). However, the actual torque of the engine has dropped to 30Nm, so the engine's torque deviation becomes 10Nm - 30Nm = -20Nm; the target torque of the P2 motor becomes -140Nm - 10Nm + (-20Nm) = -170Nm, and the actual torque is -180Nm. The target torque of the P4 motor becomes -240Nm - (-170Nm) = -70Nm, while the actual torque is -60Nm; the target torque of the rear axle becomes the target torque of the P4 motor -70Nm, and the target torque of the front axle becomes the target braking torque -200Nm - (-70Nm) = -130Nm. In other words, the target torque of the P4 motor is affected by the battery recovery capability (i.e., the allowable recovery torque) and the target torque of the P2 motor, while the target torque of the front axle is affected by the target torque of the rear axle (i.e., the target torque of the P4 motor), and the target torque of the engine is affected by the target torque of the front axle. The target torque of the P2 motor is further affected by the front axle target torque / the engine target torque / the engine's actual torque, resulting in a closed-loop, mutually influencing situation. Moreover, the above example does not include the signal transmission delay and the differences in the actual responses of the P2 motor, P4 motor, and engine.

[0035] In simple terms, due to asynchronous torque responses, the front axle target torque output by motor P2 at time M, after time N, will only reach the actual driving torque of +80Nm and the target driving torque of +20Nm, corresponding to -180Nm. Similarly, the rear axle target torque output by motor P4 at time T, after time M, will only reach the front axle target torque of -180Nm, corresponding to -60Nm. That is, at time N, the actual torque output by motor P2 (hereinafter referred to as the actual front axle torque) will deviate from the front axle target torque of -180Nm, and the actual torque output by motor P4 (hereinafter referred to as the actual rear axle torque) will deviate from the rear axle target torque of -60Nm. Ultimately, this results in a deviation between the actual braking torque experienced by the vehicle at time N (hereinafter referred to as the actual braking torque) and the target braking torque of -200Nm. This situation occurs periodically during vehicle braking, causing the actual braking torque to fluctuate around the target braking torque, which in turn causes fluctuations in deceleration.

[0036] When the vehicle is braking, the torque output by motors P2 and P4 is used to charge the battery. Therefore, the sum of the target torque for the front axle and the target torque for the rear axle must not exceed the allowable regenerative torque. The allowable regenerative torque needs to be allocated between motors P2 and P4. When the allowable regenerative torque is sufficiently large, the target torques for the front and rear axles can be set arbitrarily, and each motor can be allocated a certain share of the regenerative torque. However, when the allowable regenerative torque is relatively small, it is necessary to control the sum of the target torques for the front and rear axles to not exceed the allowable regenerative torque, and priority must be given to the P2 motor. In this case, the P2 motor may take away a share of the regenerative torque from the P4 motor.

[0037] As mentioned above, the target torque of the front axle equals the sum of the base braking torque and the compensation torque. When the deviation between the allowable regenerative torque and the target torque of the front axle is greater than or equal to the braking torque of the rear axle, the target torque of the rear axle is equal to the braking torque of the rear axle. Conversely, when the deviation between the allowable regenerative torque and the target torque of the front axle is less than the braking torque of the rear axle, the target torque of the rear axle is equal to the difference between the allowable regenerative torque and the target torque of the front axle. Therefore, the P2 motor's encroachment on the P4 motor's share of regenerative torque primarily stems from the compensation torque; the larger the compensation torque, the greater the extent to which the P2 motor encroaches on the P4 motor's share of regenerative torque.

[0038] In reality, after a vehicle enters braking mode, the actual driving torque output by the engine gradually decreases, and the torque deviation between the actual driving torque and the target driving torque also gradually decreases. Therefore, the compensation torque output by the P2 motor to the engine also gradually decreases. During this process, if the P2 motor takes away a share of the regenerative torque from the P4 motor, the extent to which the P2 motor takes away a share of the regenerative torque from the P4 motor will gradually decrease. The larger the compensation torque, the greater the decrease in the extent to which the P2 motor takes away a share of the regenerative torque from the P4 motor.

[0039] Because the torque responses of the P2 and P4 motors are asynchronous, the greater the reduction in the share of regenerative torque that the P2 motor takes from the P4 motor, the greater the deviation between the actual torque on the rear axle from the target torque, and consequently, the greater the deviation between the target braking torque and the actual braking torque. Furthermore, after the P2 motor takes a share of the P4 motor's regenerative torque, the braking system may be introduced to provide braking torque to the rear axle. The asynchronous torque response of the braking system with the P2 and P4 motors will further increase the deviation between the target braking torque and the actual braking torque, thus increasing the fluctuation of the actual braking torque. In short, the greater the compensation torque output by the P2 motor to the engine, the greater the fluctuation of the vehicle's actual braking torque, the greater the fluctuation of deceleration, and the worse the vehicle's stability.

[0040] To address the aforementioned issues, this application provides a motor control method. The method involves limiting the compensation torque output by motor P2 to the engine within a smaller range during the calculation of the target torque for the front axle when the vehicle is in direct drive mode and braking condition. When the compensation torque output by motor P2 to the engine is smaller, the deviation between the target torque and the actual torque of the front axle decreases, as does the deviation between the target torque and the actual torque of the rear axle. This reduces the deviation between the actual braking torque and the target braking torque, thereby reducing fluctuations in the actual braking torque and consequently reducing vehicle deceleration fluctuations, thus improving vehicle stability.

[0041] The method provided in this application can be executed by a controller in a vehicle, such as a vehicle control unit (VCU). The vehicle control unit is connected to an engine control unit (ECU) in the vehicle for controlling the engine, and also to a motor controller in the vehicle for controlling the P2 motor and a motor controller in the vehicle for controlling the P4 motor.

[0042] See Figure 1 , Figure 1 This is a flowchart illustrating the steps of a motor control method provided in an embodiment of this application. Figure 1 As shown, the method may include the following steps: Step 101: When the vehicle is in direct drive mode and braking condition, if the first torque deviation between the engine's current actual driving torque and the target driving torque exceeds the torque compensation boundary, then determine the compensation torque that the front axle motor needs to output for the engine based on the torque compensation boundary.

[0043] Here, the engine's target drive torque refers to the torque that the engine needs to output based on the vehicle's condition, while the actual drive torque refers to the actual drive torque output by the engine. The compensation torque that the front axle motor needs to provide to the engine is the torque output by the front axle motor to compensate for the deviation between the engine's actual drive torque and the target drive torque.

[0044] In this embodiment, during vehicle operation, after the vehicle is switched to direct drive mode, the vehicle controller can monitor whether the brake pedal is depressed. When the brake pedal is depressed, it determines that the vehicle has entered braking mode. Upon determining that the vehicle has switched to direct drive mode and entered braking mode, the vehicle controller can periodically obtain the actual drive torque output by the engine from the engine control unit. Simultaneously, it determines the target drive torque that the engine needs to output based on the vehicle's state, and then calculates the engine torque deviation (hereinafter referred to as the first torque deviation) based on the actual drive torque and the target drive torque.

[0045] For example, at a certain moment, when the vehicle is in direct drive mode and the brake pedal is detected to be depressed, the vehicle controller can determine the target braking torque required by the vehicle based on the brake pedal opening, and simultaneously determine the target drive torque that the engine needs to output. The target braking torque might be -200 Nm, and the target drive torque might be +20 Nm. At the same time, the vehicle controller can obtain the engine's actual drive torque at the current moment from the engine control unit. The actual drive torque might be +80 Nm, and the first torque deviation between the target drive torque and the actual drive torque can be calculated as (+20 Nm - (+80 Nm)) = -60 Nm.

[0046] In one implementation, a torque compensation boundary can be pre-calibrated experimentally. This torque compensation boundary is a scalar. When determining whether a first torque deviation exceeds the torque compensation boundary, the absolute value of the first torque deviation can be compared with the torque compensation boundary. If the absolute value of the first torque deviation is greater than the torque compensation boundary, it is determined that the first torque deviation exceeds the torque compensation boundary; conversely, if the absolute value of the first torque deviation is less than or equal to the torque compensation boundary, it is determined that the first torque deviation does not exceed the torque compensation boundary. For example, the torque compensation boundary can be pre-calibrated to 20 Nm. When the first torque deviation is -60 Nm, it can be determined that the first torque deviation exceeds the torque compensation boundary; when the first torque deviation is 15 Nm, it can be determined that the first torque deviation does not exceed the torque compensation boundary.

[0047] When it is determined that the first torque deviation exceeds the torque compensation boundary, the torque compensation boundary can be directly used as the compensation torque, and the direction of the compensation torque should be the same as that of the first torque deviation. For example, when the torque compensation boundary is 20 Nm and the first torque deviation is -60 Nm, the absolute value of the first torque deviation is greater than the torque compensation boundary, so the compensation torque can be determined to be -20 Nm. Conversely, when it is determined that the first torque deviation does not exceed the torque compensation boundary, the first torque deviation can be directly used as the compensation torque. For example, when the torque compensation boundary is 20 Nm and the first torque deviation is -10 Nm, the absolute value of the first torque deviation is less than or equal to the torque compensation boundary, so the compensation torque can be determined to be -10 Nm.

[0048] In another implementation, two torque compensation boundaries can be pre-calibrated experimentally. These two boundaries are vectors; one boundary (hereinafter referred to as the first torque compensation boundary) is in the opposite direction to the braking torque, and the other boundary (hereinafter referred to as the second torque compensation boundary) is in the same direction as the braking torque. When determining whether the first torque deviation exceeds the torque compensation boundary, if the first torque deviation is in the opposite direction to the braking torque, the absolute value of the first torque deviation is compared with the absolute value of the first torque compensation boundary. If the absolute value of the first torque deviation is greater than the absolute value of the first torque compensation boundary, the first torque deviation is determined to exceed the torque compensation boundary; conversely, if the absolute value of the first torque deviation is less than or equal to the absolute value of the first torque compensation boundary, the first torque deviation is determined not to exceed the torque compensation boundary.

[0049] Furthermore, when the first torque deviation is in the same direction as the braking torque, the absolute value of the first torque deviation is compared with the absolute value of the second torque compensation boundary. If the absolute value of the first torque deviation is greater than the absolute value of the second torque compensation boundary, it is determined that the first torque deviation exceeds the torque compensation boundary. Conversely, if the second torque deviation is less than or equal to the torque compensation boundary, it is determined that the first torque deviation does not exceed the torque compensation boundary.

[0050] For example, a first torque compensation boundary of 20 Nm and a second torque compensation boundary of -20 Nm can be pre-calibrated. When the first torque deviation is -60 Nm, comparing the absolute value of the first torque deviation of -60 Nm with the absolute value of the second torque compensation boundary of -20 Nm, it can be determined that the absolute value of the first torque deviation of -60 Nm is greater than the absolute value of the second torque compensation boundary of -20 Nm, thus determining the compensation torque as -20 Nm. When the first torque deviation is 15 Nm, comparing the absolute value of the first torque deviation of 15 Nm with the absolute value of the first torque compensation boundary of 20 Nm, it can be determined that the absolute value of the first torque deviation of 15 Nm is less than the absolute value of the second torque compensation boundary of 20 Nm, thus determining the compensation torque as 15 Nm.

[0051] It should be noted that the torque compensation boundary is a small torque value used to limit the compensation torque output by the front axle motor to the engine, thus confining the compensation torque to a small range. When the compensation torque is confined to a small range, the deviation between the target torque and the actual torque of the front axle can be reduced, as can the deviation between the target torque and the actual torque of the rear axle.

[0052] Step 102: Determine the target front axle torque that the front axle motor needs to output based on the compensation torque and the base braking torque allocated to the front axle motor.

[0053] Step 103: Determine the target torque that the rear axle motor needs to output based on the target torque of the front axle and the current allowable regeneration torque of the power battery.

[0054] The base braking torque allocated to the front axle motor consists of two parts: one part is the front axle braking torque output by the front axle motor, and the other part is used to counteract the target driving torque of the engine. The target torque of the front axle is the total torque that the front axle motor needs to output at the current moment.

[0055] In this embodiment, after determining that the vehicle has entered braking condition, the vehicle controller can determine the target braking torque, and based on the target braking torque, determine the front axle braking torque, and based on the vehicle status, determine the target drive torque of the engine, and determine the base braking torque based on the front axle braking torque and the target drive torque. For example, when the target braking torque is determined to be -200Nm, it can be allocated to the front and rear axles at a ratio of 50%, with the front axle braking torque being -100Nm and the rear axle braking torque being -100Nm. If the target drive torque obtained by the vehicle controller from the engine control unit is +20Nm, then the base braking torque can be determined to be -100Nm - (+20Nm) = -120Nm.

[0056] After determining the base braking torque, the compensation torque and the base braking torque can be summed, and the summed result can be used as the target torque that the front axle motor needs to output. For example, if the compensation torque is determined to be -20 Nm and the base braking torque is -120 Nm, the target torque of the front axle can be determined to be -140 Nm.

[0057] Furthermore, after determining the target torque on the front axle, the torque deviation between the allowable regenerative braking torque of the power battery and the target torque on the front axle can be calculated. If this torque deviation is less than the rear axle braking torque, the target torque on the rear axle is determined to be equal to this torque deviation. If this torque deviation is greater than or equal to the rear axle braking torque, the target torque on the rear axle is determined to be the rear axle braking torque. For example, when the allowable regenerative braking torque is -200 Nm and the target torque on the front axle is -140 Nm, the torque deviation between the allowable regenerative braking torque and the target torque on the front axle can be determined to be -60 Nm. This torque deviation is less than the rear axle braking torque of -100 Nm, therefore the target torque on the rear axle can be determined to be -60 Nm. As another example, when the allowable regenerative braking torque is -300 Nm and the target torque on the front axle is -140 Nm, the torque deviation between the allowable regenerative braking torque and the target torque on the front axle can be determined to be -160 Nm. This torque deviation is greater than the rear axle braking torque of -100 Nm, therefore the target torque on the rear axle can be determined to be -100 Nm.

[0058] Step 104: Control the front axle motor according to the target torque of the front axle, and control the rear axle motor according to the target torque of the rear axle.

[0059] In this embodiment, after determining the target torque for the front axle and the target torque for the rear axle, the vehicle controller can control the front axle motor to output the target torque based on the front axle target torque, and the rear axle motor to output the target torque based on the rear axle target torque. Specifically, after determining the target torque for the front axle, the vehicle controller can send the target torque to the motor controller of the front axle motor, which then controls the operation of the front axle motor based on the target torque. After determining the target torque for the rear axle, the vehicle controller can send the target torque to the motor controller of the rear axle motor, which then controls the operation of the rear axle motor based on the target torque.

[0060] Specifically, when the target torque of the rear axle is less than the braking torque of the rear axle, the braking system can be controlled to output a portion of the braking torque, and the sum of the braking torque output by the braking system and the target torque of the rear axle is equal to the braking torque of the rear axle.

[0061] It should be noted that when the vehicle is in direct drive mode, after the vehicle enters braking condition, the vehicle controller periodically executes steps 101-104 until the vehicle exits braking condition.

[0062] In this embodiment, when the vehicle is in direct drive mode and braking condition, if the first torque deviation between the engine's current actual driving torque and the target driving torque exceeds the torque compensation boundary, the compensation torque that the front axle motor needs to output to the engine is determined based on the torque compensation boundary. Based on the compensation torque and the base braking torque allocated to the front axle motor, the target front axle torque that the front axle motor needs to output is determined. Based on the target front axle torque and the current allowable regenerative braking torque of the power battery, the target rear axle torque that the rear axle motor needs to output is determined. The front axle motor is controlled based on the target front axle torque, and the rear axle motor is controlled based on the target rear axle torque. By limiting the compensation torque output by the front axle motor to the engine through the torque compensation boundary, the compensation torque output by the front axle motor to the engine can be limited to a small range. When the compensation torque output by the front axle motor to the engine is small, the deviation between the target front axle torque and the actual front axle torque, as well as the deviation between the target rear axle torque and the actual rear axle torque, can be reduced. This reduces the deviation between the vehicle's actual braking torque and the target braking torque, thereby reducing the fluctuation of the actual braking torque, reducing the fluctuation of vehicle deceleration, and improving vehicle stability.

[0063] Optionally, before determining the compensation torque that the front axle motor needs to output to the engine based on the torque compensation boundary if the first torque deviation between the engine's current actual driving torque and the target driving torque exceeds the torque compensation boundary, the method may further include: Determine the vehicle's current speed; The torque compensation boundary is determined based on the wheel-end torque of the engine at the current vehicle speed.

[0064] The wheel-end torque of the engine refers to the torque that is amplified by the transmission system, such as the gearbox and the final reducer, and finally acts on the wheels. The wheel-end torque is equal to the product of the engine's external characteristic torque and the speed ratio. The speed ratio, also known as the overall gear ratio, refers to the "total product" of the gear ratios of all transmission components involved in speed reduction and torque amplification from the engine crankshaft to the wheels.

[0065] In one implementation, in determining whether the first torque deviation exceeds the torque compensation boundary, the current vehicle speed can be determined first, then the wheel-end torque of the engine at the current vehicle speed can be determined, the torque compensation boundary can be determined based on the wheel-end torque, and finally, it can be determined whether the first torque deviation exceeds the torque compensation boundary.

[0066] For example, preset vehicle speeds A, B, C, and D can be preset in ascending order, and the wheel-end torques of the engine at preset vehicle speeds A, B, C, and D can be determined respectively, including wheel-end torque A corresponding to preset vehicle speed A, wheel-end torque B corresponding to preset vehicle speed B, wheel-end torque C corresponding to preset vehicle speed C, and wheel-end torque D corresponding to preset vehicle speed D.

[0067] In determining whether the first torque deviation exceeds the torque compensation boundary, the vehicle controller first determines the vehicle's current speed at the current moment and then selects the target preset speed from multiple preset speeds. For example, the vehicle controller can calculate the speed difference between the current speed and preset speeds A, B, C, and D, and select the speed with the smallest difference from these preset speeds as the target preset speed. For instance, if the speed difference between preset speed D and the current speed is the smallest, then preset speed D can be determined as the target preset speed. Next, the wheel-end torque D corresponding to preset speed D is determined, and the product of wheel-end torque D and a pre-set proportional coefficient is calculated. The product result is used as the torque compensation boundary. The wheel-end torque corresponding to each preset speed is a scalar, greater than 0, and the proportional coefficient is a coefficient greater than 0 and less than 1.

[0068] Next, the absolute value of the first torque deviation is compared with the torque compensation boundary. If the absolute value of the first torque deviation is greater than the torque compensation boundary, it is determined that the first torque deviation exceeds the torque compensation boundary, and the torque compensation boundary is used as the compensation torque. Conversely, if the absolute value of the first torque deviation is less than or equal to the torque compensation boundary, the first torque deviation is used as the compensation torque.

[0069] In this embodiment, before determining whether the first torque deviation exceeds the torque compensation boundary, the wheel-end torque of the engine at the current vehicle speed is determined, and the torque compensation boundary is determined based on the wheel-end torque. This allows the torque compensation boundary to be matched with the vehicle speed, ensuring that the limitation on the compensation torque is matched with the vehicle speed when limiting the compensation torque according to the torque compensation boundary, thereby improving the vehicle's stability at different speeds.

[0070] Optionally, the torque compensation boundary is determined based on the wheel-end torque of the engine at the current vehicle speed, including: Determine the proportional coefficient corresponding to the recycling capacity value of the power battery; the recycling capacity value is positively correlated with the proportional coefficient. The torque compensation boundary is determined by multiplying the wheel end torque by the proportional coefficient.

[0071] In one implementation, during the process of determining the torque compensation boundary based on the wheel-end torque of the engine, the recovery capacity value of the power battery can be determined first, and the wheel-end torque can be adjusted according to the proportional coefficient corresponding to the recovery capacity value to obtain the torque compensation boundary.

[0072] For example, the recovery capability can be characterized by charging power. The higher the charging power, the greater the power recovery capability of the battery. For ease of distinction, the proportional coefficient corresponding to the charging power is referred to as the first proportional coefficient. For instance, multiple charging powers arranged in ascending order can be preset, and these preset charging powers are referred to as preset charging powers. For example, the preset charging powers in ascending order are preset charging power A, preset charging power B, preset charging power C, and preset charging power D. For each preset charging power among preset charging power A, preset charging power B, preset charging power C, and preset charging power D, a corresponding proportional coefficient can be pre-calibrated experimentally. The higher the preset charging power, the higher the corresponding proportional coefficient, with a maximum proportional coefficient of 1.

[0073] After determining the wheel-end torque of the engine at the current vehicle speed, the current charging power of the power battery at the current moment can be determined. Then, from multiple preset charging powers, a preset charging power corresponding to the current charging power is determined as the target charging power. The preset charging power corresponding to the current charging power can be the preset charging power that is closest to the current charging power among multiple preset charging powers, or the preset charging power that is closest to the current charging power among at least one preset charging power that is less than the current charging power.

[0074] Then, the proportional coefficient corresponding to the target charging power is used as the first proportional coefficient. The product of the first proportional coefficient and the wheel end torque of the engine at the current vehicle speed is calculated. The product result is used as the torque compensation boundary. When the first torque deviation exceeds the torque compensation boundary, the compensation torque is determined according to the torque compensation boundary.

[0075] For example, the recovery capability value can be determined by the remaining charge of the power battery, also known as the state of charge (SOC). The larger the remaining charge, the smaller the power battery's recovery capability. For ease of distinction, the proportional coefficient corresponding to the remaining charge will be referred to as the second proportional coefficient. For example, multiple remaining charges arranged in ascending order can be preset, and these preset remaining charges will be referred to as preset remaining charges. For example, the preset remaining charges in ascending order are preset remaining charge A, preset remaining charge B, preset remaining charge C, and preset remaining charge D. For each preset remaining charge among preset remaining charges A, preset remaining charge B, preset remaining charge C, and preset remaining charge D, a corresponding proportional coefficient can be pre-calibrated experimentally. The larger the preset remaining charge, the smaller the corresponding proportional coefficient. Each proportional coefficient is greater than 0, with a maximum proportional coefficient of 1.

[0076] After determining the wheel-end torque of the engine at the current vehicle speed, the current remaining charge of the power battery at the current moment can be determined. Then, from multiple preset remaining charges, a preset remaining charge corresponding to the current remaining charge is selected as the target remaining charge. The preset remaining charge corresponding to the current remaining charge can be the preset remaining charge that is closest to the current remaining charge among multiple preset remaining charges, or the preset remaining charge that is closest to the current remaining charge among at least one preset remaining charge that is less than the current remaining charge.

[0077] Next, the proportional coefficient corresponding to the target remaining power is used as the second proportional coefficient. The product of the second proportional coefficient and the wheel end torque of the engine at the current vehicle speed is calculated. The product result is used as the torque compensation boundary. When the first torque deviation exceeds the torque compensation boundary, the compensation torque is determined according to the torque compensation boundary.

[0078] For example, the recovery capacity can be characterized by the current temperature of the power battery. The higher or lower the temperature, the greater the power battery's power recovery capacity. For ease of distinction, the proportional coefficient corresponding to the current temperature is referred to as the third proportional coefficient. Multiple temperatures can be preset, hereinafter referred to as preset temperatures. These preset temperatures include multiple preset temperatures starting from the optimal operating temperature of the power battery and increasing in ascending order, as well as multiple preset temperatures starting from the optimal operating temperature and decreasing in descending order. For example, if the optimal operating temperature is 0 degrees Celsius, preset temperatures A1, B1, C1, and D1 can be set starting from 0 degrees Celsius and increasing in ascending order. Simultaneously, preset temperatures A2, B2, C2, and D2 can be set starting from 0 degrees Celsius and decreasing in descending order. Preset temperatures A1, B1, C1, and D1 are temperature values ​​greater than 0, while preset temperatures A2, B2, C2, and D2 are temperature values ​​less than 0.

[0079] For each of the preset temperatures A1, B1, C1, and D1, as well as A2, B2, C2, and D2, a corresponding proportionality coefficient can be pre-calibrated through experiments. The larger the absolute value of the preset temperature, the smaller the corresponding proportionality coefficient. Each proportionality coefficient is greater than 0, with a maximum of 1.

[0080] After determining the engine's wheel-end torque at the current vehicle speed, the current temperature of the power battery can be determined. Then, from multiple preset temperatures, a target preset temperature is selected that corresponds to the current temperature. This target preset temperature can be the one closest to the current temperature among the multiple preset temperatures. Next, the proportionality coefficient corresponding to the target preset temperature is used as the third proportionality coefficient. The product of the third proportionality coefficient and the engine's wheel-end torque at the current vehicle speed is calculated, and the product is used as the torque compensation boundary. When the first torque deviation exceeds the torque compensation boundary, the compensation torque is determined based on the torque compensation boundary.

[0081] In practical applications, when determining the torque compensation boundary based on the wheel-end torque of the engine, any one of the first proportional coefficient, the second proportional coefficient, and the third proportional coefficient can be determined. The product of the determined proportional coefficient and the wheel-end torque is calculated, and the product is used as the torque compensation boundary.

[0082] Alternatively, two or three of the first, second, and third proportional coefficients can be determined, and the product of all determined proportional coefficients and the wheel-end torque of the engine at the current vehicle speed can be calculated. The final product is then used as the torque compensation boundary. For example, in determining the torque compensation boundary based on the engine's wheel-end torque, the first and second proportional coefficients can be determined, and then the product of the first, second, and wheel-end torques can be calculated, with the result used as the torque compensation boundary. As another example, the first, second, and third proportional coefficients can be determined, and then the product of the first, second, and third proportional coefficients and the wheel-end torques can be calculated, with the result used as the torque compensation boundary.

[0083] In practical applications, the greater the regenerative braking capacity of the power battery, the greater the allowable regenerative torque, and the lower the probability of the front axle motor taking away the regenerative torque share from the rear axle motor. The larger the regenerative braking capacity value, the larger the corresponding proportional coefficient. When the battery's regenerative braking capacity is large, a larger proportional coefficient can be selected to adjust the wheel-end torque to obtain the torque compensation boundary. Thus, when the power battery's regenerative braking capacity is large, a larger torque compensation boundary can be used to enable the front axle motor to provide greater compensation for the engine torque, thereby ensuring the vehicle's braking force and, consequently, its braking efficiency.

[0084] Optionally, step 101 may include: If the recovery capacity of the power battery is less than the preset threshold, then if the first torque deviation exceeds the torque compensation boundary, the compensation torque is determined according to the torque compensation boundary. Alternatively, if the recovery capacity value is less than the preset capacity threshold, then if the first torque deviation does not exceed the torque compensation boundary, the compensation torque is determined based on the first torque deviation. Alternatively, if the recovery capacity value is greater than or equal to the preset capacity threshold, the compensation torque is determined based on the first torque deviation.

[0085] The regenerative braking capacity value of a power battery is a parameter used to evaluate its regenerative braking ability. Regenerative braking capacity is positively correlated with allowable regenerative torque; the higher the regenerative braking capacity, the higher the allowable regenerative torque. For example, the regenerative braking capacity value can be the charging power of the power battery, and the preset capacity threshold can be a charging power threshold. When the charging power is less than the preset charging power threshold, it indicates that the power battery's regenerative braking capacity is low, and the allowable regenerative torque is small. Conversely, when the charging power is greater than or equal to the preset charging power threshold, it indicates that the power battery's regenerative braking capacity is high, and the allowable regenerative torque is large.

[0086] For example, the regenerative braking capacity of a power battery can be defined as the allowable regenerative torque, and the preset capacity threshold can be defined as the regenerative torque boundary. When the allowable regenerative torque is less than the preset regenerative torque boundary, it indicates that the power battery has a low regenerative braking capacity and a small allowable regenerative torque. Conversely, when the allowable regenerative torque is greater than or equal to the regenerative torque boundary, it indicates that the power battery has a high regenerative braking capacity and a large allowable regenerative torque.

[0087] In one implementation, when the power battery's regenerative braking capability is low, a compensation torque can be determined based on the torque compensation boundary when the first torque deviation exceeds the torque compensation boundary. Conversely, when the power battery's regenerative braking capability is high, the compensation torque can be directly determined based on the first torque deviation. For example, when the vehicle controller determines that the vehicle is in direct drive mode and detects that the brake pedal is depressed, it can determine the power battery's charging power at the current moment and simultaneously determine the first torque deviation. Then, it compares the charging power with a charging power threshold. If the charging power is less than the charging power threshold, it determines that the power battery's regenerative braking capability is low. It then further determines whether the first torque deviation exceeds the torque compensation boundary. If the first torque deviation exceeds the torque compensation boundary, the torque compensation boundary is used as the compensation torque; otherwise, the first torque deviation is used as the compensation torque.

[0088] Conversely, when the charging power is greater than or equal to the power threshold, it is determined that the power battery has a high power recovery capability, and the first torque deviation can be directly used as the compensation torque.

[0089] It should be noted that when the vehicle is in direct drive mode and braking condition, and the power battery's power recovery capability is 0 (i.e., the allowable recovery torque is 0), the target torque for the front axle and the target torque for the rear axle can be directly determined to be 0.

[0090] It should be understood that the above are merely illustrative examples, and the recovery capacity values ​​used to evaluate the power recovery capability of a power battery may include, but are not limited to, the charging power and allowable recovery torque in the examples above.

[0091] In reality, the smaller the power battery's regenerative braking capacity, the greater the probability that the front axle motor will steal the regenerative torque share from the rear axle motor. The greater the share of regenerative torque stolen from the rear axle motor, the greater the fluctuation in actual braking torque.

[0092] In this embodiment of the application, when the recovery capacity of the power battery is less than the preset capacity threshold, the compensation torque is determined according to the torque compensation boundary, which can reduce the fluctuation of the actual braking torque, thereby reducing the fluctuation of vehicle deceleration and improving vehicle stability.

[0093] When the power battery’s recovery capacity is greater than or equal to a preset capacity threshold, the compensation torque is determined based on the first torque deviation, which can ensure the front axle motor’s torque compensation to the engine, thereby improving the vehicle’s braking efficiency.

[0094] Optionally, if the first torque deviation exceeds the torque compensation boundary, the compensation torque is determined based on the torque compensation boundary, including: If the first torque deviation exceeds the torque compensation boundary, determine the target braking torque currently required by the vehicle; When the target braking torque is greater than or equal to the preset braking torque threshold, the compensation torque is determined according to the torque compensation boundary.

[0095] Among them, the braking torque threshold is a relatively small torque threshold. A target braking torque less than the braking torque threshold indicates that the target braking torque is small, and a target braking torque greater than or equal to the braking torque threshold indicates that the target braking torque is large.

[0096] In one embodiment, if the first torque deviation exceeds the torque compensation boundary, it can be determined whether the target braking torque currently required by the vehicle is greater than or equal to a preset braking torque threshold. If the target braking torque is less than the braking torque threshold, the target braking torque is determined to be small, and the first deviation threshold is directly used as the compensation torque. Conversely, if the target braking torque is greater than or equal to the braking torque threshold, the target braking torque is determined to be large, and the torque compensation boundary can be used as the compensation torque.

[0097] In practical applications, when the target braking torque is small, the vehicle deceleration is small, and even if the deceleration fluctuates, the impact on the vehicle will not be significant.

[0098] In this embodiment, when the target braking torque of the vehicle is greater than or equal to a preset braking torque threshold, it is determined that the target braking torque of the vehicle is large. The compensation torque is determined according to the torque compensation boundary, which can reduce the fluctuation of deceleration when the vehicle deceleration is large, thereby improving the stability of the vehicle.

[0099] Conversely, when the target braking torque of the vehicle is less than the preset braking torque threshold, it is determined that the target braking torque of the vehicle is small. Based on the first torque deviation, the compensation torque is determined, and the engine can be compensated more by the front axle motor to improve the braking efficiency of the vehicle.

[0100] Optionally, the compensation torque is determined based on the torque compensation boundary, including: When the target braking torque currently required by the vehicle is less than the permissible regenerative torque, a second torque deviation between the target braking torque and the permissible regenerative torque is determined. When the second torque deviation is less than the first torque deviation, the compensation torque is determined according to the torque compensation boundary. If the second torque deviation is greater than or equal to the first torque deviation, the compensation torque is determined based on the first torque deviation.

[0101] In one implementation, during the process of determining the compensation torque based on the torque compensation boundary, it can be first determined whether the target braking torque currently required by the vehicle is less than the allowable regenerative torque. If the target braking torque is less than the allowable regenerative torque, a second torque deviation between the target braking torque and the allowable regenerative torque is further determined, and then a first torque deviation is compared with the second torque deviation. If the second torque deviation is greater than or equal to the first torque deviation, it can be determined that the allowable regenerative torque can completely cover the target braking torque. That is, when the torque output by the front axle motor is increased by the first torque deviation on the basis of the basic braking torque, the front axle motor will not take away the share of the regenerative torque of the rear axle motor. At this time, the first torque deviation can be directly used as the compensation torque.

[0102] Conversely, if the second torque deviation is less than the first torque deviation, it can be determined that the allowable recovery torque cannot cover the target braking torque and the second torque deviation. When the torque output by the front axle motor is increased by the first torque deviation on the basis of the basic braking torque, the torque output by the rear axle motor will be less than the rear axle braking torque. The front axle motor will take away the recovery torque share of the rear axle motor. At this time, the torque compensation boundary can be used as the compensation torque.

[0103] As mentioned above, when the front axle motor takes up a larger share of the regenerative torque from the rear axle motor, the greater the share of regenerative torque taken up by the front axle motor, the greater the fluctuation in the vehicle's actual braking torque and deceleration.

[0104] In this embodiment, during the process of determining the compensation torque based on the torque compensation boundary, when the target braking torque is less than the allowable regenerative torque and the second torque deviation between the target braking torque and the allowable regenerative torque is less than the first torque deviation, the compensation torque is determined based on the torque compensation boundary. When the second torque compensation boundary is greater than or equal to the first torque compensation boundary, the compensation torque is determined based on the first torque deviation. This allows for the determination of the compensation torque based on the torque compensation boundary when the front axle motor is taking a share of the regenerative torque from the rear axle motor, thereby reducing fluctuations in the vehicle's actual braking torque and deceleration. Conversely, when the front axle motor does not take a share of the regenerative torque from the rear axle motor, determining the compensation torque based on the first torque deviation ensures torque compensation from the engine by the front axle motor, thus improving the vehicle's braking efficiency.

[0105] Optionally, if the second torque deviation is less than the first torque deviation, the compensation torque is determined based on the torque compensation boundary, including: If the second torque deviation is less than the first torque deviation, a third torque deviation between the second torque deviation and the first torque deviation is determined. If the third torque deviation is greater than the preset deviation threshold, the compensation torque is determined according to the torque compensation boundary.

[0106] Among them, the deviation threshold is a small value. If the third torque deviation is less than or equal to the preset deviation threshold, it means that the difference between the second torque deviation and the first torque deviation is small. If the third torque deviation is greater than the preset deviation threshold, it means that the difference between the second torque deviation and the first torque deviation is large.

[0107] In this embodiment, when the second torque deviation is less than the first torque deviation, a third torque deviation between the second torque deviation and the first torque deviation can be further determined. Then, the third torque deviation is compared with a preset deviation threshold. When the third torque deviation is less than the deviation threshold, it is determined that the difference between the second torque deviation and the first torque deviation is small. At this time, even if the front axle motor directly uses the first torque deviation as the compensation torque, the front axle motor will not take away too much of the share of the recovery torque of the rear axle motor. At this time, the compensation torque can be directly determined based on the first torque deviation.

[0108] Conversely, when the third torque deviation is greater than the deviation threshold, it is determined that the second torque deviation is significantly different from the first torque deviation. When the front axle motor uses the first torque deviation as the compensation torque, the front axle motor will take a larger share of the regenerative torque from the rear axle motor. The compensation torque can be determined based on the torque compensation boundary to limit the compensation torque to a smaller range. This can limit the front axle motor from taking a larger share of the regenerative torque from the rear axle motor, thereby reducing the fluctuations in the vehicle's target braking torque and deceleration.

[0109] In this embodiment of the application, when the third torque deviation is greater than the preset deviation threshold, the compensation torque is determined according to the torque compensation boundary. When the front axle motor has a large share of the regenerative torque of the rear axle motor, the compensation torque is determined according to the torque compensation boundary, and the compensation torque is limited to a small range. This limits the front axle motor's share of the regenerative torque of the rear axle motor, thereby reducing the fluctuation of the vehicle's actual braking torque and deceleration, and improving the vehicle's stability.

[0110] Conversely, when the third torque deviation is less than or equal to the preset deviation threshold, the compensation torque is determined based on the first torque deviation. This allows the front axle motor to compensate for the engine's torque when its share of the regenerative torque from the rear axle motor is relatively small, thereby improving the vehicle's braking efficiency.

[0111] Optionally, if the second torque deviation is greater than or equal to the first torque deviation, the step of determining the compensation torque based on the first torque deviation may include: If the second torque deviation is greater than or equal to the first torque deviation, determine whether the vehicle is on a downhill road. If the vehicle is on a downhill road, the compensation torque is determined based on the torque compensation boundary. If the vehicle is not on a downhill slope, the compensation torque is determined based on the first torque deviation.

[0112] In this embodiment, if the second torque deviation is greater than or equal to the first torque deviation, it can be further determined whether the vehicle is in a downhill condition. For example, if the inertial measurement unit (IMU) in the vehicle detects that the vehicle's acceleration in the longitudinal direction (i.e., the vertical direction) is downward for an extended period when the second torque deviation is greater than or equal to the first torque deviation, it is determined that the vehicle is in a downhill condition. When the vehicle is in a downhill condition, it indicates that the vehicle requires more braking force. At this time, even if the regenerative torque can cover the target braking torque, the front axle motor may still preempt the regenerative torque share of the rear axle motor. In this case, the compensation torque can be determined based on the torque compensation boundary.

[0113] Conversely, if the second torque deviation is greater than or equal to the first torque deviation, and the inertial measurement unit in the vehicle detects that the vehicle's acceleration in the longitudinal direction is upward or equal to 0 for a long time, it is determined that the vehicle is in an uphill or flat road condition (i.e., not in a downhill condition). It can be determined that the allowable regenerative torque can most likely cover the target braking torque, and the front axle motor is unlikely to take away the share of the regenerative torque from the rear axle motor. At this time, the compensation torque can be determined based on the first torque deviation.

[0114] In this embodiment, during the process of determining the compensation torque based on the torque compensation boundary, when the target braking torque is less than the allowable regenerative torque and the second torque deviation between the target braking torque and the allowable regenerative torque is greater than or equal to the first torque deviation, the compensation torque is determined based on the torque compensation boundary when the vehicle is in a downhill condition, and based on the first torque deviation when the vehicle is not in a downhill condition. This allows for the determination of the compensation torque based on the torque compensation boundary when the front axle motor is taking a share of the regenerative torque from the rear axle motor, thereby reducing fluctuations in the vehicle's actual braking torque and deceleration. Conversely, when the front axle motor does not take a share of the regenerative torque from the rear axle motor, the compensation torque is determined based on the first torque deviation, ensuring torque compensation from the engine by the front axle motor, thus improving the vehicle's braking efficiency.

[0115] See Figure 2 , Figure 2 This is a schematic flowchart of a motor control method provided in an embodiment of this application. Figure 2 As shown, the method may include the following steps: Step 201: Determine the regeneration capacity value of the power battery when the vehicle is in direct drive mode and braking condition.

[0116] Step 202: Determine whether the recycling capacity value is less than the preset capacity threshold.

[0117] Step 203: Determine whether the first torque deviation exceeds the torque compensation boundary.

[0118] In this embodiment, when it is determined that the vehicle is in direct drive mode, if it is determined that the vehicle's brake pedal is pressed, it is determined that the vehicle has entered braking condition. After determining that the vehicle has entered braking condition, the recovery capacity value of the power battery is determined, and then it is compared whether the recovery capacity value is less than a preset capacity threshold. If the recovery capacity value is less than the preset capacity threshold, it is determined that the power battery's power recovery capacity is low, and then step 203 is executed. If the recovery capacity value is greater than or equal to the preset capacity threshold, it is determined that the power battery's power recovery capacity is high, and step 205 is executed.

[0119] Step 204: Determine the compensation torque based on the torque compensation boundary.

[0120] Step 205: Determine the compensation torque based on the first torque deviation.

[0121] In this embodiment, after determining that the recovery capacity of the power battery is less than a preset threshold, the actual braking torque and the target braking torque of the engine are determined. Then, a first torque deviation between the actual braking torque and the target braking torque is calculated, and it is determined whether the first torque deviation exceeds the torque compensation boundary. If the first torque deviation exceeds the torque compensation boundary, step 204 is executed to determine the compensation torque based on the torque compensation boundary. If the first torque deviation does not exceed the torque compensation boundary, step 205 is executed to determine the compensation torque based on the first torque deviation.

[0122] Furthermore, after determining that the recovery capacity of the power battery is greater than or equal to a preset capacity threshold, the actual braking torque and the target braking torque of the engine are determined, then the first torque deviation between the actual braking torque and the target braking torque is calculated, and the compensation torque is determined based on the first torque deviation.

[0123] Step 206: Determine the target torque for the front axle based on the compensation torque and the base braking torque. Determine the target torque for the rear axle based on the target torque for the front axle and the allowable regenerative torque.

[0124] Step 207: Control the front axle motor according to the target torque of the front axle, and control the rear axle motor according to the target torque of the rear axle.

[0125] In this embodiment, after determining the compensation torque, the target torque of the front axle is determined based on the compensation torque and the base braking torque of the front axle motor, and the target torque of the rear axle is determined based on the target torque of the front axle and the allowable regenerative torque. Then, the front axle motor is controlled based on the target torque of the front axle, and the rear axle motor is controlled based on the target torque of the rear axle.

[0126] See Figure 3 , Figure 3 This is a flowchart illustrating another motor control method provided in an embodiment of this application. Figure 3 As shown, the method may include the following steps: Step 301: When the vehicle is in direct drive mode and braking condition, determine the wheel-end torque of the engine at the current vehicle speed, and determine the recovery capacity value of the power battery and the corresponding ratio coefficient.

[0127] Step 302: Calculate the torque compensation boundary based on the determined proportional coefficient and wheel end torque.

[0128] Step 303: Determine whether the first torque deviation exceeds the torque compensation boundary.

[0129] Step 304: Determine the compensation torque based on the torque compensation boundary.

[0130] Step 305: Determine the compensation torque based on the first torque deviation.

[0131] In this embodiment, when the vehicle is determined to be in direct drive mode, if the brake pedal is determined to be depressed, the vehicle is determined to have entered braking condition. After determining that the vehicle has entered braking condition, the regenerative braking capacity of the power battery is determined, and the wheel-end torque of the engine at the vehicle's current speed is determined. A proportional coefficient is determined based on the regenerative braking capacity value. The proportional coefficient includes one or more of a first proportional coefficient, a second proportional coefficient, and a third proportional coefficient. The torque compensation boundary is determined based on the wheel-end torque and the determined proportional coefficient. Simultaneously, the actual braking torque and the target braking torque of the engine can be determined, and then the first torque deviation between the actual braking torque and the target braking torque is calculated.

[0132] Finally, it is determined whether the first torque deviation exceeds the torque compensation boundary. If it does, step 304 is executed to determine the compensation torque based on the torque compensation boundary. If it does not exceed the torque compensation boundary, step 305 is executed to determine the compensation torque based on the first torque deviation.

[0133] Step 306: Determine the target torque for the front axle based on the compensation torque and the basic braking torque, and determine the target torque for the rear axle based on the target torque for the front axle and the allowable regenerative torque.

[0134] Step 307: Control the front axle motor according to the target torque of the front axle, and control the rear axle motor according to the target torque of the rear axle.

[0135] In this embodiment, after determining the compensation torque, the target torque of the front axle is determined based on the compensation torque and the base braking torque of the front axle motor, and the target torque of the rear axle is determined based on the target torque of the front axle and the allowable regenerative torque. Then, the front axle motor is controlled based on the target torque of the front axle, and the rear axle motor is controlled based on the target torque of the rear axle.

[0136] The above text combined Figure 1-3 The motor control method provided in the embodiments of this application has been described in detail; the following will be combined with Figure 4 and Figure 5 The controller embodiments of this application are described in detail below. It should be understood that the controller in the embodiments of this application can execute the various methods described in the foregoing embodiments of this application. That is, the specific working processes of the various products described below can be referred to the corresponding processes in the foregoing method embodiments.

[0137] See Figure 4 , Figure 4 This is a schematic diagram of the structure of a controller provided in an embodiment of this application. Figure 4 As shown, the controller 400 may include: The determining module 401 is configured to, when the vehicle is in direct drive mode and braking condition, if the first torque deviation between the current actual driving torque of the engine and the target driving torque exceeds the torque compensation boundary, determine the compensation torque that the front axle motor needs to output for the engine based on the torque compensation boundary; determine the front axle target torque that the front axle motor needs to output based on the compensation torque and the base braking torque allocated to the front axle motor; and determine the rear axle target torque that the rear axle motor needs to output based on the front axle target torque and the current allowable regeneration torque of the power battery. The control module 402 is used to control the front axle motor according to the target torque of the front axle and to control the rear axle motor according to the target torque of the rear axle.

[0138] Optionally, the determining module 401 is further configured to determine the current vehicle speed; and determine the torque compensation boundary based on the wheel-end torque of the engine at the current vehicle speed.

[0139] Optionally, the determining module 401 is specifically used to determine a proportional coefficient corresponding to the recycling capacity value of the power battery, wherein the recycling capacity value is positively correlated with the proportional coefficient; and to determine the torque compensation boundary based on the product of the wheel end torque and the proportional coefficient.

[0140] Optionally, the determining module 401 is specifically configured to: if the recovery capability value of the power battery is less than a preset capability threshold, then determine the compensation torque based on the torque compensation boundary when the first torque deviation exceeds the torque compensation boundary; or, if the recovery capability value is less than the preset capability threshold, then determine the compensation torque based on the first torque deviation when the first torque deviation does not exceed the torque compensation boundary; or, if the recovery capability value is greater than or equal to the preset capability threshold, then determine the compensation torque based on the first torque deviation.

[0141] Optionally, the determining module 401 is specifically used to determine the target braking torque currently required by the vehicle when the first torque deviation exceeds the torque compensation boundary; and to determine the compensation torque according to the torque compensation boundary when the target braking torque is greater than or equal to a preset braking torque threshold.

[0142] Optionally, the determining module 401 is specifically configured to: determine a second torque deviation between the target braking torque and the allowable regenerative torque when the target braking torque currently required by the vehicle is less than the allowable regenerative torque; determine the compensation torque according to the torque compensation boundary when the second torque deviation is less than the first torque deviation; and determine the compensation torque according to the first torque deviation when the second torque deviation is greater than or equal to the first torque deviation.

[0143] Optionally, the determining module 401 is specifically configured to determine a third torque deviation between the second torque deviation and the first torque deviation when the second torque deviation is less than the first torque deviation; and to determine the compensation torque according to the torque compensation boundary when the third torque deviation is greater than a preset deviation threshold.

[0144] See Figure 5 , Figure 5 This is a structural schematic diagram of a vehicle provided in an embodiment of this application. For example... Figure 5 As shown, the vehicle 500 includes a memory 501 and a processor 502. The memory 501 stores executable program code 5011, and the processor 502 is used to call and execute the executable program code 5011 to perform a motor control method.

[0145] Furthermore, embodiments of this application also protect a controller, which may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to perform a motor control method provided in embodiments of this application.

[0146] This embodiment can divide the controller into functional modules according to the above method example. For example, each module can correspond to a separate functional module, or two or more functions can be integrated into one output module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0147] It should be understood that the controller provided in this embodiment is used to execute the above-described motor control method, and therefore can achieve the same effect as the above-described implementation method.

[0148] This embodiment also provides a readable storage medium storing executable program code. When the executable program code is run on a vehicle, it causes the vehicle to perform the aforementioned method steps to implement a motor control method provided in the above embodiment.

[0149] This embodiment also provides a program product that, when run on a vehicle, causes the vehicle to perform the aforementioned steps to implement a motor control method provided in the above embodiment.

[0150] In this embodiment, the controller, readable storage medium, program product, or chip are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0151] Through the above description of the implementation methods, those skilled in the art can understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the controller can be divided into different functional modules to complete all or part of the functions described above.

[0152] In the embodiments provided in this application, it should be understood that the disclosed controllers and methods can be implemented in other ways. For example, the controller embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another controller, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between controllers or units may be electrical, mechanical, or other forms.

[0153] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A motor control method, characterized in that, Applied to a vehicle, the vehicle including an engine, a power battery, a front axle motor, and a rear axle motor, the method includes: When the vehicle is in direct drive mode and braking condition, if the first torque deviation between the current actual driving torque of the engine and the target driving torque exceeds the torque compensation boundary, the compensation torque that the front axle motor needs to output for the engine is determined according to the torque compensation boundary. Based on the compensation torque and the base braking torque allocated to the front axle motor, determine the target front axle torque that the front axle motor needs to output; The target torque to be output by the rear axle motor is determined based on the target torque of the front axle and the current allowable regeneration torque of the power battery. The front axle motor is controlled according to the target torque of the front axle, and the rear axle motor is controlled according to the target torque of the rear axle.

2. The method as described in claim 1, characterized in that, Before determining the compensation torque that the front axle motor needs to output to the engine based on the torque compensation boundary if the first torque deviation between the engine's current actual driving torque and the target driving torque exceeds the torque compensation boundary, the method further includes: Determine the current speed of the vehicle; The torque compensation boundary is determined based on the wheel-end torque of the engine at the current vehicle speed.

3. The method as described in claim 2, characterized in that, Determining the torque compensation boundary based on the wheel-end torque of the engine at the current vehicle speed includes: A proportionality coefficient is determined to correspond to the recycling capacity value of the power battery, wherein the recycling capacity value is positively correlated with the proportionality coefficient; The torque compensation boundary is determined by multiplying the wheel end torque and the proportional coefficient.

4. The method as described in claim 1, characterized in that, If the first torque deviation between the current actual driving torque of the engine and the target driving torque exceeds the torque compensation boundary, then determining the compensation torque that the front axle motor needs to output for the engine based on the torque compensation boundary includes: If the recovery capacity of the power battery is less than a preset capacity threshold, then when the first torque deviation exceeds the torque compensation boundary, the compensation torque is determined according to the torque compensation boundary. Alternatively, if the recovery capacity value is less than the preset capacity threshold, then if the first torque deviation does not exceed the torque compensation boundary, the compensation torque is determined based on the first torque deviation. Alternatively, if the recovery capacity value is greater than or equal to the preset capacity threshold, the compensation torque is determined based on the first torque deviation.

5. The method as described in claim 4, characterized in that, The step of determining the compensation torque based on the torque compensation boundary when the first torque deviation exceeds the torque compensation boundary includes: If the first torque deviation exceeds the torque compensation boundary, determine the target braking torque currently required by the vehicle; When the target braking torque is greater than or equal to a preset braking torque threshold, the compensation torque is determined according to the torque compensation boundary.

6. The method as described in claim 4, characterized in that, Determining the compensation torque based on the torque compensation boundary includes: If the target braking torque currently required by the vehicle is less than the allowable regenerative torque, a second torque deviation between the target braking torque and the allowable regenerative torque is determined; When the second torque deviation is less than the first torque deviation, the compensation torque is determined according to the torque compensation boundary; If the second torque deviation is greater than or equal to the first torque deviation, the compensation torque is determined based on the first torque deviation.

7. The method as described in claim 6, characterized in that, When the second torque deviation is less than the first torque deviation, determining the compensation torque based on the torque compensation boundary includes: If the second torque deviation is less than the first torque deviation, a third torque deviation between the second torque deviation and the first torque deviation is determined; If the third torque deviation is greater than a preset deviation threshold, the compensation torque is determined according to the torque compensation boundary.

8. The method as described in claim 6, characterized in that, When the second torque deviation is greater than or equal to the first torque deviation, determining the compensation torque based on the first torque deviation includes: If the second torque deviation is greater than or equal to the first torque deviation, determine whether the vehicle is on a downhill road. If the vehicle is on a downhill road, the compensation torque is determined according to the torque compensation boundary; If the vehicle is not on a downhill road, the compensation torque is determined based on the first torque deviation.

9. A readable storage medium, characterized in that, The readable storage medium stores executable program code that, when run on a vehicle, causes the vehicle to perform the method as described in any one of claims 1 to 8.

10. A vehicle, characterized in that, The vehicles include: Memory, used to store executable program code; A processor for calling and running the executable program code from the memory, causing the vehicle to perform the method as described in any one of claims 1 to 8.

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