Dual-motor pure electric heavy truck downhill constant speed control system and control method thereof

Abstract

The present invention relates to the field of vehicle control technology, and discloses a dual-motor pure electric heavy-duty truck downhill constant speed control system, including a vehicle controller, the vehicle controller is connected to a motor controller, the motor controller is connected to a mid-bridge motor and a rear-bridge motor as downhill constant speed control actuators, and the vehicle controller is connected to a signal acquisition processing unit and a map positioning device. The present invention also discloses a control method for a dual-motor pure electric heavy-duty truck downhill constant speed control system. The dual-motor pure electric heavy-duty truck downhill constant speed control system and control method thereof adopt a dual-motor braking method, and do not require a retarder.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control technology, and in particular to a downhill constant speed control system for a dual-motor pure electric heavy truck and a control method thereof. Background Art

[0002] At present, the constant speed control of trucks is mainly concentrated in the field of traditional fuel vehicles, and there are fewer constant speed controls involving pure electric heavy trucks. In addition, the constant speed control of heavy trucks is mainly carried out by means of auxiliary braking, which is achieved by calling engine auxiliary braking or retarder. To achieve constant speed control of heavy trucks going downhill, a separate retarder needs to be installed, which is costly.

[0003] A Chinese patent (publication date: June 7, 2022, publication number: CN114590233A) discloses a downhill constant speed control method, device and storage medium, which belongs to the field of vehicle control technology. The downhill constant speed control method includes S1, obtaining the load of the vehicle and the slope of the vehicle driving section; S2, obtaining the pre-control torque according to the load, slope, tire radius and the road resistance coefficient of the driving section; S3, determining the vehicle speed PID closed-loop torque; S4, summing the pre-control torque and the vehicle speed PID closed-loop torque to obtain the final control torque; S5, obtaining a control signal according to the final control torque and sending it to the hydraulic retarder; S6, repeating steps S3 to S5 until the vehicle speed is equal to the set downhill constant speed target speed. The present invention can have a shorter response time, so that the vehicle speed can be quickly stabilized at the downhill constant speed target speed during the downhill process, reducing the probability of excessive speed and improving the safety of the vehicle.

[0004] A Chinese patent (publication date: October 12, 2016, publication number: CN106004838A) discloses a downhill assist control system based on a retarder and a control method thereof. The downhill assist control system of the present invention is composed of a signal acquisition unit, an electronic control unit and a retarder. The signal acquisition unit is used to collect brake pedal opening signals, accelerator pedal opening signals and vehicle speed signals. The electronic control unit performs logical judgment based on the above three signals and automatically starts or exits the downhill road assist control program. After starting the downhill assist control program, the electronic control unit calculates the braking torque according to the vehicle state and controls the retarder to output the braking torque so that the vehicle speed is at an appropriate level and the vehicle speed no longer increases. The present invention takes the retarder as the control object, establishes a control system, formulates a control strategy, realizes the automatic start and exit of the downhill assist mode, and keeps the vehicle speed at an appropriate level to ensure that the vehicle speed no longer increases, effectively improving the active safety of the vehicle and reducing the driving burden of the driver.

[0005] A Chinese patent (publication date: August 14, 2013, publication number: CN103241238A) discloses a hybrid vehicle downhill auxiliary braking exit method based on subjective intention and safety, including an auxiliary braking exit strategy when accelerating intention and an auxiliary braking exit strategy when braking intention. When an accelerator pedal signal is found, the acceleration a of the vehicle on a flat road corresponding to the accelerator pedal opening is calculated. When a≤0, the auxiliary braking torque is not exited; when a>0, the auxiliary braking torque is gradually exited on the principle of first exiting hydraulic braking, then exiting motor braking, and finally exiting engine braking. When a brake pedal signal is found, before the total auxiliary braking torque Tsum is zero, the brake pedal braking torque is gradually increased and Tsum is reduced, but the total braking torque is always kept unchanged, and the vehicle speed is also unchanged; after Tsum is equal to zero, the brake pedal braking torque is gradually increased, and the total braking torque increases. The present invention takes into account the auxiliary braking exit strategy under acceleration intention and braking intention, and has great safety.

[0006] A Chinese patent (publication date: August 6, 2011, publication number: CN113212446A) discloses a vehicle auxiliary braking control method, device, storage medium and equipment, which relates to the field of automobile and powertrain technology. The method includes the following steps: setting multiple braking levels according to the negative braking torque and the in-cylinder braking state; calibrating the engine brake fault category and establishing a corresponding relationship between the engine brake fault category and the selectable braking level; determining the corresponding fault mode braking level according to the actual engine brake fault. The present invention can limit the braking level to exert part of the engine auxiliary braking capacity, avoid actively disabling the auxiliary braking function, and ensure the braking performance of the vehicle.

[0007] The above patents all use auxiliary braking to achieve constant speed control by calling engine auxiliary braking or retarder. However, achieving constant speed control of heavy trucks downhill requires installing a separate retarder, which is costly. Summary of the invention

[0008] The purpose of the present invention is to address the deficiencies of the above-mentioned technology and provide a dual-motor pure electric heavy truck downhill constant speed control system and control method thereof, which adopts a dual-motor braking method and does not require a retarder.

[0009] To achieve the above-mentioned purpose, the dual-motor pure electric heavy-duty truck downhill constant speed control system designed by the present invention includes a vehicle controller, the vehicle controller is connected to a motor controller, the motor controller is connected to a mid-bridge motor and a rear-bridge motor serving as downhill constant speed control actuators, and the vehicle controller is connected to a signal acquisition and processing unit and a map positioning device.

[0010] Preferably, the signal acquisition and processing unit includes a brake pedal and an accelerator, and sends the brake signal and the throttle signal to the vehicle controller. The map positioning device identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller. The vehicle controller receives the information sent by the signal acquisition and processing unit and the map positioning device, calculates the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller. The mid-axle motor and the rear-axle motor receive the control signal of the motor controller, and send the motor temperature, torque, speed and fault status to the vehicle controller.

[0011] A control method for a downhill constant speed control system of a dual-motor pure electric heavy truck as described above, wherein the signal acquisition and processing unit includes a brake pedal and an accelerator, and sends a brake signal and an accelerator signal to the vehicle controller; the map positioning device identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller; the vehicle controller receives the information sent by the signal acquisition and processing unit and the map positioning device, calculates the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller; the mid-axle motor and the rear-axle motor receive the control signal of the motor controller, and send the motor temperature, torque, speed and fault status to the vehicle controller.

[0012] Preferably, the vehicle controller receives the altitude, ramp and road information sent by the map positioning device to identify the environmental conditions and selects a preset calibration parameter table, in which the vehicle ramp resistance parameters are stored for calculating the vehicle dynamic model.

[0013] Preferably, the vehicle controller obtains the road geographic information within 20 km ahead of the current vehicle based on the road section information sent by the map positioning device. The vehicle controller analyzes the road information 20 km ahead of the current vehicle and divides it into several sections. The vehicle controller calculates the constant speed limit value Vlimit for each section of road in advance based on the slope of each section of road.

[0014] Preferably, the vehicle controller calculates the vehicle speed value through the rotation speed of the mid-bridge motor, the rear-bridge motor and the wheel end, and calculates the real-time vehicle deceleration, and divides different thresholds according to the deceleration information. When the deceleration is less than 0.2, the braking intensity level is L1, when the deceleration is between 0.2 and 0.6, the braking intensity level is L2, when the deceleration is 0.6-0.8, the braking intensity level is L3, and when the deceleration is greater than 0.8, the braking intensity is L4.

[0015] Preferably, after the vehicle starts moving, the vehicle controller calculates the current vehicle load mass according to the current vehicle motion status by using a hybrid estimation method of Kalman filtering and least squares method to assist in calculating the vehicle braking demand torque.

[0016] Preferably, when the vehicle controller receives a request for downhill constant speed control, it activates the constant speed control function, and takes the vehicle speed when entering the downhill constant speed control function as the downhill constant speed control target speed Vtarget. During the entire downhill constant speed control process, if the driver does not actively step on the brakes, the vehicle speed at the time of entry will always be the target speed. When the driver steps on the brakes, the vehicle controller obtains the constant speed limit speed value Vlimit matching different road sections in front of the vehicle through the current road section information. If the actual vehicle speed is greater than the constant speed limit speed value Vlimit after the brakes are stepped on, the matching constant speed limit speed value Vlimit is used as the target constant speed. Otherwise, the time is calculated based on the cumulative time of the brake stepping after the brakes are stepped on, and the speed is reduced by a fixed step length Vdes per second.

[0017] Preferably, the vehicle controller calculates the real-time braking torque required by the vehicle. Under normal circumstances, during downhill constant speed braking, the braking torque is evenly distributed between the mid-axle motor and the rear-axle motor. When the mid-axle motor or the rear-axle motor fails or is torque-limited, the vehicle controller calculates the current maximum braking torque limit of the mid-axle motor and the rear-axle motor, and distributes it unevenly. If the failure or torque limitation is eliminated, the average torque distribution is re-entered.

[0018] Preferably, in the downhill constant speed control stage, if the accelerator is pressed, the downhill constant speed function is exited, and when the accelerator is released again, the current vehicle acceleration value is judged. If the acceleration value is positive and exceeds the threshold value A1, the downhill constant speed control is activated and the speed before the accelerator is released is used as the target downhill constant speed control target. If the acceleration value is negative or the acceleration value is positive and the threshold value is less than A1, no braking torque is applied to the mid-axle motor and the rear-axle motor, and the vehicle is in gliding mode.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. Downhill constant speed control adopts dual motor braking mode, and no retarder is required;

[0021] 2. Map positioning matches the speed limit of the geographical location and uses it as the target constant speed to control the vehicle speed;

[0022] 3. Use different deceleration thresholds to control the braking intensity and adapt the braking torque at different stages;

[0023] 4. Use the throttle as the condition for re-entering and exiting the downhill constant speed control. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the downhill constant speed control system of the dual-motor pure electric heavy truck of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Example 1

[0029] like Figure 1 As shown, a dual-motor pure electric heavy-duty truck downhill constant speed control system includes a vehicle controller 1, the vehicle controller 1 is connected to a motor controller 2, the motor controller 2 is connected to a mid-bridge motor 3 and a rear-bridge motor 4 as downhill constant speed control actuators, and the vehicle controller 1 is connected to a signal acquisition and processing unit 5 and a map positioning device 6.

[0030] When this embodiment is used, the signal acquisition and processing unit 5 will send it to the vehicle controller 1, the map positioning device 6 will identify the road section where the vehicle is located, and send the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, target vehicle speed and braking torque, and sends it to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0031] Example 2

[0032] A dual-motor pure electric heavy-duty truck downhill constant speed control system includes a vehicle controller 1, the vehicle controller 1 is connected to a motor controller 2, the motor controller 2 is connected to a mid-bridge motor 3 and a rear-bridge motor 4 as downhill constant speed control actuators, and the vehicle controller 1 is connected to a signal acquisition processing unit 5 and a map positioning device 6.

[0033] Among them, the signal acquisition and processing unit 5 includes a brake pedal and an accelerator, and sends the brake signal and the throttle signal to the vehicle controller 1. The map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0034] When this embodiment is in use, the signal acquisition and processing unit 5 sends the braking signal and the throttle signal to the vehicle controller 1, the map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0035] Example 3

[0036] A dual-motor pure electric heavy-duty truck downhill constant speed control system includes a vehicle controller 1, the vehicle controller 1 is connected to a motor controller 2, the motor controller 2 is connected to a mid-bridge motor 3 and a rear-bridge motor 4 as downhill constant speed control actuators, and the vehicle controller 1 is connected to a signal acquisition processing unit 5 and a map positioning device 6.

[0037] Among them, the signal acquisition and processing unit 5 includes a brake pedal and an accelerator, and sends the brake signal and the throttle signal to the vehicle controller 1. The map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0038] When this embodiment is in use, the signal acquisition and processing unit 5 sends the braking signal and the throttle signal to the vehicle controller 1, the map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0039] Among them, the vehicle controller 1 receives the altitude, slope, and road information sent by the map positioning device 6 to identify the environmental conditions, and selects a preset calibration parameter table, in which the vehicle slope resistance parameters are stored, for calculating the vehicle dynamic model. At the same time, the vehicle controller 1 obtains the road geographic information within 20 km from the current vehicle according to the road section information sent by the map positioning device 6. The vehicle controller 1 analyzes the road information 20 km ahead of the current vehicle and divides it into several sections. The vehicle controller 1 combines the slope of each road section to calculate the constant speed limit speed value Vlimit of each road section in advance.

[0040] When the vehicle controller 1 receives a request for downhill constant speed control, it activates the constant speed control function, and takes the vehicle speed when entering the downhill constant speed control function as the downhill constant speed control target speed Vtarget. During the entire downhill constant speed control process, if the driver does not actively step on the brakes, the vehicle speed at the time of entry will always be the target speed. When the driver steps on the brakes, the vehicle controller 1 obtains the constant speed limit speed value Vlimit that matches different sections in front of the vehicle through the current road section information. If the actual vehicle speed is greater than the constant speed limit speed value Vlimit after stepping on the brakes, the matching constant speed limit speed value Vlimit will be used as the target constant speed. Otherwise, the time after the brakes are stepped on will be calculated cumulatively according to the time the brakes are stepped on, and the speed will be reduced by a fixed step length Vdes per second.

[0041] Example 4

[0042] A dual-motor pure electric heavy-duty truck downhill constant speed control system includes a vehicle controller 1, the vehicle controller 1 is connected to a motor controller 2, the motor controller 2 is connected to a mid-bridge motor 3 and a rear-bridge motor 4 as downhill constant speed control actuators, and the vehicle controller 1 is connected to a signal acquisition processing unit 5 and a map positioning device 6.

[0043] Among them, the signal acquisition and processing unit 5 includes a brake pedal and an accelerator, and sends the brake signal and the throttle signal to the vehicle controller 1. The map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0044] When this embodiment is in use, the signal acquisition and processing unit 5 sends the braking signal and the throttle signal to the vehicle controller 1, the map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0045] The vehicle controller 1 calculates the vehicle speed through the rotation speed of the mid-bridge motor 3, the rear-bridge motor 4 and the wheel end, and calculates the real-time vehicle deceleration. Different thresholds are divided according to the deceleration information. When the deceleration is less than 0.2, the braking intensity level is L1, when the deceleration is between 0.2 and 0.6, the braking intensity level is L2, when the deceleration is 0.6-0.8, the braking intensity level is L3, and when the deceleration is greater than 0.8, the braking intensity is L4.

[0046] After the vehicle starts moving, the vehicle controller 1 calculates the current vehicle load mass using a mixed estimation method of Kalman filtering and least squares method according to the current vehicle motion status, which is used to assist in calculating the vehicle braking demand torque.

[0047] Example 5

[0048] A dual-motor pure electric heavy-duty truck downhill constant speed control system includes a vehicle controller 1, the vehicle controller 1 is connected to a motor controller 2, the motor controller 2 is connected to a mid-bridge motor 3 and a rear-bridge motor 4 as downhill constant speed control actuators, and the vehicle controller 1 is connected to a signal acquisition processing unit 5 and a map positioning device 6.

[0049] Among them, the signal acquisition and processing unit 5 includes a brake pedal and an accelerator, and sends the brake signal and the throttle signal to the vehicle controller 1. The map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0050] When this embodiment is in use, the signal acquisition and processing unit 5 sends the braking signal and the throttle signal to the vehicle controller 1, the map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0051] The vehicle controller 1 calculates the real-time braking torque required by the vehicle. Under normal circumstances, during downhill constant speed braking, the braking torque is evenly distributed between the middle axle motor 3 and the rear axle motor 4. When the middle axle motor 3 or the rear axle motor 4 fails or is torque-limited, the vehicle controller 1 calculates the current maximum braking torque limit of the middle axle motor 3 and the rear axle motor 4, and distributes it unevenly. If the failure or torque limitation is eliminated, the average torque distribution is re-entered.

[0052] Example 6

[0053] A dual-motor pure electric heavy-duty truck downhill constant speed control system includes a vehicle controller 1, the vehicle controller 1 is connected to a motor controller 2, the motor controller 2 is connected to a mid-bridge motor 3 and a rear-bridge motor 4 as downhill constant speed control actuators, and the vehicle controller 1 is connected to a signal acquisition processing unit 5 and a map positioning device 6.

[0054] Among them, the signal acquisition and processing unit 5 includes a brake pedal and an accelerator, and sends the brake signal and the throttle signal to the vehicle controller 1. The map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0055] When this embodiment is in use, the signal acquisition and processing unit 5 sends the braking signal and the throttle signal to the vehicle controller 1, the map positioning device 6 identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller 1. The vehicle controller 1 receives the information sent by the signal acquisition and processing unit 5 and the map positioning device 6 to calculate the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller 2. The mid-bridge motor 3 and the rear-bridge motor 4 receive the control signal of the motor controller 2, and send the motor temperature, torque, speed and fault status to the vehicle controller 1.

[0056] Among them, the vehicle controller 1 receives the altitude, slope, and road information sent by the map positioning device 6 to identify the environmental conditions, and selects a preset calibration parameter table. The calibration parameter table stores the vehicle slope resistance parameters for calculating the vehicle dynamic model. The vehicle controller 1 obtains the road geographic information within 20 km ahead of the current vehicle based on the road section information sent by the map positioning device 6. The vehicle controller 1 analyzes the road information 20 km ahead of the current vehicle and divides it into several sections. The vehicle controller 1 calculates the constant speed limit speed value Vlimit for each road section in advance based on the slope of each road section.

[0057] In addition, the vehicle controller 1 calculates the vehicle speed through the rotation speed of the mid-bridge motor 3, the rear-bridge motor 4 and the wheel end, and calculates the real-time vehicle deceleration, and divides different thresholds according to the deceleration information. When the deceleration is less than 0.2, the braking intensity level is L1, when the deceleration is between 0.2 and 0.6, the braking intensity level is L2, when the deceleration is 0.6-0.8, the braking intensity level is L3, and when the deceleration is greater than 0.8, the braking intensity is L4.

[0058] After the vehicle starts moving, the vehicle controller 1 calculates the current vehicle load mass using a mixed estimation method of Kalman filtering and least squares method according to the current vehicle motion status, which is used to assist in calculating the vehicle braking demand torque.

[0059] When the vehicle controller 1 receives a request for downhill constant speed control, it activates the constant speed control function, and takes the vehicle speed when entering the downhill constant speed control function as the downhill constant speed control target speed Vtarget. During the entire downhill constant speed control process, if the driver does not actively step on the brakes, the vehicle speed at the time of entry will always be the target speed. When the driver steps on the brakes, the vehicle controller 1 obtains the constant speed limit speed value Vlimit that matches the different road sections in front of the vehicle through the current road section information. If the actual vehicle speed after stepping on the brakes is greater than the constant speed limit speed value Vlimit, the matching constant speed limit speed value Vlimit is used as the target constant speed. Otherwise, the time is calculated based on the cumulative time of stepping on the brakes after stepping on the brakes, and the speed is reduced by a fixed step length Vdes per second.

[0060] The vehicle controller 1 calculates the real-time braking torque required by the vehicle. Under normal circumstances, during downhill constant speed braking, the braking torque is evenly distributed between the middle axle motor 3 and the rear axle motor 4. When the middle axle motor 3 or the rear axle motor 4 fails or is torque-limited, the vehicle controller 1 calculates the current maximum braking torque limit of the middle axle motor 3 and the rear axle motor 4, and distributes it unevenly. If the failure or torque limitation is eliminated, the average torque distribution is re-entered.

[0061] During the downhill constant speed control stage, if the accelerator is pressed, the downhill constant speed function will be exited. When the accelerator is released again, the current vehicle acceleration value will be judged. If the acceleration value is positive and exceeds the threshold value A1, the downhill constant speed control is activated and the speed before the accelerator is released is used as the target downhill constant speed control target. If the acceleration value is negative or the acceleration value is positive and the threshold value is less than A1, no braking torque will be applied to the middle axle motor 3 and the rear axle motor 4, and the vehicle is in gliding mode.

[0062] The dual-motor pure electric heavy-duty truck downhill constant speed control system and control method thereof adopts a dual-motor braking method for downhill constant speed control, and does not require a retarder; map positioning matches the geographic location speed limit as the target constant speed control vehicle speed; different deceleration thresholds are used as the control braking intensity to adapt to the braking torque at different stages; and the throttle is used as the condition for re-entering and exiting the downhill constant speed control.

[0063] It should be noted that the description of the above technical solutions is exemplary, and this specification can be embodied in different forms and should not be interpreted as being limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are limited only by the scope of the claims.

[0064] The various aspects disclosed for describing the present specification and claims are merely examples, and therefore, the present specification and claims are not limited to the details shown. In the above description, when the detailed description of the related known functions or configurations is determined to be unnecessary to obscure the focus of the present specification and claims, the detailed description will be omitted.

[0065] In the case of using “including”, “having” and “comprising” described in the present specification, unless otherwise used, there may also be another part or other parts, and the terms used may generally be in the singular but may also represent the plural form.

[0066] Finally, it should be pointed out that the above content is a further detailed description of the invention in combination with specific implementation methods. It cannot be considered that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, simple replacements made without departing from the concept of the present invention should be regarded as belonging to the protection scope of the present invention. The above embodiments are only more representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments, and there can be many variations. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention should be considered to belong to the protection scope of the present invention.

[0067] At the same time, it should be noted that the description of the above technical solutions is exemplary, and this specification can be embodied in different forms and should not be construed as being limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are limited only by the scope of the claims. The features of the various embodiments of the present invention may be partially or completely combined or spliced ​​with each other, and may be performed in various different configurations as those skilled in the art may fully understand. The embodiments of the present invention may be performed independently of each other, or may be performed together in a mutually dependent relationship.

[0068] For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and the above structures should be regarded as belonging to the protection scope of the present invention.

Claims

1. A dual-motor pure electric heavy truck downhill constant speed control system, comprising a vehicle controller (1), characterized in that: The vehicle controller (1) is connected to a motor controller (2), the motor controller (2) is connected to a mid-bridge motor (3) and a rear-bridge motor (4) as downhill constant speed control actuators, and the vehicle controller (1) is connected to a signal acquisition processing unit (5) and a map positioning device (6); The vehicle controller (1) obtains geographical information of roads within 20 km ahead of the current vehicle based on the road section information sent by the map positioning device (6); the vehicle controller (1) analyzes the road information within 20 km ahead of the current vehicle and divides it into several sections; the vehicle controller (1) calculates the constant speed limit value Vlimit of each road section in advance based on the slope of each road section; When the vehicle controller (1) receives a request for downhill constant speed control, it activates the constant speed control function, and takes the vehicle speed when entering the downhill constant speed control function as the downhill constant speed control target speed Vtarget. During the entire downhill constant speed control process, if the driver does not actively step on the brakes, the vehicle speed at the time of entry will always be the target speed. When the driver steps on the brakes, the vehicle controller (1) obtains the constant speed limit speed value Vlimit matched by different road sections ahead of the vehicle through the current road section information. If the actual vehicle speed after stepping on the brakes is greater than the constant speed limit speed value Vlimit, the matched constant speed limit speed value Vlimit is used as the target constant speed. Otherwise, the time is calculated based on the cumulative time after the brakes are stepped on, and the vehicle speed is reduced by a fixed step length Vdes per second. The vehicle controller (1) calculates the real-time braking torque required by the vehicle. Under normal circumstances, the braking torque is evenly distributed between the middle axle motor (3) and the rear axle motor (4) during downhill constant speed braking. When the middle axle motor (3) or the rear axle motor (4) fails or has torque limitation, the vehicle controller (1) calculates the current maximum braking torque limit of the middle axle motor (3) and the rear axle motor (4) and performs non-even distribution. If the failure or torque limitation is eliminated, the average torque distribution is re-entered.

2. According to claim 1, the dual-motor pure electric heavy truck downhill constant speed control system is characterized by: The signal acquisition and processing unit (5) includes a brake pedal and an accelerator, and sends the brake signal and the accelerator signal to the vehicle controller (1). The map positioning device (6) identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller (1). The vehicle controller (1) receives the information sent by the signal acquisition and processing unit (5) and the map positioning device (6), calculates the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller (2). The mid-bridge motor (3) and the rear-bridge motor (4) receive the control signal of the motor controller (2), and send the motor temperature, torque, speed and fault status to the vehicle controller (1).

3. A control method for a downhill constant speed control system of a dual-motor pure electric heavy truck as claimed in any one of claims 1 to 2, characterized in that: The signal acquisition and processing unit (5) includes a brake pedal and an accelerator, and sends the brake signal and the accelerator signal to the vehicle controller (1). The map positioning device (6) identifies the road section where the vehicle is located, and sends the road section information to the vehicle controller (1). The vehicle controller (1) receives the information sent by the signal acquisition and processing unit (5) and the map positioning device (6), calculates the braking deceleration, the target vehicle speed and the braking torque, and sends them to the motor controller (2). The mid-bridge motor (3) and the rear-bridge motor (4) receive the control signal of the motor controller (2), and send the motor temperature, torque, speed and fault status to the vehicle controller (1).

4. The control method of the dual-motor pure electric heavy truck downhill constant speed control system according to claim 3 is characterized by: The vehicle controller (1) receives the altitude, ramp and road information sent by the map positioning device (6) to identify the environmental conditions and selects a preset calibration parameter table, in which the vehicle ramp resistance parameters are stored for calculating the vehicle power model.

5. The control method of the dual-motor pure electric heavy truck downhill constant speed control system according to claim 3 is characterized by: The vehicle controller (1) obtains road geographic information within 20 km ahead of the current vehicle based on the road section information sent by the map positioning device (6). The vehicle controller (1) analyzes the road information within 20 km ahead of the current vehicle and divides it into several sections. The vehicle controller (1) calculates the constant speed limit speed value Vlimit of each road section in advance based on the slope of each road section.

6. The control method of the dual-motor pure electric heavy truck downhill constant speed control system according to claim 3 is characterized by: The vehicle controller (1) calculates the vehicle speed value through the rotation speed of the mid-bridge motor (3), the rear-bridge motor (4) and the wheel ends, and calculates the real-time vehicle deceleration, and divides different thresholds according to the deceleration information. When the deceleration is less than 0.2, the braking intensity level is L1, when the deceleration is between 0.2 and 0.6, the braking intensity level is L2, when the deceleration is between 0.6 and 0.8, the braking intensity level is L3, and when the deceleration is greater than 0.8, the braking intensity is L4.

7. The control method of the dual-motor pure electric heavy truck downhill constant speed control system according to claim 3 is characterized by: After the vehicle starts to move, the vehicle controller (1) calculates the current vehicle load mass according to the current vehicle movement status by using a Kalman filter and a least squares hybrid estimation method to assist in calculating the vehicle braking demand torque.

8. The control method of the dual-motor pure electric heavy truck downhill constant speed control system according to claim 5 is characterized by: When receiving a request for downhill constant speed control, the vehicle controller (1) activates the constant speed control function, and takes the vehicle speed when entering the downhill constant speed control function as the downhill constant speed control target speed Vtarget. During the entire downhill constant speed control process, if the driver does not actively step on the brakes, the vehicle speed at the time of entry will always be the target speed. When the driver steps on the brakes, the vehicle controller (1) obtains the constant speed limit speed value Vlimit matched with different sections ahead of the vehicle through the current road section information. If the actual vehicle speed after stepping on the brakes is greater than the constant speed limit speed value Vlimit, the matched constant speed limit speed value Vlimit is used as the target constant speed. Otherwise, the time is calculated based on the cumulative time after the brakes are stepped on, and the vehicle speed is reduced by a fixed step length Vdes per second.

9. The control method of the dual-motor pure electric heavy truck downhill constant speed control system according to claim 3 is characterized by: The vehicle controller (1) calculates the real-time braking torque required by the vehicle. Under normal circumstances, the braking torque is evenly distributed between the middle axle motor (3) and the rear axle motor (4) during downhill constant speed braking. When the middle axle motor (3) or the rear axle motor (4) fails or has torque limitation, the vehicle controller (1) calculates the current maximum braking torque limit of the middle axle motor (3) and the rear axle motor (4) and performs non-even distribution. If the failure or torque limitation is eliminated, the average torque distribution is re-entered.

10. The control method of the dual-motor pure electric heavy truck downhill constant speed control system according to claim 3, characterized in that: In the downhill constant speed control stage, if the accelerator is pressed, the downhill constant speed function is exited, and when the accelerator is released again, the current vehicle acceleration value is judged. If the acceleration value is positive and exceeds the threshold value A1, the downhill constant speed control is activated and the speed before the accelerator is released is used as the target downhill constant speed control target. If the acceleration value is negative or the acceleration value is positive and the threshold value is less than A1, no braking torque is applied to the middle axle motor (3) and the rear axle motor (4), and the vehicle is in a gliding mode.

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