A new energy electric trailer driving and braking control method

Abstract

The present application relates to a new energy electric trailer driving and braking control method, the electric trailer obtains key, gear, vehicle speed, accelerator pedal, brake pedal, steering wheel, yaw angular velocity and other parameters through communication with the towing vehicle, to judge the driver's driving behavior, set the power-on self-checking step before driving, after meeting the self-checking safety, enter the driving mode, based on the working condition of vehicle large steering or roll in driving, set the safety condition, only when the safety condition is met, ensure that the vehicle is not in large steering or roll, the electric trailer VCU controls the motor output brake torque or driving torque, provides the braking force or driving force for the vehicle, ensures the safety, stability and smoothness of the vehicle driving, and improves the economy and power of the vehicle.

Description

Technical Field

[0001] This invention relates to the field of vehicle driving technology, and more specifically to a method for driving and braking control of a new energy electric trailer. Background Technology

[0002] In the automotive transportation industry, traditional trailers originally referred to transport vehicles without their own power drive, requiring a tractor unit to provide traction for towing and carrying passengers or goods. However, with the advancement of electrification and intelligentization in the automotive industry, new energy electric trailers have become a new development trend.

[0003] New energy electric trailers are based on traditional trailers that integrate a power unit. The power unit can output driving force to assist the tractor and jointly drive the whole vehicle, effectively improving the vehicle's power performance under harsh working conditions. When braking, the rear electric trailer can also participate in braking to realize braking energy recovery, improve the vehicle's economy, and reduce heat loss and waste.

[0004] However, existing new energy electric trailers still have two major problems in terms of drive and control: First, the safety and stability during braking. From a safety perspective, when the tractor and trailer brake, the rear electric trailer cannot participate in braking under all operating conditions, especially when the vehicle is making a sharp turn or tilting. The electric trailer cannot provide additional braking interference, otherwise it will significantly affect the braking effect and safety of the vehicle, creating safety hazards. Second, the operational stability, smoothness, and safety during driving. The vehicle conditions during the driving of the tractor and trailer are quite complex. The electric trailer cannot unconditionally provide assistance under all driving conditions. Inappropriate assistance from the electric trailer will not only affect the operational stability and smoothness of the entire vehicle, but may even cause safety hazards such as trailer fishtailing and tilting. Summary of the Invention

[0005] The purpose of this invention is to provide a method for driving and braking control of new energy electric trailers to solve the above-mentioned problems.

[0006] The present invention adopts the following technical solution: A method for driving and braking control of a new energy electric trailer, wherein the electric trailer VCU and the tractor VCU communicate via CAN, and the electric trailer VCU acquires the key signal, gear position panel signal, handbrake signal, vehicle speed signal parameter Velocity, accelerator pedal opening signal parameter ACC_Ped, brake pedal opening signal parameter Bsk, steering wheel angle parameter Steering_Wheel_Angle, and yaw rate parameter Yaw_angvelocity from the tractor VCU; Specifically, key signal 1, 2, 3, or 4 correspond to the OFF, ACC, ON, or START positions of the key, respectively; the steering wheel angle threshold A_steer and yaw rate threshold V_ang are set based on the vehicle's large steering or tilting conditions; the accelerator pedal opening signal and duration at different vehicle speeds determine whether high power is needed, and the trailer power mode parameter Power_Mode is set. If Power_Mode=1, high power is needed, and the trailer power mode is entered; the specific steps are as follows: Step 1) The electric trailer is powered by low voltage. When the key signal = 1 and Velocity < 1, the trailer is in power-off mode.

[0007] Step 2) When the key signal is ≥2, the electric trailer enters the wake-up mode, powers on the electric trailer and performs a self-test. If the self-test is normal, it enters the ready mode; otherwise, it enters the fault mode.

[0008] Step 3) When the key signal is ≥3 and the Bsk acquired by the electric trailer is >0, the electric trailer enters the drive mode.

[0009] Step 4) When the electric trailer enters the drive mode, if the handbrake signal = 0, that is, the handbrake is released, and the signal on the tractor's gear panel is in forward gear, the electric trailer enters the driving mode.

[0010] Step 5) In the electric trailer driving mode, when the electric trailer obtains Bsk > 0, if the electric trailer obtains Steering_Wheel_Angle < A_steer and Yaw_ang_velocity < V_ang, then the electric trailer enters braking mode. The electric trailer VCU obtains the braking torque Torque_Bsk corresponding to the current brake pedal opening based on the brake pedal opening and vehicle speed interpolation braking torque map table, and calculates the output motor torque TM_rq as: TM_rq = Torque_Bsk; if the electric trailer obtains Steering_Wheel_Angle ≥ A_steer or Yaw_ang_velocity ≥ V_ang, the electric trailer VCU controls the output motor torque TM_rq as: TM_rq = 0.

[0011] Step 6) In electric trailer driving mode, when the electric trailer obtains ACC_Ped≥0, if Power_Mode=1, and simultaneously satisfies Steering_Wheel_Angle<A_steer and Yaw_ang_velocity<V_ang, the electric trailer enters drive assist mode. The electric trailer VCU obtains the drive torque Torque_drive corresponding to the current accelerator pedal opening based on the interpolated drive torque map table of accelerator pedal opening and vehicle speed, and calculates the output motor torque TM_rq as: TM_rq=Torque_drive; if Power_Mode=1 is not satisfied, or Steering_Wheel_Angle≥A_steer, or Yaw_ang_velocity≥V_ang, the electric trailer VCU controls the output motor torque TM_rq as: TM_rq=0.

[0012] Furthermore, step 2) includes two steps: Step 2.1) When the key signal is ≥2, the electric trailer enters the wake-up mode, performs a self-test on the low voltage of each component of the electric trailer, and enters the fault mode if a problem is found in the self-test.

[0013] Step 2.2) After each component self-tests normally, each high-voltage relay of the electric trailer closes in sequence. If a high-voltage relay is faulty, it enters fault mode. If the high-voltage relay works normally, the electric trailer enters ready mode and the DC-DC converter of the electric trailer is enabled.

[0014] Furthermore, the different vehicle speed conditions include starting acceleration, medium-speed acceleration, low-speed acceleration, overtaking acceleration, hill-climbing acceleration, and continuous hill-climbing acceleration.

[0015] Further, in step 6), the following parameters are set: vehicle speed threshold parameter V1 for vehicle start-up acceleration, vehicle speed threshold parameter V2 for vehicle medium-speed acceleration, vehicle speed threshold parameter V3 for vehicle uphill acceleration, vehicle speed threshold parameter V4 for vehicle continuous uphill acceleration, acceleration threshold parameter a1 for low-speed acceleration, accelerator pedal opening calibration threshold parameter Pb, and time threshold parameters T1, T2, T3, T4, T5, and T6 for calibrating cumulative ACC_Ped≥Pb; the conditions for determining Power_Mode=1 include the following: a) When the parameters acquired by the electric trailer satisfy Velocity < V1 and ACC_Ped ≥ Pb and duration ≥ T1; b) When the parameters acquired by the electric trailer satisfy Velocity > V2 and ACC_Ped ≥ Pb and duration ≥ T2; c) When the parameters obtained by the electric trailer satisfy V1≤Velocity≤V2 and ACC_Ped≥Pb and the duration≥T3 and the vehicle acceleration≤a1; d) When the parameters acquired by the electric trailer satisfy ACC_Ped≥Pb and the duration≥T4; e) When the parameters acquired by the electric trailer satisfy Velocity < V3 and ACC_Ped ≥ Pb and duration ≥ T5; f) When the parameters acquired by the electric trailer satisfy Velocity < V4 and ACC_Ped ≥ Pb and duration ≥ T6; If any one of the conditions a) to f) above is met, Power_Mode is determined to be 1.

[0016] Preferably, the vehicle speed threshold parameter V1 < V3 < V4 < V2.

[0017] Furthermore, the tractor gear position panel signals include forward gear, reverse gear, and neutral gear.

[0018] As can be seen from the above description of the structure of the present invention, compared with the prior art, the present invention has the following advantages: 1. The electric trailer of this invention obtains parameters such as key, gear position, vehicle speed, accelerator pedal, brake pedal, steering wheel, and yaw rate by communicating with the tractor vehicle. Based on these parameters, the driver's driving behavior is judged. Based on the vehicle's large steering or tilting conditions, a safety condition is set: Steering_Wheel_Angle < A_steer and Yaw_ang_velocity < V_ang. Only when the safety condition is met, ensuring that the vehicle is not in a large steering or tilting situation, will the electric trailer's VCU control the motor to output braking torque or driving torque to provide braking or driving force to the vehicle. This ensures the vehicle's safety, stability, and smoothness while improving its economy and power.

[0019] 2. This invention standardizes and divides complex driving conditions, defines different speed ranges, and determines whether the driver needs high power based on different speed ranges, accelerator pedal opening and duration. Under the premise of ensuring vehicle safety and stability, it controls the output drive torque of the electric trailer motor to provide assistance to the vehicle, making the entire driving process safer, more stable and smoother.

[0020] 3. Before the electric trailer of this invention enters the drive mode after being powered on, it sets up two self-testing methods based on the key signal. First, it powers on each component of the electric trailer with low voltage and performs a self-test. Only after the self-test is passed will the high-voltage relays be closed in sequence until all high-voltage relays are working normally. Only then will it enter the ready mode and enable DC-DC converter, thereby further ensuring the safety of the electric trailer. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the control logic for steps 1) to 3) of the present invention.

[0022] Figure 2 This is a schematic diagram of the control logic for steps 4) to 6) of the present invention. Detailed Implementation

[0023] The specific implementation of the embodiments of the present invention will now be described with reference to the accompanying drawings.

[0024] Reference Figure 1 and Figure 2 A new energy electric trailer drive and braking control method is proposed, which integrates components such as electric drive axle, multi-function unit, power battery, power battery BMS, trailer VCU, battery water cooling unit, and motor cooling system on the electric trailer. Its specific circuit structure is basically the same as that of the transmission electric trailer, and will not be described in detail here.

[0025] Reference Figure 1 and Figure 2 In this invention, the electric trailer VCU communicates with the tractor VCU via CAN. The electric trailer VCU acquires the tractor VCU's key signal, tractor gear panel signal, handbrake signal, vehicle speed signal parameter Velocity, accelerator pedal opening signal parameter ACC_Ped, brake pedal opening signal parameter Bsk, steering wheel angle parameter Steering_Wheel_Angle, and yaw rate parameter Yaw_angvelocity, which are used to determine the driver's driving behavior.

[0026] Specifically, key signals 1, 2, 3, or 4 correspond to the OFF, ACC, ON, or START positions of the key, respectively; the tractor gear panel signals include forward, reverse, and neutral. Furthermore, the steering wheel angle threshold A_steer and yaw rate threshold V_ang are set based on conditions of large steering or tilting of the vehicle; the accelerator pedal opening signal and duration at different vehicle speeds determine whether high power is required, and the trailer power mode parameter Power_Mode is set. If Power_Mode=1, indicating a need for high power, the trailer power mode is activated.

[0027] Reference Figure 1 and Figure 2 The specific steps of this invention are as follows: Step 1) The electric trailer is powered by low voltage. When the key signal = 1 and Velocity < 1, the trailer is in power-off mode.

[0028] Step 2) When the key signal is ≥2, the electric trailer enters the wake-up mode, powers on the electric trailer and performs a self-test. If the self-test is normal, it enters the ready mode; otherwise, it enters the fault mode.

[0029] This step can be divided into two parts: first, a low-voltage power-on self-test is performed, followed by closing the high-voltage relay. This distributed self-test of low and high voltage further improves vehicle safety. Specifically: Step 2.1) When the key signal is ≥2, the electric trailer enters the wake-up mode, performs a self-test on the 24V low voltage power supply of each component of the electric trailer, and enters the fault mode if there is a problem in the self-test.

[0030] Step 2.2) After each component self-tests normally, each high-voltage relay of the electric trailer closes in sequence. If a high-voltage relay is faulty, it enters fault mode. If the high-voltage relay works normally, the electric trailer enters ready mode and the DC-DC converter of the electric trailer is enabled.

[0031] Step 3) When the key signal is ≥3 and the Bsk acquired by the electric trailer is >0, the electric trailer enters the drive mode.

[0032] Step 4) When the electric trailer enters the drive mode, if the handbrake signal = 0, that is, the handbrake is released, and the tractor gear panel signal = 1, the tractor gear is in forward gear, and the electric trailer enters the driving mode.

[0033] In this embodiment, when the tractor gear panel signal = 1, the tractor gear panel signal is in D gear, i.e., the vehicle is in forward gear; when the tractor gear panel signal = 2, the tractor gear panel signal is in N gear, i.e., the vehicle is in neutral gear; when the tractor gear panel signal = 3, the tractor gear panel signal is in R gear, i.e., the vehicle is in reverse gear.

[0034] Step 5) In the electric trailer driving mode, when the electric trailer obtains Bsk > 0, if the electric trailer obtains Steering_Wheel_Angle < A_steer and Yaw_ang_velocity < V_ang, then the electric trailer enters braking mode. The electric trailer VCU obtains the braking torque Torque_Bsk corresponding to the current brake pedal opening based on the brake pedal opening and vehicle speed interpolation braking torque map table, and calculates the output motor torque TM_rq as: TM_rq = Torque_Bsk; if the electric trailer obtains Steering_Wheel_Angle ≥ A_steer or Yaw_ang_velocity ≥ V_ang, the electric trailer VCU controls the output motor braking torque TM_rq as: TM_rq = 0.

[0035] In this step of the invention, the conditions Steering_Wheel_Angle < A_steer and Yaw_ang_velocity < V_ang are set to determine whether the vehicle is making a large turn or tilting. From a safety perspective, when the vehicle is making a large turn or tilting, the tractor and electric trailer should not have any additional braking force interference. Only after the above conditions are ruled out can the motor of the electric trailer be allowed to output braking torque.

[0036] Furthermore, in this embodiment, the brake pedal opening and vehicle speed interpolated braking torque map is a braking torque value table calibrated based on the motor parameters used, engineering experience, and experimental tests. In braking mode, the motor's braking torque output is negative, thereby achieving brake energy recovery and improving fuel economy.

[0037] Step 6) In electric trailer driving mode, when the electric trailer obtains ACC_Ped≥0, if Power_Mode=1, and simultaneously satisfies Steering_Wheel_Angle<A_steer and Yaw_ang_velocity<V_ang, the electric trailer enters drive assist mode. The electric trailer VCU obtains the drive torque Torque_drive corresponding to the current accelerator pedal opening based on the interpolated drive torque map table of accelerator pedal opening and vehicle speed, and calculates the output motor torque TM_rq as: TM_rq=Torque_drive; if Power_Mode=1 is not satisfied, or Steering_Wheel_Angle≥A_steer, or Yaw_ang_velocity≥V_ang, the electric trailer VCU controls the output motor torque TM_rq to be: TM_rq=0.

[0038] Similarly, in this step of the present invention, setting Steering_Wheel_Angle < A_steer and Yaw_ang_velocity < V_ang is intended to determine whether the vehicle is making a large turn or tilting. From a safety perspective, when the vehicle is making a large turn or tilting, the tractor and electric trailer should not have additional driving force. Only after ruling out the above situations and determining that the vehicle has a high power demand, is the electric trailer's motor allowed to output driving torque to assist the tractor and electric trailer in driving, thereby improving power performance.

[0039] Furthermore, in this embodiment, the accelerator pedal opening and vehicle speed interpolation drive torque map table is a drive torque value table calibrated based on the motor parameters used, engineering experience, and experimental tests.

[0040] In this invention, determining whether a vehicle requires high power involves dividing complex and varied driving conditions into four categories: starting acceleration, medium-speed acceleration, low-speed acceleration, overtaking acceleration, hill-climbing acceleration, and continuous hill-climbing acceleration. The accelerator pedal depressor time is set and judged for each condition to determine whether the vehicle needs high power. The specific method is as follows: Set the vehicle speed threshold parameters V1 for initial acceleration, V2 for medium-speed acceleration, V3 for hill-climbing acceleration, and V4 for continuous hill-climbing acceleration, where V1 < V3 < V4 < V2. Set the acceleration threshold parameter a1 for low-speed acceleration, the accelerator pedal opening calibration threshold parameter Pb, and the time threshold parameters T1, T2, T3, T4, T5, and T6 for calibrating cumulative ACC_Ped ≥ Pb. The conditions for determining Power_Mode=1 include the following: a) When the parameters obtained by the electric trailer satisfy Velocity < V1 and ACC_Ped ≥ Pb and the duration ≥ T1; this condition corresponds to the vehicle start-up acceleration condition.

[0041] b) When the parameters acquired by the electric trailer satisfy Velocity>V2 and ACC_Ped≥Pb and the duration≥T2; this condition corresponds to the vehicle's medium-speed acceleration condition.

[0042] c) When the parameters obtained by the electric trailer satisfy V1≤Velocity≤V2 and ACC_Ped≥Pb and the duration≥T3 and the vehicle acceleration≤a1; this condition corresponds to the low-speed acceleration condition of the vehicle.

[0043] d) When the parameters obtained by the electric trailer satisfy ACC_Ped≥Pb and the duration≥T4; this condition corresponds to the vehicle overtaking acceleration condition and is also applicable to the vehicle high-speed acceleration condition.

[0044] e) When the parameters obtained by the electric trailer satisfy Velocity < V3 and ACC_Ped ≥ Pb and the duration ≥ T5; this condition corresponds to the vehicle's hill-climbing acceleration condition.

[0045] f) When the parameters obtained by the electric trailer satisfy Velocity < V4 and ACC_Ped ≥ Pb and the duration ≥ T6; this condition corresponds to the vehicle's continuous uphill acceleration condition.

[0046] If any one of the conditions a) to f) above is met, Power_Mode is determined to be 1.

[0047] This invention standardizes and divides complex driving conditions, defines different speed ranges, and determines whether the driver needs high power based on different speed ranges, accelerator pedal opening and duration. Under the premise of ensuring vehicle safety and stability, it controls the output drive torque of the electric trailer motor to provide assistance to the vehicle, making the entire driving process extremely safe, stable and smooth.

[0048] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A method for driving and braking control of a new energy electric trailer, characterized in that: The electric trailer VCU communicates with the tractor VCU via CAN. The electric trailer VCU obtains the tractor VCU's key signal, tractor gear panel signal, handbrake signal, vehicle speed signal parameter Velocity, accelerator pedal opening signal parameter ACC_Ped, brake pedal opening signal parameter Bsk, steering wheel angle parameter Steering_Wheel_Angle, and yaw rate parameter Yaw_angvelocity. When the key signal = 1, 2, 3, or 4, it corresponds to the OFF, ACC, ON, or START positions of the key, respectively. The steering wheel angle threshold A_steer and yaw rate threshold V_ang are set based on the vehicle's large steering or tilting conditions. The accelerator pedal opening signal and duration at different vehicle speeds determine whether high power is needed, and the trailer power mode parameter Power_Mode is set. If Power_Mode = 1, indicating high power is required, the trailer power mode is entered. The specific steps are as follows: Step 1) The electric trailer is powered by low voltage. When the key signal = 1 and Velocity < 1, the trailer is in power-off mode. Step 2) When the key signal is ≥2, the electric trailer enters the wake-up mode, powers on the electric trailer and performs a self-test. If the self-test is normal, it enters the ready mode; otherwise, it enters the fault mode. Step 3) When the key signal is ≥3 and the Bsk acquired by the electric trailer is >0, the electric trailer enters the drive mode; Step 4) When the electric trailer enters the drive mode, if the handbrake signal = 0, that is, the handbrake is released, and the signal on the tractor's gear panel is in forward gear, the electric trailer enters the driving mode. Step 5) In the electric trailer driving mode, when the electric trailer obtains Bsk > 0, if the electric trailer obtains Steering_Wheel_Angle < A_steer and Yaw_ang_velocity < V_ang, then the electric trailer enters braking mode. The electric trailer VCU obtains the braking torque Torque_Bsk corresponding to the current brake pedal opening based on the brake pedal opening and vehicle speed interpolation braking torque map table, and calculates the output motor torque TM_rq as: TM_rq = Torque_Bsk; if the electric trailer obtains Steering_Wheel_Angle ≥ A_steer or Yaw_ang_velocity ≥ V_ang, the electric trailer VCU controls the output motor torque TM_rq as: TM_rq = 0; Step 6) In electric trailer driving mode, when the electric trailer obtains ACC_Ped≥0, if Power_Mode=1, and simultaneously satisfies Steering_Wheel_Angle<A_steer and Yaw_ang_velocity<V_ang, the electric trailer enters drive assist mode. The electric trailer VCU obtains the drive torque Torque_drive corresponding to the current accelerator pedal opening based on the interpolated drive torque map table of accelerator pedal opening and vehicle speed, and calculates the output motor torque TM_rq as: TM_rq=Torque_drive; if Power_Mode=1 is not satisfied, or Steering_Wheel_Angle≥A_steer, or Yaw_ang_velocity≥V_ang, the electric trailer VCU controls the output motor torque TM_rq as: TM_rq=0.

2. The method for driving and braking control of a new energy electric trailer according to claim 1, characterized in that: Step 2) includes two steps: Step 2.1) When the key signal is ≥2, the electric trailer enters the wake-up mode, performs a self-test on the low voltage of each component of the electric trailer, and enters the fault mode if a problem is found in the self-test. Step 2.2) After each component self-tests normally, each high-voltage relay of the electric trailer closes in sequence. If a high-voltage relay is faulty, it enters fault mode. If the high-voltage relay works normally, the electric trailer enters ready mode and the DC-DC converter of the electric trailer is enabled.

3. The method for driving and braking control of a new energy electric trailer according to claim 1, characterized in that: The different vehicle speed conditions include starting acceleration, medium-speed acceleration, low-speed acceleration, overtaking acceleration, hill-climbing acceleration, and continuous hill-climbing acceleration.

4. The method for driving and braking control of a new energy electric trailer according to claim 3, characterized in that: In step 6), the following parameters are set: vehicle speed threshold V1 for vehicle start-up acceleration, vehicle speed threshold V2 for vehicle medium-speed acceleration, vehicle speed threshold V3 for vehicle uphill acceleration, vehicle speed threshold V4 for vehicle continuous uphill acceleration, acceleration threshold a1 for vehicle low-speed acceleration, accelerator pedal opening calibration threshold Pb, and time thresholds T1, T2, T3, T4, T5, and T6 for calibrating cumulative ACC_Ped ≥ Pb. The conditions for determining Power_Mode=1 include the following: a) When the parameters acquired by the electric trailer satisfy Velocity < V1 and ACC_Ped ≥ Pb and duration ≥ T1; b) When the parameters acquired by the electric trailer satisfy Velocity > V2 and ACC_Ped ≥ Pb and duration ≥ T2; c) When the parameters obtained by the electric trailer satisfy V1≤Velocity≤V2 and ACC_Ped≥Pb and the duration≥T3 and the vehicle acceleration≤a1; d) When the parameters acquired by the electric trailer satisfy ACC_Ped≥Pb and the duration≥T4; e) When the parameters acquired by the electric trailer satisfy Velocity < V3 and ACC_Ped ≥ Pb and duration ≥ T5; f) When the parameters acquired by the electric trailer satisfy Velocity < V4 and ACC_Ped ≥ Pb and duration ≥ T6; If any one of the conditions a) to f) above is met, Power_Mode is determined to be 1.

5. The method for driving and braking control of a new energy electric trailer according to claim 4, characterized in that: The vehicle speed threshold parameters are V1 < V3 < V4 < V2.

6. The method for driving and braking control of a new energy electric trailer according to claim 1, characterized in that: The gear position panel signals of the tractor include forward gear, reverse gear, and neutral gear.

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