TCU master control two-gear pure electric commercial vehicle gear shifting control method

Abstract

The invention relates to the field of vehicle control of new energy vehicles, in particular to a TCU master control two-gear pure electric commercial vehicle gear shifting control method which comprises the steps that S1, a vehicle is powered on, a vehicle VCU, a TCU, an MCU, a BMS and all controllers of the vehicle are awakened, and after high voltage Ready is powered on, the TCU detects whether a driver requests to shift to a D gear or not; s2, the TCU collects vehicle state information in real time, S3, working condition recognition is conducted, the TCU recognizes the intention of a driver according to the collected accelerator pedal opening degree and brake pedal signals, and the current driving working condition is judged according to the collected vehicle speed and vehicle load information; the method comprises the steps of S1, carrying out gear shifting cooperative control, S4, generating a target gear instruction by the TCU based on a preset basic economy gear shifting curve in combination with a dynamic correction factor, and S5, carrying out gear shifting cooperative control, so that the defects in a single-gear reducer scheme and a multi-gear AMT scheme at the present stage are overcome.

Description

Technical Field

[0001] This invention relates to the field of vehicle control for new energy vehicles, specifically to a two-speed pure electric commercial vehicle shift control method controlled by a TCU master unit. Background Technology

[0002] Currently, the electrification of commercial vehicles, especially light trucks, is accelerating. Compared with passenger cars, electric light trucks have characteristics such as heavy load and complex operating conditions (frequent start-stop, hill climbing, and large load changes), which puts forward higher requirements for the power, economy and reliability of the drive system.

[0003] Currently, most pure electric light trucks on the market adopt single-speed reducer solutions and multi-speed AMT solutions. Among them, the single-speed reducer solution has a simple structure, low cost, and high reliability, and is the mainstream configuration. However, its disadvantage is that in order to meet the high torque requirements such as full-load climbing, the peak power and torque of the motor need to be very high. As a result, under commonly used medium and high speed cruising conditions, the motor operates in the inefficient range for a long time, resulting in high energy consumption and a significant reduction in driving range. At the same time, the high speed operation of the motor also brings noise and wear problems. The multi-speed AMT solution is usually 4 or 6 speeds, which borrows the technology of traditional fuel vehicle transmissions. Its advantage is that by switching between multiple gears, the motor can operate in the high-efficiency range more often, improving the range and power performance. Its disadvantages are complex structure, high cost, and complex shift control strategy (requiring coordination of motor, transmission, and clutch). Power interruption or shock may occur during shifting, affecting driving smoothness and cargo safety, and reliability is challenged.

[0004] Therefore, there is a technological gap that urgently needs to be addressed between the economic efficiency of single-speed solutions and the performance advantages of multi-speed AMT solutions: a two-speed transmission solution that is simple in structure, intelligent in control, moderate in cost, and can significantly improve the working efficiency of motors.

[0005] At present, a two-speed pure electric vehicle shift control method with TCU main control is proposed to solve the problems mentioned in the background technology. Summary of the Invention

[0006] The purpose of this invention is to provide a two-speed pure electric commercial vehicle shift control method controlled by a TCU. By integrating and processing vehicle status information through the TCU, a set of intelligent shift decisions that take into account driving intention, vehicle load and real-time efficiency are executed, and the drive motor MCU is coordinated to perform precise torque adjustment, thereby achieving fast, smooth and economical two-speed switching, effectively improving the overall performance and reliability of the vehicle.

[0007] A two-speed pure electric vehicle shift control method with TCU main control, the specific steps of which are as follows:

[0008] Step S1: Power on the vehicle, wake up the vehicle VCU, TCU, MCU, BMS and each controller. After the high voltage is ready, the TCU detects whether the driver requests to shift into D gear.

[0009] Step S2: The TCU collects vehicle status information in real time, including vehicle speed, accelerator pedal opening, brake pedal signal, motor speed and torque, and vehicle load information.

[0010] Step S3: Perform operating condition identification. The TCU identifies the driver's intention based on the collected accelerator pedal opening and brake pedal signals, and determines the current driving condition based on the collected vehicle speed and vehicle load information.

[0011] Step S4, Integrated shift decision: The TCU generates a target gear command based on a preset basic economic shift curve and combined with a dynamic correction factor. The dynamic correction factor corrects the basic economic shift curve according to the driver's intention, vehicle load and current driving conditions identified in step S3.

[0012] Step S5, perform shift coordination control: When the target gear generated in step S4 is inconsistent with the current gear, the TCU, as the main controller, performs the following steps in sequence:

[0013] Step S5.1, Torque Reduction Stage: The TCU sends a precise torque zeroing request to the MCU. The MCU controls the drive motor to quickly and smoothly reduce the output torque to zero and feeds back the actual torque and speed to the TCU.

[0014] Step S5.2, Disengagement Stage: After the motor torque meets the requirements, the TCU controls the transmission shift actuator to disengage to neutral.

[0015] In step S5.3, the TCU controls the motor to adjust its speed and pre-synchronize it with the target gear speed;

[0016] Step S5.4: The MCU feeds back the actual torque and speed to the TCU;

[0017] In step S5.5, the TCU determines the gear shift speed difference and controls the transmission actuator to engage the target gear;

[0018] Step S5.6, Torque Recovery Stage: The TCU calculates and requests the target drive torque based on the current accelerator pedal opening, and the MCU controls the motor torque to smoothly rise to the target value, restoring power output;

[0019] Step S6: Perform fault diagnosis and implement security policies.

[0020] Furthermore, the vehicle load information in step S2 is obtained directly through a load sensor.

[0021] Furthermore, the vehicle load information in step S2 is estimated by the relationship between the motor output torque and the vehicle acceleration.

[0022] Further defining the driver's intention in step S3, the identification includes smooth acceleration, rapid acceleration, cruising, and deceleration based on the accelerator pedal opening and its rate of change, and the current driving conditions include heavy-load uphill climbing, downhill driving, and low-speed crawling.

[0023] Further specifying, the basic economic shift curve in step S4 is a preset two-parameter shift map based on vehicle speed and accelerator pedal opening.

[0024] Further specifying, the dynamic correction factor in step S4 is: when a rapid acceleration intention is identified, upshifting is delayed; when a heavy load condition is identified, the upshifting speed threshold is increased; when a hill climbing condition is identified, upshifting is prohibited or downshifting is actively performed.

[0025] Further specifying, in step S5.3, the TCU calculates the target speed adjustment speed based on the difference between the current motor speed and the target gear speed, and sends a speed adjustment command to the MCU until the speed difference is less than a preset threshold.

[0026] Further defining the fault diagnosis and safety strategy in step S6, the TCU continuously monitors key parameters such as the position of the shift actuator and the synchronization status of the motor speed. If the shift timeout or an abnormality occurs, the TCU immediately interrupts the shift process, attempts to return to the original gear or enter the limp home mode, and records the fault code to ensure the basic driving safety of the vehicle.

[0027] The advantages of this invention compared to the prior art are as follows:

[0028] 1. By introducing multi-dimensional information such as load and driving intention, the basic economic shift curve is dynamically corrected, making the shift decision more in line with the actual working scenario, significantly improving the average working efficiency of the motor, improving vehicle economy, and extending the driving range.

[0029] 2. High shift smoothness: Controlled by the TCU, the motor torque is actively and precisely coordinated and controlled. The communication time is short and the response speed is fast, realizing a rapid and smooth transition of torque "first decrease and then increase" during the shift process. This greatly reduces the feeling of power interruption and shock, and improves driving comfort and cargo safety.

[0030] 3. Balance between system cost and reliability: Compared with multi-speed AMT, the two-speed system structure is greatly simplified; through optimized control strategies, the advantages of two speeds are fully utilized, achieving an excellent balance between cost, reliability and performance, making it very suitable for the pure e-commerce vehicle market.

[0031] 4. High adaptability: The strategy fully considers the typical working conditions of commercial vehicles, such as heavy load and hill climbing, and enhances the vehicle's environmental adaptability, power, and economic performance. Attached Figure Description

[0032] Figure 1 This is the logic control flowchart of the present invention;

[0033] Figure 2 This is a MAP diagram of the motor. Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0035] Example:

[0036] like Figure 1 As shown, a two-speed pure electric commercial vehicle with TCU main control is described, and the specific steps are as follows:

[0037] Step S1: Power on the vehicle, wake up the vehicle VCU, TCU, MCU, BMS and each controller. After the high voltage is ready, the TCU detects whether the driver requests to shift into D gear.

[0038] Step S2: The TCU collects and processes sensor signals and CAN bus information from the vehicle in real time. The vehicle status information includes vehicle speed, accelerator pedal opening, brake pedal signal, motor speed and torque, current gear status, battery SOC and vehicle load information. The vehicle load information is obtained directly by the load sensor or estimated by the relationship between motor output torque and vehicle acceleration.

[0039] Step S3: The vehicle starts. The TCU collects and processes sensor signals and CAN bus information from the whole vehicle in real time to identify the driving conditions. The TCU identifies the driver's intention based on the collected accelerator pedal opening and brake pedal signals, and determines the current driving conditions based on the collected vehicle speed and vehicle load information. The driver's intention includes smooth acceleration, rapid acceleration, cruising and deceleration identified based on the accelerator pedal opening and its rate of change. The current driving conditions include high-load climbing, downhill and low-speed crawling.

[0040] Step S4, Integrated Shift Decision: The TCU generates a target gear command based on a preset basic economic shift curve and a dynamic correction factor. The dynamic correction factor modifies the basic economic shift curve according to the driver's intention, vehicle load, and current driving conditions identified in step S3. The basic economic shift curve is a preset two-parameter shift map based on vehicle speed and accelerator pedal opening, designed to ensure the motor operates in its high-efficiency range. A table of some shift lines is shown below:

[0041] Throttle opening 0 5 10 20 30 40 50 60 70 80 90 100 Shifting from 1st to 2nd gear 2405 2415 2420 2430 2450 2460 2480 2510 2530 2550 2570 2590 Shift down from 2nd gear to 1st gear 820 830 840 850 860 870 880 890 900 910 920 930

[0042] The dynamic correction factors are as follows: when a rapid acceleration intention is detected, upshifting is delayed; when a heavy load condition is detected, the upshifting speed threshold is increased; when a hill climbing condition is detected, upshifting is prohibited or downshifting is actively performed.

[0043] Step S5, perform shift coordination control: when the target gear generated in step S4 is inconsistent with the current gear, the TCU, as the main controller, coordinates the various execution components to perform the following steps in sequence;

[0044] Step S5.1, Torque Reduction Stage: The TCU sends a precise torque zeroing request to the MCU. The MCU controls the drive motor to quickly and smoothly reduce the output torque to zero and feeds back the actual torque and speed to the TCU.

[0045] Step S5.2, Disengagement Stage: After the motor torque meets the requirements, the TCU controls the transmission shift actuator to disengage to neutral.

[0046] In step S5.3, the TCU controls the motor to adjust its speed and pre-synchronize it with the target gear speed. The TCU calculates the target speed adjustment speed based on the difference between the current motor speed and the target gear speed, and sends a speed adjustment command to the MCU until the speed difference is less than a preset threshold.

[0047] Step S5.4: The MCU feeds back the actual torque and speed to the TCU;

[0048] In step S5.5, the TCU determines the gear shift speed difference and controls the transmission actuator to engage the target gear;

[0049] Step S5.6, Torque Recovery Stage: The TCU calculates and requests the target drive torque based on the current accelerator pedal opening, and the MCU controls the motor torque to smoothly rise to the target value, restoring power output;

[0050] Step S6: Perform fault diagnosis and implement safety strategies. The TCU continuously monitors key parameters such as the position of the shift actuator and the synchronization status of the motor speed. If the shift timeout or abnormality occurs, the TCU immediately interrupts the shift process, attempts to return to the original gear or enter the limp home mode, and records the fault code to ensure the basic driving safety of the vehicle.

[0051] In the above embodiment, the TCU, as the main controller, establishes a high-speed communication link with controllers such as VCU, MCU, and BMS via the CAN bus. The communication cycle is set to 10 milliseconds to ensure real-time transmission and execution feedback of shift commands. When the vehicle is in a heavy-load start-up condition, the TCU recognizes that the load sensor signal exceeds 80% of the rated load and the accelerator pedal opening change rate is greater than 30% per second. It determines that the intention to accelerate rapidly is superimposed on the heavy-load condition. At this time, the dynamic correction factor increases the vehicle speed threshold for shifting from 1st to 2nd gear from the basic value of 2590 rpm to 2850 rpm, so that the motor can continuously output large torque during the start-up acceleration phase and avoid insufficient power caused by upshifting too early.

[0052] In the shift coordination control process of step S5, a ramp-down strategy is adopted in the torque reduction stage. The TCU calculates the torque reduction slope based on the current motor speed and the target speed adjustment time, and sends a torque request value that decreases cycle by cycle to the MCU. The MCU reduces the output torque from the peak to below 50 N / m within 200 milliseconds, while keeping the motor speed stable. In the disengagement stage, the TCU monitors the feedback from the shift actuator position sensor. When the shift fork displacement reaches the neutral position and there is no rebound for 20 milliseconds, the disengagement is confirmed to be complete. In the motor speed adjustment stage, the TCU calculates the target motor speed based on the target gear ratio and the current vehicle speed, and generates a speed adjustment command using a proportional-integral control algorithm. After the MCU responds, it adjusts the motor speed. When the absolute value of the speed difference is less than 50 revolutions per minute and lasts for 100 milliseconds, it is determined that the speed synchronization is complete.

[0053] During gear engagement, the TCU controls the shift actuator to drive the synchronizer at a preset speed, while simultaneously monitoring motor speed fluctuations in real time. If the speed difference exceeds the threshold again during gear engagement, the gear engagement action is immediately paused and the speed regulation process is retried. During torque recovery, an S-shaped curve rising strategy is adopted, with a slow initial rise rate to avoid impact, followed by acceleration to 80% of the target torque, and finally slowly approaching the target value. The entire torque recovery process is controlled within 300 milliseconds, achieving seamless power transition.

[0054] The fault diagnosis module runs continuously throughout the entire shift cycle, with multiple timeout thresholds: 500 milliseconds for the torque reduction phase, 400 milliseconds for the disengagement phase, 800 milliseconds for the speed adjustment phase, and 600 milliseconds for the engagement phase. If any phase times out or an actuator position abnormality or speed synchronization failure is detected, the TCU immediately executes the fault handling procedure, prioritizing an attempt to return to the original gear. If the original gear cannot be returned to, it forces the vehicle into neutral and limits the motor torque output to 30% of the rated value, entering limp-home mode. Simultaneously, a fault warning message is displayed on the instrument panel to remind the driver to have the vehicle inspected promptly.

[0055] The above provides a detailed description of a two-speed pure electric vehicle shift control method with TCU master control provided by the present invention. The description of specific embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A two-speed pure electric commercial vehicle shift control method controlled by a TCU master unit, characterized in that: The specific steps are as follows: Step S1: Power on the vehicle, wake up the vehicle VCU, TCU, MCU, BMS and each controller. After the high voltage is ready, the TCU detects whether the driver requests to shift into D gear. Step S2: The TCU collects vehicle status information in real time, including vehicle speed, accelerator pedal opening, brake pedal signal, motor speed and torque, current gear status, battery SOC, and vehicle load information. Step S3: Perform operating condition identification. The TCU identifies the driver's intention based on the collected accelerator pedal opening and brake pedal signals, and determines the current driving condition based on the collected vehicle speed and vehicle load information. Step S4, Integrated shift decision: The TCU generates a target gear command based on a preset basic economic shift curve and combined with a dynamic correction factor. The dynamic correction factor corrects the basic economic shift curve according to the driver's intention, vehicle load and current driving conditions identified in step S3. Step S5, perform shift coordination control: When the target gear generated in step S4 is inconsistent with the current gear, the TCU, as the main controller, performs the following steps in sequence: Step S5.1, Torque Reduction Stage: The TCU sends a precise torque zeroing request to the MCU. The MCU controls the drive motor to quickly and smoothly reduce the output torque to zero and feeds back the actual torque and speed to the TCU. Step S5.2, Disengagement Stage: After the motor torque meets the requirements, the TCU controls the transmission shift actuator to disengage to neutral. In step S5.3, the TCU controls the motor to adjust its speed and pre-synchronize it with the target gear speed; Step S5.4: The MCU feeds back the actual torque and speed to the TCU; In step S5.5, the TCU determines the gear shift speed difference and controls the transmission actuator to engage the target gear; Step S5.6, Torque Recovery Stage: The TCU calculates and requests the target drive torque based on the current accelerator pedal opening, and the MCU controls the motor torque to smoothly rise to the target value, restoring power output; Step S6: Perform fault diagnosis and implement security policies.

2. The two-speed pure electric commercial vehicle shift control method with TCU main control according to claim 1, characterized in that: The vehicle load information in step S2 is obtained directly through the load sensor.

3. The two-speed pure electric commercial vehicle shift control method with TCU main control according to claim 1, characterized in that: The vehicle load information in step S2 is estimated by the relationship between the motor output torque and the vehicle acceleration.

4. The two-speed pure electric commercial vehicle shift control method with TCU main control according to claim 1, characterized in that: The driver's intention identification in step S3 includes smooth acceleration, rapid acceleration, cruising, and deceleration identified based on the accelerator pedal opening and its rate of change. The current driving conditions include heavy-load uphill climbing, downhill driving, and low-speed crawling.

5. A two-speed pure electric commercial vehicle shift control method with TCU main control according to claim 4, characterized in that... The basic economic shift curve in step S4 is a preset two-parameter shift map based on vehicle speed and accelerator pedal opening.

6. The two-speed pure electric commercial vehicle shift control method with TCU main control according to claim 1, characterized in that: The dynamic correction factor in step S4 is as follows: when a rapid acceleration intention is detected, upshifting is delayed; when a heavy load condition is detected, the upshifting speed threshold is increased; when a hill climbing condition is detected, upshifting is prohibited or downshifting is actively performed.

7. The shift control method for a two-speed pure electric commercial vehicle controlled by a TCU master as described in claim 1, characterized in that: In step S5.3, the TCU calculates the target speed adjustment speed based on the difference between the current motor speed and the target gear speed, and sends a speed adjustment command to the MCU until the speed difference is less than a preset threshold.

8. The shift control method for a two-speed pure electric commercial vehicle controlled by a TCU master as described in claim 1, characterized in that: The fault diagnosis and safety strategy in step S6 is as follows: The TCU continuously monitors key parameters such as the position of the shift actuator and the synchronization status of the motor speed. If the shift timeout or abnormality occurs, the TCU immediately interrupts the shift process, attempts to return to the original gear or enter the limp home mode, and records the fault code to ensure the basic driving safety of the vehicle.

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