Fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountains and hills

Abstract

The invention relates to a fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountains and hills. Comprising a sectional chassis, a waist bowing and twisting device, a rear wheel steering device, a hydrogen fuel cell system, an electronic control unit, a DCDC converter, a driving motor controller, a clutch, a driving motor, a power battery, an electric agricultural implement controller and an inverter. The fuel cell tractor and power recovery auxiliary driving electric agricultural implement system suitable for mountains and hills has the advantages of zero emission, high energy utilization efficiency, flexibility, practicability and the like. With continuous progress of the technology and reduction of the cost, the system is expected to be widely applied and popularized in the agricultural field in the future.

Description

Technical Field

[0001] The present invention relates to the technical field of mountain and hilly tractors, and specifically to a fuel cell tractor applicable to mountains and hills and a power recovery auxiliary drive electric agricultural implement system. Background Art

[0002] With the increasing global emphasis on clean energy and environmental protection, as well as the intensive introduction of energy conservation and emission reduction policies, the electrification of agricultural machinery has become an inevitable trend in the future development of agricultural machinery.

[0003] As a kind of clean energy, hydrogen fuel cells have the advantages of high energy density, long endurance mileage, short refueling time, etc., and are very suitable for application in high-power agricultural machinery. A hydrogen fuel cell tractor uses a hydrogen fuel cell as the main power source, and converts hydrogen into electric energy through a chemical reaction to drive the tractor. This technology is not only environmentally friendly and pollution-free, but also has a high energy conversion efficiency, which can reach more than 50%, far higher than the efficiency of traditional internal combustion engines. The hydrogen refueling time of a hydrogen fuel cell tractor is short, usually only taking a few minutes to complete, which greatly improves the operation efficiency. In addition, a hydrogen fuel cell tractor also has the advantages of low noise and small vibration, improving the driving comfort. Therefore, hydrogen fuel cells have broad application prospects in the field of tractors.

[0004] At the same time, in the prior art, during the operation of traditional agricultural implements, especially on narrow roads such as mountains and hills, there are frequent uphill and downhill movements. Traditional tractors have the following problems in hilly terrain: (1) The center of gravity is too high, resulting in a risk of rollover (the rollover rate increases by 60% when the slope > 15°); (2) The mechanical transmission system cannot recover energy, and the energy consumption loss during downhill is up to 40%.

[0005] Therefore, in order to solve the above problems, it is necessary to develop a system that is flexible in turning and going uphill and downhill, uses hydrogen fuel cells, and can recover and utilize the energy generated during the operation of the tractor to improve the energy utilization efficiency and extend the endurance mileage. Summary of the Invention

[0006] To solve the above problems, the purpose of the present invention is to provide a fuel cell tractor applicable to mountains and hills and a power recovery auxiliary drive electric agricultural implement system. The tractor has a segmented chassis, a folding and twisting device, and a rear-wheel steering device, and can flexibly go uphill and downhill and turn on narrow roads such as mountains and hills. At the same time, the system is also designed with an energy recovery device, which can efficiently convert, recover, and utilize the energy generated when the tractor decelerates and brakes during the driving operation of the tractor, as well as the energy of the deceleration of agricultural implements. These stored energies can provide power support for agricultural implements during subsequent operations, thereby realizing the recycling of energy.

[0007] A fuel cell tractor applicable to mountainous and hilly areas and a power recovery assisted drive electric agricultural implement system, comprising a segmented chassis, a waist folding and twisting device, a rear-wheel steering device, a hydrogen fuel cell system, a power battery, an electronic control unit (VCU), a DC / DC converter, a drive motor controller, a drive motor, an electric agricultural implement controller, and an inverter;

[0008] The segmented chassis includes a front carriage and a rear carriage. A front wheel is installed on each of the left and right sides of the front carriage, and a rear wheel is installed on each of the left and right sides of the rear carriage. The front carriage and the rear carriage are connected by a waist folding and twisting device;

[0009] The waist folding and twisting device includes a hydraulic actuator, a universal hinge, and a steering angle sensor,

[0010] Further, the maximum bending angle of the waist folding and twisting device is ±30°. The material of the universal hinge is high-strength alloy steel. The steering angle sensor is arranged on the steering column of the steering wheel.

[0011] The rear-wheel steering device is arranged between the two rear wheels and is softly connected to the two rear wheels.

[0012] The rear-wheel steering device includes a steering execution mechanism, a vehicle speed sensor, and a rear-wheel steering angle sensor. The steering execution mechanism includes a rear-wheel steering motor, a steering tie rod, and a steering knuckle. The steering knuckle is softly connected to the two rear wheels; the rear-wheel steering device is controlled by the electronic control unit (VCU).

[0013] Further, the rear-wheel steering motor adopts a servo motor, and the accuracy of the rear-wheel steering angle sensor is ±0.5°.

[0014] The rear-wheel steering device controls the steering angle of the rear wheels through an electronic or mechanical device, and determines the steering direction and angle of the rear wheels according to parameters such as the vehicle speed and steering angle respectively collected by the vehicle speed sensor and the rear-wheel steering angle sensor.

[0015] The power output by the hydrogen fuel cell system is first stabilized by the DC / DC converter and output as usable direct current, and then converted into high-voltage alternating current by the inverter and output to the waist folding and twisting device, the rear-wheel steering device, the drive motor controller, and the electric agricultural implement controller respectively. The drive motor controller is electrically connected to the drive motor, and the electric agricultural implement controller is electrically connected to the electric agricultural implement. Among them, the drive motor provides power for the tractor to travel.

[0016] The power output from the power battery first passes through a DC / DC converter to stabilize the voltage and output usable direct current, and then is converted into alternating current through an inverter and output to the folding and twisting device, rear-wheel steering device, electronic control unit, drive motor controller, and electric agricultural implement controller respectively. The hydrogen fuel cell system and the power battery are both connected to the electronic control unit via the CAN bus and controlled by the VCU.

[0017] The electronic control unit is signal-connected to the folding and twisting device, rear-wheel steering device, electric agricultural implement controller, and drive motor controller respectively via the CAN bus.

[0018] Furthermore, the hydrogen fuel cell system and the power battery are installed at the front of the tractor frame, and the electronic control unit (VCU) is installed on one side of the hydrogen energy fuel cell system; the drive motor is installed in the rear compartment.

[0019] The electric agricultural implement controller includes a driver, an electronic control module, an energy output management system, a current sensor, a voltage sensor, and a temperature sensor. Among them, the current sensor and the voltage sensor are both installed on the power output interface of the electric agricultural implement controller, and the temperature sensor is installed on the drive motor of the electric agricultural implement.

[0020] Furthermore, the electronic control unit (VCU) is configured with a central processor, a storage module, and a communication interface; the VCU is signal-connected to the drive motor controller and the electric agricultural implement controller via the CAN bus. Among them, the VCU is programmed to perform: real-time monitoring of the operating state parameters of the electric agricultural implement, including but not limited to the motor speed, torque output, and battery voltage of the electric agricultural implement; generating multi-dimensional control instructions according to a preset operation algorithm, and the instructions at least include a speed adjustment instruction, a steering control instruction, and an operation parameter adjustment instruction; transmitting instruction signals to the electric agricultural implement controller or the drive motor controller via the CAN bus protocol.

[0021] The operation parameter adjustment instructions include: a tillage depth adjustment module, an operation speed coordination module, an energy optimization module, and a fault diagnosis unit; the tillage depth adjustment module is configured to adjust the operation state of the electric agricultural implement according to the data of the soil resistance sensor, and the soil resistance sensor is installed on the electric agricultural implement; the operation speed coordination module is used to match the proportional relationship between the traveling speed of the tractor and the operation speed of the agricultural implement; the energy optimization module dynamically adjusts the maximum output power threshold based on the remaining power of the battery system. The fault diagnosis unit is configured to: monitor the internal temperature, current fluctuation, and insulation impedance parameters of the electric agricultural implement controller; when over-temperature (>85°C), over-current (current exceeding 150% of the rated value), or insulation failure (impedance <5 MΩ) is detected, trigger a hierarchical protection mechanism, and the hierarchical protection mechanism includes: in the first stage, reduce the output power to 50% and issue a warning signal; in the second stage, cut off the power output and record the fault code; in the third stage, activate the emergency braking device.

[0022] The electronic control unit (VCU):

[0023] (1) The VCU communicates with the electric agricultural implement controller through the CAN bus, supports the ISO 11783 protocol, and the maximum communication delay ≤ 50 ms.

[0024] (2) The electronic control unit (VCU) mainly integrates control elements, is responsible for controlling the tractor drive motor, the tractor transmission, the operation equipment, and precisely controlling the bending angle required by the folding and twisting mechanism of the tractor when going uphill and downhill. The VCU dynamically adjusts the bending angle of the folding and twisting device according to the terrain slope sensor signal. The bending angle calculation formula is θ = arctan(h / L), where h is the height difference between the front wheel and the rear wheel, and L is the wheelbase.

[0025] The electronic control unit (VCU) can precisely control the output power adjustment of the hydrogen fuel cell system, and dynamically match the energy supply ratio of the hydrogen fuel cell system and the power battery according to the required power.

[0026] The described electronic control unit (VCU) integrates an electronic control output control module, which is used to monitor and control the working state of the power output system, including the input / output voltage and current, working temperature, etc. of the inverter; this module controls the change of the power output type through the CAN bus according to the power output set by the driver; this module receives feedback signals such as the required electric power, vehicle speed, and driving path of the electric agricultural implement operation, and sends them to the electronic control unit (VCU) for automatically adjusting the operation state of the tractor.

[0027] When driving on relatively narrow roads such as in mountainous and hilly areas, the auxiliary system actively intervenes through the electronic control unit (VCU) to drive the rear-wheel steering device.

[0028] Furthermore, the system also includes a GPS (Global Positioning System), an IMU (Inertial Measurement Unit), wheel speed sensors, and a terrain slope sensor. The GPS is installed on the top of the tractor, and the IMU is installed in the middle of the tractor frame or near the drive motor. The terrain slope sensor is set on the chassis and can monitor the change of terrain slope in real time so that the VCU (Vehicle Control Unit) can adjust the rear-wheel steering strategy according to different slopes. The wheel speed sensors are set inside the wheel hubs and can accurately measure the wheel rotation speed, providing data support for calculating the vehicle driving state. The IMU inertial measurement unit is used for terrain prediction compensation. The IMU can obtain the vehicle's attitude and motion information in real time. By analyzing and processing these data, it can predict the vehicle's steering demand in advance and adjust the rear-wheel steering strategy in advance to better adapt to complex terrain changes. When the driver turns the steering wheel, the electronic control unit (VCU) judges the steering intention according to the signal of the steering angle sensor and determines the appropriate rear-wheel steering strategy in combination with the signal collected by the wheel speed sensors. Because at different vehicle speeds, the amplitude and timing of rear-wheel steering are different. At low speeds, the rear wheels may need to steer in the opposite direction to the front wheels to reduce the turning radius. At high speeds, the rear wheels usually steer in the same direction as the front wheels to improve the vehicle's stability.

[0029] The above functions adopt a double-closed-loop control structure:

[0030] Outer loop (path tracking): Calculate the target steering angle based on the Bicycle model:

[0031]

[0032] In the formula: L is the wheelbase, K is the path curvature, v is the vehicle speed, and g is the acceleration due to gravity

[0033] Inner loop (execution control): Adjust the drive motor speed through the PID fuzzy algorithm:

[0034]

[0035] u(t): The output value of the controller. In the scenario of drive motor speed control, this output value is usually used to control the voltage, current, or duty cycle of the pulse width modulation (PWM) signal of the drive motor to adjust the drive motor speed.

[0036] K P : Proportional coefficient. It is multiplied by the current error e(t) for a quick response to the error. The role of the proportional term is to respond proportionally to the current error. The larger the error, the larger the output of the proportional term, so that the system quickly approaches the target value. However, if K P is too large, the system may produce overshoot and even cause the system to be unstable.

[0037] K i: Integral coefficient. The integral term integrates the error over time, that is, accumulates the error over a period of time in the past. Its function is to eliminate the steady-state error of the system, because as long as there is an error, the integral term will continue to accumulate until the error is eliminated. However, the integral term may cause the system response to slow down and may cause integral saturation problems in some cases.

[0038] K d : Differential coefficient. The derivative term is the rate of change of the error, which reflects the changing trend of the error. By calculating the rate of change of the error, the changing direction of the error can be predicted in advance, so as to make adjustments before the error becomes very large, improve the dynamic response of the system, reduce overshoot, and improve the stability of the system.

[0039] e(t): The error value at the current time t, that is, the difference between the target rotational speed and the actual rotational speed.

[0040] The electronic control unit (VCU) transmits control instructions to the steering actuator in the rear-wheel steering device through electrical signals. The steering actuator is an electric power steering motor or a hydraulic control unit.

[0041] After receiving the instruction from the electronic control unit (VCU), the steering actuator drives the rear-wheel steering device to work. The rear-wheel steering motor rotates a certain angle according to the instruction and drives the rear wheels to steer through the steering tie rod.

[0042] The electronic control unit (VCU) is signal-controlled and connected to the hydrogen fuel cell system and the power battery through the CAN bus respectively;

[0043] Both the hydrogen fuel cell system and the power battery are controlled by the electronic control unit (VCU). The electronic control unit (VCU) will switch the drive mode according to the driver's needs in different situations such as operation and endurance.

[0044] (1) Mode switching based on power demand, specifically including the following two modes:

[0045] ① Low-load steady-state operation mode (driven by the power battery)

[0046] Trigger conditions:

[0047] The state of charge (SOC) of the power battery ≥ 40%,

[0048] Or the current agricultural implement power demand ≤ 70% of the maximum continuous output power of the power battery,

[0049] Or the operation slope detected by the slope sensor ≤ 10°

[0050] Control strategy: Turn off the hydrogen fuel cell system and supply power only by the power battery to reduce hydrogen consumption;

[0051] ② High-load / dynamic response mode (hybrid drive)

[0052] Trigger conditions:

[0053] The power demand of the agricultural implement suddenly increases (e.g., when the rotary tiller encounters a hard soil layer),

[0054] or the instantaneous output power of the power battery ≥ 80% of the rated value and lasts for 5 seconds,

[0055] or the slope sensor detects that the working slope ≥ 15° (extra traction is required),

[0056] Control strategy: The hydrogen fuel cell system and the power battery are connected in parallel to supply power. The basic power of the fuel cell is called first, and the power battery supplements the peak demand.

[0057] (2) Mode switching based on energy management, specifically including the following two modes:

[0058] ① Energy feedback priority mode

[0059] Trigger conditions:

[0060] The tractor is in a downhill or braking state,

[0061] or the SOC of the power battery ≤ 90%,

[0062] Control strategy: Disconnect the hydrogen fuel cell system, convert kinetic energy into electrical energy through the drive motor and feedback it to the power battery, and activate forced feedback when the slope > 20°.

[0063] ② Fuel cell preheating / charging mode

[0064] Trigger conditions:

[0065] The SOC of the power battery ≤ 30%,

[0066] or the ambient temperature < 5°C (the hydrogen fuel cell system needs to be preheated)

[0067] Control strategy: Start the hydrogen fuel cell system to charge the power battery, and at the same time preheat the fuel cell stack through the waste heat circulation system. After charging to SOC ≥ 50%, switch back to the pure electric mode.

[0068] (3) Mode switching based on the environment and equipment status, specifically including the following two modes:

[0069] ① High-temperature protection mode

[0070] Trigger conditions:

[0071] The temperature of the power battery ≥ 45°C or the temperature of the fuel cell coolant ≥ 75°C

[0072] Control strategy: Force the hydrogen fuel cell system to start and share the load, reduce the battery charge and discharge rate, and trigger the highest gear operation of the cooling system.

[0073] ② Fault tolerance mode

[0074] Trigger conditions:

[0075] The voltage volatility of the fuel cell > 15%,

[0076] or the voltage difference of the power battery cells > 0.2V

[0077] Control strategy: Lock the current energy supply mode and send a fault code to the CAN bus.

[0078] During the driving and operation of the tractor, the electronic control unit (VCU) has a memory function and can intelligently allocate the electric energy output according to different road surface conditions and the operation conditions of different electric agricultural implements.

[0079] The system also includes a power recovery system.

[0080] The power recovery auxiliary drive electric agricultural implement system, that is, the power recovery system, and the power recovery includes the power recovery during the driving of the tractor.

[0081] The power recovery during the driving of the tractor means that when the tractor decelerates and brakes during driving, after the driver outputs a deceleration command, the wheels still rotate under the action of inertia, and the power recovery system converts the kinetic energy of the wheels into the kinetic energy of the rotor of the drive motor. At this time, the motor changes from the drive state to the power generation state and stores the electricity in the power battery.

[0082] During agricultural production activities in complex terrains such as hilly mountains, such as plowing, sowing, fertilizing, and harvesting, the electronic control unit (VCU) controls the folding and twisting device through the CAN bus to achieve precise folding and steering of the wheels.

[0083] The present invention also provides a use method of the fuel cell tractor and the power recovery auxiliary drive electric agricultural implement system suitable for mountainous and hilly areas as described above, which is characterized in that it specifically includes the following steps:

[0084] Step 1: Before implementing the connection operation with the electric agricultural implement, it is necessary to carefully check the electrical equipment lines and mechanical connection components, confirm the required power type and rated working voltage parameters of the electric agricultural implement, and then complete the adaptation connection operation of the power output port and the control signal interface;

[0085] Step 2: Start the tractor power supply, and the electronic control unit immediately conducts a power-on self-check on the entire tractor and detects each part to ensure that there are no signal abnormalities and potential power output faults;

[0086] Step 3: The driver manually mounts the electric agricultural implement and precisely sets the electrical energy parameters and operation type required by the electric agricultural implement with the help of the electric agricultural implement controller. At the same time, the driver reasonably sets the power cut-off power threshold of the electric agricultural implement to effectively avoid potential dangerous situations;

[0087] Step 4: The driver enters the pre-planned operation route into the vehicle-mounted system according to the actual requirements of the upcoming operation. The vehicle-mounted system includes an electronic control unit;

[0088] Step 5: After the driver controls the tractor to reach the operation site and inputs the operation command, the power battery will output electrical energy to the electric agricultural implement via the electric agricultural implement controller to drive it to officially start the operation process;

[0089] If the electrical energy output by the power battery can meet the full-process operation requirements of the electric agricultural implement, the entire operation process will be supported by the independent power supply of the power battery;

[0090] When the electric agricultural implement controller monitors that the power of the power battery can no longer support the subsequent operation process, the electronic control unit will immediately coordinate the hydrogen fuel cell system and the power battery to work together to hybrid drive the electric agricultural implement;

[0091] If the power load required by the electric agricultural implement is too high and exceeds the single-load capacity of the power battery, the electronic control unit will directly activate the hybrid drive mode of the hydrogen fuel cell system and the power battery to ensure the stable operation of the electric agricultural implement;

[0092] During the driving process, due to the existence of many uphill and downhill road conditions on the special terrain roads in mountains and hills, when encountering an uphill section, the electronic control unit will precisely identify the uphill angle and control the folding and twisting mechanism to implement distributed control of the front and rear carriages to adjust the body posture to an appropriate angle that conforms to the operation requirements;

[0093] In the downhill stage, the power recovery system will be automatically activated to efficiently convert the kinetic energy generated during the downhill process into electrical energy to recharge the power battery;

[0094] When facing a narrow road that makes turning more difficult, the electronic control unit will rely on precise recognition ability and intelligent path planning algorithm to control the rear-wheel steering device to assist the driver to complete the turning operation smoothly;

[0095] Step 6. During driving and operation, if the instantaneous power output approaches or is about to exceed the maximum power limit value set in advance by the driver, the vehicle system will immediately trigger the early warning mechanism; if it is within the normal operating fluctuation range, the driver can manually cancel the early warning; if it is determined to be a fault state, the electric agricultural machinery controller will quickly cut off the power input of the electric agricultural machinery. At the same time, the power recovery system will be started synchronously to assist the electric agricultural machinery in achieving braking operations.

[0096] Compared with the prior art, the present invention has the following beneficial effects:

[0097] The present invention adopts a hydrogen fuel cell system and a power battery to provide power for tractors and electric agricultural machinery, and has a segmented chassis, a waist folding and twisting device, and a rear-wheel steering device, which solves the problems of traditional tractors having difficulty in driving and inflexible control on complex roads such as mountains and hills; in addition, a power recovery auxiliary system is adopted to reasonably distribute energy, reduce energy loss, and extend the cruising range. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Figure 1 This is a working diagram of a fuel cell tractor and a power recovery auxiliary drive electric agricultural implement system suitable for mountainous areas and hills according to the present invention;

[0099] Figure 2 It is a structural schematic diagram of a fuel cell tractor and a power recovery auxiliary drive electric agricultural implement system suitable for mountainous areas and hills according to the present invention;

[0100] Figure 3 It is a schematic diagram of rear wheel steering in a fuel cell tractor and a power recovery auxiliary drive electric agricultural implement system suitable for mountainous areas and hills according to the present invention;

[0101] Figure 4 It is a schematic diagram of the structure of a segmented chassis and a waist bending and twisting device.

[0102] Reference numerals

[0103] 1- Segmented chassis, 2- Rear wheel steering device, 3- Hydrogen fuel cell system, 4- Power battery, 5- Electronic control unit, 6- DC\DC converter, 7- Drive motor controller, 8- Drive motor, 9- Electric agricultural machinery controller, 10- Inverter. DETAILED DESCRIPTION

[0104] In order to better understand the content of the present invention, the present invention will be further described below in conjunction with specific embodiments and drawings. The following embodiments are implemented based on the technology of the present invention, and detailed implementation methods and operating steps are given, but the protection scope of the present invention is not limited to the following embodiments.

[0105] Please combine Figures 1-4, a fuel cell tractor applicable to mountainous and hilly areas and a power recovery-assisted drive electric agricultural implement system, including a segmented chassis 1, a folding and twisting device, a rear-wheel steering device 2, a hydrogen fuel cell system 3, a power battery 4, an electronic control unit (VCU) 5, a DC / DC converter 6, a drive motor controller 7, a drive motor 8, an electric agricultural implement controller 9, an inverter 10 (wherein, Figure 2 the folding and twisting device is not shown);

[0106] The segmented chassis 1 includes a front carriage and a rear carriage. A front wheel is installed on each of the left and right sides of the front carriage, and a rear wheel is installed on each of the left and right sides of the rear carriage. The front carriage and the rear carriage are connected by a folding and twisting device;

[0107] The folding and twisting device includes a hydraulic actuator, a universal hinge, and a steering angle sensor. The maximum bending angle of the folding and twisting device is ±30°. The material of the universal hinge is high-strength alloy steel. The steering angle sensor is arranged on the steering column of the steering wheel and is used to accurately detect the angle and angular velocity of the driver turning the steering wheel and provide steering input information for the VCU.

[0108] In this embodiment, the folding and twisting device is a folding and twisting device controlled by a hydraulic actuator. The drive system of the folding and twisting device includes components such as a hydraulic actuator and a universal hinge. The folding and twisting device belongs to the prior art and will not be elaborated here.

[0109] The rear-wheel steering device 2 is arranged between the two rear wheels and is softly connected to the two rear wheels.

[0110] The rear-wheel steering device 2 includes a steering execution mechanism, a vehicle speed sensor, and a rear-wheel corner sensor. The steering execution mechanism includes a rear-wheel steering motor, a steering tie rod, and a steering knuckle. The steering knuckle is softly connected to the two rear wheels; the rear-wheel steering device is controlled by an electronic control unit (VCU).

[0111] In this embodiment, the rear-wheel steering motor uses a servo motor, and the accuracy of the rear-wheel corner sensor is ±0.5°.

[0112] The rear-wheel steering device 2 controls the steering angle of the rear wheels through an electronic or mechanical device and determines the steering direction and angle of the rear wheels according to parameters such as the vehicle speed and steering angle respectively collected by the vehicle speed sensor and the rear-wheel corner sensor.

[0113] The electric power output by the hydrogen fuel cell system 3 first passes through the DC / DC converter 6 to stabilize the voltage and output it as usable direct current, and then is converted into high-voltage alternating current through the inverter 10 and output to the folding and twisting device, the rear-wheel steering device 2, the drive motor controller 7, and the electric agricultural implement controller 9 respectively. The drive motor controller 7 is electrically connected to the drive motor 8, and the electric agricultural implement controller 9 is electrically connected to the electric agricultural implements. Among them, the drive motor 8 provides power for the tractor to travel.

[0114] The electric power output by the power battery 4 first passes through the DC / DC converter 6 to stabilize the voltage and output it as usable direct current, and then is converted into alternating current through the inverter 10 and output to the folding and twisting device, the rear-wheel steering device 2, the electronic control unit 5, the drive motor controller 7, and the electric agricultural implement controller 9 respectively. The hydrogen fuel cell system 3 and the power battery 4 are both connected to the electronic control unit 5 through the CAN bus and are controlled by the VCU.

[0115] The electronic control unit 5 is respectively connected to the folding and twisting device, the rear-wheel steering device, the electric agricultural implement controller, and the drive motor controller through CAN bus signals to control the power output.

[0116] The direct current generated by the hydrogen fuel cell is converted into high-voltage alternating current through the inverter and then output to supply power to the tractor and the electric agricultural implements; the electric energy of the power battery passes through the electric agricultural implement controller, converts the output voltage into the power required by the electric agricultural implements, and then outputs the electric energy. In addition, the power battery also supplies power to the drive motor, and thus also supplies power to the tractor;

[0117] The hydrogen fuel cell system and the power battery are installed at the front part of the tractor frame, and the electronic control unit (VCU) is installed on one side of the hydrogen energy fuel cell system; the drive motor is installed in the rear compartment.

[0118] The electric agricultural implement controller 9 includes a driver, an electronic control module, an energy output management system, a current sensor, a voltage sensor, and a temperature sensor. Among them, the current sensor and the voltage sensor are both installed on the power output interface of the electric agricultural implement controller, and the temperature sensor is installed on the drive motor of the electric agricultural implement.

[0119] Current sensor: It is mainly used to monitor the current magnitude of the drive motor of the electric agricultural implements. By monitoring the current in real time, the electric agricultural implement controller can judge the load condition of the drive motor of the electric agricultural implements. For example, when the agricultural implements encounter hard soil during plowing, the load of the drive motor of the electric agricultural implements increases, and the current will also increase accordingly. If the current exceeds the safe range, the electric agricultural implement controller can take timely measures to prevent the drive motor of the electric agricultural implements from being damaged due to overload.

[0120] Voltage sensor: This sensor can measure the supply voltage of the drive motor of an electric agricultural implement. Stable voltage is the basis for the normal operation of the drive motor of an electric agricultural implement. The voltage sensor enables the electric agricultural implement controller to know in real time whether the voltage is stable. If the voltage is too low, the drive motor of the electric agricultural implement may not reach the rated power; if the voltage is too high, it may damage the drive motor of the electric agricultural implement. The electric agricultural implement controller makes adjustments according to the voltage situation to ensure the stable operation of the drive motor of the electric agricultural implement.

[0121] Temperature sensor: The temperature sensor installed on the drive motor of the electric agricultural implement can monitor the temperature of the drive motor of the electric agricultural implement in real time. The drive motor of the electric agricultural implement generates heat due to factors such as resistance during operation. When the temperature is too high, it will affect the performance and lifespan of the drive motor of the electric agricultural implement. Once the temperature sensor detects an abnormal increase in temperature, the controller will take measures such as reducing power or stopping operation to protect the drive motor of the electric agricultural implement.

[0122] Electronic control unit (VCU), configured with a central processing unit, a storage module, and a communication interface; data interaction between the VCU and the drive motor controller and the electric agricultural implement controller is achieved through a bidirectional communication module. Among them, the VCU is programmed to perform: real-time monitoring of the operating state parameters of the electric agricultural implement, including but not limited to the motor speed, torque output, and battery voltage of the electric agricultural implement; generating multi-dimensional control instructions according to a preset operating algorithm, and the instructions at least include a speed adjustment instruction, a steering control instruction, and an operating parameter adjustment instruction; transmitting instruction signals to the electric agricultural implement controller or the drive motor controller through the CAN bus protocol.

[0123] The operating parameter adjustment instructions include: a tillage depth adjustment module, an operating speed coordination module, an energy optimization module, and a fault diagnosis unit; the tillage depth adjustment module is configured to adjust the operating state of the electric agricultural implement according to the data of the soil resistance sensor, and the soil resistance sensor is installed on the electric agricultural implement; the operating speed coordination module is used to match the proportional relationship between the traveling speed of the tractor and the operating speed of the agricultural implement; the energy optimization module dynamically adjusts the maximum output power threshold based on the remaining power of the battery system. The fault diagnosis unit is configured to: monitor the internal temperature, current fluctuation, and insulation impedance parameters of the electric agricultural implement controller; when over-temperature (>85°C), over-current (current exceeding 150% of the rated value), or insulation failure (impedance <5MΩ) is detected, trigger a hierarchical protection mechanism, and this hierarchical protection mechanism includes: in the first stage, reduce the output power to 50% and issue a warning signal; in the second stage, cut off the power output and record the fault code; in the third stage, activate the emergency braking device.

[0124] The electronic control unit (VCU):

[0125] (1) The VCU communicates with the electric agricultural implement controller via the CAN bus, supports the ISO 11783 protocol, and the maximum communication delay ≤ 50 ms.

[0126] (2) The electronic control unit (VCU) mainly integrates control components and is responsible for controlling the tractor drive motor, the tractor transmission, the operation equipment, and precisely controlling the bending angle required by the folding and twisting mechanism of the tractor when going uphill and downhill. The VCU dynamically adjusts the bending angle of the folding and twisting device according to the terrain slope sensor signal. The bending angle calculation formula is θ = arctan(h / L), where h is the height difference between the front wheel and the rear wheel, and L is the wheelbase.

[0127] The electronic control unit (VCU) can precisely control the output power regulation of the hydrogen fuel cell system and dynamically match the energy supply ratio of the hydrogen fuel cell system and the power battery according to the required power.

[0128] The described electronic control unit (VCU) 6 integrates an electronic control output control module. This module is used to monitor and control the working state of the power output system, including the input / output voltage and current, working temperature, etc. of the inverter. This module controls the change of the power output type through the CAN bus according to the power output set by the driver. This module receives feedback signals such as the required electric power for the operation of the electric agricultural implement, vehicle speed, and driving path, and sends them to the electronic control unit (VCU) 6 for automatically adjusting the operating state of the tractor.

[0129] When driving on relatively narrow roads such as in mountainous and hilly areas, the auxiliary system actively intervenes to drive the rear-wheel steering device 3 through the electronic control unit (VCU).

[0130] The device integrates multi-source data such as GPS (positioning), IMU (inertial measurement unit), wheel speed sensor, steering angle sensor, and terrain slope sensor in the system to ensure steering accuracy. Among them, the GPS is installed on the top of the tractor, and the IMU is installed in the middle of the tractor frame or near the drive motor. The steering angle sensor is installed on the steering column of the steering wheel to accurately detect the angle and angular velocity of the driver turning the steering wheel, and provide steering input information for the VCU; the terrain slope sensor is set on the chassis to monitor the change of terrain slope in real time, so that the VCU can adjust the rear-wheel steering strategy according to different slopes; the wheel speed sensor is set inside the wheel hub to accurately measure the wheel speed and provide data support for calculating the driving state of the vehicle. The IMU inertial measurement unit is used for terrain prediction compensation. The IMU can obtain the attitude and motion information of the vehicle in real time. By analyzing and processing these data, the steering demand of the vehicle can be predicted in advance, and the rear-wheel steering strategy can be adjusted in advance to better adapt to complex terrain changes. When the driver turns the steering wheel, the electronic control unit (VCU) judges the steering intention according to the signal of the steering angle sensor, and determines the appropriate rear-wheel steering strategy by combining the signal collected by the wheel speed sensor. Because at different vehicle speeds, the amplitude and timing of rear-wheel steering are different. At low speeds, the rear wheels may need to steer in the opposite direction to the front wheels to reduce the turning radius; at high speeds, the rear wheels usually steer in the same direction as the front wheels to improve the stability of the vehicle.

[0131] The above functions adopt a double closed-loop control structure:

[0132] Outer loop (path tracking): Calculate the target steering angle based on the Bicycle model:

[0133]

[0134] Where: L is the wheelbase, K is the path curvature, v is the vehicle speed, and g is the acceleration due to gravity

[0135] Inner loop (execution control): Adjust the speed of the drive motor through the PID fuzzy algorithm:

[0136]

[0137] u(t): The output value of the controller. In the scenario of controlling the speed of the drive motor, this output value is usually used to control the voltage, current or duty cycle of the pulse width modulation (PWM) signal of the drive motor, so as to adjust the speed of the drive motor.

[0138] K P : Proportional coefficient. It is multiplied by the current error e(t) to quickly respond to the error. The role of the proportional term is to respond proportionally to the current error. The larger the error, the larger the output of the proportional term, so that the system can quickly approach the target value. But if K PIf it is too large, the system may produce overshoot and even cause system instability.

[0139] K i : Integral coefficient. The integral term integrates the error over time, that is, accumulates the error over a period of time in the past. Its function is to eliminate the steady-state error of the system, because as long as there is an error, the integral term will continue to accumulate until the error is eliminated. However, the integral term may cause the system response to slow down and may cause integral saturation problems in some cases.

[0140] K d : Differential coefficient. The differential term is the rate of change of the error, which reflects the changing trend of the error. By calculating the rate of change of the error, the changing direction of the error can be predicted in advance, so as to make adjustments before the error becomes very large, improve the dynamic response of the system, reduce overshoot, and improve the stability of the system.

[0141] e(t): The error value at the current moment t, that is, the difference between the target rotational speed and the actual rotational speed.

[0142] Then, the electronic control unit (VCU) transmits the control instruction to the steering actuator in the rear-wheel steering device through an electrical signal. The steering actuator is an electric power steering motor or a hydraulic control unit.

[0143] After receiving the instruction from the electronic control unit (VCU), the actuator drives the rear-wheel steering device 3 to work. The rear-wheel steering motor rotates a certain angle according to the instruction and drives the rear wheels to turn through the tie rod.

[0144] In other embodiments, the rear-wheel steering device is connected to the VCU using a dual CAN bus communication architecture to improve the reliability and stability of system communication. When one CAN bus fails, the other bus can continue to work, ensuring unobstructed information transmission between the VCU and each component and ensuring the normal operation of the vehicle steering system.

[0145] For the ramp parking situation, when the slope is greater than 15°, the VCU will control the steering actuator in the rear-wheel steering device 3 to perform a self-locking function. This function can effectively prevent the vehicle from slipping and other dangerous situations due to accidental steering on the ramp, enhancing the parking safety of the vehicle on the ramp.

[0146] The electronic control unit (VCU) is signal-controlled and connected to the hydrogen fuel cell system and the power battery through the CAN bus respectively;

[0147] Both the hydrogen fuel cell system and the power battery are controlled by the electronic control unit (VCU), and the electronic control unit (VCU) will switch the driving mode according to the driver's needs in different situations such as operation and endurance.

[0148] (1) Mode switching based on power demand, specifically including the following two modes:

[0149] ① Low-load steady-state operation mode (driven by power battery)

[0150] Trigger conditions:

[0151] The state of charge (SOC) of the power battery ≥ 40%,

[0152] or the power demand of the current agricultural machinery ≤ 70% of the maximum continuous output power of the power battery,

[0153] or the working slope detected by the slope sensor ≤ 10°

[0154] Control strategy: Turn off the hydrogen fuel cell system and supply power only by the power battery to reduce hydrogen consumption;

[0155] ② High-load / dynamic response mode (hybrid drive)

[0156] Trigger conditions:

[0157] The power demand of the agricultural machinery suddenly increases (such as when a rotary tiller encounters a hard soil layer),

[0158] or the instantaneous output power of the power battery ≥ 80% of the rated value and lasts for 5 seconds,

[0159] or the working slope detected by the slope sensor ≥ 15° (additional traction is required),

[0160] Control strategy: The hydrogen fuel cell system and the power battery supply power in parallel. The basic power of the fuel cell is called first, and the power battery supplements the peak demand.

[0161] (2) Mode switching based on energy management, specifically including the following two modes:

[0162] ① Energy feedback priority mode

[0163] Trigger conditions:

[0164] The tractor is in a downhill or braking state,

[0165] or the state of charge (SOC) of the power battery ≤ 90%,

[0166] Control strategy: Disconnect the hydrogen fuel cell system, convert kinetic energy into electrical energy through the drive motor and feedback it to the power battery, and activate forced feedback when the slope > 20°.

[0167] ② Fuel cell preheating / charging mode

[0168] Trigger conditions:

[0169] The state of charge (SOC) of the power battery ≤ 30%,

[0170] or the ambient temperature < 5°C (the hydrogen fuel cell system needs to be preheated)

[0171] Control strategy: Start the hydrogen fuel cell system to charge the power battery, and at the same time preheat the stack through the waste heat circulation system. After charging to SOC ≥ 50%, switch back to the pure electric mode.

[0172] (3) Mode switching based on the environment and equipment status, specifically including the following two modes:

[0173] ① High-temperature protection mode

[0174] Trigger condition:

[0175] The power battery temperature ≥ 45°C or the fuel cell coolant temperature ≥ 75°C

[0176] Control strategy: Force the hydrogen fuel cell system to share the load, reduce the battery charge and discharge rate, and trigger the highest gear operation of the heat dissipation system.

[0177] ② Fault tolerance mode

[0178] Trigger condition:

[0179] The fuel cell voltage volatility > 15%,

[0180] or the voltage difference of the power battery single cell > 0.2V

[0181] Control strategy: Lock the current energy supply mode and send a fault code to the CAN bus.

[0182] During the driving and operation of the tractor, the electronic control unit (VCU) has a memory function and can intelligently allocate the electric energy output according to different road surface conditions and the operation conditions of different electric agricultural implements.

[0183] The power recovery auxiliary drive electric agricultural implement system, that is, the power recovery system, and the power recovery includes the power recovery during the tractor driving process.

[0184] The power recovery during the tractor driving process means that when the tractor decelerates and brakes during driving, after the driver outputs a deceleration instruction, the wheels still rotate under the action of inertia, and the kinetic energy of the wheels will be converted into the kinetic energy of the rotor of the drive motor. At this time, the motor changes from the drive state to the power generation state and stores it in the power battery.

[0185] During agricultural production activities in complex terrains such as hilly mountains, such as plowing, sowing, fertilizing, and harvesting, the electronic control unit (VCU) 5 controls the folding and twisting device through the CAN bus to achieve precise folding and steering of the wheels.

[0186] When operating on a narrow road, the electronic control unit (VCU) 5 collects road surface information and will automatically intervene when the driver encounters a turning problem and drive the rear-wheel steering device 2. The steering angle of the rear wheels is controlled by an electronic or mechanical device, and the steering direction and angle of the rear wheels are determined according to parameters such as vehicle speed and steering angle to assist the driver in completing the turn. The mountain tractor adopts rear-wheel active steering technology. After testing, a minimum turning radius of 2.8 m was achieved on a 25° slope. Compared with the turning radius of 4.5 m of traditional models, it was reduced by 37.8%. This achievement benefits from the application of the hierarchical Ackerman geometry correction algorithm in the VCU, which effectively reduces the slip rate of the outer wheel during steering and keeps it below 9%. During the continuous S-turn climbing test, the VCU precisely adjusts the torque distribution in real time through the IMU attitude sensor. The test results show that the roll angle is successfully controlled within ±3°, and the wheel-end driving force fluctuation rate <5%, ensuring the stability of the tractor when driving on complex slopes.

[0187] When the tractor is driving on a road condition with frequent uphill and downhill, more energy is consumed when going uphill. When going downhill, the power recovery device will automatically intervene. After the driver outputs a deceleration command, the wheels still rotate under the action of inertia, and the kinetic energy of the wheels will be converted into the kinetic energy of the rotor of the motor. At this time, the motor changes from the driving state to the power generation state to charge the power battery.

[0188] During the test on a downhill section with a slope of 15% and a length of 500 m, the system successfully recovered 21.3 kWh of electric energy, accounting for 17.8% of the total capacity of the power battery, and the recovery efficiency was as high as 82%.

[0189] Taking into account the uphill energy consumption and downhill recovery, the system's cruising range reaches 68 km. Compared with the cruising range of 52 km in the non-recovery mode, it is increased by 22%, meeting the cruising range requirements for single-day terraced field operations.

[0190] The electric agricultural implement controller is an electronic device specifically used to control electric agricultural implements (such as electric fertilizer spreaders, electric sprayers, electric harvesters, etc.). It receives instructions from the operator or the electronic control unit (VCU), processes them through internal circuits and algorithms, and outputs corresponding control signals to drive the motors or other actuators of the electric agricultural implements to achieve the expected operation effect.

[0191] When the power of the power battery is insufficient to drive the electric agricultural implement to complete the operation, the electronic control unit (VCU) controls the hydrogen fuel cell system and the power battery to supply power to the electric agricultural implement together through the CAN bus. Low SOC condition (SOC = 18%): When the SOC is at 18%, the VCU automatically starts the hydrogen fuel cell system, with an output power of 52 kW, and at the same time limits the power battery discharge to below 5 kW. At this time, the hydrogen consumption rate is maintained at 2.3 kg / h.

[0192] High SOC operating condition (SOC = 83%): When the SOC reaches 83%, the system switches to the pure electric mode. In this mode, the power battery continuously outputs a power of 38 kW, and the fuel cell enters the standby state, only maintaining an auxiliary power supply of 1 kW.

[0193] Mode switching response: When the SOC threshold is triggered, the power source switching delay < 0.8 s, and the torque fluctuation amplitude is controlled within the range of ±8 Nm, ensuring the smoothness of the power switching process.

[0194] Independent charging interface unit configuration: The power battery module is integrated with an independent charging interface unit, whose electrical connection characteristics meet the requirements of the DC charging interface in the GB / T 20234.3-2015 standard, the interface protection level reaches IP67, and a mechanical interlock device is built in to prevent hot plugging;

[0195] Dedicated communication protocol design: The communication protocol between the charging interface unit and the external charging device adopts the ISO 15118-20:2022 standard extended protocol, which supports charging pile identity authentication, dynamic adjustment of charging power, and data interaction of the battery health state (SOH). The protocol is compatible with the CAN 2.0B and Ethernet physical layers;

[0196] Off-system charging ability: When the fuel cell system is in the shutdown or fault state, the charging interface unit can operate independently from the vehicle control system and directly input electric energy to the power battery through an external charging device. The charging power covers 5 kW (emergency mode) to 30 kW (fast charging mode);

[0197] Emergency guarantee mechanism: The charging interface unit is built in with a bidirectional DC / DC converter, which supports the switching between the charging and reverse power supply modes, and can provide a minimum temporary power output of 2 kW for electric agricultural machinery in case of emergency.

[0198] Technical feature correlation description

[0199] - Physical interface specification: Referencing the GB / T standard ensures charging compatibility, and the IP67 protection is suitable for the dusty and humid environment in the mountains;

[0200] - Communication redundancy design: Integrating the ISO standard and multi-protocol interfaces meets the data reliability requirements under complex operating conditions;

[0201] - Bidirectional energy flow: Adopting the energy conversion technology in the hybrid power system in the existing technology enhances the emergency power supply ability.

[0202] When the electric agricultural machinery is connected to the tractor, it has a memory function. A hierarchical memory is established. The core layer stores basic parameters. The cache layer records terrain feedback data in real time (power compensation value when the slope > 15°). The blockchain distributed storage technology is adopted to ensure that key parameters such as tillage depth and climbing angle cannot be tampered with. When connecting for the first time, the driver needs to confirm whether the power output parameters of the electric agricultural machinery are correct. When it is not the first connection, the drive controller of the electric agricultural implement can automatically set the historical power output parameters.

[0203] There are two operating modes in the system for driving electric agricultural machinery. It can be automatically switched and finely tuned by the electric agricultural machinery controller according to the preset intelligent algorithm and combined with the real-time operating parameters of the system (such as tractor traveling speed, operation load, battery power, etc.) to achieve the optimal operation efficiency. It also allows the driver to manually trigger the mode conversion instruction through the VCU according to the intuitive observation and experience judgment of the on-site operation, and precisely control the drive mode of the electric agricultural machinery to ensure that the system maintains an efficient, stable and adaptable operating state in the complex and changeable mountain and hilly operation scenarios.

[0204] Once the electric agricultural machinery encounters fault types such as circuit short circuit, mechanical component jamming, sensor failure, etc. during operation, or abnormal working conditions such as overheating, overload, abnormal vibration, etc., the built-in electric agricultural machinery controller can rely on its high-speed and accurate fault monitoring and diagnosis module to quickly respond within a very short time (usually in milliseconds), immediately activate the pre-set safety protection mechanism, cut off the power output link to the electric agricultural machinery, effectively prevent the further deterioration of the fault, and maximize the protection of the personnel safety, equipment integrity and surrounding operation environment at the operation site, ensuring the controllability and safety of the entire operation process.

[0205] The electric agricultural machinery controller is respectively connected to the electronic control unit (VCU) by signals, and can flexibly switch between two electric energy output modes: the power battery drives the electric agricultural machinery alone and the fuel cell and the power battery drive the electric agricultural machinery in cooperation. The specific operation process includes the following steps:

[0206] Step 1: Before connecting the electric agricultural machinery, it is necessary to carefully check the electrical equipment lines and mechanical connection components, accurately confirm the electrical type and rated working voltage parameters required by the electric agricultural machinery, and then complete the adaptation connection operation of the power output port and the control signal interface, where the electrical type refers to direct current or alternating current;

[0207] Step 2: Start the tractor power supply. The electronic control unit (VCU) immediately powers on and self-checks the entire tractor, and detects each part to ensure that there are no signal abnormalities and potential power output faults;

[0208] Step 3: The driver manually mounts the electric agricultural implement and precisely sets the electrical energy parameters and operation type required by the electric agricultural implement with the help of the electric agricultural implement controller. At the same time, the driver reasonably sets the power-off power threshold of the electric agricultural implement to effectively avoid potential dangerous situations;

[0209] Step 4: According to the actual requirements of the upcoming operation, the driver enters the pre-planned operation route in the vehicle system (the vehicle system includes VCU);

[0210] Step 5: After the driver controls the tractor to reach the operation site and inputs the operation command, the power battery will output electrical energy to the electric agricultural implement via the electric agricultural implement controller to drive it to officially start the operation process;

[0211] If the electrical energy output by the power battery can meet the full-process operation requirements of the electric agricultural implement, the entire operation process will be supported by the independent power supply of the power battery;

[0212] When the electric agricultural implement controller monitors that the power of the power battery is no longer sufficient to support the subsequent operation process, the electronic control unit (VCU) will immediately coordinate the hydrogen fuel cell system and the power battery to work together to hybridly drive the electric agricultural implement;

[0213] If the power load required by the electric agricultural implement is too high and exceeds the single-load capacity of the power battery, the electronic control unit (VCU) will directly activate the hybrid drive mode of the hydrogen fuel cell system and the power battery to ensure the stable operation of the electric agricultural implement.

[0214] During driving, due to the existence of many uphill and downhill road conditions on special terrain roads such as mountains and hills, when encountering a large slope uphill section, the electronic control unit (VCU) will precisely identify the uphill angle and control the folding and twisting mechanism to implement distributed regulation of the front and rear compartments to adjust the body posture to an appropriate angle that conforms to the operation requirements;

[0215] In the downhill stage, the power recovery system will be automatically activated to efficiently convert the kinetic energy generated during downhill into electrical energy to charge the power battery;

[0216] When facing a narrow road that makes turning more difficult, the electronic control unit (VCU) will rely on precise recognition ability and intelligent path planning algorithm to control the rear-wheel steering device to assist the driver to successfully complete the turning operation.

[0217] Step 6: During driving and operation, if the instantaneous power output approaches or is about to exceed the maximum power limit value preset by the driver, the vehicle system will immediately trigger the warning mechanism. If it is within the normal operating fluctuation range, the driver can manually cancel the warning; if it is determined to be a fault state, the electric agricultural implement controller will quickly cut off the power input of the electric agricultural implement. At the same time, the power recovery system will be started synchronously to assist the electric agricultural implement in braking operation, ensuring the safety and stability of the operation process in all aspects.

[0218] The above is only an embodiment of the present invention, and does not limit the present invention in any form. The present invention can also have other forms of embodiments according to the above structures and functions, which are not listed one by one. Therefore, any simple modification, equivalent change and modification made by any technician familiar with the profession to the above embodiment according to the technical essence of the present invention without departing from the scope of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A fuel cell tractor and power recovery auxiliary drive electric agricultural machinery system suitable for mountainous areas, characterized in that: It includes a segmented chassis, a waist bending and twisting device, a rear wheel steering device, a hydrogen fuel cell system, a power battery, an electronic control unit, a DC\DC converter, a drive motor controller, a drive motor, an electric agricultural implement controller, and an inverter; The segmented chassis comprises a front compartment and a rear compartment, the left and right sides of the front compartment are respectively provided with a front wheel, the left and right sides of the rear compartment are respectively provided with a rear wheel, and the front compartment and the rear compartment are connected by a waist bending and twisting device; The rear wheel steering device is arranged between the two rear wheels and is softly connected to the two rear wheels; The power output by the hydrogen fuel cell system is firstly output to the bending and twisting device, the rear wheel steering device, the drive motor controller and the electric agricultural implement controller through the DC\DC converter and the inverter. The drive motor controller is electrically connected to the drive motor, and the electric agricultural implement controller is electrically connected to the electric agricultural implement. The drive motor provides power for the tractor to travel. The power output by the power battery first passes through the DC\DC converter and then through the inverter, and then is output to the bending and twisting device, rear wheel steering device, electronic control unit, drive motor controller and electric agricultural machinery controller; The hydrogen fuel cell system and power battery are connected to the electronic control unit through the CAN bus and controlled by the electronic control unit; The electronic control unit is respectively connected with the waist bending and twisting device, the rear wheel steering device, the electric agricultural machinery controller and the driving motor controller through CAN bus signals.

2. The fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous and hilly areas as claimed in claim 1, characterized in that: The waist bending and twisting device includes a hydraulic actuator, a universal hinge, and a steering angle sensor. The material of the universal hinge is high-strength alloy steel. The steering angle sensor is arranged on the steering column of the steering wheel. The maximum bending angle of the waist bending and twisting device is ±30°. The rear-wheel steering device includes a steering actuator, a vehicle speed sensor, and a rear-wheel steering angle sensor. The steering actuator includes a rear-wheel steering motor, a steering rod, and a steering knuckle. The steering knuckle is flexibly connected to the two rear wheels. The rear-wheel steering device is controlled by an electronic control unit. The rear-wheel steering device determines the steering direction and angle of the rear wheels based on the vehicle speed and steering angle parameters collected by the vehicle speed sensor and the rear-wheel steering angle sensor respectively.

3. The fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous and hilly areas as claimed in claim 1, characterized in that: The electronic control unit is configured with a central processing unit, a storage module and a communication interface; the electronic control unit is programmed to perform: real-time monitoring of the operating status parameters of the electric agricultural machinery, including but not limited to the motor speed, torque output, and battery voltage of the electric agricultural machinery; generating multi-dimensional control instructions according to a preset operating algorithm, the instructions at least including speed adjustment instructions, steering control instructions and operating parameter adjustment instructions; transmitting command signals to the electric agricultural machinery controller or the drive motor controller through the CAN bus protocol.

4. The fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous and hilly areas as claimed in claim 2, characterized in that: The rear wheel steering motor uses a servo, and the accuracy of the rear wheel angle sensor is ±0.5°; The hydrogen fuel cell system and power battery are installed at the front of the tractor frame, and the electronic control unit (VCU) is installed on one side of the hydrogen energy fuel cell system; the drive motor is installed in the rear compartment; The electric agricultural machinery controller includes a driver, an electronic control module, an energy output management system, a current sensor, a voltage sensor, and a temperature sensor, wherein the current sensor and the voltage sensor are both installed on the power output interface of the electric agricultural machinery controller, and the temperature sensor is installed on the driving motor of the electric agricultural machinery.

5. The fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous areas as claimed in claim 1, characterized in that: The electronic control unit communicates with the electric agricultural implement controller via the CAN bus, supports the ISO11783 protocol, and has a maximum communication delay of ≤50ms; the electronic control unit (VCU) mainly integrates control components, is responsible for the tractor drive motor control, tractor transmission control, operating equipment control, and accurately controls the angle at which the tractor's bending and twisting mechanism needs to bend when going uphill or downhill. The VCU dynamically adjusts the bending angle of the bending and twisting device according to the terrain slope sensor signal. The bending angle calculation formula is θ=arctan(h / L), where h is the height difference between the front wheel and the rear wheel, and L is the wheelbase; The electronic control unit can accurately control the output power regulation of the hydrogen fuel cell system and dynamically match the energy supply ratio of the hydrogen fuel cell system and the power battery according to the required power.

6. The fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous and hilly areas as claimed in claim 1, characterized in that: The system also includes GPS, IMU inertial measurement unit, wheel speed sensor, terrain slope sensor, wherein GPS is installed on the top of the tractor, IMU is installed in the middle of the tractor frame or near the drive motor; the terrain slope sensor is arranged on the chassis, and the wheel speed sensor is arranged on the inner side of the wheel hub; the IMU inertial measurement unit is used for terrain prediction compensation; the IMU can obtain the posture and motion information of the vehicle in real time, and through the analysis and processing of these data, the steering demand of the vehicle can be predicted, and the rear wheel steering strategy can be adjusted in advance to adapt to complex terrain changes; When the driver turns the steering wheel, the electronic control unit determines the steering intention based on the steering angle sensor signal and determines the appropriate rear-wheel steering strategy based on the signal collected by the wheel speed sensor; The above functions adopt a double closed-loop control structure: Outer loop (path tracking): Calculate the target turning angle based on the Bicycle model: Where: L is the wheelbase, K is the path curvature, v is the vehicle speed, and g is the acceleration due to gravity Inner loop (execution control): Regulate the speed of the drive motor through PID fuzzy algorithm: u(t): The output value of the controller. In the drive motor speed control scenario, this output value is usually used to control the voltage, current or duty cycle of the pulse width modulation (PWM) signal of the drive motor to adjust the speed of the drive motor; K P : Proportional coefficient, which is multiplied by the current error e(t) to quickly respond to the error; the role of the proportional term is to respond proportionally to the current error. The larger the error, the larger the output of the proportional term, so that the system quickly approaches the target value; but if K P If it is too large, the system may overshoot or even become unstable. K i : Integral coefficient. The integral term integrates the error over time, that is, it accumulates the error over a period of time. Its function is to eliminate the steady-state error of the system, because as long as there is an error, the integral term will continue to accumulate until the error is eliminated. However, the integral term may cause the system to respond more slowly and may cause integral saturation problems in some cases. K d : Differential coefficient, the differential term is the rate of change of the error, which reflects the trend of the error change; by calculating the rate of change of the error, the direction of error change can be predicted in advance, so that adjustments can be made before the error becomes very large, improving the dynamic response of the system, reducing overshoot, and improving the stability of the system; e(t): The error value at the current time t, that is, the difference between the target speed and the actual speed.

7. The fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous and hilly areas as claimed in claim 1, characterized in that: Both the hydrogen fuel cell system and the power battery are controlled by the electronic control unit, which will switch the driving mode according to the driver's needs in different working and endurance situations: (1) Mode switching based on power demand, including the following two modes: ①Low-load steady-state operation mode (power battery drive) Trigger conditions: Power battery SOC (remaining power) ≥ 40%, Or the current power demand of agricultural machinery is ≤ 70% of the maximum continuous output power of the power battery. Or the slope sensor detects that the working slope is ≤10° Control strategy: shut down the hydrogen fuel cell system and only use the power battery to supply power to reduce hydrogen consumption; ②High load / dynamic response mode (hybrid drive) Trigger conditions: The power demand of agricultural machinery increases suddenly (such as rotary tiller cutting hard soil layer). Or the instantaneous output power of the power battery is ≥ 80% of the rated value and lasts for 5 seconds, Or the slope sensor detects that the operating slope is ≥15° (additional traction is required), Control strategy: The hydrogen fuel cell system and the power battery are connected in parallel to supply power, with the basic power of the fuel cell being used first and the power battery supplementing the peak demand; (2) Mode switching based on energy management, specifically including the following two modes: ①Energy feedback priority mode Trigger conditions: The tractor is in downhill or braking state. Or power battery SOC≤90%, Control strategy: disconnect the hydrogen fuel cell system, convert kinetic energy into electrical energy through the drive motor and feed it back to the power battery, and activate forced feedback when the slope is greater than 20°; ②Fuel cell preheating / charging mode Trigger conditions: Power battery SOC≤30%, Or the ambient temperature is less than 5°C (the hydrogen fuel cell system needs to be preheated) Control strategy: Start the hydrogen fuel cell system to charge the power battery, and preheat the stack through the waste heat circulation system. After charging to SOC ≥ 50%, switch back to pure electric mode; (3) Mode switching based on environment and device status, including the following two modes: ①High temperature protection mode Trigger conditions: Power battery temperature ≥ 45°C or fuel cell coolant temperature ≥ 75°C Control strategy: Force the hydrogen fuel cell system to share the load, reduce the battery charge and discharge rate, and trigger the cooling system to run at the highest level; ②Fault tolerance mode Trigger conditions: Fuel cell voltage fluctuation rate>15%, Or the voltage difference of power battery cells is greater than 0.2V Control strategy: lock the current energy supply mode and send the fault code to the CAN bus.

8. The fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous and hilly areas as claimed in claim 1, characterized in that: The electronic control unit transmits control instructions to the steering actuator in the rear-wheel steering device through electrical signals. After receiving the instructions from the electronic control unit, the steering actuator drives the rear-wheel steering device to work; the rear-wheel steering motor rotates a certain angle according to the instructions and drives the rear wheels to steer through the steering rod.

9. The fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous areas as claimed in claim 1, characterized in that: The system also includes a power recovery system; when the tractor decelerates and brakes during driving, the wheels continue to rotate under the action of inertia after the driver outputs a deceleration command. The power recovery system converts the kinetic energy of the wheels into the rotor kinetic energy of the drive motor. At this time, the motor changes from a driving state to a power generation state and stores it in the power battery.

10. A method for using the fuel cell tractor and power recovery auxiliary drive electric agricultural implement system suitable for mountainous areas as claimed in any one of claims 1 to 9, characterized in that: The specific steps include: Step 1: Before connecting the electric agricultural machinery, it is necessary to carefully check the power equipment circuit and mechanical connection components, confirm the power type and rated working voltage parameters required by the electric agricultural machinery, and then complete the adaptation connection operation between the power output port and the control signal interface; Step 2: Start the tractor power supply, and the electronic control unit will then perform a power-on self-test on the entire tractor and test each part to ensure that there are no abnormal signals or hidden dangers of power output failure; Step 3: The driver manually mounts the electric agricultural implement and uses the electric agricultural implement controller to accurately set the power parameters and operation type required by the electric agricultural implement. At the same time, the driver reasonably sets the power-off power threshold of the electric agricultural implement to effectively avoid potential dangerous conditions. Step 4: The driver enters the pre-planned operation route into the vehicle computer system according to the actual needs of the operation to be carried out, and the vehicle computer system includes an electronic control unit; Step 5: After the driver controls the tractor to arrive at the work site, he inputs the work instruction. At this time, the power battery will output electric energy to the electric agricultural implement through the electric agricultural implement controller, driving it to officially start the work process; If the power output of the power battery can meet the full operation requirements of the electric agricultural machinery, the entire operation process is supported by the power battery independently; When the electric agricultural implement controller detects that the power battery is no longer able to support the subsequent operation process, the electronic control unit will immediately deploy the hydrogen fuel cell system and the power battery to work together to drive the electric agricultural implement; If the power load required by the electric agricultural implement is too high and exceeds the power battery's capacity alone, the electronic control unit will directly enable the hybrid drive mode of the hydrogen fuel cell system and the power battery to ensure the stable operation of the electric agricultural implement; During driving, given the many uphill and downhill road conditions in mountainous and hilly terrain, when encountering an uphill section, the electronic control unit will accurately identify the uphill angle, control the waist bending and twisting mechanism, and implement distributed control of the front and rear compartments to adjust the body posture to the appropriate angle that meets the operating needs; During the downhill phase, the power recovery system will automatically activate and run, efficiently converting the kinetic energy generated during the downhill process into electrical energy to replenish the power battery; When facing narrow roads that make turning more difficult, the electronic control unit will use its precise recognition capabilities and intelligent path planning algorithm to control the rear-wheel steering device to assist the driver in completing the turning operation smoothly; Step 6: During driving and operation, if the instantaneous power output approaches or is about to exceed the maximum power limit value preset by the driver, the vehicle system will immediately trigger the warning mechanism; if it is within the normal operating fluctuation range, the driver can manually cancel the warning; If it is determined to be a fault state, the electric agricultural machinery controller will quickly cut off the power input of the electric agricultural machinery. At the same time, the power recovery system will be started synchronously to assist the electric agricultural machinery in achieving braking operations.

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