Tractor hybrid chassis device and control method

Abstract

This invention relates to the field of agricultural machinery technology, specifically to a hybrid chassis device and control method for a tractor, comprising a hybrid power module, a chassis power control module, an energy management module, and a shifting strategy module. The hybrid power module integrates an engine, motor, battery pack, and power coupling device; the chassis power control module achieves real-time correction of chassis attitude through load sensing, center of gravity estimation, attitude prediction, and feedforward compensation; the energy management module identifies four operating conditions: plowing, transporting, PTO output, and idling, and dynamically optimizes the power distribution between the engine and motor; the shifting strategy module uses a Kalman filter algorithm to predict the target gear and achieves smooth shifting through three-stage coordinated control of torque phase, inertia phase, and synchronization phase. This can improve the stability of operation in complex terrain, optimize energy utilization efficiency, achieve uninterrupted shifting, and significantly reduce fuel consumption and emissions.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, and in particular to a hybrid chassis device and control method for a tractor. Background Technology

[0002] As a core power source in agricultural production, the tractor's power performance and fuel economy directly impact the efficiency and cost of agricultural operations. Traditional tractors primarily use diesel engines as their sole power source. While these engines offer advantages such as simple structure and high reliability, they suffer from several shortcomings in actual operation. Traditional tractors experience significant load variations under different working conditions, including plowing and transport, causing the engine to frequently operate in uneconomical zones, resulting in higher fuel consumption and severe emissions. Secondly, traditional tractors suffer from power interruptions during gear shifts, especially under heavy loads, where shifting shocks can affect work quality and driving comfort. Furthermore, traditional tractors lack active control over their chassis posture, making them prone to tilting and slippage during slope operations or turns, posing safety hazards.

[0003] With the development of new energy technologies, hybrid technology has gradually been introduced into the tractor field. Hybrid tractors, through the coordinated work of the engine and electric motor, can optimize power distribution under different operating conditions, improve fuel economy, and utilize the rapid response characteristics of the electric motor to improve shift quality. However, existing hybrid tractor technology still has some problems: first, the energy management strategy is relatively simple and fails to fully consider the characteristics of different operating conditions; second, the shift control strategy is not perfect, and the torque coordination control accuracy during shifting is insufficient; third, there is a lack of active control over the chassis attitude, and stability needs to be improved when operating in complex terrain. Therefore, there is an urgent need to develop a hybrid chassis device for tractors that can comprehensively solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a hybrid chassis device and control method for tractors, which can improve the stability of operation in complex terrain, optimize energy utilization efficiency, realize uninterrupted gear shifting, and significantly reduce fuel consumption and emissions.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a tractor hybrid chassis device, including a hybrid power module, a chassis power control module, an energy management module, and a shift strategy module; The hybrid power module includes an engine, an electric motor, a battery pack, and a power coupling device; The chassis power control module is electrically connected to the hybrid power module. It is used to collect chassis status parameters in real time and generate control commands. Then, it predicts chassis attitude deviation based on the changes in the steering angle of the tractor's front wheels and the load on the front axle, and corrects the control commands in real time based on the actual attitude deviation. The energy management module is used to dynamically allocate the power output ratio between the engine and the motor according to the chassis status parameters, battery SOC value and operating conditions. The shift strategy module is used to realize automatic shift control of the multi-gear transmission according to the control commands output by the chassis power control module. The control commands include torque requirements and speed requirements.

[0006] The chassis dynamic control module includes a load sensing unit, a center of gravity estimation unit, an attitude prediction unit, and a feedforward compensation unit. The load sensing unit is used to collect load distribution data of the front axle and the rear axle in real time and generate control commands, including torque distribution of the left and right drive wheels. The center of gravity estimation unit is used to estimate the position of the overall center of gravity based on the load distribution data and the geometric parameters of the tractor. The attitude prediction unit is used to predict the attitude deviation of the tractor when working on a slope based on the center of gravity position, front wheel steering angle and working resistance. The feedforward compensation unit adjusts the torque distribution of the left and right drive wheels in advance based on the attitude deviation to correct the control command.

[0007] The energy management module includes a working condition identification unit, a power distribution unit, and an engine torque limiting unit. The working condition identification unit is used to identify the working condition type of the tractor, including plowing condition, transportation condition, PTO output condition and no-load condition. The power distribution unit is used to match the target power distribution ratio between the engine and the motor according to the type of operating condition and the battery SOC value. The engine torque limiting unit is used to limit the engine torque output for charging when the battery SOC value is lower than a preset threshold.

[0008] The operating condition identification unit includes a signal receiving subunit, an operating condition classification subunit, and an operating condition output subunit; The signal receiving subunit is used to receive input signals, including chassis status parameter signals, engine operating parameter signals, motor operating parameter signals, and gearbox gear signals. The working condition classification subunit is used to perform working condition type matching based on the input signal. The identified working condition types include plowing working condition, transportation working condition, PTO output working condition, and empty running working condition. The operating condition output subunit is used to send the matched operating condition type to the energy management module and the shifting strategy module.

[0009] The power distribution unit is further configured to prioritize the use of electric motor drive to reduce emissions during plowing operations and to prioritize the use of engine drive to improve fuel economy during transportation operations.

[0010] The shift strategy module includes a gear prediction unit, a shift smoothness control unit, and a shift torque compensation unit. The gear prediction unit is used to predict the next target gear based on the current rate of change of torque demand and the trend of vehicle speed change. The shift smoothness control unit is used to coordinate and control the engine torque and motor torque during shifting to reduce the impact on the transmission system. The shift torque compensation unit is used to provide auxiliary torque compensation through the motor when downshifting and to absorb excess torque through the motor when upshifting.

[0011] The gear prediction unit includes a torque demand analysis subunit, a vehicle speed trend prediction subunit, and a gear decision subunit. The torque demand analysis subunit collects accelerator pedal opening signal, working resistance signal and slope signal, and combines them with a preset torque demand calculation model to obtain the current torque demand value and its rate of change over time. When the rate of change of torque demand exceeds the first preset threshold, it is determined to be a rapid acceleration condition. When the rate of change of torque demand is lower than the second preset threshold, it is determined to be a gradual change condition. The vehicle speed trend prediction subunit is used to smooth the vehicle speed signal using a Kalman filter algorithm and calculate the vehicle speed prediction value based on historical vehicle speed data and current acceleration. When the predicted vehicle speed increases and exceeds the upper limit of the optimal economic speed range of the current gear, an upshift tendency signal is generated. When the predicted vehicle speed decreases and is lower than the lower limit of the optimal power speed range of the current gear, a downshift tendency signal is generated. The gear decision subunit is used to determine the target gear by querying a preset gear mapping table. The gear mapping table is established based on engine speed, vehicle speed, torque requirements and operating conditions, and a shift delay interval is set to prevent frequent gear shifting.

[0012] The shift smoothness control unit includes a shift phase division subunit, a torque coordination control subunit, and an impact monitoring subunit. The shift phase division subunit is used to divide the shift process into three stages: torque phase, inertia phase, and synchronization phase. The torque phase is the clutch disengagement phase, the inertia phase is the engine speed adjustment phase, and the synchronization phase is the new gear engagement phase. The current shift phase is determined based on the ratio of the input shaft speed to the output shaft speed of the transmission. The torque coordination control subunit is used to control the engine torque to decrease at a first preset slope and simultaneously control the motor torque to increase at a second preset slope to compensate for the output torque loss during the torque phase phase. During the inertia phase phase, the speed adjustment amount is calculated based on the difference between the target speed and the actual speed, and the motor is controlled to run in speed mode to assist the engine in quickly reaching the target speed. During the synchronization phase phase, the engine torque and motor torque are controlled to increase synchronously to the target torque value at a third preset slope. The impact monitoring subunit is used to collect the longitudinal acceleration signal of the vehicle through the acceleration sensor, calculate the derivative of acceleration with respect to time to obtain the impact, and adjust the slope of the change of engine torque and motor torque to reduce the impact when the impact exceeds the preset impact threshold.

[0013] The shift torque compensation unit includes a downshift torque compensation subunit, an upshift torque absorption subunit, and a compensation amount adaptive adjustment subunit. The downshift torque compensation subunit is used to calculate the torque gap based on the speed ratio change before and after downshifting at the start of downshifting, and control the motor to output positive torque to fill the torque gap. The upshift torque absorption subunit is used to calculate the torque surplus based on the speed ratio change before and after upshifting at the start of upshifting, control the motor to work in the power generation mode to absorb the excess torque, and store the absorbed energy in the battery pack. The adaptive adjustment subunit for compensation amount is used to collect the actual impact and shift time during the shift process. When the actual impact is greater than the target impact, the response speed of the motor compensation torque is increased. When the shift time exceeds the preset shift time threshold, the amplitude of the motor compensation torque is increased, and the maximum value of the motor compensation torque is limited according to the battery SOC value. When the battery SOC value is lower than the preset SOC threshold, the maximum value of the motor compensation torque is reduced.

[0014] Secondly, the present invention also provides a control method for a tractor hybrid chassis device, using the aforementioned tractor hybrid chassis device.

[0015] This invention discloses a hybrid tractor chassis device and control method. By incorporating a chassis power control module, it can perceive chassis load distribution in real time, predict attitude deviations, and perform feedforward compensation, thereby improving the stability and safety of the tractor when operating in complex terrain. By incorporating an energy management module, it can intelligently allocate the power output ratio of the engine and motor according to different operating conditions, optimizing energy utilization efficiency and reducing fuel consumption and emissions. By incorporating a shift strategy module, it can achieve intelligent gear prediction and smooth shift control, reducing shift shock and improving driving comfort and work quality. Through the participation of the motor in shift torque compensation, it can effectively fill torque gaps or absorb excess torque during shifting, achieving uninterrupted shifting. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0017] Figure 1 This is a structural diagram of the first embodiment of the present invention.

[0018] Figure 2 This is a structural diagram of the chassis power control module according to the first embodiment of the present invention.

[0019] Figure 3 This is a structural diagram of the energy management module of the first embodiment of the present invention.

[0020] Figure 4 This is a structural diagram of the working condition identification unit of the first embodiment of the present invention.

[0021] Figure 5 This is a structural diagram of the shifting strategy module of the first embodiment of the present invention.

[0022] Figure 6 This is a structural diagram of the gear prediction unit according to the first embodiment of the present invention.

[0023] Figure 7 This is a structural diagram of the shift smoothness control unit according to the first embodiment of the present invention.

[0024] Figure 8 This is a structural diagram of the shift torque compensation unit according to the first embodiment of the present invention.

[0025] In the diagram: 1 Hybrid power module, 11 Engine, 12 Motor, 13 Battery pack, 14 Power coupling device; 2 Chassis power control module, 21 Load sensing unit, 22 Center of gravity estimation unit, 23 Attitude prediction unit, 24 Feedforward compensation unit; 3 Energy management module, 31 Operating condition identification unit, 311 Signal receiving subunit, 312 Operating condition classification subunit, 313 Operating condition output subunit, 32 Power distribution unit, 33 Engine torque limiting unit; 4 Shift strategy module, 41 Gear prediction unit, 411 Torque demand analysis subunit, 412 Vehicle speed trend prediction subunit, 413 Gear decision subunit, 42 Shift smoothness control unit, 421 Shift phase division subunit, 422 Torque coordination control subunit, 423 Shock monitoring subunit, 43 Shift torque compensation unit, 431 Downshift torque compensation subunit, 432 Upshift torque absorption subunit, 433 Compensation amount adaptive adjustment subunit. Detailed Implementation

[0026] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0027] First embodiment: Please see Figures 1-8 This invention provides a hybrid chassis device for a tractor, comprising a hybrid power module 1, a chassis power control module 2, an energy management module 3, and a shift strategy module 4. The hybrid power module 1 serves as the core power source of the entire device, responsible for generating and transmitting power; the chassis power control module 2 is responsible for real-time monitoring and control of the chassis status; the energy management module 3 is responsible for optimizing energy distribution; and the shift strategy module 4 is responsible for achieving smooth shifting. The shift strategy module is used to implement automatic shifting control of the multi-gear transmission based on control commands output by the chassis power control module, including torque and speed requirements. The modules communicate with each other via a Controller Area Network (CAN) bus to achieve information sharing and collaborative control. The CAN bus adopts the ISO 11898 standard, with a communication rate of 500kbps, and uses a two-wire differential transmission method, possessing strong anti-interference capabilities and adapting to electromagnetic interference in the tractor's operating environment.

[0028] In this embodiment, the tractor hybrid chassis system adopts a distributed control architecture, with each module equipped with an independent electronic control unit (ECU). Hybrid power module 1 is equipped with a hybrid power controller (HCU), chassis power control module 2 with a chassis controller (VCU), energy management module 3 with an energy management controller (EMU), and shift strategy module 4 with a transmission controller (TCU). The controllers exchange data via a CAN bus, and each controller has independent fault diagnosis and safety protection functions. When a controller detects a fault, it can send fault information to other controllers via the CAN bus, triggering a system-level fault response strategy to ensure the safe operation of the tractor under fault conditions.

[0029] The entire device operates as follows: First, the chassis power control module 2 collects real-time load distribution data of the front and rear axles through the load sensing unit 21, estimates the overall center of gravity position through the center of gravity estimation unit 22, predicts attitude deviation through the attitude prediction unit 23, and generates torque distribution commands through the feedforward compensation unit 24. The energy management module 3 identifies the current operating condition through the working condition identification unit 31, and allocates the power output ratio of the engine and motor according to the working condition and battery SOC value through the power distribution unit 32. The shift strategy module 4 predicts the target gear through the gear prediction unit 41, coordinates and controls the shifting process through the shift smoothness control unit 42, and performs torque compensation through the shift torque compensation unit 43. The hybrid power module 1 coordinates the output of the engine 11 and the motor 12 according to the control commands of each module to achieve efficient power transmission.

[0030] The hybrid power module 1 includes an engine 11, an electric motor 12, a battery pack 13, and a power coupling device 14. The hybrid power module 1 adopts a parallel hybrid power architecture, in which the engine 11 and the electric motor 12 can drive the vehicle independently or work together to drive the vehicle, which has the advantages of compact structure, high efficiency, and good reliability.

[0031] Engine 11 is a four-cylinder turbocharged diesel engine equipped with an electronically controlled high-pressure common rail fuel injection system. The injection pressure can reach 180 MPa, enabling multiple injections, optimizing the combustion process, and reducing emissions. Engine 11 also features an exhaust gas turbocharger and intercooler system to increase intake air density and enhance power output. The electronic control unit (ECU) of engine 11 communicates with the hybrid power control unit (HCU) via a CAN bus, receiving torque commands and feeding back engine status parameters, including engine speed, torque, coolant temperature, oil pressure, and fuel consumption rate. Engine 11 operates in the following modes: normal drive mode, where the engine provides the primary power source and drive torque; charging mode, where the engine operates in its high-efficiency range, with excess power used to charge the battery pack 13; and auxiliary mode, where the engine works in conjunction with the electric motor 12 to meet high-power demands.

[0032] Motor 12 is a permanent magnet synchronous motor (PMSM) with a peak power of 45kW, a rated power of 25kW, a peak torque of 300Nm, a rated torque of 150Nm, a maximum speed of 6000rpm, and a rated voltage of 400V. Motor 12 features high power density, high efficiency, and fast response, with an efficiency exceeding 95%. Motor 12 can function as a motor to provide drive torque, or as a generator to recover braking energy or absorb excess torque during gear shifts. Motor 12 is equipped with an independent motor controller (MCU) using a vector control (FOC) algorithm to achieve precise torque control with a torque response time of less than 10ms. The MCU communicates with the hybrid power control unit (HCU) via a CAN bus, receiving torque or speed commands and feeding back motor status parameters, including motor speed, torque, current, and temperature. Motor 12 operates in the following modes: drive mode, where the motor outputs positive torque to assist drive; generator mode, where the motor operates in generator mode to recover energy; speed mode, where the motor assists the engine speed adjustment through speed control; and standby mode, where the motor does not participate in operation and is in a zero-torque state.

[0033] Battery pack 13 uses lithium iron phosphate (LiFePO4) batteries with a rated capacity of 40kWh and a rated voltage of 400V. It consists of 128 individual cells connected in series, each with a rated voltage of 3.2V and a rated capacity of 100Ah. State of charge (SOC) estimation uses an ampere-hour integral method combined with an open-circuit voltage method for correction, achieving an estimation accuracy within 3%. Battery pack 13 operates within a temperature range of -20℃ to 55℃ and is equipped with a liquid-cooled thermal management system. In high-temperature environments, it dissipates heat through coolant circulation, while in low-temperature environments, it preheats with a heater to ensure the battery operates within its optimal temperature range. The charge / discharge management strategy of battery pack 13 is as follows: the upper limit of SOC is set at 90%, and the lower limit is set at 20%. When the SOC is below 20%, low-charge protection is triggered, limiting motor power output and prioritizing motor drive while charging the battery. When the SOC is above 90%, high-charge protection is triggered, limiting energy recovery and prioritizing motor drive.

[0034] The power coupling device 14 employs a planetary gear-type power coupling mechanism, comprising four basic components: a sun gear, planet gears, a planet carrier, and a ring gear. The engine 11 is connected to the planet carrier, the motor 12 is connected to the sun gear, and the ring gear serves as the output end, connected to the gearbox input shaft. By controlling the speed and torque of the motor 12, the output torque of the engine 11 can be steplessly adjusted, ensuring that the engine 11 always operates in its high-efficiency range. The speed ratio characteristic of the power coupling device 14 is: Output torque = Engine torque × (1+k) / k + Motor torque × (1+k), where k is the ratio of the number of teeth on the ring gear to the number of teeth on the sun gear; in this embodiment, k = 2.5. The power coupling device 14 is also equipped with a one-way clutch and brake, enabling switching between various operating modes, including pure electric drive mode, engine-only drive mode, and hybrid drive mode. The power coupling device 14 achieves a transmission efficiency of over 96%, offering advantages such as compact structure, smooth transmission, and low noise.

[0035] The chassis power control module 2 includes a load sensing unit 21, a center of gravity estimation unit 22, an attitude prediction unit 23, and a feedforward compensation unit 24. The main function of the chassis power control module 2 is to monitor the chassis status in real time, predict attitude deviations, and perform feedforward compensation control to improve the stability and safety of the tractor when operating in complex terrain.

[0036] The load sensing unit 21 collects load distribution data in real time using strain gauge pressure sensors installed on the front and rear axles. Two pressure sensors are installed on the front axle, located at the suspension system connection points of the left and right front wheels respectively; two pressure sensors are installed on the rear axle, located at the suspension system connection points of the left and right rear wheels respectively. The pressure sensors are resistance strain gauge type, with a range of 0-50kN, an accuracy of 0.5%FS, and an output signal of 4-20mA current. The load sensing unit 21 samples at a frequency of 100Hz, acquiring load data every 10ms. The load sensing unit 21 filters the acquired raw signal using a fourth-order Butterworth low-pass filter with a cutoff frequency set to 10Hz to eliminate high-frequency noise interference. The filtered load data is used to calculate the front axle load, rear axle load, left-side load, right-side load, and total load. The load sensing unit 21 also generates control commands based on the load distribution data, including the torque distribution ratio between the left and right drive wheels. When the load difference between the left and right sides is detected to exceed a preset threshold (such as 15% of the total load), the load sensing unit 21 automatically adjusts the torque distribution of the left and right drive wheels, increases the torque output of the side with a larger load, and decreases the torque output of the side with a smaller load, thereby achieving adaptive torque distribution.

[0037] The center of gravity estimation unit 22 estimates the overall center of gravity position based on load distribution data and the tractor's geometric parameters. The tractor's geometric parameters include wheelbase L (distance between the front and rear wheel centers, 2400mm in this embodiment), track width W (distance between the left and right wheel centers, 1800mm in this embodiment), front axle height h1 (height of the front wheel center from the ground, 650mm in this embodiment), and rear axle height h2 (height of the rear wheel center from the ground, 750mm in this embodiment). The center of gravity estimation uses the torque balance method, calculated as follows: longitudinal position of center of gravity Xcg = (rear axle load × wheelbase) / total load; lateral position of center of gravity Ycg = (right side load - left side load) × track width / (2 × total load); center of gravity height Hcg is estimated using an empirical formula: Hcg = h2 + 0.3 × (h2 - h1) + Δh, where Δh is a correction value calculated based on suspension deformation. The calculation cycle of the center of gravity estimation unit 22 is 10ms, synchronized with the sampling cycle of the load sensing unit 21. The center of gravity estimation results are used for attitude prediction and feedforward compensation control. The center of gravity estimation unit 22 also performs a reasonableness check on the estimation results. When the estimated center of gravity position exceeds the preset range, it is marked as abnormal data, replaced by the valid data from the previous moment, and the sensor fault diagnosis program is triggered.

[0038] The attitude prediction unit 23 predicts the tractor's attitude deviation when operating on a slope based on the center of gravity position, front wheel steering angle, and working resistance. The attitude prediction unit 23 establishes a tractor dynamics model, including a roll dynamics model and a pitch dynamics model. The roll dynamics model predicts the roll angle of the tractor when turning or operating on a cross slope, calculated as: roll angle θr = arctan((lateral acceleration × center of gravity height) / (wheelbase × g / 2 - lateral acceleration × center of gravity height)), where g is the acceleration due to gravity. The pitch dynamics model predicts the pitch angle of the tractor when operating on a longitudinal slope, calculated as: pitch angle θp = arctan((longitudinal acceleration × center of gravity height) / (wheelbase × g - longitudinal acceleration × center of gravity height)). The attitude prediction unit 23 also considers the influence of working resistance, which is collected by force sensors in the three-point suspension system, including traction and lifting forces. When the tractor is plowing on a slope, the working resistance generates an additional pitching moment, which the attitude prediction unit 23 incorporates into the dynamics model for correction. The attitude prediction unit 23 has a prediction period of 20ms and a prediction time domain of 500ms, meaning it predicts the attitude change trend within the next 500ms. The attitude prediction results are used for feedforward compensation control to adjust torque distribution in advance and suppress the development of attitude deviations.

[0039] The feedforward compensation unit 24 adjusts the torque distribution of the left and right drive wheels in advance based on the attitude deviation to correct the control command. The feedforward compensation adopts a proportional-derivative (PD) control strategy. The compensation torque calculation formula is: Compensation torque = Kp × Predicted attitude deviation + Kd × Predicted attitude deviation change rate, where Kp is the proportional coefficient and Kd is the derivative coefficient. In this embodiment, the proportional coefficient for roll compensation is Kp_r = 500 Nm / rad, and the derivative coefficient is Kd_r = 100 Nm·s / rad; the proportional coefficient for pitch compensation is Kp_p = 300 Nm / rad, and the derivative coefficient is Kd_p = 60 Nm·s / rad. The feedforward compensation unit 24 superimposes the compensation torque onto the basic torque distribution of the left and right drive wheels to achieve active attitude control. For example, when it is predicted that the tractor will roll to the left, the feedforward compensation unit 24 increases the torque output of the left drive wheel and decreases the torque output of the right drive wheel, generating a rightward restoring torque to suppress the roll tendency. The feedforward compensation unit 24 also sets upper and lower limits for the compensation torque, with the upper limit being 30% of the total drive torque and the lower limit being -30% of the total drive torque, to prevent over-compensation from causing system instability. The compensation response time of the feedforward compensation unit 24 is less than 50ms, which can effectively cope with the attitude changes of the tractor when operating in complex terrain.

[0040] The energy management module 3 includes a working condition identification unit 31, a power distribution unit 32, and an engine torque limiting unit 33. The main function of the energy management module 3 is to optimize the power distribution between the engine and the motor based on the working conditions and battery status, thereby achieving efficient energy utilization.

[0041] The operating condition identification unit 31 includes a signal receiving subunit 311, an operating condition classification subunit 312, and an operating condition output subunit 313. The signal receiving subunit 311 receives input signals from various sensors, including chassis status parameter signals (vehicle speed, acceleration, steering angle, etc.), engine operating parameter signals (speed, torque, throttle opening, etc.), motor operating parameter signals (speed, torque, current, etc.), and transmission gear position signals. The signal receiving subunit 311 preprocesses the input signals, including signal filtering, unit conversion, and outlier removal. Signal filtering uses a moving average filter with a window length of 5 sampling points; unit conversion converts the signals from each sensor to a unified SI system; outlier removal uses the 3σ criterion, where a signal value exceeding the mean ± 3 times the standard deviation is considered an outlier and removed.

[0042] The operating condition classification subunit 312 employs a rule-based classification algorithm to match operating condition types based on the characteristics of the input signal. The judgment logic for operating condition classification is as follows: First, it judges the PTO output operating condition. When the PTO output shaft speed is greater than 100 rpm and the PTO torque is greater than 50 Nm, it is identified as the PTO output operating condition. Second, it judges the plowing operating condition. When the traction force is greater than 10 kN and the vehicle speed is less than 10 km / h, it is identified as the plowing operating condition. Third, it judges the transportation operating condition. When the vehicle speed is greater than 15 km / h and the traction force is less than 5 kN, it is identified as the transportation operating condition. Finally, it judges the empty running operating condition. When the vehicle speed is greater than 0, the traction force is less than 2 kN, and the PTO torque is less than 20 Nm, it is identified as the empty running operating condition. The operating condition classification subunit 312 also sets operating condition priorities, with priorities from high to low as follows: PTO output operating condition, plowing operating condition, transportation operating condition, and empty running operating condition. When multiple operating condition conditions are met simultaneously, the operating condition type is selected according to priority. The operating condition classification subunit 312 is also equipped with an operating condition stability judgment. The operating condition switch is only confirmed when the same operating condition lasts for more than 3 seconds, so as to prevent frequent changes in operating conditions.

[0043] The operating condition output subunit 313 sends the matched operating condition type to the energy management module 3 and the shift strategy module 4 via the CAN bus. The data frame format sent by the operating condition output subunit 313 is as follows: frame ID is 0x180, data length is 8 bytes, the first byte is the operating condition type code (0x01 for plowing, 0x02 for transportation, 0x03 for PTO output, 0x04 for empty driving), bytes 2-5 are the traction force value (floating-point number, unit kN), bytes 6-7 are the vehicle speed value (unsigned integer, unit 0.1 km / h), and the eighth byte is the checksum. The transmission cycle of the operating condition output subunit 313 is 100ms, meaning it sends operating condition information every 100ms.

[0044] The power allocation unit 32 matches the target power allocation ratio between the engine 11 and the electric motor 12 based on the operating condition type and the battery SOC value. The power allocation strategy employs a rule-based energy management strategy, optimized in conjunction with an equivalent fuel consumption minimization strategy (ECMS). The power allocation unit 32 has a built-in power allocation mapping table that queries the target power allocation ratio based on the operating condition type and SOC value. In this embodiment, the power allocation strategy is as follows: Under plowing conditions, due to high operating resistance, low vehicle speed, and the engine operating in the low-speed, high-torque range, the electric motor is prioritized for drive to reduce emissions. When the State of Charge (SOC) is greater than 50%, the power distribution ratio is 70% for the electric motor and 30% for the engine, with the electric motor as the primary power source and the engine operating in its lowest stable speed range to charge the battery. When the SOC is between 30% and 50%, the power distribution ratio is 50% for the electric motor and 50% for the engine, with the engine and motor working together. When the SOC is less than 30%, the power distribution ratio is 30% for the electric motor and 70% for the engine, with the engine as the primary power source while simultaneously charging the battery. Under plowing conditions, the engine's target speed is controlled within the low-speed, high-efficiency range of 1400-1600 rpm to avoid excessive smoke emissions from the engine in the low-speed, high-torque range.

[0045] Under transport conditions, due to higher vehicle speeds, relatively stable loads, and the engine operating in the medium-to-high speed range, engine-driven operation is prioritized to improve fuel economy. When the State of Charge (SOC) is greater than 50%, the power distribution ratio is 80% engine and 20% electric motor, with the engine as the primary power source and the electric motor only providing auxiliary torque during acceleration or hill climbing. When the SOC is between 30% and 50%, the power distribution ratio is 90% engine and 10% electric motor, with the engine as the primary power source and the electric motor providing a small amount of auxiliary torque. When the SOC is less than 30%, the power distribution ratio is 100% engine and 0% electric motor, with the engine driving solely and simultaneously charging the battery. Under transport conditions, the target engine speed is controlled within the high-speed, high-efficiency range of 1800-2200 rpm, utilizing the engine's high-speed economic characteristics to reduce fuel consumption.

[0046] Under PTO output conditions, engine 11 primarily bears the PTO load, while motor 12 bears the drive load. The PTO output power is typically 30%-50% of the engine's rated power; in this embodiment, the PTO output power requirement is approximately 30-45kW. The power allocation strategy is: Engine output power = PTO power requirement + Drive power requirement × Engine allocation ratio. When the State of Charge (SOC) is greater than 40%, the drive power is borne by the motor, and the engine focuses on PTO output; when the SOC is less than 40%, the engine simultaneously bears both PTO output and part of the drive power, with the remaining drive power borne by the motor. Under PTO conditions, the target engine speed is determined based on the PTO speed requirement; the standard PTO speed is 540rpm or 1000rpm, corresponding to an engine speed of PTO speed × transmission PTO gear ratio.

[0047] Under no-load conditions, the power source is determined by the battery's State of Charge (SOC). When the SOC is greater than 60%, pure electric mode is used, with the engine off or idling, and the electric motor driving alone to achieve zero-emission driving. When the SOC is between 40% and 60%, a hybrid drive mode is used, with the engine and electric motor working together, and the engine operating in its high-efficiency range. When the SOC is less than 40%, engine-driven mode is used, with the engine driving alone while simultaneously charging the battery. Under no-load conditions, the vehicle speed is typically low (less than 15 km / h), and electric motor drive can meet the power requirements while avoiding the efficiency drop caused by the engine operating in a low-load range.

[0048] When the battery's state of charge (SOC) value is lower than a preset threshold, the engine torque limiting unit 33 limits the maximum torque output of the engine 11 to 80% of its rated torque, using the remaining power to charge the battery pack 13. The purpose of engine torque limiting is to prioritize battery charge recovery while ensuring power demand, preventing excessive battery discharge. The engine torque limiting unit 33 sets multiple SOC thresholds: when the SOC is below 30%, the maximum engine torque is limited to 90% of the rated torque; when the SOC is below 25%, the maximum engine torque is limited to 80% of the rated torque; when the SOC is below 20%, the maximum engine torque is limited to 70% of the rated torque, simultaneously triggering a low battery alarm to prompt the driver to charge the battery or reduce the load as soon as possible. The engine torque limiting unit 33 also sets a gradual torque limiting strategy, with the torque limit value smoothly transitioning within 5 seconds to avoid driving discomfort caused by sudden torque changes. The engine torque limiting unit 33 also monitors the engine status; when the engine coolant temperature is too high or the oil pressure is too low, the torque limiting is canceled to prioritize engine protection.

[0049] The shift strategy module 4 includes a gear prediction unit 41, a shift smoothness control unit 42, and a shift torque compensation unit 43. The main function of the shift strategy module 4 is to intelligently predict the target gear based on torque demand and vehicle speed changes, and coordinate and control the shift process to achieve smooth shifting.

[0050] The gear prediction unit 41 includes a torque demand analysis subunit 411, a vehicle speed trend prediction subunit 412, and a gear decision subunit 413. The main function of the gear prediction unit 41 is to predict the next target gear based on the current torque demand change rate and vehicle speed change trend, providing a decision basis for gear shift control.

[0051] The torque demand analysis subunit 411 collects accelerator pedal opening signals, operating resistance signals, and gradient signals, and combines them with a preset torque demand calculation model to obtain the current torque demand value and its rate of change over time. The torque demand calculation model is: Torque Demand = Base Torque × Throttle Coefficient × Resistance Coefficient × Gradient Coefficient. The base torque is obtained by looking up a table based on vehicle speed and gear, representing the torque demand when driving at a constant speed on a flat road; the throttle coefficient is calculated based on the accelerator pedal opening, with a coefficient of 0 when the throttle opening is 0% and 1.5 when the throttle opening is 100%; the resistance coefficient is calculated based on the operating resistance, with a larger coefficient for greater resistance; the gradient coefficient is calculated based on the gradient, with a coefficient greater than 1 for uphill driving and less than 1 for downhill driving. The rate of change of torque demand is calculated using numerical differentiation, with the formula: Torque Demand Change Rate = (Current Torque Demand - Previous Torque Demand) / Sampling Period. In this embodiment, the sampling period is 10ms. The torque demand analysis subunit 411 sets two thresholds: the first preset threshold is set to 50 Nm / s. When the torque demand change rate exceeds 50 Nm / s, it is determined to be a rapid acceleration condition, and it is predicted that a downshift is needed to provide greater torque; the second preset threshold is set to 10 Nm / s. When the torque demand change rate is less than 10 Nm / s, it is determined to be a gradual change condition, and the current gear is maintained or the gear is predicted based on the vehicle speed trend.

[0052] The vehicle speed trend prediction subunit 412 uses a Kalman filter algorithm to smooth the vehicle speed signal, eliminate noise interference, and calculates the predicted vehicle speed value based on historical vehicle speed data and current acceleration. The state equation of the Kalman filter is: Vehicle speed (k+1) = Vehicle speed (k) + Acceleration (k) × Δt, and the observation equation is: Observed vehicle speed (k) = Vehicle speed (k) + Measurement noise. The parameters of the Kalman filter are set as follows: Process noise covariance Q = 0.1, Measurement noise covariance R = 1.0, and Initial state covariance P = 1.0. The vehicle speed prediction uses a linear extrapolation method, and the prediction formula is: Predicted vehicle speed = Current vehicle speed + Current acceleration × Prediction time domain. In this embodiment, the prediction time domain is set to 2 seconds, that is, predicting the vehicle speed within the next 2 seconds. The vehicle speed trend prediction subunit 412 generates a shift tendency signal based on the predicted vehicle speed: when the predicted vehicle speed increases and exceeds the upper limit of the optimal economic speed range for the current gear, an upshift tendency signal is generated; when the predicted vehicle speed decreases and falls below the lower limit of the optimal power speed range for the current gear, a downshift tendency signal is generated. The optimal economic speed range and the optimal power speed range are determined based on the engine's universal characteristic curve. In this embodiment, the optimal economic speed range is 1600-2000 rpm, and the optimal power speed range is 1800-2200 rpm.

[0053] The gear selection decision subunit 413 determines the target gear by querying a preset gear mapping table. The gear mapping table is a three-dimensional lookup table structure; the input variables are engine speed, vehicle speed, and torque demand, and the output variable is the target gear. The gear mapping table is established based on engine speed, vehicle speed, torque demand, and operating condition, covering an engine speed range of 800-2400 rpm, a vehicle speed range of 0-40 km / h, and a torque demand range of 0-500 Nm. The gear mapping table is established as follows: first, the economic speed range and power speed range of each gear are determined based on the engine's universal characteristic curve; then, the corresponding engine speed is calculated based on the vehicle speed and gear ratio; finally, the selection of either the economic gear or the power gear is determined based on the torque demand. The gear selection decision subunit 413 also sets a shift delay interval to prevent frequent shifting. The shift delay interval is: when the engine speed is within the range of 1500-1800 rpm, no shifting operation is performed to avoid frequent switching at shift boundaries. The gear shift decision subunit 413 also sets a shift cooling time, with a minimum time interval of 3 seconds between two shifts to prevent the transmission from overheating due to continuous shifting.

[0054] The shift smoothness control unit 42 includes a shift phase division subunit 421, a torque coordination control subunit 422, and an impact monitoring subunit 423. The main function of the shift smoothness control unit 42 is to coordinate and control the engine torque and the electric motor torque during shifting, reduce the impact on the transmission system, and improve the shift quality.

[0055] The shift phase segmentation subunit 421 divides the shifting process into three phases: the torque phase, the inertia phase, and the synchronization phase. The torque phase is the clutch disengagement phase, during which the clutch of the original gear gradually disengages, and the transmitted torque gradually decreases, lasting approximately 100-200ms. The inertia phase is the engine speed adjustment phase, during which the engine speed adjusts from the speed corresponding to the original gear to the speed corresponding to the target gear, lasting approximately 200-400ms. The synchronization phase is the new gear engagement phase, during which the clutch of the target gear gradually engages, and the transmitted torque gradually increases, lasting approximately 100-200ms. The shift phase segmentation subunit 421 determines the current shift phase based on the ratio of the input shaft speed to the output shaft speed of the transmission. Specifically, the judgment logic is as follows: when the input shaft speed / output shaft speed equals the original gear ratio, it is in the torque phase; when the input shaft speed / output shaft speed varies between the original gear ratio and the target gear ratio, it is in the inertia phase; and when the input shaft speed / output shaft speed equals the target gear ratio, it is in the synchronization phase. The shift phase division subunit 421 has a sampling period of 5ms to monitor the shift process in real time.

[0056] The torque coordination control subunit 422 employs different control strategies at each stage. In the torque phase, the engine torque is controlled to decrease at a first preset slope, while the motor torque is controlled to increase at a second preset slope to compensate for output torque loss. In this embodiment, the first preset slope is set to 100 Nm / s, meaning the engine torque decreases by 100 Nm per second; the second preset slope is set to 150 Nm / s, meaning the motor torque increases by 150 Nm per second. The motor torque increase rate is greater than the engine torque decrease rate to compensate for torque loss during clutch disengagement and maintain stable output torque. In the inertia phase, the speed adjustment amount is calculated based on the difference between the target speed and the actual speed, and the motor is controlled to operate in speed mode to assist the engine in quickly reaching the target speed. The speed adjustment amount is calculated as follows: Speed ​​adjustment amount = Kp_n × speed difference + Ki_n × integral of speed difference + Kd_n × derivative of speed difference, where Kp_n = 0.5, Ki_n = 0.1, and Kd_n = 0.05. When the motor operates in speed mode, the output torque is automatically adjusted by the speed controller to achieve rapid and precise adjustment of the engine speed. During the synchronization phase, the engine torque and motor torque are controlled to rise synchronously to the target torque value according to a third preset slope. In this embodiment, the third preset slope is set to 80 Nm / s, and the engine torque and motor torque rise synchronously, maintaining a constant power distribution ratio. The torque coordination control subunit 422 also sets upper and lower limits for torque change: the upper limit of the engine torque change rate is 200 Nm / s, and the lower limit is -200 Nm / s; the upper limit of the motor torque change rate is 300 Nm / s, and the lower limit is -300 Nm / s.

[0057] The impact monitoring subunit 423 collects the vehicle's longitudinal acceleration signal through an acceleration sensor installed on the rear axle, with a sampling frequency of 200Hz. The impact is calculated by taking the derivative of acceleration with respect to time. The formula for calculating impact is: Impact = da / dt = (a(k) - a(k-1)) / Δt, where a is the longitudinal acceleration and Δt is the sampling period (5ms). The impact monitoring subunit 423 filters the impact signal using a second-order low-pass filter with a cutoff frequency of 20Hz to eliminate high-frequency noise. In this embodiment, the preset impact threshold is set to 10m / s³. When the impact exceeds this threshold, it is determined that the shift impact is too large, and the slope of the engine torque and motor torque changes is automatically adjusted. The adjustment strategy is to reduce the current torque change slope by 20% and extend the shift time by 10% to reduce the impact. The impact monitoring subunit 423 also records the maximum and average impact for each shift, used for shift quality evaluation and parameter optimization.

[0058] The shift torque compensation unit 43 includes a downshift torque compensation subunit 431, an upshift torque absorption subunit 432, and a compensation amount adaptive adjustment subunit 433. The main function of the shift torque compensation unit 43 is to utilize the rapid response characteristics of the motor during the shift process to fill the torque gap or absorb excess torque, thereby achieving shifting without power interruption.

[0059] At the start of downshifting, the downshift torque compensation subunit 431 calculates the torque gap based on the change in speed ratio before and after downshifting, and controls the motor to output positive torque to fill the torque gap. The formula for calculating the torque gap is: Torque gap = Output torque demand × (New speed ratio - Original speed ratio) / New speed ratio. For example, when downshifting from 3rd gear to 2nd gear, the speed ratio of 3rd gear is 1.5 and the speed ratio of 2nd gear is 2.0. If the output torque demand is 500 Nm, then the torque gap = 500 × (2.0 - 1.5) / 2.0 = 125 Nm. The downshift torque compensation subunit 431 controls the motor to output a positive torque of 125 Nm to fill the torque gap caused by the increase in speed ratio and maintain the stability of the output torque. The execution process of downshift torque compensation is as follows: In the torque phase, the motor torque rises from 0 at a preset slope to the compensation torque value; in the inertia phase, the motor maintains the compensation torque output; in the synchronization phase, the motor torque gradually decreases to the target torque value. The downshift torque compensation subunit 431 also sets upper and lower limits for the compensation torque, with the upper limit being 80% of the peak torque of the motor (240Nm) and the lower limit being 0.

[0060] At the start of upshifting, the torque absorption subunit 432 calculates the torque surplus based on the change in speed ratio before and after upshifting, controls the motor to operate in generator mode to absorb the excess torque, and stores the absorbed energy in the battery pack 13. The formula for calculating the torque surplus is: Torque Surplus = Output Torque Demand × (Original Speed ​​Ratio - New Speed ​​Ratio) / Original Speed ​​Ratio. For example, when upshifting from 2nd gear to 3rd gear, the speed ratio of 2nd gear is 2.0 and the speed ratio of 3rd gear is 1.5. If the output torque demand is 500 Nm, then the torque surplus = 500 × (2.0 - 1.5) / 2.0 = 125 Nm. The torque absorption subunit 432 controls the motor to operate in generator mode, absorbing 125 Nm of torque, eliminating the torque surplus caused by the decrease in speed ratio, and preventing sudden changes in output torque. The formula for calculating the absorbed energy is: Absorbed Energy = Motor Torque × Motor Speed ​​× Efficiency × Time. In this embodiment, the average motor speed during the upshift process is approximately 1500 rpm, the absorption efficiency is approximately 85%, and the absorption time is 0.5 seconds. Therefore, the absorbed energy is approximately 125 × 157 × 0.85 × 0.5 = 8.3 kJ. The upshift torque absorption subunit 432 also sets upper and lower limits for the absorbed torque, with the upper limit being 50% of the motor's peak torque (150 Nm) and the lower limit being 0.

[0061] The adaptive adjustment subunit 433 collects the actual impact and shift time during the gear shifting process and performs adaptive adjustments to optimize shift quality. The adaptive adjustment strategy is as follows: When the actual impact is greater than the target impact (e.g., 5 m / s³), the response speed of the motor's compensation torque is increased, raising the torque change rate by 20% to enable the motor to respond to torque compensation requirements more quickly; when the shift time exceeds the preset shift time threshold (e.g., 800 ms), the amplitude of the motor's compensation torque is increased, raising the compensation torque by 10% to accelerate the shifting process; when the shift time is too short (e.g., less than 400 ms) and the impact is large, the amplitude of the motor's compensation torque is reduced, lowering the compensation torque by 10% to extend the shift time and reduce impact. The adaptive adjustment subunit 433 also limits the maximum value of the motor compensation torque based on the battery SOC value: when the battery SOC value is greater than 50%, the maximum motor compensation torque is 80% of the motor peak torque (240 Nm); when the battery SOC value is between 30% and 50%, the maximum motor compensation torque is 60% of the motor peak torque (180 Nm); and when the battery SOC value is less than 30%, the maximum motor compensation torque is 40% of the motor peak torque (120 Nm) to protect the battery from over-discharge. The adaptive adjustment subunit 433 also records the adjustment parameters for each gear shift for subsequent gear shift control parameter optimization. Second Embodiment

[0062] The present invention also provides a control method for a tractor hybrid chassis device, employing a tractor hybrid chassis device as described in any of the preceding claims. The control method includes the following steps: After the tractor starts, each controller performs a self-test, checking the status of sensors, actuators, and communication. Once the self-test passes, it reads the stored calibration parameters and the status data from the last shutdown, completing system initialization. Initialization takes approximately 2 seconds, during which the engine idles and the motor is in standby mode.

[0063] The load distribution data of the front and rear axles is collected in real time by the load sensing unit 21, with a sampling frequency of 100Hz. The center of gravity estimation unit 22 estimates the position of the overall machine's center of gravity, with a calculation period of 10ms. The attitude prediction unit 23 predicts the attitude deviation of the tractor when operating on a slope, with a prediction period of 20ms. The feedforward compensation unit 24 generates torque distribution commands, with a compensation period of 10ms.

[0064] The signal receiving subunit 311 receives input signals from each sensor, the operating condition classification subunit 312 matches the operating condition type based on the characteristics of the input signals, and the operating condition output subunit 313 sends the matched operating condition type to the energy management module 3 and the shift strategy module 4. The operating condition identification cycle is 100ms.

[0065] The power distribution unit 32 matches the target power distribution ratio between the engine 11 and the motor 12 according to the operating condition and the battery SOC value. The engine torque limiting unit 33 limits the torque output of the engine 11 to facilitate charging when the battery SOC value is below a preset threshold. The power distribution cycle is 50ms.

[0066] The torque demand analysis subunit 411 calculates the current torque demand value and its rate of change, the vehicle speed trend prediction subunit 412 predicts the vehicle speed change trend, and the gear decision subunit 413 queries the gear mapping table to determine the target gear. The gear prediction cycle is 50ms.

[0067] When a gear shift is required, the shift phase division subunit 421 divides the shift stage, the torque coordination control subunit 422 coordinates and controls the engine torque and electric motor torque, and the shift shock monitoring subunit 423 monitors the shift shock. The shift execution process lasts approximately 400-800ms.

[0068] The downshift torque compensation subunit 431 provides torque compensation during downshifting, the upshift torque absorption subunit 432 absorbs excess torque during upshifting, and the compensation amount adaptive adjustment subunit 433 adaptively adjusts the compensation parameters according to the actual impact and shift time. Torque compensation and shifting are performed synchronously.

[0069] Hybrid power module 1 coordinates the outputs of engine 11 and motor 12 according to the control commands of each module, achieving power coupling through power coupling device 14, and transmitting power to the gearbox and drive wheels. Taking a single planetary gear set as an example, the sun gear is usually connected to the motor, the planet carrier is directly connected to the engine crankshaft, and the ring gear is connected to the gearbox input shaft. This arrangement allows the engine and motor to output power to the gearbox simultaneously or individually, achieving multiple power coupling methods. The function of the planetary gears is to transmit power and change speed. They both rotate on their own axis and revolve around the sun gear with the planet carrier. This dual motion characteristic allows the planetary gear mechanism to achieve complex speed ratio changes. The power output control cycle is 10ms.

[0070] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A tractor hybrid chassis device, characterized in that, This includes a hybrid power module, a chassis dynamics control module, an energy management module, and a shift strategy module; The hybrid power module includes an engine, an electric motor, a battery pack, and a power coupling device; The chassis power control module is electrically connected to the hybrid power module. It is used to collect chassis status parameters in real time and generate control commands. Then, it predicts chassis attitude deviation based on the changes in the steering angle of the tractor's front wheels and the load on the front axle, and corrects the control commands in real time based on the actual attitude deviation. The energy management module is used to dynamically allocate the power output ratio between the engine and the motor according to the chassis status parameters, battery SOC value and operating conditions. The shift strategy module is used to realize automatic shift control of the multi-gear transmission according to the control commands output by the chassis power control module. The control commands include torque requirements and speed requirements.

2. The tractor hybrid chassis device as described in claim 1, characterized in that, The chassis dynamic control module includes a load sensing unit, a center of gravity estimation unit, an attitude prediction unit, and a feedforward compensation unit. The load sensing unit is used to collect load distribution data of the front axle and the rear axle in real time and generate control commands, including torque distribution of the left and right drive wheels. The center of gravity estimation unit is used to estimate the position of the overall center of gravity based on the load distribution data and the geometric parameters of the tractor. The attitude prediction unit is used to predict the attitude deviation of the tractor when working on a slope based on the center of gravity position, front wheel steering angle and working resistance. The feedforward compensation unit adjusts the torque distribution of the left and right drive wheels in advance based on the attitude deviation to correct the control command.

3. A tractor hybrid chassis device as described in claim 2, characterized in that, The energy management module includes an operating condition identification unit, a power distribution unit, and an engine torque limiting unit. The working condition identification unit is used to identify the working condition type of the tractor, including plowing condition, transport condition, PTO output condition and no-load condition. The power distribution unit is used to match the target power distribution ratio between the engine and the motor according to the type of operating condition and the battery SOC value. The engine torque limiting unit is used to limit the engine torque output for charging when the battery SOC value is lower than a preset threshold.

4. A tractor hybrid chassis device as described in claim 3, characterized in that, The operating condition identification unit includes a signal receiving subunit, an operating condition classification subunit, and an operating condition output subunit; The signal receiving subunit is used to receive input signals, including chassis status parameter signals, engine operating parameter signals, motor operating parameter signals, and gearbox gear signals. The working condition classification subunit is used to perform working condition type matching based on the input signal. The identified working condition types include plowing working condition, transportation working condition, PTO output working condition, and empty running working condition. The operating condition output subunit is used to send the matched operating condition type to the energy management module and the shifting strategy module.

5. A tractor hybrid chassis device as described in claim 4, characterized in that, The power distribution unit is also configured to prioritize the use of electric motor drive to reduce emissions during plowing operations and to prioritize the use of engine drive to improve fuel economy during transportation operations.

6. A tractor hybrid chassis device as described in claim 5, characterized in that, The shifting strategy module includes a gear prediction unit, a shifting smoothness control unit, and a shifting torque compensation unit: The gear prediction unit is used to predict the next target gear based on the current rate of change of torque demand and the trend of vehicle speed change. The shift smoothness control unit is used to coordinate and control the engine torque and motor torque during shifting to reduce the impact on the transmission system. The shift torque compensation unit is used to provide auxiliary torque compensation through the motor when downshifting and to absorb excess torque through the motor when upshifting.

7. A tractor hybrid chassis device as described in claim 6, characterized in that, The gear prediction unit includes a torque demand analysis subunit, a vehicle speed trend prediction subunit, and a gear decision subunit: The torque demand analysis subunit collects accelerator pedal opening signal, working resistance signal and slope signal, and combines them with a preset torque demand calculation model to obtain the current torque demand value and its rate of change over time. When the rate of change of torque demand exceeds the first preset threshold, it is determined to be a rapid acceleration condition. When the rate of change of torque demand is lower than the second preset threshold, it is determined to be a gradual change condition. The vehicle speed trend prediction subunit is used to smooth the vehicle speed signal using a Kalman filter algorithm and calculate the vehicle speed prediction value based on historical vehicle speed data and current acceleration. When the predicted vehicle speed increases and exceeds the upper limit of the optimal economic speed range of the current gear, an upshift tendency signal is generated. When the predicted vehicle speed decreases and is lower than the lower limit of the optimal power speed range of the current gear, a downshift tendency signal is generated. The gear decision subunit is used to determine the target gear by querying a preset gear mapping table. The gear mapping table is established based on engine speed, vehicle speed, torque requirements and operating conditions, and a shift delay interval is set to prevent frequent gear shifting.

8. A tractor hybrid chassis device as described in claim 7, characterized in that, The shift smoothness control unit includes a shift phase division subunit, a torque coordination control subunit, and an impact monitoring subunit. The shift phase division subunit is used to divide the shift process into three stages: torque phase, inertia phase, and synchronization phase. The torque phase is the clutch disengagement phase, the inertia phase is the engine speed adjustment phase, and the synchronization phase is the new gear engagement phase. The current shift phase is determined based on the ratio of the input shaft speed to the output shaft speed of the transmission. The torque coordination control subunit is used to control the engine torque to decrease at a first preset slope and simultaneously control the motor torque to increase at a second preset slope to compensate for the output torque loss during the torque phase phase. During the inertia phase phase, the speed adjustment amount is calculated based on the difference between the target speed and the actual speed, and the motor is controlled to run in speed mode to assist the engine in quickly reaching the target speed. During the synchronization phase phase, the engine torque and motor torque are controlled to increase synchronously to the target torque value at a third preset slope. The impact monitoring subunit is used to collect the longitudinal acceleration signal of the vehicle through an acceleration sensor, calculate the derivative of acceleration with respect to time to obtain the impact, and adjust the slope of the change of engine torque and motor torque to reduce the impact when the impact exceeds a preset impact threshold.

9. A tractor hybrid chassis device as described in claim 8, characterized in that, The shift torque compensation unit includes a downshift torque compensation subunit, an upshift torque absorption subunit, and a compensation amount adaptive adjustment subunit: The downshift torque compensation subunit is used to calculate the torque gap based on the speed ratio change before and after downshifting at the start of downshifting, and control the motor to output positive torque to fill the torque gap. The upshift torque absorption subunit is used to calculate the torque surplus based on the speed ratio change before and after upshifting at the start of upshifting, control the motor to work in the power generation mode to absorb the excess torque, and store the absorbed energy in the battery pack. The adaptive adjustment subunit for compensation amount is used to collect the actual impact and shift time during the shift process. When the actual impact is greater than the target impact, the response speed of the motor compensation torque is increased. When the shift time exceeds the preset shift time threshold, the amplitude of the motor compensation torque is increased, and the maximum value of the motor compensation torque is limited according to the battery SOC value. When the battery SOC value is lower than the preset SOC threshold, the maximum value of the motor compensation torque is reduced.

10. A control method for a tractor hybrid chassis device, characterized in that, The tractor hybrid chassis device according to any one of claims 1-9 is adopted.

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