Power dividing type hybrid power tractor driving system and control method

Abstract

The invention provides a power dividing type hybrid power tractor driving system. The power dividing type hybrid power tractor driving system comprises a power source and a power dividing type multi-mode switching mechanical transmission system, wherein the power source is composed of an engine, a P3 motor and a PS motor. The invention further provides a control method of the power split type hybrid power tractor driving system. Through the arrangement of the P3 motor, the PS motor, the power coupling mechanism, the clutch and the brake, energy distribution and efficient work of the engine are achieved. The device is compact in structure and good in dynamic property and economical efficiency, can realize multi-mode driving operation according to complex working conditions of the tractor, and has the advantages of interval stepless speed change, accurate control and the like.

Description

Technical Field

[0001] The present invention relates to the field of hybrid tractors, and particularly to a power split hybrid tractor drive system and a control method thereof. Background Art

[0002] With the increasingly serious problems of oil energy shortage and air pollution, it is extremely urgent to vigorously develop the new energy vehicle industry. Hybrid vehicles combine the advantages of electric vehicles and traditional vehicles and have become a research hotspot at home and abroad in recent years. As the agricultural machinery equipment with the largest application amount in the agricultural production process, tractors mainly use fuel engines as power at present. There are high environmental pollution problems during the operation of complex working conditions. The application of hybrid technology can effectively improve the disadvantages in the use process of tractors.

[0003] The hybrid system has the advantages of high flexibility in structural design and high efficiency. Compared with traditional stepped transmission tractors, it can effectively solve the problems that the engine operating point is extremely vulnerable to external load disturbances and difficult speed regulation. The hybrid system optimizes the engine working area by adding a dual-motor, thereby improving energy efficiency. Therefore, researching energy-saving and environment-friendly agricultural vehicles, especially hybrid tractors, is an important way to solve the energy crisis and environmental pollution problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a power split hybrid tractor drive system and a control method thereof. The drive system can not only switch between multiple drive modes to meet the requirements of the complex working environment of the tractor, but also has the advantages of stepless speed change in a range and precise control, etc., and can effectively improve the power performance, economy and driving comfort of the tractor.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A power split hybrid tractor drive system includes an overall controller, a power battery pack, a power management system, a distribution box, an engine, a P3 motor and a PS motor installed on the hybrid tractor. The overall controller is respectively connected to an engine controller, a mechanical transmission system controller, a power management system, a P3 motor controller and a PS motor controller. The overall controller and the distribution box are connected by a control circuit. The overall controller is used to control the normal operation of the hybrid tractor. The engine controller, the P3 motor controller and the PS motor controller respectively control the driving of the engine, the P3 motor and the PS motor; the power management system controls the charging and discharging of the power battery pack; the mechanical transmission system controller controls the operation of the tractor mechanical transmission system;

[0007] The mechanical transmission system includes a P3 motor shaft, a PS motor shaft, a reduction device, an engine shaft, a brake, a power reversing device, a power output speed change device, a power output shaft, a power coupling device, an intermediate shaft, and a central transmission shaft;

[0008] The front end of the P3 motor shaft is connected to the P3 motor, and the rear end is connected to the central transmission shaft through the reduction device; the front end of the PS motor shaft is connected to the PS motor, and the rear end is connected to the power coupling device. The power coupling device is coupled to the intermediate shaft and is also connected to the central transmission shaft;

[0009] The engine shaft is connected to the engine; the engine shaft is coupled to the power reversing device, and the power reversing device is coupled to the power coupling device; the engine shaft is connected to the power output speed change device, and the power output speed change device is coupled to the power output shaft;

[0010] The brake is connected to the PS motor shaft, and the connection or separation between the PS motor shaft and the frame is achieved by controlling the brake;

[0011] The power output shaft is connected to agricultural implements;

[0012] The central transmission shaft is connected to the central transmission of the tractor.

[0013] The reduction device includes a reduction sun gear, reduction planet gears, a reduction ring gear, and a reduction planet carrier; the reduction planet gears are installed on the reduction planet carrier, and the reduction planet gears are respectively meshed with the reduction ring gear and the reduction sun gear; the rear end of the P3 motor shaft is connected to the reduction sun gear.

[0014] The power coupling device (21) includes a coupling sun gear (2101), a coupling planet carrier (2102), coupling planet gears, a coupling ring gear, a first-gear driving gear, a second-gear driving gear, a third-gear driving gear, a first-gear clutch, a third-gear clutch, a second-gear clutch, a third-gear driven gear, a second-gear driven gear, and a first-gear driven gear; the coupling planet gears are installed on the coupling planet carrier, and the coupling planet gears are meshed with the coupling ring gear and the coupling sun gear; the first-gear driving gear is meshed with the first-gear driven gear, and the connection or disconnection between the first-gear driving gear and the intermediate shaft is achieved by controlling the first-gear clutch; the second-gear driving gear is meshed with the second-gear driven gear, and the connection or disconnection between the second-gear driving gear and the intermediate shaft is achieved by controlling the second-gear clutch; the third-gear driving gear is meshed with the third-gear driven gear, and the connection or disconnection between the third-gear driving gear and the intermediate shaft is achieved by controlling the third-gear clutch; the intermediate shaft is connected to the coupling ring gear of the power coupling device; the third-gear driven gear, the second-gear driven gear, and the first-gear driven gear are connected to the central transmission shaft; the power coupling device can increase or decrease the gear according to the power demand of the tractor;

[0015] The described power shift device includes a mode switching clutch, a forward gear driven gear, a forward gear clutch, a forward gear driving gear, a reverse gear driving gear, a reverse gear clutch, a reverse gear transmission gear, a mode switching shaft, and a reverse gear driven gear; the mode switching clutch is connected to the mode switching shaft, and by controlling the mode switching clutch, the connection or disconnection between the mode switching shaft and the PS motor shaft is achieved; the mode switching shaft is connected to the forward gear driven gear, the reverse gear driven gear, and the coupling planet carrier; the forward gear driving gear meshes with the forward gear driven gear, and by controlling the forward gear clutch, the connection or disconnection between the forward gear driving gear and the engine shaft is achieved; the reverse gear driving gear meshes with the reverse gear transmission gear, and by controlling the reverse gear clutch, the connection or disconnection between the reverse gear driving gear and the engine shaft is achieved; the reverse gear driven gear meshes with the reverse gear transmission gear;

[0016] The rear end of the PS motor shaft is connected to the coupling sun gear of the power coupling device.

[0017] The described engine includes a diesel engine, a natural gas engine, and a hydrogen fuel engine.

[0018] The described power shift device includes a mode switching clutch, a forward gear driven gear, a forward gear clutch, a forward gear driving gear, a reverse gear driving gear, a reverse gear clutch, a reverse gear transmission gear, a mode switching shaft, and a reverse gear driven gear; the mode switching clutch is connected to the mode switching shaft, and by controlling the mode switching clutch, the connection or disconnection between the mode switching shaft and the PS motor shaft is achieved; the mode switching shaft is connected to the forward gear driven gear, the reverse gear driven gear, and the coupling planet carrier; the forward gear driving gear meshes with the forward gear driven gear, and by controlling the forward gear clutch, the connection or disconnection between the forward gear driving gear and the engine shaft is achieved; the reverse gear driving gear meshes with the reverse gear transmission gear, and by controlling the reverse gear clutch, the connection or disconnection between the reverse gear driving gear and the engine shaft is achieved; the reverse gear driven gear meshes with the reverse gear transmission gear.

[0019] The described power output speed change device includes a power output second gear clutch, a power output second gear driven gear, a power output first gear driven gear, a power output first gear clutch, a power output first gear driving gear, and a power output second gear driving gear;

[0020] The power output first-gear driving gear and the power output second-gear driving gear are connected to the engine shaft; the power output first-gear driving gear meshes with the power output first-gear driven gear, and the connection or disconnection between the power output first-gear driven gear and the power output shaft is realized by controlling the power output first-gear clutch; the power output second-gear driving gear meshes with the power output second-gear driven gear, and the connection or disconnection between the power output second-gear driven gear and the power output shaft is realized by controlling the power output second-gear clutch; the power output speed-changing device can increase or decrease the gear according to the requirements of the tractor agricultural implements.

[0021] The power management system, the distribution box, the P3 motor controller, the PS motor controller, the mechanical transmission system controller, the engine controller and the whole machine controller constitute the control system of the hybrid tractor drive system;

[0022] The whole machine controller obtains the information of the power management system, the distribution box, the P3 motor controller, the PS motor controller, the mechanical transmission system controller and the engine controller through the high-speed CAN bus; and sends control signals to the power management system, the distribution box, the P3 motor controller, the PS motor controller, the mechanical transmission system controller and the engine controller through the high-speed CAN bus; the whole machine controller obtains the hybrid tractor instrument and lighting information through the low-speed CAN bus;

[0023] The power management system controls the power battery pack, and the power battery pack supplies power to the P3 motor, the PS motor and the low-voltage storage battery through the distribution box;

[0024] The operation information of the hybrid tractor includes key signal, mode signal, position signal, torque signal and speed signal.

[0025] The present invention also provides a control method for the drive system of the power-split hybrid tractor as described above, specifically as follows: SOC is preset h as the upper limit value of the high-efficiency region of the SOC of the power battery pack; SOC l as the lower limit value of the high-efficiency region of the SOC of the power battery pack; T req,cd as the required torque of the tractor equivalent to the central drive shaft; T e_l,cd as the lower limit of the high-efficiency working range torque of the engine equivalent to the central drive shaft; T e_h,cd as the upper limit of the high-efficiency working range torque of the engine equivalent to the central drive shaft; n e_l,cd as the lower limit of the high-efficiency working range speed of the engine equivalent to the central drive shaft; n e_h,cd as the upper limit of the high-efficiency working range speed of the engine equivalent to the central drive shaft;

[0026] After the power split hybrid tractor control system is started, the whole vehicle enters the self-check of the control system. After the self-check of the system passes, the whole vehicle controller obtains the key signal, mode signal, position signal, torque signal and speed signal. The whole vehicle controller determines the starting mode of the drive system according to the obtained information, and at the same time sends control signals to the power management system, distribution box, P3 motor controller, PS motor controller, mechanical transmission system controller, and engine controller, so that the power split hybrid tractor selects to operate in different drive modes;

[0027] The drive modes of the power split hybrid tractor include:

[0028] A. Pure electric drive mode: When the power demand of the tractor cannot achieve the engine working in the high-efficiency area, and the SOC of the power battery pack satisfies SOC > SOC l , the tractor demand torque satisfies T req,cd ≤T e_l,cd , the demand speed satisfies n req,cd ≤n e_h,cd , switch to the pure electric drive mode; at this time, the engine is turned off, and the power battery pack provides energy to the P3 motor and PS motor in the best economic control mode according to the demand power to drive the vehicle to move forward. The P3 motor and PS motor drive the vehicle independently, or the P3 motor and PS motor drive the vehicle through the torque coupling method;

[0029] B. Series electric drive mode: When the power demand of the tractor cannot achieve the engine working in the high-efficiency area, and the state of charge SOC of the power battery pack ≤ SOC l , the tractor demand torque satisfies T req,cd ≤T e_l,cd , the demand speed satisfies n req,cd ≤n e_h,cd , switch to the series drive mode; at this time, the PS motor drives the engine to start, and then drives the PS motor to generate electricity. The power battery pack and the P3 motor provide energy for the P3 motor drive simultaneously or the PS motor alone; when the SOC of the power battery pack reaches SOC l , charging protection is carried out. The engine drives the PS motor to generate electricity, and the PS motor provides energy for the P3 motor and the power battery pack simultaneously. When it reaches SOC h , trickle charging protection is carried out; in this mode, the engine is decoupled from the tractor running system, allowing the engine to operate in the best working condition to drive the PS motor to generate electricity, providing energy for the P3 motor and the power battery pack, and providing power for the tractor running system in series;

[0030] C. Engine independent drive mode: When the power demand of the tractor reaches the best working condition range of the engine and the tractor running speed and external working environment change little, and the tractor demand torque satisfies Te_l,cd <T req,cd ≤T e_h,cd When the required rotational speed satisfies n e_l,cd <n req,cd ≤n e_h,cd , switch to the engine independent drive mode; at this time, both the P3 motor and the PS motor do not work, and the power of the engine is all transmitted to the walking system by mechanical transmission. Since the power does not pass through the electric drive device, the energy loss caused by energy conversion can be avoided, and the system efficiency is the highest in this mode;

[0031] D. Torque coupling drive mode: When the torque demand of the tractor changes greatly and the SOC of the power battery pack satisfies SOC > SOC l When the required torque of the tractor satisfies T req,cd >T e_h,cd When the required rotational speed satisfies n e_l,cd <

[0032] n req,cd ≤n e_h,cd , switch to the torque coupling drive mode. The PS motor absorbs the excess power output by the engine to convert it into electrical energy and store it in the power battery pack or supply it to the P3 motor. The engine and the P3 motor provide power for the tractor walking system through torque coupling;

[0033] E. Power coupling drive mode: When the rotational speed demand of the tractor changes greatly and the SOC of the power battery pack satisfies SOC > SOC l When the required torque of the tractor satisfies T e_l,cd <T req,cd ≤T e_h,cd When the required rotational speed satisfies n req,cd >n e_h,cd , switch to the power coupling drive mode. The P3 motor absorbs the excess power output by the engine to convert it into electrical energy and store it in the power battery pack or supply it to the PS motor. The engine, the PS motor and the P3 motor provide power for the tractor walking system through power coupling;

[0034] F. Energy recovery mode: When the tractor brakes or decelerates, the required torque T of the tractor req,cd <0. The mechanical energy of the walking system drags reversely, and the P3 motor generates electricity to realize braking / deceleration energy recovery. At this time, the engine stops or decouples from the tractor walking system.

[0035] The beneficial effects brought by the present invention are:

[0036] 1. The power-split hybrid system described in the present invention can adjust the dual motors to enable the engine to operate in the optimal working range, improve its fuel economy through the energy flow path, and combine the easy control of electric drive with the high efficiency of mechanical drive, effectively enhancing the performance of the whole vehicle and achieving stepless speed change in the range.

[0037] 2. The power-split hybrid system consists of an engine, dual motors, and a power-split mechanical transmission system. Through control, six modes including pure electric drive, series drive, engine independent drive, torque coupling drive, power coupling drive, and energy recovery can be achieved. The multi-mode drive method is beneficial for the tractor to operate in various complex environments, improving the power performance, economy, and adaptability of the whole vehicle.

[0038] 3. The power reversing device of the mechanical transmission system can make the number of forward gears and reverse gears of the tractor the same, improving the working ability of the tractor when reversing, which is beneficial for improving the flexibility of the tractor in field operations.

[0039] 4. The power coupling device of the mechanical transmission system can achieve torque coupling between the engine and the P3 motor, reducing the complexity of the tractor transmission system. At the same time, it can meet the operating requirements of the tractor with low speed and large torque, effectively enhancing the traction characteristics of the tractor.

[0040] 5. The power coupling device of the mechanical transmission system can achieve power coupling among the engine, the PS motor, and the P3 motor, reducing the complexity of the tractor transmission system. At the same time, it can meet the operating requirements of stepless speed change in the range of the tractor.

[0041] 6. When the hybrid tractor is in a short-term stop in place or braking while moving, the system enters the energy recovery mode, improving the overall energy utilization rate of the machine. Brief Description of the Drawings

[0042] Figure 1 is a schematic structural diagram of the drive system of a power-split hybrid tractor;

[0043] Figure 2 is a schematic structural diagram of the mechanical transmission system;

[0044] Figure 3 is a schematic structural diagram of the reduction device of the mechanical transmission system;

[0045] Figure 4 is a schematic structural diagram of the reversing device of the mechanical transmission system;

[0046] Figure 5 is a schematic structural diagram of the power output speed change device of the mechanical transmission system;

[0047] Figure 6 is a schematic structural diagram of the power coupling device of the mechanical transmission system;

[0048] Figure 7 is the circuit connection diagram of the power split hybrid tractor drive system;

[0049] Figure 8 is the control method flowchart of the power split hybrid tractor drive system.

[0050] The reference numerals in the attached drawings are explained as follows:

[0051] 1. Power battery pack, 2. P3 motor, 3. Power management system, 4. Distribution box, 5. P3 motor controller, 6. PS motor controller, 7. Mechanical transmission system controller, 8. Engine controller, 9. Whole machine controller, 10. PS motor, 11. Engine, 12. Mechanical transmission system, 13. P3 motor shaft, 14. PS motor shaft, 15. Reduction device, 1501. Reduction sun gear, 1502. Reduction planet gear, 1503. Reduction ring gear, 1504. Reduction planet carrier, 16. Engine shaft, 17. Brake, 18. Power reversing device, 1801. Mode switching clutch, 1802. Forward gear driven gear, 1803. Forward gear clutch, 1804. Forward gear driving gear, 1805. Reverse gear driving gear, 1806. Reverse gear clutch, 1807. Reverse gear transmission gear, 1808. Mode switching shaft, 1809. Reverse gear driven gear, 19. Power take-off speed change device, 1901. Power take-off second gear clutch, 1902. Power take-off second gear driven gear, 1903. Power take-off first gear driven gear, 1904. Power take-off first gear clutch, 1905. Power take-off first gear driving gear, 1906. Power take-off second gear driving gear, 20. Power take-off shaft, 21. Power coupling device, 2101. Coupling sun gear, 2102. Coupling planet carrier, 2103. Coupling planet gear, 2104. Coupling ring gear, 2105. Coupling first gear driving gear, 2106. Coupling second gear driving gear, 2107. Coupling third gear driving gear, 2108. Coupling first gear clutch, 2109. Coupling third gear clutch, 2110. Coupling second gear clutch, 2111. Coupling third gear driven gear, 2112. Coupling second gear driven gear, 2113. Coupling first gear driven gear, 22. Intermediate shaft, 23. Central transmission shaft. Detailed implementation mode

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the "first", "second" and "third" in the following embodiments are only used to distinguish the device names and do not have specific meanings.

[0053] Refer to Figure 1, A power-split hybrid tractor drive system, including a power battery pack 1, a distribution box 4, a P3 motor 2 and a PS motor 10 which are connected by high-voltage circuits and installed on the hybrid tractor. The whole machine controller 9 is respectively connected to the engine controller 8, the mechanical transmission system controller 7, the power management system 3, the P3 motor controller 5, the PS motor controller 6 and the distribution box 4 through control circuits. The whole machine controller 9 is used to control the normal operation of the hybrid tractor. The engine controller 8, the P3 motor controller 5 and the PS motor controller 6 respectively control the drives of the engine 11, the P3 motor 2 and the PS motor 10. The power management system 3 controls the charging and discharging of the power battery pack 1. The mechanical transmission system controller 7 controls the operation of the tractor mechanical transmission system 12.

[0054] Refer to Figure 2 , The mechanical transmission system 12 includes a P3 motor shaft 13, a PS motor shaft 14, a reduction device 15, an engine shaft 16, a brake 17, a power reversing device 18, a power output speed-changing device 19, a power output shaft 20, a power coupling device 21, an intermediate shaft 22 and a central transmission shaft 23;

[0055] The front end of the P3 motor shaft 13 is connected to the P3 motor 2, and the rear end is connected to the reduction sun gear 1501 of the reduction device 15;

[0056] The front end of the PS motor shaft 14 is connected to the PS motor 10, and the rear end is connected to the coupling sun gear 2101 of the power coupling device 21;

[0057] Refer to Figure 3 , The reduction device 15 includes a reduction sun gear 1501, a reduction planet gear 1502, a reduction ring gear 1503 and a reduction planet carrier 1504; The reduction planet carrier 1504 is fixed to the reduction planet gear 1502, and the reduction planet gear 1502 meshes with the reduction ring gear 1503 and the reduction sun gear 1501;

[0058] The engine shaft 16 is connected to the engine 11; The engine includes a diesel engine, a natural gas engine and a hydrogen fuel engine;

[0059] The brake 17 is connected to the PS motor shaft 14, and the connection or separation between the PS motor shaft 14 and the frame is realized by controlling the brake 17;

[0060] Refer to Figure 4, the power shift device 18 includes a mode switching clutch 1801, a forward gear driven gear 1802, a forward gear clutch 1803, a forward gear driving gear 1804, a reverse gear driving gear 1805, a reverse gear clutch 1806, a reverse gear transmission gear 1807, a mode switching shaft 1808 and a reverse gear driven gear 1809; the mode switching clutch 1801 is connected to the mode switching shaft 1808, and by controlling the mode switching clutch 1801, the connection or disconnection between the mode switching shaft 1808 and the PS motor shaft 14 is realized; the mode switching shaft 1808 is connected to the forward gear driven gear 1802, the reverse gear driven gear 1809 and the coupling planet carrier 2102; the forward gear driving gear 1804 meshes with the forward gear driven gear 1802, and by controlling the forward gear clutch 1803, the connection or disconnection between the forward gear driving gear 1804 and the engine shaft 16 is realized; the reverse gear driving gear 1805 meshes with the reverse gear transmission gear 1807, and by controlling the reverse gear clutch 1806, the connection or disconnection between the reverse gear driving gear 1805 and the engine shaft 16 is realized; the reverse gear driven gear 1809 meshes with the reverse gear transmission gear 1807;

[0061] Referring to Figure 5 , the power output speed change device 19 includes a power output second gear clutch 1901, a power output second gear driven gear 1902, a power output first gear driven gear 1903, a power output first gear clutch 1904, a power output first gear driving gear 1905 and a power output second gear driving gear 1906; the power output first gear driving gear 1905 and the power output second gear driving gear 1906 are connected to the engine shaft 16; the power output first gear driving gear 1905 meshes with the power output first gear driven gear 1903, and by controlling the power output first gear clutch 1904, the connection or disconnection between the power output first gear driven gear 1903 and the power output shaft 20 is realized; the power output second gear driving gear 1906 meshes with the power output second gear driven gear 1902, and by controlling the power output second gear clutch 1901, the connection or disconnection between the power output second gear driven gear 1902 and the power output shaft 20 is realized; the power output speed change device 19 can increase or decrease the gear according to the requirements of the tractor agricultural implements:

[0062] The power output shaft 20 is connected to the agricultural implements;

[0063] Referring to Figure 6, the power coupling device 21 includes a coupling sun gear 2101, a coupling planet carrier 2102, coupling planet gears 2103, a coupling ring gear 2104, a coupling first-gear driving gear 2105, a coupling second-gear driving gear 2106, a coupling third-gear driving gear 2107, a coupling first-gear clutch 2108, a coupling third-gear clutch 2109, a coupling second-gear clutch 2110, a coupling third-gear driven gear 2111, a coupling second-gear driven gear 2112, and a coupling first-gear driven gear 2113; the coupling planet carrier 2102 is fixed to the coupling planet gears 2103, and the coupling planet gears 2103 mesh with the coupling ring gear 2104 and the coupling sun gear 2101; the coupling first-gear driving gear 2105 meshes with the coupling first-gear driven gear 2113, and connection or disconnection between the coupling first-gear driving gear 2105 and the intermediate shaft 22 is achieved by controlling the coupling first-gear clutch 2108; the coupling second-gear driving gear 2106 meshes with the coupling second-gear driven gear 2112, and connection or disconnection between the coupling second-gear driving gear 2106 and the intermediate shaft 22 is achieved by controlling the coupling second-gear clutch 2110; the coupling third-gear driving gear 2107 meshes with the coupling third-gear driven gear 2111, and connection or disconnection between the coupling third-gear driving gear 2107 and the intermediate shaft 22 is achieved by controlling the coupling third-gear clutch 2109; the intermediate shaft 22 is connected to the coupling ring gear 2104 of the power coupling device 21; the coupling third-gear driven gear 2111, the coupling second-gear driven gear 2112, the coupling first-gear driven gear 2113, and the central transmission shaft 23 are connected; the speed coupling device 21 can increase or decrease gears according to the power demand of the tractor;

[0064] The central transmission shaft 23 is connected to the central transmission of the tractor;

[0065] Refer to Figure 7 , the power management system 3, the distribution box 4, the P3 motor controller 5, the PS motor controller 6, the mechanical transmission system controller 7, the engine controller 8, and the whole-machine controller 9 constitute the control system of the hybrid tractor drive system;

[0066] The whole-machine controller 9 obtains the information of the power management system 3, the distribution box 4, the P3 motor controller 5, the PS motor controller 6, the mechanical transmission system controller 7, and the engine controller 8 through the high-speed CAN bus; and sends control signals to the power management system 3, the distribution box 4, the P3 motor controller 5, the PS motor controller 6, the mechanical transmission system controller 7, and the engine controller 8 through the high-speed CAN bus; the whole-machine controller 9 obtains the information of the hybrid tractor instrument, lighting, etc. through the low-speed CAN bus.

[0067] The power management system 3 controls the power battery pack 1, and the power battery pack 1 supplies power to the P3 motor 2, the PS motor 10, and the low-voltage storage battery through the distribution box 5.

[0068] The operating information of the hybrid tractor includes key signal, mode signal, position signal, torque signal and speed signal.

[0069] Refer to Figure 8 , the hybrid tractor has 6 modes including pure electric drive, series electric drive, engine independent drive, torque coupling drive, power coupling drive and energy recovery.

[0070] After the hybrid tractor is started, the whole vehicle enters system self-check. After the system self-check passes, the whole vehicle controller 9 obtains the key signal, mode signal, position signal, torque signal and speed signal. The whole vehicle controller 9 determines the starting method according to the obtained information, and at the same time sends control signals to the power management system 3, distribution box 4, P3 motor controller 5, PS motor controller 6, mechanical transmission system controller 7 and engine controller 8, so that the hybrid tractor selects different operating modes:

[0071] 1) Pure electric drive mode: When the power demand of the tractor cannot enable the engine 11 to work in the high-efficiency area, and the SOC of the power battery pack 1 satisfies SOC > SOC l , the tractor demand torque satisfies T req,cd ≤T e_l,cd , the demand speed satisfies n req,cd ≤n e_h,cd , it switches to the pure electric drive mode. At this time, the engine 11 can be controlled to be turned off, and the power battery pack 1 provides energy to the P3 motor 2 and the PS motor 10 in the best economic control manner according to the demand power to drive the vehicle to move. The P3 motor 2 and the PS motor 10 drive the vehicle independently or in torque coupling, and at the same time, the advantages of the motor with low speed and large torque and pure electric drive being green and pollution-free can be utilized in this mode. For example, working conditions such as the tractor starting without load, walking without load at low speed and short-distance transfer.

[0072] 2) Series electric drive mode: When the power demand of the tractor cannot enable the engine 11 to work in the high-efficiency area, and the state of charge SOC of the power battery pack 1 ≤ SOC l , the tractor demand torque satisfies T req,cd ≤T e_l,cd , the demand speed satisfies n req,cd ≤n e_h,cd , it switches to the series drive mode. At this time, the PS motor 10 drives the engine 11 to start, and then drives the PS motor 10 to generate electricity. The power battery pack 1 and the P3 motor 2 provide energy for the P3 motor 2 to drive simultaneously or the PS motor 10 alone. When the SOC of the power battery pack 1 reaches SOC lCharging protection is carried out when the engine 11 drives the PS motor 10 to generate electricity, and the PS motor 10 provides energy for both the P3 motor 2 and the power battery pack 1 simultaneously until the SOC reaches h Trickle charging protection is carried out. In this mode, the engine 11 is decoupled from the walking system, allowing the engine 11 to operate under the best working conditions to drive the PS motor 10 to generate electricity, providing energy for the P3 motor 2 and the power battery pack 1, and providing power for the tractor walking system in a series connection manner. For example, in working conditions such as the tractor starting with no load, running at low speed with no load, and transferring fields.

[0073] 3) Engine independent drive mode: When the power demand of the tractor reaches the best working condition range of the engine 11, and the walking speed of the tractor and the external working environment change little, and the demand torque of the tractor satisfies T e_l,cd <T req,cd ≤T e_h,cd and the demand speed satisfies n e_l,cd <n req,cd ≤n e_h,cd it switches to the engine independent drive mode. At this time, both the P3 motor 2 and the PS motor 10 do not work, and the power of the engine 11 is all transmitted to the tractor walking system by mechanical transmission. Since the power does not pass through the electric drive device, the energy loss caused by energy conversion can be avoided, and the system efficiency is the highest in this mode. For example, in working conditions such as plowing, sowing, and harvesting.

[0074] 4) Torque coupling drive mode: When the torque demand of the tractor changes greatly, and the SOC of the power battery pack 1 satisfies SOC > SOC l and the demand torque of the tractor satisfies T req,cd >T e_h,cd and the demand speed satisfies n e_l,cd <n req,cd ≤n e_h,cd it switches to the torque coupling drive mode. The PS motor 10 absorbs the excess power output by the engine 11 to convert it into electrical energy and store it in the power battery pack 1 or provide it to the P3 motor 2. The engine 11 and the P3 motor 2 provide power for the tractor walking system through torque coupling. For example, in working conditions such as getting out of trouble, plowing, harrowing, rotary tillage, and low-speed transportation with load.

[0075] 5) Power coupling drive mode: When the speed demand of the tractor changes greatly, and the SOC of the power battery pack 1 satisfies SOC > SOC l and the demand torque of the tractor satisfies T e_l,cd <T req,cd ≤T e_h,cd and the demand speed satisfies n req,cd >n e_h,cdWhen it is in this state, it switches to the power coupling drive mode. The P3 motor 2 absorbs the excess power output by the engine 11 to convert it into electrical energy and store it in the power battery pack 1 or supply it to the PS motor 10. The engine 11, the PS motor 10, and the P3 motor 2 provide power for the tractor running system through power coupling. For example, in working conditions such as intertillage, harvesting, light-load transportation, medium-load transportation, and long-distance transfer.

[0076] 6) Energy recovery mode: When the tractor brakes or decelerates, the required torque T of the tractor req,cd <0, the mechanical energy of the running system drives in the reverse direction, and the P3 motor 2 generates electricity to achieve braking / deceleration energy recovery. At this time, the engine 11 stops or decouples from the tractor running system. For example, the tractor is in working conditions such as transportation and transfer braking / deceleration.

[0077] The SOC h is the upper limit value of the high-efficiency region of the SOC of the power battery pack 1; SOC l is the lower limit value of the high-efficiency region of the SOC of the power battery pack 1; T req,cd is the required torque of the tractor equivalent to the central drive shaft 23; T e_l,cd is the lower limit of the torque in the high-efficiency working range of the engine 11 equivalent to the central drive shaft 23; T e_h,cd is the upper limit of the torque in the high-efficiency working range of the engine 11 equivalent to the central drive shaft 23; n e_l,cd is the lower limit of the rotational speed in the high-efficiency working range of the engine 11 equivalent to the central drive shaft 23; n e_h,cd is the upper limit of the rotational speed in the high-efficiency working range of the engine 11 equivalent to the central drive shaft 23.

[0078] In addition, according to actual needs, those skilled in the art can also select other possible working states.

[0079] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiment, it is not intended to limit the present invention. Any person skilled in the relevant art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

[0080] The parts not detailed in the present invention are the prior art.

Claims

1. A power-split hybrid tractor drive system, comprising a whole-machine controller (9), a power battery pack (1), a power management system (3), a distribution box (4), an engine (11), a P3 motor (2) and a PS motor (10) installed on the hybrid tractor, characterized in that: The described whole machine controller (9) is respectively connected to the engine controller (8), the mechanical transmission system controller (7), the power management system (3), the P3 motor controller (5) and the PS motor controller (6). The whole machine controller (9) is connected to the control circuit of the distribution box (4). The whole machine controller (9) is used to control the normal operation of the hybrid tractor. The engine controller (8), the P3 motor controller (5), and the PS motor controller (6) respectively control the drives of the engine (11), the P3 motor (2), and the PS motor (10). The power management system (3) controls the charge and discharge of the power battery pack (1). The mechanical transmission system controller (7) controls the operation of the tractor mechanical transmission system (12). The described mechanical transmission system (12) includes a P3 motor shaft (13), a PS motor shaft (14), a reduction device (15), an engine shaft (16), a brake (17), a power reversing device (18), a power output speed change device (19), a power output shaft (20), a power coupling device (21), an intermediate shaft (22), and a central transmission shaft (23). The front end of the P3 motor shaft (13) is connected to the P3 motor (2), and the rear end is connected to the central transmission shaft (23) through the reduction device (15). The front end of the PS motor shaft (14) is connected to the PS motor (10), and the rear end is connected to the power coupling device (21). The power coupling device (21) is coupled to the intermediate shaft (22), and the power coupling device is connected to the central transmission shaft (23). The engine shaft (16) is connected to the engine (11). The engine shaft (16) is coupled to the power reversing device (18), and the power reversing device (18) is coupled to the power coupling device (21). The engine shaft (16) is connected to the power output speed change device (19), and the power output speed change device (19) is coupled to the power output shaft (20). The brake (17) is connected to the PS motor shaft (14), and the connection or separation between the PS motor shaft (14) and the frame is achieved by controlling the brake (17). The power output shaft (20) is connected to agricultural implements. The central transmission shaft (23) is connected to the central transmission of the tractor.

2. The power split type hybrid tractor drive system according to claim 1, characterized in that: The described reduction device (15) includes a reduction sun gear (1501), a reduction planet gear (1502), a reduction ring gear (1503), and a reduction planet carrier (1504). The reduction planet gear (1502) is installed on the reduction planet carrier (1504), and the reduction planet gear (1502) meshes with the reduction ring gear (1503) and the reduction sun gear (1501) respectively. The rear end of the P3 motor shaft (13) is connected to the reduction sun gear (1501).

3. A power split hybrid tractor drive system according to claim 1, characterized in that: The described power coupling device (21) includes a coupling sun gear (2101), a coupling planet carrier (2102), coupling planet gears (2103), a coupling ring gear (2104), a coupled first-gear driving gear (2105), a coupled second-gear driving gear (2106), a coupled third-gear driving gear (2107), a coupled first-gear clutch (2108), a coupled third-gear clutch (2109), a coupled second-gear clutch (2110), a coupled third-gear driven gear (2111), a coupled second-gear driven gear (2112), and a coupled first-gear driven gear (2113); the coupling planet gears (2103) are mounted on the coupling planet carrier (2102), and the coupling planet gears (2103) mesh with the coupling ring gear (2104) and the coupling device sun gear (2101); the coupled first-gear driving gear (2105) meshes with the coupled first-gear driven gear (2113), and connection or disconnection between the coupled first-gear driving gear (2105) and the intermediate shaft (22) is achieved by controlling the coupled first-gear clutch (2108); the coupled second-gear driving gear (2106) meshes with the coupled second-gear driven gear (2112), and connection or disconnection between the coupled second-gear driving gear (2106) and the intermediate shaft (22) is achieved by controlling the coupled second-gear clutch (2110); the coupled third-gear driving gear (2107) meshes with the coupled third-gear driven gear (2111), and connection or disconnection between the coupled third-gear driving gear (2107) and the intermediate shaft (22) is achieved by controlling the coupled third-gear clutch (2109); the intermediate shaft (22) is connected to the coupling ring gear (2104) of the power coupling device (21); the coupled third-gear driven gear (2111), the coupled second-gear driven gear (2112), and the coupled first-gear driven gear (2113) are connected to the central transmission shaft (23); the power coupling device (21) can increase or decrease the gear positions according to the power demand of the tractor; The described power shift device (18) includes a mode switching clutch (1801), a forward gear driven gear (1802), a forward gear clutch (1803), a forward gear driving gear (1804), a reverse gear driving gear (1805), a reverse gear clutch (1806), a reverse gear transmission gear (1807), a mode switching shaft (1808), and a reverse gear driven gear (1809); the mode switching clutch (1801) is connected to the mode switching shaft (1808), and by controlling the mode switching clutch (1801), the connection or disconnection between the mode switching shaft (1808) and the PS motor shaft (14) is achieved; the mode switching shaft (1808) is connected to the forward gear driven gear (1802), the reverse gear driven gear (1809), and the coupling planet carrier (2102); the forward gear driving gear (1804) meshes with the forward gear driven gear (1802), and by controlling the forward gear clutch (1803), the connection or disconnection between the forward gear driving gear (1804) and the engine shaft (16) is achieved; the reverse gear driving gear (1805) meshes with the reverse gear transmission gear (1807), and by controlling the reverse gear clutch (1806), the connection or disconnection between the reverse gear driving gear (1805) and the engine shaft (16) is achieved; the reverse gear driven gear (1809) meshes with the reverse gear transmission gear (1807). The rear end of the PS motor shaft (14) is connected to the coupling sun gear (2101) of the power coupling device (21).

4. A power split hybrid tractor drive system according to claim 1, characterized in that: The described engine (11) includes a diesel engine, a natural gas engine, and a hydrogen fuel engine.

5. A power split hybrid tractor drive system according to claim 1, characterized in that: The described power shift device (18) includes a mode switching clutch (1801), a forward gear driven gear (1802), a forward gear clutch (1803), a forward gear driving gear (1804), a reverse gear driving gear (1805), a reverse gear clutch (1806), a reverse gear transmission gear (1807), a mode switching shaft (1808), and a reverse gear driven gear (1809); the mode switching clutch (1801) is connected to the mode switching shaft (1808), and by controlling the mode switching clutch (1801), the connection or disconnection between the mode switching shaft (1808) and the PS motor shaft (14) is achieved; the mode switching shaft (1808) is connected to the forward gear driven gear (1802), the reverse gear driven gear (1809), and the coupling device planet carrier (2102); the forward gear driving gear (1804) meshes with the forward gear driven gear (1802), and by controlling the forward gear clutch (1803), the connection or disconnection between the forward gear driving gear (1804) and the engine shaft (16) is achieved; the reverse gear driving gear (1805) meshes with the reverse gear transmission gear (1807), and by controlling the reverse gear clutch (1806), the connection or disconnection between the reverse gear driving gear (1805) and the engine shaft (16) is achieved; the reverse gear driven gear (1809) meshes with the reverse gear transmission gear (1807).

6. A power split hybrid tractor drive system according to claim 1, characterized in that: The described power output speed change device (19) includes a power output second gear clutch (1901), a power output second gear driven gear (1902), a power output first gear driven gear (1903), a power output first gear clutch (1904), a power output first gear driving gear (1905), and a power output second gear driving gear (1906); the power output first gear driving gear (1905) and the power output second gear driving gear (1906) are connected to the engine shaft (16); the power output first gear driving gear (1905) meshes with the power output first gear driven gear (1903), and by controlling the power output first gear clutch (1904), the connection or disconnection between the power output first gear driven gear (1903) and the power output shaft (20) is achieved; the power output second gear driving gear (1906) meshes with the power output second gear driven gear (1902), and by controlling the power output second gear clutch (1901), the connection or disconnection between the power output second gear driven gear (1902) and the power output shaft (20) is achieved; the power output speed change device (19) can increase or decrease the gear according to the requirements of the tractor agricultural implements.

7. A power split hybrid tractor drive system according to claim 1, characterized in that: The described power management system (3), distribution box (4), P3 motor controller (5), PS motor controller (6), mechanical transmission system controller (7), engine controller (8), and whole vehicle controller (9) form the control system of the hybrid tractor drive system; The whole vehicle controller (9) obtains the information of the power management system (3), distribution box (4), P3 motor controller (5), PS motor controller (6), mechanical transmission system controller (7), and engine controller (8) through the high-speed CAN bus; sends control signals to the power management system (3), distribution box (4), P3 motor controller (5), PS motor controller (6), mechanical transmission system controller (7), and engine controller (8) through the high-speed CAN bus; the whole vehicle controller (9) obtains the hybrid tractor instrument and lighting information through the low-speed CAN bus; The power management system (3) controls the power battery pack (1), and the power battery pack (1) supplies power to the P3 motor (2), PS motor (10), and low-voltage storage battery through the distribution box (5); The operating information of the hybrid tractor includes key signal, mode signal, position signal, torque signal, and speed signal.

8. The control method of a power split hybrid tractor drive system according to any one of claims 1-7, characterized in that: Specifically as follows: preset the SOC h is the upper limit value of the high-efficiency region of the SOC of the power battery pack (1); SOC l is the lower limit value of the high-efficiency region of the SOC of the power battery pack (1); T req,cd is the required torque of the tractor equivalent to the central drive shaft (23); T e_l,cd is the lower limit of the torque in the high-efficiency working range of the engine (11) equivalent to the central drive shaft (23); T e_h,cd is the upper limit of the torque in the high-efficiency working range of the engine (11) equivalent to the central drive shaft (23); n e_l,cd is the lower limit of the rotational speed in the high-efficiency working range of the engine (11) equivalent to the central drive shaft (23); n e_h,cd is the upper limit of the rotational speed in the high-efficiency working range of the engine (11) equivalent to the central drive shaft (23); After the power split hybrid tractor control system is started, the whole vehicle enters the control system self-check. After the control system self-check passes, the whole vehicle controller (9) obtains the key signal, mode signal, position signal, torque signal, and speed signal. The whole vehicle controller (9) decides to select the drive system start mode according to the obtained information, and at the same time sends control signals to the power management system (3), distribution box (4), P3 motor controller (5), PS motor controller (6), mechanical transmission system controller, (7), and engine controller (8), so that the power split hybrid tractor selects to operate in different drive modes; The drive modes of the power-split hybrid tractor include: A. Pure electric drive mode: When the power demand of the tractor cannot achieve the engine (11) operating in the high-efficiency region, and the SOC of the power battery pack (1) satisfies SOC > SOC l , the tractor demand torque satisfies T req,cd ≤T e_l,cd , the demand speed satisfies n req,cd ≤n e_h,cd , switch to the pure electric drive mode; at this time, turn off the engine (11), and the power battery pack (1) provides energy to the P3 motor (2) and the PS motor (10) in the optimal economic control mode according to the demand power to drive the vehicle to move forward. The P3 motor (2) and the PS motor (10) independently drive the vehicle respectively, or the P3 motor (2) and the PS motor (10) drive the vehicle through torque coupling; B. Series electric drive mode: When the power demand of the tractor cannot enable the engine (11) to operate in the high-efficiency area and the state of charge (SOC) of the power battery pack (1) is ≤ SOC l , the required torque of the tractor satisfies T req,cd ≤ T e_l,cd , and the required speed satisfies n req,cd ≤ n e_h,cd , switch to the series drive mode; at this time, the PS motor (10) drives the engine (11) to start, and then drives the PS motor (10) to generate electricity. The power battery pack (1) and the P3 motor (2) simultaneously or the PS motor (10) alone provide energy for the drive of the P3 motor (2); when the SOC of the power battery pack (1) reaches SOC l , carry out charging protection. The engine (11) drives the PS motor (10) to generate electricity, and the PS motor (10) provides energy for both the P3 motor (2) and the power battery pack (1) simultaneously. When it reaches SOC h , carry out trickle charging protection; in this mode, the engine (11) is decoupled from the tractor running system, enabling the engine (11) to operate under the best working conditions to drive the PS motor (10) to generate electricity, providing energy for the P3 motor (2) and the power battery pack (1), and providing power for the running system in series; C. Engine independent drive mode: When the power demand of the tractor reaches the optimal operating range of the engine (11), and the traveling speed of the tractor and the external working environment change little, and the required torque of the tractor satisfies T e_l,cd <T req,cd ≤T e_h,cd , and the required speed satisfies n e_l,cd <n req,cd ≤n e_h,cd When this occurs, switch to the engine independent drive mode; at this time, both the P3 motor (2) and the PS motor (10) do not work, and the power of the engine (11) is all transmitted to the tractor traveling system in a mechanical transmission manner. Since the power does not pass through the electric drive device, the energy loss caused by energy conversion can be avoided, and the system efficiency is the highest in this mode; D. Torque coupling drive mode: When the torque demand of the tractor changes significantly and the SOC of the power battery pack (1) satisfies SOC > SOC l , the required torque of the tractor satisfies T req,cd > T e_h,cd , the required speed satisfies n e_l,cd < n req,cd ≤ n e_h,cd When this condition is met, it switches to the torque coupling drive mode. The PS motor (10) absorbs the excess power output by the engine (11) to convert it into electrical energy and store it in the power battery pack (1) or supply it to the P3 motor (2). The engine (11) and the P3 motor (2) provide power to the tractor's traveling system through torque coupling; E. Power coupling drive mode: When the change in the rotational speed demand of the tractor is large and the SOC of the power battery pack (1) satisfies SOC > SOC l , the required torque of the tractor satisfies T e_l,cd < T req,cd ≤ T e_h,cd , the required rotational speed satisfies n req,cd > n e_h,cd , switch to the power coupling drive mode. The P3 motor (2) absorbs the excess power output by the engine (11) to convert it into electrical energy and store it in the power battery pack (1) or supply it to the PS motor (10). The engine (11), the PS motor (10), and the P3 motor (2) provide power to the tractor running system through power coupling; F. Energy recovery mode: When the tractor brakes or decelerates, the required torque T of the tractor req,cd <0, the mechanical energy of the running gear is dragged in reverse, and the P3 motor (2) generates electricity to achieve braking / deceleration energy recovery. At this time, the engine (11) stops or is decoupled from the tractor running gear.

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