A double-row planetary gear electric tractor coupling device and control method thereof

Abstract

The invention relates to a double-row planetary gear electric tractor coupling device and a control method thereof, comprising a driving motor mainly transmitting power to a driving bridge, a PTO motor mainly used for driving a rotary tillage mechanism and a double-row planetary gear coupling transmission. The first planetary gear coupling mechanism, the second planetary gear coupling mechanism and the electromagnetic lock are provided to realize the control of the convergence and diversion of the power of the two motors, and the transmission is provided to realize the change of the transmission ratio, the switching of the transmission direction and the interruption of the power transmission. The double-row planetary gear coupling transmission can not only effectively solve the limitation of the large volume of the high-power drive system, but also increase the application range of the electric tractor, and improve the power and economy of the electric tractor.

Description

Technical Field

[0001] The invention relates to the field of electric tractors, and in particular to a double-row planetary gear electric tractor coupling device and a control method thereof. Background Art

[0002] At present, most tractors on the market still use diesel engines as their power source. This traditional diesel tractor is not only noisy, inefficient, but also seriously pollutes the environment. Electric tractors use electricity to drive vehicles. Compared with traditional diesel tractors, electric tractors have the advantages of low emissions, clean and pollution-free, low noise, and high energy utilization. In addition, the motor has the advantage of flexible control, which further simplifies the transmission structure of the tractor. Therefore, electric tractors have become a new trend in the development of tractors.

[0003] In the research of electric tractors, single motor drive is mostly used, which is difficult to meet the complex working conditions of tractors. In hybrid tractors, the electric motor is used as auxiliary power, and the diesel engine is mainly used as the main power. This method does not give full play to the characteristics of high energy utilization and flexible control of the electric motor. Although tractors driven by dual motors have been disclosed in the prior art, there are generally problems such as the large size of the dual motor power coupling mechanism, the single operation mode, insufficient power, and low energy utilization. Summary of the invention

[0004] The purpose of the present invention is to provide a double-row planetary gear electric tractor coupling device and a control method thereof, which can realize the power convergence and diversion between the drive motor and the PTO motor, and improve the power and economy of the electric tractor by flexibly controlling the dual motors to adapt to the complex working conditions of the tractor, and significantly reduce the volume of the dual motor coupling mechanism.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a double-row planetary gear electric tractor coupling device, comprising a BMS controller, a power battery pack and a distribution box installed on the electric tractor and connected in sequence, the distribution box is respectively connected to the whole machine controller, the drive motor controller, the PTO motor controller, and the locking controller circuit, the whole machine controller is used to control the operation of the electric double-row planetary gear electric tractor, the drive motor controller and the PTO motor controller respectively control the rotation of the drive motor and the PTO motor; the locking controller controls the operation of the double-row planetary gear coupling transmission;

[0006] The double-row planetary gear coupling transmission comprises a first planetary gear coupling mechanism and a second planetary gear coupling mechanism arranged side by side, and a first gear ring of the first planetary gear coupling mechanism and a second gear ring adjacent to the first planetary gear coupling mechanism are externally meshed for transmission;

[0007] The first input shaft of the first planetary gear coupling mechanism is connected to the drive motor, the first ring gear of the first planetary gear coupling mechanism is connected to the first electromagnetic locker, the first output shaft of the first planetary gear coupling mechanism is provided with a second electromagnetic locker for locking or unlocking the first planet carrier in the first planetary gear coupling mechanism to drive the first output shaft, the first output shaft is connected to the transmission, and the transmission is connected to the drive axle of the electric tractor through the third output shaft;

[0008] The second input shaft of the second planetary gear coupling mechanism is connected to the PTO motor, and a third electromagnetic locker is provided at the second output shaft for locking or unlocking the transmission of the second sun gear to the second output shaft in the second planetary gear coupling mechanism, and the second output shaft is connected to the rotary tillage mechanism.

[0009] Furthermore, the first planetary gear coupling mechanism includes a first sun gear connected to the first input shaft, a first ring gear having external teeth and internal teeth, a first electromagnetic lock for locking or unlocking the first ring gear, a first planetary gear, and a first planet carrier connected to the first output shaft, the first planetary gear is externally meshed with the first sun gear, the first planetary gear is internally meshed with the first ring gear and is positioned and supported by the first planet carrier.

[0010] Furthermore, the second planetary gear coupling mechanism includes a second planetary carrier connected to the second input shaft, a second planetary gear, a second ring gear provided with external teeth and internal teeth, and a second sun gear connected to the second output shaft. The second planetary gear is externally meshed with the second sun gear, and the second planetary gear is internally meshed with the second ring gear and is positioned and supported by the second planetary carrier.

[0011] Furthermore, the whole machine controller obtains BMS controller information, drive motor controller information, locking controller information, distribution box information and PTO motor controller information through the high-speed CAN bus; sends control signals to the BMS controller, drive motor controller, locking controller, distribution box and PTO motor controller through the high-speed CAN bus; the whole machine controller obtains electric tractor operation information through the low-speed CAN bus.

[0012] Furthermore, the BMS controller controls the power battery pack, which supplies power to the drive motor, the PTO motor and the first electromagnetic lock, the second electromagnetic lock and the third electromagnetic lock; the locking controller controls the locking or unlocking of the first electromagnetic lock, the second electromagnetic lock and the third electromagnetic lock.

[0013] Furthermore, the BMS controller, drive motor controller, locking controller, distribution box, PTO motor controller and whole machine controller constitute a control system of a double-row planetary gear electric tractor coupling device, which is provided with a walking-only mode, an operating-only mode, a walking-operation separation mode and an energy recovery mode.

[0014] Furthermore, the operating information of the electric tractor includes key signal, transmission gear signal, pedal position signal, operation mode signal, motor and rotating shaft speed signal.

[0015] Furthermore, the transmission is an intermediate shaft type transmission.

[0016] A control method for a double-row planetary gear electric tractor coupling device includes the following steps: After the electric tractor starts, the whole vehicle enters system self-check. After the system self-check passes, the whole vehicle controller obtains the key signal, transmission gear position signal, pedal position signal, operation mode signal, first electromagnetic lock position signal, second electromagnetic lock position signal, third electromagnetic lock position signal, and motor rotating shaft speed signal. The whole vehicle controller sends control signals to the BMS controller, drive motor controller, lock controller, PTO motor controller, and distribution box according to the obtained information, so that the electric tractor selects different control modes:

[0017] 1) Only driving mode: When the whole vehicle controller receives the only driving mode, the whole vehicle controller calculates the real-time required power Px. When the rated power Pq of the drive motor is greater than or equal to Px, the lock controller controls the first electromagnetic lock to engage. At this time, the drive motor is in the working state. The whole vehicle controller calculates the target speed nq of the drive motor, and then sends the signal to the drive motor controller. The drive motor adjusts the speed in real time according to the signal of the drive motor controller;

[0018] When Pq < Px, the lock controller controls the third electromagnetic lock to engage. At this time, both the drive motor and the PTO motor are in the working state. The whole vehicle controller calculates the target speed nq of the drive motor and the target speed np of the PTO motor based on the maximum working efficiency distribution control strategy, and then sends the signal to the drive motor controller and the PTO motor controller. The drive motor adjusts the speed in real time according to the signal of the drive motor controller, and the PTO motor adjusts the speed in real time according to the signal of the PTO motor controller;

[0019] 2) Only operation mode: When the whole vehicle controller receives the only operation mode, the lock controller controls the first electromagnetic lock to engage. At this time, the PTO motor is in the working state. The whole vehicle controller calculates the target speed np of the PTO motor, and then sends the signal to the PTO motor controller. The PTO motor operates at a constant speed according to the signal of the PTO motor controller. The sensor collects the actual speed of the PTO motor in real time. The whole vehicle controller compares the actual speed of the PTO motor with the target speed of the PTO motor and sends the signal to the PTO motor controller in real time, and controls the speed of the PTO motor through the PTO motor controller to keep the PTO motor operating at a constant speed;

[0020] 3) Walking operation mode: When the whole machine controller receives the walking operation mode, the locking controller controls the first electromagnetic lock to engage. At this time, the drive motor and the PTO motor are both in working state. The whole machine controller calculates the target speed nq of the drive motor and the target speed np of the PTO motor, and then transmits the signal to the drive motor controller and the PTO motor controller. The drive motor adjusts the speed in real time according to the signal of the drive motor controller, and the PTO motor works at a constant speed according to the signal of the PTO motor controller. The sensor collects the actual speed of the PTO motor in real time. The whole machine controller compares the actual speed of the PTO motor with the target speed of the PTO motor and transmits the signal to the PTO motor controller in real time. The speed of the PTO motor is controlled by the PTO motor controller to keep the PTO motor working at a constant speed.

[0021] 4) Energy recovery mode: When the whole machine controller recognizes that the tractor is stationary and the PTO is not working or braking, the lock controller controls the second electromagnetic lock and the third electromagnetic lock to combine. At this time, the drive motor is in working state, and the PTO motor works as a generator. The whole machine controller calculates the speed nq of the drive motor in the lowest energy consumption state, and then transmits the signal to the drive motor. The drive motor adjusts the speed in real time according to the signal of the drive motor controller, and the PTO motor acts as an electric motor to transmit electrical energy to the power battery pack.

[0022] The beneficial effects brought by the present invention are:

[0023] 1. The double-row planetary gear coupling transmission of the present invention has a more compact structure and a greater load-bearing capacity because the ring gear on the first planetary gear coupling mechanism and the ring gear arranged on the second planetary gear coupling mechanism are externally meshed for transmission; compared with the dual-motor coupling mechanism of an electric tractor of the same level, the volume of the double-row planetary gear coupling transmission of the present invention is reduced by 20%, on this basis, the capacity of the power battery can be increased, and the cruising range of the electric tractor can be increased.

[0024] 2. Using dual motors as the power source of the electric tractor, the drive motor transmits power to the variable speed drive axle alone, and the PTO motor drives power to the rotary tillage mechanism alone. This can simplify the gearbox structure, facilitate the layout of the entire vehicle, and select the appropriate working mode according to different operating requirements, thereby improving the motor's working efficiency and energy utilization.

[0025] 3. By controlling the lock, the four operating modes of "walking only mode, working only mode, walking and working separation mode, and energy recovery mode" can be flexibly switched to meet the multi-scenario operation needs of electric tractors and improve the power, economy and adaptability of the vehicle.

[0026] 4. When the electric tractor is temporarily parked or braking, the system enters the energy recovery mode to improve the energy utilization of the whole machine.

[0027] 5. By controlling the hydraulic pump to change the transmission ratio of the continuously variable transmission mechanism, the dual power coupling mechanism can distribute the power of the drive motor and the PTO motor to the drive axle and the rotary tillage mechanism based on the maximum work efficiency distribution control strategy.

[0028] 6. The power source used in the present invention is an electric motor, and the power battery pack provides electrical energy to achieve zero pollution emissions, effectively solving the harm of traditional tractor emissions to crops and the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of a double-row planetary gear electric tractor coupling device;

[0030] Figure 2 It is a structural schematic diagram of a double-row planetary gear coupling transmission;

[0031] Figure 3 is a structural schematic diagram of the first planetary gear coupling mechanism;

[0032] Figure 4 is a structural schematic diagram of the second planetary gear coupling mechanism;

[0033] Figure 5 It is the circuit connection diagram of the power coupling control system of the electric tractor;

[0034] Figure 6 It is a flow chart of a control method of a double-row planetary gear electric tractor coupling device.

[0035] The following are the descriptions of the figures:

[0036] 1. BMS controller, 2. power battery pack, 3. drive motor controller, 4. drive motor, 5. double-row planetary gear coupling transmission, 6. drive axle, 7. rotary tillage mechanism, 8. locking controller, 9. PTO motor, 10. distribution box, 11. PTO motor controller, 12. whole machine controller, 13. first input shaft, 14. first planetary gear coupling mechanism, 1401. first sun gear, 1402. first ring gear, 1403. first planetary gear, 1404. first planetary carrier, 15. first electromagnetic lock, 16. first output shaft, 17. second electromagnetic lock, 18 transmission, 19. third output shaft, 20. second output shaft, 21. third electromagnetic lock, 22. second planetary gear coupling mechanism, 2201. second planetary carrier, 2202. second planetary gear, 2203. second ring gear, 2204. second sun gear, 23. second input shaft. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with 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 names of the devices and do not have specific meanings.

[0038] Reference Figure 1 A double-row planetary gear electric tractor coupling device includes a BMS controller 1, a power battery pack 2, a drive motor controller 3, a drive motor 4, a double-row planetary gear coupling transmission 5, a drive axle 6, a rotary tillage mechanism 7, a locking controller 8, a PTO motor 9, a distribution box 10, a PTO motor controller 11 and a whole machine controller 12.

[0039] The BMS controller 1, the power battery pack 2 and the distribution box 10 are circuit-connected. The distribution box 10 is circuit-connected with the whole machine controller 12, the drive motor controller 3, the PTO motor controller 11 and the locking controller 8 respectively. The whole machine controller 12 is used to control the operation of the electric double-row planetary gear electric tractor. The drive motor controller 3 and the PTO motor controller 11 respectively control the rotation of the drive motor 4 and the PTO motor 9; the locking controller 8 controls the operation of the double-row planetary gear coupling transmission 5.

[0040] Reference Figure 2 The double-row planetary gear coupling transmission 5 includes a first planetary gear coupling mechanism 14 and a second planetary gear coupling mechanism 22 arranged side by side. The first input shaft 13 of the first planetary gear coupling mechanism 14 is connected to the drive motor 4, the first ring gear 1402 of the first planetary gear coupling mechanism 14 is connected to the first electromagnetic lock 15, the first output shaft 16 of the first planetary gear coupling mechanism 14 is provided with a second electromagnetic lock 17 for locking or unlocking the first planet carrier 1404 in the first planetary gear coupling mechanism 14 to drive the first output shaft 16, the first output shaft 16 is connected to the transmission 18, and the transmission 18 is connected to the drive axle 6 of the electric tractor through the third output shaft 19. The transmission 18 is an intermediate shaft transmission, which realizes changing the transmission ratio, switching the transmission direction and interrupting the power transmission.

[0041] The second input shaft 23 of the second planetary gear coupling mechanism 22 is connected to the PTO motor 9, and the second output shaft 20 is provided with a third electromagnetic locker 21 for locking or unlocking the second sun gear 2204 in the second planetary gear coupling mechanism 22 to drive the second output shaft 20, and the second output shaft 20 is connected to the rotary tillage mechanism 7.

[0042] Reference Figure 3The first planetary gear coupling mechanism 14 includes a first sun gear 1401 connected to the first input shaft 13, a first ring gear 1402 with external teeth and internal teeth, a first electromagnetic locker 15 for locking or unlocking the first ring gear 1402, a first planetary gear 1403, and a first planet carrier 1404 connected to the first output shaft 16. The first planetary gear 1403 is externally meshed with the first sun gear 1401, internally meshed with the first ring gear 1402 and positioned and supported by the first planet carrier 1404. The first ring gear 1402 is externally meshed with the second ring gear 2203 arranged on the second planetary gear coupling mechanism 22 for transmission.

[0043] Reference Figure 4 The second planetary gear coupling mechanism 22 includes a second planetary carrier 2201 connected to the second input shaft 23, a second sun gear 2202, a second ring gear 2203 with external teeth and internal teeth, and a second sun gear 2204 connected to the second output shaft 20. The second planetary gear 2202 is externally meshed with the second sun gear 2204, internally meshed with the second ring gear 2203 and positioned and supported by the second planetary carrier 2201. The second ring gear 2203 is externally meshed with the first ring gear 1402 arranged on the first planetary gear coupling mechanism 14 for transmission.

[0044] Reference Figure 5 , the BMS controller 1, the drive motor controller 3, the locking controller 8, the distribution box 10, the PTO motor controller 11 and the whole machine controller 12 constitute the control system of the double-row planetary gear electric tractor coupling device. The system is provided with five operation modes: walking mode only, operation mode only, walking operation separation mode and energy recovery mode. The whole machine controller 12 obtains the information of the BMS controller 1, the drive motor controller 3, the locking controller 8, the distribution box 10 and the PTO motor controller 11 through the high-speed CAN bus; sends control signals to the BMS controller, the drive motor controller 3, the locking controller 8, the distribution box 10 and the PTO motor controller 11 through the high-speed CAN bus; obtains the operation information of the electric tractor through the low-speed CAN bus, so that the driver can understand the whole vehicle information in real time. The operation information of the electric tractor includes key signal, gearbox gear signal, pedal position signal, operation mode signal, motor and rotating shaft speed signal.

[0045] The power battery pack 2 is used to supply power to the drive motor 4, the PTO motor 9, and each electromagnetic lock. The whole-machine controller 12 is used to control the double-row planetary gear electric tractor. The whole-machine controller 12 transmits control signals to the BMS controller 1 through the high-speed CAN bus to control the power battery pack 2; transmits to the lock controller to control the first electromagnetic lock 15, the second electromagnetic lock 17, and the third electromagnetic lock 21 to lock or unlock; transmits to the drive motor controller 3 and the PTO motor controller 11 respectively to control the rotation of the drive motor 4 and the PTO motor 9.

[0046] Refer to Figure 6 , after the electric tractor starts, the whole vehicle enters the system self-check. After the system self-check passes, the whole-machine controller 12 obtains the key signal, the transmission 18 gear signal, the pedal position signal, the operation mode signal, the first electromagnetic lock 15, the second electromagnetic lock 17, and the third electromagnetic lock 21 position signals, and the motor and the rotating shaft speed signals. The whole-machine controller 12 sends control signals to the BMS controller 1, the drive motor controller 3, the lock controller 8, the PTO motor controller 11, and the distribution box 10 according to the obtained information, so that the electric tractor selects different control modes:

[0047] 1) Only walking mode: When the whole-machine controller 12 receives the only walking mode, the whole-machine controller 12 calculates the real-time required power Px. When the rated power Pq of the drive motor is greater than or equal to Px, the lock controller 8 controls the first electromagnetic lock 15 to engage. At this time, the drive motor 4 is in the working state. The whole-machine controller 12 calculates the target speed nq of the drive motor 4, and then transmits the signal to the drive motor controller 3. The drive motor 4 adjusts the speed in real time according to the signal of the drive motor controller 3;

[0048] When the rated power Pq of the drive motor is less than Px, the lock controller 8 controls the third electromagnetic lock 21 to engage. At this time, both the drive motor 4 and the PTO motor 9 are in the working state. The whole-machine controller 12 calculates the target speed nq of the drive motor 4 and the target speed np of the PTO motor 9 based on the maximum working efficiency distribution control strategy, and then transmits the signal to the drive motor controller 3 and the PTO motor controller 11. The drive motor 4 adjusts the speed in real time according to the signal of the drive motor controller 3, and the PTO motor 9 adjusts the speed in real time according to the signal of the PTO motor controller 11;

[0049] 2) Operation-only mode: When the whole machine controller 12 receives the operation-only mode, the locking controller 8 controls the first electromagnetic lock 15 to engage. At this time, the PTO motor 9 is in working state. The whole machine controller 12 calculates the target speed np of the PTO motor 9, and then transmits the signal to the PTO motor controller 11. The PTO motor 9 operates at a constant speed according to the signal of the PTO motor controller 11. The sensor collects the actual speed of the PTO motor 9 in real time. The whole machine controller 12 compares the actual speed of the PTO motor 9 with the target speed of the PTO motor 9 and transmits the signal to the PTO motor controller 11 in real time. The speed of the PTO motor 9 is controlled by the PTO motor controller 11 to keep the PTO motor 9 working at a constant speed;

[0050] 3) Walking operation mode: When the whole machine controller 12 receives the walking operation mode, the locking controller 8 controls the first electromagnetic lock 15 to engage. At this time, the drive motor 4 and the PTO motor 9 are both in working state. The whole machine controller 12 calculates the target speed nq of the drive motor 4 and the target speed np of the PTO motor 9, and then transmits the signal to the drive motor controller 3 and the PTO motor controller 11. The drive motor 4 adjusts the speed in real time according to the signal of the drive motor controller 3, and the PTO motor 9 operates at a constant speed according to the signal of the PTO motor controller 11. The sensor collects the actual speed of the PTO motor 9 in real time. The whole machine controller 12 compares the actual speed of the PTO motor 9 with the target speed of the PTO motor 9 and transmits the signal to the PTO motor controller 11 in real time. The speed of the PTO motor 9 is controlled by the PTO motor controller 11 to keep the PTO motor 9 working at a constant speed.

[0051] 4) Energy recovery mode: When the whole machine controller 12 recognizes that the tractor is stationary and the PTO is not operating or braking, the locking controller 8 controls the second electromagnetic lock 17 and the third electromagnetic lock 21 to engage. At this time, the drive motor 4 is in working state, and the PTO motor 9 works as a generator. The whole machine controller 12 calculates the speed nq of the drive motor 4 in the lowest energy consumption state, and then transmits the signal to the drive motor 4. The drive motor 4 adjusts the speed in real time according to the signal of the drive motor controller 3, and the PTO motor 9 acts as an electric motor to transmit electrical energy to the power battery pack 2.

[0052] In addition, according to actual needs, those skilled in the art can also select other possible working states.

[0053] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A control method for a double-row planetary gear electric tractor coupling device, characterized in that: The coupling device comprises a BMS controller (1), a power battery pack (2) and a distribution box (10) which are installed on the electric tractor and are connected in sequence in a circuit. The distribution box (10) is respectively connected in a circuit to a whole machine controller (12), a drive motor controller (3), a PTO motor controller (11) and a locking controller (8). The whole machine controller (12) is used to control the operation of the electric double-row planetary gear electric tractor. The drive motor controller (3) and the PTO motor controller (11) respectively control the rotation of the drive motor (4) and the PTO motor (9). The locking controller (8) controls the operation of the double-row planetary gear coupling transmission (5). The double-row planetary gear coupling transmission (5) comprises a first planetary gear coupling mechanism (14) and a second planetary gear coupling mechanism (22) arranged side by side, a first ring gear (1402) of the first planetary gear coupling mechanism (14) and an adjacent second ring gear (2203) arranged on the second planetary gear coupling mechanism (22) being externally meshed for transmission; The first input shaft (13) of the first planetary gear coupling mechanism (14) is connected to a drive motor (4); the first ring gear (1402) of the first planetary gear coupling mechanism (14) is connected to a first electromagnetic locker (15); a first output shaft (16) of the first planetary gear coupling mechanism (14) is provided with a second electromagnetic locker (17) for locking or unlocking the transmission of the first output shaft (16) by the first planet carrier (1404) in the first planetary gear coupling mechanism (14); the first output shaft (16) is connected to a transmission (18); and the transmission (18) is connected to a drive axle (6) of the electric tractor via a third output shaft (19); The second input shaft (23) of the second planetary gear coupling mechanism (22) is connected to the PTO motor (9); a third electromagnetic locker (21) for locking or unlocking the transmission of the second sun gear (2204) in the second planetary gear coupling mechanism (22) to the second output shaft (20) is provided at the second output shaft (20); the second output shaft (20) is connected to the rotary tillage mechanism (7); The first planetary gear coupling mechanism (14) comprises a first sun gear (1401) connected to a first input shaft (13), a first ring gear (1402) provided with external teeth and internal teeth, a first electromagnetic locker (15) for locking or unlocking the first ring gear (1402), a first planetary gear (1403), and a first planet carrier (1404) connected to a first output shaft (16), wherein the first planetary gear (1403) is externally meshed with the first sun gear (1401), the first planetary gear (1403) is internally meshed with the first ring gear (1402), and is positioned and supported by the first planet carrier (1404); The second planetary gear coupling mechanism (22) comprises a second planet carrier (2201) connected to the second input shaft (23), a second planetary gear (2202), a second ring gear (2203) provided with external teeth and internal teeth, and a second sun gear (2204) connected to the second output shaft (20); the second planetary gear (2202) is externally meshed with the second sun gear (2204), the second planetary gear (2202) is internally meshed with the second ring gear (2203), and is positioned and supported by the second planet carrier (2201); The whole machine controller (12) obtains information from the BMS controller (1), the drive motor controller (3), the locking controller (8), the distribution box (10) and the PTO motor controller (11) via the high-speed CAN bus; sends control signals to the BMS controller (1), the drive motor controller (3), the locking controller (8), the distribution box (10) and the PTO motor controller (11) via the high-speed CAN bus; the whole machine controller (12) obtains the operation information of the electric tractor via the low-speed CAN bus; The BMS controller (1) controls the power battery pack (2), and the power battery pack (2) supplies power to the drive motor (4), the PTO motor (9), and the first electromagnetic lock (15), the second electromagnetic lock (17), and the third electromagnetic lock (21); the locking controller (8) controls the first electromagnetic lock (15), the second electromagnetic lock (17), and the third electromagnetic lock (21) to lock or unlock; The BMS controller (1), the drive motor controller (3), the locking controller (8), the distribution box (10), the PTO motor controller (11) and the whole machine controller (12) constitute a control system of a double-row planetary gear electric tractor coupling device, the system being provided with a travel-only mode, an operation-only mode, a travel-operation separation mode and an energy recovery mode; The control method comprises the following steps: after the electric tractor is started, the whole vehicle enters a system self-check, and after the system self-check passes, the whole machine controller (12) obtains a key signal, a gear position signal of a transmission (18), a pedal position signal, an operation mode signal, a first electromagnetic lock (15), a second electromagnetic lock (17) and a third electromagnetic lock (21) position signal, and a motor and a rotating shaft speed signal, and the whole machine controller (12) sends a control signal to a BMS controller (1), a drive motor controller (3), a locking controller (8), a PTO motor controller (11) and a distribution box (10) based on the obtained information, so that the electric tractor selects different control modes: 1) Only walking mode: When the whole machine controller (12) receives the only walking mode, the whole machine controller (12) calculates the real-time required power Px. When the rated power of the drive motor Pq ≥ Px, the locking controller (8) controls the first electromagnetic lock (15) to engage. At this time, the drive motor (4) is in the working state. The whole machine controller (12) calculates the target speed nq of the drive motor (4), and then transmits the signal to the drive motor controller (3). The drive motor (4) adjusts the speed in real time according to the signal of the drive motor controller (3); When Pq < Px, the locking controller (8) controls the third electromagnetic lock (21) to engage. At this time, both the drive motor (4) and the PTO motor (9) are in the working state. The whole machine controller (12) calculates the target speed nq of the drive motor (4) and the target speed np of the PTO motor (9) based on the maximum working efficiency distribution control strategy, and then transmits the signal to the drive motor controller (3) and the PTO motor controller (11). The drive motor (4) adjusts the speed in real time according to the signal of the drive motor controller (3), and the PTO motor (9) adjusts the speed in real time according to the signal of the PTO motor controller (11); 2) Only operation mode: When the whole machine controller (12) receives the only operation mode, the locking controller (8) controls the first electromagnetic lock (15) to engage. At this time, the PTO motor (9) is in the working state. The whole machine controller (12) calculates the target speed np of the PTO motor (9), and then transmits the signal to the PTO motor controller (11). The PTO motor (9) operates at a constant speed according to the signal of the PTO motor controller (11). The sensor collects the actual speed of the PTO motor (9) in real time. The whole machine controller (12) transmits the signal to the PTO motor controller (11) in real time by comparing the actual speed of the PTO motor (9) with the target speed of the PTO motor (9), and controls the speed of the PTO motor (9) through the PTO motor controller (11) to keep the PTO motor (9) operating at a constant speed; 3) Walking and operation mode: When the whole machine controller (12) receives the walking and operation mode, the locking controller (8) controls the first electromagnetic lock (15) to engage. At this time, both the drive motor (4) and the PTO motor (9) are in the working state. The whole machine controller (12) calculates the target speed nq of the drive motor (4) and the target speed np of the PTO motor (9), and then transmits the signal to the drive motor controller (3) and the PTO motor controller (11). The drive motor (4) adjusts the speed in real time according to the signal of the drive motor controller (3), and the PTO motor (9) operates at a constant speed according to the signal of the PTO motor controller (11). The sensor collects the actual speed of the PTO motor (9) in real time. The whole machine controller (12) transmits the signal to the PTO motor controller (11) in real time by comparing the actual speed of the PTO motor (9) with the target speed of the PTO motor (9), and controls the speed of the PTO motor (9) through the PTO motor controller (11) to keep the PTO motor (9) operating at a constant speed; 4) Energy recovery mode: When the whole machine controller (12) recognizes that the tractor is stationary and the PTO is not operating or is braking, the locking controller (8) controls the second electromagnetic lock (17) and the third electromagnetic lock (21) to engage. At this time, the drive motor (4) is in a working state, and the PTO motor (9) works as a generator. The whole machine controller (12) calculates the speed nq of the drive motor (4) in the lowest energy consumption state, and then transmits the signal to the drive motor (4). The drive motor (4) adjusts the speed in real time according to the signal of the drive motor controller (3), and the PTO motor (9) acts as an electric motor to transmit electric energy to the power battery pack (2).

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