A dual-motor transmission device for electric tractors and its control strategy

Abstract

A dual-motor transmission device for an electric tractor and a control strategy thereof relate to the technical field of electric tractors. The invention transmits power to a PTO output shaft (9-3) and an output shaft gear A (7-1) respectively through a dual planetary gear coupling mechanism (6); by manipulating the locking and releasing of a PTO output shaft brake (9-2), a ring gear brake (6-4) and an output shaft brake (7-3), a front planetary gear mechanism and a rear planetary gear mechanism can achieve the convergence and divergence of power and torque of a PTO drive motor (4) and a power drive motor (5) through a dual planetary gear common ring gear (6-3); a high-low speed switching mechanism (8) achieves high-low speed switching by changing a gear transmission ratio to compensate for the insufficiency of motor speed regulation, and a neutral position is set at the same time; the motor utilization rate is improved through the convergence and divergence control of the motor, and the adaptability of the tractor is increased.

Description

Technical Field

[0001] The invention relates to the technical field of electric tractors, and in particular to a dual-motor transmission device for an electric tractor and a control strategy thereof. Background Art

[0002] It is known that the continuous exploitation of fossil energy will eventually be exhausted; and diesel engines have certain pollution to the atmosphere. As people's requirements for environmental quality become higher and higher, the electrification of tractors has become a trend; John Deere abroad exhibited the high-horsepower tractor SESAM at the SIMA exhibition in France; Luoyang First Tractor Co., Ltd. in China displayed the smart 5G electric tractor in 2020; electric tractors have become a new hot spot in the development of tractors because of their many advantages such as cleanliness, pollution-free, energy-saving and environmental protection.

[0003] Tractors require a lot of power and low-speed traction to work, and they also need a power output device (PTO) to output power to farm implements, so it is difficult for a single motor to provide enough power and torque. Therefore, in the field of electric tractor research, dual-motor coupling transmission has become the mainstream. However, the current dual-motor coupling transmission mechanism has many parts that are difficult to arrange, large in size and low in efficiency, and complex mode switching. Many of them simply replace the diesel engine with an electric motor based on the original tractor transmission. Therefore, it is necessary to provide a transmission solution that is more suitable for electric tractors to meet their specific needs. Summary of the invention

[0004] In order to overcome the shortcomings of the background technology, the present invention provides an electric tractor dual-motor transmission device and a control strategy thereof. The present invention can provide multiple working modes and can realize power diversion and convergence between the drive motor and the PTO motor according to power requirements. It is suitable for multiple working modes of the tractor, further improving the utilization rate of the motor and reducing energy consumption.

[0005] In order to achieve the above-mentioned purpose of the invention, the present invention adopts the following technical solution:

[0006] A dual-motor transmission device for an electric tractor comprises a power battery pack, an operation control unit, a drive control unit, a PTO drive motor, a power drive motor, a dual planetary gear coupling mechanism, a drive output shaft transmission mechanism, a high-low speed switching mechanism, a PTO output transmission structure and an energy management system, wherein the power battery pack is arranged at the front of the tractor, the power battery pack is connected to the drive control unit through a wire to provide electric energy for the drive control unit, the drive control unit is arranged at the bottom of a seat in a cab, the drive control unit is respectively connected to the operation control unit, the PTO drive motor, the power drive motor, the ring gear brake in the dual planetary gear coupling mechanism, the output shaft brake in the drive output shaft transmission mechanism, the PTO output shaft brake in the PTO output transmission structure and the energy management system through wires, the operation control unit is arranged in the cab, the torque and speed of the PTO drive motor and the power drive motor are controlled by the drive control unit, and the PT drive motor is driven by the power drive motor. The O drive motor is arranged on the frame in the middle of the tractor body, the input shaft of the PTO drive motor is connected to the front planetary row sun gear in the double planetary row coupling mechanism and transmits its power to the front planetary gear mechanism through the front planetary row sun gear, the power drive motor is arranged on the frame at the rear of the tractor, the input shaft of the power drive motor is connected to the rear planetary row sun gear in the double planetary row coupling mechanism and transmits its power to the rear planetary gear mechanism through the rear planetary row sun gear, the double planetary row coupling mechanism is arranged between the PTO drive motor and the power drive motor, the PTO output shaft gear in the PTO output transmission structure is connected to the gear on the front planetary row planet carrier in the double planetary row coupling mechanism, the output shaft gear A in the driving output shaft transmission mechanism is connected to the gear on the rear planetary row planet carrier in the double planetary row coupling mechanism, and the input shaft gear in the high and low speed switching mechanism is connected to the output shaft A in the driving output shaft transmission mechanism to form the electric tractor dual-motor transmission device.

[0007] The electric tractor dual-motor transmission device, the double planetary row coupling mechanism includes a front planetary gear mechanism, a rear planetary gear mechanism, a double planetary row common ring gear, a ring gear brake and a ring gear fixed bearing, the front planetary gear mechanism and the rear planetary gear mechanism are arranged in a housing of the gearbox at intervals, the front planetary row planetary carriers at the upper and lower ends of the front planetary gear mechanism and the rear planetary row planetary carriers at the upper and lower ends of the rear planetary gear mechanism are respectively connected to the double planetary row common ring gear located at the upper and lower ends of the housing, the two double planetary row common ring gears are respectively installed on the housing through the ring gear fixed bearings, and ring gear brakes are respectively provided on the outside of the double planetary row common ring gear, and the fixed ends of the ring gear brakes are arranged on the housing.

[0008] The electric tractor dual-motor transmission device, the front planetary gear mechanism includes a front planetary gear sun gear and a front planetary gear carrier, the front planetary gear carrier is provided with two, the two front planetary gear carriers are arranged at intervals, and the front planetary gear sun gear is arranged between the two front planetary gear carriers.

[0009] The electric tractor dual-motor transmission device, the rear planetary gear mechanism includes a rear planetary gear carrier and a rear planetary gear sun gear, the rear planetary gear carrier is provided with two, the two rear planetary gear carriers are arranged at intervals, and the rear planetary gear sun gear is arranged between the two rear planetary gear carriers.

[0010] The electric tractor dual-motor transmission device, the driving output shaft transmission mechanism includes an output shaft gear A, an output shaft A and an output shaft brake, the output shaft gear A is meshed with the gear on the rear planetary gear carrier, the output shaft gear A is sleeved on the output shaft A, an output shaft brake is provided on the output shaft A, and the fixed end of the output shaft brake is set on the housing of the gearbox.

[0011] The electric tractor dual-motor transmission device, the high-low speed switching mechanism includes an input shaft gear, an intermediate shaft input gear, an intermediate shaft output gear, an output shaft gear B, a synchronizer and an output shaft B. The output shaft B is connected to the output shaft A to form a high-low speed switching power input shaft. The input shaft gear, the synchronizer and the output shaft gear B are arranged on the high-low speed switching power input shaft from left to right in sequence. The input shaft gear and the output shaft gear B are respectively meshed with the intermediate shaft input gear and the intermediate shaft output gear.

[0012] In the electric tractor dual-motor transmission device, the intermediate shaft input gear and the intermediate shaft output gear are sleeved on the intermediate shaft at intervals, and the intermediate shaft is arranged on the gearbox housing through a bearing.

[0013] The electric tractor dual-motor transmission device, the PTO output transmission structure includes a PTO output shaft gear, a PTO output shaft brake and a PTO output shaft, the PTO output shaft gear is meshed with the gear on the front planetary gear carrier, the PTO output shaft gear is arranged on the PTO output shaft, and the PTO output shaft is provided with a PTO output shaft brake.

[0014] In the electric tractor dual-motor transmission device, the fixed end of the PTO output shaft brake is connected to the gearbox housing, and the right end of the PTO output shaft is connected to the agricultural implement requiring power input.

[0015] A control strategy for a dual-motor transmission device of an electric tractor is disclosed. The control strategy adopts a simulated annealing algorithm. First, the optimal working mode of the tractor is automatically determined by collecting the working state information of the tractor. Then, the power coupling between the PTO drive motor and the power drive motor is adjusted to make the tractor work in the optimal state. The different power couplings of the PTO drive motor and the power drive motor are calculated, the coupling results are compared, and the global optimal solution of the objective function is randomly found in the solution space in combination with the probability jump characteristics. The probability selection formula is used to select the optimal solution. Select a bad solution, expand the optimization range, and finally complete the optimization process of the solution space to find the optimal coupling power.

[0016] By adopting the above technical solution, the present invention has the following advantages:

[0017] The present invention transmits power to the PTO output shaft and the output shaft gear A respectively through the double planetary gear coupling mechanism, and through the locking and releasing of the PTO output shaft brake, the ring gear brake and the output shaft brake, the front planetary gear mechanism and the rear planetary gear mechanism can realize the convergence and diversion of the power and torque of the PTO drive motor and the power drive motor through the double planetary gear common ring gear, and the high-low speed switching mechanism realizes high-low speed switching by changing the gear transmission ratio to make up for the deficiency of the motor speed regulation, and sets the neutral position at the same time; the utilization rate of the motor is improved through the convergence and diversion control of the motor, and the adaptability of the tractor is increased. At the same time, the dual-motor system is smaller in size than the single motor, and can be symmetrically arranged to make the weight distribution of the vehicle body uniform, and then adopts multi-mode switching control and simulated annealing algorithm, and automatically judges the optimal working matching parameters of the tractor by collecting the working state information of the tractor, and makes the tractor work in the optimal state by adjusting the power coupling of the PTO drive motor and the power drive motor, etc., which is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the overall structural diagram of the dual-motor transmission in the present invention;

[0019] Figure 2 It is a PTO output transmission structure diagram in the present invention;

[0020] Figure 3 This is a diagram of a double planetary gear coupling mechanism in the present invention;

[0021] Figure 4 It is a driving output transmission structure diagram in the present invention;

[0022] Figure 5 It is a high-speed and low-speed switching structure diagram of the present invention;

[0023] Figure 6 It is a dual-motor transmission control strategy diagram in the present invention;

[0024] Figure 7 It is a flow chart of the dual motor transmission algorithm in the present invention;

[0025] In the figure: 1. Power battery pack; 2. Operation control unit; 3. Drive control unit; 4. PTO drive motor; 5. Power drive motor; 6. Double planetary gear coupling mechanism; 6-1. Front planetary gear sun gear; 6-2. Front planetary gear carrier; 6-3. Double planetary gear common ring gear; 6-4. Ring gear brake; 6-5. Ring gear fixed bearing; 6-6. Rear planetary gear carrier; 6-7. Rear planetary gear sun gear; 7. Drive output shaft transmission mechanism; 7-1. Output shaft gear A; 7-2. Output shaft A; 7-3. Output shaft brake; 8. High and low speed switching mechanism; 8-1. Input shaft gear; 8-2. Intermediate shaft input gear; 8-3. Intermediate shaft output gear; 8-4. Output shaft gear B; 8-5. Synchronizer; 8-6. Output shaft B; 9. PTO output transmission structure; 9-1. PTO output shaft gear; 9-2. PTO output shaft brake; 9-3. PTO output shaft; 10. Energy management system. DETAILED DESCRIPTION

[0026] The present invention can be explained in more detail by the following examples, but the present invention is not limited to the following examples;

[0027] In the description of the present invention, it is to be understood that the terms “center”, “lateral”, “length”, “width”, “height”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “side”, etc., indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0028] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Combined with Figures 1 to 7The present invention discloses a dual-motor transmission device for an electric tractor, comprising a power battery pack 1, an operation control unit 2, a drive control unit 3, a PTO drive motor 4, a power drive motor 5, a dual planetary gear coupling mechanism 6, a drive output shaft transmission mechanism 7, a high-low speed switching mechanism 8, a PTO output transmission structure 9 and an energy management system 10. The power battery pack 1 is arranged at the front of the tractor, and the power battery pack 1 is connected to the drive control unit 3 through a wire to provide electric energy for the drive control unit 3. The drive control unit 3 is arranged at the bottom of a seat in a cab. The drive control unit 3 is respectively connected to the operation control unit 2, the PTO drive motor 4, the power drive motor 5, the ring gear brake 6-4 in the dual planetary gear coupling mechanism 6, the output shaft brake 7-3 in the drive output shaft transmission mechanism 7, the PTO output shaft brake 9-2 in the PTO output transmission structure 9 and the energy management system 10 through wires. The operation control unit 2 is arranged in the cab, and the torque and speed of the PTO drive motor 4 and the power drive motor 5 are controlled by the drive control unit 3. The PTO drive motor 4 is arranged on the frame in the middle of the tractor body, the input shaft of the PTO drive motor 4 is connected to the front planetary row sun gear 6-1 in the double planetary row coupling mechanism 6 and transmits its power to the front planetary gear mechanism through the front planetary row sun gear 6-1, the power drive motor 5 is arranged on the frame at the rear of the tractor, the input shaft of the power drive motor 5 is connected to the rear planetary row sun gear 6-7 in the double planetary row coupling mechanism 6 and transmits its power to the rear planetary gear mechanism through the rear planetary row sun gear 6-7, the double planetary row coupling mechanism 6 is arranged between the PTO drive motor 4 and the power drive motor 5, the PTO output shaft gear 9-1 in the PTO output transmission structure 9 is connected to the gear on the front planetary row planet carrier 6-2 in the double planetary row coupling mechanism 6, the output shaft gear A7-1 in the drive output shaft transmission mechanism 7 is connected to the gear on the rear planetary row planet carrier 6-6 in the double planetary row coupling mechanism 6, and the input shaft gear 8-1 in the high and low speed switching mechanism 8 is connected to the output shaft A7-2 in the drive output shaft transmission mechanism 7 to form the electric tractor dual motor transmission device.

[0030] like Figure 3As shown, the double planetary gear coupling mechanism 6 includes a front planetary gear mechanism, a rear planetary gear mechanism, a double planetary gear common ring gear 6-3, a ring gear brake 6-4 and a ring gear fixed bearing 6-5. The front planetary gear mechanism and the rear planetary gear mechanism are arranged at intervals in the housing of the gearbox. The front planetary gear carriers 6-2 at the upper and lower ends of the front planetary gear mechanism and the rear planetary gear carriers 6-6 at the upper and lower ends of the rear planetary gear mechanism are respectively connected to the double planetary gear common ring gear 6-3 located at the upper and lower ends of the housing. The two double planetary gear common ring gears 6-3 are respectively installed on the housing through ring gear fixed bearings 6-5. Ring gear brakes 6-4 are respectively provided on the outside of the double planetary gear common ring gear 6-3, and the fixed ends of the ring gear brakes 6-4 are arranged on the housing. During implementation, the front planetary gear mechanism includes a front planetary gear sun gear 6-1 and a front planetary gear carrier 6-2, the front planetary gear carrier 6-2 is provided in two, the two front planetary gear carriers 6-2 are arranged at intervals, and the front planetary gear sun gear 6-1 is arranged between the two front planetary gear carriers 6-2. The rear planetary gear mechanism includes a rear planetary gear carrier 6-6 and a rear planetary gear sun gear 6-7, the rear planetary gear carrier 6-6 is provided in two, the two rear planetary gear carriers 6-6 are arranged at intervals, and the rear planetary gear sun gear 6-7 is arranged between the two rear planetary gear carriers 6-6.

[0031] like Figure 4 As shown, the driving output shaft transmission mechanism 7 includes an output shaft gear A7-1, an output shaft A7-2 and an output shaft brake 7-3. The output shaft gear A7-1 is meshed with the gear on the rear planetary gear carrier 6-6. The output shaft gear A7-1 is sleeved on the output shaft A7-2. An output shaft brake 7-3 is provided on the output shaft A7-2. The fixed end of the output shaft brake 7-3 is set on the housing of the gearbox.

[0032] like Figure 5 As shown, the high-low speed switching mechanism 8 includes an input shaft gear 8-1, an intermediate shaft input gear 8-2, an intermediate shaft output gear 8-3, an output shaft gear B8-4, a synchronizer 8-5 and an output shaft B8-6. The output shaft B8-6 is connected with the output shaft A7-2 to form a high-low speed switching power input shaft. The input shaft gear 8-1, the synchronizer 8-5 and the output shaft gear B8-4 are arranged on the high-low speed switching power input shaft from left to right. The input shaft gear 8-1 and the output shaft gear B8-4 are meshed with the intermediate shaft input gear 8-2 and the intermediate shaft output gear 8-3 respectively. During implementation, the intermediate shaft input gear 8-2 and the intermediate shaft output gear 8-3 are sleeved on the intermediate shaft at intervals, and the intermediate shaft is arranged on the gearbox housing through a bearing.

[0033] like Figure 2As shown, the PTO output transmission structure 9 includes a PTO output shaft gear 9-1, a PTO output shaft brake 9-2 and a PTO output shaft 9-3, wherein the PTO output shaft gear 9-1 is meshed with a gear on the front planetary gear carrier 6-2, the PTO output shaft gear 9-1 is arranged on the PTO output shaft 9-3, and the PTO output shaft 9-3 is provided with a PTO output shaft brake 9-2. The fixed end of the PTO output shaft brake 9-2 is connected to the gearbox housing, and the right end of the PTO output shaft 9-3 is connected to an agricultural implement requiring power input.

[0034] A control strategy for a dual-motor transmission device of an electric tractor, the control strategy adopts a simulated annealing algorithm, firstly, by collecting the working state information of the tractor, automatically determining the optimal working mode of the tractor, and then by adjusting the power coupling of the PTO drive motor 4 and the power drive motor 5, the tractor works in the optimal state, by calculating the different power couplings of the PTO drive motor 4 and the power drive motor 5, comparing the coupling results, and randomly searching for the global optimal solution of the objective function in the solution space in combination with the probability jump characteristics, and selecting the optimal solution by the probability formula Select a bad solution, expand the optimization range, and finally complete the optimization process of the solution space to find the optimal coupling power.

[0035] like Figure 6 As shown, a control strategy is specified according to the dual-motor transmission structure and working mode of the electric tractor; the driver's operation information collected by the operation control unit is converted into control instructions according to the control rules and transmitted to the drive control unit. The drive control unit selects the working mode of the electric tractor by integrating battery information and vehicle working status, completes mode switching by controlling the corresponding controller, and changes the control current of the motor at the same time to achieve precise control of speed and torque in different modes.

[0036] like Figure 7 As shown in the figure, let T = T0, which indicates the initial temperature for annealing, randomly generate an initial solution X0, and calculate the corresponding objective function value E(X0); let T = kT, where K is between 0 and 1, which is the temperature drop rate; for the current solution X t Apply random perturbations to generate a new solution X in its domain t+1 , and calculate the corresponding objective function value E(X t+1 ), calculate ΔE=E(X t+1 )-E(X t ); if ΔE<0, accept the new solution as the current solution, otherwise follow the probability Determine whether to accept the new solution; at temperature T, repeat the perturbation and acceptance process L times, that is, execute steps 3 and 4; determine whether the temperature reaches the termination temperature, if so, terminate the algorithm, otherwise return to step 2, and finally output the optimal motor power coupling parameters to complete the optimization process.

[0037] When the present invention is implemented, the working modes include the following forms:

[0038] Towing-only working mode: When operating at low power, only the PTO drive motor 4 works, the double planetary gear ring 6-3 is locked, the PTO output shaft brake 9-2 is released, and the output shaft brake 7-3 is released. The power transmission route is: PTO drive motor 4, front planetary gear sun gear 6-1, front planetary gear planet carrier 6-2, PTO output shaft gear 9-1, PTO output shaft 9-3. When operating at high power, two motors need to converge their power. At this time, the double planetary gear ring 6-3 is released, the PTO output shaft brake 9-2 is locked, and the output shaft brake 7-3 is released. The power transmission route is: PTO drive motor 4, front planetary gear sun gear 6-1, double planetary gear ring 6-3, rear planetary gear planet carrier 6-6. At this time, the power transmitted from the power drive motor 5 through the rear planetary gear sun gear 6-7 and the rear planetary gear planet carrier 6-6 converges, and then passes through the drive output shaft transmission mechanism 7 and the high-low speed switching mechanism 8 to the drive wheel.

[0039] PTO output mode only: At this time, the tractor has no power transmitted to the drive wheel. When the low-power PTO power is output, the ring gear brake 6-4 is locked, the PTO output shaft brake 9-2 is released, and the output shaft brake 7-3 is locked, interrupting the power transmission between the double planetary gears. The power drive motor 5 does not work, and the power is generated by the PTO drive motor 4, passed through the front planetary gear sun gear 6-1, the front planetary gear carrier 6-2, and transmitted to the PTO output transmission structure 9, and finally output to the outside through the PTO output shaft 9-3. When high-power PTO power is output, the ring gear brake 6-4 is released, the PTO output shaft brake 9-2 is released, the output shaft brake 7-3 is locked, and the power drive motor 5 participates in the work. The power of the power drive motor 5 is transmitted to the front planetary gear carrier 6-2 by the rear planetary gear sun gear 6-7, the rear planetary gear carrier 6-6, and the double planetary gear common ring gear 6-3, and finally generates power with the PTO drive motor 4, passes through the front planetary gear sun gear 6-1, and is transmitted to the front planetary gear carrier 6-2. The power converges, is then transmitted to the PTO output transmission structure 9, and finally is output to the outside through the PTO output shaft 9-3.

[0040] When the PTO and power output are in simultaneous working mode: the double planetary gear ring 6-3 is released, the PTO output shaft brake 9-2 and the output shaft brake 7-3 are released, and the power transmission between the double planetary gears is restored. The PTO drive motor 4 and the power drive motor 5 work at the same time. According to the output power of the PTO output shaft 9-3 and the power output shaft, the two motors realize power convergence and diversion through the double planetary gear ring 6-3, and the drive control unit 3 adjusts the power matching of the two motors to realize the adjustment of the vehicle speed and the PTO shaft speed.

[0041] The beneficial effects of the present invention are as follows:

[0042] 1. The present invention can realize the independent operation of the PTO drive motor 4 and the power drive motor 5, and realize the convergence and diversion of power according to different working modes, thereby improving the utilization rate of the motor and enhancing the adaptability of the electric tractor.

[0043] 2. The high-low speed switching mechanism 8 can change the transmission ratio to achieve high-speed and low-speed switching, making up for the limitation of the motor in the speed regulation range, and at the same time setting a neutral position for the convenience of towing.

[0044] 3. The designed mechanism uses a double planetary gear common ring 6-3, eliminating the gear transmission required for power coupling in other designs, making the structure simpler and more stable. The two motors are placed in front and behind the double planetary gear coupling mechanism 6, respectively, with uniform weight distribution, which is conducive to the layout on the tractor frame.

[0045] 4. The control system only needs to control 3 brakes and 2 motors to achieve the convergence and diversion of mode switching power and the adjustment of power size, which simplifies the complexity of the control system and improves the stability of the system.

[0046] 5. The present invention adopts a modular design. The double planetary gear coupling mechanism 6, the PTO drive motor 4, the power drive motor 5, the PTO output transmission structure 9, the drive output shaft transmission mechanism 7, and the high-speed and low-speed switching mechanism 8 are respectively separate assembly modules, which are convenient for rapid assembly and maintenance and replacement, thereby improving production efficiency.

[0047] Parts of the present invention not described in detail are prior art.

[0048] The embodiments selected herein for the purpose of disclosing the invention are currently considered to be suitable, but it should be understood that the invention is intended to include all changes and modifications of the embodiments that fall within the scope of the concept and invention.

Claims

1. A dual-motor transmission device for an electric tractor, comprising a power battery pack (1), an operation control unit (2), a drive control unit (3), a PTO drive motor (4), a power drive motor (5), a dual planetary gear coupling mechanism (6), a drive output shaft transmission mechanism (7), a high-speed and low-speed switching mechanism (8), a PTO output transmission structure (9) and an energy management system (10), wherein: The power battery pack (1) is arranged at the front of the tractor. The power battery pack (1) is connected to a drive control unit (3) through a wire to provide electric energy for the drive control unit (3). The drive control unit (3) is arranged at the bottom of a seat in a cab. The drive control unit (3) is respectively connected to an operation control unit (2), a PTO drive motor (4), a power drive motor (5), a ring gear brake (6-4) in a double planetary gear coupling mechanism (6), an output shaft brake (7-3) in a drive output shaft transmission mechanism (7), a PTO output shaft brake (9-2) in a PTO output transmission structure (9), and an energy management system (10) through wires. The operation control unit (2) is arranged in the cab. The torque and speed of the PTO drive motor (4) and the power drive motor (5) are controlled by the drive control unit (3). The PTO drive motor (4) is arranged on a frame in the middle of the tractor body. The input shaft of the PTO drive motor (4) is connected to the front planetary gear sun gear (6-1) in the double planetary gear coupling mechanism (6). ) is connected to the front planetary gear mechanism through the front planetary gear sun gear (6-1), the power drive motor (5) is arranged on the frame at the rear of the tractor, the input shaft of the power drive motor (5) is connected to the rear planetary gear sun gear (6-7) in the double planetary gear coupling mechanism (6), and the power is transmitted to the rear planetary gear mechanism through the rear planetary gear sun gear (6-7), the double planetary gear coupling mechanism (6) is arranged between the PTO drive motor (4) and the power drive motor (5), the PTO output shaft gear (9-1) in the PTO output transmission structure (9) is connected to the gear on the front planetary gear carrier (6-2) in the double planetary gear coupling mechanism (6), the output shaft gear A (7-1) in the drive output shaft transmission mechanism (7) is connected to the gear on the rear planetary gear carrier (6-6) in the double planetary gear coupling mechanism (6), and the input shaft gear (8-1) in the high-low speed switching mechanism (8) is connected to the output shaft A (7-2) in the drive output shaft transmission mechanism (7), thereby forming the electric tractor dual motor transmission device.

2. The electric tractor dual-motor transmission device according to claim 1 is characterized in that: The double planetary gear coupling mechanism (6) comprises a front planetary gear mechanism, a rear planetary gear mechanism, a double planetary gear common ring gear (6-3), a ring gear brake (6-4) and a ring gear fixed bearing (6-5). The front planetary gear mechanism and the rear planetary gear mechanism are arranged in a housing of a gearbox at intervals. The front planetary gear carriers (6-2) at the upper and lower ends of the front planetary gear mechanism and the rear planetary gear carriers (6-6) at the upper and lower ends of the rear planetary gear mechanism are respectively connected to the double planetary gear common ring gear (6-3) located at the upper and lower ends of the housing. The two double planetary gear common ring gears (6-3) are respectively installed on the housing through the ring gear fixed bearings (6-5). Ring gear brakes (6-4) are respectively arranged outside the double planetary gear common ring gear (6-3), and the fixed ends of the ring gear brakes (6-4) are arranged on the housing.

3. The electric tractor dual-motor transmission device according to claim 2 is characterized in that: The front planetary gear mechanism comprises a front planetary gear sun gear (6-1) and a front planetary gear carrier (6-2). The front planetary gear carrier (6-2) is provided in two pieces. The two front planetary gear carriers (6-2) are provided at an interval. The front planetary gear sun gear (6-1) is provided between the two front planetary gear carriers (6-2).

4. The electric tractor dual-motor transmission device according to claim 2 is characterized in that: The rear planetary gear mechanism comprises a rear planetary gear carrier (6-6) and a rear planetary gear sun gear (6-7). The rear planetary gear carrier (6-6) is provided in two numbers. The two rear planetary gear carriers (6-6) are provided at intervals. The rear planetary gear sun gear (6-7) is provided between the two rear planetary gear carriers (6-6).

5. The electric tractor dual-motor transmission device according to claim 1, characterized in that: The driving output shaft transmission mechanism (7) comprises an output shaft gear A (7-1), an output shaft A (7-2) and an output shaft brake (7-3); the output shaft gear A (7-1) is meshed with a gear on a rear planetary gear carrier (6-6); the output shaft gear A (7-1) is sleeved on the output shaft A (7-2); an output shaft brake (7-3) is provided on the output shaft A (7-2); and a fixed end of the output shaft brake (7-3) is provided on a housing of a gearbox.

6. The electric tractor dual-motor transmission device according to claim 1, characterized in that: The high-low speed switching mechanism (8) comprises an input shaft gear (8-1), an intermediate shaft input gear (8-2), an intermediate shaft output gear (8-3), an output shaft gear B (8-4), a synchronizer (8-5) and an output shaft B (8-6); the output shaft B (8-6) is connected to the output shaft A (7-2) to form a high-low speed switching power input shaft; the input shaft gear (8-1), the synchronizer (8-5) and the output shaft gear B (8-4) are arranged on the high-low speed switching power input shaft from left to right in sequence; the input shaft gear (8-1) and the output shaft gear B (8-4) are respectively meshed with the intermediate shaft input gear (8-2) and the intermediate shaft output gear (8-3).

7. The electric tractor dual-motor transmission device according to claim 6, characterized in that: The intermediate shaft input gear (8-2) and the intermediate shaft output gear (8-3) are sleeved on the intermediate shaft at intervals, and the intermediate shaft is arranged on the gearbox housing through a bearing.

8. The electric tractor dual-motor transmission device according to claim 1, characterized in that: The PTO output transmission structure (9) comprises a PTO output shaft gear (9-1), a PTO output shaft brake (9-2) and a PTO output shaft (9-3); the PTO output shaft gear (9-1) is meshed with a gear on a front planetary gear carrier (6-2); the PTO output shaft gear (9-1) is arranged on the PTO output shaft (9-3); and the PTO output shaft (9-3) is provided with a PTO output shaft brake (9-2).

9. The electric tractor dual-motor transmission device according to claim 8, characterized in that: The fixed end of the PTO output shaft brake (9-2) is connected to the gearbox housing, and the right end of the PTO output shaft (9-3) is connected to an agricultural implement requiring power input.

10. The control strategy of the dual-motor transmission device of an electric tractor according to any one of claims 1 to 9 is characterized in that: The control strategy adopts a simulated annealing algorithm. First, the tractor's working state information is collected to automatically determine the tractor's optimal working mode. Then, the power coupling between the PTO drive motor (4) and the power drive motor (5) is adjusted to make the tractor work in the optimal state. Different power couplings between the PTO drive motor (4) and the power drive motor (5) are calculated, the coupling results are compared, and the global optimal solution of the objective function is randomly found in the solution space in combination with the probability jump characteristic. The probability selection formula is used to select the optimal solution. Select a bad solution, expand the optimization range, and finally complete the optimization process of the solution space to find the optimal coupling power.

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