Hybrid Tractor Power System, Control Method, Product, Equipment and Medium

Abstract

The present disclosure provides a hybrid tractor power system, a control method, a product, a device and a medium, relating to the technical field of tractors, including an engine and a CVT transmission; the CVT transmission adopts a structure of dual power batteries, dual drive motors and dual variable motors. The dual power batteries include a first power battery and a second power battery. The dual drive motors include a first drive motor and a second drive motor. The dual variable motors include a generator and a CPTO drive motor. The tractor provides three types of power paths: the engine directly provides power for the wheels through a gear pair; the engine drives the generator to charge the dual power batteries, and is connected to at least any of the dual drive motors and the dual variable motors through the dual power batteries to provide power for the wheels; the engine drives the generator to charge the dual power batteries, and the dual power batteries provide power for agricultural implements through the CPTO drive motor. The present invention significantly improves the overall performance and operation efficiency of the tractor.

Description

Technical Field

[0001] The present disclosure relates to the technical field of tractors, and particularly to a power system, a control method, a product, a device and a medium of a hybrid tractor. Background Art

[0002] With the acceleration of the global agricultural modernization process, as a core power equipment in agricultural production, the energy utilization efficiency and environmental impact of tractors have attracted increasing attention. Traditional tractors mostly rely on diesel engines for driving. Although they have powerful power output, they also face problems such as high fuel consumption and heavy emission pollution. Especially in complex operating environments, the load of the tractor's power system fluctuates greatly, resulting in the engine often being in a non-optimal working condition, further exacerbating fuel waste and environmental pollution. Therefore, how to improve the energy efficiency of tractors and reduce emissions has become an urgent problem to be solved in the current field of agricultural machinery.

[0003] In this context, hybrid tractors, as an emerging power system solution, have gradually attracted research and application attention. The hybrid technology combines the advantages of traditional internal combustion engines and electric motors. It can not only optimize power output under different working conditions, improve energy utilization efficiency, but also effectively reduce emissions and relieve the environmental burden. Especially during the operation process, the hybrid system can dynamically adjust the power source according to the load demand, thereby avoiding the internal combustion engine running in an inefficient working condition for a long time, and improving the overall efficiency of the system and the operating performance of the tractor.

[0004] With the continuous development of battery technology and control strategies, hybrid tractors not only have the potential to make breakthroughs in energy efficiency and emissions, but also provide new possibilities for the green transformation of agricultural machinery. There are currently two main technical routes for hybrid tractors: plug-in hybrid electric vehicle (PHEV) and range-extended electric vehicle (REEV). In a plug-in hybrid electric vehicle (PHEV), the engine and the generator can work together to support both the electric motor drive and the engine drive modes, while in a range-extended electric vehicle (REEV), the engine does not directly drive the wheels but serves as a generator to charge the battery, and the vehicle is completely driven by the electric motor.

[0005] Facing the complex and changeable farmland operation environment, the plug-in hybrid transmission can improve fuel economy under low-load working conditions by virtue of its larger battery capacity and longer electric driving range advantages. The range-extended hybrid transmission, on the other hand, uses its efficient energy management system to enable the engine to work under the optimal working condition, taking into account both power performance and fuel economy, and is particularly suitable for long-time and high-load operation scenarios. At the same time, there are also some technical problems with hybrid tractors of these two different routes:

[0006] 1. Problems existing in plug-in hybrid tractors

[0007] (1)When a plug-in hybrid tractor relies on the battery for pure electric drive, the battery capacity is limited. This means that during long-term high-load operations, the battery power may be quickly consumed, affecting the operation time and efficiency. Especially in rural areas lacking charging facilities, it may lead to operation interruptions.

[0008] (2)To ensure its charging needs, a plug-in hybrid tractor requires a complete charging infrastructure. Although it is relatively easy to charge in urban or more developed areas, in remote rural areas, the imperfect charging facilities will limit its use.

[0009] (3)The battery is a key component of the plug-in hybrid system. It is usually relatively expensive, and as the usage time increases, the battery characteristics change, the health life will decline, and the cost of replacing the battery is also relatively high. In addition, the performance of the battery may be poor in low-temperature environments, affecting the operation efficiency in the low-temperature season.

[0010] In summary, when designing a plug-in hybrid tractor, it mainly relies on the battery for pure electric drive, and the working scenarios are mostly suitable for modern small farms with timely charging facilities; also, the heavier the tractor, the faster the power consumption, which limits the weight of the tractor itself and the attached agricultural machinery.

[0011] 2. Problems existing in range-extended hybrid tractors

[0012] (1)The engine in the range-extended hybrid system usually needs to operate under specific working conditions (such as the optimal speed). However, in some low-load or high-load working conditions, the engine may not be operating within its optimal efficiency range, resulting in reduced fuel economy.

[0013] (2)The battery, as a key component of the range-extended tractor, although it can provide electric drive in a short time, the battery capacity is limited and cannot support long-term high-load operations. The service life of the battery will also gradually decline as the number of charge and discharge cycles increases.

[0014] Therefore, the existing hybrid tractors have deficiencies in economy, overall performance, and operation efficiency. Summary of the Invention

[0015] The present disclosure proposes a power system, control method, product, device, and medium for a hybrid tractor to solve the above problems, significantly improving the overall performance and operation efficiency of the tractor.

[0016] According to some embodiments, the present disclosure adopts the following technical solutions:

[0017] A power system for a hybrid tractor, comprising an engine and a CVT transmission;

[0018] The CVT transmission adopts a structure with two power batteries, two drive motors, and two variable motors. The two power batteries include a first power battery and a second power battery. The two drive motors include a first drive motor and a second drive motor. The two variable motors include a generator and a CPTO drive motor;

[0019] The tractor provides three types of power paths:

[0020] The first power path: The engine directly provides power to the wheels through a gear pair;

[0021] The second power path: The engine drives the generator to charge the two power batteries, and is connected to at least any of the two drive motors and the two variable motors through the two power batteries to provide power to the wheels;

[0022] The third power path: The engine drives the generator to charge the two power batteries, and the two power batteries provide power to agricultural implements through the CPTO drive motor.

[0023] According to some embodiments, the present disclosure adopts the following technical solutions:

[0024] A control method for a power system of a hybrid tractor selects a power path for control according to the current working mode of the tractor. Specifically:

[0025] In the low-load starting mode, select the second power path, and the first drive motor and the second drive motor drive jointly;

[0026] In the high-load starting mode, select the second power path. On the premise that the first drive motor and the second drive motor drive jointly, judge whether the generator and the CPTO drive motor participate in driving according to the required power;

[0027] In the low-load traveling mode, select the second power path, and the first drive motor and the second drive motor drive jointly;

[0028] In the high-load traveling mode, according to the discharge rate of the power battery, it is divided into two control methods:

[0029] (1) When the discharge rate of at least one of the first power battery and the second power battery is greater than the threshold, select the combination of the first power path and the second power path. On the premise that the engine and the second drive motor drive jointly, judge whether the CPTO drive motor participates in driving according to the required power;

[0030] (2) When the discharge rates of both the first power battery and the second power battery are not greater than the threshold, select the second power path. On the premise that the first drive motor and the second drive motor drive jointly, judge whether the generator and the CPTO drive motor participate in driving according to the required power;

[0031] In the current working mode, when there is a farming requirement, an additional third power path is combined and controlled.

[0032] Among them, during the control process where the generator is not converted into a drive motor, according to the real-time predicted low-resistance interval and the current battery power, differential control is performed on the charging and discharging of the first power battery and the second power battery.

[0033] According to some embodiments, the present disclosure adopts the following technical solutions:

[0034] A computer program product includes a computer program, and when the computer program is executed by a processor, it implements the control method of a hybrid tractor power system as described above.

[0035] According to some embodiments, the present disclosure adopts the following technical solutions:

[0036] A non-transitory computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the control method of a hybrid tractor power system as described above is implemented.

[0037] According to some embodiments, the present disclosure adopts the following technical solutions:

[0038] An electronic device includes: a processor, a memory, and a computer program; wherein, the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device runs, the processor executes the computer program stored in the memory so that the electronic device executes and implements the control method of a hybrid tractor power system as described above.

[0039] Compared with the prior art, the beneficial effects of the present disclosure are:

[0040] (1) Regarding the plug-in hybrid problem, the present invention adopts an extended-range hybrid technical solution, and the engine drives the generator to provide continuous electrical energy for the first power battery and the second power battery, thereby significantly increasing the effective driving range of the tractor for a single operation.

[0041] (2) Regarding the problem of excessive power consumption when the load is large, in addition to adopting the extended-range hybrid technical solution, the present invention introduces the idea of parallel connection of the engine and the drive motor into the drive path. Through the cooperative engagement of the first clutch and the third clutch, the engine directly participates in driving. In this case, the engine can not only drive the generator but also drive the gear pair.

[0042] (3) By optimizing the starting process of the tractor, the present invention effectively solves the power problems under low-load and high-load conditions; when starting under low load, it avoids excessive consumption of battery power caused by multi-motor drive, thereby improving the economy of the whole machine; when starting under high load, by reasonably configuring the power system, it avoids the problem of insufficient power of single-motor drive and ensures the smoothness and efficiency of the tractor starting; these improvement measures significantly improve the overall performance and operation efficiency of the tractor.

[0043] (4) In order to address the battery life issue of the power battery of the range-extended hybrid tractor and considering the law of battery life attenuation of multiple power batteries, the present invention proposes a dynamic balancing method for the output power of multiple batteries based on the low-resistance power range of the battery; this method can dynamically adjust the charge and discharge strategy according to the health status of the battery, so that the energy consumption of the tractor is always kept within the optimal energy efficiency range, extend the service life of the battery, and improve the overall economy and reliability of the system at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings forming a part of this disclosure are used to provide a further understanding of this disclosure. The schematic embodiments and descriptions thereof of this disclosure are used to explain this disclosure and do not constitute an improper limitation of this disclosure.

[0045] Figure 1 It is a structural diagram of the power system of the hybrid tractor in Embodiment 1.

[0046] Figure 2 It is a relationship diagram between the internal resistance and the battery power (SOC) of the battery in Embodiment 2.

[0047] Among them, 1, engine; 2, generator; 3, first drive motor; 4, first power battery; 5, second power battery; 6, second drive motor; 7, first gear pair; 8, second gear pair; 9, first clutch; 10, third gear pair; 11, fourth gear pair; 12, planetary gear ring; 13, planetary gear carrier; 14, planetary gear sun gear; 15, fifth gear pair; 16, sixth gear pair; 17, seventh gear pair; 18, eighth gear pair; 19, ninth gear pair; 20, tenth gear pair; 21, eleventh gear pair; 22, CPTO drive motor; 23, CPTO clutch; 24, second clutch; 25, twelfth gear pair; 26, thirteenth gear pair; 27, third clutch; 28, planetary gear mechanism; 29, CVT transmission; S1, first control switch; S2, second control switch; S3, third control switch; S4, fourth control switch; S5, fifth control switch; S6, sixth control switch; S7, seventh control switch; S8, eighth control switch. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

[0049] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which the present disclosure belongs.

[0050] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0051] Term Explanation:

[0052] CPTO: Clutch Power Take Off, the clutch of the power take-off device;

[0053] CVT: Continuously Variable Transmission, continuously variable transmission.

[0054] Embodiment 1

[0055] In one embodiment of the present disclosure, a hybrid tractor power system is provided. As Figure 1 shown, it includes an engine 1 and a CVT transmission 29. Figure 1 In the figure, the red line is for wire harness connection, the black line is for mechanical connection, and the blue line is for shaft connection.

[0056] The CVT transmission 29 adopts a structure of double power batteries, double drive motors, and double variable motors. The double power batteries include a first power battery 4 and a second power battery 5. The double drive motors include a first drive motor 3 and a second drive motor 6. The double variable motors include a generator 2 and a CPTO drive motor 22.

[0057] The tractor provides three types of power paths:

[0058] The first power path: The engine 1 directly provides power to the wheels through a gear pair.

[0059] Specifically, the driving path of the engine 1 is as follows: The engine 1 drives the first gear pair 7, the first gear pair 7 drives the second gear pair 8 to rotate, the second gear pair 8 drives the planetary gear ring 12. When the power is transmitted to the planetary gear ring 12, a power path from the engine 1 to the planetary gear mechanism 28 is achieved here, and the engine 1 directly participates in the working process of providing power to the wheels under this power path.

[0060] Second power path: The engine 1 drives the generator 2 to charge the dual power battery, and is connected to at least any one of the dual drive motors and the dual variable motors through the dual power battery to provide power to the wheels.

[0061] Among them, the driving path of the first drive motor 3 is as follows: The first drive motor 3 drives the third gear pair 10 to drive the third gear pair 10 to rotate, the third gear pair 10 drives the fourth gear pair 11, and the fourth gear pair 11 drives the planetary gear ring 12 to rotate, transmitting the power to the planetary gear mechanism 28.

[0062] The driving path of the second drive motor 6 is as follows: The second drive motor 6 drives the fifth gear pair 15, and the fifth gear pair 15 drives the sixth gear pair 16 to transmit the power to the planetary gear mechanism 28.

[0063] The driving path of the CPTO drive motor 22 (driving the wheels) is as follows: The CPTO drive motor 22 drives the twelfth gear pair 25, the twelfth gear pair 25 drives the thirteenth gear pair 26, the thirteenth gear pair 26 drives the fifth gear pair 15, and the fifth gear pair 15 drives the sixth gear pair 16 to transmit the power to the planetary gear mechanism 28.

[0064] Third power path: The engine 1 drives the generator 2 to charge the dual power battery, and the dual power battery provides power to the agricultural implements through the CPTO drive motor 22.

[0065] Specifically, the driving path of the CPTO drive motor 22 (driving the agricultural implements) is as follows: The CPTO drive motor 22 is connected to the agricultural implements through the CPTO clutch 23 to provide power to the agricultural implements.

[0066] The wheels have reverse gears and forward gears. The ninth gear pair 19, the tenth gear pair 20, and the eleventh gear pair 21 are all used for reverse gears, while the eighth gear pair 18 is used for forward gears.

[0067] When the power converges in the planetary gear mechanism 28, the planetary gear carrier 13 serves as the power output end, and the planetary gear carrier 13 drives the seventh gear pair 17. The seventh gear pair 17 drives different gear pairs for power output according to whether it is a reverse gear or a forward gear.

[0068] Further, the engine 1 is connected to the generator 2 through the third clutch 27. The engine 1 is connected to the wheels through the first gear pair 7, the second gear pair 8, the first clutch 9, and the planetary gear mechanism 28. The generator 2 is respectively connected to the first power battery 4 and the second power battery 5 through the first control switch S1 and the second control switch S2.

[0069] Further, the outputs of the first power battery 4 and the second power battery 5 are respectively connected to the first drive motor 3 through the third control switch S3 and the fourth control switch S4, connected to the second drive motor 6 through the fifth control switch S5 and the sixth control switch S6, and connected to the CPTO drive motor 22 through the seventh control switch S7 and the eighth control switch S8.

[0070] Further, the first drive motor 3 and the second drive motor 6 are respectively connected to the wheels through gear pairs and the planetary gear mechanism 28.

[0071] Further, the CPTO drive motor 22 is connected to the agricultural implement through the CPTO clutch 23, and connected to the wheels through gear pairs, the second clutch 24, and the planetary gear mechanism 28.

[0072] The battery capacity of the plug-in hybrid mode is limited. At the same time, the preset working mode of the plug-in hybrid tractor is mainly the pure electric mode. The battery capacity has a decisive effect on the endurance and power performance of the tractor. Therefore, this mode is not suitable for medium and large tractors used in large farms. So, this embodiment adopts a new type of hybrid tractor with dual power batteries + dual drive motors + dual variable motors, and realizes the speed regulation process of variable load by controlling the clutch and switch, making the entire power system more reliable and easier to maintain in the later stage. The key points of the new type of hybrid tractor are described below:

[0073] 1. The engine 1 drives the generator 2 to generate electricity to continuously supply electric energy to the first power battery 4 and the second power battery 5, achieving the purpose of charging while driving. Specifically:

[0074] When the battery power of either the first power battery 4 or the second power battery 5 drops to the lower limit of the predicted low-resistance battery power range, the driving charging mode is turned on, and the first control switch S1 of the generator 2 and the second control switch S2 of the generator 2 are closed.

[0075] Through the engagement of the third clutch 27, the engine 1 drives the generator 2 to generate electricity and charges the first power battery 4 and the second power battery 5 while driving. When the battery powers of both power batteries reach the upper limit of the predicted low-resistance battery power range, the first control switch S1 and the second control switch S2 are turned off, and the driving charging mode is turned off.

[0076] II. To solve the problem of excessive battery discharge rate caused by large load or cold environment during walking, the idea of parallel connection of the engine 1 and the drive motor is introduced into the drive path. Through the engagement of the first clutch 9 and the third clutch 27, the engine 1 directly participates in the operation of the CVT transmission 29, drives the first gear pair 7, and provides power for the tractor.

[0077] The battery discharge rate is too fast. In this embodiment, it is defined that the discharge rate is not lower than 0.5C. A discharge rate of 0.5C means that the battery is completely discharged within 2 hours. If the battery capacity is 100Ah, it is discharged at a current of 100A within 2 hours; a discharge rate of 1C means that the battery is completely discharged within 1 hour. If the battery capacity is 100Ah, it is discharged at a current of 100A within 1 hour.

[0078] The idea of parallel connection of the engine 1 and the drive motor is introduced into the drive path. The specific implementation method is as follows:

[0079] Through the first clutch 9 and the third clutch 27, when the two clutches are engaged, the engine 1 participates in driving the first gear pair 7, and the power is transmitted to the second gear pair 8 through the first gear pair 7. At the same time, the third control switch S3 and the fourth control switch S4 are turned off, the first drive motor 3 stops working, the fifth control switch S5 and the sixth control switch S6 are turned on, and the dual power batteries supply power to the second drive motor 6, thus realizing the power transmission path in which the engine 1 and the second drive motor 6 transmit power to the planetary gear ring 12 of the planetary gear mechanism 28 and the planetary gear carrier 13 outputs power.

[0080] Adopting the power transmission method of parallel connection of the engine 1 and the second drive motor 6, switching from the pure electric mode to the parallel hybrid mode can effectively alleviate the problem of excessive power consumption of the power battery. At the same time, according to the following formula (1), the required torque of the planetary gear carrier 13 is greater, and in this connection method, the engine 1 can directly converge power to the planetary gear carrier 13:

[0081] (1)

[0082] Where M14 is the torque of the planetary gear sun gear 14, M12 is the torque of the planetary gear ring 12, M13 is the torque of the planetary gear carrier 13, and α is the tooth ratio of the planetary gear ring 12 to the planetary gear sun gear 14.

[0083] III. During the starting process of the tractor, it will face various different operating conditions, and the loads on the tractor are not the same in different situations; in the case of low-load starting, multi-motor drive will increase the power consumption of the power battery and reduce the economy of the whole machine; in the case of high-load starting, the problem of insufficient power brought by single-motor drive will make it difficult for the tractor to start, reduce efficiency. At multiple input ends of the planetary gear, if the required torque at the input end is greater than the rated torque of a single motor, it is considered a high load, otherwise it is a low load. The specific solution is as follows:

[0084] For the low-load starting situation, the combination of multiple power batteries can ensure a relatively high power supply.

[0085] Specifically, in the case of low load, the first drive motor 3 and the second drive motor 6 are driven by dual motors to transmit power to the planetary gear mechanism 28, and the planetary carrier 13 of the planetary gear transmits power outward to drive the wheels.

[0086] For the high-load starting situation, the tractor is subject to a large ground static friction force, and stronger power is required at this time.

[0087] At this time, the first clutch 9 and the second clutch 24 are both engaged, the third clutch 27 is disengaged, and the engine 1 does not work. The tractor is in a pure electric mode. The starting in the pure electric mode has a higher mechanical efficiency than the parallel connection of the engine 1 and the drive motor. The first control switch S1 and the second control switch S2 are closed. The first power battery 4 and the second power battery 5 supply power to the generator 2. The generator 2 acts as a drive motor to provide power to the first to seventh gear pairs 17 at this time. The generator 2, the first drive motor 3, the second drive motor 6, and the CPTO drive motor 22 are driven by four motors simultaneously to transmit power to the planetary mechanism, and the planetary carrier 13 of the planetary gear transmits power outward to drive the wheels.

[0088] Embodiment 2

[0089] In an embodiment of the present disclosure, a control method for the power system of a hybrid tractor is provided. According to the current working mode of the tractor, a power path is selected for control, that is, according to different loads, the number of motors participating in the drive of the power system is different. The power system adopts a structure of "dual power batteries + dual drive motors + dual variable motors" to achieve dual-motor or four-motor drive. At the same time, the prediction of the internal resistance values of multiple power batteries realizes the dynamic balance of the charging and discharging of multiple batteries, and realizes the separate control of the state of the generator 2, the state of the drive motor, the state of the control switch, the state of the drive clutch, and the state of the CPTO clutch 23. The following gives the control methods for several typical working modes of the tractor:

[0090] 1. Low-load starting mode

[0091] Select the second power path, and the first drive motor 3 and the second drive motor 6 are jointly driven. The current state is:

[0092] 1) State of the generator 2: Determined according to the SOC, that is, judge whether the battery charge SOC is less than the lower limit SOC of the low-resistance range min_limit , if less, generate electricity;

[0093] 2) State of the drive motor: The first drive motor 3 and the second drive motor 6 are jointly driven;

[0094] 3) State of the control switch: The seventh control switch S7 and the eighth control switch S8 are open, the third control switch S3, the fourth control switch S4, the fifth control switch S5, and the sixth control switch S6 are closed, and the first control switch S1 and the second control switch S2 are determined according to the SOC;

[0095] 4) State of the drive clutch: The third clutch 27 is determined according to the SOC;

[0096] 5) State of the CPTO clutch 23: Judge engagement and disengagement according to whether farming is carried out.

[0097] 2. High-load starting mode

[0098] Select the second power path. On the premise that the first drive motor 3 and the second drive motor 6 are jointly driven, judge whether the generator 2 and the CPTO drive motor 22 participate in driving according to the required power. The current state is:

[0099] 1) State of the generator 2: Do not generate electricity

[0100] 2) State of the drive motor: The generator 2 is converted into a drive motor, and the generator 2, the first drive motor 3, the second drive motor 6, and the CPTO drive motor 22 are driven;

[0101] 3) State of the control switch: The first control switch S1, the second control switch S2, the seventh control switch S7, and the eighth control switch S8 are closed, and the third control switch S3, the fourth control switch S4, the fifth control switch S5, and the sixth control switch S6 are closed;

[0102] 4) State of the drive clutch: The first clutch 9 and the second clutch 24 are engaged, and the third clutch 27 is determined according to the SOC;

[0103] 5) State of the CPTO clutch 23: Judge engagement and disengagement according to whether farming is carried out.

[0104] Among them, in the case of "no farming is required" and "no power generation is required", whether the generator 2 is converted into a drive motor and the CPTO drive motor 22 is driven to provide power as a drive motor is judged by the following conditions:

[0105] If the required torque of the fifth gear pair 15 > the rated torque of the second drive motor 6, the CPTO drive motor 22 participates in driving; if the required torque of the third gear pair 10 is greater than the rated torque of the first drive motor 3, in-vehicle charging is not available and the generator 2 is used as a drive motor.

[0106] 3. Low-load walking mode

[0107] Select the second power path, and the first drive motor 3 and the second drive motor 6 jointly drive. The current state is:

[0108] 1) State of the generator 2: Determined according to the SOC, that is, judge whether the battery power SOC is less than the lower limit SOC of the low-resistance range min_limit , if less, generate electricity;

[0109] 2) State of the drive motor: The first drive motor 3 and the second drive motor 6 drive;

[0110] 3) State of the control switch: The seventh control switch S7 and the eighth control switch S8 are off, the third control switch S3, the fourth control switch S4, the fifth control switch S5, and the sixth control switch S6 are on, and the first control switch S1 and the second control switch S2 are determined according to the SOC;

[0111] 4) State of the drive clutch: The third clutch 27 is determined according to the SOC;

[0112] 5) State of the CPTO clutch 23: Engage and disengage according to whether farming is carried out.

[0113] 4. High-load walking mode

[0114] According to the discharge rate of the power battery, it is divided into two control methods:

[0115] The first control method: When the discharge rate of at least one of the first power battery 4 and the second power battery 5 is greater than the threshold, select the combination of the first power path and the second power path. On the premise of the combined drive of the engine 1 and the second drive motor 6, judge whether the CPTO drive motor 22 participates in driving according to the required power, and provide two high-load walking modes:

[0116] (1) High-load walking mode 1, the condition is that the battery discharge rate > 0.5C && the required torque of the fifth gear pair 15 < the rated torque of the second drive motor 6:

[0117] 1) State of the generator 2: Determined according to the SOC, that is, judge whether the battery power SOC is less than the lower limit SOC of the low-resistance range min_limit , if less, generate electricity;

[0118] 2) State of the drive motor: The second drive motor 6 drives;

[0119] 3) Control switch status: The fifth control switch S5 and the sixth control switch S6 are closed, the first control switch S1 and the second control switch S2 are determined according to the SOC, and the third control switch S3, the fourth control switch S4, the seventh control switch S7, and the eighth control switch S8 are open;

[0120] 4) Driving clutch status: The first clutch 9 and the third clutch 27 are engaged, and the second clutch 24 is disengaged;

[0121] 5) Status of the CPTO clutch 23: Determine engagement and disengagement according to whether farming is carried out.

[0122] (2) High-load walking mode two, the condition is that the battery discharge rate > 0.5C && the required torque of the fifth gear pair 15 > the rated torque of the second drive motor 6:

[0123] 1) Status of the generator 2: Determined according to the SOC, that is, judge whether the battery power SOC is less than the lower limit SOC of the low-resistance range min_limit , if less, generate electricity;

[0124] 2) Driving motor status: The second drive motor 6 and the CPTO drive motor 22 are driving;

[0125] 3) Control switch status: The fifth control switch S5, the sixth control switch S6, the seventh control switch S7, and the eighth control switch S8 are closed, the first control switch S1 and the second control switch S2 are determined according to the SOC, and the third control switch S3 and the fourth control switch S4 are open;

[0126] 4) Driving clutch status: The first clutch 9, the second clutch 24, and the third clutch 27 are engaged;

[0127] 5) Status of the CPTO clutch 23: Determine engagement and disengagement according to whether farming is carried out.

[0128] The second control method: When the discharge rates of the first power battery 4 and the second power battery 5 are not greater than the threshold value, select the second power path. On the premise of the combined drive of the first drive motor 3 and the second drive motor 6, judge whether the generator 2 and the CPTO drive motor 22 participate in the drive according to the required power, and provide two high-load walking modes:

[0129] (1) High-load walking mode three, the condition is that the battery discharge rate < 0.5C && the required torque of the fifth gear pair 15 < the rated torque of the second drive motor 6:

[0130] 1) Status of the generator 2: Determined according to the SOC, that is, judge whether the battery power SOC is less than the lower limit SOC of the low-resistance range min_limit , if less, generate electricity;

[0131] 2) Driving motor status: the first driving motor 3, the second driving motor 6;

[0132] 3) Control switch status: the third control switch S3, the fourth control switch S4, the fifth control switch S5, the sixth control switch S6, the seventh control switch S7, the eighth control switch S8 are closed, and the first control switch S1 and the second control switch S2 are determined according to the SOC;

[0133] 4) Driving clutch status: the second clutch 24 is engaged, and the third clutch 27 is determined according to the SOC;

[0134] 5) Status of the CPTO clutch 23: Determine engagement and disengagement according to whether farming is carried out.

[0135] (2) High-load walking mode four, the condition is that the battery discharge rate < 0.5C && the required torque of the fifth gear pair 15 > the rated torque of the second driving motor 6:

[0136] 1) Status of the generator 2: Determined according to the SOC, that is, judge whether the battery power SOC is less than the lower limit SOC of the low-resistance interval min_limit , if less, generate electricity;

[0137] 2) Driving motor status: driven by the first driving motor 3, the second driving motor 6, and the CPTO driving motor 22;

[0138] 3) Control switch status: the third control switch S3, the fourth control switch S4, the fifth control switch S5, the sixth control switch S6, the seventh control switch S7, the eighth control switch S8 are closed, and the first control switch S1 and the second control switch S2 are determined according to the SOC;

[0139] 4) Driving clutch status: the second clutch 24 is engaged, and the third clutch 27 is determined according to the SOC;

[0140] 5) Status of the CPTO clutch 23: Determine engagement and disengagement according to whether farming is carried out.

[0141] In the current working mode, when there is a farming requirement, that is, when farming needs to be carried out, an additional third power path is used for combined control.

[0142] Among them, during the control process where the generator 2 is not converted into a driving motor, differential control is performed on the charging and discharging of the first power battery 4 and the second power battery 5 according to the real-time predicted low-resistance interval and the current battery power.

[0143] The following is a detailed description of the differential control:

[0144] The quality of power batteries is mainly considered from multiple aspects such as energy storage density, the ability to release energy per unit time, the safe life of the battery, and environmental friendliness; currently, lithium batteries are often used as the power source for new energy vehicles in China, and their performance in the above aspects is much better than that of traditional chemical batteries. For the battery selection of range-extended buses, considering the service life and battery stability, lithium iron phosphate batteries, which are superior to ternary lithium batteries, are used as the type of power battery. Since power batteries are composed of many single cells with very small rated voltages and capacities through series and parallel combinations.

[0145] During manufacturing, the parameters between single cells are not exactly the same. As the number of usage times increases, the parameters of the battery continuously change. The most obvious manifestation is that the internal resistance of the battery will change continuously with the SOC.

[0146] For a single lithium iron phosphate battery, the trend of internal resistance during use is as Figure 2 shown. When discharging from 100% to 60% and from 30% to 0%, the internal resistance continuously increases, and the consumed electric power continuously increases; in the SOC range of 30% to 60%, the resistance value is relatively low and changes smoothly; therefore, the SOC range of 30% to 60% is defined as the best energy consumption range of the battery, and for the subsequent control rules, the SOC charging threshold value also refers to this relationship.

[0147] At the same time, the best energy consumption range is not fixed, and it will change with the use and aging of the battery; especially the increase in internal resistance may cause the original best energy consumption range to shrink or change. The temperature of the battery, the use environment, the charging method, and the optimization of the battery management system will all affect the range and performance of the best energy consumption range.

[0148] During the use of the battery, the increase in internal resistance and the attenuation of capacity are inevitable. A reasonable charging and use strategy helps to delay the change of the best energy consumption range and optimize the overall performance of the battery.

[0149] Therefore, this embodiment uses the method of LSTM + reinforcement learning for real-time prediction. Before training the prediction model, data collection and processing are required first, including SOC, internal resistance, current, voltage, temperature, C-rate (charge and discharge rate), and cycle times; set the time step Δt (1 min), collect the data shown in Table 1, and input the data set As shown in formula (2), the output data set As shown in formula (3):

[0150] (2)

[0151] (3)

[0152] Among them, SOC 1min_limitThe lower limit of the low-resistance range predicted for the first power battery 4; SOC 1max_limit The upper limit of the low-resistance range predicted for the first power battery 4; SOC 2min_limit The lower limit of the low-resistance range predicted for the second power battery 5; SOC2 max_limit The upper limit of the low-resistance range predicted for the second power battery 5.

[0153] Table 1 Acquisition data

[0154]

[0155] The input layer of the neural network receives multiple state variables of the battery. The hidden layer can contain multiple fully connected layers, and the output layer directly outputs two values: the upper and lower limits of the low-resistance range of SOC, which characterize the optimal energy consumption range. Input layer: Receives multiple state variables of the battery, with a dimension of 7. The hidden layer can be one or more fully connected layers, and the number of layers and neurons can be selected according to the complexity of the data. In this embodiment, two hidden layers are used as an example, each hidden layer has 64 neurons, and the ReLU activation function is used. The output layer directly outputs the upper and lower limits of the low internal resistance range of SOC. By inputting the real-time state of the battery (SOC, internal resistance, current, voltage, temperature, C-rate, number of cycles) into the neural network, the dynamic prediction of the upper / lower limits of the SOC range of the low resistance of the battery is realized, and a dynamically changing low-resistance range of the battery is obtained, so as to obtain the upper and lower limits of the SOC power of the battery charge and discharge for the subsequent charge and discharge balance of the dual batteries. Through the predicted low-resistance ranges of the first power battery 4 and the second power battery 5, by comparing the current battery power SOC with the low-resistance range power threshold in real time, the specific dynamic control logic is as follows:

[0156] (1) When the SOC of the first power battery 4 is greater than the upper limit of the low-resistance range, reduce its discharge amount and increase the discharge amount of the second power battery 5.

[0157] When the battery power drops to the predicted lower limit of the low-resistance SOC power of the battery, turn on the driving charging mode until the power rises to the predicted upper limit of the low-resistance SOC power of the battery.

[0158] (2) When the SOC of the second power battery 5 is greater than the upper limit of the low-resistance range, reduce its discharge amount and increase the discharge amount of the first power battery 4.

[0159] When the battery power drops to the predicted lower limit of the low-resistance SOC power of the battery, turn on the driving charging mode until the power rises to the predicted upper limit of the low-resistance SOC power of the battery.

[0160] (3) If the SOC of the second power battery 5 is less than the lower limit of the low-resistance range, increase its charging amount until the battery charge rebounds to the predicted upper limit of the low-resistance SOC of the battery, and reduce the charging amount of the first power battery 4.

[0161] (4) If the SOC of the first power battery 4 is less than the lower limit of the low-resistance range, increase its charging amount until the battery charge rebounds to the predicted upper limit of the low-resistance SOC of the battery, and reduce the charging amount of the second power battery 5.

[0162] (5) When both the first power battery 4 and the second power battery 5 are within the low-resistance SOC range, the output power of the first power battery 4 and the second power battery 5 is dynamically allocated according to the real-time predicted low-resistance range and the current battery charge, as shown in formula (5):

[0163] (4)

[0164] (5)

[0165] Wherein, P 1battery is the output power of the first power battery 4; P 2battery is the output power of the second power battery 5; P2 is the required power of the generator 2 when it acts as a drive motor; P3 is the required power of the first drive motor 3; P6 is the required power of the second drive motor 6; P 22 is the required power of the CPTO drive motor 22; SOC 1_cur is the current charge of the first power battery 4; SOC 1min_limit is the predicted lower limit of the low-resistance range of the first power battery 4; SOC 1max_limit is the predicted upper limit of the low-resistance range of the first power battery 4; SOC 2_cur is the current charge of the second power battery 5; SOC 2min_limit is the predicted lower limit of the low-resistance range of the second power battery 5; SOC2 max_limit is the predicted upper limit of the low-resistance range of the second power battery 5.

[0166] Embodiment 3

[0167] In one embodiment of the present disclosure, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the hybrid tractor power system described above is implemented.

[0168] Embodiment 4

[0169] In one embodiment of the present disclosure, a non-transitory computer-readable storage medium is provided, and the non-transitory computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the hybrid tractor power system described above is implemented.

[0170] Example 5

[0171] In an embodiment of the present disclosure, an electronic device is provided, including: a processor, a memory, and a computer program; wherein, the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device runs, the processor executes the computer program stored in the memory, so that the electronic device executes to implement the hybrid tractor power system described above.

[0172] The present disclosure is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present disclosure. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general purpose computer, a special purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate a device for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or a device for implementing the functions specified in multiple blocks.

[0173] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or steps for implementing the functions specified in multiple blocks.

[0174] Although the specific implementation manners of the present disclosure have been described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present disclosure. Those skilled in the art should understand that, based on the technical solutions of the present disclosure, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present disclosure.

Claims

1. A control method for a power system of a hybrid tractor, characterized in that Select a power path for control according to the current working mode of the tractor, specifically as follows: In the low-load starting mode, select the second power path, and the first drive motor and the second drive motor drive jointly; In the high-load starting mode, select the second power path. On the premise that the first drive motor and the second drive motor drive jointly, judge whether the generator and the CPTO drive motor participate in driving according to the required power; In the low-load traveling mode, select the second power path, and the first drive motor and the second drive motor drive jointly; In the high-load traveling mode, it is divided into two control methods according to the discharge rate of the power battery: When the discharge rate of at least one of the first power battery and the second power battery is greater than the threshold value, select the combination of the first power path and the second power path. On the premise that the engine and the second drive motor drive jointly, judge whether the CPTO drive motor participates in driving according to the required power; When the discharge rates of both the first power battery and the second power battery are not greater than the threshold value, select the second power path. On the premise that the first drive motor and the second drive motor drive jointly, judge whether the generator and the CPTO drive motor participate in driving according to the required power; In the current working mode, when there is an agricultural operation requirement, add a third power path for combined control; Among them, in the control process where the generator is not converted into a drive motor, differential control of the charge and discharge of the first power battery and the second power battery is performed according to the real-time predicted low-resistance interval and the current battery power, specifically as follows: When the power of the current power battery is greater than the upper limit of the low-resistance interval, reduce its discharge amount and increase the discharge amount of the other power battery; When the powers of both the first power battery and the second power battery are within the low-resistance interval, dynamically distribute the output powers of the first power battery and the second power battery; When the power of either the first power battery or the second power battery is less than the lower limit of the low-resistance interval, the engine drives the generator to charge the battery with a power less than the lower limit; When the power of either the first power battery or the second power battery is greater than the upper limit of the low-resistance interval, reduce the output power of the battery greater than the upper limit and increase the output power of the other battery; The calculation method of the output power is as follows: Among them, P 1battery is the output power of the first power battery; P 2battery is the output power of the second power battery; P2 is the required power when the generator acts as a drive motor; P3 is the required power of the first drive motor; P6 is the required power of the second drive motor; P 22 is the required power of the CPTO drive motor; SOC 1_cur is the current power level of the first power battery; SOC 1min_limit is the lower limit of the predicted low-resistance range of the first power battery; SOC 1max_limit is the upper limit of the predicted low-resistance range of the first power battery; SOC 2_cur is the current power level of the second power battery; SOC 2min_limit is the lower limit of the predicted low-resistance range of the second power battery; SOC2 max_limit is the upper limit of the predicted low-resistance range of the second power battery; The power system of the hybrid tractor includes an engine and a CVT transmission; The CVT transmission adopts a structure of two power batteries, two drive motors, and two variable motors. The two power batteries include a first power battery and a second power battery. The two drive motors include a first drive motor and a second drive motor. The two variable motors include a generator and a CPTO drive motor; The tractor provides three types of power paths: The first power path: The engine directly provides power for the wheels through a gear pair; The second power path: The engine drives the generator to charge the two power batteries, and is connected to at least any motor among the two power batteries, the two drive motors, and the two variable motors to provide power for the wheels; The third power path: The engine drives the generator to charge the two power batteries, and the two power batteries provide power for agricultural implements through the CPTO drive motor.

2. The control method of a power system of a hybrid tractor according to claim 1, characterized in that The engine is connected to the generator through a third clutch. The engine is connected to the wheels through a gear pair, a first clutch, and a planetary gear mechanism. The generator is connected to a first power battery and a second power battery through a first control switch and a second control switch respectively.

3. The control method of a power system of a hybrid tractor according to claim 1, characterized in that, The outputs of the first power battery and the second power battery are respectively connected to a first drive motor through a third control switch and a fourth control switch, connected to a second drive motor through a fifth control switch and a sixth control switch, and connected to a CPTO drive motor through a seventh control switch and an eighth control switch. The first drive motor and the second drive motor are respectively connected to the wheels through a gear pair and a planetary gear mechanism. The CPTO drive motor is connected to agricultural implements through a CPTO clutch, and connected to the wheels through a gear pair, a second clutch, and a planetary gear mechanism.

4. The control method of a power system of a hybrid tractor according to claim 1, wherein, The low resistance range is based on battery charge, internal resistance, current, voltage, temperature, charge and discharge rate, and number of cycles, and uses a trained neural network to predict the optimal energy consumption range of the battery, obtaining the upper and lower limits of the low resistance range.

5. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the control method of a hybrid tractor power system according to any one of claims 1-4.

6. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, it implements the control method of a hybrid tractor power system according to any one of claims 1-4.

7. An electronic device, characterized in that, Including: A processor, a memory, and a computer program; wherein, the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device runs, the processor executes the computer program stored in the memory, so that the electronic device executes the control method of a hybrid tractor power system according to any one of claims 1-4.

Images