Planetary gear hybrid system and control method thereof

Abstract

This invention discloses a planetary gear hybrid power system and its control method, relating to the technical field of hybrid power transmission systems for new energy vehicles. It includes an engine, two sets of electric motors, two sets of planetary gear sets, a clutch, a brake, and structural elements disposed between the planetary gear sets for power transmission. The engine and the two sets of electric motors are connected to the two sets of planetary gear sets respectively through different structural elements to form a planetary gear hybrid power transmission system. By controlling the working states of the motors, clutches, and brakes, six driving modes can be achieved: pure electric drive, engine direct drive, power split, parallel drive, brake energy recovery, and parking charging. The use of planetary gear sets, compared to fixed-axis gear arrangements, reduces the use of shift forks, resulting in a compact structure, high integration, clear shifting logic, and greater torque capacity, thus improving the power transmission efficiency of the vehicle's hybrid power system.

Description

Technical Field

[0001] This invention belongs to the technical field of new energy vehicle transmission systems, specifically relating to a planetary gear hybrid power system and its control method. Background Technology

[0002] As a crucial direction for the green transformation of the automotive industry, the powertrain system of new energy vehicles has become one of the core technologies. Among them, hybrid systems, with their advantages in fuel economy, emissions, and power performance, are occupying an increasingly important position in the automotive market and are currently one of the most valuable key components of new energy vehicles. The usage scenarios for new energy vehicles are becoming increasingly complex. Vehicles need high torque output during startup and hill climbing, as well as high-speed power output. However, most mainstream dual-motor hybrid systems in China are single-speed, which cannot meet the demands for improved vehicle economy and power. A few models are equipped with multi-speed hybrid systems, but current multi-speed hybrid systems mostly use a fixed-axis gear transmission arrangement, relying on shift forks for gear changes, which often results in power interruption or shift shock, affecting driving comfort.

[0003] Therefore, it is essential to research and develop new hybrid power systems with more compact structures, higher integration, better shifting comfort, and superior power transmission performance to ensure that vehicles have better adaptability to driving conditions, thereby improving vehicle power and economy. Summary of the Invention

[0004] To address the issues of different operating conditions required for automobiles in various usage scenarios, and the fact that most current mainstream hybrid systems are single-speed, and shifting using a shift fork can cause power interruption or shift shock, affecting driving comfort, the first aspect of this invention proposes a planetary gear hybrid system comprising: an engine 100, a first motor M1, a second motor M2, a first planetary gear set, a second planetary gear set, a clutch, a brake, and structural elements disposed between the planetary gear sets for transmitting power; The first planetary gear set is planetary gear set P1, which includes a first sun gear S1, a first planet carrier H1, and a first ring gear R1; the second planetary gear set is composed of planetary gear set P2 and planetary gear set P3, and includes a second sun gear S2, a third sun gear S3, a second planet carrier H2, and a second ring gear R2. The clutch is clutch C1, the brake includes a first brake B1 and a second brake B2, the first motor M1 includes a stator 10 and a rotor 11, and the second motor M2 includes a stator 20 and a rotor 21. The structural elements include a housing 9, a first structural element 1, a second structural element 2, a third structural element 3, a fourth structural element 4, a fifth structural element 5, and a sixth structural element 6; The first structural element 1 is connected to the first ring gear R1 and the second planetary carrier H2, and is also connected to the clutch C1; the other end of the clutch C1 is connected to the power output shaft of the engine 100, and a shock absorber can also be installed between the clutch C1 and the engine 100; one end of the second structural element 2 is connected to the first sun gear S1, and the other end is connected to the rotor 11 of the first motor M1; one end of the third structural element 3 is connected to the third sun gear S3, and the other end is connected to the rotor 21 of the second motor M2; one end of the fourth structural element 4 is connected to the second sun gear S2, and the other end is connected to the first brake B1; one end of the fifth structural element 5 is connected to the second planetary carrier H2, and the other end is connected to the second brake B2; one end of the sixth structural element 6 is connected to the first planetary carrier H1, and the other end is connected to the second ring gear R2.

[0005] Furthermore, each planetary gear set is completely symmetrical with respect to the rotation center, the power output shaft of the engine 100, the first motor M1, and the second motor M2 are mounted on the same axis, and the stator 10 of the first motor M1 and the stator 20 of the second motor M2 are both fixedly connected to the housing 9.

[0006] Furthermore, the second planetary gear set also includes planetary gear X2 and planetary gear X3, which are mounted on the same planetary carrier. Planetary gear X2 meshes with planetary gear X3, the second sun gear S2, and the second ring gear R2, respectively. Planetary gear X3 meshes with planetary gear X2 and the third sun gear S3, respectively. Planetary gear set P2 and planetary gear set P3 share the same planet carrier, that is, the second planet carrier H2 serves as the planet carrier of the composite planetary gear set; planetary gear set P2 and planetary gear set P3 share the same gear ring, that is, the second gear ring R2 serves as the gear ring of the composite planetary gear set. The first brake B1 is connected to the housing 9 at one end and to the fourth structural element 4 at the other end; the second brake B2 is connected to the housing 9 at one end and to the fifth structural element 5 at the other end.

[0007] Furthermore, the second structural element 2 is designed as a hollow shaft through which the first structural element 1 passes; it is understood that this structural design, through a reasonable layout, further enhances the overall compactness of the system.

[0008] Furthermore, multiple planetary gears X1 are typically evenly distributed around the first sun gear S1; multiple planetary gears X2 and X3 are evenly distributed around the second sun gear S2 and the third sun gear S3, respectively.

[0009] Furthermore, both the first motor M1 and the second motor M2 are connected to the controller; the hybrid power system also includes a battery, a motor driver, etc., and the battery is connected to the motor driver, the first motor M1 and the second motor M2, which is the same as the existing dual-motor hybrid power system.

[0010] The second aspect of this application discloses a control method for a planetary gear hybrid power system. The control method is used to control the aforementioned hybrid power system. The control method controls the operating states of the engine 100, clutch C1, brake B1, brake B2, first motor M1, and second motor M2, enabling the hybrid power system to switch between pure electric mode, engine direct drive mode, power split mode, parallel drive mode, brake energy recovery mode, and parking charging mode.

[0011] Furthermore, controlling the hybrid power system to switch to pure electric drive mode, the method includes: the engine 100 stopping operation. When combined with the second brake B2, the first motor M1 is driven and the second motor M2 is not working, the hybrid power system has a pure electric first gear; With the second brake B2 engaged, the first motor M1 is not working, and the second motor M2 is driven, thus the hybrid power system has two pure electric modes. Combined with the first brake B1, the first motor M1 is driven, and the second motor M2 is not working, the hybrid power system has three pure electric speeds; With the first brake B1 engaged, the first motor M1 is not in operation, and the second motor M2 is driven, thus the hybrid power system has four pure electric gears.

[0012] Furthermore, controlling the hybrid power system to switch to engine direct drive mode, the method includes: starting and operating the engine 100. Engaging clutch C1, by controlling the speed of the second motor M2 to zero, thereby making the speed of the third sun gear S3 to zero, the hybrid power system has engine direct drive first gear; Engaging clutch C1, by controlling the speed of the first motor M1 to zero, thereby reducing the rotational speed of the first sun gear S1 to zero, the hybrid power system has a direct-drive two-speed engine. With clutch C1 and first brake B1 engaged, the power output from engine 100 is transmitted to the sixth structural element 6 via the second planetary gear set, and the hybrid power system has a direct-drive three-speed engine.

[0013] Furthermore, controlling the hybrid power system to switch to power split mode includes: starting the engine 100, engaging the clutch C1, and transmitting the power output of the engine 100 to the first ring gear R1 and the second planetary carrier H2. This can be achieved by controlling the first motor M1 to generate electricity and the second motor M2 to drive it; or by controlling the second motor M2 to generate electricity and the first motor M1 to drive it.

[0014] Furthermore, the hybrid power system switches to parallel drive mode, the method including: engine 100 starts working. When the clutch C1 is engaged, the first motor M1 is driven, and the second motor M2 is not working. The hybrid power system has a parallel drive gear. When the clutch C1 is engaged, the first motor M1 is not working, and the second motor M2 is driven, so the hybrid power system has two parallel drive gears.

[0015] Furthermore, the hybrid power system is controlled to switch to the braking energy recovery mode. The method includes: the engine 100 stops working, and in conjunction with the second brake B2, the rotational torque is transmitted to the first planetary carrier H1 and the second ring gear R2 through the sixth structural element 6. The first sun gear S1 and the third sun gear S3 rotate, and the first motor M1 and the second motor M2 both rotate to generate electricity.

[0016] Furthermore, controlling the hybrid system to switch to parking charging mode, the method includes: it can be understood that when parking, the sixth structural element 6 rotates to zero, the engine 100 starts working, and the clutch C1 is engaged. The power output by the engine 100 is transmitted to the first ring gear R1 and the second planetary carrier H2, the first sun gear S1 and the third sun gear S3 rotate, and the first motor M1 and the second motor M2 both rotate to generate electricity.

[0017] The planetary gear hybrid power system and its control method provided by the present invention, as described above, have the following beneficial effects: 1. The planetary gear hybrid power system and its control method proposed in this invention adopt planetary gear set transmission. When switching working states, the working state of the planetary gear set is changed to reduce the use of brakes and clutches. The shifting operation can adapt to different vehicle use scenarios and has superior power transmission performance. Compared with shift forks, it has a compact structure, higher integration, better shifting comfort, larger torque capacity, clear shifting logic, simple control, can effectively avoid problems such as gear grinding during shifting, and does not require a special shifting control mechanism to operate shift forks.

[0018] 2. This planetary gear hybrid power system employs a dual-motor structure, enabling it to drive or generate electricity using the motors. The motors boast high power utilization, excellent acceleration performance, and an optimized transmission layout. Furthermore, it can operate independently or simultaneously, allowing for direct engine drive, pure electric operation, power splitting, or parallel drive, thus enhancing the flexibility of power source selection and increasing output power in hybrid driving mode to meet power demands.

[0019] 3. This planetary gear hybrid system controls the planetary gear set or the electric motor to change gears when the engine is in direct drive, so that the engine can maintain a fuel-efficient operating condition when the vehicle speed is relatively high, thereby reducing the engine's fuel consumption. Attached image description: To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly introduced below. The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] in: Figure 1 This is a schematic diagram of the planetary gear hybrid power system of the present invention.

[0021] Figure 2 This is a schematic diagram showing the relationship between the planetary gear sets in the planetary gear hybrid power system of the present invention.

[0022] in: 1-6 are six structural components, C1 is a clutch, B1-B2 are two brakes, P1 is a single-stage planetary gear set, and P2 and P3 are two single-stage planetary gear sets that make up the second planetary gear set.

[0023] R1 is the ring gear of P1, H1 is the planet carrier of P1, S1 is the sun gear of P1, R2 is the shared ring gear of P2 and P3, H2 is the shared planet carrier of P2 and P3, S2 is the sun gear of P2, S3 is the sun gear of P3, X2 is the planetary gear of P2, X3 is the planetary gear of P3, 10 is the stator of the first motor M1, 11 is the rotor of the first motor M1, 20 is the stator of the second motor M2, and 21 is the rotor of the second motor M2. Detailed implementation method: The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more; words such as "set" and "connect" should be interpreted broadly unless otherwise explicitly defined. It is understandable that some well-known structures and their descriptions may be omitted in the drawings for those skilled in the art, and this should not be construed as a limitation of the present invention. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0024] The housing 9 described herein remains stationary. The first motor M1 includes a stator 10 and a rotor 11, and the second motor M2 includes a stator 20 and a rotor 21. In the engine direct drive mode, the first motor M1 and the second motor M2 are locked, meaning the motor rotor speed is zero. Controlling the motor speed to zero is a well-known technique in electrical control engineering and is not the focus of this invention; it will not be described further below. In this hybrid power system, each planetary gear set is completely symmetrical with respect to the center of rotation. Figure 1 and Figure 2 The lower half of the center of rotation is omitted and will not be explained further in the following description.

[0025] Example: Please refer to Table 1. Figure 1 and Figure 2 According to a first aspect of the present invention, a planetary gear hybrid power system includes: an engine 100, a first motor M1, a second motor M2, a first planetary gear set, a second planetary gear set, a clutch, a brake, and structural elements disposed between the planetary gear sets for transmitting power; the first planetary gear set is planetary gear set P1 including a first sun gear S1, a first planet carrier H1, and a first ring gear R1; the second planetary gear set is composed of planetary gear set P2 and planetary gear set P3, and the second planetary gear set includes a second sun gear S2, a third sun gear S3, a second planet carrier H2, and a second ring gear R2; The clutch is clutch C1, the brake includes a first brake B1 and a second brake B2, the first motor M1 includes a stator 10 and a rotor 11, the second motor M2 includes a stator 20 and a rotor 21; the structural elements include a housing 9, a first structural element 1, a second structural element 2, a third structural element 3, a fourth structural element 4, a fifth structural element 5, and a sixth structural element 6. The first structural element 1 connects to the first ring gear R1 and the second planetary carrier H2, and is also connected to the clutch C1. This can be understood as a fixed connection between the first ring gear R1 and the second planetary carrier H2. The other end of the clutch C1 is connected to the power output shaft of the engine 100. The second structural element 2 connects to the first sun gear S1 at one end and to the rotor 11 of the first motor M1 at the other end. This can be understood as a fixed connection between the rotor 11 of the first motor M1 and the first sun gear S1. The third structural element 3 connects to the third sun gear S3 at one end and to the rotor 21 of the second motor M2 at the other end. This can be understood as a fixed connection between the rotor 21 of the second motor M2 and the third sun gear S3. The fourth structural element 4 connects to the second sun gear S2 at one end and to the first brake B1 at the other end. The fifth structural element 5 connects to the second planetary carrier H2 at one end and to the second brake B2 at the other end. The sixth structural element 6 connects to the first planetary carrier H1 at one end and to the second ring gear R2 at the other end. This can be understood as a fixed connection between the first planetary carrier H1 and the second ring gear R2.

[0026] The planetary gear hybrid power system of the present invention can realize multiple power modes, mainly including pure electric mode, engine direct drive mode, power split mode, parallel drive mode, brake energy recovery mode, and parking charging mode. The specific power modes are as follows: Please refer to Table 1. Figure 1 and Figure 2 It is understood that the engine 100 does not work in any of the gears of pure electric drive, and the clutch C1 is disengaged to prevent the engine 100 from being dragged backward.

[0027] Pure electric first gear: Combined with the second brake B2 and the first motor M1 for drive.

[0028] Combined with the second brake B2, the second planetary carrier H2 is fixedly connected to the housing 9. The second planetary carrier H2, the first structural element 1, and the first gear ring R1 rotate at zero speed. The first motor M1 drives them. The first sun gear S1 rotates at the same speed as the first motor M1. The first motor M1 transmits power sequentially to the second structural element 2, the first sun gear S1, the first planetary carrier H1, and the sixth structural element 6 to output power to the outside.

[0029] Pure electric second gear: Driven by the second brake B2 and the second motor M2.

[0030] Combined with the second brake B2, the second planetary carrier H2 is fixedly connected to the housing 9. The second planetary carrier H2 rotates at zero speed and is driven by the second motor M2. The third sun gear S3 rotates at the same speed as the second motor M2. The second motor M2 transmits power sequentially to the third structural element 3, the third sun gear S3, the planetary gear X3, the planetary gear X2, the second gear ring R2, and the sixth structural element 6 to output power to the outside.

[0031] Pure electric three-speed: driven by the first brake B1 and the first motor M1.

[0032] Combined with the first brake B1, the second sun gear S2 is fixedly connected to the housing 9, and the rotational speed of the second sun gear S2 is zero; driven by the first motor M1, the first sun gear S1 and the first motor M1 rotate at the same speed, and the first motor M1 transmits power sequentially to the second structural element 2, the first sun gear S1, the planetary gear X1, the first ring gear R1, the first structural element 1, the second planetary carrier H2, the second ring gear R2, and the sixth structural element 6 to output power to the outside.

[0033] Pure electric four-speed: driven by the first brake B1 and the second motor M2. Combined with brake B1, the second sun gear S2 is fixedly connected to the housing 9, and the rotational speed of the second sun gear S2 is zero; the second motor M2 drives the second sun gear S3, and the second motor M2 rotates at the same speed as the third sun gear S3; the second motor M2 transmits power sequentially to the third structural element 3, the third sun gear S3, the planetary gear X3, and the planetary gear X2, and the third sun gear S3, the planetary gear X3, and the planetary gear X2 transmit power to the second ring gear R2 through the shared planet carrier H2, and the sixth structural element 6 outputs power to the outside.

[0034] Engine direct drive first gear: Engage clutch C1 to control the second motor M2 to zero speed. Engaging clutch C1, the second planetary carrier H2 is connected to the engine 100 and rotates at the same speed, controlling the second motor M2 to rotate at zero speed. The third sun gear S3 rotates at the same speed as the second motor M2, also at zero speed. The engine 100 transmits power to clutch C1, the first structural element 1, the second planetary carrier H2, the second ring gear R2, and the sixth structural element 6 to output power to the outside.

[0035] Engine direct drive, second gear: Engage clutch C1 to control the speed of the first motor M1 to zero. Engaging clutch C1, the first gear ring R1 is connected to the engine 100 and rotates at the same speed, controlling the speed of the first motor M1 to zero. The first sun gear S1 rotates at the same speed as the first motor M1, which is also zero. The engine 100 transmits power to clutch C1, the first structural element 1, the first gear ring R1, the first planetary carrier H1, and the sixth structural element 6 to output power to the outside.

[0036] Engine direct drive third gear: Engage clutch C1 and first brake B1 When the first brake B1 is engaged, the second sun gear S2 is fixedly connected to the housing 9, and the second sun gear S2 rotates at zero. When the clutch C1 is engaged, the first structural element 1 is connected to the engine 100 and rotates at the same speed. The engine 100 transmits power to the clutch C1, the first structural element 1, the second planetary carrier H2, the planetary gear X2, the second ring gear R2, and the sixth structural element 6 to output power to the outside.

[0037] Power split mode: Engage clutch C1 When the clutch C1, first ring gear R1, and second planetary carrier H2 are connected to the engine 100 at the same rotational speed, the engine 100 transmits power to the clutch C1, first structural element 1, first ring gear R1, and second planetary carrier H2. The engine 100 can drive the first motor M1 to rotate, with the first motor M1 acting as a generator and the second motor M2 acting as a drive motor; or the engine 100 can drive the second motor M2 to rotate, with the second motor M2 acting as a generator and the first motor M1 acting as a drive motor. In this mode, based on the vehicle's output power requirements, the coordinated operation of the engine 100, first motor M1, second motor M2, and either the first or second planetary carrier ensures the engine always operates within a high-efficiency range, thereby guaranteeing fuel economy and improving the overall power and economy of the vehicle. The engine's good fuel economy helps reduce battery usage, extends battery life, and thus improves the overall economic efficiency of the vehicle.

[0038] Parallel drive mode, first gear: Engaging clutch C1, the first motor M1 drives the system. When the first gear ring R1 of clutch C1 is connected to the engine 100 and rotates at the same speed, the engine 100 transmits power to clutch C1, first structural element 1, and first gear ring R1; at the same time, the first motor M1 drives and transmits power to the second structural element 2 and the first sun gear S1; the two power streams converge on the first planetary carrier H1 and are then transmitted to the sixth structural element 6 for external power output.

[0039] Parallel drive mode, second gear: Engages clutch C1, second motor M2 drives the system. When the clutch C1 and the second planetary carrier H2 are connected to the engine 100 and rotate at the same speed, the engine 100 transmits power to the clutch C1, the first structural element 1, and the second planetary carrier H2; at the same time, the second motor M2 drives the power to the third structural element 3 and the third sun gear S3. The two power streams converge on the second planetary carrier H2 and are then transmitted to the second ring gear R2 and the sixth structural element 6 for external power output.

[0040] Braking energy recovery mode: When the vehicle brakes in each of the aforementioned modes, the engine 100 does not operate, and the clutch C1 disengages to prevent the engine 100 from being dragged backwards; the second brake B2 engages, and the rotation speeds of the second planetary carrier H2, the first structural element 1, and the first ring gear R1 are zero. The first motor M1 and the second motor M2 are subjected to reverse torque and rotate to generate electricity, and the hybrid power system enters the braking energy recovery mode. At this time, the braking energy recovery route is divided into two paths: one path is where the sixth structural element 6, the first planetary carrier H1, the planetary gear X1, the first sun gear S1, the second structural element 2, and the first motor M1 rotate to generate electricity; the other path is where the sixth structural element 6, the second ring gear R2, the planetary gear X2, the planetary gear X3, the third structural element 3, and the second motor M2 rotate to generate electricity. This mode is applied to vehicle braking energy recovery.

[0041] Parking charging mode: Engine starts working at 100 rpm, engaging clutch C1. It is understandable that when entering the parking charging mode, the parking mechanism locks the wheels, thus reducing the rotation speed of the sixth structural element 6 to zero. This, combined with the clutch C1, the first ring gear R1, and the second planetary carrier H2, connects the engine 100 to the power supply at the same rotation speed. The engine 100 transmits power sequentially to the clutch C1 and the first structural element 1, with the power split into two paths: one path transmits power to the first ring gear R1, planetary gear X1, the first sun gear S1, and the second structural element 2, with the first motor M1 acting as a generator; the other path transmits power to the second planetary carrier H2, planetary gear X2, planetary gear X3, the third sun gear S3, and the third structural element 3, with the second motor M2 acting as a generator.

[0042] Reverse gear: The reverse gear has the following two implementation forms. 1. Combined with brake B2, the first motor M1 reverses and drives, and the power is sequentially transmitted to the second structural element 2, the first sun gear S1, the first planetary carrier H1, and the sixth structural element 6 to output power outward in the opposite direction; 2. Combined with brake B2, the second motor M2 reverses and drives, and the power is sequentially transmitted to the third structural element 3, the third sun gear S3, the planetary gear X3, the planetary gear X2, the second gear ring R2, and the sixth structural element 6 to output power in the opposite direction.

[0043] Of course, the relationship between gear and road conditions is not limited to the above. Different gear distribution modes can be arranged for different road conditions based on fuel consumption and power. Here, we will not limit the relationship between gear and road conditions.

[0044] Table 1 is the gear control logic diagram for this planetary gear hybrid system. Table 1:

[0045] Note: In the table, "√" indicates that the clutch or brake is engaged, and no "√" indicates that it is not engaged.

[0046] The embodiments described above are some, but not all, of the embodiments of the present invention; all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

Claims

1. A planetary gear hybrid power system, characterized in that, It includes an engine (100), a first motor M1, a second motor M2, a first planetary gear set, a second planetary gear set, a clutch, a brake, and structural elements disposed between the planetary gear sets for transmitting power; The first planetary gear set is planetary gear set P1, which includes a first sun gear S1, a first planet carrier H1, and a first gear ring R1; The second planetary gear set is composed of planetary gear set P2 and planetary gear set P3. The second planetary gear set includes a second sun gear S2, a third sun gear S3, a second planet carrier H2, and a second ring gear R2. The clutch is clutch C1, the brake includes a first brake B1 and a second brake B2, the first motor M1 includes a stator (10) and a rotor (11), and the second motor M2 includes a stator (20) and a rotor (21). The structural elements include a housing (9), a first structural element (1), a second structural element (2), a third structural element (3), a fourth structural element (4), a fifth structural element (5), and a sixth structural element (6). The first structural element (1) is connected to the first ring gear R1 and the second planetary carrier H2, and is also connected to the clutch C1; the other end of the clutch C1 is connected to the power output shaft of the engine (100); the second structural element (2) is connected to the first sun gear S1 at one end and to the rotor (11) of the first motor M1 at the other end; the third structural element (3) is connected to the third sun gear S3 at one end and to the rotor (21) of the second motor M2 at the other end; the fourth structural element (4) is connected to the second sun gear S2 at one end and to the first brake B1 at the other end; the fifth structural element (5) is connected to the second planetary carrier H2 at one end and to the second brake B2 at the other end; the sixth structural element (6) is connected to the first planetary carrier H1 at one end and to the second ring gear R2 at the other end. Each planetary gear set is completely symmetrical with respect to the rotation center. The power output shaft of the engine (100), the first motor M1, and the second motor M2 are mounted on the same axis. The stator (10) of the first motor M1 and the stator (20) of the second motor M2 are both fixedly connected to the housing (9). The second planetary gear set also includes planetary gear X2 and planetary gear X3, which are mounted on the same planetary carrier. Planetary gear X2 meshes with planetary gear X3, the second sun gear S2, and the second ring gear R2, respectively. Planetary gear X3 meshes with planetary gear X2 and the third sun gear S3, respectively. Planetary gear set P2 and planetary gear set P3 share the same planet carrier, that is, the second planet carrier H2 serves as the planet carrier of the composite planetary gear set; planetary gear set P2 and planetary gear set P3 share the same gear ring, that is, the second gear ring R2 serves as the gear ring of the composite planetary gear set. The first brake B1 is connected to the housing (9) at one end and to the fourth structural element (4) at the other end; the second brake B2 is connected to the housing (9) at one end and to the fifth structural element (5) at the other end. A shock absorber disc is installed between the clutch (C1) and the engine (100); The second structural element (2) is designed as a hollow shaft so that the first structural element (1) can pass through it; The control method of the planetary gear hybrid system controls the hybrid system to switch between pure electric drive mode, engine direct drive mode, power split mode, parallel drive mode, brake energy recovery mode and parking charging mode by controlling the working state of the engine (100), clutch, brake, first motor M1 and second motor M2. The method of controlling the hybrid system to switch to pure electric drive mode includes: the engine (100) stops working, the first motor M1 drives in conjunction with the second brake B2, the second motor M2 does not work, and the hybrid system has a pure electric first gear; With the second brake B2 engaged, the first motor M1 is not working, and the second motor M2 is driven, thus the hybrid power system has two pure electric modes. Combined with the first brake B1, the first motor M1 is driven, and the second motor M2 is not working, the hybrid power system has three pure electric speeds; With the first brake B1 engaged, the first motor M1 is not working, and the second motor M2 is driven, thus the hybrid power system has four pure electric speeds. The method of controlling the hybrid system to switch to engine direct drive mode includes: starting the engine (100), engaging the clutch C1, and controlling the speed of the second motor M2 to zero, thereby causing the speed of the third sun gear S3 to zero; the hybrid system has an engine direct drive first gear; Engaging clutch C1, the speed of the first motor M1 is controlled to zero, thereby causing the speed of the first sun gear S1 to zero; the hybrid power system has two-speed direct drive engine. With clutch C1 and first brake B1 engaged, the power output of engine (100) is transmitted to the sixth structural element (6) via the second planetary gear set. The hybrid power system has engine direct drive three gears. The method of controlling the hybrid power system to switch to power split mode includes: starting the engine (100) and engaging the clutch C1, so that the power output by the engine (100) is transmitted to the first ring gear R1 and the second planetary carrier H2; The generator can be controlled to generate electricity and the second motor M2 can drive it; or the generator can be controlled to generate electricity and the first motor M1 can drive it. The hybrid system switches to parallel drive mode, the method of which includes: the engine (100) starts working, the clutch C1 engages, the first motor M1 drives, the second motor M2 does not work, and the hybrid system has a parallel drive first gear mode. When the clutch C1 is engaged, the first motor M1 is not working, and the second motor M2 is driven. The hybrid power system has a parallel drive two-speed mode. The method of controlling the hybrid power system to switch to the braking energy recovery mode includes: the engine (100) stops working, and in conjunction with the second brake B2, the rotational torque is transmitted to the first planetary carrier H1 and the second ring gear R2 through the sixth structural element (6), the first sun gear S1 and the third sun gear S3 rotate, and the first motor M1 and the second motor M2 both rotate to generate electricity; The method of controlling the hybrid power system to switch to parking charging mode includes: when parking, the speed of the sixth structural element (6) is zero, the engine (100) starts working, and the clutch C1 is engaged. The power output of the engine (100) is transmitted to the first ring gear R1 and the second planetary carrier H2. The first sun gear S1 and the third sun gear S3 rotate, and the first motor M1 and the second motor M2 both rotate to generate electricity.

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