Series-parallel hybrid power system based on P1P3 and control method

Abstract

The invention provides a P1P3-based series-parallel hybrid power system and a control method, and belongs to the technical field of hybrid electric vehicle power transmission, and the system comprises a generator which is connected with the output end of an engine and is used for converting mechanical energy of the engine into electric energy; the driving motor is used for outputting torque; the speed change mechanism comprises a power input shaft, a power output shaft, at least four planet rows arranged between the power input shaft and the power output shaft and a mode switching mechanism. Power of the generator and the driving motor is coupled through different planet rows in the speed change mechanism and is output through a power output shaft; the mode switching mechanism is used for switching working modes of the speed change mechanism so as to at least realize a pure electric driving mode, an engine direct driving mode and a hybrid driving mode; the control unit is used for controlling operation of the mode switching mechanism, the engine, the generator and the driving motor according to the vehicle operation state. The driving smoothness is improved, the power distribution is optimized, the system complexity is reduced, and the endurance mileage is increased.

Description

Technical Field

[0001] This application belongs to the field of hybrid electric vehicle powertrain technology, specifically relating to a series-parallel hybrid system and control method based on P1P3. Background Technology

[0002] Hybrid electric vehicles (HEVs) play a crucial role in achieving energy conservation and emission reduction. The power systems of HEVs are mainly classified into three types: series, parallel, and series-parallel. In a series hybrid system, the engine only drives a generator to produce electricity, which then drives an electric motor to propel the vehicle. While gear shifting is smooth, the multiple energy conversions reduce transmission efficiency, especially at high speeds where energy loss is significant. In a parallel hybrid system, the engine and electric motor can drive the vehicle simultaneously or individually. The structure is relatively simple, but power interruptions often occur during gear shifts, affecting driving smoothness and ride comfort. Series-parallel systems (such as power-split systems) can balance power and economy, but their complex mechanisms, numerous planetary gear sets, clutches, brakes, and other components result in high manufacturing costs. The control system relies on multiple sensors, leading to a higher failure rate and greater maintenance difficulty.

[0003] To address the aforementioned issues, hybrid electric vehicles typically employ a P1P3 architecture. This architecture integrates the generator (P1) at the engine crankshaft and the drive motor (P3) at the drive shaft, creating a parallel-parallel layout that balances the smoothness of series mode with the efficient direct-drive capability of parallel mode, achieving multiple operating modes through power splitting. However, existing P1P3 systems often rely on multiple clutches and brakes for mode switching, resulting in power interruptions or shocks during gear shifts, affecting driving smoothness. Furthermore, the system has a large number of planetary gear sets and actuators, leading to complex structures and high costs. In pure electric mode, the system may still drive some unnecessary rotating parts, resulting in significant parasitic losses, reduced efficiency, and limited range.

[0004] Therefore, there is an urgent need for a hybrid system that can improve shift smoothness, has high pure electric efficiency, simple structure, flexible control and low cost, while maintaining the advantages of the P1P3 architecture, so as to meet the needs of different vehicle models and various driving scenarios. Summary of the Invention

[0005] In a first aspect, embodiments of this application provide a series-parallel hybrid system based on P1P3, including an engine, a generator, a drive motor, a transmission mechanism, and a control unit; The generator is connected to the output of the engine to convert the engine's mechanical energy into electrical energy; The drive motor is used to output torque to drive the vehicle; The transmission mechanism includes a power input shaft, a power output shaft, and at least four planetary gear sets and a mode switching mechanism disposed between the power input shaft and the power output shaft; The power of the generator and the drive motor is coupled through different planetary gear sets in the transmission mechanism and output through the power output shaft; The mode switching mechanism is used to switch the working mode of the transmission mechanism to achieve at least pure electric drive mode, engine direct drive mode and hybrid drive mode; The control unit is used to control the mode switching mechanism and the operation of the engine, generator and drive motor according to the vehicle's operating status.

[0006] Furthermore, the transmission mechanism includes a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set.

[0007] Furthermore, the generator is directly connected to the engine, and is connected to the first planetary gear set in sequence through a clutch, a first synchronizer, and so on. The first synchronizer has a first engagement position and a second engagement position; when in the first engagement position, the first sun gear of the first planetary set is fixed; when in the second engagement position, the first planet carrier of the first planetary set is engaged with the first sun gear.

[0008] Furthermore, the drive motor is directly connected to the second sun gear of the second planetary gear set, and the second ring gear of the second planetary gear set is fixed; The second planetary carrier of the second planetary row is directly connected to the third sun wheel of the third planetary row.

[0009] Furthermore, the transmission mechanism also includes a second synchronizer, which is disposed between the second planetary gear set and the third planetary gear set; The second synchronizer has a third engagement position and a fourth engagement position; When in the third engagement position, the third gear of the third planetary set is fixed; When in the fourth engagement position, the second planet carrier of the second planetary set engages with the third gear of the third planetary set.

[0010] Furthermore, the first ring gear of the first planetary gear set is connected to the power output shaft and to the third planet carrier of the third planetary gear set.

[0011] Secondly, embodiments of this application also provide a control method based on the system described in the first aspect, comprising the following steps: S1. Obtain vehicle operating parameters; the vehicle operating parameters include battery SOC, vehicle speed, vehicle load, and driving mode request; S2. Based on vehicle operating parameters, determine the target operating mode of the series-parallel hybrid system; the target operating mode includes pure electric drive mode, engine direct drive mode, or hybrid drive mode; S3. Generate control commands corresponding to the target working mode and send them to the mode switching mechanism to control the first synchronizer and / or the second synchronizer to switch to the target engagement position, so that the transmission mechanism enters the transmission state that matches the target working mode. S4. Based on the target operating mode, coordinate and control the torque and speed of the engine, generator, and drive motor to achieve the target power output.

[0012] Furthermore, the specific steps for determining the target operating mode in step S2 include: If the battery SOC is higher than the first preset SOC threshold and the vehicle load is lower than the first preset load threshold, then the target operating mode is determined to be the pure electric drive mode. If the battery SOC is lower than the second preset SOC threshold, or the vehicle speed is higher than the first preset vehicle speed threshold, or the vehicle load is higher than the second preset load threshold, then the target operating mode is determined to be the hybrid drive mode. Among them, the hybrid drive mode includes the hybrid operating condition in which the engine and the drive motor drive together, and the hybrid direct drive operating condition in which the engine power is converted into electrical energy by the generator and then directly supplied to the drive motor.

[0013] Furthermore, in step S3, when the target operating mode switches from pure electric drive mode to hybrid drive mode, the control command controls the first synchronizer to switch from the first engagement position to the second engagement position, so as to release the fixation of the first sun gear and engage the first planetary carrier with the first sun gear, so that the power of the engine is connected to the transmission path of the transmission mechanism. When the target operating mode involves switching the drive motor gears, the control command controls the second synchronizer to switch between the third and fourth engagement positions to change the transmission ratio from the drive motor to the power output shaft.

[0014] Furthermore, in step S4, the specific steps of coordination control, based on different target operating modes, are as follows: In pure electric drive mode, the engine is stopped, the drive motor is controlled to output torque according to the accelerator pedal opening and vehicle speed, and the drive motor is controlled to start with the transmission ratio corresponding to the second synchronizer being in the fourth engagement position. In hybrid drive mode, the engine output power is allocated according to the vehicle's power demand and battery SOC, based on a preset energy management strategy. Part of the power is directly output through the transmission mechanism, and the other part drives the generator to generate electricity. The generated energy, together with the power battery's electrical energy, or separately, supplies the drive motor. When a braking request is detected, the drive motor is controlled to enter the power generation mode to provide braking torque and the recovered electrical energy is stored in the power battery. When the vehicle is stationary and the battery SOC is below the preset power generation threshold, the engine is started and the drive motor is controlled to provide anti-drag torque, so that the engine drives the generator to generate electricity in the parking vehicle.

[0015] As can be seen from the above technical solutions, this application has the following advantages: The series-parallel hybrid system and control method based on P1P3 provided in this application achieves uninterrupted gear shifting through precise control of the synchronizer, improving driving smoothness and ride comfort; optimizes power coupling and distribution strategies, reducing energy conversion losses, especially in pure electric mode, improving system efficiency and extending driving range; reduces the number of parts by adopting a simplified planetary gear set and synchronizer structure, lowering manufacturing costs and maintenance difficulty; the gears of the engine and drive motor can be independently adjusted to adapt to various driving scenarios, improving the overall flexibility and adaptability of the system; through intelligent switching of multiple operating modes (pure electric, hybrid, super hybrid, etc.), stable and efficient power output is ensured under different operating conditions; and by rationally distributing power in different modes, fuel consumption and emissions are reduced, achieving energy conservation and emission reduction. Attached Figure Description

[0016] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the series-parallel hybrid system based on P1P3 according to the present invention.

[0018] Figure 2 This is a flowchart illustrating the series-parallel hybrid system control method based on P1P3 of the present invention.

[0019] Among them, 100 is the engine; P1 is the generator; P3 is the drive motor; X1 is the first planetary gear set; X2 is the second planetary gear set; X3 is the third planetary gear set; X4 is the fourth planetary gear set; CX is the clutch; C1 is the first synchronizer; C2 is the second synchronizer; C1-M1 is the first engagement position; C1-M2 is the second engagement position; C2-M1 is the third engagement position; C2-M2 is the fourth engagement position; XC1 is the first planetary carrier; XC2 is the second planetary carrier; XC3 is the third planetary carrier; XC4 is the fourth planetary carrier; S1 is the first sun gear; S2 is the second sun gear; S3 is the third sun gear; S4 is the fourth sun gear; R1 is the first ring gear; R2 is the second ring gear; R3 is the third ring gear; R4 is the fourth ring gear. Detailed Implementation

[0020] The various embodiments of this disclosure will be described more fully in the following detailed description of a P1P3-based series-parallel hybrid system. This disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of this disclosure to the specific embodiments disclosed herein, but rather this disclosure should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of this disclosure.

[0021] For example, hybrid electric vehicles (HEVs) make significant contributions to energy conservation and emission reduction. Their power systems are mainly divided into three types: series, parallel, and series-parallel. In a series hybrid system, the engine is only used to drive a generator to produce electricity, which is then used by the electric motor to drive the vehicle. Although gear shifting is smooth, multiple energy conversions lead to reduced transmission efficiency, especially at high speeds where energy loss is significant. In a parallel hybrid system, the engine and electric motor can drive the vehicle individually or together. The structure is relatively simple, but power interruptions are prone to occur during gear shifts, affecting driving smoothness and comfort. Series-parallel systems (such as power-split systems) balance power and economy, but their complex mechanisms include numerous planetary gear sets, clutches, and brakes, resulting in high manufacturing costs. The control system relies on multi-sensor coordination, leading to a high failure rate and difficult maintenance.

[0022] To address these issues, hybrid electric vehicles often employ a P1P3 architecture, integrating the generator (P1) at the engine crankshaft and the drive motor (P3) at the drive shaft in a parallel configuration. This architecture combines the high smoothness of a series mode with the efficient direct-drive capability of a parallel mode, achieving multiple operating modes through power splitting. However, existing P1P3 systems typically rely on multiple clutches and brakes for mode switching, resulting in power interruptions or shocks during gear shifts, affecting driving smoothness; the planetary gear sets and actuators are numerous, complex in structure, and costly; furthermore, in pure electric mode, some rotating parts are still driven, leading to significant parasitic losses, reduced efficiency, and limited driving range.

[0023] Therefore, there is an urgent need to develop a hybrid system that can improve shift smoothness, increase pure electric efficiency, simplify structure, reduce control complexity, and lower cost, while retaining the advantages of the P1P3 architecture, in order to meet the needs of different vehicle models and diverse driving scenarios.

[0024] To address the aforementioned issues, this embodiment provides a series-parallel hybrid system based on P1P3, which improves driving smoothness, optimizes power output, reduces system complexity and cost, and enhances economy and driving range.

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figure 1 The diagram shown is a schematic of a series-parallel hybrid system based on P1P3 in a specific embodiment. The system includes an engine 100, a generator P1, a drive motor P3, a transmission mechanism, and a control unit. The generator P1 is connected to the output terminal of the engine 100 and is used to convert the mechanical energy of the engine 100 into electrical energy. Drive motor P3 is used to output torque to drive the vehicle; The transmission mechanism includes a power input shaft, a power output shaft, and at least four planetary gear sets and a mode switching mechanism disposed between the power input shaft and the power output shaft; The power of generator P1 and drive motor P3 is coupled through different planetary gear sets in the transmission mechanism and output through the power output shaft; The mode switching mechanism is used to switch the working mode of the transmission mechanism to achieve at least pure electric drive mode, engine direct drive mode and hybrid drive mode; The control unit is used to control the mode switching mechanism and the operation of the engine 100, generator P1 and drive motor P3 according to the vehicle's operating status. It should be noted that engine 100 provides mechanical energy, which is converted into electrical energy or directly drives the vehicle through generator P1, and is the main power source of the system; through synchronizer control, power can be flexibly connected or disconnected in different modes, improving the adaptability of the system; The generator P1 efficiently converts the mechanical energy of the engine 100 into electrical energy to charge the battery or directly supply the drive motor P3, thereby improving the energy utilization efficiency of the system. In hybrid drive mode, it provides electrical energy support to the drive motor P3, enhancing the overall power output capability of the system. The drive motor P3 outputs torque to drive the vehicle and is the main power output component in pure electric mode and hybrid drive mode; it enters the power generation mode during braking to recover energy and store it in the battery, thereby improving the energy recovery efficiency of the system. The transmission mechanism achieves power coupling and distribution between engine 100, generator P1 and drive motor P3 through planetary gear set and synchronizer, optimizing the power output path; it supports multiple working modes, improving the system's flexibility and adaptability; The control unit intelligently switches operating modes according to the vehicle's operating status, coordinates the operation of various components, and improves the overall performance of the system and the user experience; through precise control, it optimizes energy management and power distribution, and improves the system's economy and power.

[0027] This embodiment achieves flexible switching between multiple operating modes through the coordinated operation of engine 100, generator P1, drive motor P3, transmission mechanism and control unit, thereby improving the overall performance and adaptability of the system; it supports multiple modes such as pure electric, engine direct drive and hybrid drive to meet different driving needs and improve the economy and power of the system.

[0028] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, in order to fully illustrate the specific implementation process in this embodiment, another series-parallel hybrid system based on P1P3 is provided, which is suitable for various models such as compact passenger cars and mid-size SUVs. The system includes an engine 100, a generator P1, a drive motor P3, a transmission mechanism, and a control unit. The generator P1 is connected to the output terminal of the engine 100 and is used to convert the mechanical energy of the engine 100 into electrical energy. Drive motor P3 is used to output torque to drive the vehicle; The transmission mechanism includes a power input shaft, a power output shaft, and at least four planetary gear sets and a mode switching mechanism disposed between the power input shaft and the power output shaft; The power of generator P1 and drive motor P3 is coupled through different planetary gear sets in the transmission mechanism and output through the power output shaft; The mode switching mechanism is used to switch the working mode of the transmission mechanism to achieve at least pure electric drive mode, engine direct drive mode and hybrid drive mode; The control unit is used to control the mode switching mechanism and the operation of the engine 100, generator P1 and drive motor P3 according to the vehicle's operating status. The transmission mechanism includes a first planetary gear set X1, a second planetary gear set X2, a third planetary gear set X3, and a fourth planetary gear set X4; The generator P1 is directly connected to the engine 100, and is connected to the first planetary gear X1 in sequence through the clutch CX, the first synchronizer C1; The first synchronizer C1 has a first engagement position C1-M1 and a second engagement position C1-M2; when it is in the first engagement position C1-M1, the first sun gear S1 of the first planetary set X1 is fixed; when it is in the second engagement position C1-M2, the first planet carrier XC1 of the first planetary set X1 engages with the first sun gear S1. The drive motor P3 is directly connected to the second sun gear S2 of the second planetary gear X2, and the second ring gear R2 of the second planetary gear X2 is fixed. The second planetary carrier XC2 of the second planetary row X2 is directly connected to the third sun wheel S3 of the third planetary row X3; The transmission mechanism also includes a second synchronizer C2, which is located between the second planetary gear set X2 and the third planetary gear set X3; The second synchronizer C2 has a third engagement position C2-M1 and a fourth engagement position C2-M2; When in the third engagement position C2-M1, the third gear ring R3 of the third planetary set X3 is fixed; When in the fourth engagement position C2-M2, the second planet carrier XC2 of the second planetary set X2 engages with the third gear ring R3 of the third planetary set X3; The first ring gear R1 of the first planetary gear set X1 is connected to the power output shaft and to the third planet carrier XC3 of the third planetary gear set X3. For example, engine 100 uses a 1.5T turbocharged engine with a maximum output power of 120kW and a peak torque of 250N. m, balancing power and fuel economy; Generator P1 is a permanent magnet synchronous generator with a rated power of 30kW, a maximum speed of 8000rpm, and an efficiency range of 92%-97%, which can efficiently convert the engine's mechanical energy into electrical energy. The P3 drive motor is a high-power-density permanent magnet synchronous drive motor with a rated power of 60kW, a peak power of 120kW, and a peak torque of 300N. m, supports energy recovery in power generation mode; The first planetary gear set X1, the second planetary gear set X2, the third planetary gear set X3, and the fourth planetary gear set X4 all adopt a single-row planetary gear structure with a gear module of 2.5, a tooth width of 20mm, and are made of 20CrMnTi alloy steel, which is carburized and quenched to improve wear resistance and load-bearing capacity. The first planetary gear set X1 has a transmission ratio of 2.8, the second planetary gear set X2 has a transmission ratio of 1.6, the third planetary gear set X3 has a transmission ratio of 2.2, and the fourth planetary gear set X4 has a transmission ratio of 1.8. A wide range of speed changes is achieved through the cooperation of multiple planetary gear sets. The clutch in the mode switching mechanism CX is a dry single-plate clutch with a maximum transmitted torque of 400N. m, engagement time ≤ 0.3s; both the first synchronizer C1 and the second synchronizer C2 are lock-ring type synchronizers, with a synchronization cone angle of 6° and a synchronization capacity of 150N. m ensures smooth and shock-free gear shifting; The control unit uses a TC397 chip with an operating frequency of 300MHz, supports multi-channel CAN FD communication, and can process sensor signals and output control commands in real time. Power input assembly: Generator P1 is directly connected to the front end of engine 100 crankshaft via flange, with coaxiality error ≤0.02mm; Generator P1 output is connected to clutch CX drive plate via spline, clutch CX driven plate is rigidly connected to first synchronizer C1 input via drive shaft, and first synchronizer C1 output is respectively matched with first sun gear S1 and first planetary carrier XC1 of first planetary gear X1; Drive motor end assembly: The output shaft of drive motor P3 is directly connected to the second sun gear S2 of the second planetary gear X2 via a spline. The second ring gear R2 of the second planetary gear X2 is fixed to the gearbox housing with bolts. The second planetary carrier XC2 is rigidly connected to the third sun gear S3 of the third planetary gear X3 via a drive shaft. The drive shaft adopts a hollow shaft structure with an outer diameter of 45mm and an inner diameter of 30mm, balancing strength and lightweight. Synchronizer assembly: The second synchronizer C2 is mounted on the drive shaft between the second planetary gear X2 and the third planetary gear X3. The synchronizer sleeve can slide axially and is adapted to the third gear ring R3 of the third planetary gear X3 and the engagement gear ring of the second planetary carrier XC2, respectively. The first gear ring R1 of the first planetary gear X1 is connected to the power output shaft through a spline and is fixed to the third planetary carrier XC3 of the third planetary gear X3 by bolts to achieve power coupling output. Sensor assembly: Magnetoelectric speed sensors are installed on the engine output shaft, generator shaft, drive motor shaft, and power output shaft, with a measurement accuracy of ±1 rpm; position sensors are installed on the clutch CX, first synchronizer C1, and second synchronizer C2 to monitor the engagement status in real time; the power battery pack is equipped with voltage, current, and temperature sensors with a sampling frequency of 100Hz to provide data support for SOC calculation; In pure electric drive mode: Triggering conditions: The power battery SOC is higher than 60% (first preset SOC threshold), and the vehicle load is lower than 30% (first preset load threshold), such as low-speed driving on urban roads and commuting on smooth roads.

[0029] Mechanism Action: The control unit sends a command to disengage the clutch CX, the first synchronizer C1 switches to the first engagement position C1-M1, and the first sun gear S1 is fixed; the second synchronizer C2 switches to the fourth engagement position C2-M2 first, and the second planetary carrier XC2 engages with the third ring gear R3 of the third planetary gear X3. At this time, the power transmission ratio of the drive motor is 2.1 (calculated by the second planetary gear X2 and the third planetary gear X3), which is suitable for starting acceleration requirements; Power flow: When the engine stops at 100 km / h, the DC power output from the power battery is converted into three-phase AC power by the inverter to supply the drive motor P3. The output torque of the drive motor P3 is transmitted sequentially through the second sun gear S2, the second planetary carrier XC2, the third sun gear S3, and the third planetary carrier XC3 to the first ring gear R1, and finally drives the wheels by the power output shaft. When the vehicle speed increases to 80 km / h, if the vehicle load is still below the threshold, the second synchronizer C2 switches to the third engagement position C2-M1, the third ring gear R3 is fixed, the transmission ratio switches to 1.3, the drive motor speed is reduced, and the operating efficiency is improved. Hybrid drive mode: Triggering conditions: The power battery SOC is below 30% (second preset SOC threshold), or the vehicle speed is above 100km / h (first preset vehicle speed threshold), or the vehicle load is above 60% (second preset load threshold), such as high-speed cruising, climbing hills, rapid acceleration, etc. Mechanism operation: The control unit controls the first synchronizer C1 to switch from the first engagement position C1-M1 to the second engagement position C1-M2, the first planetary carrier XC1 engages with the first sun gear S1, the clutch CX engages, and the engine power is connected to the transmission path; the second synchronizer C2 dynamically switches the engagement position according to the vehicle speed and load to achieve adaptive adjustment of the transmission ratio. Hybrid operation (driven by both engine and drive motor): Power distribution: The engine operates in the optimal fuel economy range (2000-3000 rpm, 40%-60% load), with an output power of 80kW. Of this, 50kW is directly transmitted to the power output shaft through the first planetary gear set X1 and the third planetary gear set X3, and 30kW drives the generator P1 to generate electricity. The electricity generated by the generator is rectified and combined with the output electricity from the power battery to supply the drive motor P3. The drive motor outputs 60kW of power, which works in conjunction with the engine's direct drive power, for a total output power of 110kW, meeting the needs of high-speed overtaking or hill climbing. Torque Coordination: The control unit adjusts the engine torque, generator torque, and drive motor output torque through a PI algorithm to ensure that the torque superposition is shock-free and the torque response time is ≤0.2s; Hybrid direct drive mode (engine power is converted by generator and then supplied to drive motor): Power Flow: Engine 100 outputs 100kW, which drives generator P1 to generate electricity. The generator converts mechanical energy into electrical energy (95% efficiency). The electrical energy is directly supplied to drive motor P3 via inverter. The drive motor outputs 90kW to drive the vehicle. At the same time, the power battery selectively supplements power according to the SOC (State of Charge) (10kW supplement when SOC is below 20%). This operating condition is suitable for scenarios where the engine's high-efficiency range does not match the vehicle's power requirements, such as driving at a medium speed. Engine direct drive mode: Triggering conditions: The vehicle is traveling at a constant speed (100-140km / h), the power battery SOC is between 30% and 60%, the vehicle load is between 20% and 40%, and the engine is operating in its optimal efficiency range. Mechanism operation: The first synchronizer C1 maintains the second engagement position C1-M2, the clutch CX is fully engaged, and the drive motor P3 stops or enters the idling state; the second synchronizer C2 switches to the third engagement position C1-M1, the third gear ring R3 is fixed, and the direct transmission ratio of 0.71 is achieved through the planetary gear set, which is suitable for high-speed cruising requirements. Power flow: The engine output power of 60kW is transmitted directly to the power output shaft through the clutch CX, the first synchronizer C1, the first planetary gear set X1, and the third planetary gear set X3, without any energy conversion loss; at this time, the generator P1 runs idle with the engine or selectively generates electricity according to the battery SOC (when the SOC is below 40%, it generates 10kW to supplement the battery). Special operating conditions: Braking energy recovery mode: When a brake pedal signal (brake request) is detected, the control unit immediately controls the drive motor P3 to switch to generator mode, the second synchronizer C2 maintains its current engagement position, and the drive motor generates electricity by reverse dragging the wheels, with a maximum power output of 80kW; the recovered electrical energy is rectified and stored in the power battery, with a recovery efficiency of ≥65% (when braking at vehicle speeds of 30-100km / h); at the same time, the mechanical braking and motor braking are coordinated according to the braking intensity to ensure that the braking distance meets the national standard requirements (100km / h-0 braking distance ≤38m). Parking power generation condition: When the vehicle is stationary and the power battery SOC is below 20% (preset power generation threshold), the control unit starts the engine at 100 rpm, and the drive motor P3 provides 50 N of power. The anti-drag torque ensures a smooth engine start; when the engine is running at an idle speed of 1500 rpm, the generator P1 generates electricity at a power of 25 kW with a power generation efficiency of 94%, and the time required to charge the power battery from 20% to 80% is ≤40 minutes; at this time, the clutch CX is engaged, the first synchronizer C1 is in the second engagement position C1-M2, and the drive motor provides anti-drag resistance through the planetary gear mechanism to avoid engine idle speed fluctuations.

[0030] Neutral coasting mode: When the vehicle is coasting at high speed (vehicle speed ≥ 80km / h) and there is no acceleration or braking request, the system enters neutral coasting mode, the clutch CX is disengaged, the engine 100 stops, and the drive motor P3 provides 5kW of maintenance power to ensure low resistance operation of the transmission system. The coasting distance is increased by 20% compared with traditional fuel vehicles. When the driver presses the accelerator pedal, the system can quickly switch to hybrid drive mode within 0.3s without any sense of power interruption.

[0031] like Figure 2As shown, the following are embodiments of the control method for a series-parallel hybrid system based on P1P3 provided in this disclosure. This method belongs to the same inventive concept as the series-parallel hybrid systems based on P1P3 in the above embodiments. For details not described in detail in the embodiments of the control method for the series-parallel hybrid system based on P1P3, please refer to the embodiments of the series-parallel hybrid system based on P1P3 described above.

[0032] The method includes the following steps: S1. Obtain vehicle operating parameters; the vehicle operating parameters include battery SOC, vehicle speed, vehicle load, and driving mode request; It should be noted that by acquiring parameters such as battery SOC, vehicle speed, vehicle load, and driving mode requests, the system provides a basis for mode switching decisions; by monitoring the vehicle's operating status in real time, the system ensures that it can quickly respond to driving needs and changes in operating conditions. S2. Based on vehicle operating parameters, determine the target operating mode of the series-parallel hybrid system; the target operating mode includes pure electric drive mode, engine direct drive mode, or hybrid drive mode; It should be noted that the target operating mode is determined based on real-time parameters to ensure that the system operates in the best condition, thereby improving economy and power; the mode can be flexibly switched according to different working conditions to meet diverse driving needs. S3. Generate control commands corresponding to the target working mode and send them to the mode switching mechanism to control the first synchronizer C1 and / or the second synchronizer C2 to switch to the target engagement position, so that the transmission mechanism enters the transmission state that matches the target working mode. It should be noted that by controlling the synchronizer to switch to the target engagement position, uninterrupted gear shifting is achieved, improving driving smoothness; ensuring that the transmission mechanism enters the transmission state that matches the target working mode, and optimizing the power output path; S4. Based on the target operating mode, coordinate and control the torque and speed of engine 100, generator P1 and drive motor P3 to achieve the target power output; It should be noted that by coordinating and controlling the torque and speed of the engine, generator, and drive motor, the efficiency and stability of power output are ensured; and by rationally distributing power in different modes, the overall energy efficiency of the system is improved and energy waste is reduced.

[0033] This embodiment achieves efficient system operation and improves user experience and system performance by acquiring vehicle operating parameters and intelligently switching working modes.

[0034] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, in order to fully illustrate the specific implementation process in this embodiment, another control method for a series-parallel hybrid system based on P1P3 is provided, which includes the following steps: S1. Obtain vehicle operating parameters; the vehicle operating parameters include battery SOC, vehicle speed, vehicle load, and driving mode request; For example, the control unit collects vehicle operating parameters in real time through sensors, with the following sampling frequencies: battery SOC (10Hz), vehicle speed (20Hz), vehicle load (calculated by accelerator pedal opening and throttle opening, 20Hz), driving mode request (Economy / Standard / Sport mode, 5Hz), engine speed (50Hz), motor speed (50Hz), synchronizer position (10Hz), etc. The collected parameters are filtered (using Kalman filtering algorithm) to remove noise interference and ensure data accuracy. S2. Based on vehicle operating parameters, determine the target operating mode of the series-parallel hybrid system; the target operating mode includes pure electric drive mode, engine direct drive mode, or hybrid drive mode; The specific steps for determining the target operating mode in step S2 include: If the battery SOC is higher than the first preset SOC threshold and the vehicle load is lower than the first preset load threshold, then the target operating mode is determined to be the pure electric drive mode. If the battery SOC is lower than the second preset SOC threshold, or the vehicle speed is higher than the first preset vehicle speed threshold, or the vehicle load is higher than the second preset load threshold, then the target operating mode is determined to be the hybrid drive mode. Among them, the hybrid drive mode includes the hybrid working condition in which the engine and the drive motor drive together, and the hybrid direct drive working condition in which the engine power is converted into electrical energy by the generator P1 and then directly supplied to the drive motor P3. For example, the control unit has a built-in mode decision algorithm based on fuzzy control theory. The input parameters are battery SOC, vehicle speed, vehicle load, and driving mode request. The output is the target operating mode. In Economy mode: prioritize pure electric drive mode (SOC≥60% and load≤30%), followed by engine direct drive mode (vehicle speed100-140km / h and load20%-40%), and finally hybrid drive mode (other operating conditions).

[0035] In standard mode: the pure electric drive mode is triggered when SOC ≥ 50% and load ≤ 40%, the hybrid drive mode is the main operating mode, and the engine direct drive mode is automatically switched in during high-speed cruising.

[0036] In Sport mode: Hybrid drive mode (super hybrid mode) is used first, with the engine and drive motor outputting full power. Pure electric drive mode is only triggered when SOC ≥ 80% and load ≤ 20%. S3. Generate control commands corresponding to the target working mode and send them to the mode switching mechanism to control the first synchronizer C1 and / or the second synchronizer C2 to switch to the target engagement position, so that the transmission mechanism enters the transmission state that matches the target working mode. In step S3, when the target working mode is switched from pure electric drive mode to hybrid drive mode, the control command controls the first synchronizer C1 to switch from the first engagement position C1-M1 to the second engagement position C1-M2, so as to release the fixation of the first sun gear S1 and engage the first planetary carrier XC1 with the first sun gear S1, so that the power of the engine 100 is connected to the transmission path of the transmission mechanism. When the target working mode involves switching the drive motor P3 gear, the control command controls the second synchronizer C2 to switch between the third engagement position C2-M1 and the fourth engagement position C2-M2 to change the transmission ratio from the drive motor P3 to the power output shaft. For example, switching from pure electric mode to hybrid drive mode: The control unit first calculates the target engine speed (matching the current vehicle speed, with an error ≤ 50 rpm), and controls the drive motor P3 to adjust the speed to achieve synchronization between the engine and transmission system speeds; after synchronization is completed, the first synchronizer C1 is controlled to switch from the first engagement position C1-M1 to the second engagement position C1-M2, with a switching time ≤ 0.2s; finally, the clutch CX is engaged, and the engagement process is divided into three stages: pre-engagement (0-0.1s, torque 50N) m), semi-engagement (0.1-0.2s, torque 150N) m), complete engagement (0.2-0.3s, torque 400N) m), to avoid impact.

[0037] Drive motor gear switching (C2 synchronizer switching): The target gear ratio is calculated based on the vehicle speed and required torque, and the synchronizer sleeve is controlled to move. The moving speed is adjusted by PWM signal (0.1-0.2m / s). During the switching process, the drive motor torque is temporarily reduced by 30%, and it is quickly restored after the switching is completed to ensure smooth gear shifting and no power interruption. S4. Based on the target operating mode, coordinate and control the torque and speed of engine 100, generator P1 and drive motor P3 to achieve the target power output; In step S4, the specific steps of coordination and control are as follows, depending on the different target operating modes: In pure electric drive mode, the engine is stopped at 100, and the drive motor P3 is controlled to output torque according to the accelerator pedal opening and vehicle speed. The drive motor P3 is also controlled to start with the transmission ratio corresponding to the second synchronizer C2 being in the fourth engagement position C2-M2. In hybrid drive mode, the output power of engine 100 is allocated according to the vehicle's power demand and battery SOC, based on a preset energy management strategy. Part of the power is directly output through the transmission mechanism, and the other part of the power drives generator P1 to generate electricity. The generated energy, together with the power battery's electrical energy, is supplied to drive motor P3 either together or separately. When a braking request is detected, the drive motor P3 is controlled to enter the power generation mode to provide braking torque and store the recovered electrical energy into the power battery. When the vehicle is stationary and the battery SOC is lower than the preset power generation threshold, the engine 100 is started and the drive motor P3 is controlled to provide anti-drag torque, so that the engine 100 drives the generator P1 to generate electricity in the parking vehicle. For example, in pure electric mode: the torque of the drive motor is obtained by looking up a table based on the accelerator pedal opening and vehicle speed. When the accelerator pedal opening is 0-50%, the torque increases linearly; when it is 50%-100%, the torque is output according to the maximum power limit curve; when the vehicle speed exceeds 120km / h, the torque decreases inversely proportional to the square of the vehicle speed to ensure high-speed stability.

[0038] Hybrid drive mode: Based on the strategy of minimizing equivalent fuel consumption, the power of the engine and drive motor is allocated. The objective function is fuel consumption rate + electricity consumption equivalent fuel consumption rate. The constraints are engine power range (20-120kW), motor power range (-80-120kW, negative power is power generation), and battery SOC change rate (-5% / h-5% / h). The optimal power allocation scheme is solved by dynamic programming algorithm, and the control command is updated every 10ms.

[0039] Regenerative braking mode: The braking torque distribution follows the principle of prioritizing motor braking. When the braking intensity is ≤0.3g, the braking force is entirely provided by motor braking. When the braking intensity is >0.3g, the motor braking provides the maximum braking force (the braking torque corresponding to 80kW), and the remaining braking force is supplemented by mechanical braking. At the same time, the regeneration intensity is adjusted according to the battery SOC. Regeneration stops when SOC is ≥90% and reaches the maximum regeneration intensity when SOC is ≤20%.

[0040] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0041] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A series-parallel hybrid system based on P1P3, characterized in that, It includes an engine (100), a generator (P1), a drive motor (P3), a transmission mechanism, and a control unit; The generator (P1) is connected to the output terminal of the engine (100) and is used to convert the mechanical energy of the engine (100) into electrical energy; The drive motor (P3) is used to output torque to drive the vehicle; The transmission mechanism includes a power input shaft, a power output shaft, and at least four planetary gear sets and a mode switching mechanism disposed between the power input shaft and the power output shaft; The power of the generator (P1) and the drive motor (P3) is coupled through different planetary gear sets in the transmission mechanism and output through the power output shaft; The mode switching mechanism is used to switch the working mode of the transmission mechanism to achieve at least pure electric drive mode, engine direct drive mode and hybrid drive mode; The control unit is used to control the mode switching mechanism and the operation of the engine (100), generator (P1) and drive motor (P3) according to the vehicle's operating status.

2. The series-parallel hybrid system based on P1P3 according to claim 1, characterized in that, The transmission mechanism includes a first planetary gear set (X1), a second planetary gear set (X2), a third planetary gear set (X3), and a fourth planetary gear set (X4).

3. The series-parallel hybrid system based on P1P3 according to claim 2, characterized in that, The generator (P1) is directly connected to the engine (100) and is connected to the first planetary gear set (X1) in sequence through the clutch (CX), the first synchronizer (C1); The first synchronizer (C1) has a first engagement position (C1-M1) and a second engagement position (C1-M2); when in the first engagement position (C1-M1), the first sun gear (S1) of the first planetary gear set (X1) is fixed; when in the second engagement position (C1-M2), the first planet carrier (XC1) of the first planetary gear set (X1) is engaged with the first sun gear (S1).

4. The series-parallel hybrid system based on P1P3 according to claim 2, characterized in that, The drive motor (P3) is directly connected to the second sun gear (S2) of the second planetary gear set (X2), and the second ring gear (R2) of the second planetary gear set (X2) is fixed. The second planetary carrier (XC2) of the second planetary row (X2) is directly connected to the third sun wheel (S3) of the third planetary row (X3).

5. The series-parallel hybrid system based on P1P3 according to claim 2, characterized in that, The transmission mechanism also includes a second synchronizer (C2), which is located between the second planetary gear set (X2) and the third planetary gear set (X3); The second synchronizer (C2) has a third engagement position (C2-M1) and a fourth engagement position (C2-M2). When in the third engagement position (C2-M1), the third gear ring (R3) of the third planetary set (X3) is fixed; When in the fourth engagement position (C2-M2), the second planet carrier (XC2) of the second planetary set (X2) engages with the third gear ring (R3) of the third planetary set (X3).

6. The series-parallel hybrid system based on P1P3 according to claim 2, characterized in that, The first gear ring (R1) of the first planetary gear set (X1) is connected to the power output shaft and to the third planet carrier (XC3) of the third planetary gear set (X3).

7. A control method based on the system according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Obtain vehicle operating parameters; the vehicle operating parameters include battery SOC, vehicle speed, vehicle load, and driving mode request; S2. Based on vehicle operating parameters, determine the target operating mode of the series-parallel hybrid system; the target operating mode includes pure electric drive mode, engine direct drive mode, or hybrid drive mode; S3. Generate control commands corresponding to the target working mode and send them to the mode switching mechanism to control the first synchronizer (C1) and / or the second synchronizer (C2) to switch to the target engagement position, so that the transmission mechanism enters the transmission state that matches the target working mode; S4. Based on the target working mode, coordinate and control the torque and speed of the engine (100), generator (P1) and drive motor (P3) to achieve the target power output.

8. The control method according to claim 7, characterized in that, The specific steps for determining the target operating mode in step S2 include: If the battery SOC is higher than the first preset SOC threshold and the vehicle load is lower than the first preset load threshold, then the target operating mode is determined to be the pure electric drive mode. If the battery SOC is lower than the second preset SOC threshold, or the vehicle speed is higher than the first preset vehicle speed threshold, or the vehicle load is higher than the second preset load threshold, then the target operating mode is determined to be the hybrid drive mode. Among them, the hybrid drive mode includes the hybrid operating condition in which the engine and the drive motor drive together, and the hybrid direct drive operating condition in which the engine power is converted into electrical energy by the generator (P1) and then directly supplied to the drive motor (P3).

9. The control method according to claim 8, characterized in that, In step S3, when the target working mode is switched from pure electric drive mode to hybrid drive mode, the control command controls the first synchronizer (C1) to switch from the first engagement position (C1-M1) to the second engagement position (C1-M2) to release the fixation of the first sun gear (S1) and engage the first planetary carrier (XC1) with the first sun gear (S1), so that the power of the engine (100) is connected to the transmission path of the transmission mechanism; When the target operating mode involves gear switching of the drive motor (P3), the control command controls the second synchronizer (C2) to switch between the third engagement position (C2-M1) and the fourth engagement position (C2-M2) to change the transmission ratio from the drive motor (P3) to the power output shaft.

10. The control method according to claim 7, characterized in that, In step S4, the specific steps of coordination and control are as follows, depending on the different target operating modes: In pure electric drive mode, the engine (100) is stopped, the drive motor (P3) is controlled to output torque according to the accelerator pedal opening and vehicle speed, and the drive motor (P3) is controlled to start with the transmission ratio corresponding to the second synchronizer (C2) being in the fourth engagement position (C2-M2). In hybrid drive mode, the output power of the engine (100) is allocated according to the vehicle's power demand and battery SOC, based on a preset energy management strategy. Part of the power is directly output through the transmission mechanism, and the other part of the power drives the generator (P1) to generate electricity. The generated energy and the power battery's electrical energy are supplied to the drive motor (P3) together or separately. When a braking request is detected, the drive motor (P3) is controlled to enter the power generation mode to provide braking torque and store the recovered electrical energy into the power battery; When the vehicle is stationary and the battery SOC is lower than the preset power generation threshold, the engine (100) is started and the drive motor (P3) is controlled to provide anti-drag torque, so that the engine (100) drives the generator (P1) to generate electricity in the parking vehicle.

Images