Mode management and control method for hybrid electric vehicle

Abstract

The invention discloses a mode management and control method for a hybrid electric vehicle, aiming at a P2.5 + P4 hybrid electric vehicle framework with a four-gear gearbox, targeted design is made for management and control of an engine starting scene and a hybrid power mode working condition, and the mode management and control method mainly comprises the following steps of: presetting a forced power generation area and a preferential power generation area of a battery; if the electric quantity is in the forced power generation area, starting an engine to guarantee electricity; if the electric quantity is in the preferential power generation area and the vehicle runs at the set speed, starting an engine to generate power; when the vehicle runs normally in the pure electric mode, if the battery or the motor is large in working load for a long time, the engine is correspondingly started to enter the series connection mode or the parallel connection mode; in addition, on the basis of the structure, the invention further provides a method for executing different mode judgment mechanisms according to the operation intention of the driver, so that the vehicle can reliably and accurately respond to the requirements of the driver, and therefore, a relatively ideal solution is provided for mode management and control of the hybrid electric vehicle with the structure.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid vehicles, and particularly to the management and control of hybrid modes of a P2.5+P4 hybrid architecture, specifically a method for controlling hybrid vehicle modes. Background Art

[0002] In the industry, P2.5 is a parallel hybrid vehicle route. The P2.5 motor can achieve the functions of engine start-stop and parallel assist (assist or generate electricity when the engine is directly driving). When paired with a P4 motor (wheel direct drive motor layout), the series function can be achieved. However, there is currently no relatively ideal solution in the industry on how to achieve reliable and stable mode control in the P2.5+P4 architecture, especially engine start and related mode switches. Summary of the Invention

[0003] In view of the above, the present invention aims to provide a method for controlling hybrid vehicle modes to solve the aforementioned technical problems.

[0004] The technical solution adopted by the present invention is as follows: The present invention provides a method for controlling hybrid vehicle modes. The architecture of the hybrid vehicle includes: a vehicle controller, a rear motor controller, a transmission controller, a front motor controller, and an engine controller. The hybrid vehicle is equipped with a four-speed transmission with four clutches. Among them, the control method includes: Pre-configure battery power partitions, where the battery power partitions at least include: a forced power generation area and a priority power generation area; If it is detected that the SOC is in the forced power generation area, start the engine for power preservation until it is charged to the priority power generation area; if it is detected that the SOC is in the priority power generation area and the vehicle is traveling at a predetermined speed, start the engine for power generation; When the vehicle is traveling normally in pure electric mode, if it is detected that the duration of the battery discharge condition is greater than a first predetermined duration, start the engine to enter the series mode; or if it is detected that the duration of the motor operation condition is greater than a second predetermined duration, start the engine to enter the parallel mode; Execute different mode judgment mechanisms according to the driver's operation intention: when the vehicle is traveling normally in pure electric mode, if a full throttle acceleration condition is detected, start the engine to enter the parallel mode; if it is detected that the vehicle is in the P gear and the accelerator pedal is depressed, or a user trigger to enter the in-situ power replenishment function is received, start the engine to enter the series mode; if the vehicle is in the D gear and it is detected that the brake pedal is released and switched to the accelerator pedal being depressed, start the engine, and after the brake pedal is released, switch from the series mode to the parallel mode.

[0005] In at least one possible implementation, starting the engine into the series mode includes: After starting the engine in the pure electric rear-wheel drive mode, the vehicle control unit sends the series mode requirement to the transmission control unit. The transmission control unit controls the first clutch to close, the front motor control unit switches to the torque mode, and applies a pre-calibrated torque to make the output speed of the engine control unit reach the established speed. The engine control unit triggers fuel injection and ignition. After the engine outputs positive torque, the front motor control unit switches to the speed mode to adjust the economic operating point of the engine, and at the same time applies negative torque to switch the vehicle from the pure electric rear-wheel drive mode to the series mode.

[0006] In at least one possible implementation, the control method further includes: if the front motor control unit switches from the speed mode to the torque mode, torque distribution is performed on the engine, the front motor, and the rear motor according to the current vehicle speed, SOC, throttle opening, and vehicle state.

[0007] In at least one possible implementation, the control method further includes a target mode requirement decision mechanism: After the rear motor control unit, the transmission control unit, the front motor control unit, and the engine control unit all feedback a fault-free state, calculate the current series mode and parallel mode capabilities according to the available power of the current battery, front motor, engine, and rear motor respectively. The formula is as follows: Series mode capability = {[Battery available power + (Engine available power, Front motor available power) min , Rear motor available power} min ; Parallel mode capability = Engine available power + [Battery available power, (Front motor available power + Rear motor available power)] min ; The vehicle control unit determines the target mode requirement according to the obtained series mode capability, parallel mode capability, and wheel-end required torque: if the current parallel mode capability is greater than the series mode capability and the wheel-end required torque is greater than the series mode capability, the target mode requirement is to enter the parallel mode; if the current series mode capability is greater than the parallel mode capability and the wheel-end required torque is greater than the parallel mode capability, the target mode requirement is to enter the series mode.

[0008] In at least one possible implementation, the control method further includes: Before switching to the parallel mode, determine whether the current vehicle speed is greater than the preset switching vehicle speed threshold; If so, calculate the minimum torque value in the parallel mode according to the current vehicle speed, the available power of the battery, the current SOC, and the gear ratio of the preselected gear. If the required torque at the wheel end is greater than the minimum torque value, entry into the parallel mode is allowed.

[0009] In at least one possible implementation, the switching vehicle speed threshold is obtained based on the engine speed or the gearshift line of the transmission; and if the current operating condition is hard acceleration, the switching vehicle speed threshold is lowered.

[0010] In at least one possible implementation, the control method further includes: During the process of the vehicle being in series drive, the transmission controller calculates the currently relatively optimal preselected gear in real time according to the current vehicle speed, throttle opening, and engine speed; Before the vehicle controller sends a switching request for the parallel mode to the transmission controller, the front motor is speed-controlled according to the gear ratio of the preselected gear, the current vehicle speed, and the rotational speed of the front axle output shaft of the vehicle; After receiving the instruction to trigger the start of the parallel mode, the transmission controller controls the clutch corresponding to the preselected gear to close; After determining that the clutch is closed, the transmission controller updates the current actual gear to the corresponding parallel gear; The vehicle controller completes the switching from the series mode to the parallel mode.

[0011] In at least one possible implementation, if the preselected gear changes, the vehicle controller re-performs speed control according to the changed preselected gear.

[0012] In at least one possible implementation, the speed control of the front motor includes: During the speed control process, the vehicle controller sends a pre-fill oil instruction to the transmission controller; The transmission controller fills the corresponding clutch with oil in combination with the current preselected gear until the clutch reaches the preset semi-engagement point.

[0013] The main design concept of the present invention lies in that, for the P2.5+P4 hybrid vehicle architecture equipped with a four-speed gearbox, targeted designs are carried out for the engine start-up scenario and the control of the hybrid mode operating conditions, mainly including: presetting the forced power generation area and the priority power generation area of the battery; if the SOC is in the forced power generation area, starting the engine to maintain the power; if the SOC is in the priority power generation area and the vehicle is traveling at a given speed, starting the engine to generate power; and when the vehicle is traveling in pure electric mode, if the battery or the motor has a large workload due to long-term operation, the corresponding engine is started to enter the series mode or the parallel mode respectively; in addition, on the basis of the above architecture, the present invention also proposes to execute different mode judgment mechanisms according to the driver's operation intention, so that the vehicle can reliably and accurately respond to the driver's demand to enter the parallel or series mode, or realize the switching between the series-parallel modes. Further, the present invention provides a detailed implementation reference for the processes and details involved in mode switching, providing an ideal solution for the mode control of hybrid vehicles with the P2.5+P4 architecture. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with the drawings, where: Figure 1 It is a schematic diagram of the hybrid vehicle mode control method provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and cannot be construed as a limitation to the present invention.

[0016] The present invention proposes an embodiment of a hybrid vehicle mode control method. Specifically, the present invention mentions that the hybrid vehicle adopts a P2.5+P4 architecture, and the control units involved in this architecture can be referred to as follows: VCU vehicle controller, MCU rear motor controller (i.e., P4 motor controller), TCU transmission controller, GCU front motor controller (i.e., P2.5 motor controller), SOC battery state of charge, BMS battery management system, and ECU engine controller.

[0017] In some preferred embodiments, the present invention also considers deploying a multi-speed gearbox, specifically a four-speed AT gearbox, so that the vehicle can take into account power economy and have rich driving modes.

[0018] Specifically, through the coordinated control of the four clutches A, B, C, and D of the aforementioned four-speed transmission, two-speed control of the motor and four-speed control of the engine can be achieved, enabling the vehicle to have functions such as pure electric rear-wheel drive, pure electric front-wheel drive, pure electric four-wheel drive, series, parallel power generation, and parallel assist. Specifically, by closing clutch C or D, the GCU can perform a driving function on the front axle to achieve pure electric four-wheel drive or pure electric front-wheel drive; by closing clutch A, the GCU can start the engine to generate electricity and adjust the economic and power points of the engine, thereby realizing vehicle series operation; and after entering the series operation, while keeping clutch A closed, closing the front axle drive clutch B or C or D to achieve direct engine drive, and the following parallel states can be entered (AC - 1st gear, AD - 2nd gear, AB - 3rd gear, CD - 4th gear); when all four clutches are disengaged, it is pure electric rear-wheel drive.

[0019] For the mode control method proposed in this embodiment, as Figure 1 shown, the following implementation references are given here: Step S1: Pre-configure the battery power partition, where the battery power partition at least includes: a forced power generation area and a priority power generation area; In actual operation, the battery power partition can be pre-configured: based on the aforementioned architecture, the VCU divides the battery state of charge (SOC) according to the battery power sent by the BMS and the current ambient temperature and altitude information. Specifically, it can be divided into: a forced power generation area, a priority power generation area, etc. Of course, in other embodiments, it may also involve a balance area, a priority power consumption area, and a forced power consumption area, which are not limited in this invention. For the forced power generation area, it means that when the battery power is too low, the engine is forced to start to charge the battery; while the priority power generation area means that in this SOC range, the engine is relatively easy to start and can charge the battery or be used for motor drive.

[0020] It can be further expanded that several energy modes can also be pre-set for the control method proposed in this invention, for example: Pure electric priority mode: To ensure the user's driving experience, the engine is generally difficult to start. This mode will only start when the battery discharge power or the motor capacity cannot meet the current wheel-end power demand, or the battery power drops below the aforementioned priority power generation area, or the engine needs to be started due to the requirements of certain vehicle components. And in this mode, the power retention SOC cannot be modified.

[0021] Fuel priority mode: Prioritize power retention and balance the SOC, and the wheel-end required torque is greater than the minimum torque required to start the engine (this torque is relatively small in this mode). The engine will only start when the above adjustments are met. Similarly, in this mode, the power retention SOC cannot be modified.

[0022] Forced pure electric mode: The engine is prohibited from starting until the vehicle's battery level drops extremely low (which can be determined based on a pre-calibrated lower threshold), and then it automatically switches to pure electric priority. At the same time, the engine is forced to start for charging.

[0023] Intelligent mode: It can receive the power conservation SOC point set by the user to address the user's electricity consumption anxiety.

[0024] Continuing from the previous text, in step S2, if it is detected that the SOC is in the forced power generation area, the engine is started for power conservation until it is charged to the priority power generation area; if it is detected that the SOC is in the priority power generation area and the vehicle is traveling at a set speed (the vehicle can be controlled to travel at a preset low speed to maintain pure electricity, and the purpose of this set speed is to ensure the user's driving experience), the engine is started for power generation. Step S3: When the vehicle is driving normally in pure electric mode, if it is detected that the duration of the battery discharge condition is greater than the first preset duration, the engine is started and enters the series mode; or if it is detected that the duration of the motor operation condition is greater than the second preset duration, the engine is started and enters the parallel mode. Specifically, when the vehicle is driving normally in pure electric mode (mainly in pure electric rear-wheel drive mode), if it is detected that the battery is in a high-load discharge state for a long time, that is, the available discharge power of the battery may jump, and at this time the available power generation power of the battery cannot meet the wheel-end drive power required for the driver to drive at a constant speed at the current vehicle speed. Therefore, the engine needs to start and enter the series mode to supplement power for the wheel-end drive. To elaborate, when starting the engine in pure electric rear-wheel drive mode, the VCU sends the target mode series to the TCU, and the TCU closes clutch A. At this time, the GCU and the ECU are rigidly connected, the GCU switches to torque mode, applies a certain torque (calibrated value) to make the ECU reach the specified speed, and then the ECU injects fuel and ignites. After the engine outputs positive torque, the GCU switches to speed mode to adjust the economic point of the engine and applies negative torque. The actual mode of the whole vehicle switches from pure electric rear-wheel drive to series mode to supply power to the battery.

[0025] Correspondingly, when the vehicle is driving normally in pure electric mode, if it is detected that the motor is in a high-load working state for a long time, that is, the motor power may drop due to overheating or other problems and cannot meet the wheel-end drive power required for the current vehicle to continue driving at a constant speed, the engine needs to start and enter the parallel mode, and the engine participates in driving, and the vehicle switches to engine direct drive or parallel four-wheel drive (the engine and the P4 motor drive simultaneously); regarding the four-wheel drive mode: Since this mode is based on the aforementioned P2.5+P4 hybrid architecture and provides reliable four-wheel drive capabilities, it can be used for light off-road. For example, when the user selects the off-road mode, the vehicle can switch from pure electric rear-wheel drive to pure electric four-wheel drive mode, or enter the low-speed parallel four-wheel drive mode.

[0026] Next, in step S4, the following mode judgment mechanism is executed according to the driver's operation intention: When the vehicle is driving normally in pure electric mode, if it is detected that the driver fully depresses the accelerator pedal to overtake, the engine is started and the vehicle enters the parallel mode, and the vehicle switches to parallel four-wheel drive to improve the vehicle's power performance. If it is detected that the vehicle is in the P gear for parking and the driver steps on the accelerator pedal in place, or the user trigger to enter the in-situ charging function fed back by MP4 is received, the engine is started and enters the series mode to charge the vehicle. If the vehicle is in the established vehicle "launch" mode, that is, when the brake pedal is depressed in the D gear and then switched to the accelerator pedal to enter the launch mode, the engine will start at this time. After the user releases the brake pedal, the vehicle will quickly switch from series to parallel, enabling the vehicle to have the maximum acceleration ability.

[0027] In addition, for the start of the engine, the following situation is also included: if the vehicle is in a low-temperature environment, after the vehicle is started and the air conditioner is turned on for heating inside the vehicle, the engine will start to heat the thermal management water pump to heat the passenger compartment. This invention will not elaborate and limit this, and specifically, the decision-making process for entering the series mode or parallel mode may also include the following: First, according to the fault status of the GCU, MCU, TCU, and the engine, it is judged whether series or parallel is currently allowed; second, due to the characteristics of the above P2.5+P4 architecture in this embodiment, when in parallel, if the vehicle speed is too low, the engine speed may be dragged down very low by the wheel-end resistance, causing the engine to stall. Therefore, the condition for entering the parallel mode at least requires the current vehicle speed to meet the preset vehicle speed value.

[0028] According to the current battery capacity (available power), GCU capacity, engine capacity, and MCU capacity, calculate the capabilities of the current series mode and parallel mode (that is, the available drive power of series / parallel), and the formula is as follows: Series capacity = {[Battery capacity + (Engine capacity, GCU capacity) min , MCU capacity} min Parallel capacity = Engine capacity + [Battery capacity, (GCU capacity + MCU capacity)] min The VCU determines the actual series or parallel demand according to the current series and parallel capabilities and the demand torque at the wheel end: if the current parallel capacity is greater than the series capacity and the demand torque at the wheel end is greater than the series capacity, the VCU demands to enter the parallel mode; the same is true for series, which will not be elaborated here. If the capabilities of both series and parallel are relatively large (that is, the difference between the two is small), the above judgment method will only take effect when the demand torque at the wheel end is large: at this time, for the consideration of power performance, when the demand torque at the wheel end is large, the series or parallel mode is determined based on the current series and parallel capabilities.

[0029] Combined with the vehicle speed influence mentioned above, for entering the parallel mode, especially the series-parallel switching condition during normal driving, it can be further elaborated as follows: Generally, when in parallel front-wheel drive, the vehicle speed maintaining the lowest engine speed at the lowest gear (maximum speed ratio) cannot be 0. Therefore, the prerequisite for entering the parallel mode is the vehicle speed, and it is only allowed to enter the parallel mode when the vehicle speed is greater than a certain value. At the same time, considering economy, the series mode is mainly used at lower vehicle speeds, and the parallel mode can be entered when the vehicle speed is higher than a certain value. In addition, considering NVH, the engine speed during series power generation should not be too high. Therefore, the series and parallel switching vehicle speeds can be obtained based on the engine speed. Moreover, the series-parallel switching vehicle speeds can also be obtained based on the gearshift line of the transmission. Of course, it is also possible to combine the embodiments based on the driver's intention mentioned above. Further supplementally, in the case of sudden acceleration (full throttle), the driver demands a large torque. Therefore, a low gear with a large speed ratio can be selected. At the same time, because in the case of sudden acceleration, the series-parallel switching vehicle speed can be lowered to enable the vehicle to enter the parallel mode as soon as possible.

[0030] After the vehicle speed condition meets the switching requirement, based on the current vehicle speed, battery capacity, current battery charge, and the speed ratio of the preselected gear, etc., the minimum torque value in the parallel mode can be calculated. From this calculation result, once the parallel mode is demanded to be entered, the demanded torque at the wheel end should be greater than this minimum torque value.

[0031] Combined with the architecture embodiment of the 4-speed transmission mentioned above, since the parallel 4th gear uses clutches C and D, the whole vehicle cannot directly switch from series (clutch A) to the parallel 4th gear and can only switch to the parallel 1st / 2nd / 3rd gears.

[0032] Thus, during the series drive process, the TCU calculates the ideal preselected gear in real time based on the vehicle speed, throttle, and engine speed, etc. The ideal gear here refers to the relatively optimal gear calculated currently.

[0033] Before the VCU sends a parallel mode switching request to the TCU, it is necessary to adjust the speed of the GCU based on the speed ratio of the preselected gear, the current vehicle speed, and the front axle output shaft speed sent by the TCU. Specifically, during the speed adjustment process, the VCU sends a pre-fill oil command to the TCU, and the TCU finds the corresponding clutch according to the current preselected gear and fills the oil to make the corresponding clutch reach the Kisspoint (semi-engagement point). It should be supplemented here that pre-filling the oil in advance can prevent the TCU from changing the preselected gear due to vehicle speed changes or other reasons.

[0034] After that, the TCU waits for the VCU to start the parallel mode, and the TCU performs the action of closing the clutch. If during this process, the preselected gear changes due to network delay, the VCU re-performs the aforementioned speed regulation with the changed preselected gear. Then, after the clutch is closed, the TCU updates the current actual gear to the parallel 1 / 2 / 3 gears, and the VCU changes the current mode to the parallel mode.

[0035] Finally, it can also be supplemented that, in combination with the aforementioned embodiment based on the user's intention again, if in the working condition where the GCU switches from the speed mode to the torque mode, the VCU distributes the torques of the ECU, GCU, and MCU according to the current vehicle speed, battery power, throttle, and other vehicle states. For example, when the current vehicle speed and battery power are relatively high, and the user drives with a large throttle, after the actual vehicle mode changes from series to parallel, all the original vehicle driving forces come from the MCU. At this time, considering power and safety, some of the driving forces of the MCU need to be transferred to the front axle for distribution by the ECU and GCU. At this time, the vehicle is in a parallel four-wheel drive mode with GCU assistance; if the current battery power is low, the GCU may allocate some negative torques for power generation. At this time, the MCU may also only perform energy recovery, and all the driving forces of the vehicle are borne by the ECU. At this time, the vehicle is in a parallel front-wheel drive power generation state.

[0036] In summary, the main design concept of the present invention is that for the P2.5+P4 hybrid vehicle architecture equipped with a four-speed gearbox, targeted designs are carried out for the engine start scenario and the control of the hybrid mode working conditions, mainly including: presetting the forced power generation area and the priority power generation area of the battery; if the SOC is in the forced power generation area, starting the engine to maintain the battery power; if the SOC is in the priority power generation area and the vehicle is traveling at a predetermined vehicle speed, starting the engine to generate power; and when the vehicle is traveling in pure electric mode, if the battery or the motor has a large workload due to long-term operation, starting the engine to enter the series mode or the parallel mode respectively; in addition, on the basis of the above architecture, the present invention also proposes to execute different mode judgment mechanisms according to the driver's operation intention, so that the vehicle can reliably and accurately respond to the driver's demand to enter the parallel or series mode, or realize the switching between the series and parallel modes. Further, the present invention provides a detailed implementation reference for the processes and details involved in mode switching, providing an ideal solution for the mode control of P2.5+P4 architecture hybrid vehicles.

[0037] In the embodiments of the present invention, if there are any expressions referring to directions, they are based on the relative concepts of the embodiments. In addition, "at least one" means one or more, and "a plurality of" means two or more. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent the cases where A exists alone, A and B exist simultaneously, and B exists alone. Here, A and B can be singular or plural. The character " / " generally indicates an "or" relationship between the associated objects before and after. "At least one of the following" and its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0038] The structure, features, and effects of the present invention have been described in detail based on the embodiments shown in the drawings above. However, the above are only the preferred embodiments of the present invention. It should be noted that for the technical features involved in the above embodiments and their preferred modes, those skilled in the art can, without departing from or changing the design concept and technical effects of the present invention, reasonably combine and match them into various equivalent solutions. Therefore, the scope of the present invention is not limited by the drawings shown. Any changes made in accordance with the concept of the present invention or modified into equivalent embodiments with equivalent changes, as long as they still do not exceed the spirit covered by the description and the drawings, shall fall within the protection scope of the present invention.

Claims

1. A hybrid vehicle mode control method, wherein the architecture of the hybrid vehicle comprises: The whole vehicle controller, the rear motor controller, the gearbox controller, the front motor controller, and the engine controller are provided, and the hybrid vehicle is equipped with a four-speed gearbox with four clutches, characterized in that the control method includes: Pre-configuring battery power partitions, wherein the battery power partitions at least include: a mandatory power generation area and a priority power generation area; If it is detected that the SOC is in the mandatory power generation area, the engine is started to maintain power until the power is replenished to the priority power generation area; if it is detected that the SOC is in the priority power generation area and the vehicle is traveling at a predetermined speed, the engine is started to generate power; When the vehicle is running normally in pure electric mode, if it is detected that the battery discharge condition lasts longer than the first predetermined time, the engine is started to enter the series mode; or if it is detected that the motor operation condition lasts longer than the second predetermined time, the engine is started to enter the parallel mode; Different mode judgment mechanisms are executed according to the driver's operating intention: when the vehicle is driving normally in pure electric mode, if full throttle acceleration is detected, the engine is started to enter parallel mode; if it is detected that the vehicle is in P gear parked and the accelerator pedal is pressed, or if the user triggers the on-the-spot charging function, the engine is started to enter series mode; if the vehicle is in D gear and it is detected that the brake pedal is switched from being pressed to the accelerator pedal being pressed, the engine is started, and after the brake pedal is released, the mode is switched from series mode to parallel mode.

2. The hybrid vehicle mode control method according to claim 1, characterized in that: The starting the engine to enter the series mode comprises: After starting the engine in pure electric rear-drive mode, the vehicle controller sends the series mode request to the transmission controller; The transmission controller controls the first clutch to close, the front motor controller switches to the torque mode, and applies a pre-calibrated torque to make the output speed of the engine controller reach a predetermined speed; The fuel injection ignition is triggered by the engine controller, and after the engine outputs positive torque, the front motor controller switches to the speed mode to adjust the engine's economic operating point, and at the same time applies negative torque to switch the vehicle from pure electric rear-wheel drive mode to series mode.

3. The hybrid vehicle mode control method according to claim 2, characterized in that: The control method also includes: if the front motor controller switches from the speed mode to the torque mode, the torque is distributed to the engine, the front motor and the rear motor according to the current vehicle speed, SOC, throttle opening and the vehicle status.

4. The hybrid vehicle mode control method according to claim 1, characterized in that: The control method also includes a target mode demand decision mechanism: After the rear motor controller, transmission controller, front motor controller, and engine controller all report a fault-free state, the current series mode and parallel mode capabilities are calculated based on the available power of the current battery, front motor, engine, and rear motor, respectively. The formula is as follows: Series mode capability = {[battery available power + (engine available power, front motor available power) min ], available power of rear motor} min ; Parallel mode capability = engine available power + [battery available power, (front motor available power + rear motor available power)] min ; The vehicle controller determines the target mode requirement based on the obtained series mode capacity, parallel mode capacity and wheel-end required torque: if the current parallel mode capacity is greater than the series mode capacity, and the wheel-end required torque is greater than the series mode capacity, then the target mode requirement is to enter the parallel mode; if the current series mode capacity is greater than the parallel mode capacity, and the wheel-end required torque is greater than the parallel mode capacity, then the target mode requirement is to enter the series mode.

5. The hybrid vehicle mode control method according to claim 4, characterized in that: The control method also includes: Before switching to the parallel mode, determine whether the current vehicle speed is greater than a preset switching speed threshold; If yes, the minimum torque value in parallel mode is calculated based on the current vehicle speed, the available power of the battery, the current SOC, and the speed ratio of the pre-selected gear; If the wheel-end demand torque is greater than the minimum torque value, entering the parallel mode is allowed.

6. The hybrid vehicle mode control method according to claim 5, characterized in that: The switching vehicle speed threshold is obtained according to the engine speed or based on the gear shift line of the transmission; and if the vehicle is currently in a rapid acceleration condition, the switching vehicle speed threshold is lowered.

7. The hybrid vehicle mode control method according to claim 5, characterized in that: The control method also includes: When the vehicle is in series drive, the transmission controller calculates the current relatively optimal pre-selected gear in real time based on the current vehicle speed, throttle opening and engine speed; Before the vehicle controller sends a parallel mode switching request to the transmission controller, the front motor is speed-regulated according to the speed ratio of the pre-selected gear, the current vehicle speed and the rotation speed of the front axle output shaft of the vehicle; After receiving the instruction to trigger the parallel mode start, the transmission controller controls the clutch corresponding to the preselected gear to close; After determining that the clutch is closed, the transmission controller updates the current actual gear position to the corresponding parallel gear position; The vehicle controller completes the switch from series mode to parallel mode.

8. The hybrid vehicle mode control method according to claim 7, characterized in that: If the pre-selected gear changes, the vehicle controller will readjust the speed according to the changed pre-selected gear.

9. The hybrid vehicle mode control method according to claim 7 or 8, characterized in that: The speed regulation of the front motor comprises: During the speed regulation process, the vehicle controller sends a pre-fill oil instruction to the transmission controller; The transmission controller, in combination with the current preselected gear, fills the corresponding clutch with oil until the clutch reaches a preset half-engagement point.

Images