阅读说明：本技术 无离合器滑磨的混合动力模式切换协调控制方法及系统 (Hybrid power mode switching coordination control method and system without clutch sliding mill ) 是由 徐兴 梁聪 王峰 江昕炜 李勇 盘朝奉 解炬 于 2021-07-27 设计创作，主要内容包括：本发明提供了一种无离合器滑磨的混合动力模式切换协调控制方法及系统,该方法为：当混合动力汽车从纯电动模式向混合动力模式切换时,控制辅助电机带动发动机启动；在发动机的转速达到怠速时发动点火完成启动,在此过程中离合器保持分离状态,主电机提供车辆驱动力矩；进一步控制辅助电机转矩,实现离合器的从动盘转速平稳接近离合器的驱动盘转速,发动机在此期间不输出转矩,辅助电机转矩在加速阶段末端逐渐趋近于零；在两者转速差小于预设阈值后瞬间加大离合器油压实现离合器接合,从而实现在混合动力汽车从纯电动模式切换至混合动力模式时,避免了离合器滑磨,减少了能量损耗；且离合器接合前后传递转矩保持为零,实现无冲击的接合。(The invention provides a method and a system for hybrid power mode switching coordination control without clutch sliding, wherein the method comprises the following steps: when the hybrid electric vehicle is switched from the pure electric mode to the hybrid power mode, the auxiliary motor is controlled to drive the engine to start; when the rotating speed of the engine reaches the idling speed, the ignition is started to finish the starting, in the process, the clutch is kept in a separation state, and the main motor provides the driving torque of the vehicle; the torque of the auxiliary motor is further controlled, the rotating speed of a driven disc of the clutch is stably close to the rotating speed of a driving disc of the clutch, the engine does not output the torque in the period, and the torque of the auxiliary motor gradually approaches zero at the tail end of an acceleration stage; when the difference of the rotating speed of the clutch and the rotating speed of the engine is smaller than a preset threshold value, the clutch is instantly compressed by increasing the oil pressure of the clutch to realize the engagement of the clutch, so that the slipping of the clutch is avoided and the energy loss is reduced when the hybrid electric vehicle is switched from a pure electric mode to a hybrid power mode; and the transmission torque before and after the clutch is engaged is kept to be zero, so that the engagement without impact is realized.)

1. A hybrid power mode switching coordination control method without clutch sliding is characterized in that:

and (3) during the starting stage of the engine: the second clutch (3) is kept in a separated state, the auxiliary motor (14) drags the engine (17) to start, and when the rotating speed of the engine (17) is higher than the idling rotating speed, the starting stage of the engine (17) is finished;

clutch acceleration engagement phase: the engine (17) is started and finishes the torque output temporarily, the second clutch (3) keeps the separation state, the auxiliary motor (14) outputs the torque, the rotating speed of a driven plate of the second clutch (3) is enabled to be smoothly close to the rotating speed of a driving plate of the second clutch (3) to be less than a threshold value a, and the clutch acceleration connection stage is finished; the output torque of the auxiliary motor (14) is close to 0 at the later stage of the phase;

clutch engagement stage: the speed difference of the left end and the right end of the second clutch (3) is smaller than a threshold value a, the output torque of the auxiliary motor (14) maintains the driven disc of the second clutch (3) to track the rotating speed of the driving disc, the acceleration of the driven disc is consistent with that of the driving disc, and at the moment, the transmission controller (12) controls the second clutch (3) to be engaged.

2. The method of claim 1, wherein the clutch transmits a torque of 0 to the vehicle driveline during the acceleration engagement phase, and transmits a resultant force of the engine (17) and the auxiliary electric machine (14) to the vehicle driveline during the engagement phase.

3. The hybrid mode-switching coordinated control method of clutch-less slip-mill according to claim 2, characterized in that the driven disk acceleration of the second clutch (3) is gradually decreased during the acceleration engagement, and the resultant force of the auxiliary motor (14) and the engine (17) is close to 0; the torque transmitted by the second clutch (3) to the vehicle transmission system at the moment of engagement is kept at 0, and no sudden change in torque occurs.

4. The method of claim 1, wherein the threshold a is: and when the second clutch (3) is engaged, the maximum value of the difference between the rotating speed of the driven plate of the second clutch (3) and the rotating speed of the driving plate of the second clutch (3).

5. The hybrid mode-switching coordinated control method of clutch-less slip-mill according to claim 1, characterized in that the auxiliary motor (14) output torque is determined by the electronic control unit (18) based on a multi-objective optimization algorithm whose control targets are the rapidity and comfort of the mode-switching process, obtaining the torques of the auxiliary motor (14) and the drive motor (7) of the mode-switching process.

6. The clutch-less slip hybrid mode-switching coordination control method of claim 5, characterized in that said mode-switching process is: and (3) switching the pure electric mode in which the driving motor (7) is driven independently to the hybrid driving mode of the engine (17) and the driving motor (7).

7. A control system for implementing the hybrid power mode switching coordination control method of the clutch-free slip mill of any one of claims 1-6, characterized by comprising an energy management controller, a rotation speed sensor, a coordination controller and an actuator control unit, wherein the energy management controller, the rotation speed sensor and the coordination controller are connected with the coordination controller, and the coordination controller and the actuator control unit are connected; the actuator control unit comprises an engine controller (16), a gearbox controller (12), an auxiliary motor controller (13) and a driving motor controller (8), wherein the engine controller (16), the gearbox controller (12), the auxiliary motor controller (13) and the driving motor controller (8) respectively control the engine (17), the clutch, the auxiliary motor (14) and the driving motor (7); the energy management controller determines a travel mode of the vehicle based on the driver torque request.

8. The control system according to claim 7, characterized in that the clutches comprise a first clutch (2), a second clutch (3) and a third clutch (4), the first clutch (2) is connected with an auxiliary motor (14), the auxiliary motor (14) is connected with the second clutch (3) and the third clutch (4), and the second clutch (3) is respectively connected with a gear pair II (19), a gear pair III (20) and a drive motor reduction gear pair (6); the third clutch (4) is connected with the gear pair I (11); the driving motor (7) is connected with the gear pair II (19) and the gear pair III (20) through the driving motor reduction gear pair (6).

9. The control system according to claim 8, characterized in that in the electric-only mode, the first clutch (2) is engaged, the second clutch (3) and the third clutch (4) are disengaged, and the auxiliary electric machine (14) and the engine (17) are stationary; and in the hybrid driving mode, the coordination controller determines a control torque according to the rotating speed, the motor torque and the clutch torque and transmits the control torque to the actuator control unit.

Technical Field

The invention belongs to the technical field of hybrid vehicle control, and particularly relates to a clutch-free sliding-grinding hybrid mode switching coordination control method and system.

Background

In recent years, new energy automobiles driven by pure electric energy are rapidly developed. However, the driving range of the electric vehicle is short due to the limitation of the battery capacity, so that the hybrid electric vehicle combining the long driving range of the fuel vehicle and the energy-saving characteristic of the new energy vehicle is a new development trend. A hybrid electric vehicle mainly comprises a motor, an engine, a clutch and a power coupling mechanism, wherein a vehicle control unit is communicated with controllers of actuators through a CAN network. The multi-power source structure of the hybrid electric vehicle determines that an energy management strategy needs to be designed to dynamically distribute the output power of the engine and the motor, and the working modes are switched to improve the fuel economy. However, the switching of the operation mode involves the intervention or withdrawal of the power source, which is likely to cause fluctuations in the output torque and even a power interruption. It is therefore desirable to design a coordinated control strategy to achieve a smooth and rapid mode switching process.

The prior art employs a slip of the clutch to start the engine and engage the clutch, which, while achieving a smooth mode switching process, introduces additional energy waste and reduces the useful life of the clutch.

Disclosure of Invention

The invention provides a hybrid power mode switching coordination control method and a hybrid power mode switching coordination control system without clutch sliding, aiming at the defects in the prior art, when a pure electric working mode is switched to a hybrid power working mode, the sliding process of a clutch is cancelled, an auxiliary motor is used for adjusting the rotating speeds of two ends of the clutch to a certain threshold value, the sum of the torques of the auxiliary motor and an engine is controlled to be 0 when the rotating speeds of the two ends are synchronous, and then the clutch is directly engaged, so that the clutch is ensured to be engaged without impact.

The present invention achieves the above-described object by the following technical means.

A hybrid power mode switching coordination control method without clutch sliding friction specifically comprises the following steps:

and (3) during the starting stage of the engine: the second clutch keeps a separation state, the auxiliary motor drags the engine to start, and when the rotating speed of the engine is higher than the idling rotating speed, the starting stage of the engine is finished;

clutch acceleration engagement phase: the engine is started and does not output torque temporarily, the second clutch keeps a separation state, the motor is assisted to output torque, the rotating speed of a driven plate of the second clutch is stably close to the rotating speed of a driving plate of the second clutch until the rotating speed is smaller than a threshold value a, and the clutch acceleration connection stage is finished; the output torque of the auxiliary motor (14) is close to 0 at the later stage of the phase;

clutch engagement stage: and the rotating speed difference of the left end and the right end of the second clutch is smaller than a threshold value a, the output torque of the auxiliary motor maintains the driven disc of the second clutch to track the rotating speed of the driving disc, the acceleration of the driven disc is consistent with that of the driving disc, and the transmission controller controls the second clutch to be engaged at the moment.

Further, the clutch transmits a torque of 0 to the vehicle driveline during the acceleration engagement phase, and transmits a resultant force of the engine and the auxiliary motor to the vehicle driveline during engagement.

Further, the acceleration of the driven plate of the second clutch is gradually reduced in the acceleration engaging process, and the resultant force of the auxiliary motor and the engine is close to 0; the torque transmitted by the second clutch to the vehicle driveline at the moment of engagement remains 0 and no sudden change in torque occurs.

Further, the threshold value a is: and when the second clutch is engaged, the maximum value of the difference between the rotating speed of the driven plate of the second clutch and the rotating speed of the driving plate of the second clutch is obtained.

Further, the output torque of the auxiliary motor is determined by the electronic control unit based on a multi-objective optimization algorithm, the control target of the multi-objective optimization algorithm is rapidity and comfort of the mode switching process, and the torques of the auxiliary motor and the driving motor in the mode switching process are obtained.

Further, the mode switching process is: and switching the pure electric mode in which the driving motor is driven independently to the hybrid driving mode of the engine and the driving motor.

A hybrid power mode switching coordination control system without clutch sliding grinding comprises an energy management controller, a rotating speed sensor, a coordination controller and an actuator control unit, wherein the energy management controller and the rotating speed sensor are connected with the coordination controller; the actuator control unit comprises an engine controller, a gearbox controller, an auxiliary motor controller and a driving motor controller, wherein the engine controller, the gearbox controller, the auxiliary motor controller and the driving motor controller respectively control the engine, the clutch, the auxiliary motor and the driving motor; the energy management controller determines a travel mode of the vehicle based on the driver torque request.

In the above technical scheme, the clutch includes a first clutch, a second clutch and a third clutch, the first clutch is connected with an auxiliary motor, the auxiliary motor is connected with the second clutch and the third clutch, and the second clutch is respectively connected with a gear pair II, a gear pair III and a driving motor reduction gear pair; the third clutch is connected with the gear pair I; the driving motor is connected with the gear pair II and the gear pair III through the driving motor reduction gear pair.

In the technical scheme, when the electric-only electric drive mode is adopted, the first clutch is in an engaging state, the second clutch and the third clutch are in a separating state, and the auxiliary motor and the engine are in a static state; and in the hybrid driving mode, the coordination controller determines a control torque according to the rotating speed, the motor torque and the clutch torque and transmits the control torque to the actuator control unit.

The invention has the beneficial effects that:

(1) the invention realizes the stable and impact-free switching of the pure electric working mode to the hybrid power working mode through the coordination control of the auxiliary motor, the driving motor and the clutch;

(2) the invention cancels the sliding process of the clutch in the accelerating engagement stage and the engagement stage of the clutch, reduces the consumption of the sliding work of the clutch, saves energy, protects environment and prolongs the service life of the clutch;

(3) the invention does not need to accurately control the torque of the clutch, thereby reducing the difficulty of designing a lower layer controller.

Drawings

FIG. 1 is a schematic diagram of a dual motor hybrid vehicle system according to the present invention;

FIG. 2 is a schematic diagram of a hybrid mode switching coordination control system without a clutch and a sliding friction according to the present invention;

FIG. 3 is a schematic diagram illustrating the energy flow of a two motor hybrid vehicle according to the present invention during mode switching;

FIG. 4 is a flow chart of a hybrid mode switching coordination control method of the clutch-less slip-grinding system of the present invention;

FIG. 5 shows the variation of the torque of the auxiliary motor, the torque transmitted by the second clutch, the rotational speed of the driven plate of the second clutch and the rotational speed of the driving plate of the second clutch at each stage of the present invention;

in the figure, 1, wheel; 2. a first clutch; 3. a second clutch; 4. a third clutch; 5. a dual clutch transmission; 6. A pair of drive motor reduction gears; 7. a drive motor; 8. a drive motor controller; 9. a main reducer; 10. a differential gear pair; 11. a gear pair I; 12. a transmission controller; 13. an auxiliary motor controller; 14. an auxiliary motor; 15. a brake; 16. an engine controller; 17. an engine; 18. an electronic control unit; 19. a gear pair II; 20. and a gear pair III.

Detailed Description

The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.

As shown in fig. 1, a two-motor hybrid vehicle includes an engine 17, an Engine Controller (ECU)16, an auxiliary motor 14, an auxiliary Motor Controller (MCUI)13, a drive Motor Controller (MCUII)8, a drive motor 7, a first clutch 2, a second clutch 3, a third clutch 4, a brake 15, a dual clutch transmission 5, a Transmission Controller (TCU)12, and an electronic control unit (HCU) 18; the brake 15 is located between the engine 17 and the first clutch 2; the first clutch 2 is connected with the auxiliary motor 14; the double-clutch gearbox 5 comprises a second clutch 3, a third clutch 4, a gear I pair 11, a gear II pair 19, a gear III pair 20, a driving motor reduction gear pair 6 and a differential gear pair 10; the auxiliary motor 14 is connected with the second clutch 3 and the third clutch 4; the second clutch 3 is respectively connected with the gear pair II 19, the gear pair III 20 and the driving motor reduction gear pair 6; the third clutch 4 is connected with the gear pair I11; the driving motor 7 is connected with a gear pair II 19 and a gear pair III 20 through a driving motor reduction gear pair 6; the gear I pair 11, the gear II pair 19 and the gear III pair 20 are connected with the differential gear pair 10; the differential gear pair 10 is connected with the main speed reducer 9; the main speed reducer 9 is connected with the wheels 1 through half shafts; an Engine Controller (ECU)16 is connected to the engine 17; an auxiliary Motor Controller (MCUI)13 is connected to an auxiliary motor 14; a drive Motor Controller (MCUII)8 is connected with the drive motor 7; the gearbox controller 12 is connected with the dual clutch gearbox 5; an electronic control unit (HCU)18 is connected to an Engine Controller (ECU)16, an auxiliary Motor Controller (MCUI)13, a drive Motor Controller (MCUII)8, and a transmission controller 12.

As shown in fig. 2, an Engine Controller (ECU)16, a Transmission Controller (TCU)12, an auxiliary Motor Controller (MCUI)13, and a drive Motor Controller (MCUII)8 serve as actuator control units, and the Engine Controller (ECU)16, the Transmission Controller (TCU)12, the auxiliary Motor Controller (MCUI)13, and the drive Motor Controller (MCUII)8 send control signals to the engine 17, the clutches (first clutch 2, second clutch 3, third clutch 4), the auxiliary motor 14, and the drive motor 7, respectively; an Engine Controller (ECU)16, a Transmission Controller (TCU)12, an auxiliary Motor Controller (MCUI)13 and a driving Motor Controller (MCUII)8 are connected with a coordination controller, and the coordination controller is connected with a rotating speed sensor and an energy management controller; the energy management controller determines a travel mode of the vehicle based on the driver torque request.

The present invention is directed to a mode switching process from an electric-only mode in which the drive motor 7 is driven alone to a mode in which the engine 17 and the drive motor 7 are driven in combination.

Before the mode switching, the vehicle runs in a pure electric mode driven by a driving motor 7, a first clutch 2 is in an engaged state, a second clutch 3 and a third clutch 4 are in a separated state, and an auxiliary motor 14 and an engine 17 are in a static state; when the energy manager sends a mode switching command, the coordination controller determines a control torque (see Hao Y, Jiao X, Liang L, et al. objective. H ∞ control-based regenerative control system for plug-in hybrid electric vehicle J. Mechanical Systems and Signal Processing,2018,99(jan.15):326- > 344) according to the rotation speed, the motor torque (including the driving motor and the auxiliary motor) and the clutch torque, and transmits the control torque to the actuator control unit through the CAN bus, and the actuator control unit further controls the engine 17, the second clutch 3, the auxiliary motor 14 and the driving motor 8 to complete the mode switching.

The energy flow change during the mode switching of the two-motor hybrid vehicle is shown in fig. 3; in the pure electric mode, the first clutch 2, the second clutch 3 and the third clutch 4 are all in a separated state, only the driving motor 7 acts to drive the vehicle, and energy flows to the wheels 1 from the driving motor 7; during the mode switching process, the first clutch 2 is directly engaged, the second clutch 3 is kept in a disengaged state, the engine 17 is ensured, and the rotating speed of a driven plate of the second clutch 3 is increased; when the rotation speed of the two ends of the second clutch 3 is less than the threshold value a, the second clutch 3 is engaged, the torque output of the engine 17 after the start is completed and the auxiliary motor 14 can be transmitted to the wheels 1 through the engaged second clutch 3, and the vehicle is driven by the cooperation of the energy of the driving motor 7, and enters a hybrid driving mode.

In fig. 3, C1 denotes the first clutch 2, C2 denotes the second clutch 3, MG1 denotes the assist motor 14, and MG2 denotes the drive motor 7.

As shown in FIG. 4, the hybrid mode shift coordinated control method without clutch slipping includes an engine start phase, a clutch acceleration engagement phase and a clutch engagement phase.

The torque T of the auxiliary motor 14 at each stage is shown in FIG. 5_m1Torque T transmitted by the second clutch 3_clThe driven disk speed omega of the second clutch 3_clWith the rotational speed ω of the drive plate of the second clutch 3_crA change in situation.

And (3) during the starting stage of the engine: the second clutch 3 is kept in a separated state, and the torque for dragging the engine 17 to start by the auxiliary motor 14 is decided by a control algorithm in the electronic control unit 18 by taking the fastest engaging speed and driving smoothness as control targets; when the rotational speed ω of the engine 17_eAbove idle speed omega_idelThe engine 17 start phase ends.

Clutch acceleration engagement phase: the engine 17 is started completely but torque is not output temporarily, the second clutch 3 is kept in a disengaged state, the auxiliary motor 14 continues to output the required torque according to a control algorithm in the electronic control unit 18, the rotating speed of the driven plate of the second clutch 3 is smoothly close to the rotating speed of the driving plate of the second clutch 3 until the rotating speed is smaller than a certain threshold value a (the threshold value a represents the maximum value of the difference between the rotating speed of the driven plate of the second clutch 3 and the rotating speed of the driving plate of the second clutch 3 when the second clutch 3 is engaged and can be set according to actual conditions), and the clutch acceleration engaging stage is ended. The torque transmitted by the clutch to the vehicle driveline during the acceleration engagement phase is 0, while the combined force of the engine 17 and the auxiliary electric machine 14 is transmitted to the vehicle driveline during engagement. In order to avoid abrupt changes in torque transmission before and after clutch engagement, as shown in fig. 5, the driven disk acceleration of the second clutch 3 is controlled to be gradually reduced during the acceleration engagement, so the output torque of the auxiliary motor 14 is also gradually reduced to approach 0, and the engine 17 does not output torque to the outside at this time; so that the torque transmitted by the second clutch 3 to the vehicle driveline does not jump during the moment of engagement, resulting in a smooth mode switching process. Compared with the traditional mode switching process, the mode switching process realizes the synchronization of the rotating speed and the torque at two sides through the sliding grinding of the first clutch 3, and the mode switching process does not need the sliding grinding of the second clutch 3.

Clutch engagement stage: the speed difference between the left end and the right end of the second clutch 3 is smaller than a threshold value a, the output torque of the auxiliary motor 14 maintains the driven disc of the second clutch 3 to track the rotating speed of the driving disc and the acceleration keeps consistent, and at the moment, a Transmission Control Unit (TCU)12 directly controls the second clutch 3 to be engaged; at this time, as shown in fig. 5, the torque actually transmitted after the engagement of the clutch is the resultant force of the assist motor 14 and the engine 17, and since the resultant force is 0, the torque transmitted before and after the engagement of the clutch is 0, and there is no abrupt change in torque, so that the mode switching process without shock and without slip is realized.

The control algorithm is a multi-objective optimization algorithm (prior art) whose control objectives are rapidity and comfort of the mode switching process, and optimizing the torques of the auxiliary motor 14 and the drive motor 7 for obtaining the mode switching process.

Considering that the running condition of the vehicle is complex, the interference of the surrounding environment on the vehicle system and the error of the sensor signal acquisition may deteriorate the control effect of the coordination controller, a robust H ∞ control algorithm is selected to control the driven disk and the driving disk of the second clutch 3 to track the reference rotating speed obtained by the conversion of the vehicle speed required by the driver, so as to decide the driving torques of the auxiliary motor 14 and the driving motor 7. The robust H-infinity control algorithm can resist external interference in the vehicle mode switching process, so that a more stable control effect is obtained. The specific process is as follows:

first, the two-motor hybrid vehicle system may construct the following system equations:

in the formula, T_enIs the engine 17 torque, T_m1To assist the motor 14 torque, T_m2For driving motor 8 torque, T_fAs a running resistance torque of the vehicle, i₂For reduction ratio of the drive motor 8, i₀Is the reduction ratio of the final drive 9, J_enIs the equivalent moment of inertia of the engine, J_m1To assist the motor 14Equivalent moment of inertia, J_clIs the equivalent moment of inertia of the driven plate of the second clutch 3, J_crFor equivalent moment of inertia of the discs of the second clutch 3, J_m2To drive the equivalent moment of inertia of the motor 8, J_vehIs the equivalent moment of inertia, k, of the whole vehicle_TDSIs the equivalent torsional stiffness of the output shaft of the engine 17, C_TDSFor equivalent torsional damping of the output shaft of the engine 17, k_THEquivalent torsional stiffness of the wheel 1 and the axle shaft, C_THFor equivalent torsional damping of the wheel 1 and the half-shaft, theta_enAn output shaft angle of the engine 17 is shown,representing the first derivative of the output shaft rotation angle of the engine 17,representing the second derivative of the output shaft rotation angle, theta, of the engine 17_lIndicates the driven plate rotational angle of the second clutch 3,the first derivative of the driven disc rotational angle of the second clutch 3 is indicated,representing the second derivative of the angle of rotation of the driven plate, theta, of the second clutch 3_rIndicates the drive disk rotational angle of the second clutch 3,representing the first derivative of the driving disk rotational angle of the second clutch 3,representing the second derivative of the angle of rotation of the driving plate, theta, of the second clutch 3_fWhich indicates the angle of rotation of the wheel 1,the first derivative of the angle of rotation of the wheel 1 is indicated,representing the second derivative of the rotation angle of the wheel 1;

the selected state quantity and the control quantity are respectively expressed as:

thus, the state equation of the mode switching process of the dual-motor hybrid vehicle is obtained as follows:

in the formula: w external interference signal, and w ═ T_enΔB_ad]^I，B_aD is a linear fitting coefficient of the vehicle running resistance moment, and is a sensor measurement error; a is the system state matrix, B₁To control the matrix, B₂Is an interference matrix, and:

the objective function of the control algorithm may be expressed as:

wherein J represents an objective function value, α₁、α₂、α₃Respectively representing driving smoothness, mode switching time and drivingWeight parameter, alpha, of three indicators of member torque demand₄The torque of the auxiliary motor is as close to 0 as possible when the constraint system reaches the equilibrium state, so that the impact caused by sudden change of the torque during engagement, alpha, is avoided₅The torque for restraining the driving motor is as small as possible, so that the waste of energy is avoided;

indicating the degree of impact, ω_lIs the driven disk speed, omega, of the second clutch 3_refThe clutch disc reference rotation speed obtained by conversion according to the required vehicle speed,first derivative, omega, of clutch disc reference speed obtained by conversion according to required vehicle speed_rThe rotational speed of the drive plate, T, of the second clutch 3_refThe obtained reference torque is converted for the driver required rotation speed.

The performance output of the dual-motor hybrid mode switching is thus:

further, the performance output of the system may be expressed as:

z＝C₁x+D₁u (6)

in the formula, C₁To output a state matrix, D₁Is an output control matrix, and:

from the robust H ∞ control theory, the hybrid mode switching system is asymptotically stable if and only if there is one symmetric positive definite matrix P and the matrix G, W, such that:

the linear matrix inequality (equation (7)) is solved based on the MATLAB LMI toolbox, and the feedback gain of the hybrid mode switching system can be obtained:

K＝GW^-1 (8)

the drive torques of the auxiliary motor 14 and the drive motor 7 are:

u＝Kx (9)

the motors are controlled according to the calculated required torques of the assist motor 14 and the drive motor 7, and the clutch is controlled to be rapidly engaged when the clutch engagement condition is satisfied, completing the mode switching process.

The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.