CN107364440B - Hybrid power car pure electric vehicle starting-up process control method - Google Patents

Abstract

The invention discloses a method for controlling the pure electric starting process of a hybrid electric vehicle. The method is as follows: when a starting request is recognized, a command to start an auxiliary oil pump is sent to the CAN network to make the clutch work at a half-joint point; when the brake pedal is released, , control the speed of the power motor to reach the set value, and at the same time control the clutch to start torque transmission, the whole vehicle starts from a standstill, and when the clutch speed is synchronized with the motor speed, the starting process is completed. In the present invention, the clutch torque control PI parameter and the feed-forward torque are related to the electric power of the power motor, and the clutch torque is corrected according to the electric power of the motor to prevent overload or runaway; at the same time, the target speed of the clutch is based on the speed of the power motor as a reference point, and the clutch torque is controlled in sections, open-loop The control ensures the rapid torque rise, and the closed-loop control makes the clutch speed change according to the target speed during the starting process, which ensures the smooth starting process of the whole vehicle and avoids the starting shock.

Description

Control method for pure electric starting process of hybrid car

technical field

The invention relates to the field of hybrid electric vehicle control, in particular to a method for controlling the pure electric starting process of a hybrid electric vehicle.

Background technique

Hybrid vehicles have multiple operating modes such as hybrid, pure electric, drive-start, and park-start. When a hybrid electric vehicle starts purely electric, since the power motor has no idle speed, it can transmit torque to the gearbox at a very low speed. When starting at low speed in pure electric mode, there are auxiliary equipment to pre-fill the clutch with oil to make the clutch work at the half-engagement point, so that it can start quickly when the speed meets the conditions. During low-speed starting, the torque transmitted by the clutch can be adjusted by controlling the pressure of the clutch. At the same time, the torque transmitted by the clutch will in turn affect the speed of the motor. Therefore, it is necessary to precisely control the clutch torque to ensure fast and no impact during the starting process.

The patent "A Pure Electric Start Control Method for Intense Hybrid Vehicles" (application number 201410317214.1) controls the motor to simulate the engine entering the idling state, and drives the internal mechanical pump of the CVT to build pressure for the CVT. After the CVT builds up pressure successfully, the clutch is controlled to enter the slipping state , the vehicle starts. In this patent, the control of clutch torque and motor speed during starting is not involved.

Contents of the invention

The object of the present invention is to provide a pure electric starting process control method of a hybrid electric vehicle which can avoid torque shock and vibration during the pure electric starting process of a hybrid electric vehicle, realize fast and stable starting of the whole vehicle, and avoid starting shock.

The present invention solves the technical problem by adopting the following technical scheme: a method for controlling the pure electric starting process of a hybrid electric vehicle, which includes:

S10. Determine whether the driver has a driving intention; when it is recognized that the vehicle has a start request, send a request to start the auxiliary oil pump to the CAN network, so that the clutch works at the half-engagement point;

S20. When the brake pedal is released, send the motor target speed S _tm to the CAN network, and when the power motor speed reaches the set speed, control the clutch to start torque transmission, the whole vehicle starts from a standstill, and the clutch control torque is T _clt ;

S30. When the rotation speed of the clutch is synchronized with the rotation speed of the motor, the starting process is completed.

Optionally, the S10 includes: when the whole vehicle is in the ready state, the shift handle is placed in the D position, the brake pedal is stepped on, and it is judged that the driver has a driving intention.

Optionally, the S20 specifically includes: when the brake pedal is released, the target speed S _Tm of the power motor is obtained according to the gear position information and the accelerator pedal position look-up table StallSpeed, and the target speed of the power motor is sent to the CAN network; the speed of the power motor When the set speed is reached, the clutch torque is controlled to rise to T _open at the rate of T _step ; after the clutch control torque reaches T _open , the clutch torque is controlled as T _clt =T _PI +T _Proactive , where T _PI is the speed closed-loop adjustment torque, P is the proportional coefficient, I is the integral coefficient; S _CltError is the difference between the actual speed of the clutch and the target speed, and the target speed of the clutch is the target speed of the motor S _Tm -S _slip1 , where S _slip1 is the speed of the motor and the speed of the clutch during pure electric driving Slip difference; T _Proactive means feed-forward torque.

Optionally, when the rate of change of the rotational speed of the motor is less than _ATm , the target rotational speed of the clutch will not increase temporarily, and the target rotational speed will change according to the curve again after the rotational speed of the motor recovers above _ATm .

Optionally, the synchronization between the rotation speed of the clutch and the rotation speed of the motor means that the rotation speed difference between the two is within S _slip1 .

The present invention has the following beneficial effects: in this embodiment, when the car is stationary, the auxiliary oil pump is used to provide oil pressure for the clutch system, so that the clutch works near the half-joint point, which can avoid the power consumption of the main motor when starting, and can also be used when the driver releases the clutch. Fast operation when the brake pedal is used, which not only meets the quickness of starting the car, but also saves battery power; and the clutch torque control PI parameters and feed-forward torque are related to the power of the power motor, and the clutch torque can be corrected according to the power of the motor to prevent overload or runaway; Third, the clutch target speed takes the power motor speed as the reference point, the clutch torque is controlled in stages, the open-loop control ensures the rapid torque rise, and the closed-loop control makes the clutch speed change according to the target speed during the starting process, ensuring the starting process of the whole vehicle Steady, to avoid starting shock.

Description of drawings

Fig. 1 is the schematic diagram of the powertrain structure of the hybrid electric vehicle of the present invention;

Fig. 2 is the calculation process diagram of the clutch control torque of the present invention;

Fig. 3 is a schematic diagram of the pure electric starting process of the hybrid electric vehicle of the present invention.

The marks in the figure are: 1-engine; 2-separation clutch; 3-power motor-; 4-dual-clutch automatic transmission.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the embodiments and the accompanying drawings.

Example 1

This embodiment provides a method for controlling the pure electric starting process of a hybrid electric vehicle. The power assembly of the hybrid electric vehicle is shown in Figure 1, which includes an engine, a separation clutch, a power motor, a dual-clutch automatic transmission, and an auxiliary oil pump; The two ends of the separation clutch are respectively connected to the engine and the power motor, the output end of the power motor is connected to the dual-clutch automatic transmission, and the output end of the dual-clutch automatic transmission is connected to the driving wheels through a reducer or the like. When the power motor is running, it will drive the mechanical pump to rotate and build up oil pressure for the transmission system. In order to realize the control method of this embodiment, the vehicle is also equipped with an auxiliary oil pump system. The auxiliary oil pump includes a set of low-voltage motor and an oil pump. The low-voltage motor is powered by a low-voltage battery. The auxiliary oil pump is connected to the hydraulic system of the vehicle. When the power motor is not working, the auxiliary oil pump can operate independently, and can provide pressure and lubrication for the entire transmission circuit.

Figure 2 is a schematic diagram of the clutch torque closed-loop control during the starting process. The input of the PI controller is the difference between the clutch target speed and the actual speed. After the PI controller calculates a torque plus the T _Proactive torque, the new torque value is obtained after passing the torque limit. By adjusting the clutch pressure and then controlling the clutch speed and the motor speed, the speed synchronization of the two is finally realized.

As shown in Figure 3, the method includes:

S10. Determine whether the driver has a driving intention; when it is recognized that the vehicle has a start request, send a request to start the auxiliary oil pump to the CAN network, so that the clutch of the dual-clutch automatic transmission works at the half-engagement point.

The whole vehicle is in the ready state, and the shift handle is placed in the D position. At time _t1 , when the brake pedal is stepped on, it is judged that the driver has driving intentions, and a request to start the auxiliary oil pump is sent to the CAN network, so that the clutch of the dual-clutch automatic transmission Works at the semi-junction point P _kisssp .

S20. When the brake pedal is released, send the motor target speed S _tm to the CAN network. When the power motor speed reaches the set speed, the clutch controlling the dual-clutch automatic transmission starts to transmit torque, and the vehicle starts from a standstill, and the clutch controls The torque is T _clt .

At time _t2 , the brake pedal is released, and the target speed S _Tm of the power motor is obtained according to the gear position information and the accelerator pedal position look-up table StallSpeed, and the target speed of the power motor is sent to the CAN network. At time _t3 , the power motor speed When the set speed is reached, the clutch torque is controlled to rise to T _open at the rate of T _step ; after the clutch control torque reaches T _open , the clutch torque is controlled as T _clt =T _PI +T _Proactive , where T _PI is the speed closed-loop adjustment torque, P is a proportional coefficient, and I is an integral coefficient. The values of P and I are related to the electric power of the power motor. They are obtained through table lookup of test data. S _CltError is the difference between the clutch actual speed and the target speed, and the clutch target speed is the motor target speed S _Tm - S _slip1 , S _slip1 is the slipping difference between the motor speed and the clutch speed during pure electric driving, and this speed difference is related to the operating conditions of the whole vehicle. In order to prevent the motor from shutting down, when the rate of change of motor speed is less than _ATm , the target speed of the clutch will not increase temporarily, until the change of motor speed returns to above _ATm , the target speed will change according to the curve. T _Proactive refers to the feed-forward torque, which is related to the power of the power motor and is obtained from the oil temperature and motor power look-up table.

S30. When the clutch rotation speed of the dual-clutch automatic transmission is synchronized with the motor rotation speed, the starting process is completed.

Preferably, the clutch works at the semi-combination point, which means that the clutch of the dual-clutch automatic transmission is about to transmit torque; and in different operating modes (manual, automatic and sports modes), the gear position information and the accelerator pedal position look-up table StallSpeed are different .

In S20, the clutch control torque is limited. When the clutch control torque is less than the set value, the clutch control torque is used as the output value. When the clutch control torque is greater than or equal to the set value, the set value is used as the output value.

In S30 , synchronizing the rotation speed of the clutch and the rotation speed of the motor means that the difference between the rotation speeds of the two is within S _slip1 .

In this embodiment, in S10, when the driver has a driving intention, start the auxiliary oil pump to rotate; when the main oil pressure is greater than the set value, fill the clutch with oil; when the speed of the power motor is greater than the set value (for example, 200rpm) , turn off the auxiliary oil pump.

In this embodiment, when the car is stationary, the auxiliary oil pump is used to provide oil pressure for the clutch system, so that the clutch works near the half-joint point, which can avoid the power consumption of starting the main motor, and can run quickly when the driver releases the brake pedal. It not only satisfies the quickness of starting the car, but also saves battery power.

Moreover, the clutch torque control PI parameters and feed-forward torque are related to the power of the power motor, and the clutch torque can be corrected according to the power of the motor to prevent overload or runaway.

Third, the clutch target speed takes the power motor speed as the reference point, the clutch torque is controlled in stages, the open-loop control ensures the rapid torque rise, and the closed-loop control makes the clutch speed change according to the target speed during the starting process, ensuring the starting process of the whole vehicle Steady, to avoid starting shock.

The sequence of the above embodiments is only for convenience of description, and does not represent the advantages or disadvantages of the embodiments.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (4)

1. A pure electric starting process control method for a hybrid electric vehicle, characterized in that, comprising: S10. Determine whether the driver has a driving intention; when it is recognized that the vehicle has a start request, send a request to start the auxiliary oil pump to the CAN network, so that the clutch works at the half-engagement point; S20. When the brake pedal is released, send the motor target speed S _tm to the CAN network, and when the power motor speed reaches the set speed, control the clutch to start torque transmission, the whole vehicle starts from a standstill, and the clutch control torque is T _clt ; S30. When the clutch speed is synchronized with the motor speed, the starting process is completed; The S20 is specifically: when the brake pedal is released, according to the gear position information and the accelerator pedal position look-up table StallSpeed, the target speed S _Tm of the power motor is obtained, and the target speed of the power motor is sent to the CAN network; the speed of the power motor reaches the set speed , the control clutch torque rises to T _open at the rate of T _step ; after the clutch control torque reaches T _open , the control clutch torque is T _clt = T _PI + T _Proactive , where T _PI is the speed closed-loop adjustment torque, P is the proportional coefficient, I is the integral coefficient; S _CltError is the difference between the actual speed of the clutch and the target speed, and the target speed of the clutch is the target speed of the motor S _Tm -S _slip1 , where S _slip1 is the speed of the motor and the speed of the clutch during pure electric driving Slip difference; T _Proactive means feed-forward torque. 2. The method for controlling the pure electric starting process of a hybrid electric vehicle according to claim 1, wherein said S10 includes: when the vehicle is in the ready state, the shift handle is placed in the D gear, the brake pedal is stepped on, and judging The driver has driving intentions. 3. The pure electric starting process control method of hybrid electric vehicle according to claim 2, characterized in that, after the rate of change of the rotational speed of the motor is less than _ATm , the target rotational speed of the clutch will not increase temporarily until the change of the rotational speed of the motor returns to After A _Tm is above, the target speed changes according to the curve. 4. The pure electric starting process control method of a hybrid vehicle according to claim 1, characterized in that, the synchronization of the clutch speed and the motor speed means that the speed difference between the two is within S _slip1 .