阅读说明：本技术 混合动力汽车纯电动驱动模式换档点标定的方法 (Method for calibrating pure electric drive mode shift point of hybrid electric vehicle ) 是由 韩婷 钟发平 于海生 程辉军 邹永强 庞雷保 孙哲浩 于 2020-03-31 设计创作，主要内容包括：本发明提供了一种混合动力汽车纯电动驱动模式换档点标定的方法,根据EV-1驱动模式换档点的标定方法获得EV-1驱动模式下的外齿圈转速、外齿圈扭矩与系统效率的三维对应表和外齿圈转速、外齿圈扭矩与第一制动器锁止扭矩的三维对应表,根据EV-2驱动模式换档点的标定方法获得EV-2驱动模式下的外齿圈扭矩、外齿圈转速与系统效率的三维对应表,根据EV-3驱动模式换档点的标定方法获得EV-3驱动模式下的外齿圈转速、外齿圈扭矩与系统效率的三维对应表和外齿圈转速、外齿圈扭矩与第一行星架转速的三维对应表。本发明方法简单可行,确保混合动力汽车所运行工况的动力系统效率最优,减少效率损失。(The invention provides a method for calibrating a pure electric drive mode gear shifting point of a hybrid electric vehicle, which comprises the steps of obtaining a three-dimensional correspondence table of an outer gear ring rotating speed, an outer gear ring torque and system efficiency and a three-dimensional correspondence table of the outer gear ring rotating speed, the outer gear ring torque and first brake locking torque under an EV-1 drive mode according to a calibration method of the EV-1 drive mode gear shifting point, obtaining a three-dimensional correspondence table of the outer gear ring torque, the outer gear ring rotating speed and system efficiency under an EV-2 drive mode according to a calibration method of the EV-2 drive mode gear shifting point, and obtaining a three-dimensional correspondence table of the outer gear ring rotating speed, the outer gear ring torque and system efficiency and a three-dimensional correspondence table of the outer gear ring rotating speed, the outer gear ring torque and first planet carrier rotating speed under an EV-3 drive mode gear shifting point. The method is simple and feasible, ensures the optimal efficiency of the power system of the running working condition of the hybrid electric vehicle, and reduces the efficiency loss.)

1. A method for calibrating a shift point of a pure electric drive mode of a hybrid electric vehicle is characterized by comprising the following steps: the method comprises the following steps:

the calibration method of the EV-1 driving mode shift point specifically comprises the following steps:

s1 setting the running mode of the vehicle to be EV-1 driving mode in INCA-F L OW software, increasing the rotation speed of the half shaft to the target rotation speed of the half shaft, and setting the target torque THo _ Set of the outer gear ring and the maximum Value TB1 of the locking torque of the first brake by a Set Value tool_maxThe external gear ring torque nominal quantity THo _ soll _ MC and the first brake locking torque nominal quantity TB1_ soll are assigned respectively, and then the step S2 is executed;

s2 measures and records a first brake locking torque TB1, an outer gear ring torque THo, an outer gear ring rotating speed nHo and system Efficiency Sys _ Effecieny in real time within a Set time, calculates average values of the first brake locking torque, the outer gear ring rotating speed and the system Efficiency respectively, writes the average values into an Excel table through an Excel Write tool, takes the average values of the first brake locking torque, the outer gear ring rotating speed and the system Efficiency as a Set of corresponding first brake locking torque, outer gear ring rotating speed and system Efficiency under the half-shaft target rotating speed, assigns the current values of a first brake locking torque standard quantity TB1_ soll and an outer gear ring torque standard quantity THo _ soll _ MC to a constant A and a constant B through a Set Value tool respectively, and then executes a step S3;

s3, judging whether the current temperatures of the small motor (E1) and the large motor (E2) are both lower than a first preset temperature, if so, executing a step S4; if not, removing the first brake locking torque standard quantity TB1_ soll and the outer gear ring torque standard quantity THo _ soll _ MC, waiting for the temperature reduction of the small motor and the large motor, when the temperatures of the small motor and the large motor are both smaller than a second preset temperature, enabling the second preset temperature to be smaller than the first preset temperature, respectively assigning the values of the constant A and the constant B to the first brake locking torque standard quantity TB1_ soll and the outer gear ring torque standard quantity THo _ soll _ MC, and then executing the step S2 again;

s4 reassigns the current first brake locking torque nominal quantity TB1soll to the first brake locking torque nominal quantity TB1_ soll after subtracting the first preset value, and judges whether the reassigned first brake locking torque nominal quantity TB1soll is smaller than the first brake locking torque minimum value TB1_minIf not, re-executing step S2; if yes, subtracting a second preset value from the current outer gear ring torque standard quantity THo _ soll _ MC, then reassigning the value to the outer gear ring torque standard quantity THo _ soll _ MC, judging whether the reassigned outer gear ring torque standard quantity THo _ soll _ MC is smaller than the difference value between the minimum value allowed by the outer gear ring torque and a third preset value, and if yes, executing a step S5; if not, re-executing step S2;

s5, changing the target rotation speed of the half shaft, obtaining all corresponding first brake locking torques, external gear ring rotation speeds and system efficiencies under different target rotation speeds of the half shaft according to the steps S1-S4, selecting the highest system efficiency under the combination of the rotation speed of each external gear ring and the torque of each external gear ring and the first brake locking torque corresponding to the highest system efficiency, and establishing a three-dimensional correspondence table of the rotation speed of the external gear ring, the torque of the external gear ring and the system efficiency and a three-dimensional correspondence table of the rotation speed of the external gear ring, the torque of the external gear ring and the first brake locking torque under the EV-1 driving mode by using the selected data;

the calibration method of the EV-2 driving mode shift point is specifically carried out according to the following steps:

(a) setting the vehicle running mode to be an EV-2 driving mode in the INCA-F L OW software, then increasing the rotation speed of the half shaft to the target rotation speed of the half shaft, assigning the target torque THo _ Set of the outer gear ring to the calibrated amount THo _ soll _ MC of the outer gear ring through a Set Value tool, and then executing the step (b) again;

(b) measuring and recording the external gear ring torque THo, the external gear ring rotating speed nHo and the system Efficiency Sys _ Efficiency in real time within a set time, respectively calculating average values of the external gear ring torque, the external gear ring rotating speed and the system Efficiency, writing the average values into an Excel table through an Excel Write tool, taking the average values of the external gear ring torque, the external gear ring rotating speed and the system Efficiency as a set of corresponding external gear ring torque, external gear ring rotating speed and system Efficiency at the target rotating speed of the half shaft, and then executing the step (c);

(c) judging whether the temperatures of the current small motor (E1) and the current large motor (E2) are both lower than a first preset temperature, if so, executing the step (d); if not, removing the outer gear ring torque calibration amount THo _ soll _ MC, waiting for the small motor and the large motor to be cooled, and when the temperatures of the small motor and the large motor are both lower than a second preset temperature, and the second preset temperature is lower than the first preset temperature, re-executing the step (b);

(d) subtracting a second preset value from the current outer gear ring torque standard quantity THo _ soll _ MC, then reassigning the value to the outer gear ring torque standard quantity THo _ soll _ MC, judging whether the reassigned outer gear ring torque standard quantity THo _ soll _ MC is smaller than the difference value between the outer gear ring torque allowable minimum value and a fourth preset value, and if so, executing the step (e); if not, re-executing the step (b);

(e) changing the target rotating speed of the half shaft, obtaining the torque of the outer gear ring, the rotating speed of the outer gear ring and the system efficiency corresponding to the target rotating speeds of different half shafts according to the steps (a) - (d), and establishing a three-dimensional corresponding table of the torque of the outer gear ring, the rotating speed of the outer gear ring and the system efficiency in the EV-2 driving mode;

the calibration method of the EV-3 driving mode gear shifting point is specifically carried out according to the following steps:

i setting the running mode of the vehicle to be an EV-3 driving mode in INCA-F L OW software, increasing the rotating speed of a half shaft to a target rotating speed of the half shaft, and using a Set Value tool to increase the target torque THo _ Set of the outer gear ring and the maximum rotating speed nst of the first planet carrier_maxCorrespondingly assigning a torque standard quantity THo _ soll _ MC of the outer gear ring and a rotating speed standard quantity nst _ soll of the first planet carrier, and then executing the step ii;

ii, measuring and recording the first planet carrier rotating speed nst, the outer gear ring torque THo, the outer gear ring rotating speed nHo and the system Efficiency Sys _ Efficiency in real time within a Set time, respectively calculating average values of the first planet carrier rotating speed, the outer gear ring torque, the outer gear ring rotating speed and the system Efficiency, writing the average values into an Excel table through an Excel Write tool, taking the average values of the first planet carrier rotating speed, the outer gear ring torque, the outer gear ring rotating speed and the system Efficiency as a Set of corresponding first brake locking torque, outer gear ring rotating speed and system Efficiency under the half-shaft target rotating speed, respectively assigning the current values of the first planet carrier rotating speed standard quantity nst _ soll and the outer gear ring torque standard quantity THo _ solo _ MC to a constant A and a constant B through a Set Value tool, and then executing a step iii;

iii, judging whether the temperatures of the current small motor (E1) and the current large motor (E2) are both lower than a first preset temperature, if so, executing a step iv; if not, removing the first planet carrier rotating speed standard amount nst _ soll and the outer gear ring torque standard amount THo _ soll _ MC, waiting for the small motor and the large motor to be cooled, when the temperatures of the small motor and the large motor are both lower than a second preset temperature, enabling the second preset temperature to be lower than the first preset temperature, respectively assigning the values of the constant A and the constant B to the first planet carrier rotating speed standard amount nst _ soll and the outer gear ring torque standard amount THo _ soll _ MC, and then executing the step ii again;

iv, subtracting a fifth preset value from the current first planet carrier rotating speed standard quantity nst _ soll, then assigning the value to the first planet carrier rotating speed standard quantity nst _ soll again, and judging whether the reassigned first planet carrier rotating speed standard quantity nst _ soll is smaller than the first planet carrier rotating speed minimum value nst_minIf not, re-executing the step ii; if yes, subtracting a second preset value from the current outer gear ring torque standard quantity THo _ soll _ MC, then reassigning the value to the outer gear ring torque standard quantity THo _ soll _ MC, judging whether the reassigned outer gear ring torque standard quantity THo _ soll _ MC is smaller than the difference value between the minimum value allowed by the outer gear ring torque and a sixth preset value, and if yes, executing the step v; if not, re-executing the step ii;

and v, changing the target rotating speed of the half shaft, obtaining all corresponding first planet carrier rotating speeds, outer gear ring torques, outer gear ring rotating speeds and system efficiencies under different target rotating speeds of the half shaft according to the steps i-iv, selecting the highest system efficiency under the combination of the rotating speeds of the outer gear rings and the outer gear ring torques and the first planet carrier rotating speed corresponding to the highest system efficiency, and establishing a three-dimensional correspondence table of the rotating speeds of the outer gear rings, the torques of the outer gear rings and the system efficiency and a three-dimensional correspondence table of the rotating speeds of the outer gear rings, the torques of the outer gear rings and the first planet carrier rotating speeds by using the selected data.

2. The method for calibrating the pure electric gear shift point of the hybrid electric vehicle as claimed in claim 1, characterized in that: if a single pure electric drive mode exists in a certain working condition, the pure electric drive mode is selected for the working condition; if more than two pure electric driving modes exist in a certain working condition and the system efficiency is different when the working condition adopts different pure electric driving modes, the pure electric driving mode with higher system efficiency is selected in the working condition; if more than two pure electric driving modes exist in a certain working condition and the system efficiency is the same when any pure electric driving mode is adopted in the working condition, a transition gear shifting point is set in the working condition.

3. The method for calibrating the pure electric gear shifting point of the hybrid electric vehicle as claimed in claim 1 or 2, characterized in that: the first preset value is 25-35N, the second preset value is 45-55N, the third preset value is 790-810N, the fourth preset value is 370-390N, the fifth preset value is 25-35 rpm, the sixth preset value is 270-290N, the first preset temperature is 115-125 ℃, and the second preset temperature is 75-85 ℃.

Technical Field

The invention relates to a method for calibrating a pure electric drive mode shift point of a hybrid electric vehicle.

Background

During the driving process of the hybrid electric vehicle, gear switching can be performed according to the working condition and the intention of a driver, correspondingly, the working mode of a hybrid electric system used by the hybrid electric vehicle is correspondingly changed, and for switching among different working modes, torque distribution can be related, whether the torque distribution is proper or not can be related, and finally the system efficiency of the power system and the oil consumption of the whole vehicle can be influenced. In order to optimize the system efficiency of the powertrain at the time of shifting, it is necessary to consider the shift points, and how to determine the shift points of each drive mode is a current research subject.

Disclosure of Invention

The invention aims to provide a simple and feasible method for calibrating the pure electric drive mode shift point of a hybrid electric vehicle, so that the optimal efficiency of a power system under the running working condition of the hybrid electric vehicle is ensured, and the efficiency loss is reduced.

The invention is realized by the following scheme:

a method for calibrating a shift point of a pure electric drive mode of a hybrid electric vehicle is carried out according to the following conditions:

the calibration method of the EV-1 driving mode shift point specifically comprises the following steps:

s1 setting the running mode of the vehicle to be EV-1 driving mode in INCA-F L OW software, increasing the rotation speed of the half shaft to the target rotation speed of the half shaft, and setting the target torque THo _ Set of the outer gear ring and the maximum Value TB1 of the locking torque of the first brake by a Set Value tool_maxThe external gear ring torque nominal quantity THo _ soll _ MC and the first brake locking torque nominal quantity TB1_ soll are assigned respectively, and then the step S2 is executed;

s2 measures and records a first brake locking torque TB1, an outer gear ring torque THo, an outer gear ring rotating speed nHo and system Efficiency Sys _ Effecieny in real time within a Set time, calculates average values of the first brake locking torque, the outer gear ring rotating speed and the system Efficiency respectively, writes the average values into an Excel table through an Excel Write tool, takes the average values of the first brake locking torque, the outer gear ring rotating speed and the system Efficiency as a Set of corresponding first brake locking torque, outer gear ring rotating speed and system Efficiency under the half-shaft target rotating speed, assigns the current values of a first brake locking torque standard quantity TB1_ soll and an outer gear ring torque standard quantity THo _ soll _ MC to a constant A and a constant B through a Set Value tool respectively, and then executes a step S3;

s3, judging whether the current temperatures of the small motor (E1) and the large motor (E2) are both lower than a first preset temperature, if so, executing a step S4; if not, removing the first brake locking torque standard quantity TB1_ soll and the outer gear ring torque standard quantity THo _ soll _ MC, namely, enabling the first brake locking torque standard quantity TB1_ soll and the outer gear ring torque standard quantity THo _ soll _ MC to return to zero, waiting for the small motor and the large motor to cool down, enabling the second preset temperature to be smaller than the first preset temperature when the temperatures of the small motor and the large motor are both smaller than the second preset temperature, respectively assigning the values of the constant A and the constant B to the first brake locking torque standard quantity TB1_ soll and the outer gear ring torque standard quantity THo _ soll _ MC, and then executing the step S2 again;

s4 reassigns the current first brake locking torque nominal quantity TB1soll to the first brake locking torque nominal quantity TB1_ soll after subtracting the first preset value, and judges whether the reassigned first brake locking torque nominal quantity TB1soll is smaller than the first brake locking torque minimum value TB1_minIf not, re-executing step S2; if yes, subtracting a second preset value from the current outer gear ring torque standard quantity THo _ soll _ MC, then reassigning the value to the outer gear ring torque standard quantity THo _ soll _ MC, judging whether the reassigned outer gear ring torque standard quantity THo _ soll _ MC is smaller than the difference value between the minimum value allowed by the outer gear ring torque and a third preset value, and if yes, executing a step S5; if not, re-executing step S2;

s5, changing the target rotation speed of the half shaft, obtaining all corresponding first brake locking torques, external gear ring rotation speeds and system efficiencies under different target rotation speeds of the half shaft according to the steps S1-S4, selecting the highest system efficiency under the combination of the rotation speed of each external gear ring and the torque of each external gear ring and the first brake locking torque corresponding to the highest system efficiency, and establishing a three-dimensional correspondence table of the rotation speed of the external gear ring, the torque of the external gear ring and the system efficiency and a three-dimensional correspondence table of the rotation speed of the external gear ring, the torque of the external gear ring and the first brake locking torque under the EV-1 driving mode by using the selected data;

the calibration method of the EV-2 driving mode shift point is specifically carried out according to the following steps:

(a) setting the vehicle running mode to be an EV-2 driving mode in the INCA-F L OW software, then increasing the rotation speed of the half shaft to the target rotation speed of the half shaft, assigning the target torque THo _ Set of the outer gear ring to the calibrated amount THo _ soll _ MC of the outer gear ring through a Set Value tool, and then executing the step (b) again;

(b) measuring and recording the external gear ring torque THo, the external gear ring rotating speed nHo and the system Efficiency Sys _ Efficiency in real time within a set time, respectively calculating average values of the external gear ring torque, the external gear ring rotating speed and the system Efficiency, writing the average values into an Excel table through an Excel write tool, taking the average values of the external gear ring torque, the external gear ring rotating speed and the system Efficiency as a set of corresponding external gear ring torque, external gear ring rotating speed and system Efficiency at the target rotating speed of the half shaft, and then executing the step (c);

(c) judging whether the temperatures of the current small motor (E1) and the current large motor (E2) are both lower than a first preset temperature, if so, executing the step (d); if not, removing the outer gear ring torque standard quantity THo _ soll _ MC, namely enabling the outer gear ring torque standard quantity THo _ soll _ MC to return to zero, waiting for the small motor and the large motor to cool down, and when the temperatures of the small motor and the large motor are both lower than a second preset temperature, enabling the second preset temperature to be lower than the first preset temperature, and executing the step (b) again;

(d) subtracting a second preset value from the current outer gear ring torque standard quantity THo _ soll _ MC, then reassigning the value to the outer gear ring torque standard quantity THo _ soll _ MC, judging whether the reassigned outer gear ring torque standard quantity THo _ soll _ MC is smaller than the difference value between the outer gear ring torque allowable minimum value and a fourth preset value, and if so, executing the step (e); if not, re-executing the step (b);

(e) changing the target rotating speed of the half shaft, obtaining the torque of the outer gear ring, the rotating speed of the outer gear ring and the system efficiency corresponding to the target rotating speeds of different half shafts according to the steps (a) - (d), and establishing a three-dimensional corresponding table of the torque of the outer gear ring, the rotating speed of the outer gear ring and the system efficiency in the EV-2 driving mode;

the calibration method of the EV-3 driving mode gear shifting point is specifically carried out according to the following steps:

i setting the running mode of the vehicle to be an EV-3 driving mode in INCA-F L OW software, increasing the rotating speed of a half shaft to a target rotating speed of the half shaft, and using a Set Value tool to increase the target torque THo _ Set of the outer gear ring and the maximum rotating speed nst of the first planet carrier_maxCorrespondingly assigning a torque standard quantity THo _ soll _ MC of the outer gear ring and a rotating speed standard quantity nst _ soll of the first planet carrier, and then executing the step ii;

ii, measuring and recording the first planet carrier rotating speed nst, the outer gear ring torque THo, the outer gear ring rotating speed nHo and the system Efficiency Sys _ Efficiency in real time within a Set time, respectively calculating average values of the first planet carrier rotating speed, the outer gear ring torque, the outer gear ring rotating speed and the system Efficiency, writing the average values into an Excel table through an Excel Write tool, taking the average values of the first planet carrier rotating speed, the outer gear ring torque, the outer gear ring rotating speed and the system Efficiency as a Set of corresponding first brake locking torque, outer gear ring rotating speed and system Efficiency under the half-shaft target rotating speed, respectively assigning the current values of the first planet carrier rotating speed standard quantity nst _ soll and the outer gear ring torque standard quantity THo _ solo _ MC to a constant A and a constant B through a Set Value tool, and then executing a step iii;

iii, judging whether the temperatures of the current small motor (E1) and the current large motor (E2) are both lower than a first preset temperature, if so, executing a step iv; if not, removing the first planet carrier rotating speed standard quantity nst _ soll and the outer gear ring torque standard quantity THo _ soll _ MC, namely the first planet carrier rotating speed standard quantity nst _ soll and the outer gear ring torque standard quantity THo _ soll _ MC are reset to zero, waiting for the small motor and the large motor to be cooled, when the temperatures of the small motor and the large motor are both lower than a second preset temperature, the second preset temperature is lower than the first preset temperature, respectively assigning the values of the constant A and the constant B to the first planet carrier rotating speed standard quantity nst _ soll and the outer gear ring torque standard quantity THo _ soll _ MC, and then executing the step ii again;

iv, subtracting a fifth preset value from the current first planet carrier rotating speed standard quantity nst _ soll, then assigning the value to the first planet carrier rotating speed standard quantity nst _ soll again, and judging whether the reassigned first planet carrier rotating speed standard quantity nst _ soll is smaller than the first planet carrier rotating speed minimum value nst_minIf not, re-executing the step ii; if yes, subtracting a second preset value from the current outer gear ring torque standard quantity THo _ soll _ MC, then reassigning the value to the outer gear ring torque standard quantity THo _ soll _ MC, judging whether the reassigned outer gear ring torque standard quantity THo _ soll _ MC is smaller than the difference value between the minimum value allowed by the outer gear ring torque and a sixth preset value, and if yes, executing the step v; if not, re-executing the step ii;

and v, changing the target rotating speed of the half shaft, obtaining all corresponding first planet carrier rotating speeds, outer gear ring torques, outer gear ring rotating speeds and system efficiencies under different target rotating speeds of the half shaft according to the steps i-iv, selecting the highest system efficiency under the combination of the rotating speeds of the outer gear rings and the outer gear ring torques and the first planet carrier rotating speed corresponding to the highest system efficiency, and establishing a three-dimensional correspondence table of the rotating speeds of the outer gear rings, the torques of the outer gear rings and the system efficiency and a three-dimensional correspondence table of the rotating speeds of the outer gear rings, the torques of the outer gear rings and the first planet carrier rotating speeds by using the selected data.

Further, if a single pure electric drive mode exists in a certain working condition, the pure electric drive mode is selected for the working condition; if more than two pure electric driving modes exist in a certain working condition and the system efficiency is different when the working condition adopts different pure electric driving modes, the pure electric driving mode with higher system efficiency is selected in the working condition; if more than two pure electric driving modes exist in a certain working condition and the system efficiency is the same when any pure electric driving mode is adopted in the working condition, a transition gear shifting point is arranged in the working condition, and one pure electric driving mode can be selected at the transition gear shifting point according to specific conditions.

Further, the first preset value is 25-35N, the second preset value is 45-55N, the third preset value is 790-810N, the fourth preset value is 370-390N, the fifth preset value is 25-35 rpm, the sixth preset value is 270-290N, the first preset temperature is 115-125 ℃, and the second preset temperature is 75-85 ℃.

The calculation formula of the system efficiency is designed according to the structure of the used hybrid power transmission system, and is pre-stored in a test program, so that the system efficiency can be calculated and recorded in real time. The value range of the target rotating speed of the half shaft is obtained by conversion according to the prior art according to the value range of the rotating speed of the outer gear ring.

The method for calibrating the shift points of the pure electric driving mode of the hybrid electric vehicle is simple and feasible, the shift points with the optimal system efficiency of different pure electric driving modes are obtained through comprehensive sweeping point-to-point comparison, the accuracy is high, the optimal power system efficiency of the running working condition of the hybrid electric vehicle is ensured, and the efficiency loss is reduced.

Drawings

Fig. 1 is a schematic configuration diagram of a hybrid power transmission system used in the present invention.

Detailed Description

The invention is further illustrated by the following figures and examples, but the invention is not limited to the examples.

The structure of the hybrid power transmission system used in the present invention is schematically shown in fig. 1, and its main components include a planetary gear coupling mechanism composed of a small electric machine E1, a large electric machine E2, a first brake B1, a first clutch C0, a second clutch C1, a first single planetary row PG1 and a second single planetary row PG2, and a third single planetary row PG3, the first single planetary row PG1 includes a first planet carrier PC1, a first planet carrier P1, a first sun gear S1 and a first ring gear R1, the second single planetary row PG1 includes a second planet carrier PC1, a second planet carrier P1, a second sun gear S1 and a second ring gear R1, the first sun gear S1 of the first single planetary row PG1 is connected to the first rotor shaft 2 of the small electric machine E1, the second sun gear S1 of the second single planetary row PG1 is connected to the second sun gear S1 of the large electric machine E1, the third planet carrier P1 and the third planet carrier 1, the input shaft 1 is connected with an output shaft of an engine ICE, one end of a first clutch C0 is connected with a first planet carrier PC1, and the other end of a first clutch C0 is connected with the input shaft 1; one end of a second clutch C1 is connected to the second rotor shaft 3 of the large electric machine E2, the other end of the second clutch C1 is connected to the input shaft 1, one end of a first brake B1 is connected to the first carrier PC1, and one end of a second brake B2 is connected to the first rotor shaft 2 of the small electric machine E1. The structure of the hybrid power transmission system used in the present invention has been disclosed in a transmission for a front-drive hybrid vehicle (publication No. CN 108105358A).

The hybrid power transmission system used in the present invention has a plurality of drive modes, and the control relationship between each drive mode and the shift element is shown in table 1, where good represents an open state and ● represents a closed state.

TABLE 1 control relationship between drive modes and shift elements

Drive mode	C0	C1	B1	B2
					EV-1	〇	〇	●	〇
EV-2	〇	〇	〇	●
					EV-3	〇	〇	〇	〇
EV-1RD	〇	〇	●	〇
					HEV-1	〇	●	〇	〇
HEV-2	〇	●	●	〇
					HEV-3	〇	●	〇	●
HEV-4	●	〇	〇	〇
					HEV-5	●	〇	〇	●
HEV-6	●	●	〇	〇

The first gear pure electric drive mode (EV-1 drive mode for short) is the pure electric drive mode with the best low-speed power property and is used for accelerating a low-speed large throttle; the second gear pure electric drive mode (EV-2 drive mode for short) is mainly used for accelerating a small accelerator, the application range of the vehicle speed is wide, the vehicle speed range from static to a vehicle speed range exceeding 120kmh can be covered, the rotating speed of a large motor E2 is increased along with the increase of the vehicle speed, the torque of an outer gear ring, namely the output torque is reduced, the dynamic property is reduced, and the cooling flow of a small motor E1 is wasted; the third gear pure electric drive mode (EV-3 drive mode for short) is used for high vehicle speed, the rotating speeds of the small motor E1 and the large motor E2 are low, the maximum torques of the small motor E1 and the large motor E2 are relatively large, and the cooling flows of the small motor E1 and the large motor E2 are not wasted.