阅读说明：本技术 一种电动汽车双电机驱动系统及其功率耦合综合控制方法 (Electric automobile double-motor driving system and power coupling comprehensive control method thereof ) 是由 田晋跃 盛家炜 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种电动汽车双电机驱动系统及其功率耦合综合控制方法,通过采用电动汽车双电机驱动系统,通过行星齿轮机构的动力耦合方式,实现电动汽车驱动系统的在不同工况下的转矩和转速耦合,双电机驱动系统具有功率分流型的可以实现连续调速和调矩的传动调节功能,能有效调节电动汽车电机工作状态,提高电机效率,且本发明功率耦合综合控制方法在需求转速和转矩一定的情况下,匹配工作模式,制定经济性控制策略,对双电机转速和转矩进行分配,使双电机工作在高能效状态,实现中低负荷经济性换挡、中高负荷动力性换挡的综合型换挡控制策略。(The invention discloses a double-motor driving system of an electric automobile and a power coupling comprehensive control method thereof, wherein the torque and the rotating speed coupling of the electric automobile driving system under different working conditions is realized by adopting the double-motor driving system of the electric automobile and a power coupling mode of a planetary gear mechanism, the double-motor driving system has a power split type transmission adjusting function capable of realizing continuous speed regulation and torque regulation, the working state of a motor of the electric automobile can be effectively adjusted, and the efficiency of the motor is improved.)

1. The double-motor driving system of the electric automobile is characterized by comprising a vehicle control unit, wherein the vehicle control unit is respectively connected with a motor A (1) and a motor B (5), and power transmission is realized between an output shaft A (2) of the motor A (1) and a coupling unit through a driving gear A (3); an output shaft of the motor B (5) is connected with a transmission shaft (7) through a gear; inputting the power of the motor B (5) into a commutator (8); the power is transmitted with the coupling unit through the commutator (8).

2. The dual-motor driving system of the electric vehicle as claimed in claim 1, wherein the vehicle control unit comprises a torque and speed requirement calculation module, an output end of the torque and speed requirement calculation module is connected to the operation mode determination module, an output end of the operation mode determination module is connected to the torque and speed distribution module, and the torque and speed distribution module is respectively connected to the motor a (1) and the motor B (5).

3. The electric vehicle dual-motor driving system as claimed in claim 2, wherein the torque and speed demand calculation module is configured to receive vehicle status information, motor status information, battery status information, and the like, wherein the vehicle status information includes vehicle speed and gradient; the motor state information comprises rotating speed and torque.

4. The dual-motor driving system of the electric automobile according to claim 3, wherein the coupling unit comprises a driven gear A (9), one end of the driven gear A (9) is engaged with the driving gear A (3), the other end of the driven gear A is engaged with the driving gear A, the planetary gear (12) inside the driving gear A (11) is engaged with the sun gear (14) for transmission, the input shaft of the sun gear (14) is connected with the commutator (8), the planet carrier (13) of the planetary gear (12) is used as the output of the coupling unit, the shaft of the planet carrier (13) transmits the output power to the differential mechanism (10) through the gear pair, and the differential mechanism (10) is connected with the output half shaft for transmitting the power to the left and right driving tires.

5. The power coupling comprehensive control method of the double-motor driving system of the electric automobile based on claim 4 is characterized by comprising the following steps of:

step 1, collecting the change rate of an accelerator pedal, comparing the change rate of the accelerator pedal with a set change rate threshold value delta of the accelerator pedal, and judging whether the change rate of the accelerator pedal is larger than the set change rate threshold value delta of the accelerator pedal according to a judgment result<Delta, indicating that the vehicle runs smoothly, turning to step 2, otherwise indicating that the vehicle is in an acceleration state and needing to provide the compensation torque T_add1；

Step 2, obtaining the gradient according to the condition of the running road, comparing the gradient with a gradient threshold value theta, and judging whether the gradient is the same or not according to the judgment result<Theta, then calculating the basic torque T required by the vehicle_bThe real-time control of the electric automobile is realized; otherwise, the vehicle is in a climbing state, and the compensation torque T needs to be provided for obtaining good dynamic performance_add2；

Step 3, calculating compensation torque according to the battery information, the motor state information and the vehicle running state information of the vehicle, and passing the compensation torque T_add1To the baseTorque T_bCompensation is carried out to obtain the required torque T_req；

Step 4, according to the required torque T_reqAnd selecting an optimal working mode.

6. The power coupling comprehensive control method of the double-motor driving system of the electric automobile as claimed in claim 5, wherein the required torque T is obtained in the step 3_reqThe method comprises the following steps:

step 3.1, the compensation torque set for the accelerator pedal should satisfy: t is_add1＝(T_vmax-T_b(k) A), wherein, T_add1Indicating a sudden acceleration compensation torque, T_vmaxRepresenting the maximum torque, T, that can be provided at vehicle speed v_b(k) The basic torque corresponding to the condition that the opening degree of an accelerator pedal is k under the vehicle speed v is shown, and a shows the coefficient of the change rate of the opening degree of the accelerator pedal;

step 3.2, the compensation torque during climbing is as follows: t is_add2＝(T_vmax-T_b(k) B), wherein b is a gradient coefficient;

step 3.3, collecting battery information of the vehicle, wherein the battery information of the vehicle comprises the temperature and the residual electric quantity of the battery; if the temperature of the battery is less than T and the residual capacity is more than T, the battery capacity is sufficient;

and 3.5, calculating the basic torque and the additional torque of the electric automobile to obtain the real-time required torque of the dual-motor power system: t is_req＝T_b+T_add＝T_b+(T_vmax-T_b(k))*(a+b)。

7. The power coupling comprehensive control method of the double-motor driving system of the electric automobile according to claim 5 or 6, characterized in that the method for selecting the optimal operation mode in the step 4 comprises the following steps:

and obtaining the highest rotating speed and the maximum torque according to the target vehicle speed, the pedal opening and the required torque, screening the working modes based on the highest rotating speed and the maximum torque, namely selecting the minimum energy consumption mode through mode energy consumption calculation, namely selecting the corresponding point of the equivalent driving force diagram as the optimal working condition mode.

Technical Field

The invention belongs to the technical field of electric automobile transmission drive control, and particularly relates to a double-motor drive system of an electric automobile and a power coupling comprehensive control method thereof.

Background

The efficiency of the motor of the electric automobile is improved in the driving process, the endurance mileage of the electric automobile can be effectively improved, the efficiency of the motor is higher near the rated rotating speed of the motor according to the efficiency distribution condition of the motor, the efficiency is lower in a high-speed interval and a low-speed interval, and the difference can reach about 30% at most, so that the energy efficiency of the motor can be effectively improved by adjusting the working interval of the motor.

The patent of application No. 201710095652.1 describes a dual-motor driving system and a control method for an electric vehicle, which comprises a vehicle signal unit, a vehicle controller, a first motor controller, a second motor controller, a low-speed driving motor and a high-speed driving motor; the vehicle signal unit is used for transmitting a vehicle signal to the whole vehicle controller; the vehicle controller identifies a driver's command according to the received vehicle signal and determines control commands transmitted to the first motor controller and the second motor controller according to the comparison of the vehicle speed with thresholds V1, V2 and V3, wherein V1< V2< V3; when the vehicle speed is lower than the speed V1, the vehicle control unit controls the low-speed driving motor to operate through the first motor controller; when the vehicle speed is greater than V1 and less than V2, the vehicle control unit controls the low-speed driving motor and the high-speed driving motor to operate simultaneously through the first motor controller and the second motor controller; when the vehicle speed is greater than V2, the vehicle control unit controls the high-speed driving motor to operate through the second motor controller. The driving scheme provided by the patent has no power coupling, and the vehicle is provided with two independent driving systems, namely, the vehicle can realize low-speed walking and the vehicle can realize high-speed walking. The switching of the two systems is simple.

The patent of application No. 201811626223.3 describes a dual-motor driving system of an electric vehicle and a control method thereof, the system comprises a main driving battery, a first integrated controller, a first driving motor, a second integrated controller, a second driving motor and a dual-input reduction gearbox, and the ratio of the reduction ratios of a low-speed gear and a high-speed gear in the dual-input reduction gearbox is 2-3; the control method is characterized in that one high-speed motor is responsible for low-speed and high-current running through differential speed of two input shafts and matching with a corresponding control strategy, so that the problem of low speed and high current is solved, the cargo carrying capacity and climbing capacity of a vehicle are improved, and the other high-speed motor is responsible for high-speed running so as to give consideration to the efficiency of low-speed and high-torque output and high-speed running. The problem of the power consumption efficiency that current motor direct drive formula low-speed four-wheel car exists is too low is solved. The patent is difficult to implement in engineering from structural analysis, the two motors are coupled by adopting shafts, torque interference exists between the two motors, and power transmission is difficult.

The patent of application No. 201721345995.0 describes a dual-motor drive system for a pure electric vehicle, comprising: two motors with driving and driven gears, two synchronous mechanisms with combined gears, two output shafts, two gear driven gears, an intermediate shaft with a transmission gear and a differential mechanism, wherein gear hubs of the two synchronous mechanisms are respectively fixedly connected with the driven gears of the first motor and the second motor and are sleeved on the first output shaft and the second output shaft in a hollow way, one end of each of the two synchronous mechanisms is a combined gear fixedly connected with the output shaft, the other end of each of the two synchronous mechanisms is a combined gear serving as an EV gear driving gear, the differential mechanism comprises a first-gear EV driving gear and a second-gear EV driving gear, wherein the first-gear EV driving gear and the second-gear EV driving gear are respectively sleeved on a first output shaft and a second output shaft in a hollow mode, a second-gear driven gear is fixedly arranged on the first output shaft and meshed with a transmission gear of an intermediate shaft, a first-gear driven gear is fixedly arranged on the intermediate shaft, and the differential mechanism is respectively meshed with two synchronous mechanisms through a main speed reduction driving gear. Two motors of the patent work independently, realize the conversion of power through two synchronizers, the structure is redundant, and it is relatively complicated to control, can not realize the distribution of power according to the road surface operating mode automatically.

In order to give consideration to higher maximum speed per hour and larger climbing gradient, most of electric automobiles adopt a power system form of a motor with larger power and a single-stage speed reducer, and a control system of the power system is simpler. The driving mode of adopting the single motor and the single-stage speed reducer can cause the working interval of the motor to change greatly along with the driving working condition and can not be concentrated in the high-efficiency interval, so that the driving force system has lower efficiency under the comprehensive working condition operation condition.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides a double-motor driving and power coupling system of an electric vehicle and a comprehensive control method thereof.

The technical scheme adopted by the invention is as follows:

a double-motor driving system of an electric automobile comprises a vehicle control unit, wherein the vehicle control unit is respectively connected with a motor A and a motor B, and power transmission is realized between an output shaft A of the motor A and a coupling unit through a driving gear A; an output shaft of the motor B is connected with a transmission shaft through a gear; inputting the power of the motor B into the commutator; power transmission is carried out between the commutator and the coupling unit;

further, the vehicle control unit comprises a torque and rotation speed demand calculation module, wherein the output end of the torque and rotation speed demand calculation module is connected with a working mode determination module, the output end of the working mode determination module is connected with a torque and rotation speed distribution module, and the torque and rotation speed distribution module is respectively connected with a motor A and a motor B;

further, the torque and rotation speed demand calculation module is used for receiving information such as vehicle state information, motor state information and battery state, wherein the vehicle state information comprises vehicle speed and gradient; the motor state information comprises rotating speed and torque;

furthermore, the coupling unit comprises a driven gear A, one end of the driven gear A is meshed with the driving gear A, the other end of the driven gear A passes through a gear ring, a planetary gear in the gear ring is meshed with a sun gear for transmission, an input shaft of the sun gear is connected with a commutator, a planetary carrier of the planetary gear is used as the output of the coupling unit, the shaft of the planetary carrier transmits the output power to a differential mechanism through a gear pair, and the differential mechanism is connected with an output half shaft and transmits the power to left and right driving tires;

a power coupling comprehensive control method of a double-motor driving system of an electric automobile comprises the following steps:

step 1, collecting the change rate of an accelerator pedal, comparing the change rate of the accelerator pedal with a set change rate threshold value delta of the accelerator pedal, and judging whether the change rate of the accelerator pedal is larger than the set change rate threshold value delta of the accelerator pedal according to a judgment result<Delta, indicating that the vehicle runs smoothly, turning to step 2, otherwise indicating that the vehicle is in an acceleration state and needing to provide the compensation torque T_add1；

Step 2, obtaining the gradient according to the condition of the running road, comparing the gradient with a gradient threshold value theta, and judging whether the gradient is the same or not according to the judgment result<Theta, then calculating the basic torque T required by the vehicle_bThe real-time control of the electric automobile is realized; otherwise, the vehicle is in a climbing state, and the compensation torque T needs to be provided for obtaining good dynamic performance_add2；

Step 3, calculating compensation torque according to the battery information, the motor state information and the vehicle running state information of the vehicle, and passing the compensation torque T_add1For basic torque T_bCompensation is carried out to obtain the required torque T_req；

Step 4, according to the required torque T_reqAnd selecting an optimal working mode.

Further, the required torque T is obtained in the step 3_reqThe method comprises the following steps:

step 3.1, the compensation torque set for the accelerator pedal is to be satisfied

T_add1＝(T_vmax-T_b(k))*a

Wherein, T_add1Indicating a sudden acceleration compensation torque, T_vmaxRepresenting the maximum torque, T, that can be provided at vehicle speed v_b(k) The basic torque corresponding to the condition that the opening degree of an accelerator pedal is k under the vehicle speed v is shown, and a shows the coefficient of the change rate of the opening degree of the accelerator pedal;

step 3.2, the compensation torque during climbing is as follows:

T_add2＝(T_vmax-T_b(k))*b

wherein b is a gradient coefficient;

step 3.3, collecting battery information of the vehicle, wherein the battery information of the vehicle comprises the temperature and the residual electric quantity of the battery; if the temperature of the battery is less than T and the residual capacity is more than T, the battery capacity is sufficient;

and 3.5, calculating the basic torque and the additional torque of the electric automobile to obtain the real-time required torque of the dual-motor power system:

T_req＝T_b+T_add＝T_b+(T_vmax-T_b(k))*(a+b)。

further, the method for selecting the optimal working mode in the step 4 comprises the following steps: and obtaining the highest rotating speed and the maximum torque according to the target vehicle speed, the pedal opening and the required torque, screening the working modes based on the highest rotating speed and the maximum torque, namely selecting the minimum energy consumption mode through mode energy consumption calculation, namely selecting the corresponding point of the equivalent driving force diagram as the optimal working condition mode.

The invention has the beneficial effects that:

1. the invention provides a novel coupling configuration of a double-motor power system of a pure electric vehicle, which meets the torque requirement of the electric vehicle during climbing and the rotating speed requirement of the electric vehicle during high speed through power coupling of double motors in different modes. The problem that the contradiction between the climbing performance and the high-speed performance cannot be simultaneously met by adopting a low-power single-motor fixed transmission ratio mode and the problem that the energy utilization rate is low by adopting a high-power motor is solved.

2. The double-motor power system has a plurality of working modes of single working of double motors, torque coupling working, rotating speed coupling working and the like, under the condition that the required rotating speed and torque are constant, the working modes are matched, an economic control strategy is formulated, the rotating speed and the torque of the double motors are distributed, the double motors work in a high-energy-efficiency state, the energy efficiency of the electric automobile is improved, and the comprehensive gear shifting control strategy of low-load economic gear shifting and medium-load dynamic gear shifting is realized on the basis of a motor efficiency contour map and an accelerator pedal opening output curve.

Drawings

FIG. 1 is a schematic view of a dual motor power drive system of the present invention;

FIG. 2 is a schematic diagram of a dual motor power system configuration according to the present invention;

FIG. 3 is a schematic diagram of a power coupling unit according to the present invention;

FIG. 4 is a flow chart of the calculation of the requested torque for the dual motor power system of the present invention;

FIG. 5 is a flow chart of mode division of a dual-motor power system based on the principle of least energy consumption of an electric vehicle;

FIG. 6 is a schematic diagram of dividing equivalent driving force diagram corresponding points into optimal working condition modes;

in the figure, 1, a motor A, 2, an output shaft A, 3, a driving gear A, 4, a driving gear B, 5, a motor B, 6, a driven gear B, 7, a transmission shaft 8, a commutator 9, a driven gear A, 10, a differential mechanism, 11, a gear ring, 12, a planet wheel, 13, a planet carrier, 14 and a sun wheel.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1 and 2, the dual-motor driving system of the electric vehicle designed by the invention comprises a vehicle controller, wherein the vehicle controller comprises a torque and rotation speed demand calculation module, and the torque and rotation speed demand calculation module is used for receiving information such as vehicle state information (vehicle speed, gradient), motor state information (rotation speed and torque) and battery state; the output end of the torque and rotation speed requirement calculation module is connected with the working mode determination module, the output end of the working mode determination module is connected with the torque and rotation speed distribution module, and the torque and rotation speed distribution module is respectively connected with a motor A1 and a motor B5; the output shaft A2 of the motor A1 is provided with a driving gear A3; a driving gear B4 is mounted on an output shaft of the motor B5, a driving gear B4 is in meshed transmission with a driven gear B6, the driven gear B6 is sleeved on the transmission shaft 7, and the transmission shaft 7 is connected with the commutator 8.

As shown in fig. 3, the coupling unit includes a driven gear a9, one end of the driven gear a9 is engaged with the driving gear A3, the other end is a ring gear 11, the planetary gears 12 inside the ring gear 11 are engaged with the sun gear 14 for transmission, the input shaft of the sun gear 14 is connected with the commutator 8, the planet carrier 13 of the planetary gears 12 is used as the output of the coupling unit, the shaft of the planet carrier 13 transmits the output power to the differential 10 through the gear pair, and the differential 10 is connected with the output half shaft for transmitting the power to the left and right driving tires.

A power coupling comprehensive control method of a double-motor driving system of an electric automobile comprises the following steps:

step 1, collecting the change rate of an accelerator pedal, comparing the change rate of the accelerator pedal with a set change rate threshold value delta of the accelerator pedal, and judging whether the change rate of the accelerator pedal is larger than the set change rate threshold value delta of the accelerator pedal according to a judgment result<Delta, indicating that the vehicle runs smoothly, turning to step 2, otherwise indicating that the vehicle is in an acceleration state and needing to provide the compensation torque T_add1；

Step 2, obtaining the gradient according to the running road condition, and combining the gradient and the rampComparing the threshold value theta, and judging if the gradient is the same according to the judgment result<Theta, then calculating the basic torque T required by the vehicle_bThe real-time control of the electric automobile is realized; otherwise, the vehicle is in a climbing state, and the compensation torque T needs to be provided for obtaining good dynamic performance_add2；

Step 3, calculating compensation torque according to the battery information, the motor state information and the vehicle running state information of the vehicle, and passing the compensation torque T_add1For basic torque T_bCompensation is carried out to obtain the required torque:

T_req＝T_b+T_add＝T_b+(T_vmax-T_b(k))*(a+b)

and finally, the required torque of the vehicle is obtained to realize the real-time control of the electric automobile.

The required torque T is obtained in step 3_reqThe method comprises the following steps:

step 3.1, pedal information: considering the characteristics that the torque compensation is larger at low speed and is properly reduced at high speed when the automobile runs, the compensation torque set for the accelerator pedal is satisfied

T_add1＝(T_vmax-T_b(k))*a

Wherein, T_add1Indicating a sudden acceleration compensation torque, T_vmaxRepresenting the maximum torque, T, that can be provided at vehicle speed v_b(k) The reference torque represents a base torque corresponding to a vehicle speed v at which the accelerator opening is k, and a represents an accelerator opening change rate coefficient.

Step 3.2, road information: carry out suitable compensation to basic torque in real time according to the road ramp condition, will be favorable to improving electric automobile's driving comfort, compensation torque when climbing is:

T_add2＝(T_vmax-T_b(k))*b

wherein b is a gradient coefficient.

Step 3.3, collecting battery information of the vehicle, wherein the battery information of the vehicle comprises the temperature and the residual electric quantity of the battery; if the temperature of the battery is < T and the remaining power is > T, it indicates that the battery is sufficiently charged. The large compensation torque easily causes the battery to discharge too fast, reduces the endurance mileage of the electric automobile, and meanwhile, when the discharge current is too large, the battery temperature is too high, the battery load is increased, and the service life of the battery is influenced.

Step 3.4, motor information: as can be seen from the analysis of the motor efficiency MAP, when the motor load factor exceeds 60%, the motor efficiency is likely to be decreased by performing the torque compensation.

And 3.5, therefore, the real-time required torque of the dual-motor power system can be obtained by calculating the basic torque and the additional torque of the electric automobile:

T_req＝T_b+T_add＝T_b+(T_vmax-T_b(k))*(a+b)。

and 4, the rotating speed and torque requirements of the electric automobile under different working conditions can be met through the cooperative work of the four working modes, the working intervals of the working modes are reasonably divided, the improvement of the planned energy efficiency of the electric automobile is facilitated, and the driving range is increased. Therefore, the mode division is performed on the dual-motor power system based on the principle of least energy consumption of the electric vehicle, and a specific flowchart is shown in fig. 5: and obtaining the highest rotating speed and the maximum torque according to the target vehicle speed, the pedal opening and the required torque, screening the working modes based on the highest rotating speed and the maximum torque, namely selecting the minimum energy consumption mode, namely the optimal working condition mode of the corresponding point of the equivalent driving force diagram through mode energy consumption calculation. The specific division condition of the optimal working condition mode of the corresponding points of the equivalent driving force diagram is shown in figure 6, and when the vehicle speed is lower than 21km/h and the torque is greater than 12 x v, a first working mode is selected; selecting a second working mode when the vehicle speed is lower than 29km/h and the torque is less than 12 v or the vehicle speed is 29-80km/h and the torque is less than 477-4.36 v; selecting a third mode when the vehicle speed is 21-51km/h and the torque demand is greater than 12 v, or the vehicle speed is 51-60km/h and the demand torque is greater than 22 v-879, or the vehicle speed is 60-101km/h and the torque is greater than 472-0.31 v; mode four is selected when vehicle speed is in the range of 60-86km/h and the requested torque is greater than 333-1.56 v and less than 472-0.31 v or vehicle speed is greater than 86km/h and torque is less than 472-0.31 v.

The specific working process of the 4 working modes of the structure is as follows:

the first working mode is as follows: the motor A1 works independently, at the moment, a shifting fork of the commutator 8 keeps neutral, the motor A1 is meshed with the driving gear A3, power is input from the driving gear A3, the transmission ratio is small at the moment according to the characteristics of a planetary gear, and the working point of the motor can be mostly positioned in the high-efficiency area of the motor when the motor works at a medium speed and a small torque.

And a second working mode: when the motor A1 does not work, the motor B5 works alone, the shifting fork of the commutator 8 moves rightwards at the moment to combine friction plates, the output power of the motor A2 is transmitted to the sun gear 14 through the commutator 8, and the power of the motor A2 is input from the sun gear 14. When the motor works under the working condition of low speed and large torque, the working point of the motor can be mostly positioned in the high-efficiency area of the motor.

And a third working mode: the motor A1 and the motor B5 are driven in a torque coupling mode, at the moment, a shifting fork of the commutator 8 moves leftwards, the power of the motor A1 is directly input through the driving gear A3, and the power of the motor B5 is transmitted to the gear ring through the commutator 8. When the motor works under the working condition of medium speed and large torque, the torques of the two motors can be adjusted to enable the motors to work in the interval with higher efficiency respectively.

And a fourth working mode: the motor A1 and the motor B5 are driven in a rotating speed coupling mode, at the moment, a shifting fork of the commutator 8 moves rightwards, the power of the motor A1 is directly input from a driving gear A3, and the output power of the motor B5 is transmitted to the sun gear 14 through the commutator 8 and is coupled through a planetary gear mechanism. When the motor works under the working condition of high speed and small torque, the rotating speeds of the two motors can be adjusted to enable the motors to work in the interval with higher efficiency respectively.

The invention adopts a double-motor driving system of the electric automobile, realizes the torque and rotating speed coupling of the driving system of the electric automobile under different working conditions by a power coupling mode of a planetary gear mechanism, has a power division type transmission adjusting function capable of realizing continuous speed and torque adjustment, can effectively adjust the working state of the motor of the electric automobile, and improves the efficiency of the motor.

Aiming at the problems, the invention discloses a power coupling comprehensive control method for a double-motor driving system of an electric automobile. The novel coupling configuration of the double-motor power system of the pure electric vehicle is provided, and the torque requirement when the electric vehicle climbs a slope and the rotating speed requirement when the electric vehicle is at a high speed are met through power coupling of double motors in different modes. The problem that the contradiction between the climbing performance and the high-speed performance cannot be simultaneously met by adopting a low-power single-motor fixed transmission ratio mode and the problem that the energy utilization rate is low by adopting a high-power motor is solved.

The double-motor power system has a plurality of working modes of single working of double motors, torque coupling working, rotating speed coupling working and the like, under the condition that the required rotating speed and torque are constant, the working modes are matched, an economic control strategy is formulated, the rotating speed and the torque of the double motors are distributed, the double motors work in a high-energy-efficiency state, the energy efficiency of the electric automobile is improved, and the comprehensive gear shifting control strategy of low-load economic gear shifting and medium-load dynamic gear shifting is realized on the basis of a motor efficiency contour map and an accelerator pedal opening output curve.

The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.