1. A torque distribution method of a dual motor system, wherein the dual motor system includes two mutually independent single motor systems, the method comprising:

acquiring the corresponding relation among the rotating speed, the torque and the power loss of each single motor system;

determining the maximum torque of each single motor system under different rotating speeds according to the corresponding relation among the rotating speed, the torque and the power loss of each single motor system, and determining the maximum torque of the double motor systems under different rotating speeds according to the maximum torque of each single motor system under different rotating speeds;

carrying out gridding processing on the maximum torque of the double-motor system at different rotating speeds to obtain a torque distribution combination and corresponding total power loss of the double-motor system at different rotating speeds;

determining a torque distribution combination corresponding to the lowest total power loss of the double-motor system at different rotating speeds according to the torque distribution combination and the corresponding total power loss of the double-motor system at different rotating speeds, and taking the torque distribution combination as an optimal torque distribution combination of the double-motor system at different rotating speeds;

and carrying out torque distribution on the double-motor system according to the optimal torque distribution combination of the double-motor system at different rotating speeds.

2. The method of claim 1, wherein the obtaining the correspondence between the rotation speed, the torque and the power loss of each single motor system comprises:

respectively carrying out bench test on each single motor system;

respectively determining the corresponding relation among the rotating speed, the torque and the power loss of each single motor system according to the bench test result;

the determining the maximum torque of each single motor system at different rotating speeds according to the corresponding relation among the rotating speed, the torque and the power loss of each single motor system, and determining the maximum torque of the double motor systems at different rotating speeds according to the maximum torque of each single motor system at different rotating speeds comprises:

respectively carrying out gridding processing on the rotating speed and the torque of each motor system according to a preset rotating speed interval and a first preset torque interval to obtain a rotating speed-torque two-dimensional matrix table of each motor system;

determining the maximum torque of each single motor system under different rotating speeds according to the rotating speed-torque two-dimensional matrix table of each motor system;

and respectively summing the maximum torques of the single motor systems at different rotating speeds to obtain the maximum torques of the double motor systems at different rotating speeds.

3. The method of claim 1, wherein the gridding the maximum torques of the dual-motor system at different rotation speeds to obtain the torque distribution combinations and the corresponding total power losses of the dual-motor system at different rotation speeds comprises:

according to a second preset torque interval, carrying out gridding processing on the maximum torque of the double-motor system at different rotating speeds to obtain a rotating speed-maximum torque one-dimensional matrix table of the double-motor system;

distributing the corresponding maximum torque under different rotating speeds to each single machine system according to a preset distribution proportion according to the rotating speed-maximum torque one-dimensional matrix table of the double motor system to obtain torque distribution combinations of the double motor system under different rotating speeds;

determining power losses corresponding to the torques distributed by each single machine system at different rotating speeds, and summing the power losses corresponding to the torques distributed by each single machine system at different rotating speeds to obtain the total power loss corresponding to the torque distribution combination of the double-motor system at different rotating speeds.

4. The method of claim 1, wherein after the torque distribution of the dual motor system according to the optimal torque distribution combination, the method further comprises:

acquiring mechanical power of the double-motor system at different rotating speeds;

and determining the efficiency of the double-motor system at different rotating speeds according to the mechanical power of the double-motor system at different rotating speeds and the total power loss corresponding to the torque distribution combination at different rotating speeds.

5. The method of claim 1, wherein the dual motor system includes a first motor and a second motor, the method further comprising:

under the condition that the double-motor system adopts a first dragging mode, the dragging torque of the first motor at different rotating speeds is obtained through a rack test, and under the condition that the double-motor system adopts a second dragging mode, the dragging torque of the second motor at different rotating speeds is obtained through the rack test;

adding the dragging torque of the first motor at different rotating speeds to the torque of the second motor at different rotating speeds to obtain new torque of the second motor at different rotating speeds, and adding the dragging torque of the second motor at different rotating speeds to the torque of the first motor at different rotating speeds to obtain new torque of the first motor at different rotating speeds;

determining power loss corresponding to new torque of the second motor at different rotating speeds as power loss of the dual-motor system in the first dragging mode, and determining power loss corresponding to new torque of the first motor at different rotating speeds as power loss of the dual-motor system in the second dragging mode;

determining the extra loss of the first motor at different rotating speeds, respectively adding the extra loss of the first motor at different rotating speeds to the power loss of the dual-motor system in the first dragging mode to obtain the total power loss of the dual-motor system in the first dragging mode, determining the extra loss of the second motor at different rotating speeds, respectively adding the extra loss of the second motor at different rotating speeds to the power loss of the dual-motor system in the second dragging mode to obtain the total power loss of the dual-motor system in the second dragging mode;

determining the lowest total power loss of the dual-motor system in the first dragging mode according to the total power loss of the dual-motor system in the first dragging mode, and determining the lowest total power loss of the dual-motor system in the second dragging mode according to the total power loss of the dual-motor system in the second dragging mode.

6. The method as claimed in claim 5, wherein the lowest total power loss of the dual-motor system at different rotation speeds is the lowest total power loss of the dual-motor system in the normal mode, and after obtaining the lowest total power loss of the dual-motor system in the first towing mode and the lowest total power loss of the dual-motor system in the second towing mode, the method further comprises:

determining the highest efficiency of the double-motor system in the normal mode according to the lowest total power loss of the double-motor system in the normal mode;

determining the highest efficiency of the double-motor system in the first dragging mode according to the lowest total power loss of the double-motor system in the first dragging mode;

determining the highest efficiency of the double-motor system in the second dragging mode according to the lowest total power loss of the double-motor system in the second dragging mode;

and comparing the double-motor system highest efficiency in the normal mode, the double-motor system highest efficiency in the first dragging mode and the double-motor system highest efficiency in the second dragging mode to determine the optimal control mode of the double-motor system according to the comparison result.

7. The method of claim 1, wherein the dual motor system includes a first motor and a second motor, the method further comprising:

acquiring the current temperature, the current rotating speed and the current torque of the first motor;

under the condition that the current temperature of the first motor reaches a power reduction temperature value, acquiring a torque distribution efficiency table, wherein the torque distribution efficiency table is used for recording the corresponding relation between different torque distribution combinations and the efficiency of a double-motor system;

according to the torque distribution efficiency table, reducing the current torque of the first motor to obtain the adjusted torque of the first motor;

and determining the adjusted torque of the second motor according to the adjusted torque of the first motor and the maximum torque of the second motor at the current rotating speed.

8. The method of claim 7, wherein determining the adjusted torque of the second electric machine based on the derated torque of the first electric machine and the maximum torque of the second electric machine at the current speed comprises:

calculating the difference value between the maximum torque of the dual-motor system at the current rotating speed and the adjusted torque of the first motor;

if the difference is larger than the maximum torque of the second motor at the current rotating speed, taking the maximum torque of the second motor at the current rotating speed as the adjusted torque of the second motor;

and if the difference is not larger than the maximum torque of the second motor at the current rotating speed, taking the difference as the adjusted torque of the second motor.

9. The method of claim 1, wherein the method further comprises:

receiving a torque distribution request of an upper-layer control system to the dual-motor system;

determining a torque distribution strategy of the double motors according to the torque distribution requests of the double motors, wherein the torque distribution strategy comprises an optimal torque distribution combination and an optimal control mode;

distributing the torque to the double motors according to the torque distribution strategy of the double motors.

10. A dual motor system, wherein the dual motor system comprises a first motor system and a second single motor system, the first single motor system comprises a first motor and a first controller connected to the first motor, the first motor system comprises a second motor and a second controller connected to the second motor, and the first controller is configured to implement the method of any one of claims 1 to 9.

Background

With the increasing deterioration of the environment and the increasing problem of energy crisis around the world, the environment and energy problems become important factors restricting the global economic development, and the energy-saving and environment-friendly new energy automobile becomes the key research and development direction of each large automobile enterprise around the world, so as to relieve the energy pressure and reduce the environmental pollution.

Under the great trend of motorization of various vehicle types, the structural modes of double-stator motors or double-motor driving of front and rear shafts are increasing day by day, and compared with an electric vehicle driven by a single motor, the electric vehicle has the advantages of strong dynamic property and balanced structural distribution, and the system efficiency can be optimized through a reasonable control strategy.

The existing double-motor power matching method has a torque distribution method for detecting the optimal efficiency in real time according to the efficiency, but the method has overlarge calculation amount and overhigh load rate of a controller and cannot meet the current technical requirements. There are also methods of apportioning the dual motors according to the torque requirements of the upper control system, which, although simple, are not necessarily optimal in efficiency.

Disclosure of Invention

The embodiment of the application provides a double-motor torque distribution method and a double-motor system, so that the torque distribution of the double-motor system is optimized, and the system efficiency is improved.

The embodiment of the application adopts the following technical scheme:

in a first aspect, an embodiment of the present application provides a torque distribution method for a dual-motor system, where the dual-motor system includes two independent single-motor systems, and the method includes:

acquiring the corresponding relation among the rotating speed, the torque and the power loss of each single motor system;

determining the maximum torque of each single motor system under different rotating speeds according to the corresponding relation among the rotating speed, the torque and the power loss of each single motor system, and determining the maximum torque of the double motor systems under different rotating speeds according to the maximum torque of each single motor system under different rotating speeds;

carrying out gridding processing on the maximum torque of the double-motor system at different rotating speeds to obtain a torque distribution combination and corresponding total power loss of the double-motor system at different rotating speeds;

determining a torque distribution combination corresponding to the lowest total power loss of the double-motor system at different rotating speeds according to the torque distribution combination and the corresponding total power loss of the double-motor system at different rotating speeds, and taking the torque distribution combination as an optimal torque distribution combination of the double-motor system at different rotating speeds;

and carrying out torque distribution on the double-motor system according to the optimal torque distribution combination of the double-motor system at different rotating speeds.

Optionally, the obtaining the correspondence among the rotating speed, the torque and the power loss of each single motor system includes:

respectively carrying out bench test on each single motor system;

respectively determining the corresponding relation among the rotating speed, the torque and the power loss of each single motor system according to the bench test result;

the determining the maximum torque of each single motor system at different rotating speeds according to the corresponding relation among the rotating speed, the torque and the power loss of each single motor system, and determining the maximum torque of the double motor systems at different rotating speeds according to the maximum torque of each single motor system at different rotating speeds comprises:

respectively carrying out gridding processing on the rotating speed and the torque of each motor system according to a preset rotating speed interval and a first preset torque interval to obtain a rotating speed-torque two-dimensional matrix table of each motor system;

determining the maximum torque of each single motor system under different rotating speeds according to the rotating speed-torque two-dimensional matrix table of each motor system;

and respectively summing the maximum torques of the single motor systems at different rotating speeds to obtain the maximum torques of the double motor systems at different rotating speeds.

Optionally, the grid processing the maximum torques of the dual-motor system at different rotation speeds to obtain the torque distribution combination and the corresponding total power loss of the dual-motor system at different rotation speeds includes:

according to a second preset torque interval, carrying out gridding processing on the maximum torque of the double-motor system at different rotating speeds to obtain a rotating speed-maximum torque one-dimensional matrix table of the double-motor system;

distributing the corresponding maximum torque under different rotating speeds to each single machine system according to a preset distribution proportion according to the rotating speed-maximum torque one-dimensional matrix table of the double motor system to obtain torque distribution combinations of the double motor system under different rotating speeds;

determining power losses corresponding to the torques distributed by each single machine system at different rotating speeds, and summing the power losses corresponding to the torques distributed by each single machine system at different rotating speeds to obtain the total power loss corresponding to the torque distribution combination of the double-motor system at different rotating speeds.

Optionally, after the torque distribution of the dual-motor system is performed according to the optimal torque distribution combination, the method further includes:

acquiring mechanical power of the double-motor system at different rotating speeds;

and determining the efficiency of the double-motor system at different rotating speeds according to the mechanical power of the double-motor system at different rotating speeds and the total power loss corresponding to the torque distribution combination at different rotating speeds.

Optionally, the dual motor system comprises a first motor and a second motor, the method further comprising:

under the condition that the double-motor system adopts a first dragging mode, the dragging torque of the first motor at different rotating speeds is obtained through a rack test, and under the condition that the double-motor system adopts a second dragging mode, the dragging torque of the second motor at different rotating speeds is obtained through the rack test;

adding the dragging torque of the first motor at different rotating speeds to the torque of the second motor at different rotating speeds to obtain new torque of the second motor at different rotating speeds, and adding the dragging torque of the second motor at different rotating speeds to the torque of the first motor at different rotating speeds to obtain new torque of the first motor at different rotating speeds;

determining power loss corresponding to new torque of the second motor at different rotating speeds as power loss of the dual-motor system in the first dragging mode, and determining power loss corresponding to new torque of the first motor at different rotating speeds as power loss of the dual-motor system in the second dragging mode;

determining the extra loss of the first motor at different rotating speeds, respectively adding the extra loss of the first motor at different rotating speeds to the power loss of the dual-motor system in the first dragging mode to obtain the total power loss of the dual-motor system in the first dragging mode, determining the extra loss of the second motor at different rotating speeds, respectively adding the extra loss of the second motor at different rotating speeds to the power loss of the dual-motor system in the second dragging mode to obtain the total power loss of the dual-motor system in the second dragging mode;

determining the lowest total power loss of the dual-motor system in the first dragging mode according to the total power loss of the dual-motor system in the first dragging mode, and determining the lowest total power loss of the dual-motor system in the second dragging mode according to the total power loss of the dual-motor system in the second dragging mode.

Optionally, the minimum total power loss of the dual-motor system at different rotation speeds is the minimum total power loss of the dual-motor system in the normal mode, and after the minimum total power loss of the dual-motor system in the first dragging mode and the minimum total power loss of the dual-motor system in the second dragging mode are obtained, the method further includes:

determining the highest efficiency of the double-motor system in the normal mode according to the lowest total power loss of the double-motor system in the normal mode;

determining the highest efficiency of the double-motor system in the first dragging mode according to the lowest total power loss of the double-motor system in the first dragging mode;

determining the highest efficiency of the double-motor system in the second dragging mode according to the lowest total power loss of the double-motor system in the second dragging mode;

and comparing the double-motor system highest efficiency in the normal mode, the double-motor system highest efficiency in the first dragging mode and the double-motor system highest efficiency in the second dragging mode to determine the optimal control mode of the double-motor system according to the comparison result.

Optionally, the dual motor system comprises a first motor and a second motor, the method further comprising:

acquiring the current temperature, the current rotating speed and the current torque of the first motor;

under the condition that the current temperature of the first motor reaches a power reduction temperature value, acquiring a torque distribution efficiency table, wherein the torque distribution efficiency table is used for recording the corresponding relation between different torque distribution combinations and the efficiency of a double-motor system;

according to the torque distribution efficiency table, reducing the current torque of the first motor to obtain the adjusted torque of the first motor;

and determining the adjusted torque of the second motor according to the adjusted torque of the first motor and the maximum torque of the second motor at the current rotating speed.

Optionally, the determining an adjusted torque of the second motor according to the reduced torque of the first motor and the maximum torque of the second motor at the current rotation speed includes:

calculating the difference value between the maximum torque of the dual-motor system at the current rotating speed and the adjusted torque of the first motor;

if the difference is larger than the maximum torque of the second motor at the current rotating speed, taking the maximum torque of the second motor at the current rotating speed as the adjusted torque of the second motor;

and if the difference is not larger than the maximum torque of the second motor at the current rotating speed, taking the difference as the adjusted torque of the second motor.

Optionally, the method further comprises:

receiving a torque distribution request of an upper-layer control system to the dual-motor system;

determining a torque distribution strategy of the double motors according to the torque distribution requests of the double motors, wherein the torque distribution strategy comprises an optimal torque distribution combination and an optimal control mode;

distributing the torque to the double motors according to the torque distribution strategy of the double motors.

In a second aspect, an embodiment of the present application further provides a dual-motor system, where the dual-motor system includes a first motor system and a second single-motor system, the first single-motor system includes a first motor and a first controller connected to the first motor, the first motor system includes a second motor and a second controller connected to the second motor, and the first controller is configured to implement any one of the foregoing methods.

The embodiment of the application adopts at least one technical scheme which can achieve the following beneficial effects: according to the torque distribution method of the double-motor system, the corresponding relation among the rotating speed, the torque and the power loss of each single-motor system is obtained firstly; then determining the maximum torque of each single motor system under different rotating speeds according to the corresponding relation among the rotating speed, the torque and the power loss of each single motor system, and determining the maximum torque of the double motor systems under different rotating speeds according to the maximum torque of each single motor system under different rotating speeds; then carrying out gridding processing on the maximum torque of the double-motor system at different rotating speeds to obtain a torque distribution combination and corresponding total power loss of the double-motor system at different rotating speeds; determining a torque distribution combination corresponding to the lowest total power loss of the double-motor system at different rotating speeds according to the torque distribution combination and the corresponding total power loss of the double-motor system at different rotating speeds, and taking the torque distribution combination as an optimal torque distribution combination of the double-motor system at different rotating speeds; and finally, carrying out torque distribution on the double-motor system according to the optimal torque distribution combination of the double-motor system at different rotating speeds. The torque distribution method of the double-motor system in the embodiment of the application carries out torque distribution based on the lowest power loss of the double-motor system, and improves the system efficiency. In addition, the two single motor systems are used as integrated independent systems, the requirement on an upper-layer control system is low, the system replacement is strong, and the control is simple.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a schematic flow chart illustrating torque distribution efficiency of a dual-motor system according to an embodiment of the present disclosure;

FIG. 2 is a diagram illustrating an efficiency MAP of the single motor system 1 according to an embodiment of the present invention;

FIG. 3 is a MAP illustrating the efficiency of the single motor system 2 according to an embodiment of the present disclosure;

FIG. 4 is a MAP illustrating the efficiency of a dual-motor system according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of an efficiency MAP after a dual-motor system increases a drag mode in an embodiment of the present application;

FIG. 6 is a schematic diagram illustrating a control mode of a dual-motor system according to an embodiment of the present disclosure;

FIG. 7 is a schematic illustration of a torque distribution efficiency profile in an embodiment of the present application;

FIG. 8 is a schematic diagram illustrating a relationship between a torque derating coefficient and a motor temperature according to an embodiment of the present disclosure;

fig. 9 is a schematic diagram of an architecture of a dual-motor system in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The technical solutions provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.

The existing torque distribution scheme of the dual-motor system at least has the following problems:

1) the scheme for calculating the highest efficiency in real time in the controller of the dual-motor system has large calculation amount, high controller load and higher requirement on the control system;

2) the method of proportional allocation is simple, but the system efficiency is low;

3) the torque matching depends on an upper-layer system, independent control cannot be achieved, the requirement on the upper-layer control system is high, and the replaceability is poor;

4) only the efficiency optimization is considered, and a torque distribution strategy under the conditions of reducing the power of the motor and the like is not provided.

Based on this, an embodiment of the present application provides a torque distribution method for a dual-motor system, where the dual-motor system of the embodiment of the present application includes two independent single-motor systems, as shown in fig. 1, a schematic flow chart of torque distribution efficiency of the dual-motor system in the embodiment of the present application is provided, and the method includes at least the following steps S110 to S150:

step S110, acquiring corresponding relations among the rotating speed, the torque and the power loss of each single motor system;

step S120, determining the maximum torque of each single motor system at different rotating speeds according to the corresponding relation among the rotating speed, the torque and the power loss of each single motor system, and determining the maximum torque of the double motor systems at different rotating speeds according to the maximum torque of each single motor system at different rotating speeds;

step S130, carrying out gridding processing on the maximum torques of the double-motor system at different rotating speeds to obtain a torque distribution combination and corresponding total power loss of the double-motor system at different rotating speeds;

step S140, determining a torque distribution combination corresponding to the lowest total power loss of the double-motor system at different rotating speeds according to the torque distribution combination and the corresponding total power loss of the double-motor system at different rotating speeds, and taking the torque distribution combination as the optimal torque distribution combination of the double-motor system at different rotating speeds;

and S150, distributing the torque of the double-motor system according to the optimal torque distribution combination of the double-motor system at different rotating speeds.

The torque distribution method of the double-motor system in the embodiment of the application carries out torque distribution based on the lowest power loss of the double-motor system, and improves the system efficiency. In addition, the two single motor systems are used as integrated independent systems, the requirement on an upper-layer control system is low, the system replacement is strong, and the control is simple.

In an embodiment of the present application, the obtaining the correspondence between the rotation speed, the torque, and the power loss of each single motor system includes: respectively carrying out bench test on each single motor system; respectively determining the corresponding relation among the rotating speed, the torque and the power loss of each single motor system according to the bench test result; the determining the maximum torque of each single motor system at different rotating speeds according to the corresponding relation among the rotating speed, the torque and the power loss of each single motor system, and determining the maximum torque of the double motor systems at different rotating speeds according to the maximum torque of each single motor system at different rotating speeds comprises: respectively carrying out gridding processing on the rotating speed and the torque of each motor system according to a preset rotating speed interval and a first preset torque interval to obtain a rotating speed-torque two-dimensional matrix table of each motor system; determining the maximum torque of each single motor system under different rotating speeds according to the rotating speed-torque two-dimensional matrix table of each motor system; and respectively summing the maximum torques of the single motor systems at different rotating speeds to obtain the maximum torques of the double motor systems at different rotating speeds.

In the step S110, when obtaining the corresponding relationship between the rotation speed, the torque, and the power loss of each single motor system, the embodiment of the present application first performs the bench test on each single motor system, where the bench test generally refers to that after the motor is designed, the motor needs to be calibrated, and the performance and the corresponding parameters of the motor are calibrated, and the motor can be put into use after the test. In the embodiment of the application, the torque and the power loss of the single motor system corresponding to different rotating speeds can be obtained by respectively performing bench test on each single motor system, and the corresponding relation among the rotating speed, the torque and the power loss of each single motor system can be obtained. It should be noted that the power loss of the single motor system herein includes the power loss of the entire system formed by the controller and the motor body in the single motor system.

In step S120, after obtaining the correspondence among the rotation speed, the torque, and the power loss of each single motor system, the embodiment of the present application may perform grid division of the two single motor systems into unified coordinates, where the rotation speed may be divided according to the same rotation speed interval, and the torque may be divided according to the same torque interval. For example, the rotation speed-torque two-dimensional matrix table of each motor system can be obtained by dividing 1000rpm (rotation speed) into 0,100,200,300, … … and 1000rpm at equal rotation speed intervals of 100rpm and dividing 100Nm (torque) into 0,10,20, … … and 100Nm at equal torque intervals of 10 Nm.

And then, according to the rotating speed-torque two-dimensional matrix table of each motor system, the maximum torque of each single motor system corresponding to each rotating speed point can be determined, and the maximum torque represents the maximum output capacity of each single motor system at the rotating speed point. Then, the maximum torques of each single motor system at different rotation speeds can be summed, so that the maximum torques of the whole double motor system at different rotation speeds can be obtained, for example, when the rotation speed is 800rpm, the maximum torque of the single motor system 1 is 100Nm, the maximum torque of the single motor system 2 is 50Nm, and the maximum torque of the whole double motor system at 800rpm is 150 Nm.

In an embodiment of the present application, the performing the meshing processing on the maximum torques of the dual-motor system at different rotation speeds to obtain the torque distribution combination and the corresponding total power loss of the dual-motor system at different rotation speeds includes: according to a second preset torque interval, carrying out gridding processing on the maximum torque of the double-motor system at different rotating speeds to obtain a rotating speed-maximum torque one-dimensional matrix table of the double-motor system; distributing the corresponding maximum torque under different rotating speeds to each single machine system according to a preset distribution proportion according to the rotating speed-maximum torque one-dimensional matrix table of the double motor system to obtain torque distribution combinations of the double motor system under different rotating speeds; determining power losses corresponding to the torques distributed by each single machine system at different rotating speeds, and summing the power losses corresponding to the torques distributed by each single machine system at different rotating speeds to obtain the total power loss corresponding to the torque distribution combination of the double-motor system at different rotating speeds.

In step S130, after the maximum torques of the dual-motor systems at different rotation speeds are obtained, the maximum torques of the dual-motor systems at different rotation speeds may be subjected to a meshing process, specifically, the torques corresponding to each rotation speed point may be divided according to a certain torque interval, that is, a second preset torque interval, and are respectively allocated to the two single-motor systems according to the certain torque interval, so that the sum of the torques allocated to the two single-motor systems is the torque corresponding to the rotation speed point of the dual-motor system.

For example, 1000rpm is divided into 0,10,20 … … 1000Nm, 100Nm is divided into 0,10,20 … … 100Nm at equal intervals and then sequentially allocated to the single motor system 1, and correspondingly, 100,90,80 … … 0Nm is sequentially allocated to the single motor system 2, so that a plurality of torque allocation combinations {0,100}, {10,90}, … …, {100,0} of the dual motor system at different rotation speeds can be obtained.

After a plurality of torque distribution combinations of the dual-motor system at different rotating speeds are obtained, the corresponding relation among the rotating speed, the torque and the power loss of each single-motor system obtained in the above embodiment can be used to determine the power loss corresponding to the torque distributed by the two single-motor systems in each torque distribution combination, and the total power loss of the whole dual-motor system can be obtained by adding the power losses of the two single-motor systems.

For example, for the torque distribution combination {10,90}, by querying the correspondence among the rotation speed, the torque and the power loss of each single motor system, it is determined that the power loss corresponding to the torque 10Nm of the single motor system 1 is 2kW, and the power loss corresponding to the torque 90Nm of the single motor system 2 is 5kW, then the total power loss of the whole dual motor system can be 7 kW.

In one embodiment of the present application, after the torque distribution of the dual motor system is performed according to the optimal torque distribution combination, the method further comprises: acquiring mechanical power of the double-motor system at different rotating speeds; and determining the efficiency of the double-motor system at different rotating speeds according to the mechanical power of the double-motor system at different rotating speeds and the total power loss corresponding to the torque distribution combination at different rotating speeds.

Based on the above, the total power loss corresponding to the torque distribution combination of the dual-motor system at different rotation speeds can be obtained, and the efficiency of the dual-motor system at different rotation speeds can be further calculated by the embodiment of the application, specifically by adopting the following formula:

Eff＝Pm/(Pm+Ploss1+Ploss2)，(1)

in the formula (1), Eff is the efficiency of the dual motor system at a certain rotation speed, Pm is the mechanical power at the rotation speed, Ploss1 is the power loss of the single motor system 1, and Ploss2 is the power loss of the single motor system 2.

Based on the above formula (1), the efficiency of the dual-motor system corresponding to the torque distribution combination of the dual-motor system at different rotation speeds can be obtained, as shown in fig. 2, an efficiency MAP schematic diagram of the single-motor system 1 in the embodiment of the present application is provided, as shown in fig. 3, an efficiency MAP schematic diagram of the single-motor system 2 in the embodiment of the present application is provided, as shown in fig. 4, an efficiency MAP schematic diagram of the dual-motor system in the embodiment of the present application is provided.

In one embodiment of the present application, the dual motor system includes a first motor and a second motor, the method further comprising: under the condition that the double-motor system adopts a first dragging mode, the dragging torque of the first motor at different rotating speeds is obtained through a rack test, and under the condition that the double-motor system adopts a second dragging mode, the dragging torque of the second motor at different rotating speeds is obtained through the rack test; adding the dragging torque of the first motor at different rotating speeds to the torque of the second motor at different rotating speeds to obtain new torque of the second motor at different rotating speeds, and adding the dragging torque of the second motor at different rotating speeds to the torque of the first motor at different rotating speeds to obtain new torque of the first motor at different rotating speeds; determining power loss corresponding to new torque of the second motor at different rotating speeds as power loss of the dual-motor system in the first dragging mode, and determining power loss corresponding to new torque of the first motor at different rotating speeds as power loss of the dual-motor system in the second dragging mode; determining the extra loss of the first motor at different rotating speeds, respectively adding the extra loss of the first motor at different rotating speeds to the power loss of the dual-motor system in the first dragging mode to obtain the total power loss of the dual-motor system in the first dragging mode, determining the extra loss of the second motor at different rotating speeds, respectively adding the extra loss of the second motor at different rotating speeds to the power loss of the dual-motor system in the second dragging mode to obtain the total power loss of the dual-motor system in the second dragging mode; determining the lowest total power loss of the dual-motor system in the first dragging mode according to the total power loss of the dual-motor system in the first dragging mode, and determining the lowest total power loss of the dual-motor system in the second dragging mode according to the total power loss of the dual-motor system in the second dragging mode.

The above embodiment mainly aims at the situation that two single motor systems in the dual-motor system work in a normal mode, and under some working conditions, the motor of one single motor system is used as a load, which may further improve the system efficiency. Based on this, the embodiment of the present application provides another control mode of the dual-motor system, that is, a dragging mode, where the dragging mode is that only one controller of the single-motor system is enabled in the entire dual-motor system, and the other controller of the single-motor system is enabled to be turned off, and dragging of the motor that is enabled to be turned on drives the other motor that is enabled to be turned off to idle, that is, to be used as a load.

For a dual-motor system, the dragging mode in the embodiment of the present application may specifically include a first dragging mode and a second dragging mode, where the first dragging mode refers to enabling the single-motor system 1 to be turned off, and enabling the single-motor system 2 to be turned on, and the second dragging mode refers to enabling the single-motor system 1 to be turned on, and enabling the single-motor system 2 to be turned off.

Taking the first dragging mode as an example, when torque distribution of the dual-motor system is performed in the first dragging mode, the single-motor system 1 is turned off and enabled, the single-motor system 2 is turned on and enabled, dragging torque of the first motor in the single-motor system 1 at different rotating speeds can be obtained through bench testing, namely the first motor can be driven by the second motor to obtain required torque, then the dragging torque of the first motor at different rotating speeds is increased to torque of the second motor at corresponding rotating speeds, new torque of the second motor at different rotating speeds is obtained, and the new torque represents the torque required to be provided by the dual-motor system when the dragging mode is increased.

After obtaining the new torque of the second motor at different rotation speeds, interpolation processing may be performed on the new torque to obtain the power loss corresponding to the new torque of the second motor at different rotation speeds, which is used as the power loss of the dual-motor system in the first dragging mode. In addition, in some special operating conditions, when the first motor is in high-speed operation, in order to perform torque distribution in the first dragging mode, some other losses, such as flux weakening control losses, are generated, and the losses need to be added to the power loss of the dual-motor system in the first dragging mode, so as to obtain the total power loss of the dual-motor system in the first dragging mode.

The total power loss of the double-motor system in the second dragging mode can be obtained by the same method, finally, the lowest total power loss of the double-motor system in the first dragging mode can be determined according to the total power loss corresponding to different rotating speeds of the double-motor system in the first dragging mode, and the lowest total power loss of the double-motor system in the second dragging mode can be determined according to the total power loss corresponding to different rotating speeds of the double-motor system in the second dragging mode.

In an embodiment of the present application, the minimum total power loss of the dual-motor system at different rotation speeds is the minimum total power loss of the dual-motor system in the normal mode, and after obtaining the minimum total power loss of the dual-motor system in the first towing mode and the minimum total power loss of the dual-motor system in the second towing mode, the method further includes: determining the highest efficiency of the double-motor system in the normal mode according to the lowest total power loss of the double-motor system in the normal mode; determining the highest efficiency of the double-motor system in the first dragging mode according to the lowest total power loss of the double-motor system in the first dragging mode; determining the highest efficiency of the double-motor system in the second dragging mode according to the lowest total power loss of the double-motor system in the second dragging mode; and comparing the double-motor system highest efficiency in the normal mode, the double-motor system highest efficiency in the first dragging mode and the double-motor system highest efficiency in the second dragging mode to determine the optimal control mode of the double-motor system according to the comparison result.

The minimum total power loss of the dual-motor system in the normal mode, the minimum total power loss in the first dragging mode and the minimum total power loss in the second dragging mode can be obtained through the embodiment, and in order to further determine the optimal control mode, the minimum total power losses of the three control modes in different rotating speeds can be compared, so that the optimal control modes in different rotating speeds can be determined.

Certainly, the maximum efficiency of the dual-motor system in the normal mode, the maximum efficiency in the first dragging mode and the maximum efficiency in the second dragging mode can be respectively calculated based on the efficiency calculation formula in the above embodiment, and the maximum efficiency in the first dragging mode and the maximum efficiency in the second dragging mode are compared, so that the optimal control modes of the dual-motor system at different rotating speeds are determined.

Fig. 5 is a schematic diagram of an efficiency MAP of a dual-motor system after a drag mode is added in the embodiment of the present application, and fig. 6 is a schematic diagram of a control mode of the dual-motor system in the embodiment of the present application.

In one embodiment of the present application, the dual motor system includes a first motor and a second motor, the method further comprising: acquiring the current temperature, the current rotating speed and the current torque of the first motor; under the condition that the current temperature of the first motor reaches a power reduction temperature value, acquiring a torque distribution efficiency table, wherein the torque distribution efficiency table is used for recording the corresponding relation between different torque distribution combinations and the efficiency of a double-motor system; according to the torque distribution efficiency table, reducing the current torque of the first motor to obtain the adjusted torque of the first motor; and determining the adjusted torque of the second motor according to the adjusted torque of the first motor and the maximum torque of the second motor at the current rotating speed.

The torque distribution scheme in the prior art is mainly designed for optimal efficiency, and the influence of the self states of the two motors on the torque distribution strategy is not considered. Based on the above, the embodiment of the application further detects the self states of the two motors to perform torque adjustment, such as the temperature of the motors, so as to comprehensively consider the economy and the dynamic property of the operation of the dual-motor system.

Specifically, the current temperatures of the two motors can be monitored in real time or at intervals, the first motor is taken as an example here, after the current temperature of the first motor is monitored, the current rotating speed and the current torque of the first motor can be simultaneously obtained, the current temperature of the first motor is compared with the power reduction temperature value of the first motor, the power reduction temperature value can be regarded as a temperature critical value, the temperature value is reached, it is shown that the temperature of the motor is higher at this moment, and the power loss needs to be reduced to avoid the motor from being damaged.

Therefore, if the current temperature of the first motor reaches the power reduction temperature value, which indicates that the power loss of the first motor needs to be reduced, a torque distribution efficiency table may be obtained first, and a correspondence relationship between different torque distribution combinations and dual-motor system efficiency may be recorded in the torque distribution efficiency table, which may be specifically represented in the form of fig. 7, that is, a schematic diagram of a torque distribution efficiency distribution in the embodiment of the present application.

As can be seen from fig. 7, torque distribution efficiency is highest at a certain point, and when a certain motor reduces power, torque is distributed by moving left and right, so that both dynamic performance and efficiency can be guaranteed. For example, when the maximum rotation speed is 2000rpm and the maximum torque is 200Nm, the maximum efficiency point is that the torque of the first motor is allocated to 120Nm, the torque of the second motor is allocated to 80Nm, when the current temperature of the first motor reaches the power reduction temperature value, the torque allocated to the first motor needs to be reduced to obtain the adjusted torque of the first motor, meanwhile, the torque of the second motor needs to be correspondingly increased because the sum of the torques of the first motor and the second motor at the same rotation speed point is constant, and when the torque of the second motor is increased, the maximum torque which can be borne by the second motor at the rotation speed needs to be considered, so that the final adjusted torque of the second motor is determined.

In one embodiment of the present application, the determining the adjusted torque of the second electric machine based on the reduced torque of the first electric machine and the maximum torque of the second electric machine at the current rotational speed comprises: calculating the difference value between the maximum torque of the dual-motor system at the current rotating speed and the adjusted torque of the first motor; if the difference is larger than the maximum torque of the second motor at the current rotating speed, taking the maximum torque of the second motor at the current rotating speed as the adjusted torque of the second motor; and if the difference is not larger than the maximum torque of the second motor at the current rotating speed, taking the difference as the adjusted torque of the second motor.

In determining the adjusted torque of the second electric machine, this may be determined as follows:

TorqueCmd＝TorqueMotor1Cmd+TorqueMotor2Cmd，(2)

TorqueMotor1Cmd_New＝TorqueMotor1Cmd*Motor1Percentage，(3)

if the second motor output capacity does not exceed the maximum value, then it can be found that:

TorqueMotor2Cmd_New＝TorqueCmd-TorqueMotor1Cmd_New，(4)

if the second motor output capacity exceeds the current maximum capacity value, then it can be found that:

TorqueMotor2Cmd_New＝TorqueMotor2Cmd_Max，(5)

TorqueCmd_New＝TorqueMotor1Cmd_New+TorqueMotor2Cmd_New，(6)

in the above formula, torque Cmd is a required torque value of the dual-motor system at the current rotating speed, torque motor1Cmd is the optimal distribution required torque of the first motor at the current rotating speed and the maximum torque, and torque motor2Cmd is the optimal distribution required torque of the second motor at the current rotating speed and the maximum torque; the torque motor1Cmd _ New is a New torque distributed by the first motor after reducing power under the current rotating speed and the maximum torque, namely the adjusted torque of the first motor, and the torque motor2Cmd _ New is a New torque distributed by the second motor under the current rotating speed and the maximum torque, namely the adjusted torque of the second motor; the torque Motor2Cmd _ Max is the maximum torque which can be output by the second Motor under the current rotating speed and the maximum torque, and the Motor1percent is the torque derating coefficient of the first Motor.

As shown in fig. 8, a schematic diagram of a corresponding relationship between a torque derating coefficient and a motor temperature in the embodiment of the present application is provided, where the torque derating coefficient is 100% before the motor temperature reaches a power reduction temperature value, and the torque derating coefficient decreases as the motor temperature increases after the motor temperature reaches the power reduction temperature value.

The above method is also applicable to the case of reducing the power of the second motor, and is not described herein.

In one embodiment of the present application, the method further comprises: receiving a torque distribution request of an upper-layer control system to the dual-motor system; determining a torque distribution strategy of the double motors according to the torque distribution requests of the double motors, wherein the torque distribution strategy comprises an optimal torque distribution combination and an optimal control mode; distributing the torque to the double motors according to the torque distribution strategy of the double motors.

In an actual condition scene, the dual-motor system according to the embodiment of the present application may receive an instruction of the upper-layer control system to perform torque allocation, specifically, a torque allocation request of the upper-layer control system to the dual-motor system may be received first, where the torque allocation request may include information such as a required torque value, and then a torque allocation policy to be adopted, including an optimal torque allocation combination and an optimal control mode to be adopted, is determined according to the torque allocation request, and finally, torque allocation and control to each single motor in the dual-motor system are implemented according to the optimal torque allocation combination and the optimal control mode.

It should be noted that, in the above embodiment, the determination of the optimal torque distribution combination of the dual-motor system at different rotation speeds may be completed offline, and after a torque distribution instruction of the upper-layer control system is subsequently received, the optimal torque distribution combination under the condition may be directly determined according to the result of offline processing, and real-time calculation by the controller is not required, so that the computation amount and load of the controller are reduced, and the overall efficiency of the system is improved.

An embodiment of the present application further provides a dual-motor system, and as shown in fig. 9, an architectural schematic diagram of a dual-motor system in an embodiment of the present application is provided, where the dual-motor system includes a first motor system and a second single-motor system, the first single-motor system includes a first motor and a first controller connected to the first motor, the first motor system includes a second motor and a second controller connected to the second motor, and the first controller is configured to implement any one of the foregoing methods.

According to the embodiment of the application, a controller in a first single Motor system in a dual-Motor system CAN be used as a main controller MCU1, the MCU1 receives commands such as required torque of an upper-layer control system through CAN communication, then the first Motor1 in the first single Motor system is subjected to torque distribution and control according to a torque distribution strategy, the torque distribution strategy comprises an optimal torque distribution combination and an optimal control mode, and the like, and torque is distributed to a second Motor2 in another single Motor system through CAN communication.

The dual-motor system may be, for example, a front-rear driving dual-axle motor, on one hand, the MCU1 may transmit the allocated torque and control mode to the controller MCU2 in the second single-motor system through the CAN according to the optimal torque allocation combination and the optimal control mode, and on the other hand, the MCU1 may redistribute the torque and control mode according to the front-rear axle torque limit of the upper control system, for example, the front-rear axle torque limit in case of a slip.

Of course, it should be noted that the torque distribution method in the embodiment of the present application may be applicable to a dual-motor system, such as a front-rear driving dual-bridge motor system, and may also be applicable to a single-motor system, such as a dual-stator motor system, and if the dual-stator motor system is adopted, the torque distribution may be directly performed according to the control strategy of the controller in the dual-stator motor system.

It can be understood that the above dual-motor system can implement the steps of the dual-motor torque distribution method provided in the foregoing embodiment, and the related explanations regarding the dual-motor torque distribution method are applicable to the dual-motor system, and are not described herein again.

In summary, the torque distribution method of the dual-motor system of the present application at least achieves the following technical effects:

1) torque distribution is performed based on the lowest power loss, and the torque and the control mode under the condition of optimal efficiency can be provided for each single motor system;

2) the torque is matched offline, and the controller is simple to realize;

3) the two single motor systems are used as integrated independent systems, so that the requirement on an upper-layer control system is low, the system replacement is strong, and the control is simple;

4) the torque distribution strategy is further optimized aiming at the working conditions of reducing power and the like, and the economy and the dynamic performance of the double-motor system can be guaranteed.

It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.