CN109808673B

CN109808673B - Motor control method and device for hybrid electric vehicle

Info

Publication number: CN109808673B
Application number: CN201711175512.1A
Authority: CN
Inventors: 孙俊; 李雯; 张霏霏; 赖祥翔; 谷靖
Original assignee: SAIC Motor Corp Ltd
Current assignee: SAIC Motor Corp Ltd
Priority date: 2017-11-22
Filing date: 2017-11-22
Publication date: 2021-01-22
Anticipated expiration: 2037-11-22
Also published as: CN109808673A

Abstract

The embodiment of the application discloses a motor control method of a hybrid electric vehicle, which comprises the steps of firstly dividing a torque interval in which a motor works into a first torque interval and a second torque interval, then calculating the comprehensive efficiency of a power system under different motor torques by controlling the motor to work under different motor torques, simultaneously determining a preset condition, and determining whether the motor works in an electric mode or a power generation mode according to whether the motor torque corresponding to the comprehensive efficiency meeting the preset condition belongs to the first torque interval or the second torque interval. Because the working mode of the motor is determined by the comprehensive efficiency of the power system, the running mode of the motor is not determined by taking the battery storage capacity as a basis like the prior art, and the purposes of greatly reducing the energy loss of the power system in the running process of the vehicle, improving the fuel economy of the running of the whole vehicle and enabling the power system to work efficiently are achieved.

Description

Motor control method and device for hybrid electric vehicle

Technical Field

The application relates to the field of automobiles, in particular to a motor control method and device for a hybrid electric vehicle.

Background

A hybrid vehicle is a vehicle using two or more power sources, and the common power sources are classified into two types: an engine powered by fuel and an electric machine powered by a battery. Because the hybrid vehicle has the characteristics of high energy utilization rate, low emission and the like, the hybrid vehicle is a recognized effective means for solving the problem of energy shortage and environmental pollution at present and also becomes a key point for research and development in the vehicle field.

In the prior art, when a hybrid vehicle is in use, when the electric quantity stored in a battery is high, the hybrid vehicle can supply power to a motor, so that the motor assists an engine to drive the vehicle to run or the motor drives the vehicle to run independently; when the electric quantity stored by the battery is low, the engine can drive the motor to charge the battery. The system efficiency is low because the operation mode of the motor is determined based on the stored electric quantity of the battery.

Disclosure of Invention

In order to solve the technical problems in the prior art, the application provides a motor control method and device for a hybrid electric vehicle, and aims of reducing energy loss of a power system in the vehicle running process and improving the fuel economy of the whole vehicle in running are achieved.

The application provides a hybrid electric vehicle motor control method, the hybrid electric vehicle has a driving system, the driving system includes motor and engine, its characterized in that, the method includes:

acquiring a torque interval corresponding to the motor under the current working condition, wherein the torque interval comprises a first torque interval and a second torque interval, the first torque interval is obtained according to a torque limit value of the motor under an electric mode, the second torque interval is obtained according to a torque limit value of the motor under a power generation mode, and the first torque interval and the second torque interval respectively comprise at least one motor torque;

respectively calculating the comprehensive efficiency of the power system when the motor works under the torque of each motor;

if the motor torque corresponding to the comprehensive efficiency meeting the preset condition is in the first torque interval, controlling the motor to enter an electric mode;

and if the motor torque corresponding to the comprehensive efficiency meeting the preset condition is in the second torque interval, controlling the motor to enter a power generation mode.

Optionally, the torque interval is determined according to the current rotation speed of the motor and the SOC value of the battery pack.

Optionally, the calculating the respective torques of the motors may include:

traversing each motor torque in the first torque interval according to a preset step length, and respectively calculating the comprehensive efficiency of the power system under the motor torque for the motor torque in each first torque interval;

and traversing each motor torque in the second torque interval according to the preset step length, and respectively calculating the comprehensive efficiency of the power system under the motor torque for the motor torque in each second torque interval.

Optionally, the calculating the respective torques of the motors may include:

acquiring the current rotating speed of the motor and the current rotating speed of the engine;

obtaining the engine torque of the engine according to the motor torque of the motor;

obtaining the output power and the input power of the power system according to the current rotating speed of the motor, the torque of the motor, the current rotating speed of the engine and the torque of the engine;

and obtaining the comprehensive efficiency of the power system according to the output power and the input power of the power system.

Optionally, if the motor torque is within the first torque interval, the obtaining the output power of the power system according to the current rotation speed of the motor, the motor torque, the current rotation speed of the engine, and the engine torque includes:

obtaining the mechanical power of the motor according to the motor torque and the rotating speed of the motor;

obtaining the mechanical power of the engine according to the torque of the engine and the rotating speed of the engine;

and taking the sum of the mechanical power of the engine and the mechanical power of the motor as the output power of the power system.

Optionally, if the motor torque is within the first torque interval, the obtaining the input power of the power system according to the current rotation speed of the motor, the motor torque, the current rotation speed of the engine, and the engine torque includes:

obtaining the instantaneous energy of the engine fuel required for realizing the mechanical power according to the mechanical power of the engine;

obtaining the electric power of the motor according to the mechanical power of the motor;

acquiring the current efficiency of the battery pack;

and obtaining the input power of the power system according to the instantaneous energy of the engine fuel, the electric power and the efficiency of the battery pack.

Optionally, the obtaining the instantaneous energy of the engine fuel required to achieve the mechanical power of the engine according to the mechanical power of the engine comprises:

obtaining the efficiency of the engine according to the rotating speed of the engine and the torque of the engine;

and obtaining the instantaneous energy of the engine fuel according to the mechanical power of the engine and the efficiency of the engine.

Optionally, the obtaining the electric power of the motor according to the mechanical power of the motor includes:

obtaining the current working efficiency of the motor according to the current voltage of the battery pack;

and obtaining the electric power of the motor according to the current working efficiency and the mechanical power of the motor.

Optionally, the obtaining the efficiency of the battery pack includes:

and obtaining the current efficiency of the battery pack according to the current voltage of the battery pack, the SOC value of the battery pack and the current value of the battery pack.

Optionally, if the motor torque is within the second torque interval, the obtaining the output power of the power system according to the current rotation speed of the motor, the motor torque, the current rotation speed of the engine, and the engine torque includes:

acquiring the current efficiency of the battery pack and the average value of the efficiency of the battery pack in the latest preset time period;

obtaining the work efficiency average value of the motor in the latest preset time period according to the voltage of the battery pack in the latest preset time period;

and obtaining the output power of the power system according to the mechanical power of the motor, the mechanical power of the engine, the electric power of the motor, the current efficiency of the battery pack, the average value of the efficiency of the battery pack and the average value of the working efficiency of the motor.

Optionally, if the motor torque is within the second torque interval, the obtaining the input power of the power system according to the current rotation speed of the motor, the motor torque, the current rotation speed of the engine, and the engine torque includes:

and obtaining the input power of the power system according to the mechanical power of the motor and the instantaneous energy of the engine fuel.

A hybrid vehicle motor control apparatus, the hybrid vehicle having a powertrain including a motor and an engine, the apparatus comprising:

the torque interval acquisition unit is used for acquiring a torque interval corresponding to the motor under the current working condition, wherein the torque interval comprises a first torque interval and a second torque interval, the first torque interval is obtained according to a torque limit value of the motor under an electric mode, the second torque interval is obtained according to a torque limit value of the motor under a power generation mode, and the first torque interval and the second torque interval respectively comprise at least one motor torque;

the comprehensive efficiency obtaining unit is used for respectively calculating the comprehensive efficiency of the power system when the motor works under each motor torque;

a control unit for controlling an operation mode of the motor, wherein:

Optionally, the comprehensive efficiency obtaining unit includes:

the first acquisition unit is used for traversing each motor torque in the first torque interval according to a preset step length, and respectively calculating the comprehensive efficiency of the power system under the motor torque for the motor torque in each first torque interval;

and the second acquisition unit traverses the motor torques in the second torque intervals according to the preset step length, and respectively calculates the comprehensive efficiency of the power system under the motor torque for the motor torque in each second torque interval.

Optionally, the comprehensive efficiency obtaining unit includes:

a rotation speed obtaining unit for obtaining a current rotation speed of the motor and a current rotation speed of the engine;

the torque acquisition unit is used for acquiring the engine torque of the engine according to the motor torque of the motor;

the power acquisition unit is used for obtaining the output power and the input power of the power system according to the current rotating speed of the motor, the torque of the motor, the current rotating speed of the engine and the torque of the engine;

and the comprehensive efficiency calculating unit is used for obtaining the comprehensive efficiency of the power system according to the output power and the input power of the power system.

Optionally, if the motor torque is within the first torque interval, the power obtaining unit includes:

the first motor mechanical power acquisition unit is used for acquiring the mechanical power of the motor according to the motor torque and the rotating speed of the motor;

the first engine mechanical power acquisition unit is used for acquiring the mechanical power of the engine according to the torque of the engine and the rotating speed of the engine;

and the first output power acquisition unit is used for taking the sum of the mechanical power of the engine and the mechanical power of the motor as the output power of the power system.

the first instantaneous energy acquisition unit is used for acquiring the instantaneous energy of the engine fuel required for realizing the mechanical power according to the mechanical power of the engine;

a first motor electric power obtaining unit for obtaining electric power of the motor according to mechanical power of the motor;

the first battery pack efficiency acquisition unit is used for acquiring the current efficiency of the battery pack;

and the first input power acquisition unit is used for obtaining the input power of the power system according to the instantaneous energy of the engine fuel, the electric power and the efficiency of the battery pack.

Optionally, the first instantaneous energy obtaining unit is specifically configured to obtain efficiency of the engine according to a rotation speed of the engine and the engine torque;

Optionally, the first motor electric power obtaining unit is specifically configured to obtain a current working efficiency of the motor according to a current voltage of the battery pack;

Optionally, the first battery pack efficiency obtaining unit is specifically configured to obtain the current efficiency of the battery pack according to the current voltage of the battery pack, the SOC value of the battery pack, and the current value of the battery pack.

Optionally, if the motor torque is within the second torque interval, the power obtaining unit includes:

the second motor mechanical power acquisition unit is used for acquiring the mechanical power of the motor according to the motor torque and the rotating speed of the motor;

the second engine mechanical power acquisition unit is used for acquiring the mechanical power of the engine according to the engine torque and the rotating speed of the engine;

a second motor electric power obtaining unit for obtaining electric power of the motor according to mechanical power of the motor;

the second battery pack efficiency obtaining unit is used for obtaining the current efficiency of the battery pack and the average value of the battery pack efficiency in the latest preset time period;

the second motor efficiency obtaining unit is used for obtaining the working efficiency average value of the motor in the latest preset time period according to the voltage of the battery pack in the latest preset time period;

and the second output power acquisition unit is used for obtaining the output power of the power system according to the mechanical power of the motor, the mechanical power of the engine, the electric power of the motor, the current efficiency of the battery pack, the average value of the efficiency of the battery pack and the average value of the working efficiency of the motor.

the second instantaneous energy acquisition unit is used for acquiring the instantaneous energy of the engine fuel required for realizing the mechanical power according to the mechanical power of the engine;

and the second input power acquisition unit is used for obtaining the input power of the power system according to the mechanical power of the motor and the instantaneous energy of the fuel of the engine.

According to the technical scheme, the torque interval of the motor is divided into the first torque interval and the second torque interval, the comprehensive efficiency of the power system under different motor torques is calculated by controlling the motor to work under different motor torques, and whether the motor works in the electric mode or the power generation mode is determined according to whether the motor torque corresponding to the comprehensive efficiency meeting the preset condition belongs to the first torque interval or the second torque interval. Therefore, the working mode of the motor is determined through the comprehensive efficiency of the power system, the operation mode of the motor is not determined based on the battery storage capacity as in the prior art, in addition, the motor torque corresponding to the comprehensive efficiency meeting the preset condition is the high-efficiency working point of the motor, and the power system works at the high-efficiency working point, so that the purposes of greatly reducing the energy loss of the power system in the driving process of the vehicle, improving the driving fuel economy of the whole vehicle and enabling the power system to work efficiently can be achieved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic diagram of a hardware scene structure of a motor control method for a hybrid electric vehicle according to an embodiment of the present application;

FIG. 2 is a flowchart illustrating an embodiment of a method for controlling a motor of a hybrid vehicle according to the present disclosure;

FIG. 3 is a flowchart illustrating an embodiment of a method for controlling a motor of a hybrid vehicle according to the present disclosure;

FIG. 4 is a flow chart illustrating an embodiment of a method provided herein for deriving the output power and the input power of the powertrain system based on motor torque in the first torque interval;

FIG. 5 is a flow chart illustrating an embodiment of a method for deriving the output power and the input power of the powertrain system based on the motor torque in the second torque interval provided herein;

FIG. 6 is a block diagram illustrating an exemplary embodiment of a motor control apparatus for a hybrid vehicle according to the present disclosure;

fig. 7 is a flowchart of an embodiment of a method for controlling a motor of a hybrid electric vehicle according to the present application.

Detailed Description

In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part 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 present application scheme is described below with reference to specific application scenarios, for example, one of the scenarios in the embodiment of the present application may be applied to a hardware scenario shown in fig. 1, where the hardware includes: a vehicle control module 100 and a power system 101.

The vehicle control module 100 is connected to the power system 101 through a Controller Area Network (CAN), and the control of the operating mode of the power system 101 is completed by calculating the comprehensive efficiency of the power system 101.

The vehicle control module 100 integrates the control function of each electronic device in the hybrid electric vehicle on a chip, so as to control a plurality of electronic devices in the vehicle, for example: the torque of the engine and the motor, the rotating speed of the engine and the motor, the gear of the engine and the motor, the vehicle speed, the pedal depth and the like. The entire vehicle control module 100 may implement at least one of the following functions: the control system has the functions of motor working mode control, engine control, battery pack control, vehicle speed control and the like.

Optionally, the chip may be a Digital Signal Processor (DSP), a ciscarl chip, and a single chip.

The power system includes a motor 102, an engine 103, and a battery pack 104. When the hybrid electric vehicle runs under a certain working condition, the vehicle control module 100 takes different motor torques, respectively calculates the comprehensive efficiency of the power system corresponding to the different motor torques, and then controls the working mode of the motor 102 according to the comprehensive efficiency meeting preset conditions.

The electric machine 102 is capable of operating in an electric mode and a generating mode. When the motor 102 operates in the electric mode, the motor 102 can assist the engine 103 to drive wheels, and supplement the shortage of the power output of the engine 103. When the motor 102 operates in the power generation mode, the engine 103 drives the motor 102 to charge the battery pack 104.

The battery pack 104 is used to provide power to the motor 102 when operating in the motoring mode.

It should be noted that the foregoing application scenarios are only shown for facilitating understanding of the principles of the present application, and are not intended to limit the technical solutions provided by the embodiments of the present application.

The method comprises the following steps:

referring to fig. 2, the figure is a flowchart of an embodiment of a method for controlling a motor of a hybrid electric vehicle according to an embodiment of the present application.

The motor control method for the hybrid electric vehicle provided by the embodiment comprises the following steps:

s201, acquiring a torque interval corresponding to the motor under the current working condition.

The torque interval comprises a first torque interval and a second torque interval, the first torque interval is obtained according to a torque limit value of the motor in an electric mode, the second torque interval is obtained according to a torque limit value of the motor in a power generation mode, and the first torque interval and the second torque interval respectively comprise at least one motor torque.

The current working condition is the current running state of the vehicle, and can be one of the following conditions: idling, starting, accelerating, decelerating and uniform speed. Wherein the idle speed comprises a parking idle speed and a driving idle speed, the acceleration comprises mild acceleration and rapid acceleration, and the deceleration comprises no braking, light braking, medium braking, heavy braking and emergency braking.

The torque limit is a limit of load capacity of the motor in different working modes, and may be determined according to a current rotation speed of the motor and a remaining battery capacity (State of Charge, SOC for short).

One possible way of achieving the torque interval is:

and taking the torque limit value of the motor in the electric mode as the right end point of the torque interval, taking the torque limit value of the motor in the power generation mode as the left end point of the torque interval, wherein the torque limit value of the motor in the power generation mode is a negative value.

The first torque interval is an interval formed by an origin of the torque interval and the right end point, and the second torque interval is an interval formed by the left end point and the origin of the torque interval.

For example, in the condition that the vehicle is slowly accelerated on a highway, the current rotating speed of the motor can reach more than 5000rpm, and according to the current rotating speed of the motor and the condition that the battery pack is fully charged, the torque limit value of the motor in the electric mode can be 200 N.m, the torque limit value of the motor in the power generation mode is-200 N.m, wherein N.m is the international unit Newton meter of the torque. Then, the first torque interval may be an interval formed by an origin of the torque interval and the right end point 200N · m, i.e., [0,200 ]. The second torque interval may be an interval formed by the left end point-200N · m and an origin of the torque interval, i.e., -200, 0.

Certainly, the motor can also be obtained in a torque interval corresponding to the current under different working conditions, such as constant-speed running on urban roads and speed-reducing running on mountain roads, and the embodiment of the application is not repeated one by one.

S202, respectively calculating the comprehensive efficiency of the power system when the motor works under the torque of each motor.

The overall efficiency of the power system may be the ratio of the output power to the input power of the power system.

One possible implementation manner of the comprehensive efficiency of the power system is as follows:

The preset step length is the step length of the motor torque, the size of the preset step length is related to the accuracy of the motor control method, the smaller the preset step length is, the more the number of the motor torques selected in the torque interval is, the more the comprehensive efficiency is obtained through calculation, and finally, when the working mode of the motor is determined according to the comprehensive efficiency, the more the numerical values can be referred to, so that the accuracy of the motor control method is higher. On the contrary, the accuracy of the motor control method is low. However, in an actual motor control algorithm, the efficiency of the algorithm needs to be considered, and if the preset step length is too small, the running time of the motor control algorithm is too long, and the efficiency is low. Therefore, the preset step length can be as small as possible on the premise of meeting the efficiency requirement, and the accuracy of the motor control algorithm is improved.

For example, the first torque interval may be [0,200], and the preset step may be 5. Traversing the first torque interval from the origin according to a preset step 5 to obtain 41 motor torques of 0,5,10, … and 200 which are sequentially increased, and respectively calculating the comprehensive efficiency of the corresponding power system according to the 41 motor torques.

In this embodiment, the preset step length may also be set to 10, the first torque interval [0,200] is traversed from the right endpoint to obtain 21 motor torques sequentially decreasing from 200,190, … and 0, and then the comprehensive efficiency of the corresponding power system is calculated according to the 41 motor torques.

For the same first torque interval [0,200], the motor control algorithm operates less efficiently at a preset step size of 5 than at a preset step size of 10, but with a higher accuracy than at a preset step size of 10.

Of course, other preset step lengths can be determined to obtain the torques of the motors in the second torque interval, and then the comprehensive efficiency of the power system under the torque of the motor is calculated according to the torques of the motors.

S203, if the motor torque corresponding to the comprehensive efficiency meeting the preset condition is in the first torque interval, controlling the motor to enter an electric mode;

The preset condition may be: the combined efficiency is at a maximum or the combined efficiency is at a minimum. After the comprehensive efficiency meeting the preset condition is selected, the working mode of the motor can be judged according to the comprehensive efficiency meeting the preset condition. The working mode is an electric mode or a power generation mode.

And if the comprehensive efficiency of the power system is the ratio obtained by the input power on the output power ratio, the preset condition is that the comprehensive efficiency of the power system is the maximum. At the moment, if the motor torque corresponding to the maximum comprehensive efficiency is in the first torque interval, controlling the motor to enter an electric mode to assist the engine to drive wheels; and controlling the motor to enter a power generation mode to charge the battery pack if the motor torque corresponding to the maximum comprehensive efficiency is in the second torque interval.

And if the comprehensive efficiency of the power system is the ratio obtained by the output power on the input power ratio, the preset condition is that the comprehensive efficiency of the power system is minimum. At the moment, if the motor torque corresponding to the minimum comprehensive efficiency is in the first torque interval, controlling the motor to enter an electric mode to assist the engine to drive wheels; and controlling the motor to enter a power generation mode to charge the battery pack if the motor torque corresponding to the minimum comprehensive efficiency is in the second torque interval.

The embodiment of the application uses the comprehensive efficiency of the power system to determine the working mode of the motor, rather than determining the running mode of the motor based on the stored electric quantity of the battery, so that the purposes of reducing the energy loss of the power system in the running process of the vehicle and improving the running fuel economy of the whole vehicle are achieved.

In the method, the torque interval can be determined according to the running condition of the hybrid electric vehicle, the preset step length for traversing the torque interval is determined under the condition of simultaneously meeting the efficiency and the accuracy, and finally the comprehensive efficiency corresponding to the torque of each motor is calculated according to the determined torque interval and the preset step length, so that the working mode of the motor is determined. In the actual process of determining the comprehensive efficiency, the motor torque is considered, and factors such as the motor rotating speed and the engine rotating speed can be referred to, so that the accuracy of the comprehensive efficiency is further improved. How to obtain the overall efficiency by referring to the motor speed, the engine speed and other factors is further described below.

Referring to fig. 3, the figure is a flowchart of an embodiment of a method for controlling a motor of a hybrid electric vehicle according to the embodiment of the present application.

s301, acquiring a torque interval corresponding to the motor under the current working condition.

When the method is used, the torque interval is obtained under any working condition, and the torque interval is not limited in the embodiment of the application.

And S302, respectively calculating the comprehensive efficiency of the power system when the motor works under the torque of each motor.

S303, if the motor torque corresponding to the comprehensive efficiency meeting the preset condition is in the first torque interval, controlling the motor to enter an electric mode;

And selecting the comprehensive efficiency meeting the preset condition, judging whether the motor torque corresponding to the comprehensive efficiency meeting the preset condition falls into the first torque interval or the second torque interval, and if the corresponding motor torque is in the first torque interval, enabling the motor to enter an electric mode at the moment to assist the engine to drive the wheels. Otherwise, entering a power generation mode and charging the battery pack.

When the method is used, the comprehensive efficiency is obtained under which preset condition is selected, and the method is not limited in the embodiment of the application.

In the method, the comprehensive efficiency of the power system meeting the preset condition is obtained according to the output power and the input power of the power system, and the working mode of the motor is determined according to the comprehensive efficiency of the power system meeting the preset condition. The output power and the input power of the power system can be obtained according to the motor torque in the first torque interval, and this embodiment of the present application provides one possible implementation manner of step S302.

Referring to fig. 4, the flowchart of an embodiment of a method for obtaining the output power and the input power of the powertrain according to the motor torque in the first torque interval is provided.

One possible implementation manner of the step S302 provided in this embodiment includes the following steps:

s401, calculating the output power of the power system when the motor torque is in the first torque interval.

The output power of the power system is the sum of the mechanical power of the engine and the mechanical power of the motor, and the specific calculation method may be as follows:

P_out1＝P_ICEMech+P_TMMech

wherein, P_out1Is the output power of the power system, P, if the current motor torque is in the first torque interval_ICEMechIs the mechanical power of the engine, P_TMMechIs the mechanical power of the motor.

The mechanical power of the engine is a product of the engine torque and the engine rotation speed, and the specific calculation method may be as follows:

P_ICEMech＝Trq_ICE×Spd_ICE

wherein, Trq_ICEFor said engine torque, Spd_ICEAnd obtaining the current rotating speed of the engine under the current working condition in real time.

The engine torque can be obtained according to the actual torque demand of the wheels, the motor torque, the transmission ratio of the engine transmission system and the transmission ratio of the motor transmission system, and the specific calculation method can be as follows:

Trq_ICE＝(Trq_wheelReq-Trq_TM×Ratio_TM)/Ratio_ICE

wherein, Trq_wheelReqRatio is the actual torque demand of the wheel_TMRatio of the motor drive train_ICEFor the engine-drive-train gear ratio, Trq_TMIs the motor torque.

The motor torques are all motor torques obtained by traversing the first torque interval according to preset step lengths.

The motor-drive train transmission ratio may be a ratio of a current rotational speed of the motor to a rotational speed of wheels, and the engine-drive train transmission ratio may be a ratio of a current rotational speed of the engine to a rotational speed of wheels.

The current rotating speed of the engine obtained in real time under the current working condition can be obtained according to the current rotating speed of the motor obtained in real time under the current working condition, the transmission ratio of an engine transmission system and the transmission ratio of a motor transmission system, and the specific calculation method can be as follows:

Spd_ICE＝Spd_TM/Ratio_TM×Ratio_ICE

wherein, Spd_TMAnd obtaining the current rotating speed of the motor under the current working condition in real time.

The mechanical power of the motor is the product of the motor torque and the current rotating speed of the motor obtained in real time under the current working condition, and the specific calculation method can be as follows:

P_TMMech＝Trq_TM×Spd_TM

the current rotating speed of the motor obtained in real time under the current working condition can be obtained according to the vehicle speed, the conversion coefficient of the current rotating speed of the motor and the vehicle speed and the transmission ratio of a motor circuit transmission system, and the specific calculation method can be as follows:

Spd_TM＝Veloctiy×Ratio_TM/Coef

and Velocity is the vehicle speed, and Coef is a conversion coefficient of the current rotating speed of the motor and the vehicle speed.

S402, calculating the input power of the power system when the motor torque is in the first torque interval.

The input power of the power system is obtained according to the instantaneous energy of the engine fuel, the electric power of the motor and the efficiency of the battery pack, and the specific calculation method can be as follows:

P_in1＝P_ICEFuel+P_TMElect/Effi_Batt

wherein, P_in1For the present motor torque in the first torque interval, the input power of the powertrain, P_ICEFuelIs the instantaneous energy of the engine fuel, P_TMElectFor the electric power of the motor, Effi_BattIs the battery efficiency.

The instantaneous energy of the engine fuel is the energy of the engine fuel required for realizing the mechanical power of the engine, and is obtained according to the mechanical power of the engine and the efficiency of the engine, and the specific calculation method can be as follows:

P_ICEFuel＝P_ICEMech/Effi_ICE

wherein, P_ICEFuelFor the instantaneous energy of the engine fuel, Effi_ICEFor the engine efficiency, the engine efficiency may be calculated by an interpolation method according to a test rotation speed of the engine, a test torque of the engine, and an actually measured engine efficiency map.

The actually measured engine efficiency map is an engine efficiency relation set correspondingly obtained under different working conditions of the test rotating speed of the engine and the test torque of the engine when a vehicle runs.

The electric power of the motor is obtained according to the mechanical power of the motor and the current working efficiency of the motor, and the specific calculation method can be as follows:

P_TMElect＝P_TMMech/Effi_TM

wherein Effi_TMFor the current working efficiency of the motor, interpolation can be used according to the test rotating speed of the motor, the test torque and the actual of the motorAnd calculating the measured motor efficiency map and the current voltage of the battery pack.

The actually measured motor efficiency map is a motor efficiency relation set correspondingly obtained under different working conditions of the test rotating speed of the motor and the test torque of the motor when a vehicle runs.

The battery pack efficiency is the current efficiency of the battery pack, and can be obtained by utilizing an interpolation method according to the current voltage of the battery pack, the SOC value of the battery pack and the current value of the battery pack. The current value of the battery pack may be obtained according to the electric power of the motor and the current voltage of the battery pack, and the specific calculation method may be:

I_Batt＝P_TMElect/V_Batt

wherein, I_BattIs a current value, V, of the battery pack_BattIs the current voltage of the battery pack.

And S403, obtaining the comprehensive efficiency of the power system according to the output power and the input power of the power system under the condition that the motor torque is in the first torque interval.

For example, one possible way to achieve the overall efficiency of the powertrain is to obtain the ratio of the output power to the input power:

Effi_sys1＝P_out1/P_in1＝(P_ICEMech+P_TMMech)/(P_ICEFuel+P_TMElect/Effi_Batt)

wherein Effi_sys1Is the overall efficiency of the powertrain system under conditions in which the motor torque is within the first torque interval.

For example, another possible way to achieve the overall efficiency of the powertrain is to obtain the ratio of the input power to the output power:

Effi_sys1＝P_in1/P_out1＝(P_ICEFuel+P_TMElect/Effi_Batt)/(P_ICEMech+P_TMMech)

when this method is used, step S401 may be executed first, and then step S402 may be executed.

In the above method, the output power and the input power of the power system with the motor torque in the first torque interval are obtained according to the mechanical power of the engine, the mechanical power of the motor, the instantaneous energy of the engine fuel, the electric power and the efficiency of the battery pack, so as to obtain the comprehensive efficiency of the power system meeting the preset condition, and the working mode of the motor is determined according to the comprehensive efficiency of the power system meeting the preset condition. The output power and the input power of the power system may also be obtained according to the motor torque in the second torque interval, and this embodiment of the present application provides another possible implementation manner of step S302.

Referring to fig. 5, the flowchart of an embodiment of a method for obtaining the output power and the input power of the powertrain according to the motor torque in the second torque interval is shown.

Another possible implementation manner of the step S302 provided in this embodiment includes the following steps:

s501, calculating the output power of the power system when the motor torque is in the second torque interval.

The output power of the power system is obtained according to the mechanical power of the motor, the mechanical power of the engine, the electric power of the motor, the current efficiency of the battery pack, the average value of the efficiency of the battery pack and the average value of the working efficiency of the motor, and the specific calculation method may be as follows:

P_out2＝P_ICEMech-P_TMMech+P_TMElect×Effi_Batt×Effi_BattAve×Effi_TMAve

wherein, P_out2Is the output power of the power system, P, if the motor torque is in the second torque interval_ICEMechIs the mechanical power of the engine, P_TMMechIs the mechanical power of the motor, P_TMElectFor the electric power of the motor, Effi_BattFor the current efficiency of the battery, Effi_BattAveAs the average value of the efficiency of the battery pack, Effi_TMAveAnd the average value of the working efficiency of the motor is obtained.

The mechanical power of the engine is the product of the engine torque and the rotational speed of the engine. The mechanical power of the motor is the product of the motor torque and the motor speed. The electric power of the motor is obtained according to the mechanical power of the motor and the current working efficiency of the motor, wherein the current working efficiency of the motor can be obtained by utilizing an interpolation method and calculating according to the rotating speed of the motor, the torque of the motor, an actually measured motor efficiency map and the current voltage of a battery pack.

The average value of the battery pack efficiency is the average value of the battery pack efficiency in the latest preset time period, and the average value of the working efficiency of the motor is obtained according to the voltage of the battery pack in the latest preset time period.

And S502, calculating the input power of the power system when the motor torque is in the second torque interval.

The input power of the power system is the sum of the mechanical power of the motor and the instantaneous energy of the engine fuel, and the specific calculation method can be as follows:

P_in2＝P_ICEFuel+P_TMMech

wherein, P_in2Is the input power, P, of the power system if the motor torque is in the second torque interval_ICEFuelIs the instantaneous energy of the engine fuel. The instantaneous energy of the engine fuel is obtained according to the mechanical power of the engine and the efficiency of the engine, and the details of this embodiment are not repeated herein.

And S503, under the condition that the motor torque is in the second torque interval, obtaining the comprehensive efficiency of the power system according to the output power and the input power of the power system.

Effi_sys2＝P_out2/P_in2＝(P_ICEMech-P_TMMech+P_TMElect×Effi_Batt×Effi_BattAve×Effi_TMAve)/(P_ICEFuel+P_TMMech)

wherein Effi_sys2Is the overall efficiency of the powertrain system under the condition that the motor torque is within the second torque interval.

Effi_sys2＝P_in2/P_out2＝(P_ICEFuel+P_TMMech)/(P_ICEMech-P_TMMech+P_TMElect×Effi_Batt×Effi_BattAve×Effi_TMAve)

when this method is used, step S501 may be executed first, and then step S502 may be executed.

In the method, the output power and the input power of the power system with the motor torque in the second torque interval are respectively obtained according to the mechanical power of the motor, the mechanical power of the engine, the electric power of the motor, the current efficiency of the battery pack, the average working efficiency of the motor and the instantaneous energy of the fuel of the engine, so that the comprehensive efficiency of the power system meeting the preset condition is obtained, and the working mode of the motor is determined according to the comprehensive efficiency of the power system meeting the preset condition.

In the following, the method of the present application is described in application scenarios, and during driving of a hybrid electric vehicle, it is necessary to determine when a motor operates in an electric mode, assist an engine to drive wheels, and operate in a starting mode to charge a battery pack. In order to enable a power system to work at an efficient working point, meet the requirement of intelligent charging, and achieve the purposes of greatly reducing energy loss of the power system in the vehicle running process, improving fuel economy of vehicle running and enabling the power system to work efficiently, an embodiment of the application provides a method for controlling a motor of a hybrid electric vehicle, and refer to fig. 7, which is a flow chart of the method for controlling the motor of the hybrid electric vehicle provided by the embodiment of the application.

and S701, initializing parameters.

The number of the working points is (motor electric torque limit value-motor generating torque limit value)/preset torque step length + 1;

the optimal torque of the motor is equal to the motor electric torque limit value;

the optimal system efficiency is 0;

the initialization operating point number is 0.

The number of the working points is the cycle number of the motor control method cycle, and can be obtained according to the preset torque step length, the torque limit of the motor in the electric mode and the torque limit of the motor in the power generation mode. In the first calculation period of the motor control method, the electric torque of the motor can be limited to the optimal torque of the motor, the optimal system efficiency is 0, and the serial number of the working point is 0.

For example, if the motor electric torque limit value can be 200N · m, the motor electric torque limit value can be-200N · m, the preset torque step can be 10, the number of operating points is 41, and the number of cycle periods of the motor control method is 41.

And S702, calculating the comprehensive efficiency.

The integrated efficiency is a ratio of an output power of the power system and an input power of the power system. The output power of the power system can be obtained according to the rotating speed of the motor, the current torque of the motor, the rotating speed of the engine and the torque of the engine. The input power of the power system can be obtained according to the rotating speed of the motor, the current torque of the motor, the rotating speed of the engine and the torque of the engine.

The current motor torque is obtained according to the torque limit, the current working point sequence number and the preset torque step length in the motor electric mode, and the specific calculation method can be as follows:

the current motor torque is equal to the motor electric torque limit value-the working point serial number multiplied by the preset torque step length.

For example, if the current operating point number is 10, it indicates that the motor control method is performing the 11 th loop calculation, and the current motor torque is 200-10 × 10, i.e., 100N · m.

The engine torque can be obtained according to the wheel end torque demand, the current motor torque, the transmission ratio of the motor transmission system and the rotation ratio of the engine transmission system, and the specific calculation method can be as follows:

engine torque-wheel end torque demand-current motor torque x motor driveline ratio/engine driveline rotation ratio.

The motor rotating speed and the engine rotating speed adopted in calculating the comprehensive efficiency are the current rotating speed of the motor and the current rotating speed of the engine.

And S703, judging the comprehensive efficiency.

Comparing the integrated efficiency of the current cycle obtained in step S702 with the optimal system efficiency obtained in all previous cycles, where the comparison condition may be: and if the comprehensive efficiency of the current cycle is greater than the optimal system efficiency obtained in all the previous cycle, the step S704 is executed, otherwise, the step S705 is directly executed.

And S704, replacing the optimal system efficiency with the comprehensive efficiency of the current period, and replacing the optimal torque of the motor obtained in all the previous cycle periods with the current motor torque.

S705, increasing the sequence number of the current working point by 1 to obtain the sequence number of the updated working point.

S706, judging whether the sequence number of the updated working point is not more than the set working point number in the step S701, if so, recalculating the current motor torque by using the sequence number of the updated working point, executing the step S702 again according to the new current motor torque, calculating new comprehensive efficiency until the sequence number of the updated working point is more than the set working point number, and finishing the circulation of the motor control algorithm.

And S707, acquiring the optimal torque of the motor corresponding to the optimal system efficiency.

And acquiring the motor torque corresponding to the optimal system efficiency finally obtained by the motor control algorithm for finishing the circulation as the optimal motor torque.

And S708, taking the optimal torque of the motor as the optimal torque requirement of the motor. Obtaining the optimal torque demand of the engine according to the optimal torque demand of the motor, the torque demand of the wheel end, the transmission ratio of the motor transmission system and the rotation ratio of the engine transmission system, wherein one possible implementation method comprises the following steps:

engine optimum torque demand (wheel end torque demand-motor optimum torque demand x motor drive)

Driveline ratio)/engine driveline rotation ratio.

According to the method, the optimal torque demand of the motor and the optimal torque demand of the engine are obtained according to the motor control algorithm, so that the high-efficiency working point of the power system is determined, and the power system works under the high-efficiency working point, so that the aims of greatly reducing the energy loss of the power system in the running process of the vehicle, improving the fuel economy of the running of the whole vehicle and enabling the power system to work efficiently are fulfilled.

Based on the method for controlling the motor of the hybrid electric vehicle provided by the embodiment, the embodiment of the application also provides a device for controlling the motor of the hybrid electric vehicle, and the working principle of the device is described in detail with reference to the attached drawings.

Device embodiment

Referring to fig. 6, the drawing is a block diagram of a structure of a motor control device of a hybrid electric vehicle according to an embodiment of the present application.

The motor control device of the hybrid electric vehicle provided by the embodiment comprises:

a torque interval obtaining unit 601, configured to obtain a torque interval corresponding to the motor under a current working condition, where the torque interval includes a first torque interval and a second torque interval, the first torque interval is obtained according to a torque limit of the motor in an electric mode, the second torque interval is obtained according to a torque limit of the motor in a power generation mode, and the first torque interval and the second torque interval each include at least one motor torque;

a comprehensive efficiency obtaining unit 602, configured to calculate a comprehensive efficiency of the power system when the motor works under each motor torque;

a control unit 603 for controlling the operating mode of the motor, wherein:

Optionally, the comprehensive efficiency obtaining unit 602 includes:

Optionally, the first instantaneous energy obtaining unit is specifically configured to obtain the efficiency of the engine according to the rotation speed of the engine and the engine torque;

According to the device, the comprehensive efficiency of the power system is calculated by using the comprehensive efficiency acquisition unit, the working mode of the motor is determined according to the comprehensive efficiency of the power system meeting the preset condition instead of the conventional operation mode of the motor determined based on the stored electric quantity of the battery, and the purposes of reducing the energy loss of the power system in the driving process of the vehicle and improving the driving fuel economy of the whole vehicle are achieved.

When introducing elements of various embodiments of the present application, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

It should be noted that, as one of ordinary skill in the art would understand, all or part of the processes of the above method embodiments may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, and when executed, the computer program may include the processes of the above method embodiments. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus embodiment, since it is substantially similar to the method embodiment, it is relatively simple to describe, and reference may be made to some descriptions of the method embodiment for relevant points. The above-described apparatus embodiments are merely illustrative, and the units and modules described as separate components may or may not be physically separate. In addition, some or all of the units and modules may be selected according to actual needs to achieve the purpose of the solution of the embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

The foregoing is directed to embodiments of the present application and it is noted that numerous modifications and adaptations may be made by those skilled in the art without departing from the principles of the present application and are intended to be within the scope of the present application.

Claims

1. A method of controlling a motor of a hybrid vehicle having a powertrain including a motor and an engine, the method comprising:

if the motor torque corresponding to the comprehensive efficiency meeting the preset condition is in the second torque interval, controlling the motor to enter a power generation mode;

wherein, the calculating the motor working under each motor torque respectively, the comprehensive efficiency of the power system comprises:

2. The method of claim 1, wherein the torque interval is determined based on a current speed of the electric machine and a SOC value of a battery pack.

3. The method of claim 1, wherein said separately calculating the overall efficiency of the powertrain system for operation of the electric machines at each electric machine torque comprises:

4. The method of claim 1, wherein if the motor torque is within the first torque interval, the deriving the output power of the powertrain from the current speed of the motor, the motor torque, the current speed of the engine, and the engine torque comprises:

5. The method of claim 1, wherein if the motor torque is within the first torque interval, the deriving the input power of the powertrain from the current speed of the motor, the motor torque, the current speed of the engine, and the engine torque comprises:

acquiring the current efficiency of the battery pack;

6. The method of claim 5, wherein deriving the instantaneous energy of the engine fuel required to achieve the mechanical power of the engine based on the mechanical power of the engine comprises:

7. The method of claim 5, wherein the deriving the electrical power of the motor from the mechanical power of the motor comprises:

8. The method of claim 5, wherein said obtaining battery efficiency comprises:

9. The method of claim 1, wherein if the motor torque is within the second torque interval, the deriving the output power of the powertrain system based on the current speed of the motor, the motor torque, the current speed of the engine, and the engine torque comprises:

10. The method of claim 1, wherein if the motor torque is within the second torque interval, the deriving the input power of the powertrain system based on the current speed of the motor, the motor torque, the current speed of the engine, and the engine torque comprises:

11. A motor control apparatus for a hybrid vehicle, the hybrid vehicle having a powertrain including a motor and an engine, the apparatus comprising:

a control unit for controlling an operation mode of the motor, wherein:

wherein, the comprehensive efficiency acquisition unit includes:

12. The apparatus of claim 11, wherein the integrated efficiency obtaining unit comprises:

13. The apparatus of claim 11, wherein if the motor torque is within the first torque interval, the power harvesting unit comprises:

14. The apparatus of claim 11, wherein if the motor torque is within the first torque interval, the power harvesting unit comprises:

15. The apparatus of claim 14, wherein the first transient energy capture unit is configured to derive the efficiency of the engine based on the rotational speed of the engine and the engine torque; and obtaining the instantaneous energy of the engine fuel according to the mechanical power of the engine and the efficiency of the engine.

16. The device according to claim 14, characterized in that the first motor electric power obtaining unit is specifically configured to derive a current operating efficiency of the motor from a current voltage of the battery pack; and obtaining the electric power of the motor according to the current working efficiency and the mechanical power of the motor.

17. The apparatus according to claim 14, wherein the first battery efficiency obtaining unit is specifically configured to obtain the current efficiency of the battery pack according to the current voltage of the battery pack, the SOC value of the battery pack, and the current value of the battery pack.

18. The apparatus of claim 11, wherein if the motor torque is within the second torque interval, the power harvesting unit comprises:

19. The apparatus of claim 11, wherein if the motor torque is within the second torque interval, the power harvesting unit comprises: