CN111016877A

CN111016877A - Engine start-stop management system and method for single-motor hybrid power system

Info

Publication number: CN111016877A
Application number: CN201911236480.0A
Authority: CN
Inventors: 王景蓉; 林潇; 姜博; 王来钱; 杨超群; 郭思阳; 巴特
Original assignee: Zhejiang Geely Holding Group Co Ltd; Zhejiang Geely Automobile Research Institute Co Ltd
Current assignee: Zhejiang Geely Holding Group Co Ltd; Zhejiang Geely Automobile Research Institute Co Ltd
Priority date: 2019-12-05
Filing date: 2019-12-05
Publication date: 2020-04-17
Anticipated expiration: 2039-12-05
Also published as: CN111016877B

Abstract

The invention provides a single-motor hybrid power system engine start-stop management system and a single-motor hybrid power system engine start-stop management method, and belongs to the technical field of hybrid vehicle energy management strategies. The method solves the problem of how to realize the optimization of the engine start-stop management under various working conditions in a self-adaptive manner. The system comprises an acquisition module, an SOC judgment module, a threshold value determination module, a torque judgment module and an execution module. The method comprises the following steps: judging whether the current SOC is greater than a first SOC threshold value, and if the current SOC is less than the first SOC threshold value, judging whether the current SOC is in an uplink section or a downlink section; determining a current engine start-stop demand torque threshold value; and when the current required torque meets the current engine start-stop required torque threshold, sending an engine start-stop control instruction. The differential control of starting and stopping of the engine is respectively carried out by distinguishing the SOC ascending process and the SOC descending process, so that the low-efficiency working point of the engine and the low-speed frequent starting and stopping of the engine are favorably eliminated, the running time of the engine in a low SOC section is increased, and the short-time efficient utilization of energy is ensured.

Description

Engine start-stop management system and method for single-motor hybrid power system

Technical Field

The invention belongs to the technical field of energy management strategies of hybrid vehicles, and relates to a system and a method for managing starting and stopping of an engine of a single-motor hybrid power system.

Background

The engine starting and stopping strategy is an important component of an energy management strategy and is related to the control of the output of engine energy and idle oil consumption. The current common engine start-stop strategy is a single rule for determining the required torque to start and stop the engine according to the SOC and the vehicle speed, and the single rule is generally set based on the consideration of the engine efficiency or the system efficiency, wherein the SOC is the charge of a power battery. The required torque threshold value for starting the engine is lower when the SOC is low, the shutdown threshold value is close to 0, the engine can be started under a small throttle and is not easy to shut down, the working conditions that the engine participates in driving and power generation are increased, the required torque startup threshold value is increased along with the increase of the SOC, the shutdown threshold value is increased, the working conditions that the engine participates in driving and power generation are reduced, the driving working conditions of the motor are increased, the charging and discharging energy of the battery tends to be balanced in a period of time, and the SOC is not increased any more and is in a balanced state. Although the strategy has certain adaptability to different working conditions, the optimal control under each working condition cannot be realized, and the oil saving effect of the energy management strategy is influenced.

The present chinese patent document discloses a hybrid electric vehicle and a drive control method and apparatus thereof with application number 201510134343.1, the method is: acquiring the current gear of the hybrid electric vehicle, the current electric quantity of a power battery and the gradient of a road where the hybrid electric vehicle is located; judging whether the hybrid electric vehicle is in a sliding start-stop interval or not according to the current gear of the hybrid electric vehicle, the current electric quantity of a power battery and the gradient of a road where the hybrid electric vehicle is located at present; if the hybrid electric vehicle is in the sliding start-stop interval, further acquiring the current speed of the hybrid electric vehicle; and controlling the hybrid electric vehicle to enter a small-load shutdown function or a small-load flameout function according to the current vehicle speed. This strategy is that single rule engine opens and stops the strategy and can distinguish the start-stop strategy of high speed of a motor operating mode and low speed of a motor operating mode according to the speed of a motor, realizes SOC balance in different levels under different operating modes, but there are two aspects problems: firstly, the sensitivity of a start-stop engine valve value to SOC is not easy to set, if the sensitivity to SOC is high, the engine cannot stably work for a long time, the working efficiency of the engine is influenced, if the sensitivity is low, the engine can be driven and generate electricity for a long time under the working condition of a low-speed urban area with low electric quantity, a large amount of energy is stored in a battery and cannot be effectively utilized, the efficiency of a hybrid power system is influenced, and the economical efficiency is poor; and secondly, the working condition of the low-speed small accelerator is a high-income working condition for two modes of running power generation and pure electric drive, the running power generation under the working condition can obtain a large amount of electric energy at the cost of increasing a small amount of oil consumption, and the pure electric drive can save a large amount of fuel oil at the cost of a small amount of electricity consumption, so that if the running power generation and the pure electric drive can be carried out alternately in a period of time, the oil saving can be effectively realized.

Disclosure of Invention

The invention provides a single-motor hybrid power system engine start-stop management system and method aiming at the problems in the prior art. The system and the method solve the problem of how to realize the optimization of the engine start-stop management under various working conditions in a self-adaptive manner.

The invention is realized by the following technical scheme: the single-motor hybrid power system engine start-stop management system comprises an acquisition module and is characterized in that the system also comprises an acquisition module used for acquiring the current SOC of a power battery

The SOC judging module is used for judging whether the current SOC is greater than a first SOC threshold value, and if the current SOC is less than the first SOC threshold value, judging whether the current SOC is in an uplink section or a downlink section;

the threshold value determining module is used for determining a current engine start-stop demand torque threshold value, and when the current SOC is greater than the SOC threshold value one, determining that the current engine start-up demand torque is a first start-up threshold value and the current engine stop demand torque is a first stop threshold value; when the current SOC is in a downlink section, determining that the current engine starting requirement torque is a starting threshold value II, and the current engine stopping requirement torque is a stopping threshold value II; when the current SOC is in an uplink section, determining that the current engine startup required torque is a startup threshold value three, and the current engine stop required torque is a stop threshold value three; the first startup threshold value is larger than the second startup threshold value and larger than the third startup threshold value, and the first shutdown threshold value is larger than the second shutdown threshold value and larger than the third shutdown threshold value;

the torque judgment module is used for judging whether the current required torque is larger than or smaller than the current engine start-stop required torque threshold value to meet the condition;

and the execution module sends an engine start-stop control instruction when the current required torque meets the current engine start-stop required torque threshold value.

The SOC judging module judges according to the residual charge capacity of the power battery, when the current SOC is larger than the SOC threshold value, the power battery is full of electric quantity, at the moment, the working frequency of a motor is increased as much as possible, the working frequency of the engine is reduced, the threshold value determining module determines that the current torque threshold value required by starting and stopping of the engine is a starting threshold value I and a stopping threshold value I, at the moment, the starting threshold value I and the stopping threshold value I are set to be the highest, the starting difficulty of the engine is increased, and the stopping difficulty is reduced. Similarly, when the current SOC is smaller than the SOC threshold value one, the power battery needs to be charged, and when the current SOC is in a downlink section, the threshold value determining module determines that the current engine start-stop required torque threshold value is a start-up threshold value two and a stop threshold value two. And when the current SOC is in an uplink section, the threshold value determining module determines that the current engine start-stop required torque threshold value is a start-up threshold value III and a stop threshold value III, and the start-up threshold value III is smaller than a start-up threshold value II and the stop threshold value III is smaller than a stop threshold value II, the start-up threshold value III is lower at the moment, and the stop threshold value III is close to zero. The engine is relatively easy to start and relatively difficult to stop when the engine is in a downlink zone relative to the SOC. The engine can be started under a small throttle and is not easy to stop, and when the SOC of the power battery is in an ascending section, namely the battery needs more electric quantity, the working conditions that the engine participates in driving and power generation are increased. When the power battery is charged upwards for a period of time and exceeds the SOC balance point of the low-speed urban working condition, the power battery is expected to descend under the low-speed urban working condition, and the SOC of the power battery is in a descending section at the moment, namely the SOC balance point of the descending urban working condition is close to the SOC balance point of the low-speed urban working condition. And when the SOC of the power battery is in a downlink section, increasing the current torque threshold value and shutdown threshold value required by starting the engine at a low speed, properly reducing the working conditions of the engine participating in driving and power generation when the speed is low, and increasing the motor driving working conditions. When the vehicle is in a suburb overhead working condition, the high-speed engine is easy to start and stop, after the power battery exceeds the low-speed urban working condition SOC balance point and the charging uplink exceeds the SOC threshold value for a moment, the current engine starting and stopping required torque threshold value is determined to be a first starting threshold value and a first stopping threshold value, the first starting threshold value and the first stopping threshold value are set to be the highest, the high-speed engine works less at the moment, and the work of the pure electric machine is increased. The starting instruction triggering difficulty of the engine is increased due to the increase of the starting threshold value of the engine at present, and the stopping instruction triggering is easy due to the increase of the stopping threshold value of the engine. The differential control of starting and stopping of the engine is carried out by distinguishing the SOC ascending process and the SOC descending process, the low-speed urban area working condition characteristics are adapted, the elimination of the low-efficiency working point of the engine and the frequent starting and stopping of the engine at low speed are facilitated, the suburban overhead working condition is controlled in a differential mode, the continuous high-efficiency working of the engine at low SOC section and high speed is realized, and more running power generation working conditions provide support for electric energy accumulation. The efficient utilization of energy under different working conditions is guaranteed, the vehicle economy is improved, and the fuel consumption of the target hybrid vehicle in the urban area can be effectively reduced.

In the single-motor hybrid power system engine start-stop management system, the system further comprises a time judgment module, which is used for calculating the continuous time when the current required torque is greater than or less than the threshold value of the current engine start-stop required torque and meets the condition and judging whether the current required torque is greater than the set parameter; the time judgment module is internally provided with continuous time parameters, wherein the continuous time parameters meeting the first startup threshold, the second startup threshold, the third startup threshold, the first shutdown threshold, the second shutdown threshold and the third shutdown threshold are respectively t1, t2, t3, t11, t12 and t13 when the current required torque is triggered, t1 is not less than t2 and not less than t3, and t11 is not less than t12 and not more than t 13. And after the threshold value of the required torque is set, determining the authenticity and validity of the condition that the required torque meets the condition by comparing the current required torque with the threshold value of the required torque and determining the time for which the condition is met. Making the determination more accurate. And the more difficult the starting torque is according to the difficulty degree of starting and stopping needs, the longer the time needs to be met. The judgment of meeting the time of the same vehicle speed under various working conditions can be adapted, so that the judgment can be made under the stable working conditions.

In the single-motor hybrid power system engine start-stop management system, when the current SOC is greater than the SOC threshold value one, the threshold value determination module determines that the threshold value of the current required torque for starting the engine is a startup threshold value one, the torque judgment module judges that the current required torque is greater than the startup threshold value one, and the time judgment module starts the engine when the continuous time is greater than t 1; when the current SOC is smaller than the SOC threshold value one and is in an uplink section, the threshold value determining module determines that the threshold value of the required torque of the currently started engine is a starting threshold value three, the torque judging module judges that the current required torque is larger than the starting threshold value three, and the time judging module judges that the continuous time is larger than t3 to start the engine; when the current SOC is smaller than the SOC threshold value I and is in a downlink section, the threshold value determining module determines that the threshold value of the required torque of the currently started engine is a starting threshold value II, the torque judging module judges that the current required torque is larger than the starting threshold value II, and the time judging module judges that the continuous time is larger than t2 to start the engine; when the current SOC is larger than the SOC threshold value one, the threshold value determining module determines that the threshold value of the required torque for stopping the engine at present is a first stop threshold value, the torque judging module judges that the current required torque is smaller than the first stop threshold value, and the time judging module judges that the continuous time is larger than t11, the engine is stopped; when the current SOC is smaller than the SOC threshold value one and is in an uplink section, the threshold value determining module determines that the threshold value of the required torque of the currently stopped engine is a stop threshold value three, the torque judging module judges that the current required torque is smaller than the stop threshold value three, and the time judging module judges that the continuous time is longer than t13, the engine is stopped; when the current SOC is smaller than the SOC threshold value one and is in a downlink section, the threshold value determining module determines that the threshold value of the torque required by the current starting engine is a stopping threshold value two, the torque judging module judges that the current required torque is smaller than the stopping threshold value two, the engine is started when the continuous time of the time judging module is larger than t12, and the starting and stopping of the engine are executed when the judging conditions are met.

The change of the required torque starting threshold value and the required torque stopping threshold value is carried out through the upper section and the lower section of the SOC, so that no matter a plurality of SOC target balance points or a single target balance point are set, the dynamic change of the required torque starting threshold value of the engine can be set according to the fluctuation change of the SOC up and down particularly in a low vehicle speed area, the engine starting can be self-adaptive to all driving working conditions, the driving problem that the engine is frequently started and stopped at a low-speed low-efficiency working point and a low vehicle speed is favorably solved, and the short-time efficient utilization of energy is ensured. The economy of the vehicle is further improved.

In the above-mentioned single-motor hybrid power system engine start-stop management system, the threshold value determination module includes a first engine start-stop strategy model in which SOC is greater than SOC threshold value by one, a second engine start-stop strategy model in which SOC is less than SOC threshold value by one and a third engine start-stop strategy model in which SOC is less than SOC threshold value by one and is in the uplink section, where the first engine start-stop strategy model, the second engine start-stop strategy model and the third engine start-stop strategy model are all: in a coordinate system which takes a Y axis as an engine required torque threshold value and an X axis as a vehicle speed, respectively drawing a starting curve and a stopping curve by taking a starting threshold value I, a starting threshold value II, a starting threshold value III, a stopping threshold value I, a stopping threshold value II and a stopping threshold value III which correspond to the Y axis as starting points. The engine start-stop strategy model corresponding to different SOC periods is established, and the current required torque is directly fitted in the start curve to judge whether the judgment condition of the threshold value of the start-stop and stop required torque is met, so that the reaction speed of the engine start-stop strategy is increased, and the calculated amount is reduced.

A single-motor hybrid power system engine start-stop management method is used for obtaining the current SOC of a power battery, and is characterized by further comprising the following steps:

judging whether the current SOC is greater than a first SOC threshold value, and if the current SOC is less than the first SOC threshold value, judging whether the current SOC is in an uplink section or a downlink section;

determining a current engine start-stop demand torque threshold value: when the current SOC is larger than the SOC threshold value one, determining that the current engine startup required torque is a startup threshold value one, and the current engine shutdown required torque is a shutdown threshold value one; when the current SOC is in a downlink section, determining that the current engine starting requirement torque is a starting threshold value II, and the current engine stopping requirement torque is a stopping threshold value II; when the current SOC is in an uplink section, determining that the current engine startup required torque is a startup threshold value three, and the current engine stop required torque is a stop threshold value three; the first startup threshold value is larger than the second startup threshold value and larger than the third startup threshold value, and the first shutdown threshold value is larger than the second shutdown threshold value and larger than the third shutdown threshold value;

and when the current required torque meets the current engine start-stop required torque threshold, sending an engine start-stop control instruction.

According to the judgment of the residual charge capacity of the power battery, when the current SOC is larger than the SOC threshold value, the power battery is full of electric quantity, at the moment, the working frequency of a motor is increased as much as possible, the working frequency of the motor is reduced, the current torque threshold value required by starting and stopping the motor is determined to be a starting threshold value I and a stopping threshold value I, the starting threshold value I and the stopping threshold value I are set highest, the starting difficulty of the motor is increased, and the stopping difficulty is reduced. Similarly, when the current SOC is smaller than the SOC threshold value one, the power battery needs to be charged, and when the current SOC is in a downlink section, the current engine start-stop required torque threshold value is determined to be a start-up threshold value two and a stop threshold value two. And when the current SOC is in an uplink section, determining that the current engine start-stop required torque threshold is a start-up threshold III and a stop threshold III, wherein the start-up threshold III is smaller than the start-up threshold II, the stop threshold III is smaller than the stop threshold II, the start-up threshold III is lower at the moment, and the stop threshold III is close to zero. The engine is relatively easy to start and relatively difficult to stop when the engine is in a downlink zone relative to the SOC. The engine can be started under a small throttle and is not easy to stop, and when the SOC of the power battery is in an ascending section, namely the battery needs more electric quantity, the working conditions that the engine participates in driving and power generation are increased. The electric power battery of the vehicle is expected to descend under the working condition of the low-speed urban area after the electric power battery is charged upwards for a period of time and exceeds the SOC balance point of the working condition of the low-speed urban area, and the SOC of the electric power battery is in a descending section at the moment, namely the SOC balance point of the working condition of the low-speed urban area is close to the descending. And when the SOC of the power battery is in a downlink section, increasing the current torque threshold value and shutdown threshold value required by starting the engine at a low speed, properly reducing the working conditions of the engine participating in driving and power generation when the speed is low, and increasing the motor driving working conditions. When the vehicle is in a suburb overhead working condition, the high-speed engine is easy to start and stop, after the power battery exceeds the low-speed urban working condition SOC balance point and the charging uplink exceeds the SOC threshold value for a moment, the current engine starting and stopping required torque threshold value is determined to be a first starting threshold value and a first stopping threshold value, the first starting threshold value and the first stopping threshold value are set to be the highest, the high-speed engine works less at the moment, and the work of the pure electric machine is increased. The starting instruction triggering difficulty of the engine is increased due to the increase of the starting threshold value of the engine at present, and the stopping instruction triggering is easy due to the increase of the stopping threshold value of the engine. The differential control of starting and stopping of the engine is carried out by distinguishing the SOC ascending process and the SOC descending process, the low-speed urban area working condition characteristics are adapted, the elimination of the low-efficiency working point of the engine and the frequent starting and stopping of the engine at low speed are facilitated, the suburban overhead working condition is controlled in a differential mode, the continuous high-efficiency working of the engine at low SOC section and high speed is realized, and more running power generation working conditions provide support for electric energy accumulation. The efficient utilization of energy under different working conditions is guaranteed, the vehicle economy is improved, and the fuel consumption of the target hybrid vehicle in the urban area can be effectively reduced.

In the single-motor hybrid power system engine start-stop management method, continuous time parameters of the current required torque trigger, which meet a start threshold value I, a start threshold value II, a start threshold value III, a stop threshold value I, a stop threshold value II and a stop threshold value III, are respectively set as t1, t2, t3, t11, t12 and t13, t1 is not less than t2 is not less than t3, and t11 is not less than t12 is not less than t 13. And after the threshold value of the required torque is set, determining the authenticity and validity of the condition that the required torque meets the condition by comparing the current required torque with the threshold value of the required torque and determining the time for which the condition is met. Making the determination more accurate. And the more difficult the starting torque is according to the difficulty degree of starting and stopping needs, the longer the time needs to be met. The judgment of meeting the time of the same vehicle speed under various working conditions can be adapted, so that the judgment can be made under the stable working conditions.

In the method for managing the starting and stopping of the engine of the single-motor hybrid power system, when the current SOC is greater than the SOC threshold value one, the threshold value of the required torque of the current starting engine is determined to be a starting threshold value one, and the engine is started when the current required torque is greater than the starting threshold value one and the continuous time is greater than t 1; when the current SOC is smaller than the SOC threshold value one and is in an uplink section, determining that the threshold value of the required torque of the current starting engine is a starting threshold value two, judging that the current required torque is larger than the starting threshold value two, and starting the engine when the continuous time is larger than t 2; and when the current SOC is smaller than the SOC threshold value one and is in a downlink section, determining that the threshold value of the current required torque for starting the engine is a starting threshold value three, judging that the current required torque is larger than the starting threshold value three, and starting the engine when the continuous time is larger than t 3. The starting threshold value is changed through the upper and lower sections of the SOC, so that no matter a plurality of SOC target balance points or a single target balance point is set, the dynamic change of the starting threshold value of the engine required torque can be set according to the upper and lower fluctuation changes of the SOC in the current vehicle speed, particularly in a low vehicle speed area, the starting of the engine can be self-adaptive to all driving working conditions, the driving problems of low-speed low-efficiency working points of the engine and frequent starting of the engine at low vehicle speed are favorably solved, and the short-time high-efficiency utilization of energy is ensured. The economy of the vehicle is further improved.

In the method for managing the starting and stopping of the engine of the single-motor hybrid power system, when the current SOC is greater than the SOC threshold value one, the threshold value of the required torque for stopping the engine at present is determined as a first stop threshold value, the current required torque is judged to be smaller than the first stop threshold value, and the engine is stopped when the continuous time is greater than t 11; when the current SOC is smaller than the SOC threshold value one and is in a downlink section, determining that the threshold value of the required torque of the currently stopped engine is a stop threshold value two, judging that the current required torque is smaller than the stop threshold value two, and stopping the engine when the continuous time is longer than t 12; and when the current SOC is smaller than the SOC threshold value one and is in an uplink section, determining that the threshold value of the current starting engine required torque is a stop threshold value three, judging that the current required torque is smaller than the stop threshold value three, and starting the engine when the continuous time is longer than tl 3. The change of the shutdown threshold value is carried out through the upper section and the lower section of the SOC, so that no matter a plurality of SOC target balance points or a single target balance point is set, the shutdown threshold value can be set according to the dynamic change of the engine required torque in the current vehicle speed, particularly in the low vehicle speed area according to the fluctuation change of the SOC up and down, the engine can be stopped to adapt to all driving conditions, the driving problems of low-speed low-efficiency working points and low-vehicle-speed frequent shutdown of the engine can be eliminated, and the short-time high-efficiency utilization of energy is guaranteed. The economy of the vehicle is further improved.

In the engine start-stop management method for the single-motor hybrid power system, in a coordinate system taking a Y axis as an engine required torque threshold value and an X axis as a vehicle speed, a start-up curve and a stop curve are respectively drawn by taking a start-up threshold value I, a start-up threshold value II, a start-up threshold value III, a stop threshold value I, a stop threshold value II and a stop threshold value III which correspond to the Y axis as starting points, and an engine start-stop strategy model I with the SOC being greater than the SOC threshold value one, an engine start-stop strategy model II with the SOC being less than the SOC threshold value I and the SOC being in a downlink section and an engine start-stop strategy model III with the SOC being less than the SOC threshold value I and the being. The engine start-stop strategy model corresponding to different SOC periods is established, and the current required torque is directly fitted in the start curve to judge whether the judgment condition of the threshold value of the start-stop and stop required torque is met, so that the reaction speed of the engine start-stop strategy is increased, and the calculated amount is reduced.

In the method for managing the starting and stopping of the engine of the single-motor hybrid power system, when judging whether the current SOC is in an uplink section or a downlink section, the uplink section and the downlink section are hysteresis sections, threshold values of the hysteresis sections are set to be a and b, and a > b, if the SOC is greater than a, the downlink section is represented, and if the SOC is smaller than b, the SOC enters the uplink section; and the SOC is in an uplink section less than b, and the SOC enters a downlink section when ascending until the SOC is more than a. Under the same speed and SOC, because the uplink and downlink states are different, different engine starting and stopping controls are carried out, so that the engine starting and stopping controls can be adaptive to various working conditions of the vehicle, the engine starting and stopping strategy is further optimized, and the reasonability of energy management and the economical efficiency of the vehicle are improved. Compared with the prior art, the single-motor hybrid power system engine start-stop management system and method have the following advantages:

1. the invention can carry out different engine starting and stopping controls under the same vehicle speed and SOC, distinguish the SOC up-down process to carry out the differentiated control of the engine starting and stopping, when the SOC is in a lower section, the SOC up-down process can reduce the starting threshold value of the engine, ensure the long-time running of the engine, after the SOC is raised to a certain degree, if the vehicle continues to run in the low-speed urban working condition, the vehicle enters the down-down process, the starting threshold value of the low-speed engine is improved, the small accelerator driving system is more in a pure electric driving state, the invention is beneficial to eliminating the low-efficiency working point of the engine and the driveability of frequent starting and stopping of the low vehicle speed, thereby ensuring the short-time efficient utilization of energy.

2. The invention provides support for more running power generation working conditions by increasing the running time of the engine in the low SOC section, so that the SOC balance and the battery power bottom holding are easier and more reasonable.

3. When the SOC approaches to a battery electric quantity consumption section, the higher the SOC is, the higher the startup and shutdown threshold value is, the more easily the engine is stopped and the engine is not easy to start, and the SOC is stabilized in front of the consumption section according to the variation degree of the required torque and the vehicle speed in the working condition.

Drawings

FIG. 1 is a system block diagram of the present invention.

FIG. 2 is a logic flow diagram of the engine start stop determination of the present invention.

FIG. 3 is an engine start stop strategy model of the present invention.

In the figure, 1, an acquisition module; 2. an SOC judging module; 3. a threshold value determining module; 4. a torque judgment module; 5. a time judgment module; 6. an execution module; 31. an engine start-stop strategy model I; 32. an engine start-stop strategy model II; 33. an engine start-stop strategy model III; tq1 and a starting threshold value I; tq2 and a starting threshold value II; tq3 and a starting threshold value III; tt1, shutdown threshold one; tt2, shutdown threshold two; tt3, stop threshold three.

Detailed Description

The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described with reference to the drawings, but the present invention is not limited to these embodiments.

As shown in FIGS. 1-3, the engine start-stop management system of the single-motor hybrid power system comprises

The system comprises an acquisition module 1, a storage module and a control module, wherein the acquisition module is used for acquiring the current SOC of a power battery;

the SOC judging module 2 is used for judging whether the current SOC is greater than a first SOC threshold value, and if the current SOC is less than the first SOC threshold value, judging whether the current SOC is in an uplink section or a downlink section;

the threshold value determining module 3 is used for determining a current engine start-stop demand torque threshold value, and when the current SOC is greater than the SOC threshold value, determining that the current engine start-up demand torque is a start-up threshold value Tq1, and the current engine stop demand torque is a stop threshold value Tt 1; when the current SOC is in a downlink section, determining that the current engine starting requirement torque is a starting threshold value two Tq2, and the current engine stop requirement torque is a stop threshold value two Tt 2; when the current SOC is in an uplink section, determining that the current engine startup required torque is a startup threshold value three Tq3, and the current engine stop required torque is a stop threshold value three Tt 3; the first startup threshold Tq1 is greater than the second startup threshold Tq2 and greater than the third startup threshold Tq3, and the first shutdown threshold Tt1 is greater than the second shutdown threshold Tt2 and greater than the third shutdown threshold Tt 3;

the threshold value determining module 3 comprises a first engine start-stop strategy model 31 with SOC greater than a first threshold value, a second engine start-stop strategy model 32 with SOC less than a first threshold value and SOC in a downlink section, and a third engine start-stop strategy model 33 with SOC less than a first threshold value and SOC in an uplink section, wherein the first engine start-stop strategy model 31, the second engine start-stop strategy model 32 and the third engine start-stop strategy model 33 are all as follows: in a coordinate system with a Y axis as an engine required torque threshold value and an X axis as a vehicle speed, a starting curve and a stopping curve are respectively drawn with a starting threshold value Tq1, a starting threshold value Tq2, a starting threshold value Tq3, a stopping threshold value Tt1, a stopping threshold value Tt2 and a stopping threshold value Tt3 which correspond to the Y axis as starting points. The engine start-stop strategy model corresponding to different SOC periods is established, and the current required torque is directly fitted in the start curve to judge whether the judgment condition of the threshold value of the start-stop and stop required torque is met, so that the reaction speed of the engine start-stop strategy is increased, and the calculated amount is reduced.

The torque judgment module 4 is used for judging whether the current required torque is larger than or smaller than the current engine start-stop required torque threshold value to meet the condition;

and the execution module 6 sends an engine start-stop control instruction when the current required torque meets the current engine start-stop required torque threshold value.

The time judgment module 5 is used for calculating the continuous time of the torque judgment module 4 when judging that the current required torque is larger than or smaller than the current engine start-stop required torque threshold value and meets the condition and judging whether the current required torque is larger than a set parameter; continuous time parameters of the current required torque trigger meeting the startup threshold value one Tq1, the startup threshold value two Tq2, the startup threshold value three Tq3, the shutdown threshold value one Tt1, the shutdown threshold value two Tt2 and the shutdown threshold value three Tt3 are respectively t1, t2, t3, t11, t12 and t13, in addition, t1 is more than or equal to t2 and more than or equal to t3, and t11 is more than or equal to t12 and less than or equal to t13 are arranged in the time judgment module 5. And after the threshold value of the required torque is set, determining the authenticity and validity of the condition that the required torque meets the condition by comparing the current required torque with the threshold value of the required torque and determining the time for which the condition is met. Making the determination more accurate. And the more difficult the starting torque is according to the difficulty degree of starting and stopping needs, the longer the time needs to be met. The judgment of meeting the time of the same vehicle speed under various working conditions can be adapted, so that the judgment can be made under the stable working conditions.

When the current SOC is larger than the SOC threshold value one, the threshold value determining module 3 determines that the threshold value of the current required torque for starting the engine is a starting threshold value Tq1, the torque judging module 4 judges that the current required torque is larger than the starting threshold value Tq1, and the time judging module 5 starts the engine when the continuous time is larger than t 1; when the current SOC is smaller than the SOC threshold value one and is in an uplink section, the threshold value determining module 3 determines that the threshold value of the required torque of the currently started engine is a starting threshold value three Tq3, the torque judging module 4 judges that the current required torque is larger than the starting threshold value three Tq3, and the time judging module 5 starts the engine when the continuous time is larger than t 3; when the current SOC is smaller than the SOC threshold value one and is in a downlink section, the threshold value determining module 3 determines that the threshold value of the required torque of the currently started engine is a starting threshold value two Tq2, the torque judging module 4 judges that the current required torque is larger than the starting threshold value two Tq2, and the time judging module 5 starts the engine when the continuous time is larger than t 2; when the current SOC is larger than the SOC threshold value one, the threshold value determining module 3 determines that the threshold value of the current required torque for stopping the engine is a stop threshold value Tt1, the torque judging module 4 judges that the current required torque is smaller than the stop threshold value Tt1, and the time judging module 5 judges that the continuous time is larger than t11, and the engine is stopped; when the current SOC is smaller than the SOC threshold value one and is in an uplink section, the threshold value determining module 3 determines that the threshold value of the required torque of the currently stopped engine is a stop threshold value three Tt3, the torque judging module 4 judges that the current required torque is smaller than the stop threshold value three Tt3, and the time judging module 5 judges that the continuous time is larger than t13, and the engine is stopped; when the current SOC is smaller than the SOC threshold value one and is in a downlink section, the threshold value determining module 3 determines that the threshold value of the current required torque for starting the engine is a stop threshold value two Tt2, the torque judging module 4 judges that the current required torque is smaller than the stop threshold value two Tt2, the time judging module 5 starts the engine when the continuous time is larger than t12, and when the judging conditions are met, starting and stopping of the engine are executed. The change of the required torque starting threshold value and the required torque stopping threshold value is carried out through the upper section and the lower section of the SOC, so that no matter a plurality of SOC target balance points or a single target balance point are set, the dynamic change of the required torque starting threshold value of the engine can be set according to the fluctuation change of the SOC up and down particularly in a low vehicle speed area, the engine starting can be self-adaptive to all driving working conditions, the driving problem that the engine is frequently started and stopped at a low-speed low-efficiency working point and a low vehicle speed is favorably solved, and the short-time efficient utilization of energy is ensured. The economy of the vehicle is further improved.

The single-motor hybrid power system engine start-stop management method obtains the current SOC of the power battery, and further comprises the following steps:

determining a current engine start-stop demand torque threshold value: when the current SOC is larger than the SOC threshold value one, determining that the current engine startup required torque is a startup threshold value Tq1, and the current engine stop required torque is a stop threshold value Tt 1; when the current SOC is in a downlink section, determining that the current engine starting requirement torque is a starting threshold value two Tq2, and the current engine stop requirement torque is a stop threshold value two Tt 2; when the current SOC is in an uplink section, determining that the current engine startup required torque is a startup threshold value three Tq3, and the current engine stop required torque is a stop threshold value three Tt 3; the first startup threshold Tq1 is greater than the second startup threshold Tq2 and greater than the third startup threshold Tq3, and the first shutdown threshold Tt1 is greater than the second shutdown threshold Tt2 and greater than the third shutdown threshold Tt 3;

in a coordinate system with a Y axis as an engine required torque threshold value and an X axis as a vehicle speed, respectively drawing a starting curve and a stopping curve with a starting threshold value one Tq1, a starting threshold value two Tq2, a starting threshold value three Tq3, a stopping threshold value one Tt1, a stopping threshold value two Tt2 and a stopping threshold value three Tt3 which correspond to the Y axis as starting points, and accordingly establishing an engine starting and stopping strategy model one 31 when the SOC is greater than the SOC threshold value, an engine starting and stopping strategy model two 32 when the SOC is less than the SOC threshold value one and the SOC is in a downlink section and an engine threshold value starting and stopping strategy model three 33 when the SOC is less than the SOC value one and the SOC is in an uplink section. The engine start-stop strategy model corresponding to different SOC periods is established, and the current required torque is directly fitted in the start curve to judge whether the judgment condition of the threshold value of the start-stop and stop required torque is met, so that the reaction speed of the engine start-stop strategy is increased, and the calculated amount is reduced.

Continuous time parameters of the current required torque trigger, which meet a start threshold value one Tq1, a start threshold value two Tq2, a start threshold value three Tq3, a stop threshold value one Tt1, a stop threshold value two Tt2 and a stop threshold value three Tt3, are respectively set as t1, t2, t3, t11, t12 and t13, wherein t1 is more than or equal to t2 and more than or equal to t3, and t11 is more than or equal to t12 and more than or equal to t 13. And after the threshold value of the required torque is set, determining the authenticity and validity of the condition that the required torque meets the condition by comparing the current required torque with the threshold value of the required torque and determining the time for which the condition is met. Making the determination more accurate. And the more difficult the starting torque is according to the difficulty degree of starting and stopping needs, the longer the time needs to be met. The judgment of meeting the time of the same vehicle speed under various working conditions can be adapted, so that the judgment can be made under the stable working conditions.

When the current SOC is larger than the SOC threshold value one, determining that the threshold value of the required torque of the current starting engine is a starting threshold value Tq1, judging that the current required torque is larger than the starting threshold value Tq1, and starting the engine when the continuous time is larger than t 1; when the current SOC is smaller than the SOC threshold value one and is in an uplink section, determining that the threshold value of the required torque of the currently started engine is a starting threshold value three Tq3, judging that the current required torque is larger than a starting threshold value three Tq3, and starting the engine when the continuous time is larger than t 3; when the current SOC is smaller than the SOC threshold value one and is in a downlink section, determining that the threshold value of the required torque of the currently started engine is a starting threshold value two Tq2, judging that the current required torque is larger than the starting threshold value two Tq2, and starting the engine when the continuous time is larger than t 2. The starting threshold value is changed through the upper and lower sections of the SOC, so that no matter a plurality of SOC target balance points or a single target balance point is set, the dynamic change of the starting threshold value of the engine required torque can be set according to the upper and lower fluctuation changes of the SOC in the current vehicle speed, particularly in a low vehicle speed area, the starting of the engine can be self-adaptive to all driving working conditions, the driving problems of low-speed low-efficiency working points of the engine and frequent starting of the engine at low vehicle speed are favorably solved, and the short-time high-efficiency utilization of energy is ensured. The economy of the vehicle is further improved.

When the current SOC is larger than the SOC threshold value one, determining that the threshold value of the required torque of the currently stopped engine is a stop threshold value Tt1, judging that the current required torque is smaller than the stop threshold value Tt1, and stopping the engine when the continuous time is larger than t 11; when the current SOC is smaller than the SOC threshold value one and is in a descending section, determining the threshold value of the required torque of the currently stopped engine as a stopping threshold value two Tt2, judging that the current required torque is smaller than the stopping threshold value two Tt2, and stopping the engine when the continuous time is larger than t 12; when the current SOC is smaller than the SOC threshold value one and is in the ascending section, the threshold value of the current starting engine required torque is determined to be a stop threshold value three Tt3, the current required torque is judged to be smaller than the stop threshold value three Tt3, and the engine is started when the continuous time is larger than t 13. The change of the shutdown threshold value is carried out through the upper section and the lower section of the SOC, so that no matter a plurality of SOC target balance points or a single target balance point is set, the shutdown threshold value can be set according to the dynamic change of the engine required torque in the current vehicle speed, particularly in the low vehicle speed area according to the fluctuation change of the SOC up and down, the engine can be stopped to adapt to all driving conditions, the driving problems of low-speed low-efficiency working points and low-vehicle-speed frequent shutdown of the engine can be eliminated, and the short-time high-efficiency utilization of energy is guaranteed. The economy of the vehicle is further improved.

When judging whether the current SOC is in an uplink section or a downlink section, the uplink section and the downlink section are hysteresis sections, a threshold value of the hysteresis section is provided with a threshold value a and a threshold value b, the SOC is larger than the threshold value a and represents the downlink section, and the SOC enters the uplink section when the SOC is lower than the threshold value b; and the SOC is in an uplink section which is smaller than a threshold value b, and the SOC enters a downlink section when ascending until the SOC is larger than a threshold value a. Under the same speed and SOC, because the uplink and downlink states are different, different engine starting and stopping controls are carried out, so that the engine starting and stopping controls can be adaptive to various working conditions of the vehicle, the engine starting and stopping strategy is further optimized, and the reasonability of energy management and the economical efficiency of the vehicle are improved. Further SOC threshold value I > threshold value a > low-speed urban area working condition balance point > threshold value b > severe congestion working condition SOC balance point,

starting the engine in the running process of the vehicle, firstly judging whether a requirement for prohibiting starting the engine exists, if so, not executing a starting process, judging an obtained current SOC value after the starting process is started, and judging an uplink section and a downlink section after the SOC value is smaller than a set SOC threshold value by one. Whether the SOC is in an uplink section or a downlink section of the SOC balance point, if the SOC is at a plurality of dynamic balance points, the different sections of the SOC at different balance points corresponding to different working conditions can be respectively divided into the uplink section and the downlink section for control. And then executing an engine starting judgment process according to the section where the current SOC is located, namely, searching a starting engine threshold value, namely a starting threshold value Tq1, a starting threshold value two Tq2 or a starting threshold value three Tq3, which is larger than the SOC threshold value one and corresponds to the required torque of the SOC downlink section or the SOC uplink section, according to the current SOC and the vehicle speed, and obtaining a stopping engine threshold value, namely a stopping threshold value one Tt1, a stopping threshold value two Tt2 and a stopping threshold value three Tt3, which correspond to the required torque. And if the current required torque is larger than the current corresponding start threshold Tq1, Tq2 or Tq3, continuously judging whether the condition establishment time is larger than t1, t2 or t3, if the condition establishment time is met, sending an engine starting command, and if the condition establishment time is not met, returning to the logic initial position for circulation. The shutdown judgment logic flow is as follows: and the current required torque is smaller than the current corresponding shutdown threshold Tt1, Tt2 or Tt3, whether the condition is satisfied for a time longer than tl1, tl2 or tl3 or not is continuously judged, an engine stopping command is sent out when the condition is satisfied for a confirmed time, and the loop returns to the beginning of the logic if the condition is not satisfied.

The specific SOC judging module 2 judges according to the remaining charged electric quantity of the power battery, when the current SOC is larger than the SOC threshold value one, the electric quantity of the power battery is full, at the moment, the working frequency of a motor is increased as much as possible, and the working frequency of an engine is reduced, the threshold value determining module 3 determines that the current torque threshold value required by starting and stopping of the engine is a starting threshold value Tq1 and a stopping threshold value Tt1, at the moment, the starting threshold value Tq1 and the stopping threshold value Tt1 are set to be the highest, the starting difficulty of the engine is increased, and the stopping difficulty is reduced. Similarly, when the current SOC is smaller than the SOC threshold value, the power battery needs to be charged, and the SOC threshold value I is larger than the SOC balance point of the working condition in the low-speed urban area. And when the current SOC is in a downlink section, the threshold value determining module 3 determines that the current engine start-stop required torque threshold value is the startup threshold value two Tq2 and the shutdown threshold value two Tt2, because the startup threshold value two Tq2 is smaller than the startup threshold value one Tq1, and the shutdown threshold value two Tt2 is smaller than the shutdown threshold value one Tt1, the startup of the engine is relatively easy when the SOC is larger than the SOC threshold value for a moment, and the shutdown is relatively difficult. And when the current SOC is in the uplink section, the threshold value determining module 3 determines that the current engine start-stop required torque threshold value is the start-up threshold value three Tq3 and the stop threshold value three Tt3, because the start-up threshold value three Tq3 is smaller than the start-up threshold value two Tq2, the stop threshold value three Tt3 is smaller than the stop threshold value two Tt2, the start-up threshold value three Tq3 is lower at this time, and the stop threshold value three Tt3 is close to zero. The engine is relatively easy to start and relatively difficult to stop when the engine is in a downlink zone relative to the SOC. The engine can be started under a small throttle and is not easy to stop, and when the SOC of the power battery is in an ascending section, namely the battery needs more electric quantity, the working conditions that the engine participates in driving and power generation are increased. And when the power battery is charged upwards for a period of time and exceeds the SOC balance point of the low-speed urban working condition, the power battery is expected to descend under the low-speed urban working condition, and the SOC of the power battery is in a descending section at the moment, namely the SOC balance point of the descending urban working condition is close to the SOC balance point of the low-speed urban working condition. And when the SOC of the power battery is in a downlink section, increasing the current torque threshold value and shutdown threshold value required by starting the engine at a low speed, properly reducing the working conditions of the engine participating in driving and power generation when the speed is low, and increasing the motor driving working conditions. When the vehicle is in a suburb overhead working condition, the high-speed engine is easy to start and stop, the power battery exceeds a low-speed urban working condition SOC balance point, when the charging uplink exceeds an SOC threshold value, the current engine starting and stopping required torque threshold value is determined to be a starting threshold value Tq1 and a stopping threshold value Tt1, at the moment, the starting threshold value Tq1 and the stopping threshold value Tt1 are set to be the highest, at the moment, the work of the high-speed engine is reduced, and the work of pure electric machines is increased. The starting instruction triggering difficulty of the engine is increased due to the increase of the starting threshold value of the engine at present, and the stopping instruction triggering is easy due to the increase of the stopping threshold value of the engine. The differential control of starting and stopping of the engine is carried out by distinguishing the SOC ascending process and the SOC descending process, the low-speed urban area working condition characteristics are adapted, the elimination of the low-efficiency working point of the engine and the frequent starting and stopping of the engine at low speed are facilitated, the suburban overhead working condition is controlled in a differential mode, the continuous high-efficiency working of the engine at low SOC section and high speed is realized, and more running power generation working conditions provide support for electric energy accumulation. The efficient utilization of energy under different working conditions is guaranteed, the vehicle economy is improved, and the fuel consumption of the target hybrid vehicle in the urban area can be effectively reduced.

The specific working condition adaptive engine start-stop function is realized by the engine strategy model shown in fig. 3, each engine strategy model in fig. 3 reflects the relation between the required torque threshold value for starting and stopping the engine and the vehicle speed, if a dynamic SOC balance point is set correspondingly according to the working condition in the actual process, wherein the SOC threshold value one is a power battery balance point set under the suburb overhead working condition, the SOC threshold value two is a power battery balance point set under the low-speed urban working condition, the SOC threshold value three is a power battery balance point set under the severe congestion working condition, and the SOC threshold value one is greater than the SOC threshold value two and greater than the SOC threshold value three. If the current SOC is smaller than the second SOC threshold value and is close to the set threshold value b under the working condition of the low-speed urban area, the current SOC is in an SOC uplink section, an engine start-stop strategy model III 33 is executed as shown in FIG. 3, at the moment, a curve X3 is used as an engine start strategy and a curve L3 is used as a stop strategy, if a required torque start threshold is set to be a smaller value of a start threshold value tri Tq3, the stop threshold, namely the stop threshold value tri Tt3 is almost zero, the engine is easy to start and keeps running as far as possible, and the battery electric quantity can be quickly and efficiently charged to the second SOC threshold value under the working condition of the low-speed urban area by combining an accelerator losing power generation function and. When the current SOC is larger than the second SOC threshold value and is close to the set threshold value a, the vehicle enters a SOC downlink section, a second engine start-stop strategy model 32 is executed, a curve X2 is used as an engine start strategy and a curve L2 is used as a stop strategy in the figure, a second required torque start-stop threshold value Tq2 is set to have a large low vehicle speed and a small high vehicle speed, pure electric driving under the working condition of a low-speed small accelerator is realized, and the combination of the third engine start-stop strategy model 33 and the second engine start-stop strategy model 32 meets the requirements of the working condition of a low-speed urban area, namely whether the engine is started to stably generate power or the engine is stopped to. For suburb and overhead working conditions, the average vehicle speed is high, as shown in fig. 3, the first engine start-stop strategy model 31 is implemented, in the figure, a curve X1 is used as an engine start strategy and a curve L1 is used as a stop strategy, the engine is easy to start and is not easy to stop, the engine is continuously and efficiently charged by combining a torque distribution strategy until the SOC is greater than the first SOC threshold, the required torque start-up threshold is greater, the stop threshold is relatively increased, the engine operating condition is reduced, the system power consumption is increased and the SOC is stabilized near the first SOC threshold by matching with the torque distribution strategy to work in a relatively high-efficiency region as much as possible, so the start-stop strategy for suburb and overhead working conditions is the combination of the first engine start-stop strategy model 31 and the second engine start-stop strategy model: the engine is either running efficiently or is shut down.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims

1. The single-motor hybrid power system engine start-stop management system comprises an acquisition module (1) for acquiring the current SOC of a power battery, and is characterized by further comprising

The SOC judging module (2) is used for judging whether the current SOC is greater than a first SOC threshold value, and if the current SOC is less than the first SOC threshold value, judging whether the current SOC is in an uplink section or a downlink section;

the threshold value determining module (3) is used for determining a current engine start-stop demand torque threshold value, and when the current SOC is greater than the SOC threshold value one, determining that the current engine start-up demand torque is a start-up threshold value one (Tq1) and the current engine stop demand torque is a stop threshold value one (Tt 1); when the current SOC is in a downlink section, determining that the current engine starting demand torque is a starting threshold value two (Tq2), and the current engine stop demand torque is a stop threshold value two (Tt 2); when the current SOC is in the ascending section, determining that the current engine starting demand torque is a starting threshold value three (Tq3) and the current engine stop demand torque is a stop threshold value three (Tt 3); the first startup threshold value (Tq1) is greater than the second startup threshold value (Tq2) and greater than the third startup threshold value (Tq3), and the first shutdown threshold value (Tt1) is greater than the second shutdown threshold value (Tt2) and greater than the third shutdown threshold value (Tt 3);

the torque judgment module (4) is used for judging whether the current required torque is larger than or smaller than the current engine start-stop required torque threshold value to meet the condition;

and the execution module (6) sends an engine start-stop control instruction when the current required torque meets the current engine start-stop required torque threshold value.

2. The single-motor hybrid power system engine start-stop management system of claim 1, characterized in that the system further comprises a time judgment module (5) for calculating a continuous time during which a current required torque is greater than or less than a current engine start-stop required torque threshold value and meets a condition and judging whether the current required torque is greater than a set parameter; continuous time parameters of a current required torque trigger meeting a first start threshold (Tq1), a second start threshold (Tq2), a third start threshold (Tq3), a first stop threshold (Tt1), a second stop threshold (Tt2) and a third stop threshold (Tt3) are respectively set in the time judgment module (5) as t1, t2, t3, t11, t12 and t13, wherein t1 is more than or equal to t2 more than or equal to t3, and t11 is more than or equal to t12 more than or equal to t 13.

3. The one-motor hybrid power system engine start-stop management system of claim 2, characterized in that when the current SOC is greater than the SOC threshold value one, the threshold value determination module (3) determines that the threshold values of the current start-stop engine required torque are a start threshold value one (Tq1) and a stop threshold value one (Tt1), the torque judgment module (4) judges that the current required torque is greater than the start threshold value one (Tq1), and the time judgment module (5) judges that the continuous time is greater than t1, starts the engine, if the current required torque is less than the stop threshold value one (Tt1), and stops the engine if the continuous time is greater than t 11; when the current SOC is smaller than the SOC threshold value one and is in an uplink section, a threshold value determining module (3) determines that the threshold value of the current start-stop engine demand torque is a start threshold value three (Tq3) and a stop threshold value three (Tt3), a torque judging module (4) judges that the current demand torque is larger than the start threshold value three (Tq3), and a time judging module (5) judges that the continuous time is larger than t3, the engine is started, and if the current demand torque is smaller than the stop threshold value three (Tt3) and the continuous time is larger than t13, the engine is stopped; when the current SOC is smaller than the SOC threshold value one and is in a downlink section, the threshold value determining module (3) determines that the threshold value of the current start-stop engine required torque is a start threshold value two (Tq2) and a stop threshold value two (Tt2), the torque judging module (4) judges that the current required torque is larger than the start threshold value two (Tq2), the time judging module (5) judges that the continuous time is larger than t2, the engine is started, if the current required torque is smaller than the stop threshold value two (Tt2) and the continuous time is larger than t12, and when the judging conditions are met at will, the engine is started and stopped.

4. The single-motor hybrid power system engine start-stop management system of any one of claims 1 to 3, wherein the threshold determination module (3) comprises a first engine start-stop strategy model (31) with a SOC greater than a first SOC threshold, a second engine start-stop strategy model (32) with a SOC less than the first SOC threshold and a SOC in a downlink segment, and a third engine start-stop strategy model (33) with a SOC less than the first SOC threshold and a uplink segment, and the first engine start-stop strategy model (31), the second engine start-stop strategy model (32) and the third engine start-stop strategy model (33) are all: in a coordinate system with a Y axis as an engine required torque threshold value and an X axis as a vehicle speed, a starting curve and a stopping curve are respectively drawn with a starting threshold value I (Tq1), a starting threshold value II (Tq2), a starting threshold value III (Tq3), a stopping threshold value I (Tt1), a stopping threshold value II (Tt2) and a stopping threshold value III (Tt3) which correspond to the Y axis as starting points.

5. A single-motor hybrid power system engine start-stop management method is used for acquiring the current SOC of a power battery, and is characterized by further comprising the following steps:

determining a current engine start-stop demand torque threshold value: when the current SOC is larger than the SOC threshold value one, determining that the current engine starting demand torque is a starting threshold value one (Tq1) and the current engine stop demand torque is a stopping threshold value one (Tt 1); when the current SOC is in a downlink section, determining that the current engine starting demand torque is a starting threshold value two (Tq2), and the current engine stop demand torque is a stop threshold value two (Tt 2); when the current SOC is in the ascending section, determining that the current engine starting demand torque is a starting threshold value three (Tq3) and the current engine stop demand torque is a stop threshold value three (Tt 3); the first startup threshold value (Tq1) is greater than the second startup threshold value (Tq2) and greater than the third startup threshold value (Tq3), and the first shutdown threshold value (Tt1) is greater than the second shutdown threshold value (Tt2) and greater than the third shutdown threshold value (Tt 3);

6. The single-motor hybrid power system engine start-stop management method is characterized in that before the current engine start-stop required torque threshold is determined, continuous time parameters of the current required torque trigger, which meet a start-up threshold I (Tq1), a start-up threshold II (Tq2), a start-up threshold III (Tq3), a stop threshold I (Tt1), a stop threshold II (Tt2) and a stop threshold III (Tt3), are respectively set to be t1, t2, t3, t11, t12 and t13, wherein t1 is more than or equal to t2 and more than or equal to t3, and t11 is more than or equal to t12 and more than or equal to t 13.

7. The one-motor hybrid power system engine start-stop management method of claim 5 or 6, characterized in that when the current SOC is greater than the SOC threshold value one, the threshold value of the required torque of the current start-up engine is determined to be a start-up threshold value one (Tq1), the current required torque is judged to be greater than the start-up threshold value one (Tq1), and the engine is started when the continuous time is greater than t 1; when the current SOC is smaller than the SOC threshold value one and is in an uplink section, determining that the threshold value of the current starting engine required torque is a starting threshold value three (Tq3), judging that the current required torque is larger than the starting threshold value three (Tq3), and starting the engine when the continuous time is larger than t 3; when the current SOC is smaller than the SOC threshold value one and is in a downlink section, the threshold value of the current starting engine required torque is determined to be a starting threshold value two (Tq2), the current required torque is judged to be larger than the starting threshold value two (Tq2), and the engine is started when the continuous time is larger than t 2.

8. The one-motor hybrid power system engine start-stop management method according to claim 5 or 6, characterized in that when the current SOC is greater than the SOC threshold value one, the threshold value of the current required torque for stopping the engine is determined as a stop threshold value one (Tt1), the current required torque is judged to be less than the stop threshold value one (Tt1), and the engine is stopped when the continuous time is greater than t 11; when the current SOC is smaller than the SOC threshold value one and is in a descending section, determining the threshold value of the current required torque for stopping the engine as a second stop threshold value (Tt2), judging that the current required torque is smaller than the second stop threshold value (Tt2), and stopping the engine when the continuous time is larger than t 12; when the current SOC is smaller than the SOC threshold value one and is in an ascending section, the threshold value of the current starting engine required torque is determined to be a stop threshold value three (Tt3), the current required torque is judged to be smaller than the stop threshold value three (Tt3), and the engine is started when the continuous time is larger than t 13.

9. The single-motor hybrid power system engine start-stop management method of claim 8, characterized in that in a coordinate system with a Y axis as an engine required torque threshold and an X axis as a vehicle speed, a start-up threshold value one (Tq1), a start-up threshold value two (Tq2), a start-up threshold value three (Tq3), a stop threshold value one (Tt1), a stop threshold value two (Tt2) and a stop threshold value three (Tt3) corresponding to the Y axis are respectively used as starting points to respectively draw a start-up curve and a stop curve, so as to establish an engine start-stop strategy model one (31) when the SOC is greater than the threshold value one, an engine start-stop strategy model two (32) when the SOC is less than the threshold value one and the SOC is in a downlink section, and an engine start-stop strategy model three (33) when the SOC is less than the threshold value one and the SOC is in.

10. The single-motor hybrid power system engine start-stop management method according to claim 5, characterized in that when judging whether the current SOC is in an uplink section or a downlink section, the uplink section and the downlink section are hysteresis sections, a threshold value of the hysteresis section is provided with a threshold value a and a threshold value b, the threshold value a is larger than the threshold value b, the SOC represents the downlink section when being larger than the threshold value a, and the SOC enters the uplink section when the SOC is downlink until the SOC is smaller than the threshold value b; and the SOC is in an uplink section which is smaller than a threshold value b, and the SOC enters a downlink section when ascending until the SOC is larger than a threshold value a.