阅读说明：本技术 一种混合动力车辆的节油控制方法及系统 (Fuel-saving control method and system for hybrid vehicle ) 是由 郑辉 刘积成 刘亚威 马磊 于 2018-07-06 设计创作，主要内容包括：本发明涉及一种混合动力车辆的节油控制方法及系统,属于混合动力汽车技术领域。本发明在高速工况下,根据坡度大小进行电机助力的控制,处于爬大坡工况时,为了避免电池SOC的急剧下降,同时为了充分发挥发动机的动力输出,执行发动机直接驱动；处于中等坡度工况时,由于发动机瞬态工况油耗高,为了保证发动机始终处于稳态工况的输出,此时车辆所需要的瞬态功率,如坡道阻力功率和加速阻力功率,均由电机提供。本发明通过上述控制,在不增加动力电池容量的同时,能够有效降低高速工况整车燃油消耗量,实现整车节能。(The invention relates to an oil-saving control method and an oil-saving control system for a hybrid electric vehicle, and belongs to the technical field of hybrid electric vehicles. Under the high-speed working condition, the motor assistance is controlled according to the gradient, and when the vehicle is in the working condition of climbing a large slope, the direct driving of the engine is executed to avoid the rapid decrease of the SOC of the battery and fully exert the power output of the engine; when the vehicle is in the medium-gradient working condition, because the oil consumption of the engine under the transient working condition is high, in order to ensure that the engine is always in the output of the steady-state working condition, the transient power required by the vehicle, such as the ramp resistance power and the acceleration resistance power, is provided by the motor. Through the control, the fuel consumption of the whole vehicle under the high-speed working condition can be effectively reduced while the capacity of the power battery is not increased, and the energy conservation of the whole vehicle is realized.)

1. A fuel-saving control method of a hybrid vehicle, characterized by comprising the steps of:

1) collecting the speed of the vehicle, and judging whether the vehicle is in an acceleration working condition or not when the speed of the vehicle is greater than a speed set value;

2) when the vehicle is in an acceleration working condition, judging whether the SOC of the vehicle power battery is greater than a first SOC set value, and if so, judging the gradient of the vehicle;

3) when the vehicle is on a slope larger than a first slope set value, the output power of the engine is increased, the increased power of the engine is equal to the sum of the acceleration resistance power and the slope resistance power, when the vehicle is on a slope larger than a second slope set value and smaller than the first slope set value, the motor is adopted for assisting, and the assisting power of the motor is equal to the sum of the acceleration resistance power and the slope resistance power.

2. The fuel-saving control method of the hybrid vehicle according to claim 1, wherein when the vehicle is in a non-acceleration condition, it is determined whether the SOC of the vehicle power battery is less than a second SOC set value, if so, a difference between the optimal torque of the engine and the current torque is calculated, and if the difference is not less than the set torque value, the power generation torque of the motor is controlled to be equal to the difference between the optimal torque of the engine and the current torque.

3. The fuel-saving control method of a hybrid vehicle according to claim 1 or 2, characterized in that, in the step 3), if the gradient of the vehicle is smaller than a second gradient set value, the motor is used for assisting, and the assisting power of the motor is equal to the accelerating resistance power.

4. The fuel-saving control method of a hybrid vehicle according to claim 1 or 2, characterized in that the acceleration condition is determined according to a vehicle accelerator pedal opening change rate, and when the vehicle accelerator pedal opening change rate is larger than an opening change set value, it indicates that the vehicle is in the acceleration condition.

5. The fuel saving control method of a hybrid vehicle according to claim 2, wherein the engine optimum torque is composed of torque values at which specific fuel consumption is lowest at different rotation speeds.

6. An oil-saving control system of a hybrid vehicle is characterized by comprising a vehicle information acquisition unit and a control unit, the vehicle information acquisition unit is used for acquiring the speed of the vehicle, the SOC of the power battery and the gradient of the vehicle, and the collected information is sent to a control unit for processing, the control unit is used for controlling the vehicle speed to be higher than a speed set value, the vehicle is in an acceleration working condition and the SOC of the vehicle power battery is higher than a first SOC set value, and the control is carried out according to the slope of the vehicle, when the slope of the vehicle is larger than the first slope set value, increasing the output power of the engine, wherein the increased power of the engine is equal to the sum of the acceleration resistance power and the ramp resistance power, when the slope of the vehicle is larger than the second slope set value and smaller than the first slope set value, the motor is adopted for assisting, and the assisting power of the motor is equal to the sum of the accelerating resistance power and the ramp resistance power.

7. The fuel-saving control system of a hybrid vehicle according to claim 6, wherein the control unit determines whether the SOC of the vehicle power battery is less than a second SOC set value when the vehicle is in a non-acceleration operating condition, calculates a difference between the optimal torque of the engine and the current torque if the SOC of the vehicle power battery is less than the second SOC set value, and controls the electric motor to generate the electric torque equal to the difference between the optimal torque of the engine and the current torque if the SOC of the vehicle power battery is not less than the set torque value.

8. The fuel-saving control system of a hybrid vehicle according to claim 6 or 7, wherein the control unit uses the motor to assist the vehicle when the vehicle speed is greater than a set speed value, the vehicle is in an acceleration condition, and the vehicle power battery SOC is greater than a first SOC set value, and when the vehicle is on a slope less than a second slope set value, and the motor power assisting power is equal to the acceleration resistance power.

9. The fuel-saving control system of a hybrid vehicle according to claim 6 or 7, wherein the acceleration condition is determined according to a vehicle accelerator pedal opening change rate, and when the vehicle accelerator pedal opening change rate is greater than an opening change set value, it indicates that the vehicle is in the acceleration condition.

10. The fuel saving control system of a hybrid vehicle according to claim 7, wherein the engine optimum torque is composed of torque values at which specific fuel consumption is lowest at different rotation speeds.

Technical Field

The invention relates to an oil-saving control method and an oil-saving control system for a hybrid electric vehicle, and belongs to the technical field of hybrid electric vehicles.

Background

In the aspects of regulations and fuel oil limit values, the third stage fuel oil limit value standard of the limit value of the fuel consumption of a heavy commercial vehicle is about to be executed, the energy-saving and new-energy commercial vehicle point management system is started in 2018, the new-energy vehicle subsidies the grade, for a passenger transport tourism vehicle with high-speed working conditions, the braking energy recovery technology becomes an important technical means for solving the problem of high vehicle oil consumption, and the problem of how to realize oil saving by using a hybrid power technology in the high-speed working conditions becomes a difficult problem to be overcome urgently.

There are many control methods related to fuel saving of hybrid vehicles, but there is no fuel saving control method for high speed working conditions, for example, the publication number CN102756727A discloses a hybrid vehicle torque control method: the hybrid vehicle controller is coupled with and communicated with the engine controller, the transmission controller, the motor controller, the battery controller, the brake anti-lock controller and the vehicle body controller through a whole vehicle local area network bus to judge the current hybrid power mode of the hybrid vehicle; determining a vehicle demand torque and current torques associated with the engine and the electric machine; determining target torques of the engine and the motor from the current hybrid mode and the vehicle demand torque in combination with current torques associated with the engine and the motor; and after receiving the target torques of the engine and the motor distributed by the hybrid vehicle controller, the engine controller and the motor controller control the engine and the motor to gradually realize respective target torques. The method has the advantages of good control precision, good fuel economy and easy matching with the whole vehicle. However, in order to solve the problem of how to distribute the engine torque and the motor torque in the hybrid system, the vehicle required torque is simply distributed to the engine and the motor based on the current hybrid mode and the vehicle required torque of the hybrid vehicle, and the specific torque distribution strategy is not considered in the scheme aiming at the characteristic that the ratio of high-speed working conditions of passenger transport vehicles/tourism vehicles is high, so that the technical scheme still has defects and limitations, and the oil saving effect still has an optimization space. Under the high-speed working condition, the rotating speed of the motor is high, the output power of the motor is large, if the maximum assistance of the motor is considered singly, the SOC allowance of the battery is insufficient, the capacity of the power battery needing to be matched is increased, the cost is increased, and the oil saving effect of the engine is poor.

Disclosure of Invention

The invention aims to provide an oil-saving control method and an oil-saving control system for a hybrid vehicle, which aim to solve the problems of increased power capacity and increased cost caused by only considering the maximum power assistance of a motor under a high-speed working condition.

The invention provides an oil-saving control method of a hybrid vehicle for solving the technical problems, which comprises the following steps:

1) collecting the speed of the vehicle, and judging whether the vehicle is in an acceleration working condition or not when the speed of the vehicle is greater than a speed set value;

2) when the vehicle is in an acceleration working condition, judging whether the SOC of the vehicle power battery is greater than a first SOC set value, and if so, judging the gradient of the vehicle;

3) when the vehicle is on a slope larger than a first slope set value, the output power of the engine is increased, the increased power of the engine is equal to the sum of the acceleration resistance power and the slope resistance power, when the vehicle is on a slope larger than a second slope set value and smaller than the first slope set value, the motor is adopted for assisting, and the assisting power of the motor is equal to the sum of the acceleration resistance power and the slope resistance power.

Under the acceleration working condition, the motor assistance is controlled according to the gradient, and when the vehicle is in the working condition of climbing a large slope, the direct driving of the engine is executed to avoid the rapid decrease of the SOC of the battery and fully exert the power output of the engine; when the vehicle is in the medium-gradient working condition, because the oil consumption of the engine under the transient working condition is high, in order to ensure that the engine is always in the output of the steady-state working condition, the transient power required by the vehicle, such as the ramp resistance power and the acceleration resistance power, is provided by the motor. Through the control, the fuel consumption of the whole vehicle under the high-speed working condition can be effectively reduced while the capacity of the power battery is not increased, and the energy conservation of the whole vehicle is realized.

Further, when the vehicle is in a non-acceleration working condition, whether the SOC of the vehicle power battery is smaller than a second SOC set value or not is judged, if yes, a difference value between the optimal torque of the engine and the current torque is calculated, and if the difference value is not smaller than the set torque value, the power generation torque of the motor is controlled to be equal to the difference value between the optimal torque of the engine and the current torque.

Under the non-acceleration working condition, whether the motor needs to drive the vehicle for power generation is determined according to the difference value parameter of the current output torque of the engine and the optimal torque of the engine, so that the load rate of the engine is improved, the fuel consumption level is reduced, and meanwhile, the SOC of the battery is kept at a reasonable level.

Further, in the step 3), if the slope of the vehicle is smaller than a second slope set value, a motor is used for assisting, and the assisting power of the motor is equal to the accelerating resistance power. For the working condition without ascending slope, the invention controls the motor to provide the acceleration resistance power generated in the acceleration process, so that the engine is always in the output of the steady working condition, and the fuel consumption level is further reduced.

Further, the acceleration condition is determined according to the opening degree change rate of the accelerator pedal of the vehicle, and when the opening degree change rate of the accelerator pedal of the vehicle is greater than the opening degree change set value, the vehicle is in the acceleration condition.

Further, the optimal torque of the engine is composed of the torque value with the lowest fuel consumption rate at different rotating speeds.

The invention also provides an oil-saving control system of the hybrid vehicle, which comprises a vehicle information acquisition unit and a control unit, the vehicle information acquisition unit is used for acquiring the speed of the vehicle, the SOC of the power battery and the gradient of the vehicle, and the collected information is sent to a control unit for processing, the control unit is used for controlling the vehicle speed to be higher than a speed set value, the vehicle is in an acceleration working condition and the SOC of the vehicle power battery is higher than a first SOC set value, and the control is carried out according to the slope of the vehicle, when the slope of the vehicle is larger than the first slope set value, increasing the output power of the engine, wherein the increased power of the engine is equal to the sum of the acceleration resistance power and the ramp resistance power, when the slope of the vehicle is larger than the second slope set value and smaller than the first slope set value, the motor is adopted for assisting, and the assisting power of the motor is equal to the sum of the accelerating resistance power and the ramp resistance power.

Further, the control unit judges whether the SOC of the vehicle power battery is smaller than a second SOC set value or not when the vehicle is in a non-acceleration working condition, if so, a difference value between the optimal torque of the engine and the current torque is calculated, and if not, the generating torque of the motor is controlled to be equal to the difference value between the optimal torque of the engine and the current torque.

Further, when the speed of the vehicle is greater than a speed set value, the vehicle is in an acceleration working condition, and the SOC of the power battery of the vehicle is greater than a first SOC set value, if the slope of the vehicle is smaller than a second slope set value, the control unit uses the motor to assist, and the assist power of the motor is equal to the acceleration resistance power.

Further, the acceleration condition is determined according to the opening degree change rate of the accelerator pedal of the vehicle, and when the opening degree change rate of the accelerator pedal of the vehicle is greater than the opening degree change set value, the vehicle is in the acceleration condition.

Further, the optimal torque of the engine is composed of the torque value with the lowest fuel consumption rate at different rotating speeds.

Drawings

Fig. 1 is a flowchart of a fuel saving control method of a hybrid vehicle;

FIG. 2 is a schematic diagram of an engine optimization curve according to an embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

Embodiment of fuel saving control method for hybrid vehicle of the invention

The fuel-saving control method of the invention aims at that the vehicle is in a high-speed working condition, judges whether the vehicle is in an acceleration working condition, and judges and outputs three working conditions of the assistance of the motor and the engine according to whether the vehicle is in an uphill working condition or not in the uphill working condition if the vehicle is in the acceleration working condition: when the vehicle is in a heavy-slope working condition, in order to avoid the rapid reduction of the SOC of the battery and fully exert the power output of the engine, the engine is directly driven, and when the vehicle is in a medium-slope working condition, because the oil consumption of the engine under the transient working condition is high, in order to ensure that the engine is always in the output of the steady-state working condition, the transient power required by the vehicle, such as the ramp resistance power and the acceleration resistance power, is provided by the motor. The invention can effectively reduce the fuel consumption of the whole vehicle under the high-speed working condition and realize the energy conservation of the whole vehicle. The specific implementation flow of the method is shown in fig. 1, and the following detailed description is provided for each implementation step.

1. And judging whether the vehicle is in an acceleration working condition or not.

The invention aims at the high-speed working condition, so that whether the vehicle speed is greater than or equal to a speed set value A or not needs to be judged firstly, if the vehicle speed is greater than or equal to the speed set value A, the vehicle is in the high-speed working condition, and then the acceleration working condition is judged. The acceleration condition of the invention is determined by judging the opening degree change rate of the accelerator pedal, and the opening degree change rate of the accelerator pedal is obtained by calculating the opening degree value of the accelerator pedal at corresponding time intervals. If the calculated accelerator pedal opening change rate is larger than or equal to the set opening change rate B, the vehicle is in an acceleration working condition, otherwise, the vehicle is in a non-acceleration working condition.

2. And controlling the vehicle under an acceleration condition.

When the vehicle is in an acceleration working condition, judging whether the SOC value of the power battery of the vehicle is larger than a first SOC set value C, if so, indicating that the SOC allowance of the power battery meets the requirement, and judging and outputting three working conditions of motor assistance according to whether the power battery is in an uphill working condition or not. The gradient is obtained through equipment such as a gyroscope, an accelerometer sensor and the like.

When the vehicle is located at a slope larger than a first slope set value E, namely a large slope, in order to avoid the rapid decrease of the SOC of the power battery and fully exert the power output of the engine, the direct drive of the engine is executed, the output power of the engine is increased, and the increased power of the engine is equal to the sum of the acceleration resistance power and the slope resistance power; when the gradient of the vehicle is greater than or equal to the second gradient set value D and less than or equal to the first gradient set value E, the vehicle is in a medium-gradient working condition, and because the fuel consumption of the transient working condition of the engine is high, in order to ensure that the engine is always in the output of a steady-state working condition, the transient power required by the vehicle, such as ramp resistance power and acceleration resistance power, is provided by the motor, namely the power-assisted power of the motor is the sum of the acceleration resistance power and the ramp resistance power; when the vehicle is at a slope smaller than the second slope set value D, the vehicle is in a non-uphill working condition, only acceleration resistance power exists at the same time, and the motor provides the acceleration resistance power generated in the acceleration process, so that the engine is always in steady-state working condition output, and the fuel consumption level is lowest.

3. And controlling the vehicle under the non-acceleration working condition.

When the vehicle is in a non-acceleration working condition, whether the motor needs to drive the vehicle for power generation is determined according to parameters such as the battery SOC, the difference value of the current output torque of the engine and the optimal torque of the engine, so that the load factor of the engine is improved, the fuel consumption level is reduced, and meanwhile, the battery SOC is kept at a reasonable level. And when the SOC value of the vehicle power battery is less than or equal to a second SOC set value F, calculating the difference value between the optimal torque of the engine and the current torque, and if the difference value is not less than a set torque value G, controlling the power generation torque of the motor to be equal to the difference value between the optimal torque of the engine and the current torque.

The optimal engine torque is composed of torque values with the lowest fuel consumption rate at different rotating speeds, the optimal engine torque adopted in the embodiment is shown in fig. 2 and obtained by performing experimental calibration on the vehicle at different rotating speeds, and the optimal engine torque value determined by a certain engine adopted in the embodiment is shown in table 1.

TABLE 1

Rotational speed, rpm	900	1100	1300	1500	1700	1900	2100	2300
									Optimum torque value, Nm	425	475	590	710	710	620	600	600

The set torque value G in this embodiment is 250Nm, under a high-speed condition, the output torque value of the engine at this time is 500Nm, and the rotation speed is 1700 rpm, that is, the engine operates at the point a in fig. 2, as can be known from table 1, the optimal torque value of the engine at this time is 710Nm, and the optimal torque value of the engine, that is, the current output torque value of the engine, that is, 210Nm < G, that is, 250Nm, so that the motor does not need to run for power generation under this condition; if the engine is operated at point C in fig. 2, the engine output torque value at this time is 350Nm, the rotation speed is 1700 rpm, and similarly, the engine optimum torque value — the engine current output torque value is 260Nm > G250 Nm, so the motor generated torque value in this condition is 260 Nm.

The set values related to the invention, such as the vehicle speed A, the accelerator pedal opening degree change rate B, the SOC values C and F of the power battery, the gradients D and E, the torque value G and the like, are not fixed values, are related to the vehicle type and the power configuration, and can be obtained by calibration according to different vehicle types and different power configurations.

Embodiment of fuel-saving control system for hybrid vehicle

The fuel-saving control system comprises a vehicle information acquisition unit and a control unit, wherein the vehicle information acquisition unit is used for acquiring the speed, the SOC (state of charge) of a power battery and the gradient of the vehicle and sending the acquired information to the control unit for processing, the control unit is used for controlling according to the gradient of the vehicle when the speed of the vehicle is greater than a speed set value, the vehicle is in an acceleration working condition and the SOC of the power battery of the vehicle is greater than a first SOC set value, when the gradient of the vehicle is greater than a first gradient set value, the output power of an engine is increased, the increased power of the engine is equal to the sum of the acceleration resistance power and the ramp resistance power, when the gradient of the vehicle is greater than a second gradient set value and is less than the first gradient set value, the motor is used for assisting power, and the assisting power of the motor is equal to the sum.

Specifically, the vehicle information acquisition unit may be a sensing device for vehicle speed, accelerator pedal opening, engine speed, and engine torque, or may be acquired through a CAN bus of the vehicle, and the slope where the vehicle is located may be acquired through equipment such as a gyroscope and an accelerometer sensor. The control unit can adopt a vehicle control unit, and the vehicle control unit generates a corresponding control strategy according to the information of the vehicle information acquisition unit, sends the control strategy to the motor controller and controls the engine and the motor to execute corresponding actions.

Under a high-speed non-acceleration working condition, the motor is driven to generate electricity to improve the load rate of the engine, reduce the fuel consumption level and simultaneously keep the SOC of the battery at a reasonable level; when the vehicle is in a working condition of climbing a large slope, the engine is directly driven to avoid the rapid reduction of the SOC of the battery; when the vehicle is in a medium-gradient working condition, the motor provides transient power required by the vehicle to ensure the steady-state working condition output of the engine; when the engine is in a non-uphill working condition, the motor provides acceleration resistance power generated in the acceleration process, so that the engine is always in steady state working condition output, and the fuel consumption level is lowest. Through the control of the whole process, the invention can effectively reduce the fuel consumption of the whole vehicle under the high-speed working condition and realize the energy conservation of the whole vehicle.