CN112644331B

CN112644331B - Range-extending type electric automobile energy control method based on battery electric quantity increase rate

Info

Publication number: CN112644331B
Application number: CN202110057174.1A
Authority: CN
Inventors: 包旭; 汪伟; 贝绍轶; 吴玉峰; 鲁正; 崔修杰; 马树清
Original assignee: Jiangsu University of Technology
Current assignee: Jiangsu University of Technology
Priority date: 2021-01-15
Filing date: 2021-01-15
Publication date: 2022-05-13
Anticipated expiration: 2041-01-15
Also published as: CN112644331A

Abstract

The invention discloses a range-extended electric vehicle energy control method based on a battery electric quantity increase rate, which selects the charging time of a battery and intervenes the charging speed of the battery through the battery electric quantity increase rate Q, wherein the battery electric quantity increase rate Q is the change value of the SOC of the battery detected in two adjacent times. The method of the invention maximally utilizes the electric quantity stored in the battery, and only when the electric quantity is less than 60%, Q is less than or equal to-3%, and the SOC of the electric quantity is less than or equal to 30%, the engine is started to drive the generator to generate electricity to supplement the electricity for the battery, thereby properly prolonging the endurance mileage. Under other working conditions, the battery is supplied with electricity by only recovering the braking energy. This scheme both has been convenient for the driver and has been utilized the mileage of extension to look for and fill electric pile, reduces the start-up number of times of engine again and reduces the use of fuel, reduces harmful gas's emission to reduce the cost of using fuel.

Description

Range-extending type electric automobile energy control method based on battery electric quantity increase rate

Technical Field

The invention relates to a range-extending type electric automobile energy control method based on the battery electric quantity increase rate.

Background

Because the electric quantity of the battery is limited, the pure electric vehicle must find nearby charging piles as soon as possible to supplement the electricity before the electric quantity of the battery is exhausted. And when the power is supplemented, the charging speed is low, the waiting time is long, the number of nearby idle charging piles with perfect functions is limited, so that various charging-related problems can occur to a vehicle owner of the electric vehicle in the long-distance driving process, and the popularization range of the electric vehicle is narrow.

Therefore, the appearance of the extended range electric vehicle overcomes the problem of difficult charging, and is beneficial to prolonging the driving mileage of the electric vehicle. However, in contrast to hybrid vehicles, extended range electric vehicles still run with the wheels directly driven by the electric motor, and their primary energy source is still derived from a fully charged battery. In order to reduce the weight of the automobile and reduce energy consumption, an internal combustion engine (or an engine) which is arranged on the extended-range electric automobile and used for driving a generator to work has smaller displacement and power, generally cannot directly drive the automobile to run, but is only used for driving the generator to generate electricity, and the generated electric energy is used for supplementing electricity to a battery, so that the running mileage of the electric automobile is effectively prolonged, and the automobile is prevented from stopping running due to the exhaustion of electric quantity when no effective charging pile is arranged around. Therefore, the generator driven by the engine is not enough to directly supply the motor for a long time and drive the automobile to run, and is a midway supplement source of electric energy to slow down the consumption speed of the electric quantity in the battery and prolong the running distance when only the battery supplies power, so that a driver has enough time to search for a charging pile to supplement the electric energy. When the electric quantity in the battery is too low, still need look for and fill electric pile and supply electricity, the car just can continue to travel.

In the prior art, an energy distribution or control strategy of an electric vehicle or a range-extended electric vehicle is mainly based on a battery index, namely a state of charge (SOC), which reflects the remaining battery capacity. However, the charging and discharging performances of the battery at different temperatures are greatly different, for example, in winter, the electric quantity after the battery is fully charged is smaller than that in other seasons, so that the electric quantity in the battery is consumed faster than that in other seasons, that is, under the same vehicle driving condition, the power down speed of the battery is faster in winter under the same 100% electric quantity condition, so that the driving mileage of the electric vehicle in winter is smaller than that in other seasons, and therefore, it is not accurate enough to perform energy distribution or control based on the SOC value of the remaining electric quantity alone.

Disclosure of Invention

Compared with the prior art, the energy control method for the extended-range electric automobile can further prolong the driving mileage of the automobile, enables a driver to have more driving mileage for finding a proper charging pile and improves the convenience of the electric automobile in long-distance driving.

In order to solve the technical problems, the invention provides the following technical scheme:

in the invention, a new reference index, namely a battery charge increase rate Q, is added in addition to the SOC index, and is defined as the change value (percentage) of the SOC of the battery detected in two adjacent times, wherein when the battery charge detected in the two adjacent times is increased, Q is a positive value, when the battery charge is decreased, Q is a negative value, and the time interval between the two adjacent times is T. Through the index, the charging and discharging speed of the battery can be accurately monitored under the temperature in different seasons, and the charging and discharging speed of the battery can be monitored under different automobile running conditions or loads, so that the charging and discharging conditions of the battery can be known in time, the charging opportunity of the battery is selected in advance and the charging speed of the battery is interfered, and the interference is not performed when the SOC in the battery is too low, so that the electric quantity in the battery can be kept in a set reasonable interval, and the running mileage of the electric automobile can be further prolonged. In the invention, the automobile can recover the braking energy only when the driver steps on the brake pedal, thereby reducing the intervention frequency of the braking energy recovery and improving the driving smoothness. Meanwhile, the sliding distance of the vehicle after the driver looses the accelerator is also improved.

The working process of the invention comprises the following steps:

s1, starting a controller for energy distribution;

s2, using the battery module for monitoring the voltage and current of the battery, the controller measures the voltage and current value of the battery, and calculates the SOC value (percentage of the remaining capacity) of the battery;

s3, (1) if the SOC is more than or equal to 60%, which indicates that the battery electric quantity is sufficient, detecting and judging the electric quantity increase rate Q of the battery, if Q is more than-3%, setting the intensity of the braking energy recovery at the lowest 1 grade by the controller, and replenishing the battery with the lowest energy recovery rate when a driver steps on a braking pedal; if Q is less than or equal to-3%, the controller sets the intensity of the recovery of the braking energy at a higher 2-gear, and the battery is recharged with a higher energy recovery rate when a driver steps on a braking pedal;

(2) if the SOC is more than 30% and less than 60%, which indicates that the battery electric quantity is moderate, the battery electric quantity increase rate Q is detected and judged,

1) if Q is less than or equal to minus 3 percent, the battery power consumption speed is over high, the engine is started and drives the generator to generate power so as to supplement the power for the battery, and then the battery power increase rate Q is detected again and judged; if Q is more than-3% < 0, the controller sets the intensity of the braking energy recovery at the middle 2 grades, so that the braking force generated during the energy recovery is moderate, and the energy recovery rate is moderate; if Q is more than or equal to 0, the controller sets the strength of the braking energy recovery at the lowest 1 gear, so that the braking force generated during the energy recovery is the minimum, the running smoothness of the automobile is improved, and the energy recovery rate is the lowest; if Q is less than or equal to-3%, the controller sets the strength of the braking energy recovery at the strongest 3 grades, so that the braking force generated during the energy recovery is the largest, the smoothness of the automobile running is poor, but the energy recovery rate is the highest, and the quick power supplement to the battery is facilitated;

2) if Q is more than or equal to-2%, the controller sets the braking energy recovery intensity at the 1 gear;

3) if-3% < Q < -2%, the controller sets the braking energy recovery intensity in gear 2.

(3) If the SOC is less than or equal to 30%, the engine is started and drives the generator to generate electricity, the electricity quantity increase rate Q of the battery is detected and judged, and if the Q is more than 3 percent and less than 0, the controller sets the intensity of braking energy recovery at the middle 2 gear; if Q is more than or equal to 0, the controller sets the intensity of the braking energy recovery at the lowest 1 grade; if Q is less than or equal to-3%, the controller sets the strength of the braking energy recovery at the strongest 3 gear; thereby having a corresponding energy recovery rate and generating a corresponding braking force.

S4, the process returns to S2, and the process is repeated.

In the above steps, the duration after the engine is started to generate power is 10 minutes, and the engine is stopped after 10 minutes. When engine start is again required, the engine will be started again and run for 10 minutes. When the increase rate of the electric quantity of the battery is detected, the time interval between the two adjacent detection is T, the setting is carried out according to the average running speed of the automobile, if the average running speed V is less than or equal to 30km/h, the road is congested, a driver needs to frequently step on a brake to decelerate or stop the automobile, the automobile correspondingly carries out braking energy recovery, the frequency of the energy recovery is high, and the T is set to be 2 minutes, so that the influence of the braking energy recovery on the electric quantity of the battery can be more accurately judged; if the average speed is 30km/h < V < 60km/h, the road is smooth, the driver has the function of properly decelerating when stepping on the brake, the frequency of stepping on the brake is lower, correspondingly, the frequency of recovering the braking energy of the automobile is lower, and T is set to be 5 minutes, so that enough time is reserved for judging the influence of the recovery of the braking energy on the electric quantity of the battery; similarly, if the average speed V is greater than 60km/h, the road is quite smooth, a driver rarely steps on a brake to brake, the frequency of energy recovery is lowest, and T is set to be 10 minutes.

The hardware in the invention at least comprises: the system comprises a controller, a battery module capable of monitoring the performance of a battery, a motor capable of driving wheels and generating electricity by back dragging of the wheels, a generator and an engine. The controller is connected with and controls the operation of the battery module, the motor, the generator and the engine.

The engine is started to drive the generator to generate power with set power output, the braking energy recovery is 1 grade, 2 grades and 3 grades from low to high in sequence according to the intensity of energy recovery, wherein the recovery intensity of the 1 grade is 25% of the maximum braking energy recovery intensity of the vehicle, the recovery intensity of the 2 grade is 50% of the maximum braking energy recovery intensity of the vehicle, and the recovery intensity of the 3 grade is the maximum braking energy recovery intensity of the vehicle. The higher the recovery intensity of the braking energy, the higher the recovery rate of the energy, the larger the braking force, the more obvious the braking effect of the automobile felt by a driver, and the smoother the running. Therefore, from the perspective of ensuring the driving smoothness of the automobile, the intensity of recovering the braking energy is lower as much as possible, so that the comfort of a driver and passengers in the automobile is better. Meanwhile, in order to maximally utilize the electric quantity stored in the battery, the engine is started to drive the generator to generate electricity to supplement the electricity for the battery only when the electric quantity is less than 60%, Q is less than or equal to-3% and the SOC is less than or equal to 30%, and the endurance mileage is prolonged moderately. Under other working conditions, the battery is supplied with electricity by only recovering the braking energy.

The extended-range electric vehicle energy control method based on the battery power increase rate has the advantages that a driver can conveniently find a charging pile by using an extended mileage, the starting times of an engine are reduced to reduce the consumption of fuel, the emission of harmful gas is reduced, and the cost of using the fuel is reduced; after finding the charging pile, the driver charges the electric automobile and then continues to drive by utilizing the charged electric quantity. This scheme makes the car mainly still fill the electric quantity that fills the electric pile into the battery and drive the car and go, has reduced the use cost of car, improves the car and seeks to fill the convenience that electric pile charges, has reduced harmful exhaust's emission.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a flow chart of the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Examples

As shown in fig. 1: the range-extended electric vehicle energy control method based on the battery electric quantity increase rate comprises the following steps:

s1, starting a controller for energy distribution;

s2, calculating the SOC value of the battery by using the battery module for monitoring the voltage and the current of the battery through the controller;

s3, selecting an appropriate control strategy by the controller according to the SOC value:

when the SOC is more than or equal to 60 percent, detecting and judging the increase rate Q of the battery electric quantity,

(1) when Q > -3%, the controller sets the intensity of the recovered braking energy at the lowest 1 st gear, and then when a driver steps on a braking pedal, the battery is replenished with electricity at the lowest energy recovery rate;

(2) q is less than or equal to-3%, the controller sets the intensity of the recovered braking energy at a higher 2-gear, and the battery is charged with higher energy recovery rate when a driver steps on a brake pedal;

when the SOC is more than 30% and less than 60%, detecting and judging the battery electric quantity increase rate Q,

(1) q is less than or equal to-3%, the engine is started and drives the generator to generate electricity, so that electricity is supplemented for the battery;

and (3) detecting and judging the Q value again:

1) -3% < Q < 0, the controller sets the intensity of braking energy recovery in the middle gear 2;

2) q is more than or equal to 0, the controller sets the strength of braking energy recovery at the lowest 1 level,

3) q is less than or equal to-3%, and the controller sets the strength of braking energy recovery at the strongest 3 grades;

(2) if Q is more than or equal to-2%, the controller sets the braking energy recovery intensity at the 1 gear;

(3) if-3% < Q < -2%, the controller sets the braking energy recovery intensity in gear 2.

When the SOC is less than or equal to 30%, the engine is started and drives the generator to generate electricity, so that the battery is supplied with electricity, and the Q value is detected and judged:

(1) -3% < Q < 0, the controller sets the intensity of braking energy recovery in the middle gear 2;

(2) q is more than or equal to 0, and the controller sets the strength of braking energy recovery at the lowest 1 grade;

(3) if Q is less than or equal to-3%, the controller sets the strength of the braking energy recovery at the strongest 3 grades;

s4, repeat S2, and repeat the loop again.

In order to prevent the control flow from interfering with the started engine, the continuous working time after the engine is started to generate power is 10 minutes, and then the engine is stopped until the engine is started again by the control flow. .

The method of the invention maximally utilizes the electric quantity stored in the battery, and only when the electric quantity is less than 60%, Q is less than or equal to-3%, and the SOC of the electric quantity is less than or equal to 30%, the engine is started to drive the generator to generate electricity to supplement the electricity for the battery, thereby properly prolonging the endurance mileage. Under other working conditions, the battery is supplied with electricity by only recovering the braking energy. This scheme both has been convenient for the driver and has been utilized the mileage of extension to look for and fill electric pile, reduces the start-up number of times of engine again and reduces the consumption of fuel, reduces harmful gas's emission to reduce the cost of using fuel.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The energy control method of the extended-range electric automobile based on the battery electric quantity growth rate is characterized in that the charging time of a battery is selected through the battery electric quantity growth rate Q and the charging speed of the battery is intervened, wherein the battery electric quantity growth rate Q is a change value of the SOC of the battery detected in two adjacent times; the method specifically comprises the following steps:

s1, starting a controller for energy distribution;

s2, using the battery module for monitoring the voltage and current of the battery, the controller measures the voltage and current value of the battery, and calculates the SOC value of the battery;

s3, selecting an appropriate control strategy according to the SOC value:

when the SOC is more than or equal to 60 percent and Q is > -3 percent, the controller sets the intensity of the recovered braking energy at the lowest 1 gear, and the battery is recharged with the lowest energy recovery rate when a driver steps on a braking pedal;

when the SOC is more than or equal to 60 percent and the Q is less than or equal to minus 3 percent, the controller sets the intensity of the recovery of the braking energy at a higher 2-gear, and the battery is recharged with a higher energy recovery rate when a driver steps on a braking pedal;

when the SOC is more than 30 percent and less than 60 percent and the Q is less than or equal to-3 percent, the engine is started and drives the generator to generate electricity so as to supplement the electricity for the battery; then, the battery electric quantity increase rate Q is detected again and judged, if the battery electric quantity increase rate Q is detected again and is larger than-3% < Q < 0, the controller sets the braking energy recovery strength to the middle 2, so that the braking force generated during energy recovery is moderate, and the energy recovery rate is moderate; if Q is detected to be more than or equal to 0 again, the controller sets the strength of the braking energy recovery at the lowest 1 gear, so that the braking force generated during the energy recovery is the minimum, the running smoothness of the automobile is improved, and the energy recovery rate is the lowest; if the Q is detected to be less than or equal to minus 3 percent again, the controller sets the strength of the braking energy recovery at the strongest 3 grades, so that the braking force generated during the energy recovery is maximized, the running smoothness of the automobile is poor, but the energy recovery rate is the highest, and the quick power supplement of the battery is facilitated;

when SOC is more than 30% and less than 60%, Q is more than-3% and less than-2, the controller sets the intensity of braking energy recovery in the middle gear 2;

when the SOC is more than 30 percent and less than 60 percent and the Q is more than or equal to-2, the controller sets the intensity of the braking energy recovery at the lowest 1 gear,

when the SOC is less than or equal to 30%, the engine is started and drives the generator to generate electricity, the electricity quantity increase rate Q of the battery is detected and judged, and if the Q is more than 3 percent and less than 0, the controller sets the intensity of braking energy recovery at the middle 2 gear; if Q is more than or equal to 0, the controller sets the intensity of the braking energy recovery at the lowest 1 grade; if Q is less than or equal to-3%, the controller sets the strength of the braking energy recovery at the strongest 3 gear; thereby having corresponding energy recovery rate and generating corresponding braking force;

s4, repeat S2, and repeat the loop again.

2. The energy control method for the extended-range electric vehicle based on the battery power increase rate as claimed in claim 1, wherein the duration of the engine start-up power generation is 10 minutes, then the engine is stopped, and when the engine start-up is required again, the engine is started again and continues to operate for 10 minutes.

3. The energy control method of extended-range electric vehicle based on battery power increase rate as claimed in claim 1, wherein when the battery power increase rate Q is detected, the time interval between two adjacent detections is T, T is set according to the average vehicle speed of the vehicle, and if the average vehicle speed V is less than or equal to 30km/h, T is set to 2 minutes;

if the average vehicle speed is 30km/h < V is less than or equal to 60km/h, setting T as 5 minutes;

if the average vehicle speed V >60km/h, T is set to 10 minutes.

4. The energy control method of the extended-range electric vehicle based on the battery power increase rate as claimed in claim 1, wherein the recovery intensity of 1 gear of the recovery of the braking energy according to the intensity of the energy recovery is 25% of the maximum recovery intensity of the braking energy of the vehicle, the recovery intensity of 2 gears is 50% of the maximum recovery intensity of the braking energy of the vehicle, and the recovery intensity of 3 gears is the maximum recovery intensity of the braking energy of the vehicle.