KR102435345B1 - Eco-friendly vehicle and method of controlling battery thereof - Google Patents

Abstract

The present invention relates to an eco-friendly vehicle and a battery control method therefor, and more particularly, to a battery control method for preventing a sudden cell voltage drop of a battery, and an eco-friendly vehicle for performing the same. According to an embodiment of the present invention, there is provided a method for controlling battery output of an eco-friendly vehicle, the method comprising: determining whether a battery for driving an electric motor has continuous output; calculating a first energy, which is battery accumulated energy used for a first time, when it is determined as a continuous output as a result of the determination; and reducing the output of the battery by a first ratio when the first energy is greater than the second energy that is the output limiting energy reference.

Description

ECO-FRIENDLY VEHICLE AND METHOD OF CONTROLLING BATTERY THEREOF

The present invention relates to an eco-friendly vehicle and a battery control method therefor, and more particularly, to a battery control method for preventing a sudden cell voltage drop of a battery, and an eco-friendly vehicle for performing the same.

The demand for eco-friendly vehicles is increasing as the demand for continuous improvement of fuel efficiency for vehicles and the strengthening of emission gas regulations in each country is increasing. /PHEV) and eco-friendly vehicles such as electric vehicles (EVs) are being provided.

An eco-friendly vehicle may generally use an electric motor as a driving force, and a battery for supplying electric power for driving the electric motor is mounted, and the battery generally includes a plurality of cells. In order to increase the mileage of a vehicle using such an electric motor, the energy density per unit volume of the battery is increasing. However, as the energy density per unit volume increases, the volume for storing the same energy decreases, but there may be a disadvantage in the continuous output of the battery. That is, when excessive continuous output is continued, problems such as abrupt drop in output or damage to durability due to a sudden drop in cell voltage may occur. This will be described with reference to FIG. 1 .

1 is a view for explaining the cell voltage characteristics of a typical eco-friendly vehicle battery. In FIG. 1 , it is assumed that the vehicle is rapidly accelerated using only the power of the electric motor.

Referring to FIG. 1 , as the rapid acceleration is performed, the power consumption of the battery rapidly increases, and the speed of the vehicle also increases. As a certain speed is reached, the battery power decreases somewhat, but a considerable amount of power is continuously consumed to maintain the speed. As a result, considerable power is continuously output from the viewpoint of the battery, and the cell voltage of the battery gradually decreases according to this continuous output. Control to prevent further drop in voltage is performed.

However, when this control is performed, the battery output is suddenly lowered, so a shock is felt due to a sudden sense of deceleration.

An object of the present invention is to provide a method for more efficiently controlling a battery in an eco-friendly vehicle having an electric motor.

In particular, an object of the present invention is to provide an eco-friendly vehicle capable of more efficiently controlling a cell voltage drop of a battery in a continuous output situation, and a method for controlling the same.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. will be able

In order to solve the above technical problem, a method for controlling battery output of an eco-friendly vehicle according to an embodiment of the present invention includes: determining whether a battery for driving an electric motor has continuous output; calculating a first energy, which is battery accumulated energy used for a first time, when it is determined as a continuous output as a result of the determination; and reducing the output of the battery by a first ratio when the first energy is greater than the second energy that is the output limiting energy reference.

In addition, an eco-friendly vehicle according to an embodiment of the present invention, an electric motor for generating a driving force; a battery for supplying power to the electric motor; and determining whether the battery has continuous output, and when it is determined as continuous output as a result of the determination, a first energy that is the battery accumulated energy used for a first time is calculated, and the first energy is a second energy that is an output-limited energy standard If greater, it may include a battery management system (BMS) that controls the output of the battery to decrease by a first ratio.

The eco-friendly vehicle according to at least one embodiment of the present invention configured as described above may perform battery control more efficiently.

In particular, by controlling the cell voltage drop criterion in stages according to the determination of continuous output, a sudden decrease in output or a sense of delay is alleviated, and the durability of the battery is protected, but the amount of available energy is increased.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art from the following description. will be.

1 is a view for explaining the cell voltage characteristics of a typical eco-friendly vehicle battery.
2 is a flowchart illustrating an example of a battery control process according to an embodiment of the present invention.
3 shows an example of the form of an APS lookup table for determining whether continuous output is performed according to an embodiment of the present invention.
4 shows an example of the form of an output limited energy reference table according to an embodiment of the present invention.
5 is a block diagram illustrating an example of a vehicle structure according to an embodiment of the present invention.
6 is a diagram for explaining an effect of battery output control according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. In addition, parts indicated with the same reference numerals throughout the specification mean the same components.

In an embodiment of the present invention, when it is determined that the battery is in a continuous output state in an eco-friendly vehicle having an electric motor, the accumulated energy consumption of the battery is calculated for a predetermined period from the detection time, and the calculated cumulative usage is based on a preset standard. It is proposed to reduce the output of the battery stepwise by a predetermined ratio whenever it is exceeded. This will be described with reference to FIG. 2 .

2 is a flowchart illustrating an example of a battery control process according to an embodiment of the present invention.

Referring to FIG. 2 , as driving using the electric motor (ie, driving in EV mode) starts, it may be determined whether the battery is in a continuous output state ( S210 ).

Whether the continuous output state is determined may be determined through at least one method of location information-based (S210A) and accelerator pedal sensor (APS) value-based (S210B).

In more detail, the location information-based determination may be performed in a GPS module or an AVN (Audio/Video/Navigation) system that obtains location information therefrom, and the current location generally requires continuous output (eg, a highway). .

In addition, the determination of the APS value reference may be determined based on whether the APS value is at a level causing a cell voltage drop in consideration of factors affecting the output of the battery. Here, the factors affecting the output of the battery include temperature and a state of charge (SOC) of the battery. In addition, for the determination of the APS value reference, a reference table indicating a threshold value for generating a cell voltage drop based on the SOC and temperature for the battery of the corresponding vehicle may be used. This reference table configuration will be described with reference to FIG. 3 .

3 shows an example of the form of an APS lookup table for determining whether continuous output is performed according to an embodiment of the present invention.

In the table of FIG. 3 , the horizontal direction indicates the SOC of the battery and the vertical direction indicates the battery temperature, respectively, and the values of the columns specified by the SOC and the temperature indicate the APS value. The configuration of this table indicates the output characteristics of the battery, and each column may be a threshold value at which a cell voltage drop that is problematic at the corresponding SOC and temperature does not occur. For example, when the SOC is 30 and the temperature is minus 5 degrees, if the APS value is 23% or less, the cell voltage drop is not a big problem even if the output corresponding to the APS value is continuously generated, but the APS value exceeds 23% In this case, a drop in cell voltage may occur. On the other hand, the point where the APS value is displayed as 0 can be regarded as a condition in which a sudden drop in cell voltage occurs when continuous output is requested from the battery. After all, the lower the APS value, the more frequently the output limiting is performed, and the higher the value, the opposite. Of course, the configuration of the table shown in FIG. 3 may be different for each vehicle type and for each battery.

Returning to FIG. 2 again, when it is determined that the continuous output state is determined, the accumulated energy usage (output) of the battery may be calculated from the determination time ( S220 ). The accumulated energy usage may be calculated by integrating the output of the battery while driving, and the output of the battery may be calculated as a product of the battery voltage and current. The output of the battery may be performed by a battery management system (BMS), but is not limited thereto.

When the accumulated energy usage for the first predetermined time (a second, for example, 15 seconds) exceeds the output limit energy criterion (S230), the battery output limit may be performed (S270).

In this case, the output limit energy reference may be calculated as a first ratio of an output corresponding to a case in which the maximum energy that the current battery can output is generated for a second predetermined time. Here, the second predetermined time may be set as a time for maintaining the maximum output, and the maximum output may be a unique characteristic of the battery determined according to the SOC and temperature. Also, the first ratio may be set to a ratio corresponding to the amount of energy used in which the cell voltage drop rapidly occurs. For example, when the second predetermined time is 15 seconds for a certain battery and the first ratio is 70%, the battery can maintain the maximum output for 15 seconds, and when more than 70% of the maximum power is used for 15 seconds, the cell It can be seen that the voltage drop occurs abruptly. As a result, if the energy consumption for 15 seconds is used at 70% or less of the maximum power, it is regarded as a situation in which the same output can be generated for the next 15 seconds, and thus it can be determined that the limitation due to the continuous output is unnecessary. The first predetermined time and the second predetermined time are preferably the same, but not necessarily the same.

Such an output limiting energy reference may have the form of a reference table, and an example thereof will be described with reference to FIG. 4 .

4 shows an example of the form of an output limited energy reference reference table according to an embodiment of the present invention.

In the table of FIG. 4, the horizontal direction indicates the battery's SOC and the vertical direction indicates the battery temperature, respectively, and the values in the column specified by the SOC and temperature are energy consumption values when 70% of the maximum power is used for 15 seconds (unit: KWs) indicates For example, when the SOC is 30 and the temperature is 5 degrees, it can be seen that there is no fear of a sudden drop in the cell voltage even if energy corresponding to a total of 1461.2 KWs is used for 15 seconds. Of course, the configuration of the table shown in FIG. 4 may be different for each vehicle type and for each battery.

Returning again to FIG. 2 , the adjusted output according to the output limit of the battery may be an output that is reduced by a second ratio from the current output (eg, 90% of the current output). After the output is adjusted, determination (S210A, S210B) of continuous output may be performed again.

However, before the actual output limitation is performed, the battery cell voltage condition and the battery voltage may be further considered.

Specifically, when the battery cell voltage becomes less than the cell voltage that needs to be protected in terms of durability (hereinafter, referred to as the “durability reference cell voltage” for convenience, for example, 2V) (S240), the addition of the cell voltage as in general control In order to prevent a drop, the battery output may be rapidly limited ( S250 ).

When the battery cell voltage is equal to or greater than the endurance reference cell voltage, when the battery voltage is smaller than the voltage requiring output limitation (hereinafter, referred to as "output limitation required voltage" for convenience) (S260), gentle output limitation may be performed. (S270). If the battery voltage is higher than the required output limiting voltage, the output limit is unnecessary, so the process returns to the used energy calculation step (S220) again.

Here, the required output limiting voltage may be a value obtained by multiplying the minimum voltage guaranteed in terms of durability by a factor (K). The lowest voltage guaranteed in terms of durability may be a characteristic characteristic of the battery. In addition, the coefficient K is greater than 1, and may increase as the SOC of the battery decreases and the temperature of the battery decreases.

In the above-described process, each determination process, calculation of values necessary therefor, and storage/referencing of reference data may be performed in the BMS, but is not necessarily limited thereto. For example, a separate controller for controlling the output of the battery may be provided in the vehicle, and a controller other than the BMS performs judgment and calculation for this output control function and then transmits the battery output control command to the BMS. it might be

Hereinafter, a vehicle structure for performing the above-described battery output control process will be described with reference to FIG. 5 .

5 is a block diagram illustrating an example of a vehicle structure according to an embodiment of the present invention.

Referring to FIG. 5 , the vehicle according to the present embodiment may include a battery 510 , a BMS 520 , an inverter 530 , and an electric motor 540 . Each component shown in FIG. 5 is not limited by its name, and in actual vehicle implementation, a function corresponding to one component is distributed to a plurality of devices, or a function corresponding to two or more components is implemented in one It may also be implemented as a device.

Hereinafter, each component will be described.

The battery 510 may include a plurality of cells, and the BMS 520 may monitor the state (SOC, temperature, voltage, current, etc.) of the battery and control the output power. Also, the BMS 520 may perform at least some of the processes described above with reference to FIG. 2 .

The inverter 530 converts the DC output of the battery 510 into an AC output and supplies it to the electric motor 540 , and may also serve as a controller of the electric motor 540 .

Of course, although not shown in FIG. 5 , an upper controller that controls the BMS 520 and the inverter 530 according to the vehicle type, for example, a vehicle controller (VCU: Vehicle Control Unit) or a hybrid controller (HCU: Hybrid Control Unit) may be additionally provided.

The effect of the above-described battery output control will be described with reference to FIG. 6 .

6 is a view for explaining the effect of battery output control according to an embodiment of the present invention.

First, the basic assumption (rapid acceleration) in FIG. 6A is similar to FIG. 1 . Referring to FIG. 6A , in general control, as described above with reference to FIG. 1 , when the cell voltage becomes less than a predetermined value due to continuous output, the battery output is rapidly limited to protect the battery. However, according to the control according to the present embodiment, the control to reduce the output by calculating the amount of power consumption before the cell voltage abruptly drops is performed, so that a sudden drop in output or deterioration in drivability can be prevented.

In addition, as shown in (b) of FIG. 6 , in the battery output control method according to the present embodiment, since the battery output decreases in stages, the effect of increasing the battery energy that can actually be used is higher than that of general control in a continuous output situation. have.

The present invention described above can be implemented as computer-readable code on a medium in which a program is recorded. The computer-readable medium includes all kinds of recording devices in which data readable by a computer system is stored. Examples of computer-readable media include Hard Disk Drive (HDD), Solid State Disk (SSD), Silicon Disk Drive (SDD), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. There is this.

Accordingly, the above detailed description should not be construed as restrictive in all respects but as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all transitions within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (19)

In the battery output control method of an eco-friendly vehicle,
determining whether a battery for driving an electric motor has continuous output;
calculating a first energy, which is battery accumulated energy used for a first time, when it is determined as a continuous output as a result of the determination; and
and reducing the output of the battery by a first ratio when the first energy is greater than a second energy that is an output limiting energy reference. The method of claim 1,
The step of determining whether the continuous output is
A method for controlling battery output, which is performed through at least one of location information and an accelerator pedal sensor value. 3. The method of claim 2,
The step of determining whether the continuous output is
and determining as the continuous output when it is determined that the location information is a specific type of road or when the value of the accelerator pedal sensor exceeds a criterion for a current battery state. 4. The method of claim 3,
The step of determining whether the continuous output is
The battery output control method is performed with reference to a first table including the reference values set according to the state of charge (SOC) and the temperature of the battery. The method of claim 1,
Further comprising the step of obtaining the second energy,
The obtaining step is
The battery output control method is performed by referring to a second table including the values of the second energy respectively set according to the state of charge (SOC) and the temperature of the battery. The method of claim 1,
The second energy is
The battery output control method, which corresponds to a second ratio of the maximum output that the battery can output for a second time. 7. The method of claim 6,
The first time and the second time are the same, the battery output control method. The method of claim 1,
Reducing the output of the battery by a first ratio comprises:
The first energy is greater than the second energy that is the output limiting energy standard,
The battery output control method is performed when the cell voltage of the battery is equal to or greater than a preset endurance reference cell voltage, and the voltage of the battery is less than the required output limiting voltage. 9. The method of claim 8,
The output limit required voltage is,
A method for controlling battery output, which is obtained by multiplying a coefficient having a larger value as the state of charge (SOC) and temperature of the battery is lower than 1 multiplied by a minimum voltage for guaranteeing durability of the battery. A computer-readable medium in which a program related to the charging mode control method of a hybrid vehicle according to any one of claims 1 to 9 is recorded. In an eco-friendly vehicle,
an electric motor generating a driving force;
a battery for supplying power to the electric motor; and
When it is determined whether the battery has continuous output or not, and when it is determined as continuous output as a result of the determination, a first energy that is the battery's accumulated energy used for a first time is calculated, and the first energy is higher than the second energy that is the output-limited energy standard. and a battery management system (BMS) that controls to reduce the output of the battery by a first ratio when it is large. 12. The method of claim 11,
The battery management system,
An eco-friendly vehicle that determines whether the continuous output is made through at least one of location information and an accelerator pedal sensor value. 13. The method of claim 12,
The battery management system,
When it is determined that the location information is a specific type of road or when the value of the accelerator pedal sensor exceeds a standard for a current battery state, the continuous output is determined as the continuous output. 14. The method of claim 13,
The battery management system,
An eco-friendly vehicle that refers to a first table including the reference values set according to the state of charge (SOC) and temperature of the battery, respectively. 12. The method of claim 11,
The battery management system,
and obtaining the second energy by referring to a second table including values of the second energy set according to a state of charge (SOC) and a temperature of the battery. 12. The method of claim 11,
The second energy is
The eco-friendly vehicle, which corresponds to a second ratio of the maximum output that the battery can output for a second time. 17. The method of claim 16,
The first time and the second time are the same, the eco-friendly vehicle. 12. The method of claim 11,
The battery management system,
When the first energy is greater than the second energy that is the output limiting energy reference, the cell voltage of the battery is equal to or higher than the preset endurance reference cell voltage, and the voltage of the battery is less than the required output limiting voltage, the output of the battery is reduced to the second energy. An eco-friendly vehicle that reduces by 1 percentage. 19. The method of claim 18,
The output limit required voltage is,
An eco-friendly vehicle, which is obtained by multiplying a coefficient having a larger value as the state of charge (SOC) and temperature of the battery is lower than 1 multiplied by a minimum voltage for guaranteeing durability of the battery.

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