KR20190013021A - Eco-friendly vehicle and method of controlling battery thereof - Google Patents

Abstract

The present invention relates to an eco-friendly automobile and to a battery control method therefor, and more specifically, to a battery control method for preventing an abrupt cell voltage drop of a battery, and to an eco-friendly automobile for performing the method. A method for controlling a battery output of the environmentally friendly automobile according to an embodiment of the present invention comprises the following steps: determining whether the battery for driving an electric motor is continuously output; calculating first energy, which is an accumulated battery use energy for a first time when the output is determined as a continuous output as a result of the determination; and reducing the output of the battery by a first rate when the first energy is greater than second energy which is an output limiting energy reference.

Description

TECHNICAL FIELD [0001] The present invention relates to an ECO-FRIENDLY VEHICLE AND METHOD OF CONTROLLING BATTERY THEREOF,

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

The demand for environmentally friendly vehicles is increasing due to the demand for constant fuel efficiency improvement for vehicles and the strengthening of exhaust gas regulations of each country. Hybrid vehicles (Hybrid Electric Vehicle / Plug-in Hybrid Electric Vehicle, HEV / PHEV) and electric vehicles (EVs).

An environmentally friendly vehicle usually uses an electric motor as a driving force, and is equipped with a battery that supplies electric power for driving an electric motor, and the battery generally includes a plurality of cells. In order to increase the mileage of the 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, if an excessive continuous output continues, a sudden drop in output due to a sudden drop in the cell voltage or damage to the durability may occur. This will be described with reference to FIG.

1 is a view for explaining a cell voltage characteristic of a general environmentally 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 consumed power of the battery sharply increases, and the speed of the vehicle also increases. As the speed reaches a certain level, the battery power is somewhat reduced, but a considerable amount of power is continuously consumed to maintain the speed. As a result, the battery voltage of the battery gradually decreases according to the continuous output of the battery from the viewpoint of the battery. In the vehicle, when the cell voltage is below a certain value, Perform control to prevent further drop of voltage.

However, when such control is performed, the battery output is suddenly lowered, so that a sudden deceleration sensation is felt. This causes a problem of not being able to efficiently use remaining energy of the battery as well as lowering of operability.

The present invention provides a method of controlling a battery more efficiently in an environmentally friendly vehicle equipped with an electric motor.

In particular, the present invention provides an environmentally friendly vehicle and a control method thereof that can perform control according to a cell voltage drop of a battery more efficiently in a continuous output situation.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to an aspect of the present invention, there is provided a method of controlling a battery output of an environmentally friendly vehicle, the method comprising: determining whether a battery for driving an electric motor is continuously output; Calculating a first energy, which is an accumulated battery use energy for a first time, if it is determined as a continuous output as a result of the determination; And reducing the output of the battery by a first rate if the first energy is greater than a second energy that is an output limiting energy criterion.

Further, an eco-friendly vehicle according to an embodiment of the present invention includes an electric motor for generating a driving force; A battery for supplying electric power to the electric motor; And determining whether or not the battery is continuously output. When the determination result indicates that the battery is continuously output, the first energy calculation unit calculates a first energy as a cumulative battery use energy for a first time period, The battery management system (BMS) that controls the output of the battery to decrease by a first rate.

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

In particular, according to the determination of continuous output, the cell voltage drop reference is stepwise controlled to alleviate the occurrence of sudden output decrease or occurrence of the yearbook, and the durability of the battery is protected, but the amount of available energy is increased.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

1 is a view for explaining a cell voltage characteristic of a general environmentally friendly vehicle battery.
2 is a flowchart showing an example of a battery control process according to an embodiment of the present invention.
FIG. 3 shows an example of an APS look-up table for determining whether continuous output is performed according to an embodiment of the present invention.
FIG. 4 shows an example of the output limiting energy reference table according to an embodiment of the present invention.
5 is a block diagram showing an example of a vehicle structure according to an embodiment of the present invention.
6 is a diagram for explaining the effect of the battery output control according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. In addition, parts denoted by the same reference numerals throughout the specification denote the same components.

In an embodiment of the present invention, when the battery is judged to be in a continuous output state in an environmentally friendly vehicle equipped with an electric motor, the accumulated energy usage amount of the battery for a predetermined period of time from the sensed time is calculated, It is proposed to reduce the output of the battery stepwise by a predetermined ratio every time it exceeds. This will be described with reference to FIG.

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

Referring to FIG. 2, it can be determined whether the battery is continuously output or not (S210) as the running using the electric motor (that is, the EV mode running) starts.

The continuous output state may be determined based on at least one of the position information base S210A and the acceleration pedal sensor APS value (S210B).

More specifically, the determination of the location information based on the location information may be performed in an AVN (Audio / Video / Navigation) system for acquiring location information from the GPS module or a location where the current location generally requires continuous output , A car-exclusive road, or the like).

Also, the determination of the APS value can be determined by determining whether the APS value causes a cell voltage drop when considering factors that affect the output of the battery. Here, the factors affecting the output of the battery include a temperature and a state of charge (SOC) of the battery. Also, in order to determine the APS value, a reference table showing a threshold for generating a cell voltage drop based on the SOC and the temperature of the battery of the vehicle may be used. This reference table configuration will be described with reference to FIG.

FIG. 3 shows an example of an APS look-up 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. The value of the column specified by the SOC and the temperature indicates the APS value. The configuration of this table indicates the output characteristics of the battery, and each cell may be a threshold value at which the cell voltage drop does not occur to such a degree that the SOC and the temperature become problematic. For example, when the SOC is 30 and the temperature is 5 degrees, if the APS value is 23% or less, even if the output corresponding to the APS value continuously occurs, the cell voltage drop is not a big problem. However, The cell voltage drop may occur. On the other hand, when the APS value is set to 0, a sudden cell voltage drop occurs when the battery requires continuous output. As a result, the lower the APS value, the more frequent the output limit, and vice versa. Of course, the configuration of the table shown in Fig. 3 can be different for each type of battery and for each battery.

Returning back to FIG. 2, if the continuous output state is determined, the accumulated energy usage amount (output) of the battery may be calculated from the determination time (S220). Such accumulated energy usage can be calculated by integrating the output of the battery during driving, and the output of the battery can be calculated as a product of the battery voltage and the current. The output of the battery may be performed in a battery management system (BMS), but is not limited thereto.

If the energy accumulated usage amount for the first predetermined time (a second, for example, 15 seconds) exceeds the output limit energy reference (S230), the output limitation of the battery may be performed (S270).

At this time, the output limiting energy criterion may be calculated as a first ratio of the output corresponding to the maximum energy that the present battery can output for a second predetermined time. Here, the second predetermined time may be set to a time at which the maximum output can be maintained, and the maximum output may be an intrinsic characteristic of the battery determined according to the SOC and the temperature. Also, the first ratio may be set to a ratio corresponding to the energy consumption at which the cell voltage drop suddenly occurs. For example, if the second predetermined time is 15 seconds for any battery and the first rate is 70%, the battery can maintain its maximum output for 15 seconds, and if more than 70% of the maximum power is used for 15 seconds, It can be seen that the voltage drop is rapidly generated. As a result, if the energy usage for 15 seconds is less than 70% of the maximum power, it is considered that the same output can be generated within the next 15 seconds, and it can be judged that the limitation due to the continuous output is unnecessary. The first predetermined time and the second predetermined time are preferably the same, but they are not necessarily the same.

This output limiting energy reference may take the form of a look-up table, an example of which will be described with reference to FIG.

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

In the table of FIG. 4, the SOC of the battery and the battery temperature of the battery indicate the SOC and the temperature of the battery, respectively. The values of the SOC and the temperature indicate the consumption energy (unit: KWs) when 70% . For example, if the SOC is 30 and the temperature is 5 degrees, the cell voltage can be considered not to drop sharply even if energy corresponding to 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 back to FIG. 2, the adjusted output in response to the output limit of the battery may be a second rate reduced output (e.g., 90% of the current output) at the current output. After the output is adjusted, determination of whether or not continuous output is performed (S210A, S210B) can be performed.

However, the battery cell voltage condition and the battery voltage can be further considered before the actual output limit is implemented.

Specifically, when the battery cell voltage becomes less than the cell voltage (hereinafter referred to as "durability reference cell voltage ", for example, 2V) that needs to be protected on the endurance side (S240) The battery output may be rapidly limited in order to prevent a drop (S250).

In the case where the battery cell voltage is equal to or greater than the durability reference cell voltage, if the battery voltage is smaller than a voltage requiring an output limitation (hereinafter referred to as "output limitation required voltage" for convenience) (S270). When the battery voltage is higher than the output limitation required voltage, the output limitation is not required, and the process returns to the use energy calculation step (S220).

Here, the output limit required voltage may be a value obtained by multiplying the lowest voltage guaranteed on the durability side by the coefficient K. The lowest voltage guaranteed on the durability side may be the inherent characteristics of the battery. Also, the coefficient K may be greater than 1, and the lower the SOC of the battery and the lower the temperature of the battery, the larger the coefficient K may be.

In the above process, each determination process, calculation of necessary values thereof, and storage / reference of reference data can be performed in the BMS, but the present invention is not limited thereto. For example, a separate controller for controlling the output of the battery may be provided in the vehicle, or a determination may be made for the output control function from a controller other than the BMS, and then a battery output control command may be transmitted to the BMS .

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

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

5, the vehicle according to the present embodiment may include a battery 510, a BMS 520, an inverter 530, and an electric motor 540. [ 5 are not limited to the names, and in actual vehicle implementation, functions corresponding to one component may be implemented by being distributed to a plurality of devices, or functions corresponding to two or more components may be implemented by one Device.

Hereinafter, each component will be described.

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

The inverter 530 converts the direct current output of the battery 510 to an alternating current output and supplies the direct current output to the electric motor 540 and the electric motor 540 as a controller.

Although not shown in FIG. 5, an upper controller such as a Vehicle Control Unit (VCU) or a Hybrid Control Unit (HCU), which controls the BMS 520 and the inverter 530 according to the vehicle type, May be additionally provided.

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

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

First, the basic assumption (rapid acceleration) in FIG. 6A is similar to FIG. Referring to FIG. 6A, in the general control, as described above with reference to FIG. 1, when the cell voltage becomes lower than a predetermined value due to continuous output, the battery output is sharply limited for battery protection. However, according to the control according to the present embodiment, the power consumption is calculated before the cell voltage is rapidly dropped, and control for reducing the output in advance is performed, so that abrupt output reduction and thus lowering of operability can be prevented.

Also, as shown in FIG. 6 (b), the battery output control method according to the present embodiment is advantageous in that the battery power that can be actually used is increased more than the normal control in the continuous output state have.

The present invention described above can be embodied as computer-readable codes on a medium on which a program is recorded. The computer readable medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of the computer readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, .

Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all conversions within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims (19)

A method of controlling a battery output of an environmentally friendly vehicle,
Determining whether the battery for driving the electric motor is continuously output;
Calculating a first energy, which is an accumulated battery use energy for a first time, if it is determined as a continuous output as a result of the determination; And
And reducing the output of the battery by a first rate if the first energy is greater than a second energy that is an output limiting energy criterion. The method according to claim 1,
The method of claim 1,
Location information, and accelerator pedal sensor value. 3. The method of claim 2,
The method of claim 1,
When the position information is determined to be a certain type of road, or when the accelerator pedal sensor value exceeds a criterion for a current battery condition. The method of claim 3,
The method of claim 1,
(SOC) of the battery and the temperature of the battery, and the first table includes a value of the reference set in accordance with the state of charge (SOC) and temperature of the battery. The method according to claim 1,
Further comprising the step of acquiring the second energy,
Wherein the acquiring comprises:
(SOC) of the battery, and a second table containing the value of the second energy respectively set in accordance with the temperature of the battery. The method according to claim 1,
Wherein the second energy is a <
Wherein the battery corresponds to a second rate of maximum output that can be output for a second time. The method according to claim 6,
Wherein the first time and the second time are the same. The method according to claim 1,
Wherein the step of reducing the output of the battery by a first rate comprises:
Wherein the first energy is greater than a second energy that is an output limiting energy criterion,
Wherein when the cell voltage of the battery is equal to or greater than a predetermined durable reference cell voltage and the voltage of the battery is less than the output limit required voltage. 9. The method of claim 8,
The output-limiting-
(SOC) of the battery and a coefficient in inverse proportion to the temperature multiplied by a lowest voltage for ensuring durability of the battery. A computer-readable recording medium on which a program for executing a charging mode control method of a hybrid vehicle according to any one of claims 1 to 9 is recorded. In an environmentally friendly vehicle,
An electric motor for generating a driving force;
A battery for supplying electric power to the electric motor; And
Wherein the control unit determines whether the battery is continuously output, calculates a first energy that is a cumulative battery use energy for a first time when it is determined that the battery is continuously output, And a Battery Management System (BMS) that controls the output of the battery to be reduced by a first rate when the battery is large. 12. The method of claim 11,
The battery management system includes:
Position information and an accelerator pedal sensor value to determine whether or not to continuously output the eco-friendly vehicle. 13. The method of claim 12,
The battery management system includes:
Judges the continuous output when the position information is determined to be a certain type of road or when the acceleration pedal sensor value exceeds a criterion for a current battery condition. 14. The method of claim 13,
The battery management system includes:
(SOC) of the battery and a temperature of the reference set in accordance with the temperature, respectively. 12. The method of claim 11,
The battery management system includes:
And acquires the second energy with reference to a second table including a value of the second energy set in accordance with a state of charge (SOC) and temperature of the battery. 12. The method of claim 11,
Wherein the second energy is a <
Wherein the battery corresponds to a second rate of maximum output that can be output for a second time. 17. The method of claim 16,
Wherein the first time and the second time are the same. 12. The method of claim 11,
The battery management system includes:
Wherein when the cell voltage of the battery is greater than or equal to a predetermined durable reference cell voltage and the voltage of the battery is less than the output limit required voltage, 1 ratio. 19. The method of claim 18,
The output-limiting-
(SOC) of the battery and a coefficient in inverse proportion to the temperature multiplied by a minimum voltage for ensuring durability of the battery.

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