KR20180057232A - Method for preventing over-charging of battery management system - Google Patents

Abstract

The present invention relates to a method for preventing overcharge of a battery management system. According to an embodiment of the present invention, the method for preventing overcharge of a battery management system, including a current source having one end separately connected to a plurality of battery cells and the other end connected to a ground through a switch, comprises: a turn-on step of turning on the current source through the switch; a measuring step of measuring voltage of battery cells connected to one end of the current source turned on in the turn-on step; a diagnosis step of comparing the voltage of the battery cells measured in the measuring step with a normal range voltage to diagnose a disconnection of a line connected to the battery cells; a turn-off step of turning off the current source through the switch; and an overcharge determining step of determining whether the battery cells are overcharged by comparing voltage of each of the battery cells with a reference voltage. In the diagnosis step, when the line connected to the battery cells is disconnected as a result of the diagnosis, whether the battery cells connected to the disconnected line are overcharged is not determined in the overcharge determining step.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery management system,

The present invention relates to an apparatus for preventing overcharging of a battery which can be used in an apparatus using electric energy. Specifically, the present invention relates to a technique for preventing overcharging of a high voltage battery used in a hybrid vehicle, a plug-in hybrid vehicle, and an electric vehicle.

In recent years, various devices such as industrial devices, home appliances and automobiles using high-voltage batteries have appeared, and especially in the field of automobile technology, the use of high-voltage batteries is becoming more active.

Automobiles that use internal combustion engines that use fossil fuels such as gasoline or heavy oil as the main fuel have a serious impact on pollution such as air pollution. Therefore, in recent years, efforts have been made to develop an electric vehicle or a hybrid vehicle in order to reduce pollution.

Electric vehicles (EVs) are cars that do not use petroleum fuels and engines but that use electric batteries and electric motors. In other words, although an electric vehicle that drives a car by rotating an electric motor that is stored in a battery has been developed before a gasoline car, it has not been put into practical use due to problems such as a heavy weight of a battery and a time required for charging. Recently, And research for commercialization began in the 1990s.

On the other hand, hybrid technology (HEV) that uses electric vehicles, fossil fuels and electric energy adaptively is being commercialized as battery technology has been developed remarkably.

Since HEV uses both gasoline and electricity as power sources, it is receiving positive reviews in terms of fuel efficiency improvement and emission reduction. It is expected that HEV will play an intermediate role in evolving into a full electric vehicle because it is important to overcome the price difference with gasoline automobile by reducing the amount of secondary battery to one third of that of electric cars.

Since HEV and EV vehicles using such electric energy use a battery in which a plurality of rechargeable secondary cells are packed as a main power source, there is no exhaust gas and noise is small. have.

Since the performance of a battery using the electric energy directly affects the performance of the vehicle, it is necessary to measure the voltage of each battery cell, the voltage and current of the entire battery, and to efficiently manage charge and discharge of each battery cell However, a battery management system (BMS) is required to monitor the state of a cell sensing IC that senses each battery cell, thereby enabling stable control of the corresponding cell.

On the other hand, when the battery cell deteriorates due to long-term use, it can be overcharged compared to a normal battery cell even when the same charging voltage is applied. Thus, the battery management system is essentially required to have an overcharge protection device that stops charging when the battery cell is overcharged. In general, when the voltage of the battery cell becomes equal to or higher than the overcharge reference value, the overcharge protection device determines that the battery cell is overcharged and turns off the switch connected between the battery cell and the load, thereby preventing overcharging of the battery cell.

At this time, when the line connecting the battery cell and the battery management system is disconnected, the voltage of the battery cell connected to the disconnected line may be measured as a full-scale voltage which is a voltage exceeding the overcharge reference value. In this case, the overcharge prevention device may cause a problem that the battery cell connected to the disconnected line is overcharged and is mistaken.

U.S. Patent Application Publication No. 2014-0070772

An object of the present invention is to prevent the occurrence of an overcharge judgment by preliminarily performing a disconnection diagnosis prior to overcharge determination of a battery cell.

The overcharge prevention method of a battery management system according to an embodiment of the present invention includes a current source having one end connected to each of a plurality of battery cells and the other end connected to a ground through a switch, Turning on the current source through a switch; A measuring step of measuring a voltage of a battery cell connected to one end of a current source turned on in the turn-on step; A diagnosis step of comparing a voltage of the battery cell measured in the measuring step with a normal range voltage to diagnose a disconnection of a line connected to the battery cell; Turning off the current source through a switch; And an overcharge determination step of determining whether the plurality of battery cells are overcharged by comparing a voltage of each of the plurality of battery cells with a reference voltage, and when a line connected to the battery cell is disconnected as a result of the diagnosis in the diagnosis step, And the overcharge determination step does not determine whether the battery cell connected to the disconnected line is overcharged.

In one embodiment, the diagnosing step diagnoses that a line connected to the battery cell is disconnected when the voltage of the battery cell measured in the measuring step deviates from the normal range voltage.

In one embodiment, when the line connected to the battery cell is disconnected as a result of the diagnosis in the diagnosis step, a storage step of storing the position of the disconnected line may be further included.

In one embodiment, the overcharge determination step determines that the plurality of battery cells are overcharged when the voltage of any one of the plurality of battery cells exceeds the reference voltage.

In one embodiment, the overcharge determination step determines that the plurality of battery cells are overcharged when the voltage of any one of the plurality of battery cells exceeds the reference voltage for a predetermined time or more.

In one embodiment, in the overcharge determination step, when it is determined that the plurality of battery cells are overcharged, a connection between the plurality of battery cells and a load provided in the vehicle is cut off to prevent overcharging of the plurality of battery cells Step < / RTI >

In one embodiment, the overcharge protection step may include interrupting a connection between the plurality of battery cells and the load until a start-off signal for turning off the vehicle is input.

In one embodiment, the method may further include a reset step of connecting the plurality of battery cells and the load when a start-off signal for turning off the vehicle is input.

In one embodiment, the method may further include a warning step of warning the user if the plurality of battery cells are determined to be overcharged in the overcharge determination step.

The present invention performs disconnection diagnosis of a line connected to a battery cell, and then determines whether the battery cell is overcharged.

Thus, it is not possible to determine whether the battery cell connected to the disconnected line is overcharged.

Therefore, the present invention has the effect of improving the accuracy of battery cell overcharge judgment.

1 is a block diagram of a battery management system.
FIG. 2 is a flowchart sequentially illustrating a process of diagnosing disconnection in the overcharge prevention method of the battery management system according to an embodiment of the present invention.
FIG. 3 is a flowchart sequentially illustrating a process of determining overcharge in the overcharge prevention method of the battery management system according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the embodiments, descriptions of techniques which are well known in the technical field to which the present invention belongs and which are not directly related to the present invention are not described. This is for the sake of clarity of the present invention without omitting the unnecessary explanation.

For the same reason, some of the components in the drawings are exaggerated, omitted, or schematically illustrated. Also, the size of each component does not entirely reflect the actual size. In the drawings, the same or corresponding components are denoted by the same reference numerals.

Hereinafter, a configuration of a battery management system to which an overcharge prevention method of a battery management system according to an embodiment of the present invention is applied will be described with reference to FIG.

1 is a block diagram of a battery management system.

1, the battery management system 200 includes a power supply 220, a diode 230, a current source 240, a capacitor 250, a measurement unit 270, a diagnosis unit 280, 290). Here, the battery management system 200 may further include a lowermost capacitor C0 and a lowest current source AC connected to the power source 260 having a preset voltage.

In this case, the number of battery cells is limited to five in FIG. However, the number of battery cells may be smaller or larger, and in some cases, it may be composed of a plurality of battery modules including a plurality of battery cells. Hereinafter, for convenience of explanation, the number of battery cells is assumed to be five as shown in Fig.

The controller 210 includes a power supply 220, a diode 230, a current source 240, a measurement unit 270, a diagnosis unit 280, and an overcharge prevention unit 290. The controller 210 monitors the charge / discharge state of each of the plurality of battery cells CV1, CV2, CV3, CV4, CV5. In addition, the controller 210 may perform cell balancing if necessary according to the monitored charge / discharge status.

The power supply unit 220 supplies power to the control circuit 210 and is connected to the line diverged from the uppermost battery cell of the battery module and the uppermost diode of the diode 230.

The diode 230 is connected to each of the branched lines in each of the plurality of battery cells CV1, CV2, CV3, CV4, and CV5.

The current source 240 may be composed of first to fifth current sources CS1 to CS5. The current source 240 has one end connected to each of the plurality of battery cells CV1, CV2, CV3, CV4, and CV5, and the other end connected to the ground through a switch.

The capacitor 250 includes the first to fifth capacitors C1 to C3 and is connected at one end to each of the plurality of battery cells CV1 to CV5, Lt; / RTI > The capacitors C1, C2, C3, C4, and C5 are charged by the voltages applied from the plurality of battery cells CV1, CV2, CV3, CV4, and CV5, respectively. When the current source 240 is turned on, the charged charge of the corresponding capacitor is discharged through the current source 240.

Meanwhile, the battery management system 200 may further include a lowermost capacitor C0 and a lowermost current source connected at one end to a power source 260 having a predetermined voltage. At this time, the lowermost capacitor C0 is connected to the negative terminal of the lowermost battery cell. Further, the lowest current source AC is connected at one end to a power source having a predetermined voltage (e.g., 5V), and the other end is connected through the lowest battery cell and the switch.

The measurement unit 270 controls the switch connected to the current source 240 to turn the current source 240 on or off. The measuring unit 270 turns on the current source 240 and measures the voltage of the battery cell connected to one end of the turned on current source.

The diagnosis unit 280 compares the voltage of the battery cell measured by the measuring unit 270 with a normal range voltage to diagnose a disconnection of a line connected to the battery cell.

Specifically, when the voltage of the battery cell measured by the measuring unit 270 deviates from the normal range voltage, the diagnosing unit 280 diagnoses that the line connected to the battery cell measured by the measuring unit 270 is disconnected. The normal range voltage may mean a voltage ranging from 0 V to 5 V when the rated voltage of the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 is 5V.

If a disconnection occurs on a specific line, the voltage of the battery cell connected to the line where the disconnection occurred is measured as 0 V or 5 V. Specifically, the voltage of the battery cell at the lower side of the line where the disconnection occurred is 0 V, and the voltage of the battery cell at the upper side of the line where the disconnection occurred is measured at 5V. At this time, since the upper battery cell of the line where the disconnection has occurred is measured at a voltage of 5 V by disconnection, but is larger than the overcharge reference voltage as will be described later, there is a possibility that the overcharging prevention unit 290 may be mistaken for overcharging have. Therefore, it is necessary to prevent the battery cell on the upper side of the line where the disconnection occurred from being judged to be overcharged.

The diagnosis unit 280 may store the position of the disconnected line when the line connected to the battery cell measured by the measurement unit 270 is diagnosed as disconnected. This is to prevent the overcharge prevention unit 290 from determining the overcharge of the battery cell connected to the disconnected line.

The overcharge prevention unit 290 compares the voltage of each of the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 with the reference voltage to determine whether the battery cells CV1, CV2, CV3, CV4, .

At this time, the overcharge prevention unit 290 determines whether there is a battery cell connected to the disconnected line among the plurality of battery cells CV1, CV2, CV3, CV4, and CV5. The overcharge preventing unit 290 does not determine whether the battery cell connected to the disconnected line is overcharged when there is a battery cell connected to the disconnected line. Hereinafter, determination of whether or not the overcharge of the battery cell connected to the line which is not disconnected in the overcharge prevention section 290 is determined will be described.

More specifically, when the voltage of any of the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 exceeds the reference voltage, the overcharge prevention unit 290 prevents the overcharge protection unit 290 from discharging the plurality of battery cells CV1, CV3, CV4, CV5) are overcharged.

For example, when the voltage of the first battery cell CV1 is 4.375 V and the reference voltage is 4.6 V, the overcharge prevention unit 290 may prevent the overcharge of the battery cells CV1, CV2, CV3, CV4, It is not judged that it is overcharged. However, when the voltage of the first battery cell CV1 is 4.65 V and the reference voltage is 4.6 V, the overcharge prevention unit 290 determines that the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 are overcharged .

When the voltage of any of the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 exceeds the reference voltage for a predetermined time or longer, the overcharge prevention unit 290 prevents the battery cells CV2, CV3, CV4, and CV5) are overcharged.

For example, if the battery voltage is measured at 25 ms intervals and the predetermined time is 250 ms, if the voltage of the first battery cell CV1 is measured to exceed the reference voltage for 10 consecutive times, a plurality of battery cells CV1 and CV2 , CV3, CV4, CV5) are overcharged.

When the overcharge prevention unit 290 determines that the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 are overcharged, the overcharge prevention unit 290 detects the overcharge of the battery cells CV1, CV2, CV3, CV4, Thereby preventing overcharging of the plurality of battery cells (CV1, CV2, CV3, CV4, CV5). This may mean that a switch connecting the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 and the load is turned off.

At this time, the overcharge prevention unit 290 can keep the connection between the plurality of battery cells (CV1, CV2, CV3, CV4, CV5) and the load until the start-off signal for turning off the vehicle is input have. This may mean that the switches connecting the plurality of battery cells (CV1, CV2, CV3, CV4, CV5) and the load are kept in the off state. Thus, the risk of overcharge of the plurality of battery cells (CV1, CV2, CV3, CV4, CV5) can be more effectively prevented.

On the other hand, when the start-off signal is inputted, the overcharge prevention unit 290 can reconnect the plurality of battery cells (CV1, CV2, CV3, CV4, CV5) and the load. This may mean turning on a switch connecting the plurality of battery cells (CV1, CV2, CV3, CV4, CV5) and the load.

Alternatively, the overcharge prevention unit 290 may warn the user when it is determined that the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 are overcharged. For example, a warning message may be displayed on the AVN provided in the vehicle or a warning sound may be sounded.

Hereinafter, an overcharge prevention method of the battery management system according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG. Here, the description of the parts overlapping with those described with reference to FIG. 1 will be omitted.

FIG. 2 is a flowchart sequentially illustrating a process of diagnosing disconnection in the overcharge prevention method of the battery management system according to an embodiment of the present invention.

Referring to FIG. 2, first, the measuring unit 270 turns on the current source 240 (S10). At this time, the measuring unit 270 sequentially turns on the first current source CS1 to the fifth current source CS5. That is, after the first current source CS1 is turned on, the second current source CS2 is turned on after the disconnection diagnosis, and the disconnection diagnosis is repeated until the fifth current source CS5 is turned on.

Then, the measuring unit 270 measures the voltage of the battery cell connected to the turned on current source (S20).

Thereafter, the diagnosis unit 280 compares the voltage of the battery cell measured in step S20 with the normal range voltage (S30).

If the voltage of the battery cell measured in the comparison result S20 in step S30 is out of the normal range voltage, the diagnosis unit 280 diagnoses that the line connected to the battery cell measured in step S20 is disconnected (S40).

Thereafter, the diagnosis unit 280 stores the position of the line diagnosed by the disconnection in step S40 (S50).

Thereafter, the measuring unit 270 turns off the turned-on current source (S60).

Then, the diagnosis unit 280 confirms whether or not the disconnection of all the lines is diagnosed (S70). If it is determined that the disconnection of all the lines is not detected, steps S10 through S60 are repeated. For example, in the case of diagnosing the disconnection of the line connected to the first battery cell CV1, it is possible to diagnose the disconnection of the line connected to the second battery cell CV2 and to disconnect the line connected to the fifth battery cell CV5, Repeat until diagnosis is made.

On the other hand, if it is determined in step S70 that the disconnection diagnosis of all the lines has been performed, the overcharge prevention unit 290 determines whether the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 are overcharged. A detailed description thereof will be given later with reference to Fig.

FIG. 3 is a flowchart sequentially illustrating a process of determining overcharge in the overcharge prevention method of the battery management system according to the embodiment of the present invention.

Referring to FIG. 3, first, the overcharge prevention unit 290 checks whether there is a broken line among the lines connected to the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 (S81). This can be confirmed through the position of the line diagnosed by the broken line stored in the diagnosis unit 280.

Thereafter, the overcharge prevention unit 290 identifies a battery cell connected to the disconnected line among the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 (S82). This is because it is not necessary to determine whether the battery cell connected to the disconnected line in the overcharge prevention unit 290 is overcharged.

Thereafter, the overcharge prevention unit 290 determines whether the voltage of the battery cell connected to the non-disconnected line identified in step S82 exceeds the reference voltage (S83). At this time, the overcharge prevention unit 29 can determine whether the voltage of the battery cell connected to the un-disconnected line, which is checked in step S82, exceeds the reference voltage for a predetermined time or more.

If it is determined in step S83 that the voltage of the battery cell connected to the unconnected line exceeds the reference voltage, the overcharge preventing unit 290 determines that the battery cell is overcharged (S84). At this time, the overcharge preventing unit 290 may determine that the battery cell is overcharged when the voltage of the battery cell connected to the identified unbroken line exceeds the reference voltage for a predetermined time or more as a result of the determination in step S83.

The overcharge prevention unit 290 blocks the connection between the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 and the load on the vehicle, (S85). At this time, the overcharge prevention unit 290 can keep the connection between the plurality of battery cells (CV1, CV2, CV3, CV4, CV5) and the load until the start-off signal for turning off the start of the vehicle is inputted have. On the other hand, when the start-off signal is input, the overcharge prevention unit 290 can reconnect the plurality of battery cells CV1, CV2, CV3, CV4, CV5 and the load.

The overcharge prevention unit 290 alerts the user that the plurality of battery cells CV1, CV2, CV3, CV4, and CV5 are overcharged (S86).

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present specification Should be interpreted.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is not intended to limit the scope. It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

200: Battery Management System (BMS)
210:
220:
230: Diode
240: current source
250: Capacitor
260: Power supply
270:
280:
290: Overcharge prevention part

Claims (9)

A method of preventing overcharging of a battery management system including a current source having one end connected to each of a plurality of battery cells and the other end connected to a ground via a switch,
Turning on the current source through a switch;
A measuring step of measuring a voltage of a battery cell connected to one end of a current source turned on in the turn-on step;
A diagnosis step of comparing a voltage of the battery cell measured in the measuring step with a normal range voltage to diagnose a disconnection of a line connected to the battery cell;
Turning off the current source through a switch; And
And an overcharge determination step of comparing the voltage of each of the plurality of battery cells with a reference voltage to determine whether the plurality of battery cells are overcharged,
Wherein when the line connected to the battery cell is disconnected as a result of the diagnosis in the diagnosis step, the overcharge determination step does not determine whether the battery cell connected to the disconnected line is overcharged. The method according to claim 1,
Wherein the diagnosing step diagnoses that the line connected to the battery cell is disconnected when the voltage of the battery cell measured in the measuring step deviates from the normal range voltage. The method according to claim 1,
And storing the position of the disconnected line when the line connected to the battery cell is disconnected as a result of the diagnosis in the diagnosing step. The method according to claim 1,
Wherein the overcharge determination step determines that the plurality of battery cells are overcharged when a voltage of any one of the plurality of battery cells exceeds the reference voltage. 5. The method of claim 4,
Wherein the overcharge determining step determines that the plurality of battery cells are overcharged when the voltage of any one of the plurality of battery cells exceeds the reference voltage for a predetermined time or longer. . 5. The method of claim 4,
Further comprising an overcharge protection step of preventing overcharging of the plurality of battery cells by interrupting a connection between the plurality of battery cells and a load provided in the vehicle when it is determined in the overcharge determination step that the plurality of battery cells are overcharged, A method of preventing overcharge of a management system. The method according to claim 6,
Wherein the overcharge protection step maintains the cutoff of connection between the plurality of battery cells and the load until a start-off signal for turning off the vehicle is input. The method according to claim 6,
Further comprising a reset step of connecting the plurality of battery cells and the load when a start-off signal for turning off the vehicle is input. 5. The method of claim 4,
Further comprising a warning step of warning the user if the plurality of battery cells are determined to be overcharged in the overcharge determination step.

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