KR101673249B1 - Apparatus and method for detecting disconnection of wire in battery management system - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a breakdown diagnostic apparatus for a battery management system, including a battery module including a plurality of battery cells connected in series; A controller connected to the battery module to monitor and control a charge / discharge state of battery cells of the battery module; A wire connecting a positive electrode or a negative electrode of each battery cell of the battery module to the control unit and including a first resistor Ra; A capacitor connected in parallel to each of the battery cells to perform a function of a filter together with the first resistor (Ra); A discharging circuit unit connected in parallel to each of the battery cells and including a discharging switch and a discharging resistor that are switched and controlled to discharge each battery cell through the controller; And a disconnection detecting unit for detecting disconnection of the wire connected between the control unit and the positive or negative terminal of the specific battery cell through the switching control of the discharging switch.

Description

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery management system that can be used in an apparatus using electric energy, and more particularly, to an apparatus and method for detecting wire disconnection of battery cells.

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 vehicles that do not use petroleum fuels and engines but that use electric batteries and electric motors. That is, an electric vehicle that drives an automobile by rotating an electric motor that is accumulated in a battery is developed prior to a gasoline automobile, but is not commercialized because of problems such as a heavy weight of the battery, a limitation of the capacity of the battery, And environmental problems became serious, 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 gasoline and electricity together as a power source, it is evaluated positively in terms of fuel efficiency improvement and exhaust gas reduction, and it is expected to play an intermediate role in evolving into a fully electric vehicle.

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.

1 is a circuit diagram schematically showing a battery management system according to the related art.

Referring to FIG. 1, a vehicle battery management system includes a battery pack 10 and a battery control circuit 30 in which a plurality of battery cells are connected in series.

The battery pack 10 includes a plurality of battery cells C1, C2 and C3 connected in series and supplies the high voltage DC electric power charged in the battery cells C1, C2 and C3 to a vehicle electronic device such as a motor.

The battery control circuit 30 is connected to the battery pack 10 to monitor the charging and discharging state of the battery pack 10 and controls the charging and discharging operations of the battery pack 10. [ That is, the battery cells C1, C2, and C3 of the battery pack 10 are connected to the control circuit 30 to monitor the charging / discharging state of each cell in the control circuit 30 and perform the charging / discharging operation of the cell .

At this time, when a wire connecting the cells is disconnected to cause an open or an internal resistance to become high, a charge current flowing into the battery pack 10 flows into the control circuit 30 and the control circuit 30 is burned out A protection resistor R is provided between each cell and the control circuit 30 as shown. An RC circuit serving as a filter for removing noise from a signal input from the battery cells C1, C2, and C3 to the control circuit 30 is configured between the battery pack 10 and the control circuit 30. [

Between the battery pack 10 and the control circuit 30, a balancing resistor r and a switch SW are provided for each cell to maintain the balancing of the charging voltage between the cells, Discharge for cell balancing is possible.

However, according to the related art, as shown in the drawing, the coverage A1 that can confirm the disconnection of the wire formed between each cell and the control circuit 30 is very small, so that there is still a limit to detecting the abnormality of the system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device and method for detecting a breakage of a wire connected between a battery cell and a controller in a battery management system more efficiently.

According to an embodiment of the present invention, a breakdown diagnosis apparatus for a battery management system includes: a battery module including a plurality of battery cells connected in series; A controller connected to the battery module to monitor and control a charge / discharge state of battery cells of the battery module; A wire connected to an anode or a cathode of each battery cell of the battery module, the wire including a first resistor Ra; A capacitor connected in parallel to each of the battery cells to perform a function of a filter together with the first resistor (Ra); A discharging circuit unit connected in parallel to each of the battery cells and including a discharging switch and a discharging resistor that are switched and controlled to discharge each battery cell through the controller; A protection resistor Rc connected to an input terminal of the control unit to protect the control unit from a high voltage signal flowing from the battery cell; And a disconnection detection unit for detecting whether the wire connected between the control unit and the positive or negative terminal of the specific battery cell is disconnected through the switching control of the discharging switch and the protection resistor Rc is connected to the first resistor Ra ) Of the resistance value.
One end of the first resistor Ra is connected to the positive electrode or the negative electrode of the battery cell and the other end of the first resistor Ra is connected to one end of the capacitor, And the disconnection detecting unit detects whether the battery cell is disconnected from the positive or negative terminal of the battery cell to one end of the protection resistor Rc.
Also, the protection resistor Rc is connected between the other end of the first resistor Ra and the input terminal of the control unit.
The size of the first resistor (Ra) is 100Ω or less, the size of the protection resistor (Rc) is 1KΩ or more, and the capacitor is 100nF or more.
Also, the battery module may include a first battery cell, a second battery cell, and a third battery cell that are connected in series, and the disconnection detecting unit may be connected to the positive terminal of the second battery cell, Wherein a voltage to be measured is V, an over-discharge threshold voltage of the second battery cell is V _TH1 , and an overcharge threshold voltage of the second battery cell is V _TH2 , discharging of the first to third battery cells (+) Of the second battery cell is disconnected when the voltage V measured when the discharge switch of the second battery cell is opened after the discharge switch of the second battery cell is opened is smaller than the V _TH1 , Is determined to have occurred.
It is preferable that the disconnection detecting unit is configured such that the voltage V measured when the discharging switches of the first to third battery cells are all opened and then the discharging switch of the second battery cell is closed and then opened again is smaller than the V _TH1 When the voltage V measured in a state where the discharging switch of the second battery cell is opened and the discharging switch of the first battery cell and the discharging switch of the third battery cell are closed after the discharging switch of the second battery cell is opened is greater than V _TH2 , It is determined that a disconnection has occurred in the wire connected at the anode (+) of the cell.
The control unit, the discharge switch, and the disconnection detecting unit may include an integrated circuit (IC), and the integrated circuit and the battery module may be connected through a plurality of wires.
In addition, the integrated circuit connected to the battery module through the wire may further include the protection resistor Rc in each input terminal connected to the battery cell.

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According to an embodiment of the present invention, there is provided an apparatus and method for diagnosing a broken wire which can detect a broken wire of a wire connected between a battery cell and a controller.

Further, according to the embodiment of the present invention, it is possible to detect a wider range of wire disconnection.

1 is a block diagram of a conventional battery management system.
2 is a circuit diagram of a single line diagnostic apparatus of a battery management system according to an embodiment of the present invention.
3 is a circuit diagram of a single line diagnostic apparatus of a battery management system according to another embodiment of the present invention.
FIG. 4 is a reference diagram for explaining a single wire diagnostic method of the battery management system 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.

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

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, an apparatus and method for diagnosing a broken line in a battery management system according to an embodiment of the present invention will be described with reference to FIGS. 2 to 4. FIG.

2 and 3 are circuit diagrams of a single line diagnostic apparatus of the battery management system according to an embodiment of the present invention.

The battery management system shown in FIG. 2 includes a battery module 10 including a plurality of battery cells VC1, VC2, VC3, and VC4 connected in series and a plurality of battery cells VC1, VC2, VC3, And a controller 30 for monitoring the charging / discharging state of the battery cells VC4 and performing cell balancing if necessary. Although the number of battery cells is limited to four in the present embodiment, the number of battery cells may be smaller or larger than the number of battery cells. In some cases, the battery cells may be composed of a plurality of battery modules including a plurality of battery cells. have.

The positive (+) and negative (-) terminals of each of the battery cells VC1, VC2, VC3 and VC4 are connected to the control unit 30 through wires L1, L2, L3, L4 and L5.

A resistor Ra is connected to the front end of each wire and capacitors C1, C2, C3 and C4 are connected in parallel with the battery cells VC1, VC2, VC3 and VC4 through the other end of the resistor Ra. The resistor Ra and the capacitors C1, C2, C3, and C4 constitute an "RC filter" to eliminate noise of power supplied from each cell.

Generally, the illustrated resistance Ra plays a role of protecting the control unit 30 from a high voltage introduced from each cell. However, in the present embodiment, the resistance Ra may be used only as a resistance of the "RC filter ", and a protection resistor serving as a protection resistor may be formed in front of the controller 30 instead. That is, the magnitude of the resistance Ra is configured to be several hundreds of ohms to several tens of ohms, which is an extremely small value compared to the conventional one, without using a high-resistance resistor of several K? In this case, the value of capacitor C is replaced with a larger capacitance so that the characteristics of the "RC filter" That is, by replacing the resistor Ra with a resistor having a value about 1/10 of that of the conventional capacitor, and changing the capacitors C1, C2, C3, and C4 to capacitors having a value about 10 times that of the conventional capacitor, The characteristics of the circuit are not changed. Instead, a separate protection resistor, which can serve as a protection resistor, may be additionally provided at the input of the controller 30. [

FIG. 3 is a circuit diagram of an embodiment of a battery management system according to another embodiment of the present invention. In FIG. 3, a resistance Rc, which serves as a protection resistor instead of the resistance Ra, Fig.

In the circuit diagram of Fig. 1, assuming that the value of the resistor R is 1 K? And the value of the capacitor C is 10 nF, the value of the resistor Ra is set to 100? In the circuit diagram of Fig. 3, and the value of the capacitors C1, C2, And the value of the resistor Rc can be set to 1K ?.

As described above, by changing the characteristic of the resistance Ra to a device having a small resistance value, it is possible to replace the conventional balancing resistance r by the rear end portion of the resistance Ra rather than the front end.

Comparing FIG. 1 and FIG. 2 (or FIG. 3), in FIG. 1, since the magnitude of the protective resistance R has a very large value of about several KΩ, the discharge resistance r has to be connected in parallel to the front end of the protective resistance R. Therefore, the coverage A1 capable of detecting disconnection of the wire has an extremely narrow limit from the anode or the cathode terminal of the cell to the front end of the protection resistance R. However, in FIG. 2 or FIG. 3, since the resistance Ra has a very small value of several hundreds to several tens of ohms, the influence due to the resistance is extremely small, so that the coverage A2, which can detect disconnection of the wire, To the rear end of the resistance Ra.

As shown in the figure, each of the battery cells VC1, VC2, VC3, and VC4 includes discharge switches SW1, SW2, SW3, and SW4 and discharge resistances Rb that are controlled to be discharged to discharge the respective battery cells through the control unit 30 Are connected in parallel. The discharge circuit part is connected in parallel to the wires L1, L2, L3, L4 and L5 at the rear end of the resistor Ra in particular.

The controller 30 periodically monitors the charging voltage of each cell, and when the voltage deviation between the cells is large, the discharging switch of a specific cell is on / off controlled to maintain cell balancing.

According to another embodiment of the present invention, the control unit 30 and the discharge switches can be designed as one integrated circuit (IC) A protection resistor Rc for protecting the control circuit 100 from damage due to a high voltage signal flowing from the battery cell may be included in an input terminal of the integrated circuit 100 connected to each wire.

FIG. 4 is a reference diagram for explaining a single wire diagnostic method of the battery management system according to an embodiment of the present invention.

For example, in the circuit diagrams of FIGS. 2 and 3, it is assumed that a disconnection X occurs in a wire L2 connected to the positive terminal of the second battery cell.

At this time, the control unit 30 can detect whether the L2 is disconnected by controlling the switches SW1, SW2 and SW3 of the cells 1 to 3 as shown in FIG. 4 to measure the voltage at the point B.

First, the voltage of the second battery cell is denoted by VC2, the voltage measured at the input terminal B of the control unit 30 connected to the positive electrode (+) of the second battery cell is denoted by V2, and the overdischarge threshold voltage of the second battery cell is denoted by V _TH1 and the overcharge threshold voltage of the second battery cell is V _TH2 . At this time, it is assumed that the voltage change due to Ra is almost insignificant, and since the resistance of Ra is set to a very small value, the voltage V2 at the point B is not greatly affected.

First, all of the discharge switches SW1, SW2, and SW3 of the neighboring cells including the cell where the disconnection has occurred are opened. In this case, the voltage V2 at the point B may be formed to be equal to or slightly lower than the voltage VC2 of the second battery cell due to the charge accumulated in the capacitor C2 at the beginning.

Thereafter, the switches SW1 and SW3 of the first battery cell and the third battery cell close the switch SW2 of the second battery cell while maintaining the open state. In this case, since disconnection has occurred in L2, the charge accumulated in the capacitor C2 is rapidly discharged, so that the voltage V2 at the point B drops sharply and converges to almost zero as shown in the figure. If the disconnection X does not occur in L2, since the voltage is supplied from the second battery cell VC2, the voltage V2 at the point B will hardly fluctuate.

Thereafter, the discharging switch SW2 of the second battery cell is changed to the open state again, and the voltage V2 at the point B is measured. In this case, since the peripheral charges may flow into the capacitor C2 provided between L2 and L3 and accumulate, the voltage may rise. However, since L2 is in a disconnection state, it has a very low value compared with the voltage in the steady state. Therefore, the voltage value measured at the point B in the disconnection state in comparison with the over-discharge threshold voltage V _TH1 in the steady state of the second battery cell has a low value as shown in the figure. It is possible to determine whether or not the specific wire L2 is disconnected by measuring the V2 value in such a state (SW1, SW2, SW3 re-opened state) and comparing it with the over-discharge threshold voltage V _TH1 .

Thereafter, for more accurate disconnection detection, the discharge switch SW2 of the second battery cell is changed to the open state, and then the SW1 and the SW3 of the first and third battery cells are changed to the closed state. At this time, the capacitor C1 of the first battery cell and the capacitor C3 of the third battery cell are connected in series to the capacitor C2, so that the voltage values of VC1 and VC3 are added. Therefore, at the point B, a sudden voltage rise occurs, and when the voltage V2 at the point B is measured, the voltage becomes very high as compared with the voltage in the steady state. Therefore, the voltage value measured at the point B in the disconnection state in comparison with the overcharge threshold voltage V _TH2 in the steady state of the second battery cell has a high value as shown in the figure. It is possible to judge whether or not the specific wire L2 is disconnected by measuring the V2 value in such a state (SW2 opening, SW1 and SW3 being closed and re-opening), and comparing it with the overcharge threshold voltage.

According to another embodiment of the present invention, the reference voltage value for determining whether the wire is disconnected may be set to a value slightly lower than the over-discharge threshold voltage V _{TH1 of the} battery cell, or the overcharge threshold voltage of the battery cell may be set to be slightly higher than V _TH2 It can be set to a high value.

It will be understood by those skilled in the art that the present specification 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 specification is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents 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 embodiments, but, on the contrary, It is not intended to limit the scope of the specification. It will be apparent to 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.

10: Battery pack, battery module VC1, VC2, VC3, VC4: Battery cell
30: control circuit, control unit
R, Ra: resistance r, Rb: discharge resistance
Rc: Protection resistor C: Capacitor
A1, A2: Disconnection detection coverage
SW, SW1, SW2, SW3, SW4: switch 100: integrated circuit (IC)
V _TH1 : over-discharge threshold voltage V _TH2 : overcharge threshold voltage

Claims (8)

A breakage diagnosis apparatus for a battery management system,
A battery module including a plurality of battery cells connected in series;
A controller connected to the battery module to monitor and control a charge / discharge state of battery cells of the battery module;
A wire connected to an anode or a cathode of each battery cell of the battery module, the wire including a first resistor Ra;
A capacitor connected in parallel to each of the battery cells to perform a function of a filter together with the first resistor (Ra);
A discharging circuit unit connected in parallel to each of the battery cells and including a discharging switch and a discharging resistor that are switched and controlled to discharge each battery cell through the controller;
A protection resistor Rc connected to an input terminal of the control unit to protect the control unit from a high voltage signal flowing from the battery cell; And
And a disconnection detecting unit for detecting disconnection of the wire connected between the control unit and the positive or negative terminal of the specific battery cell through the switching control of the discharging switch,
Wherein the protection resistor Rc has a resistance value greater than the first resistance Ra.
The method according to claim 1,
One end of the first resistor Ra is connected to an anode or a cathode of the battery cell and the other end of the first resistor Ra is connected to one end of the capacitor, the discharge circuit and the protection resistor Rc,
Wherein the disconnection detecting unit detects whether the disconnection from the positive or negative terminal of the battery cell to one end of the protection resistor (Rc) is disconnected.
3. The method of claim 2,
Wherein the protection resistor Rc is connected between the other end of the first resistor Ra and the input terminal of the control unit.
The method according to claim 1,
The size of the first resistor (Ra) is 100 Ω or less, the size of the protection resistor (Rc) is 1KΩ or more,
Wherein the capacitor is at least 100 nF.
The method according to claim 1,
Wherein the battery module includes a first battery cell, a second battery cell, and a third battery cell connected in series,
The disconnection detecting unit may be configured such that a voltage measured at an input terminal of the control unit connected to the positive (+) of the second battery cell is V, an over-discharge threshold voltage of the second battery cell is V _TH1 , When the overcharge threshold voltage of the cell is V _TH2 ,
If the voltage V measured when the discharging switches of the first to third battery cells are all opened and the discharging switch of the second battery cell is closed and then opened again is smaller than V _TH1 , And determines that a disconnection has occurred in the wire connected to the positive electrode (+).
The apparatus according to claim 5,
The voltage V measured when the discharging switches of the first to third battery cells are all opened and then the discharging switch of the second battery cell is closed and then opened again is smaller than the V _TH1 ,
If the voltage V measured in a state where the discharging switch of the second battery cell is opened and the discharging switch of the first battery cell and the discharging switch of the third battery cell are closed after the discharging switch of the second battery cell is opened is greater than V _TH2 , Wherein the controller determines that a disconnection has occurred in the wire connected to the positive electrode of the battery management system.
The method according to claim 1,
Wherein the control unit, the discharge switch, and the disconnection detecting unit are constituted by an integrated circuit (IC), and the integrated circuit and the battery module are connected through a plurality of wires.
8. The method of claim 7,
Wherein the integrated circuit connected to the battery module via the wire further includes the protective resistor Rc in each input terminal connected to the battery cell.

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