KR20160063896A - Apparatus and method for detecting wire disconnection using pull-down circuit in battery management system - Google Patents

Abstract

The present invention relates to an apparatus for diagnosing a disconnection in a battery management system comprising: a battery module which includes a plurality of battery cells connected in series; a control unit which is connected with the battery module and monitors and controls charging / discharging states of battery cells of the battery module; a wire which couples an anode and a cathode of each of the battery cells of the battery module with the control unit individually; a capacitor which is coupled with each of the battery cells in parallel; a pull-down element which is connected with the wire through a switch; and a disconnection detecting unit which controls on / off states of the switch to sense a voltage of the battery cell, and compares a first voltage of the battery cell, when the switch is at an off state, with a second voltage of the battery cell, when the switch is at an on state, to detect whether the wire is disconnected. According to the present invention, it is possible to detect a disconnection of a wire connected between the battery cell and the controller efficiently by using the pull-down circuit.

Description

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

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 for maintaining the balancing of the charging voltage between cells are formed for each cell, It is possible to discharge for cell balancing separately.

On the other hand, as shown in FIG. 1, when a line is formed in a wire formed between each cell and the control circuit 30, the balancing on voltage and the balancing off voltage of the corresponding cell are usually measured, To diagnose whether the circuit is open or closed.

However, in recent years, the characteristics of the battery cell have been gradually improved, so that cell balancing is not required, or the case where the cell balancing is not required is gradually increasing. However, there is a problem that cell balancing must be performed in order to determine whether a circuit is disconnected. Further, there is a problem that it is impossible to diagnose disconnection of a wire in a platform that does not use a balancing circuit such as a fuel cell measurement control circuit.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a single wire diagnostic apparatus and method capable of more efficiently detecting disconnection of a wire connected between a battery cell and a controller using a pull-down circuit in a battery management system.

In addition, the present specification discloses a break line diagnostic device that can more effectively detect disconnection of a wire connected between a battery cell and a controller even when a balancing circuit does not exist or a balancing operation is not performed by detecting a disconnection of a wire by using a pull- And a method thereof.

According to an embodiment of the present invention, a breakdown diagnosis apparatus of 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 connecting the anode or the cathode of each battery cell of the battery module to the control unit; A capacitor connected in parallel to each of the battery cells; A pull-down device connected to the wire through a switch; And sensing a voltage of the battery cell by on / off controlling the switch, comparing a first voltage of the battery cell in an off state of the switch with a second voltage of the battery cell in an on state of the switch, And a disconnection detecting unit for detecting disconnection of the antenna.

Further, the pull-down device is characterized by being a current source for supplying a predetermined current.

The current supplied from the current source is not less than 100 mA and not more than 200 mA.

The disconnection detecting unit detects a difference between the first voltage and the second voltage, and determines that the disconnection of the wire occurs when the difference is greater than a predetermined threshold value.

In addition, the threshold value is set to be 500 mV or less.

Also, the disconnection detecting unit sequentially senses the battery cells of the battery module in the off state of the switch to store the first voltage of the battery cells, turn on the switch to operate the pull-down device, The method comprising the steps of sequentially sensing the battery cells of the battery module to store the second voltage of the battery cells, sequentially comparing the stored first voltage and the second voltage based on the position of the battery cell, And sequentially detects whether or not the signal is detected.

The control unit, the 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.

According to another aspect of the present invention, there is provided an apparatus for monitoring and controlling a charge / discharge state of battery cells, each of which is connected to a plurality of battery cells connected in series by wires, the pull- down element; A switch element connecting the wire and the pull-down element; And sensing a voltage of the battery cell by on / off control of the switch element, comparing a first voltage of the battery cell in an off state of the switch with a second voltage of the battery cell in an on state of the switch, And a disconnection detecting section for detecting whether or not the wire is disconnected.

Further, the pull-down device is characterized by being a current source for supplying a predetermined current.

The disconnection detecting unit sequentially senses the battery cells in an off state of the switch device to store the first voltage of the battery cells and sequentially senses the battery cells in an on state of the switch device, Storing the second voltage of the cells, sequentially comparing the stored first voltage and the second voltage based on the position of the battery cell, and sequentially detecting whether the wire is disconnected.

According to an embodiment of the present invention, a method of disconnecting a battery management system includes a step of connecting a plurality of battery cells connected in series to each other by a wire, and detecting whether the wire is disconnected using a pull- A method of detecting a disconnection, comprising: sequentially sensing a voltage of the battery cells in a state where the pull-down device is not conducted to the diagnostic circuit; Storing a voltage of the sensed battery cells as a first voltage; Conducting the pull-down device to the diagnostic circuit and sequentially sensing a voltage of the battery cells; Storing the voltage of the sensed battery cells as a second voltage; Comparing the first voltage and the second voltage to derive a sensed voltage difference of each of the battery cells; And comparing the derived voltage difference with a predetermined threshold value to determine that wire breakage has occurred in the battery cells exceeding the threshold value.

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 using a pull-down circuit more efficiently.

Further, by detecting the disconnection of the wire using the pull-down circuit, there is an effect that the disconnection of the wire connected between the battery cell and the controller can be detected more efficiently even if the balancing circuit does not exist or the balancing operation is not performed.

1 is a circuit 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 partial enlarged view of a single line diagnostic apparatus of a battery management system according to an embodiment of the present invention.
FIG. 4 is a flowchart sequentially illustrating a method for diagnosing a single line in a 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 disconnection of a battery management system according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG.

FIG. 2 is a circuit diagram of a single line diagnostic apparatus of a battery management system according to an embodiment of the present invention, and FIG. 3 is a diagram illustrating a pull-down circuit of a single line diagnostic apparatus of a battery management system according to an embodiment of the present invention Fig.

The breakdown diagnosis apparatus of the battery management system shown in FIG. 2 includes a battery module including a plurality of battery cells VC1, VC2, VC3 and VC4 connected in series and a battery module including battery cells VC1, VC2, VC3 and VC4 And a control unit 40 for monitoring and controlling the charge / discharge state.

The positive electrode (+) or the negative electrode (-) of each battery cell (VC1, VC2, VC3, VC4) of the battery module and the control unit 40 are connected by wires L1, L2, L3, L4 and L5 .

A resistor R serving as a protection resistor is connected to the front end of each wire and the 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 R. The resistor R and the capacitors C1, C2, C3 and C4 constitute an " RC filter " to eliminate the noise of power supplied from each battery cell VC1, VC2, VC3 and VC4.

Each wire is provided with a pull-down circuit at the rear end of the "RC circuit ".

The normal control unit 40 measures the voltage of each cell, and when the voltage of about 3V to 5V is measured, the normal control unit 40 determines that the voltage is logic high. When the voltage of substantially 0V is measured, the control unit 40 determines that the voltage is logic low. However, in the actual circuit, the cell voltage is not sensed as OV due to the influence of peripheral devices and capacitors, and a voltage including a noise value is measured. In such a state, it is impossible to grasp the logical high or low state since the correct input value is not known. Such a state is generally referred to as a floating state, and when a floating state occurs, the system is unstable and it is impossible to measure an accurate circuit state. To solve the floating state, a pull-up or pull-down device can be used. In this case, the pull-down device P is applied to the circuit to accurately detect the disconnection state of the wire connected to each cell .

The pull-down element P shown in Fig. 2 is connected to each wire through a switch.

Then, the controller 40 can measure the voltage of each cell through on / off switching control of the switch connected to the pull-down device P, and detect the presence or absence of disconnection of the wire.

Hereinafter, the pull-down circuit will be described in more detail with reference to FIG.

Fig. 3 is an enlarged circuit diagram of the portion 200 of the dotted line in Fig. 2, and it is assumed that a line D is generated in the wire L2 connected to the positive (+) terminal of the second battery cell VC2 as shown. A resistor R and a capacitor C are connected to the second battery cell VC2 to constitute a filter. At the rear end of the filter, a pull-down current source is connected to the cell sensing line through a pull-down switch PSW.

Although the present embodiment shows a current source CS as a pull-down device, according to another embodiment of the present disclosure, a resistor may be used as a pull-down device. The current source CS supplies a current of 100 mA or more and 200 mA or less, preferably about 100 mA or more to the circuit.

Each of the voltage sensing lines to which the pull-down devices are connected is connected to the AMP 41 and the comparator 42 of the control unit 40 through a switch.

First, the control unit 40 senses the voltage of each cell in a state in which the pull-down switch PSW is opened. At this time, the initial voltage of the second battery cell VC2 will be measured to be equal to or somewhat lower than the voltage VC2 of the second battery cell VC2 due to the charge stored in the capacitor C.

Thereafter, the voltage of each cell is sensed while the pull-down switch PSW is closed. If the disconnection D does not occur in the wire L2, even if the pull-down switch PSW is closed and the current generated from the pull-down current source CS flows into the circuit, the current value is very small, A voltage that is equal to or slightly lower than the voltage VC2 of the second battery cell VC2 will be measured. However, if a disconnection D occurs in the wire L2, the pull-down switch PSW is closed and the pull-down current source CS affects the circuit. That is, the charge accumulated in the capacitor C does not affect the cell voltage sensing due to the pull-down operation. Therefore, the cell voltage VC2 sensed after closing the pull-down switch PSW will be sensed substantially at 0V.

According to another embodiment of the present invention, the controller 40 may repeat the switching operation of the pull-down switch at least two times so that the charge accumulated in the capacitor C is completely pulled down.

The voltages sensed in the pull-down switch-off state and the on-state are amplified through the AMP 41 and these voltages are compared in the comparator 42 to calculate the voltage difference? V and compare this voltage difference with a preset threshold value V _TH . According to one embodiment of the present invention, the threshold value V _TH can be set in a range of 300 mV or more and 1 V or less. Preferably, the threshold V _TH is set to approximately 500 mV.

When the difference value? V of the voltages sensed in the pull-down switch-off state and the on-state is smaller than the threshold value V _TH , it is determined as normal. If the difference value? V is larger than the threshold value V _TH , It is determined that a disconnection has occurred.

2 and 3, the control unit 40 and the pull-down circuit may be formed of an integrated circuit (IC), and the integrated circuit and the battery module may be connected through a plurality of wires and a connector.

FIG. 4 is a flowchart sequentially illustrating a method for diagnosing a single line in a battery management system according to an embodiment of the present invention.

The control unit 40 turns off the pull-down switch PSW so that the pull-down device (i.e., pull-down resistor or pull-down current source) is not conducted to the diagnostic circuit, and then sequentially senses the voltage of the battery cells (S401).

The voltage of the battery cells sensed in step S401 is stored in the memory as the first voltage.

Thereafter, the control unit 40 turns on the pull-down switch PSW so that the pull-down device (that is, the pull-down resistor or pull-down current source) conducts to the diagnostic circuit (S403). If a wire break occurs, the charges stored in the capacitor C connected to the wire will not affect the cell sensing voltage through the pull-down device.

Thereafter, the voltage of the battery cells is sequentially sensed (S405), and the voltage of the sensed battery cells is stored in the memory as the second voltage, as in step S401.

Thereafter, the pull-down switch PSW is changed to the OFF state again (S407).

Then, the first voltage and the second voltage of the sensed battery cells are compared (S409).

Through the step S409 derives the difference value ΔV of the two voltages, and it is determined smaller than the threshold value V _TH is a difference value ΔV of the two pre-set voltage (S411). The threshold value V _TH set here can be set in a range of 300 mV or more and 1 V or less, and is preferably set to about 500 mV or so.

Comparison result in step S411, when the difference value ΔV of the two groups is less than the voltage threshold V _TH is set determines that a wire connected to the battery cell in a normal state (S413).

However, it is determined that a result of comparison in step S411, of the two voltage difference ΔV is greater than a predetermined threshold V _TH wire is disconnected, connected to the battery cell (S415).

Thereafter, the control unit 40 compares the first voltage and the second voltage of the next cell sequentially (S413) to derive the difference value? V of the two voltages, and feeds back the result to the step S411 to continue the determination do.

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 40:
41: AMP 42: comparator
R: Resistor C: Capacitor
D: Disconnection P: Pulldown device
CS: Current Source PSW: Pulldown Switch
SW: Switch V _TH : Threshold

Claims (13)

1. A vehicle battery management system comprising:
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 the anode or the cathode of each battery cell of the battery module to the control unit;
A capacitor connected in parallel to each of the battery cells;
A pull-down device connected to the wire through a switch; And
A first voltage of the battery cell in an off state of the switch and a second voltage of the battery cell in an on state of the switch are compared to detect a voltage of the battery cell by on / And a disconnection detecting section for detecting disconnection of the battery.
The method according to claim 1,
Wherein the pull-down device is a current source that supplies a predetermined current.
3. The method of claim 2,
Wherein the current supplied by the current source is 100 mA or more and 200 mA or less.
The apparatus according to claim 1,
Detecting a difference between the first voltage and the second voltage, and determining that a disconnection of the wire occurs when the difference is greater than a predetermined threshold value.
5. The method of claim 4,
Wherein the threshold value is set to 500 mV or less.
The apparatus according to claim 1,
Sensing the battery cells of the battery module sequentially in an off state of the switch to store the first voltage of the battery cells,
The second voltage of the battery cells is stored by sequentially sensing the battery cells of the battery module after operating the pull-down device by turning on the switch,
And sequentially detects whether the wire is disconnected by sequentially comparing the stored first voltage and the second voltage based on the position of the battery cell.
The method according to claim 1,
Wherein the controller, the 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 the wires.
An apparatus for monitoring and controlling charge and discharge of a plurality of battery cells connected in series by wires,
A pull-down device;
A switch element connecting the wire and the pull-down element; And
The first voltage of the battery cell in the off state of the switch and the second voltage of the battery cell in the on state of the switch are compared with each other to sense the voltage of the battery cell by on / And a disconnection detection unit for detecting disconnection of the battery.
9. The method of claim 8,
Wherein the pull-down device is a current source that supplies a predetermined current.
9. The apparatus according to claim 8,
Sensing the battery cells sequentially in an off state of the switch element to store the first voltage of the battery cells,
Sensing the battery cells sequentially in an on state of the switch device to store the second voltage of the battery cells,
And sequentially detects whether the wire is disconnected by sequentially comparing the stored first voltage and the second voltage based on the position of the battery cell.
A method of detecting a disconnection in a diagnostic circuit for detecting whether a wire is disconnected by using a pull-down device connected to a plurality of battery cells connected in series by wires,
Sequentially sensing a voltage of the battery cells in a state where the pull-down device is not conducted to the diagnostic circuit;
Storing a voltage of the sensed battery cells as a first voltage;
Conducting the pull-down device to the diagnostic circuit and sequentially sensing a voltage of the battery cells;
Storing the voltage of the sensed battery cells as a second voltage;
Comparing the first voltage and the second voltage to derive a sensed voltage difference of each of the battery cells; And
Comparing the derived voltage difference with a predetermined threshold value to determine that wire breakage has occurred in a battery cell exceeding the threshold value.
12. The method of claim 11,
Wherein the pull-down device is a current source that supplies a predetermined current.
12. The method of claim 11,
Wherein the step of conducting the pull-down device to the diagnostic circuit and sequentially sensing the voltage of the battery cells comprises:
Wherein the pull-down device conducts at least two times to the diagnostic circuit through on / off control of the switch.

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