Patent Description:
Unlike a primary battery, which is not rechargeable, a secondary battery can be charged and discharged. Low-capacity secondary batteries may be used for, e.g., portable small-sized electronic devices, e.g., a smart phone, a feature phone, a notebook computer, a camcorder, and the like, and high-capacity secondary batteries may be used for, e.g., driving a motor for a hybrid car, an electric vehicle, a power storage cell, and the like.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

<CIT> discloses a sampling detection circuit and a method for detecting a circuit malfunction.

<CIT> discloses an apparatus and method for diagnosing an abnormality in a cell balancing circuit in a battery pack including a plurality of cells corresponding to each cell balancing circuit.

<CIT> discloses an assembled battery system including a plurality of serially connected battery cells, and voltage detecting lines connectable at one end to electrodes of the battery cells of the assembled battery.

An embodiment is directed to a battery management system as described in claim <NUM>, and a method according to claim <NUM>.

Features will become apparent to those of skill in the art by describing in detail example embodiments with reference to the attached drawings in which:.

Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey example implementations to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being "under" another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

In addition, it will be understood that when an element A is referred to as being "connected to" an element B, the element A can be directly connected to the element B or an intervening element C may be present therebetween such that the element A and the element B are indirectly connected to each other.

As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprise or include" and/or "comprising or including," when used in this specification, specify the presence of stated features, numbers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof.

It will be understood that, although the terms first, second, etc. may be used herein to describe various members, elements, regions, layers and/or sections, these members, elements, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one member, element, region, layer and/or section from another. Thus, for example, a first member, a first element, a first region, a first layer and/or a first section discussed below could be termed a second member, a second element, a second region, a second layer and/or a second section without departing from the teachings of the present disclosure.

In addition, a control unit (controller) and/or other related devices or components according to the present disclosure may be implemented using any suitable hardware, firmware (e.g., application specific semiconductor), software, or a suitable combination of software, firmware, and hardware. For example, various components of the control unit and/or other related devices or parts according to the present disclosure may be formed on one integrated circuit chip or on separate integrated circuit chips. In addition, various components of the control unit may be implemented on a flexible printed circuit film, and may be formed on a tape carrier package, a printed circuit board, or the same substrate as the control unit.

<FIG> is a schematic diagram illustrating a battery management system according to an example embodiment.

Referring to <FIG>, a battery management system <NUM> according to an example embodiment includes a diode unit <NUM>, a switch unit <NUM>, a sensing unit <NUM>, and a control unit <NUM>. The battery management system <NUM> may be connected to a battery <NUM>, to manage the battery <NUM>.

The battery <NUM> may include a plurality of battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, and may be charged or discharged at a constant voltage. In an example embodiment, the battery <NUM> may include a plurality of battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> connected in series.

Although the battery <NUM> is illustrated in <FIG> as having five battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> connected in series, the number of battery cells may be greater or less than five. For the sake of explanation, the battery <NUM> will be described as including a first battery cell <NUM>, a second battery cell <NUM>, a third battery cell <NUM>, a fourth battery cell <NUM>, and a fifth battery cell <NUM>.

The first battery cell <NUM> may be a cell located at a minus terminal side of the battery <NUM>, and the fifth battery cell <NUM> may be a cell located at a plus terminal side of the battery <NUM>. The first battery cell <NUM> may be referred to as a lowermost battery cell, and the fifth battery cell <NUM> may be referred to as an uppermost battery cell.

The diode unit <NUM> may include a plurality of diodes <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> connected in parallel to each of the plurality of battery cells <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The number of diodes <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may correspond to the number of battery cells <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. For example, the diode unit <NUM> may include a first diode <NUM>, a second diode <NUM>, a third diode <NUM>, a fourth diode <NUM>, and a fifth diode <NUM>.

The plurality of diodes <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may allow the voltages of the battery cells <NUM>, <NUM>, <NUM>, <NUM> and <NUM> to be measured even when at least one of sensing lines is disconnected. This will be described in additional detail below.

The switch unit <NUM> may include a plurality of switches <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> connected to each of the plurality of battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. For example, the switch unit <NUM> may include a first switch <NUM>, a second switch <NUM>, a third switch <NUM>, a fourth switch <NUM>, and a fifth switch <NUM>.

The respective switches <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may open/close discharge paths of the corresponding battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

The sensing unit <NUM> may include a plurality of sensing lines <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> for sensing voltages of each of the plurality of battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. For example, the sensing unit <NUM> may include a first sensing line <NUM>, a second sensing line <NUM>, a third sensing line <NUM>, a fourth sensing line <NUM>, and a fifth sensing line <NUM>.

The plurality of sensing lines <NUM> , <NUM>, <NUM>, <NUM>, and <NUM> may be connected to a plus side of each of the battery cells <NUM> , <NUM>, <NUM> , <NUM> and <NUM>.

The switch unit <NUM> may include a discharge resistor connected to both ends of each of the switches <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, to perform cell balancing of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. For example, a discharge resistor may be connected between each end of each of the switches <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and a corresponding one of the sensing lines <NUM> , <NUM>, <NUM> , <NUM>, and <NUM>.

The control unit <NUM> may detect voltages, currents, temperatures, etc. of the respective battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> which constitute the battery <NUM>, and may control cell balancing for the battery <NUM>. In an example embodiment, the control unit <NUM> may include a microprocessor, a central processing unit (CPU), and an application-specific integrated circuit (ASIC), such as an analog front end (AFE).

The control unit <NUM> may divide the switch unit <NUM> into an even-numbered group and an odd-numbered group. The even-numbered group may include the switches <NUM> and <NUM>. The odd-numbered group may include the switches <NUM>, <NUM>, and <NUM>. The control unit <NUM> may alternately turns on the switches <NUM> and <NUM> of the even-numbered group and the switches <NUM>, <NUM>, and <NUM> of the odd-numbered group to perform cell balancing. Accordingly, the control unit <NUM> may shorten the time required for cell balancing, compared to a case of sequentially balancing the plurality of battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

In addition, the control unit <NUM> may measure voltages before and after cell balancing of each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> to detect disconnection of the sensing lines <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. This now will be described in additional detail.

Hereinafter, a method in which the control unit <NUM> detects the disconnection of the sensing lines <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> will be described in more detail. As an example, a case in which the second sensing line <NUM> (connected to the second battery cell <NUM>) is disconnected (indicated by 'X' on the second sensing line <NUM> in <FIG>) will be described.

<FIG> are schematic diagrams for explaining a method for detecting the disconnection of a sensing line in a battery management system.

First, referring to <FIG>, the control unit <NUM> may measure voltages of the respective battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> in a state in which the switch unit <NUM> is turned off, e.g., in which the switches <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are all open or nonconductive.

The control unit <NUM> may measure the voltages of the respective battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> through the sensing unit <NUM>. In an example embodiment, the control unit <NUM> may measure sensing voltages V1, V2, V3, V4, and V5 of the respective battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> through the sensing lines <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. The control unit <NUM> may obtain a difference between each of the sensing voltages V1, V2, V3, V4, and V5 of the respective battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and a sensing voltage of an adjacent lower battery cell to measure the voltages of the respective battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

Even when any one sensing line of the sensing unit <NUM> is disconnected (or opened), a sensing voltage may be measured from the disconnected sensing line by means of the diode unit <NUM>. For example, referring to <FIG>, when the sensing voltage V3 measured from the third sensing line <NUM> is <NUM> V, and the sensing voltage V1 measured from the first sensing line <NUM> is <NUM> V, a sensing voltage V2 of <NUM> V, which is an intermediate voltage between the third diode <NUM> and the second diode <NUM>, may be measured from the disconnected second sensing line <NUM> through the use of voltage division therebetween.

The control unit <NUM> may measure voltages of the respective battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> by obtaining a difference between each of the sensing voltages measured from the respective sensing lines <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and the sensing voltage measured from an adjacent lower sensing line.

For example, the control unit <NUM> may obtain a difference (V3-V2) between <NUM> V (which is the sensing voltage V3 measured from the third sensing line <NUM>) and <NUM> V (which is the sensing voltage V2 measured from the second sensing line <NUM>), thereby determining that the voltage of the third battery cell <NUM> is <NUM> V.

Similarly, the control unit <NUM> may measure a difference (V2-V1) between <NUM> V (which is the sensing voltage V2 measured from the second sensing line <NUM>) and <NUM> V (which is the sensing voltage V1 measured from the first sensing line <NUM>), thereby determining that the voltage of the second battery cell <NUM> is <NUM> V.

In the same manner as described above, the control unit <NUM> may obtain the voltages of the respective battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

In addition, when the switch unit <NUM> is turned off, the control unit <NUM> may define a voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and an adjacent upper battery cell as a first upper voltage difference and a voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and an adjacent lower battery cell as a first lower voltage difference, to then store the same in a storage unit (not shown). Here, the first lower voltage difference means the voltage of each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

Next, referring to <FIG>, the control unit <NUM> may turn on the switches <NUM> and <NUM> of the even-numbered group of the switch unit <NUM> to perform cell balancing for a predetermined period of time, and may then measure the sensing voltages of the even-numbered battery cells <NUM> and <NUM> and then turn off the switches <NUM> and <NUM> of the even-numbered group.

Then, referring to <FIG>, the control unit <NUM> may turn on the switches <NUM>, <NUM>, and <NUM> of the odd-numbered group to perform cell balancing for a predetermined period of time, and may then measure the sensing voltages of the odd-numbered battery cells <NUM>, <NUM>, and <NUM> and then turn off the switches <NUM>, <NUM>, and <NUM> of the odd-numbered group.

In an example embodiment, the cell balancing time may be set for a period of several seconds.

When the sensing line is disconnected during cell balancing, the sensing voltage of the corresponding battery cell is measured as being similar to the sensing voltage measured at the sensing line connected to the lower battery cell. Therefore, after cell balancing, the voltage difference between the sensing voltage of each battery cell and the sensing voltage of an adjacent lower battery cell becomes relatively lower than the voltage difference before cell balancing. In other words, in the battery cell connected to the disconnected sensing line, the voltage after cell balancing becomes lower than the voltage before cell balancing. In addition, since the voltage of the battery cell connected to the disconnected sensing line is lowered, the voltage of an adjacent upper battery cell is relatively increased. In addition, the control unit <NUM> may define, when the switch unit <NUM> is turned on, a voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and an adjacent upper battery cell as a second upper voltage difference and a voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and an adjacent lower battery cell as a second lower voltage difference to then store the same in the storage unit. Here, the second lower voltage difference means the voltage of each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> after cell balancing.

As such, when the second lower voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and the adjacent lower battery cell is smaller than the first lower voltage difference, the control unit <NUM> may determine that the sensing line of the corresponding battery cell is disconnected. In addition, when the second upper voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and the adjacent upper battery cell is smaller than the second upper voltage difference, the control unit <NUM> may determine that the sensing line of the corresponding battery cell is disconnected.

For example, referring again to <FIG>, when the second switch <NUM> is turned on, the second battery cell <NUM> is not connected to the second sensing line <NUM>, and thus the voltage V2 is measured to be about <NUM> V, which is similar to the voltage V1 measured from the first sensing line <NUM>. Accordingly, the control unit <NUM> may obtain a difference (V2-V1) between <NUM> V (which is the voltage V2 measured from the second sensing line <NUM>) and <NUM> V (which is the voltage V1 measured from the first sensing line <NUM>), thereby determining that the voltage of the second battery cell <NUM> is <NUM> V. In addition, the control unit <NUM> may obtain a difference (V3-V2) between <NUM> V (which is the voltage V3 measured from the third sensing line <NUM>) and <NUM> V (which is the voltage V2 measured from the second sensing line <NUM>), thereby determining that the voltage of the third battery cell <NUM> is <NUM> V.

Thus, the control unit <NUM> may compare the first upper voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and the upper battery cell thereof before cell balancing, with the second upper voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and the upper battery cell thereof after cell balancing, and, when the second upper voltage difference is greater than the first upper voltage difference, may determine that the sensing line of the corresponding battery cell is disconnected. In addition, the control unit <NUM> may compare the first lower voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and the lower battery cell thereof before cell balancing, with the second lower voltage difference between each of the battery cells <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and the lower battery cell thereof after cell balancing, and, when the second lower voltage difference is greater than the first lower voltage difference, may determine that the sensing line of the corresponding battery cell is disconnected.

By way of summation and review, in a vehicle using a secondary battery, the performance of each cell may directly affect the performance of the vehicle. Thus, a charge/discharge of each cell may be managed by measuring a voltage and current of each cell. For this, a battery management system (BMS) capable of stably controlling the corresponding cell by monitoring a state of a sensing unit that senses each cell may be used.

As described above, embodiments may provide a battery management system capable of detecting disconnection of a sensing line of a battery cell. As described above, in a battery management system according to an example embodiment, a disconnection of a sensing line may be detected by comparing a voltage difference between each battery cell and an adjacent battery cell in a state in which switches are turned off with a voltage difference between each battery cell and an adjacent battery cell after turning on the switches, thereby improving safety.

Claim 1:
A battery management system (<NUM>), comprising:
a plurality of diodes (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) which are configured to be connected in parallel to a plurality of battery cells (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>), the plurality of battery cells (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>), being connected in series;
a switch unit (<NUM>) which includes a plurality of switches (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) respectively configured to be connected to the plurality of battery cells (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
a control unit (<NUM>) which is configured to detect voltages of the plurality of battery cells (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and is configured to perform cell balancing; and
a plurality of sensing lines (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) which are configured to connect the plurality of battery cells (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the control unit (<NUM>),
wherein the control unit (<NUM>) is further configured to:
measure a first upper voltage difference between each battery cell (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and an adjacent upper battery cell in a state in which the switches (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) are turned off,
measure a second upper voltage difference between each battery cell (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the adjacent upper battery cell after turning on the switches (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) for a predetermined time,
when the second upper voltage difference is greater than the first upper voltage difference, determine that a sensing line of a corresponding battery cell is a disconnected sensing line,
characterised in that the control unit (<NUM>) is further configured to:
measure a first lower voltage difference between each battery cell (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and an adjacent lower battery cell in a state in which the switches (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) are turned off,
measure a second lower voltage difference between each battery cell (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the adjacent lower battery cell after turning on the switches (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) for a predetermined time, and
when the second lower voltage difference is smaller than the first lower voltage difference, determine that the sensing line of the corresponding battery cell is disconnected.