Patent Description:
A high-voltage battery for storing electrical energy obtained from various energy sources is applied to the environmentally-friendly vehicles. A high voltage battery includes a plurality of cells in series or in parallel to provide high voltage electrical energy.

A battery management system (BMS) for managing a high voltage battery is mounted in a vehicle to which the high voltage battery is applied. A cell balancing function which compensates a voltage deviation between cells by monitoring the voltage of each of the cells is one of the main functions of the battery management system. The battery management system calculates a state of charge (SOC) based on voltage, current, and temperature information of each cell that constitutes the high voltage battery, and performs cell balancing to compensate for voltage deviation when a SOC difference between the cells is equal to or higher than a predetermined level.

The SOC is used to predict available capacity, cycle-life, etc. of a battery in addition to the cell balancing. Therefore, it is necessary to accurately calculate the SOC to improve usability and stability of the battery. Calculation accuracy of SOC is closely related to measurement accuracy of cell voltage and temperature.

The cell voltage measurement in the battery management system is performed by an integrated circuit (IC), e.g., an analog front end (AFE) IC, having a built-in voltage detection circuit. In general, the measurement accuracy of a cell voltage of an integrated circuit at a low temperature is significantly lower than at room temperature, and the calculation accuracy of SOC is also lowered. <CIT> disclose a cell balancing control device in which an increase of the internal temperature of the device is avoided by a temperature control. <CIT> discloses a battery system monitoring device with a temperature detection unit in the vicinity of a first control device which includes a balancing switch.

An exemplary embodiment has been made in an effort to provide a voltage detection integrated circuit and a battery management system including the same for improving cell voltage measurement accuracy in a low temperature environment.

An exemplary embodiment of the present invention provides a voltage detection integrated circuit including: a voltage detection circuit electrically connected to a plurality of cells to detect a cell voltage of a corresponding one of the plurality of cells; a plurality of cell balancing switches configured to conduct or block a flow of a balancing current of a corresponding cell among the plurality of cells; a temperature sensor configured to detect an internal temperature of the voltage detection integrated circuit; and a controller configured to differently select a number of cell balancing switches that are simultaneously turned on depending on the internal temperature, and to turn on the selected switches, when the internal temperature is below a first threshold value.

In the voltage detection integrated circuit according to the exemplary embodiment, the controller may group the plurality of cell balancing switches into a plurality of groups and alternately turns on the plurality of groups when the internal temperature is less than a first threshold value.

In the voltage detection integrated circuit according to the exemplary embodiment, the controller may control turn-on times of the plurality of groups to be the same.

In the voltage detection integrated circuit according to the exemplary embodiment, the controller may simultaneously turns on the plurality of cell balancing switches when the internal temperature is less than the first threshold value, and then may gradually increase the number of cell balancing switches that are turned off as the internal temperature rises.

In the voltage detection integrated circuit according to the exemplary embodiment, the voltage detection integrated circuit may include: a multiplexer configured to select one of the plurality of cells; a differential amplifier configured to amplify and output a voltage between opposite ends of the cell selected by the multiplexer; a reference voltage supply circuit configured to supply a reference voltage; and an analog digital converter configured to output a digital value corresponding to a cell voltage of the cell selected by the multiplexer based on the reference voltage, and the temperature sensor may be disposed in contact with or adjacent to the reference voltage supply circuit.

The voltage detection integrated circuit may further include a heat generation circuit, and the controller may receive an ambient temperature of the voltage detection integrated circuit from a temperature sensor outside the voltage detection integrated circuit, and may control the heat generation circuit to generate heat when the ambient temperature is lower than a second threshold in a state where the internal temperature reaches the first threshold value and thus the plurality of cell balancing switches are turned off.

In the voltage detection integrated circuit, the heat generation circuit may include a heat generation switch connected between a positive terminal of a first one of the plurality of cells and a negative terminal of a second one of the plurality of cells.

In the voltage detection integrated circuit, the controller may turn off the heat generation switch when the ambient temperature is equal to or higher than the second threshold.

In the voltage detection integrated circuit, the controller may calculate a heat generation amount of the heat generation circuit based on the internal temperature and the ambient temperature, and may PWM-control the heat generation switch with a duty ratio corresponding to the heat generation amount.

In the voltage detection integrated circuit, the controller may calculate a heat generation amount of the heat generation circuit based on the internal temperature and the ambient temperature, and may control a turn-on and turn-off period of the heat generation switch depending on the heat generation amount.

The voltage detection integrated circuit may further include a heat generation resistor connected between the heat generation switch and the positive terminal of the first cell or between the heat generation switch and the negative terminal of the second cell.

In addition, a battery management system may include: an integrated circuit configured to include a voltage detection circuit that is electrically connected to a plurality of cells to detect a cell voltage of a corresponding cell of the plurality of cells, a plurality of cell balancing switches that conduct or block a flow of a balancing current of a corresponding cell among the plurality of cells, and a first temperature sensor; and a battery controller configured to differently select a number of cell balancing switches that are simultaneously turned on depending on an internal temperature of the integrated circuit detected through the first temperature sensor when the internal temperature is less than a threshold value, and to turn on the selected switches.

In the battery management system, the battery controller may group the plurality of cell balancing switches into a plurality of groups and alternately turn on the plurality of groups when the first temperature is less than the first threshold value.

In the battery management system, the battery controller may control turn-on times of the plurality of groups to be the same.

In the battery management system, the battery controller may simultaneously turn on the plurality of cell balancing switches when the internal temperature is less than the first threshold value, and then may gradually increase the number of cell balancing switches that are turned off as the internal temperature rises.

The battery management system may further include a second temperature sensor configured to detect an ambient temperature of the integrated circuit, and the integrated circuit may further include a heat generation circuit that generates heat depending on the ambient temperature.

In the battery management system, the battery controller may control the heat generation circuit to generate heat when the ambient temperature is lower than a second threshold in a state where the internal temperature reaches the first threshold value and thus the plurality of cell balancing switches are turned off.

In the battery management system, the heat generation circuit may include a heat generation switch connected between a positive terminal of a first one of the plurality of cells and a negative terminal of a second one of the plurality of cells.

In the battery management system, the battery controller may turn off the heat generation switch when the ambient temperature is equal to or higher than the second threshold.

In the battery management system, the battery controller may calculate a heat generation amount of the heat generation circuit based on the internal temperature and the ambient temperature, and may control turn-on and turn-off of the heat generation switch depending on the heat generation amount.

According to the exemplary embodiment, the battery management system has an effect of improving cell voltage measurement accuracy in a low temperature environment.

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the scope of the present invention.

To clearly describe the exemplary embodiments, parts that are irrelevant to the description are omitted, and like numerals refer to like or similar constituent elements throughout the specification. Therefore, the reference numbers of the constituent elements used in a previous drawing may be used in a subsequent drawing.

Further, since sizes and thicknesses of constituent members shown in the accompanying drawings are arbitrarily given for better understanding and ease of description, the exemplary embodiments are not limited to the illustrated sizes and thicknesses. In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity.

A case of electrically connecting two constituent elements includes not only a case of directly connecting the constituent elements but also a case of connecting the constituent elements via another constituent element therebetween. The constituent element therebetween may include a switch, a resistor, a capacitor, and the like. In describing exemplary embodiments, an expression of connection indicates electrical connection unless explicitly described to be direct connection.

Hereinafter, a voltage detection integrated circuit (IC) and a battery management system (BMS) including the same according to exemplary embodiments will be described in detail with reference to necessary drawings. In this document, the voltage detection IC may include an analog front end (AFE) IC including a cell voltage detection function of a battery, a cell voltage monitoring (CVM) IC, and the like.

<FIG> schematically illustrates a battery management system according to an exemplary embodiment. <FIG> schematically illustrates a configuration of the voltage detection IC of <FIG>, and <FIG> illustrates a view for describing heat generation of the cell balancing switch.

Referring to <FIG>, a battery management system according to the present exemplary embodiment may include a voltage detection IC <NUM> and a battery controller <NUM>.

The voltage detection IC <NUM> may include a plurality of cell balancing switches SW, a voltage detection circuit <NUM>, an interface <NUM>, and a controller <NUM>.

The voltage detection IC <NUM> may be electrically connected to a cell group <NUM> to detect a cell voltage of each cell constituting the cell group <NUM> through the voltage detection circuit <NUM>. Although a case where the cell group <NUM> connected to the voltage detection IC <NUM> includes six cells connected in series with each other is illustrated in <FIG> as an example, the present invention is not limited thereto, and a number of unit cells connected to the detection IC may be changed to be greater or smaller than that.

Referring to <FIG>, the voltage detection circuit <NUM> may include a multiplexer (MUX) <NUM>, a differential amplifier <NUM>, and an analog-to-digital converter (ADC) <NUM>. The voltage detection circuit <NUM> may further include a reference voltage supply circuit <NUM> for supplying the reference voltage Vref to the ADC <NUM>.

An input channel of the multiplexer <NUM> is electrically connected to each cell constituting the cell group <NUM> through an input resistor Rc. The multiplexer <NUM> selects one of the input channels and connects it to an output channel. Specifically, the multiplexer <NUM> selects one of the plurality of cells connected to the input channel, and connects opposite ends of the selected cell to a positive output terminal and a negative output terminal of the output channel, respectively.

The input resistor Rc connected to the input channel of the multiplexer <NUM> may constitute an RC filter together with an input capacitor Cc to serve to filter a noise included in the cell voltage.

A voltage between opposite ends of the cell selected by the multiplexer <NUM> is amplified by the differential amplifier <NUM> to be outputted.

The reference voltage supply circuit <NUM> supplies the reference voltage Vref to the ADC <NUM>.

The ADC <NUM> converts an output of the differential amplifier <NUM>, which is an analog value, into a digital value based on the reference voltage Vref, and outputs the digital value to the controller <NUM>. That is, the ADC <NUM> converts the voltage between opposite ends of the cell selected by the multiplexer <NUM> into a corresponding digital value and outputs it.

A cell voltage detection result outputted to the controller <NUM> by the ADC <NUM> is transferred to the battery controller <NUM> through the interface <NUM>.

The interface <NUM> may transmit and receive data to and from the battery controller <NUM> using a serial peripheral interface (SPI) method such as controller area network (CAN) communication.

The battery controller <NUM> receiving the cell voltage detection result from the voltage detection IC <NUM> may control cell balancing, charging, discharging, etc. of the cell group <NUM> based on the result.

Referring again to <FIG>, the voltage detection IC <NUM> may control cell balancing of the cells constituting the cell group <NUM>.

Each cell balancing switch SW is connected between opposite ends of a corresponding cell through a corresponding balancing resistor Rb. Each cell balancing switch (SW) conducts or blocks a flow of a cell balancing current of the corresponding cell under control of the controller <NUM>. When each cell balancing switch SW is turned on, the balancing current flows through the corresponding balancing resistor (Rb) to discharge the corresponding cell. On the other hand, when each cell balancing switch SW is turned off, the flow of the balancing current of the corresponding cell is blocked.

Each cell balancing switch SW may be formed of a field effect transistor (FET).

The controller <NUM> receives cell balancing control information from the battery controller <NUM> through the interface <NUM>, and controls turn-on/turn-off of each cell balancing switch SW based on the received cell balancing control information.

When the voltage detection IC <NUM> is exposed to a low temperature environment, voltage detection accuracy of the voltage detection circuit <NUM> tends to be significantly lower than at room temperature. This is because the reference voltage supply circuit <NUM> for supplying the reference voltage Vref to the ADC <NUM> is affected by the temperature so that a level of the reference voltage Vref outputted by the reference voltage supply circuit <NUM> becomes different between the low temperature and the room temperature. The conversion of the ADC <NUM> is performed based on the reference voltage Vref. Therefore, a change in the level of the reference voltage Vref in the low temperature environment may act as a factor to increase an error of the output value of the ADC <NUM>.

To solve this problem, the voltage detection IC <NUM> may further include a temperature sensor <NUM>.

The temperature sensor <NUM> may detect an internal temperature of the voltage detection IC <NUM>. The temperature sensor <NUM> may be disposed to be in contact with or adjacent to the reference voltage supply circuit <NUM> so as to detect an ambient temperature of the reference voltage supply circuit <NUM>, which is sensitive to temperature and acts as a cause of a cell voltage detection error in the low temperature range.

The controller <NUM> may turn on at least one cell balancing switch SW to increase the internal temperature of the voltage detection IC <NUM> when the temperature detected through the temperature sensor <NUM> is included in the low temperature region. That is, the controller <NUM> may turn on at least one cell balancing switch SW to increase the temperature when the temperature detected through the temperature sensor <NUM> is below a threshold value. Herein, the threshold value is a boundary value for determining the low temperature region, and may be set differently depending on an environment in which the battery management system is mounted.

Referring to <FIG>, when a cell balancing switch SW is turned on, a balancing current Ib flows into an internal resistor Rsw of the cell balancing switch SW to cause the cell balancing switch SW to generate heat. The heat generation of the cell balancing switch SW may operate as a heat source for increasing the internal temperature of the voltage detection IC <NUM>.

The value of the internal resistor Rsw of the cell balancing switch SW varies depending on a manufacturing process and design of the voltage detection IC <NUM>, and depends on characteristics (e.g., temperature, drain-to-source voltage, etc.) of a FET constituting the cell balancing switch SW. For example, the value of the internal resistor Rsw of the cell balancing switch SW may range from as small as <NUM> ohms up to tens of ohms.

When the cell balancing current Ib and the value of the internal resistor Rsw of each cell balancing switch SW are respectively designed to be <NUM> mA and <NUM> ohms in the voltage detection IC <NUM> including six connected cells, an energy amount P consumed by heat generation of the internal resistor Rsw of one cell balancing switch SW is <NUM> W. As a result, when all of the six cell balancing switches SW are turned on, the energy amount P consumed by the heat generated by the internal resistors Rsw of the six cell balancing switches SW is <NUM> W.

Meanwhile, when all of the cell balancing switches SW are simultaneously turned on to raise the internal temperature of the voltage detection IC <NUM>, this may exceed a maximum power consumption that the voltage detection IC <NUM> can withstand, or may cause an excessive temperature rise of the voltage detection IC <NUM>, leading to damage of the voltage detection IC <NUM>.

Accordingly, the controller <NUM> may divide the cell balancing switches SW included in the voltage detection IC <NUM> into a plurality of groups, and alternately turn on each cell balancing switch group. For example, the voltage detection IC <NUM> may group <NUM> or <NUM> cell balancing switches SW, and may alternately turn on each cell balancing switch group. For example, the voltage detection IC <NUM> may group odd-numbered cell balancing switches SW and even-numbered cell balancing switches SW into different groups, and may alternately turn on each cell balancing switch group.

When a temperature rising speed for turning on the cell balancing switches SW is too fast, even if the cell balancing switch SW is turned off after reaching a desired temperature range, the temperature rise may continue for a predetermined time. This may cause an unwanted additional temperature rise, which may result in damage to the voltage detection IC <NUM>.

Accordingly, the controller <NUM> may differently control a number of cell balancing switches SW that are simultaneously turned on depending on the temperature detected through the temperature sensor <NUM>, so as to minimize an unnecessary additional temperature rise while quickly allowing the temperature of the voltage detection IC <NUM> to reach a room temperature region. For example, when the voltage detection IC <NUM> is connected to <NUM> cells, the number of cell balancing switches SW simultaneously turned on for a temperature rise may be controlled to be <NUM> at lower than -<NUM>, <NUM> in a range of -<NUM> to -<NUM>, <NUM> in a range of -<NUM> to -<NUM>, <NUM> in a range of -<NUM> to - <NUM>, and <NUM> in a range of -<NUM> to <NUM>.

When the temperature is less than the threshold value, the controller <NUM> may turn on all the cell balancing switches SW at the same time, and then may control the cell balancing switches SW such that the number of cell balancing switches SW that are turned off gradually increases depending on the temperature rise.

In the meantime, as the cell balancing switches SW are used for increasing the temperature, it is necessary to minimize a degree to which turn-on control of the cell balancing switches for increasing the temperature deteriorates a balancing deviation between the cells or affects intercell deviation information pre-calculated by battery controller <NUM>. However, when turn-on is allowed only for cells that require cell balancing, it may take too much time for the temperature to rise, which may reduce the temperature rise effect.

Accordingly, the controller <NUM> may minimize an effect of the turn-on of the cell balancing switches SW for increasing the temperature on the cell balancing by controlling a time at which a corresponding cell balancing switch SW is turned on for increasing the temperature to be the same for all the cells.

When the temperature detected by the temperature sensor <NUM> is equal to or higher than the threshold value, the controller <NUM> turns off all the cell balancing switches SW that are turned on to stop increasing the temperature using the cell balancing switches SW.

<FIG> schematically illustrates a control method of the cell balancing switches of the battery management system of <FIG>. The control method of the cell balancing switches illustrated in <FIG> may be performed by the voltage detection IC <NUM> described with reference to <FIG>.

Referring to <FIG>, the controller <NUM> detects the internal temperature of the voltage detection IC <NUM> through the temperature sensor <NUM> (S100).

The controller <NUM> determines whether the temperature detected through the temperature sensor <NUM> is included in the low temperature region by comparing the temperature detected through the temperature sensor <NUM> with a threshold value (S110).

The controller <NUM> controls at least one cell balancing switch SW to be turned on to increase the internal temperature of the voltage detection IC <NUM> when the temperature detected through the temperature sensor <NUM> is included in the low temperature region (S120).

In step S120, the controller <NUM> may divide the cell balancing switches SW included in the voltage detection IC <NUM> into a plurality of groups, and may alternately turn on each cell balancing switch group.

In step S120, the controller <NUM> may control the number of cell balancing switches SW that are simultaneously turned on to be different depending on the temperature detected through the temperature sensor <NUM>. In this case, the controller <NUM> may control the number of cell balancing switches SW to be simultaneously turned on to increase as the temperature detected through the temperature sensor <NUM> is lower.

In step S120, the controller <NUM> may turn on all the cell balancing switches SW at the same time, and then may control the cell balancing switches SW such that the number of cell balancing switches SW that are turned off gradually increases depending on the temperature rise.

In step S120, the controller <NUM> may control a time at which a corresponding cell balancing switch SW is turned on for increasing the temperature to be the same for all the cells.

The controller <NUM> continuously detects the internal temperature of the voltage detection IC <NUM> through the temperature sensor <NUM> even while raising the internal temperature of the voltage detection IC <NUM> through the turn-on control of the cell balancing switches SW (S130). In addition, the controller <NUM> determines whether the temperature detected through the temperature sensor <NUM> is out of the low temperature range (S140).

When the temperature detected through the temperature sensor <NUM> is out of the low temperature range, the controller <NUM> controls all the cell balancing switches SW that are turned on for increasing the temperature to be turned off (S150), to stop heat generation of the cell balancing switches SW.

<FIG> schematically illustrates a battery management system according to another exemplary embodiment.

Referring to <FIG>, a battery management system according to the present exemplary embodiment may include a voltage detection IC <NUM> and a battery controller <NUM>. In the following, detailed descriptions of same or similar components as those of the battery management system described with reference to <FIG> will be omitted.

The voltage detection IC <NUM> may be electrically connected to a cell group <NUM> to detect a cell voltage of each cell constituting the cell group <NUM> through the voltage detection circuit <NUM>.

The voltage detection circuit <NUM> includes a multiplexer (see reference numeral <NUM> of <FIG>), a differential amplifier (see reference numeral <NUM> of <FIG>), an ADC (see reference numeral <NUM> of <FIG>), and a reference voltage supply circuit (see reference numeral <NUM> of <FIG>).

When one of the cells is selected by the multiplexer, the voltage detection circuit <NUM> outputs a cell voltage of the selected cell to the controller <NUM> through the differential amplifier and the ADC.

When the cell voltage is outputted from the voltage detection circuit <NUM>, the controller <NUM> transfers the cell voltage to the battery controller <NUM> through the interface <NUM>. The battery controller <NUM> receiving the cell voltage detection result from the voltage detection IC <NUM> may control cell balancing, charging, discharging, etc. of the cell group <NUM> based on the result.

The voltage detection IC <NUM> may control cell balancing of the cells constituting the cell group <NUM>.

Each cell balancing switch SW is connected between opposite ends of a corresponding cell through a corresponding balancing resistor Rb to conduct or block a flow of a cell balancing current of the corresponding cell under the control of the controller <NUM>.

In the detection circuit <NUM>, the reference voltage supply circuit for supplying the reference voltage Vref to the ADC is sensitive to temperature. Therefore, in the low temperature environment, a level of the reference voltage Vref outputted from the reference voltage supply circuit is different from at room temperature. The conversion of the ADC is performed based on the reference voltage Vref. Therefore, a change in the level of the reference voltage Vref in the low temperature environment may act as a factor to increase an error of the output value of the ADC.

To solve this problem, the controller <NUM> continuously monitors the reference voltage Vref supplied from the voltage detection circuit <NUM> to the ADC, and may perform such control so as to increase the internal temperature of the voltage detecting IC <NUM> when the reference voltage Vref is out of a predetermined range. That is, when the reference voltage Vref is out of the predetermined range, the controller <NUM> may determine that the internal temperature of the voltage detection IC <NUM> is included in the low temperature region, and may turn on at least one cell balancing switch SW to increase the internal temperature of the voltage detection IC <NUM>. Herein, the predetermined range corresponds to a level range of the reference voltage Vref outputted from the reference voltage supply circuit in the room temperature region.

In the turn-on control of the cell balancing switches for increasing the internal temperature of the voltage detection IC <NUM>, the controller <NUM> may divide the cell balancing switches SW included in the voltage detection IC <NUM> into a plurality of groups, and alternately turn on each cell balancing switch group. For example, the voltage detection IC <NUM> may group <NUM> or <NUM> cell balancing switches SW, and may alternately turn on each cell balancing switch group. For example, the voltage detection IC <NUM> may group odd-numbered cell balancing switches SW and even-numbered cell balancing switches SW into different groups, and may alternately turn on each cell balancing switch group.

In the turn-on control of the cell balancing switches for increasing the internal temperature of the voltage detection IC <NUM>, the controller <NUM> may control a time at which a corresponding cell balancing switch SW is turned on for increasing the temperature to be the same for all the cells. In this case, the influence of the turn-on control of the cell balancing switches SW for temperature rise on the cell balancing may be minimized.

When the reference voltage Vref supplied from the voltage detection circuit <NUM> to the ADC falls within a predetermined range, the controller <NUM> turns off all of the cell balancing switches SW that are turned on to raise the temperature, to stop the temperature increase using the cell balancing switches SW.

<FIG> schematically illustrates a control method of the cell balancing switches of the battery management system of <FIG>. The control method of the cell balancing switches illustrated in <FIG> may be performed by the controller <NUM> of the voltage detection IC <NUM> described with reference to <FIG>.

Referring to <FIG>, the controller <NUM> monitors the reference voltage Vref supplied from the voltage detection circuit <NUM> to the ADC (S300).

The controller <NUM> determines whether the reference voltage Vref is out of a predetermined range (S310).

When the reference voltage Vref is out of the predetermined range, the controller <NUM> determines that the internal temperature of the voltage detection IC <NUM> is included in the low temperature region, and controls at least one cell balancing switch SW to be turned on to increase the internal temperature of the voltage detection IC <NUM> (S320).

In step S320, the controller <NUM> may divide the cell balancing switches SW included in the voltage detection IC <NUM> into a plurality of groups, and may alternately turn on each cell balancing switch group.

In step S320, the controller <NUM> may control a time at which a corresponding cell balancing switch SW is turned on for increasing the temperature to be the same for all the cells.

The controller <NUM> continuously monitors the reference voltage Vref while the internal temperature of the voltage detecting IC <NUM> is being raised through the turn-on control of the cell balancing switches SW (S330). In addition, the controller <NUM> determines whether the reference voltage Vref is within a predetermined range (S340).

When the reference voltage Vref is within the predetermined range, the controller <NUM> determines that the temperature of the voltage detection IC <NUM> reaches a normal range (room temperature region), and controls all the cell balancing switches SW that are turned on for increasing the temperature to be turned off (S350), to stop heat generation of the cell balancing switches SW.

Referring to <FIG>, a battery management system according to the present exemplary embodiment may include a voltage detection IC <NUM> and a battery controller <NUM>. In the following description, detailed descriptions of same or similar components as those of the battery management system described with reference to <FIG> will be omitted.

The voltage detection IC <NUM> may include a plurality of cell balancing switches SW, a voltage detection circuit <NUM>, a temperature sensor <NUM>, an interface <NUM>, and a controller <NUM>.

The temperature sensor <NUM> may detect an internal temperature of the voltage detection IC <NUM>. The reference voltage supply circuit (see reference numeral <NUM> in <FIG>) is sensitive to temperature, and thus acts as a cause of a cell voltage detection error in a low temperature region. Therefore, the temperature sensor <NUM> may be disposed in contact with or adjacent to the reference voltage supply circuit so as to be able to detect an ambient temperature of the reference voltage supply circuit.

The controller <NUM> may turn on at least one cell balancing switch SW to increase the internal temperature of the voltage detection IC <NUM> when the internal temperature detected through the temperature sensor <NUM> is included in the low temperature region. That is, the controller <NUM> may turn on at least one cell balancing switch SW to increase the temperature when the temperature detected through the temperature sensor <NUM> is below a threshold value. Herein, the threshold value is a boundary value for determining the low temperature region, and may be set differently depending on an environment in which the battery management system is mounted.

When a cell balancing switch SW is turned on, a balancing current Ib flows into the internal resistor (see reference numeral Rsw in <FIG>) of the cell balancing switch SW to cause the cell balancing switch SW to generate heat. The heat generation of the cell balancing switch SW may operate as a heat source for increasing the internal temperature of the voltage detection IC <NUM>.

When the internal temperature of the voltage detection IC <NUM> detected through the temperature sensor <NUM> is out of the low temperature range, the controller <NUM> turns off all of the cell balancing switches SW that are turned on to raise the temperature, to stop the temperature increase using the cell balancing switches SW.

As described above, when the internal temperature of the voltage detection IC <NUM> is increased by using the cell balancing switches SW, the internal temperature of the voltage detection IC <NUM> may be rapidly increased within a short time. However, when the internal temperature of the voltage detection IC <NUM> is out of the low temperature range and the cell balancing switches SW are turned off, a situation in which the temperature of the voltage detection IC <NUM> again falls to the low temperature region by the ambient temperature (e.g., cell temperature) of the voltage detection IC <NUM> may occur. In addition, when a turn-on state of the cell balancing switches SW is continuously maintained to prevent this situation, excessive discharge of the cells may adversely affect cell cycle-life and cell balancing.

Therefore, the battery management system may further include a temperature sensor <NUM> for detecting the ambient temperature of the voltage detection IC <NUM>, as illustrated in <FIG>. The voltage detecting IC <NUM> may further include a heat generation circuit <NUM> for maintaining the internal temperature of the voltage detection IC <NUM>.

The temperature sensor <NUM> may be disposed adjacent to the voltage detection IC <NUM> to detect the ambient temperature of the voltage detection IC <NUM>. For example, when a printed circuit board (PCB) including a voltage detection IC <NUM> is attached to the cell group <NUM>, the temperature sensor <NUM> may be attached to the cell group <NUM>. Further, for example, the temperature sensor <NUM> may be used by being attached to a printed circuit board including the voltage detection IC <NUM>.

When the internal temperature of the voltage detection IC <NUM> is out of the low temperature range, and the cell balancing switches SW are turned off, the heat generation circuit <NUM> may be controlled based on the ambient temperature of the voltage detection IC <NUM> detected through the temperature sensor <NUM>.

When the ambient temperature detected through the temperature sensor <NUM> is included in the low temperature range in a state where the internal temperature of the voltage detection IC <NUM> is out of the low temperature range, the controller <NUM> may control the heat generation circuit <NUM> to generate heat in order to prevent the internal temperature of the voltage detection IC <NUM> from being lowered again by the ambient temperature. In addition, the controller <NUM> may control the heat generation circuit <NUM> to stop the heat generation when the ambient temperature detected through the temperature sensor <NUM> is out of the low temperature range.

The heat generation circuit <NUM> may be disposed in contact with or adjacent to a reference voltage supply circuit (refer to reference numeral <NUM> in <FIG>) serving as a cause of a cell voltage detection error in the low temperature region.

The heat generation circuit <NUM> may be implemented in various forms that are capable of generating heat.

For example, as illustrated in <FIG>, the heat generation circuit <NUM> includes a heat generation switch SWheat. The controller <NUM> may control the heat generation of the heat generation circuit <NUM> by controlling turn-on and turn-off of the heat generation switch SWheat.

When the heat generation switch SWheat is turned on, a current flows through internal resistance of the heat generation switch SWheat so as to allow the heat generation switch SWheat to generate heat. The heat generation of the heat generation switch SWheat may operate as a heat source for increasing or maintaining the internal temperature of the voltage detection IC <NUM>.

The heat generation switch SWheat may be connected between a positive terminal of any one of the plurality of cells constituting the cell group <NUM> and a negative terminal of any one of the plurality of cells constituting the cell group <NUM>. For example, referring to <FIG>, the heat generation switch SWheat may be connected between a positive terminal of a highest potential cell and a negative terminal of a lowest potential cell among the cells constituting the cell group <NUM>. However, the present invention is not limited thereto, and a cell of the cell group which is connected with the heat generation switch SWheat is may be changed.

Although a case where the heat generation switch SWheat is connected with the cell group <NUM> through the input resistor Rc is illustrated in <FIG> as an example, the present invention is not limited thereto, and opposite ends of the heat generation switch SWheat may be connected with the cell group <NUM> through a separate resistor (not illustrated). In this case, the resistor connected between the opposite ends of the heat generation switch SWheat and the cell group <NUM> may be disposed inside the voltage detection IC <NUM> to constitute the heat generation circuit <NUM> together with the heat generation switch SWheat.

Referring to <FIG>, the controller <NUM> detects the internal temperature of the voltage detection IC <NUM> through the temperature sensor <NUM> (S500).

The controller <NUM> determines whether the temperature detected through the temperature sensor <NUM> is included in the low temperature region by comparing the temperature detected through the temperature sensor <NUM> with a threshold value (S510).

The controller <NUM> controls at least one cell balancing switch SW to be turned on to increase the internal temperature of the voltage detection IC <NUM> when the temperature detected through the temperature sensor <NUM> is included in the low temperature region (S520).

In step S520, the controller <NUM> may divide the cell balancing switches SW included in the voltage detection IC <NUM> into a plurality of groups, and may alternately turn on each cell balancing switch group.

In step S520, the controller <NUM> may control the number of cell balancing switches SW that are simultaneously turned on to be different depending on the temperature detected through the temperature sensor <NUM>. In this case, the controller <NUM> may control the number of cell balancing switches SW to be simultaneously turned on to increase as the temperature detected through the temperature sensor <NUM> is lower.

In step S520, the controller <NUM> may turn on all the cell balancing switches SW at the same time, and then may control the cell balancing switches SW such that the number of cell balancing switches SW that are turned off gradually increases depending on the temperature rise.

In step S520, the controller <NUM> may control a time at which a corresponding cell balancing switch SW is turned on for increasing the temperature to be the same for all the cells.

The controller <NUM> continuously detects the internal temperature of the voltage detection IC <NUM> through the temperature sensor <NUM> even while raising the internal temperature of the voltage detection IC <NUM> through the turn-on control of the cell balancing switches SW (S530). In addition, the controller <NUM> determines whether the temperature detected through the temperature sensor <NUM> is out of the low temperature range (S540).

When the temperature detected through the temperature sensor <NUM> is out of the low temperature range, the controller <NUM> controls all the cell balancing switches SW that are turned on for increasing the temperature to be turned off (S550), to stop heat generation of the cell balancing switches SW.

In addition, the controller <NUM> detects the ambient temperature of the voltage detection IC <NUM> through the temperature sensor <NUM> (S560). The controller <NUM> determines whether the ambient temperature detected through the temperature sensor <NUM> is included in the low temperature region by comparing the temperature detected through the temperature sensor <NUM> with a threshold value (S570).

When the ambient temperature detected through the temperature sensor <NUM> is included in the low temperature region, the controller <NUM> turns on the heat generation switch SWheat to allow the heat generation circuit <NUM> to generate heat in order to prevent the internal temperature of the voltage detection IC <NUM> from being lowered (S580).

The controller <NUM> continuously detects the ambient temperature of the voltage detection IC <NUM> through the temperature sensor <NUM> even in a state where the heat generation switch SWheat is turned on (S590). In addition, the controller <NUM> determines whether the ambient temperature detected through the temperature sensor <NUM> is out of the low temperature range (S600).

When the ambient temperature detected through the temperature sensor <NUM> is out of the low temperature range, the controller <NUM> controls the cell balancing switches SW that are turned on for maintaining the temperature to be turned off (S6100), to stop heat generation of the heat generation circuit <NUM>.

Although a case where the controller <NUM> controls a heat generation amount of the heat generation circuit <NUM> through a turn-on time of the heat generation switch SWheat is illustrated in <FIG> as an example, the present invention is not limited thereto. The controller <NUM> may control a heat generation amount of the heat generation switch SWheat through PMW control that varies a duty ratio of the heat generation switch SWheat depending on a heat generation amount that is required while the ambient temperature of the voltage detection IC <NUM> stays in the low temperature region. In addition, the controller <NUM> may control the heat generation amount by adjusting a turn-on and turn-off period of the heat generation switch SWheat. In this case, the controller <NUM> may calculates a required heat generation amount based on a difference between the ambient temperature detected through the temperature sensor <NUM> and the internal temperature detected through the temperature sensor <NUM>, and may control the turn-on and turn-off period or the duty ratio of the heat generation switch SWheat.

Although a case where the heat generation switch SWheat is turned on after the cell balancing switches SW are turned off due to an increase in the internal temperature of the detection IC <NUM> is illustrated in <FIG> as an example, the cell balancing switches SW and the heat generation switch SWheat may be simultaneously turned on in order to increase the internal temperature of the voltage detecting IC <NUM>. In this case, even when the internal temperature of the voltage detection IC <NUM> is increased, and thus the cell balancing switches SW are turned off, the heat generation switch SWheat may be maintained in the turn-on state until the ambient temperature is out of the low temperature range.

Although a case where a measuring route of cell voltages of each of the cells of the voltage detection IC <NUM> or <NUM> and a cell balancing route share the input resistor Rc connected with the negative electrode of each cell is described as an example in the aforementioned exemplary embodiments, the present invention is not limited thereto. For example, referring to <FIG>, a voltage detection IC <NUM> may measure cell voltages through input resistors Rc connected with opposite ends of the respective cells, and may perform cell balancing through balancing resistors Rb connected with the opposite ends of the respective cells in addition to the input resistors Rc. The voltage detection IC <NUM> of <FIG> may additionally include terminals Cin for measuring the cell voltages and terminals Bin for the cell balancing, unlike the voltage detection ICs <NUM>, <NUM>, and <NUM> in which the cell balancing route shares one of the terminals Cin for measuring the cell voltages. In <FIG>, a capacitor Cb connected between the balancing terminals Bin is for preventing a malfunction from occurring due to noise such as a ripple voltage during diagnosis of the balancing switches SW.

Although a case where the function of controlling the cell balancing switch SW to raise the internal temperature of the voltage detection ICs <NUM>, <NUM>, and <NUM> is controlled by the controllers <NUM>, <NUM>, and <NUM> included in the voltage detection ICs <NUM>, <NUM>, and <NUM> is described as an example in the aforementioned exemplary embodiments, the present invention is not limited thereto, and the function of controlling the cell balancing switch SW to raise the internal temperature of the voltage detection ICs <NUM>, <NUM>, and <NUM> may be performed by the battery controller <NUM>. In this case, the controller in the voltage detection IC may transfer temperature information of the inside or the periphery of the voltage detection IC or level information of the reference voltage Vref to the battery controller through the interface, and may receive control information of the heat generation switch SWheat or the cell balancing switches SW for increasing the temperature from the battery controller.

These exemplary embodiments provide methods for increasing the internal temperature of the voltage detection IC in the low temperature environment so as to improve the accuracy of the voltage detection IC in the low temperature environment, thereby improving the accuracy of the SOC.

Conventionally, due to the inaccuracy of the SOC calculated by the battery management system, the available capacity of the battery is calculated by providing an internal margin sufficient for the SOC error in order to secure the safety of the battery pack when the battery pack is manufactured. For example, when the available range of the battery is between <NUM> % and <NUM> % of the total capacity of the battery, and the SOC output error is ± <NUM> %, the actual available battery life will be reduced to <NUM> % to <NUM> % of the battery's total capacity. That is, the available battery capacity is <NUM> % of the total capacity of the battery, but due to the SOC error, actual battery usage takes place within <NUM> % of the total capacity of the battery. Therefore, if the SOC error is reduced, the actual capacity of the battery may be increased.

Further, in the exemplary embodiments, the temperature of the voltage detection IC may be increased without any additional cost by using the cell balancing switches to raise the internal temperature of the voltage detection IC in the low temperature environment.

Claim 1:
A voltage detection integrated circuit (<NUM>) comprising:
a voltage detection circuit (<NUM>) electrically connected to a plurality of cells to detect a cell voltage of a corresponding one of the plurality of cells; and
a plurality of cell balancing switches (SW) configured to conduct or block a flow of a balancing current of a corresponding cell among the plurality of cells;
a temperature sensor (<NUM>) configured to detect an internal temperature of the voltage detection integrated circuit (<NUM>);
characterized by
a controller (<NUM>) configured to differently select a number of cell balancing switches (SW) that are simultaneously turned on depending on the internal temperature, and to turn on the selected switches (SW), when the internal temperature is below a first threshold value.