Patent Description:
The present disclosure relates to an apparatus and method for diagnosing a state of a battery, and more particularly, to an apparatus and method for diagnosing a state of a battery, which may determine whether a defect occurs in a battery module.

Among them, the lithium batteries are in the limelight since they have almost no memory effect compared to nickel-based batteries and also have very low self-discharging rate and high energy density.

Meanwhile, if a plurality of batteries are provided in a device, the imbalance of the batteries causes deterioration of the performance of the battery output, so the performance of the devices may be deteriorated. Therefore, in the prior art, in the case where a plurality of batteries are provided, technologies for diagnosing whether a capacity imbalance occurs between the plurality of batteries and solving the problem has been developed.

<CIT> discloses a technique for diagnosing an imbalance of a plurality of battery banks by calculating an impedance change amount of the plurality of battery banks and analyzing a pattern of the calculated impedance change amount. However, according to <CIT>, in order to calculate the impedance change amount of the battery banks, it is necessary to measure a voltage change amount and a current value of the battery banks. In addition, in order to determine whether or not the battery banks are unbalanced, it is essential to analyze the pattern of the impedance change amount. Accordingly, <CIT> has a problem in that it is not possible to quickly diagnose an imbalance of the plurality of battery banks.

Further prior art is described in <CIT> and <CIT>.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing an apparatus and method for diagnosing a state of a battery, which quickly and accurately determines whether a defect occurs in a battery module based on a change rate of an SOC of the battery module.

In one aspect of the present disclosure, there is provided an apparatus for diagnosing a state of a battery, which diagnoses a state of a battery module having at least one battery cell, the apparatus comprising: a charging and discharging unit configured to charge or discharge the battery module; a measuring unit configured to measure a current of the battery module at every predetermined period during a cycle in which the battery module is charged or discharged; and a control unit configured to receive a measurement value for the current of the battery module from the measuring unit, estimate a SOC (State Of Charge) of the battery module during the cycle based on the received measurement value, calculate a change rate of the estimated SOC, and determine whether a defect occurs in the battery module based on a comparison result between the calculated change rate of the SOC and a preset reference change rate.

The control unit is configured to calculate an instant change rate of the estimated SOC, determine a plurality of peaks in the calculated instant change rate, select a peak closest to an intermediate time point of the cycle among the plurality of determined peaks as a target peak, and determine whether a defect occurs in the battery module by comparing the selected target peak with a reference peak of the reference change rate.

The control unit may be configured to calculate an instant change rate of the estimated SOC, and determine whether a defect occurs in the battery module based on a comparison result between the calculated instant change rate and the reference change rate corresponding thereto at the same time point.

The control unit may be configured to determine that a defect occurs in at least one of a plurality of battery cells included in the battery module, when the calculated instant change rate is greater than the reference change rate.

The battery module may be provided in plural.

The control unit may be configured to calculate an instant change rate of the SOC for each of the plurality of battery modules, select a target peak in the instant change rate of each of the plurality of battery modules, and determine a relative degree of defect occurrence of the plurality of battery modules by comparing magnitudes of the plurality of selected target peaks.

The plurality of target peaks may be peaks closest to an intermediate time point of a charging and discharging cycle of corresponding battery modules and be locatable at different time points.

The control unit may be configured to determine that the degree of defect occurrence of the battery module is more serious as a magnitude of the corresponding target peak among the plurality of selected target peaks is greater.

A battery pack according to another aspect of the present disclosure may comprise the apparatus for diagnosing a state of a battery according to an embodiment of the present disclosure.

In another aspect of the present disclosure, there is also provided a method for diagnosing a state of a battery, which diagnoses a state of a battery module having at least one battery cell, the method comprising: a charging and discharging step of charging or discharging the battery module; a measuring step of measuring a current of the battery module at every predetermined period during a cycle in which the battery module is charged or discharged; a SOC estimating step of estimating a SOC of the battery module during the cycle based on the measurement value measured in the measuring step; a SOC change rate calculating step of calculating a change rate of the SOC estimated in the SOC estimating step; and a battery module defect determining step of determining whether a defect occurs in the battery module based on a comparison result between the change rate calculated in the change rate calculating step and a preset reference change rate.

The change rate calculating step includes an instant change rate calculating step of calculating an instant change rate of the SOC for each of the plurality of battery modules.

The defect determining step includes: a target peak selecting step of selecting a target peak in the instant change rate of each of the plurality of battery modules calculated in the change rate calculating step; and a relative defect determining step of determining a relative degree of defect occurrence of the plurality of battery modules by comparing magnitudes of the plurality of selected target peaks.

According to one aspect of the present disclosure, the apparatus for diagnosing a state of a battery has an advantage of accurately diagnosing whether a defect occurs in the battery module just by comparing SOC change rates based on the capacity characteristics of the battery module.

In addition, according to one aspect of the present disclosure, the apparatus for diagnosing a state of a battery has an advantage of quickly diagnosing whether a defect occurs in the battery module by calculating the SOC change rate while the battery module is charged or discharged.

In addition, according to one aspect of the present disclosure, the apparatus for diagnosing a state of a battery has an advantage of determining whether a defect occurs in the battery module using a relatively simple circuit configuration and minimizing the physical space required for the apparatus for diagnosing a state of a battery.

The effects of the present disclosure are not limited to the above, and other effects not mentioned herein will be clearly understood by those skilled in the art from the appended claims.

Furthermore, the term "control unit" described in the specification refers to a unit that processes at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

Hereinafter, a preferred embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

<FIG> is a diagram schematically showing an apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure.

Referring to <FIG>, the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure may include a charging and discharging unit <NUM>, a measuring unit <NUM>, and a control unit <NUM>.

The apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure may diagnose a state of a battery module <NUM> having at least one battery cell.

Here, the battery module <NUM> may include at least one battery cell. If the battery module <NUM> includes a plurality of battery cells, the plurality of battery cells may be connected in series and/or in parallel. Preferably, the plurality of battery cells included in the battery module <NUM> may be connected in parallel with each other. In addition, the battery cell refers to one independent cell that has a negative electrode terminal and a positive electrode terminal and is physically separable. For example, one pouch-type lithium polymer cell may be regarded as the battery cell.

<FIG> is a diagram schematically showing a battery pack <NUM> that includes the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure. <FIG> is a diagram showing an exemplary configuration of the battery pack <NUM> that includes the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure.

Referring to <FIG> and <FIG>, the battery module <NUM> may be connected to the battery pack <NUM>. That is, the positive electrode of the battery module <NUM> may be electrically connected to a positive electrode terminal P+ of the battery pack <NUM>. In addition, the negative electrode of the battery module <NUM> may be electrically connected to a negative electrode terminal P- of the battery pack <NUM>.

For example, in the embodiment of <FIG>, the battery pack <NUM> may include one battery module <NUM>, and the battery module <NUM> may include a first battery cell B1, a second battery cell B2, a third battery cell B3 and a fourth battery cell B4 connected in parallel.

If the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure is included in the battery pack <NUM>, the apparatus <NUM> for diagnosing a state of a battery may be connected to the battery module <NUM> included in the battery pack <NUM> and a main charging and discharging path of the battery pack <NUM>. Here, the main charging and discharging path is a path that connects the positive electrode terminal P+ of the battery pack <NUM>, the battery module <NUM> and the negative electrode terminal P- of the battery pack <NUM>, and refers to a high current path through which a current flows in the battery pack <NUM>.

The charging and discharging unit <NUM> may be configured to charge or discharge the battery module <NUM>.

The charging and discharging unit <NUM> may be connected to the control unit <NUM> to receive a charging command signal or a discharging command signal from the control unit <NUM>. In addition, the charging and discharging unit <NUM> may be operated to correspond to the charging command signal or the discharging command signal received from the control unit <NUM>. Here, the charging command signal is a signal for charging the battery module <NUM>, and the discharging command signal is a signal for discharging the battery module <NUM>.

For example, if the charging and discharging unit <NUM> receives the charging command signal from the control unit <NUM>, the charging and discharging unit <NUM> may output a current to the main charging and discharging path. The current output from the charging and discharging unit <NUM> may flow through the main charging and discharging path to charge the battery module <NUM>. Specifically, the current output from the charging and discharging unit <NUM> may charge at least one battery cell provided in the battery module <NUM>.

As another example, if the charging and discharging unit <NUM> receives the discharging command signal from the control unit <NUM>, the charging and discharging unit <NUM> may be charged by receiving a current from the battery module <NUM> through the main charging and discharging path.

In the embodiment of <FIG>, one end of the charging and discharging unit <NUM> may be connected between the positive electrode terminal P+ of the battery pack <NUM> and the positive electrode of the battery module <NUM>. In addition, the other end of the charging and discharging unit <NUM> may be connected between the negative electrode terminal P- of the battery pack <NUM> and the negative electrode of the battery module <NUM>. Therefore, if the charging and discharging unit <NUM> receives a charging command signal from the control unit <NUM>, the current output from the charging and discharging unit <NUM> may flow through the main charging and discharging path to charge the battery module <NUM>.

However, even though the embodiment of <FIG> illustrates an example where both ends of the charging and discharging unit <NUM> are directly connected to the main charging and discharging path, it is also possible that one end of the charging and discharging unit <NUM> is connected to the positive electrode terminal P+ of the battery pack <NUM> and the other end of the charging and discharging unit <NUM> is connected to the negative electrode terminal P- of the battery pack <NUM>, unlike <FIG>. That is, both ends of the charging and discharging unit <NUM> may be connected to the electrodes of the battery pack <NUM> to charge or discharge the battery module <NUM>.

The measuring unit <NUM> may be configured to measure a current of the battery module <NUM> at every predetermined period during a cycle in which the battery module <NUM> is charged or discharged.

For example, in the embodiment of <FIG>, an ampere meter A and/or a sense resistor for measuring the current of the battery module <NUM> may be further disposed on the main charging and discharging path. Hereinafter, for convenience of explanation, it will be described that the ampere meter A is disposed on the main charging and discharging path. In addition, the measuring unit <NUM> may be connected to the ampere meter A through a sensing line SL to measure the current flowing through the main charging and discharging path.

If the sense resistor is disposed on the main charging and discharging path, the measuring unit <NUM> may calculate a drop voltage dropped by the sense resistor by measuring the voltage at both ends of the sense resistor. In addition, the measuring unit <NUM> may measure the current flowing through the main charging and discharging path based on a known resistance of the sense resistor and the calculated drop voltage.

The control unit <NUM> may be configured to receive a measurement value for the current of the battery module <NUM> from the measuring unit <NUM>.

Specifically, the control unit <NUM> and the measuring unit <NUM> may be connected by wire and/or wirelessly. In addition, the measuring unit <NUM> may convert the measurement value of the measured current of the battery module <NUM> into a digital signal and output the converted signal to the control unit <NUM>. The control unit <NUM> may obtain a current value of the battery module <NUM> by reading the digital signal received from the measuring unit <NUM>.

For example, in the embodiment of <FIG>, the control unit <NUM> and the measuring unit <NUM> may be connected to each other through a wired line. In addition, the measuring unit <NUM> may convert the measured current value of the battery module <NUM> into a digital signal, and output the converted digital signal through the wired line.

The control unit <NUM> may be configured to estimate a SOC (State of charge) of the battery module <NUM> during the cycle based on the received measurement value.

For example, the control unit <NUM> may estimate the SOC of the battery module <NUM> by counting the current value of the battery module <NUM> measured by the measuring unit <NUM> during the cycle. That is, the control unit <NUM> may estimate the SOC of battery module <NUM> using an ampere counting method.

In addition, the control unit <NUM> may be configured to calculate a change rate of the estimated SOC.

Here, the change rate of the SOC is a change rate of the SOC of the battery module <NUM> during the cycle, and may include, for example, a total change rate of the SOC during the cycle or an instant change rate of the SOC calculated at every predetermined period.

For example, it is assumed that a charging cycle during which battery module <NUM> is charged has progressed from <NUM> second to <NUM>,<NUM> seconds. The control unit <NUM> may calculate the change rate of the SOC of battery module <NUM> while the change rate of the SOC is changed from <NUM> second to <NUM>,<NUM> seconds. In addition, the control unit <NUM> may calculate the change rate of the SOC as an instant change rate of the SOC at every predetermined period from <NUM> second to <NUM>,<NUM> seconds. Here, the predetermined period may be preferably the same as a period during which the measuring unit <NUM> measures the current of the battery module <NUM>.

The control unit <NUM> may be configured to determine whether a defect occurs in the battery module <NUM> based on a comparison result between the calculated change rate of the SOC and a preset reference change rate.

Specifically, the control unit <NUM> may determine whether a defect occurs in the battery module <NUM> by comparing the change rate of the SOC calculated for the battery module <NUM> with the preset reference change rate.

For example, in the embodiment of <FIG>, it is assumed that both of a reference module Ref and the battery module <NUM> have four battery cells connected in parallel. It is assumed that the reference module Ref has battery cells in a BOL (Beginning Of Life) state, and the battery module <NUM> has battery cells in an EOL (End Of Life) state. Since the SOH (State Of Health) of the battery cell is reduced as the battery cell is degraded, the BOL battery cell and the EOL battery cell may have different SOC even though the same amount of current is applied thereto. Therefore, during the same charging cycle, the change rate of the SOC of the reference module Ref and the change rate of the SOC of the battery module <NUM> may be different. Preferably, the change rate of the SOC of the battery module <NUM> may be greater than the change rate of the SOC of the reference module Ref during the cycle.

In addition, even when the battery module <NUM> and the reference module Ref include different numbers of battery cells, the change rate of the SOC of the battery module <NUM> and the reference change rate may be different from each other. For example, in the embodiment of <FIG>, it is assumed that four battery cells are normally connected in parallel in the reference module Ref, but the connection of the fourth battery cell among the four battery cells include in the battery module <NUM> is disconnected. Even in this case, the SOH of the reference module Ref may be greater than the SOH of the battery module <NUM>. Therefore, if the same amount of current is applied to the reference module Ref and the battery module <NUM>, the SOC of the battery module <NUM> may increase rapidly compared to the SOC of the reference module Ref..

Therefore, the control unit <NUM> may determine whether a defect occurs in the battery module <NUM> by comparing the change rate of the SOC of the battery module <NUM> with the reference change rate. Specifically, the control unit <NUM> may determine whether the battery module <NUM> is degraded or whether a connection failure or the like occurs in a battery cell included in the battery module <NUM>.

When determining whether a defect occurs in the battery module <NUM> having a plurality of battery cells B1, B2 and B3, the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure may determine whether the battery module <NUM> has a defect based on the change rate of the SOC of the battery module <NUM>, even though a state of each of the plurality of battery cells B <NUM>, B2 and B3 is not individually diagnosed. Therefore, the circuit configuration for determining whether a defect occurs in the battery module <NUM> is relatively simple, and there is an advantage of minimizing the physical space required for the apparatus <NUM> for diagnosing a state of a battery.

In addition, since the apparatus <NUM> for diagnosing a state of a battery determines a defective state of the battery module <NUM> in consideration of the SOC of the battery module <NUM> itself, even though the plurality of battery cells B <NUM>, B2 and B3 included in the battery module <NUM> are connected in parallel, there is an advantage in that it is not required to diagnose each battery cell individually, when determining whether a defect occurs in the battery module <NUM>.

Meanwhile, the control unit <NUM> included in the apparatus <NUM> for diagnosing a state of a battery may optionally include a processor, an application-specific integrated circuit (ASIC), another chipset, a logic circuit, a register, a communication modem, and a data processing device, and the like, known in the art to execute various control logics disclosed below. In addition, when the control logic is implemented in software, the control unit <NUM> may be implemented as a set of program modules. At this time, the program module may be stored in a memory and executed by the processor. The memory may be provided in or out of the control unit <NUM>, and may be connected to the control unit <NUM> by various well-known means.

In addition, referring to <FIG>, the apparatus <NUM> for diagnosing a state of a battery may further include a storage unit <NUM>. The storage unit <NUM> may store programs, data and the like required for the control unit <NUM> to determine whether a defect occurs at the battery module <NUM> and determine the degree of defect. That is, the storage unit <NUM> may store data necessary for operation and function of each component of the apparatus <NUM> for diagnosing a state of a battery, data generated in the process of performing the operation or function, or the like. The storage unit <NUM> is not particularly limited in its kind as long as it is a known information storage means that can record, erase, update and read data. As an example, the information storage means may include RAM, flash memory, ROM, EEPROM, registers, and the like. In addition, the storage unit <NUM> may store program codes in which processes executable by the control unit <NUM> are defined.

Preferably, the control unit <NUM> may be configured to calculate an instant change rate of the estimated SOC. Hereinafter, an example in which the control unit <NUM> calculates the instant change rate of the SOC will be described in detail with reference to <FIG>.

<FIG> is a diagram showing a SOC and a SOC change rate of a reference module Ref and a battery module <NUM>, in the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure.

Specifically, <FIG> is a diagram showing a SOC estimated by the control unit <NUM> and a calculated change rate of the SOC during a charging cycle of the reference module Ref and the battery module <NUM> charged at the same charging C-rate for the same time. More specifically, the battery module <NUM> is a module including one less battery cell compared to the reference module Ref. In addition, the reference module and the battery module <NUM> are charged by receiving a charging current of <NUM> C (C-rate) from the charging and discharging unit <NUM> for the same time.

Referring to <FIG>, during the same charging time, the SOC of the reference module Ref and the SOC of the battery module <NUM> are shown. In addition, the instant change rate of the SOC of the reference module Ref and the instant change rate of the SOC of the battery module <NUM> are shown.

Here, the instant change rate is a change rate obtained by applying a limit to an average change rate of the SOC, and may mean, for example, a slope of a tangent of the SOC shown in <FIG>.

In an embodiment, the control unit <NUM> may estimate the SOC of the battery module <NUM> by counting the current value of the battery module <NUM> measured by the measuring unit <NUM> while the battery module <NUM> is charged or discharged. In addition, the control unit <NUM> may calculate the instant change rate of the SOC of the battery module <NUM> simultaneously with estimating the SOC of the battery module <NUM>.

For example, it is assumed that the measuring unit <NUM> measures the current of the battery module <NUM> with the period of <NUM> seconds, and the control unit <NUM> estimates the SOC of the battery module <NUM> with the period of <NUM> seconds. The control unit <NUM> may calculate the instant change rate of the SOC of the battery module <NUM> at the time point of <NUM> seconds while estimating the SOC of the battery module <NUM> at the time point of <NUM>,<NUM> seconds. That is, since the instant change rate is a limit value of the average change rate (the slope of the tangent of the SOC), the control unit <NUM> may estimate the SOC of the battery module <NUM> and calculate the instant change rate of the SOC together to quickly determine a defect.

In another embodiment, the control unit <NUM> may store the SOC in the storage unit <NUM> whenever estimating the SOC of the battery module <NUM>. That is, in the charging cycle of the battery module <NUM>, the storage unit <NUM> may store a plurality of SOCs estimated at every predetermined period. In addition, the control unit <NUM> may calculate an instant change rate of the SOC corresponding to the predetermined period with respect to the plurality of SOCs stored in the storage unit <NUM>.

In addition, the control unit <NUM> may be configured to determine whether a defect occurs in the battery module <NUM> by comparing the calculated instant change rate and a reference change rate corresponding thereto at the same time point.

Here, the reference change rate may be an instant change rate of the SOC of the reference module Ref. The reference change rate may be stored in the storage unit <NUM> in advance.

The control unit <NUM> may determine whether a defect occurs in the battery module <NUM> by comparing the magnitudes of the instant change rates for the battery module <NUM> and the reference module Ref at the same time point.

For example, in the embodiment of <FIG>, the control unit <NUM> may calculate the change rate of the SOC of the battery module <NUM>, and then compare the change rate of the SOC of the battery module <NUM> and the change rate of the SOC of the reference module Ref at one or more time points during the charging cycle.

Preferably, the control unit <NUM> may select at least one time point after a predetermined time passes from the time point at which the cycle starts.

For example, the control unit <NUM> may select a time point at which <NUM>,<NUM> seconds passes from a time point (<NUM> second) at which the cycle starts. In addition, the control unit <NUM> may determine whether a defect occurs in the battery module <NUM> by comparing the change rate of the SOC of the reference module Ref and the change rate of the SOC of the battery module <NUM> at the selected time point (<NUM>,<NUM> seconds).

As another example, the control unit <NUM> may select all time points at which <NUM>,<NUM> seconds, <NUM>,<NUM> seconds, <NUM>,<NUM> seconds, <NUM>,<NUM> seconds and <NUM>,<NUM> seconds pass from the time point (<NUM> second) at which the cycle starts. In addition, the control unit <NUM> may determine whether a defect occurs in the battery module <NUM> by comparing the change rate of the SOC of the reference module Ref and the change rate of the SOC of the battery module <NUM> at the plurality of selected time points (<NUM>,<NUM> seconds, <NUM>,<NUM> seconds, <NUM>,<NUM> seconds, <NUM>,<NUM> seconds and <NUM>,<NUM> seconds). That is, if the control unit <NUM> determines whether a defect occurs in the battery module <NUM> based only on the change rate of the SOC at any one time point, it may be erroneously determined whether a defect occurs in the battery module <NUM> due to a measurement error of the measuring unit <NUM> or a SOC estimation error of the control unit <NUM>. Accordingly, the control unit <NUM> may more accurately determine whether a defect occurs in the battery module <NUM> by selecting a plurality of time points and comparing the change rate of the SOC at the plurality of selected time points.

The apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure has an advantage of accurately and quickly diagnosing whether a defect occurs in the battery module <NUM> just by comparing the instant change rate of the SOC based on the capacity characteristics of the battery module <NUM> having battery cells.

The control unit <NUM> may be configured to determine that a defect occurs in at least one of the plurality of battery cells B <NUM>, B2 and B3 included in the battery module <NUM>, if the calculated instant change rate is greater than the reference change rate.

That is, as described above, if a defect occurs in at least one of the plurality of battery cells B <NUM>, B2 and B3 included in the battery module <NUM>, the SOH of the battery module <NUM> may be reduced. This means that even if the same amount of current is applied, the SOC of the battery module <NUM> with a reduced SOH may increase rapidly compared to the reference module Ref..

Therefore, if the calculated instant change rate is greater than the reference change rate, the control unit <NUM> may determine that a defect occurs in the battery module <NUM>.

Conversely, if the calculated instant change rate is less than the reference change rate, the control unit <NUM> may be configured to determine that a defect does not occur in all of the plurality of battery cells B <NUM>, B2 and B3 included in the battery module <NUM>.

For example, in the embodiment of <FIG>, the battery module <NUM> is a module having one less battery cell compared to the reference module Ref. Accordingly, as shown in <FIG>, the instant change rate of the SOC of the battery module <NUM> may be greater than the instant change rate of the SOC of the reference module Ref. Accordingly, the control unit <NUM> may determine that a defect occurs in the battery module <NUM> according to the comparison result of the instant change rate of the SOC between the battery module <NUM> and the reference module Ref..

The control unit <NUM> may be configured to determine a plurality of peaks at the calculated instant change rate.

Specifically, the control unit <NUM> may determine a point at which the change rate increases and then decreases in the change rate of the SOC of the reference module Ref and the calculated change rate of the SOC of the battery module <NUM> as the peak.

For example, in the embodiment of <FIG>, the control unit <NUM> may determine P1, P2 and P3 as peaks in the change rate of the SOC of the battery module <NUM>, and determine Prefl and Pref2 as peaks in the change rate of the SOC of the reference module Ref..

In addition, the control unit <NUM> may be configured to select a peak closest to an intermediate time point of the charging and discharging cycle among the plurality of determined peaks as a target peak.

For example, in the embodiment of <FIG>, the control unit <NUM> may select P2 as a target peak for the battery module <NUM> and select Prefl as a target peak for the reference module Ref..

Specifically, the battery cell has a characteristic that a chemical action occurs therein during the charging or discharging process, and according to this characteristic, the SOC of the battery cell may be affected by the change of the internal resistance of the battery cell. That is, the SOC of the battery cell has a one-to-one relationship with an OCV (Open Circuit Voltage) of the battery cell, and the OCV of the battery cell is inversely proportional to the internal resistance of the battery cell. Therefore, in order to determine whether a defect occurs in the battery module <NUM> based on the SOC change rate of the battery module <NUM>, the control unit <NUM> may select a peak that responds most sensitively to the change of the internal resistance of the battery cell as a target peak among the plurality of selected peaks. In addition, the target peak may be a peak closest to the intermediate time point of the charging and discharging cycle.

That is, since the target peak selected by the control unit <NUM> is a peak most sensitive to the change of the resistance of the battery cell, considering the characteristics of the battery cell as described above, the target peak is a peak that may be used for most accurate comparison to determine whether a defect occurs in the battery cell based on the change rate of the SOC. Therefore, in order to determine whether a defect occurs in the battery module <NUM> by comparison between the change rate of the SOC of the battery module <NUM> and the reference change rate, the control unit <NUM> may select a peak closest to the intermediate time point of the charging and discharging cycle as a target peak.

The control unit <NUM> may be configured to determine whether a defect occurs in the battery module <NUM> by comparing the selected target peak with a reference peak of the reference change rate.

For example, in the embodiment of <FIG>, the control unit <NUM> may determine whether a defect occurs in the battery module <NUM> by comparing the magnitudes of P2 and Prefl. Referring to <FIG>, since P2 is greater than Prefl, the control unit <NUM> may determine that a defect occurs in the battery module <NUM>.

The apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure may diagnose whether a defect occurs in the battery module <NUM> more accurately with high reliability by comparing the magnitude of the selected target peak in consideration of the characteristics of the battery cell.

In addition, since the apparatus <NUM> for diagnosing a state of a battery may determine whether a defect occurs in the battery module <NUM> by not only comparing the change rate of the SOC of battery module <NUM> and the reference change rate at the same time point but also comparing the magnitude of the target peak, there is an advantage that it may be determined whether a defect occurs in the battery module <NUM> in various aspects.

<FIG> is a diagram showing an exemplary configuration of another battery pack <NUM> that includes the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure.

Referring to <FIG>, the battery pack <NUM> may include a plurality of the battery modules <NUM>.

For example, as shown in <FIG>, a first battery module 10a and a second battery module 10b may be included in the battery pack <NUM>. Here, the first battery module 10a and the second battery module 10b may be connected in parallel with each other.

In addition, a first ampere meter A1 for measuring a current of the first battery module 10a may be disposed at one end of the first battery module 10a. In addition, a second ampere meter A2 for measuring a current of the second battery module 10b may be disposed at one end of the second battery module 10b.

In addition, the measuring unit <NUM> may be connected to the first ampere meter A1 through a first sensing line SL1 to measure the current of the first battery module 10a. Also, the measuring unit <NUM> may be connected to the second ampere meter A2 through a second sensing line SL2 to measure the current of the second battery module 10b.

The control unit <NUM> may be configured to calculate an instant change rate of the SOC for each of the plurality of battery modules 10a, 10b.

For example, in the embodiment of <FIG>, the control unit <NUM> may estimate a SOC of the first battery module 10a based on the current value of the first battery module 10a measured by the measuring unit <NUM>. In addition, the control unit <NUM> may calculate an instant change rate of the SOC of the first battery module 10a based on the estimated SOC of the first battery module 10a.

In addition, the control unit <NUM> may estimate a SOC of the second battery module 10b based on the current value of the second battery module 10b measured by the measuring unit <NUM>. In addition, the control unit <NUM> may calculate an instant change rate of the SOC of the second battery module 10b based on the estimated SOC of the second battery module 10b.

<FIG> is a diagram showing a SOC and a SOC change rate of a reference module Ref, a first battery module 10a and a second battery module 10b, in the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure. <FIG> is a diagram showing a target peak selected for each of a plurality of battery modules 10a, 10b in <FIG>.

Specifically, the first battery module 10a is a module having one less battery cell compared to the reference module Ref, and the second battery module 10b is a module having two less battery cells compared to the reference module Ref. In addition, the reference module, the first battery module 10a and the second battery module 10b are charged by receiving a charging current of <NUM> C (C-rate) from the charging and discharging unit <NUM> for the same time.

Referring to <FIG>, the control unit <NUM> may estimate the SOC of the reference module Ref, the first battery module 10a and the second battery module 10b at the same time point, and calculate the instant change rate of the SOC. Here, the instant change rate of the SOC of the reference module Ref may be a reference change rate. In addition, the SOC of the reference module Ref and the instant change rate of the SOC may be stored in the storage unit <NUM> in advance. In this case, the control unit <NUM> may obtain the SOC of the reference module Ref and the instant change rate of the SOC by referring to the storage unit <NUM>.

In addition, the control unit <NUM> may be configured to select a target peak in the instant change rate of each of the plurality of battery modules 10a, 10b.

First, the control unit <NUM> may determine a plurality of peaks in each of the instant change rates of the reference module Ref and the plurality of battery modules 10a, 10b.

For example, in the embodiment of <FIG>, the control unit <NUM> may determine Prefl and Pref2 as peaks in the instant change rate of the SOC of the reference module Ref. In addition, the control unit <NUM> may determine P11, P12 and P13 as peaks in the instant change rate of the SOC of the first battery module 10a. Finally, the control unit <NUM> may determine P21, P22, P23 and P24 as peaks in the instant change rate of the SOC of the second battery module 10b.

In addition, the control unit <NUM> may select a target peak for each of the reference module Ref, the first battery module 10a and the second battery module 10b among the plurality of determined peaks.

As described above, the target peak may be selected as a peak closest to the intermediate time point of the cycle.

For example, in the embodiment of <FIG>, the control unit <NUM> may select Prefl as a target peak for the reference module Ref, select P12 as a target peak for the first battery cell B1, and select P23 as a target peak for the second battery cell B2. The target peaks selected by the control unit <NUM> for the reference module Ref, the first battery module 10a and the second battery module 10b are as shown in <FIG>.

In addition, the control unit <NUM> may be configured to determine a relative degree of defect occurrence of the plurality of battery modules 10a, 10b by comparing the magnitudes of the plurality of selected target peaks.

Specifically, the control unit <NUM> may compare the magnitudes of the plurality of target peaks, and determine that the degree of defect occurrence of the corresponding battery module <NUM> is relatively greater than that of other battery modules <NUM> as the magnitude of the corresponding target peak is greater.

For example, in the embodiment of <FIG>, the control unit <NUM> may compare the magnitudes of Prefl, P12 and P23. It is assumed that the magnitude of Prefl is about <NUM>, the magnitude of P12 is about <NUM>, and the magnitude of P23 is about <NUM>. Since the magnitude of P23 is greater than the magnitudes of Prefl and P12, the control unit <NUM> may determine that the degree of defect occurrence of the second battery module 10b is greater than that of the first battery module 10a and the reference module Ref. In addition, since the magnitude of P12 is greater than the magnitude of Prefl, the control unit <NUM> may determine that the degree of defect occurrence of the first battery module 10a is greater than that of the reference module Ref..

In the above, the control unit <NUM> determines the relative degree of defect occurrence among the reference module Ref, the first battery module 10a and the second battery module 10b by comparing the magnitudes of the target peaks among the reference module Ref, the first battery module 10a and the second battery module 10b. However, the control unit <NUM> may determine the relative degree of defect occurrence just between the plurality of battery modules 10a, 10b included in the battery pack <NUM>, excluding the reference module Ref..

The apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure has an advantage of quickly and easily determining the relative degree of defect occurrence between the plurality of battery modules 10a, 10b by comparing the target peaks sensitive to the resistance change of the battery module <NUM>, even if there is no process of estimating the internal resistance or SOH of each of the plurality of battery modules 10a, 10b.

That is, the apparatus <NUM> for diagnosing a state of a battery has an advantage of quickly determining the relative degree of defect occurrence between the plurality of battery modules 10a, 10b based on the SOC change rate that may be calculated during one charging process of the plurality of battery modules 10a, 10b.

The plurality of target peaks are peaks closest to the intermediate time point of the charging and discharging cycle of the corresponding battery module <NUM>, and may be located at different time points.

For example, in the embodiment of <FIG>, the target peak for the reference module Ref is Prefl, the target peak for the first battery module 10a is P12, and the target peak for the second battery module 10b is P23. That is, since the target peak is a peak most sensitive to the change of resistance of the battery module <NUM>, the time points at which the peaks appear may be different.

However, even if the degrees of defect of the plurality of battery modules 10a, 10b are different from each other, the target peaks of the plurality of battery modules 10a, 10b may be peaks closest to the intermediate time point of the charging cycle or the discharging cycle.

Therefore, the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure has an advantage of easily selecting a target peak at the change rate of the SOC in consideration of the above characteristics of the target peak. In other words, the apparatus <NUM> for diagnosing a state of a battery has an advantage of easily and quickly selecting a target peak by using only the SOC change rate, even if the voltage-charging amount curve (Q-dV/dQ curve) for the battery module <NUM> is not obtained. As a result, since the target peak may be selected quickly, the degree of defect occurrence between the plurality of battery modules 10a, 10b may be quickly and accurately compared.

The apparatus <NUM> for diagnosing a state of a battery according to the present disclosure may be applied to a BMS (Battery Management System). That is, the BMS according to the present disclosure may include the apparatus <NUM> for diagnosing a state of a battery described above. In this configuration, at least some of the components of the apparatus <NUM> for diagnosing a state of a battery may be implemented by supplementing or adding functions of components included in a conventional BMS. For example, the charging and discharging unit <NUM>, the measuring unit <NUM>, the control unit <NUM> and the storage unit <NUM> of the apparatus <NUM> for diagnosing a state of a battery may be implemented as components of the BMS.

In addition, the apparatus <NUM> for diagnosing a state of a battery according to the present disclosure may be provided to a battery pack <NUM>. For example, referring to <FIG> and <FIG>, the battery pack <NUM> may include the apparatus <NUM> for diagnosing a state of a battery according to an embodiment of the present disclosure, and the battery module <NUM> having at least one battery cell. In addition, the battery pack <NUM> may further include electrical equipment (a relay, a fuse, etc.), a case, and the like.

<FIG> is a diagram schematically showing a method for diagnosing a state of a battery according to another embodiment of the present disclosure.

The method for diagnosing a state of a battery according to another embodiment of the present disclosure is a method for diagnosing a state of the battery module <NUM> having at least one battery cell, and may be performed by the apparatus <NUM> for diagnosing a state of a battery.

Referring to <FIG>, the method for diagnosing a state of a battery according to another embodiment of the present disclosure may include a charging and discharging step (S100), a measuring step (S200), a SOC estimating step (S300), a SOC change rate calculating step (S400) and a battery module defect determining step (S500).

The charging and discharging step (S100) is a step of charging or discharging the battery module <NUM>, and may be performed by the charging and discharging unit <NUM>.

For example, the charging and discharging unit <NUM> may receive a charging command signal or a discharging command signal from the control unit <NUM>. If receiving the charging command signal, the charging and discharging unit <NUM> may output a current to the main charging and discharging path of the battery pack <NUM> to charge the battery module <NUM>. Conversely, when receiving the discharging command signal, the charging and discharging unit <NUM> may be charged by receiving a current from the battery module <NUM>.

The measuring step (S200) is a step of measuring the current of the battery module <NUM> at every predetermined period during a cycle in which the battery module <NUM> is charged or discharged, and may be performed by the measuring unit <NUM>.

For example, in the embodiment of <FIG>, the measuring unit <NUM> may measure the current of the battery module <NUM> using the ampere meter A connected through the sensing line SL while the battery module <NUM> is charged.

The SOC estimating step (S300) is a step of estimating the SOC of the battery module <NUM> during the cycle based on the measurement value measured in the measuring step (S200), and may be performed by the control unit <NUM>.

For example, the control unit <NUM> may estimate the SOC of the battery module <NUM> at every predetermined period in which the measuring unit <NUM> measures the current of the battery module <NUM>. For example, if the measuring unit <NUM> measures the current of the battery module <NUM> at every <NUM> seconds, the control unit <NUM> may estimate the SOC of the battery module <NUM> at every <NUM> seconds when the measuring unit <NUM> measures the current of the battery module <NUM>. Here, the control unit <NUM> may estimate the SOC of the battery module <NUM> by accumulatively counting the current values measured by the measuring unit <NUM>.

The SOC change rate calculating step (S400) is a step of calculating the change rate of the SOC estimated in the SOC estimating step (S300), and may be performed by the control unit <NUM>.

The control unit <NUM> may calculate the change rate of the SOC of the battery module <NUM> estimated during the cycle. Preferably, the control unit <NUM> may calculate the change rate of the SOC of the battery module <NUM> at every predetermined period.

For example, as in the former embodiment, the control unit <NUM> may estimate the SOC of the battery module <NUM> at every <NUM> seconds, and calculate the change rate of the SOC of the battery module <NUM> at every <NUM> seconds.

The battery module defect determining step (S500) is a step of determining whether a defect occurs in the battery module <NUM> based on the comparison result between the change rate calculated in the SOC change rate calculating step (S400) and a preset reference change rate, and may be performed by the control unit <NUM>.

That is, the control unit <NUM> may quickly and accurately determine whether a defect occurs in the battery module <NUM> by comparing the magnitudes of the calculated change rate and the reference change rate. Preferably, the control unit <NUM> may determine whether a defect occurs in the battery module <NUM> by comparing the magnitudes of the change rate calculated at the same time point and the reference change rate.

As in the embodiment of <FIG>, the battery module <NUM> may be provided in plural.

In this case, the SOC change rate calculating step (S400) may include an instant SOC change rate calculating step (S400).

The instant SOC change rate calculating step (S400) is a step of calculating an instant change rate of the SOC for each of the plurality of battery modules 10a, 10b, and may be performed by the control unit <NUM>.

That is, the control unit <NUM> may estimate the SOC of each of the plurality of battery modules 10a, 10b, and calculate an instant change rate of the SOC for each of the plurality of battery modules 10a, 10b.

In order to more quickly calculate the change rate of the SOC, the control unit <NUM> may calculate the change rate of the SOC of a previous period simultaneously with estimating the SOC of the battery module <NUM> at the current time point.

In addition, the battery module defect determining step (S500) may further include a target peak selecting step and a relative battery module defect determining step (S500).

The target peak selecting step is a step of selecting a target peak in the instant change rate of each of the plurality of battery modules 10a, 10b calculated in the SOC change rate calculating step (S400), and may be performed by the control unit <NUM>.

For example, as shown in <FIG>, the control unit <NUM> may determine a plurality of peaks for each of the plurality of battery modules 10a, 10b. Here, the peak may be a point at which the SOC change rate increases and then decreases. In addition, as shown in <FIG>, the control unit <NUM> may select a target peak among the plurality of determined peaks.

The relative battery module defect determining step (S500) is a step of determining a relative degree of defect occurrence of the plurality of battery modules 10a, 10b by comparing the magnitudes of the plurality of selected target peaks, and may be performed by the control unit <NUM>.

That is, the control unit <NUM> may quickly determine the relative degree of defect occurrence of the plurality of battery modules 10a, 10b by comparing the magnitudes of the target peaks.

The embodiments of the present disclosure described above are not necessarily implemented by an apparatus and method but may also be implemented through a program for realizing functions corresponding to the configuration of the present disclosure or a recording medium on which the program is recorded. Such implementation may be easily performed by those skilled in the art from the above description of the embodiments.

Claim 1:
An apparatus (<NUM>) for diagnosing a state of a battery, which diagnoses a state of a battery module (<NUM>) having at least one battery cell (B1; B2; B3), the apparatus (<NUM>) comprising:
a charging and discharging unit (<NUM>) configured to charge or discharge the battery module (<NUM>);
a measuring unit (<NUM>) configured to measure a current of the battery module (<NUM>) at every predetermined period during a cycle in which the battery module (<NUM>) is charged or discharged; and
a control unit (<NUM>) configured to receive a measurement value for the current of the battery module (<NUM>) from the measuring unit (<NUM>), estimate a SOC, State of Charge, of the battery module (<NUM>) during the cycle based on the received measurement value, calculate a change rate of the estimated SOC, and determine whether a defect occurs in the battery module (<NUM>) based on a comparison result between the calculated change rate of the SOC and a preset reference change rate,
characterized in that the control unit (<NUM>) is configured to calculate an instant change rate of the estimated SOC, determine a plurality of peaks (P1; P2; P3) in the calculated instant change rate, select a peak closest to an intermediate time point of the cycle among the plurality of determined peaks (P1; P2; P3) as a target peak (Prefl), and determine whether a defect occurs in the battery module (<NUM>) by comparing the selected target peak with a reference peak (Prefl) of the reference change rate.