Patent Description:
Recently, research and development on secondary batteries have been actively conducted. Here, the secondary batteries, as batteries that can be charged and discharged, mean that they include conventional Ni/Cd batteries and Ni/MH batteries, and recent lithium ion batteries. Among the secondary batteries, the lithium ion battery has an advantage that the energy density is much higher than that of the conventional Ni/Cd battery and Ni/MH battery, and further, the lithium ion battery can be manufactured with a tendency of a small size so that it is used as a power source for a mobile apparatus. The usage range of such a lithium ion battery extends as a power source for electric vehicles, so that the lithium ion battery attracts attention as a next generation energy storage medium.

In addition, a secondary battery is generally used as a battery pack including a battery module in which a plurality of battery cells are connected in series and/or in parallel. A state and an operation of such a battery pack are managed and controlled by a BATTERY MANAGEMENT SYSTEM (BMS).

In general, in the case of an electric vehicle, since high energy is required to improve the driving distance, battery cells are connected in parallel to increase capacity. In particular, in the case of a cylindrical secondary battery (<NUM> or <NUM> cells), a larger number of cells need to be connected in parallel because the cell amount is smaller than that of a medium-large cell (a pouch or a square).

It is practically impossible to monitor the state of all cells in BMS so that voltage is measured in units of modules including cells connected in parallel and the state of the battery (SOC and SOH) is estimated.

In the case of cylindrical cells, when gas is generated inside the cell due to overvoltage or overcurrent, CURRENT INTERRUPT DEVICE (CID), which cuts off the cell's electrical connection and releases gas, is sometimes operated. In this case, the electrical connection of one of the cells connected in parallel is cut off, so that the SOH value of the module including the cell changes. Also, the SOH value of the module including the cell changes due to deterioration of the battery cell. Therefore, it was not possible to know only with the related art whether the capacity was reduced due to the deterioration of the battery cells in the battery module or the capacity was decreased due to the CID operation.

If this is not clearly known, as an overload (increased current) occurs in the disconnected cell and the parallel connected cells, safety issues occur or cell degeneration proceeds quickly, thereby causing a decrease in battery performance.

Further background art is described in <CIT>, <CIT> and <CIT>.

An object of the present invention is to diagnose the cause of a capacity reduction by using an SOH change amount of a battery module in order to solve the above-described problem.

In order to solve the above technical problems, a battery management apparatus according to embodiments of the present invention includes: an SOC calculation unit configured to calculate an SOC of a battery module by using at least one of voltage, current, and temperature measured for the battery module in which a plurality of battery cells are connected in parallel; an SOH calculation unit configured to calculate an SOH of the battery module based on at least one of the SOC calculated by the SOC calculation unit and the voltage, current, or temperature of the battery module; and a diagnosis unit configured to calculate an SOH change rate using the SOH, and diagnose a state of the battery module using the calculated SOH change rate, wherein the state of the battery module is any one of a normal state, a state including a degenerate battery cell, or a state including a current interrupt device (CID) open battery cell.

In the battery management apparatus according to the present invention, the SOC calculation unit calculates an SOC of each of a plurality of battery modules based on at least one of voltage, current, and temperature of each of the plurality of battery modules, wherein the SOH calculation unit calculates an SOH of each of the plurality of battery modules based on an SOC of each of the plurality of battery modules, wherein the diagnosis unit diagnoses a state of the battery module by comparing the change rate of the SOH of each of the plurality of battery modules.

In the battery management apparatus according to the present invention, the diagnosis unit diagnoses a state of the corresponding battery module by comparing a preset value with an SOH change rate of other battery modules with respect to an SOH change rate of a specific battery module among change rates of each SOH of the plurality of battery modules during a predetermined time.

In the battery management apparatus according to the present invention, if the SOH change rate of the specific battery module is greater than a first value and less than a second value compared to the SOH change rate of other battery modules, the diagnosis unit diagnoses the specific battery module as a state including a degenerate battery cell, wherein if an SOH reduction rate of the specific battery module is (<NUM>/number of battery cells in the battery module) * <NUM>% or more, the diagnosis unit diagnoses the battery module as a state including a CID open battery cell, wherein the diagnosis unit diagnoses a battery module that is not in a state including the degenerate battery cell or including a CID open battery cell as a normal state.

The battery management apparatus according to embodiments of the present disclosure may further include a storage unit for storing each SOH value calculated for the plurality of battery modules.

The battery management apparatus according to embodiments of the present disclosure may further include a communication unit for transmitting a diagnosis result to an upper-level system if the state of the specific battery module is diagnosed as a state including a degenerate battery cell or including a CID open battery cell.

In order to solve the above technical problems, a battery management method according to embodiments of the present invention includes: calculating an SOC of a battery module by using at least one of voltage, current, and temperature measured for the battery module in which a plurality of battery cells are connected in parallel; calculating an SOH of the battery module based on at least one of the calculated SOC and the voltage, current, or temperature of the battery module; and calculating a change rate of the SOH of the battery module, and diagnosing a state of the battery module using the calculated SOH change rate, wherein the state of the battery module is any one of a normal state, a state including a degenerate battery cell, or a state including a current interrupt device (CID) open battery cell.

In the battery management method according to the present invention, the calculating of the SOC and the calculating of the SOH are performed for a plurality of battery modules, so that an SOC and an SOH of each of the plurality of battery modules are calculated, wherein the method may further include calculating an SOH change rate by storing the SOH of each of the plurality of battery modules.

In the battery management method according to the present invention, the diagnosing of the state of the battery module includes performing diagnosing by comparing each of the SOH of the plurality of battery modules.

In the battery management method according to the present invention, the diagnosing of the state of the battery module includes: if the SOH change rate of the specific battery module among the plurality of battery modules is greater than a first value and less than a second value compared to the SOH change rate of other battery modules, diagnosing the specific battery module as a state including a degenerate battery cell; if an SOH reduction rate of the specific battery module is (<NUM>/number of battery cells in the battery module) * <NUM>%, diagnosing the corresponding battery module as a state including a CID open battery cell; and diagnosing a battery module that is not in a state including the degenerate battery cell or including a CID open battery cell as a normal state.

The battery management method according to embodiments of the present disclosure may further include storing each SOH value calculated for the plurality of battery modules.

The battery management method according to embodiments of the present disclosure may further include transmitting a diagnosis result to an upper-level system if the state of the specific battery module is diagnosed as a state including a CID open battery cell.

The battery management method according to embodiments of the present disclosure may further include transmitting a diagnosis result to an upper-level system if the state of the specific battery module is diagnosed as a state including a degenerate battery cell and the number of corresponding diagnosis results is greater than or equal to a preset number.

The present invention has an effect of improving battery efficiency and safety by diagnosing the cause of capacity reduction using an SOH change amount of a battery module in order to solve the above-described problem.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this document, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted.

For various embodiments of the present invention disclosed in this document, specific structural or functional descriptions are exemplified only for the purpose of explaining an embodiment of the present invention, and various embodiments of the present invention may be implemented in various forms and should not be construed as being limited to the embodiments described in this document.

The terms such as "1st", "2nd", "first", "second", and the like used herein may refer to modifying various different elements of various embodiments of the present disclosure, but do not limit the elements. For example, a first component may be referred to as a second component and vice versa without departing from the technical scope of the present invention.

Terms used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the scope of other embodiments. The terms of a singular form may include plural forms unless they have a clearly different meaning in the context.

Otherwise indicated herein, all the terms used herein, which include technical or scientific terms, may have the same meaning that is generally understood by a person skilled in the art. In general, the terms defined in the dictionary should be considered to have the same meaning as the contextual meaning of the related art, and, unless clearly defined herein, should not be understood as having an ideal or excessively formal meaning. In any cases, even the terms defined in this specification cannot be interpreted as excluding embodiments of the present invention.

<FIG> is a block diagram showing a battery management system and an upper-level system.

A battery pack <NUM> includes a battery module <NUM> composed of one or more battery cells and capable of being charged and discharged, a switching unit <NUM> connected in series to the + terminal side or the - terminal side of the battery module <NUM> to control the charge/discharge current flow of the battery module <NUM>, and a BMS <NUM> that monitors the voltage, current, temperature, and the like of the battery module <NUM> to control and manage it so as to prevent overcharge and overdischarge.

Here, the switching unit <NUM> is a semiconductor switching element for controlling the current flow for the charge or discharge of the battery module <NUM>, and for example, at least one MOSFET may be used. It will be readily understood by those skilled in the art that a relay or a contactor may be used as the switching unit <NUM> in addition to the semiconductor switching element.

In addition, in order to monitor the voltage, current, temperature, etc. of the battery module <NUM>, the BMS <NUM> can measure or calculate voltages and currents of gates, sources, and drains of semiconductor switching elements, and in addition, can measure the current, voltage, temperature, etc. of the battery module using the sensor <NUM> provided adjacent to the semiconductor switching element. The BMS <NUM> is an interface for receiving the values obtained by measuring the above-described various parameters, and may include a plurality of terminals and a circuit that is connected to these terminals and processes the received values.

In addition, the BMS <NUM> may control ON/OFF of the MOSFET and may be connected to the battery module <NUM> to monitor the state of the battery module <NUM>.

Since the configuration of the battery rack <NUM> and the configuration of the BMS <NUM> are known configurations, more detailed description thereof will be omitted.

On the other hand, the BMS <NUM> according to the embodiments of the present invention is connected to the upper-level controller <NUM>, and the operation may be controlled based on a signal applied from the upper-level controller <NUM>.

<FIG> is a configuration diagram of a battery management apparatus <NUM> (battery management system). Although the battery management system <NUM> of <FIG> is shown to be connected to one battery module, the battery management apparatus <NUM> of the present invention may be connected to a plurality of battery modules.

The battery management apparatus <NUM> includes a voltage measurement unit <NUM>, a current measurement unit <NUM>, a temperature measurement unit <NUM>, an SOC calculation unit <NUM>, an SOH calculation unit <NUM>, a storage unit <NUM>, a diagnosis unit <NUM>, and a communication unit <NUM>.

The voltage measurement unit <NUM> measures the voltage at both ends of the battery module. In general, there is a method of measuring a battery voltage, for example, a method of using an operational amplifier and a method of using a relay and a capacitor.

The current measurement unit <NUM> measures the current of the battery module. In general, battery current measurement may be performed using a current sensor corresponding to at least one of a current transformer method, a hall element method, and a fuse method.

The temperature measurement unit <NUM> measures the temperature of the battery module. In general, the battery temperature measurement unit may be, for example, a thermistor. A thermistor is a semiconductor element obtained by mixing and sintering oxides such as manganese, nickel, copper, cobalt, chromium, and iron, and is an element having a characteristic in which an electrical resistance value changes depending on temperature. For example, the thermistor may be any one of the elements of a positive temperature coefficient (PTC) thermistor whose temperature and resistance values are proportional, a negative temperature coefficient (NTC) thermistor whose temperature and resistance values are inversely proportional, and a critical temperature resistor (CTR) whose resistance value changes rapidly at a specific temperature.

The SOC calculation unit <NUM> receives the voltage value of the battery module measured from the voltage measurement unit <NUM>. The SOC calculation unit <NUM> receives the current value of the battery module measured from the current measurement unit <NUM>. The SOC calculation unit <NUM> receives the measured temperature value of the battery module from the temperature measurement unit <NUM>.

The SOC calculation unit <NUM> calculates the SOC of the battery module using at least one of voltage, current, or temperature of the battery module. In general, the battery SOC displays the remaining amount of the battery's full charge capacity as a percentage. SOC estimation methods include a current integration method, a method using an EXTENDED KALMAN FILTER, an electric circuit model method, an electrochemical model method, and a data-based method. The SOC calculation unit <NUM> calculates each SOC for a plurality of battery modules. That is, the SOC calculation unit <NUM> calculates the SOC of the battery module by using at least one of the measured voltage, current, or temperature of a battery module in which a plurality of battery cells are connected in parallel.

The SOH calculation unit <NUM> receives the voltage value of the battery module measured from the voltage measurement unit <NUM>. The SOH calculation unit <NUM> receives the current value of the battery module measured from the current measurement unit <NUM>. The SOH calculation unit <NUM> receives the measured temperature value from the temperature measurement unit <NUM>. The SOH calculation unit <NUM> receives the SOC value of the battery module calculated from the SOC calculation unit <NUM>. In addition, the SOH calculation unit <NUM> also calculates the SOH for each of the plurality of battery modules using voltage values, current values, temperature values, and SOCs for each of the plurality of battery modules.

SOH represents the degree of deterioration of battery capacity due to aging. SOH can be used to adjust the charging/discharging capacity according to the battery replacement time and battery usage period. SOH estimation methods include a method of integrating battery charge/discharge current and a method of estimating using the estimated SOC, and in the present invention, a method of estimating an SOH using an SOC is used. A specific method is a known technique and a detailed description thereof will be omitted.

The storage unit <NUM> receives the SOH values calculated for the plurality of battery modules in real time from the SOH calculation unit <NUM>. The storage unit <NUM> stores the received SOH of each of the plurality of battery modules.

The diagnosis unit <NUM> receives SOH information of each of the plurality of battery modules from the storage unit <NUM>. The diagnosis unit <NUM> calculates the change rate of an SOH of each of the plurality of battery modules, and diagnoses the state of the battery module using the calculated rate of change of an SOH.

Referring to <FIG>, an SOH graph (indicated by a solid line) of a battery module in a normal state, an SOH graph (indicated by a dashed-dotted line) of a battery module in a state including a degenerate battery cell, and an SOH graph (indicated by a dashed-dotted line) of the battery module in the state including the CID open battery cell are shown.

Referring to <FIG>, it can be seen that the change rate of the SOH graph of the battery module including the degenerate battery cell is greater than the change rate of the SOH graph of the normal battery module over time. In addition, the SOH graph of the battery module including the CID open battery cell shows that the SOH rapidly decreases when the corresponding battery cell is opened. As shown in <FIG>, for example, when three battery cells are included in the battery module, and one of the battery cells is CID open, the SOH value of the battery module drops to <NUM>/<NUM> of the SOH of the normal battery module.

That is, when the SOH of a specific battery module is more than (<NUM>/number of battery cells in the battery module) * <NUM>% or more than the SOH of other battery modules, it can be seen that the corresponding battery module includes a CID open battery cell.

Accordingly, if the SOH change rate of a specific battery module is greater than the first value and less than the second value compared to the SOH change rate of other battery modules, the diagnosis unit <NUM> diagnoses the specific battery module as including a degenerate battery cell, and if the SOH reduction rate of a specific battery module is (<NUM>/number of battery cells in the battery module)*<NUM>% or more, the diagnosis unit <NUM> diagnoses the corresponding battery module as including the CID open battery cell, and the diagnosis unit <NUM> diagnoses a battery module that does not include a degenerate battery cell or a CID open battery cell as a normal state.

The communication unit <NUM> receives degenerate battery cell state information or CID open battery cell state information for a specific battery module from the diagnosis unit <NUM> and transmits it to an upper-level controller (vehicle, etc.).

<FIG> is a flowchart of a battery management method according to an embodiment of the present invention.

Charging and discharging are performed on a battery module including a plurality of battery cells connected in parallel (S400). For example, when the battery module is included in a battery pack mounted on a vehicle, charging or discharging may be performed while the vehicle is driving. Also, charging may be performed when the vehicle is parked.

Voltage, current, and temperature for the battery module are measured (S402).

The temperature measurement unit <NUM> measures the temperature of the battery module. In general, the battery temperature measurement unit may be, for example, a thermistor.

The SOC calculation unit <NUM> calculates the SOC of the battery module using at least one of voltage, current, or temperature of the battery module (S404). In general, the battery SOC displays the remaining amount of the battery's full charge capacity as a percentage. SOC estimation methods include a current integration method, a method using an EXTENDED KALMAN FILTER, an electric circuit model method, an electrochemical model method, and a data-based method. The SOC calculation unit <NUM> calculates each SOC for a plurality of battery modules. That is, the SOC calculation unit <NUM> calculates the SOC of the battery module by using at least one of measured voltage, current, and temperature of a battery module in which a plurality of battery cells are connected in series and/or in parallel.

The SOH calculation unit <NUM> also calculates the SOH for each of the plurality of battery modules using voltage values, current values, temperature values, and SOCs for each of the plurality of battery modules (S406).

The diagnosis unit <NUM> receives SOH information of each of the plurality of battery modules from the storage unit <NUM>. The diagnosis unit <NUM> calculates the change rate of the SOH of each of the plurality of battery modules (S408).

Subsequently, the diagnosis unit <NUM> calculates a change rate of the SOH of each of the plurality of battery modules, and diagnoses the state of the battery module using the calculated SOH change rate (S410).

Specifically, if the SOH change rate of a specific battery module is greater than the first value and less than the second value compared to the SOH change rate of other battery modules, the specific battery module is diagnosed as including a degenerate battery cell (S416), and if the SOH reduction rate of a specific battery module is (<NUM>/the number of battery cells in the battery module)* <NUM>% or more (i.e., if it is more than the second value), the battery module is diagnosed as including the CID open battery cell (S412), and a battery module that does not include degenerate battery cells or does not include CID open battery cells (i.e., if it is less than or equal to the first value) is diagnosed as a normal state (S414).

If it is determined that the SOH change rate of a specific battery module is more than the second value (S412), the communication unit <NUM> receives CID open battery cell state information for a specific battery module from the diagnosis unit <NUM> and transmits it to an upper-level controller (vehicle, etc.).

In addition, if it is determined that the SOH change rate of a specific battery module is less than the first value (S416), the diagnosis unit <NUM> determines whether the number of times a specific battery module is diagnosed including a degenerate battery cell is less than a preset number (S420).

If the number of diagnoses with degenerate battery cells is more than the preset number, the vehicle transmits information indicating that the battery module includes the degenerate battery cell to the upper-level controller (vehicle) (S422).

If the number of diagnosis with degenerate battery cells is less than the preset number, the diagnosis unit <NUM> determines whether the battery module is being charged or discharged (S418), and if it is being charged and discharged, the process starts again from operation S402, and if it is not being charged or discharged, the cell is determined to be a normal cell and the diagnosis is terminated.

<FIG> is a block diagram illustrating a hardware configuration of a battery management system according to an embodiment of the present invention.

A battery management system <NUM> may include a microcontroller (MCU) <NUM> for controlling various processes and components, a memory <NUM> in which an operating system program and various programs (for example, a battery pack abnormality diagnosis program or a battery pack temperature estimation program) are recorded, an input/output interface <NUM> for providing an input interface and an output interface between the battery cell module and/or the semiconductor switching element, and a communication interface <NUM> capable of communicating with the outside through a wired or wireless communication network. As described above, the computer program according to the present invention may be recorded in the memory <NUM> and processed by the microcontroller <NUM> to be implemented as a module for performing the respective functional blocks shown in <FIG>.

In the above, even though all the components constituting the embodiments of the present invention are described as being combined into one or operating in combination, the present invention is not necessarily limited to these embodiments. That is, within the scope of the object of the present invention, all of the constituent elements may be selectively combined and operated in one or more.

In addition, the terms "include", "compose", or "have" as described above means that the corresponding component can be intrinsic, unless otherwise stated, so that it should be interpreted that other components may be further included, not excluded. All terms, including technical or scientific terms, can be interpreted as having the same meaning as generally understood by a person skilled in the art to which the present invention belongs, unless otherwise defined. Generally used terms, such as predefined terms, should be interpreted as being consistent with the contextual meaning of the related art, and are not to be interpreted in an ideal or excessively formal sense, unless explicitly defined in the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications and variations without departing from the scope of the present invention as defined by the independent claims.

Claim 1:
A battery management apparatus (<NUM>) comprising:
a state of charge SOC calculation unit (<NUM>) configured to calculate an SOC for each of a plurality of battery modules (<NUM>) by using at least one of voltage, current, or temperature measured for the battery module (<NUM>) in which a plurality of battery cells are connected in parallel;
a state of health SOH calculation unit (<NUM>) configured to calculate an SOH for each of the battery modules (<NUM>) based on the SOC calculated by the SOC calculation unit (<NUM>) and at least one of the voltage, current, and temperature of the battery module; and
a diagnosis unit (<NUM>) configured to calculate a SOH change rate using the SOH, and diagnose a state of the battery module (<NUM>) using the calculated SOH change rate,
wherein the state of the battery module is any one of a normal state, a state including a degenerate battery cell, and a state including a current interrupt device CID open battery cell,
characterized in that:
the diagnosis unit (<NUM>) is configured to diagnose the state of the battery modules by comparing the SOH change rate of each of the plurality of battery modules, wherein the diagnosis unit is configured to:
diagnose the battery module (<NUM>) as the state including a degenerate battery cell, if the SOH change rate of the battery module is greater than a first preset value (TH1) and less than a second preset value (TH2) compared to the SOH change rate of other battery modules (<NUM>) during a predetermined time,
diagnose the battery module as the state including a CID open battery cell, if the SOH reduction rate of the battery module (<NUM>) is (<NUM>/number of battery cells in the battery module) * <NUM>% (TH2) or more during the predetermined time,
diagnose the battery module (<NUM>) as the normal state, if it is not in the state including the degenerate battery cell or including the CID open battery cell.