Patent Description:
In recent years, the demand for portable electronic products such as notebook computers, video cameras and portable phones has increased sharply, and the energy storage batteries, robots and satellites has been active developed. Accordingly, high-performance secondary batteries allowing repeated charging and discharging are being actively studied.

Secondary batteries commercially available at present include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium secondary batteries and the like. Among them, the lithium secondary batteries have almost no memory effect compared to nickel-based secondary batteries and thus are in the limelight due to advantageous such as free charging and discharging, low self-discharge rate and high energy density.

Batteries are used in a wide variety of applications, and large capacities are often required for devices such as electric-driven vehicles or smart grid systems to which batteries are frequently utilized. In order to increase the capacity of the battery, the capacity of the secondary battery, namely the capacity of a battery cell itself, may be increased. However, in this case, the capacity increase effect is not large and there is a physical limitation on the size expansion of the secondary battery. Thus, generally, a battery pack in which a plurality of battery modules are connected in series and in parallel is widely used.

The plurality of battery modules included in the battery pack have different capacity performances from each other due to the difference in intrinsic characteristics or manufacturing environments and versatility of system applications as the use time elapses, which causes a difference in terminal voltage or state of charge (SOC) of the corresponding modules due to charging and discharging.

If a plurality of battery modules having different relative electrical characteristics are driven as one battery pack, a specific battery module having degraded performance may limit the charging or discharging capacity of the entire battery pack, age the battery pack and cause problems such as overvoltage.

Evenly controlling the terminal voltages between battery modules is known as module balancing or inter-module charge equalization. However, in the conventional inter-module charge equalization technology, it is difficult to individually perform balancing between specific battery modules that require module balancing, among a plurality of battery modules. In particular, in order to implement a charge equalization circuit that individually selects a specific battery module, a circuit structure becomes complicated, and the number and volume of wiring bundles increase. Thus, due to these problems, it is not easy to manufacture a module equalization device, and the manufacturing process may take long time and suffer from a high defective rate.

Further background art is described in <CIT>, <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 battery module balancing, which may effectively equalize charges between battery modules while balancing a plurality of battery modules included in a battery pack.

In order to accomplish the above object, an apparatus for battery module balancing according to an embodiment, as defined by independent claim <NUM>, balances a plurality of battery modules that respectively include cell assemblies having at least one secondary battery and electrically connected in series, the apparatus for battery module balancing comprising: a monitoring unit provided to each battery module and configured to monitor at least one of voltage, temperature and current of each cell assembly; a self-circulating path provided to each battery module and electrically connected to both ends of each cell assembly to form a closed circuit, the self-circulating path having an inductor configured to allow a charging and discharging current to flow on the self-circulating path and a first discharge MOSFET configured to open or close the self-circulating path: a connector provided to each battery module and configured to have a plurality of connection terminals; a connection path provided to each battery module to electrically connect both ends of the inductor to the plurality of connection terminals and electrically connect neighboring battery modules to each other through the plurality of connection terminals, the connection path having a second discharge MOSFET provided on the connection path to open or close the connection path; and a processor configured to receive a state of each cell assembly from the monitoring unit and control opening and closing operations of the first discharge MOSFET and the second discharge MOSFET on the basis of the received state of each cell assembly so that the plurality of battery modules are balanced.

In addition, the processor may be configured to repeatedly turn on and off the first discharge MOSFET or the second discharge MOSFET so that charges of neighboring cell assemblies are equalized through the self-circulating path and the connection path.

In addition, the processor may be configured to repeatedly turn on and off the first discharge MOSFET to generate an induced electromotive force with respect to the inductor by means of a discharging current of the cell assembly flowing through the self-circulating path and transmit the generated induced electromotive force to a neighboring battery module through the connection path.

In addition, the processor may be configured to repeatedly turn on and off the second discharge MOSFET to generate an induced electromotive force of the inductor by means of a discharging current of the cell assembly flowing through the connection path and transmit the generated induced electromotive force to a neighboring battery module through the self-circulating path.

The connection path includes a first internal connection path and a second internal connection path, the plurality of connection terminals may include a first connection terminal and a second connection terminal, the first internal connection path may be configured to electrically connect a node between a positive electrode terminal of each cell assembly and one end of the inductor directly to the first connection terminal, and the second internal connection path may be configured to electrically connect a node between the other end of the inductor and the first discharge MOSFET directly to the second connection terminal.

In addition, the second discharge MOSFET may be configured to be provided on the second internal connection path.

In addition, the connection path may further include an external connection path configured to electrically connect the first connection terminal and the second connection terminal of each battery module directly to the second connection terminal and the first connection terminal of a neighboring battery module, respectively.

In addition, in order to accomplish the above object, a battery management system (BMS) according to an embodiment of the present disclosure comprises the apparatus for battery module balancing according to the present disclosure.

In addition, in order to accomplish the above object, a battery pack according to an embodiment of the present disclosure comprises the apparatus for battery module balancing according to the present disclosure.

In addition, in order to accomplish the above object, a method for battery module balancing according to an embodiment of the present disclosure balances a plurality of battery modules that respectively include cell assemblies having at least one secondary battery and electrically connected in series, the method for battery module balancing comprising: monitoring at least one of voltage, temperature and current of each cell assembly; and receiving a state of each cell assembly, which is monitored in the monitoring step, and controlling opening and closing operations of a first discharge MOSFET configured to open or close a self-circulating path, which is electrically connected to both ends of each cell assembly to form a closed circuit and has an inductor configured to allow a charging and discharging current to flow on the self-circulating path, and a second discharge MOSFET configured to open or close a connection path, which electrically connects both ends of the inductor to a plurality of connection terminals and electrically connects neighboring battery modules to each other through the plurality of connection terminals, on the basis of the received state of each cell assembly so that the plurality of battery modules are balanced.

According to the present disclosure, it is possible to allow easy manufacture of the battery pack and easily reduction of its size since connectors may be simplified and the volume of wire harness may be reduced, when individually selecting battery modules to which charging and discharging are required for charge equalization of the battery modules.

In addition, in the configuration of individually selecting battery modules, there is an advantage that the structure of the wiring connected to the battery modules is simplified and the charge equalization speed between the battery modules is increased.

In addition, the battery module equalization device according to the present disclosure has an advantage of simplifying the charge equalization circuit by easily transferring energy between the battery modules without an external power connection.

In addition, according to an aspect of the present disclosure, it is possible to reduce the number of switches and resistors by using the induced electromotive force of the inductor and to reduce the power loss consumed by the resistors, thereby effectively balancing the battery modules.

The present disclosure may have various effects other than the above, and other effects of the present disclosure may be understood from the following description and more clearly figured out by the embodiments of the present disclosure.

In addition, in the present disclosure, if it is determined that a detailed description of a related known structure or function may obscure the subject matter of the present disclosure, the detailed description will be omitted.

Furthermore, the term "processor" 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.

In this specification, the secondary battery refers to a one independent cell that includes 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 secondary battery.

An apparatus for battery module balancing according to an embodiment of the present disclosure may be an apparatus for balancing a plurality of battery modules <NUM>, <NUM> included in a battery pack. More specifically, the apparatus for battery module balancing according to an embodiment of the present disclosure may be an apparatus for equalizing charges between a plurality of battery modules <NUM>, <NUM>, which respectively include cell assemblies <NUM>, <NUM> having at least one secondary battery and electrically connected with each other in series.

<FIG> is a diagram schematically showing some components of an apparatus for battery module balancing according to an embodiment of the present disclosure.

Referring to <FIG>, the apparatus for battery module balancing according to an embodiment of the present disclosure includes monitoring units <NUM>, <NUM>, a self-circulating path L1, connectors <NUM>, <NUM>, connection paths L2, L3 and processors <NUM>, <NUM>.

The monitoring units <NUM>, <NUM> may be provided to the battery modules <NUM>, <NUM>, respectively. For example, as shown in <FIG>, the monitoring units <NUM>, <NUM> may be electrically connected to the cell assemblies <NUM>, <NUM> provided in the battery modules <NUM>, <NUM>, respectively. In addition, the monitoring units <NUM>, <NUM> may be electrically connected to both ends of the cell assemblies <NUM>, <NUM>, respectively. Also, the monitoring units <NUM>, <NUM> may be electrically connected to both ends of a current sensor provided on a charging and discharging path, respectively.

In addition, the monitoring units <NUM>, <NUM> may be configured to monitor at least one of voltage, temperature and current of each cell assembly <NUM>, <NUM>. For example, the monitoring units <NUM>, <NUM> may be configured to measure at least one of voltage, temperature and current of the secondary battery included in each cell assembly <NUM>, <NUM>. For example, the monitoring units <NUM>, <NUM> may be configured to measure the voltage of the secondary battery. For example, as shown in <FIG>, the monitoring units <NUM>, <NUM> may be electrically connected to both ends of the cell assemblies <NUM>, <NUM>. In addition, the monitoring units <NUM>, <NUM> may be electrically connected to the processors <NUM>, <NUM> to transmit and receive electric signals. In addition, the monitoring units <NUM>, <NUM> may be electrically connected to the processors <NUM>, <NUM> to transmit and receive electric signals. In addition, under the control of the processors <NUM>, <NUM>, the monitoring units <NUM>, <NUM> may measure the voltage at both ends of the cell assemblies <NUM>, <NUM> at time intervals and output a signal indicating the magnitude of the measured voltage to the processors <NUM>, <NUM>. In this case, the processors <NUM>, <NUM> may determine the voltage of the cell assemblies <NUM>, <NUM> from the signal output from the monitoring units <NUM>, <NUM>. For example, the monitoring units <NUM>, <NUM> may be implemented using a voltage measurement circuit commonly used in the art.

In addition, the monitoring units <NUM>, <NUM> may be configured to measure the current flowing through the cell assemblies <NUM>, <NUM>. For example, as shown in <FIG>, the monitoring units <NUM>, <NUM> may be electrically connected to both ends of a current sensor provided on the charging and discharging path of the cell assemblies <NUM>, <NUM>. In addition, the monitoring units <NUM>, <NUM> may be electrically coupled to the processors <NUM>, <NUM> to transmit and receive electric signals. In addition, under the control of the processors <NUM>, <NUM>, the monitoring units <NUM>, <NUM> may repeatedly measure the magnitude of the charging current or the discharging current of the cell assemblies <NUM>, <NUM> at time intervals and output a signal indicating the magnitude of the measured current to the processors <NUM>, <NUM>. In this case, the processors <NUM>, <NUM> may determine the magnitude of the current from the signal output from the monitoring units <NUM>, <NUM>. For example, the current sensor may be implemented using a hall sensor or a sense resistor generally used in the art.

In addition, the monitoring units <NUM>, <NUM> may be configured to measure the temperature of the cell assemblies <NUM>, <NUM>. For example, as shown in <FIG>, the monitoring units <NUM>, <NUM> may be connected to the cell assemblies <NUM>, <NUM> to measure the temperature of the secondary battery included in the cell assemblies <NUM>, <NUM>. In addition, the monitoring units <NUM>, <NUM> may be electrically coupled to the processors <NUM>, <NUM> to transmit and receive electric signals. In addition, the monitoring units <NUM>, <NUM> may repeatedly measure the temperatures of the cell assemblies <NUM>, <NUM> at time intervals and output a signal indicating the magnitude of the measured temperature to the processors <NUM>, <NUM>. In this case, the processors <NUM>, <NUM> may determine the temperature of the secondary battery from the signal output from the monitoring units <NUM>, <NUM>. For example, monitoring units <NUM>, <NUM> may be implemented using a thermocouple commonly used in the art.

The self-circulating path L1 may be provided to each battery module <NUM>, <NUM>. In addition, the self-circulating path L1 may be electrically connected to both ends of each cell assembly <NUM>, <NUM> to form a closed circuit. For example, as shown in <FIG>, the self-circulating path L1 may be provided to each battery module <NUM>, <NUM> and electrically connected to both ends of the cell assemblies <NUM>, <NUM>, respectively. In addition, the self-circulating path L1 may form an electrically closed circuit extending from the positive electrode terminals of the cell assemblies <NUM>, <NUM> to the negative electrode terminals of the cell assemblies <NUM>, <NUM>.

In addition, the self-circulating path L1 may include inductors <NUM>, <NUM> and first discharge MOSFETs <NUM>, <NUM> on the self-circulating path L1.

The inductors <NUM>, <NUM> may be configured to allow a charging and discharging current to flow on the path. For example, as shown in <FIG>, the inductors <NUM>, <NUM> may be provided on the self-circulating path L1. For example, the inductors <NUM>, <NUM> may be provided on the self-circulating path L1 that is directly connected to the positive electrode terminals of the cell assemblies <NUM>, <NUM>. In addition, the inductors <NUM>, <NUM> may be configured to allow a charging and discharging current flowing on the self-circulating path L1 to flow therethrough. For example, the inductors <NUM>, <NUM> may be implemented using a coil having an inductance L[H] component according to Faraday's law.

The first discharge MOSFETs <NUM>, <NUM> may be configured to open and close the path. For example, as shown in <FIG>, the first discharge MOSFETs <NUM>, <NUM> may be provided on the self-circulating path L1 to open and close the self-circulating path L1. For example, the first discharge MOSFETs <NUM>, <NUM> may be directly provided between the inductors <NUM>, <NUM> and the negative electrode terminals of the cell assemblies <NUM>, <NUM>. In addition, the first discharge MOSFETs <NUM>, <NUM> may be electrically connected to the processors <NUM>, <NUM> to transmit and receive electric signals so as to be turned off or on under the control of the processors <NUM>, <NUM>.

The connectors <NUM>, <NUM> may be provided to the battery modules <NUM>, <NUM>, respectively. For example, as shown in <FIG>, the connectors <NUM>, <NUM> may be provided at one side of the battery modules <NUM>, <NUM>, respectively. In addition, the connectors <NUM>, <NUM> may include a plurality of connection terminals. For example, as shown in <FIG>, the connectors <NUM>, <NUM> may include two connection terminals. In addition, the connectors <NUM>, <NUM> may electrically connect the battery modules <NUM>, <NUM> to each other directly through the connection terminals.

The connection paths L2, L3 may be provided to the battery modules <NUM>, <NUM>, respectively. In addition, the connection paths L2, L3 may electrically connect both ends of the inductors <NUM>, <NUM> to the plurality of connection terminals <NUM>, <NUM>, <NUM>, <NUM>, respectively. In addition, the connection paths L2, L3 may electrically connect neighboring battery modules <NUM>, <NUM> to each other through the plurality of connection terminals <NUM>, <NUM>, <NUM>, <NUM>. For example, as shown in <FIG>, the connection paths L2, L3 may be provided to the battery modules <NUM>, <NUM>, respectively, to electrically connect both ends of the inductors <NUM>, <NUM> directly to the connection terminals <NUM>, <NUM>, <NUM>, <NUM>. In addition, the connection paths L2, L3 may electrically connect the connection terminals <NUM>, <NUM>, <NUM>, <NUM> respectively provided to the battery modules <NUM>, <NUM> to each other such that neighboring battery modules <NUM>, <NUM> are electrically connected.

In addition, the connection paths L2, L3 may include second discharge MOSFETs <NUM>, <NUM>, respectively. In addition, the second discharge MOSFETs <NUM>, <NUM> may be provided on the path to open and close the path. For example, as shown in <FIG>, the second discharge MOSFETs <NUM>, <NUM> may be provided on the connection paths L2, L3 to open and close the connection paths L2, L3. For example, the second discharge MOSFETs <NUM>, <NUM> may be provided between the inductors <NUM>, <NUM> and the connection terminals <NUM>, <NUM>, <NUM>, <NUM>. In addition, the second discharge MOSFETs <NUM>, <NUM> may be electrically connected to the processors <NUM>, <NUM> to transmit and receive electric signals so as to be turned off or on under the control of the processors <NUM>, <NUM>.

Preferably, the first discharge MOSFETs <NUM>, <NUM> and the second discharge MOSFETs <NUM>, <NUM> according to an embodiment of the present disclosure are a field effect transistor (FET) element having a gate terminal, a drain terminal and a source terminal and may be turned on or off depending on whether a channel is formed according to a voltage applied between the gate terminal and the source terminal. For example, the FET element may be a metal oxide semiconductor field effect transistor (MOSFET).

In addition, the first discharge MOSFETs <NUM>, <NUM> and the second discharge MOSFETs <NUM>, <NUM> may include a FET body and a parasitic diode, respectively. Here, the parasitic diode is a diode connected in parallel with the FET body and acts as a rectifier for conducting a current in one direction.

For example, as shown in <FIG>, in the first discharge MOSFETs <NUM>, <NUM> according to an embodiment of the present disclosure, the drain terminal may be directly connected to one end of the inductors <NUM>, <NUM>, and the source terminal may be directly connected to the negative electrode terminal of the cell assemblies <NUM>, <NUM>. In addition, in the first discharge MOSFETs <NUM>, <NUM>, the parasitic diodes may allow a current to be conducted from the source terminal to the drain terminal. That is, the parasitic diodes of the first discharge MOSFETs <NUM>, <NUM> may set the direction from the negative electrode terminals of the cell assemblies <NUM>, <NUM> to the inductors <NUM>, <NUM> as a forward direction.

For example, as shown in <FIG>, in the second discharge MOSFETs <NUM>, <NUM> according to an embodiment of the present disclosure, the drain terminal may be directly connected to the connection terminals <NUM>, <NUM>, and the source terminal may be directly connected to one end of the inductors <NUM>, <NUM>. In addition, in the second discharge MOSFETs <NUM>, <NUM>, the parasitic diodes may allow a current to be conducted from the source terminal to the drain terminal. That is, the parasitic diodes of the second discharge MOSFETs <NUM>, <NUM> may set the direction from the inductors <NUM>, <NUM> to the connection terminals <NUM>, <NUM> as a forward direction.

In addition, the processors <NUM>, <NUM> may control the turn-on and turn-off operations of the first discharge MOSFETs <NUM>, <NUM> and the second discharge MOSFETs <NUM>, <NUM>. For example, as shown in <FIG>, the processors <NUM>, <NUM> may be electrically connected to the gate terminals of the first discharge MOSFETs <NUM>, <NUM> and the second discharge MOSFETs <NUM>, <NUM> to transmit and receive electric signals. In addition, the processors <NUM>, <NUM> may control the turn-on and turn-off operations of the first discharge MOSFETs <NUM>, <NUM> and the second discharge MOSFETs <NUM>, <NUM> by controlling the voltages applied to the gate terminals of the first discharge MOSFETs <NUM>, <NUM> and the second discharge MOSFETs <NUM>, <NUM>.

Preferably, the connection paths L2, L3 according to an embodiment of the present disclosure may include a first internal connection path L2 and a second internal connection path L2. In addition, the plurality of connection terminals <NUM>, <NUM>, <NUM>, <NUM> may include first connection terminals <NUM>, <NUM> and second connection terminals <NUM>, <NUM>.

As shown in <FIG>, the first internal connection path L2 may be configured to electrically connect a node between the positive electrode terminal of each cell assembly <NUM>, <NUM> and one end of the inductors <NUM>, <NUM> directly to the first connection terminals <NUM>, <NUM>.

As shown in <FIG>, the second internal connection path L2 may be configured to electrically connect a node between the other end of the inductors <NUM>, <NUM> and the first discharge MOSFETs <NUM>, <NUM> directly to the second connection terminals <NUM>, <NUM>.

Preferably, the second discharge MOSFETs <NUM>, <NUM> according to an embodiment of the present disclosure may be provided on the second internal connection path L2. For example, as shown in <FIG>, the second discharge MOSFETs <NUM>, <NUM> may be provided on the second internal connection path L2 that directly connects the node between the other end of the inductors <NUM>, <NUM> and the first discharge MOSFETs <NUM>, <NUM> directly to the second connection terminal <NUM>, <NUM>.

Preferably, the connection paths L2, L3 according to an embodiment of the present disclosure may further include an external connection path L3.

The external connection path L3 may be configured to be electrically connect the first connection terminals <NUM>, <NUM> and the second connection terminal <NUM>, <NUM> of each battery module <NUM>, <NUM> directly to the second connection terminal <NUM>, <NUM> and the first connection terminals <NUM>, <NUM> of a neighboring battery module <NUM>, <NUM>. For example, as shown in <FIG>, the external connection path L3 may electrically connect the second connection terminal <NUM> of the second battery module <NUM> directly to the first connection terminal <NUM> of the first battery module <NUM>. In addition, preferably, the external connection path L3 according to an embodiment of the present disclosure may connect the battery modules <NUM>, <NUM> to each other in a daisy chain manner.

The processors <NUM>, <NUM> may be electrically connected to the monitoring units <NUM>, <NUM> to transmit and receive electric signals so as to receive the states of the cell assemblies <NUM>, <NUM> from the monitoring units <NUM>, <NUM>. For example, the states of the cell assemblies <NUM>, <NUM> may include SOC or SOH of the secondary battery. For example, the processors <NUM>, <NUM> may receive at least one of voltage, temperature and current of the secondary battery from the monitoring units <NUM>, <NUM>. In addition, the processors <NUM>, <NUM> may estimate the SOC of the secondary battery on the basis of at least one of voltage, current and temperature of the secondary battery.

In addition, the processors <NUM>, <NUM> may receive state information of the cell assemblies <NUM>, <NUM> from the monitoring units <NUM>, <NUM>. Here, the state information of the cell assemblies <NUM>, <NUM> may include a voltage value of the secondary battery, a current value of the secondary battery, and a temperature value of the secondary battery. More specifically, the state information of the cell assemblies <NUM>, <NUM> may include voltage values at both ends of the cell assemblies <NUM>, <NUM>, current values flowing through the cell assemblies <NUM>, <NUM>, and temperature values of the cell assemblies <NUM>, <NUM>.

In addition, the processors <NUM>, <NUM> may calculate a remaining capacity of the secondary battery by calculating a state of charge (SOC) of the secondary battery using at least one of the measured voltage value, the measured current value and the measured temperature value for the cell assemblies <NUM>, <NUM> received from the monitoring units <NUM>, <NUM>. In addition, the processors <NUM>, <NUM> may calculate an estimated SOC by using the estimated remaining capacity of the secondary battery. Here, the estimated SOC may be calculated as a value corresponding to the remaining capacity of the secondary battery in the range of <NUM>% to <NUM>%.

In an embodiment of the present disclosure, the processors <NUM>, <NUM> may estimate the SOC of the secondary battery by integrating a charging current and a discharging current of the secondary battery. Here, an initial SOC value when the secondary battery starts charging or discharging may be determined using an open circuit voltage (OCV) of the secondary battery measured before the secondary battery starts charging or discharging. To this end, the processors <NUM>, <NUM> include an OCV-SOC look-up table that defines the SOC for each OCV, and may map the SOC corresponding to the OCV of the secondary battery from the look-up table.

In another embodiment of the present disclosure, the processors <NUM>, <NUM> may calculate the SOC of the secondary battery by using an extended Kalman filter. The extended Kalman filter is a mathematical algorithm that adaptively estimates a SOC of a secondary battery by using voltage, current and temperature of the secondary battery. Here, the estimation of the SOC using the extended Kalman filter may be understood with reference to, for example, the article of <NPL>). In addition to the current integration method or the extended Kalman filter as above, the SOC of the secondary battery may also be determined by other known methods for estimating a SOC by selectively utilizing voltage, current and temperature of the secondary battery.

More preferably, the processors <NUM>, <NUM> according to an embodiment of the present disclosure may receive at least one of voltage, current and temperature of the secondary battery from the monitoring units <NUM>, <NUM> and estimate a state of health (SOH) of the secondary battery on the basis of at least one of the voltage, current and temperature of the secondary battery. Here, the SOH of the secondary battery refers to a degradation rate. The degradation rate of a secondary battery may also be determined by other known methods for estimating a degradation rate by selectively utilizing a SOC of the secondary battery and an internal resistance of the secondary battery, in addition to the above method using voltage, current and temperature of the secondary battery.

In addition, the processors <NUM>, <NUM> may balance the plurality of battery modules <NUM>, <NUM> by controlling the opening and closing operations of the first discharge MOSFETs <NUM>, <NUM> and the second discharge MOSFETs <NUM>, <NUM> on the basis of the state of the received cell assemblies <NUM>, <NUM>, respectively.

Preferably, the processors <NUM>, <NUM> according to an embodiment of the present disclosure may equalize charges between neighboring cell assemblies <NUM>, <NUM> through the self-circulating path L1 and the connection paths L2, L3 by repeatedly turning on and off the first discharge MOSFETs <NUM>, <NUM> or the second discharge MOSFETs <NUM>, <NUM>.

Preferably, as shown in <FIG>, the apparatus for battery module balancing according to an embodiment of the present disclosure may further include communication units <NUM>, <NUM>, respectively.

The communication units <NUM>, <NUM> may be electrically connected to the processors <NUM>, <NUM> to transmit and receive electric signals. In addition, the processors <NUM>, <NUM> may receive the SOCs of neighboring battery modules <NUM>, <NUM> through communication units <NUM>, <NUM>. In addition, the processors <NUM>, <NUM> may balance the plurality of battery modules <NUM>, <NUM> on the basis of the received SOCs of the battery modules <NUM>, <NUM>.

Preferably, the apparatus for battery module balancing according to an embodiment of the present disclosure may further include a memory device.

The memory device may be electrically connected to the processors <NUM>, <NUM> to transmit and receive electric signals. In addition, the memory device may store information necessary for controlling the first discharge MOSFETs <NUM>, <NUM> and the second discharge MOSFETs <NUM>, <NUM> in advance.

Meanwhile, the processors <NUM>, <NUM> may be implemented to optionally include processors <NUM>, <NUM>, an application-specific integrated circuit (ASIC), other chipsets, a logic circuit, a register, and a communication modem and/or a data processing device, known in the art, to perform the above operation.

Meanwhile, the memory device is not particularly limited as long as it is a storage medium capable of recording and erasing information. For example, the memory device may be a RAM, a ROM, a register, a hard disk, an optical recording medium, or a magnetic recording medium. The memory device may also be electrically connected to the processors <NUM>, <NUM>, for example, via a data bus or the like so as to be accessible by the processors <NUM>, <NUM>, respectively. The memory device may also store and/or update and/or erase and/or transmit a program including various control logics performed by the processors <NUM>, <NUM> and/or data generated when the control logics are executed.

<FIG> and <FIG> are diagrams showing a path for the apparatus for battery module balancing according to an embodiment of the present disclosure to balance battery modules.

Referring to <FIG> and <FIG>, the processor <NUM> according to an embodiment of the present disclosure may be configured to generate an induced electromotive force for the inductor <NUM> by means of the discharging current of the cell assembly flowing through the self-circulating path L1 by repeatedly turning on and off the first discharge MOSFET <NUM> and transfer the generated induced electromotive force to a neighboring battery module through the connection paths L2, L3.

For example, as shown in <FIG>, the processor <NUM> may allow a discharging current to flow on the self-circulating path L1 included in the second battery module <NUM>. More specifically, when it is intended to discharge the second cell assembly <NUM> included in the second battery module <NUM> and charge the first cell assembly <NUM> included in the first battery module <NUM>, the processor <NUM> may allow a discharging current to flow on the self-circulating path L1 included in the second battery module <NUM>. For example, the processor <NUM> may turn on the first discharge MOSFET <NUM> included in the second battery module <NUM> so that the discharging current flows sequentially through the second cell assembly <NUM>, the inductor <NUM> and the first discharge MOSFET <NUM>.

In addition, as shown in <FIG>, the processor <NUM> may turn off the first discharge MOSFET <NUM> included in the second battery module <NUM> to generate an induced electromotive force for the inductor <NUM>. For example, if the first discharge MOSFET <NUM> is changed from a turn-on state to a turn-off state, the inductor <NUM> may generate an induced electromotive force according to Faraday's law of Equation <NUM> below. That is, the inductor <NUM> may generate an induced electromotive force for maintaining the direction of the current of <FIG>.

Here, v(t) is an induced electromotive force, L is inductance, t is time, and i(t) is a current flowing through the inductor.

In addition, as shown in <FIG>, when an induced electromotive force is generated at the inductor <NUM>, the processor <NUM> may charge the first cell assembly <NUM> through the connection paths L2, L3 and the self-circulating path L1, which sequentially connect the inductor <NUM>, the second discharge MOSFET <NUM>, the connector <NUM> of the second battery module <NUM>, the connector <NUM> of the first battery module <NUM> and the first cell assembly <NUM>.

Through this configuration, the processor <NUM> may discharge the second cell assembly <NUM> and charge the first cell assembly <NUM> by repeatedly turning on and off the first discharge MOSFET <NUM>.

Through this configuration, the apparatus for battery module balancing according to an embodiment of the present disclosure may effectively reduce the number of switches and resistors by using the induced electromotive force of the inductor and reduce the power loss consumed by the resistors, thereby effectively balancing the battery modules.

<FIG> and <FIG> are diagrams showing a path for the apparatus for battery module balancing according to another embodiment of the present disclosure to balance battery modules.

Referring to <FIG> and <FIG>, the processor <NUM> according to an embodiment of the present disclosure may be configured to generate an induced electromotive force of the inductor <NUM> by means of the discharging current of the cell assembly flowing through the connection paths L2, L3 by repeatedly turning on and off the second discharge MOSFET <NUM> and transfer the generated induced electromotive force to a neighboring battery module through the self-circulating path L1.

For example, as shown in <FIG>, the processor <NUM> may allow a discharging current to flow through the self-circulating path L1 and the connection paths L2, L3 included in the first battery module <NUM> and the second battery module <NUM>. More specifically, when it is intended to discharge the first cell assembly <NUM> included in the first battery module <NUM> and charge the second cell assembly <NUM> included in the second battery module <NUM>, the processor <NUM> may allow a discharging current to flow through the self-circulating path L1 and the connection paths L2, L3 included in the first battery module <NUM>. For example, the processors <NUM>, <NUM> allow a discharging current to sequentially flow through the first cell assembly <NUM>, the connector <NUM> of the first battery module <NUM>, the connector <NUM> of the second battery module <NUM>, the second discharge MOSFET <NUM> and the inductor <NUM> by turning off the first discharge MOSFET <NUM> included in the first battery module <NUM> and turning on the second discharge MOSFET <NUM> included in the second battery module <NUM>.

In addition, as shown in <FIG>, the processor <NUM> may generate an induced electromotive force for the inductor <NUM> by turning off the second discharge MOSFET <NUM> included in the second battery module <NUM>. For example, if the second discharge MOSFET <NUM> is changed from a turn-on state to a turn-off state, an induced electromotive force may be generated at the inductor <NUM> according to Faraday's law of Equation <NUM>. That is, the inductor <NUM> may generate an induced electromotive force to maintain the direction of the current of <FIG>.

In addition, as shown in <FIG>, if the induced electromotive force is generated at the inductor <NUM>, the processor <NUM> may charge the second cell assembly <NUM> through the self-circulating path L1 that sequentially connects the inductor <NUM>, the second cell assembly <NUM> and the first discharge MOSFET <NUM>.

Through this configuration, the processor <NUM> may discharge the first cell assembly <NUM> and charge the second cell assembly <NUM> by repeatedly turning on and off the second discharge MOSFET <NUM>.

Through this configuration, the apparatus for battery module balancing according to an embodiment of the present disclosure may easily configure lines of a balancing circuit and efficiently balance the plurality of battery modules through simple switch operations.

The apparatus for battery module balancing according to the present disclosure may include a battery management system (BMS). That is, the BMS according to the present disclosure may be included in the apparatus for battery module balancing of the present disclosure as described above. In this configuration, at least a part of the components of the apparatus for battery module balancing according to the present disclosure may be implemented by supplementing or adding functionality of components included in the conventional BMS. For example, the processor and the memory device of the apparatus for battery module balancing according to the present disclosure may be implemented as components of the BMS.

In addition, the apparatus for battery module balancing according to the present disclosure may be provided to a battery pack. That is, the battery pack according to the present disclosure may include the apparatus for battery module balancing according to the present disclosure. Here, the battery pack may include at least one secondary battery, the apparatus for battery module balancing, electrical components (such as a BMS, a relay and a fuse), a case, and so on.

<FIG> is a schematic flowchart for illustrating a method for battery module balancing according to an embodiment of the present disclosure. In <FIG>, each step may be performed by any component of the apparatus for battery module balancing according to the present disclosure as described above.

As shown in <FIG>, the method for battery module balancing according to the present disclosure includes a monitoring step S100 and a balancing step S110.

First, in the monitoring step S <NUM>, at least one of voltage, temperature and current of each cell assembly may be monitored. Subsequently, in the balancing step S110, the state of each cell assembly monitored in the monitoring step may be received, and opening and closing operations of a first discharge MOSFET configured to open or close a self-circulating path, which is electrically connected to both ends of each cell assembly to form a closed circuit and has an inductor configured to allow a charging and discharging current to flow on the self-circulating path, and a second discharge MOSFET configured to open or close a connection path, which electrically connects both ends of the inductor to a plurality of connection terminals and electrically connects neighboring battery modules to each other through the plurality of connection terminals, may be controlled on the basis of the received state of each cell assembly so that the plurality of battery modules are balanced.

Preferably, in the balancing step S <NUM> according to an embodiment of the present disclosure, the charges of neighboring cell assemblies may be equalized through the self-circulating path and the connection path by repeatedly turning on and off the first discharge MOSFET or the second discharge MOSFET.

Preferably, in the balancing step S110 according to an embodiment of the present disclosure, an induced electromotive force may be generated at the inductor by means of the discharging current of the cell assembly flowing through the self-circulating path by repeatedly turning on and off the first discharge MOSFET, and the generated induced electromotive force may be transferred to a neighboring battery module through the connection path.

Preferably, in the balancing step S110 according to an embodiment of the present disclosure, an induced electromotive force may be generated at the inductor by means of the discharging current of the cell assembly flowing on the connection path by repeatedly turning on and off the second discharge MOSFET, and the induced electromotive force may be transferred to a neighboring battery module through the self-circulating path.

Also, when the control logic is implemented in software, the processor may be implemented as a set of program modules. At this time, the program modules may be stored in a memory device and executed by the processor.

In addition, there is no particular limitation on the types of various control logics of the processor, as long as one or more control logics are combined and the combined control logic is written in a computer-readable code system so that the computer-readable access is possible. As one example, the recording medium includes at least one selected from the group consisting of a ROM, a RAM, a register, a CD-ROM, a magnetic tape, a hard disk, a floppy disk and an optical data recording device. In addition, the code system may be stored and executed in a distributed manner on computers connected through a network. Moreover, functional programs, code and segments for implementing the combined control logics may be easily inferred by programmers in the technical field to which the present disclosure belongs.

Claim 1:
An apparatus for battery module balancing, configured to balance a plurality of battery modules (<NUM>, <NUM>) that respectively include cell assemblies (<NUM>, <NUM>) having at least one secondary battery and electrically connected in series, the apparatus for battery module balancing comprising:
a monitoring unit (<NUM>; <NUM>) provided to each battery module and configured to monitor at least one of voltage, temperature and current of each cell assembly;
a self-circulating path (L1) provided to each battery module and electrically connected to both ends of each cell assembly to form a closed circuit, the self-circulating path having an inductor (<NUM>; <NUM>) configured to allow a charging and discharging current to flow on the self-circulating path and a first discharge MOSFET (<NUM>; <NUM>) configured to open or close the self-circulating path;
a connector (<NUM>; <NUM>) provided to each battery module and configured to have a plurality of connection terminals (<NUM>, <NUM>; <NUM>, <NUM>);
a connection path (L2, L3) provided to each battery module to electrically connect both ends of the inductor to the plurality of connection terminals and electrically connect neighboring battery modules to each other through the plurality of connection terminals, the connection path having a second discharge MOSFET (<NUM>; <NUM>) provided on the connection path to open or close the connection path; and
a processor (<NUM>, <NUM>) configured to receive a state of each cell assembly from the monitoring unit and control opening and closing operations of the first discharge MOSFET and the second discharge MOSFET on the basis of the received state of each cell assembly so that the plurality of battery modules are balanced;
characterised in that
the connection path includes a first internal connection path (L2) and a second internal connection path (L2), and the plurality of connection terminals include a first connection terminal (<NUM>) and a second connection terminal (<NUM>),
wherein the first internal connection path is configured to electrically connect a node between a positive electrode terminal of each cell assembly and one end of the inductor directly to the first connection terminal, and
wherein the second internal connection path is configured to electrically connect a node between the other end of the inductor and the first discharge MOSFET directly to the second connection terminal.