KR20140072965A - Battery management system, and method of balancing battery cell in battery module using the same - Google Patents

Abstract

A method for balancing cells of a battery module is provided to balance voltages of at least two battery cells included in a battery module by a battery management system (BMS). The method for balancing cells of a battery module includes the steps of: (a) measuring, by a measuring unit included in a BMS, an open circuit voltage (OCV) which is a charge voltage of each of battery cells; (b) setting, by a control unit of the BMS, a voltage included among the measured OCVs as a balancing voltage; (c) controlling, by the control unit of BMS, the respective battery cells having the measured OCVs which are higher than the balancing voltage to be balanced to have the balancing voltage by discharging currents to resistance based on the set balancing voltage by controlling a switch circuit which is included in a cell balancing unit of the BMS and is electrically connected to the resistance; and (d) controlling, by the control unit of the BMS, the respective battery cells having the measured OCVs which are lower than the balancing voltage to be balanced to have the balancing voltage by injecting currents of a current source into the respective battery cells having the measured OCVs which are lower than the balancing voltage by controlling the switch circuit which is included in the cell balancing unit and is electrically connected to the current source.

Description

[0001] The present invention relates to a battery management system, and a method of balancing battery cells using the battery management system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery management system (BMS) related technology, and more particularly, to a battery management system and a cell balancing method of a battery module using the battery management system.

Generally, a large-capacity battery (battery module) capable of generating a large amount of electric power for driving an energy storage system (ESS), an electric vehicle, a hybrid vehicle, and an electric motorcycle (E-Scooter) Can be used.

In particular, interest in energy storage systems (ESS), which can maximize the efficiency of energy storage and quality, and energy use as core of smart grid, is increasing with the spread of renewable energy . The energy storage system (ESS) may include a large-capacity battery module having a plurality of battery cells, and may include a power grid (not shown) to supply remaining power (remaining energy) ) Is a system that can optimize the quality and efficiency of electric power.

A device for managing the battery module more efficiently and stably is a battery management system. The battery management system may be connected to a plurality of battery cells to read a voltage value of each battery cell through an analog to digital converter, and then control charging or discharging of the battery cell.

When a plurality of battery cells are connected to each other as a single battery module, a voltage difference is generated between battery cells due to a chemical difference, a physical property difference, or a difference in usage period of the battery cells constituting the battery module . The lifetime of the battery module may be shortened due to the voltage difference between the battery cells. Therefore, the entire battery packaged in the packaged battery module must be replaced with a new battery module due to the performance degradation such as voltage drop of one single cell (single battery cell) Lt; / RTI > Therefore, a cell balancing process may be required by a battery management system that allows the voltage of each battery cell to be kept the same when charging or discharging a large capacity battery used in an energy storage system (ESS) and an electric vehicle.

It is an object of the present invention to reduce consumption of electrical energy used for cell balancing by reducing the number of charging and discharging cycles for cell balancing of a battery module including battery cells, A battery management system capable of increasing the lifetime of the module, and a cell balancing method of a battery module using the battery management system.

According to an aspect of the present invention, there is provided a method of balancing a battery cell by balancing a voltage of at least two battery cells included in the battery module with a battery management system (BMS) (A) measuring an open circuit voltage (OCV), which is a charge voltage of each of the battery cells, by a measurement unit included in the battery management system; (b) setting a voltage included in the measured open circuit voltages (OCV) as a balancing voltage by a control unit of the battery management system; (c) a control unit of the battery management system, based on the set balancing voltage, controls the opening of the measured open circuit, which is higher than the balancing voltage, through control of a switch circuit included in the cell balancing unit of the battery management system, Each of the battery cells having a voltage discharging a current to the resistor and being controlled to be balanced with the balancing voltage; And (d) a control unit of the battery management system controls currents of the current sources in each of the battery cells having the measured open circuit voltage lower than the balancing voltage through control of a switch circuit included in the cell balancing unit and electrically connected to the current source, And controlling each of the battery cells having the measured open circuit voltage lower than the balancing voltage to be balanced with the balancing voltage.

According to an aspect of the present invention, there is provided a battery management system (BMS) including: a measurement unit for measuring an open circuit voltage (OCV), which is a charging voltage of each of at least two battery cells included in a battery module; And setting a voltage included between the measured open circuit voltages (OCV) as a balancing voltage and controlling the balancing voltage by controlling the switch circuit included in the cell balancing unit of the battery management system based on the set balancing voltage, Each of the battery cells having the measured open circuit voltage higher than the voltage discharges the current to inject current into each of the battery cells having the measured open circuit voltage balanced with the balancing voltage and lower than the balancing voltage, And a control unit for controlling each of the battery cells having the low measured open circuit voltage to be balanced with the balancing voltage, wherein the switch circuit outputs, from each of the battery cells having the measured open circuit voltage higher than the balancing voltage, Current to be resisted Output, and the switch circuit may inject current of the current source to the respective battery cells having a low voltage circuit of the measured voltage than the balancing opening.

According to another aspect of the present invention, there is provided a cell balancing method for a battery module, the method comprising balancing a voltage of at least two battery cells included in a battery module through a battery management system (BMS) A method of balancing a cell of a battery module, the battery balancing method comprising the steps of: (a) measuring an open circuit voltage (OCV), which is a charging voltage of each of the battery cells, (b) setting a voltage included in the measured open circuit voltages (OCV) as a balancing reference voltage by a control unit of the battery management system; (c) a control section of the battery management system, based on a lookup table, controls the switch circuit included in the cell balancing section of the battery management system and electrically connected to the resistor, Each of the battery cells having an open circuit voltage discharging a current into the resistor and balancing with a balancing voltage of each of the battery cells having the measured open circuit voltage higher than the balancing reference voltage; And (d) a control unit of the battery management system, based on the reference table, controls the switch circuit to be connected to the current source by controlling the switch circuit electrically connected to the current source and having the measured open circuit voltage lower than the balancing reference voltage Each of the battery cells having the measured open circuit voltage lower than the balancing reference voltage is charged with the balancing voltage of each of the battery cells having the measured open circuit voltage lower than the balancing reference voltage, And the reference table may include a balancing voltage of each of the battery cells according to a temperature, a number of times of charging and discharging, and a discharging current amount of each of the battery cells, If the balancing reference voltage is higher than The balancing voltage of the first battery cell having the measured open circuit voltage may be higher than the balancing voltage of the second battery cell having the open circuit voltage lower than the balancing reference voltage and higher than the open circuit voltage of the first battery cell The balancing voltage of the third battery cell having the measured open circuit voltage lower than the balancing reference voltage included in the reference table is higher than the balancing reference voltage and lower than the open circuit voltage of the third battery cell May be lower than the balancing voltage of the fourth battery cell.

The reference table may include a balancing voltage of each of the battery cells according to a self-discharge amount of each of the battery cells.

The battery management system and the cell balancing method of a battery module using the battery management system according to the present invention reduce the number of times of charging and discharging for cell balancing operation of a battery module including battery cells The present invention can reduce the consumption of electric energy used in the cell balancing operation and increase the lifetime of the battery module.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the drawings used in the detailed description of the present invention, a brief description of each drawing is provided.
FIG. 1 is a block diagram illustrating a battery management system (BMS) 200 according to an embodiment of the present invention.
FIG. 2 is a view for explaining an embodiment of the cell balancing unit 210 shown in FIG.
3 is a flow chart illustrating a cell balancing method 400 of a battery module according to an embodiment of the present invention.
4 is a graph illustrating a cell balancing method of a battery module compared with the cell balancing method of the present invention.
5 is a diagram (graph) for explaining a cell balancing method of the battery module 100 according to the embodiment of the present invention.
6 is a diagram (graph) for explaining a cell balancing method of the battery module 100 according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention and the objects attained by the practice of the invention, reference should be made to the accompanying drawings, which illustrate embodiments of the invention, and to the description in the accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

FIG. 1 is a block diagram illustrating a battery management system (BMS) 200 according to an embodiment of the present invention.

Referring to FIG. 1, a battery management system (BMS) 200 includes a measurement unit 205, a cell balancing unit 210, and a control unit 215.

The battery management system (BMS) 200 is an energy storage device for electric vehicles, hybrid electric vehicles, or smart distribution, and an energy storage system (ESS) that can be applied to renewable energy fields such as wind power generation or solar power generation. ). ≪ / RTI > The energy storage system (ESS) is a modular (50 (V), 5 (AH)) unit, for example a 3.5 (KW) class residential energy storage device with a large capacity (350 (V) Cells (5 (V) or 3.7 (V), 5 (AH)) can be connected in series or in parallel. An energy storage system (ESS) can be linked to the power system via a PCS (Power Conditioning System, power converter) that can convert DC power to AC power. Conversely, the PCS is a bi-directional PCS that converts AC power of the power system into DC power and provides the converted DC power to the battery module 100 through the BMS 200. [

The battery management system (BMS) 200 monitors (measures or senses) various states of the battery module 100 to detect the temperature of the battery module, the ambient temperature of the battery module, the voltage of the battery module, It is possible to control for battery protection according to the discharge (or charging) current (or the rated capacity (Ah) of the battery module multiplied by the C-rate (current rate)), And a function of managing the battery module 100 in an appropriate state.

The battery management system (BMS) 200 measures cell balancing and SOC (State of Charge) of the cell by measuring voltage, current and temperature of each battery cell of the battery module 100, To control the safety, charge, or discharge of the storage system (ESS). The battery management system (BMS) 200 may balance (equalize) the voltage of the battery cells of the battery module 100.

If the battery cell is charged and discharged for a long time due to the inherent characteristics of the battery cell, the cell voltages may be different from each other. As a result, a minimum voltage and a maximum voltage exist in a battery module including a plurality of battery cells, and when the difference is large, overcharge or overdischarge is caused, so that the lifetime of the entire module can be shortened by one cell. Therefore, in a module composed of a plurality of battery cells, cell balancing is very important for maximizing the life of the battery module.

The measurement unit 205 measures (senses) an open circuit voltage (OCV), which is a charging voltage of each of the battery cells included in the battery module 100. A battery module (or battery pack) 100 includes battery cells, which are at least two secondary batteries. The open circuit voltage (OCV) may be a charging voltage between the anode and the cathode of the battery cell when the battery cell is not discharged or charged, and may be a long-term (open) circuit voltage. That is, the open circuit voltage (OCV) is a voltage obtained by measuring the voltage across the anode and cathode after, for example, several tens of minutes or one hour after the charging or discharging current is stopped. If necessary, . The battery cells may be connected in series or in parallel, and each of the battery cells may have a different charging voltage (or discharge voltage) depending on the temperature of the battery cell, the number of times of charging and discharging, the amount of charging current, or the amount of discharging current. In another embodiment of the present invention, an equivalent electric circuit model of a battery cell is considered considering polarization capacitance (or surface capacitance) due to a diffusion effect during discharging or charging of the battery cell. The open circuit voltage (OCV) may be measured.

The control unit 215 may set the voltage included in the open circuit voltages (OCV) measured by the measuring unit 205 as a balancing voltage. The control unit 215 controls each of the battery cells having the open circuit voltage measured by the measuring unit 205 higher than the balancing voltage through the control of the switch circuit included in the cell balancing unit 210 based on the set balancing voltage A current is injected into each of the battery cells having the open circuit voltage measured by the measuring unit 205 lower than the balancing voltage and discharging the current to discharge the measuring unit 205 lower than the balancing voltage, So that each of the battery cells having the open-circuit voltage measured in step (b) is balanced (charged) with the balancing voltage.

The switch circuit is electrically connected to the resistor and the switch circuit controls the current outputted from each of the battery cells having the open circuit voltage measured by the measurement unit 205 higher than the balancing voltage under the control of the control unit 215, So that the charging voltage of each of the battery cells having the open circuit voltage measured by the measuring unit 205 higher than the balancing voltage can be balanced (equally charged) to the balancing voltage.

The switch circuit is electrically connected to the current source and the switch circuit controls the current of the current source to each of the battery cells having the open circuit voltage measured by the measuring unit 205 lower than the balancing voltage under the control of the control unit 215 The charging voltage of each of the battery cells having the open circuit voltage measured by the measuring unit 205 lower than the balancing voltage may be balanced with the balancing voltage.

The control unit 215 may control the overall operation of the battery management system (BMS) 200 including the measurement unit 205 and the cell balancing unit 210 as a central processing unit (CPU).

FIG. 2 is a view for explaining an embodiment of the cell balancing unit 210 shown in FIG.

2 and 1, the cell balancing unit 210 includes a switch circuit 300, a resistor 305, and a current source 310. The cell balancing unit 210 may perform cell balancing of five serially connected battery cells V1 to V5, which are embodiments of the battery module 100. [

The switch circuit 300 may be electrically connected to the resistor 305 as described above. The switch circuit 300 is connected to each of the battery cells (for example, the battery cell V1) having the open circuit voltage measured by the measuring unit 205 higher than the balancing voltage under the control of the control unit 215 And discharging a current output from each of the battery cells having an open circuit voltage higher than the balancing voltage to the resistor 305 by electrically connecting the battery cells to each other, It can be balanced with voltage. The switch circuit 300 may also be electrically connected to the current source 310. The switch circuit 300 controls the current source 310 to each of the battery cells (for example, the battery cell V5) having the open circuit voltage measured by the measuring unit 205 lower than the balancing voltage under the control of the control unit 215 (Charging) the current of the current source 310 to each of the battery cells having an open circuit voltage lower than the balancing voltage by electrically connecting the battery cells to the battery cells, Balanced by balancing voltage.

3 is a flow chart illustrating a cell balancing method 400 of a battery module according to an embodiment of the present invention. The cell balancing method 400 of the battery module may be applied to the battery management system (BMS) 200 described with reference to FIGS. That is, the cell balancing method balances the voltages of at least two battery cells included in the battery module 100 through a battery management system (BMS).

3, 1, and 2, in the measurement step 405, the measurement unit 205 included in the battery management system (BMS) 200 measures the open circuit voltage OCV) is measured. The measured open circuit voltage (OCV) is provided to the control unit 215 of the battery management system (BMS)

According to the setting step 410, the control unit 215 of the battery management system (BMS) 200 adjusts the (included) voltage included in the open circuit voltages (OCV) measured in the measuring step 405 to the balancing voltage .

According to the control step 415, the control unit 215 controls the switch circuit 300 included in the cell balancing unit 210 to perform a measurement higher than the balancing voltage, based on the balancing voltage set in the setting step 410 Each of the battery cells having an open circuit voltage measured in step 405 dissipates the current (charge) to be balanced (discharged) with the balancing voltage set in the set step 410 and is applied to a measurement step 405 ) So that each of the battery cells having an open circuit voltage lower than the balancing voltage is charged to the balancing voltage set in the setting step 410 Can be controlled.

In another embodiment of the present invention, the control unit 215 controls the voltage of the battery 305 to be higher than the balancing voltage by controlling the switch circuit 300 included in the cell balancing unit 210 and electrically connected to the resistor 305 Each of the battery cells may emit current into the resistor 305 and be controlled to be balanced with the balancing voltage. The control unit 215 controls the current source 310 to each of the battery cells having an open circuit voltage lower than the balancing voltage through the control of the switch circuit 300 included in the cell balancing unit 210 and electrically connected to the current source 310, And the battery cells having an open circuit voltage lower than the balancing voltage are respectively balanced with the balancing voltage.

As described above, the battery management system according to the present invention, and the cell balancing method of a battery module using the battery management system, are configured to calculate a voltage included between open circuit voltages (OCV) of a measured battery cell as a cell balancing target voltage Balancing voltage), it is possible to reduce the number of charging and discharging cycles for cell balancing with respect to the battery module including the battery cells. Therefore, the current dissipation method or the current injection method ) Method, it is possible to reduce the consumption of electric energy used for cell balancing and increase the lifetime of the battery module. The current discharging method is a method of balancing the voltage of a battery cell by selectively discharging (discharging) a current from the highest cell based on the lowest cell voltage by connecting a switch and a resistor that are electrically controllable to both ends of the battery cell have. The current injection method may be a method of selectively charging a current from a lower cell based on the highest battery cell voltage to balance the voltage of the battery cell.

4 is a graph illustrating a cell balancing method of a battery module compared with the cell balancing method of the present invention.

Referring to FIG. 4, the cell balancing method of FIG. 4 represents a current dissipation method. That is, the minimum value of the open circuit voltages (OCV), which are the measured charging voltages of the battery cells included in the battery module, is set as the balancing target voltage (balancing voltage), and the battery cells B5 B2, B3, B4 to balance the open circuit voltages of the battery cells B1, B2, B3, B4 to the balancing target voltage.

As shown in FIG. 4, since the fluctuation of the cell voltage between the balancing start deviation voltage (for example, the open circuit voltage of B4) and the balancing target voltage is large, the energy consumed when performing cell balancing is large and the cell balancing operation The number of cell balancing is large, so that the life of the battery module may be shortened.

5 is a diagram (graph) for explaining a cell balancing method of the battery module 100 according to the embodiment of the present invention.

Referring to FIG. 5, the cell balancing method shown in FIG. 5 shows the cell balancing method of the present invention described with reference to FIGS. That is, the voltage (e.g., the open circuit voltage of the battery cell V3) included between the open circuit voltages (OCV) which are the measured charge voltages of the battery cells of the battery module 100 is referred to as a balancing target voltage , Each of the battery cells (V1, V2, V4) having a measured open circuit voltage higher than the balancing target voltage emits a current to be balanced to a balancing target voltage, and having a measured open circuit voltage lower than the balancing target voltage A current is injected into the battery cell V5 to balance the battery cell V5 with the balancing target voltage.

5 is the open circuit voltage of the battery cell V4 having the maximum value of the open circuit voltages of the battery cells V1 to V5 included in the battery module 100, 200 may be the maximum value of the balancing start voltage value set by the control unit 215 to control the start of the cell balancing operation for the battery module 100. [ The minimum value of the balancing start voltage is an open circuit voltage of the battery cell V5 having a minimum value of the open circuit voltages of the battery cells V1 to V5 included in the battery module 100, The control unit 215 may be set by the control unit 215 to control the start of the cell balancing operation for the battery module 100. [ The value between the maximum value of the balancing start voltage value and the minimum value of the balancing start voltage value may be, for example, a balancing target voltage value (balancing voltage value).

As shown in Fig. 5, the fluctuation range of the cell voltage between the balancing start deviation voltage (for example, the open circuit voltage of V4) and the balancing target voltage may be relatively smaller than the fluctuation range of the cell voltage shown in Fig. Therefore, the embodiment of FIG. 5 differs from the cell balancing method of FIG. 4 in that the energy consumed when performing cell balancing is relatively small and the cell balancing frequency is relatively reduced. The cell balancing method of FIG. 4 can be effectively increased.

6 is a diagram (graph) for explaining a cell balancing method of the battery module 100 according to another embodiment of the present invention.

The cell balancing method may be applied to the battery management system (BMS) shown in FIGS. 1 and 2. FIG. The cell balancing method of the battery module relates to a method of balancing the voltage of at least two battery cells included in the battery module 100 through a battery management system (BMS) 1 control step, and a second control step.

2, the measuring unit 205 included in the battery management system 200 measures a charging voltage of each of the battery cells included in the battery module 100, Measure the voltage (OCV). (For example, the battery cell V5 of FIG. 6) having the smallest measured open circuit voltage among the battery cells may be a battery cell having the lowest discharge characteristic (or performance) have.

According to the setting step, the control unit 215 of the battery management system 200 sets the voltage included between the open circuit voltages (OCV) measured by the measuring unit 205 as a balancing reference voltage.

According to the first control step, the control unit 215 of the battery management system 200 is included in the cell balancing unit 210 of the battery management system 200 based on a lookup table, Each of the battery cells having the open circuit voltage measured by the measuring unit 205 higher than the balancing reference voltage set in the setting step through the control of the electrically connected switch circuit discharges the current to the resistor 305, (Balancing target voltage) of each of the battery cells having the open circuit voltage measured by the measuring unit 205 higher than the balancing reference voltage. The battery cells having the open circuit voltage measured at the measuring unit 205 higher than the balancing reference voltage may be, for example, V1, V2, and V4 as shown in FIG. Since the battery cell V3 is equal to the balancing reference voltage, the cell balancing operation may not be performed.

According to the second control step, the control unit 215 of the battery management system 200 controls the switch circuit included in the cell balancing unit 210 and electrically connected to the current source 310, based on the reference table, The current of the current source 310 is injected into each of the battery cells having the open circuit voltage measured by the measuring unit 205 lower than the balancing reference voltage set in step < RTI ID = 0.0 > To be balanced with the balancing voltage of each of the battery cells having the measured open circuit voltage lower than the balancing reference voltage. The battery cell having the open circuit voltage measured by the measuring unit 205 lower than the balancing reference voltage may be, for example, V5 as shown in FIG.

The reference table may include a balancing voltage of each of the battery cells according to a temperature, a charge and discharge cycle, and a discharge current amount (or a discharge current magnitude) of each of the battery cells. The reference table may include a self-discharge amount (self discharge rate) of each of the battery cells, an amount of charge current (or a charge current amount) of each of the battery cells, an ambient temperature of each of the battery cells, And may further include a balancing voltage of each of the battery cells according to a state of health (SOH) of each of the battery cells.

The balancing voltage of the first battery cell (for example, the battery cell (V1) of FIG. 6) having the measured open circuit voltage higher than the balancing reference voltage included in the reference table is lower than the balancing reference voltage, May be higher than the balancing voltage of the second battery cell (e.g., battery cell V2 of FIG. 6) having the measured open circuit voltage higher than the open circuit voltage of the first battery cell. For example, the balancing voltage value of the battery cell V1 may have a magnitude of 90 (%) of the balancing reference voltage value, and the balancing voltage value of the battery cell V2 may be 80 (%) of the balancing reference voltage value. And the balancing voltage value of the battery cell V4 may have a magnitude of 70 (%) of the balancing reference voltage value.

The balancing voltage of the third battery cell (e.g., battery cell (V5) of FIG. 6) having the measured open circuit voltage lower than the balancing reference voltage included in the reference table is higher than the balancing reference voltage, May be lower than the balancing voltage of the fourth battery cell (not shown) having the measured open circuit voltage lower than the open circuit voltage of the third battery cell. For example, the balancing voltage value of the battery cell V5 may have a magnitude of 110 (%) of the balancing reference voltage value.

The balancing voltage (i.e., the value of the reference table) of each of the battery cells according to the temperature, the number of times of charging and discharging, the amount of discharging current, and the like of each of the battery cells may be determined (set) by experiments on each of the battery cells. The reference table may be stored in a storage unit (not shown) such as an EEPROM (Electrically Erasable Programmable Read-Only Memory) included in the battery management system 200. One cycle of the battery cell can be configured by combining one discharge count and one charge count. The self-discharge amount may be increased because the internal resistance of the battery cell may increase as the temperature of the battery cell increases, for example. The charging and discharging cycle, the self discharge amount, and the aging change determined by the experiment of the battery cell are determined by the discharge voltage value of the battery cell measured by the sensing unit (not shown) of the battery management system (BMS) (Or charge voltage value), a discharge current value (or charge current value), a temperature value, or an ambient temperature value. For example, a battery cell having a small initial value of a discharge voltage (discharge current) may be a battery cell having a large number of times of charging and discharging and aging aggressively.

6 is an open circuit voltage of the battery cell V4 having a maximum value of the open circuit voltages of the battery cells V1 to V5 included in the battery module 100, 200 may be the maximum value of the balancing start voltage value set by the control unit 215 to control the start of the cell balancing operation for the battery module 100. [ The minimum value of the balancing start voltage is an open circuit voltage of the battery cell V5 having a minimum value of the open circuit voltages of the battery cells V1 to V5 included in the battery module 100, The control unit 215 may be set by the control unit 215 to control the start of the cell balancing operation for the battery module 100. [ The value between the maximum value of the balancing start voltage value and the minimum value of the balancing start voltage value may be, for example, a balancing reference voltage value.

A method of performing the cell balancing operation on a certain range of cell balancing voltages by setting the balancing voltages of battery cells included in the battery module 100 according to another embodiment of the present invention differently for each of the battery cells, It can mean cell balancing.

The cell balancing method of the battery module according to another embodiment of the present invention described with reference to FIG. 6 and the like will be described in further detail as follows. The cell balancing method is based on the deviation history characteristic of the cell charge voltage (OCV) of the battery cell such as the temperature, the number of times of charging and discharging, the amount of discharge current, and the aging of each battery cell included in the battery module (Balancing voltage) of each of the battery cells (for example, by controlling the battery cell). Therefore, the cell balancing method of the battery module according to another embodiment of the present invention performs cell balancing according to the characteristics (discharge characteristic or charging characteristic) of each battery cell, so that the open circuit voltage of the battery cell included in the battery module becomes equal to the balancing start deviation By not reaching the voltage, the subsequent cell balancing process can be reduced to consume only the minimum energy required for cell balancing (consumption). Therefore, the above alternative embodiment may have a cell voltage fluctuation width that is smaller than the cell voltage fluctuation width of the cell balancing method shown in Figs. 4 and 5 as a whole. 4 and 5, compared to the cell balancing method of FIGS. 4 and 5, the energy consumed in performing cell balancing is relatively small and the number of cell balancing is relatively reduced. It is possible to more effectively increase (improve) the service life of the battery 100.

The components or " units " or blocks or modules used in the present embodiment may be implemented in software such as a task, a class, a subroutine, a process, an object, an execution thread, , A field programmable gate array (FPGA), or an application-specific integrated circuit (ASIC), or a combination of the above software and hardware. The components or parts may be included in a computer-readable storage medium, or a part of the components may be dispersed in a plurality of computers.

As described above, the embodiments have been disclosed in the drawings and specification. Although specific terms are used herein, they are used for the purpose of describing the present invention only and are not used to limit the scope of the present invention described in the claims or the claims. It is therefore to be understood by those skilled in the art that various modifications and equivalent embodiments are possible in light of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: Battery module
200: BMS
205:
210: cell balancing unit
215:
300: Switch circuit
305: Resistance
310: current source
405: Measuring step
410: Setup step
415: control step

Claims (4)

A cell balancing method of a battery module balancing a voltage of at least two battery cells included in a battery module through a battery management system (BMS)
(a) measuring an open circuit voltage (OCV), which is a charging voltage of each of the battery cells, by a measurement unit included in the battery management system;
(b) setting a voltage included in the measured open circuit voltages (OCV) as a balancing voltage by a control unit of the battery management system;
(c) a control unit of the battery management system, based on the set balancing voltage, controls the opening of the measured open circuit, which is higher than the balancing voltage, through control of a switch circuit included in the cell balancing unit of the battery management system, Each of the battery cells having a voltage discharging a current to the resistor and being controlled to be balanced with the balancing voltage; And
(d) a control unit of the battery management system controls currents of the current sources to each of the battery cells having the measured open circuit voltage lower than the balancing voltage through control of a switch circuit included in the cell balancing unit and electrically connected to the current source, And controlling each of the battery cells having the measured open circuit voltage lower than the balancing voltage to be balanced with the balancing voltage. A battery management system (BMS)
A measuring unit for measuring an open circuit voltage (OCV) which is a charging voltage of each of at least two battery cells included in the battery module; And
And setting a voltage included in the measured open circuit voltage (OCV) as a balancing voltage and controlling the balancing voltage (OCV) based on the set balancing voltage, through control of a switch circuit included in a cell balancing unit of the battery management system Each of the battery cells having the measured open circuit voltage higher than the balanced open circuit voltage discharges current so that current is injected into each of the battery cells having the measured open circuit voltage lower than the balancing voltage and lower than the balancing voltage, And a controller for controlling each of the battery cells having the measured open circuit voltage to be balanced with the balancing voltage,
The switch circuit discharging a current, which is output from each of the battery cells having the measured open circuit voltage higher than the balancing voltage, as a resistor, and the switch circuit being responsive to each of the battery cells having the measured open circuit voltage lower than the balancing voltage And the current of the current source is injected into the battery. A cell balancing method of a battery module balancing a voltage of at least two battery cells included in a battery module through a battery management system (BMS)
(a) measuring an open circuit voltage (OCV), which is a charging voltage of each of the battery cells, by a measurement unit included in the battery management system;
(b) setting a voltage included in the measured open circuit voltages (OCV) as a balancing reference voltage by a control unit of the battery management system;
(c) a control section of the battery management system, based on a lookup table, controls the switch circuit included in the cell balancing section of the battery management system and electrically connected to the resistor, Each of the battery cells having an open circuit voltage discharging a current into the resistor and balancing with a balancing voltage of each of the battery cells having the measured open circuit voltage higher than the balancing reference voltage; And
(d) a control unit of the battery management system controls, based on the reference table, a battery having a measured open circuit voltage lower than the balancing reference voltage through control of a switch circuit included in the cell balancing unit and electrically connected to a current source, The current of the current source is injected into each of the cells so that each of the battery cells having the measured open circuit voltage lower than the balancing reference voltage is balanced with the balancing voltage of each of the battery cells having the measured open circuit voltage lower than the balancing reference voltage Comprising:
Wherein the reference table includes a balancing voltage of each of the battery cells according to a temperature, a number of times of charging and discharging, and a discharging current amount of each of the battery cells,
The balancing voltage of the first battery cell having the measured open circuit voltage higher than the balancing reference voltage included in the reference table is lower than the balancing reference voltage and higher than the open circuit voltage of the first battery cell Is greater than the balancing voltage of the second battery cell,
The balancing voltage of the third battery cell having the measured open circuit voltage lower than the balancing reference voltage included in the reference table is lower than the balancing reference voltage and lower than the open circuit voltage of the third battery cell The balance being lower than the balancing voltage of the fourth battery cell. The method of claim 3,
Wherein the reference table includes a balancing voltage of each of the battery cells according to a self-discharge amount of each of the battery cells.

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