KR20190089421A - Battery management system, and method of balancing of battery module thereof - Google Patents

Abstract

The present invention provides a battery management system, and a balancing method of a battery module for balancing each of battery modules having a plurality of battery cells. According to an embodiment of the present invention, the battery management system comprises: a measurement unit measuring temperature and voltage of battery cells individually included in battery modules; a cell balancing unit balancing a voltage deviation between cells of the battery module; a module balancing unit compensating the voltage deviation between the battery modules; and a control unit controlling the measurement unit, the cell balancing unit, and the module balancing unit.

Description

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

An embodiment of the invention relates to a battery management system.

An embodiment of the invention relates to a balancing method of a battery module using a 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.

An example of a method of balancing between cells is a method of transferring energy between a module and a cell using a multi-winding transformer. According to this method, when energy is transferred from a cell having a higher voltage to a cell having a lower voltage, the energy is transferred from the cell having a higher voltage to the module through the balancing circuit, and again from the module through the balancing circuit to the cell having the lower voltage Energy is transmitted through the process. That is, when energy is transferred from a cell having a high voltage to a cell having a low voltage, the balancing circuit is subjected to twice, which may result in unnecessary energy consumption. Also, since the transformer has to wind the same number of windings on one core and bobbin, the larger the number of cells, the more difficult the design of the transformer becomes, and the larger the volume of the balancing circuit becomes.

Embodiments of the invention can provide a battery management system for balancing each battery module having a plurality of battery cells and a balancing method of the battery module.

Embodiments of the present invention can provide a battery management system and a method of balancing a battery module for balancing a plurality of battery cells of each battery module and balancing each battery module.

According to an embodiment of the present invention, a battery management system includes: a measurement unit that measures a temperature and a voltage of battery cells included in each of the battery modules; A cell balancing unit for balancing a voltage deviation between cells of the battery module; A module balancing unit for compensating for a voltage deviation between the battery modules; And a controller for controlling the measuring unit, the cell balancing unit, and the module balancing unit.

According to an embodiment of the present invention, the module balancing unit is connected to both ends of the battery module, and can charge or shut off the constant voltage / constant current of each battery module.

According to an embodiment of the present invention, the module balancing unit can charge a battery module having a relatively low voltage.

According to an embodiment of the present invention, the module balancing unit may include a converter for down-converting the supplied DC voltage to supply a constant voltage / constant current to each battery module, and a switch unit for controlling the operation of the converter.

According to an embodiment of the present invention, the switch unit is connected to the other end of the primary winding of the converter, and can perform an on or off operation by a control signal received from the control unit.

According to another aspect of the present invention, there is provided a battery management method for a battery module of a battery management system, comprising: detecting a voltage of each battery module having a plurality of battery cells; Calculating a voltage difference between the battery modules; Detecting a battery module having a low voltage as a result of the calculation; And operating the module balancing unit of the detected battery module to charge the detected battery module with a constant voltage / constant current.

Embodiments of the invention can reduce deviations between modules having cells of a battery.

Embodiments of the invention can reduce variations between cells of a battery.

Embodiments of the present invention can check whether a cell in a module is abnormal through balancing between battery modules.

Embodiments of the invention may reduce the number of charge and discharge cycles for cell balancing operations for battery modules.

Embodiments of the invention can reduce the consumption of electrical energy used in the cell balancing operation of the battery.

Embodiments of the invention can increase the life of the battery module.

1 is a block diagram illustrating a battery management system according to an embodiment of the present invention.
2 is a detailed block diagram of the battery management system of FIG.
3 is a view illustrating an example of a battery cell, a battery module, and a battery pack according to an embodiment of the present invention.
FIG. 4A is a circuit diagram of a battery module according to an embodiment of the present invention, and FIG. 4B is a circuit diagram illustrating an example of charging or discharging cells in the battery module.
5 is a circuit diagram showing a balancing operation between battery modules according to an embodiment of the present invention.
6 is a flowchart illustrating an example of a balancing method between battery modules according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms "part," "module," and the like, which are described in the specification, refer to a unit for processing at least one function or operation, and may be implemented by hardware or software or a combination of hardware and software.

A battery management system having a cell balancing function according to an exemplary embodiment of the present invention is a system that can be operated independently. A plurality of the battery modules are connected in series, parallel, or series and parallel, (BESS, battery energy storage system) or a battery pack.

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

Referring to FIG. 1, a battery management system 100 includes a measurement unit 120, a cell balancing unit 130, a module balancing unit 140, and a control unit 110.

The battery management system (BMS) 100 is an energy storage system for electric vehicles, hybrid electric vehicles, or smart power distribution, and an energy storage system applicable to renewable energy fields such as wind power generation or solar power generation ESS). ≪ / 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 100 may be connected to the battery module unit 150 to perform various kinds of control. The battery module unit 150 includes a plurality of battery modules 151, 152, and 153, and the plurality of battery modules 151, 152, and 153 may be connected in series or in parallel to provide predetermined power. As shown in FIG. 3, a plurality of battery cells 51 and 52 are connected in series to be provided as one battery module 151, and a plurality of battery modules 151 are serially connected to each other, 150). The battery module unit 150 may be provided as a plurality of battery modules having a plurality of battery cells.

1 and 2, the battery management system (BMS) 200 monitors (measures or detects) various states of the battery modules 151, 152 and 153 of the battery module unit 150, (Or charging current) of the battery modules 151, 152 and 153 (or the rated capacity Ah of the battery module), the C-rate of the battery modules 151, 152 and 153, the ambient temperature of the battery modules 151, 152 and 153, a value obtained by multiplying a current rate of the battery module 151 by the current rate), informing the operator of the device of the battery condition, and managing the battery modules 151, 152, 153 in an appropriate state.

The battery management system (BMS) 200 measures the voltage, current, and temperature of each battery cell 51, 52, 53 of the battery module 151, 152, 153 to perform cell balancing ) And state of charge (SOC), and to control the safety, charge, or discharge of the energy storage system (ESS). The battery management system (BMS) 200 may balance (equalize) the voltages of the battery cells 51, 52 and 53 of the battery modules 151, 152 and 153.

When the battery cells 51, 52 and 53 are charged and discharged for a long time due to the inherent characteristics of the battery cells 51, 52 and 53, the cell voltages may be different from each other. As a result, the minimum voltage and the maximum voltage exist in the battery modules 151, 152, and 153 including the plurality of battery cells 51, 52, and 53. When the difference is large, overcharge or overdischarge occurs, The life of the module can be shortened sharply. 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 120 is connected to the battery modules 150 and 151 to sense various information and the cell balancing units 130 and 132 perform cell balancing operations of the respective modules based on the sensed information . The measuring unit 120 and the cell balancing unit 130 operate under the control of the controller 110.

The voltage and temperature of the battery modules 151, 152, and 153 can be sensed, and the voltages of the cells can be measured. The measurement unit 120 measures (senses) an open circuit voltage (OCV), which is a charging voltage of each of the battery cells 51, 52 and 53 included in the battery modules 151, 152 and 153 . A battery module (or battery pack) 151, 152, 153 includes battery cells 51, 52, 53 that 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 cells 51, 52, 53 are not discharged or charged, and may be an open circuit voltage for a long period of time. 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 51, 52 and 53 may be connected in series or parallel to each other and each of the battery cells 51, 52 and 53 may be connected to the battery cells 51, 52 and 53 in accordance with the temperature of the battery cell, the number of times of charging and discharging, The charging voltage (or the discharging voltage) may be changed. For example, a cell balancing unit 130 (131, 132) is connected to each of the battery modules 151, 152, 153 having a certain number of battery cells 51, 52, 53, and the cell balancing units 130, 131, 132 and the battery modules 151, 152, 153 Can be detected by the measuring unit 120 (121, 122).

The controller 110 may set a voltage between the open circuit voltages (OCV) measured by the measurement units 120 and 121 as a balancing voltage. The control unit 110 controls the switch 120 to switch between the measurement units 120 and 121 that are higher than the balancing voltage by controlling the switch circuit SW included in the cell balancing units 130 and 131 based on the set balancing voltages Each of the battery cells having the measured open circuit voltage discharges (or discharges) a current so that current is injected into each of the battery cells, which are balanced by the balancing voltage and have an open circuit voltage measured by the measuring unit 120 lower than the balancing voltage So that each of the battery cells having the open circuit voltage measured by the measuring unit 120 lower than the balancing voltage is balanced (charged) with the balancing voltage.

4A and 4B, the switch circuit SW of the cell balancing unit 131 is electrically connected to the resistor R and the switch circuit SW is controlled by the control unit 110 A current output from each of the battery cells 51, 52 and 53 having an open circuit voltage measured by the measuring unit 120 higher than the balancing voltage is discharged to the resistor R, 120 to equalize the charging voltage of each of the battery cells having the open circuit voltage to the balancing voltage.

The switch circuit SW is electrically connected to the current source and the switch circuit SW is controlled by the control unit 110 so that the battery cell having the open circuit voltage measured by the measuring unit 120 lower than the balancing voltage 51, 52, and 53) to charge (charge) the current of the current source to balance the charging voltage of each of the battery cells having the open circuit voltage measured by the measuring unit 120 lower than the balancing voltage with the balancing voltage . The switch circuit SW may include a FET, a semiconductor element, or a contact switch such as a relay. The switch circuit SW may serve to connect or disconnect power flowing into the battery cell.

The battery management system (BMS) 200 according to an embodiment of the present invention may include a module balancing unit 140 (141, 142). A voltage deviation may occur between the battery modules depending on the external temperature or the storage state when the battery module 150 is stored. Here, the controller 110 may switch the battery management system to a sleep mode in order to minimize the voltage deviation between the battery modules and reduce the current consumption. In addition, the cell balancing operation balances the deviation between the battery cells. When a voltage deviation occurs between the modules, the cell balancing unit 130 (131, 132) There is a problem in that the process is complicated and unnecessary cell balancing is performed because it proceeds through an iterative process of reducing the deviation between balancing.

The module balancing unit 140 (141, 142) according to an embodiment of the present invention may be connected to each battery module 151, 152. The module balancing unit 140 (141, 142) is a DC / DC converter that detects a voltage deviation between the battery modules 150 (151, 152) in the measurement unit 120 when a voltage deviation occurs between the battery modules, The control unit 110 transmits control signals to the balancing module unit 140 (141, 142). At this time, the control unit 110 transmits the control signals S1 and S2, and the battery module 140 having a relatively large voltage from the voltage deviation detected by the control signal discharges, Low voltage can be charged. Thus, unnecessary cell balancing can be prevented and the life of the battery pack can be increased.

In addition, the balancing module 140 can check the abnormality of the cells in each battery module 150 through balancing among the modules. Also, the balancing module unit 140 can reduce unnecessary cell balancing.

5, the module balancing unit 140 is connected to both ends of the battery modules 151 and 152 to transmit a predetermined constant voltage / constant current (VC: CC / CV). The measurement unit 120 receives the control signal of the controller 110 and transmits the control signals S1 and S2 to the module balancing unit 140 through the control terminal.

In this case, the module balancing unit 140 may include a converter L 1 and a switch SW 1 connected to the converter L 1. A high voltage is supplied to the primary winding of the converter L1 and the high voltage is down-converted to the secondary winding to supply the charging voltage to each battery module with the CC / CV voltage. At this time, the switch unit SW1 is connected to the other end of the primary winding of the converter L1 and can be turned on or off by the control signals S1 and S2. Therefore, when a voltage deviation occurs between the battery modules 150 (151, 152), the voltage supplied to the converter L 1 by the control signals S 1, S 2 can be down converted to be charged or cut off. With this operation, a relatively low voltage is charged in each battery module, and the voltage of some battery modules is compensated to reduce the voltage deviation between the battery modules.

The controller 110 controls the overall operation of the battery management system (BMS) 200 including a measuring unit 120, a cell balancing unit 130 and a module balancing unit 140 as a central processing unit (CPU) . Accordingly, balancing between the battery cells and balancing between the battery modules can reduce the deviation between the modules in the battery pack.

6 is an example of a battery module balancing method according to an embodiment of the present invention.

Referring to FIGS. 5 and 6, the battery management system detects (301) the voltage of each battery module through each measurement unit, calculates a voltage difference of each of the detected battery modules (303) The battery module is detected 305 and the control signals S1 and S2 are transmitted to the battery module having the detected voltage.

With this control signal, the module balancing unit is driven, and the detected voltage compensates for the voltage level of the low battery module (307). This operation can be repeated to minimize or eliminate voltage variations between the modules.

Embodiments of the present invention can reduce the deviation between battery modules, thereby increasing the recycling rate of the battery module and increasing the service life of the battery module. In addition, even when a battery module having an abnormal voltage level is coupled, the deviation can be compensated and the battery replacement cost can be lowered. Further, each of the module balancing units is controlled to control the charging operation of the individual battery modules, thereby reducing the deviation between the modules, and the efficiency of the circuit itself can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

100: Battery management system
110:
120:
130: cell balancing unit
140: Module balancing unit
150: Battery module section
151, 152, 153: Battery module
51, 52, 53:

Claims (5)

A measurement unit for measuring temperature and voltage of battery cells included in each of the battery modules;
A cell balancing unit for balancing a voltage deviation between cells of the battery module;
A module balancing unit for compensating for a voltage deviation between the battery modules; And
And a controller for controlling the measuring unit, the cell balancing unit, and the module balancing unit,
Wherein the module balancing unit is connected to both ends of the battery module and charges or blocks the constant voltage / constant current of the battery modules. The method according to claim 1,
Wherein the module balancing unit charges a battery module having a relatively low voltage. 3. The method of claim 2,
Wherein the module balancing unit includes a converter for down-converting the supplied DC voltage to supply a constant voltage / constant current to each battery module, and a switch unit for controlling the operation of the converter. The method of claim 3,
The switch portion being connected to the other end of the primary winding of the converter,
And performs an on or off operation based on a control signal received from the control unit. Detecting a voltage of each battery module having a plurality of battery cells;
Calculating a voltage difference between the battery modules;
Detecting a battery module having a low voltage as a result of the calculation; And
And operating the module balancing unit of the detected battery module to charge the detected battery module with a constant voltage / constant current.

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