Patent Grant
10566816
This application claims priority to and the benefit of Korean Patent Application No. 10-2016-0106174, filed on Aug. 22, 2016, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
Aspects of the present disclosure relate to a battery charging method and a battery charging apparatus using the battery charging method.
Resistance of a battery has a non-linear characteristic that varies during a charging process, according to a C-rate, a state of charge (SOC), temperature, and/or the like. Among battery charging methods according to the related art, a step constant current (CC)/constant voltage (CV) charging method generates linear stress in a CC section, thereby generating a plurality of sections in which by-products are generated.
In addition, even when the lifespan of the battery degrades and resistance increases during the CC section, current of the same magnitude is applied, which may cause additional deterioration. Also, according to the step CC/CV charging method, if there is a difference between the performances of cells constituting a battery pack unit, over-charging and over-discharging concentrate in some of the cells, thereby degrading the total performance of the battery pack.
Aspects of one or more embodiments are directed to a battery charging method capable of increasing the lifespan of a battery, by decreasing stress elements applied during charging of a battery and applying electric current corresponding to characteristics of each cell constituting a battery pack, and a battery charging apparatus employing the battery charging method.
Aspects of one or more embodiments are directed to a battery charging method, by which a battery is charged with a constant stepwise voltage that is a charging voltage determined by taking into account a characteristic of varying resistance during the charging of the battery, and the battery charging apparatus employing the battery charging method.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.
According to one or more embodiments, there is provided a method of charging a battery, wherein the battery comprises a plurality of battery cells, the method including: charging the battery with a first voltage for a first time period, which charging is first charging; charging the battery with a second voltage for a second time period, which charging is second charging; and charging the battery with a third voltage for a third time period, which charging is third charging, wherein lengths of the first to third time periods are determined in correspondence with a magnitude of charging current of the battery.
In some embodiments, the lengths of the first time period, the second time period, and the third time period are time periods taken for a value of the charging current in the first, second, and third charging to reach a first threshold value, a second threshold value, and a third threshold value, respectively.
In some embodiments, the first threshold value is equal to or greater than the second threshold value, and the second threshold value is equal to or greater than the third threshold value.
In some embodiments, the first to third threshold values are charging current values at a time point when an internal resistance value of the battery is stabilized in the first charging, the second charging, and the third charging, respectively.
In some embodiments, the method further includes determining magnitudes of the first to third voltages.
In some embodiments, the determining of the magnitudes of the first to third voltages includes determining the magnitudes of the first to third voltages as voltage values, each of the voltage values being included in a voltage range corresponding to a peak point in an internal resistance variation curve, against time, of the battery.
According to one or more embodiments, there is provided a battery charging apparatus for a battery, wherein the battery includes a plurality of battery cells, the battery charging apparatus including: a memory configured to store information about magnitudes of a first voltage, a second voltage, and a third voltage that are charging voltages for charging the battery, wherein the battery is charged with the first voltage, the second voltage, and the third voltage respectively within a first time period, a second time period, and a third time period, and lengths of the first to third time periods correspond with a magnitude of charging current of the battery.
In some embodiments, the lengths of the first to third time periods are time periods taken for a value of the charging current in the first to third time periods to respectively reach a first threshold value, a second threshold value, and a third threshold value.
In some embodiments, the first threshold value is equal to or greater than the second threshold value, and the second threshold value is equal to or greater than the third threshold value.
In some embodiments, the first to third threshold values are charging current values at a time point when an internal resistance value of the battery is stabilized in respective charging stages.
In some embodiments, magnitudes of the first to third voltages are voltage values, each of the voltage values being included in a voltage range corresponding to a peak point in an internal resistance variation curve, against time, of the battery according to time.
These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:
Exemplary embodiments will be described in more detail below with reference to accompanying drawings. However, the present disclosure may be implemented in various aspects, and should not be construed to be limited to one or more embodiments provided herein. The embodiments are provided for complete disclosure and thorough understanding of the invention by those skilled in the art.
Hereinafter, one or more exemplary embodiments will be provided with reference to accompanying drawings. Like reference numerals denote the same elements. In the drawings, like reference numerals are provided to the same or corresponding elements, and descriptions thereof are not repeated.
Referring to
The battery may include a plurality of battery cells that may be charged and discharged, and may configure a battery pack with a switch and a controller.
The switch may include a charging switch and a discharging switch that are turned on/off by receiving control signals output from the controller, and when the charging switch is in a turn-on state, charging current supplied from the charger 100 is input to the battery.
In addition, when the discharging switch is in a turn-on state, discharging current output from the battery is transferred to a system or a load connected to the battery pack.
The controller monitors a state of the battery, and controls switching operations of the switch. Status information of the battery monitored by the controller may include a cell voltage, temperature, current, and/or the like. A charging capacity, remaining lifespan, and/or the like of the battery may be calculated based on the status information of the battery.
The charger 100 includes a memory that stores information about magnitudes of a first voltage V1, a second voltage V2, and a third voltage V3 that are charging voltages for charging the battery.
In addition, the charger 100 charges the battery with the first voltage V1, the second voltage V2, and the third voltage V3 respectively for a first time period, a second time period, and a third time period. Lengths of the first time period, the second time period, and the third time period are determined based on a magnitude of the charging current of the battery.
For example, the lengths of the first time period, the second time period, and the third time period may be the time taken for the charging current in the respective time periods to reach a first threshold value, a second threshold value, and a third threshold value.
For example, when the magnitude of the charging current reaches the first threshold value while the battery is charged with the first voltage V1, the charger 100 charges the battery with the second voltage V2.
When the battery is charged by applying a voltage of a constant magnitude, the magnitude of the charging current supplied to the battery gradually decreases, and when the magnitude of the charging current reaches the threshold value set in advance, the magnitude of the charging voltage may be switched to a voltage of a next stage determined in advance.
Therefore, the lengths of the first to third time periods are not determined in advance, and may be set as the time taken to reach the first to third threshold values.
Referring to the graph of
In the graph of
In addition, the first voltage V1 is applied during the first time period (0 to t1), the second voltage V2 is applied during the second time period (t1˜t2), and the third voltage V3 is applied during the third time period (t2˜t3).
As described above, the lengths of the first to third time periods are not determined in advance, and the charging voltage is applied to the battery until a time point when the magnitude of the charging current supplied to the battery reaches the threshold value set in advance.
In the graph of
As described above, the magnitude of the charging current gradually decreases from the time point when the charging voltage is applied from the charger during the charging of the battery.
During the first time period (0˜t1), the magnitude of the charging current supplied to the battery decreases gradually, and when the magnitude of the charging current reaches a first threshold value I1, the second voltage V2 is applied to the battery. During the second time period (t1˜t2), the second voltage V2 is applied as the charging voltage, and the magnitude of the charging current gradually decreases during the second time period (t1˜t2), and thus, when the magnitude of the charging current reaches a second threshold value I2, the third voltage V3 is applied to the battery.
Likewise, the third voltage V3 is applied as the charging voltage during the third time period (t2˜t3), and the magnitude of the charging current gradually decreases during the third time period (t2˜t3) and when the magnitude reaches a threshold value I3, the charging of the battery may be finished.
As shown in the graph of
In addition, the first to third threshold values I1, I2, and I3 may be determined as values of the charging current at a time point when an internal resistance value of the battery is stabilized in corresponding charging stages. In an example, the first to third threshold values I1, I2, and I3 may be determined as values of the charging current at a time point when battery cells included in the battery are stabilized.
Therefore, the magnitudes of the charging voltages V1, V2, and V3 described above with reference to
Referring to
In the first charging operation (S110), the battery is charged with the first voltage V1 for the first time period (0˜t1), in the second charging operation (S120), the battery is charged with the second voltage V2 for the second time period (t1˜t2), and in the third charging operation (S130), the battery is charged with the third voltage V3 for the third time period (t2˜t3). Here, the lengths of the first to third time periods are determined in correspondence with the magnitudes of the charging current of the battery.
For example, the lengths of the first time period (0˜t1), the second time period (t1˜t2), and the third time period (t2˜t3) may be time for the charging current values in the respective time periods to reach the first, second, and third threshold values.
For example, when the magnitude of the charging current reaches the first threshold value while the battery is charged with the first voltage V1, the battery is charged with the second voltage V2.
When the battery is charged by applying a voltage of a constant magnitude, the magnitude of the charging current supplied to the battery gradually decreases, and when the magnitude of the charging current reaches the threshold value set in advance, the magnitude of the charging voltage may be switched to a voltage of a next stage, which is determined in advance.
Therefore, the lengths of the first to third time periods are not determined in advance, and may be set as the time taken to reach the first to third threshold values.
As described above with reference to
Likewise, the third voltage V3 is applied as the charging voltage during the third time period (t2˜t3), and the magnitude of the charging current gradually decreases during the third time period (t2˜t3) and when the magnitude reaches a threshold value I3, the charging of the battery may be finished.
As shown in the graph of
In addition, the first to third threshold values I1, I2, and I3 may be determined as values of the charging current at a time point when an internal resistance value of the battery is stabilized in corresponding charging stages. In an example, the first to third threshold values may be determined as values of the charging current at a time point when battery cells included in the battery are stabilized.
Therefore, the magnitudes of the charging voltages V1, V2, and V3 described above with reference to
Referring to
In the operation of determining the charging voltage (S210), a magnitude of the charging voltage for charging the battery is determined. The magnitude of the charging voltage may be determined as a voltage corresponding to a peak in a temporal variation curve of voltage versus battery resistance.
As described above with reference to accompanying drawings, the battery charging method and the battery charging apparatus employing the method according to the embodiment are characterized in that the battery is charged by applying in stages the charging voltages that are determined in advance.
Here, the magnitude of the charging voltage is determined as the voltage corresponding to the peak in the temporal variation curve of the voltage versus resistance, as shown in
In the curve shown in
In an embodiment, a certain voltage value within a voltage range including the voltage V1 may be determined as the charging voltage. For example, a voltage within a range of 99% to 101% with respect to the voltage V1 corresponding to the peak may be determined as the charging voltage. In an embodiment, a voltage corresponding to a 3 dB range (e.g., a 3 dB drop) with respect to the peak may be determined as the charging voltage.
Referring to
In addition, in a result shown in
The graph of
That is, referring to
Therefore, when the battery is charged by the battery charging method according to the present disclosure, the lifespan of the battery may increase without affecting the charging time, when compared with the charging method (step CC/CV charging) according to the related art.
According to the battery charging method and the battery charging apparatus employing the method of the present disclosure, the lifespan of the battery may be increased by reducing the stress component applied during the charging of the battery and by applying the electric current corresponding to a characteristic of each of the cells configuring the battery pack.
It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.
The terms used in the present specification are merely used to describe particular embodiments, and are not intended to limit the present disclosure. An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context. In the present specification, it is to be understood that the terms such as “including,” “having,” and “comprising” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, numbers, steps, actions, components, parts, or combinations thereof may exist or may be added. It will be understood that although the terms “first,” “second,” etc. may be used herein to describe various components, these components should not be limited by these terms. These components are only used to distinguish one component from another.
As used herein, the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Further, the use of “may” when describing embodiments of the inventive concept refers to “one or more embodiments of the inventive concept.” Also, the term “exemplary” is intended to refer to an example or illustration.
The battery charging apparatus and/or any other relevant devices or components, such as the controller, according to embodiments of the present invention described herein may be implemented utilizing any suitable hardware, firmware (e.g. an application-specific integrated circuit), software, or a suitable combination of software, firmware, and hardware. For example, the various components of the battery charging apparatus may be formed on one integrated circuit (IC) chip or on separate IC chips. Further, the various components of the battery charging apparatus may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on a same substrate. Further, the various components of the battery charging apparatus may be a process or thread, running on one or more processors, in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functionalities described herein. The computer program instructions are stored in a memory which may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-transitory computer readable media such as, for example, a CD-ROM, flash drive, or the like. Also, a person of skill in the art should recognize that the functionality of various computing devices may be combined or integrated into a single computing device, or the functionality of a particular computing device may be distributed across one or more other computing devices without departing from the scope of the exemplary embodiments of the present invention.
While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims and equivalents thereof.
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