Serial charge / discharge device and charge / discharge method using the same

Abstract

The serial charging / discharging device according to the present invention is for charging / discharging a plurality of battery cells connected in series, and includes a tray, a cooling fan, a power source, a charge / discharge control board, and a control unit. The charge / discharge control algorithm installed in the control unit is composed of 1st to Nth (N is an integer from 2 to 10) charge / discharge stages, and each charge / discharge stage is configured to charge / discharge in a constant current mode and to gradually decrease the charge / discharge current value. The series-type charge / discharge device according to the present invention is configured to perform charge / discharge steps in constant current mode in multiple stages and reduce the charge / discharge current value in each charge / discharge step, thereby achieving an effect similar to that of charge / discharge in constant voltage mode. However, since it is not necessary to repeat charge / discharge in constant voltage mode for the number of batteries connected in series, the time required for charge / discharge can be reduced accordingly.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0110611, dated September 1, 2022, and Korean Patent Application No. 10-2023-0113881, dated August 29, 2023.

[0002] The present invention relates to an apparatus for charging and discharging a plurality of battery cells connected in series and a charging and discharging method using the same. [Background technology]

[0003] A secondary battery is a battery that can be repeatedly charged and discharged. A secondary battery can be considered a process for producing electrical energy, in other words, a process in which electrons are transferred through a reversible oxidation-reduction reaction via the electrolytes of two electrodes with a large difference in ionization tendency.

[0004] Typically, charging / discharging devices for lithium secondary batteries charge batteries using a constant current / constant voltage charging method. The constant current / constant voltage charging method refers to a method in which a battery is charged at a constant current up to a target voltage and then at a constant voltage once the target voltage is reached. Therefore, in this constant current / constant voltage charging method, the charging current curve over time roughly shows a constant current when the battery is below the target voltage and then exponentially decreases after the battery reaches the target voltage. Furthermore, the charging voltage curve over time roughly shows a logarithmic increase around the inflection point of the target voltage and then remains constant at the target voltage once the battery reaches the target voltage. When the charging current flowing through the battery gradually decreases and reaches a certain current value (e.g., 0.1 C to 0.3 C), the battery is determined to be fully charged and charging is stopped.

[0005] This constant voltage / constant current charging / discharging method has the disadvantage that the charging time is long in the constant voltage charging / discharging section due to the characteristics of the battery, which increases the overall charging time.

[0006] Meanwhile, there are two types of chargers: parallel and series. Parallel chargers have separate power supplies for each battery channel and are configured to charge and discharge by controlling the current and voltage for each battery channel. Series chargers, on the other hand, have the advantage of being more energy efficient because the battery channels are connected in series and the current can be controlled for all battery channels at once.

[0007] However, because a series-type charger / discharger charges and discharges multiple batteries connected in series, each with slightly different capacities and internal resistances, it is difficult to charge and discharge each battery at a constant voltage due to differences in battery characteristics. Therefore, when a series-type charger / discharger performs constant voltage / constant current charging and discharging, it controls the current of all channels to the same value to charge and discharge at a constant current. However, when charging and discharging in constant voltage mode, it is difficult to uniformly control the voltage of all channels, so it controls the charging and discharging of each battery channel by switching relays. As a result, conventional series-type charger / dischargers take a long time to charge and discharge in constant voltage mode.

[0008] Therefore, there is a need for technological development of a charging / discharging device and method that can reduce the time required to charge and discharge a large number of secondary batteries using a series charger / discharger. Summary of the Invention [Problem to be solved by the invention]

[0009] The problem to be solved by the technical idea of ​​the present invention is to provide a serial-type charge / discharge device for charging / discharging a plurality of serially connected battery cells, which reduces the time required for charging / discharging in a constant voltage mode when charging / discharging in a constant current-constant voltage (CC-CV) mode. [Means for solving the problem]

[0010] According to one embodiment of the present invention, there is provided a series-type charge / discharge device for charging / discharging a plurality of battery cells connected in series, the series-type charge / discharge device including one or more trays for accommodating the plurality of battery cells, a cooling fan for regulating the temperature of the plurality of battery cells being charged / discharged, a power source for providing charge / discharge currents to the plurality of battery cells and current to the cooling fan, a charge / discharge control board for controlling the charge / discharge currents of each of the plurality of battery cells, and a controller having a charge / discharge control algorithm, the charge / discharge control algorithm including first to Nth charge / discharge stages (N is an integer between 2 and 10), each of which is configured to charge / discharge in a constant current mode and gradually decrease the charge / discharge current value.

[0011] In one embodiment, the charge / discharge control algorithm is configured to charge / discharge the series-connected battery cells in a constant current mode in each charge / discharge step, cut off the current flowing to each battery cell that has reached a target voltage, and cut off the current when the last battery cell that has not reached the target voltage reaches the target voltage.

[0012] In one embodiment, the charge / discharge control board includes a charge / discharge switch connected in series to each of the battery cells, a bypass switch connected to both ends of the charge / discharge switch, and a switch controller that controls the on / off operations of the charge / discharge switch and the bypass switch.

[0013] According to one embodiment, the series-type charging / discharging device further includes a voltage sensing unit configured to sense the voltage of each of the plurality of battery cells and send the sensed voltage information to the control unit, and the control unit controls the switch controller to turn off the charging / discharging switch connected in series to the battery cell and turn on the bypass switch to bypass the charging / discharging current of the battery cell whenever a battery cell reaches a cut-off voltage based on the voltage information received from the voltage sensing unit.

[0014] In one embodiment, the charge / discharge control board is disposed in a space on a side of the cooling fan.

[0015] In one embodiment, the cooling fan includes an upper cooling fan disposed above the tray in a direction perpendicular to the ground, and a lower cooling fan disposed below the tray in a direction perpendicular to the ground.

[0016] The series charging / discharging device of one embodiment further includes a first charging / discharging module having a plurality of first connection members for connecting with each first electrode lead of the plurality of battery cells, and a second charging / discharging module having a plurality of second connection members for connecting with each second electrode lead of the plurality of battery cells.

[0017] In one embodiment, the charge / discharge control board includes a first charge / discharge control board connected to the first charge / discharge module, and a second charge / discharge control board connected to the second charge / discharge module.

[0018] In one embodiment, the tray is disposed between the first charge / discharge module and the second charge / discharge module with respect to a direction horizontal to the ground.

[0019] In one embodiment, the first charging / discharging module is configured to be movable in the direction of the plurality of first electrode leads and in the opposite direction, and the second charging / discharging module is configured to be movable in the direction of the plurality of second electrode leads and in the opposite direction.

[0020] In one embodiment, the plurality of first connection members are configured to press both sides of the first electrode lead, respectively, and the plurality of second connection members are configured to press both sides of the second electrode lead, respectively.

[0021] In one embodiment, the charge / discharge control algorithm is configured such that a reference current value for completely terminating charge / discharge is set, and the current value of the final charge / discharge stage is set to be equal to the reference current value.

[0022] In one embodiment, there are two or more trays, and the trays are configured to be stackable in a direction perpendicular to the ground.

[0023] According to another embodiment of the present invention, there is provided a method for charging and discharging a battery cell using the above-described series charge / discharge device. [Effects of the Invention]

[0024] A series-type charging / discharging device according to an exemplary embodiment of the present invention can simultaneously charge and discharge a plurality of battery cells connected in series at a constant current, and can control the current supply to be sequentially cut off for battery cells that have reached a cutoff voltage, thereby preventing overcharging / overdischarging.

[0025] In addition, compared to conventional series-type charge / discharge devices that charge / discharge in constant current / constant voltage mode, there is no need to repeat constant voltage mode charge / discharge for the number of series-connected batteries, which reduces the time required for charge / discharge. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a block diagram of a series charging / discharging device according to an exemplary embodiment of the present invention; [Figure 2] 1 is a front view of a series charging / discharging device according to an exemplary embodiment of the present invention; [Figure 3] FIG. 2 is a conceptual diagram for explaining a charge / discharge control algorithm according to an embodiment of the present invention. [Figure 4] 1 is a configuration diagram of a series-type charge / discharge device according to an embodiment of the present invention; [Figure 5] 4 is a flowchart illustrating a charge / discharge control algorithm according to an embodiment of the present invention. [Figure 6] 4 is a graph showing charge / discharge current values ​​according to time applied to one battery cell when charging / discharging is performed according to the charge / discharge control algorithm of the present invention. [Figure 7] FIG. 10 is a block diagram of a series charging / discharging device according to another embodiment of the present invention. [Figure 8] FIG. 10 is a perspective view of a charge / discharge module according to another embodiment of the present invention. [Figure 9] FIG. 10 is a top view of a series charge / discharge device according to another embodiment of the present invention. [Figure 10] FIG. 10 is a side view of the charge / discharge module shown in FIG. 9. DETAILED DESCRIPTION OF THE INVENTION

[0027] The terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concepts of terms in order to best describe his own invention.

[0028] Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can replace them at the time of this application.

[0029] Furthermore, in the description of the present invention, if it is determined that a detailed description of related publicly known structures or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0030] Throughout the specification, when a part "comprises" a certain element, this does not mean that it excludes other elements, but that it may further include other elements, unless specifically stated to the contrary.

[0031] In the present specification, the terms "lithium secondary battery", "secondary battery", and "battery" are used interchangeably to mean the same thing.

[0032] Furthermore, the term "controller" or the like used in the specification means a unit that processes at least one function or operation, and this may be embodied in hardware, software, or a combination of hardware and software.

[0033] Furthermore, throughout this specification, when a part is said to be "connected" to another part, this includes not only "directly connected" but also "indirectly connected" with another element in between.

[0034] The present invention provides a series-type charge / discharge device as a first embodiment.

[0035] FIG. 1 is a block diagram of a series charging / discharging device according to an exemplary embodiment of the present invention, and FIG. 2 is a front view of the series charging / discharging device according to an exemplary embodiment of the present invention.

[0036] Referring to Figures 1 and 2, a series charging / discharging device 100 according to an exemplary embodiment of the present invention may include a tray 110, a cooling fan 120, a power supply 130, a charging / discharging control board 140, and a control unit 150.

[0037] According to an exemplary embodiment of the present invention, the control unit 150 is equipped with a charge / discharge control algorithm, which consists of 1st to Nth (N is an integer between 2 and 10) charge / discharge stages, and each charge / discharge stage is configured to charge / discharge in a constant current mode and to gradually decrease the charge / discharge current value.

[0038] In order to charge and discharge in a constant current / constant voltage mode using a conventional series-type charge / discharge device, multiple battery cells connected in series are charged and discharged in constant current mode. When a battery cell reaches a target voltage first, not only the battery cell that first reached the target voltage but also the remaining battery cells that did not reach the target voltage are charged and discharged in constant voltage mode. At this time, the remaining battery cells are charged and discharged with a reduced current. Then, when the constant voltage mode charge and discharge of the battery cell that first reached the target voltage is completed, the charge and discharge of that battery cell is terminated, and the same process is repeated for the remaining battery cells. In this case, since the constant voltage mode charge and discharge must be repeated for each battery cell connected in series, there is a problem in that the overall charge and discharge time is long.

[0039] The present invention introduces a multi-stage constant current charging / discharging method that can replace constant voltage mode charging / discharging in charging / discharging multiple battery cells connected in series in constant current-constant voltage (CC-CV) mode, thereby reducing the time required for charging / discharging.

[0040] The charge / discharge control algorithm according to one embodiment of the present invention is configured to charge / discharge a plurality of battery cells in multiple stages, and each charge / discharge stage is performed in a constant current mode, with the charge / discharge current value being gradually reduced.

[0041] In one specific example, the charge / discharge steps may include 2 to 10 steps, specifically 3 to 8 steps, and more specifically 4 to 7 steps.

[0042] 3 is a conceptual diagram illustrating a charge / discharge control algorithm according to an embodiment of the present invention. Referring to FIG. 3, the charge / discharge steps according to the embodiment may include five charge / discharge steps, in which a first charge / discharge step (step 1) performs constant current charging at a current value of Ia, a second charge / discharge step (step 2) performs constant current charging at a current value of Ib, a third charge / discharge step (step 3) performs constant current charging at a current value of Ic, a fourth charge / discharge step (step 4) performs constant current charging at a current value of Id, and a fifth charge / discharge step (step 5) performs constant current charging at a current value of Ie, and the current values ​​in each charge / discharge step satisfy the following relationship:

[0043] Ia>Ib>Ic>Id>Ie

[0044] Specifically, the current values ​​Ia to Ie can be set to 1C, 0.8C, 0.6C, 0.4C, and 0.2C.

[0045] In this charge / discharge control algorithm, each charge / discharge section is charged / discharged in constant current mode, and the charge / discharge current value is set to decrease stepwise through multiple charge / discharge stages. Therefore, the second charge / discharge stage to the Nth charge / discharge stage have an effect similar to that of constant voltage mode charge / discharge overall. However, since each charge / discharge stage is charged / discharged in constant current mode, there is no need to repeat constant voltage mode charge / discharge, which reduces the time required for charge / discharge.

[0046] However, even for battery cells of the same model, there are slight differences in capacity and resistance between battery cells, so when multiple battery cells connected in series are charged and discharged at a constant current, the time it takes for each battery cell to reach a target voltage varies. In other words, the multiple battery cells do not reach the target voltage simultaneously, but rather reach the target voltage sequentially with a time difference.

[0047] If a charging / discharging current is continuously supplied to a battery cell that has reached the target voltage, overcharging or overdischarging may occur. Therefore, the series-type charging / discharging device 100 according to the present invention controls charging / discharging by cutting off the current flowing to the battery cell each time a battery cell that has reached the target voltage is encountered in each charging / discharging stage, and by cutting off the current when the last battery cell that has not reached the target voltage reaches the target voltage.

[0048] The series-type charging / discharging device 100 according to one embodiment may include a switch to cut off the charging / discharging current flowing to each battery cell or to supply the charging / discharging current to the battery cell.

[0049] 4 is a configuration diagram of a series-type charging / discharging device according to an embodiment of the present invention. Referring to FIG. 4, the device may include a charging / discharging switch 141 connected in series to each of the battery cells (B1, B2, ... Bn), and a bypass switch 142 connected to both ends of the charging / discharging switch 141.

[0050] When a battery cell reaches a target voltage during charging / discharging in a constant current mode, the controller 150 may control the bypass switch 142 of the battery cell that has reached the target voltage to be turned on and the charge / discharge switch 141 of the battery cell that has reached the target voltage to be turned off so that a charge / discharge current is not supplied to the battery cell that has reached the target voltage. As a result, the charge / discharge current flowing to the battery cell that has reached the target voltage is cut off, and the charge / discharge current may be continuously supplied to the remaining battery cells.

[0051] If the current flowing through a battery cell is cut off each time a battery cell reaches the target voltage during constant current charging and discharging, the last battery cell whose charge / discharge switch 141 is not turned off will eventually reach the target voltage. The charge / discharge control algorithm of the present invention is set to cut off constant current charging of the current value when the last battery cell reaches the target voltage, thereby ending one charge / discharge stage.

[0052] When one charge / discharge stage is completed, in order to perform the next charge / discharge stage at a current value with a reduced charge / discharge current value, the control unit controls all charge / discharge switches of the plurality of battery cells to be in an on state after cutting off one charge / discharge stage, so that a charge / discharge current flows to all battery cells when the next charge / discharge stage starts.

[0053] 6 is a diagram showing the charge / discharge current value as a function of time applied to one battery cell when charging / discharging is performed according to the charge / discharge control algorithm of the present invention. Referring to FIG. 6, any battery cell that is charged / discharged according to the charge / discharge control algorithm of the present invention is charged / discharged at a constant current in a relay-on state where the charge / discharge switch is on, and when the target voltage is reached, the charge / discharge switch is switched to a relay-off state where the charge / discharge switch is off, thereby cutting off the charge / discharge current. The battery cell that was in the relay-off state is then switched back to the relay-on state to perform the next charge / discharge step, and the charge / discharge current value applied at this time is set to be smaller than the charge / discharge current value of the previous charge / discharge step.

[0054] The charge / discharge control algorithm of the present invention is set so that a reference current value for completely terminating charge / discharge is set, and charge / discharge is completely terminated at the cutoff point of the charge / discharge stage at the reference current value.

[0055] That is, while charging and discharging in constant current mode in one charge / discharge stage, whenever a battery reaches the target voltage, the current flowing to that battery is cut off, and when the last battery that has not reached the target voltage reaches the target voltage, a cut-off process is performed. This process is repeated for each charge / discharge stage, and when the charge / discharge current value reaches the reference current value, the charge / discharge is completely terminated in the charge / discharge stage where charging and discharging are performed at the reference current value.

[0056] For example, if the charge / discharge control algorithm consists of five charge / discharge stages, from the first charge / discharge stage to the fifth charge / discharge stage, the charge / discharge current values ​​of each charge / discharge stage are Ia, Ib, Ic, Id, and Ie, and the reference current value is set to Ie, then charging / discharging will be completely completed when the fifth charge / discharge stage is completed.

[0057] In each charging / discharging stage, the on / off states of the charging / discharging switches and bypass switches connected to each of the plurality of battery cells can be controlled by the control unit, or by a switch controller for controlling the on / off operations of the charging / discharging switches and bypass switches.

[0058] Each component of the series-type charging / discharging device 100 of the present invention will be described in detail below.

[0059] 2, the charging / discharging device 100 is provided with frames 180. The frames 180 may be connected to each other to form a box-shaped framework. A power supply 130 (described later) may be disposed below the frame 180 in a direction perpendicular to the ground (Z direction), and a tray 110, a cooling fan 120, and a charge / discharge control board 140 may be disposed above the power supply 130. In this manner, the charging / discharging device 100 may be an integrated structure in which the power supply 130, the tray 110, the cooling fan 120, the charge / discharge control board 140, and the control unit 150 are assembled on one frame 180.

[0060] The tray 110 is for accommodating a plurality of battery cells, and one tray may include a plurality of battery cell storage compartments (not shown) in which the battery cells are attached. The tray may be installed in the battery cell storage compartments in a state where the battery is vertically erected relative to the ground. The tray may have an open top for easy removal of the battery cells.

[0061] The number of trays 110 may be one or two or more, and when there are two or more trays 110, the trays 110 may be configured to be stackable based on a direction perpendicular to the ground (Z direction) in order to accommodate as many trays as possible in the limited space of the charging / discharging device 100. For example, based on the direction perpendicular to the ground, a first tray 111 may be stacked below, and a second tray 112 may be stacked above the first tray, and a mounting portion (not shown) may be formed in the first tray 111 to securely mount the second tray 112 stacked above.

[0062] The cooling fan 120 may serve to adjust the temperature of the battery cells B that are being charged or discharged. The cooling fan may be configured to blow air toward a lower portion where the battery cells B mounted on the tray are located, thereby cooling the battery cells through the tray 110 with an open top.

[0063] In one embodiment, the cooling fan 120 may include an upper cooling fan disposed above the tray in a direction perpendicular to the ground (Z direction) and a lower cooling fan disposed below the tray in a direction perpendicular to the ground, but is not limited thereto, and additional cooling fans may be disposed on the sides of the tray.

[0064] In order to maintain the temperature of the battery cell at a set value during charging / discharging, the charging / discharging device 100 may additionally include a temperature sensor (not shown) for measuring the temperature of the battery cell B. The temperature sensor may be configured to measure the temperature of the battery cell B in real time during charging / discharging and send the measured temperature value to the control unit 150. If the temperature received from the temperature sensor is too high or too low, the control unit 150 may control the rotation speed of the cooling fan 120, etc., to maintain the ambient temperature of the battery cell B within a preset temperature range during charging / discharging.

[0065] The power supply 130 is for providing charging / discharging current to the plurality of battery cells B and for providing current to the cooling fan 120. In one embodiment, the power supply 130 may include a power conversion unit (not shown) that converts output power supplied from a current source into power suitable for charging / discharging the battery cells B.

[0066] The power conversion unit may include an AC / DC converter and a DC / DC converter to convert the output power supplied from the power supply 130 into power suitable for charging and discharging the battery cells. The AC / DC converter may primarily convert the AC power into DC power, and the DC / DC converter may supply a precise charge / discharge current from the DC power to each battery cell.

[0067] The power source 130 may be electrically connected to a plurality of battery cells B via a plurality of power cables (not shown). Referring to FIG. 2, a space in which the battery cells B are disposed and a space in which the power source 130 is disposed may be separated by the partition wall 181. The AC / DC converter and the DC / DC converter may both be disposed in a lower space separated by the partition wall 181. In this case, since the DC / DC converter is located far from the battery cells B, the total length of the power cables connecting the power source 130 and the battery cells B may be long.

[0068] In one embodiment, the DC / DC converter may be disposed in proximity to the tray 110 or the cooling fan 120. In this case, the AC / DC converter and the DC / DC converter are separated, thereby reducing the space occupied by the power supply 130, and the DC / DC converter is disposed in proximity to the battery cells, thereby minimizing the length of the power cable for electrically connecting the power supply 130 and the battery cells.

[0069] The charge / discharge control board 140 controls the charge / discharge current of each of the battery cells, includes a charge / discharge circuit for each of the battery cells, and may constitute the DC / DC converter.

[0070] The charge / discharge control board 140 may be connected to the power source 130 via a power cable. The charge / discharge control board 140 may include charge / discharge switches 141 connected in series to each of the battery cells (B1, B2, ... Bn) to charge / discharge the battery cells according to the charge / discharge control algorithm, bypass switches 142 connected across the charge / discharge switches, and a switch controller 143 that controls the on / off operations of the charge / discharge switches and the bypass switches.

[0071] The charge / discharge control board 140 may include a plurality of channel boards (not shown) and a backplane board (not shown) for accommodating and connecting the channel boards. The backplane board may be configured to output control signals according to a charge / discharge control algorithm installed in the controller, and the channel boards may be configured to charge / discharge each of the plurality of battery cells according to the control signals. A plurality of the channel boards may be arranged on one backplane board and electrically connected to the backplane board.

[0072] The charge / discharge control board 140 may include a first charge / discharge control board 140a corresponding to the first electrode lead B1 of the battery cell B, and a second charge / discharge control board 140b corresponding to the second electrode lead B2 of the battery cell B.

[0073] 2, the charge / discharge control board 140 may be disposed in a space on the side of the cooling fan 120. When the charge / discharge control board 140 is disposed in the space on the side of the cooling fan 120, the charge / discharge control board 140 does not obstruct the flow of air blown by the cooling fan, which is preferable in terms of cooling efficiency for the battery cells.

[0074] The control unit 150 may be configured to incorporate the charge / discharge control algorithm and to manage the controls required for charging and discharging. The control unit 150 may include a built-in CPU and memory, and the charge / discharge control algorithm may include PWM signal control required for charging and discharging, and means required for charging and discharging the battery cells connected in series. PWM signal control means converting a digital signal into an analog signal.

[0075] The series-type charging / discharging device 100 according to an embodiment may further include a voltage sensing unit (not shown) configured to sense the voltage of each of the plurality of battery cells and send the sensed voltage information to the control unit.

[0076] The charge / discharge control algorithm according to the present invention requires that the flow of charge / discharge current be cut off for cells that have reached a target voltage in each charge / discharge stage, and therefore requires a voltage sensing unit for measuring the voltage of each of the plurality of battery cells while charging / discharging is in progress.

[0077] The control unit 150 may control the switch controller 143 to turn off the charge / discharge switch 141 connected in series to the battery cell and turn on the bypass switch 142 to bypass the charge / discharge current of the battery cell whenever the battery cell reaches the cut-off voltage based on the voltage information received from the voltage sensing unit. The cut-off voltages of the plurality of charge / discharge stages are set to be the same.

[0078] FIG. 7 is a block diagram of a series-type charging / discharging device according to another embodiment of the present invention, FIG. 8 is an oblique view of a charging / discharging module according to another embodiment of the present invention, FIG. 9 is a top view of a series-type charging / discharging device according to another embodiment of the present invention, and FIG. 10 is a side view of the charging / discharging module shown in FIG. 9.

[0079] Referring to these drawings, a series charging / discharging device 100 according to another embodiment may include a tray 110, a cooling fan 120, a power supply 130, a charging / discharging control board 140, a control unit 150, and a charging / discharging module 160.

[0080] The tray, cooling fan, power supply, charge / discharge control board, and control unit have already been described in detail, so a duplicate description will be omitted.

[0081] The charging / discharging module 160 is for connecting the power source 130 and each of the battery cells B and may include a first charging / discharging module 161 and a second charging / discharging module 162. The charging / discharging module 160 and the power source 130 may be connected via a power cable. The first charging / discharging module 161 may include a plurality of first connection members 163 for connecting with each of the first electrode leads B1 of the battery cells, and the second charging / discharging module 162 may include a plurality of second connection members 164 for connecting with each of the second electrode leads B2 of the battery cells. In this case, the first electrode lead B1 and the second electrode lead B2 have opposite polarities. That is, if the first electrode lead is a positive lead, the second electrode lead is a negative lead.

[0082] 7 to 9, two trays 111 and 112 accommodating a plurality of battery cells B may be stacked along a direction perpendicular to the ground (Z direction). The trays 111 and 112 may be arranged between the first charge / discharge module 161 and the second charge / discharge module 162 based on a direction parallel to the ground (Y direction). This arrangement is due to the shape of a bidirectional battery in which electrode leads B1 and B2 of the battery cells are drawn in opposite directions.

[0083] The first charging / discharging module 161 is spaced apart from each first electrode lead B1 of the plurality of battery cells B when the first tray 111 and the second tray 112 are mounted inside the charging / discharging device 100, and the second charging / discharging module 162 is spaced apart from each second electrode lead B2 of the plurality of battery cells B. This distance allows the first tray 111 and the second tray 112 to be easily mounted inside the charging / discharging device 100, and after the first tray 111 and the second tray 112 are mounted, the first charging / discharging module 161 and the second charging / discharging module 162 move adjacent to the first tray 111 and the second tray 112 so that the first connecting member 163 and the second connecting member 164 are electrically connected to the battery cells B.

[0084] That is, the first charging / discharging module may be configured to be movable in the direction of the plurality of first electrode leads and in the opposite direction, and the second charging / discharging module may be configured to be movable in the direction of the plurality of second electrode leads and in the opposite direction.

[0085] The first and second connection members may be provided in numbers corresponding to the first and second electrode leads, respectively. Each of the first connection members may be configured to press against both sides of the first electrode lead, and each of the second connection members may be configured to press against both sides of the second electrode lead.

[0086] The first connection member may press the first electrode lead, and the second connection member may press the second electrode lead, electrically connecting the power source and the battery cell. A voltage sensing connector (not shown) may be provided adjacent to the first connection member and the second connection member, and may be separately connected to the first electrode lead and the second electrode lead to sense the voltage of the battery cell. When the voltage sensing connector transmits sensed voltage information to the controller 150, the controller 150 controls charging and discharging of the battery cell based on the voltage information.

[0087] Referring to FIG. 2, the charge / discharge control board 140 may include a first charge / discharge control board 140a connected to the first charge / discharge module 161 and a second charge / discharge control board 140b connected to the second charge / discharge module 162.

[0088] The present invention provides a charge / discharge method as a second embodiment.

[0089] The charging / discharging method according to the embodiment of the present invention may be a method of charging / discharging a plurality of battery cells connected in series using the above-described series-type charging / discharging device.

[0090] The charging / discharging method according to the present invention includes a plurality of charging / discharging steps, numbered 1 to N (N is an integer between 2 and 10), each of which is set to charge / discharge at a constant current and decrease the charging / discharging current value stepwise. Each of the charging / discharging steps includes simultaneously charging / discharging a plurality of battery cells connected in series at a constant current having a predetermined value, cutting off the current flowing to each battery cell that has reached a target voltage, and cutting off the charging / discharging step when the last battery cell that has not reached the target voltage reaches the target voltage.

[0091] Referring to FIG. 5, each charge / discharge step includes: (a) a process of charging / discharging a plurality of battery cells connected in series in a constant current mode; (b) a process of measuring the voltage of each of the battery cells and cutting off current so that no current flows to a battery cell that has reached a target voltage; and (c) a process of cutting off charge / discharge when the last battery cell that has not reached the target voltage reaches the target voltage.

[0092] The charge / discharge method according to the present invention comprises a plurality of charge / discharge steps, each of which includes the above-mentioned steps (a) to (c), and after completing steps (a) to (c), the next charge / discharge step is performed, in which the charge / discharge current value in the next charge / discharge step is set to a value that is lower than the charge / discharge current value in the previous step.

[0093] The charging / discharging method of the present invention is configured to continue charging / discharging in a constant current mode for battery cells that have not reached the target voltage and to cut off current for battery cells that have reached the target voltage in the process of cutting off current so that current does not flow to battery cells that have reached the target voltage. Therefore, the battery cells that have reached the target voltage enter a rest state in which charging / discharging is stopped while charging / discharging for the remaining battery cells continues.

[0094] The charge / discharge method of the present invention is configured to charge / discharge battery cells connected in series in a constant current mode, and cut off the current flowing to each battery cell that reaches a target voltage. When the last battery cell that has not reached the target voltage reaches the target voltage for the first time, the charge / discharge step is cut off, and then the next charge / discharge step is started.

[0095] The next charge / discharge stage differs from the immediately preceding charge / discharge stage in that the charge / discharge current value is reduced, but the steps (a) to (c) are the same.

[0096] In the charging / discharging method of the present invention, a reference current value is set to completely terminate the charging / discharging phase. The reference current value is a charging / discharging current value that is a reference for finally terminating the charging / discharging phase, and may be set differently depending on the specifications of the battery cell.

[0097] Therefore, the current value of the final charge / discharge step can be set to the same as the reference current value. That is, the charge / discharge step according to the present invention is completely terminated by performing cutoff in step (c) during the charge / discharge step in which constant current charging is performed at the same value as the reference current value.

[0098] This charging / discharging method has the effect of significantly reducing the time required for charging / discharging by replacing constant voltage mode charging / discharging with multistage constant current mode charging / discharging. [Explanation of symbols]

[0099] 100: Series charging / discharging device 110: Tray 120: Cooling fan 130: Power supply 140: Charge / discharge control board 150: Control unit 160: Charge / discharge module 180: Frame

Claims

1. A series-type charging / discharging device for charging / discharging a plurality of battery cells connected in series, a charge / discharge control board for controlling the charge / discharge current of each of the plurality of battery cells; a control unit having a charge / discharge control algorithm; The charge / discharge control algorithm It consists of first to Nth charge / discharge stages (N is an integer from 2 to 10), Each charge / discharge stage is configured to charge / discharge in a constant current mode, and the charge / discharge current value is decreased stepwise; The charge / discharge control algorithm In each charging and discharging step, A series-type charging / discharging device configured to charge / discharge series-connected battery cells in a constant current mode, cut off the current flowing to each battery cell that reaches a target voltage, and cut off the current when the last battery cell that does not reach the target voltage reaches the target voltage.

2. A series charging / discharging device as described in claim 1, wherein the charge / discharge control algorithm is configured so that a charge / discharge current flows to all of the plurality of battery cells after one charge / discharge stage ends and at the start of the next charge / discharge stage.

3. A series-type charging / discharging device for charging / discharging a plurality of battery cells connected in series, a charge / discharge control board for controlling the charge / discharge current of each of the plurality of battery cells; a control unit having a charge / discharge control algorithm; The charge / discharge control algorithm It consists of first to Nth charge / discharge stages (N is an integer from 2 to 10), Each charge / discharge stage is configured to charge / discharge in a constant current mode, and the charge / discharge current value is decreased stepwise; The charge / discharge control board a charge / discharge switch connected in series to each of the battery cells; a bypass switch connected to both ends of the charge / discharge switch; a switch controller for controlling the on / off operations of the charge / discharge switch and the bypass switch; The switch controller turns off the charge / discharge switch corresponding to the battery cell and turns on the bypass switch corresponding to the battery cell each time the battery cell reaches a target voltage in each of the charge / discharge stages.

4. A series charging / discharging device as described in claim 3, wherein the charging / discharging switch is turned on after one charging / discharging stage ends and at the start of the next charging / discharging stage.

5. The battery power supply further includes a voltage sensing unit configured to sense the voltage of each of the plurality of battery cells and send sensed voltage information to the control unit; 4. The series charging / discharging device of claim 3, wherein the control unit controls the switch controller to turn off the charging / discharging switch connected in series to the battery cell and turn on the bypass switch to bypass a charging / discharging current of the battery cell whenever a battery cell reaches a cutoff voltage based on the voltage information received from the voltage sensing unit.

6. A cooling fan for adjusting the temperature of a plurality of battery cells that are being charged and discharged, 6. The series charge / discharge device according to claim 1, wherein the charge / discharge control board is disposed in a space on a side of the cooling fan.

7. One or more trays for accommodating a plurality of battery cells; a cooling fan for adjusting the temperature of a plurality of battery cells that are charged and discharged; The cooling fan is an upper cooling fan disposed above the tray in a direction perpendicular to the ground; The series charging / discharging device according to claim 1 , further comprising: a lower cooling fan disposed below the tray with respect to a direction perpendicular to the ground.

8. A first charge / discharge module having a plurality of first connection members for connecting to each first electrode lead of the plurality of battery cells; 6. The series charging / discharging device according to claim 1, further comprising: a second charging / discharging module having a plurality of second connection members for connecting with each second electrode lead of the plurality of battery cells.

9. The charge / discharge control board The series-type charging / discharging device of claim 8 , comprising: a first charging / discharging control board connected to the first charging / discharging module; and a second charging / discharging control board connected to the second charging / discharging module.

10. one or more trays for housing a plurality of battery cells; The series charging / discharging device according to claim 8 , wherein the tray is disposed between the first charging / discharging module and the second charging / discharging module in a direction horizontal to the ground.

11. the first charge / discharge module is configured to be movable in a direction toward the plurality of first electrode leads and in an opposite direction thereto; The series-type charging / discharging device according to claim 8 , wherein the second charging / discharging module is configured to be movable in a direction toward the plurality of second electrode leads and in an opposite direction thereto.

12. 9. The series charging / discharging device according to claim 8, wherein the plurality of first connection members are configured to press both surfaces of the first electrode lead, and the plurality of second connection members are configured to press both surfaces of the second electrode lead.

13. A series charging / discharging device as described in any one of claims 1 to 5, wherein the charge / discharge control algorithm sets a reference current value that completely terminates charging / discharging, and the current value of the final charging / discharging stage is set to be the same as the reference current value.

14. A battery pack including one or more trays for accommodating a plurality of battery cells; The tray is two or more; 6. The series charging / discharging device according to claim 1, wherein the trays are configured to be stackable with respect to a direction perpendicular to the ground.

15. A method for charging and discharging battery cells using the series-type charging and discharging device according to any one of claims 1 to 5.

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