KR20170022163A - Multi battery pack apparatus and control method for charging the same - Google Patents

Abstract

Provided are a multi-battery pack device and a charge controlling method for the same. More specifically, provided are a multi-battery pack device capable of preventing spark formation by equalizing voltage of a plurality of battery packs, and a charge controlling method for the same. The multi-battery pack device includes the plurality of battery packs which are connected in parallel with each other. Each of the plurality of battery packs comprises: a plurality of battery cells; and a switching part controlling charge and discharge states of the plurality of battery cells. The switching part includes parasitic diodes which are connected in reverse directions reciprocally.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a multi-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a multi-battery pack device, and more particularly, to a multi-battery pack device capable of equalizing voltages of a plurality of battery packs and a charging control method thereof.

Smartphone, laptop computer. A portable electronic device such as a digital camera has a built-in battery pack so that the portable electronic device can be driven even if a separate power source is not provided. The battery pack may be configured such that a plurality of charge and dischargeable battery cells are connected in series. However, since the battery cell has electrochemical nonlinearity and instability characteristics, it has a risk of explosion due to damage to the battery cell in an overcharge discharge or a severe operating environment. Accordingly, battery stability is ensured through optimal battery charge management, load characteristic monitoring, and thermal management using a battery management system (hereinafter referred to as BMS) that performs an algorithm for battery management and control.

In addition, the BMS can be configured as one master and a plurality of slaves for more efficient management of the battery. The plurality of slaves control the states of the respective battery cells, and the master controls the plurality of slaves so that the overall battery management and the partial battery management can be stably performed.

In recent years, a multi battery pack device has been proposed in which a plurality of battery packs are connected and used in order to provide a sufficient capacity for ensuring stable operation of the portable electronic device and to cope with various types of portable electronic devices. An example of such a multiple battery pack device is disclosed in Japanese Patent Registration No. 3405526 (hereinafter referred to as prior art). In the prior art, each of a plurality of battery packs includes a plurality of battery cells, a circuit for detecting the charging / discharging state, and a circuit for controlling charging / discharging, one master battery pack and the other slave battery pack. The master battery pack requests transmission of data indicative of a charge / discharge state to the slave battery pack by communication, controls the entire data, determines the charge / discharge state, and controls the charge / discharge. The slave battery pack transmits data indicating the charge / discharge status according to the data request, and receives the command from the master pack to perform charging and discharging.

However, when a plurality of battery packs are connected in parallel, if the state of charge (SOC) between the battery packs, that is, the state of charge is different, sparks may occur. For example, the capacity of the battery pack may vary depending on the elapsed time from the manufacturing date, so that the charging state of the battery pack is different and an overcurrent flows from the battery pack having a higher voltage to the battery pack having a lower voltage. The spark may cause problems for the user's safety and may damage the battery cell or various circuit components.

Even when a plurality of battery packs are connected in parallel, there may be a case where the storage capacity of the battery pack is increased or a part of the battery pack is damaged and needs to be replaced. In this case, An additional battery pack must be connected. In this situation, the battery pack to be connected may have a different SOC from the battery pack to which the battery pack is connected. At this time, an overcurrent flows from the battery pack having a higher voltage to the battery pack having a lower voltage.

In order to prevent such overcurrent and spark, it is necessary to charge and discharge equipment which can precisely match the voltage of the battery pack by charging and discharging.

Japanese Patent No. 3405526

The present invention provides a multi-battery pack device and its charge control method that can prevent the occurrence of sparks and the like by equalizing the voltages of a plurality of battery cells.

The present invention provides a multi-battery pack device capable of equalizing the voltages of a plurality of battery cells without requiring a separate charging or discharging device, and a charging control method thereof.

According to an aspect of the present invention, a multi-battery pack apparatus includes a plurality of battery packs connected in parallel, each of the plurality of battery packs includes a plurality of battery cells, and a switching unit for controlling charging and discharging of the plurality of battery cells And the switching unit includes a parasitic diode connected in a reverse direction to each other.

One of the plurality of battery packs is set as a master battery pack, and the other battery packs are set as a slave battery pack.

Each of the plurality of battery packs further includes a sensing unit for sensing the state of the plurality of battery cells and a control unit for controlling the switching unit according to the state of the plurality of battery cells sensed by the sensing unit.

The control unit of the battery pack, which is set as the slave battery pack, transmits the state data of the battery cell to the battery pack set as the master battery pack, and the control unit of the battery pack set as the master battery pack includes a plurality of batteries And transmits a control signal for controlling charge / discharge of the plurality of battery cells to a control unit of the battery pack set as the slave battery pack.

The switching unit includes a charge switch controlled by the control unit and driven upon charging, and a discharge switch controlled by the control unit and driven upon discharge.

The charge switch includes a first FET and a first parasitic diode connected in parallel with the first FET, the discharge switch including a second FET and a second parasitic diode connected in parallel with the second FET.

The first and second parasitic diodes are connected to each other in a reverse direction. The first parasitic diode provides a discharging path for discharging the battery cell, and the second parasitic diode provides a charging path for charging the battery cell.

According to another aspect of the present invention, there is provided a method for controlling a charge of a multi-battery pack device, the method comprising: connecting a plurality of battery packs each having a charge switch and a discharge switch for charging and discharging the plurality of battery cells, step; Turning on the charge switch of each of the plurality of battery packs and turning off the discharge switch; Charging the plurality of connected battery packs in the order of a battery pack having a higher voltage from a battery pack having a lower voltage by applying power from the outside; And turning off the charge switch when the charge voltages of the plurality of battery packs are equal and fully charged.

When the external power is applied, the first battery pack having the lowest voltage is charged. When the voltage of the first battery pack is equal to the voltage of the second battery pack, the first and second battery packs are simultaneously charged, Charge the pack at the same voltage.

And turning on the discharge switch of the first battery pack while the first battery pack having the lowest voltage is being charged.

Setting one of the plurality of battery packs as a master battery pack and setting other battery packs as a slave battery pack.

The slave battery pack is configured such that the battery packs transmit the voltage of the battery cell to the battery pack set as the master battery pack and the battery pack set as the master battery pack is connected to the plurality of battery cells of the battery pack set as the slave battery pack. And transmits a control signal for controlling charging / discharging to the battery pack set as the slave battery pack.

The multi-battery pack device according to the embodiments of the present invention includes a switching unit including first and second switches that are respectively driven during charging and discharging in a plurality of battery packs, and can block the discharging path of the battery pack during charging. Therefore, even when a plurality of battery packs have different charging voltages depending on different charging states, it is possible to prevent a current from flowing from a battery pack having a higher voltage when the battery is charged to a battery pack having a lower voltage, Can be prevented from being generated.

1 is a schematic diagram of a multi-battery pack device according to an embodiment of the present invention;
2 and 3 are views showing the construction of one battery pack according to an embodiment of the present invention and an enlarged view thereof.
FIG. 4 is a flowchart for explaining a charge control method of a multi-battery pack apparatus according to an embodiment of the present invention; FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of other various forms of implementation, and that these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know completely.

FIG. 1 is a schematic view of a multi-battery pack apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are views illustrating a configuration of a battery pack according to an embodiment of the present invention and an enlarged view thereof.

As shown in FIG. 1, a multi-battery pack apparatus according to an embodiment of the present invention may include a plurality of battery packs 11, 12, 13, 14, 10. Although the present embodiment shows four battery packs 10 as a multiple battery pack device, at least two or more battery packs 10 may be provided. Also, the plurality of battery packs 10 can be combined and removed, and the battery pack 10 to be coupled can be varied. For example, two battery packs 10 may be connected to form a multi-battery pack, and four battery packs 10 may be connected to form a multi-battery pack.

2, the plurality of battery packs 10 include a battery 100 including a plurality of battery cells 101, 102, 103, ..., 10n, a battery 100 for managing the charge and discharge of the battery 100, And a management unit 200, respectively. When a plurality of battery packs 10 are connected, the batteries 100 of the battery packs 10 are connected to each other, and the battery management unit 200 is also connected to each other. At this time, the plurality of battery cells in one battery pack 10 are connected in series, and the batteries 100 of the plurality of battery packs 10 may be connected in parallel to each other. For example, when the batteries 100 of the plurality of battery packs 10 each include n battery cells, the positive electrodes of the first battery cells 101 of the battery pack 10 are connected to each other, The cathodes of the cell 10n may be connected to each other. Meanwhile, the battery management unit 200 may be connected by, for example, CAN (Controller Area Network) communication. Here, one of the plurality of battery packs 10 may be a master battery pack and the remainder may be a slave battery pack. For example, the first battery pack 11 may be a master battery pack and the second through fourth battery packs 12, 13, and 14 may be a slave battery pack. In the embodiment of the present invention, An example in which the battery pack 11 functions as a master battery pack and the second to fourth battery packs 12, 13 and 14 function as a slave battery pack will be described as an example.

1. Battery cell

The plurality of battery cells 101, 102, 103, ..., 10n may include a rechargeable secondary battery such as a nickel-cadmium (Ni-Cd) battery, a nickel- And a lithium (Li) battery. Here, the battery 100 may be connected to an even number of battery cells or to an odd number of battery cells. That is, n may be an even number and may be an odd number. In this embodiment, an even number of battery cells are connected so that n is an even number. In addition, a plurality of battery cells may be connected in series. That is, a plurality of battery cells have one terminal and another terminal, that is, an anode and a cathode, and one terminal of one battery cell may be connected to the other terminal of another battery cell. For example, the cathode of the first battery cell 101 may be connected to the anode of the second battery cell 102, and the cathode of the second battery cell 102 may be connected to the anode of the third battery cell 103 have. In addition, the plurality of battery cells may have the same capacity and thus the maximum charge voltage may be the same, for example, the maximum charge voltage may be 5V. However, the capacity of the battery cell may vary depending on the battery pack 10, and thus the maximum charging voltage may be different. For example, the battery cells of the battery pack 10, which have elapsed from the manufacturing date, may be smaller in capacity than the battery cells of the battery pack 10 having a shorter time elapsed from the manufacturing date, have.

2. Battery management section

The battery management unit 200 senses the state of the battery 100 including a plurality of battery cells, and controls the charging / discharging of the battery 100 accordingly. For example, the battery management unit 200 can sense the voltage of the battery 100, control the charge / discharge of the battery 100 according to the sensed voltage, and perform cell balancing on a predetermined number of battery cells. have. Also, the battery management unit 200 can control data input / output between the plurality of battery packs 10. That is, the battery management unit 200 of the master battery pack, for example, the first battery pack 11, may be connected to a plurality of slave battery packs, for example, a battery management unit (not shown) of the second to fourth battery packs 12, The control unit 200 receives data according to the charge / discharge state of the second to fourth battery packs 12, 13 and 14 from the control unit 200, determines a charge / discharge state, and transmits a control signal for controlling charge / discharge of the slave battery pack have. The second to fourth battery packs 12, 13, and 14, which are slave battery packs, transmit data according to the charging / discharging state of the corresponding battery pack to the first battery pack 11 as the master battery pack, The control signal can be received and charged / discharged. As a result, among the plurality of battery packs 10, the master battery pack can check the charging / discharging state of the plurality of slave battery packs and control the charging / discharging operations of the plurality of slave battery packs.

The battery management unit 200 includes an input and output unit 210 for inputting and outputting data between a plurality of battery packs 10, a sensing unit 220 for sensing the state of the battery 100, A controller 230 for controlling charging and discharging of the battery 100 according to the measured state of the battery 100 and a switching unit 230 for controlling connection between the battery 100 and the load in accordance with a control signal of the controller 230 240). Here, the battery management unit 200 of each of the master battery pack and the slave battery pack may have the same configuration including the input / output unit 210, the sensing unit 220, the control unit 230, and the switching unit 240, At least one of the configurations can perform other functions. For example, the control unit 230 of the second to fourth battery packs 12, 13, and 14 senses the state of the battery 100 of the corresponding battery pack and, in accordance with the control signal of the first battery pack 11, The control unit 230 of the first battery pack 11 can determine the state of the battery 100 of the second to fourth battery packs 12, 13 and 14, The charging and discharging of the second to fourth battery packs 12, 13, and 14 can be controlled using the battery pack. The battery 100 of the first battery pack 11 functioning as the master battery pack is also charged and discharged and the switching unit 240 is controlled by the control unit 230 according to the sensing data of the sensing unit 220 And the charge / discharge can be controlled. That is, the battery 100 of each of the first to fourth battery packs 11, 12, 13, and 14 can be charged and discharged, and the battery management unit 200 of the first battery pack 11 can charge and discharge the first battery pack 11 Discharge control of the battery 100 of the second to fourth battery packs 12, 13 and 14 and the charging and discharging of the battery 100 of the second to fourth battery packs 12, 13, The battery management unit 200 of the first battery pack 14 controls the charging and discharging of the battery 100 of the corresponding battery pack 12, 13, or 14 under the control of the battery management unit 200 of the first battery pack 11.

2.1. Input /

The input / output unit 210 performs data input / output between the plurality of battery packs 10. That is, data input / output between the first battery pack 11 and the second to fourth battery packs 12, 13, and 14 is performed. At this time, a CAN (Controller Area Network) communication is established between the battery packs 10 to perform data input / output. The input / output unit 210 transmits data transmitted from the control unit 230 of the pertinent battery pack 10 to the other battery pack 10, inputs data output from the other battery pack 10, 10 to the control unit 230. State data such as a measured voltage according to the charged state of the battery cell 100 of the battery pack 10 through the input / output unit 210 of the plurality of battery packs 10, a control signal for controlling the charging / . That is, data corresponding to the charged state of the battery cell 100 from each of the second to fourth battery packs 12, 13 and 14 is supplied to the input / output unit 210 of the first battery pack 11 through the input / And a control signal for controlling the charging of the second to fourth battery packs 12, 13 and 14 may be transmitted to the second to fourth batteries 11 and 12 via the input / output unit 210 of the first battery pack 11. [ Output unit 210 of the packs 12, 13, and 14, respectively. The input / output unit 210 may include a buffer (not shown) for temporarily storing data. That is, the buffer in the first battery pack 11 can temporarily store the data input from the second through fourth battery packs 12, 13, 14 and then transmit the data to the controller 230 in the order of input, The data output through the control unit 230 of the battery pack 11 may be temporarily stored and then transferred to the second to fourth battery packs 12, 13, and 14 in sequence.

2.2. Sensing portion

The sensing unit 220 may sense the states of the plurality of battery cells of the battery 100. [ The sensing unit 220 may include a voltage measuring unit for measuring a voltage of each of the plurality of battery cells. In order to measure the voltage, the sensing unit 220, that is, the voltage measuring unit is connected to a plurality of battery cells through a plurality of connection lines to measure a voltage of each of the plurality of battery cells, and transmits the voltage to the controller 230. In the embodiment of the present invention, the sensing unit 220 is formed as a single unit, but a plurality of sensing units 220 may be provided to correspond to a plurality of battery cells, as needed. Also, although not shown, an analog-to-digital converter is provided between the sensing unit 220 and the controller 230 for easy configuration and fast processing speed of the controller 230, May be converted into a digital signal and may be transmitted to the controller 230. Meanwhile, the sensing unit 220 may sense not only the voltages of the plurality of battery cells, but also current and temperature. That is, the sensing unit 220 may further include a current measuring unit and a temperature measuring unit.

2.3. The control unit

The control unit 230 controls the charge / discharge of the battery 100 according to the state of the battery cell. For example, the control unit 230 may control the charging / discharging of the battery 100 according to the voltage of the battery 100 measured by the sensing unit 220. The control unit 230 may have different functions depending on the master battery pack and the slave battery pack. That is, the control unit 230 of the master battery pack, that is, the first battery pack 11, stores state data of the battery 100 measured from the slave battery packs, that is, the second to fourth battery packs 12, 13, And control signals for controlling the charging and discharging of the batteries 100 of the second to fourth battery packs 12, 13 and 14 are inputted to the second to fourth battery packs 12, 13 and 14 Supply. The control unit 230 of each of the slave battery packs, that is, the second to fourth battery packs 12, 13 and 14, transmits the state data of the battery 100 measured by the sensing unit 220 to the first battery pack 11, And controls the switching unit 240 according to a control signal supplied from the first battery pack 11 to control the charging and discharging of the battery 100. [

The controller 230 of the master battery pack manages the charge / discharge state of the battery cells 100 of the plurality of slave battery packs. That is, the control unit 230 of the master battery pack can estimate SOC, SOH, etc. of the battery using data of the current and voltage of the battery 100 input from the plurality of slave battery packs through the input / output unit 210 have. In order to estimate the SOC and SOH of the battery, an SOC estimating unit (not shown) and an SOH estimating unit (not shown) may be provided in the controller 230, respectively. The SOH estimation unit estimates the capacity of the battery 100 to predict the degree of degradation of the battery 100. [ At this time, the estimated capacity of the battery 100 may be used in SOC estimation of the battery 100 by the SOC estimating unit. Here, the estimation of the capacity of the battery 100 can be performed in various ways. For example, since the capacity of the battery can be estimated by changing the internal resistance of the battery, it is possible to measure the current and voltage of the battery, The internal resistance can be indirectly calculated. That is, the capacity of the battery 100 can be estimated using the current and voltage data of the battery 100 input from the slave battery pack. The SOC estimator may estimate the SOC of the battery 100 using the capacity of the battery 100 estimated by the SOH estimation unit and the current of the battery 100 measured from the slave battery pack. For example, the SOC estimation unit may estimate the SOC of the battery 100 by integrating the current value measured for a predetermined time from the slave battery pack and dividing the current value by the estimated battery capacity (Capacity) from the SOH estimation unit. Of course, it is also possible to use the measured voltage without estimating the SOH and the SOC in order to check the charging / discharging state of the battery 100. [ That is, the control unit 230 of the master battery pack may store the maximum charge voltage and the lowest charge voltage, and may control charging / discharging of the slave battery pack by comparing the measured voltage of the slave battery pack with the maximum or minimum charge voltage. For example, after setting the first reference voltage for stopping the charging operation and the second reference voltage for performing the charging operation, the voltage of the battery 100 measured from the slave battery pack is compared with the reference voltage, Can be controlled. The first set voltage may be set to, for example, 4.5 V to prevent overcharging when the maximum charge voltage of the battery 100 is 5 V, and the second set voltage may be set to prevent overdischarge of the battery 100 For example, 1.5V. In this way, the control unit 230 of the master battery pack compares the measured voltage of the slave battery pack with the reference voltage, and generates a control signal according to a result of the comparison, that is, a control signal for charging or discharging, and transmits the control signal to the slave battery pack.

The control unit 230 of the slave battery pack controls and manages components constituting the slave battery pack. That is, the control unit 230 of the slave battery pack supplies data of the voltage and current of the battery cell 100 measured by the sensing unit 220 to the master battery pack through the input / output unit 260, And controls the charging and discharging of the battery cell 100 by driving the switching unit 240 according to the supplied control signal. In addition, the controller 230 of the slave battery pack may control the cell balancing unit (not shown) to balance the cells.

2.4. The switching unit

The switching unit 240 is provided between a current path between the battery 100 and the load, and controls the charging and discharging of the battery 100 by the control unit 230. The switching unit 240 may include a first switch 241 and a second switch 242 as shown in FIG. That is, the switching unit 240 is provided between the battery 100 and the load. The first switch 241 may be provided on the battery 100 side and the second switch 242 may be provided on the load side. The first and second switches 241 and 242 are driven according to the control signal generated by the controller 230 and can be driven simultaneously when charging and discharging the battery 100 and either one of them may be driven. For example, the first switch 241 may be driven when the battery 100 is charged, and the second switch 242 may be driven when the battery 100 is discharged. That is, the first switch 241 is a charging switch that is driven when the battery 100 is charged, and the second switch 242 is a discharge switch that is driven when the battery 100 is discharged. The load may include an external power source for charging the battery 100 of the battery pack 10 and an electronic device to which the battery pack 10 driven according to the discharge voltage of the battery 100 is mounted. That is, when the battery 100 is charged, the battery pack 10 is connected to an external power source, and when the battery 100 is discharged, the battery pack 10 can be connected to the electronic device.

The first switch 241 may include a first FET 241a and a first parasitic diode 241b. The first FET 241a has a source terminal and a drain terminal provided between the battery 100 and the first node Q1 and a gate terminal connected to the controller 230. [ Accordingly, the first FET 241a is driven according to a control signal output from the controller 230, and functions to apply a current to the battery 100 during charging. The first parasitic diode 241b is connected in parallel to the first FET 241a. That is, the first parasitic diode 241b is connected in a forward direction between the battery 100 and the first node Q1. This first parasitic diode 241b sets the discharge path of the battery 100 when the first FET 241a is turned off. That is, the battery 100 may be charged through the first FET 241a, and the battery 100 may be discharged through the first parasitic diode 241b.

The second switch 242 may include a second FET 242a and a second parasitic diode 242b. A source terminal and a drain terminal of the second FET 242a are provided between the first node Q1 and the load, and a gate terminal is connected to the control unit 230. [ Accordingly, the second FET 242a is driven according to a control signal output from the controller 230, and applies a discharging current of the battery 100 to the connected electronic device during discharging. The second parasitic diode 242b is connected in parallel to the second FET 242a. That is, the second parasitic diode 242b is connected in the reverse direction between the first node Q1 and the load. The second parasitic diode 242b sets the path of the charging current when the battery 100 is charged. That is, the battery 100 is discharged through the second FET 242a, and the battery 100 can be charged through the second parasitic diode 242b.

The switching unit 240 is connected to the gate terminal of the first FET 241a and the gate terminal of the second FET 242a and the control unit 230 is connected to the first and second FETs 241a and 242b, FETs 241a and 242a, respectively. The control unit 230 turns on the first FET 241a and turns off the second FET 242b when the battery 100 is charged. Therefore, the battery 100 is charged from the load, that is, the external power supply, through the second parasitic diode 242b and the first FET 241a. In addition, the controller 230 turns on the second FET 242a and turns on the second FET 241a when the battery 100 is discharged. Thus, the battery 100 is discharged from the battery 100 through the first FET 241a and the second parasitic diode 242b. At this time, the control signal for turning on the first and second FETs 241a and 242a, respectively, may be a logic high signal, and the control signal for turning off the first and second FETs 241a and 242a respectively may be a logic low signal .

As described above, the multiple battery pack device according to an embodiment of the present invention includes a plurality of battery packs 10 connected to each other, and each of the plurality of battery packs 10 includes a battery 100 including a plurality of battery cells, And a battery management unit 200 includes a control unit 230 and a switching unit 240. [ The switching unit 240 may include a first switch 241 driven when the battery 100 is charged and a second switch 242 driven when the battery 100 is discharged. The first switch 241 includes a first FET 241a and a first parasitic diode 241b and the second switch 242 includes a second FET 242a and a second parasitic diode 242b. The first FET 241a is driven to charge the battery 100 through the second parasitic diode 242b and the first FET 241a when the battery 100 is charged and when the battery 100 is charged, The first parasitic diode 242a is driven and the battery 100 is discharged through the first parasitic diode 241b and the second FET 242a. That is, the multi-battery pack apparatus according to an embodiment of the present invention includes a switching unit 240 including first and second switches 241 and 242, respectively, And the discharge path of the battery pack 10 can be shut off during charging. Therefore, even when the plurality of battery packs 10 have different charging voltages depending on the different charging states, the current from the battery pack 10 having a higher voltage at the time of charging the battery 100 to the battery pack 10 having a lower voltage And it is possible to prevent the occurrence of sparks or the like.

4 is a flowchart illustrating a method of controlling charging of a multi-battery pack apparatus according to an embodiment of the present invention.

Referring to FIG. 4, a method for controlling charging of a multi-battery pack apparatus according to an embodiment of the present invention includes the steps of turning on a charging switch and turning off a discharging switch (S110) A step S130 of judging whether the charging voltages of all the battery packs 10 are identical to each other and a step S130 of judging whether or not the charging voltages of all the battery packs 10 are the same, A step S160 of turning on the discharging switch for turning on the charging switch S160, a step S140 of turning on the discharging switch for turning on the discharging switch S160, A step (S170) of judging whether the plurality of battery packs 10 have been fully charged to the same charging voltage, and a step (S170) of turning off the charging switch when the plurality of battery packs 10 are fully charged to the same charging voltage (S180). The control method of the present invention will be described in detail as follows.

First, a charging switch provided in each of the plurality of battery packs 10 is turned on and the discharging switch is turned off to charge the multi-battery pack device to which the plurality of battery packs 10 are connected (S110). That is, the first FET 241a of the first switch 241 is turned on and the second FET 242a of the second switch 242 is turned off. At this time, in the multi-battery pack device of the present invention, the four battery packs 11, 12, 13 and 14 may be connected and the charging voltage of at least one battery pack 10 may be different. For example, when the first battery pack 11 maintains the first charge voltage, the second battery pack 12 maintains the second charge voltage lower than the first charge voltage, and the third battery pack 13 The third charging voltage lower than the first charging voltage and higher than the second charging voltage can be maintained and the fourth battery pack 14 can maintain the fourth charging voltage lower than the first charging voltage and higher than the third charging voltage. By turning on the charge switch of each of the plurality of battery packs 10 and turning off the discharge switch, the plurality of battery packs 10 can be charged but can not discharge.

When the power is supplied from the external power source and charging starts (S120), the current supplied from the external power source flows to the battery pack 10 having the lowest charging voltage, that is, the second battery pack 12, The voltage is increased. Meanwhile, the discharge switch of the second battery pack 12 may be turned on to reduce the heat generation of the second battery pack 12 while the second battery pack 12 having the lowest voltage is charged. At this time, even when the discharging switch is turned on, the voltage is maintained at the lowest level, so that the discharging is not performed to the other battery pack. When the voltage of the second battery pack 12 having the lowest voltage is charged and the voltage of the third battery pack 13 having the next lowest voltage becomes the same, the current is supplied to the second battery pack 12 and the third battery pack 13 The second and third battery packs 12 and 13 are charged at the same time. When the charging voltages of the second and third battery packs 12 and 13 are the same as those of the fourth battery pack 14, current flows to the second, third, and fourth battery packs 12, 13, 2, the third and fourth battery packs 12, 13, 14 are simultaneously charged. At this time, since each of the plurality of battery packs 10 can be charged but maintains a state in which discharging is impossible, a current flows from the first battery pack 11 having a high voltage to the battery packs 12, 13, It is inherently prevented.

When the voltages of the first to fourth battery packs 11 to 14 become equal to each other by charging the second battery pack 12 having the lowest voltage in the order of the highest first battery pack 11, Currents are divided and flowed into the fourth battery packs 11 to 14 so that the first to fourth battery packs 11 to 14 are simultaneously charged. During the charging of the first to fourth battery packs 11 to 14, the battery management unit 200 in each battery pack 10 senses the state of each battery 100, (11).

When the voltages of the first to fourth battery packs 11 to 14 become equal to each other (S130), the second FET 242a of the second switch 242 is turned on in order to reduce heat generation of the discharge switch in a state where the charge switch is turned on (S140). That is, the battery management unit 200 of the first battery pack 11 controls the voltage of the first battery pack 11 and the voltage of the battery 10 transmitted from the second to fourth battery packs 12, 13, When the voltages of the first to fourth battery packs 11, 12, 13, and 14 are equalized and the charging switches of the first to fourth battery packs 11, 12, 13, and 14 are turned on, . At this time, since the voltages of the first to fourth battery packs 11 to 14 are all the same, no current flows between the battery packs 10 and no spark is generated accordingly.

If the charging is terminated before the plurality of battery packs 10 are fully charged (S150), the charging switch, i.e., the first FET 241a is turned on for recharging and the discharging switch, i.e., the second FET 242a is turned on or off (S160). That is, the first FET 241a is turned on to charge the battery pack 10, and the second FET 242a may be turned off or turned on to reduce the heat generation.

When all of the plurality of battery packs 10 are fully charged (S170), the charging switch, i.e., the first FET 241a is turned off (S180). Thus, overcharging of the plurality of battery packs 10 is prevented, and charging is terminated. At this time, the discharge switch, that is, the second FET 242a, can be turned on or off according to the system environment.

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 will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

10: Battery pack 100: Battery cell
200: battery management unit 210: input /
220: sensing unit 230:
240:

Claims (12)

A plurality of battery packs connected in parallel,
Wherein each of the plurality of battery packs comprises:
A plurality of battery cells,
And a switching unit for controlling charging and discharging of the plurality of battery cells,
Wherein the switching unit includes parasitic diodes connected in opposite directions to each other.
The multi-battery pack apparatus according to claim 1, wherein one of the plurality of battery packs is set as a master battery pack, and the other battery packs are set as a slave battery pack.
The battery pack according to claim 2,
A sensing unit for sensing a state of the plurality of battery cells,
And a control unit for controlling the switching unit according to a state of the plurality of battery cells sensed by the sensing unit.
The master battery pack according to claim 3, wherein the control unit of the battery packs set as the slave battery pack transmits the status data of the battery cell to the battery pack set as the master battery pack, And transmits a control signal for controlling charging and discharging of the plurality of battery cells to the control unit of the battery pack set as the slave battery pack, by determining the states of the plurality of battery cells of the plurality of battery packs set to the slave battery pack.
The multi-battery pack apparatus according to claim 4, wherein the switching unit comprises a charging switch controlled by the control unit and driven upon charging, and a discharge switch controlled by the control unit and driven upon discharge.
The charge switch of claim 5, wherein the charge switch comprises a first FET and a first parasitic diode connected in parallel with the first FET,
Wherein the discharge switch comprises a second FET and a second parasitic diode connected in parallel with the second FET.
7. The battery pack of claim 6, wherein the first and second parasitic diodes are connected in opposite directions, the first parasitic diode provides a discharge path during discharge of the battery cell, Wherein the battery pack is a battery pack.
Connecting a plurality of battery packs each having a plurality of battery cells, a charging switch and a discharging switch for charging and discharging the plurality of battery cells, in parallel;
Turning on the charge switch of each of the plurality of battery packs and turning off the discharge switch;
Charging the plurality of connected battery packs in the order of a battery pack having a higher voltage from a battery pack having a lower voltage by applying power from the outside; And
And turning off the charge switch when the charge voltages of the plurality of battery packs are equal and fully charged.
The method of claim 8, wherein when the external power is applied, the first battery pack having the lowest voltage is charged, and if the voltage of the first battery pack is equal to the voltage of the second battery pack, Wherein the plurality of battery packs are charged with the same voltage.
The method according to claim 9, further comprising the step of turning on a discharge switch of the first battery pack while the first battery pack having the lowest voltage is charged.
The method according to claim 9, further comprising setting one of the plurality of battery packs as a master battery pack, and setting the other battery packs as a slave battery pack.
The slave battery pack according to claim 11, wherein the battery packs set as the slave battery packs transmit the voltage of the battery cell to the battery pack set as the master battery pack, and the battery pack set as the master battery pack, Wherein a control signal for controlling charging and discharging is transmitted to a battery pack set as the slave battery pack by determining a voltage of the plurality of battery cells.

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