KR101686018B1 - Battery cell balancing circuit using transformer - Google Patents

Abstract

The present invention relates to a technique for performing a battery cell balancing operation using a transformer.
To this end, the present invention provides a battery pack comprising a first access unit, a second access unit, an electric energy transfer unit, and a transformer for an electric energy path of a battery pack, wherein the first access unit, the second access unit, So that battery cell balancing can be achieved by selectively controlling the operation of the Strong or Wick cells of the battery pack to the primary and secondary windings of the transformer.
This improves the power efficiency of the battery pack and facilitates expansion of the battery pack according to the number of the battery cells.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell balancing circuit using a transformer,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancing technique of a multi-battery cell, and more particularly, to a battery cell balancing circuit using a transformer suitable for performing battery cell balancing operation using a transformer.

In general, there is a risk of explosion when the voltage across the battery cell exceeds the upper limit voltage, and when the voltage falls below the lower limit voltage, the battery cell is permanently damaged. A hybrid electric vehicle, a notebook computer, and the like require a relatively large power supply. Therefore, when a battery cell is used to supply power, a battery pack (battery module) in which battery cells are connected in series is used. However, when such a battery pack is used, a voltage imbalance may occur due to a variation in performance of each battery cell.

When one battery cell in the battery pack reaches the upper limit voltage before the other battery cells in charging the battery pack, the battery pack can no longer be charged, so that the charging is terminated when the other battery cells are not fully charged shall. In such a case, the charging capacity of the battery pack does not reach the rated charging capacity.

Meanwhile, when one battery cell in the battery pack reaches a lower limit voltage than other battery cells in the battery pack discharge time, the battery pack can no longer be used, shortening the use time of the battery pack.

As described above, when the battery pack is charged or discharged, the electric energy of the battery cell having higher electric energy is supplied to the battery cell having lower electric energy, thereby improving the use time of the battery pack. It is called balancing.

FIG. 1 is a battery cell balancing circuit diagram using a parallel resistor according to the related art. As shown in FIG. 1, a battery pack 11 having battery cells CELL1 to CELL4 connected in series, resistors R11 to R14, Switches SW11-SW15 for selectively connecting respective connection terminals between the battery cell 11 and the battery cells CELL1-CELL4 to corresponding terminals of the resistors R11-R14, do.

1, when the battery pack 11 is charged, the charging voltage of any battery cell among the battery cells CELL1 and CELL4 in the battery pack 11 is higher than the charging voltage of the other battery cells, The corresponding switch among the switches SW11 to SW15 is turned on so that the charging voltage is discharged through the resistor among the resistors R11 to R14.

For example, when the charging voltage of the second battery cell CELL2 reaches the upper limit voltage first of all compared with the charging voltage of the other battery cells CELL1, CELL3, CELL4, the switches SW12, SW13 are turned on . Accordingly, the charging voltage of the battery cell CELL2 is discharged through the resistor R12 to balance battery cells.

However, when such a battery cell balancing circuit is used, power is consumed through the resistor, so that the efficiency is lowered, and the efficiency is lowered because the upper limit voltage can not be supplied to the battery cell having low voltage during use of the battery pack.

2 is a battery cell balancing circuit diagram using a conventional capacitor. As shown in FIG. 2, the battery cell balancing circuit includes a battery pack 21 having battery cells CELL1 to CELL4 connected in series, capacitors C21 to C23 connected in series, The connection terminals between the capacitors C21 and C22 and the connection terminals between the capacitors C22 and C23 and the other terminals of the capacitor C23 are connected to the battery cells CELL1 to CELL4 And switches SW21 to SW24 for selectively connecting to one of the two terminals of the switch SW21.

Referring to FIG. 2, the battery cell balancing circuit using the capacitor has two connection states. 2, a connection terminal between the capacitors C21 and C22, a connection terminal between the capacitors C22 and C23, and a connection terminal between the other terminals of the capacitor C23, Are respectively connected to one terminal (positive terminal) of each of the battery cells CELL1 to CELL4. In the second connection state, one terminal of the capacitor C21, a connection terminal of the capacitors C21 and C22, a connection terminal of the capacitors C22 and C23, and a terminal of the other terminal of the capacitor C23, CELL1-CELL4), respectively.

However, such a battery cell balancing circuit has a problem that a hard switching operation occurs between a capacitor and a battery cell, resulting in low efficiency. Although it is preferable that the capacity of the battery cells in the battery pack is equal to each other, the capacities of the battery cells are different due to various reasons. In this case, even if the charging voltage of any one of the battery cells is lower than the charging voltage of the other battery cells, a larger capacity can be obtained. In this case, it is necessary to transfer the voltage of the low-voltage battery cell to the high-voltage battery cell. In such a conventional battery cell balancing circuit, such a voltage transfer function can not be performed.

3 is a battery cell balancing circuit diagram using a flyback structure according to the related art. As shown in FIG. 3, the battery pack balancing circuit includes a battery pack 31 having battery cells CELL1 to CELL4 connected in series, a flyback converter 32, A switch SW31-SW34 for selectively connecting each of the plurality of secondary coils of the flyback converter 32 to both terminals of each of the battery cells CELL1-CELL4, And a switch SW35 for selectively connecting both ends of the battery pack 31 to both ends of the battery pack 31.

The battery cell balancing circuit of FIG. 3 is a battery cell balancing circuit using a flyback structure, which is one of SMPS (Switch Mode Power Supply), and uses the switches SW31 to SW34 to connect the battery cells CELL1- CELL4, respectively, and is capable of transferring electrical energy between the terminals on both sides of the battery pack 31. [

However, as the number of battery cells provided in the battery pack increases, the size of the magnetic core used in the flyback converter increases. Accordingly, there is a disadvantage in that the battery cell balancing circuit There is a problem that the price of the battery cell balancing circuit rises.

Korean Patent Publication No. 10-2013-0091066

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of controlling a switching operation of an access unit and an electric energy transfer unit so that a strong cell or a weak cell of a battery pack is selectively connected to a primary winding and a secondary winding of a transformer So that battery cell balancing can be achieved.

According to an aspect of the present invention, there is provided a battery cell balancing circuit using a transformer, comprising: a battery pack including a plurality of battery cells connected in series; A first access unit having an access path connected between one terminal of the odd-numbered battery cell and the first common node in the battery pack; A second access unit having an access path connected between the other terminal of the odd-numbered battery cell and the second common node in the battery pack; An electrical energy transfer unit having two transfer paths for transferring electric energy recovered or supplied through the first common node; And an energy transfer unit connected between the second common node and the electric energy transfer unit for battery balancing of the battery pack to temporarily accumulate the electric energy recovered from the strong battery cells of the battery pack, And a transformer.

The present invention controls the switching operation of the switches of the access unit and the electric energy transfer unit so that the Strong cell or the wick cell of the battery pack is selectively connected to the primary winding and the secondary winding of the transformer so that battery cell balancing is performed , The power efficiency of the battery pack is improved, and the battery pack can be easily expanded according to the number of the battery cells.

FIG. 1 is a battery cell balancing circuit diagram using a conventional parallel resistor.
2 is a battery cell balancing circuit diagram using a capacitor according to the related art.
3 is a battery cell balancing circuit diagram using a flyback structure according to the prior art.
4 is a battery cell balancing circuit diagram using a transformer according to an embodiment of the present invention.
5 is a table showing switch states in four cell access modes according to the present invention.
FIGS. 6A to 6F are circuit diagrams showing paths and current flows for transferring electrical energy stored in a strong cell of odd numbers to an excellent weak cell. FIG.
FIG. 7 is a waveform diagram of each part of FIG. 4 when electric energy stored in the strong cell of the odd number is transmitted to the superior cell.
8A to 8F are circuit diagrams showing paths and current flow for delivering electric energy stored in Strong's stell cells to odd wick cells.
FIG. 9 is a waveform diagram of each part of FIG. 4 when electric energy stored in Strong's stell cells is transferred to the odd wick cells.
FIGS. 10A to 10F are circuit diagrams showing paths and current flow for delivering electric energy stored in Strong's Strong cells to superior Waste cells. FIG.
FIG. 11 is a waveform diagram of each part of FIG. 4 when electric energy stored in Strong cells of an even number is transmitted to a well cell.
Figs. 12A to 12F are circuit diagrams showing paths and current flow for transferring electric energy stored in a strong cell of radix to a wick cell of a radix. Fig.
FIG. 13 is a waveform diagram of each part of FIG. 4 when electric energy stored in a strong cell of a radix is transmitted to a radix wick cell.
14 (a) and 14 (b) are waveform diagrams showing experimental results of the battery cell balancing circuit according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a circuit diagram of a battery cell balancing circuit using a transformer according to an embodiment of the present invention. The battery cell balancing circuit 40 includes a battery pack 41, a first access unit 42, (43), an electric energy transfer unit (44), and a transformer (45).

The battery pack 41 includes battery cells B ₁ -B _N connected in series to store electric energy supplied from the outside. Voltage unbalance may occur due to performance variations of the battery cells (B ₁ -B _N ), but voltage imbalance is eliminated by the battery cell balancing operation as described below.

The first access unit 42 is connected between the negative terminal ("-" terminal) of the odd-numbered battery cell and the first common node N1 of the battery cells B ₁ -B _N provided in the battery pack 41 Numbered access path that is connected to each of the plurality of access paths. Here, the odd-numbered access paths each include a pair of switches connected in series. Among the odd-numbered access paths, the first access path 42_1 is provided with a pair of switches S _1L and S _1R connected in series, and the third access path 42_3 is provided with a pair of switches S _3L , S _3R) is provided, the fifth access path (42_5) is provided with a switch of a series-connected pair (S _5L, S _5R), the N access paths (42_N), the switch of the series-connected pair (S _NL , S _NR ) are provided.

The second access unit 43 is connected between the positive terminal (the "+" terminal) of the even battery cell and the second common node N2 among the battery cells B ₁ -B _N provided in the battery pack 41 And a second access path connected to the second access path. Here, the even-numbered access path includes a pair of switches connected in series. The second access path 43_2 is provided with a pair of switches S _2L and S _2R connected in series and the fourth access path 43_4 is provided with a pair of switches S _4L , And S _4R ), and the sixth access path 43_6 is provided with a pair of switches S _6L and S _6R connected in series, and the pair of serially connected pairs of the (N + 1) th access path 43_N + Switches S _{(N + 1) L} and S _{(N + 1) R} are provided.

The electrical energy transfer unit 44 has a first transmission path 44_1 and a second transmission path 44_2 for transferring electric energy recovered or emitted through the first common node N1. The first transmission path 44_1 is provided with a pair of switches Q _1L and Q _1R connected in series and the second transmission path 44_2 is provided with a pair of switches S _2L and S _2R connected in series .

The transformer 45 temporarily accumulates and discharges the electric energy recovered from the battery pack 41 for battery balancing with respect to the battery pack 41. To this end, the transformer (45) has a primary winding (L1) and a secondary winding (L2) wound opposite to each other. One tab of the primary winding L1 is connected to the second common node N2 and the other tab is connected to the other end of the second transmission path 44_2 of the electrical energy transfer unit 44. [ One of the taps of the secondary winding L2 is connected to the second common node N2 and the other of the taps is connected to the other end of the first transmission path 44_1 of the electric energy transfer unit 44. [

4, the switch S of the first accessing unit 42 and the second accessing unit 43 and the switch Q of the electrical energy transferring unit 44 are implemented by a metal oxide semiconductor field effect transistor . Of course, the switch according to the present invention is not limited to a MOS transistor, but may be realized by a power switch such as another switch, for example, a bipolar junction transistor (BJT) or an insulated gate bipolar transistor (IGBT). The MOS transistor is connected in parallel with the diode.

The battery cell balancing circuit 40 operates in four cell access modes and six drive modes (drive cycles). In the four cell access modes, battery cell balancing is performed on the battery cells (B ₁ -B _N ) provided in the battery pack 41. In this case, among the two battery cells selected for battery balancing, And a parity of a weak cell having a relatively low electric energy and supplied with the discharged electric energy is connected to a battery cell odd / (Even), even / odd, even / even, and odd / odd.

5 shows the switch states of the switches S of the first accessing unit 42 and the second accessing unit 43 and the switches Q of the electric energy transferring unit 44 in the four cell access modes . Here, the collect mode is a mode in which electric energy is recovered from a battery cell having a relatively high electric energy, and a release mode is an electric energy recovered by the collect mode and temporarily stored in the transformer 45 Weeks cell is a mode to supply.

The battery cell balancing path according to the present invention is classified into two paths in which electric energy flow paths are different from each other.

One of the two paths is a path (hereinafter referred to as a " different parity path ") when the strong cell and the weak cell are different parities, i.e., odd / even and even / odd. In the battery cell balancing mode using the different parity path, the electric energy recovered from the Strong cell is accumulated in the primary winding L1 of the transformer 45 and supplied to the Weck cell from the primary winding L1.

The other one of the two paths is a path (hereinafter referred to as "same parity path") in the case where Strong cells and Weeks cells have the same parity, that is, odd / odd or even / even. In the battery cell balancing mode using the same parity path, the electric energy recovered from the Strong cell is accumulated in the primary winding L1 of the transformer 45, the electric energy is transferred to the secondary winding L2, RTI ID = 0.0 > (L2) < / RTI >

For reference, in the cell access item of FIG. 5, SM and SM + 1 denote a switch for accessing the Mth strong cell. For example, when the second battery cell B2 is a strong cell, the switches S _2L and S _2R are SM and the switches S _3L and S _3R are SM + 1. SN, SN + 1 means a switch for approaching the N-th wake cell. For example, when the second battery cell B4 is a Weck cell, the switches S _5L and S _5R are SN and the switches S _6L and S _6R are SN + 1.

First, referring to FIG. 6A to FIG. 6F and FIG. 7, a balancing operation of the battery cell using the different parity path for supplying the electric energy stored in the odd battery cell odd to the superior battery cell (even) Respectively. Here, it is assumed that the battery cell B ₅ is a strong cell and the battery cell B ₂ is a weak cell.

A first mode (t ₀ -t ₁₎ the control unit (not yet displayed in the figure) from the fifth switch (S _{5L, 5R} S) of the access path (42_5), a sixth switch of the access path (42_6) (S _{6L, 6R} S ) and a second transmission path (the switch (Q _2L, and outputs a switch control signal (gate signal), the switch (S _5L, S _5R) in Q _2R) of _{44_2), (S 6L, S} 6R), (Q 2L , Q _2R ) are turned on.

6A, the positive terminal (+) of the battery cell B ₅ is connected to one tap of the primary winding L1 of the transformer 45 through the sixth access path 43_6, The negative terminal (-) of the cell B ₅ is connected to the other tap of the primary winding L1 of the transformer 45 through the fifth access path 42_5 and the second transmission path 44_2. Therefore, the electric energy of the battery cell B ₅ is transferred to the primary winding L1 of the transformer 45 and accumulated.

When the strong cell is connected to the transformer 45 in the collect mode using the switch as described above, and then the weak cell is connected to the transformer 45 using the switch in the release mode, there is a dead time between the collect mode and the release mode a dead time is required. The recovered electrical energy is circulated inside the transformer 45 during the dead time.

The second mode (t ₁ -t ₂ ) is a mode for forming an electric energy circulation path before reaching the dead time. To this end, the switch Q _1R of the first transmission path 44_1 is turned on in advance as shown in FIG. 6B.

The third mode (t ₂ -t ₃ ) is a mode in which the circulation of the recovered electric energy is started. To this end, the switches S _5L and S _5R of the fifth switch path and the switches S _6L and S _6R of the sixth access path 43_6 are turned off. As a result, an electric energy circulation path is formed through the primary winding L1 and the secondary winding L2 of the transformer 45 as shown in Fig. 6C.

The fourth mode (t ₃ -t ₄₎ is made of a pre-treatment operation prior to the transmitting the electrical energy stored in the transformer 45, a weak cell in a battery cell (B ₂₎ mode. At this time, the switch S _2R of the second access path 43_2 and the switch S _3R of the third access path 42_3 are turned on in advance as shown in FIG. 6D.

The fifth mode (t ₄ -t ₅ ) is a mode in which electric energy accumulated in the transformer 45 starts to be supplied to the battery cell B ₂ , which is a wick cell. At this time, the switch Q _1R of the first transmission path 44_1 is turned off. Thus, an electric energy supply path is formed as shown in FIG. 6E, and electric energy accumulated in the primary winding L1 of the transformer 45 starts to be supplied to the battery cell B ₂ .

The sixth mode t ₅ -t ₆ is a mode for performing the operation of turning on the switch S _2L of the second access path 43_2 and the switch S _3L of the third access path 42_3. 6F, so that the electric energy accumulated in the primary winding L1 of the transformer 45 _flows through the switches S _2L , S _2R , S _3L , S _3R , And is supplied to the cell B ₂ .

6A to 6F show the current flow direction when the electric energy is recovered from the battery cell B ₅ and the current flow when supplying the electric energy accumulated in the transformer 45 after being recovered to the battery cell B ₂ It can be seen that the directions are the same. In the battery cell balancing mode using the different parity path as described above, the electric energy recovered from the battery cell B ₅ is accumulated in the primary winding L1 of the transformer 45, and the primary winding L1 To the battery cell B ₂ .

The first to sixth modes are periodically performed, so that the voltage levels of the Strong cell and the Weak cell become equal.

Second, referring to FIGS. 8A to 8F and 9, a balancing operation of the battery cell using the different parity path for supplying the electric energy stored in the even battery cell even to the odd battery cell odd will be described. Respectively. Here, it is assumed that the battery cell B ₄ is a strong cell and the battery cell B ₁ is a week cell.

8A to 8F show the current flow direction when the electric energy is recovered from the battery cell B ₄ and the electric current stored in the transformer 45 after being recovered to the battery cell B ₁ It can be seen that the directions are the same. 8A to 8F, in the battery cell balancing mode using the different parity path, the electric energy recovered from the battery cell B ₄ is accumulated in the primary winding L1 of the transformer 45, And is supplied from the winding L1 to the battery cell B ₁ .

As a result, when comparing Figs. 8A to 8F with Figs. 7A to 7F, it can be seen that the current flow directions are opposite to each other and the remaining operations are similar to each other.

Third, referring to FIGS. 10A to 10F and 11, a balancing operation of the battery cell with respect to the same parity path for supplying the electric energy stored in the even battery cell even to the excellent battery cell (even) Respectively. Here, it is assumed that the battery cell B ₄ is a strong cell and the battery cell B ₂ is a weak cell.

In the first mode (t ₀ -t ₁ ), the control unit (not shown in the figure) is connected to the switches S _4L and S _4R of the fourth access path 43_4 and the switches S _5L and S _5R of the fifth access path 42_5 ) and a second transmission path (the switch (Q _2L, Q _2R outputs a switch control signal (gate signal), the switch (S _4L, S _{4R) on), (S 5L, S 5R} ) of 44_2), (Q _2L , Q _2R ) are turned on.

In this way, the positive terminal (+) is a primary winding (L1) of the fifth access path (42_5) and a second transmission path to the transformer 45 through a (44_2) of the battery cell (B _4), as shown in Figure 10a connected to the other side tab is, the negative terminal of the battery cell (B ₄₎ of the (-) is connected to one tap of the primary winding (L1) of the transformer (45) through a fourth access path (43_4). Therefore, the electric energy of the battery cell B ₄ is transferred to the primary winding L1 of the transformer 45 and accumulated.

When the strong cell is connected to the transformer 45 in the collect mode using the switch as described above, and then the weak cell is connected to the transformer 45 using the switch in the release mode, there is a dead time between the collect mode and the release mode a dead time is required. The recovered electric energy is circulated inside the transformer 45 at the dead time.

The second mode (t ₁ -t ₂ ) is a mode for forming an electric energy circulation path before reaching the dead time. To this end, the switch Q _1L of the first transmission path 44_1 is turned on in advance as shown in FIG. 10B.

The third mode (t ₂ -t ₃ ) is a mode in which the circulation of the recovered electric energy is started. To do so, the switches S _4L and S _4R of the fourth access path 43_4 and the switches S _5L and S _5R of the fifth access path 42_5 are turned off. Thereby, an electric energy circulation path via the primary winding L1 and the secondary winding L2 of the transformer 45 is formed as shown in Fig. 10C.

The fourth mode (t ₃ -t ₄₎ is made of a pre-treatment operation prior to the transmitting the electrical energy stored in the transformer 45, a weak cell in a battery cell (B ₂₎ mode. At this time, the switch S _2R of the second access path 42_2 and the switch S _3R of the third access path 42_3 are turned on in advance as shown in FIG. 10D.

The fifth mode (t ₄ -t ₅ ) is a mode in which electric energy accumulated in the transformer 45 starts to be supplied to the battery cell B ₂ , which is a wick cell. At this time, the switches Q _2R and Q _2L of the second transmission path 44_2 are turned off. Thus, the electric energy supply path is formed as shown in FIG. 10E, and the electric energy accumulated in the secondary winding L2 of the transformer 45 starts to be supplied to the battery cell B ₂ .

The sixth mode t ₅ -t ₆ is a mode for performing the operation of turning on the switch S _2L of the second access path 43_2 and the switch S _3L of the third access path 42_3. 10F so that the electric energy accumulated in the secondary winding L2 of the transformer 45 _flows through the switches S _2L , S _2R , S _3L , S _3R And is supplied to the battery cell B ₂ .

10A to 10F, a current flow direction when recovering electric energy from the battery cell B ₄ and a current flow when supplying the electric energy stored in the transformer 45 after being recovered to the battery cell B ₂ Direction is reversed. 10A to 10F, in the battery cell balancing mode using the different parity path, the electric energy recovered from the battery cell B ₄ is accumulated in the secondary winding L2 of the transformer 45, And is supplied from the winding L2 to the battery cell B ₂ .

The first to sixth modes are periodically performed, so that the voltage levels of the Strong cell and the Weak cell become equal.

Fourth, referring to FIGS. 12A to 12F and FIG. 13, a balancing operation of the battery cell using the same parity path for supplying the electric energy stored in the odd number of battery cells (even) to the odd number of battery cells (odd) Respectively. Here, it is assumed that the battery cell B ₅ is a strong cell, and the battery cell B ₁ is a week cell.

12A to 12F, a current flow direction when the electric energy is recovered from the battery cell B ₅ and a current flow when supplying the electric energy accumulated in the transformer 45 after being recovered to the battery cell B ₁ It can be seen that the directions are different. 12A to 12F, in the battery cell balancing mode using the same parity path, the electric energy recovered from the battery cell B ₅ is accumulated in the secondary winding L2 of the transformer 45, And is supplied from the winding L2 to the battery cell B ₁ .

As a result, when comparing FIGS. 12A to 12F with FIGS. 10A to 10F, it is found that the current flow directions are opposite to each other, and the remaining operations are similar to each other.

14 (a) and 14 (b) are waveform diagrams showing experimental results of the battery cell balancing circuit according to the present invention.

14 (a) shows the current (i _L1 ) of the primary winding of the transformer 45 and the current (i _L2 ) of the secondary winding when battery cell balancing is performed using the same parity path (even to even) Respectively. As described above, when battery cell balancing is performed using the same parity path, the electric energy recovered from the strong cell in the collector mode is accumulated in the primary winding L1 of the transformer 45, And circulated by the transformer 45 during the dead time. Thereafter, in the release mode, the electric energy stored in the primary winding L1 of the transformer 45 is transferred to the secondary winding L2 and then supplied to the wick cells.

14 (b) shows the current (i _L1 ) of the primary winding of the transformer 45 and the current (i _L2 ) of the secondary winding when battery cell balancing is performed using a different parity path (even to odd) Respectively. As described above, when battery cell balancing is performed using a different parity path, the electric energy recovered from the strong cell in the collector mode is accumulated in the primary winding L1 of the transformer 45, And circulated by the transformer 45 during the dead time. Thereafter, in the release mode, the primary cell L1 of the transformer 45 is supplied directly to the wick cells.

Although the preferred embodiments of the present invention have been described in detail above, it should be understood that the scope of the present invention is not limited thereto. These embodiments are also within the scope of the present invention.

40: Battery cell balancing circuit 41: Battery pack
42: first access unit 43: second access unit
44: Electric energy transfer part 45: Transformer

Claims (12)

A battery pack having a plurality of battery cells connected in series;
A first access unit having an access path connected between one terminal of the odd-numbered battery cell and the first common node in the battery pack;
A second access unit having an access path connected between the other terminal of the odd-numbered battery cell and the second common node in the battery pack;
An electrical energy transfer unit having two transfer paths for transferring electric energy recovered or supplied through the first common node; And
A transformer connected between the second common node and the electrical energy transfer unit for battery balancing of the battery pack to temporarily accumulate the electric energy recovered from the strong battery cells of the battery pack, A one-to-one discharge / charging operation is performed between the strong battery cell and the wick battery cell,
The transformer
A primary winding connected between the second common node and a second transmission path of the electrical energy transfer unit; And
And a secondary winding connected between the second common node and a first transmission path of the electric energy transfer part,
Wherein when the strong cell and the weak cell of the battery pack have different parities, electric energy recovered from the strong cell is accumulated in the primary winding, and electric energy is supplied to the weak cell from the primary winding,
If the strong cell and the weak cell are the same parity, the electric energy recovered from the strong cell is accumulated in the primary winding and is transferred to the secondary winding, and electric energy is transferred from the secondary winding to the wick cell The battery cell balancing circuit using the transformer.
The battery cell balancing circuit using a transformer according to claim 1, wherein the access path of any one of the first accessing unit and the second accessing unit includes a pair of switches connected in series.
3. The apparatus of claim 2, wherein the switch
Wherein the battery cell balancing circuit is one of a MOS transistor, a BJT (Bipolar Junction Transistor), and an IGBT (Insulated Gate Bipolar Transistor).
4. The apparatus of claim 3, wherein the switch
Diode connected in parallel with the battery cell balancing circuit using a transformer.
The electric energy transfer apparatus according to claim 1,
Wherein the battery cell balancing circuit includes a pair of series-connected switches.
6. The apparatus of claim 5, wherein the switch
Wherein the battery cell balancing circuit is one of a MOS transistor, a BJT (Bipolar Junction Transistor), and an IGBT (Insulated Gate Bipolar Transistor). 6. The apparatus of claim 5, wherein the switch
Diode connected in parallel with the battery cell balancing circuit using a transformer.
delete delete delete The transformer of claim 1, wherein the primary and secondary windings of the transformer
Wherein an electric energy circulation path is established in conjunction with a transmission path of the electric energy transfer unit before electric energy recovered from the Strong cell of the battery pack is transferred to the wick cell.
2. The method of claim 1, wherein the flow direction of the electric energy via the first access portion, the second access portion,
Wherein the power cell balancing circuit is determined according to the radix of the strong cell or the odd or even number of the wick cell.

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