KR20180057016A - Large-sclae battery system for inter-cell or inter-batterytray balancing - Google Patents

Abstract

The present invention relates to a collective battery system comprising: a first battery string unit including a plurality of cells connected in series; a second battery string unit including a plurality of cells connected in series, and connected in series to the first battery string unit; a first loop connected to the first battery string unit in parallel, and including a first switch and a main winding on a ground path; a second loop connected to the second battery string unit in parallel, including a main winding of the first loop on a common ground path, and including a second switch on an independent ground path; and a switching control unit for controlling switching for the switches. The present invention relates to a balancing technique optimized for a large-scale collective battery system, and provides an active balancing circuit configuration capable of rapidly performing inter-cell balancing while minimizing the number of converters.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an accumulator battery system for balancing battery cells and trays,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated battery system, and more particularly, to an integrated battery system including a circuit configuration for performing battery-cell balancing and / or inter-tray balancing in a system including a large battery cell.

Battery cell balancing technology is a technique for eliminating the voltage deviation between battery cells, and is mainly divided into passive balancing and active balancing techniques. Passive balancing is a technique for eliminating the inter-cell voltage deviation by discharging a cell having a higher voltage than other cells to the resistance element, and active balancing transfers energy from a relatively high voltage cell to a relatively low voltage cell, .

Recently, demand for large-capacity battery systems such as electric cars of about 20 kWh, electric buses of about 100 kWh, and electric ferries of about 1 MHh have increased and interest in active balancing technology with less energy loss has been increased.

Active balancing has been evaluated as a way to increase system complexity and reduce cost-to-energy, but various technologies are under study.

For example, referring to FIG. 1, US Pat. No. 7,193,392 discloses a simple active balancing circuit 100 comprised of a switch 120 for selecting one cell of the battery strings 110 and a converter 130 for exchanging energy. . One side of the converter 130 is connected to a series terminal of the battery string 110 and the other side of the converter 130 is connected to one cell through the switch 120 to balance the energy through the transfer of energy between the cell and the string. That is, when the cell having the highest voltage is connected to the converter 130 through the switching control, the battery 130 is dispersively charged from the cell to the entire battery string 110, Balancing is performed by providing the voltage of the entire cell 110 through the converter 130 to the lowest cell.

US Pat. No. 6,624,612 (refer to FIG. 2) has an external energy storage device 240 selectively connected to the battery strings 210a to 220. The external energy storage device 240 is used as an energy buffer The cell having a high voltage is connected to the external energy storage device 240 to temporarily store the energy, and then the cell having the low voltage is connected to charge the energy stored in the external energy storage device 240 with the energy temporarily stored, The balancing circuit 200 is introduced.

There is another way to use LC resonant circuit with active balancing technology.

Conventional active balancing technology is a suitable model to be applied to a small scale cell group, requiring a large number of switches and converters and taking a long time for cell balancing, which is not suitable for a commercialized high power integrated battery system.

Passive balancing is still more effective for 20kWh electric vehicles. Despite the energy saving effect of active balancing technology, vehicles that use passive balancing have a higher percentage of actual commercial vehicles.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an integrated battery system having a circuit configuration capable of quickly balancing between cells in a high-power large-scale integrated battery model, constituting a balancing circuit with improved system complexity The purpose.

The above object is achieved by an integrated battery system according to an aspect of the present invention, comprising: a first battery string part including a plurality of cells connected in series; A second battery string part including a plurality of cells connected in series and connected in series to the first battery string part; A first loop connected in parallel with the first battery string portion, the first loop including a first switch and a main winding line on the guitar; A second loop connected in parallel with the second battery string part, the second loop including a common line of the first loop on the cavity, and including a second switch on an independent circuit; And a switching controller for controlling the switching of the switches.

Here, the balancing unit comprising at least two or more serially connected balancing units including the first battery string part, the second battery string part, the first loop, and the second loop may be used, The main control lines included in the balancing unit are wound and coupled to the core, and the switching control unit controls the switches included in the plurality of balancing units to perform energy transfer between the plurality of balancing units .

And each of the battery string portions includes a local core for transferring energy between cells, the first loop including a first local winding coupled to a first local core of the first battery string portion, And the loop may include a second local winding coupled to a second local core of the second battery string portion.

The diode further includes a diode connected in parallel to the first switch and the second switch to form a reverse current path.

The present invention provides an active balancing circuit configuration capable of quickly performing inter-cell balancing while minimizing the number of converters, which is a balancing technique optimized for a large-scale integrated battery system.

Figure 1 shows a configuration of an active balancing circuit of a conventional DC converter type, representative of US 7,193,392;
FIG. 2 is an exemplary configuration of an active balancing circuit utilizing a conventional external storage device, which is a representative of US 6,624,612;
3 is a circuit conceptual diagram for explaining a schematic configuration for active balancing of an assembled battery system according to an embodiment of the present invention;
4 is an internal circuit diagram of a balancing unit according to an embodiment of the present invention;
5 is a circuit configuration diagram for performing internal balancing of a battery string part according to an embodiment of the present invention;
FIGS. 6 and 7 are circuit diagrams illustrating energy transfer according to internal balancing of the battery string portion of FIG. 5; And
FIG. 8 is a graph showing the magnitude of the current generated in the energy transfer according to FIG. 7 in the time domain.

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

3 is a circuit conceptual diagram illustrating a schematic configuration for active balancing of an assembled battery system according to an embodiment of the present invention.

Referring to FIG. 3, the collective battery system according to the embodiment of the present invention includes a plurality of balancing units 10a to 20, a switching control unit 30, and a main power line 40.

The plurality of balancing units 10a to 20 includes a battery string for supplying power to the main power line 40 and a circuit configuration accompanying the battery string. The balancing units 10a to 20 are conceptual units that are divided into unit units in terms of active balancing.

The switch control unit 30 controls so that the energy is transmitted to the switches (Q ₁ ~ Q _N), the control unit by balancing between (10a ~ 20) comprising a balancing unit (10a ~ 20).

4 is an internal circuit diagram of the balancing units 10a to 20 according to the embodiment of the present invention. Referring to Fig. 4, the circuit configuration of the balancing unit 1 (10a) will be described as an example of the internal circuit configuration of the balancing units 10a to 20 having the same structure.

The balancing unit 1 10a comprises a first battery string part B ₁ , a second battery string part B ₂ , a first loop L ₁ and a second loop L ₂ .

The first battery string part B ₁ includes a plurality of cells connected in series and also includes a balancing circuit for performing cell balancing.

The second battery string part B ₂ is connected in series with the first battery string part B ₁ and includes a plurality of series connected cells and a cell balancing circuit.

The first loop L ₁ is formed in parallel with the first battery string portion B ₁ and has a first switch Q ₁ , a first common-rail line CL ₁ , (M ₁ ).

The second loop L ₂ is connected in parallel with the second battery string part B ₂ and forms a part of the branch line with the first loop L ₁ , CL ₁ ) is installed. And a second switch Q ₂ and a second local winding M ₂ on the branch line branched from the common branch line with the first loop L ₁ . The first switch Q ₁ and the second switch Q ₂ are connected in parallel with the reverse freewheeling diodes D ₁ and D ₂ , respectively.

The balancing unit 2 (10b) has the same circuit configuration as the balancing unit 1 (10a). That is, the third battery string part B ₃ corresponding to the first battery string part B ₁ , the fourth battery string part B ₄ corresponding to the second battery string part B ₂ , third loop corresponding to L ₁₎ (L _3), the second cavity Sovereign corresponding to the second loop (L ₂₎ a fourth loop (L _4), first cavity windings (CL ₁₎ corresponding to the line ( CL ₂ ) and the like.

Of note is a ring coupled between the DC converter (CL ₁ CL ~ _N) is the parameter for the energy transfer.

Balancing unit 1 (10a) and a balancing unit 2 (10b) comprises first and second co-windings (CL _1, CL ₂₎ is ring cross couple is passed energy between the balancing unit (10a, 10b), the storage of the battery Since the power is DC, the switching controller 30 operates as a DC converter in which energy is transferred between the dominant lines CL ₁ and CL ₂ when on / off through switching.

For example, when energy is to be transmitted from the first battery string part B ₁ included in the balancing unit 1 10a, when the first switch Q ₁ is turned on in the switching control part 30, The surplus energy of the string portion B ₁ is operative to charge the third battery string portion B ₃ located on the upper side of the neighboring balancing unit 2 10b while when the first switch Q1 is turned off, The lower battery string portion B _{2 of} the first battery 10a and the fourth battery string portion B ₄ located below the balancing unit 2 10b. Likewise, the odd-numbered battery string portions located above the balancing unit 3, balancing unit 4, .... balancing unit N are charged by the induction current flowing through the free wheeling diode during the turn-on operation of the first switch Q ₁ , The even-numbered battery string portion located at the bottom is charged due to the induced current flowing in the reverse direction through the free wheeling diode during the turn-off operation of the first switch Q ₁ .

It should be noted that unlike the case where the common dominant lines CL _{1 to N} are coupled to each other so that the energy to be delivered supplies energy to the entire battery string parts B ₁ to B _N , the local windings M ₁ to Mn Are wound and coupled to the inner transcore of the battery string portion connected in parallel to each other. When the energy is transmitted through the common main winding lines CL _{1 to N} , an induced current flows in the local windings M ₁ to Mn, and accordingly an induced electromotive force is generated in the inner trans core of the battery string portion B _m , So that energy can be intensively transmitted to the selected individual cells.

Therefore, the balancing circuit according to the embodiment of the present invention is capable of transferring energy between battery strings B _{1 to n} connected in series with a plurality of cells, and transferring energy between the battery strings B _{1 to n} and individual cells .

There are various methods for selecting individual cells to which energy is transmitted. That is, the circuit configuration in which the local winding M _m is wound and coupled to the inner trans core of the battery string portion B _m can be variously selected. For example, it may be coupled to a converter corresponding to a small group of cells of the type disclosed in FIG. 1 as background art, and may also be coupled to a converter that can be installed in the energy delivery system described in FIG.

FIG. 5 is a block diagram of a balancing circuit of a battery string according to an embodiment of the present invention.

Referring to FIG. 5, a battery string B _{1 ~ n} according to an embodiment of the present invention includes a plurality of cells C _{1 ~N} connected in series, a loop L connected in parallel to each cell, , A pair of diodes (d _{1 to N} ) and a transistor switch (B _m Q _{1 to N} ) provided on the loop, and a local winding M _nn ).

Two cells (C ₁ / C ₂ .... C _{N -1} / C _N ) are paired to have additional circuitry for active balancing, and this structure is formed identically on two cell basis, This is in the same context as forming a balancing unit in string units.

On the basis of the same principle, the electromotive force is induced in the coupled local windings M _nn by the switching controller 30 selecting the cell having the surplus energy and by controlling on / off the transistor switch connected in parallel to the selected cell The induced current charges the cells.

5 is an exemplary illustration showing that the balancing circuit configuration of the battery string portion according to the embodiment of the present invention can be formed similarly to the balancing circuit configuration of a balancing unit unit which is a large cell group.

FIG. 6 is a circuit diagram for explaining an energy transfer process among six cells connected in series in the battery string part 1 (B1) according to an embodiment of the present invention.

Referring to FIG. 6, the battery string part 1 (B1) is divided into three parts. First, two cells C1 and C2 are paired, and C1 is connected to the upper cell and C2 is connected serially to the lower cell. The cell C3 is located in the lower part of the cell C2, the cell C3 is the upper cell, and the paired C4 cell is connected in series to the cell. In the same connection structure, C5 and C6 cells are connected in series to the bottom of C4.

A case where the voltage of the cell C1 is relatively high among the six cells and the energy is to be transmitted from the cell C1 will be described as an example.

The switching control unit 30 turns on the transistor switch B ₁ Q ₁ connected in parallel with the cell C1. As a result, the current flows from the C1 cell through the transistor switch (B ₁ Q ₁ ) and the local winding (M ₁₁ ), and electromotive force is induced in the opposite direction to suppress the voltage rise of the winding, Current flows in the direction opposite to the switches B ₁ Q ₃ and B ₁ Q ₅ through the diodes d ₃ and d ₅ connected in parallel with the cell and is provided to the positive terminal side of the cells C 3 and C 5 to charge each cell.

On the other hand, the operation of the circuit when the switching control unit 30 turns off, that is, when the transistor switch B ₁ Q ₁ connected in parallel with the cell C1 is switched to the fly-back conversion will be described with reference to FIG.

When the switching control unit 30 turns off the transistor switch B ₁ Q ₁ connected in parallel with the cell C1, the electromotive force is induced in the direction of holding the voltage of the local winding M ₁₁ , Are transferred to the cells C2, C4, and C6 to charge the cells.

FIG. 8 is a graph showing the energy transfer process in the case of performing flyback conversion of the C1 cell in the time domain. When the B ₁ Q ₁ transistor switch is turned off, an induced current is generated in the cells C2, C4, .

6 to 8 illustrate the process of coupling the local windings M _nn to each other to perform cell balancing in the battery string part B, but the internal local winding M _{nn is} connected to the battery string part B It can be coupled with the local coils M _n connected in parallel to the outside and charged with the energy supplied from the outside.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

For example, in the drawings disclosed in FIGS. 5 to 7, by adding an additional switch to block the current flowing in the reverse direction through the diode in the battery string portion, the cells supplied with energy supplied through the local winding are individually selected It is possible to deform it in such a manner as to control it.

Therefore, it should be understood that the embodiments of the present invention are illustrative and that the protection scope of the present invention affects the technical ideas and equivalents of the present invention described in the claims.

Claims (4)

In the assembled battery system,
A first battery string including a plurality of cells connected in series;
A second battery string part including a plurality of cells connected in series and connected in series to the first battery string part;
A first loop connected in parallel with the first battery string portion, the first loop including a first switch and a main winding line on the guitar;
A second loop connected in parallel with the second battery string part, the second loop including a common line of the first loop on the cavity, and including a second switch on an independent circuit; And
And a switching controller for controlling the switching of the switches.
The method according to claim 1,
And a balancing unit chain including at least two balancing units including the first battery string part, the second battery string part, the first loop, and the second loop,
Wherein the dominant lines included in the at least two balancing units are wound and coupled to a core of the cavity,
Wherein the switching control unit controls the switches included in the plurality of balancing units to perform energy transfer among the plurality of balancing units.
3. The method of claim 2,
Each of the battery string portions includes a local core for transferring energy between cells,
Wherein the first loop includes a first local winding coupled to a first local core of the first battery string portion,
And the second loop includes a second local winding coupled to a second local core of the second battery string portion.
4. The method according to any one of claims 1 to 3,
Further comprising a diode connected in parallel to each of the first switch and the second switch to form a reverse current path.

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