KR20190083449A - Balancing devices for battery management systems - Google Patents

Abstract

The present invention relates to a balancing device for a battery management system and, more specifically, to a balancing device for a battery management system, capable of controlling energy delivery between batteries connected to the same position relative to a coil and are placed separately without sharing the same coil. The balancing device includes: a source battery cell including a source battery and a source switch for controlling the discharge of the source battery in response to a source control signal; a source sub battery cell including a source sub battery and a source sub switch for controlling the discharge of the source sub battery in response to a source sub control signal; a target battery cell including a target battery and a target switch for controlling the charge of the target battery in response to a target control signal; a target sub battery cell including a target sub battery and a target sub switch for controlling the charge of the target sub battery in response to a target sub control signal; and a control circuit providing the source control signal for keeping the source switch on, the target control signal for keeping the target switch on and the target sub control signal for keeping the target sub switch on during a first section, in which the source switch is kept on and the target sub switch is kept on, and a second section, in which the source switch is kept on and the target switch is kept on.

Description

[0001] The present invention relates to a balancing device for a battery management system,

The present invention relates to a balancing device for a battery management system, and more particularly, to a balancing device for a battery management system for controlling energy transfer between batteries that are separated from each other and are connected to the same position relative to windings.

Recently, technologies for efficiently using electric energy such as electric vehicles, smart grid, and energy storage system (ESS) have been developed.

In particular, with the spread of renewable energy, interest in energy storage systems that can maximize the storage and quality of electric power and efficiency of energy use as core of smart grid is increasing.

The energy storage system can include a large capacity battery module having a plurality of battery cells and is a technique for storing the remaining power (residual energy) in the power system to supply it when and where it is needed, thereby optimizing the quality and efficiency of the power System.

A device for managing the battery module more efficiently and stably is a battery management system.

The battery management system may be connected to a plurality of battery cells to read a voltage value of each battery cell through an analog to digital converter, and then control charging or discharging of the battery cell.

When a plurality of batteries are connected and used as one battery module, a voltage difference may occur between the batteries due to chemical differences, differences in physical properties, or differences in usage periods of the batteries constituting the battery modules.

The lifetime of the battery module may be shortened due to the difference in voltage between the batteries. Therefore, there is a problem that the entire battery packaged in the packaged battery module must be replaced with a new battery module due to performance degradation such as voltage drop of one single cell (single battery cell) .

Therefore, a cell balancing process may be required by a battery management system that allows the voltage of each battery cell to be kept the same when charging or discharging a large capacity battery used in an energy storage system (ESS) and an electric vehicle.

A passive balancing method and an active balancing method may be proposed as balancing between batteries.

The manual balancing method can be accomplished by removing excess energy from a battery with a greater energy than other batteries through a resistor or the like.

However, the heat generated in the process of removing excess energy may cause other problems in the battery module, and energy consumption in the balancing process is high.

On the other hand, the active balancing method can be achieved by transferring the energy of a battery having a higher energy level to a battery having a lower energy level than that of another battery.

The active balancing method is advantageous in that a switch is disposed in a battery cell and can be performed through control of each switch, thereby wasting less energy than a manual balancing method.

Meanwhile, in a cell balancing circuit that uses one winding per two battery cells, there are two conventional methods of transferring energy between battery cells.

One is the way to transfer energy between adjacent cells (buck-boost). It is used to transfer energy between two adjacent cells sharing a single winding.

And the other is to transfer energy between cells that do not share the same winding. In this case, energy is transferred only to cells connected to different positions with respect to the winding (flyback method).

If there is a need to transfer energy between cells connected to the same position relative to the windings as they do not share the same winding, the two methods described above must be used sequentially. In this case, a single battery cell is further required to transmit the energy, and the operation of the balancing circuit is further performed, the energy transfer efficiency is lowered and the transfer speed is lowered.

Xu, S. Li, C. Mi, Z. Chen, and B. Cao, "SOC Based Battery Cell Balancing with Novel Topology and Reduced Component Count," Energies, vol. 6, p. 2726, 2013.

SUMMARY OF THE INVENTION The present invention has been devised to solve the conventional problems as described above, and it is an object of the present invention to provide a balancing device for a battery management system for controlling energy transfer between batteries connected to the same position have.

One aspect of the apparatus of the present invention includes a source battery cell including a source battery and a source switch for controlling a discharge of the source battery in response to a source control signal; A source sub battery including a source sub battery and a source sub switch for controlling a discharge of the source sub battery in correspondence with a source sub control signal; A target battery cell including a target battery and a target switch for controlling charging of the target battery in response to a target control signal; A target sub-battery and a target sub-battery including a target sub-switch for controlling charging of the target sub-battery in response to a target sub-control signal; And a second period during which the source switch is maintained in an on state and the target sub-switch is maintained in an on-state, and during a second period in which the source switch remains on and the target switch remains in an on- And a control circuit for providing the source control signal for maintaining the ON state, the target control signal for maintaining the ON state of the target switch, and the target sub control signal for maintaining the ON state of the target sub-switch.

In addition, the source battery and the source sub battery in one aspect of the apparatus of the present invention are directly connected and share a source winding, and the target battery and the target sub battery are directly connected and share a target winding.

In addition, the control circuit on one side of the device of the present invention turns on the source switch and the target sub-switch during a first interval to make the source and target windings magnetically coupled.

In addition, the control circuit on one side of the device of the present invention maintains the source switch in an on state during a second interval, turns off the target sub-switch, turns on the target switch, To be delivered to the target battery.

Further, the control circuit on one side of the device of the present invention turns off the target sub-switch during the second section and turns on the target switch after a dead time.

Further, the control circuit of one aspect of the apparatus of the present invention turns off the source switch and the target switch during the third period.

Further, the control circuit on one side of the device of the present invention turns off both the source switch and the target switch during the fourth period until the first current becomes zero after the second current becomes zero So that current flows while charging the source sub-battery.

The present invention relates to a control method for transferring energy between batteries connected to a balancing circuit at the same position relative to a winding and not sharing the same winding, .

The present invention also relates to a control method for transferring energy between batteries connected to the same position relative to windings in a balancing circuit without sharing the same winding, .

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a block diagram showing a balancing apparatus for a battery management system according to an embodiment of the present invention.
2 is a circuit diagram illustrating a battery cell of a balancing device of the battery management system according to the embodiment of FIG. 1 and a control circuit for controlling the battery cell in more detail.
FIGS. 3 to 6 are diagrams illustrating a current change of a balancing device of a battery management system operating according to an embodiment of the present invention.
FIG. 7 is a diagram showing a current change and a voltage change according to FIGS. 3 to 6. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments will be described in detail below with reference to the accompanying drawings.

The following examples are provided to aid in a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, this is merely an example and the present invention is not limited thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intention or custom of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification. The terms used in the detailed description are intended only to describe embodiments of the invention and should in no way be limiting. Unless specifically stated otherwise, the singular form of a term includes plural forms of meaning. In this description, the expressions "comprising" or "comprising" are intended to indicate certain features, numbers, steps, operations, elements, parts or combinations thereof, Should not be construed to preclude the presence or possibility of other features, numbers, steps, operations, elements, portions or combinations thereof.

It is also to be understood that the terms first, second, etc. may be used to describe various components, but the components are not limited by the terms, and the terms may be used to distinguish one component from another .

Hereinafter, exemplary embodiments of a battery management system according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a balancing apparatus for a battery management system according to an embodiment of the present invention.

Referring to FIG. 1, a balancing device of a battery management system may include a plurality of battery cells and a control circuit 300 for generating control signals for controlling the respective battery cells.

More specifically, the balancing device of the battery management system includes a battery string 100 connected in series and a balancing circuit 200 for balancing between each battery constituting the battery string 100 and a balancing circuit 200 for balancing And a control circuit 300 for generating a control signal for controlling the operation.

The balancing circuit 200 may include switches corresponding to the respective batteries to control the batteries constituting the battery string 100. [ Here, the battery cell can be understood as a unit including a battery and a switch directly connected to the battery. The balancing circuit 200 may include windings arranged for transfer of energy between respective battery cells and a core coupled to each of the windings.

The control circuit 300 measures or senses various states of the batteries constituting the battery string 100 to detect the temperature of the battery module, the ambient temperature of the battery module, the voltage of the battery module, and the discharge (Or a value obtained by multiplying the rated capacity (Ah) of the battery module by the C-rate (current rate)), etc., to inform the operator of the battery condition of the battery, As shown in FIG.

The control circuit 300 measures cell balancing and SOC (State of Charge) of the cell by measuring voltage, current, and temperature of each battery cell, and determines the safety, charge, and charge of the energy storage system (ESS) Or discharge can be controlled.

For this purpose, the control circuit 300 includes a measuring unit for measuring an open circuit voltage of each battery cell, and a control unit 300 for controlling the open / A control unit for determining a battery cell as a source battery cell and determining a battery cell having an open-circuit voltage lower than the reference voltage as a target battery cell to provide a control signal to transfer energy from the source battery cell to the target battery cell, And a gate driving circuit for generating a gate signal for turning on or off the switch in accordance with the control signal.

Here, the reference voltage may be variously set according to the designer or the balancing method of the balancing device of the battery management system. The source battery means a battery which supplies energy according to the judgment of the control circuit 300 and the target battery means a battery which receives the energy from the source battery according to the judgment of the control circuit 300. [

A battery cell including a source battery and a source switch for controlling the source battery can be referred to as a source battery cell. Further, a battery cell including a target battery and a target switch for controlling the target battery may be referred to as a target battery cell.

And, the source sub-battery refers to a battery that is directly connected to the source battery and shares the source winding, and the target sub-battery may refer to a battery that is directly connected to the target battery and shares the target winding.

A battery cell including a source sub-battery and a source sub-switch for controlling the source sub-battery may be referred to as a source sub-battery cell. Further, a battery cell including a target sub-battery and a target sub-switch for controlling the target sub-battery may be referred to as a target sub-battery cell.

The source battery, the source sub-battery, the target battery, and the target sub-battery may denote various batteries of the battery string 100, and will be described as first to fourth batteries. The source switch, the source sub-switch, the target switch, and the target sub-switch may also be expressed by the first to fourth switches and the like. The battery cell may also be represented by first to fourth battery cells.

FIG. 2 is a circuit diagram showing a battery cell of a balancing device of the battery management system according to the embodiment of FIG. 1 and a control circuit 300 for controlling the battery cell in more detail.

Referring to FIG. 2, the balancing device of the battery management system may include a battery string 100, a balancing circuit 200, and a control circuit 300.

2 is a circuit diagram illustrating a battery cell of some of the balancing devices of the battery management system. Referring to FIG. 2, it can be seen that one battery cell is composed of one battery, a switch connected in parallel to the battery, and a coil connected to the battery and the switch.

The balancing device of the battery management system includes a battery string 100 and a balancing circuit 200 in which the battery cell units are continuously arranged when two battery cells paired to share the same winding are regarded as one unit, And a control circuit 300 for providing a control signal for controlling each battery cell.

In order to balance the voltages of the battery cells, the control circuit 300 can transfer the current from the battery cell having the high voltage of the battery to the battery cell having the low battery voltage.

FIG. 2 exemplifies any four battery cells (CELL1 to CELL4) among a plurality of battery cells constituting the balancing device of the battery management system.

2, the first battery cell CELL1 and the second battery cell CELL2 are disposed adjacent to each other so as to share the first winding L1 and the third battery cell CELL3 and the fourth battery cell CELL4 are disposed adjacent to each other, Are arranged adjacent to each other so as to share the second winding (L2). The second battery cell CELL2 and the third battery cell CELL3 may be disposed adjacent to each other, and may include at least one other battery cell unit therebetween.

More specifically, the battery string 100 of the balancing device of the battery management system may include a plurality of batteries C1, C2, C3, C4, and a balancing circuit 200 for energy balancing between the batteries Switches and windings L1, S1, S2, L2, S3, S4.

2, the first battery cell CELL1 may include a first battery C1, a first switch S1 and a first winding L1, a second battery cell CELL2 may include a second battery C2 ), A second switch S2, and a first winding L1.

The first battery cell CELL1 and the second battery cell CELL2 may be disposed adjacent to each other. The first battery C1 and the second battery C2 may be arranged such that a positive electrode and a negative electrode, which are opposite in polarity to each other, are disposed adjacent to each other.

The first battery cell CELL1 and the second battery cell CELL2 may share the first winding L1. That is, one end of the first winding L1 is connected to both the first battery C1 and the second battery C2, and the other end of the first winding L1 is connected to the first switch S1 and the second switch S2 ). ≪ / RTI >

As described above, the first battery cell CELL1 and the second battery cell CELL2 may have different polarities of the batteries connected to one end of the first coil L1 shared by them, and the other configurations may be the same.

In addition, since the battery cell units adjacent to the two battery cells are continuously arranged as described above, the battery cells included in the balancing apparatus of the battery management system can be configured to be even.

The third battery cell CELL3 of FIG. 2 may include a third battery C3, a third switch S3 and a second winding L2 in the same manner as the first battery cell CELL1, The fourth battery cell CELL4 includes the fourth battery C4 and the fourth switch S4 in the same manner as the second battery cell CELL2 and the second battery CELL4 shared by the third battery cell CELL3, (L2).

The number of battery cells included in the balancing device of the battery management system can be variously set according to the designer's intention or the size of the voltage required in the system requiring the balancing device of the battery management system.

Hereinafter, the first battery cell CELL1 and the second battery cell CELL2 can be understood as any two battery cells in the balancing apparatus of the battery management system that share the first coil L1 and are adjacent to each other, The fourth battery cell CELL3 and the fourth battery cell CELL4 share the second winding L2 and can be understood as any two battery cells in the balancing device of the adjacent battery management system.

Hereinafter, the configuration of the battery cells will be described in more detail.

The first to fourth batteries C1 to C4 may be any ones of the batteries constituting the battery string 100. The first battery C1 and the second battery C2 are directly connected to each other , And the third battery C3 and the fourth battery C4 may be directly connected to each other.

The first to fourth switches S1 to S4 are switches for controlling charging or discharging of the batteries C1 to C4 included in the corresponding battery cells CELL1 to CELL4, respectively. The first to fourth switches S1 to S4 may be BJTs, metal oxide semiconductors (MOSFETs), insulated gate bipolar transistors (IGBTs), or the like, as various switches for switching the current flow.

The first switch S1 may be turned on or turned off in response to the first control signal CON1 provided by the control circuit 300 and the second switch S2 may be turned on or off by the control circuit 300 The third switch S3 may be turned on or off in response to the third control signal CON3 provided by the control circuit 300. The third switch S3 may be turned on or off in response to the second control signal CON2, And the fourth switch S4 may be turned on or turned off in response to the fourth control signal CON4 provided by the control circuit 300. [

The first winding L1 and the second winding L2 may be connected to one core or a different core to perform energy transfer.

The first winding L1 shared by the first battery cell CELL1 and the second battery cell CELL2 has a magnetizing inductance sharing the magnetic flux with the windings in the same core and a magnetic flux of the first winding L1 The leakage inductance may be affected. Lm denotes the magnetization inductance of the coils sharing the core with the first winding L1 and the first winding L1 and Lleak1 can mean the leakage inductance of the first winding L1.

Here, the leakage inductance may be a value for a ratio indicating how much the discharged energy is transferred to the cell to be charged. Also, the second winding L2 can be modeled by dividing by the magnetizing inductance Lm and the leakage inductance Lleak2.

Here, the leakage inductance refers to the leakage inductance included in the multi-winding transformer itself, or the inductance on the winding used for the connection, or the inductance additionally connected to the circuit.

BACKGROUND ART [0002] Conventionally, a buck boost method and a flyback method are known for energy transfer between battery cells.

A buck boost energy transfer can be used to transfer energy between battery cells sharing the same winding.

For example, to transfer energy between the first battery C1 and the second battery C2 in FIG. 2 or to transfer energy between the third battery C3 and the fourth battery C4.

Fly back energy transfer can be used to transfer energy between battery cells connected to other windings.

For example, to transfer energy between the first battery C1 and the fourth battery C4 in FIG. 2 or to transfer energy between the second battery C2 and the third battery C3.

The energy of the first battery C1 may be transferred to the second battery C2 through the first winding L1 or the energy of the second battery C2 may be transferred to the first winding L1 L1 to the first battery C1. The energy of the third battery C3 is transmitted to the fourth battery C4 via the second winding L2 or the energy of the fourth battery C4 is supplied to the third battery C3 ).

The energy of the first battery C1 is transmitted to the fourth battery C4 through the first winding L1 and the second winding L2 or the energy of the second battery C2 is transmitted through the first winding L1 and the second winding L2, To the third battery (C3) through the first winding (L1) and the second winding (L2). The energy of the third battery C3 is transferred to the second battery C2 via the second winding L2 and the first winding L1 or the energy of the fourth battery C4 is supplied to the second winding L2, To the first battery (C1) through the first winding (L1).

On the other hand, according to the prior art, there was no direct energy transfer method when transferring the energy between the batteries connected to different windings and the same position (both the upper side of the windings or the lower side of the windings) unlike the above. For example, when energy is transferred between the first battery C1 and the third battery C3 in FIG. 2 or energy is transferred between the second battery C2 and the fourth battery C4, There was no way, and the energy was transferred in a form that used the buck-boost method and the flyback method sequentially (or in reverse order).

As a result, the second battery C2 or the third battery C3, which is located in the middle, is once again passed in the process of transferring the energy, the operation of the balancing circuit 200 is increased, and the loss increases. In addition, the time required for energy transfer is also increased.

The present invention relates to a control method for transferring energy between batteries connected to a balancing circuit 200 at the same position relative to a winding, which is not shared by the same winding, and is hereinafter referred to as a forward method.

3 and 7, the control circuit 300 controls the first switch S1 and the fourth switch S1 for the first period (from the start time t0 to the first time t1) The first current L1 is supplied to the first winding L1 and the second current iL2 flows to the second winding L2 so that the first winding L1 and the second winding L2 ) To become magnetically coupled (t0-t1).

4 and 7, the control circuit 300 turns off the fourth switch S4 during the second period (from the first point of time t1 to the second point of time t2) (S3). At this time, the first switch S1 is kept on. Then, the current discharged from the first battery C1 is transmitted to the third battery S3 (t1-t2).

Next, as shown in FIGS. 5 and 7, the control circuit 300 turns on the first switch S1 and the third switch S3 during the set second period (t1-t2) The first switch S1 and the third switch S3 are all turned off during the period (from the second time point t2 to the third time point t3).

At this time, when the first switch S1 is turned off, the first current iL1 flows to charge the second battery C2 and the third battery C3 (C3) flows until the second current iL2 becomes zero (T2-t3).

6 and 7, the control circuit 300 controls the first switch S1 and the third switch S3 (for example, during the fourth period t3 to the fourth time t4) So that the current flows through the second battery C2 while charging the second battery C2 until the first current iL1 becomes zero after the second current iL2 becomes zero -t4).

3 and 7, it is ideal that the first switch S1 and the fourth switch S4 are turned on at the same time at t0. However, even if two switches are turned on at a slight time difference, none.

Referring to FIGS. 4 and 7, it is ideal to turn on the third switch S3 immediately after turning off the fourth switch S4 at t1, but when the third switch S3 and the fourth switch S4 are simultaneously turned on, A short path is formed through the battery C3 and the fourth battery C4 so that it is necessary to implement a slight deadtime for safety.

At this time, the first switch S1 may be turned off for a predetermined time at t1.

Referring to FIGS. 5 and 7, it is ideal to simultaneously turn off the first switch S1 and the third switch S3 at t2, but there may be a slight delay in turning off the two switches none.)

The present invention relates to a control method for transferring energy between batteries connected to a balancing circuit at the same position relative to a winding and not sharing the same winding, .

The present invention also relates to a control method for transferring energy between batteries connected to the same position relative to windings in a balancing circuit without sharing the same winding, .

100: Battery string 200: Balancing circuit
300: control circuit

Claims (7)

A source battery cell including a source battery and a source switch for controlling a discharge of the source battery in response to a source control signal;
A source sub battery including a source sub battery and a source sub switch for controlling a discharge of the source sub battery in correspondence with a source sub control signal;
A target battery cell including a target battery and a target switch for controlling charging of the target battery in response to a target control signal;
A target sub-battery and a target sub-battery including a target sub-switch for controlling charging of the target sub-battery in response to a target sub-control signal; And
During a second period in which the source switch is maintained in an ON state and the target sub-switch is maintained in an ON state and a second period in which the source switch is maintained in an ON state and the target switch is maintained in an ON state, A target control signal for maintaining the on state of the target switch and a target sub control signal for maintaining the on state of the target sub-switch; and a control circuit Balancing device of management system. The method according to claim 1,
Wherein the source battery and the source sub-battery are directly connected and share a source winding,
Wherein the target battery and the target sub battery are directly connected and share a target winding. 3. The method of claim 2,
Wherein the control circuit turns on the source switch and the target sub-switch during a first interval such that the source winding and the target winding are magnetically coupled. The method of claim 3,
Wherein the control circuit maintains the source switch in an on state during a second period and turns off the target sub switch and turns on the target switch to cause a current discharged from the source battery to be transferred to the target battery Balancing device. 5. The method of claim 4,
Wherein the control circuit turns off the target sub-switch during a second interval and turns on the target switch after a dead time. 5. The method of claim 4,
And the control circuit turns off the source switch and the target switch during the third period. The method according to claim 6,
The control circuit turns off the source switch and the target switch during the fourth period so that the current flows while charging the source sub-battery until the first current becomes zero after the second current becomes zero. Balancing device of a battery management system.

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