KR101610923B1 - Apparatus and method for autonomous battery balancing - Google Patents

Abstract

An embodiment of the present invention relates to an apparatus and a method for autonomous battery balancing. The autonomous battery balancing apparatus comprises: at least one discharge resistor coupled to each battery cell in a battery module composed of at least one battery cell; and at least one diode configured to cell-balance a voltage of the battery cell through the coupled discharge resistor by making a current flow in the reversal direction of the diode when the voltage of the battery cell exceeds a preset threshold voltage.

Description

[0001] APPARATUS AND METHOD FOR AUTONOMOUS BATTERY BALANCING [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autonomous battery balancing apparatus and method thereof, and more particularly, to an autonomous battery balancing apparatus and method that can autonomously perform cell balancing using a discharge resistor and a diode connected to a battery cell.

In recent years, various devices such as industrial devices, home appliances and automobiles using high-voltage batteries have appeared, and especially in the field of automobile technology, the use of high-voltage batteries is becoming more active.

Automobiles that use internal combustion engines that use fossil fuels such as gasoline or heavy oil as the main fuel have a serious impact on pollution such as air pollution. Therefore, in recent years, efforts have been made to develop an electric vehicle or a hybrid vehicle in order to reduce pollution.

Electric vehicles (EVs) are vehicles that do not use petroleum fuels and engines but that use electric batteries and electric motors. That is, an electric vehicle that drives an automobile by rotating an electric motor that is accumulated in a battery is developed prior to a gasoline automobile, but is not commercialized because of problems such as a heavy weight of the battery, a limitation of the capacity of the battery, And environmental problems became serious, research for commercialization began in the 1990s.

On the other hand, hybrid technology (HEV) that uses electric vehicles, fossil fuels and electric energy adaptively is being commercialized as battery technology has been developed remarkably. Since HEV uses gasoline and electricity together as a power source, it is evaluated positively in terms of fuel efficiency improvement and exhaust gas reduction, and it is expected to play an intermediate role in evolving into a fully electric vehicle.

Since HEV and EV vehicles using such electric energy use a battery in which a plurality of rechargeable secondary cells are packed as a main power source, there is no exhaust gas and noise is small. have.

Since the performance of a battery using the electric energy directly affects the performance of the vehicle, it is necessary to measure the voltage of each battery cell, the voltage and current of the entire battery, and to efficiently manage charge and discharge of each battery cell However, a battery management system (BMS) is required to monitor the state of a cell sensing IC that senses each battery cell, thereby enabling stable control of the corresponding cell.

1 is a block diagram schematically showing a battery management system according to the prior art.

Referring to FIG. 1, a vehicle battery management system 100 includes a battery stack 10 including a plurality of battery modules, a vehicle electronic device 20, and a battery control device 30.

The battery stack 10 includes a plurality of battery modules 11 and 12, and the battery modules 11 and 12 include a plurality of battery cells. The battery stack 10 supplies the charged high voltage direct current power to the vehicle electronic device 20 such as a motor.

The battery control device 30 may include a plurality of MCUs 31 and 32 and a BCU 33 for controlling the MCU. The battery control device 30 is connected to the battery stack to monitor the charge / discharge state of the battery stack 10, and controls the charge / discharge operation of the battery stack 10. [

As described above, in a battery management system combining a plurality of battery cells, a voltage deviation between battery cells due to a structural difference necessarily occurs. Such a voltage deviation hinders the uniformity of the battery voltage, and eventually acts as a cause of battery deterioration, thereby reducing the life of the battery.

Therefore, the battery cell balancing operation which maintains the voltage of each cell evenly during the operation of the system using the battery power or the charge / discharge of the battery cell becomes a very important element of the battery management system.

This battery cell balancing technique discharges higher cell voltages based on the voltage of the lower cell. To this end, the battery management system requires a circuit for measuring the voltage between the battery cells, a circuit for comparing the voltages of the battery cells, and a circuit for discharging the voltages of the lower cells in order to balance the battery cells.

Also, the battery management system should always monitor the battery cells, not measure or compare the voltage of each battery cell only in a specific section. Thus, the load associated with monitoring and controlling the battery management system can be increased.
Korean Unexamined Patent Publication No. 10-2013-0086362 (published on Mar. 08, 2013) discloses a conventional autonomous battery balancing technique.

Embodiments of the present invention provide an autonomous battery balancing apparatus and method that can autonomously perform cell balancing using a discharge resistor and a diode connected to a battery cell.

Embodiments of the present invention also provide an autonomous battery balancing device and method for comparing the modular voltage of a battery module including at least one battery cell with a balancing voltage of at least one diode to determine whether the cell balancing is performed I want to.

In addition, embodiments of the present invention provide an autonomous battery balancing apparatus and method that can estimate the number of battery cells in which cell balancing has occurred when cell balancing occurs in at least one battery cell.

According to the first aspect of the present invention, at least one discharging resistor connected to a battery cell in a battery module composed of at least one battery cell, And at least one discharging resistor, and when a voltage of any one of the at least one battery cell exceeds a predetermined threshold voltage, current flows in a direction opposite to the diode to connect the voltage of the battery cell to the connected An autonomous battery balancing device including at least one diode for cell balancing through discharge resistance can be provided.

The at least one diode may be a Zener diode having a breakdown voltage of the predetermined threshold voltage.

The apparatus comprises: a first voltage measuring unit connected to both the uppermost and lowermost ends of the battery module, the at least one battery cell being configured to measure a module voltage; A second voltage measuring unit connected to both the uppermost and lowermost ends of the at least one diode to measure a balancing voltage; A storage unit for storing the measured module voltage and the balancing voltage, respectively; And a controller for comparing the module voltage with the balancing voltage to determine whether cell balancing occurs in the at least one battery cell.

The controller may calculate a voltage difference between the module voltage and the balancing voltage when cell balancing occurs in the at least one battery cell to estimate the number of battery cells in which the cell balancing occurred in the at least one battery cell .

Wherein the controller calculates a voltage difference between the module voltage and the balancing voltage and estimates the number of battery cells in which cell balancing has occurred in the at least one battery cell using the calculated voltage difference and the voltage drop of the predetermined discharge resistance can do.

The controller may estimate the number of battery cells that are not adjacent to each other in which cell balancing occurs in the at least one battery cell using the calculated voltage difference and the voltage drop of the predetermined discharge resistance.

The controller may inform the balancing abnormal state when the estimated number of battery cells exceeds the threshold number.

According to a second aspect of the present invention, there is provided an autonomous battery balancing method in an autonomous battery balancing apparatus including at least one discharge resistor and at least one diode connected to a battery cell in a battery module including at least one battery cell, If a voltage of any one of the at least one battery cell exceeds a predetermined threshold voltage, a current flows in a direction opposite to the diode to perform cell balancing of the voltage of the battery cell through the connected discharge resistor; Measuring a module voltage across the battery module comprising the at least one battery cell; Measuring a balancing voltage across the at least one diode; And comparing the module voltage with the balancing voltage to determine whether cell balancing occurs in the at least one battery cell.

The at least one diode may be a zener diode having a breakdown voltage of the predetermined threshold voltage.

The method may further include estimating the number of battery cells in which cell balancing has occurred in the at least one battery cell by calculating a voltage difference between the module voltage and the balancing voltage when cell balancing occurs in the at least one battery cell As shown in FIG.

The step of estimating the number of battery cells may estimate the number of battery cells in which cell balancing has occurred in the at least one battery cell using the calculated voltage difference and the voltage drop of one predetermined discharge resistor.

The step of estimating the number of battery cells may estimate the number of non-adjacent battery cells in which cell balancing occurs in the at least one battery cell using the calculated voltage difference and the voltage drop of the predetermined discharge resistance .

The method may further include notifying a balancing abnormal state when the estimated number of battery cells exceeds a threshold number.

Embodiments of the present disclosure are capable of autonomously cell balancing using discharge resistances and diodes coupled to battery cells.

In addition, the embodiments of the present invention can confirm cell balancing by comparing a module voltage of a battery module including at least one battery cell with a balancing voltage across at least one diode.

In addition, embodiments of the present invention can estimate the number of battery cells in which cell balancing has occurred when cell balancing occurs in at least one battery cell.

1 is a block diagram schematically showing a battery management system according to the prior art.
2 is a configuration diagram of an autonomous battery balancing apparatus according to an embodiment of the present invention.
3 is an explanatory view of a cell balancing operation in an autonomous battery balancing apparatus according to an embodiment of the present invention.
4 is a flowchart of an autonomous battery balancing method according to an embodiment of the present invention.

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

In describing the embodiments, descriptions of techniques which are well known in the technical field to which this specification belongs and which are not directly related to this specification are not described. This is for the sake of clarity without omitting the unnecessary explanation and without giving the gist of the present invention.

For the same reason, some of the components in the drawings are exaggerated, omitted, or schematically illustrated. Also, the size of each component does not entirely reflect the actual size. In the drawings, the same or corresponding components are denoted by the same reference numerals.

2 is a configuration diagram of an autonomous battery balancing apparatus according to an embodiment of the present invention.

First, an autonomous battery balancing device 200 according to an embodiment of the present invention is connected to a battery module. The autonomic battery balancing device 200 is a device that balances the voltage and current of a battery with time in an application using a battery such as an electric vehicle (EV), a hybrid vehicle, and an uninterruptible power supply (UPS) Allows cell balancing autonomously in large fluctuating random systems.

2, an autonomous battery balancing apparatus 200 according to an embodiment of the present invention includes first to eighth discharge resistors R1 to R8, first to eighth diodes D1 to D8, 1 voltage measuring unit 210, a second voltage measuring unit 220, a controller 230, and a storage unit 240.

The specific configuration and operation of each component of the autonomous battery balancing apparatus 200 of FIG. 2 will be described below. In order to describe one embodiment of the present invention, a description will be made with reference to a battery module composed of eight battery cells (V1 to V8) and a structure in which a discharge resistor and a diode are connected to each battery cell. Here, the present invention is not limited to a battery module composed of a specific number of battery cells. In addition, the same autonomous balancing device can be applied to a battery pack composed of at least one battery module other than the battery module.

Here, the battery pack is a battery pack that outputs a higher voltage than a low voltage battery of a general vehicle. The high-voltage battery can be used for a hybrid vehicle or an electric vehicle as driving means for traveling through an engine and a motor. At both ends of such a battery pack, a motor may be connected as a load as required, or alternators may be connected as a charger if necessary.

The discharge resistance is connected to the first to eighth battery cells V1 to V8, which are eight battery cells. Here, the battery cell is included in at least one battery cell, that is, a battery module composed of eight battery cells. Discharge resistance may be further connected to the lowermost end of the battery cell, that is, the eighth battery cell V8.

The diode is composed of eight diodes, and is connected to the first to eighth discharge resistors R1 to R8, respectively. When a voltage of any one of the first to eighth battery cells V1 to V8 exceeds a preset threshold voltage in the connection structure of the diode and the discharge resistor, current flows in the reverse direction of the diode. The diode then autonomously performs cell balancing through the discharge resistor connected to the diode to the voltage of the battery cell.

For this autonomous battery balancing, the first to eighth diodes D1 to D8 may be zener diodes having a breakdown voltage of a predetermined threshold voltage. Here, the threshold voltage may be preset to a voltage at which the battery cell is overcharged and can be judged as an overvoltage. At this time, even if an overvoltage occurs in the battery cell, the diode may be turned on autonomously so that the overvoltage in the battery cell can be discharged or balanced through the corresponding discharge resistor. This discharging operation is not limited to a specific battery cell, and when any battery cell exceeds an predetermined threshold voltage and becomes an overvoltage, the diode is turned on due to its overvoltage so that the bal balancing is performed.

A process of estimating the number of battery cells in which cell balancing has occurred will be described.

The first voltage measuring unit 210 is connected to the uppermost and lowermost ends of the battery module including the first through eighth battery cells V1 through V8. That is, the first voltage measuring unit 210 is connected to the first battery cell V1 and the eighth battery cell V8. The first voltage measuring unit 210 is connected to both ends of the battery module and measures the module voltage plus the voltages of the first to eighth battery cells V1 to V8.

The second voltage measuring unit 220 is connected to the uppermost and lowermost ends of the first to eighth diodes D1 to D8. The second voltage measuring unit 220 measures the balancing voltage across the entire diode plus the top and bottom lines of the diode, i.e., the voltage of the whole diode.

The controller 230 is connected to the first voltage measuring unit 210 and the second voltage measuring unit 220. The controller 230 compares the measured voltage and the balancing voltage of the first voltage measuring unit 210 and the second voltage measuring unit 220, respectively. Then, the controller 230 can check whether cell balancing occurs in the first to eighth battery cells V1 to V8 using the result of the voltage comparison.

The storage unit 240 stores the measured module voltages and balancing voltages measured by the first voltage measurement unit 210 and the second voltage measurement unit 220, respectively. The control unit 230 receives the stored module voltage and the balancing voltage from the storage unit 240 and can later check whether cell balancing occurs. In addition, the storage unit 240 may further store a result of checking whether cell balancing occurs and the number of battery cells where cell balancing has occurred.

When the cell balancing occurs in the first to eighth battery cells V1 to V8, the controller 230 calculates the voltage difference between the module voltage and the balancing voltage to calculate the voltage difference between the first to eighth battery cells V1 to V8, The number of battery cells in which balancing has occurred can be estimated.

The controller 230 calculates a voltage difference between the measured voltage and the balanced voltage measured by the first voltage measuring unit 210 and the second voltage measuring unit 220, It is possible to estimate the number of battery cells in which cell balancing has occurred in the first to eighth battery cells V1 to V8. In addition, the controller 230 estimates the number of non-adjacent battery cells in which the cell balancing occurred in the first to eighth battery cells V1 to V8, using the calculated voltage difference and the voltage drop of the predetermined discharge resistance .

Thereafter, when the number of estimated battery cells exceeds a preset threshold number, the control unit 230 can notify the user of the balancing abnormal state through the instrument panel of the vehicle or the electronic device of the vehicle. Cell balancing can be performed without special cell balancing instructions due to failure of cell balancing. In addition, due to the discharge resistance in which cell balancing is performed due to overcharging of the battery cell, the temperature of the battery cell may increase, and the battery cell or the battery management system may be damaged. Accordingly, the controller 230 can inform the user of the state of the cell balancing.

Meanwhile, the first voltage measuring unit 210 may repeatedly measure the voltage of the module caught at both ends of the battery module. Also, the second voltage measurement unit 220 can repeatedly measure the module voltage at both ends of the uppermost and lowermost diodes.

When the cell balancing occurs in the first to eighth battery cells V1 to V8, the controller 230 calculates the voltage difference between the module voltage and the balancing voltage and outputs the voltage difference between the first to eighth battery cells V1 to V8, The number of battery cells in which cell balancing has occurred can be estimated repeatedly. It is possible to more accurately measure the number of battery cells by averaging the number of battery cells repeatedly estimated.

Alternatively, the first voltage measuring unit 210 may be connected to the battery module via a first switching circuit (not shown) connected to the first through eighth battery cells V1 through V8. Here, the first voltage measuring unit 210 measures the voltage of each battery cell, not the voltage of the entire battery module, through the first switching circuit, and calculates the module voltage of the battery module by summing the voltages of the measured battery cells can do.

The second voltage measuring unit 220 may be connected to the battery module through a second switching circuit (not shown) connected to the first to eighth diodes D1 to D8. Here, the second voltage measuring unit 220 measures the voltage of each diode, not the voltage across the entire diode through the second switching circuit, and measures the balancing voltage across the entire diode by summing the voltages of the measured diodes .

The control unit 230 compares the measured voltage of the module and the balancing voltage measured by the first voltage measuring unit 210 and the second voltage measuring unit 220, Can be confirmed. Here, the module voltage and the balancing voltage represent the voltages at which the voltages of the battery cell and the diode are respectively added.

Then, the controller 230 estimates the number of battery cells in which the cell balancing has occurred in the first to eighth battery cells V1 to V8 using the voltage difference between the voltage of the battery cell and the voltage of the diode corresponding to the battery cell can do. In addition, the controller 230 can estimate the number of battery cells in which the cell balancing occurred in the first to eighth battery cells V1 to V8 using the calculated voltage difference and the voltage drop of the predetermined discharge resistance.

3 is an explanatory view of a cell balancing operation in an autonomous battery balancing apparatus according to an embodiment of the present invention.

The operation of the autonomous battery balancing apparatus 200 will be described in the case where overvoltage or cell balancing occurs in the first to eighth battery cells V1 to V8.

For example, it is assumed that the second battery cell V2 and the fourth battery cell V4 in the first through eighth battery cells V1 through V8 are over-voltage.

When the second battery cell V2 and the fourth battery cell V4 exceed the preset threshold voltage and become overvoltage, the second diode D2 corresponding to the second battery cell V2 and the fourth battery cell V4 And the fourth diode D4 are turned on. Then, current flows in the direction opposite to the second diode D2 and the fourth diode D4. The overcurrent of the second battery cell V2 and the fourth battery cell V4 is cell balanced through the second discharge resistor and the fourth discharge resistor.

At this time, the first voltage measuring unit 210 may measure the module voltage of the entire battery module as a sum of voltages of the first to eighth battery cells.

In addition, the second diode D2 and the fourth diode D4 are turned on in the entire diode so that no voltage is applied. The second voltage measurement unit 220 may measure the voltage across the remaining diodes except for the second diode D2 and the fourth diode D4 as a balancing voltage.

Specifically, when cell balancing is performed in the second battery cell V2 and the fourth battery cell V4, a voltage drop occurs in the second resistor and the fourth resistor. Therefore, the second voltage measuring unit 220 can measure a voltage obtained by subtracting the voltage drop due to the second resistor and the fourth resistor from the voltage across the entire diode, as a balancing voltage. Here, the voltage drop can be preset to a voltage drop in accordance with the resistance value of the discharge resistor.

Then, the controller 230 calculates the voltage difference between the module voltage and the balancing voltage, compares the calculated voltage difference with the voltage drop of the second discharge resistor and the fourth discharge resistor, and if the voltage difference is equal to the voltage difference, It is possible to estimate the number of battery cells in which balancing has occurred to be two. Here, a pre-offset according to the voltage comparison between the voltage difference and the voltage drop can be set.

4 is a flowchart of an autonomous battery balancing method according to an embodiment of the present invention.

The autonomic battery balancing method shown in FIG. 4 includes first to eighth discharge resistors R 1 to R 8 and first to eighth discharge resistors R 1 to R 8 connected to a battery cell in a battery module composed of first to eighth battery cells V 1 to V 8, And may be applied to an autonomous battery balancing apparatus 200 including diodes D1 to D8.

First, when the voltage of any one of the battery modules, that is, the first to eighth battery cells V1 to V8, exceeds a preset threshold voltage, current flows in the reverse direction of the diode. Then, the cell balancing is performed through the discharging resistor in which the voltage of the battery cell is connected to the battery cell.

Thereafter, the first voltage measuring unit 210 is connected to the uppermost and lowermost ends of the battery module to measure a module voltage of the battery module (S402).

Then, the storage unit 240 stores the measured module voltage at the first voltage measurement unit 210 (S404).

Meanwhile, the second voltage measuring unit 220 measures the balancing voltages at the uppermost and lowermost ends of the entire Zener diodes (S406).

Then, the storage unit 240 stores the measured balancing voltage at the second voltage measuring unit 220 (S408).

The controller 230 checks whether the measured voltage values of the first voltage measuring unit 210 and the second voltage measuring unit 220 are equal to each other (S410).

If the measured module voltages and balancing voltages are equal to each other, the controller 230 determines that no cell balancing or overvoltage occurs in the first to eighth battery cells V1 to V8 S412).

On the other hand, if it is determined in step S410 that the measured module voltages and balancing voltages are not equal to each other, the controller 230 determines that cell balancing or overvoltage has occurred in the first to eighth battery cells V1 to V8 (S414).

Then, the controller 230 calculates the voltage difference between the measured module voltage and the balanced voltage (S416).

The controller 230 may estimate the number of battery cells in which overvoltage or cell balancing has occurred based on the calculated voltage difference (S418). At this time, the controller 230 can accurately estimate the number of battery cells in which the cell balancing has occurred in the first to eighth battery cells V1 to V8 using the calculated voltage difference and the predetermined voltage drop of the one discharge resistor have.

It will be understood by those skilled in the art that the present specification may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments set forth in the claims are illustrative in all aspects and not restrictive. The scope of the present specification is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present specification Should be interpreted.

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 embodiments, but, on the contrary, It is not intended to limit the scope of the specification. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: Battery Management System (BMS)
10: Battery pack
11, 12, 13: Battery module
20: vehicle electronic device
30: Battery control device
31, 32: MCU
33: BCU
200: Autonomous battery balancing device
210: first voltage measuring unit
220: second voltage measuring unit
230:
240:
V1 to V8: First to eighth battery cells
R1 to R8: First to eighth discharging resistances
D1 to D8: First to eighth diodes

Claims (13)

At least one discharging resistor connected to the battery cell in a battery module consisting of at least one battery cell;
And a control unit connected to the at least one discharging resistor, and when a voltage of any one of the at least one battery cell exceeds a predetermined threshold voltage, a current flows in a direction opposite to the diode, At least one diode for cell balancing through a resistor;
A first voltage measuring unit connected to the uppermost and lowermost ends of the battery module, the first voltage measuring unit measuring the module voltage;
A second voltage measuring unit connected to both the uppermost and lowermost ends of the at least one diode to measure a balancing voltage;
A storage unit for storing the measured module voltage and the balancing voltage, respectively; And
A controller for comparing the module voltage with the balancing voltage to determine whether cell balancing occurs in the at least one battery cell; And an automatic battery balancing device. The method according to claim 1,
The at least one diode
And a Zener diode having a breakdown voltage of the predetermined threshold voltage. delete The method according to claim 1,
The control unit
And calculates a voltage difference between the module voltage and the balancing voltage when cell balancing occurs in the at least one battery cell to estimate the number of battery cells in which cell balancing has occurred in the at least one battery cell. 5. The method of claim 4,
The control unit
An autonomous battery for estimating the number of battery cells in which cell balancing has occurred in the at least one battery cell using the calculated voltage difference and the voltage drop of the predetermined discharge resistance, Balancing device. 5. The method of claim 4,
The control unit
And estimates the number of non-adjacent battery cells in which cell balancing occurred in the at least one battery cell using the calculated voltage difference and the voltage drop of the predetermined discharge resistance. 5. The method of claim 4,
The control unit
And notifies the balancing abnormal state when the estimated number of battery cells exceeds the threshold number. 1. An autonomous battery balancing method in an autonomous battery balancing apparatus including at least one discharge resistor and at least one diode each connected to a battery cell in a battery module composed of at least one battery cell,
If a voltage of any one of the at least one battery cell exceeds a predetermined threshold voltage, a current flows in a direction opposite to the diode to perform cell balancing of the voltage of the battery cell through the connected discharge resistor;
Measuring a module voltage across the battery module comprising the at least one battery cell;
Measuring a balancing voltage across the at least one diode; And
Comparing the module voltage with the balancing voltage to determine whether cell balancing occurs in the at least one battery cell
Wherein the autonomous battery balancing method comprises: 9. The method of claim 8,
The at least one diode
And a Zener diode having a breakdown voltage of the predetermined threshold voltage. 9. The method of claim 8,
Estimating the number of battery cells in which cell balancing has occurred in the at least one battery cell by calculating a voltage difference between the module voltage and the balancing voltage when cell balancing occurs in the at least one battery cell;
Further comprising the steps of: 11. The method of claim 10,
The step of estimating the number of battery cells
And estimating the number of battery cells in which cell balancing has occurred in the at least one battery cell using the calculated voltage difference and the voltage drop of one predetermined discharge resistance. 11. The method of claim 10,
The step of estimating the number of battery cells
And estimating the number of non-adjacent battery cells in which cell balancing occurred in the at least one battery cell using the calculated voltage difference and the voltage drop of the predetermined discharge resistance. 11. The method of claim 10,
If the number of the estimated battery cells exceeds the threshold number, notifying the balancing abnormal state
Further comprising the steps of:

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