KR20170065322A - Apparatus and method for blancing battery - Google Patents

Abstract

The present invention relates to a battery balancing apparatus, and a battery balancing apparatus according to an embodiment of the present invention is a battery balancing apparatus for balancing a voltage of a plurality of battery cells including at least two serially connected first and second cells A first resistor connected to one side of the first cell, a second resistor connected between the first cell and the second cell, and a third resistor connected to the other side of the second cell, The second resistor, and the third resistor are connected at a common contact, and a first switch, a second switch, and a third switch are connected between the first resistor, the second resistor, and the third resistor, respectively, .

Description

[0001] APPARATUS AND METHOD FOR BLANCING BATTERY [0002]

The present invention relates to an apparatus for balancing the voltage of a battery that can be used in an apparatus using electrical energy. Specifically, the present invention relates to a technique for balancing the voltage between a plurality of battery cells of a high voltage battery used in a hybrid vehicle, a plug-in hybrid vehicle and an electric vehicle.

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 cars that do not use petroleum fuels and engines but that use electric batteries and electric motors. In other words, although an electric vehicle that drives a car by rotating an electric motor that is stored in a battery has been developed before a gasoline car, it has not been put into practical use due to problems such as a heavy weight of a battery and a time required for charging. Recently, And 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 both gasoline and electricity as power sources, it is receiving positive reviews in terms of fuel efficiency improvement and emission reduction. It is expected that HEV will play an intermediate role in evolving into a full electric vehicle because it is important to overcome the price difference with gasoline automobile by reducing the amount of secondary battery to one third of that of electric cars.

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.

Meanwhile, if any one of the plurality of cells of the battery reaches the threshold value during the charging process of the battery, the charging is stopped irrespective of the charging state of the other cells. In order to prevent such a situation, it is indispensable to discharge a specific battery cell through a cell balancing function.

Charging the battery is divided into a rapid charging method and a general charging method. The fast-charge method charges the battery at a relatively fast rate to charge 80% of the battery in about 30 minutes. In this case, the battery balancing speed is also required to be relatively high.

However, in the conventional battery balancing apparatus, only the discharging time during discharging of the battery cell can be controlled, and the amount of discharging current is fixed. Therefore, efficient battery balancing is not possible in a situation where fast battery balancing is required such as rapid charging.

U.S. Patent Application Publication No. 2014-0070772

An object of the present invention is to simplify a battery balancing circuit by performing balancing by changing only a connection state of a plurality of battery cells and a switch connected to the plurality of battery cells during voltage balancing of the plurality of battery cells.

In addition, the present invention performs balancing by changing connection states of switches connected to a plurality of battery cells when performing voltage balancing of a plurality of battery cells, thereby selectively discharging only a desired battery cell or discharging a plurality of battery cells There is a purpose.

Another object of the present invention is to adjust the magnitude of the discharge current required for balancing by performing balancing by changing connection states of switches connected to a plurality of battery cells in performing voltage balancing of a plurality of battery cells.

According to an embodiment of the present invention, a battery balancing apparatus balances a voltage of a plurality of battery cells including at least two serially connected first and second cells, the balancing apparatus comprising: A second resistor connected between the first cell and the second cell, and a third resistor connected to the other side of the second cell, wherein the first resistor, the second resistor, and the third A second switch, and a third switch are respectively provided between the first resistor, the second resistor and the third resistor, and the common contact, respectively.

The controller may further include a controller for monitoring a voltage value of each of the plurality of battery cells, determining an overcharged battery cell among the plurality of battery cells, and discharging the overcharged battery cell.

The controller determines the discharge time and the discharge current size of the overcharged battery cell and controls the first switch, the second switch, and the third switch according to the determined discharge time and discharge current magnitude, The battery cell can be discharged.

The control unit may calculate an average value of the voltage values of the plurality of battery cells and may determine that the battery cell is overcharged when the voltage value of each of the plurality of battery cells exceeds the average value.

The control unit calculates a difference value between the voltage value of the overcharged battery cell and the average value of the voltage values of the plurality of battery cells and adjusts the discharge time and the discharge current size of the overcharged battery cell in proportion to the difference value You can decide.

In addition, the controller may control whether the first switch, the second switch, and the third switch are turned on / off differently according to the determined discharge time and discharge current magnitude of the overcharged battery cell to discharge the overcharged battery cell can do.

According to an embodiment of the present invention, a battery balancing method includes: a monitoring step of monitoring a voltage value of each of a plurality of battery cells; An overcharge determination step of determining an overcharged battery cell among the plurality of battery cells as a result of monitoring in the monitoring step;

A discharging amount determining step of determining a discharging time and a discharging current size of the overcharged battery cell determined in the overcharge determining step; And a discharging step of discharging the overcharged battery cell by controlling the first switch, the second switch and the third switch in accordance with the discharge time and the discharge current size determined in the discharging amount determining step.

The overcharge determining step may calculate an average value of the voltage values of the plurality of battery cells, and may determine that the battery cell is overcharged when the voltage value of each of the plurality of battery cells exceeds the average value.

The discharging amount determining step may calculate a difference value between the voltage value of the overcharged battery cell and the average value of the voltage values of the plurality of battery cells and calculate a discharge time and discharge time of the overcharged battery cell in proportion to the difference value, The current magnitude can be determined.

Also, the discharging step may control whether the first switch, the second switch, and the third switch are turned on / off differently according to the discharge time and the discharge current magnitude of the overcharge battery cell determined in the discharging amount determining step, The overcharged battery cell can be discharged.

The present invention has the effect of simplifying the battery balancing circuit by performing balancing by changing only the connection state of the switches connected to the plurality of battery cells in performing voltage balancing of the plurality of battery cells.

The present invention also provides a method of balancing the voltage of a plurality of battery cells by changing the connection state of the plurality of battery cells and the switches connected to the plurality of battery cells, thereby selectively discharging only the desired battery cells or discharging the plurality of battery cells. There is an effect.

In addition, the present invention is capable of freely adjusting the magnitude of the discharge current required for balancing by performing balancing by changing the connection states of switches connected to a plurality of battery cells when voltage balancing of a plurality of battery cells is performed .

In addition, the present invention has the effect of increasing the battery life and controlling the calorific value according to the situation by performing balancing by adjusting not only the discharge time but also the discharge current magnitude in the voltage balancing of a plurality of battery cells.

1 is a configuration diagram of a battery balancing apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating determination of an overcharged battery cell of a battery balancing apparatus according to an embodiment of the present invention.
FIG. 3 is an explanatory view illustrating discharge of a battery cell with a general discharge current of a battery balancing apparatus according to an embodiment of the present invention. FIG.
FIG. 4 is an explanatory view showing discharge of a battery cell by a sudden discharge current of a battery balancing apparatus according to an embodiment of the present invention. FIG.
5 is a flowchart illustrating a battery balancing method of a battery balancing apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following description of the embodiments of the present invention, descriptions of techniques which are well known in the technical field of the present invention and are not directly related to the present invention will be omitted. This is for the sake of clarity of the present invention without omitting the unnecessary explanation.

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.

Hereinafter, a battery balancing apparatus according to an embodiment of the present invention will be described with reference to FIG.

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

1, a battery balancing apparatus 100 according to an embodiment of the present invention includes a plurality of resistors 21, 22, 23, 24, and 25, a plurality of switches 31, 32, 33, And a control unit 40.

A battery balancing apparatus 100 according to an embodiment of the present invention performs voltage balancing of a plurality of battery cells C1, C2, C3, C4. Preferably, the battery balancing apparatus 100 according to an embodiment of the present invention may balance the voltages of a plurality of battery cells including at least two serially connected first and second cells.

Here, the number of the battery cells, the resistors, and the switches shown in FIG. 1 are illustrative, and include more or less than the number shown in FIG.

The plurality of resistors 21, 22, 23, 24, and 25 are connected to both ends of each of the plurality of battery cells C1, C2, C3, and C4. That is, the first resistor 21 is connected to one side of the first cell C1. A second resistor 22 is connected between the first cell C1 and the second cell C2. The third resistor 23 is connected between the second cell C2 and the third cell C3. The fourth resistor 24 is connected between the third cell C3 and the fourth cell C4. The fifth resistor 25 is connected to the other side of the fourth cell. Further, the plurality of resistors 21, 22, 23, 24, and 25 are connected at a common contact point. Therefore, as shown in FIG. 1, if the number of battery cells is four, the number of resistors is five. As another example, if the number of battery cells is six, the number of resistors is seven. That is, if the number of battery cells is N, the number of resistors is N + 1.

The resistance values of the plurality of resistors 21, 22, 23, 24 and 25 are preferably equal to each other, but they can be set to approximate values within a predetermined error range.

A plurality of switches (31, 32, 33, 34, 35) are provided between the plurality of resistors (21, 22, 23, 24, 25) and the common contacts. That is, the first switch 31 is provided between the first resistor 21 and the common contact. A second switch (32) is provided between the second resistor (22) and the common contact. The third switch 33 is provided between the third resistor 23 and the common contact. A fourth switch (34) is provided between the fourth resistor (24) and the common contact. The fifth switch 35 is provided between the fifth resistor 25 and the common contact. Therefore, as shown in FIG. 1, if the number of resistors is five, the number of switches is five. As another example, if the number of resistors is seven, the number of switches is seven. That is, if the number of resistors is N, the number of switches is N. The plurality of switches 31, 32, 33, 34, and 35 are connected in series to the plurality of resistors 21, 22, 23, 24, and 25, respectively.

The plurality of switches 31, 32, 33, 34, and 35 include all elements having on / off functions. For example, an element such as a transistor may be included.

The plurality of resistors 21, 22, 23, 24 and 25 and the plurality of switches 31, 32, 33, 34 and 35 are connected to the switches 31, 32, 33, Thereby forming a passage through which the discharge current in the plurality of battery cells (C1, C2, C3, C4) can flow.

The control unit 40 monitors the voltage value of each of the plurality of battery cells C1, C2, C3, and C4.

The control unit 40 determines an overcharged battery cell among the plurality of battery cells C1, C2, C3, and C4.

FIG. 2 is an explanatory diagram illustrating determination of an overcharged battery cell of a battery balancing apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the controller 40 calculates an average value of the voltage values of the plurality of battery cells C1, C2, C3, and C4. When the voltage value of each of the plurality of battery cells C1, C2, C3, and C4 exceeds the average value, the control unit 40 determines that the battery cell C2 exceeding the average value is an overcharged battery cell.

The control unit 40 determines the discharge time and the discharge current size of the overcharged battery cell. At this time, the control unit 40 may calculate the difference between the voltage value of the overcharged battery cell and the average value, and determine the discharge time and the discharge current size of the overcharged battery cell in proportion to the difference value. That is, the controller 40 may determine that the discharge time is longer or the discharge current size is larger when the difference value is larger. For example, when the difference value is 10 mV, the discharge time is 1 second or the discharge current size is 1 mA. If the difference is 1 V, the discharge time is 15 seconds or The discharge current magnitude can be determined as 70mA. Meanwhile, the controller 40 may determine the discharge time and the discharge current size of the overcharged battery cell by other methods.

The controller (40) controls the plurality of switches (31, 32, 33, 34, 35) according to the determined discharge time and the discharge current magnitude to discharge the overcharged battery cell. At this time, the control unit 40 may control whether each of the plurality of switches 31, 32, 33, 34, and 35 is turned on / off to discharge the overcharged battery cell.

FIG. 3 is an explanatory view showing discharge of a battery cell by a general discharge current of a battery balancing apparatus according to an embodiment of the present invention. FIG.

3, the controller 40 controls the plurality of switches 31, 32, 33, 34, and 35 so that the discharge current is relatively small when the overcharged battery cell determines that a sudden discharge is not required. do. For example, a closed loop is formed such that only the voltage of the overcharged battery cell C2 is considered, as shown in Fig. That is, only the second switch 32 and the third switch 33 among the plurality of switches are turned on (short-circuited), and the remaining switches are turned off (opened). In this case, the discharge current can be expressed by i1 = C2 / (R2 + R3). At this time, R2 (22) is a resistor connected to the second switch, and R3 (23) is a resistor connected to the third switch.

FIG. 4 is an explanatory view showing discharge of a battery cell by a sudden discharge current of a battery balancing apparatus according to an embodiment of the present invention. FIG.

Referring to FIG. 4, when the overcharged battery cell determines that a sudden discharge is required, the controller 40 controls the plurality of switches 31, 32, 33, 34, and 35 so that the discharge current magnitude is relatively large . For example, as shown in Fig. 4, a closed loop is formed so that not only the overcharged battery cell C2 but also the voltages of C3 and C4 are considered. That is, only the second switch 32 and the fifth switch 35 among the plurality of switches are turned on (short-circuited), and the remaining switches are turned off (opened). In this case, the discharge current can be expressed by i2 = (C2 + C3 + C4) / (R2 + R5). At this time, R2 (22) is a resistor connected to the second switch (32), and R5 (23) is a resistor connected to the fifth switch (35).

As described above, since the resistance values of the plurality of resistors 21, 22, 23, 24, and 25 have approximate values, when the i2 value is at least three times larger than i1 Respectively. Therefore, even if a sudden discharge is required, a rapid discharge is possible.

That is, as described above, the battery balancing apparatus 100 can perform balancing by appropriately adjusting the discharging time and the discharging current size when the voltage balancing of the plurality of battery cells C1, C2, C3, and C4 is performed. Therefore, the life of the battery can be increased and the amount of heat generated can be appropriately controlled.

Hereinafter, a battery balancing method according to an embodiment of the present invention will be described with reference to FIG.

5 is a flowchart illustrating a battery balancing method of a battery balancing apparatus according to an embodiment of the present invention.

First, the control unit 40 monitors the voltage value of each of the plurality of battery cells C1, C2, C3, and C4 (S101).

Then, the control unit 40 determines the overcharged battery cell among the plurality of battery cells C1, C2, C3, and C4 (S103).

FIG. 2 is an explanatory diagram illustrating determination of an overcharged battery cell of a battery balancing apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the controller 40 calculates an average value of the voltage values of the plurality of battery cells C1, C2, C3, and C4. When the voltage value of each of the plurality of battery cells C1, C2, C3, and C4 exceeds the average value, the control unit 40 determines that the battery cell C2 exceeding the average value is an overcharged battery cell.

Then, the control unit 40 determines the discharge time and the discharge current size of the overcharged battery cell (S105). At this time, the control unit 40 may calculate the difference between the voltage value of the overcharged battery cell and the average value, and determine the discharge time and the discharge current size of the overcharged battery cell in proportion to the difference value. That is, the controller 40 may determine that the discharge time is longer or the discharge current size is larger when the difference value is larger. For example, when the difference value is 10 mV, the discharge time is 1 second or the discharge current size is 1 mA. If the difference is 1 V, the discharge time is 15 seconds or The discharge current magnitude can be determined as 70mA. Meanwhile, the controller 40 may determine the discharge time and the discharge current size of the overcharged battery cell by other methods.

Thereafter, the control unit 40 controls the plurality of switches 31, 32, 33, 34, and 35 according to the discharge time and the discharge current size determined in step S105 to discharge the overcharged battery cell (S107). At this time, the control unit 40 may control whether each of the plurality of switches 31, 32, 33, 34, and 35 is turned on / off to discharge the overcharged battery cell. This is described above with reference to FIG. 3, FIG. 4, Equation 1 and Equation 2, and will be omitted.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention 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 the equivalents thereof are included in the scope of the present invention 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, And is not intended to limit the scope of the invention. It is to be understood by 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 balancing device
C1, C2, C3, C4: Battery cell
21, 22, 23, 24,
31, 32, 33, 34, 35:
40:

Claims (10)

A battery balancing apparatus for balancing a voltage of a plurality of battery cells including at least two serially connected first and second cells,
A first resistor connected to one side of the first cell, a second resistor connected between the first cell and the second cell, and a third resistor connected to the other side of the second cell,
Wherein the first resistor, the second resistor and the third resistor are connected at a common contact, and a first switch, a second switch and a second switch are connected between each of the first resistor, the second resistor and the third resistor, And a third switch are respectively provided in the battery. The method according to claim 1,
Further comprising a controller for monitoring a voltage value of each of the plurality of battery cells, determining an overcharged battery cell among the plurality of battery cells, and discharging the overcharged battery cell. 3. The method of claim 2,
The controller determines the discharge time and the discharge current size of the overcharged battery cell and controls the first switch, the second switch and the third switch according to the determined discharge time and the discharge current magnitude, And discharging the battery. 3. The method of claim 2,
Wherein the controller calculates an average value of the voltage values of the plurality of battery cells and determines the battery cell as an overcharged battery cell when the voltage value of each of the plurality of battery cells exceeds the average value. 5. The method of claim 4,
The control unit calculates a difference value between the voltage value of the overcharged battery cell and the average value of the voltage values of the plurality of battery cells and determines the discharge time and the discharge current size of the overcharged battery cell in proportion to the difference value Wherein the battery balancing device is a battery balancing device. The method of claim 3,
The control unit controls the ON / OFF state of each of the first switch, the second switch and the third switch in accordance with the determined discharge time and the discharge current size of the overcharged battery cell to discharge the overcharged battery cell Battery balancing device. A monitoring step of monitoring a voltage value of each of the plurality of battery cells;
An overcharge determination step of determining an overcharged battery cell among the plurality of battery cells as a result of monitoring in the monitoring step;
A discharging amount determining step of determining a discharging time and a discharging current size of the overcharged battery cell determined in the overcharge determining step; And
And discharging the overcharged battery cells by controlling the first switch, the second switch, and the third switch according to the discharge time and the discharge current size determined in the discharge amount determination step. 8. The method of claim 7,
Wherein the overcharge determination step calculates an average value of the voltage values of the plurality of battery cells and determines that the battery cell is overcharged when the voltage value of each of the plurality of battery cells exceeds the average value. 9. The method of claim 8,
Wherein the discharging amount determining step calculates a difference value between a voltage value of the overcharged battery cell and an average value of the voltage values of the plurality of battery cells and determines a discharge time and a discharge current size of the overcharged battery cell in proportion to the difference value, And determining the battery balancing method. 8. The method of claim 7,
The discharging step may control whether the first switch, the second switch, and the third switch are turned on / off differently according to the discharge time and the discharge current magnitude of the overcharge battery cell determined in the discharging amount determining step, And discharging the battery cell.

Images