KR101482147B1 - Balencing controller for battery management systme - Google Patents

Abstract

Disclosed is a balance control device for a battery management system, capable of: minimizing cell efficiency degradation in a minimum voltage follow-up manner of adjusting peripheral cells according to properties of a lowest cell by adjusting cell balance using a mean value for output voltages of multiple cells, and shortcomings of ignoring conditions of the peripheral cells; minimizing energy waste in a maximum voltage follow-up manner of adjusting cell balance by discharging a cell having the highest voltage; and identifying a location relationship in a battery pack by giving each cell a channel number to individually monitor each cell.

Description

[0001] Balancing controller for battery management system [0001]

[0001] The present invention relates to an equalizing control apparatus, and more particularly, to an equalizing control apparatus that performs equalization control for matching a cell balance of a neighboring cell by following an average value of each cell constituting a battery pack, To an even control apparatus for a battery management system.

Generally, a battery pack is a battery in which a voltage of a cell-unit battery is directly connected to form a high voltage and is used as an energy storage system (ESS), an uninterruptible power supply (UPS), an electric vehicle battery and a portable power tool battery .

These battery packs can increase the output voltage by connecting the secondary battery cells that can be charged and discharged in series, or increase the current supply amount by connecting them in parallel, or by connecting them in series and parallel, .

Here, when a battery pack is constructed by connecting cells in series, a voltage imbalance state may occur between cells constituting the battery pack.

When the cell is charged, the cell connected to the cathode is charged first. When the neighboring cell is charged, the charged cell becomes overcharged, while the neighboring other cell is charged to a low level. There is a difference in charging state.

Due to this difference, the output voltage of the entire battery pack may be lowered due to a low discharge among the cells connected in series, or the output voltage of the overdischarged cell may be rapidly decreased to lower the output voltage of the entire battery pack. Overcharging and overdischarging of a cell can shorten the life expectancy of the entire battery pack or shorten the power supply duration of the battery pack.

As a proposed cell control method for this problem, there are a minimum voltage follow-up method and a maximum voltage follow-up method.

The lowest voltage tracking method is a method for uniformly controlling each cell by adjusting the voltage of another cell based on the voltage of the cell having the lowest output voltage among the output voltages of the cells constituting the battery pack,

As the number of battery cells increases, the voltage of the other cells must be decreased according to the cell having the lowest voltage, so that unnecessary energy consumption becomes excessive.

In addition, the lowest voltage tracking method has a disadvantage in that the voltage of a cell having a good characteristic is down based on a voltage of a cell having a poor characteristic, and therefore, the characteristic of the battery pack as a whole is adjusted to the worst cell.

As compared with the lowest voltage follow-up method, there is a highest voltage follow-up method. In the peak voltage follow-up method, the output voltage of the cell having the highest output voltage among the cells constituting the battery pack is lowered, do.

Compared with the lowest voltage tracking method, the maximum voltage tracking method has an advantage of less energy wastage. However, the voltage difference between each cell is larger than that of the lowest voltage tracking method in which the characteristics of each cell are matched to the cell outputting the lowest voltage have.

In addition, since the cells outputting the maximum voltage are controlled to be discharged by switching control in units of cells, the time required for battery control tends to be increased as compared with the lowest voltage follow-up method.

That is, in the case of the lowest voltage tracking method, the effect of preventing the cell having the lowest output voltage from being overdischarged is most remarkable. In the long term, it is possible to reduce the life span due to the deterioration of the battery pack due to the specific cell. The consumption of one charge / discharge cycle is lower than that of the other passive equilibrium control. On the other hand, in the case of the peak voltage estimation method, since it is a method of uniformly controlling by single battery cell switching, it takes longer time to complete the uniform control than in the case of the lowest voltage follow-up method. However, The big disadvantage is.

On the other hand, Japanese Patent Laid-Open No. 10-0680854 proposes a charge / discharge device having a cell balancing function for simulating load characteristics of each cell constituting a battery pack and performing cell balancing for each cell according to the result. However, in the cell balancing method described in the Japanese Patent Application No. 10-0680854, load characteristics for each cell must be grasped for the load characteristics of each cell. This is because the cell balancing method is more preferable than the maximum voltage follow- Can take more time.

SUMMARY OF THE INVENTION It is an object of the present invention to minimize the energy consumption in cell balancing, to minimize the time consumed for cell balancing, to follow the control of a specific cell to follow a number of cell characteristics, The battery management system comprising: a battery management system for controlling the battery;

According to an aspect of the present invention, there is provided an AD (Analog to Digital) conversion unit for measuring and converting a voltage of each cell of a battery pack constituted by arraying at least one cell, And an average value of the output voltage of each cell is calculated and a discharge control is performed on excess cells exceeding the average value among the cells using the discharge array to thereby balance the cell balance with respect to each cell The equalization control unit calculates an average value of the voltage of each cell, assigns a channel number to each cell, aligns the cell to which the channel number is assigned according to the size of the voltage, And an equalizing control device for a battery management system for monitoring position information occupied by the battery pack by each cell constituting the pack.

According to the present invention, by adjusting the cell balance using the average value of the output voltages of a plurality of cells, it is possible to reduce the cell efficiency of the cell balance method of the lowest voltage follow- Minimizing the disadvantage of neglecting the condition, discharging the cell with the highest voltage, minimizing the energy wastage of the maximum voltage follow-up method that adjusts the cell balance, assigning the channel number to each cell, Each cell can be monitored individually.

1 shows a block diagram of a uniform control apparatus for a battery management system according to an embodiment of the present invention.
Fig. 2 shows a reference drawing for explaining the manner of operation of the discharge array shown in Fig.
3 shows a flowchart of an equalization control method for a battery management system according to an embodiment of the present invention.
FIG. 4 is a graph showing an experimental result of a passive equalization control apparatus using an alignment technique for a battery management system according to the present invention.
FIG. 5 shows an experimental graph according to the highest voltage tracking method by passive uniformity control for a conventional battery management system.
FIG. 6 shows an experimental graph of the lowest voltage tracking scheme by passive uniformity control for a conventional battery management system.

The cell referred to in the present specification is composed of a secondary battery, and may mean a battery unit connected in series to increase the output voltage of the secondary battery.

The battery pack referred to in this specification may mean a battery cell connector in which a plurality of cells are connected in series and output a high voltage.

The cell balancing referred to herein may mean "equalization" to the output voltage of each cell constituting the battery pack. Thus, the uniformity control referred to herein may mean control for cell balancing for each cell.

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

FIG. 1 is a block diagram of a uniform control apparatus for a battery management system according to an embodiment of the present invention, and FIG. 2 is a reference diagram for explaining a method of operating the discharge array shown in FIG.

1 and 2, the equalizing control apparatus for a battery management system according to the embodiment includes positive (+) terminals and negative (-) terminals of each of the cells C1 to Cn constituting the battery pack C, ), An A / D (analog to digital) converter 120, and an even-numbered control unit 130. [

The discharge array 110 is composed of a plurality of discharge units 110a to 110n and the discharge units 110a to 110n are connected between the positive terminal and the negative terminal of each of the cells C1 to Cn do. Each of the discharge units 110a to 110n includes resistors 111a to 111n sequentially connected between positive (+) terminals of the cells C1 to Cn and a switching element, and the switching elements 112a To 112n are controlled on and off by the uniformity controller 130. [

For example, when the discharging unit 110a is switched on by the equalizing control unit 130 and the remaining discharging units 110b to 110n are switched to the switch-off state, the cell C1, the resistor 111a, The current in the cell C1 may be consumed in the resistor 111a and the voltage may be lowered. The remaining cells (C2 to Cn) are also consumed by the resistors (111b to 111n) provided in the discharge units (110b to 110n) in the same manner, so that the voltage can be lowered. The discharge array 110 according to the embodiment can selectively turn on only the desired cells C1 to Cn by switching on and off for each cell C1 to Cn.

The A / D converter 120 is connected to the positive terminals of the cells C1 to Cn to obtain analog voltage values of the cells C1 to Cn and converts the analog voltage values into digital values, to provide. FIG. 1 illustrates that the AD converter 120 is provided for each of the cells C1 to Cn. However, the A / D converter 120 may be implemented using a single integrated chip. In this case, the A / D converter 120 may be implemented as a single chip that receives voltages output from the positive terminals of the cells C1 to Cn. . On the other hand, the A / D converter 120 may be embedded in the uniform controller 130. However, it is not limited.

The equalization control unit 130 grasps the output voltages of the cells C1 to Cn through the AD conversion unit 120 and calculates the average value of the output voltages of the cells C1 to Cn.

The equalizer 130 may assign a channel number to each of the cells C1 to Cn using the calculated average value. The channel number is allocated to each cell C1 to Cn that is not identified from the outside of the battery pack, And the cells C1 to Cn can be managed by the identification codes of the cells C1 to Cn. Accordingly, when managing the battery pack, it is possible to know whether the state of any of the cells (C1 to Cn) is poor or not, and when replacing the cell in the battery pack, It can be easily recognized.

In this embodiment, the channel number can be given in the order in which the cells C1 to Cn are arranged in the battery pack. For example, when the battery pack is composed of 10 cells, the channel number can be assigned to the channel 1, the channel 2, the channel 3, the channel 10, and so on. The channel number may be determined according to the order of the AD converters 120a to 120n connected to the equalization controller 130. [ In FIG. 1, reference numeral 120a corresponds to channel 1, reference numeral 120b corresponds to channel 2, and reference numeral 120c corresponds to channel 3. Therefore, the equalization control unit 130 does not need to separately assign the channel numbers to the cells C1 to Cn, and assigns the channel numbers to the cells C1 to Cn in the order in which the AD converters 120a to 120n are arranged Which corresponds to the order in which each cell C1 to Cn is connected in the battery pack.

The equalization controller 130 may match the output voltages of the cells C1 to Cn to the channel numbers assigned to the cells C1 to Cn and store the same in the memory 135. [

Then, the equalization controller 130 may rank the channel numbers by using the output voltages corresponding to the channel numbers. Alignment of the channel numbers can be arranged in the order of higher output voltage or lower order.

The uniformity controller 130 may include a voltage measuring unit 131, an average value calculator 132, an aligner 133, and a discharge controller 134.

The voltage measuring unit 131 compares the digital output voltages of the cells C1 to Cn through the AD conversion unit 120 and outputs the digital output voltages to the AD converter 120a to 120n, .

The sorting unit 133 may sort the channel numbers according to the order of the maximum voltage or the minimum voltage in consideration of the output voltages of the cells C1 to Cn to which the channel numbers are assigned. For example, assuming that the cells C1 to Cn are lithium-ion batteries and are composed of six cells and the output voltages of the cells C1 to C6 are as follows, the equalization controller 130 associates the output voltages of the respective channels as follows, (135).

When the output voltage of the cell C1 is 3.3V-channel 1

When the output voltage of the cell C2 is 3.6V-channel 2

When the output voltage of the cell C3 is 3.8 V - channel 3

When the output voltage of the cell C4 is 4.1V-channel 4

When the output voltage of the cell C5 is 3.7V-channel 5

When the output voltage of the cell C6 is 3.7V-channel 6

Thereafter, the equalization controller 130 may rank each channel number in the order of a high voltage (or a low voltage), and sequentially sort the cells C1 to C6 as follows.

When the output voltage of the cell C4 is 4.1V-channel 4

When the output voltage of the cell C3 is 3.8 V - channel 3

When the output voltage of the cell C5 is 3.7V-channel 5

When the output voltage of the cell C6 is 3.7V-channel 6

When the output voltage of the cell C2 is 3.6V-channel 2

When the output voltage of the cell C1 is 3.3V-channel 1

Next, the average value calculating unit 132 calculates an average value of the output voltages of the cells (C1 to C6), and the calculated average value is 3.7 V (222/6 cells) C1 to C6 can be calculated as 3.7v.

When the voltage and the average value for each channel number (channel 1 to channel 6) are calculated, the discharge controller 134 determines at least one of the cells (C1 to C6) requiring discharge control, 112n are switched on or switched off so that the output voltages of the cells C1 to C6 follow the average value (3.7 V). At this time, the discharge control unit 134 may set the cells C3 and C4 outputting a voltage higher than the average value as a discharge control target.

Therefore, only the two cells C3 and C4 among the six cells C1 to C6 constituting the battery pack are discharged to the average value (3.7 V) through the discharge control and the remaining cells (C1 C2 , C5, and C6). if,

Assuming that the discharge control is performed according to the conventional lowest voltage follow-up scheme, all of the remaining cells (C2 to C6) except for the cell (C1) must be subject to discharge control, The equalization controller 130 according to the embodiment performs the discharge control only on the two cells C3 and C4, so that the energy loss is small.

On the other hand, assuming that discharge control is performed in accordance with the conventional maximum voltage follow-up scheme,

The voltage of the cell C4 must be lowered from 4.1 V to 3.3 V because the voltage of 4.1 V of the cell C4 must be discharged in accordance with the voltage of 3.3 V of the cell C1, It is necessary to discharge until 4.1V at 3.3V, so a long discharge time is required.

Meanwhile, the equalization controller 130 according to the embodiment only reduces the voltage of the cell C3 by -0.1 V, and the voltage of the cell C4 having the largest difference between the output voltage and the average value is 0.5 V (4.1 V - 3.7 V) It is possible to reduce the energy loss and the time required for the discharge control as compared with the maximum voltage follow-up method. That is, the equalization controller 130 according to the embodiment overcomes the disadvantages of the conventional lowest voltage follow-up scheme and the maximum voltage follow-up scheme with high energy consumption.

The discharge control unit 134 refers to the average value calculated by the average value calculation unit 132 and the output voltages of the cells C1 to Cn determined by the voltage detection unit 131 and outputs the voltages exceeding the average value, Cn). The discharge control unit 134 can lower the voltages of the cells C1 to Cn by switching on and off the discharge units 110a to 110n provided in the discharge array 110. [ The discharge control method will be described with reference to Fig.

2, the equalization controller 130 applies a control signal CTRL1 to the switching element 112a to switch on the switching element 112a. When the switching element 112a is switched on, The capacitor C1, the resistor 111a, and the switching element 112a are electrically energized to form a current path. When the current path is formed, the current in the cell C1 is consumed through the resistor 111a, and the output voltage of the cell C1 is lowered as much as it is consumed through the resistor 111a.

At this time, the control signal CTLR1 provided from the discharge controller 134 to the switching element 112a may be a pulse or direct current (DC) type signal. When the control signal CTRL1 is of the pulse type, the switching element 112a consumes the current of the cell C1 in the resistor 111a while repeating the switching-on and switching-off intermittently. In the case of the DC type, The current of the cell C1 can be consumed through the AD converter 120 until the target voltage (for example, 3.7 V) is reached. Here, the switching element 112b provided in the cell C2 maintains the switching-off state so as not to be connected to the current path of the cell C1.

3 shows a flowchart of an equalization control method for a battery management system according to an embodiment of the present invention. Referring to FIGS. 1 and 2 together,

First, the AD converter 120 measures an output voltage of each of the cells C1 to Cn constituting the battery pack (S301), and the equalizer controller 130 calculates the output voltage of each of the cells C1 to Cn (S302). ≪ / RTI > Next, the equalization control unit 130 assigns channel numbers to the cells C1 to Cn according to the measurement positions of the AD converters 120a to 120n, records them in the memory 135 in association with the channel numbers and the output voltages, (S303).

Next, the aligner 133 aligns the output voltages of the cells C1 to Cn in accordance with the channel number recorded in the memory 135 (S304), and arranges the output voltages of the respective channel numbers according to the output voltage magnitudes (S305).

At this time, the alignment unit 133 can generate a rank area in the memory 135 by the number of channels. If the cell to which the channel number is assigned up to 6 constitutes the battery pack, the aligning unit 133 may generate six rank regions in the memory equal to the number of channel numbers.

Next, the aligner 133 compares the channel numbers and output voltages of the stored cells C1 to Cn with respect to the positions of the channels according to the channel order to determine the order of the output voltages.

For example, assuming that the cells C1 to Cn constitute a battery pack, and the channels for each cell are CH1 to CHn,

The alignment unit 133 compares the output voltages of CH1 and CH2 to determine which output voltage of the channel is higher. As a result of the determination, if CH2 > CH1, the rank can be set in the order of CH2 - CH1. Next, the aligner 133 compares the output voltage of CH3 with CH1 to determine the position of CH3, and then aligns CH1, CH2 and CH3. Next, the aligner 133 adjusts the output voltage of CH4 to CH1 to CH4 The rank of CH4 can be set.

The aligner 133 may derive the lowest (or highest) rank by referring to the output voltages of the channels CH1 to CH4 and set this process to one cycle. Next, the sorting unit 133 repeatedly applies the same method to the remaining channels except for the lowest (or highest) rank, and performs re-sorting on the remaining three channels to obtain the lowest (or the highest ) Rank can be judged.

The sorting unit 133 sets the second sorting process to the second cycle, and in the third cycle, the remaining two channels are sorted again to set the rank. Setting the rank for the remaining two channels through the third sort completes the rank setting for all channels.

For example, when it is assumed that the output voltages of the channels CH1 to CH4 are CH3> CH1> CH4> CH2 and that the output voltages are arranged in descending order in the order of decreasing output voltage,

(1) First cycle:

1. Assignment of CH1, CH2, CH3, and CH4 to the rank (RANK) according to the connected AD converter (e.g., 120a to 120n in Fig.

RANK1 = CH1, RANK2 = CH2, RANK3 = CH3, RANK4 = CH4

2. It compares in order according to rank order of each channel.

2-1) Comparison between RANK1 and RANK2

   RANK1 = CH1> RANK2 = CH2 RANK1 = CH1, RANK2 = CH2

2-2) Comparison between RANK2 and RANK3

   RANK2 = CH2 < RANK3 = CH3 RANK2 = CH3, RANK3 = CH2

2-3) Comparison between RANK3 and RANK4

   RANK3 = CH2 < RANK4 = CH4 RANK3 = CH4, RANK4 = CH2

3. Therefore, the channel (CH2) is arranged in the lowest rank RANK4. The lowest rank, RANK4, is excluded in the next cycle.

(2) Second cycle:

4). RANK4 = CH1, RANK2 = CH3, and RANK3 = CH4 are compared in order, except for the lowest rank RANK4

4-1) Comparison between RANK1 and RANK2

   RANK1 = CH1 < RANK2 = CH3 RANK1 = CH3, RANK2 = CH1

4-2) Comparison between RANK2 and RANK3

   RANK2 = CH1> RANK3 = CH4 RANK2 = CH1, RANK3 = CH4

5. RANK3, which is the lowest rank in the current cycle, is excluded in the next cycle like RANK4.

6. Third cycle:

6-1) RANK4 which is the lowest rank and RANK3 which is the lowest rank in the previous cycle are excluded and RANK1 = CH3 and RANK2 = CH1 are compared

6-2) Comparison between RANK1 and RANK2

   RANK1 = CH3> RANK2 = CH1 RANK1 = CH3, RANK2 = CH1

6-3) This completes the rank setting, and the completed result is as follows.

   RANK1 = CH3, RANK2 = CH1, RANK3 = CH4, RANK4 = CH2

Therefore, when the number of channels is N, the arranging unit 133 can determine the rank of each channel with N-1 comparison cycles and arrange and record the rank in the rank area set in the memory 135 (S305).

Next, the alignment unit 133 determines whether the output voltage comparison for all the channels is completed (S307). As a result of the determination, if the comparison of the output voltages of all the channels is not completed, the process proceeds to step S305. If the comparison of the output voltages is completed, any one of the cells C1 to Cn of the highest output voltage , And records it in the memory 135 (S308).

Finally, the discharge control unit 134 performs discharge control for the cell of the channel ranked with the highest output voltage among the channels ranked in the memory 135, at which time the cell of the channel ranked with the highest output voltage The discharge control can be performed until the output voltage becomes equal to the average value (S309).

On the other hand, when the sorting unit 133 arranges channels in the highest voltage order, the sorting unit 133 can sort the channel numbers in the order of the channel having the higher output voltage and the channel having the lower output voltage. In this case, it is possible to determine that the cell (C1 to Cn) of the channel arranged in the lowest order in the sorting unit 133 is the oldest cell, and when the battery pack is managed, (At least one of the replacement target cells C1 to Cn) through the network. Likewise, when the sorting order of the aligning unit 133 is the lowest voltage order, the cells with the most deteriorated characteristics can be displayed at the highest rank.

FIG. 4 is a graph showing an experimental result of a passive equalization control apparatus using an alignment technique for a battery management system according to the present invention. Channel 1, Channel 2. Channel 3 and channel 4 represent channel numbers for each cell constituting the battery pack.

In FIG. 4, channel 1 and channel 2 are formed by switching elements 112a to 112n connected to the equalizer control unit 130 for voltage equalization control with a voltage higher than the average value of all the cells (channel 1 to channel 4) (Resistors 111a to 111n provided in the current path) to cause a voltage drop, and the voltage drop was continuously performed until the voltage of the cell corresponding to channel 1 became an average value. As a result, it is confirmed that the battery cell voltages of channel 1 and channel 2 are close to the average value at the time of completion of discharge.

FIG. 5 shows an experimental graph according to the highest voltage tracking method by passive uniformity control for a conventional battery management system. Referring to FIG. 5, it can be seen that the output voltage of the cell becomes closer to the lowest voltage as the discharge is completed, but the voltage difference of each battery cell is larger than that of FIG.

FIG. 6 shows an experimental graph of the lowest voltage tracking scheme by passive uniformity control for a conventional battery management system. Referring to FIG. 6, the closer to the discharge completion time, the closer to the lowest voltage and the uniformity control effect is superior to the experimental graphs of FIGS. 4 and 5. However, since the energy consumption of the cells is excessive, . As a result, it can be seen that the condition of other cells is neglected except for the battery cell showing the lowest voltage.

C1 to Cn: Cell 110: Discharge array
110a to 110n: discharging unit 120: AD conversion unit
130: Equalization control unit 131: Voltage measurement unit
132: average value calculation unit 133:
134: discharge control section 135: memory

Claims (7)

An analog-to-digital (AD) converter for measuring and converting the voltage of each cell of the battery pack constituted by at least one or more cells connected in an array;
A discharge array for forming a current path between the anode and the cathode of each cell; And
Calculating an average value of the output voltages of each of the cells and performing discharge control for excess cells exceeding the average value among the cells using the discharge array to adjust the cell balance for each of the cells; &Lt; / RTI &
The equalizing control unit calculates an average value of the voltages of the respective cells, assigns channel numbers to the cells, arranges cells assigned channel numbers according to the voltage,
And monitors the position information occupied by the battery pack by each cell constituting the battery pack by referring to the sorted channel number. delete The method according to claim 1,
Wherein the equalization control unit comprises:
Wherein each time a voltage for each of the cells constituting the battery pack is measured, a voltage of a previously measured and ranked channel number is compared with a voltage of a currently measured channel number to set a rank of a channel number Equal control device for battery management system. The method according to claim 1,
The cell balancing may include:
And the voltage of each of the cells is equalized. The method according to claim 1,
The discharge array includes a plurality of discharge portions,
The discharge unit
And a discharge resistor and a switching element directly connected between the positive and negative terminals of each of the cells. 6. The method of claim 5,
Wherein the equalization control unit comprises:
Wherein a current path of an anode and a cathode of an excess cell in which an output voltage of the cells exceeds the average value is exhausted through the discharge resistor to lower the voltage of the excess cell. 6. The method of claim 5,
Wherein the A /
Wherein the equalizing control unit is connected to a node where the electrodes of each cell are connected to the discharging resistor to obtain an output voltage of each cell and provides the output voltage to the equalizing control unit.

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