JP4059225B2 - Voltage equalization circuit for battery pack - Google Patents

Description

  The present invention relates to a voltage equalization circuit for an assembled battery.

  For example, in an assembled battery using a lithium battery, it is necessary to equalize voltage between secondary batteries (cells) constituting the assembled battery, that is, to reduce voltage variation, and various voltage equalization circuits have been proposed.

  Patent Document 1 below uses a plurality of voltage equalization circuit blocks that equalize the internal cell voltage of a battery block composed of two cells connected in series with each other, and further, two battery blocks share one cell. Have proposed a voltage equalization method (two-cell equalization method) for equalizing all cell voltages of the assembled battery.

Similarly, Patent Document 2 below uses a plurality of voltage equalization circuit blocks that equalize the internal cell voltage of a battery block composed of three cells connected in series with each other, and two battery blocks share one cell. Thus, a voltage equalization method (three-cell equalization method) for equalizing all cell voltages of the assembled battery has been proposed.
Japanese Patent Application Laid-Open No. 08-556443 JP-A-11-262188

  In the above-described 2-cell equalization method of Patent Document 1, n-1 voltage equalization circuit blocks are required for voltage equalization of n-cell assembled batteries. If each voltage equalization circuit block is an IC, In this case, there arises a problem that a large number of ICs are required to realize a voltage equalization circuit for the assembled battery. In order to improve this problem, it is conceivable to integrate a plurality of voltage equalizing circuit blocks adjacent to each other in a single IC. For example, if two battery blocks that are adjacent to each other in potential are integrated in one IC, this is equivalent to equalizing three cells after all (2k (k is a positive integer) +1) total number of cells It is possible to equalize only the assembled battery having That is, if the number of voltage equalization circuit blocks integrated in one IC is increased, it can be applied only to a battery pack having a specific total number of cells.

  Similarly, the 3-cell equalization method of Patent Document 2 described above can equalize only the assembled batteries having the total number of cells (2k (k is a positive integer) +1).

  In the same way, the 4-cell equalization method can equalize only the assembled battery having the total number of cells (3k (k is a positive integer) +1), and the 5-cell equalization method (4k ( There is a problem that equalization can be performed only with assembled batteries having k as a positive integer) +1) total number of cells.

  That is, the above-described conventional voltage equalization method has a drawback that voltage equalization of assembled batteries having various total cell numbers cannot be performed without increasing the types of ICs for voltage equalization.

  The present invention has been made in view of the above problems, and voltage equalization of assembled batteries capable of voltage equalization of assembled batteries having various total cell numbers without increasing the types of ICs for voltage equalization. Its purpose is to provide a circuit.

  The voltage equalization circuit for the assembled battery according to the present invention divides the voltage of the battery block composed of m (m is a positive integer of 3 or more) secondary batteries connected in series with each other into m and outputs the divided voltage. If it is determined that the divided voltage is lower by comparing the circuit, the divided voltage, and the potential at the connection point of two adjacent cells of the battery block, the secondary battery on the lower potential side than the connection point A discharge circuit that discharges and discharges the secondary battery at a higher potential side than the connection point to equalize the voltages of the secondary batteries in the battery block when it is determined that the partial pressure is higher; Each of the pair of voltage equalization circuit blocks, and the pair of voltage equalization circuit blocks includes a pair of battery packs in which n (n is a positive integer larger than m) secondary batteries are connected in series. A set for performing the equalization operation individually on the battery blocks In the voltage equalization circuit of the battery, the pair of battery blocks is characterized in that sharing x (x is a positive integer of 2 or more) number of the secondary battery connected adjacent to each other.

  In the present invention, since the battery block has three or more cells, the voltage equalization circuit block individually controls the potential of the connection points of a plurality of adjacent two cells belonging to the battery block that performs voltage equalization. A plurality of discharge circuits (for example, operational amplifier circuits).

  That is, according to the present invention, a circuit configuration in which two battery blocks that perform voltage equalization between cells independently share two or more cells (hereinafter referred to as a multiple cell sharing method) is adopted. is doing. On the other hand, the conventional voltage equalization method is also referred to as a one-cell sharing method, since two battery blocks share one cell. In this way, by using a voltage equalization circuit block that equalizes a battery block of a certain number of cells, an assembled battery having a total number of cells different from the conventional one-cell sharing method is used as a terminal of the voltage equalization circuit block. It is possible to equalize the voltages without generating fractions. It should be noted that the generation of fractions at the terminals of the voltage equalization circuit block means that the highest potential terminal and the lowest potential terminal for detecting the block voltage of the voltage equalization circuit block to form each divided voltage, and the cell of the battery block This means that a plurality of intermediate potential terminals for discharging the battery cannot be connected to a connection point between each cell of the battery block without causing a space.

  For example, when the battery block has three cells, the voltage equalization of the assembled battery having an arbitrary total number of cells can be achieved by adopting the two-cell sharing method. Further, when the two-cell sharing method is adopted when the battery block has four cells, it is possible to equalize the voltages of the assembled batteries in which the total number of cells is an even number of four or more.

  Furthermore, according to the present invention, the time required for voltage equalization can be shortened. In other words, the fact that a battery block has a plurality of shared cells means that a plurality of cells are subjected to voltage equalization processing between the battery blocks between adjacent battery blocks. Voltage equalization speed is improved.

In a preferred aspect, predetermined y ( two is a positive integer different from x) connected adjacent to each other or another pair of battery blocks sharing one secondary battery individually It has another pair of voltage equalization circuit blocks for equalization. That is, according to this aspect, for example, a battery block group that is voltage-equalized by the two-cell sharing method of the present invention and a battery block group that is voltage-equalized by the conventional one-cell sharing method are mixed to form an assembled battery. Since it can be configured, it is possible to equalize the voltage of assembled batteries having various or arbitrary total cell numbers. Alternatively, the assembled battery may be configured by a battery block group that is voltage-equalized by the 2-cell sharing method and a battery block group that is voltage-equalized by the 3-cell sharing method. Furthermore, an assembled battery in which a battery block group of a 1-cell shared cell system, a battery block group of a 2-cell shared cell system, and a battery block group of a 3-cell shared cell system can be configured. As a result, according to this aspect, it is possible to perform voltage equalization on assembled batteries having various or arbitrary total cell numbers using an IC in which one type of voltage equalization circuit block is integrated.

  In a preferred aspect, there is provided switch means for prohibiting an operation of matching a predetermined voltage division of the voltage dividing circuit by each discharge circuit and a potential of a connection point of a predetermined secondary battery of the battery block. In this case, by any chance, the operation of two voltage equalization circuit blocks sharing two or more cells interferes, and the cells of two battery blocks in which these two voltage equalization circuit blocks perform voltage equalization Even if a situation where the voltage does not converge to a predetermined voltage value occurs, by operating the switch means, the voltage equalization operation of the predetermined voltage equalization circuit block is prohibited, thereby suppressing the interference. The cell voltages of these two battery blocks can be converged to a predetermined voltage value satisfactorily.

  The switch means may include a switch for cutting off the connection between the connection point of the adjacent two cells and the discharge circuit, or a switch for stopping the operation of the discharge circuit. These switches automatically operate according to a predetermined program. Alternatively, it may be opened and closed manually. As a switch for stopping the operation of the discharge circuit, for example, a power switch for the discharge circuit that cuts off the application of the power supply voltage to the power supply terminal of the discharge circuit can be employed.

  The voltage equalization circuit block has a plurality of discharge circuits (for example, operational amplifier circuits) that individually control potentials of connection points of a plurality of adjacent two cells belonging to a battery block that performs voltage equalization. This switch means only needs to be able to cut off only the operation of a part of the plurality of discharge circuits included in one voltage equalization circuit block and individually discharging the connection points of a plurality of adjacent two cells.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. Of course, the voltage equalization circuit of the assembled battery of the present invention is not limited to the following embodiments, and the technical idea of the present invention can be realized by combining known techniques and techniques having common functions with them. . For example, a charge transfer system using a capacitor instead of an operational amplifier circuit can be employed as the discharge circuit.

  The voltage equalization circuit of the assembled battery of Example 1 will be described with reference to the block diagram shown in FIG. In FIG. 1, 1 to 6 are secondary batteries (cells) constituting the assembled battery 100, the cells 1 to 4 constitute the battery block 101, and the cells 3 to 6 are on the low potential side of the battery block 101. The battery block 102 adjacent to the battery block 101 is configured. 7 and 8 are 4-cell equalization ICs (voltage equalization circuit block referred to in the present invention) having the same circuit configuration. The 4-cell equalization IC 7 performs voltage equalization of the battery block 101 and is used for 4 cells. The equalization IC 8 performs voltage equalization of the battery block 102.

  In this embodiment, two battery blocks 101 and 102 that are adjacent to each other while being individually subjected to voltage equalization processing by the four-cell equalization ICs 7 and 8 that form voltage equalization circuit blocks, respectively, 4 is shared. In other words, these four-cell equalization ICs 7 and 8 perform voltage equalization on the two shared cells 3 and 4.

  As a result, the 4-cell equalization IC 7 equalizes the voltages of the cells 1 to 4 and the 4-cell equalization IC 8 performs the voltage equalization of the cells 3 to 6. Will be equalized. That is, if the 4-cell equalization IC of this embodiment is used, the voltage equalization of the assembled battery having a total cell number of 6 can be performed as shown in FIG. Considering further generalization, voltage equalization can be performed for an assembled battery having a total number of cells that is an even number of six or more by using a positive integer of four or more equalization ICs for four cells.

  As a specific circuit configuration of the 4-cell equalization ICs 7 and 8, a method using a conventional operational amplifier type discharge circuit, which is one less than the number of cells of the battery block that performs voltage equalization, or a capacitor to be switched is used. It is possible to employ a method of moving charges by using them. The operational amplifier type discharge circuit will be specifically described below.

  A voltage equalization circuit of the assembled battery of Example 2 will be described with reference to a circuit diagram shown in FIG. In FIG. 2, 1 to 4 are secondary batteries (cells) constituting the assembled battery 100 ′, the cells 1 to 3 constitute the battery block 103, and the cells 2 to 4 represent the low potential side of the battery block 103. The battery block 104 adjacent to the battery block 103 is configured. 7 'and 8' are equalization ICs for three cells (also referred to as voltage equalization circuit blocks) having the same circuit configuration, and the equalization IC for 3 cells 7 'performs voltage equalization of the battery block 103 and 3 cells. The equalizing IC 8 ′ performs voltage equalization of the battery block 104.

  Also in this embodiment, the two battery blocks 103 and 104 adjacent to each other while being individually subjected to the voltage equalization processing by the two three-cell equalization ICs 7 ′ and 8 ′ include the two cells 2, 3 and 3 adjacent to each other. Share In other words, these two 3-cell equalization ICs 7 ′ and 8 ′ perform voltage equalization on the same two cells 7 and 8.

  As a result, the 3-cell equalization IC 7 ′ performs voltage equalization for the cells 1 to 3 and the 3-cell equalization IC 8 ′ performs voltage equalization for the cells 2 to 4. Will be equalized. That is, if the three-cell equalization IC of this embodiment is used, it is possible to equalize the voltage of the assembled battery having a total cell number of four as shown in FIG. In this embodiment, when the total number of cells is 5 or more, three three-cell equalization ICs perform voltage equalization on one and the same cell. Therefore, in this case, by setting the number of equalization ICs for three cells to 2 or more, it is possible to equalize the voltages of the assembled batteries having a total number of cells of 4 or more.

  The circuit operation of the 3-cell equalization ICs 7 'and 8' will be described below. The three-cell equalization IC 7 ′ has a resistance type voltage dividing circuit 70 and two operational amplifier type discharge circuits (discharge circuits in the present invention) 71 and 72. The three-cell equalization IC 8 ′ has a resistance voltage dividing circuit 80 and two operational amplifier type discharge circuits (discharge circuits in the present invention) 81 and 82. The three-cell equalization ICs 7 'and 8' have a highest potential terminal L1, two intermediate potential terminals L2 and L3, and a lowest potential terminal L4.

  The voltage dividing circuit 70 is formed by connecting voltage dividing resistors R21, R22, and R23 having equal resistance values in series, and the voltage dividing circuit 80 is formed by connecting voltage dividing resistors R31, R32, and R33 having equal resistance values in series. Become. The discharge circuit 71 has an operational amplifier 211 and its negative feedback resistor 201, and the discharge circuit 72 has an operational amplifier 212 and its negative feedback resistor 202. The discharge circuit 81 has an operational amplifier 311 and its negative feedback resistor 301, and the discharge circuit 82 has an operational amplifier 312 and its negative feedback resistor 302. That is, the highest potential terminal L1 and the lowest potential terminal L4 form terminals (also referred to as voltage input terminals) for inputting the voltage of the battery block to the voltage dividing circuit, and the two intermediate potential terminals L2 and L3 are each battery block. 2 are terminals (also referred to as discharge terminals) for changing the potential at the connection point of two adjacent cells existing in two locations.

  Accordingly, the three voltage dividing output points of the voltage dividing circuit 70 output the divided voltages V1 and V2 obtained by dividing the voltage of the battery block 103 into three equal parts, and the three voltage dividing output points of the voltage dividing circuit 80 are the voltages of the battery block 104. Are divided into three equal parts, and divided voltages V1 ′ and V2 ′ are output, and these divided voltages are input to the positive input terminals of the discharge circuits 71, 72, 81 and 82. The potentials V12, V23, and V34 of the intermediate potential terminals L2 and L3 of the battery blocks 103 and 104 are input to the negative input terminals of the discharge circuits 71, 72, 81, and 82, respectively.

  The operation itself of each operational amplifier is essentially the same as that described in the above-mentioned patent document. The operational amplifier 212 compares the divided voltage V1 and the detected voltage V23, the operational amplifier 211 compares the divided voltage V2 and the detected voltage V12, the operational amplifier 312 compares the divided voltage V1 ′ and the detected voltage V34, and the operational amplifier 311 The voltage V2 ′ is compared with the detection voltage V23.

  Hereinafter, the operation of the discharge circuit 71 including the operational amplifier 211 with the negative feedback resistor 201 will be described. Here, it is assumed that each operational amplifier is supplied with power supply voltage from two cells 1 and 2 whose electrode terminals are connected to the connection point of the assembled battery connected to the negative input terminal.

  First, consider a case where the detection voltage V12 is higher than the divided voltage V2. The output voltage of the discharge circuit 71 becomes very low, and the current flows from the intermediate potential terminal L2 to the output terminal of the discharge circuit 71 through the negative feedback resistor 201, whereby the cell 2 or the cells 2 and 3 are discharged. Conversely, consider the case where the detection voltage V12 is lower than the divided voltage V2. The output voltage of the discharge circuit 71 becomes very high, and the current flows from the output terminal of the discharge circuit 71 toward the intermediate potential terminal L2 through the negative feedback resistor 201, whereby the cell 1 is discharged. Such an operation is essentially the same in the other discharge circuits 72, 81, 82, whereby the 3-cell equalization IC 7 ′ performs voltage equalization between the cells of the battery block 103, and the 3-cell equalization. The integrated IC 8 ′ performs voltage equalization between the cells of the battery block 104, whereby voltage equalization between the cells of the assembled battery 100 ′ is performed. The output terminal of the discharge circuit 71 is connected to the + power supply terminal and the −power supply terminal of the operational amplifier 211 through the internal circuit of the operational amplifier 211. Between these two power supply terminals, all cells of the assembled battery or a combination of predetermined cells are used. It is assumed that a power supply voltage is applied. In other words, if it is determined that the partial pressure is lower by comparing the partial pressure with the potential at the connection point of two adjacent cells in the battery block, the secondary battery on the lower potential side than the connection point is discharged and the partial pressure is If it is determined that the voltage is higher, the secondary battery on the higher potential side than the connection point can be discharged to equalize the voltage of each secondary battery in the battery block. Further, the two voltage equalizing circuit blocks 7, Since two battery blocks that are individually equalized by 8 share two cells, voltage equalization between these two battery blocks can be processed in a short time.

(Modification)
A modification will be described with reference to FIG. This embodiment shows an example in which the 4-cell equalization ICs 7 to 9 are equalized by the conventional one-cell sharing method. Two battery blocks adjacent to each other among the battery blocks 101 to 103 share one cell. That is, when the 4-cell equalization IC is used, the voltage of the assembled battery can be equalized using any one of the 1-cell sharing method, the 2-cell sharing method, and the 3-cell sharing method.

( Reference mode)
A reference mode will be described with reference to FIG.

This reference mode shows an example in which voltage equalization is performed on an assembled battery having a total number of 9 cells using the 4-cell equalization ICs 7 to 9. The 4-cell equalization ICs 7 and 8 individually perform voltage equalization on the two battery blocks 101 and 102 having two shared cells, and the 4-cell equalization ICs 8 and 9 have one shared cell. Voltage equalization is individually performed for the two battery blocks 102 and 103. That is, when the 4-cell equalization IC is used, it is possible to perform voltage equalization of the assembled battery in which the 1-cell sharing method, the 2-cell sharing method, and the 3-cell sharing method are mixed.

  A voltage equalization circuit of the assembled battery of Example 3 will be described with reference to FIG. This embodiment is characterized in that the switches S1, S2, and S3 are provided in FIG. Normally, the switches S1 and S2 are turned on and the switch S3 is turned off, so that the circuit configuration is the same as in FIG.

  In FIG. 5, if the tolerance between the resistances of the operational amplifier and the voltage dividing circuit is large, the voltage equalization between the battery blocks may not converge to a predetermined value. That is, in FIG. 2, the voltages of the cells 1 to 4 are V1, V2, V3, and V4, and the resistance values of the voltage dividing resistors R21, R22, R23, R31, R32, and R33 are simply R21, R22, and R23 for simplification. , R31, R32, R33, the convergence condition is as follows.

V1: V2: V3 = R21: R22: R23
V2: V3: V4 = R31: R32: R33
But these two equations hold
R22: R23 = R32: R33
This is only the case. When it is expected that the circuit constants vary greatly between the voltage equalization circuit blocks (three-cell equalization IC) and the voltage equalization cannot be performed well, the switches S1 and S2 in FIG. By turning on the switch S3, the operation of the discharge circuit 81, which is an operational amplifier circuit, is stopped, so that convergence can be facilitated. That is, in this aspect, by adding a switch, the 2-cell shared 3-cell equalization method is changed to the 1-cell shared 2-cell equalization method to avoid interference (opposite operation) between operational amplifiers due to circuit constant variations. Is. In practice, a slight dead band is provided so that some variation does not become a problem. However, when the dead band is increased, an error in the equalization voltage increases.
(Modification)
In order to selectively stop the operation of the discharge circuit 82 of the voltage equalization circuit block 8 ′, as shown in FIG. 6, between the + power supply terminal of the operational amplifier 311 of the discharge circuit 82 and the terminal to which the power supply voltage is applied. A power switch S4 may be provided in the front and the power switch S4 may be opened. In this way, the same effect can be achieved with a single switch.

FIG. 3 is a block circuit diagram illustrating a voltage equalization circuit of the assembled battery according to the first embodiment. FIG. 6 is a circuit diagram showing a voltage equalization circuit of the assembled battery of Example 2. It is a block circuit diagram which shows a deformation | transformation aspect. It is a block circuit diagram which shows a deformation | transformation aspect. FIG. 6 is a circuit diagram showing a voltage equalization circuit of the assembled battery of Example 3. It is a block circuit diagram which shows a deformation | transformation aspect.

Explanation of symbols

L1 highest potential terminal L2 intermediate potential terminal L4 lowest potential terminal R21 to R23 voltage dividing resistor R31 to R33 voltage dividing resistor S1 to S4 switch (switch means)
1-6 cells (secondary battery)
7- cell equalization IC (voltage equalization circuit block, one of a pair of voltage equalization circuit blocks referred to in the present invention )
8 cell equalization IC (voltage equalization circuit block, another one of a pair of voltage equalization circuit blocks referred to in the present invention, and one of another pair of voltage equalization circuit blocks referred to in the present invention)
9 Cell equalization IC (voltage equalization circuit block, other one of the other pair of voltage equalization circuit blocks referred to in the present invention)
70, 80 Voltage divider circuit 71, 72 Discharge circuit 81, 82 Discharge circuit 100 Battery pack 101 Battery block (one of a pair of battery blocks in the present invention)
102 battery block (the other one of the pair of battery blocks referred to in the present invention and one of the other pair of battery blocks referred to in the present invention)
103 battery block (the other one of the other pair of battery blocks referred to in the present invention)
104 battery block 211 operational amplifier 212 operational amplifier 311 operational amplifier 312 operational amplifier

Claims (3)

A voltage dividing circuit which (is m 3 or more positive integer) connected in series the m voltage of the battery block of the secondary battery of m to divide the output from each other, a front Stories partial pressure of the battery block When it is determined that the partial pressure is lower by comparing the potential at the connection point of two adjacent cells, the secondary battery on the lower potential side than the connection point is discharged, and the partial pressure is higher. a pair of voltage equalizing circuit blocks each having a discharge circuit for equalizing the voltage of each secondary battery when it is determined within the battery block to discharge the rechargeable battery on the high potential side of the connection point Prepared,
The pair of voltage equalization circuit blocks (7, 8) includes:
A set in which the equalization operation is individually performed on a pair of battery blocks (101, 102) of a battery pack (100) in which n (n is a positive integer larger than m) secondary batteries are connected in series. In the battery voltage equalization circuit,
The pair of battery blocks (101, 102)
A voltage equalization circuit for an assembled battery, wherein x (x is a positive integer of 2 or more) secondary batteries (3, 4) connected adjacent to each other are shared. In the assembled battery voltage equalization circuit according to claim 1,
Predetermined y (y is a positive integer greater than or equal to 2 different from x) or one secondary battery connected adjacent to each other and different from the pair of battery blocks (101, 102) Another pair of voltage equalization circuit blocks (7, 8) which are different from the pair of voltage equalization circuit blocks (7, 8) individually equalizing the other pair of battery blocks (102, 103) as a block pair A voltage equalization circuit for an assembled battery, comprising the voltage equalization circuit block (8, 9) . In the assembled battery voltage equalization circuit according to claim 1,
The voltage equalization circuit block includes:
A voltage of the assembled battery comprising switch means for prohibiting an operation of matching a predetermined voltage division of the voltage dividing circuit by the discharge circuit with a potential of a connection point of a predetermined secondary battery of the battery block. Equalizing circuit.

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