JP3460534B2 - Power storage device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power storage device configured by connecting a number of storage batteries in series as an assembled battery, and more particularly to a power storage device suitable for use in an electric vehicle.

[0002]

2. Description of the Related Art In recent years, technological development for improving the practicality of electric vehicles has been advanced. However, the current power source of electric vehicles is one in which a large number of storage batteries (hereinafter referred to as batteries) are connected in series (group). Battery). In the case of an assembled battery in which a large number of storage batteries are connected in series in this way, the output of the assembled battery depends on the battery with the lowest voltage, so it is not possible to use each battery evenly and the capacity of each battery is maximized. Can not be demonstrated to.

By the way, like a lithium-ion battery,
In the case where the output voltage is determined depending on the discharge amount (see FIG. 6), the discharge amount (conversely, the charge amount or the remaining capacity) of each battery is made equal by making the voltage of each battery equal. Therefore, charging may be performed while adjusting the voltages of the batteries to be equal. Therefore, a voltage balancing circuit for a storage battery (battery) has been conventionally provided, and is configured as shown in FIG.

The circuit shown in FIG. 7 is an extract of one cell (or one module) of the voltage balancing circuit of the assembled battery, and each battery is equipped with the circuit. And
The charging operation is performed with the circuit as described above, and the discharging operation is performed by the circuit at the end of the charging operation. That is, although the terminal voltage of the battery 101 rises as the charging progresses, this state is monitored by the voltage monitoring circuit (voltage detection circuit) 104, and when the voltage VB across the cell becomes equal to or higher than the set voltage, the discharge switch. 102 is turned on (closed).

As a result, the discharge resistor 103 is energized and electric energy is converted into heat and consumed. Due to this consumption, when the cell voltage VB becomes equal to or lower than the set voltage, the discharge switch 102 is shifted to the off state (open state). The voltage VB of the battery cell is adjusted to the set voltage by repeatedly turning on and off the discharge switch 102.

In the actual circuit, the discharge switch 10
A general method is to use a power element such as a power transistor instead of 2, and adjust the voltage by linear control instead of on / off control.

[0007]

However, the conventional power storage device has various problems. That is, in the case of the above circuit, the energy exceeding the set voltage is wasted in the form of heat by the discharge resistor 103. For this reason,
As the power loss increases, it becomes a big problem that heat dissipation measures must be taken into consideration.

Further, the balancing is possible only when the cell voltage VB at the final stage of charging rises, and the voltage balancing cannot be performed by utilizing the idle time during discharging or when the vehicle is not used. There is. Therefore, it cannot be used for a hybrid electric vehicle that does not charge to full charge when it runs on power generation.

Further, it is necessary to use a large capacity one such as a discharge resistor, a heat radiating plate and an element for switching, which makes the device large and requires a cooling device for heat radiation, so that the structure is simple. There is also the issue of not becoming. Therefore, a balancing circuit that is not a discharge method is necessary, and the technology of Japanese Patent Laid-Open No. 6-319287 is provided as an example.

According to this technique, capacitors are connected to both ends of an assembled battery connected in series to charge each battery cell (charging cell) substantially uniformly, but a large capacity capacitor is required and The control logic of the control for selecting the required battery cell to be charged while detecting the terminal voltage of the battery cell is complicated. Therefore, a first connection mode in which a number of capacitors corresponding to each battery are provided for the batteries connected in series and each capacitor is connected in parallel with the corresponding battery, and the above-mentioned capacitors are connected to the corresponding battery, respectively. It is conceivable to balance the voltages of the batteries by alternately switching between the adjacent batteries and the second connection mode in which the batteries are connected in parallel.

In this case, the voltage of each battery is balanced by moving the charge between the batteries via the capacitors. However, in such a configuration, there is a problem that it takes time to balance the voltages because charges can be transferred only between adjacent batteries. In particular, as the discharge progresses, the voltage difference between the batteries becomes large. In this case, if the charges are transferred only at the voltage between the adjacent batteries, the voltage can not be efficiently balanced, and the voltage balance cannot be achieved. It takes a lot of time to convert.

By the way, in Japanese Unexamined Patent Publication No. 6-319287, when a battery pack in which a plurality of battery cells are connected in series is charged by a capacitor charged from a regenerative current, the terminal voltage of each battery cell and A technique for selecting a battery cell to be charged while monitoring the capacitor voltage is disclosed. In this technology, some of the battery cells are selected for charging so that the total terminal voltage of the battery cells to be charged is lower than the capacitor voltage. In addition to the above, it is possible to uniformly charge a plurality of battery cells by charging a battery cell having a low terminal voltage.

This technique can make the voltages of the batteries uniform when the batteries are charged, but cannot balance the voltages of the batteries except when the batteries are being charged. However, this is a technique that can be used for voltage balancing of general batteries. The present invention was devised in view of the above-mentioned problems, and while preventing the waste of electric energy, it is possible to quickly balance the voltages of the storage means even in a state where the battery is not fully charged. The purpose is to provide a device.

[0014]

Therefore, in the power storage device according to the present invention as set forth in claim 1, the voltage monitoring means monitors the respective voltages of the plurality of power storage means, and the connection selecting means controls the voltage of the voltage monitoring means. Depending on the monitoring result, the connection correspondence order of the power storage means for each of the plurality of power storage devices provided in parallel for each of the power storage means is selectively set. The connection switching means selectively switches between the first connection mode and the second connection mode. In the first connection mode, the above-mentioned connection correspondence order set by the connection selection means is applied to each capacitor. Each power storage unit is connected in parallel, and in the second connection mode, each power storage unit adjacent to each power storage unit connected in the first connection mode is connected in parallel to each power storage unit. Since such connection mode switching is repeated,
As a result of setting the connection correspondence order, charges are exchanged between the power storage units adjacent to each other through the power storage unit, and the voltage difference between these adjacent power storage units is reduced.

In the power storage device of the present invention as set forth in claim 2, since the connection correspondence order is set such that the voltage difference between the power storage means adjacent to each other becomes large, the power storage means is connected between the power storage means adjacent to each other. Transfer of electric charges is efficiently performed, and the voltage difference between these adjacent storage means is rapidly reduced.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 6 show a power storage device as an embodiment of the present invention. First, FIG.
The principle of voltage balancing of the power storage device will be described with reference to FIGS.

As shown in FIG. 2, the present power storage device is configured as a battery pack in which a plurality of storage batteries (secondary batteries, hereinafter also referred to as batteries or battery cells) B1 to B5 as power storage means are connected in series. ing. In this example,
Although an example in which five batteries are connected is shown as an example in which a plurality of batteries are connected in series, the number of batteries is not limited to this, of course.

A plurality of power storage devices (capacitors) C1 to C5, which can be connected in parallel with the plurality of power storage devices B1 to B5 and are connected in series, are provided.
Further, switches S1 to S5 as connection switching means are interposed between the respective storage batteries C1 to C5 and between the corresponding storage batteries B1 to B5, and one end side (terminal Switches S0 and S6 as connection switching means are provided in a connecting portion 8 that connects the cell of the storage battery B1 on the A side) and the cell of the storage battery B5 on the other end side (terminal B side) in a ring shape.

That is, terminals S1B and S2A are provided between the storage batteries B1 and B2, terminals S2B and S3A are provided between the storage batteries B2 and B3, and terminals S3B and S4A are provided between the storage batteries B3 and B4. Terminals S4B and S5A are connected between the storage batteries B4 and B5, respectively, terminals S0B and S1A are provided between one end of the assembled battery and the storage battery B1, and between the other end of the assembled battery and the storage battery 5. Are connected to terminals S5B and S6A, respectively, and further, a terminal S6B is connected to one end of the battery C1 and a terminal S0 is connected to a battery C5 side end of the battery C4.
A is connected to each.

Then, a terminal S1 is provided at one end of the capacitor C1.
A switch S1 that can selectively switch connection between A and the terminal S1B, and switch S2 that can selectively switch connection between the terminal S2A and the terminal S2B between the power storage device C1 and the power storage device C2 include a power storage device C2 and the power storage device C2. A switch S3 capable of selectively connecting and switching the terminal S3A and the terminal S3B to and from C3, and a switch S3 and selectively connecting the terminal S4A and the terminal S4B to and from the capacitor C3 and C4. The switch S4 is provided with a switch S5 capable of selectively connecting and switching between the terminal S5A and the terminal S5B on the power storage device C5 side of the power storage device C4, and the terminal S0A and the terminal S0A are provided on one end side (power storage device C4 side) of the power storage device C5. The switch S0 capable of selectively connecting and switching between S0B and
A switch S6 capable of selectively connecting and switching the terminal S6A and the terminal S6B is provided on the other end side of the switch 5.

The switches S0 to S6 are configured to be interlocked with each other and are connected to the terminals S0A to S6A (first connection mode M).
1) and the state in which they are connected to the terminals S0B to S6B (second connection mode M2), respectively, are synchronously switched in synchronization. In addition, in the first connection mode M1, each of the capacitors C1, C2, C3, C4, C
5 is in a state of being connected in parallel with each corresponding storage battery 1, 2, 3, 4, 5 and, in the second connection mode M2, each storage battery C1, C2, C3, C4, C5 is associated with the corresponding storage battery. Storage batteries B2, B3, B adjacent to B1 to B5
4, B5 and B1 are connected in parallel.

Further, the first by the connection switching means S0 to S6
The control means 7 for controlling the switching between the connection mode M1 and the second connection mode M2 is provided, and the storage batteries B1 to B1 are switched while the mode switching is repeatedly performed at a required cycle by a control signal from the control means 7. It is configured to make the potential difference of B5 equal. Here, the control operation for equalizing the potential differences of the storage batteries B1 to B5 described above is
The operation between the battery 1 and the battery 2 will be focused and described.

First, it is assumed that the voltage of the battery 1 is V1 and the voltage of the battery 2 is V2 (V1> V2). As shown in FIG. 3, the switches S1 and S2 are swung to the left and connected to the terminals S1A and S2A, respectively, and the capacitor C
When 1 and the battery B1 are connected in parallel, the voltage of the battery B1 and the potential difference of the capacitor become V1 '. This V
1'is a voltage (= V1−) that is lower than V1 by a minute amount (a minute amount) v ₁ corresponding to the charge flowing from the battery B1 to the capacitor.
v ₁ ).

Next, as shown in FIG. 4, the switches S1 and S2 are
Is swung to the right and connected to terminals S1B and S2B,
When the capacitor C1 and the battery B2 are connected in parallel, the voltage of the battery B2 and the potential difference of the capacitor become V2 '. The V2 ', the charge amount that has flowed from the battery B2 to the capacitor than V2 (minute amount) v ₂ voltage higher (= V
2 + v ₂ ).

In this way, via the capacitor C1,
Charges are transferred from the battery B1 to the battery B2, the voltage of the battery B1 gradually decreases from V1, the voltage of the battery B2 gradually increases from V2, and eventually the voltages of the batteries B1 and B2 become equal values V12 (V1 >V12> V2). This power storage device is designed to perform voltage balancing based on such a principle, but in this power storage device, terminals S1A, S1B, S2A, S2B, ...
The matrix switch circuit 1 is interposed in the portions of the conductors L1, L2, ... Connecting the respective batteries B1, B2, ... With each of the capacitors C1, C2 ,.
For each battery (battery cell) B1, B2, ...
.. It is possible to selectively set the corresponding order of parallel connection of.

The configuration of the power storage device of this embodiment will be described below with reference to FIG. In this power storage device, as shown in FIG. 1, a storage battery (secondary battery, hereinafter, as a plurality of power storage means,
Also referred to as battery or battery cell) ..., Bk, B
(K + 1), ... Are configured as an assembled battery in which they are connected in series. Hereinafter, the storage means (battery cell) is generally represented by Bk (where k is an arbitrary number from 1 to n).

In particular, the power storage device of this embodiment can be applied to an assembled battery (= a battery formed by connecting a plurality of storage batteries) used as a power source for an electric vehicle, and several tens of battery cells are connected in series. It is configured as an assembled battery connected to. Although only two battery cells Bk and B (k + 1) are shown in FIG. 1 for convenience of drawing, a large number of battery cells (not shown) are further connected, and a total of n battery cells (for example, dozens of battery cells). ) Battery cells are connected in series.

However, in this power storage device, the number of battery cells (power storage means) forming the assembled battery is not particularly limited. Further, the same number of capacitors (condensers) ..., Cm, C (m + 1), ... As the battery cells Bk are provided in series so as to correspond to the battery cells Bk, like the battery cells Bk. Has been. Hereinafter, a capacitor (electric storage device) is generally represented by Cm (where m is a number from 1 to n). Although only two capacitors Cm and C (m + 1) are shown in FIG. 1 for the sake of convenience of drawing, a large number of capacitors (not shown) are further connected so as to have the same number (n) as the battery cells Bk. Be present.

A matrix switch circuit 1 is provided between the terminals provided between the capacitors Cm and the terminals (the positive terminals and the negative terminals) of the battery cell Bk. The matrix switch circuit 1 and the matrix switch circuit control means 2
The connection selection means 3 is composed of Of the capacitors Cm connected in series with each other, the terminal terminals of the capacitors C1 and Cn at both ends are connected to each other,
The terminal terminals of the capacitors C1 and Cn at both ends are also connected to the matrix switch circuit 1.

The matrix switch circuit 1 is a switching circuit capable of selectively connecting each battery cell Bk in parallel with any capacitor Cm,
Each battery cell Bk can be connected in parallel to an arbitrary capacitor Cm according to a control signal. That is, the two ends of each capacitor Cm, that is, between the capacitors C (m-1) and Cm, and between the capacitors Cm and C (m + 1), are two in the vertical direction in FIG. Conductor part CY (m
-1) 1, CY (m-1) 2 and CYm ₁ , CYm ₂ are connected (m is an arbitrary number from 1 to n).

On the other hand, the positive terminal B of each battery cell Bk
k₁Is a conductor portion BYk shown in the vertical direction in FIG.₁Through
And the conductor portion BXk shown in the horizontal direction₁Are connected to each
Negative terminal Bk of battery cell Bk₂Smells in Figure 1
And vertical section BYk ₂Show laterally through
Line part BXk₂(K is 1 to n). That
And the conductor portion CYm connected to each capacitor Cm.₁, C
Ym₂2n switch terminals are connected to each
ing. For example, the conductor portion CYm₁Switch terminal CY
m₁Sk₁, CYm₁Sk₂(That is, CYm₁S1₁，
CYm₁S1₂~ CYm₁Sn₁, CYm₁Sn₂)
But the conductor CYm₂Switch terminal CYm₂Sk₁，
CYm₂Sk₂(That is, CYm₂S1₁, CYm₂S1
₂~ CYm₂Sn₁, CYm₂Sn₂)
Has been continued.

The positive terminal B of each battery cell Bk
conductor part BX connected to k1 and the minus terminal Bk2
k₁, BXk₂Also, each has 2n switch terminals
It is connected. For example, the conductor portion BXk₁Switch on
Terminal BXk₁Sm₁, BXk₁Sm₂(That is, BXk₁
S1₁, BXk₁S1₂~ BXk₁Sn₁, BXk₁S
n ₂), The switch terminal BXk is connected to the conductor portion BXk2.₂S
m₁, BXk₂Sm₂(That is, BXk₂S1₁, BXk
₂S1₂~ BXk2Sn₁, BXk₂Sn₂) But that
Each is connected.

Then, the switch Sk ₁ m for opening and closing the switch terminal CYm ₁ Sk ₁ on the side of each capacitor Cm and each switch terminal BXk ₁ Sm _{1 of} each battery cell Bk.
₁ is a switch terminal CYm ₂ Sk of each capacitor Cm side
₁ and each switch terminal BXk ₁ Sm of each battery cell Bk
_The switch Sk ₁ m ₂ opens and closes ₂ and the switch Sk ₂ m ₁ opens and closes the switch terminal CYm ₁ Sk ₂ on the side of each capacitor Cm and each switch terminal BXk ₂ Sm _{1 of} each battery cell Bk. , A switch Sk ₂ m ₂ is provided so as to open and close the switch terminal CYm ₂ Sk ₂ on the side of each capacitor Cm and each switch terminal BXk ₂ Sm _{2 of} each battery cell Bk.

As a result, both the positive terminal Bk ₁ and the negative terminal Bk ₂ of each battery cell Bk can be connected to any end of any capacitor Cm. Therefore, any battery cell Bk can be connected in parallel to any capacitor Cm. In addition, in FIG. 1, the switches Sk ₁ (m−1) ₁ , Sk ₂ (m) ₂ , and S (k + 1) _{1 are used.}
m ₁ and S (k + 1) ₂ (m + 1) ₂ are connected to each other, and for example, the battery cell Bk is connected to the capacitor Cm.
Shows an example in which the state in which the cells are connected in parallel and the state in which the battery cells B (k + 1) are connected in parallel can be switched.

Thus, the matrix switch circuit 1
Are the switches Sk ₁ m ₁ , Sk ₁ m ₂ , Sk ₂ m ₁ ,
By turning on and off Sk ₂ m ₂ (k and m are arbitrary numbers from 1 to n), the correspondence of the parallel connection of each battery cell (electric storage means) Bk to each capacitor (electric storage) Cm, that is, , The corresponding order of parallel connection of each battery cell Bk to each capacitor Cm can be selectively set.

The matrix switch circuit 1
(That is, setting of the corresponding order of parallel connection of each battery cell Bk to each capacitor Cm) is performed by the matrix switch circuit control means 2 described above. In this control means 2, the terminal voltage of each battery cell Bk is controlled. Based on the above, the corresponding order of parallel connection of the battery cells Bk to the capacitor Cm is set.

Therefore, a battery cell voltage monitor 4 is provided as a voltage monitoring means for monitoring the terminal voltage of each battery cell Bk, and the terminal of each battery cell Bk obtained by the monitoring of this battery cell voltage monitor 4 is provided. The voltage information is transmitted to the matrix switch circuit control means 2. In the matrix switch circuit control means 2, the corresponding order of parallel connection is set so that the voltage difference between the battery cells adjacent to each other in connection relation becomes large.

For example, five battery cells B1, B2
Assuming that the battery pack of the present power storage device is composed of B3, B4, B5, these battery cells B1, B2, B
It is assumed that the terminal voltages of B3, B4 and B5 are in a state as shown in FIG. In this order, the voltage difference between adjacent battery cells, that is, the difference between B1 and B2, the difference between B2 and B3, the difference between B3 and B4, and the difference between B4 and B
The difference from 5 is as low as 0.1 V (volt) (however, if B5 and B1 are adjacent to each other, it is relatively high at 0.4 V), so that it takes time to balance the voltage. .
That is, even if the voltages of the adjacent battery cells can be quickly balanced, it takes time to balance all the battery cells.

Therefore, the battery cells B1, B2, B3
B4, B5 capacitors C1, C2, C3, C4, C5
When the corresponding order of the parallel connection to the battery cells is rearranged to the state as shown in FIG. 5B, the voltage difference between adjacent battery cells, that is, the difference between B1 and B3, the difference between B3 and B5, B
The difference between 5 and B2 and the difference between B2 and B4 are 0.2, respectively.
When V, 0.2 V, and 0.3 V become large and the voltages of the adjacent battery cells are balanced, the balancing of all the battery cells is promoted, and the time required for balancing all the battery cells can be shortened.

In the matrix switch circuit control means 2, the capacitors C of the battery cells B1, B2, B3, B4, B5 are thus arranged so that the voltage difference between the adjacent battery cells becomes large as a result of the rearrangement.
The corresponding order of parallel connection to 1, C2, C3, C4 and C5 is rearranged. By the way, the two conductor portions CYm ₁ and CYm ₂ are connected to the ends on the side of the capacitor Cm, and the switch Sm is interposed between the conductor portions CYm ₁ and CYm ₂ and the side of the capacitor Cm. .
That is, the switch Sm includes the capacitors Cm and C (m +
1) The terminal Smc connected between them, the terminal Sm1 connected to the conductor portions CYm ₁ and CYm ₂ , and the conductor portion CY (m +
1) ₁ and CY (m + 1) ₂ connected to a terminal Sm2 connected to the capacitors Cm, C (m + 1)
Between the conductors CYm ₁ and CYm ₂ (first
Connection mode) and a state in which the capacitors Cm and C (m + 1) are connected to the conductor portions CY (m + 1) ₁ and CY (m + 1) ₂ (second connection mode).

A connection switching control means 5 is provided to issue a switching command for each switch Sm, and each switch Sm and the connection switching control means 5 constitute a connection switching means 6. The connection switching control means 5 is configured to repeatedly switch between the first and second connection modes at a predetermined cycle.

The connection mode switching cycle by the connection switching control means 5 is set so that the number of switching frequencies is approximately 1/3 of the time constant (resistance × capacitance) of the capacitor. This is because if the switching frequency of the switch Sm is set to approximately 1/3 or less of the time constant (resistance × capacitance) of the capacitor, the balancing time hardly changes regardless of the capacitance or resistance value of the capacitor. This is because the result has been clarified, and the switching frequency that achieves both the reduction of the voltage balancing time and the reduction of the switching frequency of the switch is approximately ⅓ of the time constant (resistance × capacitance) of the capacitor.

The switching frequency is not limited to approximately 1/3 of the time constant of the battery Cm, and may be set to approximately 1/3 or less of the time constant of the battery Cm, for example. However, if the switching frequency is set too high, the energy loss due to the switch Sm becomes large as described above, so about 1/3 of the time constant is preferable. The objects to be switched and controlled by the connection switching means 6 are the adjacent battery cells in the battery cells Bk for which the connection selecting means 3 sets the corresponding order of parallel connection to the capacitors Cm. In the connection mode of No. 3, each battery cell Bk for which the connection selection means 3 sets the corresponding order of parallel connection is connected to each capacitor Cm,
In the second connection mode, the adjacent battery cells of the battery cells Bk for which the parallel connection corresponding order is set by the connection selection unit 3 are connected to the capacitors Cm.

A power storage device as an embodiment of the present invention is
Since it is configured as described above, the following operation is performed. That is, the connection selection means 3 controls the connection state of each switch of the matrix switch circuit 1 through the matrix switch circuit control means 2 on the basis of the voltage information from the battery cell voltage monitor 4 as the voltage monitoring means, and each capacitor. Each battery cell B for Cm
Set the corresponding order of k parallel connections. That is, the corresponding order of parallel connection of the battery cells Bk to the capacitors Cm is rearranged so that the voltage difference between the adjacent battery cells becomes large. The switching of each switch Sm is periodically controlled through. Here, the switching frequency is set to be approximately 1/3 of the time constant (resistance × capacity) of the capacitor.

When the voltage difference between the battery cells adjacent to each other is set to be large in this way and then the voltage is balanced by switching the switch Sm, the battery cells having a large voltage difference are Since the amount of charge transfer is large, for example, the voltage of a battery cell with an extremely low voltage can be quickly increased, and the voltage of a battery cell with an extremely high voltage can be quickly decreased, so that the voltage of all battery cells can be quickly balanced. Will be carried out.

Particularly, as the discharge progresses, the voltage difference between the battery cells becomes large. In this case, if the charges are transferred only at the voltage between the adjacent battery cells, the voltage can be efficiently balanced. However, in this power storage device, since charge transfer is performed between battery cells having a large voltage difference to perform voltage balancing, even in such a case, There is an advantage that the voltage can be balanced quickly.

After the connection switching means 6 has switched a predetermined number of times or a predetermined time, the connection selecting means 3 again causes each capacitor to be based on the voltage information from the battery cell voltage monitor 4 as the voltage monitoring means. The order of parallel connection of the battery cells Bk to Cm is reset, and the connection switching means 6 again causes the connection switching control means 5 to operate.
The switching of each switch Sm may be periodically controlled through.

In particular, the larger the voltage difference between the two battery cells, the faster the transfer of charges from the battery cells to the capacitor C1, and the shorter the voltage balancing due to the transfer of charges between the two battery cells. Therefore, the voltage can be balanced efficiently. Each battery cell B for each capacitor Cm
The setting of the corresponding order of the parallel connection of k is not limited to the setting of the embodiment, and, for example, the average voltage of all the battery cells is calculated, and the average value of the voltages of the adjacent battery cells becomes the average voltage. You may set so that it may come close.

As described above, in this power storage device, the corresponding order of parallel connection of each battery cell Bk to each capacitor Cm can be set arbitrarily, so that if the battery cells are appropriately selected and the voltage balancing process is performed. The voltage balancing process can be performed extremely efficiently. In addition,
The configuration of the matrix switch circuit 1 shown in the embodiment is an example as a constituent element of the connection selection means 3, and any configuration can be performed as long as the corresponding order of parallel connection of the battery cells Bk to the capacitors Cm can be freely set. Alternatively, a matrix switch having another circuit configuration may be used.

By the way, the storage battery according to the present power storage device is formed of, for example, a lithium ion battery, and the voltage is determined depending on the amount of discharge like the characteristics of the lithium ion battery shown in FIG. Conversely speaking, it can be said that the battery voltage is determined depending on the charge amount (charge amount). Therefore, by balancing the voltage, a desired discharge amount, that is,
It will be adjusted to the state of charge amount (charge amount).

Incidentally, in the storage battery having a flat characteristic in which the voltage is not uniquely determined with respect to the discharge amount, like the characteristic of the nickel-hydrogen battery shown in FIG. 6, the discharge amount (charge amount) is desired by balancing the voltage. However, in the case where the voltage is uniquely determined with respect to the discharge amount as in the above lithium ion battery, the discharge amount (charge amount) of each battery cell of the assembled battery is equalized to a desired state. It becomes possible to fully utilize the performance of a battery (for example, a lithium ion battery).

Of course, in this device, the charge is transferred through the capacitor Cm to each battery cell Bk.
There is no large heating element to balance the voltage of
Balancing is achieved while avoiding energy loss due to heat generation. In addition, not only during full charge of the battery pack, but also during running, charging, discharging, etc., the balancing operation can be performed in all states regardless of usage conditions. The balancing operation can be performed even when the battery is not used. Of course, it can also be used for a hybrid electric vehicle that does not charge until fully charged, such as a hybrid electric vehicle.

When such a circuit is actually applied, it is necessary for the switch Sm to operate efficiently, with reliable operation and good durability. It is preferable to use a power element (FET or IGBT) or the like with a switching loss as small as possible, and to equip the switch switching control device 1 with a circuit for automatically switching the switch Sm by an external oscillation circuit or the like.

If a capacitor having a relatively large capacity, such as an electric double layer capacitor, is used as the capacitor Cm, the voltage can be quickly balanced, but for example, such voltage balancing control is performed constantly or frequently. By doing so, even if a small-capacity capacitor is used, the amount of charge can be balanced by practically sufficient voltage balancing. Further, it is considered necessary to have a circuit for preventing inrush current to the capacitor Cm and an initial charging circuit.

Further, in the switch switching control device 1, in addition to the switch switching operation as described above, a maintenance switch used when performing maintenance and each switch Sm are interlocked, or an external voltage measuring circuit is used. When the need arises, a driving method, a voltage balancing process (a process of selecting each switch Sm and appropriately connecting them) are performed when the vehicle is not in use, or a timer circuit or the like is performed at regular intervals. Method,
Various combinations are conceivable, such as a method to be executed when a balancing instruction is received from a control circuit or the like of an electric load to be connected (in the case of an electric vehicle, a motor controller, a remaining capacity meter, etc.)

The power storage device can also be applied to an assembled power storage device in which a capacitor (power storage device) is used instead of a battery as the power storage means. That is, instead of the assembled battery including a plurality of storage batteries (batteries) connected in series, it is also possible to apply the present invention to an assembled battery including a plurality of capacitors (condensers) connected in series. Then, when the battery or electric double layer capacitor, etc., in which various troubles due to variations in cell voltage are apt to be prominent in the assembled battery state or the assembled battery state, the above-described structure is adopted and a voltage balancing circuit is configured, a large energy consumption is increased. It becomes possible to realize a system that can always balance the voltage without loss.

It is possible to embody a method for balancing the voltage at any necessary time by monitoring the battery cell voltage or the like, not by constantly operating this circuit. In particular, by applying this circuit to a lithium-ion battery, it becomes easy to secure safety while drawing out 100% of the capacity of the lithium-ion battery. Note that the time required for voltage balancing can be shortened by changing the speed of connection mode switching by the control unit as the cell voltage unbalance is changed from large to small.

[0058]

As described above in detail, according to the power storage device of the present invention as set forth in claim 1, the connection correspondence order of the power storage means for each of the plurality of power storage devices is selected according to the voltage monitoring result of each power storage means. After being set to each storage device, a first connection mode in which each storage device is connected in parallel to each storage device and each storage device adjacent to each storage device connected in each storage device in the first connection mode are set. Since the switching to the first connection mode for parallel connection is repeatedly performed, as a result of setting the connection correspondence order, electric charges are exchanged between the adjacent electric storage means through the electric storage devices, and between the adjacent electric storage means. Since the voltage difference is reduced, there is an advantage that the voltage can be quickly balanced among all the power storage units according to the setting of the connection correspondence order.

According to the power storage device of the present invention as defined in claim 2, the connection corresponding order is set so that the voltage difference between the power storage means adjacent to each other becomes large, so that the voltage balance among all the power storage means. There is an advantage that the conversion can be performed quickly.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a main configuration of a power storage device as an embodiment of the present invention.

FIG. 2 is a circuit diagram for explaining a voltage balancing principle of a power storage device as an embodiment of the present invention.

FIG. 3 is a main part circuit diagram for explaining a voltage balancing principle of a power storage device as an embodiment of the present invention.

FIG. 4 is a main part circuit diagram for explaining a voltage balancing principle of a power storage device as an embodiment of the present invention.

5A and 5B are diagrams showing an example of connection selection of a power storage device as one embodiment of the present invention, in which FIG. 5A shows a state before connection selection and FIG. 5B shows a state after connection selection. .

FIG. 6 is a graph showing characteristics of a battery in a power storage device according to an embodiment of the present invention.

FIG. 7 is a schematic circuit diagram showing a conventional power storage device.

[Explanation of symbols]

1 Matrix Switch Circuit 2 Matrix Switch Circuit Control Means 3 Connection Selection Means 4 Battery Cell Voltage Monitor 5 as Voltage Monitoring Means 5 Connection Switching Control Means 6 Connection Switching Means Bk Battery Cells Cm Constituting Storage Battery (Secondary Battery) as Power Storage Means Battery (capacitor) Sm switch

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-11-98698 (JP, A) JP-A-10-164768 (JP, A) JP-A-10-285817 (JP, A) JP 2000-511398 (JP, A) US Patent 6064178 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02J ^7/ 00-7/12 H02J ⁷ /34-7/36

Claims (2)

(57) [Claims] 1. A power storage device configured by connecting a plurality of power storage means in series, and a plurality of power storage devices connected in series with each other and provided in parallel with the respective power storage means. Voltage monitoring means for monitoring respective voltages of the plurality of power storage means, and connection selection means for selectively setting a connection corresponding order of the power storage means to each of the above-mentioned power storage devices according to a voltage monitoring result of the voltage monitoring means, A first connecting the respective storage means in parallel to the respective storage devices in the connection corresponding order set by the connection selection means;
Connection mode, and connection switching means for selectively switching, for each of the above-mentioned storage devices, a second connection mode in which each storage means adjacent to each storage means connected in the first connection mode is connected in parallel. A power storage device, characterized in that the connection switching means is configured to repeatedly switch the first and second connection modes. 2. The power storage device according to claim 1, wherein the connection selection unit sets the connection correspondence order so that a voltage difference between the power storage units adjacent to each other becomes large.