WO1998015047A1

WO1998015047A1 - Electricity storing device

Info

Publication number: WO1998015047A1
Application number: PCT/JP1997/003506
Authority: WO
Inventors: Hiroyasu Suzuki; Toshiya Shinbo; Nobuya Furukawa
Original assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
Priority date: 1996-10-03
Filing date: 1997-10-01
Publication date: 1998-04-09

Abstract

In an electricity storing device in which electricity storing means (1-5) are connected in series, capacitors (C1-C5) which are connected in series to each other in a state where the capacitors (C1-C5) can respectively be connected in parallel with the means (1-5), switching means (S0-S6) which can switch the connecting mode of the means (1-5) between a first connection mode in which the means (1-5) are respectively connected in parallel with the capacitors (C1-C5) and a second connection mode in which the electricity storing means (2, 3, 4, 5 and 1) which are adjacent to the means (1, 2, 3, 4 and 5) respectively connected to the capacitors (C1-C5) in the first connection mode are respectively connected in parallel to the capacitors (C1-C5), and a control means (7) which controls the switching means (S0-S6) so that the means (S0-S6) can alternately switch the connection mode between the first and second modes in a prescribed cycle are provided so as to balance the voltages at the means (1-5) against each other by transferring charges among the means (1-5). The connection mode switching cycle is set to about 1/3 or smaller than the time constant which is found from the products of the resistance and the capacitance values of the capacitors (C1-C5).

Description

Technical field

The present invention relates to a power storage device suitable for use in an electric vehicle. Background art

In recent years, technological development has been promoted to improve the practicality of electric vehicles. However, the current power source for electric vehicles is a battery in which a large number of storage batteries (hereinafter also referred to as batteries) are connected in series (assembled batteries). You are using

In the case of such an assembled battery in which a number of storage batteries are connected in series, the output of the assembled battery depends on the battery with the lowest voltage, so that each battery cannot be used equally and the capacity of each battery is maximized. Can not be demonstrated.

By the way, in the case where the output voltage is determined depending on the discharge amount, such as a lithium-ion battery (hereinafter, referred to as a lithium battery) (see FIG. 5), the voltage of each battery is equalized, and the It is possible to equalize the amount of discharge of the battery (in other words, the amount of charge or the remaining capacity), and charge while adjusting the voltage of each battery 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. 12 is an excerpt of one cell (or one module) of the voltage balancing circuit of the assembled battery, and each battery is equipped with the same circuit.

Then, a charging operation is performed in a state including such a circuit. At the end of the charging operation, a discharging operation is performed by the circuit. In other words, the terminal voltage of the battery 101 rises due to the progress of charging, but this state is monitored by the voltage monitoring circuit (voltage detection circuit) 104, and the voltage VB across the cell exceeds the set voltage. In this case, the discharge switch 102 is shifted to the ON state (closed state).

As a result, the discharge resistor 103 is energized, and the electric energy is consumed by being converted into heat.

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). By repeatedly turning on and off the discharge switch 102, the voltage VB of the battery cell is adjusted to the set voltage.

In an actual circuit, a method is generally used in which a power element such as a power transistor is used in place of the discharge switch 102 and the voltage is adjusted by linear control instead of on / off control.

However, conventional power storage devices have various problems.

That is, in the case of the above-described circuit, the energy exceeding the set voltage is wasted by the discharge resistor 103 in the form of heat.

For this reason, the power loss increases and the major problem is that heat dissipation measures must be taken into account.

In addition, balancing can be performed only when the cell voltage VB at the end of charging rises, and there is a problem that voltage balancing cannot be performed using idle time during discharging or when the vehicle is not used. is there.

Therefore, it cannot be used for those that do not charge until they are fully charged during power generation, such as hybrid electric vehicles.

In addition, large-capacity devices such as discharge resistors, heat sinks, and switching elements must be used, which does not simplify the structure, such as increasing the size of the device or requiring a cooling device for heat dissipation. There are issues _c Therefore, a balancing circuit other than the discharge method is required. As an example, the technique disclosed in Japanese Patent Application Laid-Open No. Hei 6-319927 is provided.

This technology connects capacitors at both ends of a series-connected battery pack and charges each battery cell (charged cell) almost uniformly. However, a large-capacity capacitor is required, and each battery cell is required. The control to select the desired cell to be charged while detecting the terminal voltage of the battery is complicated with the control port.

Therefore, for the batteries connected in series, the number of capacitors corresponding to each battery is provided, each capacitor is connected in parallel with the corresponding battery, and each capacitor is placed adjacent to the corresponding battery. By alternately switching between the battery and the state of being connected in parallel, it is conceivable to balance the voltage of each battery by transferring charge between the batteries via a capacitor.

However, in such a configuration, the voltage balancing time of each battery greatly changes depending on the specification of the capacitor and the switching cycle (or switching frequency) for switching each connection mode, so that the performance of the battery may not be fully exploited. Conceivable. Also, simply setting the switching frequency high can shorten the voltage balancing time, but in this case, the energy loss increases with the switching operation at the time of mode switching. Challenges arise. Disclosure of the invention

An object of the present invention is to provide a power storage device that can balance the amount of charge of power storage means even when the battery is not fully charged, while preventing waste of electric energy.

Another object of the present invention is to meet the specifications and performance of batteries and capacitors. Power storage device that efficiently balances the voltages of a plurality of batteries in the same manner, and can reduce the time for balancing the voltages of a plurality of storage batteries while reliably preventing energy loss due to the switching operation described above. It is to provide

In order to achieve the above object, a power storage device of the present invention includes: a plurality of power storage units connected in series; the same number of power storage units as the plurality of power storage units; and the plurality of power storage units for each of the plurality of power storage units. A combination of a switching means capable of switching the combination of the parallel connection and a combination of the parallel connection of each of the storage means with respect to each of the storage batteries at a predetermined cycle while connecting each of the storage capacitors in parallel so as to be one-to-one. Control means for controlling the switching means so as to sequentially switch to the adjacent power storage means.

In the present device, as the connection mode by the switching means, a first connection mode in which the plurality of power storage means are connected in parallel to each of the plurality of power storages; and a first connection mode in which each of the plurality of power storages is connected to the first A second connection mode in which the power storage means adjacent to the power storage means connected in the connection mode are respectively connected in parallel, wherein the control means includes a first connection mode and a second connection mode which are arranged at predetermined intervals. It is preferable that the switching means be controlled so as to alternately switch between the two.

With such a configuration, it becomes possible to transfer charges between the plurality of power storage means, and the charge of the power storage means having a relatively high voltage among the plurality of power storage means can be transferred. By transferring to the storage means, the voltage of the plurality of storage means can be balanced. Therefore, there is an advantage that voltage balancing can be performed while suppressing power loss without wasting the unbalanced voltage in power consumption due to heat dissipation. An additional advantage is that the heat dissipation measures can be reduced by reducing the heat dissipation loss. Further, in the present apparatus, one terminal is connected to the plurality of power storage means and the other terminal is connected to the switching means, and the same number of resistors as the plurality of power storage means is further provided. The connection modes by means include a first connection mode in which the plurality of power storage means are connected in parallel to each of the plurality of power storage devices, and a first connection mode in which each of the plurality of power storage devices is connected in the first connection mode. A second connection mode in which power storage means adjacent to the connected power storage means are connected in parallel, and a first connection mode in which the plurality of power storage devices are respectively connected to the plurality of power storage devices through the plurality of resistors. A third connection mode in which the connected power storage means or the power storage means connected in the second connection mode are connected in parallel, respectively, wherein the control means first performs the third connection mode. By performing According connection, then, to switch alternately between the first connection mode and said second connection mode one de, it is preferably configured to control the said switching means.

With this configuration, even if a voltage is applied to the capacitor while the capacitor is not storing electric charge, a current flows through the resistor through the resistor, so a sudden inrush current flows into the capacitor. This is advantageous in that the capacitor can be sufficiently protected from a sudden inrush current. In addition, since the inrush current can be prevented in this way, it is possible to lower the withstand current specification of the capacitor, and therefore, there is an additional advantage that a small-capacity capacitor can be used. be able to.

Further, in this device, it is preferable that the control means is configured to control the switching means so that the potential states of the plurality of power storage means are equal to each other.

With this configuration, it is possible to appropriately control the transfer of charges between the plurality of power storage means. Further, in the present device, it is preferable that the control means is configured to set the predetermined cycle based on a resistance value and an electric capacity of the capacitor, and more preferably, the predetermined cycle includes: The time constant determined by the product of the resistance value and the electric capacity of the capacitor is set to be approximately 1 Z3 or less.

With this configuration, it is possible to efficiently balance the voltage in accordance with the specifications and performance of the power storage means and the power storage, and further, while reliably suppressing the energy loss due to the switching operation, There is also an advantage that the time required for balancing can be reduced.

Preferably, the power storage means is a storage battery, and a plurality of the storage batteries are connected in series and configured as an assembled battery used for an electric vehicle power supply. BRIEF DESCRIPTION OF THE FIGURES

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

FIG. 2 is a circuit diagram corresponding to FIG. 1 for describing the operation of the power storage device according to the first embodiment of the present invention, and is a diagram illustrating an operation mode different from FIG.

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

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

FIG. 5 is a graph showing characteristics of a battery in the power storage device according to the first embodiment of the present invention.

FIG. 6 shows a main configuration of a power storage device according to a second embodiment of the present invention. FIG.

FIG. 7 is a circuit diagram illustrating a main configuration of a power storage device according to a third embodiment of the present invention.

FIG. 8 is a circuit diagram corresponding to FIG. 7 for describing the operation of the power storage device according to the third embodiment of the present invention, and is a diagram illustrating an operation mode different from FIG. .

FIG. 9 is a diagram showing charge / discharge characteristics of a general capacitor (capacitor) in a power storage device as a third embodiment of the present invention.

FIG. 10 is a diagram showing a result of simulating the relationship between the voltage balancing time of the storage battery and the switching frequency of the switch in the power storage device according to the third embodiment of the present invention. FIG. 9 is a diagram illustrating a voltage balancing time when the electric capacity of the battery is changed while the resistance is fixed.

FIG. 11 is a diagram showing a result of simulating the relationship between the voltage balancing time of the storage battery and the switching frequency of the switch in the power storage device according to the third embodiment of the present invention. FIG. 9 is a diagram illustrating a voltage balancing time when the resistance of the battery is changed while the electric capacity is fixed.

FIG. 12 is a schematic circuit diagram showing a conventional power storage device. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 to FIG. 5 show a power storage device as a first embodiment of the present invention, and FIG. Fig. 7 shows a power storage device as a second embodiment, and Figs. 7 to 11 show power storage devices as one embodiment of the present invention.

First, the circuit configuration of the first embodiment will be described. As shown in FIG. 1 and FIG. 2, the present power storage device includes a plurality of power storage devices. Ponds (secondary batteries, also referred to as batteries or battery cells) 1 to 5 are configured as assembled batteries connected in series. In this example, as an example in which a plurality of batteries are connected in series, an example in which five batteries are connected is shown, but the number of batteries is not limited to this.

Further, there are provided a plurality of capacitors (capacitors) C1 to C5 which can be connected in parallel with the plurality of power storage means 1 to 5, respectively, and which are connected in series with each other.

Further, switches S1 to S5 as connection switching means are interposed between the respective storage batteries C1 to C5 and the corresponding storage batteries 1 to 5, respectively. Cell of storage battery 1 on one end (terminal A side) and the other end

Switches S 0 and S 6 as connection switching means are provided in a connecting portion 8 that connects the cells of the storage battery 5 (terminal B side) in a ring shape.

That is, the terminals S 1 B and S 2 A are applied between the storage batteries 1 and 2 ^ the terminals S 2 B and S 3 A are provided between the storage batteries 2 and 3, and the terminals are provided between the storage batteries 3 and 4. Terminals S 4 B and S 5 A are connected between storage batteries 4 and 5, respectively, and terminals S 0 B and S 4 A are connected between one end of the assembled battery and storage battery 1. 1 A, terminals S 5 B and S 6 A are connected between the other end of the assembled battery and the storage battery 5, respectively, and a terminal S 6 B is connected to one end of the capacitor C 1 and a capacitor C The terminal SOA is connected to the end of the capacitor C 5 on the side of the capacitor C 5, respectively, and the switch S 1 that can selectively switch between the terminals S 1 A and S 1 B is connected to one end of the capacitor C 1. The switch S2, which can selectively connect and switch the terminal S2A and the terminal S2B, is provided between the capacitor C1 and the capacitor C2, and the switch S2 between the capacitor C2 and the capacitor C3. Terminal S 3 A and terminal S 3 B Switch S3 switch that can be connected and disconnected Switch S4 switch that can selectively switch terminal S4A and terminal S4B between the capacitors C3 and C4 Terminal S 5 on the capacitor C 5 side A switch S5 is provided to selectively switch connection between A and the terminal S5B <, and a terminal SOA and a terminal S0B are provided at one end of the capacitor C5 (side of the capacitor C4). A switch S 6 for selectively switching connection between a terminal S 6 A and a terminal S 6 B is provided on the other end of the switch S 0, which can be selectively switched.

These switches SO to S6 are configured to be switched in an interlocked manner, each of which is connected to the terminals S0A to S6A (the first connection mode KM1) and each of the terminals S0A to S6A. It is configured to be able to simultaneously and synchronously switch between the state connected to 0B to S6B (the second connection mode M2).

In the first connection mode M1, the capacitors C1, C2, C3, C4, and C5 are connected in parallel with the corresponding storage batteries 1, 2, 3, 4, and 5, respectively. In the second connection mode M 2, each of the capacitors C 1, C 2, C 3, C 4, C 5 and the storage batteries 2, 3, 4, 5, 1 adjacent to the corresponding storage batteries 1 to 5 Each is connected in parallel.

Further, control means 7 for controlling switching between the first connection mode M1 and the second connection mode M2 by the connection switching means S0 to S6 is provided. It is configured to make the potential difference of each of the storage batteries 1 to 5 equal while repeating the mode switching in a required cycle by the control signal.

In this embodiment, the connection switching means is constituted by the switches S0 to S6. However, in an actual circuit configuration, in consideration of controllability and durability, non-contact switching means such as a transistor is used. It is conceivable to configure with.

Further, the power storage device of the present embodiment is applicable to an assembled battery (= battery formed by connecting a plurality of storage batteries) used as a power supply for an electric vehicle. About 30 batteries in series A power storage device using a connected battery pack can be naturally applied to such a battery pack composed of a large number of batteries.

Since the power storage device as the first embodiment of the present invention is configured as described above, the following operation is performed.

First, a charging voltage is applied between terminals A and B, and storage batteries 1 to 5 are charged.

Then, the switches S0 to S6 are interlocked and switched by the control signal from the control means 7, and the connection state to the terminals S0A to S6A and the connection state to the terminals S0B to S6B are changed. Are switched simultaneously.

As a result, the first connection mode M 1 in which each of the capacitors C 1, C 2, C 3, C 4, and C 5 is connected in parallel with each of the corresponding storage batteries 1, 2, 3, 4, and 5, The second connection module KM 2 connected in parallel with the storage batteries 2, 3, 4, 5, 5 and 1 adjacent to the storage batteries 1 to 5 corresponding to the storage capacitors CI, C2, C3, C4, and C5 is selected. Is switched.

The switching between the first connection mode M1 and the second connection mode KM2 by the connection switching means SO to S6 is repeated at a required cycle by the control signal from the control means 7. As a result, the potential difference between the storage batteries 1 to 5 gradually equalizes.

Here, the control operation for equalizing the potential difference between the storage batteries 1 to 5 described above will be described focusing on the operation between the battery 1 and the battery 2.

First, assume that the voltage of battery 1 is V 1 and the voltage of battery 2 is V 2 (V 1> V 2).

As shown in FI G. 3, when the switches S l and S 2 are swung to the left and connected to the terminals S 1 A and S 2 A, respectively, and the capacitor C 1 and the battery 1 are connected in parallel, The voltage of battery 1 and the potential difference of the capacitor are each V. This v is smaller than the current flowing from battery 1 to the capacitor than V 1. The voltage (= V 1 — ν) is lower (= V 1 — ν) according to the load (small amount) V

Next, as shown in FIG. 4, when the switches S 1 and S 2 are swung to the right and connected to the terminals S 1 B and S 2 B, the capacitor C 1 and the battery 2 are connected in parallel. Then, the voltage of the battery 2 and the potential difference of the capacitor become V 2 ′, respectively. This V 2 ′ is a voltage (= V 2 + v ₂ ) higher than V 2 by the charge (small amount) V ₂ flowing into the capacitor from the battery 2.

In this way, charge is transferred from battery 1 to battery 2 via capacitor C1, and the voltage of battery 1 gradually decreases from V1, and the voltage of battery 2 gradually increases from V2, and eventually. The voltages of battery 1 and battery 2 have the same value V12 (V1> V12> V2).

Here, the storage batteries 1 to 5 are formed of, for example, lithium batteries, and the voltage is determined depending on the discharge amount as in the characteristics of the lithium batteries shown in FIG. Conversely, it can be said that the battery voltage is determined depending on the charged amount (charged amount). Therefore, the state of a desired discharge amount, that is, a charged amount (charged amount) is adjusted by such voltage balancing.

In the case of a battery with flat characteristics where the voltage is not uniquely determined with respect to the discharge amount, such as the characteristics of the nickel-metal hydride battery (nickel battery) shown in Fig. 5, the discharge amount (charge Amount that does not reach the desired state Force In the case where the voltage is uniquely determined with respect to the amount of discharge as in the above lithium battery, the amount of discharge (the amount of charge) of each battery in the assembled battery is equalized to the desired state Thus, the performance of such a battery (for example, a lithium battery) can be fully utilized.

As described above, the operation of balancing the amount of charge (charging rate) by voltage balancing is performed for each of the storage batteries 1 to 5.

As described above, in this device, the electric charge is transferred through the capacitors C1 to C5 to balance the voltages of the batteries 1 to 5, so that a large heat generating element is generated. Does not exist, and balancing is achieved in a state where energy loss due to heat generation is avoided.

In addition, the equilibrium operation can be performed in all states, not only during charging until the battery is fully charged, but also during driving, charging, discharging, etc. Even when the battery is not used, the balancing operation can be performed. Of course, it can also be used for hybrid electric vehicles that do not charge until they are fully charged during power generation.

By the way, when such a circuit is actually applied, it is necessary to ensure that the operation is efficient, the operation is reliable, and the durability is high. Considering these specific conditions, the switches S 0 to S 6 A switching element such as a power element (FET or IGBT) with the smallest possible switching loss is used for the control means 7 and a circuit for automatically switching the switches S0 to S6 by an external oscillation circuit or the like. It is preferable to equip it.

If capacitors C1 to C5 are relatively large capacitors, for example, an electric double layer capacitor, the voltage can be quickly balanced.For example, such voltage control is always or frequently performed. In this case, even if a small-capacity capacitor is used, the amount of charge can be balanced by the voltage balance sufficiently for practical use.

In addition, a circuit to prevent inrush current to the capacitors C1 to C5 and an initial charging circuit are considered necessary.

In addition to the continuous operation of switching the switches S0 to S6, the control means 7 is provided with a maintenance switch used when performing maintenance, or driven when an external voltage measurement circuit or the like requires it. Method, driving when the vehicle is not in use, driving at regular intervals using a timer circuit, etc., controlling the connected electric load, etc. (For electric vehicles, use a motor controller or a residual capacity meter. Etc.) Various combinations such as a method of driving in the case of being conceived are conceivable. The present power storage device can also be applied to a battery pack in which a capacitor (capacitor) is used instead of a battery as the power storage means. In other words, application to a battery pack consisting of a plurality of series-connected capacitors (capacitors) instead of a battery pack consisting of a plurality of series-connected batteries (batteries) may be considered.

If a battery or electric double-layer capacitor, etc., in which various problems due to variations in cell voltage are likely to become noticeable when in the assembled battery state or the assembled battery state, the above-described structure is adopted, and a voltage balancing circuit is configured, This makes it possible to realize a system that can always balance the voltage without generating a large energy loss.

The operation of this circuit is not always performed, and it is possible to realize a method of balancing the voltage at any required time by using a battery cell voltage monitor, etc.In particular, by applying this circuit to a lithium ion battery, the ability of after having pulled out 1 0 0 Pas one cents of the lithium-ion battery, ensure safety mosquito readily ⁷ by.

The time required for voltage balancing can be shortened by changing the connection mode switching speed by the control means in accordance with the transition from when the cell voltage imbalance is large to small. Next, a power storage device according to a second embodiment of the present invention will be described. As shown in FIG. 6, storage batteries (batteries) 11 and 12 as a plurality of power storage means are connected in series. Constitutes an assembled battery. Although this example shows an example in which two batteries are connected, the number of batteries is not limited to this, as in the first embodiment. A plurality of capacitors (capacitors) C11 and C12 are provided that can be connected in parallel to the respective power storage means 11 and 12. Further, switches S11 to S14 as connection switching means are interposed between each of the storage batteries CI1, CI2 and each of the storage batteries 11, 12.

Here, between the storage batteries 11 and 12, terminals S11B, S12A, S12C, S13A, S13C and S14B power, ', storage battery 1 One end (terminal A side) of terminal 1 has terminals S11A, S11C and S13B, and the other end (terminal B side) of storage battery 12 has terminals S12B, S14A and S14C are connected respectively.

As shown in FIG. 6, between the terminal A side of the storage battery 11 and the terminal S 11 C, a resistor R 11 having a desired resistance value is connected. A resistor R12 having a desired resistance value is connected between the terminal B side of the terminal 12 and the terminal S14C.

A switch S 11 1 which can be selectively connected to terminal S 11 A, terminal S 11 B or terminal S 11 C at one end of the capacitor C 11 is also provided. at the other end to the terminal S 1 2 a, terminal S 1 2 B or terminal S 1 2 C selectively connected switchable switch S 1 2 further _c are provided, one end of the capacitor C 1 2 The switch S13 which can be selectively connected to terminal S13A, terminal S13B or terminal S13C on the other side, and terminal S1 on the other end of the capacitor C12 A switch S14 that can selectively switch connection to 4A, terminal S14B or terminal S14C is provided.

These switches S11 to S14 are configured to be switched in an interlocked manner, and are connected to the terminals S11A to S14A, respectively (first connection mode M1). And a state in which each is connected to terminals S11B to S14B (second connection mode M2), and a state in which each is connected to terminals S11C to S14C (third connection mode). The connection mode M3) can be switched simultaneously and synchronously. In the first connection mode KM 1, the respective capacitors C 11 and C 12 are connected in parallel with the corresponding storage batteries 11 1 and 12, and in the second connection mode KM 2, capacitor C 1 1, C 1 2 Chikaraku, corresponding storage battery 1 1, 1 2 battery 1 2 adjacent to, 1 1 _c also becomes a state of being connected in parallel, respectively, in the third connection mode M 3, Each of the capacitors C 11 and C 12 is powerfully connected to the storage batteries 11 and 12 in parallel via the resistors R ll and R 12, respectively.

Control means 17 is provided for controlling switching of the first connection mode KM1, the second connection mode KM2, and the third connection mode KM3 by the connection switching means S11 to S14. According to the control signal from the control means 17, the mode switching is repeatedly performed in the required switching state, and the potential difference between the storage batteries 11 and 12 is made equal.

In the present embodiment, the connection switching means is constituted by mechanical switches S11 to S14. However, in an actual circuit configuration, when controllability and durability are taken into consideration, a semiconductor such as a transistor is used. It is conceivable to use semiconductor switching means (semiconductor switch) using elements.

By the way, the reason why the resistors R11 and R12 and the terminals S11 to S14C are provided as in the present embodiment is as follows.

In other words, the capacitors C 11 and C 12 have the function of storing electric charges in the same manner as the storage batteries 11 and 12, but normally, unlike a battery, a capacitor is relatively self-discharging. Notable. Therefore, when the electric storage device as described above is mounted on an electric vehicle and the vehicle is left unattended for a long time, the electric storage devices C11 and C12 may have no charge. In this case, even if the key switch of the vehicle is turned off (that is, the identification switch is turned off), if the switches S11 to S14 are held in the first connection mode KM1 or the second connection mode KM2. The capacitors C 1 1 and C 1 2 are connected to terminal S 1 1 A to S 14 A or the terminals S 11 C to S 14 C are connected to the storage batteries 11 and 12, so that the capacitors C 11 and C 12 are completely discharged. It is unlikely that you will be charged.

However, if a semiconductor switch such as a transistor is used instead of a mechanical switch for the connection switching means, when the switch is turned off, each of the switches S 11 to S 14 may be connected to any terminal depending on the characteristics of the semiconductor switch. It is in a state where it does not come into contact with it, and it promotes self-discharge.

Then, in a state where the capacitors C 11 and C 12 do not store the electric charge (that is, the discharged state), the circuit is started (when the ignition is turned on) or the terminal is charged for charging. If a charger is connected between A and B), the resistors R11 and R12 will not be provided, and the capacitors C11 and C12 will suddenly have a large current (such a large current Inrush current), which may damage the capacitors C11 and C12.

Therefore, in the present embodiment, in order to avoid such an inrush current, the storage batteries C 11 and C 12 are connected to the storage battery 1 via the resistors R 11 and R 12 in comparison with the above-described first embodiment. A third connection mode KM 3 is provided to connect with 1, 1 and 2.

In the state where the capacitors C 11 and C 12 are storing electric charges (that is, in a charged state), since the capacitors C 11 and C 12 themselves act as resistors, such inrush occurs. current and _c does not flow to the capacitor C 1 1, C 1 2, in the present embodiment, when starting the circuit (e.g., Iguni' to Nkion or when the terminal a, the voltage for charging between B is applied ), The switches S11 to S14 are interlocked by the control signal from the control means 17 so as to be connected to the terminals S11C to S14C. — Can be switched to de M3.

In addition, the capacitors C 11 and C 12 are connected via the resistors R 11 and R 12 in this manner. Connected to the storage batteries 11 and 12 and the charger to prevent the surge current from flowing through the storage capacitors C 11 and C 12 even when the storage capacitors C 11 and C 12 are in the discharging state. It is possible to charge the capacitors C 11 and C 12 while avoiding them.

Then, after a lapse of a predetermined time until the capacitors C11 and C12 are charged, the switches S11 to S14 are switched to the first connection mode M1 and the second connection mode M2. The switching is controlled alternately.

The power storage device according to the second embodiment can be applied to a battery pack (= a battery formed by connecting a plurality of storage batteries) used as a power supply for an electric vehicle, as in the first embodiment. In the current electric vehicle, an assembled battery in which about 20 to 30 batteries are connected in series is generally used, but the present power storage device is naturally applied to an assembled battery including such a large number of batteries. sell.

Since the power storage device according to the second embodiment of the present invention is configured as described above, the following operation is performed.

First, when the power is turned on, that is, when the circuit is started (for example, when the ignition key is turned on or when a charging voltage is applied between the terminals A and B to the storage batteries 11 and 12), the switches S11 to S11 are switched on. S 14 is interlocked and switched by the control signal from the control means 17 and is controlled by the third connection mode KM 3 _c . In this case, each switch S 11 to S 14 is connected to a terminal S 1 1 (: Connected to S 14 C, connected to storage batteries 1 1, 1 2 via capacitors C 11, C 12 force ^ resistors R ll, R 12 respectively And

As a result, even when each of the capacitors C 11 and C 12 has no charge at all, the batteries C 1 and C 12 store large amounts of power from the batteries 11 and 12 and the charger at power-on and charging. No current (rush current) flows, and the capacitors C 11 C 12 can be sufficiently protected.

Then, after a lapse of a predetermined time, it is determined that the capacitors C 11 and C 12 have been sufficiently charged, and the switches S 11 to S 14 are switched in response to a control signal from the control means 17. The connection state to the terminals S11A to S14A and the connection state to the terminals S11B to S14B are simultaneously switched.

Thereby, the first connection mode KM 1 connected in parallel with each of the storage batteries 11 1 and 12 corresponding to each of the capacitors C 11 and C 12, and the storage battery 1 corresponding to each of the capacitors C 11 and C 1 2 The storage batteries 12 and 11 adjacent to 1 and 12 and the second connection mode KM 2 connected in parallel with each other are selectively switched. The switching between the first connection mode M 1 and the second connection mode KM 2 by the switches S 11 to S 14 as such connection switching means is controlled by the control means 17. The repetition at a required period by the signal causes the potential difference between the storage batteries 11 and 12 to be gradually equalized. Note that the control operation for equalizing the potential difference between the storage batteries 11 and 12 is the same as that in the above-described first embodiment, and will not be described here.

As described above, in the power storage device of the second embodiment, the following effects can be obtained in addition to the effects and advantages of the above-described first embodiment.

That is, when starting the circuit while the capacitors C 11 and C 12 do not store electric charge (ie, in a discharged state) (for example, when the ignition is turned on, or when the terminal A is charged for charging). , B), the current flows through the capacitors C 11 and C 12 through the resistors R 11 and R 12, so that the capacitors C 11 and C 12 This has the advantage that it is possible to prevent a large current (rush current) from flowing suddenly and to sufficiently protect the capacitors C 11 and C 12.

Further, according to the present embodiment, such a rush current can be prevented. Since the specifications for the withstand current of the capacitors C 11 and C 12 can be minimized, a small-capacity capacitor can be used, and the capacitors C 11 and C 12 can be downsized. There are advantages.

Next, a power storage device according to a third embodiment of the present invention will be described. As shown in FIGS. 7 and 8, this device also includes a plurality of storage batteries (batteries) 11 and 1 and 2 are connected in series, thereby forming an assembled battery. In the present embodiment, the circuit configuration is the same as that of the second embodiment (see FIG. 6) except that the terminals S11 (: to S14C and the resistors Rll and R12) are omitted. For this reason, the detailed description of the circuit configuration is omitted, and FIGS. 7 and 8 show examples in which two batteries are connected. The number is not limited to this.

In the present embodiment, since the terminals S 11 C to S 14 C and the resistors R 11 and R 12 are omitted, the connection mode corresponding to the third connection mode KM 3 in the second embodiment is And the first connection mode KM 1 connected in parallel with each of the storage batteries 11 1 and 12 corresponding to each of the capacitors C 11 and C 12, and the storage battery corresponding to each of the capacitors C ll and C 12 A storage battery 12, 11 adjacent to 11, 12 is provided with a second connection mode KM 2 connected in parallel with each of the storage batteries 12, 11.

Then, according to the control signal from the control means 17, the connection state of the switches S11 to S14 was connected to the terminals S11A, S12A, S13A, S14A, respectively. The state (first connection mode Ml) and the state (second connection mode M2) connected to terminals SI1B, S12B, S13B, and S14B, respectively. It is configured so that the potential difference between the storage batteries 11 and 12 is made equal while repeating the switching between.

By the way, the capacitor (storage device) connected to the storage batteries 1 1 and 1 2 C 1 1 Specification of C12 ゃ The voltage balancing time greatly changes depending on the switching frequency of the switches S11 to S14. For this reason, setting the switching frequency of switches S11 to S14 is important in order to balance the voltages of the storage batteries 11 and 12 and to bring out the performance of batteries 11 and 12 sufficiently. .

On the other hand, Fig. 9 is a graph showing the charge and discharge characteristics of a general capacitor (capacitor). As can be seen from this graph, the capacitor has a charge at the start of charging or discharging due to its characteristics. Change (charge / discharge rate) is relatively large, and the rate of change of charge becomes gradual over time. Therefore, when the change of charge (charge / discharge rate) is large, the switches S11 to S14 are switched. The more the switching is performed, the shorter the balancing time can be. That is, the shorter the switching period of the switches S11 to S14, the more efficiently the storage batteries 11 and 12 can be balanced.

However, energy loss always occurs when the switches S11 to S14 operate, so if the switching cycle is too short, this energy loss increases, and conversely, the efficiency may decrease.

Therefore, it is necessary to set the switching cycle (switching frequency) so that the voltages of the storage batteries 11 and 12 can be balanced in a short time while minimizing the energy loss due to the switches S11 to S14. is there.

Here, FIG. 10 and FIG. 11 are the results of simulating the relationship between the voltage balancing time of the storage batteries 11 and 12 and the switching frequency of the switches S11 to S14. Fig. 10 shows the voltage balancing time when the resistance of the capacitor (capacitor) is fixed and the capacitance of the capacitor is changed. Fig. 11 is the capacitor (capacitor). FIG. 4 is a diagram showing a voltage balancing time when the capacitance of the capacitor is fixed and the resistance of the condenser is changed.

The simulation results shown in Fig. 10 and Fig. 11 are used. As can be seen, if the switching frequency of switches S11 to S14 is set to approximately 1Z3 or less, which is the time constant (resistance X capacitance) of the capacitor, the balance will be maintained regardless of the capacitance or resistance value of the capacitor. Change time hardly changes. Therefore, it is effective to set the switching frequency near the time constant of the capacitor (resistance X capacitance) of about 1 Z3.

Therefore, in the present embodiment, the switching frequency of the switches S 11 to S 14 by the control means 17 is determined by the time constant obtained by the product of the resistance value R of the capacitors C 11 and C 12 and the electric capacity C. It is set to 1 Z 3. Note that the switching frequency is not limited to 1/3 of the time constant of the capacitors C11 and C12, but may be, for example, approximately 1/3 or less of the time constant of the capacitors C11 and C12. It only has to be set. However, if the switching frequency is too high, the energy loss due to the switches S11 to S14 increases as described above, so that the time constant is preferably about 1/3.

In the present embodiment, the connection switching means is constituted by mechanical switches S11 to S14. However, in an actual circuit configuration, when controllability and durability are taken into consideration, a semiconductor such as a transistor is used. It is conceivable to use semiconductor switching means (semiconductor switch) using elements. In this case, the energy loss due to the switching operation can be smaller than that of a mechanical switch.

Further, similarly to the first embodiment, the power storage device of the present embodiment can be applied to an assembled battery (= a battery formed by connecting a plurality of storage batteries) used as a power supply for an electric vehicle. In the current electric vehicle, an assembled battery in which about 20 to 30 batteries are connected in series is generally used, but the present power storage device is naturally applied to an assembled battery including such a large number of batteries. The power storage device according to the third embodiment of the present invention is configured as described above, and thus performs the following operation. First, when the power is turned on, that is, when the ignition key is turned on, or when a voltage for charging is applied between the terminals B of the storage batteries 11 and 12, the switches Sll to S14 are controlled by the control means 17. Switching is performed in conjunction with the signal, and the connection status to terminals S11A to S14A and the connection status to terminals S11B to S14B are alternately and simultaneously switched.

Thereby, the first connection mode KM 1 connected in parallel with each of the storage batteries 11 1 and 12 corresponding to each of the capacitors C 11 and C 12, and the storage battery 1 corresponding to each of the capacitors C 11 and C 1 2 The storage batteries 12 and 11 connected to 1 and 12 and the second connection mode M 2 connected in parallel with each other are selectively switched. The switching between the first connection mode M 1 and the second connection mode KM 2 by the switches S 11 to S 14 as such connection switching means is performed by the control means 17. The potential difference between the storage batteries 11 and 12 is gradually equalized by being repeatedly performed in a required cycle by the control signal. In this device, the switching frequency of the switches S11 to S1 at this time is set based on the time constant obtained by the product of the resistance value R of the capacitors C11 and C12 and the capacitance C. This has the advantage that the voltage balancing time can be reduced while reducing the energy loss due to the switching operation. In particular, in the present embodiment, the switching frequency is set to approximately one third of the time constant obtained by multiplying the resistance value R of the capacitors C 11 and C 12 by the electric capacitance, and thus the switching operation is performed. Therefore, there is an advantage that the voltage balancing time can be extremely effectively reduced while preventing energy loss due to the above. Industrial applicability

According to the power storage device of the present invention, by transferring the charge of the high-voltage storage battery (power storage means) to the low-voltage storage battery, it is possible to eliminate the voltage variation among the plurality of storage batteries and equalize the voltage of the storage batteries. Can, among multiple batteries Since the voltage level of storage batteries with relatively low voltage can be increased, it is easy to secure the output of the batteries even in the case of a battery pack in which many batteries are connected in series, and each battery can be used equally. It is possible to maximize the capacity of each storage battery. Therefore, if this device is applied to, for example, an assembled battery used as a power supply for an electric vehicle, the practicality of the electric vehicle can be greatly improved, and it is extremely useful.

Claims

The scope of the claims

1. A plurality of power storage means (1 to 5, 11, 12, 12) connected in series and the same number of capacitors (C1 to C5) as the plurality of power storage means (1 to 5, 11, 12, 12) , C 1 1, C 1 2)

For each of the plurality of power storage means (1 to 5, 11, 12, 12), the plurality of power storage units (C1 to C5, C11, C12) should be one-to-one. Switching means (S 0 to S 6, S ll, S 12) which can be connected in parallel to each other and switch the combination of the parallel connection;

The combination of the parallel connection of the respective storage means (1 to 5, 11, 12) to each of the storage devices is sequentially switched to the adjacent storage means (2 to 5, 1, 12, 11) at a predetermined cycle. Control means (7, 17) for controlling the switching means (S0 to S6, S11, S12) as described above.

2. As the connection mode by the switching means (S0 to S6, S11, S12), each of the plurality of capacitors (C1 to C5, C11, C12) The first connection mode in which the plurality of storage means (1 to 5, 11, 12, 12) are connected in parallel to the above, and the first connection mode, in which the plurality of storage means (C1 to C5, C11, C12) The power storage means (2 to 5, 1, 12, 12) adjacent to the power storage means (1 to 5, 11, 12, 12) connected in the first connection mode are connected in parallel to each of them. With a second connection mode,

The control means (7, 17) controls the switching means (S0 to S6, S11, S11) so as to alternately switch between the first connection mode and the second connection mode at a predetermined cycle. Claim 1 characterized by controlling 1 2)

3. One terminal is connected to the plurality of power storage means (11, 12), and the other terminal is connected to the switching means (S11, S12). (11, 12) and the same number of resistors (R11, R12) are further provided.

As the connection mode by the switching means (S11, S12), the plurality of power storage means (C11, C12) are respectively connected to the plurality of power storage means (C11, C12).

(1 1, 1 2) in parallel in the first connection mode, and power storage means connected to each of the plurality of capacitors (C 11, C 12) in the first connection mode. A second connection mode in which power storage means (12, 11) adjacent to (11, 12) are connected in parallel, and a plurality of power storage means (CI1, C12) for each of the plurality of power storage devices (CI1, C12). Power storage means (11, 12) connected in the first connection mode or the power storage means connected in the second connection mode via the respective resistors (R11, R12). (1 2, 1 1) in parallel with each other, and a third connection mode,

The control means (17) performs the connection in the third connection mode first, and then switches the first connection mode and the second connection mode alternately. The power storage device according to claim 1, wherein (S11, S12) is controlled.

4. The control means (7, 17) controls the switching means (S0 to S6, S1) so that the potential states of the plurality of power storage means (1 to 5, 11, 12, 12) become equal to each other. Claim 1, characterized by controlling (S1, S2).

5. The control means (7, 17) sets the predetermined period to the storage capacitor (C1 The power storage device according to claim 1, wherein the power storage device is set based on resistance values and electric capacitances of C5, Cll, and C12).

6. The control means (7, 17) sets the predetermined period as an abbreviation of a time constant obtained by multiplying a resistance value and an electric capacity of the capacitors (C1 to C5, Cll, C12). The power storage device according to claim 5, wherein the power storage device is set so as to be 1/3 or less.

7. The power storage means (1 to 5, 11, 12) is a storage battery, and a plurality of the storage batteries are connected in series to constitute a battery pack used for a power supply for an electric vehicle. The power storage device according to claim 1, characterized in that: