The present invention relates to a storage battery system, a storage battery monitoring device, and a storage battery monitoring method.
A storage battery system using a chargeable secondary cell is used as a power source for moving vehicles such as electric vehicles (EV) and electric forklifts or a stationary power source for a power storage device. In the storage battery system, a plurality of electrically-connected cell are generally used.
In charging/discharging each of the plurality of electrically-connected cell with same electric power, when the cells have different characteristics (for example, a charging capacity), some of the cells may be overcharged or overdischarged.
In this connection, Japanese patent publication JP2003-217534A (patent literature 1) describes a technique of providing a cell pack in which each of single cells is charged in an optimum state even when the cells have different initial states and cell performances to improve the life and reliability of the cells. The patent literature 1 discloses the cell pack having a plurality of chargeable single cells, a charging control circuits of the same number as the single cells and a plurality of switch circuits enabled to connect the plurality of single cells in series during discharging and enabled to individually connect each of the plurality of single cell to each of the charging control circuits during charging.
In a storage battery system mounted on vehicles such as EV, a plurality of cells may be replaced by a user. In replacement, all of the plurality of cells may be replaced at one time or only some of the plurality of cells may be replaced.
In replacing some of the plurality of cells, when newly-mounted cells have characteristics that are identical to characteristics of remained unreplaced cells, there is no problem. However, when the new cells have characteristics that are different from the characteristics of the remained cells, some cells may be overcharged or overdischarged as described above. It is difficult for a user to identify whether or not the characteristics of the newly-mounted cells match characteristics of the other cells before the replacement.
Therefore, an object of the present invention is to provide a storage battery system, a storage battery monitoring device and a storage battery monitoring method, which can identify whether or not a cell can be mounted on the storage battery system.
A storage battery system according to the present invention includes: a plurality of secondary cell pack installed in a moving vehicle; an information storage part which is attached to each of the plurality of secondary cell pack and stores cell information concerning the each secondary cell back; and a monitoring device configured to determine whether or not the secondary cell packs can be mounted on the storage battery system or determine whether or not a combination of the plurality of secondary cell pack is appropriate, based on the cell information stored in the information storage part.
According to the present invention, since the monitoring device determines whether or not a specification of a secondary cell pack to be newly attached is appropriate, use of a wrong secondary cell pack is prevented. Since the monitoring device determines whether or not the combination of the plurality of secondary cell pack is appropriate, use of the secondary cell packs having different characteristics in combination is prevented. As a result, occurrence of the overcharged or overdischarged secondary cell pack is prevented.
The storage battery system according to the present invention includes a storage part for storing system standard information that represents a specification range of a mountable secondary cell pack. The information storage part stores specification information that represents a specification of each of the secondary cell packs as the cell information. At this time, it is preferred that the monitoring device compares specifications of the plurality of secondary cell pack with the system standard information to determine whether or not the each secondary cell pack can be mounted.
It is preferred that the specification information includes information on at least one of an appropriate voltage range (maximum charging voltage, minimum discharging voltage), an appropriate current range (maximum charging current, maximum discharging current), a capacity range, an input/output range, a temperature range and a resistance value range.
The storage battery system according to the present invention may further include a current state detection part provided in the each secondary cell pack, and the current state detection part detects a current state of the each secondary cell pack. At this time, cell information may include current information representing the current state of the each secondary cell pack. The current state detection part stores the detected current state in the information storage part as the current information. At this time, it is preferred that the monitoring device determines whether or not the secondary cell packs can be mounted by comparing the current states of the plurality of secondary cell pack with each other based on the current information.
It is preferred that the current information includes information on at least one of a current charging capacity, a current internal resistance and a number of charge/discharge cycles of the each secondary cell pack.
It is preferred that the monitoring device is connected between both ends of the whole of the plurality of secondary cell pack, and acquires the cell information from the information storage part through a closed circuit that is formed of the monitoring device and the plurality of secondary cell pack.
The storage battery system according to the present invention may further include a wireless part attached to the each secondary cell pack, and the wireless part wirelessly transmits the cell information stored in the information storage part to the monitoring device. At this time, it is preferred that the monitoring device includes a wireless receiving part configured to wirelessly receive the transmitted cell information.
A storage battery monitoring device according to the present invention includes: a cell information acquisition part configured to acquire the cell information about each of a plurality of secondary cell pack from the plurality of secondary cell pack; and a cell determination part configured to determine whether or not the secondary cell pack can be mounted based on the acquired cell information.
A secondary cell pack according to the present invention is a secondary cell pack mounted on a moving vehicle or a power storage device. The secondary cell pack includes: at least one single cell; and an information storage part storing cell information about the single cell. The cell information is transmitted to a monitoring device provided in a storage battery system when the secondary cell pack is attached to the storage battery system.
A storage battery monitoring method according to the present invention includes: acquiring cell information on each of a plurality of secondary cell pack from the plurality of secondary cell pack; and determining whether or not the secondary cell packs can be mounted by determining whether or not a combination of the plurality of secondary cell pack is appropriate based on the acquired cell information.
It is preferred that the cell information includes current information representing a current state of the each secondary cell pack, and the determining includes determining whether or not the secondary cell packs can be mounted by comparing the current states of the plurality of secondary cell pack with each other based on the current information.
According to the present invention, the storage battery system, the storage battery monitoring device and the storage battery monitoring method are provided, which can identify whether or not each of the single cells in the storage battery system is available.
Referring to drawings, embodiments of the present invention will be described.
As shown in
Each of the secondary cell packs 1 has at least one chargeable/dischargeable single cell 10. For example, a lithium-ion cell is used as the single cell 10. Each secondary cell pack 1 is defined as a minimum unit that can be replaced. In the example shown in
In the each secondary cell pack, an IC memory 4 (information storage part) and a current state detection part 5 are provided.
The IC memory 4 stores cell information that is information concerning the each secondary cell pack 1.
When the each secondary cell packs 1 is attached to the storage battery system, the IC memory 4 is connected to the closed circuit 3. The IC memory 4 transmits the cell information to the BMU 2 through the closed circuit 3, when receiving a read signal through the closed circuit 3.
The specification information is information representing a specification of the each secondary cell pack 1. Specifically, as shown in
The current information shown in
The current state detection part 5 detects a current state of the single cell 10, for example periodically, and writes the detection result to the IC memory 4 as the current information. The current state detection part 5 also counts a number of charging/discharging times of the single cell 10, and stores the counted number in the IC memory 4 as the number of cycles.
A method of detecting the current state by the current state detection part 5 is not specifically limited.
For example, the “current charging capacity” and the “current internal resistance value” can be detected by utilizing a fact that a voltage of the single cell 10 depends on a charging capacity. In this case, the current state detection part 5 may include a voltage sensor for measuring the voltage of the single cell 10, and a voltage-charging capacity storage part for previously storing a correspondence relationship between the voltage and the charging capacity. The current charging capacity can be detected by referring to the voltage-charging capacity storage part based on a voltage value of the single cell 10 that is actually measured by the voltage sensor.
Alternatively, the “current charging capacity” can be detected by summing current values. In this case, the current state detection part 5 may include an ammeter for measuring a current flowing through the single cell 10.
For example, the current internal resistance value can be detected by providing an ammeter and a voltmeter for respectively measuring a current value and a voltage value of the single cell 10.
For example, the highest operating temperature up to the present time and the lowest operating temperature up to the present time can be detected, by providing a thermometer for measuring the temperature of the single cell 10.
The total operating time can be measured by attaching a timer device having a timer function to the single cell 10.
A method of counting the number of cycles is not specifically limited, and the number of cycles may be counted, for example, based on change in the charging capacity.
Subsequently, the BMU 2 will be described.
The storage part 25 is exemplified by a hard disc or the like. The system standard information stored in the storage part 25 indicates a specification range of a mountable secondary cell pack (hereinafter referred to as appropriate specification range). The appropriate specification range represents at least one of a charging voltage range, a discharging voltage range, a charging current range, a discharging current range, a capacity range, an input/output range, a temperature range and a resistance value range.
The storage part 25 only needs to be provided in the storage battery system and need not be provided in the BMU.
The cell information acquisition part 23 is connected to the closed circuit 3, and transmits the read signal to the IC memory 4 provided in the each secondary cell pack 1 via the closed circuit 3, for example, when the secondary cell pack 1 at a certain position is replaced. Then, when the cell information is transmitted from the IC memory 4 in response to the read signal, the cell information acquisition part 23 receives the cell information through the closed circuit 3 and stores the information in the RAM 24 or the like.
The ROM 22 stores a cell identification program for identifying the secondary cell pack 1 as a computer program. The each secondary cell pack 1 is identified by the CPU 21 executing the cell identification program.
The cell information acquired by the cell information acquisition part 23 is compared with the system standard information by the cell information identification program. Specifically, the specification information of the each secondary cell pack 1 (refer to
By the determination mentioned above, the secondary cell packs having different specifications can be prevented from being combined.
For example, in a case where the secondary cell packs 1 having different “maximum charging voltages” are included in the plurality of secondary cell pack 1, when the plurality of secondary cell pack 1 are charged on the basis of the secondary cell pack 1 having a higher “maximum charging voltage”, the secondary cell pack 1 having a lower “maximum charging voltage” is overcharged.
Further, in a case where the secondary cell packs 1 having different “minimum discharging voltages” are included, when the plurality of secondary cell pack 1 are discharged on the basis of the secondary cell pack 1 having a lower “minimum discharging voltage”, the secondary cell pack 1 having a higher “minimum discharging voltage” is overdischarged.
Further, in a case where the secondary cell packs 1 having different “maximum discharging current” are included, the magnitude of a current value during discharging must be conformed with the secondary cell pack 1 having a smaller “maximum discharging current”. Accordingly, characteristics of the secondary cell pack 1 having a larger “maximum discharging current” cannot be sufficiently derived.
Further, in a case where the secondary cell packs 1 having different “maximum charging current” are included, the magnitude of a current value during charging must be conformed with the secondary cell pack 1 having a smaller “maximum charging current”. Accordingly, characteristics of the secondary cell pack 1 having a larger “maximum charging current” cannot be sufficiently derived.
Further, in a case where the secondary cell packs 1 having different “capacity ranges” are included, when the secondary cell pack 1 having a larger “capacity range” is completely charged, the secondary cell pack 1 having a smaller “capacity range” is overcharged.
Further, in a case where the secondary cell packs 1 having different “resistance value ranges” are included, the voltages of the secondary cell packs 1 cannot be made uniform, resulting in that the secondary cell packs 1 cannot be charged such that the voltages of all of the secondary cell packs 1 have the same value.
On the other hand, according to the present embodiment, when the appropriate specification range specified in the system standard information is smaller than the specification range of the cell in any secondary cell pack 1, it is determined that the secondary cell pack is unavailable. Accordingly, even when only one cell that is out of the appropriate specification range specified in the system standard information is mounted, the system does not operate, and failure is prevented.
Even when all of the secondary cell packs 1 have the appropriate specifications, the cell information identification program compares the current information of the plurality of secondary cell pack 1 with each other. When a difference between the current states of the plurality of secondary cell pack 1 is within a predetermined range, it is determined that the combination of the plurality of secondary cell pack 1 is appropriate. On the contrary, when the difference between the current states of the plurality of secondary cell pack 1 is out the predetermined range, it is determined that the combination of the plurality of secondary cell pack 1 is inappropriate. Specifically, it is determined whether or not a difference between the plurality of secondary cell pack 1 is within a predetermined range, about at least one of the “current charging capacity”, the “current internal resistance value”, the “highest operating temperature up to the present time”, the “lowest operating temperature up to the present time”, the “actual use time” and the “number of cycles”.
When determining that the combination of the plurality of secondary cell pack 1 is inappropriate, the cell information identification program activates an alarm device (not shown) such as an audio alarm or a display device to inform the user of the unavailable combination. Alternatively, the storage battery system is controlled so as not to be operated, by a blocking device (not shown).
According to the present embodiment, the BMU 2 determines whether or not the specifications of the plurality of secondary cell pack 1 are appropriate. Whereby, it is determined whether or not the attached secondary cell packs 1 can be available. Thus, it is possible to prevent the user from wrongly using the secondary cell packs having different specifications in combination.
The secondary cell may be deteriorated by repeats of charging/discharging. Even when the secondary cell packs 1 have the same specification, different deterioration states may cause different charging capacities and internal resistance values. When the secondary cell packs 1 having different charging capacities and internal resistance values are mounted, the single cell 10 may be overcharged/overdischarged during charging/discharging.
On the other hand, according to the present embodiment, the current states of the plurality of secondary cell pack 1 are compared with each other, and when the secondary cell packs having different current states are combined, it is determined as unavailable. Thus, it is prevented that the secondary cell packs 1 having different deterioration states are used in combination. As a result, overcharging/overdischarging of the secondary cell pack during charging or discharging can be prevented more reliably.
In the present embodiment, the case has been described, where the current state detection part 5 is provided in the each secondary cell pack 1. However, the current state detection part 5 is not necessarily provided in the each secondary cell packs 1, and may be provided in a main body of the storage battery system. In this case, the current state detection part 5 may be arranged so as to be able to detect the current state of the each secondary cell pack 1 when the each secondary cell pack 1 is attached to the storage battery system. By employing such a configuration, the same effects as those described in the present embodiment can be achieved.
Further, in the present embodiment, the case has been described, where the cell information is transmitted to the BMU 2 through the closed circuit 3 that is formed of the plurality of secondary cell pack 1 and the BMU 2. However, the cell information is not necessarily transmitted to the BMU 2 through the closed circuit 3.
For example, a communication line that is separate from the closed circuit 3 may be provided in the storage battery system, and the IC memory 4 may be connected to the BMU 2 with the communication line when the each secondary cell pack 1 is attached to the storage battery system. At this time, the cell information is transmitted to the BMU 2 through the communication line. By employing such a configuration, the same effects as those described in the present embodiment can be achieved.
Further, in the IC memory 4 provided in the each secondary cell pack 1, address information may be included, which represents where the each secondary cell pack 1 is attached in the storage battery system. When the address information is included, the cell information identification program can identify which secondary cell packs 1 is unavailable, based on the address information. In addition, it can be possible to inform the user which of the unavailable secondary cell pack 1 is unavailable.
As a configuration where the address information is stored in the IC memory 4, for example, a writing part for writing the address information may be provided in the main body of the storage battery system. The writing part is configured so as to write the address information to the IC memory 4 wirelessly or by wire when the each secondary cell pack 1 is attached.
Subsequently, a second embodiment of the present invention will be described.
As shown in
A wireless part 6-2 is provided in the secondary cell pack 1-2. The wireless part 6-2 is connected to the IC memory 4-2 and transmits the cell information stored in the IC memory 4-2 to the BMU 2 by a wireless signal. On the other hand, in the BMU 2, the cell information acquisition part 23 is configured so as to receive the cell information transmitted from the wireless part 6-2.
Since the cell information is transmitted to the BMU 2 by the wireless signal, even when the secondary cell pack 1-2 is not attached to the storage battery system, the user can identify whether or not the secondary cell pack 1-2 is available. For example, in a case of the storage battery system mounted on the EV, merely by placing the secondary cell pack 1 near the vehicle, the user can identify whether or not the secondary cell pack 1 is available.
Subsequently, a third embodiment will be described.
As shown in
The wireless part 74 wirelessly communicates with the wireless part 6 provided in the each secondary cell pack 1. The wireless part 74 receives the cell information of the each secondary cell pack 1 from the wireless part 6 by a wireless signal and stores the cell information in the RAM 73.
The diagnosis program diagnoses an optimum cell replacement time and an optimum replaced cell specification, based on the cell information acquired by the wireless part 74.
For example, the cell replacement time can be decided based on the current information included in the cell information. In a more specific example, how many times the single cell 10 provided in the each secondary cell packs 1 can be further charged and discharged is calculated, based on an upper limit of the number of cycles which is previously stored in the RAM 73 or the like, and the cell replacement time is calculated based on the calculated number of times.
For example, when a secondary cell pack 1 to be replaced is designated, the replaced cell specification can be decided based on the cell information of the remained secondary cell packs 1. For example, it is assumed that the wireless part 74 acquires a “maximum charging voltage”, a “minimum charging voltage”, a “maximum charging current”, an “internal resistance”, a “current charging capacity”, a “current internal resistance value” and an “number of cycles” as the cell information, from the each secondary cell pack 1. The diagnosis program 72 calculates an average value in each of the items for the secondary cell packs 1 remained in the storage battery system, and decides the calculated average value as the replaced cell specification.
The diagnosis result of the diagnosis program is outputted by an output device not shown (for example, a display device) and informed to the user.
According to the present embodiment, the cell replacement time representing a remaining life of the each secondary cell packs 1 is informed to the user. The user can prepare a new secondary cell pack 1 by referring to the cell replacement time. Further, by informing the replaced cell specification to the user, the user can prepare the secondary cell pack 1 having an optimum specification so as to be suited for the combination of the plurality of secondary cell pack 1.
In the present embodiment, the case has been described where the diagnosis device 7 is prepared separately from the BMU 2. However, the diagnosis program may be stored in the ROM 22 in the BMU 2 so that the BMU 2 diagnoses the cell replacement time and the replaced cell specification. In this case, the BMU 2 functions as the diagnosis device 7.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2008/062914 | 7/17/2008 | WO | 00 | 3/16/2011 |