JP2014068467A - Charge control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To charge an assembled battery efficiently and suppress a deterioration thereof.SOLUTION: An assembled battery has a series circuit of a plurality of cells. As to each cell, a relationship between an internal resistance value and an SOC (State Of Charge) is measured and an SOC that locally maximizes the internal resistance value is detected as a peak SOC (SOC[1], SOC[2]). An SOC range including each peak SOC is set as a peak SOC range, and when the assembled battery is charged, a current rate (I) in the peak SOC range is made lower than a current rate (I) in an SOC range on a lower SOC side of the peak SOC range and a current rate (I) in an SOC range on a higher SOC side of the peak SOC range.

Description

  The present invention relates to a charge control device.

  FIG. 15 shows an example of the relationship between the SOC (State Of Charge) and the internal resistance value of a storage battery such as a lithium ion battery. In a storage battery such as a lithium ion battery, the internal resistance value often decreases as the SOC, which is a charging rate, basically increases. However, the current transmission mechanism in the storage battery changes in a medium SOC range. Before and after the change, ions in the storage battery may not move easily, and the internal resistance value may locally increase. The SOC corresponding to this local increase and taking the maximum value in the internal resistance value of the storage battery is called peak SOC (peak charge rate). Based on the idea that if a relatively large charging current is applied with a large internal resistance value, deterioration of the storage battery will be promoted due to the influence of heat generation, etc., the internal resistance value of the assembled battery is measured sequentially during charging. A method of suppressing the charging current when the resistance value is high has been proposed (see Patent Document 1 below).

JP-A-9-84277

  When a relatively large charging current is applied in the SOC range where the peak SOC exists, deterioration of the storage battery is promoted. However, in the low SOC range, even if the internal resistance value is high, ions (lithium ions, etc.) in the storage battery are solid. Deterioration is unlikely to proceed even when a relatively large charging current is passed due to reasons such as difficulty in precipitation. In the method of performing charging current suppression control by paying attention only to the internal resistance value of the assembled battery, the charging current may be suppressed more than necessary, and efficient charging is hindered. Excessive suppression of the charging current is not preferable because it increases the time required for charging. Considering the relationship between the internal resistance value and the SOC, suppressing the charging current at a truly necessary timing (for example, the timing corresponding to the above peak SOC) is considered to be important for achieving both efficient charging and suppression of deterioration. It is done.

  Then, an object of this invention is to provide the charge control apparatus which contributes to efficiency improvement of the assembled battery which consists of a some storage battery, and suppression of the deterioration accompanying charging.

  The charge control device according to the present invention derives a storage battery charge rate that is a charge rate of each of a plurality of storage batteries connected in series forming an assembled battery, or an assembled battery charge rate that is a charge rate of the entire assembled battery. Based on the first data according to the storage battery charge rate dependency of the storage battery resistance value, which is the internal resistance value of each storage battery, the storage battery resistance value increases with the increase of the storage battery charge rate for each storage battery. The storage battery charging rate when turning from increasing to decreasing is detected as a peak charging rate, or based on the second data corresponding to the assembled battery charging rate dependency of the assembled battery resistance value which is the internal resistance value of the entire assembled battery The battery pack charging rate when the battery pack resistance value changes from increasing to decreasing as the battery pack charging rate increases is detected as the peak battery charging rate, and each peak charging rate is included and the lower limit is less than zero. Big pea A setting unit configured to set a charging rate range; and a control unit configured to control charging of the assembled battery, wherein the control unit is configured such that the assembled battery charging rate or a storage battery charging rate of any storage battery is within the peak charging rate range. At the timing belonging to, the charging current rate of the assembled battery is made lower than other timings.

  Another charge control device according to the present invention provides a storage battery charge rate that is a charge rate of each of a plurality of series-connected storage batteries that form an assembled battery, or an assembled battery charge rate that is a charge rate of the entire assembled battery. A charging rate deriving unit for deriving, and a measuring unit for measuring an assembled battery resistance value that is an internal resistance value of the entire assembled battery or each storage battery resistance value that is an internal resistance value of each storage battery during a charging period of the assembled battery; The reference resistance value is set based on the first data corresponding to the storage battery charging rate dependency of the storage battery resistance value of each storage battery or the second data corresponding to the assembled battery charging rate dependency of the assembled battery resistance value. And a control unit for controlling charging of the assembled battery, wherein the control unit is measured by the measuring unit when the assembled battery charging rate or any of the storage battery charging rates is equal to or greater than a predetermined value. The battery resistance value or any battery resistance value is In greater timing than the reference resistance value, the charge current rate of the battery pack, is lower than the other timing.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the charge control apparatus which contributes to efficiency improvement of the assembled battery which consists of a some storage battery, and suppression of the deterioration accompanying charging.

It is a figure which shows the assembled battery and several voltage sensor which concern on 1st Embodiment of this invention. 1 is an overall configuration diagram of a power storage system according to a first embodiment of the present invention. It is a figure which shows the example of a relationship between internal resistance value and SOC regarding one cell. It is a figure which shows the resistance characteristic measurement part in connection with an electrical storage system. It is a figure which shows the time relationship between the period for a measurement, and a charge period. It is a figure which shows the example of SOC dependence of the internal resistance value of each cell, and SOC dependence of the internal resistance value of an assembled battery. It is a figure which shows the example of a setting of the 1st-3rd SOC range according to the SOC dependence of the internal resistance value of each cell, and the SOC dependence of the internal resistance value of an assembled battery. It is a figure which concerns on 1st Embodiment of this invention and shows the example of the electric current pattern of charging. It is a figure which concerns on 1st Embodiment of this invention and shows the other example of the electric current pattern of charging. It is a figure which shows the function part which can be provided in a control unit. It is a figure which concerns on 2nd Embodiment of this invention and shows the detail of a charging period. It is an internal block diagram of the control unit which concerns on 3rd Embodiment of this invention. It is a figure which concerns on 3rd Embodiment of this invention and shows the 1st example of the reference resistance value and the electric current pattern of charge. It is a figure which concerns on 3rd Embodiment of this invention and shows the 2nd example of the reference resistance value and the electric current pattern of charge. It is a figure which concerns on a prior art and is a figure which shows the example of a relationship between SOC of a storage battery, and internal resistance value.

  Hereinafter, an example of an embodiment of the present invention will be specifically described with reference to the drawings. In each of the drawings to be referred to, the same part is denoted by the same reference numeral, and redundant description regarding the same part is omitted in principle. In this specification, for simplification of description, a symbol or reference that refers to information, signal, physical quantity, state quantity, member, or the like is written to indicate information, signal, physical quantity, state quantity or Names of members and the like may be omitted or abbreviated.

<< First Embodiment >>
A first embodiment of the present invention will be described. FIG. 1 shows an assembled battery 11 _TT and a plurality of voltage sensors 13 according to the first embodiment of the present invention. The assembled battery 11 _TT has n storage batteries 11 connected in series with each other. n is an arbitrary integer of 2 or more. The assembled battery 11 _TT may further include a storage battery other than the series circuit of the n storage batteries 11. Each storage battery 11 is an arbitrary type of storage battery (secondary battery), for example, a lithium ion battery or a nickel metal hydride battery. Although each storage battery 11 may be formed by combining a plurality of cells, which are the minimum unit of the storage battery, hereinafter, the storage battery 11 is referred to as a cell 11 on the assumption that the storage battery 11 is composed of one cell. In this specification, the discharge and charge, unless otherwise described, refers to a discharge and charge of the cell 11 or the assembled battery 11 _TT. The plurality of voltage sensors 13 measure the terminal voltage of each cell 11.

FIG. 2 is an overall configuration diagram of the power storage system 1 according to the first embodiment of the present invention. The power storage system 1 includes each part shown in FIG. In the following, when n cells 11 need to be distinguished from each other as shown in FIG. 2, the n cells 11 are referred to as cells 11 [1] to 11 [n]. A voltage sensor 13 is connected to each of the cells 11 [1] to 11 [n]. The voltage sensor 13 [i], which is the voltage sensor 13 connected to the cell 11 [i], measures the terminal voltage of the cell 11 [i] and outputs a signal representing the measured voltage value. i is an arbitrary integer. The terminal voltage and the voltage value of the cell 11 [i] are represented by the symbol V [i]. A current flowing through the cell 11 [i] (hereinafter also referred to as a cell current) and its current value are represented by a symbol I [i]. The current flowing through the entire assembled battery 11 _TT (hereinafter also referred to as an assembled battery current) and its current value are represented by the symbol I _TT . Since the cells 11 [1] to 11 [n] are connected to each other in series, I _TT = I [i].

A current sensor 14 for measuring the assembled battery current is connected to the assembled battery 11 _TT , and the current sensor 14 outputs a signal representing the measured current value I _TT . The control unit 30 determines the terminal voltage value (V [1] to V [n]) and current value I of each cell 11 from the output signals of the voltage sensors 13 [1] to 13 [n] and the output signal of the current sensor 14. Recognize _TT . However, during constant current charging, the main control unit 33 in the control unit 30 can specify the current value I _TT by controlling the power conversion circuit 16, so that the control unit 30 outputs the current sensor 14. The current value I _TT can be recognized without depending on the signal. It is assumed that the polarity of the current flowing in the direction from the positive electrode to the negative electrode of the cell 11 [i] is positive.

The charging source 15 is an arbitrary power source that can supply charging power to the assembled battery 11 _TT . For example, the power that generates power based on natural energy (solar, hydro, wind, geothermal, etc.) and outputs the generated power. Or a commercial AC power source (or a power system connected to the commercial AC power source). The power conversion circuit 16 performs power conversion (DC / DC conversion or AC / DC conversion) on the charging power supplied from the charging source 15 under the control of the main control unit 33, and uses the obtained DC power. It supplies to assembled battery _11TT as charging electric power. The assembled battery 11 _TT can also supply discharge power to an arbitrary load (not shown) via the power conversion circuit 16, but in the following, unless otherwise specified, operations related to charging of the assembled battery 11 _TT and The configuration will be described.

The control unit 30 provided in the power storage system 1 includes each part referred to by reference numerals 31 to 34. The data holding unit 31 stores data indicating the relationship between the internal resistance value of the cell 11 and the charging rate of the cell 11, that is, the charging rate dependency of the internal resistance value of the cell 11 (hereinafter also referred to as resistance characteristic data). Hold every. The resistance characteristic data for the cell 11 [i] is represented by the symbol R _CR [i]. The charging rate of the cell 11 is expressed as SOC (State Of Charge) of the cell 11. The SOC of the cell 11 [i] is represented by the symbol SOC [i]. As is well known, SOC [i] is the ratio of the remaining capacity of the cell 11 [i] to the full charge capacity of the cell 11 [i].

FIG. 3 shows an example of the resistance characteristic data R _CR [i]. The resistance characteristic data R _CR [i] indicates the relationship between the internal resistance value of the cell 11 [i] and the SOC [i]. The internal resistance value of the cell 11 [i] is represented by the symbol R [i]. The resistance characteristic measurement unit 40 (see FIG. 4A) provided inside or outside the power storage system 1 can acquire the resistance characteristic data R _CR [i] in a predetermined measurement period 310. As shown in FIG. 5, the measurement period 310 is before the charging period 320 described later. The measurement period 310 may be a period provided at the time of designing, manufacturing, or shipping the power storage system 1, the control unit 30, the assembled battery 11 _TT, or the cell 11. In this case, as shown in FIG. 4B, the resistance characteristic measuring unit 40 may be an experimental device provided outside the power storage system 1 (however, the resistance characteristic measuring unit 40 may be connected to the power storage system 1 or the control). It can also be provided in the unit 30). The measurement period 310 may be a period provided after manufacture and shipment of the power storage system 1, the control unit 30, the assembled battery 11 _TT, or the cell 11. In this case, as shown in FIG. 4C, the resistance characteristic measuring unit 40 is provided in the control unit 30.

In the measurement period 310, the resistance characteristic measurement unit 40 changes the cell current value I [i] from the first current value (for example, zero) to the first value in a state where the SOC [i] of the cell 11 [i] is set to the predetermined evaluation SOC. A first step of obtaining the terminal voltage fluctuation amount ΔV [i] of the cell 11 [i] before and after the fluctuation from the output signal of the voltage sensor 13 [i], and a terminal voltage fluctuation amount ΔV. By dividing [i] by the variation ΔI [i] of the cell current value I [i] (that is, the difference between the first and second current values), the internal resistance value R [ i] is calculated (that is, R [i] = ΔV [i] / ΔI [i]). The internal resistance value R [i] corresponding to one evaluation SOC is obtained by executing the first and second process groups one time. In the measurement period 310, the resistance characteristic measurement unit 40 repeatedly executes the first and second steps while sequentially changing the evaluation SOC (for example, while changing the evaluation SOC in increments of 1%), whereby the resistance characteristic data R _CR [i] can be obtained. The resistance characteristic measurement unit 40 obtains the resistance characteristic data R _CR [1] to R _CR [n] by performing the above-described processing on each of the cells 11 [1] to 11 [n]. The data holding unit 31 holds the obtained resistance characteristic data R _CR [1] to R _CR [n].

In a storage battery such as a lithium ion battery, the internal resistance value generally decreases as the SOC increases. However, the current transmission mechanism in the storage battery changes in the medium SOC range, and before and after the change. The ions in the storage battery may be difficult to move and the internal resistance value may locally increase. A storage battery having such characteristics is assumed as the cell 11 [i]. In fact, the internal resistance value of the cell 11 [i] takes a maximum value in a region where the SOC is medium. The SOC that takes the maximum value in the internal resistance value of the cell 11 is called peak SOC (peak charge rate) (see FIG. 3). The peak SOC for the cell 11 [i] is represented by the symbol SOC _PK [i], and the internal resistance value R [i] when the SOC [i] matches the SOC _PK [i] is particularly called a peak resistance value. Together with the symbol R _PK [i]. In addition, although it is clear from the meaning of the term “maximum value”, regarding the cell 11 [i], the internal resistance value when the internal resistance value R [i] changes from increasing to decreasing with increasing SOC [i]. R [i] is a local maximum.

Data holding unit 31, instead of the resistance characteristic data _{R CR [1] ~R CR [} n], or, in addition to the resistance characteristic data _{R CR [1] ~R CR [} n], the resistance characteristic data R _CRTT You may hold | maintain (refer FIG. 2). The resistance characteristic data R _CRTT is data indicating the charging rate dependency of the internal resistance value in the entire assembled battery 11 _TT . Charging rate of the entire assembled battery 11 _TT is expressed as the assembled battery 11 _TT overall SOC (State Of Charge). The SOC of the entire assembled battery 11 _TT is represented by the symbol SOC _TT . As is well known, SOC _TT is the ratio of the assembled battery 11 _TT total remaining capacity to the full charge capacity of the entire battery pack 11 _TT.

FIG. 6 shows an example of the resistance characteristic data R _CRTT together with examples of the resistance characteristic data R _CR [1] and R _CR [2]. The internal resistance value of the entire assembled battery 11 _TT is represented by the symbol R _TT . Resistance characteristic data R _CRTT shows the relationship between the SOC _TT of the assembled battery 11 internal resistance value of _TT R _TT and the assembled battery 11 _TT. The internal resistance value R _TT is the sum of the internal resistance values R [1] to R [n]. The SOC _{TT of the} assembled battery 11 _TT is an average of SOC [1] to SOC [n]. Therefore, if the resistance characteristic data R _CR [1] to R _CR [n] is determined, the resistance characteristic data R _CRTT is determined.

Accordingly, the resistance characteristic measuring unit 40 (see FIG. 4A and the like) obtains the resistance characteristic data R _CR [1] to R _CR [n] as described above, and then the resistance characteristic data R _CR [1] to R Resistance characteristic data R _CRTT can be obtained from _CR [n]. If the data holding unit 31 resistance characteristic data _{R CR [1] ~R CR [} n] is maintained, the resistance characteristic data R _CR [1] by SOC range setting unit 32 described later resistor from to R _CR [n] The characteristic data R _CRTT may be derived.

Alternatively, the resistance characteristic measurement unit 40 may directly obtain the resistance characteristic data R _CRTT without _obtaining the resistance characteristic data R _CR [1] to R _CR [n]. In this case, an assembled battery voltage sensor (not shown) that measures the terminal voltage of the entire assembled battery 11 _TT and outputs a signal representing the measured voltage value may be connected to the assembled battery 11 _TT . The assembled battery voltage sensor may be formed by the voltage sensors 13 [1] to 13 [n]. In the measurement period 310, the resistance characteristic measurement unit 40 changes the current value I _TT from the first current value (for example, zero) to the second current value in a state where the SOC _TT is set to the predetermined evaluation SOC, and before and after the change. assembled battery 11 and the first step of obtaining the variation amount [Delta] V _TT of _TT of the terminal voltage from the output signal of the battery pack voltage sensor, variation of the variation amount [Delta] V _TT current value I _TT terminal voltage [Delta] I _TT (i.e., first And the second step of calculating the internal resistance value R _TT corresponding to the evaluation SOC (ie, R _TT = ΔV _TT / ΔI _TT ). . A set of first and second step by performing one time, the internal resistance value R _TT corresponding to one evaluation SOC is obtained. In the measurement period 310, the resistance characteristic measurement unit 40 repeatedly executes the first and second steps while sequentially changing the evaluation SOC (for example, changing the SOC _TT in increments of 1%), whereby the resistance characteristic data R _CRTT can be obtained.

Corresponding to the characteristic that the internal resistance value R [i] of the cell 11 [i] has a maximum value with respect to the change of the SOC [i], the internal resistance value _RTT of the assembled battery _11TT also changes to the SOC _TT . On the other hand, it has a maximum value. The SOC _TT that makes the internal resistance value R _TT maximum is also called peak SOC (peak charge rate). In this embodiment, as shown in FIG. 6, when SOC _TT matches SOC _PK [1], the internal resistance value R _TT takes a maximum value R _PKTT [1], and SOC _TT becomes SOC _PK [1]. the internal resistance value R _TT when consistent with 2] is assumed to take a maximum value R _PKTT [2]. As with the maximum value of the internal resistance value R [i], the maximum value of the internal resistance value R _TT also called peak resistance value. Although it is clear from the meaning of the term "maximum value", the internal resistance value R _TT when the internal resistance value R _TT with increasing SOC _TT turns from increase to decrease is maximum value.

A method of causing the data holding unit 31 to hold at least the resistance characteristic data R _CR [1] to R _CR [n] is referred to as a first data holding method. When adopting the first data holding method, the control unit 30 recognizes the peak SOC and peak resistance value of each cell 11 in association with each cell 11 based on the data R _CR [1] to R _CR [n]. be able to. That is, when the first data holding method is adopted, the control unit 30 can recognize that SOC _PK [i] and R _PK [i] are the peak SOC and peak resistance value for the cell 11 [i].

A method of causing the data holding unit 31 to hold only the resistance characteristic data R _CRTT is referred to as a second data holding method. At the time of adopting the second data holding method, the control unit 30 can recognize that SOC _PK [1] and SOC _PK [2] are peak SOCs that cause the internal resistance value _RTT to be a maximum value, but the SOC _PK It cannot be recognized that [i] is the peak SOC for the cell 11 [i].

The SOC range setting unit (charge rate range setting unit) 32 is based on the resistance characteristic data R _CR [1] to R _CR [n] acquired from the data holding unit 31, and the peak SOC (that is, the cell 11) of each cell 11 (that is, Based on the detection operation for detecting the SOC of the cell 11 when the internal resistance value of the cell 11 changes from increasing to decreasing as the SOC of the cell 11 increases, or based on the resistance characteristic data R _CRTT acquired from the data holding unit 31 the assembled battery 11 _TT peak SOC (i.e., SOC of the assembled battery 11 _TT when the internal resistance of the battery pack 11 _TT with increasing SOC of the battery pack 11 _TT turns from increase to decrease) the detection operation of detecting I do.

The setting unit 32 sets the SOC range including each detected peak SOC as a peak SOC range (peak charge rate range) (see FIG. 7). At this time, the setting unit 32 specifies the maximum peak SOC as SOC _PKMAX among the plurality of peak SOCs detected by the detection operation, and specifies the minimum peak SOC as SOC _PKMIN. According to (2), SOC _ST which is the lower limit SOC of the peak SOC range and SOC _ED which is the upper limit SOC of the peak SOC range are determined (see FIG. 7). ΔSOC _A and ΔSOC _B have a predetermined value (for example, 10%) larger than 0, but SOC _ST is not set to 0% or less, and SOC _ED is not set to 100% or more. The coincidence or disagreement between ΔSOC _A and ΔSOC _B does not matter. In the following, it is _assumed that SOC _PKMIN = SOC _PK [1] and SOC _PKMAX = SOC _PK [2] unless otherwise _specified .
SOC _ST = SOC _PKMIN −ΔSOC _A (1)
SOC _ED = SOC _PKMAX + ΔSOC _B (2)

Further, the peak SOC range is referred to as a second SOC range for convenience. Then, it can be considered that the first to third SOC ranges are set by setting unit 32. The SOC range refers to a numerical range to which the SOC of the cell 11 or the assembled battery 11 _TT should belong. As shown in FIG. 7, the first to third SOC ranges do not overlap each other, and the SOC belonging to the second SOC range is always higher than the SOC belonging to the first SOC range and lower than the SOC belonging to the third SOC range. SOC _ST is a boundary value between the first and second SOC ranges, and SOC _ED is a boundary value between the second and third SOC ranges. The lower limit SOC of the first SOC range is 0%, but can be set to a predetermined value (for example, 5%) larger than 0%. The upper limit SOC of the third SOC range is a predetermined value SOC _CV (for example, 80%) less than 100%.

Based on the resistance characteristic data R _CR [1] to R _CR [n], the setting unit 32 sets the peak of the cell 11 from the range of the cell charge rate having a positive predetermined value (for example, 30%) or more for each cell 11. well if the SOC detection and extracts, or, on the basis of the resistance characteristic data R _CRTT, positive detection and extraction peaks SOC of the battery pack 11 _TT from the scope of the assembled battery charging rate with more than a predetermined value (e.g. 30%) Good. Thereby, the lower limit of the second SOC range (that is, SOC _ST ) can be made larger than 0% (for example, the lower limit of the second SOC range can be set to a positive predetermined value (for example, 20%) or more). The range of the cell charging rate indicates the SOC range of the cell 11, and the range of the assembled battery charging rate indicates the SOC range of the assembled battery _11TT .

The main control unit 33 of FIG. 2 sets the assembled battery 11 _TT of current patterns during the charging period 320 based on the detection and the setting result of the setting unit 32. In FIG. 8, a waveform 350 represents an example of a current pattern of the assembled battery 11 _TT during the charging period 320. In the charging period 320, when the SOC _TT belongs to the first, second, and third SOC ranges, the current pattern indicates that the assembled battery 11 _TT should be charged at the first, second, and third target current rates, respectively. 350 stipulates. Charging the assembled battery 11 _TT at the first, second, and third target current rates determines the assembled battery 11 _TT in a state where the current value I _TT matches the current values I _CC1 , I _CC2 , and I _CC3 , respectively. It refers to current charging. Here, “I _CC1 > I _CC2 ” and “I _CC2 <I _CC3 ”. That is, the second target current rate is lower than the first and third target current rates. In FIG. 8, “I _CC1 > I _CC3 ”, but “I _CC1 <I _CC3 ” or “I _CC1 = I _CC3 ” may be used.

In the charging period 320, the main control unit 33 adjusts the charging current of the assembled battery _{11TT to} the current defined in the set current pattern, in other words, the actual charging current rate matches the target current rate. The power conversion circuit 16 is controlled. The charging current rate refers to a charging current value of the assembled battery 11 _TT when performing constant current charging of the assembled battery 11 _TT during the charging period 320. For example, when the current pattern 350 is set, when the SOC _TT belongs to the first, second, and third SOC ranges during the charging period 320, the current value I _TT is the current value I _CC1 , I _CC2 , I _The battery pack 11 _TT is charged with constant current in a state consistent with _CC3 .

In the charging period 320, the assembled battery 11 _TT terminal voltage V _TT of reaches a predetermined voltage corresponding to SOC _CV, charging of the assembled battery 11 _TT is switched to the constant voltage charging from the constant current charging. State terminal voltage V _TT of the assembled battery 11 _TT reaches a predetermined voltage corresponding to SOC _CV corresponds to the state SOC _TT reaches a predetermined value SOC _CV. In FIG. 8, for the sake of convenience, a current change during constant voltage charging is shown in the current pattern 350 (a specific value of the current value I _TT during constant voltage charging is defined by the current pattern 350. Actually, in constant voltage charging, the specific value of the cell current is not controlled according to the current pattern 350 (the same applies to other current patterns described later).

The SOC calculation unit (charge rate deriving unit) 34 in FIG. 2 obtains SOCs of the cells 11 [1] to 11 [n], that is, SOC [1] to SOC [n]. The SOC calculation unit 34 uses the voltage sensor 13 [i] based on the voltage value V [i] measured by the voltage sensor 13 [i] for each of the cells 11 [1] to 11 [n]. Based on the measured voltage value V [i] and the current value I _TT measured by the current sensor 14, the SOC [i] at each time can be calculated according to any known SOC calculation method.

For example, before the start of the charging period 320, the SOC calculation unit 34 uses the voltage value V [i] in a state where no current is flowing in the cell 11 [i] as the open circuit voltage value of the cell 11 [i]. 13 [i], and using predetermined table data (known data indicating the relationship between the open circuit voltage value of the cell 11 and the SOC of the cell 11), the voltage value V [i] acquired as the open circuit voltage value is determined as the SOC. [I], and the SOC [i] obtained by this conversion is handled as the SOC of the cell 11 [i] at the start of the charging period 320. Thereafter, in the charging period 320, the SOC calculation unit 34 sequentially acquires the current value I _TT measured by the current sensor 14, and integrates the current value I _TT during an arbitrary integration target period to thereby calculate the integration target. The total amount ΣI of the charging current of the cell 11 [i] during the period is obtained, and from the total amount ΣI, the SOC of the cell 11 [i] at the start of the integration target period, and the full charge capacity of the cell 11 [i]. The SOC of the cell 11 [i] at the end of the integration target period can be obtained. Thereby, the SOC of the cell 11 [i] at an arbitrary time can be derived.

The main control unit 33 recognizes the SOC [i] calculated by the SOC calculation unit 34 as the SOC [i] at each time. The main control unit 33 can obtain the SOC _TT at each time from the SOC [1] to SOC [n] at each time. Alternatively, the SOC calculation unit 34 obtains the SOC _TT from the calculated SOC [1] to SOC [n], and obtains the SOC [1] to SOC [n] and SOC _TT , or only the SOC _TT, from the main control unit 33. You may make it send to. The main control unit 33 controls the charging current value at each time by controlling the power conversion circuit 16 based on the SOC [1] to SOC [n] or SOC _TT calculated at each time in the charging period 320. For example, the power conversion circuit 16 is controlled so that the charging current of the assembled battery 11 _TT becomes the current defined in the current pattern 350.

If a relatively large charging current is passed in a state where the internal resistance value is large, deterioration of the storage battery is promoted due to the influence of heat generation or the like. Therefore, it is preferable to suppress the charging current when the internal resistance value is large. However, in the low SOC range, even if the internal resistance value is high, ions (lithium ions, etc.) in the storage battery are not easily precipitated as solids. Deterioration is unlikely to progress even when charging current is passed. On the other hand, excessive suppression of the charging current increases the time required for charging. For this reason, a method of suppressing the charging current when the maximum value appears is examined. However, since the SOC of the maximum value appears is also sufficient to differ for each cell 11, to suppress the charging current for the entire battery pack 11 _TT focuses only on one cell 11 is not desirable. Considering this, the main control unit 33 sets the second SOC range (peak charge rate range) including each of the above-described peak SOCs, and determines the charge current rate when the SOC _TT belongs to the second SOC range as the SOC. The charging current rate is set lower than when _TT belongs to the first or third SOC range. As a result, when the charging current is increased, the charging current is suppressed in the middle SOC range where deterioration of the cell 11 is expected to be accelerated, and the deterioration of the entire assembled battery is suppressed. The charge current is relatively large in the low SOC range where there is no peak SOC and the deterioration does not easily progress even if the internal resistance value is high, so that the required charge time does not unnecessarily increase. In the conventional method in which the charging current is uniformly controlled based only on the internal resistance value of the entire assembled battery without considering the existence of the peak SOC (peak resistance value), the charging current may be excessively suppressed.

In the current pattern 350 of FIG. 8, the charging current rate when SOC _TT belongs to the second SOC range is constant (I _CC2 ), but it may be varied. With reference to FIG. 9, this method will be described under the assumption that “R _PKTT [1]> R _PKTT [2]” holds. Under this assumption, the setting unit 32 includes an SOC range 371 that includes the peak SOC (that is, SOC _PK [1]) of the assembled battery 11 _TT corresponding to the peak resistance value R _PKTT [1] and has a predetermined charging rate width. And an SOC range 372 including the peak SOC (that is, SOC _PK [2]) of the battery pack 11 _TT corresponding to the peak resistance value R _PKTT [2] and having a predetermined charging rate width, the second SOC range (peak Set within the charging rate range). Typically, for example, the center value of the SOC range 371 matches SOC _PK [1], and the center value of the SOC range 372 matches SOC _PK [2]. Here, it is assumed that SOC ranges 371 and 372 do not overlap each other as a result of SOC _PK [1] and SOC _PK [2] being sufficiently separated from each other. _{Corresponding to} SOC _PKMIN = SOC _PK [1] and SOC _PKMAX = SOC _PK [2], the lower limit of the SOC range 371 should match the SOC _ST, and the upper limit of the SOC range 372 should match the SOC _ED. .

A current pattern 360 in FIG. 9 represents an example of a current pattern of the assembled battery 11 _TT during the charging period 320 that can be set by the main control unit 33. When the current pattern 360 is set, when the SOC _TT belongs to the first and third SOC ranges during the charging period 320, the assembled battery is in a state where the current value I _TT matches the current values I _CC1 and I _CC3 , respectively. When the constant current charging of 11 _TT is performed and the SOC _TT belongs to the SOC ranges 371 and 372 during the charging period 320, the current value I _TT coincides with the current values I _CC2A and I _CC2B , respectively. Current value I _TT so that constant current charging of assembled battery 11 _TT is performed in the state and SOC _TT belongs to SOC range 373 between SOC range 371 and SOC range 372 during charging period 320 The main control unit 33 controls the power conversion circuit 16 so that constant current charging of the assembled battery 11 _TT is performed in a state where the current value “I _CC2A + k · (I _CC2B −I _CC2A )” matches. Here, “I _CC1 > I _CC2B > I _CC2A ” and “I _CC3 > I _CC2B > I _CC2A ”. The value of the coefficient k increases linearly from 0 to 1 as the SOC _TT moves from the upper limit of the SOC range 371 toward the lower limit of the SOC range 372.

Thus, when the peak resistance value R _PKTT [1] corresponding to the SOC range 371 is higher than the peak resistance value R _PKTT [2] corresponding to the SOC range 372, the SOC _TT belongs to the SOC range 371. The charging current rate (I _CC2A ) is set lower than the charging current rate (I _CC2B ) when SOC _TT belongs to the SOC range 372. Thereby, a charging current is further suppressed in a portion corresponding to a larger peak resistance value, and deterioration of the assembled battery is effectively suppressed.

In addition, at least one of the first data including the resistance characteristic data R _CR [1] to R _CR [n] and the second data as the resistance characteristic data R _CRTT is the assembled battery 11 using the main control unit 33. Before charging _TT , it is preferable to hold the data in the data holding unit 31 in advance.

Further, the control unit 30 may provide a plurality of measurement periods 310 (see FIG. 5) intermittently (for example, periodically) in time series. That is, the resistance characteristic measurement unit 40 performs the above-described operation for obtaining the resistance characteristic data R _CR [1] to R _CR [n] (operation for measuring the SOC dependency of the internal resistance value of the cell 11 for each cell 11). Alternatively, the above-described operation for obtaining the resistance characteristic data R _CRTT (operation for measuring the SOC dependency of the internal resistance value of the assembled battery 11 _TT ) may be repeated intermittently (for example, periodically). good. In this case, as shown in FIG. 10, a resistance characteristic measuring unit 40 and a data updating unit 41 may be provided in the control unit 30 in addition to the data holding unit 31. The data updating unit 41 holds the data holding unit 31 with the latest resistance characteristic data R _CR [1] to R _CR [n] obtained by the measurement of the resistance characteristic measuring unit 40 or the latest resistance characteristic data R _CRTT . The data R _CR [1] to R _CR [n] and R _CRTT held in the data holding unit 31 are updated to the latest data R _CR [1] to R _CR [n] and R _CRTT . Updated.) The setting unit 32 can set an arbitrary SOC range including the first to third SOC ranges using the latest retained data R _CR [1] to R _CR [n] and R _CRTT through this update. . While charging and discharging of the assembled battery 11 _TT are repeated, the charging period 320 is repeatedly provided on the time series. For example, on the time series, the first time before the first charging period 320 is the first time. The measurement period 310 can be provided, and then the second measurement period 310 can be provided between the jth charging period 320 and the (j + 1) th charging period 320 (j is a natural number). The SOC dependency of the internal resistance value of the cell 11 can change depending on the deterioration state of the cell 11 and the use environment of the assembled battery _11TT . As described above, when the resistance characteristic data is updated, the charge current rate control adapted to the change in the peak SOC accompanying the deterioration of the cell 11 or the like can be performed.

<< Second Embodiment >>
A second embodiment of the present invention will be described. The second embodiment and the third embodiment which will be described later are embodiments based on the first embodiment. Regarding matters not particularly described in the second and third embodiments, unless otherwise specified and there is no contradiction, The description of the first embodiment also applies to the second and third embodiments.

The second embodiment is based on the premise that the first data holding method is adopted among the first and second data holding methods described above. In the first embodiment, at the timing when the SOC of the assembled battery 11 _TT (that is, SOC _TT ) belongs to the second SOC range (peak charge rate range), the charging current rate is set lower than the other timings. In the embodiment, at the timing when the SOC of any cell 11 belongs to the second SOC range (peak charge rate range), the charging current rate is set lower than other timings.

As described above, when SOC _PKMIN = SOC _PK [1] and SOC _PKMAX = SOC _PK [2], SOC _ST and SOC _ED are set based on SOC _PK [1] and SOC _PK [2]. The main control unit 33 individually monitors the SOC [1] and SOC [2] calculated by the SOC calculation unit 34 in the charging period 320 including the periods 321 to 324 as shown in FIG. 323 so that the constant current charging of the assembled battery 11 _TT is performed in a state where the current value I _TT coincides with the current values I _CC1 , I _CC2 , and I _CC3 , and in the period 324, the assembled battery 11 _TT The power conversion circuit 16 is controlled so that constant voltage charging is performed.

As time progresses, periods 321, 322, 323, 324 come in this order. Period 321 is a period in which SOC [1], SOC [2], and SOC _TT do not reach the lower limit SOC _ST of the second SOC range. The main control unit 33 determines the start point of the period 322 based on the SOC of the cell 11 corresponding to SOC _PKMIN (= SOC _PK [1]) (and therefore SOC [1]), and SOC _PKMAX (= SOC _PK [2]). The end point of the period 322 is determined based on the SOC of the cell 11 corresponding to (accordingly, SOC [2]). Specifically, the period 322 is a period from the time when SOC [1] reaches SOC _ST until the time when SOC [2] increases and SOC [2] reaches the upper limit SOC _ED of the second SOC range. It is. The period 323 is a period until the terminal voltage V _TT of the assembled battery 11 _TT reaches a predetermined voltage corresponding to the SOC _CV after the SOC [2] reaches the SOC _ED . Here, it is assumed that the difference between SOC [1] and SOC [2] at each time is not so large that SOC [1] reaches SOC _ST before SOC [2] reaches SOC _ED (simply For example, SOC [1] = SOC [2]).

According to the second embodiment, the same effect as that of the first embodiment can be obtained. Further, the timing (period) for increasing or decreasing the charging current rate based on the SOCs of the cells 11 [1] and 11 [2] corresponding to the SOC _PK [1] and SOC _PK [2] that are the sources of the SOC _ST and SOC _ED. In order to determine the boundary timing between 321 and 322 and the boundary timing between periods 322 and 323), charging current suppression is optimized in cell units. This is because suppressing the charging current in the portion where the internal resistance value of the cell 11 [1] corresponding to the SOC _PK [1] that is the basis of the SOC _ST has the maximum value is to suppress the deterioration of the cell 11 [1]. It is suitable to suppress the charging current in the portion where the internal resistance value of the cell 11 [2] corresponding to the SOC _PK [2] that is the basis of the SOC _ED takes the maximum value. It is because is suitable for suppression, also is the source of the period 321 and SOC _ED until the SOC of the cell 11 [1] corresponding to the SOC _PK [1] which was the source of the SOC _ST reaches SOC _ST In the period 323 after the SOC of the cell 11 [2] corresponding to the SOC _PK [2] reaches the SOC _ED , the SOC of each cell 11 is not in the vicinity of each peak SOC, so it is necessary to suppress the charging current. This is because the nature is low.

In addition, when “R _PKTT [1]> R _PKTT [2]” is satisfied under the assumption described above in the second embodiment (see FIG. 6 and the like; that is, when SOC _TT matches SOC _PK [1]) the internal resistance value R _TT of the assembled battery 11 _TT is greater than R _TT when the SOC _TT matches the SOC _PK [2]), _{or, "R PK [1]>} R PK [2]" is When established (see FIG. 6 etc.), that is, when SOC [1] coincides with SOC _PK [1], the internal resistance value R [1] of the cell 11 [1] is SOC [2] is SOC _PK [2]. , The setting unit 32 sets the peak resistance value R _PKTT [1] or R _PK [1] to the peak resistance value R _PKTT [1], as shown in FIG. corresponding cells 11 [1] of the peak SOC (i.e. SOC _PK [1]) SOC range 371 and having a predetermined charging rate width comprises, Beauty, cell 11 [2] SOC range 372 and having a predetermined charging rate width comprises peaks SOC (i.e. SOC _PK [2]) that corresponds to the peak resistance value R _PKTT [2] or R _PK [2] It may be set within the second SOC range (peak charge rate range). The SOC ranges 371 and 372 are the same as those described in the first embodiment (see FIG. 9).

When “R _PKTT [1]> R _PKTT [2]” or “R _PK [1]> R _PK [2]” is satisfied, the main control unit 33 determines the SOC calculation unit in the period 322 of FIG. The charging current rate when the SOC [1] calculated in 34 belongs to the SOC range 371, and the charging current when the SOC [2] calculated in the SOC calculation unit 34 belongs to the SOC range 372 It may be lower than the rate. Specifically, for example, when SOC [1] belongs to the SOC range 371 during the period 322, the battery pack 11 _TT is charged with constant current while the current value I _TT matches the current value I _CC2A. In addition, when SOC [2] belongs to the SOC range 372 during the period 322, the battery pack 11 _TT is charged with constant current while the current value I _TT matches the current value I _CC2B . In addition, at other timings during the period 322, the battery pack 11 _TT is charged with constant current while the current value I _{TT matches the} current value “I _CC2A + k · (I _CC2B −I _CC2A )”. The main control unit 33 may control the power conversion circuit 16 (0 <k <1; see FIG. 9). However, here, it is assumed that the timing at which SOC [2] belongs to the SOC range 372 comes after the timing at which SOC [1] belongs to the SOC range 371, and the former timing and the latter timing do not overlap. .

Thus, the peak resistance values (R _PKTT [1], R _PK [1]) corresponding to the cell 11 [1] and the SOC range 371 are the peak resistance values (R _RKK [1], R _PK [1]) corresponding to the cell 11 [2] and the SOC range 372. _PKTT [2], R _PK [2]), the charge current rate (I _CC2A ) when the SOC of the cell 11 [1] belongs to the SOC range 371 is similar to the method of FIG. The charging current rate (I _CC2B ) when the SOC of the cell 11 [2] belongs to the SOC range 372 is set to be lower. Thereby, a charging current is further suppressed in a portion corresponding to a larger peak resistance value, and deterioration of the assembled battery is effectively suppressed.

<< Third Embodiment >>
A third embodiment of the present invention will be described. The power storage system 1 according to the third embodiment is provided with a control unit 30A shown in FIG. The control unit 30 </ b> A includes each part referred to by reference numerals 31, 34, 36 to 38. The configuration and function of the control unit 30 of the first or second embodiment may be included in the control unit 30A.

Prior to charging the assembled battery 11 _TT using the main control unit 38, the data holding unit 31 uses first resistance data R _CR [1] to R _CR [n] and resistance characteristic data R _CRTT. At least one of the second data is held in advance. The resistance characteristic measuring unit 40 and the data updating unit 41 of FIG. 10 may be provided in the control unit 30A, and the data held in the data holding unit 31 may be updated according to the method described in the first embodiment.

The reference resistance value setting unit 36 sets a predetermined reference resistance value R _REF . At this time, the setting unit 36 can set the reference resistance value R _REF based on the data held in the data holding unit 31. As a method for setting the reference resistance value R _REF based on the data held in the data holding unit 31, the first or second setting method can be adopted.
In the first setting method, the setting unit 36 is based on the resistance characteristic data R _CRTT acquired from the data holding unit 31, and the peak resistance value of the assembled battery 11 _TT including the peak resistance values R _PKTT [1] and R _PKTT [2]. And a reference resistance value R _REF1 based on the detected plurality of peak resistance values is set as the reference resistance value R _REF . For example, as shown in FIG. 13, a value obtained by subtracting a predetermined positive value from the minimum value among a plurality of detected peak resistance values can be set as the reference resistance value R _REF1 .
In the second setting method, the setting unit 36 calculates the peak resistance values R _PK [1] and R _PK [2] based on the resistance characteristic data R _CR [1] to R _CR [n] acquired from the data holding unit 31. The peak resistance value of each cell 11 that is included is detected, and the reference resistance value R _REF2 based on the detected plurality of peak resistance values is set as the reference resistance value R _REF . For example, as shown in FIG. 14, a value obtained by subtracting a predetermined positive value from the minimum value among a plurality of detected peak resistance values can be set as the reference resistance value R _REF2 .

The internal resistance value measurement unit 37 performs real-time measurement processing for measuring the internal resistance value of each cell 11 and the internal resistance value of the assembled battery 11 _TT during the charging period 320. Measurement unit 37, the real-time measurement processing, the internal resistance of the cell 11 [1] ~11 [n] only, or may be measured only the internal resistance of the battery pack 11 _TT. The measurement unit 37 repeatedly executes the real-time measurement process intermittently (for example, periodically) during the period in which the constant current charging is performed in the charging period 320. A known method can be used as a method of measuring the internal resistance value of the cell during execution of constant current charging.

For example, in the real-time measurement process, the current value I _TT in constant current charging is temporarily changed (decreased or increased) from the current value I _TT1 to the current value I _TT2 according to the set current pattern and the target current rate. A step PR1 for obtaining the fluctuation amount ΔV [i] of the terminal voltage of the cell 11 [i] before and after the fluctuation from the output signal of the voltage sensor 13 [i], and the fluctuation amount ΔV [i] obtained in the step PR1 are represented by the cell current. A step of calculating the internal resistance value R [i] of the cell 11 [i] by dividing by the variation amount ΔI [i] of the value I [i] (that is, the difference between the current values I _TT1 and I _TT2 ). And PR2 (ie, R [i] = ΔV [i] / ΔI [i]). By executing steps PR1 and PR2 for each cell 11, internal resistance values R [1] to R [n] can be obtained.

Measurement unit 37 can obtain the total value of the internal resistance value obtained at step PR2 R [1] ~R [n ] as the internal resistance value R _TT of the assembled battery 11 _TT. However, the internal resistance value _RTT may be obtained directly. In this case, a connecting battery pack voltage sensor described earlier (not shown) to the assembled battery 11 _TT. In the real-time measurement process, the measurement unit 37 changes (decreases or increases) the current value I _TT in constant current charging from the current value I _TT1 to the current value I _TT2, and the assembled battery 11 _TT before and after the change. get the variation amount [Delta] V _TT of the terminal voltage from the output signal of the battery pack voltage sensor, dividing the variation amount [Delta] V _TT at a current value I _TT variation amount [Delta] I _TT (i.e., the difference between the current value I _TT1 and I _TT2) by may be calculated internal resistance value R _TT of the assembled battery 11 _{TT (i.e., R TT = ΔV TT / ΔI} TT).

The internal resistance value obtained by the measurement unit 37 is particularly called a measurement resistance value. The function of the SOC calculation unit 34 in the control unit 30A is the same as that described above. The main control unit 38 sets the reference resistance value R _REF set by the setting unit 36, the measured resistance value from the measurement unit 37, and the calculated SOC (SOC [1] to SOC [n], SOC _TT ) by the calculation unit 34. Based on this, the charging of the assembled battery 11 _TT is controlled. The main control unit 38 can arbitrarily control the current value I _TT in constant current charging by controlling the power conversion circuit 16. The main control unit 38 may have a function equivalent to that of the main control unit 33 of the first or second embodiment. Hereinafter, functions unique to the main control unit 38 will be described.

When adopting the first setting method, the reference resistance value _REF1 that is set based on the peak resistance value of the assembled battery 11 _TT is set to the reference resistance R _REF. Thus, at the time of the adoption of the first setting method, the controller 38, the measured resistance value is compared with R _TT and the reference resistance value R _REF1, the charging current at larger time than the measured resistance value R _TT is the reference resistance value R _REF1 Reduce the rate. However, since there is little need to lower the charging current rate in the low SOC range, the main control unit 38 limits the SOC range in which the charging current rate is lowered.

When adopting the second setting method, the reference resistance value _REF2 is set to a reference resistance value R _REF, which is set based on the peak resistance value of each cell 11. Therefore, when adopting the second setting method, the main control unit 38 compares the measured resistance values R [1] to R [n] with the reference resistance value R _REF2 to measure the measured resistance values R [1] to R [n]. The charging current rate is lowered at a timing when any one of them is larger than the reference resistance value R _REF2 . However, since there is little need to lower the charging current rate in the low SOC range, the main control unit 38 limits the SOC range in which the charging current rate is lowered.

First, a specific flow of operation during the charging period 320 when the first setting method is adopted will be described. It is assumed that the SOC of the assembled battery 11 _TT is sufficiently low at the start of the charging period 320 (it may be considered to be 0%). The main control unit 38 can consider that the assembled battery 11 _TT and the SOC of each cell 11 at the start of the charging period 320 belong to the first SOC range, and at least immediately after the start of the charging period 320, “ The battery pack 11 _TT is _subjected to constant current charging (see FIG. 8) with I _TT = I _CC1 ″.

Thereafter, as shown in FIG. 13, the main control unit 38 determines that “I _TT = I regardless of the measured resistance value R _TT until the SOC _TT from the SOC calculation unit 34 reaches a predetermined threshold SOC _TH (for example, 30%). _After the constant current charging at _CC1 ″ is maintained and the SOC _TT becomes equal to or higher than the threshold SOC _TH , the reference resistance value R _REF1 is sequentially compared with the obtained measured resistance value R _TT (0 <SOC _TH <1). The main control unit 38 determines that the SOC range to which the SOC _TT belongs has shifted from the first SOC range to the second SOC range when a measured resistance value R _TT greater than the reference resistance value R _REF1 is obtained after the start of the comparison. Thus, the current value I _TT in constant current charging is lowered from I _CC1 to I _CC2 . Depending on the resistance characteristics, “R _REF1 <R _TT ” may be established immediately after the start of the comparison, as in the example of FIG.

The main control unit 38 reduces the current value I _TT from I _CC1 to I _CC2 , and then when the measured resistance value R _TT equal to or lower than the reference resistance value R _REF1 is obtained, the SOC range to which the SOC _TT belongs is the second SOC. It is determined that the range has shifted to the third SOC range, and the current value I _TT in constant current charging is increased from I _CC2 to I _CC3 . Thereafter, when the assembled battery 11 _TT terminal voltage V _TT of reaches a predetermined voltage corresponding to SOC _CV, charging of the assembled battery 11 _TT is switched to the constant voltage charging from the constant current charging.

Next, a specific flow of operation during the charging period 320 when the second setting method is adopted will be described. It is assumed that the SOC of each cell 11 is sufficiently low at the start of the charging period 320 (may be considered to be 0%). The main control unit 38 can consider that the assembled battery 11 _TT and the SOC of each cell 11 at the start of the charging period 320 belong to the first SOC range, and at least immediately after the start of the charging period 320, “ The battery pack 11 _TT is _subjected to constant current charging (see FIG. 8) with I _TT = I _CC1 ″.

Thereafter, as shown in FIG. 14, main controller 38 until SOC [1] to SOC [n] from SOC calculator 34 reaches threshold SOC _TH (or SOC _TT reaches threshold SOC _TH) . ), Constant current charging at “I _TT = I _CC1 ” is maintained regardless of the measured resistance values R [1] to R [n], and any one of SOC [1] to SOC [n] (or SOC _TT ) _Becomes equal to or higher than the threshold SOC _TH , the reference resistance value R _REF2 is sequentially compared with the obtained measurement resistance values R [1] to R [n]. After starting the comparison, when it is confirmed that any one of the measured resistance values R [1] to R [n] is larger than the reference resistance value R _REF2 , the main control unit 38 sets the SOC [1] to SOC. It is determined that the SOC range to which any of [n] belongs has shifted from the first SOC range to the second SOC range, and the current value I _TT in constant current charging is lowered from I _CC1 to I _CC2 . Depending on the resistance characteristics, “R _REF2 <R [i]” may be satisfied immediately after the start of the comparison, as in the example of FIG.

The main control unit 38 decreases the current value I _TT from I _CC1 to I _CC2 , compares the measured resistance values R [1] to R [n] with the reference resistance value R _REF2, and measures the measured resistance value R [1 ] To R [n] are confirmed to be equal to or lower than the reference resistance value R _REF2 , the SOC range to which the SOC [1] to SOC [n] belong has shifted from the second SOC range to the third SOC range. _Therefore , the current value I _TT in constant current charging is increased from I _CC2 to I _CC3 . Thereafter, when the assembled battery 11 _TT terminal voltage V _TT of reaches a predetermined voltage corresponding to SOC _CV, charging of the assembled battery 11 _TT is switched to the constant voltage charging from the constant current charging.

As described above, in the third embodiment, when the SOC _TT is equal to or greater than the threshold SOC _TH and the measured resistance value R _TT is larger than the reference resistance value R _REF1 , the charging current rate of the assembled battery 11 _TT is set to another timing. Or any of SOC [1] to SOC [n] is greater than or equal to the threshold SOC _{TH and} any of the measured resistance values R [1] to R [n] is greater than the reference resistance value R _REF2 . At a larger timing, the charging current rate of the assembled battery _11TT is made lower than the other timings. Thereby, when the charging current is increased, the charging current is suppressed in the high resistance region where the deterioration of the cell 11 is expected to be accelerated, and the deterioration of the entire assembled battery is suppressed. Since the charging current is relatively large in the low SOC range where deterioration does not easily proceed even if the internal resistance value is high, the required charging time does not unnecessarily increase (that is, efficient charging is possible). In addition, since the charging current rate can be controlled using the internal resistance value measured in real time, optimal charging control adapted to the deterioration state and use environment (temperature, etc.) of the assembled battery _11TT or each cell 11 is possible. . Therefore, the power storage system 1 according to the third embodiment is also suitable for electric vehicles and hybrid electric vehicles (of course, the power storage system 1 according to the first or second embodiment can also be applied to electric vehicles and hybrid electric vehicles. Is).

In addition, by setting a reference current value that defines the boundary of increase / decrease of the charging current rate based on the assembled battery _11TT or the resistance characteristic data of each cell 11, it is possible to achieve a good balance between suppression of deterioration and efficient charging. it can. This is because, by referring to the resistance characteristic data, the reference resistance value can be determined so that the charging current rate can be lowered at the portion where the assembled battery 11 _TT or the internal resistance value of each cell 11 takes the maximum value.

<< Deformation, etc. >>
The embodiment of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims. The above embodiment is merely an example of the embodiment of the present invention, and the meaning of the term of the present invention or each constituent element is not limited to that described in the above embodiment. The specific numerical values shown in the above description are merely examples, and as a matter of course, they can be changed to various numerical values. As annotations applicable to the above-described embodiment, notes 1 to 4 are described below. The contents described in each comment can be arbitrarily combined as long as there is no contradiction.

[Note 1]
In the above-described embodiment, it is assumed that only one peak SOC exists for each cell 11 for simplification of description. However, even when a plurality of peak SOCs exist for each cell 11, the above-described main points are satisfied. What is necessary is just to control the current rate in charge. For example, when a plurality of peak SOCs exist for the cell 11 [i], the second SOC range including the peak SOC of each cell 11 other than the cell 11 [i] and the plurality of peak SOCs for the cell 11 [i]. Should be set.

[Note 2]
In the embodiment described above, control is performed such current rate based on the SOC converted to the ratio of the residual capacity of the assembled battery 11 _TT or each cell 11 for the full charge capacity of the battery pack 11 _TT or each cell 11 using the remaining capacity of the battery pack 11 _TT or the assembled battery 11 _TT or each cell 11 in place of SOC of each cell 11 may be performed any of the processes described above, including the control of the current rate. As a matter of course, in the assembled battery 11 _TT , if the full charge capacity is normalized to 1, the SOC and the remaining capacity have the same value, so the control based on the SOC and the control based on the remaining capacity are equivalent ( The same applies to the cell 11).

[Note 3]
The control unit 30 or 30A can be configured by hardware or a combination of hardware and software. Arbitrary specific functions that are all or part of the functions realized by the control unit 30 or 30A are described as a program, and the program is stored in a flash memory that can be mounted on the control unit 30 or 30A. The specific function may be realized by executing the program on a program execution device (for example, a microcomputer mountable in the control unit 30 or 30A). The program can be stored and fixed in an arbitrary recording medium (not shown). A recording medium (not shown) for storing and fixing the program may be mounted or connected to a device (such as a server device) different from the control unit 30 or 30A.

[Note 4]
For example, it can be considered as follows. The power storage system 1 includes a charge control device that performs charge control. The charge control device includes at least the control unit 30 or 30A, and may include the above-described resistance characteristic measurement unit 40. The charging control device may be considered to further include at least one of the power conversion circuit 16, the voltage sensors 13 [1] to [n], and the current sensor 14. At the time of charging, the power conversion circuit 16 functions as a current supply circuit for the assembled battery _11TT .

1 Power Storage System 11 _TT Battery 11 Cell (Storage Battery)
13, 13 [i] Voltage sensor 14 Current sensor 15 Charging source 16 Power conversion circuit 30, 30A Control unit 31 Data holding unit 32 SOC range setting unit 33, 38 Main control unit 34 SOC calculation unit 36 Reference resistance value setting unit 37 Inside Resistance measurement unit 40 Resistance characteristic measurement unit 41 Data update unit

Claims (9)

A charge rate deriving unit for deriving a storage battery charge rate that is a charge rate of each of a plurality of storage batteries connected in series forming an assembled battery, or an assembled battery charge rate that is a charge rate of the entire assembled battery;
When the storage battery resistance value changes from increasing to decreasing as the storage battery charging rate increases for each storage battery based on the first data corresponding to the storage battery charging rate dependency of the storage battery resistance value that is the internal resistance value of each storage battery The storage battery charging rate is detected as a peak charging rate, or based on the second data corresponding to the assembled battery charging rate dependency of the assembled battery resistance value, which is the internal resistance value of the entire assembled battery, the assembled battery charging rate The battery pack charge rate when the battery pack resistance value changes from increase to decrease as the battery charge increases is detected as the peak charge rate, and a peak charge rate range including each peak charge rate and having a lower limit greater than zero A setting section to be set;
A control unit for controlling charging of the assembled battery,
The said control part is a charge control apparatus which makes the charging current rate of the said assembled battery lower than other timings in the timing when the said battery charging rate or the storage battery charging rate of any storage battery belongs to the said peak charging rate range. The assembled battery charging rate when the assembled battery resistance value changes from increasing to decreasing with an increase in the assembled battery charging rate includes first and second peak charging rates, and the assembled battery charging rate is the first When the assembled battery resistance value when it coincides with one peak charging rate is larger than the assembled battery resistance value when the assembled battery charging rate coincides with the second peak charging rate,
The setting unit includes a first charging rate range including the first peak charging rate and having a predetermined charging rate range, and a second peak charging rate including the second peak charging rate and having a predetermined charging rate range. The range is set within the peak charging rate range, and the control unit determines a charging current rate when the assembled battery charging rate belongs to the first charging rate range, and the assembled battery charging rate is the second charging rate. The charging control device according to claim 1, wherein the charging current rate is lower than a charging current rate when belonging to the range. The plurality of storage batteries include first and second storage batteries,
The setting unit detects a peak charge rate of each storage battery including first and second peak charge rates that are peak charge rates for the first and second storage batteries based on the first data,
Of the plurality of peak charge rates detected for the plurality of storage batteries, when the first peak charge rate is minimum and the second peak charge rate is maximum,
The setting unit sets a lower limit and an upper limit of the peak charge rate range based on the first and second peak charge rates, and the control unit sets the charge rate of the first storage battery to a lower limit of the peak charge rate range. 2. The charge control device according to claim 1, wherein a charging current rate until the charging rate of the second storage battery reaches the upper limit of the peak charging rate range after reaching the upper limit is lower than charging current rates at other timings. When the assembled battery resistance value when the assembled battery charging rate matches the first peak charging rate is larger than the assembled battery resistance value when the assembled battery charging rate matches the second peak charging rate Or, when the charging rate of the first storage battery matches the first peak charging rate, the internal resistance value of the first storage battery matches the charging rate of the second storage battery with the second peak charging rate. If it is larger than the internal resistance value of the second storage battery,
The setting unit includes a first charging rate range including the first peak charging rate and having a predetermined charging rate range and a second charging rate range including the second peak charging rate and having a predetermined charging rate range. Is set within the peak charging rate range, and the control unit determines a charging current rate when the charging rate of the first storage battery belongs to the first charging rate range. The charging control device according to claim 3, wherein the charging control device is set to be lower than a charging current rate when belonging to the two charging rate range. Prior to charging the assembled battery using the control unit, the battery pack further includes a data holding unit that holds in advance at least one of the first and second data,
The charge control device according to claim 1, wherein the setting unit acquires at least one of the first and second data from the data holding unit. In a measurement period different from the charging period of the assembled battery, a first measurement operation for measuring the storage battery charging rate dependency of the storage battery resistance value for each storage battery, or the assembled battery charging rate dependency of the assembled battery resistance value A resistance characteristic measurement unit that intermittently repeatedly executes the second measurement operation to be measured;
The charge control device according to claim 5, further comprising: a data update unit that updates data held in the data holding unit using a measurement result of the resistance characteristic measurement unit. The setting unit detects the peak charge rate from a range of storage battery charge rates having a predetermined value or more based on the first data for each storage battery, or a set having a predetermined value or more based on the second data. The charge control apparatus according to any one of claims 1 to 6, wherein the peak charge rate is detected from a range of battery charge rates. A charge rate deriving unit for deriving a storage battery charge rate that is a charge rate of each of a plurality of storage batteries connected in series forming an assembled battery, or an assembled battery charge rate that is a charge rate of the entire assembled battery;
During the charging period of the assembled battery, a measuring unit that measures an assembled battery resistance value that is an internal resistance value of the entire assembled battery or each storage battery resistance value that is an internal resistance value of each storage battery;
A setting unit that sets a reference resistance value based on the first data corresponding to the storage battery charge rate dependency of the storage battery resistance value of each storage battery or the second data corresponding to the battery pack charge rate dependency of the battery pack resistance value When,
A control unit for controlling charging of the assembled battery,
The control unit is configured such that the assembled battery charging rate or any storage battery charging rate is equal to or greater than a predetermined value, and the assembled battery resistance value or any storage battery resistance value measured by the measuring unit is greater than the reference resistance value. A charging control device that makes a charging current rate of the assembled battery lower than other timings at a large timing. The setting unit detects, based on the first data, the storage battery resistance value when the storage battery resistance value changes from increasing to decreasing with an increase in the storage battery charging rate for each storage battery, or the second data The assembled battery resistance value when the assembled battery resistance value changes from increasing to decreasing with an increase in the assembled battery charging rate is detected based on data, and the reference resistance value is set based on the detected resistance value. 9. The charge control device according to 8.

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