JP2013038884A - Charge/discharge controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge/discharge controller capable of maintaining supply of rating capacity from a power storage device by constantly making maintenance.SOLUTION: A power storage device 10 includes at least one standby electric cell 2. Respective electric cells 2 in the power storage device 10 are connected in parallel or separated from each other by a switching element 3. During charge, a current measurement unit 5 measures a current value of the respective electric cells 2 and a control unit 9 detects an abnormal electric cell 2 on the basis of this measured value. The control unit 9 separates the abnormal electric cell 2 from parallel connection by controlling the switching element 3 while connecting the standby electric cell 2 in parallel, upon detection of the abnormal electric cell 2.

Description

  The present invention relates to a charge / discharge control device that controls charge / discharge of a power storage device including a plurality of power storage elements connected in parallel.

  Secondary batteries such as nickel metal hydride batteries and lithium ion batteries can be used repeatedly by charging discharged batteries, and are widely used as power sources for mobile devices such as notebook computers and video cameras. ing.

  In order to take out the voltage and power required for the device, a plurality of such secondary batteries are often used in combination as a combined battery in series or in parallel. Hereinafter, in this specification, a configuration including only one secondary battery is referred to as a single battery with respect to the assembled battery.

  For example, in Patent Document 1, switch means for disconnecting from parallel connection or connecting in parallel to a plurality of cells connected in parallel is provided, and the current value and voltage value of each cell are detected. Describes a power supply control device that detects the state of each unit cell and performs charging and discharging while switching the switch means based on the deterioration state of the unit cell.

  Patent Document 2 relates to a difference between a first sensor for detecting a current value flowing in a power storage device including a plurality of cells connected in parallel and a current value flowing in a plurality of power storage elements connected in parallel. A plurality of power storage elements having a second sensor for acquiring information and a controller for controlling charge / discharge of the power storage device, the controller being connected in parallel based on the outputs of the first and second sensors The charging / discharging control apparatus which calculates the highest current value among the electric current values which flow through and controls charging / discharging of an electrical storage apparatus based on the calculated electric current value is described.

  By using the techniques described in Patent Documents 1 and 2, it is possible to equalize and suppress deterioration of the single cells connected in parallel and to extend the life of the power storage device.

JP 2007-259612 A (released on October 4, 2007) JP 2011-24303 A (published February 3, 2011)

  However, even if the techniques described in Patent Documents 1 and 2 are used, it is inevitable that the amount of energy (power capacity) that can be supplied from the power storage device gradually decreases. This is to supplement the energy supply of the deteriorated unit cell with another unit cell that also supplies energy. When the amount of energy that can be supplied decreases, there arises a problem that a load that can be operated in the initial stage cannot be operated. For this reason, conventionally, before the load becomes inoperable, it is determined that the life of the power storage device has been reached, and all the cells included in the power storage device are replaced with new ones.

  It is an object of the present invention to provide a charge / discharge control device that makes it possible to continue supplying an energy amount equivalent to the initial amount from a power storage device by performing maintenance.

  In order to solve the above problems, a charge / discharge control device of the present invention is a charge / discharge control device that controls charge / discharge of a power storage device including N power storage elements connected in parallel (N is an integer of 2 or more). The power storage device includes at least one spare power storage element charged in an amount smaller than a rated capacity, and a plurality of power storage elements including the N power storage elements and the spare power storage elements are connected in parallel. A plurality of switching elements that are connected to or disconnected from the parallel connection, a plurality of current measuring units that measure current values flowing through the plurality of power storage elements including the N power storage elements and the spare power storage elements, and N connected in parallel A charge / discharge control unit for controlling charge / discharge of each of the power storage elements, wherein the charge / discharge control unit is configured to connect N power storage units connected in parallel from each current value measured by the current measurement unit during charging. Abnormal power storage element in the element In some cases, this is detected, and the detected abnormal power storage element is disconnected from the parallel connection by controlling the switching element, while the spare power storage element is connected in parallel. It is characterized in that charging / discharging of the power storage device is controlled so as to perform charging / discharging by individual power storage elements.

  According to this, a spare power storage element is prepared in the power storage device. The charge / discharge control unit determines whether there is an abnormal power storage element among the N power storage elements connected in parallel based on the current value of each power storage element detected by the current measurement unit when the power storage device is charged. Is detected. When detecting the abnormal power storage element, the charge / discharge control unit controls the switching element to disconnect the detected abnormal power storage element from the parallel connection, while connecting the spare power storage element in parallel. Thereafter, charging and discharging are performed with N power storage elements including spare power storage elements.

  Thereby, even if an abnormality occurs in the power storage element constituting the power storage device, even if the amount of energy (power capacity) that can be temporarily supplied from the power storage device is reduced, Since it is switched to the spare power storage element, the amount of energy (power capacity) that can be supplied from the power storage device can be maintained as in the initial stage. Then, at the next maintenance, by replacing the storage element in which an abnormality has occurred with a new spare storage element, the rated capacity of the storage apparatus will continue to be supplied from the storage apparatus unless regular maintenance is required. Is possible.

  Here, the backup power storage element is charged with an amount smaller than the rated capacity, and in this case, it is preferably charged within a range of 10 to 50% of the rated capacity.

  If the spare power storage element is sufficiently charged up to the rated capacity, it has the energy itself and thus has the effect of self-discharge. On the other hand, if the amount of charge of the spare power storage element is too small than the rated capacity, it takes time to charge the spare power storage element, the charging time becomes longer, and overdischarge may occur. In this way, by configuring the battery to be charged with an amount smaller than the rated capacity, it is possible to minimize the increase in the charging time of the spare power storage element in a state where the deterioration of the power storage element is unlikely to occur. Can do. In the existing power storage element, the charge amount of the spare power storage element may be 10 to 50% of the rated capacity.

  In the charge / discharge control device of the present invention, the charge / discharge control unit further calculates an average current value of N power storage elements connected in parallel, and calculates a current value of each power storage element and the calculated average current value. It can also be set as the structure which detects an abnormal electrical storage element based on the absolute value of a difference. In this case, the charge / discharge control unit may be configured to detect a storage element having an absolute value of a difference of 10% or more of the average current value as an abnormal storage element.

  Whether or not the storage element is abnormal is determined by obtaining an average current value of N storage elements connected in parallel and determining based on an absolute value of a difference between the current value of each storage element and the average current value. The abnormality can be determined regardless of the capacity variation of the individual differences between the respective power storage elements constituting and the history of the respective power storage elements (number of times of charging / discharging). Specifically, it is 10 to 50% of the rated capacity. By setting it as this range, in the existing electrical storage element, it is difficult to cause deterioration of the electrical storage element, and the charging time can be suppressed as much as possible. In an existing power storage element, a power storage element having an absolute value of a difference from the average current value of 10% or more of the average current value may be detected as an abnormal power storage element.

  In the charging / discharging control device of the present invention, the charging / discharging control unit performs N power storage elements connected in parallel in two stages of constant current charging and subsequent constant voltage charging. After repeatedly detecting abnormal power storage elements from each current value measured by the measurement unit, disconnecting the abnormal power storage elements, the constant voltage charging of the remaining power storage elements is continued, and the constant current charging is completed. Then, it is possible to connect the spare power storage elements in parallel to perform constant current charging of the spare power storage elements, and then perform constant voltage charging together with the remaining power storage elements from which the abnormal power storage elements are separated.

  According to this, since the current value of each power storage element is constantly monitored during constant current charging, a power storage element in which an abnormality such as a short circuit has occurred can be found and separated early. Therefore, more stable charging can be performed.

  The charge / discharge control apparatus of the present invention further includes a plurality of power storage element groups each including the N power storage elements connected in parallel and the spare power storage elements connectable in parallel to the power storage devices, It is preferable that a plurality of power storage element groups be connected in series.

  With such a configuration, the amount of energy (power capacity) that can be supplied from the power storage device can be increased.

  The charge / discharge control apparatus of the present invention may further be configured such that the arrangement position of the spare power storage element is set at a central portion of N power storage elements connected in parallel.

  According to this, it is possible to suppress the temperature increase of other power storage elements with the spare power storage element. The power storage element constituting the power storage device inevitably rises in temperature during discharge. Since the spare power storage element itself is not operating, it has a function of reducing the concentration of heat in the power storage device. Therefore, by arranging the spare power storage element in the central portion of the storage element array that constitutes the power storage device, the temperature rise of the power storage device itself can be effectively suppressed, and the influence of heat on the power storage device can be suppressed. it can.

  In the charge / discharge control device of the present invention, the power storage element further includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode includes a current collector. The current collector is made of a film-like or fibrous resin layer having a conductive layer on both sides, and the separator is a non-aqueous secondary battery having a higher thermal deformation temperature than the resin layer. it can.

  In the worst case, a storage element that has developed an abnormality such as a short circuit may cause a thermal runaway of the unit cell due to the generation of heat. Therefore, it is necessary to detect and disconnect the storage element that has developed an abnormality such as a short circuit at an early stage. For this purpose, it is preferable to constantly monitor the current value of each storage element. According to the above configuration, since the current does not flow to the electric storage element at the same time as the short circuit, such a danger can be avoided without always monitoring.

  According to the charge / discharge control device of the present invention, it is possible to continue to supply the same amount of energy from the power storage device as long as the maintenance is neglected regularly.

It is a circuit block diagram of the charging / discharging control apparatus which is one Embodiment of this invention. It is explanatory drawing which shows the two-stage charge of the electrical storage apparatus which the said charging / discharging control apparatus implements. It is a flowchart which shows the procedure of charge of the electrical storage apparatus by the said charging / discharging control apparatus. It is another flowchart which shows the procedure of charge of the electrical storage apparatus by the said charging / discharging control apparatus. The modification of one said Embodiment is shown and it is a circuit block diagram of a charging / discharging control apparatus. It is a flowchart which shows another procedure of charge of the electrical storage apparatus by the said charging / discharging control apparatus. It is a flowchart which shows another procedure of charge of the electrical storage apparatus by the said charging / discharging control apparatus. The modification of one said Embodiment is shown and it is a circuit block diagram of a charging / discharging control apparatus. The other modification of the said embodiment is shown, and it is a circuit block diagram of a charging / discharging control apparatus. FIG. 11 is a diagram illustrating another modification of the embodiment, and is an explanatory diagram illustrating a configuration of a non-aqueous secondary battery that can be used as a single battery configuring the power storage device. FIG. 10 is a flowchart showing another charging method of the power storage device suitable for charging the power storage device including the nonaqueous secondary battery of FIG. 7, showing another modification of the embodiment. It is a block diagram which shows the function of the principal part of the charging / discharging control apparatus which is another embodiment of this invention. It is explanatory drawing which shows another example of the electrical storage element which comprises the said electrical storage apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a circuit block diagram of a charge / discharge control apparatus 1 according to an embodiment of the present invention. The charge / discharge control device 1 controls charge / discharge of a power storage device 10 including N (N is an integer of 2 or more) unit cells (power storage elements) 2 connected in parallel.

  The power storage device 10 includes at least one spare unit cell 2 in addition to the N unit cells 2 connected in parallel. In the configuration of FIG. 1, a total of five unit cells 2 are provided, where N is four and the number of spare unit cells 2 is one. The spare unit cell 2 has the same standard capacity as the unit cell 2 as the other unit cells 2 constituting the power storage device 10, but the predetermined charge capacity is smaller than the original rated capacity. Is charged to an amount in the range. In the present embodiment, the spare unit cell 2 is charged at 10 to 50% of the rated capacity.

  If the spare unit cell 2 is sufficiently charged up to the rated capacity, it has the energy of its own and thus has the effect of self-discharge. On the contrary, when the charged amount of the spare unit cell 2 is too small than the rated capacity, it takes a long time to charge the spare unit cell 2 and the charging time becomes longer, and overdischarge may occur. In this way, by setting the amount of charge of the spare unit cell 2 to an amount smaller than the rated capacity, the spare unit cell 2 is in a state where the degradation of the unit cell 2 is unlikely to occur and the charging time becomes longer. This can be suppressed as much as possible. In the existing unit cell 2, the charge amount of the spare unit cell 2 may be 10 to 50% of the rated capacity.

  In the present embodiment, the power storage device 10 includes a plurality of blocks (power storage element groups) each including N unit cells 2 connected in parallel and at least one spare unit cell 2 connected in series. In the configuration of FIG. 1, the power storage device 10 includes three blocks 11 to 13, each of which includes five single cells 2 including one spare, and the blocks 11 to 13 are connected in series.

  Such a power storage device 10 is connected to a load (not shown) at the time of discharging and connected to a power source (not shown) at the time of charging via the plus terminal 7a and the minus terminal 7b of the charging / discharging path 7. .

  The charge / discharge control device 1 includes a control unit 9, a voltage measurement unit 8 provided for each block of the power storage device 10, and a switching element 3, a switching element 6, provided for each unit cell included in each block, It is comprised from a pair of switching element 4a * 4b and the electric current measurement part 5. FIG.

  If it demonstrates paying attention to the block 11, the switching element 3 which connects these in parallel and disconnects from the parallel connection is connected to the five unit cells 2 including the reserve included in the block 11. The switching element 3 is provided in each unit cell 2.

  The bases (gates) of the switching elements 3 are independently connected to a control unit (charge / discharge control unit) 9 described later. Each switching element 3 is ON / OFF controlled by the control unit 9 to connect or disconnect the corresponding single cells 2 in parallel. Of the five unit cells 2, four (N) unit cells 2 excluding the spare are connected to the charge / discharge path 7.

  Moreover, the current measuring part 5 which measures the electric current value which flows into the five unit cells 2 contained in the block 11 is connected. The current measuring unit 5 is provided for each single cell 2.

  Here, each current measuring unit 5 is connected to each single cell 2 via a switching element 4a that forms a pair with the switching element 4b. Only one of the pair of switching elements 4a and 4b is turned on when the polarity of the signal flowing through the base (gate) is switched. That is, when the switching element 4a is turned on, the switching element 4b is always turned off, and when the switching element 4a is turned off, the switching element 4b is always turned on.

  The pair of switching elements 4 a and 4 b are arranged between the current measuring units 5 and the single cells 2, but their bases (gates) are connected to the control unit 9 in common. Therefore, in the plurality of pairs of switching elements 4a and 4b, either one of the switching element 4a or the switching element 4b is simultaneously turned ON by a signal from the control unit 9.

  When the switching elements 4 a are turned on all at once, the five single cells 2 are connected to the charge / discharge path 7 via the current measuring unit 5. On the other hand, when the switching elements 4 b are turned on all at once, the five single cells 2 are connected to the charge / discharge path 7 without going through the current measuring unit 5.

  The measured values (output values) of the current measuring units 5 are input to the control unit 9 via the switching elements 6. The switching element 6 is provided in each current measuring unit 5, and the base (gate) of the switching element 6 is independently connected to the control unit 9. Each switching element 6 is controlled to be turned ON / OFF by the control unit 9, thereby causing the corresponding measurement value of the current measuring unit 5 to be input to the control unit 9.

  As the switching element 6, the switching element 3, and the pair of switching elements 4a and 4b, various switching elements such as a bipolar transistor and a field effect transistor can be used.

  Further, the five unit cells 2 included in the block 11 are also provided with a voltage measuring unit 8 that measures a voltage when connected in parallel and connected to the charge / discharge path 7.

  Similarly to the block 11, the block 12 and the block 13 connected in series with the block 11 correspond to the five single cells 2 including one spare, and the switching element 3 and the pair of switching elements 4a and 4b. In addition, five current measuring units 5 and five switching elements 6 are provided, and the voltage measuring unit 8 is provided in units of blocks.

  The control unit 9 (charge / discharge control unit) controls ON / OFF of the switching element 6, the switching element 3, and the pair of switching elements 4 a and 4 b to control charging and discharging of the power storage device 10. The control unit 9 connects four (N) unit cells 2 in parallel in the blocks 11 to 13 included in the power storage device 10 and controls charging and discharging thereof.

  The control unit 9 can arbitrarily select four unit cells 2 connected in parallel among the five unit cells 2 by controlling ON / OFF of each switching element 3. At the time of charging / discharging, the control unit 9 connects four of the five unit cells 2 except for one spare in parallel in each of the blocks 11 to 13, and separates the spare unit cell 2 from the parallel connection. deep.

  Moreover, the control unit 9 can switch ON / OFF simultaneously by switching the polarity of the signal supplied to the base (gate) of the pair of switching elements 4a and 4b. The control unit 9 connects all the five cells 2 included in each of the blocks 11 to 13 to the charging / discharging path 7 through the current measuring unit 5 during charging, and the current measuring unit 5 during discharging. It connects with the charging / discharging path | route 7 without going through.

  Furthermore, the control unit 9 can arbitrarily acquire the current value measured by the current measuring unit 5 to which each switching element 6 is connected by controlling ON / OFF of each switching element 6. The control unit 9 acquires the current value measured by the current measuring unit 5 to which each switching element 6 is connected during charging. The current measuring unit 5 measures the current of the connected unit cells 2.

  Based on the acquired current value, the control unit 9 detects the abnormal unit cell 2 in the four unit cells 2 connected in parallel, and detects the unit cell 2 in which the abnormality is detected. Are disconnected from the parallel connection, and the spare unit cells 2 included in the same block are connected in parallel instead of the separated unit cells 2. Such separation and connection of the unit cells 2 are performed by controlling ON / OFF of the switching element 3 described above. Thereafter, the control unit 9 controls charging / discharging of the power storage device 10 so as to perform charging / discharging with the four unit cells 2 including the spare unit cell 2.

  By the way, as shown in FIG. 2, the control unit 9 charges the power storage device 10 in two stages: constant current charging using a constant current (CC) and subsequent constant voltage charging using a constant voltage (CV). To do. When the voltage value of each block 11 to 13 reaches a preset charging end voltage in constant current charging (also referred to as CC charging), the constant current voltage is shifted to constant voltage charging. The voltage value of each block 11-13 is input into the control unit 9 from the voltage measurement part 8 provided in each block 11-13, and the control unit 9 can detect the arrival to the end-of-charge voltage.

  The control unit 9 detects the abnormal single cell 2 as described above while the power storage device 10 is being charged. There are two detection timings: when the constant current charging ends, and when performing constant current charging.

  This will be described with reference to the flowcharts of FIGS. The flowchart of FIG. 3 shows a charging procedure in the case of detecting an abnormal unit cell 2 at the end of constant current charging.

  When a power source is connected to the power storage device 10 via the charge / discharge path 7, the control unit 9 starts charging the power storage device 10. First, the control unit 9 starts constant current charging (CC charging) using a constant current (S1). After the start, it is determined whether or not the end-of-charge voltage has been reached based on the input from the voltage measuring unit 8 of each block 11 to 13 (S2), and S2 is repeated until the end-of-charge voltage is reached. When it is determined in S2 that it has reached, the current values of the four unit cells 2 connected in parallel excluding the spare unit cell 2 are detected from each current measuring unit 5 for each of the blocks 11 to 13. (S3) For each block 11-13, the average current value of the four single cells 2 is calculated (S4).

  Next, for each cell 2 connected in parallel, the control unit 9 calculates a difference Δ between the corresponding average current value and the detected current value of the cell 2 and corresponds to the absolute value of the calculated difference Δ. The determination value α to be compared is compared (S5). In addition, a corresponding average current value is an average current value of a block in which the unit cell 2 is included. When the calculated absolute value of the difference Δ is equal to or less than the determination value α, it is determined that the unit cell 2 is not abnormal. On the other hand, when the absolute value of the calculated difference Δ is larger than the determination value α, the unit cell 2 is determined to be abnormal.

  For example, as an example, in the power storage device 10, 10 unit cells 2 per block are connected in parallel, and 14 blocks are connected in series (total of 154 unit cells). Is set to flow in 10 parallel cells 2, the variation in the current value of each cell 2 in the block is kept within 10% of the average when the cells 2 are existing secondary cells. It is essential. Therefore, 0.3 can be set as an example of the determination value α. This current variation differs in the rated charging current of the current depending on the rated capacity of the unit cell 2. Moreover, the variation between the individual batteries is also different. Therefore, when the unit cell 2 is an existing secondary battery, it is essential to suppress the average cell to within 10% of the average, but it is preferable that it can be preferably suppressed to 5% or less. For this purpose, there is a method of combining the impedances of the single cells with an increased accuracy in the initial stage.

  In this way, the presence or absence of abnormality of the unit cell 2 is determined by determining the average current value of the unit cell 2 for each block, comparing the current value of each unit cell with the average current value, and using the magnitude of the difference Δ. By doing so, abnormality can be determined irrespective of the capacity | capacitance of each cell 2 which comprises the electrical storage apparatus 10. FIG. That is, the presence / absence of abnormality of the unit cell 2 can be determined using, for example, x% of the rated capacity of each unit cell 2 constituting the power storage device 10 as a determination value. However, in that case, it is necessary to reset the determination value so as to correspond to the capacity of each unit cell 2 constituting the power storage device 10. On the other hand, by using the difference Δ between the current value and the average current value of each unit cell, it is possible to determine whether the unit cell 2 is good or bad regardless of the capacity of each unit cell 2.

  The unit cell (normal unit cell) 2 determined to have no abnormality in S5 is prepared for constant voltage charging (S6). Thereafter, the control unit 9 determines in S7 that there is no abnormality in all the cells 2 included in all blocks, or until it determines in S14 that the spare cell 2 has reached the end-of-charge voltage. , Stand by without performing constant voltage charging.

  On the other hand, the unit cell (abnormal unit cell) 2 determined to be abnormal in S5 is disconnected from the parallel connection (S10), and the spare unit cell 2 is connected in parallel instead (S11). Next, constant current charging of the spare cell 2 is started (S13), and an alarm indicating the abnormality is turned on for the detached cell 2 (S13). Thereafter, it is determined whether or not the spare cell 2 has reached the end-of-charge voltage (S14), and S14 is repeated until the end-of-charge voltage is reached. When it is determined that the spare unit cell 2 has reached the end-of-charge voltage, the process proceeds to S8.

  In S8, the control unit 9 starts constant voltage charging (CV charging) using a constant voltage for the power storage device 10 that has reached the end-of-charge voltage. Here, when the abnormal unit cell 2 is switched to the spare unit cell 2 through S10 and S11, the spare unit cell 2 is also charged with a constant voltage together with other normal unit cells 2. The Thereafter, when the constant voltage charging is completed (S9), the charging of the power storage device 10 is terminated.

  Thereafter, the control unit 9 controls charging / discharging of the power storage device 10 including the spare unit cell 2 whose connection has been switched. In addition, the abnormal unit cell 2 that has been disconnected in S10 can be easily recognized at the time of the next maintenance because an alarm indicating that the battery has failed is turned on in S13. It is exchanged for the unit cell 2. When the abnormal unit cell 2 is removed, the control unit 9 turns off the alarm indicating the abnormality of the unit cell 2 arranged at the corresponding position.

  By the way, although it is the process of carrying out constant current charge of the spare cell 2 in said S12, since all the normal cell 2 has reached the end-of-charge voltage, normal cell 2 and spare cell 2 are connected. Even if the process is performed in a state of being connected in parallel, current may flow from the normal unit cell 2 to the spare unit cell 2, and in this case, it is estimated that leveling occurs in the parallel connection. The

  On the other hand, from the viewpoint of further improving safety, the step S12 may be performed in a state in which the parallel connection with the normal unit cell 2 is disconnected. That is, as shown in the flowchart of FIG. 4, the procedure is to implement S61 instead of S6 in the flowchart of FIG. 3, and to implement S62 before S8. In S61, the unit cell (normal unit cell) 2 determined to have no abnormality in S5 is turned off and disconnected from the charging / discharging path 7 before being prepared for constant voltage charging. In S62, prior to the start of constant voltage charging in S8, each switching element 3 of the normal cell 2 disconnected from the charging / discharging path 7 in S61 is turned on and connected to the charging / discharging path 7. The step of connecting the separated normal cell 2 to the charge / discharge path 7 in S8 is performed after reaching the end-of-charge voltage of the spare cell 2 in S14.

  Alternatively, as shown in the circuit block diagram of FIG. 5, before and after each current measuring unit 5 provided in each unit cell 2, the direction of current flow is changed from a positive terminal 7 a that is a charging direction to a negative terminal 7 b. A diode 15 that restricts the direction of flow through the power storage device 10 may be added.

  On the other hand, the flowchart of FIG. 6 shows a charging procedure when an abnormal cell 2 is always detected during constant current charging. The flowchart of FIG. 6 differs from the flowchart of FIG. 3 in that S3 to S5 are performed before reaching the end-of-charge voltage, and after S5, it is determined whether or not the end-of-charge voltage has been reached. If not, the process returns to S3. In this case, if the spare unit cells 2 are connected in parallel at S11 before the constant current charging of the unit cells (normal unit cells) 2 having no abnormality is completed, the unit cells 2 having no abnormality in the block. There is a possibility that current flows from the battery to the spare cell 2. Therefore, in S2, after the normal cells 2 other than the abnormal cell (abnormal cell) 2 disconnected in S10 in the power storage device 10 reaches the end-of-charge voltage, the spare cells 2 are connected in parallel. It is supposed to be.

  In this case as well, from the viewpoint of further improving safety, as shown in the flowchart of FIG. 7, S61 may be performed instead of S6 in the flowchart of FIG. 6 and S62 may be performed before S8. Good.

  In the procedure of the flowcharts of FIGS. 6 and 7, since the current value of each unit cell 2 is constantly monitored during constant current charging, the unit cell 2 in which an abnormality such as a short circuit has occurred can be detected and disconnected at an early stage. it can. Therefore, more stable charging can be performed.

  By the way, although it is an arrangement position of the spare unit cell 2, it is preferable to set it about the center position of the unit cell 2 contained in each block 11-13. This is because the spare unit cell 2 suppresses the temperature rise of the unit cells 2 in the block. The unit cells 2 in the block inevitably rise in temperature when discharged. Since the spare unit cell 2 itself is not operating, it does not generate heat and has an effect of reducing the concentration of heat in the power storage device. Therefore, by arranging the spare unit cells 2 in the center part (near the center) of the unit cells 2, the temperature rise of the block itself can be effectively suppressed, and the influence of heat on the power storage device 10 can be suppressed. it can.

  Therefore, in the present embodiment, the set position of the spare unit cell 2 is set to the center position of the unit cell 2 included in each of the blocks 11 to 13, and the position of the abnormal unit cell 2 taken out at the time of maintenance is set. Further, the previous spare unit cell 2 in use is moved, and a new spare unit cell 2 is set at the position of the central spare unit cell 2. When the maintenance unit performs an alarm resetting operation and an operation for notifying that the spare unit cell 2 is set at a predetermined position in the center during maintenance, the control unit 9 is set at a predetermined position in the center. 2 is recognized as a spare unit cell 2.

  In the circuit block diagram of FIG. 1, the voltage measuring unit 8 is provided for each block. However, as shown in the circuit block diagram of FIG. 8, a configuration in which one voltage measuring unit 8 is provided in the blocks 11 to 13 may be adopted. Good. In this case, the end-of-charge voltage has a value three times that of the circuit block diagram shown in FIG. 1 (Furthermore, as shown in the circuit block diagram of FIG. The switching element 6 for selectively inputting the measured value may be omitted, in which case the current value of the corresponding single cell 2 measured by the current measuring unit 5 is always input to the control unit 9. Further, the pair of switching 4a and 4b for connecting the current measuring unit 5 to the unit cell 2 only at the time of charging can be omitted.

  Next, a more desirable configuration will be described as the unit cell 2 constituting the power storage device 10. In WO2009 / 131184A1, the applicant of the present application has previously proposed a non-aqueous secondary battery that is resistant to short-circuit abnormality and can be reduced in cost. This non-aqueous secondary battery will be briefly described. As shown in FIG. 10, the non-aqueous secondary battery 50 includes a positive electrode 51, a negative electrode 53, and a separator 52 interposed between the positive electrode 51 and the negative electrode 53. At least one of the positive electrode 51 and the negative electrode 53 includes a current collector. In the configuration of FIG. 10, current collectors 60 and 61 are formed on the positive electrode 51 and the negative electrode 53. The current collector 60 is composed of a film-like or fibrous resin layer 55 having conductive layers 56, 56 on both sides, and the current collector 61 is a film-like or fibrous resin layer having conductive layers 58, 58 on both sides. 59. The separator 52 has a higher heat distortion temperature than the resin layers 55 and 59.

  With such a configuration, when a short circuit occurs, the resin layers 55 and 59 constituting the current collectors 60 and 61 are first melted to shut down the current between the positive electrode 51, the negative electrode 53, and P. It has a function to do. Further, it has a function of preventing an internal short circuit of the battery that occurs at the end of the electrode due to contraction of the separator 52. The battery having the above function has high safety even when the temperature rises. Furthermore, a large-capacity battery carries a current several times greater than that of a conventional portable battery. Even in a large-capacity battery made by mere scale-up, if the above configuration is applied, it becomes easy to prevent an internal short circuit that occurs at the electrode end due to the shrinkage of the separator when the temperature rises. In addition, the amount of metal used can be reduced as compared with a current collector made only of a metal foil used in a conventional non-aqueous secondary battery. As a result, it is possible to reduce the cost by reducing the weight of the battery and reducing the amount of metal used.

  In the charging procedure shown in the flowcharts of FIGS. 6 and 7, since the current value of each unit cell 2 is constantly observed during constant current charging, the unit cell 2 in which a short circuit abnormality has occurred is immediately detected. , It is possible to disconnect it in S10.

  However, in the charging procedure shown in the flowcharts of FIG. 3 and FIG. 4, the current value of each unit cell 2 is detected at the end of constant current charging. It's time. Therefore, the unit cell 2 in which the short circuit abnormality has occurred may lead to thermal runaway of the unit cell in the worst case due to generation of heat. Such a danger can be avoided by using the non-aqueous secondary battery 50 as the unit cell 2 constituting the power storage device 10.

  However, when the non-aqueous secondary battery 50 is used as such a unit cell 2, if a short circuit failure occurs, no current flows at all, so the average current value of the unit cells 2 in the block decreases. The average current value of the single cells 2 in the block decreases more remarkably when the number of N pieces connected in parallel in the block is small. On the other hand, the current flows through the remaining single cells 2 in the block so as to compensate for the receipt of the short-circuited single cells 2, so that the current value increases in the remaining single cells 2. Therefore, the difference Δ between the current value of the normal unit cell 2 and the average current value of the unit cells 2 in the block becomes large despite the normal unit cell 2. Therefore, when detecting the abnormal unit cell 2 using the difference Δ from the average current value of the unit cells 2 in the block, if a short circuit failure occurs, there is a possibility that the normal unit cell 2 is detected as abnormal. In order to avoid this, it is necessary to detect the presence of the unit cell 2 in which a short circuit has occurred before calculating the average current value of the unit cells 2 in the block.

  FIG. 11 shows a flowchart of a charging procedure suitable for a configuration using the non-aqueous secondary battery 50 as the unit cell 2. The flowchart of FIG. 11 is different from the flowchart of FIG. 3 in that S21 to S23 are performed between S1 and S2. In S21, the control unit 9 detects the current value of each unit cell 2, and in S22, the presence or absence of the unit cell 2 in which a short circuit abnormality has occurred is determined from the detected current value of each unit cell. When the short-circuited cell 2 is detected in S22, the process proceeds to S2 via S23. In S <b> 23, correction is performed to minus 1 the total number of single cells 2 in the block including the short-circuited single cells 2. Thereby, since the average current value of the single cells 2 in the block calculated in S4 is calculated in a state where the short-circuited single cells 2 are omitted, an accurate value can be calculated.

  Also in this case, from the viewpoint of improving safety, it is possible to implement S61 in the flowchart of S4 instead of S6 in the flowchart of FIG. 11 and perform S62 before S8.

  In the above description of the embodiment, a configuration in which one spare unit cell 2 is provided for each block of the power storage device 10 is shown. However, it is not necessary to provide a spare cell 2 for each block, and a configuration as shown in FIG. In the configuration of FIG. 12, in the power storage device 10 </ b> A, a spare unit cell 34 is provided in common for the plurality of blocks 31 to 33, and the control unit 9 </ b> A switches the switch unit when an abnormal unit cell 2 is detected. 35 is controlled to connect the remaining unit cells 2 in the block and the spare unit cell 2A in parallel.

  Furthermore, as the power storage element constituting the power storage device 10, the single battery 2 composed of one secondary battery is illustrated. However, as illustrated in FIG. 13, a power storage element 65 in which a plurality of single batteries 2 are connected in series, It is good also as a structure replaced with the cell 2 of FIG.1, FIG.5, FIG.8 and FIG.

  As described above, the spare battery 2 is prepared in the power storage device 10, and the control unit 9 is based on the current value of each battery 2 detected by the current measuring unit 5 when the power storage device 10 is charged. Thus, it is detected whether or not there is an abnormal unit cell 2 among the plurality of unit cells 2 connected in parallel. When the control unit 9 detects the abnormal cell 2, the control unit 9 controls the switching element 3 to disconnect the detected abnormal cell 2 from the parallel connection, while connecting the spare cell 2 in parallel. Thereafter, charging / discharging is performed in a plurality of unit cells 2 including spare unit cells 2.

  As a result, even if an abnormality occurs in the single battery 2 constituting the power storage device 10 and the amount of energy (power capacity) that can be temporarily supplied from the power storage device 10 is reduced, the unit in which the abnormality has occurred during the next charging is reduced. Since the battery 2 is switched to the spare cell 2, the amount of energy (power capacity) that can be supplied from the power storage device 10 can be maintained as in the initial stage. Then, at the next maintenance, by replacing the unit cell 2 in which an abnormality has occurred with a new spare unit cell 2, the energy amount equivalent to the initial value can be obtained from the power storage device 10 unless it is neglected to perform regular maintenance. It becomes possible to continue supplying.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Charging / discharging control apparatus 2, 2A Single cell 3 Switching element 4a, 4b Switching element 4b Switching element 5 Current measuring part 6 Switching element 7 Charging / discharging path | route 8 Voltage measuring part 9, 9A Control unit 10, 10A Power storage apparatus 11-13 Block 31-33 Block 34 Cell 35 Switch unit 50 Non-aqueous secondary battery 51 Positive electrode 52 Separator 53 Negative electrode 55, 59 Resin layer 56/58 Conductive layer 60/61 Current collector 65 Storage element α Determination value

Claims (8)

A charge / discharge control device for controlling charge / discharge of a power storage device including N (N is an integer of 2 or more) power storage elements connected in parallel,
The power storage device includes at least one spare power storage element that is charged with an amount smaller than a rated capacity,
A plurality of switching elements for connecting or disconnecting the plurality of power storage elements including the N power storage elements and the spare power storage elements in parallel or disconnected from each other;
A plurality of current measuring units that measure current values flowing through a plurality of power storage elements including the N power storage elements and the spare power storage elements;
A charge / discharge control unit for controlling charge / discharge of N power storage elements connected in parallel;
The charging / discharging control unit detects, when there is an abnormal power storage element among N power storage elements connected in parallel, from each current value measured by the current measurement unit during charging. The abnormal storage element is disconnected from the parallel connection by controlling the switching element, and the spare storage element is connected in parallel, and thereafter, the N storage elements including the backup storage element are charged and discharged. A charge / discharge control device that controls charge / discharge of the power storage device so as to perform the above.   The charge / discharge control device according to claim 1, wherein the spare power storage element is charged in a range of 10 to 50% of a rated capacity.   The charge / discharge control unit calculates an average current value of N power storage elements connected in parallel, and an abnormal power storage element based on an absolute value of a difference between the current value of each power storage element and the calculated average current value The charge / discharge control device according to claim 1, wherein the charge / discharge control device is detected.   The charge / discharge control device according to claim 3, wherein the charge / discharge control unit detects a storage element having an absolute value of a difference from the average current value of 10% or more of the average current value as an abnormal storage element. . The charge / discharge control unit
N storage elements connected in parallel are performed in two stages of constant current charging and subsequent constant voltage charging.
During constant current charging, detection of abnormal storage elements from each current value measured by the current measuring unit is repeated, and after disconnecting abnormal storage elements, constant voltage charging of the remaining storage elements is continued. When the constant current charging is completed, the spare power storage elements are connected in parallel to perform constant current charging of the spare power storage elements, and then constant voltage charging is performed together with the remaining power storage elements from which the abnormal power storage elements are separated. The charge / discharge control apparatus according to any one of claims 1 to 4, wherein   The power storage device includes a plurality of power storage element groups including N power storage elements connected in parallel and the spare power storage elements connectable in parallel to the power storage devices, and the plurality of power storage element groups are connected in series. The charge / discharge control apparatus according to any one of claims 1 to 5, wherein   The charge / discharge control apparatus according to claim 1, wherein the arrangement position of the spare power storage element is set at a central portion of N power storage elements connected in parallel.   The power storage element includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, at least one of the positive electrode and the negative electrode includes a current collector, and the current collector has conductive layers on both sides. 8. The non-aqueous secondary battery according to claim 1, wherein the separator is a non-aqueous secondary battery having a thermal deformation temperature higher than that of the resin layer. The charging / discharging control apparatus of description.

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