JP2014115127A - Full charge capacity estimation device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure time for waiting for dissolution of polarization of a battery block of an estimation object of full charge capacity, and exactly estimate the full charge capacity of the battery block without hindering use of the battery block by a vehicle, a motor-driven device, etc. regarding a full charge capacity estimation device of battery blocks connected in parallel and a method.SOLUTION: A full charge capacity estimation device of battery blocks comprises: switches 21-24 which individually separate a plurality of battery blocks 11-14 to be connected in parallel with one another from parallel connection; a switch control section 1 which controls the switches so as to separate only a battery block whose full charge capacity is estimated from the parallel connection among the plurality of battery blocks; and a full charge capacity calculation unit 2 which acquires a value of voltage after dissolution of polarization of the separated battery block, charges the battery block by a predetermined charge amount by a charger 4, calculates charge rates (SOC) before and after charge from voltage before and after the charge of the battery block, and estimates the full charge capacity from the values and the predetermined charge amount.

Description

  The present invention relates to a full charge capacity estimation apparatus and method for estimating the full charge capacity of a rechargeable battery, and more particularly to a full charge capacity estimation apparatus and method for estimating the full charge capacity of batteries connected in parallel. .

  Battery packs in which a plurality of battery blocks including one or a plurality of batteries are connected in parallel are used for industrial vehicles such as forklifts and other electric devices. The battery pack is required to accurately display the remaining capacity and usable time of each battery block. Since they are calculated from the full charge capacity of the battery pack, it is required to accurately estimate the full charge capacity. In some cases, battery capacity may be used as an indicator such as aging of the battery. In this case as well, accurate estimation of the full charge capacity is required.

  As a technique for estimating the full charge capacity of batteries connected in parallel, for example, according to Patent Document 1 below, the current flowing between the positive and negative terminals of the battery is detected, the current is integrated, and the voltage of the battery Charge rate, which is a remaining capacity percentage based on the voltage at the time of the open circuit, is calculated, and the full charge capacity is calculated based on the difference between the current integration value and the previous time, and the current rate difference between the current time and the previous time. Is known, and the new full charge capacity is corrected based on the full charge capacity and the previous full charge capacity.

  In addition, as a charge control technique for batteries connected in parallel, a correlation in which the charging current and the battery temperature to the battery are input variables and the charging voltage when the battery is fully charged is an output variable according to the following Patent Document 2 and the like. When a function is stored in a predetermined storage unit and the battery is in a predetermined condition that can be charged, the estimated full charge at the time of full charge when the battery is charged with the current charging current at the current battery temperature Technology for calculating the voltage for each battery using the correlation function, and controlling the battery so that the charging current is concentrated in order from the battery having the largest difference between the calculated estimated full charge voltage and the current battery voltage. It has been known.

JP 2010-86764 A JP 2010-263755 A

  As a technique for estimating the full charge capacity of a rechargeable battery, there is known a technique of estimating from an open circuit voltage before and after the battery is charged and a current integrated amount during charging. When the battery is charging / discharging, the voltage becomes different from the open circuit voltage due to polarization. Therefore, the open circuit voltage of the battery must be observed after the polarization is eliminated.

  However, a battery pack in which a plurality of battery blocks used in an industrial vehicle such as a forklift is connected in parallel is often used immediately after charging, and there is a case where it is not possible to ensure time for waiting for polarization to be eliminated. . In such a case, the full charge capacity of each battery block cannot be accurately estimated.

  In view of the above problems, in the present invention, for a rechargeable battery block used in a vehicle, an electric device, or the like and connected in parallel, a target for estimating a full charge capacity without hindering the use of the battery block. It is possible to secure the time for eliminating the polarization of the battery block and accurately estimate the full charge capacity of the battery block.

  A full charge capacity estimation device according to an aspect of the present invention includes a switch for individually disconnecting each rechargeable battery block connected in parallel to a load from the parallel connection, and a full battery among the plurality of battery blocks. The battery block for estimating the charge capacity is disconnected from the parallel connection until the polarization of the battery block is eliminated, and other battery blocks other than the battery block for estimating the full charge capacity are connected to the charger. Switch control means for controlling the switch and controlling the switch so as to disconnect the other battery block from the parallel connection, and connecting the battery block for estimating the full charge capacity to the charger; and the full charge Obtain the voltage before charging after depolarization of the battery block to estimate the capacity, and after the battery block is charged with a predetermined charge amount, Obtain the voltage of the battery block, obtain the charge rate before and after charging from the obtained voltage after depolarization of the battery block before and after charging, respectively, from those values and the predetermined amount of charge And a full charge capacity calculating means for estimating the full charge capacity.

  The battery full charge capacity estimation method according to another aspect of the present invention includes a first step of individually disconnecting each chargeable battery block connected in parallel with a load from the parallel connection by a switch. Among the battery blocks, the battery block for estimating the full charge capacity is disconnected from the parallel connection in the first step, and then the voltage before charging after the polarization of the battery block is eliminated is obtained. And a battery block for estimating the full charge capacity after the second step is connected to a charger via the switch, and a predetermined block is connected to the battery block. A third step of charging the amount of charge; and after the third step, the battery block is inserted into the battery block by the switch for a predetermined time during which the polarization of the battery block for estimating the full charge capacity is eliminated. After the fourth step of disconnecting from the column connection and after the fourth step, a voltage of the battery block for estimating the full charge capacity is obtained, and a charge rate after charging is obtained based on the voltage. The full charge capacity of the battery block is estimated from the step, the charge rates before and after charging obtained in the second step and the fifth step, and the predetermined charge amount charged in the third step. And a sixth step.

  According to the present invention, for a rechargeable battery block that is used in a vehicle, an electric device, or the like and is connected in parallel, the battery block that estimates the full charge capacity is separated from the parallel connection, thereby providing another battery block. Without disturbing the use of the battery block, it is possible to secure the time for eliminating the polarization of the battery block whose full charge capacity is to be estimated, and to accurately estimate the full charge capacity of the battery block.

It is a figure which shows the structural example of embodiment of the full charge capacity estimation apparatus by this invention. It is a flowchart of a full charge capacity estimation when it determines with the polarization having been eliminated. It is a flowchart of a full charge capacity estimation when it determines with polarization not cancelling | eliminating. It is explanatory drawing of the improvement of the estimation precision of a full charge capacity. It is a figure which shows an example of the charge state of each battery block by implementation of full charge capacity estimation.

  FIG. 1 shows a configuration example of a full charge capacity estimation apparatus according to the present invention. As shown in the figure, the target of full charge capacity estimation according to the present invention is a battery pack in which a plurality of battery blocks 11 to 14 are connected in parallel. Each of the battery blocks 11 to 14 may be a plurality of batteries connected in series or a single battery. Here, the battery blocks 11 to 14 are collectively referred to as a “battery block”. It is called.

  FIG. 1 shows an example in which four battery blocks are connected in parallel as a battery pack. However, the battery pack is not limited to four battery blocks, and two or more battery blocks are connected in parallel. It can be applied to a connected battery pack.

  As shown in FIG. 1, for each battery block 11 to 14 connected in parallel to the charger 4 and the load 5, switches 21 to 24 that individually disconnect the battery blocks 11 to 14 from the parallel connection are provided. It is done. As the switches 21 to 24, relays, semiconductor switches, or the like can be used. The switches 21 to 24 are controlled by the switch control unit 1 in the battery controller 10.

  Further, switches 25 and 26 for connecting the battery blocks 11 to 14 connected in parallel to either the charger 4 or the load 5 are provided. The switches 25 and 26 are similarly controlled by the switch control unit 1.

  Moreover, the current sensor 3 which detects the amount of current flowing in or out of the battery blocks 11 to 14 connected in parallel is provided. In addition, it is good also as a structure which provides the current sensor which detects each electric current amount of each battery block 11-14 separately instead of the structure which provides the current sensor 3 in each battery block 11-14 in common.

  When current sensors are individually provided for each of the battery blocks 11 to 14, the full charge capacity can be estimated simultaneously for a plurality of battery blocks, and only one current sensor 3 is provided. If so, the full charge capacity of the battery block is estimated one by one. In FIG. 1, broken lines indicate control signal or measurement signal flow paths between the switches 21 to 26, the current sensor 3 and the charger 4, and the controller 10.

  The switch control unit 1 controls the switch 21 so as to disconnect the battery block whose full charge capacity is to be estimated (here, the battery block 11 is taken as an example) from the parallel connection with the other battery blocks 12 to 14. For the switches 22 to 24, the connection with either the charger 4 or the load 5 is maintained, and the other battery blocks 12 to 14 are left in a usable state.

  For the battery block 11 whose parallel connection is disconnected by the switch 21, the full charge capacity calculation unit 2 in the battery controller 10 acquires the voltage after the polarization of the battery block 11 is eliminated. Each battery block 11-14 is provided with a voltage sensor (not shown), and the full charge capacity calculation unit 2 acquires the voltage of the battery block 11 from the voltage sensor.

  The full charge capacity calculation unit 2 calculates a state of charge (SOC) that is a ratio of the remaining capacity to the full charge capacity of the battery block stored in advance and an open circuit voltage (OCV). With reference to the SOC-OCV characteristic indicating the correlation, the charging rate (SOC) of the battery block 11 before charging is obtained based on the acquired voltage.

  Next, the battery controller 10 disconnects the battery blocks 12 to 14 from the charger 4 or the load 5, connects the battery block 11 to the charger 4 by the switches 21 and 25, and charges the battery block 11 to a predetermined charge by the charger 4. The amount (current integrated amount Ah) is charged. After completion of the charging, the battery controller 10 turns off the switch 21 by the switch control unit 1 and puts the battery block 11 into an open circuit state for a predetermined time in order to cancel the polarization.

  While waiting for the polarization of the battery block 11 to disappear, the other battery blocks 12 to 14 are connected to the charger 4 or the load 5 via the switches 22 to 24 and the switches 25 or 26 for charging. Alternatively, discharge is performed.

The full charge capacity calculation unit 2 in the battery controller 10 acquires the value of the voltage of the battery block 11 from a voltage sensor (not shown) after a predetermined time when the polarization after charging of the battery block 11 is eliminated. The full charge capacity calculation unit 2 refers to the SOC-OCV characteristics based on the acquired voltage, and obtains the charge rate (SOC) after the battery block 11 is charged. The full charge capacity calculation unit 2 calculates the full charge capacity from the predetermined charge amount (Ah) charged by the charger 4 and the charge rate (SOC) before and after charging according to the following formula 1.
Full charge capacity = charge amount × 100 ÷ (SOC after charge−SOC before charge) (Equation 1)
In this way, the full charge capacity is estimated while waiting for depolarization while the battery block 11 whose full charge capacity is to be estimated is disconnected from the other parallel connected battery blocks 12 to 14, and the other battery blocks 12 to 12 are estimated. 14 is connected to the charger 4 or the load 5. Therefore, during the waiting time for depolarization of the battery block 11, the other battery blocks 12 to 14 can be used for driving and using a vehicle, an electric device or the like, or the other battery blocks 12 to 14 are charged. It is possible.

  The operation flow of full charge capacity estimation according to the present invention will be described with reference to FIGS. FIG. 2 shows a flow in the case where it is determined that the battery block whose full charge capacity is to be estimated is depolarized. FIG. 3 shows a flow when it is determined that the polarization is not eliminated.

  Whether or not the polarization has been resolved is determined by comparing the elapsed time after disconnection of the main power switch that drives the vehicle, the electric device, or the like with a predetermined threshold, and the elapsed time does not exceed the threshold In this case, it can be determined that the polarization has not been eliminated, and if the elapsed time exceeds the threshold, it can be determined that the polarization has been eliminated.

  When it is determined that the polarization has been eliminated, as shown in FIG. 2, a battery block (hereinafter referred to as “estimated block”) whose full charge capacity is to be estimated is determined and selected (step S21). If a current sensor is provided for each battery block and the amount of charge charged in each battery block can be obtained, a plurality of estimated blocks may be selected. When only one current sensor is provided in the battery pack, one battery block is selected.

  Next, the voltage of the estimation block is acquired (step S22). A charging rate before charging is obtained from the voltage. Next, the estimation block is connected to the charger by a switch, and charging is started only for the estimation block (step S23). Then, a predetermined amount of charge is charged in the estimation block (step S24). The amount of charge can be arbitrarily changed according to voltage measurement accuracy and current integration accuracy. Increasing the charge amount improves the estimation accuracy of the full charge capacity, but the charge time increases accordingly, and the time required to estimate the full charge capacity increases.

  As shown in FIG. 4, the estimation accuracy of the full charge capacity is improved when the charge amount is increased. As shown in FIG. 4, the change amount of the charge rate (ΔSOC) that changes due to the charge is as a ratio to the full charge state 100%. This is because when the full charge capacity is calculated, the effective values of the charge amount and the change amount of the charge rate (ΔSOC) in the above-described equation 1 both increase, and the error decreases accordingly. In FIG. 4, the horizontal axis represents the charging rate (SOC), the vertical axis represents the open circuit voltage (OCV), and the curve 41 represents SOC− indicating the correlation of the open circuit voltage (OCV) to the charging rate (SOC). It represents the OCV characteristic.

  After the charging of the predetermined charging amount is completed, the connection of the switch of the estimation block is turned off (open circuit) in order to cancel the polarization (step S25). During the waiting time for eliminating the polarization, charging is started by connecting a charger to a battery block other than the estimated block (step S26). By charging the battery blocks other than the estimation block during the polarization elimination waiting time, the charging time for charging all the battery blocks can be shortened in step S29 described later.

  At this time, the battery block other than the estimated block is charged with the same amount of charge as that charged in the estimated block. By doing so, the voltage difference of each battery block can be reduced, and after the estimation of the full charge capacity is completed, the estimation block can be connected in parallel with other battery blocks in a balanced state of charge.

  At this time, battery blocks other than the estimation block are not limited to being connected to the charger, but may be connected to a load to be discharged. If a battery block other than the estimated block is charged or discharged and the charge capacity of the estimated block is the same as the charge capacity of the other battery blocks, the estimated block is loaded in a balanced state of charge after the estimation of the full charge capacity is completed. It can be connected in parallel with other battery blocks.

  Next, after elapse of the polarization elimination waiting time, the voltage of the estimated block is measured (step S27). A charging rate after charging is obtained from the voltage. Then, the full charge capacity of the estimation block is calculated from the charged amount (Ah) and the charging rate before and after charging by the above-described equation 1 (step S28).

  After the above steps are completed, when the voltages of the estimated block and the other battery blocks become the same, all the battery blocks are connected to the chargers by switches and charged (step S29). After this step, as in the normal charging process, the charging end determination is performed and the charging is ended.

  Next, an operation flow when it is determined that polarization has not been eliminated will be described with reference to FIG. In this case, the operation flow is obtained by adding step S31 after the estimation block is determined in step S21 to the operation flow of FIG.

  That is, after determining the estimated block in step S21, while waiting for the polarization of the estimated block to be canceled, only the switch of the estimated block is turned off, and the switches of the battery blocks other than the estimated block are turned on and the charger is turned on. Connect and charge (step S31). By charging in this step, the charging time for charging all the battery blocks in step S29 can be shortened in the same manner as the charging in step 26 described above. At this time, battery blocks other than the estimation block are not limited to being connected to the charger, but may be connected to a load and discharged.

  After elapse of time for depolarization of the estimation block, the voltage of the estimation block is acquired in the same manner as in step S22 in FIG. 2, and thereafter, the same steps as those in the operation flow in FIG. 2 are performed. However, if the amount of charge charged in the battery block other than the estimated block in step S31 exceeds the predetermined amount of charge charged in step S24 of FIG. 2, the battery block other than the estimated block is charged. The estimated amount of charge or more is charged to the estimation block as a new predetermined charge amount (step S24).

  This is because when the battery blocks other than the estimated block are charged in step S26, the charging rate (charge amount) of the estimated block and the charge rate (charge amount) of the battery blocks other than the estimated block are aligned. The other steps are the same as the steps shown in FIG.

  FIG. 5 shows an example of the state of charge of each of the battery blocks 11 to 14 by performing the full charge capacity estimation according to the present invention. In FIG. 5, the charging rate (charge amount) of each of the battery blocks 11 to 14 is indicated by hatching. (A) has shown the example of the charging rate (charge amount) of each battery block 11-14 until the battery block 11 is selected as an estimation block, and the voltage after the polarization cancellation of an estimation block is acquired.

  (B) has shown the example of the charging rate (charge amount) when charging only for the estimation block 11 for full charge capacity estimation. (C) has shown the example of the charge condition when charging of the other battery blocks 12-14, such as the waiting period of the polarization elimination of the estimation block 11, is shown. At this time, the other battery blocks 12 to 14 are charged with the same charge amount as the charge amount charged to the estimation block 11, and the voltages of all the battery blocks 11 to 14 are made uniform.

  (D) After the estimation of the full charge capacity of the estimation block 11 is completed, the estimation block 11 is connected to the charger in parallel like the other battery blocks 12 to 14, and all the charging processes are performed in the same manner as in the normal charging process. The example of the charging rate (charge amount) when charging the battery blocks 11 to 14 is shown.

  As described above, for a vehicle or an electric device using a rechargeable battery, only a battery block for estimating a full charge capacity among a plurality of rechargeable battery blocks connected in parallel is disconnected from the parallel connection and fully charged. By estimating the charge capacity, it is possible to connect another battery block to a load or a charger while waiting for the polarization of the battery block to be eliminated. Therefore, when performing the estimation of the full charge capacity, without interrupting the use of the vehicle driven by the battery or the electric device, the time for waiting for the cancellation of the polarization of the battery block for estimating the full charge capacity, The full charge capacity of the battery block can be accurately estimated.

  As mentioned above, although embodiment of this invention was described based on the Example, this invention is not limited to embodiment described above, A various structure or within the range which does not deviate from the summary of this invention. Embodiments can be taken.

DESCRIPTION OF SYMBOLS 1 Switch control part 2 Full charge capacity calculation part 3 Current sensor 4 Charger 5 Load 10 Battery controller 11-14 Battery block 21-26 Switch

Claims (4)

A plurality of rechargeable battery blocks connected in parallel to the load, the switch individually disconnecting from the parallel connection;
Among the plurality of battery blocks, the battery block for estimating the full charge capacity is disconnected from the parallel connection until the polarization of the battery block is eliminated, and other than the battery block for estimating the full charge capacity. Control the switch to connect the battery block to the charger, connect the battery block for estimating the full charge capacity to the charger, and control the switch to disconnect the other battery block from the parallel connection. Switch control means to perform,
Obtaining the voltage before charging after depolarization of the battery block for estimating the full charge capacity, obtaining the voltage of the battery block after depolarization after the battery block is charged with a predetermined amount of charge, and A full charge for obtaining a charge rate before and after charging from the obtained voltage after depolarization of the battery block before and after charging, and estimating a full charge capacity from those values and the predetermined charge amount. Capacity calculation means;
A battery full charge capacity estimation device characterized by comprising: A first step of individually disconnecting each rechargeable battery block connected in parallel to the load from the parallel connection by a switch;
Among the battery blocks, after the battery block for estimating the full charge capacity is disconnected from the parallel connection by the first step, a voltage before charging after the polarization of the battery block is eliminated is obtained, and based on the voltage A second step for determining the charging rate before charging;
After the second step, a third step of connecting the battery block for estimating the full charge capacity to a charger via the switch and charging the battery block with a predetermined charge amount;
After the third step, a fourth step of disconnecting the battery block from the parallel connection by the switch for a predetermined time when the polarization of the battery block for estimating the full charge capacity is eliminated;
After the fourth step, a fifth step of obtaining a voltage of the battery block that estimates the full charge capacity and obtaining a charge rate after charging based on the voltage;
A full charge capacity of the battery block is estimated from the charge rate before and after charging obtained in the second step and the fifth step and the predetermined charge amount charged in the third step. Steps,
The battery full charge capacity estimation method characterized by including.   In the second step, it is determined whether or not the polarization of the battery block for estimating the full charge capacity has been eliminated. If the polarization has not been eliminated, the battery has a predetermined time for which the polarization is eliminated. The battery full charge capacity estimation method according to claim 2, wherein the block is separated by the switch.   The step 4 includes charging a battery block other than the battery block for estimating the full charge capacity by connecting to a charger via the switch for a predetermined time when the polarization is eliminated. The battery full charge capacity estimation method according to claim 2 or 3.

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