JP2013070534A - Electric construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric movable body having small full charge capacity errors without interference with employing the electric movable body.SOLUTION: An electric construction machine converting electric power stored in a secondary battery 10 to motive power includes a battery management unit 11 for calculating full charge capacity of the secondary battery based on battery voltage change in each period of a plurality of charge quiescent periods set at least two times during charging the secondary battery and an electric charge charged in the secondary battery in one or a plurality of charging periods between two charge quiescent periods in the plurality of charge quiescent periods.

Description

  The present invention relates to an electric construction machine including a secondary battery.

  Installed in electric vehicles (electric vehicles (EV), plug-in hybrid vehicles (PHEV), etc.) and electric construction machines (battery excavators, plug-in hybrid excavators, etc.) and small machines such as notebook computers and mobile phones The storage system for managing the rechargeable battery measures the full charge capacity of the battery, calculates the remaining usage time and remaining travel distance, and diagnoses the state of health (SOH) of the battery. Sometimes. Here, as a method of measuring the full charge capacity of the battery, the battery is discharged from the full charge state, the open circuit voltage (OCV) after the discharge is finished, and the charging rate (State of Charge: SOC) obtained from the OCV is measured. ) And the discharge charge (Patent Document 1). Here, OCV gradually rises after discharge and settles to a value that is less than about 2 hours in many batteries. The converged value is a function of SOC.

JP 2002-247773 A

  The technique described in Patent Document 1 is intended for a notebook personal computer. When applied to an electric vehicle or the like equipped with a large battery (large battery) from the viewpoint of securing energy, a problem occurs. That is, when the technique of Patent Document 1 is applied to a large battery, an error occurs when the SOC is estimated from the OCV, and as a result, an error occurs in the full charge capacity. This is because in large batteries, it takes time to eliminate the heat trapped inside, and the OCV is not stable due to the influence of the heat, so the OCV after discharge does not converge to a constant value in about 2 hours, and it becomes SOC. This is because an error occurs. On the other hand, when the OCV is stabilized and the SOC error is reduced by leaving it to stand for 2 hours or more, the leaving time becomes long and the operation efficiency of the electric mobile body is hindered.

  In particular, since an electric construction machine (electric construction machine) has a large number of batteries to be mounted, temperature unevenness due to a difference in the arrangement position is likely to occur, and deterioration may progress only to a specific battery. Therefore, management of SOH of each battery is more important than other electric vehicles such as an electric automobile. In other words, in an electric construction machine, it is more important than other electric vehicles to calculate an accurate full charge capacity and manage the SOH of each battery.

  An object of the present invention is to provide an electric construction machine that does not hinder the operation of the electric construction machine and has a small full charge capacity error.

  In order to achieve the above object, the present invention is an electric construction machine driven by power obtained by converting electric power stored in a secondary battery, and is set at least twice during charging of the secondary battery. Based on a change in battery voltage during each of a plurality of charging suspension periods and a charge charged in the secondary battery during one or more charging periods sandwiched between two charging suspension periods in the plurality of charging suspension periods. And a control means for calculating the full charge capacity of the secondary battery.

  According to the present invention, since charging is an endothermic reaction, it is difficult for heat to be accumulated and the OCV convergence time can be shortened, so that troubles to the operation of the electric construction machine can be reduced and the full charge capacity can be accurately calculated.

1 is an external view of a battery-type hydraulic excavator according to each embodiment of the present invention. The block diagram of the electrical storage system mounted in the battery-type hydraulic shovel which concerns on the 1st Embodiment of this invention. The flowchart of the full charge capacity calculation process performed in the battery management unit which concerns on the 1st Embodiment of this invention. The figure which shows the time change of the battery voltage and charge stop signal in the 1st Embodiment of this invention. The figure which shows the communication format example of the data output to the battery management unit 11 from the secondary battery 10. FIG. The figure which shows the function table of the battery voltage OCV and SOC at the time of no load in each embodiment of this invention. The figure which measured the battery voltage (OCV) of the secondary battery 10 after charge, and plotted the data of the said battery voltage. The figure which shows an example of the polarization time constant table in each embodiment of this invention. The figure which shows an example of the screen of the display apparatus 16 when displaying SOH of the some battery module which comprises the secondary battery 10. FIG. The figure which shows an example of the screen of the display apparatus 16 when displaying SOH of the several separate battery which comprises a battery module. The figure which shows the other example of the time change of the battery voltage in the 1st Embodiment of this invention, and a charge suspension signal. The figure which shows the OCV-SOC characteristic of a certain secondary battery (battery 1). The figure which shows the SOC error characteristic of the battery 1. The figure which shows the OCV-SOC characteristic of another secondary battery (battery 2). The figure which shows the SOC error characteristic of the battery 2. The block diagram of the electrical storage system mounted in the battery-type hydraulic excavator which concerns on the 2nd Embodiment of this invention. The block diagram of the electrical storage system mounted in the battery-type hydraulic shovel which concerns on the 3rd Embodiment of this invention. The flowchart of the full charge capacity calculation process performed in the battery management unit which concerns on the 3rd Embodiment of this invention. An example of a screen prompting the user to turn on the charger switch. An example of a screen that prompts the user to wait while charging. An example of a screen prompting the user to turn off the charger switch. An example of a screen that prompts the user to wait while charging is stopped. An example of the screen which alert | reports to a user that calculation of a full charge capacity, etc. were completed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an external view of a battery-type hydraulic excavator (battery excavator) according to each embodiment of the present invention. The configuration of each embodiment described below can also be applied to other electric construction machines that can be charged by a charger, an electric vehicle such as an electric vehicle (EV), and a power storage system related thereto.

  The battery-type hydraulic excavator shown in this figure includes an articulated working device 1A having a boom 1a, an arm 1b and a bucket 1c, and a vehicle body 1B having an upper swing body 1d and a lower traveling body 1e.

  The boom 1a is rotatably supported by the upper swing body 1d and is driven by a hydraulic cylinder (boom cylinder) 3a. The arm 1b is rotatably supported by the boom 1a and is driven by a hydraulic cylinder (arm cylinder) 3b. The bucket 1c is rotatably supported by the arm 1b and is driven by a hydraulic cylinder (bucket cylinder) 3c. The upper swing body 1d is swiveled by an electric motor (swing motor) (not shown), and the lower runner 1e is driven by left and right travel motors (hydraulic motors) 3e, 3f (not shown). The hydraulic cylinder 3a, the hydraulic cylinder 3b, the hydraulic cylinder 3c, and the travel motors 3e and 3f are driven by pressure oil pumped from the tank 9 by the hydraulic pump 6 (see FIG. 2).

  FIG. 2 is a configuration diagram of a power storage system mounted on the battery-type hydraulic excavator according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part as previous drawing, and description is abbreviate | omitted suitably (following drawing is also the same).

  The power storage system shown in this figure includes a secondary battery 10, a battery management unit (BCU) 11 for monitoring the state of the secondary battery 10, and a current flowing through the secondary battery 10. An ammeter (charge detection means) 12, a communication line 13 connecting the secondary battery 10 and the battery management unit 11, a charger 14 for charging the secondary battery 10, and the charger 14 and the battery management unit 11 are connected. Communication line 15, a display device (display means) 16 for displaying the full charge capacity of the secondary battery 10 calculated by the battery management unit 11, and the communication line connecting the battery management unit 12 and the display device 16. 17, an inverter device (power conversion device) 18 for controlling the motor 19 while converting DC power from the secondary battery 10 into AC power, and a three-phase AC power generated by the power of the secondary battery 10 And over motor (electric motor) 19, and a hydraulic pump 6 driven by a motor 19. In the example of FIG. 2, the hydraulic pump 6 is illustrated as being driven by the motor 19, but other driving devices may be used.

  The secondary battery 10 is an assembled battery composed of a plurality of unit cells, and a lithium ion battery is used in the present embodiment. An assembled battery is an assembly of battery modules. As a general battery module, there is one in which 4 to 40 batteries are connected in series and housed in a box. The battery modules are further connected in series or in parallel to form a component of the assembled battery. The secondary battery 10 shown in FIG. 2 has battery modules connected in series, but may have a series-parallel configuration. In this case, the battery management unit 11 and the ammeter 12 are prepared for each series.

  As the ammeter 12, for example, one using a shunt resistor (for example, see JP-A-2005-188945) or one using a Hall element (for example, see JP-A-7-294561) can be applied. is there. The current value detected by the ammeter 12 is output to the battery management unit 11.

  The secondary battery 10 is connected to the battery management unit 12 via the communication line 13. Further, the secondary battery 10 monitors the voltage of each battery and periodically transmits a voltage value to the battery management unit 11 via the communication line 13. As the communication line 13, local interconnect network (LIN), controller area network (CAN), etc. can be used (Michio Sato, “In-vehicle network system thorough explanation-CAN, LIN, FlexRay protocol and implementation (design wave) Mook) ”, CQ Publishing, December 1, 2005). The total voltage detection line may be connected to an AD converter (not shown) of the battery management unit 11. Further, the battery management unit 11 and the inverter device 18 may be connected by a communication line (CAN may be used).

  The charger 14 is for charging the secondary battery 10 and is used by being connected to the secondary battery 10. In addition, as a form of the charger 14, there are one mounted on an electric vehicle (battery excavator) and one installed outside the electric vehicle outside the electric vehicle, but either one may be used.

  Examples of the charging method of the charger 14 include CCCV charging (Constant-Current Constant-Voltage) and pulse charging method. The CCCV charging method is a method in which charging is performed in a constant current mode from the start of charging, and charging is performed in a constant voltage mode when a target voltage for charging is reached (see, for example, JP 2011-4509 A). In the pulse charging, a pulse current is input every predetermined time (for example, every several seconds), and charging is performed up to a target voltage for charging (Japanese Patent Laid-Open No. 2001-169474). In addition, since the pause by pulse charge is short, it is not treated as the “charge pause period” in the present invention.

  The charger 14 according to the present embodiment stops charging based on a charging suspension signal output from the battery management unit 11, and further stops automatically when the battery is fully charged. . As an alternative to the charging suspension signal, there is a configuration in which a relay is connected to an existing charger and its switch (SW) is controlled (see FIG. 17). The control communication line from the battery management unit 11 uses CAN or a voltage line (ON / OFF state signal indicating that charging by the charger 14 has started) (charge start signal) from the charger 14. One for sending to the battery management unit 11 and one for sending a charging suspension signal from the battery management unit 11 to the charger 14 may be used.

  As a hardware configuration, the battery management unit (control means) 11 includes an arithmetic processing device (for example, a CPU) for executing various control programs, and a storage device (for example, for storing various data including the control program). ROM, RAM) and the like (both not shown). Using such a hardware configuration, the battery management unit 11 fully charges each battery based on the battery voltage of each battery acquired via the communication line 13 and the current acquired via the ammeter 12. Calculate capacity. Then, the charging rate (SOC: State of Charge) and the deterioration level (SOH: State of health) of the entire secondary battery 10 and the SOC and SOH of each battery module and individual battery are calculated based on the full charge capacity (calculation). Details of the method will be described later). The calculated SOH or SOC is output via the communication line 17 and displayed on the display device 16 (details of the display method will be described later). One of the calculation methods of SOH is the following formula (1). Moreover, there exists following formula (2) as a calculation method of SOC.

  The battery management unit 11 stores a no-load battery voltage OCV [V] as specification information of the secondary battery 10. Since the OCV value changes according to the state of charge (SOC) of the battery, the battery management unit 11 in the present embodiment stores the relationship between the SOC and the OCV in the form of a table (see FIG. 6).

  Further, the battery management unit 11 sends a charging suspension command to the charger 14 via the communication line 15. The process of creating a charging suspension command signal for the charger 14 will be described later.

  FIG. 3 is a flowchart of the full charge capacity calculation process executed in the battery management unit according to the first embodiment of the present invention, and FIG. 4 shows the battery voltage and the charge suspension signal in the first embodiment of the present invention. It is a figure which shows the time change of. In the present embodiment, the process shown in FIG. 3 is performed by the battery management unit 11, but the case where it is performed by another apparatus (diagnostic apparatus 101) will be described in the second embodiment.

  The flowchart of FIG. 3 is started when the charging operation of the battery-type hydraulic excavator is started. In addition, when the charger 14 is mounted on the battery-type hydraulic excavator, the charging start time is connected to the system when the charger 14 is mounted, and when the charger 14 is installed outside, the charging power line is connected to the battery-type hydraulic excavator. Sometimes. Moreover, when there is a charge start button on the display device 16 or the charger 14 as in the following embodiment, it is assumed that the user presses the button. By the way, at the time of starting the charging operation (at time zero in FIG. 4), charging of the secondary battery 10 is not started. That is, a charging suspension signal is output from the battery management unit 11 to the charger 14.

  When the charging operation is started, the battery management unit 11 inputs the voltage of each battery module before charging from each battery module via the communication line 13 (step 20). FIG. 5 is a diagram illustrating a communication format example of data output from the secondary battery 10 to the battery management unit 11. This figure shows communication with one battery module and shows an example in which four batteries are connected in series. The format is composed of the number of batteries in one module (four in the case of FIG. 5), the first battery voltage, the second battery voltage, the third battery voltage, and the fourth battery voltage. . The battery management unit 11 receives this communication format for each battery module. Although the total voltage of the secondary battery 10 can be calculated from the sum of the battery voltages, a total voltage detection line may be provided separately and connected to the AD converter of the battery management unit 11 for measurement. .

  When step 20 is completed, the charging suspension signal is turned off and charging of the secondary battery 10 is started (step 21). The time indicated as “charging start” in FIG. 4 is the start time of step 21. In order to start charging the secondary battery 10, the charging suspension signal may be turned off and the charging start signal may be output to the charger 14.

  When charging is started in step 21, the battery management unit 11 executes a process of measuring the voltage and charging current of the secondary battery 10 at predetermined intervals (step 22). The battery voltage is received from each battery module in the format of FIG. 5 (separately, a voltage total voltage detection line may be provided and connected to the AD converter of the battery management unit 11 for measurement). As the current, a value measured by the ammeter 12 is used. These measurement periods may be predetermined values (for example, 80 milliseconds or 100 milliseconds), and in step 22, the measurement may be waited until the period is reached. The value obtained by integrating the current value measured here is used as the charge of the secondary battery 10 when calculating the full charge capacity (step 31). The initial value of the charge is set to 0, and the value is reset to 0 every time charging is started.

  When step 22 is completed, the battery management unit 11 performs a process for determining whether or not to stop charging of the secondary battery 10 (charging stop determination) (step 23). The charging suspension determination in the present embodiment is based on whether or not the voltage increase value from the battery voltage at the start of the charging period (that is, the value measured in step 20 in the first time) has reached the set value. Done. That is, it is determined whether or not the difference ΔV between the battery voltage at the start of the charging period and the current battery voltage has reached the set value.

  Since the secondary battery 10 is composed of a plurality of batteries, an average voltage obtained by dividing the total voltage of the secondary battery 10 by the number of series batteries may be used as the value of the battery voltage used for the charging suspension determination. The minimum value of “current battery voltage−battery voltage immediately before the previous pause period” for each battery may be used. The predetermined value ΔV may be a voltage increase corresponding to the SOC specified in advance (voltage difference indicated by reference numeral 34 in FIG. 4). Here, the calculation of the voltage increase for the designated SOC will be described using the table of FIG.

  FIG. 6 is a diagram showing a function table of OCV and SOC in each embodiment of the present invention. The table shown in this figure is composed of OCV and SOC columns, and is stored in the storage device of the battery management unit 11. The battery management unit 11 estimates the initial SOC by using the value measured in step 20 as the OCV before the start of charging. Note that the OCV value measured in step 20 is not converged because it does not converge, but is used here as a guide. If the OCV is 3.1V, the initial SOC is 10% from the table of FIG. If the SOC specified in advance is 10%, the next charging suspension timing from the initial value (10%) is when SOC is 20%. Here, since the voltage when SOC is 20% is 3.2V from FIG. 6, ΔV = 3.2−3.1 = 0.1V.

  Other charging suspension determinations may be made based on whether or not the charging charge of the secondary battery 10 at the start of the charging period has reached a set value. The set value in this case may be 10% or 20% of the previously measured full charge capacity, or 10% of the full charge capacity of the battery described in the catalog.

  If it is determined in step 23 that charging is not suspended, the process returns to step 22. On the other hand, if it is determined to suspend, a charging suspension signal is output to the charger 14 to start a charging suspension period (step 24).

  During the charging suspension period, the battery management unit 11 performs a process of measuring a change in battery voltage during the charging suspension period (step 25). As a method for measuring a change in the voltage of the secondary battery 10 during the period, there is a method of measuring the voltage of the secondary battery 10 at a predetermined interval. The battery voltage is received from each battery module in the format of FIG. 5 (separately, a voltage total voltage detection line may be provided and connected to the AD converter of the battery management unit 11 for measurement). Note that the battery voltage measurement cycle may be a predetermined value (for example, 1 minute), and in step 25, the measurement may be waited until the cycle is reached.

  When step 25 is completed, the battery management unit 11 executes a process for determining whether or not to resume charging of the secondary battery 10 (charging resumption determination) (step 26). The charge resumption determination in the present embodiment is made based on whether or not the elapsed time from the start time of the charge suspension period (time of step 24) has reached a set value (for example, 30 minutes) or more. In addition, the said setting value is good also as the polarization relaxation time of the secondary battery 10 obtained by measuring the voltage change of the secondary battery 10 after charge previously. Here, the polarization relaxation time is a time during which the polarization relaxation inside the secondary battery 10 sufficiently proceeds after charging and the battery voltage substantially converges. In this embodiment, the polarization relaxation time described with reference to FIG. The value is greater than the constant.

  FIG. 7 is a diagram in which the battery voltage (OCV) of the secondary battery 10 during the charging suspension period is measured every minute for a long time (for example, 2 hours), and data 63 of the battery voltage is plotted. In the graph shown in this figure, the vertical axis represents the battery voltage, and the horizontal axis represents the elapsed time after charging. In the graph, a dotted line 64, a straight line 65, and a point 66 are shown. A dotted line 64 indicates the final value (convergence value) of the OCV of the secondary battery 10. In step 28 described later, the convergence value is estimated based on a plurality of battery voltage data measured during the charging suspension period. Yes. A straight line 65 is a tangent at time zero with respect to a curve (OCV curve) obtained from the OCV plot data 63. A point 66 is an intersection of a dotted line 64 and a straight line 65. In the present embodiment, the time at point 66 is the polarization time constant, and the set value set to be equal to or greater than the polarization time constant is used for the charge resumption determination in step 26.

  Since the polarization time constant changes depending on the temperature, it is preferable to store the polarization time constant (or the setting value for determining resumption of charging) in the storage device of the battery management unit 11 in a table format associated with the temperature. When using a polarization time constant that matches the temperature in this way, a thermometer (not shown) is installed in the secondary battery 10, and the value measured by the thermometer is acquired via the communication line 13. The polarization time constant may be changed according to the value. FIG. 8 is a diagram showing an example of a polarization time constant table in each embodiment of the present invention. The table shown in this figure has two columns of temperature and polarization time constant. In the illustrated example, the value of the polarization time constant measured every 10 ° C. in a predetermined temperature range (from −30 ° C. to 60 ° C.) is stored.

  If it is determined in step 26 that charging is not resumed, the process returns to step 25. On the other hand, if it is determined to resume, the output of the charging suspension signal to the charger 14 is stopped and the charging period is resumed (step 27).

  When the charging period is resumed, the battery management unit 11 executes a process of calculating the SOC of the secondary battery 10 at the end of the charging suspension period (step 28). In this calculation of SOC (charge rate [%]), first, the convergence value of OCV is estimated from the battery voltage measured during the charging suspension period (that is, the value periodically measured in step 25). And since OCV is a function with SOC, SOC is estimated using the estimated convergence value of OCV and the table of FIG.

  As a calculation method for estimating the OCV convergence value in step 28, there is a method using an autoregressive model. In this method, a curve is approximated by a linear sum of a plurality of exponential functions, and the convergence value of the function is used. Specifically, it is calculated from the OCV time series according to the following formula (3) (Statistics Department of Liberal Arts, University of Tokyo, “Statistics of Natural Science”, The University of Tokyo Press). Equation (3) is a second-order case, but a third-order or higher model may be used. Further, instead of the convergence value, the final voltage value during the charging suspension period may be used.

  When the calculation of the OCV convergence value is completed in step 28, the battery management unit 11 performs a process of determining whether or not to calculate the full charge capacity of the secondary battery 10 (full charge capacity calculation determination (calculation determination)). Execute (step 29). The calculation determination in the present embodiment is performed based on whether or not the number of charging suspension periods has reached a set value. The set value is set to be twice or more, and is set to be twice in the present embodiment.

  Note that the SOC value of the secondary battery 10 may be further added to the calculation determination condition. That is, the determination is made based on whether the number of charging suspension periods is two or more and the SOC value exceeds the set value. Refer to the SOC error when setting the SOC setting value. Specifically, ΔSOC / (ΔOCV × 100) is obtained from the table of FIG. 6, and the value is set to a SOC value that is a certain value (for example, the reciprocal of voltage sensing accuracy).

  As a result of the calculation determination in step 29, if it is determined not to calculate the full charge capacity, the process proceeds to step 30 to increase the number of charge suspension periods by 1, and the process returns to step 22. On the other hand, when it is determined that the full charge capacity is to be calculated, the number of charge suspension periods is reset to zero and the process proceeds to the next step 31.

  In step 31, the battery management unit 11 performs a process of calculating and displaying the full charge capacity. The full charge capacity is calculated using the following formula (4) in the case of the present embodiment (that is, when the number of charging suspension periods is two). “Charge between pauses” in equation (4) is the secondary battery 10 in the charge period (charge period 2 in FIG. 4) sandwiched between two adjacent charge pause periods (pause periods 1 and 2 in FIG. 4). It can be obtained by integrating the current periodically measured in step 22 during the charging period. In addition, the “resting SOC” in the following formula (4) is the SOC of the secondary battery 10 at the end of the two charging suspension periods, and is calculated in step 28. Furthermore, the “currently idle SOC” corresponds to the SOC in the idle period 2 in FIG. 4, and the “previous idle SOC” corresponds to the SOC in the idle period 1 in FIG. 4. The full charge capacity calculated here is output to the display device 16 and displayed on the screen of the display device 16. The full charge capacity may be calculated not only for the entire secondary battery 10 but also for each module or for each individual battery, and displayed on the display device 16. Further, when the number of charging suspension periods is three or more, the following formula (5) is used based on the SOC of each charging suspension period and the charging charge of the charging period sandwiched between each charging suspension period. Just calculate.

  Further, the battery management unit 11 is caused to execute processing for calculating the SOC and SOH of the secondary battery 10 using the full charge capacity calculated as described above (see the above formulas (1) and (2)). Furthermore, a process for displaying the calculated SOC and SOH values on the display device 16 may be executed.

  FIG. 9 is a diagram showing an example of a screen of the display device 16 when displaying the SOH of a plurality of battery modules constituting the secondary battery 10. The secondary battery 10 shown in this figure is composed of five battery modules, and the identification number and SOH of each battery module are displayed on the screen. For example, the identification number of the battery module 81 in FIG. 9 is 1 and SOH is 70%. When the close button 83 shown in FIG. 9 is selected, the screen of FIG. 9 can be closed and the SOH display of each battery module can be terminated. In this embodiment, when displaying the SOH of each battery module, first, the SOH of a plurality of individual batteries constituting the battery module is calculated, and the lowest one among the SOHs of the plurality of individual batteries is calculated. Displayed as SOH of battery module.

  By the way, here, the display as shown in FIG. 9 is assumed on the assumption that the battery is replaced in units of modules, but in reality, information on the degree of deterioration of the individual battery may be necessary as production information. In this case, it is preferable that an SOH of an individual battery in the selected battery module is displayed by selecting an image of each battery module on the screen of FIG. 9 with a pointing device or the like. An example of this is shown in FIG.

  FIG. 10 is a diagram showing an example of the screen of the display device 16 when displaying the SOH of a plurality of individual batteries constituting the battery module. The battery module shown in this figure is composed of four individual batteries, and the identification number and SOH for each individual battery are displayed on the screen. This figure displays the SOH of the individual batteries in the battery module 82 in FIG. Referring to FIG. 9, the battery module 82 has an SOH of 50%. However, referring to FIG. 10, an individual battery having an SOH of 50% can be identified. That is, it can be determined that the individual battery with 50% SOH is that of identification number 2 in FIG. When the return button 92 on the screen is selected, the screen of FIG. 9 can be returned. If the screen display range of the display device 16 permits, FIGS. 9 and 10 may be displayed simultaneously.

  When the process of step 31 is finished, a series of full charge capacity calculation processes is finished. Note that the charging of the secondary battery 10 by the charger 14 continues even when these processes are completed. In addition, charging is stopped when the charger 14 automatically determines the timing of the end of charging (the fully charged state of the battery 10).

  As described above, in the power storage system according to the present embodiment, two or more charging suspension periods are provided during charging, and the full charge capacity is calculated by estimating the OCV there. As described above, when OCV is estimated during the charging suspension period, the heat inside the battery can be released by performing an endothermic reaction called charging before and after the charging suspension period. It can be shortened in comparison. As a result, the full charge capacity can be accurately calculated without significantly extending the total time from the start of charging to the completion of charging. That is, according to the present embodiment, it is possible to reduce the troubles that are imposed on the operation of the electric vehicle and to calculate the full charge capacity with high accuracy.

  By the way, in said embodiment, the full charge capacity | capacitance of the secondary battery 10 was calculated by setting at least 2 charge suspension periods between charge start and charge completion. However, the charging suspension period is set only once from the start of charging to the end of charging (including the case where the subsequent charging is not performed), and further the battery voltage change during the charging suspension period And the charge charged in the secondary battery 10 between the end of the charging suspension period and the end of charging of the secondary battery 10, and the change in battery voltage until the predetermined time elapses from the end of charging. Based on this, the full charge capacity may be calculated. This case will be described with reference to FIG.

  FIG. 11 is a diagram illustrating another example of the time variation of the battery voltage and the charging suspension signal according to the first embodiment of the present invention. In the example shown in this figure, the charging suspension period (pausing period 1) is set only once between the start of charging and the completion of charging. In this case, the battery management unit 11 executes the process of periodically measuring the battery voltage from the time when the charging is completed (the specific process content is the same as the process during the charging suspension period (step 25)). Then, when a predetermined time (for example, polarization relaxation time) in which the OCV convergence value can be estimated has elapsed, the measurement of the battery voltage is terminated, and the SOC is calculated in the same manner as in step 28 based on the battery voltage change at the predetermined time. Execute the process. Then, the battery management unit 11 calculates by integrating the SOC calculated from the battery voltage change during the suspension period 1, the SOC calculated after the charging is completed, and the current value measured during the charging period 2 (see FIG. 11). Using the charge, a process for calculating the full charge capacity is executed as in step 31.

  If the SOC is calculated after the completion of charging in this way and the full charge capacity is calculated, the number of charging suspension periods can be reduced by one, so that the time from the start of charging to the completion of charging can be shortened. Accordingly, it is possible to further reduce troubles that affect the operational efficiency of the electric construction machine (electric mobile body). In addition, although the case where the frequency | count of the charging suspension period was 1 was demonstrated here, it cannot be overemphasized that it may set to 2 times or more.

  In the above embodiment, the charging suspension period is started when a predetermined battery voltage is reached. The timing of starting the charging suspension period is the SOC (or OCV) of the secondary battery 10 and the OCV-SOC of each battery. It is preferable to set according to the characteristics. This is because the SOC (OCV) value at which the SOC error calculated in step 28 increases depends on the characteristics of each secondary battery, so that the SOC at the start of the charging suspension period is changed to the characteristics of the secondary battery. This is because it is preferable to optimize accordingly. This point will be described with reference to the drawings.

  FIG. 12 is a diagram showing the OCV-SOC characteristic of a certain secondary battery (battery 1), and FIG. 13 is a diagram showing the SOC error characteristic of the battery 1. Since the voltage calculated in step 25 has an error, even if the voltage x01 is calculated as shown in FIG. 12, there is actually a true voltage within the error range x02. Therefore, when the SOC is obtained from the OCV based on the OCV-SOC curve of FIG. 12, the true value of the SOC exists between the error ranges x03. Therefore, the function of the width of the voltage detection error and the SOC error is expressed by the following equation (6).

  FIG. 13 shows the SOC error width calculated from the above equation (6). In FIG. 13, if the allowable SOC error is determined, a range in which OCV may be measured (restorable range) x04 is obtained. That is, here, the charging suspension period is set when the SOC of the secondary battery 10 is included in the suspension possible range x04. Therefore, this condition is added to the condition that “the voltage difference or the charge charge is greater than or equal to the threshold value” in the charge suspension determination described above. Here, the SOC error range may be a fixed value (for example, 5% or 0.25%). In addition, when the number of charging suspension periods is n, the SOC error range may be calculated using the following equation (7). As the voltage detection error, it is preferable to use the value of the AD conversion error of the system.

  By the way, in order to start the charging suspension period as described above, it is necessary to calculate the current SOC of the secondary battery 10. There are some errors in this, but (1) the full charge capacity of the secondary battery 10 obtained most recently, (2) the SOC initial value calculated from the OCV before the start of charge, and (3) the time of charge start The current SOC can be obtained by using the current integrated value (charged charge) from.

  FIG. 14 is a diagram illustrating OCV-SOC characteristics of another secondary battery (battery 2), and FIG. 15 is a diagram illustrating SOC error characteristics of the battery 2. In the example of FIGS. 12 and 13, the flat voltage region (the region where the SOC error is large) exists when the SOC is relatively high (greater than 50%). Then, this region exists where the SOC is about 50%. As described above, the region where the SOC error increases differs depending on the type of the secondary battery. The resting possible range in this case is indicated by a hatched area as in FIG.

  Next, a second embodiment of the present invention will be described. In the first embodiment, the calculation process of the full charge capacity is performed by the battery management unit 11. However, in the present embodiment, a control means (diagnostic device 101) different from the battery management unit 11 is connected via the communication line 102. The case where the battery management unit 11 is connected and the full charge capacity is calculated by the control means will be described.

  FIG. 16 is a configuration diagram of a power storage system mounted on a battery-type hydraulic excavator according to the second embodiment of the present invention. The power storage system shown in this figure includes a diagnostic device 101 connected to the battery management unit 11 via a communication line 102. The diagnostic device 101 is connected to the display device 16 and is connected to the charger 14 via the communication line 103. In addition, CAN etc. may be used for the connection of each apparatus.

  As the diagnostic device 101, a portable terminal used by a serviceman who performs maintenance work on the electric vehicle, a terminal installed together with the charger 14 in the charging facility of the electric vehicle, or mounted separately from the battery management unit 11 on the electric vehicle. Control device. In addition, the display device 16 may be integrated with a portable terminal for a service person, installed in a charging facility, or mounted on an electric vehicle.

  The full charge capacity calculation process in the present embodiment is performed by the diagnosis apparatus 101 executing each process shown in the flowchart of FIG. However, the battery voltage and current of the secondary battery 10 are obtained by the diagnostic device 101 via the communication line 102 as detected by the battery management unit 11, and the charging suspension signal to the charger 14 is transmitted through the communication line 103. The point that the diagnostic device 101 outputs is different from the point that the diagnostic device 101 outputs the display signal to the display device 16. The display screen of the display device 16 may be the same as that of the first embodiment (for example, FIGS. 9 and 10).

  Thus, even if the full charge capacity is calculated by a control means different from the battery management unit 11, the same effect as in the previous embodiment can be obtained.

  Next, a third embodiment of the present invention will be described. In each of the previous embodiments, the charger 14 is automatically controlled by the battery management unit 11 or the diagnostic apparatus 101. However, the present embodiment is characterized in that it is manually performed.

  FIG. 17 is a configuration diagram of a power storage system mounted on a battery-type hydraulic excavator according to the third embodiment of the present invention. The power storage system shown in this figure includes a charger 14A and a display device 16A. The charger 14A is provided with a switch (switching device) 34 for switching ON / OFF (execution / cancellation) of charging of the secondary battery 10. The display device 16A includes a normal display function and a touch panel having an input function for inputting an instruction to the battery management unit 11 when the user touches the screen. Further, the display device 16A functions as a notification means for notifying the user of the timing by displaying the ON / OFF switching timing of the switch 34 on the screen (details will be described later). Further, the power storage system shown in FIG. 17 is different from that shown in FIG. 2 in that the communication line 15 is omitted.

  FIG. 18 is a flowchart of the full charge capacity calculation process executed in the battery management unit according to the third embodiment of the present invention. The processing here is mainly the same as that shown in FIG. 3, but the ON / OFF of the charger 14A is manual. Furthermore, an instruction to the user is displayed on the screen of the display device 16A at the timing of manual operation of the charger 14A. The same processes as those in FIG. 3 are denoted by the same reference numerals, and description thereof may be omitted as appropriate.

  When the flowchart shown in this figure is started, the battery management unit 11 inputs the voltage of each battery module before charging (step 20), and prompts the user to turn on the switch 34 of the charger 14A. Is displayed on the display device 16A (step 1101). FIG. 19 shows an example of the display screen at this time.

  In the screen shown in FIG. 19, a message display unit 121 that displays a message prompting the user to turn on the switch 34, and a confirmation for causing the battery management unit 11 to confirm that the switch 34 has been turned on. A button 122 is provided.

  When the battery management unit 11 displays the above screen in step 1101, the battery management unit 11 determines whether or not the switch 34 of the charger 14A has been turned ON (that is, whether or not charging has started) (charging SW-ON determination). The processing to be performed is executed (step 1102). Charging SW-ON determination in the present embodiment is performed based on whether or not confirmation button 122 is pressed by the user.

  In the “charging SW-ON determination” in step 1102, the confirmation button 122 is omitted from the screen of FIG. 19, and it is determined that the switch 34 is turned on based on the change in the detection value of the ammeter 12. Also good. As a method of detecting that the switch 34 has been turned on by current, there is a method of determining based on whether or not the absolute value of the current has exceeded a predetermined threshold (for example, 1 [A]).

  If it is not confirmed in step 1102 that the confirmation button 122 has been pressed, the process returns to step 1101 to continuously display the screen shown in FIG. On the other hand, if it is confirmed in step 1102 that the confirmation button 122 has been pressed, the current / voltage is measured (step 22), and the standby screen shown in FIG. 20 is displayed on the display device 16A (step 1103).

  FIG. 20 shows an example of the display screen in step 1103. The screen shown in FIG. 20 is provided with a message display unit 131 that displays a message prompting the user to wait for charging. In this embodiment, the time until the next switch OFF is displayed, but it is also possible to simply issue a “waiting” message. The time until the next switch OFF is a value obtained by dividing the value corresponding to the target SOC charge amount by the current current.

  While the screen of FIG. 20 is displayed, the processes of steps 22 and 23 are performed. In step 23, charging suspension determination is performed. If it is not determined that charging of the secondary battery 10 is suspended, the process returns to step 1103 to display a standby screen. On the other hand, if it is determined that charging of the secondary battery 10 is suspended, the process proceeds to step 1104.

  In step 1104, a process of displaying a screen prompting the user to turn off the switch 34 of the charger 14A on the display device 16A is executed. FIG. 21 shows an example of the display screen at this time. In the screen shown in FIG. 21, a message display unit 141 that displays a message prompting the user to turn off the switch 34, and a confirmation for making the battery management unit 11 confirm that the switch 34 has been turned off. A button 142 is provided.

  When the battery management unit 11 displays the above screen in step 1104, the battery management unit 11 determines whether or not the switch 34 of the charger 14A is turned OFF (that is, whether or not charging is stopped) (charging SW-OFF determination). The processing to be performed is executed (step 1106). Charging SW-OFF determination in the present embodiment is performed based on whether or not confirmation button 142 is pressed by the user.

  In the “charging SW-OFF determination” in step 1106, the confirmation button 142 is omitted from the screen of FIG. 21, and it is determined that the switch 34 is turned off based on the change in the detected value of the ammeter 12. Also good. As a method of detecting that the switch 34 has been turned off by the current, there is a method of determining based on whether or not the absolute value of the current has become a predetermined threshold value (for example, 1 [A]) or less.

  If it is not confirmed in step 1106 that the confirmation button 142 has been pressed, the process returns to step 1104 to continuously display the screen shown in FIG. On the other hand, if it is confirmed in step 1106 that the confirmation button 142 has been pressed, the voltage is measured (step 25) and the standby screen shown in FIG. 22 is displayed on the display device 16A (step 1107).

  FIG. 22 shows an example of the display screen in step 1107. The screen shown in FIG. 22 is provided with a message display unit 151 for displaying a message prompting the user to wait for charging to be stopped. In this embodiment, the time until the next switch is turned on is displayed, but it is also possible to simply issue a “waiting” message. The time until the next switch ON is calculated as “predetermined time−elapsed time from switch OFF”. Here, when the polarization time constant is used as the “predetermined time”, the value is used.

  While the screen of FIG. 22 is displayed, the processing of steps 25 and 26 is performed. In step 26, a charge resumption determination is performed. Here, if it is not determined to resume the charging of the secondary battery 10, the process returns to step 1107 to display a standby screen. On the other hand, when it is determined that the charging of the secondary battery 10 is resumed, the process proceeds to the next process (step 1108).

  In step 1108, the same processing as in step 1101 is executed. That is, the battery management unit 11 performs a process of displaying on the display device 16A a screen (see FIG. 19) that prompts the user to turn on the switch 34 of the charger 14A. When the screen is displayed in step 1108, the battery management unit 11 executes a process for performing the charging SW-ON determination similarly to step 1102 (step 1109). If it is not confirmed in step 1109 that the confirmation button 122 has been pressed, the process returns to step 1108 to continuously display the screen shown in FIG.

  On the other hand, if it is confirmed in step 1109 that the confirmation button 122 has been pressed, a process of calculating the SOC of the secondary battery 10 at the end of the charging suspension period is executed (step 28), and the full charge capacity calculation determination is performed. The processing to be performed is executed (step 29). As a result of the determination in step 29, if it is determined that the full charge capacity is not calculated, the process proceeds to step 30 where the number of charge suspension periods is increased by 1, and the process returns to step 1103.

  On the other hand, if it is determined in step 29 that the full charge capacity is to be calculated, the process proceeds to the next step 31. At that time, the number of charging suspension periods is reset to zero. In step 31, the battery management unit 11 performs a process of calculating and displaying the full charge capacity. At that time, the battery management unit 11 is caused to execute processing for calculating the SOC and SOH of the secondary battery 10 using the calculated full charge capacity, and the calculated SOC and SOH values are displayed on the display device 16A. You may perform the process to display.

  When step 31 is completed, the battery management unit 11 displays a screen (diagnosis end screen) for notifying the user that the calculation of the full charge capacity is completed on the display device 16A (step 1111). FIG. 23 shows an example of the display screen at this time. In the screen shown in FIG. 23, a message display unit 161 that displays a message that the diagnosis is completed and a message that prompts the user to turn on the switch 34, and battery management that the switch 34 is turned on are displayed. A confirmation button 162 for allowing the unit 11 to confirm is provided. The battery management unit 11 confirms that the user has pressed the confirmation button 162, and ends the above series of processing. If the confirmation button 162 is not pressed, the screen display in step 1111 is continued.

  As in the screen of FIG. 19 described above, in the “charging SW-ON determination” in step 1111, the confirmation button 162 is omitted from the screen of FIG. 23 and the switch 34 is turned on. You may determine based on the change of a detected value. In addition, when it is not necessary to fully charge the battery, it is not necessary to turn on the switch 34. In this case, the confirmation button 162 may be omitted. At that time, the screen of FIG. 23 may be displayed for a predetermined time, and then the screen may be automatically turned off.

  As described above, even if the charger 14 is manually turned ON / OFF, the full charge capacity and the like can be calculated in the same manner as in each of the above-described embodiments, so that the same effect can be obtained. In the present embodiment, the case where the battery management unit 11 performs the process of calculating the full charge capacity has been described. However, even when the diagnosis apparatus 101 executes the process as in the second embodiment. Needless to say, it is applicable. In this case, the communication line 103 may be removed from the configuration of FIG. 16 and the charger 14 may be provided with a switch 34.

  By the way, in general, since the deterioration of the secondary battery does not progress suddenly, it is not necessary to perform the full charge capacity calculation process in each of the above embodiments for each charge, and periodically (for example, every other month). ) May be carried out. In that case, from the viewpoint of managing the day when the full charge capacity is calculated, it is preferable to provide a means for preparing a calendar in the battery management unit 11 and storing the date and time when this processing is performed.

  In addition, when the SOC of the secondary battery 10 is high before the start of the full charge capacity calculation process, the SOC is reduced to about 20% in advance by moving the battery-powered excavator from the viewpoint of suppressing the deterioration of the deterioration degree of the battery 10. It is preferable to lower it.

  Moreover, although each said embodiment demonstrated the case where the battery was connected in series, this invention is applicable also when connected in parallel. In this case, the full charge capacity may be calculated for each series.

10 Secondary battery (battery)
11 Battery Management Unit 12 Ammeter 13 Communication Line 14 Charger 15 Communication Line 16 Display Device 17 Communication Line 18 Inverter Device 19 Motor 31 Switch 32 Voltage Acquisition Timing and Voltage before Charging 34 Voltage Increase 63 Plot Data 64 OCV Convergence Value 65 Tangent 66 Polarization time constant 81 Battery module 1
82 Battery module 2
83 button (screen end button)
91 Individual battery 1
92 button (screen transition button)
101 Diagnostic Device 102 Communication Line 103 Communication Line 121 Message Display Unit 122 Button (Charge SW-ON Information Input Button)
131 Message Display Unit 141 Message Display Unit 142 Button (Charge SW-OFF Information Input Button)
151 Message display section 161 Message display section 162 Button (Diagnosis end confirmation button)

Claims (10)

In an electric construction machine driven by power obtained by converting electric power stored in a secondary battery,
Change in battery voltage for each of a plurality of charging suspension periods set at least twice during charging of the secondary battery, and one or a plurality of charging periods sandwiched between two charging suspension periods in the plurality of charging suspension periods And a control means for calculating a full charge capacity of the secondary battery based on the charge charged in the secondary battery. The electric construction machine according to claim 1,
The electric construction machine further comprising display means for displaying a full charge capacity of the secondary battery calculated by the control means. In the electric construction machine according to claim 1 or 2,
A switching device for switching execution / suspension of charging of the secondary battery by charging means;
An electric construction machine further comprising notification means for notifying a user of the switching timing of the switching device. In the electric construction machine according to any one of claims 1 to 3,
The electric construction machine is characterized in that the start timings of the plurality of charging suspension periods are each set when a voltage increase value from the battery voltage at the start of the charging period reaches a set value. In the electric construction machine according to any one of claims 1 to 3,
The start timing of the plurality of charging suspension periods is set when the charge of the secondary battery at the start of the charging period reaches a set value, respectively. In the electric construction machine according to any one of claims 1 to 5,
The plurality of charging suspension periods are set to be equal to or greater than a polarization time constant of the secondary battery. In the electric construction machine according to any one of claims 1 to 6,
The electric construction machine characterized in that the control means starts charging after a set time has elapsed since the end of the immediately preceding charging period. In the electric construction machine according to any one of claims 1 to 7,
The electric construction machine, wherein the plurality of charging suspension periods are set when the SOC is within an SOC error range based on an OCV-SOC characteristic of the secondary battery. A secondary battery,
Change in battery voltage for each of a plurality of charging suspension periods set at least twice during charging of the secondary battery, and one or a plurality of charging periods sandwiched between two charging suspension periods in the plurality of charging suspension periods And a control means for calculating a full charge capacity of the secondary battery based on the charge charged in the secondary battery. In an electric construction machine driven by power obtained by converting electric power stored in a secondary battery,
The battery voltage change during the charging suspension period set before completion of charging of the secondary battery and the secondary battery was charged between the end of the charging suspension period and the end of charging of the secondary battery An electric construction machine comprising: control means for calculating a full charge capacity of the secondary battery based on the electric charge and a battery voltage change from when the charging is completed until a predetermined time elapses.

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