JP6656986B2 - Deterioration determination device for power storage device - Google Patents

Description

  The present invention relates to a device for determining deterioration of a power storage device.

  A power storage device requiring a high voltage and a high capacity (for example, a capacitor mounted on a hybrid shovel or the like) is generally configured by connecting a large number of power storage cells such as a capacitor cell and a secondary battery cell.

  For such a power storage device, a method of determining the deterioration state of each power storage cell has been proposed (for example, Patent Document 1).

  Patent Literature 1 discloses a method of calculating the capacitance of each cell of a capacitor mounted on a shovel and determining the degree of deterioration of each cell based on the calculated capacitance.

WO 2013/121916

  However, according to the technology disclosed in Patent Document 1, it is necessary to calculate the capacitance in a state where the charge and discharge of the capacitor are not performed. Therefore, the opportunity is limited, and the degree of deterioration of each storage cell is easily determined. You may not be able to.

  In view of the above problem, an object of the present invention is to provide a power storage device deterioration determination device that can easily determine the degree of deterioration of each power storage cell included in the power storage device.

To achieve the above object, in one embodiment,
A deterioration determination device for a power storage device including three or more predetermined number of power storage cells connected in series,
An equalization control circuit configured to discharge from one or a plurality of target cells smaller than the predetermined number, the storage cells having a relatively high inter-electrode voltage among the predetermined number of storage cells,
For each of the predetermined number of storage cells, a degradation determination unit that determines a relative degradation degree,
The deterioration determination unit determines a degree of deterioration of each of the predetermined number of power storage cells based on the number of the target cells when the equalization control by the equalization control circuit is performed.
An apparatus for determining deterioration of a power storage device is provided.

  According to the above-described embodiment, it is possible to provide a power storage device deterioration determination device that can easily determine the degree of deterioration of each power storage cell included in the power storage device.

It is a side view of a shovel. It is a figure showing an example of composition of a drive system of a shovel. FIG. 3 is a circuit diagram illustrating an example of a configuration of a power storage system of the shovel. FIG. 3 is a circuit diagram illustrating an example of a configuration of a capacitor. It is a flowchart which shows an example of a deterioration determination process schematically. FIG. 5 is a diagram illustrating voltage characteristics of a normal cell and a deteriorated cell. FIG. 4 is a diagram illustrating a method for determining deterioration of each capacitor cell. 9 is a flowchart schematically illustrating another example of the deterioration determination process. FIG. 4 is a diagram illustrating a method for determining deterioration of each capacitor cell.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

  First, the configuration of a shovel according to the present embodiment will be described with reference to FIGS.

  FIG. 1 is a side view showing the shovel according to the present embodiment.

  As shown in FIG. 1, an upper revolving unit 3 is mounted on a lower traveling unit 1 that is hydraulically driven by hydraulic motors 1A and 1B (see FIG. 2) via a revolving mechanism 2. A boom 4 is attached to the upper swing body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to the tip of the arm 5. The boom 4, the arm 5, and the bucket 6 as attachments are each hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9 as hydraulic actuators. The upper revolving unit 3 is provided with a cabin 10 on which an operator rides, and an engine 11 (see FIG. 2) and the like.

  FIG. 2 is a block diagram illustrating a configuration of a drive system of the shovel. In the figure, the mechanical power system is indicated by a double line, the high-pressure hydraulic line is indicated by a thick solid line, the pilot line is indicated by a broken line, and the electric drive / control system is indicated by a thin solid line.

  In the shovel according to the present embodiment, an engine 11 as a main drive and a motor generator 12 as an assist drive are connected to two input shafts of a speed reducer 13, respectively. A main pump 14 and a pilot pump 15 are connected to an output shaft of the speed reducer 13. Further, a control valve 17 is connected to the main pump 14 via a high-pressure hydraulic line 16.

  The engine 11 drives a main pump 14 and a pilot pump 15 via a speed reducer 13.

  The motor generator 12 can drive the main pump 14 and the pilot pump 15 by assisting the engine 11 via the speed reducer 13. Further, the motor generator 12 can generate electric power by the power of the engine 11 transmitted through the speed reducer 13.

  The main pump 14 is, for example, a variable displacement hydraulic pump. By controlling the angle (tilt angle) of the swash plate, the stroke length of the piston can be adjusted, and the discharge flow rate (discharge pressure) can be controlled.

  The pilot pump 15 is, for example, a fixed displacement hydraulic pump.

  The control valve 17 is a control device that controls a hydraulic system according to an operation input from the operation device 26. Hydraulic motors 1A (for right), 1B (for left), boom cylinder 7, arm cylinder 8, and bucket cylinder 9 for undercarriage 1 (hereinafter sometimes referred to collectively or individually as "hydraulic actuator") Is connected to the control valve 17 via a high-pressure hydraulic line. The control valve 17 is provided between the main pump 14 and each of the hydraulic actuators, and includes a plurality of hydraulic control valves that control the flow rate (pressure) of hydraulic oil supplied from the main pump 14 to each of the hydraulic actuators and the flowing direction thereof. Including.

  A power storage system 120 including a capacitor 19 (see FIG. 3) as an example of a power storage device is connected to the motor generator 12 via an inverter 18A.

  It should be noted that instead of the capacitor 19, another form of power supply that can transfer power such as a rechargeable secondary battery such as a lithium ion battery may be employed.

  An operating device 26 is connected to the pilot pump 15 via a pilot line 25. The operating device 26 includes levers 26A and 26B and a pedal 26C, the lower traveling unit 1 (hydraulic motors 1A and 1B), the upper revolving unit 3 (a revolving electric motor 21 described later), a boom 4 (boom cylinder 7), and an arm. 5 (an arm cylinder 8) and an operating means for operating the bucket 6 (bucket cylinder 9) and the like. The levers 26A and 26B and the pedal 26C are connected to the control valve 17 and the pressure sensor 29 via a hydraulic line 27 and a hydraulic line 28, respectively. As a result, a pilot signal (pilot pressure) corresponding to the operating state of the lower traveling structure 1, the upper swing structure 3, the boom 4, the arm 5, the bucket 6, and the like in the operating device 26 is input to the control valve 17. The pressure sensor 29 is connected to the controller 30. As a result, a pressure signal corresponding to the operating state of the lower traveling structure 1, the upper swing body 3, the boom 4, the arm 5, the bucket 6, and the like in the operating device 26 is input to the controller 30.

  In the shovel according to the present embodiment, the turning mechanism 2 is electrically driven, and a turning electric motor 21 that drives the upper turning body 3 via the turning mechanism 2 is provided. The turning electric motor 21 converts kinetic energy into electric energy and performs regenerative power generation when the upper turning body 3 decelerates turning. Turning electric motor 21 is connected to power storage system 120 via inverter 18B. A resolver 22, a mechanical brake 23, and a turning speed reducer 24 are connected to a rotating shaft 21A of the turning electric motor 21.

  The controller 30 is a control device that performs drive control of the shovel. The controller 30 includes, for example, an arithmetic processing unit (microcomputer) including a CPU, a ROM, and the like, and executes various drive control programs stored in the ROM on the CPU to realize various drive controls. .

  The controller 30 converts a pressure signal supplied from the pressure sensor 29 (a signal indicating the operating state of the upper swing body 3 in the operating device 26) into a speed command, and controls the drive of the swing motor 21.

  The signal supplied from the pressure sensor 29 to the controller 30 includes a signal representing an operation amount of the operation device 26 for turning the turning mechanism 2.

  Further, the controller 30 controls the operation of the motor generator 12 (switching between electric (assist) operation and power generation operation), and controls the charge and discharge of the capacitor 19 by controlling the drive of the buck-boost converter 100 (see FIG. 3). I do. The controller 30 controls the buck-boost converter 100 based on the state of charge of the capacitor 19, the operation state of the motor generator 12 (electric (assist) operation or power generation operation), and the operation state of the turning motor 21 (powering operation or regenerative operation). The switching control between the step-up operation and the step-down operation is performed, whereby the charge / discharge control of the capacitor 19 is performed.

  Further, the controller 30 performs a deterioration determination process of the capacitor 19. Details will be described later.

  FIG. 3 is a circuit diagram showing an example of the configuration of the power storage system 120.

  Power storage system 120 includes capacitor 19, step-up / step-down converter 100, DC bus 110, and the like.

  The DC bus 110 controls transfer of electric power among the capacitor 19, the motor generator 12, and the turning motor 21. The capacitor 19 is provided with a capacitor voltage detecting unit 112 and a capacitor current detecting unit 113 for detecting a voltage value and a current value of the capacitor 19. The capacitor voltage value and the capacitor current value detected by the capacitor voltage detection unit 112 and the capacitor current detection unit 113 are supplied to the controller 30.

  The buck-boost converter 100 switches between the step-up operation and the step-down operation so that the voltage value of the DC bus 110 (DC bus voltage value) falls within a certain range in accordance with the operation state of the motor generator 12 and the turning motor 21. . The DC bus 110 is provided between the inverters 18A and 18B and the step-up / step-down converter 100, and the capacitor 19, the motor generator 12, and the turning motor 21 exchange power via the DC bus 110.

  The switching control between the step-up operation and the step-down operation of the buck-boost converter 100 is performed by the DC bus voltage value detected by the DC bus voltage detection unit 111, the capacitor voltage value detected by the capacitor voltage detection unit 112, and the capacitor current detection unit 113. This is executed by the controller 30 based on the detected capacitor current value.

  FIG. 4 is a circuit diagram illustrating an example of the configuration of the capacitor 19.

  The capacitor 19 includes a predetermined number (n) or more of three or more capacitor cells (hereinafter simply referred to as “cells”) 19-1 to 19-n (n is an integer of 3 or more) connected in series. That is, the capacitor 19 is configured as a series connection of n cells 19-1 to 19-n.

  In the present embodiment, all of the n cells 19-1 to 19-n are connected in series, but the cells connected in series form one group (cell group), and a plurality of cell groups A configuration in which they are connected in parallel may be used. Hereinafter, the cells 19-1 to 19-n are collectively or individually referred to as cells 19-k (k = 1, 2,..., N).

  The capacitor 19 is connected to a capacitor control circuit 140 (an example of an equalization control circuit).

  The capacitor control circuit 140 has a function of measuring the voltage of each cell 19-k (voltage measurement function) and an equalization function of equalizing the voltage of each cell (also referred to as a cell balance function).

  The capacitor control circuit 140 includes a monitoring IC (Integrated Circuit) 142 as a control unit, and both ends of each cell 19-k are connected to the monitoring IC 142. Specifically, for example, one of the electrodes of the cell 19-1 is connected to the monitoring IC 142 by a wiring 144-1, and the other electrode is connected to the monitoring IC 142 by a wiring 144-2. Similarly, one of the electrodes of the cell 19-n is connected to the monitoring IC 142 by a wiring 144-n, and the other electrode is connected to the monitoring IC 142 by a wiring 144- (n + 1). That is, both ends of the cell 19-k are connected to the monitoring IC 142 by two wires 144-k, 144- (k + 1).

  A balance FET (Field effect transistor) 146-1 and a discharge resistor 148-1 are connected in series between the wiring 144-1 and the wiring 144-2. In other words, a series connection of the balancing FET 146-1 and the discharge resistor 148-1 is connected in parallel to the cell 19-1 between the wiring 144-1 and the wiring 144-2. The gate of the balancing FET 146-1 is connected to the monitoring IC 142. Similarly, a balancing FET 146-n and a discharge resistor 148-n are connected in series between the wiring 144-n and the wiring 144- (n + 1). In other words, a series connection of the balancing FET 146-n and the discharge resistor 148-n is connected in parallel to the cell 19-n between the wiring 144-n and the wiring 144- (n + 1). The gate of the balancing FET 146-n is connected to the monitoring IC 142. That is, a series connection of the balancing FET 146-k and the discharge resistor 148-k is connected between the wiring 144-k and the wiring 144- (k + 1) so as to be connected in parallel with the cell 19-k. In addition, the gate of the balancing FET 146-k is connected to the monitoring IC 142.

  The balancing FET 148-k and the discharge resistor 148-k constitute a so-called equalization (cell balance) circuit, and the cell 19-k can be short-circuited by turning on the balancing FET 148-k. That is, when the balancing FET 148-k is short-circuited, the discharge from the cell 19-k is performed, and the discharge energy is consumed by the discharge resistor 148-k. Thereby, when an inter-electrode voltage (hereinafter, referred to as a cell voltage Vk), that is, an unbalance occurs in the capacitance between the cells 19-k, the cells 19-k having a relatively high cell voltage Vk. By discharging k, the imbalance can be eliminated. Therefore, it is possible to avoid a situation in which all the capacitance of the capacitor 19 cannot be used due to the imbalance of the cell voltage Vk between the cells 19-k.

  When a voltage measurement command is input from the controller 30, the monitoring IC 142 measures the cell voltage Vk of each cell 19-k and outputs the measured cell voltage Vk of each cell 19-k to the controller 30. For example, the cell voltage V1 of the cell 19-1 can be detected as a potential difference between the wiring 144-1 and the wiring 144-2. Similarly, the cell voltage Vn of the cell 19-n can be detected as a potential difference between the wiring 144-n and the wiring 144- (n + 1). That is, the cell voltage Vk of the cell 19-k can be detected as a potential difference between the wiring 144-k and the wiring 144- (k + 1).

  Further, the monitoring IC 142 performs equalization control for eliminating the imbalance of the cell voltage Vk between the cells 19-k in accordance with the forced balance command input from the controller 30. Specifically, the monitoring IC 142 transmits an ON signal to the gate of the balancing FET 146-k, and the cell 19-k (hereinafter, the target cell 19-i (i: (An integer value between). At this time, the discharge current from the target cell 19-i becomes a small current due to the action of the discharge resistor 148-i, so that the cell voltage Vi of the target cell 19-i gradually decreases.

  Next, an example of a process of determining deterioration of the capacitor 19 (a process of determining a relative degree of deterioration of each cell 19-k) performed by the controller 30 will be described with reference to FIG.

  In the present embodiment, the deterioration determination process of the capacitor 19 is executed by the controller 30, but may be executed by the monitoring IC 142 or may be executed by another processing device other than the controller 30.

  FIG. 5 is a flowchart schematically illustrating an example of a process of determining deterioration of the capacitor 19 by the controller 30. As described below, the deterioration determination process of the capacitor 19 in the present embodiment is executed in a mode that integrally includes equalization control of the target cell 19-i. The process according to this flowchart may be repeatedly executed at predetermined time intervals during the operation of the shovel, that is, during a period from key-on to key-off of the shovel.

  In step S102, the controller 30 transmits a voltage measurement command for measuring the cell voltages Vk of all the cells 19-k to the monitoring IC 142. Accordingly, the monitoring IC 142 measures the cell voltages Vk of all the cells 19-k, and transmits the measured values to the controller 30.

  In step S104, controller 30 determines whether equalization control is necessary. For example, the controller 30 determines whether the difference between the highest cell voltage value and the lowest cell voltage value among the cell voltages Vk of the cells 19-k is greater than a predetermined value, or at least one of the cells 19-k. For example, when the voltage Vk exceeds a predetermined upper limit voltage value, it can be determined that equalization control is necessary. If the controller 30 determines that the equalization control is necessary, the process proceeds to step S106, and if it determines that the equalization control is not necessary, the controller 30 ends the current process.

  In step S106, the controller 30 sets a target voltage Vtgt for lowering the voltage of the target cell 19-i by the equalization control. The target voltage Vtgt may be a predetermined voltage value (constant) or an average value of the cell voltages Vk of all the cells 19-k.

  In step S108, the controller 30 determines the target cell 19-i. For example, the controller 30 may determine the cell 19-k higher than the target voltage Vtgt as the target cell 19-i.

  In step S110, the controller 30 discharges the determined target cell 19-i, that is, performs equalization control on the target cell 19-i. If there are a plurality of determined target cells 19-i, equalization control is performed for each target cell 19-i. Specifically, the controller 30 transmits a forced balance signal to the monitoring IC 142, and the monitoring IC 142 performs equalization control in response to receiving the forced balance signal. The monitoring IC 142 transmits an ON signal to the gate of the balancing FET 19-i, short-circuits the target cell 19-i, and discharges the target cell 19-i.

  When performing the equalization control, the monitoring IC 142 obtains the cell voltage Vi of the target cell 19-i constantly or periodically, and confirms that the target cell 19-i has dropped to the target voltage Vtgt. , An OFF signal is transmitted to the gate of the balancing FET 19-i. Further, the monitoring IC 142 may calculate a time for decreasing the voltage to the target voltage Vtgt in advance, and turn on the balancing FET 19-i for the calculated time.

  In step S112, the controller 30 increments an index value (deterioration point Pi) indicating the degree of deterioration of the target cell 19-i based on the number of target cells 19-i. Specifically, the controller 30 increases the increment value of the deterioration point Pi as the number of target cells 19-i in the current equalization control decreases. That is, the controller 30 additionally gives a deterioration point to the target cell 19-i such that the smaller the number of the target cells 19-i in the current equalization control, the higher the degree of deterioration. For example, the deterioration point given when the number of target cells 19-i in each equalization control is one is set to the maximum value, and each time the number of target cells 19-i increases by one, the target cell 19-i is increased. May be reduced by a predetermined amount. Further, the deterioration point given when the number of target cells 19-i in each equalization control is one is set as a maximum value, and the deterioration point given to the target cell 19-i is determined by using the maximum value as the target cell. It may be a value divided by the number of 19-i.

  Note that the process of step S112 may be executed in parallel with (ie, simultaneously with) step S110. Further, the deterioration point Pk of each cell 19-k is stored in the nonvolatile internal memory of the controller 30. Further, the deterioration point Pk of each cell 19-k is set to “0” when the capacitor 19 is not used, and as the usage time of the capacitor 19 by the operation of the shovel advances and the number of equalization controls increases, It is sequentially updated in the process of step S112. That is, every time the equalization control is performed, the controller 30 gives the target cell 19-i an index value indicating a deterioration degree that becomes higher as the number of the target cells 19-i is smaller, and adds the cell 19-i. The integrated value of the index value for each k is stored in the internal memory. Further, as described later, when any one of the cells 19-k is determined to be relatively deteriorated and the cell 19-k is replaced, the deterioration points Pk of all the cells 19-k are set to “0”. Initialized to ".

  In step S114, the controller 30 determines the deterioration point Pk of each cell 19-k updated in the process of step S112 (that is, the degree of deterioration given to the target cell 19-i in each process of step S112). The presence or absence of deterioration of the capacitor 19 is determined based on the integrated value of the indicated index value). Specifically, the controller 30 determines that the capacitor 19 has deteriorated when the variation in the progress of deterioration of each cell 19-k included in the capacitor 19 is larger than a predetermined reference. For example, the controller 30 may determine that the capacitor 19 has deteriorated when the difference between the maximum value Pmax and the minimum value Pmin of the deterioration point Pk of each cell 19-k is equal to or larger than a predetermined threshold Pth1.

  In step S116, controller 30 determines whether or not capacitor 19 has deteriorated based on the result of step S114. If the controller 30 determines that the capacitor 19 has deteriorated, the process proceeds to step S118, and if it determines that the capacitor 19 has not deteriorated, the controller 30 ends the current process.

  In step S118, the controller 30 abnormally progresses the deterioration of the cells 19-k of the capacitor 19 based on the deterioration point Pk of each cell 19-k (ie, relatively deteriorates). The cell 19-k (hereinafter, referred to as a deteriorated cell) is specified. Specifically, when the deterioration point Pk is equal to or more than the predetermined threshold value Pth2, or when the deterioration point Pk has a difference equal to or more than the predetermined threshold value Pth1 from the minimum value Pmin, the controller 30 sets the cell 19-k to It may be determined that the battery is relatively deteriorated.

  In step S120, the controller 30 issues an alarm indicating that the capacitor 19 is deteriorated by a display on a display or an indicator (both not shown) disposed in the cabin 10 or a sound through a speaker (not shown). Do. At this time, the controller 30 may display on a display or the like in the cabin 10 which of the cells 19-k of the capacitor 19 is a degraded cell. Thereby, the replacement of the deteriorated cell of the capacitor 19 can be urged to the operator of the shovel or the operator who maintains the shovel.

  As described above, in this example, the controller 30 determines whether or not the capacitor 19 has deteriorated based on the number of the target cells 19-i when the equalization control is performed by the capacitor control circuit 140 (specifically, the monitoring IC 142). , And the degree of deterioration of each cell 19-k. Specifically, every time the monitoring IC 142 performs the equalization control, the controller 30 sets an index value (deterioration) indicating the degree of deterioration that becomes higher as the number of the target cells 19-i is smaller for the target cell 19-i. Points). Then, the controller 30 determines whether or not the capacitor 19 has deteriorated and the degree of deterioration of each cell 19-k based on the integrated value (deterioration point Pk) of the deterioration points of each cell 19-k. Therefore, according to the present embodiment, the deterioration determination of the power storage device can be performed in association with the normal equalization control. Therefore, the opportunity for determining the deterioration of the power storage device is not limited, and the deterioration of the power storage device can be easily determined.

  Here, with reference to FIGS. 6 and 7, the details of the processing of steps S112, S114, and S118 in FIG. 5 described above, that is, the details of the method of determining the deterioration of the capacitor 19 will be described.

  FIG. 6 is a diagram for explaining a normal cell 19-k in which deterioration has hardly progressed (hereinafter, referred to as a normal cell) and a voltage characteristic of a deteriorated cell in which deterioration has progressed to some extent. FIG. 5 is a diagram showing a change characteristic of a cell voltage with respect to a charging time of a deteriorated cell. FIG. 7 is a diagram illustrating a method of determining deterioration of each cell 19-k. Specifically, FIG. 7 shows a case where a deteriorated cell is subject to equalization control (a) and a case where a normal cell is subject to equalization control. It is a figure which shows the cell voltage Vk of each cell 19-k of (b).

  In the example shown in FIG. 7, the number of cells 19-k included in the capacitor 19 is six (that is, n = 6). In the example shown in FIG. 7, the number of deteriorated cells is one.

  As shown in FIG. 6, the cell voltage of a normal cell (solid line in the figure) changes with a relatively gentle slope with respect to the charging time. On the other hand, the cell voltage of the abnormal cell (dotted line in the figure) changes with a relatively steep slope with respect to the charging time. Therefore, in the state where the charging rate of the capacitor 19 is relatively high, since the area corresponds to the area (the area where the charging time is long) on the right side of the intersection Ps between the solid line and the dotted line in the figure, the equalization control target cell 19-i is: It becomes a deteriorated cell. On the other hand, in the state where the charging rate of the capacitor 19 is relatively low, the area corresponds to the area (the area where the charging time is short) on the left side of the intersection Ps between the solid line and the dotted line in the figure, and the target of equalization control is a normal cell. . That is, the target cell 19-i in each equalization control is one of a normal cell and an abnormal cell.

  The number of deteriorated cells is usually a relatively small number (one cell 19-4 in this example) with respect to the number of all cells 19-k of the capacitor 19. Therefore, as shown in FIG. 7A, when the deteriorated cell is subjected to the equalization control, the number of the target cells 19-i is relatively smaller than the whole number (dotted frame in the figure). That is, the number of target cells 19-i is equal to the number of cells 19-k (hereinafter, referred to as non-target cells 19-j (j is an integer between 1 and n)) other than the target cell 19-i. Less. On the other hand, as shown in FIG. 7B, when a normal cell is subjected to equalization control, the number of target cells 19-i is relatively large with respect to the total number (dotted frame in the figure). That is, the number of target cells 19-i is larger than the number of non-target cells 19-j (dotted frame in the figure). Therefore, as described above, a deterioration point is additionally provided to the target cell 19-i so that the lower the number of the target cells 19-i in each equalization control is, the higher the number of the target cells 19-i becomes (the deterioration point Pi is incremented. Therefore, the deterioration point Pk of the deteriorated cell is easily increased, and the deterioration point Pk of the normal cell is hardly increased. Therefore, every time the equalization control is performed, the deterioration point Pi of the target cell 19-i is updated (integrated), thereby deteriorating the capacitor 19 (specifically, the deterioration progress of each cell 19-k). And the relative deterioration of each cell 19-k.

  For example, in each equalization control, when one target cell 19-i is provided, five additional points are given as deterioration points (the deterioration point Pi is incremented by five points), and one target cell 19-i is provided. A method is adopted in which the number of deterioration points given to the target cell 19-i is reduced by one point each time the number of cells increases. In this case, in the example shown in FIG. 7, when the deteriorated cell (cell 19-4) is subjected to equalization control, five points are given to the deteriorated cell as deterioration points. On the other hand, when the normal cells (cells 19-1 to 19-3 and cells 19-5 and 19-6) are subjected to equalization control, only one normal cell is given as a deterioration point. In addition, since the capacitor 19 is generally used widely from a relatively high charging rate to a relatively low charging rate, the target of equalization control does not concentrate on one of the normal cell and the deteriorated cell. Therefore, the deterioration point of the deteriorated cell (cell 19-4) increases earlier than the deterioration point of the normal cell, and by the processing in steps S114 and S118 in FIG. Deterioration determination can be performed.

  In this example, the degree of deterioration of each cell 19-k is determined based on the number of target cells 19-i in each equalization control. The degree of deterioration may be determined based on both the number of target cells 19-j. Specifically, the magnitude relationship between the number of target cells 19-i and the number of non-target cells 19-j in each round of equalization control, that is, the target cell 19-i in each round of equalization control is the non-target cell 19-j The degree of deterioration of each cell 19-k may be determined based on whether it is more or less than j.

  For example, when the number of target cells 19-i in each equalization control is smaller than the number of non-target cells 19-j, a deterioration point is additionally provided to the target cell 19-i (the deterioration point Pi is incremented). . On the other hand, when the number of target cells 19-i in each equalization control is larger than the number of non-target cells 19-j, conversely, a deterioration point is additionally provided to the non-target cell 19-j (deterioration point Pj Is incremented). That is, when the number of target cells 19-i is smaller than the number of non-target cells 19-j, the degree of deterioration of the target cell 19-i becomes higher than the degree of deterioration of the non-target cells 19-j, and the target cell 19-i Is larger than the number of non-target cells 19-j, the relative deterioration degree of each cell 19-k is set such that the deterioration degree of the non-target cell 19-j is higher than the deterioration degree of the target cell 19-i. May be determined. Thereby, the same operation and effect as in the above-described example (FIG. 5) can be obtained.

  Next, another example of the deterioration determination processing of the capacitor 19 by the controller 30 will be described with reference to FIG.

  FIG. 8 is a flowchart schematically showing another example of the deterioration determination process of the capacitor 19 by the controller 30. The process according to this flowchart may be repeatedly executed at predetermined time intervals during the operation of the shovel, that is, during the period from the key-on to the key-off of the shovel, similarly to the flowchart of FIG.

  The processing in steps S202 to S208 and S216 to S222 in this flowchart is the same as the processing in steps S102 to S108 and S114 to 120 in the flowchart in FIG. Therefore, in the following description, description will be made focusing on portions different from the flowchart of FIG.

  In step S210, the controller 30 discharges the determined target cell 19-i, that is, performs equalization control on the target cell 19-i. If there are a plurality of determined target cells 19-i, equalization control is performed for each target cell 19-i. At this time, the controller 30 causes the target cell 19-i to be discharged with the predetermined time T as an upper limit. Specifically, the controller 30 transmits a forced balance signal including an instruction to discharge to the monitoring IC 142 with the predetermined time T as an upper limit, and the monitoring IC 142 performs equalization control according to the forced balance signal. The monitoring IC 142 transmits an ON signal to the gate of the balancing FET 19-i, and determines whether the cell voltage Vi of the target cell 19-i decreases to the target voltage Vtgt or the predetermined time T elapses. Until the condition is established, the target cell 19-i is short-circuited and the target cell 19-i is discharged.

  In step S212, the controller 30 determines whether the equalization of the target cell 19-i has been completed, that is, whether or not all the cell voltages Vi of the target cell 19-i determined in step S208 have decreased to the target voltage Vtgt. Is determined. When the cell voltages Vi of all the target cells 19-i have decreased to the target voltage Vtgt, the controller 30 proceeds to Step S214. On the other hand, when the cell voltages Vi of all the target cells 19-i have not dropped to the target voltage Vtgt, the controller 30 returns to step S212, and the cell voltage Vi of the target cells 19-i drops to the target voltage Vtgt. The equalization control is performed again for those that have not been performed (retry).

  The controller 30 stores the number of retries for equalization control in an internal memory or the like for each target cell 19-i.

  In step S214, the controller 30 indicates the degree of deterioration of the target cell 19-i based on the number of target cells 19-i and the number of discharges of each target cell 19-i (that is, the number of retries of equalization control). The index value (deterioration point Pi) is incremented. Specifically, the controller 30 increases the increment value of the deterioration point Pi of each target cell 19-i as the number of target cells 19-i in the current equalization control is smaller. Further, the controller 30 increases the increment value of the deterioration point Pi of each target cell 19-i as the number of retries of each target cell 19-i in the current equalization control increases. That is, the controller 30 sets the degree of deterioration to be higher as the number of target cells 19-i in the current equalization control is smaller, and to be higher as the number of retries of the current equalization control is larger. , A deterioration point is additionally provided to the target cell 19-i. For example, when the number of target cells 19-i in each equalization control is one, the deterioration point given when the number of target cells 19-i is one is the maximum value, every time the number of target cells 19-i increases by one, all target cells 19-i increase. -The deterioration point given to i may be reduced by a predetermined amount. In addition, the deterioration point given when the number of target cells 19-i in each equalization control is one is set as a maximum value, and the deterioration points given to all target cells 19-i are the maximum values. It may be a value divided by the number of target cells 19-i. In addition, a mode in which a predetermined number of deterioration points are further given to each target cell 19-i each time the number of retries increases by one.

  The deterioration point Pk of each cell 19-k is stored in the nonvolatile internal memory of the controller 30. Further, the deterioration point Pk of each cell 19-k is set to “0” when the capacitor 19 is not used, and as the usage time of the capacitor 19 by the operation of the shovel advances and the number of equalization controls increases, It is sequentially updated in the process of step S214. When it is determined that any of the cells 19-k is relatively deteriorated and the cells 19-k are replaced, the deterioration points Pk of all the cells 19-k are initialized to "0". Is done.

  As described above, in this example, the controller 30 sets the capacitor based on the discharge time (the number of retries) of the target cell 19-i in addition to the number of the target cells 19-i when the equalization control is performed by the monitoring IC 142. The presence or absence of deterioration of the cell 19 and the degree of deterioration of each cell 19-k are determined. Specifically, each time the monitoring IC 142 performs the equalization control, the controller 30 sets the index value (deterioration point) indicating the degree of deterioration such that the target cell 19-i becomes higher as the discharge time becomes longer. Is given. Then, the controller 30 determines whether or not the capacitor 19 has deteriorated and the degree of deterioration of each cell 19-k based on the integrated value (deterioration point Pk) of the deterioration points of each cell 19-k.

  Here, with reference to FIG. 9, the details of the processing of steps S214, S216, and S220 in FIG. 8 described above, that is, the details of the method of determining the deterioration of the capacitor 19 will be described.

  FIGS. 9A to 9C are diagrams for explaining a method of determining deterioration of each cell 19-k. Specifically, the deteriorated cells are subjected to equalization control, and the deterioration between cells is determined. FIG. 6 is a diagram illustrating an execution state of equalization control when there is a difference in absolute degree of deterioration in the embodiment.

  In the example shown in FIG. 9, the number of cells 19-k included in the capacitor 19 is six (that is, n = 6). In the example shown in FIG. 9, the number of deteriorated cells is two (cells 19-3 and 19-4). In the example shown in FIG. 9, the target voltage Vtgt is the same as the cell voltage Vk of the normal cell.

  As shown in FIG. 9A, when the target of equalization control is a deteriorated cell, there may be a case where a difference occurs in the absolute degree of deterioration between the deteriorated cells. As shown in FIG. 5 described above, as the degree of deterioration increases, the rising speed (gradient) of the cell voltage Vk with respect to the charging time becomes steeper, and therefore, of the equalization target cells 19-3 and 19-4, The difference between the cell 19-4 and the cell voltage (target voltage Vtgt) of the normal cell is larger in the cell 19-4 having a higher degree of actual deterioration than in the cell 19-3.

  In such a case, as described above, if the upper limit of the discharging time in the equalization control is set to the predetermined time T, as shown in FIG. In the first equalization control, the cell voltage V3 decreases to the target voltage Vtgt. On the other hand, in the cell 19-4 having a high degree of deterioration among the deteriorated cells, the cell voltage V4 does not decrease to the target voltage Vtgt in the first equalization control. Therefore, the equalization control (retry) is performed again on the cell 19-4 having a high degree of deterioration, and as shown in FIG. 9C, the cell voltage V4 drops to the target voltage Vtgt by the second equalization control. I do.

  As described above, when the upper limit (predetermined time T) of the discharging time in the equalization control is set, when the deteriorated cell is a target of the equalization control, the target cell 19-i having a higher absolute degree of deterioration has a larger number of retries. Increase. Therefore, as described above, a deterioration point is additionally given to the target cell 19-i so as to increase as the number of discharges (the number of retries) in the equalization control increases, whereby a deteriorated cell having a high degree of deterioration is increased. The more the deterioration points increase, the more the deterioration points increase. Therefore, it is possible to consider the absolute degree of deterioration, for example, to determine the difference in the degree of deterioration among the deteriorated cells, or to determine the absolute difference in the degree of deterioration between the deteriorated cell and the normal cell. can do.

  Instead of the number of discharges (the number of retries), in the equalization control, the time until the cell voltage Vi of the target cell 19-i reaches the target voltage Vtgt (that is, the time for discharging) is measured. The configuration may be such that a deterioration point is additionally provided to the target cell 19-i so as to increase as the length increases. Thereby, the same operation and effect as those of the other example (FIG. 8) described above can be obtained.

  Further, in this example, in each equalization control, an additional assignment of a deterioration point based on the discharge time is performed regardless of whether the target cell 19-i is a normal cell or a deteriorated cell. Is not limited. That is, in each equalization control, only when the target cell 19-i is a deteriorated cell, that is, when the number of the target cells 19-i is smaller than the number of the non-target cells 19-j, it is based on the discharge time. Additional provision of a deterioration point may be performed.

  Further, in the present example, as described above, the degree of deterioration of each cell 19-k may be determined based on whether the number of target cells 19-i in each round of equalization control is greater or less than the number of non-target cells 19-j. . Specifically, when the number of target cells 19-i in each equalization control is smaller than the number of non-target cells 19-j, a deterioration point is additionally given to the target cell 19-i (the deterioration point Pi is set to Increment). On the other hand, when the number of target cells 19-i in each equalization control is larger than the number of non-target cells 19-j, conversely, a deterioration point is additionally provided to the non-target cell 19-j (deterioration point Pj Is incremented). Thereby, the same operation and effect as those of the other example (FIG. 8) described above can be obtained. In this case, when the number of target cells 19-i in each equalization control is smaller than the number of non-target cells 19-j, that is, when the target cell 19-i is a deteriorated cell, the target cell 19-i is determined based on the discharge time. The deterioration point is additionally provided to the cell 19-i. On the other hand, when the number of target cells 19-i is larger than the number of non-target cells 19-j, that is, when the target cell 19-i is a normal cell, the deterioration point based on the discharge time of the target cell 19-i is determined. Do not grant.

  As described above, the embodiments for carrying out the present invention have been described in detail. However, the present invention is not limited to the specific embodiments, and various modifications may be made within the scope of the present invention described in the appended claims. Can be modified and changed.

  For example, in the above-described embodiment, the power storage device (capacitor 19) to be subject to deterioration determination is mounted on the shovel, but is not limited to this configuration. For example, the target of the deterioration determination may be a power storage device mounted on an electric vehicle or a stationary power storage device.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 1A, 1B Hydraulic motor 2 Slewing mechanism 3 Upper revolving body 4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cabin 11 Engine 12 Motor generator 13 Reduction gear 14 Main pump 15 Pilot pump 16 High pressure Hydraulic line 17 Control valve 18, 18A, 18B Inverter 19 Capacitor (power storage device)
19-1 to 19 to n, 19-k Capacitor cells (power storage cells)
19-i Target cell 19-j Non-target cell 21 Turning motor 22 Resolver 23 Mechanical brake 24 Turning reducer 25 Pilot line 26 Operating device 26A, 26B Lever 26C Pedal 27, 28 Hydraulic line 29 Pressure sensor 30 Controller 100 Step-up / step-down converter 110 DC Bus 111 DC Bus Voltage Detector 112 Capacitor Voltage Detector 113 Capacitor Current Detector 120 Power Storage System 140 Capacitor Control Circuit (Equalization Control Circuit)
142 Monitoring IC
144-1 to 144- (n + 1) Wiring 146-1 to 146-n Balance FET
148-1 to 148-n Discharge resistance Pk Deterioration point (integrated value of index value indicating degree of deterioration)
Vk cell voltage (voltage between electrodes)

Claims (6)

A deterioration determination device for a power storage device including three or more predetermined number of power storage cells connected in series,
An equalization control circuit configured to discharge from one or a plurality of target cells smaller than the predetermined number, the storage cells having a relatively high inter-electrode voltage among the predetermined number of storage cells,
For each of the predetermined number of storage cells, a degradation determination unit that determines a relative degradation degree,
The deterioration determination unit determines a degree of deterioration of each of the predetermined number of power storage cells based on the number of the target cells when the equalization control by the equalization control circuit is performed.
Deterioration determination device for power storage device. Each time the equalization control is performed by the equalization control circuit, the deterioration determination unit assigns, to the target cell, an index value indicating a deterioration degree that increases as the number of the target cells decreases, and Determining the degree of deterioration of each of the predetermined number of power storage cells based on an integrated value of the index value for each of the predetermined number of power storage cells;
The power storage device deterioration determination device according to claim 1. The deterioration determination unit determines a degree of deterioration of each of the predetermined number of power storage cells based on a discharge time of the target cell when the equalization control by the equalization control circuit is performed.
The power storage device deterioration determination device according to claim 2. Each time the equalization control is performed by the equalization control circuit, the deterioration determination unit assigns the index value to the target cell such that the index value increases as the discharge time increases.
The power storage device degradation determination device according to claim 3. The deterioration determination unit, based on whether the number of the target cells when the equalization control by the equalization control circuit is performed is larger or smaller than the number of non-target cells that are power storage cells other than the target cells, Determining the degree of deterioration of each of the predetermined number of storage cells;
The power storage device deterioration determination device according to claim 1. The deterioration determining unit, when the number of the target cell when the equalization control by the equalization control circuit is made smaller than the number of the non-target cell, the deterioration degree of the deterioration degree is the non-target cell of the target cell becomes higher than the case where the number of the target cell is greater than the number of the non-target cells, wherein such deterioration degree of the non-target cell is higher than the deterioration degree of the target cells, of each of the predetermined number of storage cells Judge the degree of deterioration,
The power storage device degradation determination device according to claim 5.

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