JP2017181260A - Deterioration assessing device for power storage devices - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deterioration assessing device for power storage devices that can easily assess the degree of deterioration of each power storage cell contained in a power storage device.SOLUTION: A deterioration assessing device for power storage devices comprising serially connected power storage cells of a prescribed number of at least three is equipped with an equalization control circuit that causes one object cell or multiple such cells fewer than the prescribed number, which are power storage cells relatively high in inter-electrode voltage, and a deterioration assessing unit that assesses the relative degree of deterioration of each of the prescribed number of power storage cells. The deterioration assessing unit assesses the degree of deterioration of each of the prescribed number of power storage cells on the basis of the number of object cells at the time of equalization control by the equalization control circuit.SELECTED DRAWING: Figure 5

Description

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

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

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

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

International Publication No. 2013/121916

  However, in the technique disclosed in Patent Document 1, since it is necessary to calculate the capacitance without charging and discharging the capacitor, the opportunities are limited, and the deterioration degree of each storage cell is easily determined. It may not be possible.

  Then, in view of the said subject, it aims at providing the degradation determination apparatus of the electrical storage apparatus which can determine easily the deterioration degree of each electrical storage cell contained in an electrical storage apparatus.

In order to achieve the above object, in one embodiment,
A degradation determination device for a power storage device including a predetermined number of power storage cells of 3 or more connected in series,
An equalization control circuit for discharging from one or a plurality of target cells less than the predetermined number among the predetermined number of power storage cells, which is a power storage cell having a relatively high inter-electrode voltage;
For each of the predetermined number of storage cells, a deterioration determination unit that determines a relative deterioration degree,
The deterioration determination unit determines a deterioration degree of each of the predetermined number of storage cells based on the number of the target cells when equalization control is performed by the equalization control circuit;
A deterioration determination device for a power storage device is provided.

  According to the embodiment described above, it is possible to provide a deterioration determination device for a power storage 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 an excavator It is a figure which shows an example of a structure of the drive system of an shovel. It is a circuit diagram which shows an example of a structure of the electrical storage system of an excavator. It is a circuit diagram which shows an example of a structure of a capacitor. It is a flowchart which shows an example of a deterioration determination process roughly. It is a figure explaining the voltage characteristic of a normal cell and a deterioration cell. It is a figure explaining the deterioration determination method of each capacitor cell. It is a flowchart which shows schematically the other example of deterioration determination processing. It is a figure explaining the deterioration determination method of each capacitor cell.

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

  First, with reference to FIGS. 1-4, the structure of the shovel which concerns on this embodiment is demonstrated.

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

  As shown in FIG. 1, an upper swing body 3 is mounted via a swing mechanism 2 on a lower traveling body 1 that is hydraulically driven by hydraulic motors 1 </ b> A and 1 </ b> B (see FIG. 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 hydraulically driven by a boom cylinder 7, an arm cylinder 8 and a bucket cylinder 9 as hydraulic actuators, respectively. Further, the upper swing body 3 is provided with a cabin 10 on which an operator is boarded, and an engine 11 (see FIG. 2) and the like.

  FIG. 2 is a block diagram showing the configuration of the excavator drive system. 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.

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

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

  The motor generator 12 can assist the engine 11 and drive the main pump 14 and the pilot pump 15 via the speed reducer 13. In addition, the motor generator 12 can generate power with the power of the engine 11 transmitted through the speed reducer 13.

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

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

  The control valve 17 is a control device that controls the hydraulic system in accordance with 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 (hereinafter may be referred to collectively or individually as “hydraulic actuators”) for lower traveling body 1 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 hydraulic actuator, and includes a plurality of hydraulic control valves for controlling the flow rate (pressure) of hydraulic oil supplied from the main pump 14 to each of the hydraulic actuators and the flow direction. 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.

  Instead of the capacitor 19, another form of power source capable of transferring power such as a chargeable / dischargeable secondary battery such as a lithium ion battery may be employed.

  An operation device 26 is connected to the pilot pump 15 through a pilot line 25. The operating device 26 includes levers 26A and 26B and a pedal 26C, and includes a lower traveling body 1 (hydraulic motors 1A and 1B), an upper revolving body 3 (a turning electric motor 21 described later), a boom 4 (boom cylinder 7), and an arm. 5 (arm cylinder 8), 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 the hydraulic line 27 and the hydraulic line 28, respectively. As a result, a pilot signal (pilot pressure) corresponding to the operating state of the lower traveling body 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 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 body 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 excavator according to the present embodiment, the turning mechanism 2 is motorized, and the turning electric motor 21 that drives the upper turning body 3 via the turning mechanism 2 is provided. Further, the turning electric motor 21 converts kinetic energy into electric energy and performs regenerative power generation when the upper turning body 3 turns and decelerates. The turning electric motor 21 is connected to the power storage system 120 via the inverter 18B. A resolver 22, a mechanical brake 23, and a turning speed reducer 24 are connected to the rotating shaft 21 </ b> A of the turning electric motor 21.

  The controller 30 is a control device that performs drive control of the shovel. The controller 30 is constituted by, for example, an arithmetic processing unit (microcomputer) including a CPU, a ROM, and the like, and various drive controls are realized by executing various drive control programs stored in the ROM on the CPU. .

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

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

  In addition, the controller 30 performs operation control of the motor generator 12 (switching between electric (assist) operation or power generation operation) and charge / discharge control of the capacitor 19 by drivingly controlling the step-up / down converter 100 (see FIG. 3). I do. The controller 30 is based on the charge state 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 (power running 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 for the capacitor 19. Details will be described later.

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

  The power storage system 120 includes a capacitor 19, a buck-boost converter 100, a DC bus 110, and the like.

  The DC bus 110 controls transmission and reception of electric power among the capacitor 19, the motor generator 12, and the turning electric motor 21. The capacitor 19 is provided with a capacitor voltage detector 112 and a capacitor current detector 113 that detect the voltage value and 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 step-up / step-down 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 according to the operating state of the motor generator 12 and the turning electric motor 21. . The DC bus 110 is disposed between the inverters 18 </ b> A and 18 </ b> B and the buck-boost converter 100, and the capacitor 19, the motor generator 12, and the turning electric motor 21 exchange power via the DC bus 110.

  Switching control between the step-up / 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 showing an example of the configuration of the capacitor 19.

  Capacitor 19 includes a predetermined number (n pieces) of 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 body 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. However, the cells connected in series are defined as one group (cell group), and a plurality of cell groups are included. The structure connected in parallel may be sufficient. 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 measuring function) and an equalizing function (also referred to as a cell balance function) for equalizing the voltage of each cell.

  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 the two wirings 144-k, 144- (k + 1).

  A balancing 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 body 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 body 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 body 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 to 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 cell 19-k is discharged, and the discharge energy is consumed by the discharge resistor 148-k. As a result, when an imbalance occurs in the voltage between electrodes (hereinafter referred to as the cell voltage Vk), that is, the capacitance between the cells 19-k, the cell 19- having a relatively high cell voltage Vk. Unbalance can be eliminated by discharging k. Therefore, it is possible to avoid a situation in which the capacity of the capacitor 19 cannot be completely used due to the imbalance of the cell voltage Vk between the cells 19-k.

  When the 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).

  In addition, the monitoring IC 142 performs equalization control for canceling the imbalance of the cell voltage Vk between the cells 19-k in response to 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 is 1 to n) to be subjected to equalization control. The integer value between) is short-circuited. At this time, since the discharge current from the target cell 19-i becomes a minute current due to the action of the discharge resistor 148-i, the cell voltage Vi of the target cell 19-i gradually decreases.

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

  In this embodiment, the controller 30 executes the deterioration determination process for the capacitor 19, 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 showing an example of the deterioration determination process for the capacitor 19 by the controller 30. As will be described below, the deterioration determination process for the capacitor 19 in the present embodiment is executed in a manner that includes the equalization control of the target cell 19-i as a unit. The processing according to this flowchart may be repeatedly executed at predetermined time intervals during the operation of the shovel, that is, from the key on to the key off of the shovel.

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

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

  In step S106, the controller 30 sets a target voltage Vtgt when the voltage of the target cell 19-i is reduced by equalization control. The target voltage Vtgt may be a predetermined voltage value (constant) or may be 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 that is 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. When 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 reception of 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.

  The monitoring IC 142 confirms that the target cell 19-i has decreased to the target voltage Vtgt by acquiring the cell voltage Vi of the target cell 19-i constantly or periodically when performing equalization control. Then, an OFF signal is transmitted to the gate of the balancing FET 19-i. Further, the monitoring IC 142 may calculate a time for reducing the voltage to the target voltage Vtgt in advance, and may 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 deterioration points to the target cell 19-i so that the degree of deterioration increases as the number of target cells 19-i in the current equalization control decreases. For example, every time the number of target cells 19-i increases by using the maximum degradation point given when the number of target cells 19-i in each equalization control is one, the target cell 19-i It is possible to reduce the deterioration points given to the item 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 the maximum value, and the deterioration point given to the target cell 19-i is 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 points Pk of the respective cells 19-k are all set to “0” when the capacitor 19 is not used, and the use time of the capacitor 19 by the operation of the excavator advances, and the number of equalization control increases. It is sequentially updated in the process of step S112. That is, every time equalization control is performed, the controller 30 gives the target cell 19-i an index value indicating the degree of deterioration that increases as the number of the target cells 19-i decreases, and 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 it is determined that any one of the cells 19-k is relatively deteriorated and the cell 19-k is replaced, the deterioration points Pk of all the cells 19-k are “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 index value). Specifically, the controller 30 determines that the capacitor 19 is deteriorated when the variation in the deterioration progress 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 greater than a predetermined threshold value Pth1.

  In step S116, the controller 30 determines whether or not the 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. If the controller 30 determines that the capacitor 19 has not deteriorated, the current process ends.

  In step S118, based on the deterioration point Pk of each cell 19-k, the controller 30 has abnormally progressed deterioration of the cell 19-k of the capacitor 19 (that is, relatively deteriorated). A cell 19-k (hereinafter referred to as a degraded cell) is specified. Specifically, when the deterioration point Pk is equal to or greater than the predetermined threshold value Pth2, or when the deterioration point Pk is different from the minimum value Pmin by the predetermined threshold value Pth1 or more, the controller 30 You may determine that it has deteriorated relatively.

  In step S120, the controller 30 issues an alarm indicating that the capacitor 19 has deteriorated due to a display on a display or an indicator (both not shown) arranged in the cabin 10 or sound through a speaker (not shown). Do. At this time, the controller 30 may display on the display or the like in the cabin 10 which one of all the cells 19-k of the capacitor 19 is a deteriorated cell. As a result, the excavator operator or the operator who maintains the excavator can be urged to replace the deteriorated cell of the capacitor 19.

  Thus, in this example, the controller 30 determines whether or not the capacitor 19 has deteriorated based on the number of 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 is determined. Specifically, each time the equalization control is performed by the monitoring IC 142, the controller 30 indicates an index value (deterioration) indicating a degree of deterioration that increases as the number of the target cells 19-i decreases with respect to the target cells 19-i. Points). And the controller 30 determines the presence or absence of deterioration of the capacitor 19 and the deterioration degree of each cell 19-k based on the integrated value (deterioration point Pk) of the deterioration point of each cell 19-k. Therefore, according to the present embodiment, it is possible to determine the deterioration of the power storage device accompanying the normal equalization control. Therefore, the opportunity for determining the deterioration of the power storage device is not limited, and it is possible to easily determine the deterioration of the power storage device.

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

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

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

  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 an abnormal cell (dotted line in the figure) changes with a relatively steep slope with respect to the charging time. Therefore, in a state where the charging rate of the capacitor 19 is relatively high, since it corresponds to a region on the right side (region where charging time is long) from the intersection Ps between the solid line and the dotted line in the figure, the target cell 19-i for equalization control is It becomes a degraded cell. On the other hand, when the charging rate of the capacitor 19 is relatively low, it corresponds to the region on the left side of the intersection Ps between the solid line and the dotted line (region where the charging time is short) in the figure, and therefore the target of equalization control is a normal cell. . That is, the target cell 19-i in each equalization control is either a normal cell or an abnormal cell.

  The number of deteriorated cells is normally relatively small with respect to the number of all cells 19-k of the capacitor 19 (in this example, one cell 19-4). Therefore, as shown in FIG. 7A, when the deteriorated cell becomes the target of equalization control, the number of target cells 19-i is relatively small with respect to the total number (dotted line frame in the figure). That is, the number of target cells 19-i is based on the number of cells 19-k other than the target cell 19-i (hereinafter referred to as non-target cells 19-j (j is an integer value between 1 and n)). Less. On the other hand, as shown in FIG. 7B, when a normal cell is a target of equalization control, the number of target cells 19-i is relatively large with respect to the total number (dotted line 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 line frame in the figure). Therefore, as described above, a deterioration point is additionally given to the target cell 19-i so as to increase as the number of target cells 19-i in each equalization control decreases (the deterioration point Pi is incremented). Thus, the deterioration point Pk of the deteriorated cell is likely to increase, and the deterioration point Pk of the normal cell is difficult to increase. Therefore, each time the equalization control is executed, the deterioration point Pi of the target cell 19-i is updated (integrated), whereby the deterioration of the capacitor 19 (specifically, the deterioration progress of each cell 19-k progresses). Variation) and the relative deterioration of each cell 19-k can be determined.

  For example, in each equalization control, when there is one target cell 19-i, 5 points are additionally given as deterioration points (the deterioration point Pi is incremented by 5 points), and one target cell 19-i is provided. A method is employed in which the deterioration points given to the target cell 19-i are decremented one by one each time the number increases. In this case, in the example shown in FIG. 7, when the deteriorated cell (cell 19-4) is subjected to equalization control, 5 points are assigned to the deteriorated cell as deterioration points. On the other hand, when normal cells (cells 19-1 to 19-3 and cells 19-5 and 19-6) are subjected to equalization control, only one point is given to the normal cell as a deterioration point. Moreover, since the capacitor 19 is normally 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 the deterioration determination of the capacitor 19 and the determination of the cell 19-4 are performed by the processing of steps S114 and S118 of 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, but the number of target cells 19-i in each time equalization control is not determined. The degree of deterioration may be determined based on both the number of target cells 19-j. Specifically, the size relationship between the number of target cells 19-i and the number of non-target cells 19-j in each equalization control, that is, the target cell 19-i in each time equalization control is the non-target cell 19-. The degree of deterioration of each cell 19-k may be determined based on whether it is greater than 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 given 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, deterioration points are additionally given to the non-target cells 19-j (deterioration points 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 degradation level of the target cells 19-i is higher than the degradation level of the non-target cells 19-j, and the target cell 19-i When the number of cells 19-j is larger than the number of non-target cells 19-j, the relative deterioration degree of each cell 19-k is set so 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 effect | action and effect similar to the example (FIG. 5) mentioned above can be acquired.

  Next, another example of the deterioration determination process for 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 for the capacitor 19 by the controller 30. Similar to the flowchart of FIG. 5, the processing according to this flowchart may be repeatedly executed at predetermined time intervals during the operation of the excavator, that is, from the key-on to the key-off of the shovel.

  The processes in steps S202 to S208 and S216 to S222 in this flowchart are the same as the processes in steps S102 to S108 and S114 to 120 in the flowchart in FIG. For this reason, in the following description, the description will focus on parts 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. When 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 discharges the target cell 19-i with the predetermined time T as an upper limit. Specifically, the controller 30 transmits a forced balance signal including an instruction to discharge 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 the condition that either the cell voltage Vi of the target cell 19-i drops to the target voltage Vtgt or the predetermined time T elapses is met. Until it 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 equalization of the target cell 19-i has been completed, that is, whether all the cell voltages Vi of the target cell 19-i determined in step S208 have decreased to the target voltage Vtgt. Determine whether. When the cell voltage Vi of all the target cells 19-i has 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 decreased to the target voltage Vtgt, the controller 30 returns to step S212, and the cell voltage Vi of the target cells 19-i decreases to the target voltage Vtgt. The equalization control is performed again for those not yet performed (retry).

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

  In step S214, the controller 30 represents 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 times of equalization control retries). 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 decreases. 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 increases the degree of deterioration as the number of target cells 19-i in the current equalization control decreases, and increases as the number of retries of the current equalization control increases. The deterioration point is additionally given to the target cell 19-i. For example, every time the number of target cells 19-i is increased by one, the deterioration point given when the number of target cells 19-i in each equalization control is one is the maximum value. It may be an aspect in which the deterioration points given to -i are reduced by a predetermined amount. Moreover, the deterioration point given when the number of target cells 19-i in each equalization control is one is the maximum value, and the deterioration points given to all the target cells 19-i are the maximum values. It may be a value divided by the number of target cells 19-i. Further, a predetermined amount of deterioration points may be given to each target cell 19-i every time the number of retries increases by one.

  Note that the deterioration point Pk of each cell 19-k is stored in a nonvolatile internal memory of the controller 30. Further, the deterioration points Pk of the respective cells 19-k are all set to “0” when the capacitor 19 is not used, and the use time of the capacitor 19 by the operation of the excavator advances, and the number of equalization control 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 cell 19-k is replaced, the deterioration points Pk of all the cells 19-k are initialized to “0”. Is done.

  Thus, in this example, the controller 30 determines the capacitor based on the discharge time (the number of retries) of the target cell 19-i in addition to the number of target cells 19-i when the equalization control by the monitoring IC 142 is performed. The presence or absence of 19 deterioration and the deterioration degree of each cell 19-k are determined. Specifically, each time the equalization control is performed by the monitoring IC 142, the controller 30 indicates an index value (degradation point) that indicates the degree of deterioration so that the discharge time becomes higher for the target cell 19-i. Is granted. And the controller 30 determines the presence or absence of deterioration of the capacitor 19 and the deterioration degree of each cell 19-k based on the integrated value (deterioration point Pk) of the deterioration point of each cell 19-k.

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

  FIGS. 9A to 9C are diagrams illustrating a method for determining the deterioration of each cell 19-k. Specifically, the deteriorated cell is a target of equalization control, and between the deteriorated cells. It is a figure showing the execution condition of equalization control when there is a difference in absolute deterioration level.

  In the example shown in FIG. 9, the number of cells 19-k included in the capacitor 19 is six (ie, n = 6). In the example shown in FIG. 9, there are two deteriorated cells (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 difference in the absolute deterioration degree between the deteriorated cells. As shown in FIG. 5 described above, as the degree of deterioration increases, the rate of increase (inclination) of the cell voltage Vk with respect to the charging time becomes steeper. The cell 19-4 having a higher degree of general deterioration has a larger deviation from the cell voltage (target voltage Vtgt) of the normal cell than the cell 19-3.

  In such a case, as described above, when 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, the cell 19-4 having a high degree of deterioration among the deteriorated cells does not drop the cell voltage V4 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 the cell voltage V4 is reduced to the target voltage Vtgt in the second equalization control as shown in FIG. 9C. To do.

  Thus, when the upper limit (predetermined time T) of the discharge time in the equalization control is provided, when the deteriorated cell is the target of the equalization control, the target cell 19-i having a higher absolute deterioration degree has the number of retries. Will increase. Therefore, as described above, a deteriorated cell having a high degree of deterioration by additionally giving a deterioration point to the target cell 19-i so as to increase as the number of discharges (retry number) in the equalization control increases. The deterioration point tends to increase. Therefore, it is possible to consider the absolute deterioration level, for example, to determine the difference in deterioration level among the deteriorated cells, or to determine the absolute difference in deterioration level 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 deterioration points are additionally given to the target cell 19-i so as to increase as the length increases. Thereby, the effect | action and effect similar to the other example (FIG. 8) mentioned above can be acquired.

  Further, in this example, in each equalization control, the deterioration point based on the discharge time is additionally provided regardless of whether the target cell 19-i is a normal cell or a deterioration 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 target cells 19-i is smaller than the number of non-target cells 19-j, based on the discharge time. Additional provision of deterioration points may be performed.

  In this example, as described above, the degree of deterioration of each cell 19-k may be determined based on whether the target cell 19-i in each equalization control is more or less than the non-target cell 19-j. . Specifically, when the number of target cells 19-i in each round of 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 (deterioration point Pi is set). 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, deterioration points are additionally given to the non-target cells 19-j (deterioration points Pj). Is incremented). Thereby, the effect | action and effect similar to the other example (FIG. 8) mentioned above can be acquired. In this case, when the number of target cells 19-i in each round of 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 is based on the discharge time. Further deterioration points are additionally given to the cells 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. Do not grant.

  As mentioned above, although the form for implementing this invention was explained in full detail, this invention is not limited to this specific embodiment, In the range of the summary of this invention described in the claim, various Can be modified or changed.

  For example, in the embodiment described above, the power storage device (capacitor 19) to be subjected to deterioration determination is mounted on a shovel, but is not limited to this configuration. For example, the degradation determination target 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 Turning mechanism 3 Upper turning body 4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cabin 11 Engine 12 Motor generator 13 Reducer 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-n, 19-k capacitor cell (storage cell)
19-i target cell 19-j non-target cell 21 electric motor for turning 22 resolver 23 mechanical brake 24 turning reduction gear 25 pilot line 26 operating device 26A, 26B lever 26C pedal 27, 28 hydraulic line 29 pressure sensor 30 controller 100 step-up / down converter 110 DC bus 111 DC bus voltage detection unit 112 capacitor voltage detection unit 113 capacitor current detection unit 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 balancing FET
148-1 to 148-n Discharge resistance Pk Deterioration point (integrated value of index values indicating the degree of deterioration)
Vk cell voltage (interelectrode voltage)

Claims (6)

A degradation determination device for a power storage device including a predetermined number of power storage cells of 3 or more connected in series,
An equalization control circuit for discharging from one or a plurality of target cells less than the predetermined number among the predetermined number of power storage cells, which is a power storage cell having a relatively high inter-electrode voltage;
For each of the predetermined number of storage cells, a deterioration determination unit that determines a relative deterioration degree,
The deterioration determination unit determines a deterioration degree of each of the predetermined number of storage cells based on the number of the target cells when equalization control is performed by the equalization control circuit;
A power storage device deterioration determination device. Each time the equalization control circuit performs equalization control, the deterioration determination unit gives an index value representing a degree of deterioration that increases as the number of target cells decreases to the target cell, and Determining the degree of deterioration of each of the predetermined number of storage cells based on the integrated value of the index values for each of the predetermined number of storage cells;
The deterioration determination device for a power storage device according to claim 1. The deterioration determination unit determines a deterioration degree of each of the predetermined number of power storage cells based on a discharge time of the target cell when equalization control is performed by the equalization control circuit.
The deterioration determination device for a power storage device according to claim 2. The degradation determination unit gives the index value so that the discharge time becomes longer as the discharge time becomes longer each time equalization control is performed by the equalization control circuit.
The deterioration determination device for a power storage device according to claim 3. The degradation determination unit is based on whether the number of target cells when equalization control by the equalization control circuit is performed is greater or less 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 deterioration determination device for a power storage device according to claim 1. When the number of the target cells when equalization control is performed by the equalization control circuit is less than the number of the non-target cells, the deterioration degree of the target cells is higher than the deterioration degree of the non-target cells, When the number of target cells is larger than the number of non-target cells, the degree of deterioration of each of the predetermined number of power storage cells is determined so that the degree of deterioration of the non-target cells is higher than the degree of deterioration of the non-target cells. ,
The degradation determination device for a power storage device according to claim 5.

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