JPWO2014033880A1 - Power storage device - Google Patents

Abstract

The power storage device according to the embodiment includes a power storage unit, a voltage detection unit, a charge / discharge unit, and a control unit. The power storage unit includes a plurality of power storage circuits that are connected in parallel through switches. The voltage detector detects each voltage of the plurality of power storage circuits. The charging / discharging unit supplies the discharge power from the power storage unit to the load, and charges the power storage unit with the power supplied from the power source. The control unit controls the switch and the charging / discharging unit so that the voltage difference between the power storage circuits falls within a predetermined range, and executes an adjustment process for charging or discharging the power storage circuit individually.

Description

  The disclosed embodiment relates to a power storage device.

  In recent years, in order to charge and discharge a large amount of power, a power storage device has been developed in which secondary batteries such as nickel metal hydride batteries and lithium ion batteries are connected in parallel. Examples of such a power storage device include a power storage device for power storage in combination with a power storage device for automobiles, and a new energy system such as a solar battery or wind power generation.

  The secondary battery deteriorates by repeated charge and discharge, and the internal resistance increases or the capacity at full charge decreases. Therefore, a technique has been proposed in which a plurality of secondary batteries are connected in parallel through respective switches and the switches are controlled to preferentially use secondary batteries having a low degree of deterioration among the plurality of secondary batteries ( For example, see Patent Document 1).

Japanese Patent No. 4572850

  However, in the conventional power storage device, a plurality of secondary batteries are connected in parallel by a switch, so that if the voltage difference between the secondary batteries is large, a large inrush current flows between the secondary batteries when the switch is turned on. There is.

  Such inrush current can be prevented by connecting an inrush prevention resistor in series with each secondary battery. However, when an inrush prevention resistor is arranged, there are problems in terms of installation space and cost. In addition, since the inrush prevention resistor generates heat due to the current, when the bypass conductor is used so as not to pass through the inrush prevention resistor except during the period when the inrush current flows, the bypass conductor placement space and cost are reduced. The challenges will increase.

  One aspect of the embodiment has been made in view of the above, and in a power storage device in which a plurality of secondary batteries are connected in parallel via a switch, a large inrush current can be prevented from flowing when the switch is controlled. An object is to provide a power storage device.

  A power storage device according to an aspect of an embodiment includes a power storage unit, a voltage detection unit, a charge / discharge unit, and a control unit. The power storage unit includes a plurality of power storage circuits connected in parallel through switches. The voltage detection unit detects each voltage of the plurality of power storage circuits. The charging / discharging unit supplies discharge power from the power storage unit to a load, and charges the power storage unit with power supplied from a power source. The controller controls the switch and the power storage circuit so that a voltage difference between the power storage circuits falls within a predetermined range, and executes an adjustment process for individually charging or discharging the power storage circuit.

  According to one aspect of the embodiment, in a power storage device in which a plurality of secondary batteries are connected in parallel via a switch, a power storage device that can prevent a large inrush current from flowing when the switch is controlled can be provided.

FIG. 1 is a diagram illustrating a configuration of a power storage device according to the embodiment. FIG. 2 is a diagram illustrating the configuration of the charge / discharge unit and the control unit illustrated in FIG. 1. FIG. 3 is a flowchart showing the flow of processing in the diagnosis / adjustment mode. FIG. 4 is a diagram for explaining a method of calculating the internal resistance value of the secondary battery. FIG. 5 is a diagram showing battery characteristics of the secondary battery.

  Hereinafter, embodiments of a power storage device disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

  FIG. 1 is a diagram illustrating a configuration of a power storage device according to the embodiment. As shown in FIG. 1, the power storage device 1 according to the embodiment is connected to a power source 2 and a load 3. The power storage device 1 accumulates electric power supplied from the power source 2 and supplies the accumulated electric power to the load 3.

  Here, an example in which the power source 2 is a DC power source and the load 3 is a DC load will be described. The power source 2 may be, for example, a DC power source obtained by converting an AC voltage output from an AC power source into a DC voltage by a converter circuit. The load 3 includes, for example, an inverter circuit and an AC motor, and operates the AC motor by converting DC power supplied from the power source 2 or the power storage device 1 into AC power by the inverter circuit and outputting the AC power to the AC motor.

  The power storage device 1 includes a power storage unit 10, a charge / discharge unit 11, a voltage detection unit 12, a current detection unit 13, a control unit 14, an operation unit 15, and a display unit 16.

  The power storage unit 10 includes secondary batteries 21a to 21c, which are power storage circuits, and switches 22a to 22c connected in series to the secondary batteries 21a to 21c, and the secondary batteries 21a to 21c via the switches 22a to 22c. Are connected in parallel.

  The secondary batteries 21a to 21c are, for example, nickel metal hydride batteries, lithium ion batteries, nickel cadmium batteries, and nickel ion polymer batteries. Hereinafter, the secondary batteries 21 a to 21 c may be collectively referred to as the secondary battery 21. The power storage circuit is not limited to the secondary battery 21 and may be a capacitor such as an electric double layer capacitor.

  The switches 22a to 22c are, for example, electromagnetic relays or semiconductor switches. These switches 22a to 22c are short-circuited by on-control and opened by off-control. In the following description, the switches 22a to 22c may be collectively referred to as the switch 22. Note that the switch 22 is on-controlled by a high level signal and off-controlled by a low-level signal, but may be a switch that is on-controlled by a low-level signal and off-controlled by a high-level signal. .

  In addition, although the voltage of the electrical storage part 10 is demonstrated as a thing lower than the voltage of the power supply 2, a voltage relationship is not limited to this relationship. In the example illustrated in FIG. 1, the power storage unit 10 is configured by connecting three secondary batteries 21 a to 21 c in parallel. However, the configuration of the power storage unit 10 is not limited to the configuration illustrated in FIG. 1. For example, the power storage unit 10 may have a configuration in which two or four or more secondary batteries 21 are connected in parallel, or may have a configuration in which secondary battery groups in which a plurality of secondary batteries 21 are connected in series are connected in parallel. The power storage unit 10 may be used.

  The charging / discharging unit 11 is, for example, a DC-DC converter, and steps down the voltage supplied from the power source 2 to a predetermined voltage value and supplies the voltage to the power storage unit 10. The voltage is boosted to a value and supplied to the load 3. When the voltage of power storage unit 10 is higher than the voltage of power supply 2, charging / discharging unit 11 boosts the voltage supplied from power supply 2 to a predetermined voltage value and supplies it to power storage unit 10. The voltage stored in is reduced to a predetermined voltage value and supplied to the load 3.

  The voltage detection unit 12 detects the voltage value Vdc between the positive electrode TP and the negative electrode TN of the power storage unit 10 (hereinafter, referred to as a detection voltage value Vdc), and the voltage value of the power storage unit 10 and the secondary battery. 21 voltage values are detected. In addition, it is good also considering the voltage detection part 12 as the voltage detection part 12 connected between the positive electrode of each secondary battery 21a-21c, and detecting the value of the voltage of each secondary battery 21a-21c.

  The current detection unit 13 detects the value Idc of the current flowing between the positive electrode TP of the power storage unit 10 and the charge / discharge unit 11 (hereinafter, referred to as a detected current value Idc), so that the power storage unit 10 and the secondary battery The value of the current flowing through 21 is detected. The current detection unit 13 is, for example, a current sensor that detects a current using a Hall element that is a magnetoelectric conversion element. In addition, it is good also considering the some current detection part which is connected in series with each secondary battery 21a-21c and detects the electric current of each secondary battery 21a-21c as the current detection part 13. FIG.

  The control unit 14 controls the charging / discharging unit 11 and the switch 22 to select and execute the four modes of the charging mode, the discharging mode, the diagnostic mode, and the adjustment mode.

  The charging mode is an operation mode in which the power supplied from the power source 2 or the regenerative power when the load 3 is in a regenerative operation is supplied to the power storage unit 10. The charging / discharging unit 11 changes the voltage of the power source 2 to a predetermined voltage. The voltage is stepped down and supplied to the power storage unit 10. For example, the control unit 14 executes the charging mode when the amount of charge of the power storage unit 10 falls below a predetermined threshold or when the load 3 enters a regenerative operation.

  The discharge mode is an operation mode in which the electric power accumulated in the power storage unit 10 is supplied to the load 3. The charge / discharge unit 11 boosts the voltage of the power storage unit 10 to a predetermined voltage and supplies the voltage to the load 3. For example, the control unit 14 executes the discharge mode when not in the charge mode.

  The diagnosis mode is an operation mode for diagnosing deterioration of the secondary battery 21 by detecting the internal resistance of each secondary battery 21 included in the power storage unit 10. In the diagnosis mode, the control unit 14 acquires information on the detected voltage value Vdc and the detected current value Idc from the charging / discharging unit 11, and based on the information, the internal resistance values Ri1 to Ri3 (hereinafter referred to as the respective secondary batteries 21a to 21c). , The internal resistance value Ri may be collectively referred to).

  The adjustment mode is an operation mode in which the voltage difference between the secondary batteries 21a to 21c is set to a predetermined range. In the adjustment mode, the control unit 14 performs charging / discharging control of the power storage unit 10 by the charging / discharging unit 11 based on information on the detected voltage value Vdc acquired from the charging / discharging unit 11, so that the secondary batteries 21 a to 21 c are connected. The voltage difference is set within a predetermined range. Such an adjustment mode is executed before the charge mode and the discharge mode based on a predetermined condition.

  The power storage device 1 according to the present embodiment performs adjustment mode to charge or discharge the secondary batteries 21a to 21c individually, and adjust the voltage difference between the secondary batteries 21a to 21c to be within a predetermined range. To do. Therefore, even if the switches 22a to 22c that connect the secondary batteries 21a to 21c are turned on and the secondary batteries 21a to 21c are electrically connected, the potential difference between the secondary batteries 21a to 21c. Because there is little, large inrush current does not flow.

  Therefore, it is possible to reduce or eliminate the problem of the arrangement space and cost of the inrush prevention resistor and the bypass conductor. For example, since the inrush current can be reduced and the resistance value of the inrush prevention resistor can be suppressed by setting the voltage difference between the secondary batteries 21 within a predetermined range, the inrush prevention resistor can be reduced in size. In addition, by making the voltage difference between the secondary batteries 21 close to zero, it is possible to provide a configuration in which no inrush prevention resistor or bypass conductor is provided.

  FIG. 2 is a diagram illustrating the configuration of the charging / discharging unit 11 and the control unit 14. First, the structure of the charging / discharging part 11 is demonstrated. As shown in FIG. 2, the charge / discharge unit 11 includes a communication unit 31, an input / output unit 32, a drive control unit 34, and a conversion circuit unit 35.

  The communication unit 31 transmits and receives information to and from the control unit 14. Information transmitted to the control unit 14 by the communication unit 31 is information indicating the state of the detected voltage value Vdc, the detected current value Idc, and the like, for example. Information received from the control unit 14 by the communication unit 31 is, for example, a control command or an operation command.

  The input / output unit 32 includes information on the detected voltage value Vdc detected by the voltage detecting unit 12, information on the detected current value Idc detected by the current detecting unit 13, and a detected voltage value Vpn detected by the voltage detector 51 described later. Enter the information. The input / output unit 32 outputs pulse signals Sig4 and Sig5 for driving the conversion circuit unit 35 to the conversion circuit unit 35 based on the PWM command output from the drive control unit 34.

  The drive control unit 34 generates a PWM command based on the operation command, the control command, the detected voltage value Vdc, the detected current value Idc, and the detected voltage value Vpn. The operation command includes, for example, a charge command indicating power conversion from the power source 2 side to the power storage unit 10 side, a discharge command indicating power conversion from the power storage unit 10 side to the load 3 side, and the like.

  The control command includes, for example, information specifying a voltage value or a current value, and the drive control unit 34 is a PWM for causing the charge / discharge unit 11 to output a voltage value or a current value specified by the control command. A signal is generated and output to the input / output unit 32.

  For example, when the type of operation command is a charge command and the current value I1 is specified in the control command, the drive control unit 34 generates a PWM command based on the specified current value I1 and the detected current value Idc. To do. For example, the drive control unit 34 uses, as a PWM command, a signal obtained by proportionally integrating the deviation by an internal proportional integrator so that the deviation between the designated current value I1 and the detected current value Idc becomes zero. Output to.

  For example, when the type of the operation command is a discharge command and the voltage value V1 is specified in the control command, the drive control unit 34 performs PWM based on the specified voltage value V1 and the detected voltage value Vpn. Generate directives. For example, the drive control unit 34 uses, as a PWM command, a signal obtained by proportionally integrating the deviation with an internal proportional integrator so that the deviation between the designated voltage value V1 and the detected voltage value Vpn becomes zero. Output to.

  The conversion circuit unit 35 includes switching elements 52 and 53, protection diodes D1 and D2, a choke coil L1, capacitors C1 and C2, and a voltage detector 51. The conversion circuit unit 35 receives pulse signals Sig4 and Sig5 from the input / output unit 32. Based on this, DC-DC conversion is performed. The switching elements 52 and 53 are self-extinguishing semiconductor elements such as IGBTs and MOSFETs, for example.

  In the charging mode, the switching element 53 is ON / OFF controlled by the pulse signal Sig4 from the input / output unit 32, and the conversion circuit unit 35 functions as a buck converter by the choke coil L1 and the capacitor C2. Thereby, the voltage of the power supply 2 is stepped down to the charging voltage of the power storage unit 10 and the power storage unit 10 is charged.

  On the other hand, in the discharge mode, the switching elements 52 and 53 are alternately turned on and off by the pulse signals Sig4 and Sig5 from the input / output unit 32, and the conversion circuit unit 35 serves as a boost converter by the choke coil L1 and the capacitor C1. Function. As a result, the voltage of the power storage unit 10 is boosted to a voltage value equal to or higher than the voltage value of the power source 2, and discharging from the power storage unit 10 to the load 3 is performed.

  Moreover, although the structure shown in FIG. 2 was demonstrated as an example as a bidirectional | two-way DC-DC converter, it is not limited to this structure. The conversion circuit unit 35 may have, for example, a configuration in which two unidirectional DC-DC converters are connected in parallel in opposite directions. Two conversion circuit units 35 are connected in series via an insulating transformer to the power storage unit 10. Alternatively, a circuit configuration that freely raises and lowers pressure may be used.

  Next, the configuration of the control unit 14 will be described. The control unit 14 includes a communication unit 41, an input / output unit 42, a storage unit 43, a command generation unit 44, and an internal resistance calculation unit 45.

  The communication unit 41 transmits / receives information to / from the communication unit 31 of the charge / discharge unit 11. Information transmitted to the charge / discharge unit 11 by the communication unit 41 is, for example, a control command or an operation command. Moreover, the information received from the charging / discharging part 11 by the communication part 41 is information, such as detected voltage value Vdc and detected current value Idc, for example.

  The input / output unit 42 receives an operation signal from the operation unit 15 and notifies the command generation unit 44 of the operation signal. The operation unit 15 includes an automatic / manual selection switch (not shown), a diagnostic button, and the like. The operation unit 15 outputs an operation signal corresponding to the operated button to the input / output unit 42. The automatic / manual selection switch is a switch for switching between automatic selection and manual selection. Note that the control unit 14 automatically selects the charging mode or the discharging mode at the time of automatic selection, stops the operation state until the diagnosis button is pressed at the time of manual selection, and puts the power storage device 1 in a standby state.

  Further, the input / output unit 42 outputs control signals Sig1 to Sig3 for performing on / off control of the switches 22a to 22c based on the switch command output from the command generation unit 44.

  The storage unit 43 stores various setting information and detection value information. The storage unit 43 stores setting information such as a supply voltage value Va, a charging current value Ia, a charging current value Ir, and an internal resistance threshold value Rmin, which will be described later. Further, the storage unit 43 stores information such as the detected voltage value Vdc and the detected current value Idc acquired from the charge / discharge unit 11 via the communication unit 41, for example. The charging current value Ir is information used in the diagnosis mode, and is set to a value smaller than the charging current value Ia.

  The command generation unit 44 generates an operation command, a control command, and a switch command based on the operation signal acquired from the input / output unit 42 and the setting information stored in the storage unit 43. The command generation unit 44 outputs the generated operation command and control command to the charge / discharge unit 11 via the communication unit 41. In addition, the command generation unit 44 outputs the generated switch command to the input / output unit 42.

  Specifically, the command generation unit 44 stores the operation command in which the type is the discharge command and the storage unit 43 when the operation signal of the automatic / manual selection switch indicates automatic selection and the discharge mode is selected. The control command for setting the supplied voltage value Va as the specified voltage value is output to the charge / discharge unit 11 via the communication unit 41.

  Further, the command generation unit 44, when the operation signal of the automatic / manual selection switch indicates automatic selection and selects the charging mode, the operation command with the type as the charging command and the charging current stored in the storage unit 43 A control command for setting the value Ia as the designated current value is output to the charge / discharge unit 11 via the communication unit 41.

  The command generation unit 44 outputs a switch command to the input / output unit 42 when the operation signal of the automatic / manual selection switch indicates manual selection and the operation signal of the diagnosis button indicates pressing of the diagnosis button. An operation command and a control command are output to the discharge unit 11, and a calculation command is output to the internal resistance calculation unit 45. Thereby, a diagnosis / adjustment mode to be described later is executed. The diagnosis / adjustment mode is an operation mode in which the diagnosis mode and the adjustment mode are continuously performed.

  When the internal resistance calculation unit 45 acquires a calculation command from the command generation unit 44, each of the secondary resistance calculation units 45 based on the detected voltage value Vdc and the detected current value Idc acquired from the charge / discharge unit 11 via the communication unit 41. The internal resistance value Ri of the battery 21 is calculated.

  FIG. 3 is a flowchart showing the flow of processing in the diagnosis / adjustment mode. As described above, this process is a process executed by the control unit 14 when, for example, an operation signal corresponding to the operation of the diagnostic button is acquired from the input / output unit 42 or at a preset maintenance timing. The maintenance timing is, for example, a predetermined date / time of each month, a timing when the number of executions of the discharge mode or the charging mode reaches a predetermined number, and the information on the timing is stored in the storage unit 43, for example.

  As illustrated in FIG. 3, in the diagnosis / adjustment mode, the command generation unit 44 first stores information on the detected voltage value Vdc transmitted from the charge / discharge unit 11 to the communication unit 41 in the storage unit 43 as the reference voltage value Vref. (Step S10).

  The reference voltage value Vref is a voltage value of the power storage unit 10 detected by the voltage detection unit 12 in a state where all the switches 22a to 22c are on. In the standby state in which no operation mode is executed, the power storage device 1 turns on all the switches 22a to 22c and electrically connects the secondary batteries 21a to 21c in parallel.

  In this embodiment, all the switches 22a to 22c are turned on in the standby state, but all the switches 22a to 22c can be turned off in the standby state. In this state, since the secondary batteries 21 are not connected, it is possible to prevent a current from flowing between the batteries and to reduce power consumption. When all the switches 22a to 22c are turned off in the standby state, the control unit 14 turns on all the switches 22a to 22c when starting the discharge mode or the charge mode.

  Next, the command generation unit 44 outputs a switch command to the input / output unit 42 to turn off all the switches 22a to 22c (step S11). Accordingly, the secondary batteries 21a to 21c are electrically disconnected from each other, and the power storage unit 10 is electrically disconnected from the charge / discharge unit 11 and the like.

  Next, the command generation unit 44 selects one switch 22 connected to the secondary battery 21 for which the internal resistance value Ri has not been calculated, and turns on the switch 22 (step S12). As a result, only one secondary battery 21 can be charged and discharged, and the internal resistance value Ri of the secondary battery 21 can be calculated.

  The command generation unit 44 outputs an operation command whose type is a charging command and a control command whose specified current value is the charging current value Ir stored in the storage unit 43 to the charging / discharging unit 11 via the communication unit 41. The internal resistance calculation unit 45 calculates the internal resistance value Ri of the secondary battery 21 based on the detected voltage value Vdc and the detected current value Idc acquired via the communication unit 41 (step S13).

  FIG. 4 is a diagram for explaining a method for calculating the internal resistance value Ri of the secondary battery 21. As shown in FIG. 4, the command generation unit 44 sends the operation command and the control command to the charging / discharging unit so that the current of the charging current value Ir flows through the power storage unit 10 only during a predetermined charging period (time t0 to t1). 11 to output. During this time, the detection voltage value Vdc gradually increases. The command generation unit 44 outputs a calculation command to the internal resistance calculation unit 45, and the secondary battery 21 is based on the detection voltage value Vdc and detection current value Idc during charging and the detection voltage value Vdc during non-charging. The internal resistance calculation unit 45 is caused to calculate the internal resistance value Ri.

The internal resistance calculator 45 calculates the internal resistance value Ri by the following equation (1), for example. In the following formula (1), Vdc0 is the detected voltage value Vdc before charging (for example, time t0), Vdc1 is the detected voltage value Vdc when charging is stopped (for example, time t2), and Vdc2 is The detected voltage value Vdc immediately before the stop of charging (for example, time t1). Idc1 is a detected current value Idc during charging. If Vdc0 and Vdc1 substantially match, Vdc0 may be used instead of Vdc1.
Ri = (Vdc2−Vdc1) / Idc1 (1)

  When the process of step S13 ends, the command generation unit 44 turns off the switch 22 that was turned on in step S12 (step S14). Thereafter, the command generator 44 determines whether there is a secondary battery 21 that has not calculated the internal resistance value Ri (step S15). If it determines with there being the secondary battery 21 which has not calculated internal resistance value Ri (step S15; Yes), the command generation part 44 will transfer a process to step S12.

  On the other hand, when determining that there is no secondary battery 21 that has not calculated the internal resistance value Ri (step S15; No), the command generation unit 44, based on the internal resistance value Ri calculated by the internal resistance calculation unit 45, It is determined whether there is a deteriorated secondary battery 21 (step S16). The internal resistance calculator 45 determines that there is a deteriorated secondary battery 21 when any of the internal resistance values Ri <b> 1 to Ri <b> 3 is equal to or greater than the internal resistance threshold Rmin stored in the storage unit 43.

  If it is determined that there is a deteriorated secondary battery 21 (step S16; Yes), the internal resistance calculation unit 45 causes the display unit 16 to display a message prompting the replacement of the secondary battery 21 via the input / output unit 42 ( Step S17). The message includes information that identifies the secondary battery 21 whose internal resistance value Ri is equal to or greater than the internal resistance threshold value Rmin as the deteriorated secondary battery 21. Thus, the control part 14 does not perform an adjustment process, when there exists the secondary battery 21 whose internal resistance value Ri is more than internal resistance threshold value Rmin.

  After displaying the message on the display unit 16, the control unit 14 determines whether or not the deteriorated secondary battery 21 has been replaced with a new secondary battery 21 (step S18). For example, a battery folder (not shown) for detachably connecting the secondary battery 21 to the power storage unit 10 is disposed in the power storage unit 10, and a mounting detection unit for the secondary battery 21 is disposed in the battery folder. The control unit 14 determines that the secondary battery 21 has been replaced with a new secondary battery 21 based on the mounting detection signal output from the mounting detection unit when the secondary battery 21 is mounted in the battery folder. Whether it is attached or detached is determined, for example, based on whether the detected voltage value Vdc is zero or non-zero.

  If it determines with the degraded secondary battery 21 having been replaced | exchanged for the new secondary battery 21 (step S18; Yes), the control part 14 will transfer a process to step S19. Similarly, when it is determined in step S16 that there is no deteriorated secondary battery 21 (step S16; No), the control unit 14 proceeds to step S19.

  In step S <b> 19, the command generation unit 44 selects one switch 22 connected to the secondary battery 21 that has not been subjected to voltage adjustment, and turns on the switch 22. Thereby, only the one secondary battery 21 will be in the state which can be charged / discharged, and the voltage of each secondary battery 21 can be adjusted separately.

  Next, the command generation unit 44 performs voltage adjustment of the secondary battery 21 selected in step S19 as an adjustment target (hereinafter referred to as the secondary battery 21 to be adjusted) (step S20). Specifically, the command generation unit 44 acquires the detected voltage value Vdc detected by the voltage detection unit 12 via the communication unit 41. The detected voltage value Vdc is a voltage value of the secondary battery 21 to be adjusted, and is hereinafter referred to as a detected voltage value Vdce.

  The command generation unit 44 determines whether or not the detected voltage value Vdce is within a predetermined range, that is, within a predetermined voltage difference Ve with respect to the reference voltage value Vref. Further, when the detected voltage value Vdce is not within the range of Vref ± Ve, the command generation unit 44 determines whether the detected voltage value Vdce is larger or smaller than the reference voltage value Vref.

  When the detected voltage value Vdce is outside the range of Vref ± Ve and smaller than the reference voltage value Vref, the command generation unit 44 uses the operation command with the type as the charge command and the charging current value Ia stored in the storage unit 43. A control command for the designated current value is output to the charge / discharge unit 11 via the communication unit 41. Thereby, the charging / discharging part 11 starts the charge with the charging current value Ia to the secondary battery 21 to be adjusted.

  Thereafter, the command generator 44 stops outputting the operation command and the control command when the detected voltage value Vdc detected by the voltage detector 12 becomes the reference voltage value Vref. Thereby, the charging / discharging part 11 complete | finishes the charge to the secondary battery 21 of adjustment object, and the voltage of the secondary battery 21 of adjustment object is adjusted to the reference voltage value Vref.

  On the other hand, when the detected voltage value Vdce is outside the range of Vref ± Ve and is larger than the reference voltage value Vref, the command generation unit 44 generates an operation command having a type as a discharge command, a supply voltage value Va, and a discharge current value Ib. A control command for the designated current value is output to the charge / discharge unit 11 via the communication unit 41. Thereby, the charging / discharging part 11 starts the discharge with the discharge current value Ib from the secondary battery 21 to be adjusted. The drive control unit 34 of the charge / discharge unit 11 adjusts the supply voltage value Va so that the deviation between the detected current value Idc and the discharge current value Ib becomes zero, so that the secondary battery 21 has the discharge current value Ib. Discharge from

  Thereafter, the command generator 44 stops outputting the operation command and the control command when the detected voltage value Vdce detected by the voltage detector 12 becomes the reference voltage value Vref. Thereby, the charging / discharging unit 11 ends the discharge of the secondary battery 21 to be adjusted, and the voltage of the secondary battery 21 to be adjusted is adjusted to the reference voltage value Vref.

  The discharge from the secondary battery 21 can also be performed by the control unit 14 operating the load 3. In this case, the command generation unit 44 outputs a drive command for requesting a predetermined load current to flow through the load 3 to the input / output unit 42 instead of the command for the charge / discharge unit 11. As described above, the load 3 includes, for example, an inverter circuit and an AC motor, and a predetermined load current flows by driving the inverter circuit so that a DC current flows through the AC motor according to a drive command. Note that a predetermined load current may be caused to flow by connecting a discharge unit in which a discharge resistor and a switching element are connected in series between DC voltages and turning on the switching element by a drive command.

  Moreover, when it replaces | exchanges for the new secondary battery 21 by step S18, the control part 14 can adjust the reference voltage value Vref. For example, the control unit 14 causes the voltage detection unit 12 to detect the voltage value of the new secondary battery 21, compares the voltage value with the reference voltage value Vref, and the voltage value of the secondary battery 21 is the reference voltage value Vref. Is higher than the reference voltage value Vref, the voltage value of the secondary battery 21 is used. Further, the control unit 14 stores the voltage value of the new secondary battery 21 in the storage unit 43 in advance, so that the detection process by the voltage detection unit 12 is not performed and the voltage value stored in the storage unit 43 is used. You can also.

  When the process of step S20 ends, the command generation unit 44 turns off the switch 22 that was turned on in step S19 (step S21). Thereafter, the command generator 44 determines whether there is a secondary battery 21 that has not been subjected to voltage adjustment (step S22). If it determines with there being the secondary battery 21 which has not performed voltage adjustment (step S22; Yes), the command generation part 44 will transfer a process to step S19.

  On the other hand, if it is determined that there is no secondary battery 21 that has not been subjected to voltage adjustment (step S22; No), the command generator 44 turns on all the switches 22a to 22c to enter a standby state, and ends the diagnosis / adjustment mode. . In step S22, a standby state in which all the switches 22a to 22c are turned off may be set.

  As described above, in the power storage device 1 according to this embodiment, the control unit 14 controls the switch 22 so that the voltage difference between the secondary batteries 21 falls within a predetermined range, and individually charges and discharges the secondary batteries 21. An adjustment process for charging or discharging by the unit 11 is executed. Such adjustment processing is performed, for example, before the discharge mode or the charge mode.

  With such a configuration, even when the switch 22 that connects the secondary batteries 21 is turned on and the secondary batteries 21 are electrically connected, the potential difference between the secondary batteries 21 is small, so a large rush occurs. Current does not flow. Therefore, it is possible to reduce or eliminate the problem of the arrangement space and cost of the inrush prevention resistor and the bypass conductor.

  In addition, since the inrush current can be reduced, it is possible to easily cope with the load 3 that has a large load fluctuation and is difficult to predict the fluctuation of the load capacity by increasing the number of secondary batteries 21 connected in parallel. Can do. The load 3 that has a large load fluctuation and is difficult to predict the load capacity fluctuation is, for example, a machine with a lifting operation such as a crane or a vertical transfer machine, or the load capacity is stable depending on the road surface condition even in the case of horizontal movement. There is no trolley.

  In the above-described embodiment, the information on the detection voltage value Vdc detected by the voltage detection unit 12 in a state where all the switches 22a to 22c are on is the reference voltage value Vref. However, the reference voltage value Vref is applied. It is not limited to information. For example, the voltage value in consideration of the battery characteristics of the secondary battery 21 may be set as the reference voltage value Vref, and the voltage value of the secondary battery 21 having the highest voltage may be set as the reference voltage value Vref.

  When the voltage value in consideration of the battery characteristics of the secondary battery 21 is used as the reference voltage value Vref, for example, battery characteristic information indicating the relationship between the voltage of the secondary battery 21 and the charge amount is stored in the storage unit 43. . FIG. 5 is a diagram showing the battery characteristics of the secondary battery 21. As shown in FIG. 5, the secondary battery 21 has a characteristic that the voltage increases as the charge amount increases. For example, in the region A, the change in the voltage with respect to the change in the charge amount is small.

  Therefore, the control unit 14 determines the reference voltage value Vref in a region where the change in voltage with respect to the change in charge amount is small. Thereby, the voltage adjustment of the secondary battery 21 can be performed in a region where the voltage is stable, and there is little variation in the voltage value of the secondary battery 21 after the voltage adjustment. Therefore, the inrush current generated between the secondary batteries 21 can be accurately reduced.

  In addition, when the voltage value of the secondary battery 21 having the highest voltage is set as the reference voltage value Vref, the control unit 14 controls one switch 22 among the switches 22a to 22c before the process of step S19. The voltage value of the secondary battery 21 is detected by the voltage detector 12. And the control part 14 memorize | stores the highest detected voltage value Vdc in the memory | storage part 43 as the reference voltage value Vref among the detected voltage values Vdc detected by the voltage detection part 12, and performs the process of step S19. In addition, the control part 14 can memorize | store the detection voltage value Vdc detected by the voltage detection part 12 in step S13 in the memory | storage part 43, and can also use the highest detection voltage value Vdc as the reference voltage value Vref. Thereby, the processing speed can be improved.

  Moreover, the voltage value of the secondary battery 21 with the smallest voltage change with respect to the change in the charge amount among the voltages of the secondary batteries 21a to 21c may be set as the reference voltage value Vref. For example, when the voltages V11 to V13 of the secondary batteries 21a to 21c are in the state shown in FIG. 5, the voltage V11 of the secondary battery 21a is selected as the reference voltage value Vref. By doing in this way, the processing speed in voltage adjustment can be improved, reducing the inrush current which arises between the secondary batteries 21 accurately.

  Further, the control unit 14 sets the voltage value of the secondary battery 21 having the lowest voltage when fully charged as the reference voltage value Vref, and executes the adjustment process so that the difference from the reference voltage value Vref falls within a predetermined range. You can also. The secondary battery 21 having a high internal resistance Ri has a high degree of deterioration, and the voltage at full charge is often the lowest. Therefore, the control unit 14 sets the secondary battery 21 having the highest internal resistance value Ri as the secondary battery 21 having the lowest voltage when fully charged, and sets the voltage value of the secondary battery 21 as the reference voltage value Vref. By doing in this way, adjustment processing can be performed with higher accuracy.

  In the above-described embodiment, the diagnosis / adjustment mode in which the diagnosis mode and the adjustment mode are continuously performed has been described. However, the control unit 14 can also execute the diagnosis mode and the adjustment mode individually. In this case, the processes of steps S11 to S18 are performed in the diagnosis mode, and the processes of steps S19 to S22 are performed in the adjustment mode.

  Further, the control unit 14 can set the adjustment mode to be executed immediately after the discharge mode ends, immediately before the charge mode is executed, immediately after the replacement with the new secondary battery 21, or the like. When executing the adjustment mode immediately before executing the charging mode, the control unit 14 individually acquires the voltage value of each of the secondary batteries 21a to 21c, and sets the remaining voltage to the voltage value of the secondary battery 21 having the highest voltage. The voltage of the secondary battery 21 is adjusted. Thereby, since the voltage adjustment of the secondary battery 21 having the highest voltage is not performed, the processing time in the adjustment mode can be shortened.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Power storage device 2 Power supply 3 Load 10 Power storage part 11 Charging / discharging part 12 Voltage detection part 13 Current detection part 14 Control part 21a-21c (21) Secondary battery (electric storage circuit)
22a-22c (22) Switch

Claims (7)

A power storage unit having a plurality of power storage circuits each connected in parallel via a switch;
A voltage detector for detecting each voltage of the plurality of power storage circuits;
A charging / discharging unit that supplies discharge power from the power storage unit to a load and charges the power storage unit with power supplied from a power source;
A control unit for controlling the switch and the charge / discharge unit,
The controller is
A power storage device, wherein the switch and the power storage circuit are controlled so that a voltage difference between the power storage circuits falls within a predetermined range, and adjustment processing for individually charging or discharging the power storage circuit is performed. The controller is
2. The power storage according to claim 1, wherein a voltage of the power storage circuit detected by the voltage detection unit is used as a reference voltage, and the adjustment process is executed so that a voltage difference from the reference voltage falls within a predetermined range. apparatus. The controller is
The adjustment processing is executed such that the voltage of the power storage circuit detected by the voltage detection unit in a state where all the switches are on is set as a reference voltage, and the voltage difference from the reference voltage is within a predetermined range. The power storage device according to claim 2. The controller is
3. The adjustment process according to claim 2, wherein a voltage of one power storage circuit among the plurality of power storage circuits is set as a reference voltage, and the adjustment process is executed so that a voltage difference from the reference voltage falls within a predetermined range. Power storage device. A storage unit that stores information indicating a relationship between a voltage of the power storage circuit and a charge amount;
The controller is
2. The adjustment process is performed based on information stored in the storage unit so that a voltage difference between the storage circuits is in a predetermined range in a region where a change in voltage with respect to a change in charge amount is small. The power storage device described in 1. A current detector for detecting each current value of the plurality of power storage circuits;
The controller is
Before the adjustment process, based on detection results of the voltage detection unit and the current detection unit, an internal resistance detection process for calculating an internal resistance value of the power storage circuit,
The power storage device according to claim 1, wherein the adjustment process is executed based on a detection result of the voltage detection unit used in the internal resistance detection process. The controller is
The power storage device according to claim 6, wherein the adjustment process is not performed when there is the power storage circuit having an internal resistance value equal to or greater than a predetermined value.

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