Electric storage device and start-up method

Provided is an electric storage device including: a control unit, a charge/discharge management unit and a current generation unit, which are connected through an input/output unit; and an electric storage unit that is connected to the charge/discharge management unit and is connected to the current generation unit through a switch.

TECHNICAL FIELD

The present disclosure relates to an electric storage device and a start-up method.

BACKGROUND ART

Electric storage devices that supply power to a load such as an electronic device are in widespread use. The electric storage device is required to be started up even when external power is not supplied during such as electric blackout. In the following Patent Literature 1, an electric storage device that is started up using power of a battery when a commercial power supply is stopped is disclosed.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

An electric storage device disclosed in Patent Literature 1 maintains a standby state using power of a battery. There was a problem that the standby state of the electric storage device cannot be maintained over a long period because the power of the battery is consumed in the standby state.

Therefore, one of objects of the present disclosure is to provide an electric storage device that rids power that is consumed in the standby state. Further, the present disclosure intends to provide a start-up method of the electric storage device.

Solution to Problem

According to the present disclosure, for example, there is provided an electric storage device including: a control unit, a charge/discharge management unit and a current generation unit, which are connected through an input/output unit; and an electric storage unit that is connected to the charge/discharge management unit and is connected to the current generation unit through a switch.

According to the present disclosure, for example, there is provided an electric storage device including: an electric storage unit; and a current generation unit that generates a charge current smaller than a usual charge current in a case where a voltage of the electric storage unit is smaller than a threshold value. Power output from the electric storage unit is supplied to the current generation unit at a time of start-up.

According to the present disclosure, for example, there is provided a start-up method of an electric storage device, the electric storage device including a control unit, a charge/discharge management unit and a current generation unit, which are connected through an input/output unit, and an electric storage unit that is connected to the charge/discharge management unit and is connected to the current generation unit through a switch, the start-up method including: turning off the control unit and the charge/discharge management unit and turning off the switch in a shutdown state and turning on the switch in a case of start-up from the shutdown state; generating, by the current generation unit, a predetermined current based on power supplied from the electric storage unit in response to turning-on of the switch, and outputting the generated current to the input/output unit; and turning on the control unit and the charge/discharge management unit in a case where a voltage in the input/output unit reaches an operating voltage by a current supplied from the current generation unit.

Advantageous Effects of Invention

According to at least an embodiment, standby power of the electric storage device in a standby state can be ridden.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments, etc., of the present disclosure will be described with reference to the drawings. The description will be performed according to the following order.

Embodiments, etc., described below are preferable specific examples and the content of the present disclosure is not limited to these embodiments, etc.

Incidentally, in the following description, a state of an electric storage device that is connected to a load but does not supply power to the load and can supply the power to the load according to an instruction is appropriately called as a standby state or a shutdown state. The instruction at this time is, for example, a predetermined operation of the electric storage device by a user.

The power for the electric storage device to maintain the standby state, in other words, the power that is consumed in the standby state (shutdown state) is appropriately called as standby power. As will hereinafter be described in detail, a general electric storage device (an electric storage system) consumes the standby power to maintain the standby state using commercial power or power of a battery. According to the electric storage device in the present disclosure, the standby power can be made zero. Further, the electric storage device in the present disclosure can be started-up even when there is no external power supply such as the commercial power, and can realize an autonomous operation of the electric storage device.

In the following description, “smaller than A” may be construed to be equal to or less than A or less than A. “Larger than A” may be construed to be equal to or greater than A or to exceed A.

1. First Embodiment

“One Example of Electric Storage Unit”

An electric storage device in the present disclosure includes an electric storage unit. Before the electric storage device is described, an example of the electric storage unit will be described. The electric storage unit includes, for example, a plurality of secondary batteries. The secondary battery that constitutes the electric storage unit is, for example, a lithium ion secondary battery that includes a positive electrode active material and a carbon material such as graphite as a negative electrode active material. A positive electrode material is not particularly limited but preferably contains the positive electrode active material having an olivine structure.

As the positive electrode active material having the olivine structure, lithium iron phosphate (LiFePO4), or lithium iron composite phosphate containing a different kind of atom (LiFexM1-xO4: M represents one or more kinds of metals, x is 0<x<1.) is preferred. Here, “mainly” means that a total amount of the positive electrode active material of a positive electrode active material layer is 50% or more. Further, when M includes two or more kinds, a total amount of the respective subscript numbers is selected to be 1−x.

As the M, transition elements, IIA group elements, IIIA group elements, IIIB group elements, IVB group elements, etc., can be cited. In particular, at least one kind of cobalt (Co), nickel, manganese (Mn), iron, aluminum, vanadium (V) and titanium (Ti) is preferably contained.

The positive electrode active material may be provided with a coating layer containing metal oxide (for example, one selected from Ni, Mn, Li, etc.) having a composition different from the relevant oxide or phosphate (for example, lithium phosphate, etc.), etc. on a surface of the lithium iron phosphate or the lithium iron composite phosphate.

As the positive electrode material that can absorb and release lithium (Li), lithium composite oxides such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium manganese oxide (LiMnO2), which have a layered rock salt structure, and lithium manganese oxide (LiMn2O4) that has a spinel structure may be used.

As the graphite in the present disclosure, without particular limitation, graphite materials used in the business field can be broadly used. As the material of the negative electrode, lithium titanate, silicon (Si)-based materials, tin (Sn)-based materials, etc. may be used.

As a manufacturing method of a battery electrode according to the present disclosure, methods used in the business field can be broadly used without particular limitation.

As a battery configuration in the present disclosure, well-known configurations can be broadly used without particular limitation.

As an electrolytic solution used in the present disclosure, the electrolytic solutions used in the business field including liquid electrolyte and gel-like electrolyte can be broadly used without particular limitation.

The lithium ion secondary battery can be categorized into a square type, a cylinder type, etc. in accordance with a shape. As an example in the present disclosure, a cylindrical lithium ion secondary battery is used. One cylindrical lithium ion secondary battery is appropriately called as a cell. An average output voltage of the cell of the lithium ion secondary battery is, for example, about 3.0 Volt (V), and a full charge voltage is, for example, about 4.2 V. Further, a capacity of the cell of the lithium ion secondary battery is, for example, 3 ampere hour (Ah) (3000 milliampere hour (mAh)).

A sub-module is formed when a plurality of cells are connected. The submodule has a configuration in which, for example, 8 cells are connected in parallel. In this case, a capacity of the submodule becomes about 24 Ah, and a voltage becomes about 3.0 V the same as a voltage of a cell voltage.

When, for example, 16 submodules are connected in series and housed in a common case, an electric storage unit is configured. The capacity of the electric storage unit at this case becomes about 24 Ah, and the voltage becomes about 48 V (3.0 V×16). Further, the configuration of the electric storage unit can be properly changed according to use, etc. Still further, the electric storage unit may be configured of electric double layers, large capacitors, etc. without limiting to the lithium ion secondary battery.

“Configuration of General Electric Storage Device”

In order to make the understanding of the present disclosure easier, a configuration of the general electric storage device (electric storage system) will be described with reference toFIG. 1. Solid line arrows in fromFIG. 1toFIG. 7show a flow of power. Inside the electric storage device or between the electric storage device and external instruments, communication based on specified standard is performed. However, a flow of a signal based on the communication is omitted from illustrating.

An electric storage device1is connected to, for example, a direct current (DC) power unit2and an alternating current AC) power unit3. The DC power unit2is a solar battery module set, for example, on a roof, out of doors, etc. The solar battery module is formed by connecting a plurality of solar batteries into a panel and called also as a solar panel. Usually, a plurality of sheets of solar battery modules are set arranged side by side and configure a solar battery array.

A power conditioner (omitted from showing in the drawing) is disposed to the DC power unit2. The power conditioner performs a control called as maximum power point tracking (MPPT). This control is a method that always tracks a maximum power point by following a variation of generated power of the solar battery module. A configuration in which an output of the power conditioner is connected to a power supply line of an external power system and the generated power (superfluous power) of the solar battery module is sold may be taken.

The AC power unit3is, for example, a commercial power. Power (alternating current power) generated at an electric generation plant of a power supplier is supplied to the AC power unit3through a transmission network and an electric grid, which are not shown in the drawing.

The electric storage device1is connected to a load4and supplies the power to the load4. The load4can be properly set according to use other than electronic devices such as a refrigerator and a television receiver.

The electric storage device1includes, for example, a photovoltaic (PV) charger20, an input/output unit21through which power is input/output, an AC-DC converter22, a DC-AC inverter23, a charge/discharge unit24, an AC-DC conversion unit25, a current generation unit26, an energy management unit (EMU)27, a battery management unit (BMU)28, and an electric storage unit29. The AC-DC converter22, the DC-AC inverter23, and the charge/discharge unit24form an uninterruptable power supply (UPS) unit35.

Each unit will be schematically described. The PV charger20includes a DC-DC converter and a charge control unit. A voltage supplied from the DC power unit2by the DC-DC converter is converted to a predetermined voltage. A charge control unit controls a value of a current output from the PV charger20. The PV charger20is operated when the voltage supplied from the DC power unit2exceeds a threshold value (for example, 100 volt (V)). To the input/output unit21, for example, the PV charger20, the current generation unit26, the charge/discharge unit24, the EMU27and the BMU28are connected.

The AC-DC converter22generates direct current power from the commercial power (alternating current power) input from the AC power unit3. The direct current power output from the AC-DC converter22is supplied to the DC-AC inverter23. The DC-AC inverter23forms alternating current power of the same level and frequency as a level and a frequency of the commercial power. The formed alternating current power is supplied to the load4.

The charge/discharge unit24operates in response to charge or discharge of the electric storage device1. For example, when the charge is performed to the electric storage unit29, the direct current power is formed from the alternating current power input through the AC-DC converter22and the direct current power is output to the input/output unit21. When the discharge is performed, the direct current power supplied from the input/output unit21is supplied to the DC-AC inverter23.

The AC-DC conversion unit25forms the direct current power from the commercial power (alternating current) input from the AC power unit3. The formed direct current power is supplied to the current generation unit26.

The current generation unit26includes, for example, a constant-current DC-DC converter and generates a current having a predetermined current value. The predetermined current value is, for example, about 10 ampere (A). In the case where the voltage of the electric storage unit29is low, for example, in the case of smaller than 42 V, when a usual charge current (for example, about several tens A) is flowed to the electric storage unit29, abnormality such as heat generation may be induced. There, in the case where the voltage of the electric storage unit29is smaller than 42 V, the electric storage unit29is initially charged by a low rate constant current of about 1.0 A. When the voltage of the electric storage unit29becomes larger than 42 V, the charge/discharge unit24is operated, and the electric storage unit29is charged based on the usual charge current output from the charge/discharge unit24.

Incidentally, in the case where the electric storage unit29is charged by the direct current power supplied from the DC power unit2, the similar control is performed. In this case, the PV charger20described above generates a low rate current, and an initial charge is performed by the low rate current generated by the PV charger20. After the end of the initial charge, the PV charger20generates the usual charge current, and the electric storage unit29is charged by the charge current.

A controller is disposed to control the electric storage device1. The controller includes, for example, the EMU27that is an example of the control unit and the BMU28that is an example of a charge/discharge management unit. Each of the EMU27and the BMU28includes a micro-control unit, and a communication is performed between the EMU27and the BMU28.

The EMU27performs an overall management of the electric storage device1. The BMU28observes the state (residual capacity, battery voltage, battery temperature, etc.) of the electric storage unit29and operates such that a proper charge/discharge operation is performed. The BMU28properly controls on/off of a charge control switch and a discharge control switch (these are omitted from showing in the drawing) formed of a field effect transistor (FET), etc. and controls the charge/discharge to the electric storage unit29. Known control can be applied to the control of the charge/discharge in the BMU28. Incidentally, although, in the present embodiment, the BMU28and the EMU27are described as separate configurations, these may be realized in one microcomputer, etc. and may be integrated in one body.

An example of a flow of power in the electric storage device1will be described. As shown with a dotted line (a) ofFIG. 2, in the electric storage device1, the electric storage unit29can be charged based on the direct current power supplied from the DC power unit2. That is, the direct current voltage supplied from the DC power unit2is converted into a proper direct current voltage by the PV charger20. The direct current voltage formed by the PV charger20is supplied to the electric storage unit29through the input/output unit21and the BMU28, and the electric storage unit29is charged.

Further, as shown with a dotted line (b1) and a dotted line (b2) ofFIG. 2, in the electric storage device1, the electric storage unit29can be charged based on the direct current power supplied from the AC power unit3. A passage shown with the dotted line (b1) shows a passage of power at the time of initial charge, and a passage shown with the dotted line (b2) shows a passage of power at the time of usual charge.

The alternating current voltage supplied from the AC power unit3is converted into the direct current voltage by the AC-DC conversion unit25. The direct current voltage is supplied to the current generation unit26. The current generation unit26generates a low rate charge current for initial charge based on the supplied direct current voltage. The charge current from the current generation unit26is supplied to the electric storage unit29through the input/output unit21and the BMU28. Then, the charge by the low rate charge current is performed until the voltage of the electric storage unit29becomes the threshold value or more.

When the voltage of the electric storage unit29becomes the threshold value or higher, usual charge of the electric storage unit29is performed by the power that flows the passage of the dotted line (b2). That is, the alternating current voltage supplied from the AC power unit3is supplied to the charge/discharge unit24through the AC-DC converter22. The alternating current voltage is converted into the direct current voltage by the charge/discharge unit24. The direct current voltage is supplied to the electric storage unit29through the input/output unit21and the BMU28, and the electric storage unit29is charged. The charge/discharge unit24performs charge according to, for example, a constant-current (CC)-constant-voltage (CV) method.

The initial charge and the usual charge are switched by the EMU27. A switching control of the initial charge and the usual charge is performed, for example, as shown below. A switch SW1(omitted from showing in the drawing) is connected between the AC power unit3and the AC-DC conversion unit25. Further, a switch SW2(omitted from showing in the drawing) is connected between the AC power unit3and the AC-DC converter22.

The BMU28observes the battery voltage of the electric storage unit29and informs the EMU27of information of the battery voltage. The information of the battery voltage is informed to the EMU27at, for example, a predetermined cycle. The EMU27controls such that the switch SW1is turned on and the switch SW2is turned off when the battery voltage is smaller than the threshold value. By this control, the initial charge is performed. In the case where the battery voltage is equal to or greater than the threshold value or the battery voltage becomes equal to or greater than the threshold value by the initial charge, the EMU27turns off the switch SW1and turns on the switch SW2. The usual charge is performed by this control.

By performing communication between the EMU27and the UPS unit35and by controlling the operation of the charge/discharge unit24based on the communication, the usual charge and the initial charge may be switched. The output voltage of the current generation unit26is set lower than the output voltage of the charge/discharge unit24and the output voltage of the PV charger20. Therefore, in the case where the UPS unit35and the PV charger20are not operated, the initial charge is performed by the output power of the current generation unit26. That is, the usual charge and the initial charge can be switched by controlling the operation of the UPS unit35and the PV charger20.

As shown with a dotted line (c) ofFIG. 3, the electric storage device1can supply the power supplied from the DC power unit2to the load4. The direct current voltage supplied from the DC power unit2is converted into a predetermined voltage by a DC-DC converter in the PV charger20, and the direct current power is formed. The direct current power formed by the PV charger20is supplied to the DC-AC inverter23through the input/output unit21and the charge/discharge unit24.

The DC-AC inverter23forms alternating current power of the same level and frequency as a level and a frequency of the commercial power. The alternating current power formed by the DC-AC inverter23is supplied to the load4.

As shown with a dotted line (d) ofFIG. 3, the electric storage device1can supply the alternating current power supplied from the AC power unit3to the load4. The alternating current power supplied from the AC power unit3is supplied to the AC-DC converter22. The AC-DC converter22forms the direct current power from the AC power and outputs. The direct current power output from the AC-DC converter22is supplied to the DC-AC inverter23. The DC-AC inverter23forms the alternating current power of a level and a frequency the same as a level and a frequency of the commercial power based on the supplied direct current power. The alternating current power formed by the DC-AC inverter23is supplied to the load4.

When a switch is disposed at a proper position of a passage of each power and each switch is properly turned-on or turned-off, input of the power to the electric storage device1can be switched. For example, in each of between the DC power unit2and the PV charger20and between the AC power unit3and the AC-DC converter22, a switch is provided. The EMU27controls the PV charger20and the UPS unit35by communication, and the PV charger20and the UPS unit35may be on/off controlled. According to the control, a supply passage of the power to the load4may be switched.

As shown with a dotted line (e) ofFIG. 4, the electric storage device1can supply the power due to the discharge of the electric storage unit29to the load4. The direct current power due to the discharge of the electric storage unit29is supplied to the DC-AC inverter23through the BMU28, the input/output unit21and the charge/discharge unit24. The DC-AC inverter23forms the alternating current power of a level and a frequency the same as a level and a frequency of the commercial power. The alternating current power formed by the DC-AC inverter23is supplied to the load4.

Incidentally, in order to start up the above-described electric storage device1, it is necessary to supply the power to at least the EMU27. In the electric storage device1, the power supplied from the DC power unit2or the AC power unit3through, for example, the passages shown with a dotted line (f1), a dotted line (f2) and a dotted line (f3) ofFIG. 5is supplied to the EMU27. Here, in the case where the power is not supplied from the DC power unit2and the AC power unit3due to the blackout, the bad weather etc., the electric storage device1cannot be started up. In an environment where stoppage of power supply is assumed, even when the electric storage device1is not used, the power supply is continued to the EMU27and the BMU28, and the standby state is maintained. Since the power is always used to maintain the standby state, there is inconvenience from the cost point of view, etc.

On the other hand, it is considered to supply, in place of the DC power unit2and the AC power unit3, the power of the electric storage unit29to the EMU27and the BMU28. However, it becomes difficult to maintain the standby state in the case where the remaining capacity of the electric storage unit29decreased due to consumption of the power for maintaining the standby state. There, the electric storage device in the present disclosure makes the standby power zero while starting up the electric storage device by the power of the electric storage unit. Hereinafter, an example of the electric storage device in the present disclosure will be described in detail.

“Configuration of Electric Storage Device in Present Disclosure”

FIG. 6shows an exemplary configuration of an electric storage device (electric storage device10) in the present disclosure. In the electric storage device10, the like members the same as those of the electric storage device1will be identified by the like reference numerals, and duplicated description will be omitted.

In the electric storage device10, the electric storage unit29and the current generation unit26are connected through a switch SW40. The switch SW40is, for example, a button disposed to an exterior case of the electric storage device10. The switch SW40is turned off in the standby state. Further, in the standby state, the EMU27and the BMU28are turned off. That is, the electric storage unit29is separated from each unit in the electric storage device10in the standby state. Therefore, the power of the electric storage unit29is not consumed in the standby state, and the standby power becomes zero.

A user of the electric storage device10pushes down the button for, for example, about a few seconds and turn on the switch SW40when starting up the electric storage device10. By continuing the push down of the button for about a few seconds, the electric storage device10is started up. After the start-up of the electric storage device10, the user releases the push down of the button and the switch SW40is turned off. Since the switch SW40is turned off, the power of the electric storage unit29is not directly supplied to the current generation unit26after the start-up.

“Start-Up Processing of Electric Storage Device”

An example of a start-up processing of the electric storage device10will be described in detail. In response to turning-on of the switch SW40, the direct current power of the electric storage unit29is supplied to the current generation unit26. The current generation unit26generates a low rate current based on the direct current power supplied from the electric storage unit29. This current is a current of about 1.0 A the same as a low rate charge current in the initial charge. The low rate current generated by the current generation unit26is supplied to the input/output unit21.

When the current is supplied from the current generation unit26, the voltage in the input/output unit21gradually increases. When the voltage in the input/output unit21exceeds a predetermined value, units (EMU27and BMU28, for example) connected to the input/output unit21are started up. Here, the predetermined value is a voltage (operating voltage) necessary for the EMU27and the BMU28to operate. The operating voltage of the EMU27and the operating voltage of the BMU28may be the same or different from each other.

After the EMU27and the BMU28are started up, the electric storage unit29is connected to each unit of the electric storage device10through the BMU28. Thus, the standby power can be made zero and, at the same time, the electric storage device10can be started up by using the power of the electric storage unit29.

Here, in the case where any one of the units connected to the input/output unit21is broken down or a connecting line is short-circuited, the voltage in the input/output unit21does not increase even when the current is supplied from the current generation unit26. That is, the voltage in the input/output unit21does not reach the operating voltage of the EMU27and the EMU28, and the electric storage device10is not started up. The electric storage unit29is not connected to each unit of the electric storage device10since the EMU27and the BMU28do not work. Thus, the electric storage unit29can be prevented from being connected to the unit having a failure such as malfunction, etc. when the power of the electric storage unit29is supplied through the current generation unit26. Then, failure (secondary failure) of the electric storage unit29due to the connection of the electric storage unit29to the unit having the failure can be prevented.

Further, when the electric storage unit29is connected directly to the EMU27, etc., an inrush current flows, and the EMU27, etc. may be damaged. However, according to the electric storage device in the present disclosure, the EMU27, etc. can be prevented from being damaged by the inrush current since the power of the electric storage unit29is output through the current generation unit26.

The electric storage device can be started up also by the power through a resistor50as shown inFIG. 7, for example. However, in the case where a unit connected to the input/output unit21has a failure, etc., a configuration shown inFIG. 7is not preferable because the relevant unit may generate heat and cause a secondary failure.

An example of a specific circuit configuration will be described. As shown inFIG. 8, in the general electric storage device1, the power is not supplied from the electric storage unit29to the current generation unit26.

FIG. 9shows an example of a specific circuit configuration between the electric storage unit29and the current generation unit26in the electric storage device10. The AC-DC conversion unit25and the current generation unit26are connected by a power line L1and a power line L2. A power line L10is connected to the power line L1and a power line L20is connected to the power line L2. The power line L10is connected to a positive electrode terminal of the electric storage unit29, and the power line20is connected to a negative electrode terminal of the electric storage unit29. By this configuration, the power of the electric storage unit29is connected to an input of the current generation unit26.

A diode D1is disposed to the power line L1. The diode D1prevents a backward flow from the electric storage unit29to the AC-DC conversion unit25when the switch SW40is turned on. The power line L10is provided with a fuse FU, the switch SW40, a resistor R and a diode D2from the electric storage unit29side. A mid-point of the resistor R and the diode D2in the power line L10and the power line L20are connected by a line L30, and a capacitor C is connected to the line L30. A diode D3is connected to the power line L20.

The fuse FU is molten down at the time of overcurrent and secures safety of the system. The diode D2prevents the power from the AC power unit3from flowing to the electric storage unit29when the voltage of the electric storage unit29is low. The diode D3prevents the current from flowing the power line L20toward the power line L2. An analogue low-pass filter is formed from the resistor R and the capacitor C and removes a high-frequency component. Incidentally, a circuit configuration shown inFIG. 9is an example, and the power of the electric storage unit29may be supplied to the current generation unit26by a circuit configuration different from the illustrated circuit configuration.

As described above, the electric storage device in the present disclosure can be started up even when there is no external power. Further, the standby power in the standby state can be made zero. Still further, in the case where there is an abnormality in a system of the electric storage device, by outputting the power of the electric storage device through the current generation unit, the relevant system and the electric storage unit are prevented from being electrically connected.

2. Second Embodiment

Since a configuration and an operation of an electric storage device in a second embodiment are the same as a configuration and an operation of the electric storage device10in the first embodiment, duplicated descriptions will be omitted. In the second embodiment, in the case where there is an external power supply in a state where the electric storage device10is shut down, a system of the electric storage device10is autonomously started up and charges the electric storage unit29. Then, in the case where the externally supplied power diminishes or decreases, the electric storage device10autonomously shuts down the system and makes the standby power zero. In the second embodiment, the DC power unit2is described as a solar battery module.

An example of a flow of processing of the electric storage device10in the second embodiment will be described with reference to a flow chart ofFIG. 10. The electric storage device10is shut down in a step S10. That is, the switch SW40is turned off and the electric storage unit29is separated from the system in the electric storage device10. As described above, the standby power in this state is zero. And, the processing proceeds to a step S11.

In a step S11, it is determined whether a generated voltage (PV generated voltage) V of the solar battery module is equal to or greater than a threshold value Vstart. The threshold value Vstartis set to 100 V, for example. When the generated voltage V of the solar battery module is smaller than the threshold value Vstart, the processing returns to the step S11, and the determination of the step S11is repeated. When the generated voltage V of the solar battery module is equal to or greater than the threshold value Vstart, the processing proceeds to a step S12.

In the step S12, the PV charger20is started up. The determination of the above-described step S11is not performed by a microcomputer, etc. but the PV charger20is autonomously started up when the generated voltage V of the solar battery module becomes equal to or greater than the threshold value Vstart. Of course, the generated voltage of the solar battery module may be supervised by the microcomputer, etc. Then, the step proceeds to a step S13.

In the step S13, the PV charger20supplies the power to the input/output unit21. The EMU27and the BMU28connected to the input/output unit21are started up thereby. Then, the processing proceeds to a step S14. In the step S14, as the BMU28is operated, the electric storage unit29is connected to the system of the electric storage device10. Next, the processing proceeds to a step S15.

In the step S15, whether it is necessary to supply the power to the load4is determined. This determination is performed by the EMU27, for example. In the case where there is no need of supplying the power to the load4, the processing proceeds to a step S16. In the case where there is no need of supplying the power to the load4, the processing proceeds to a step S17.

In the step S16, the processing according to a usual charge/discharge mode is performed. The usual charge/discharge mode is a mode for charging/discharging according to, for example, an optional method. That is, in this mode, the power supplied from the solar battery module may be supplied to the load4or the power of the electric storage unit29may be supplied to the load4. Further, while charging the electric storage unit29by the power supplied from the solar battery module, the power supplied from the AC power unit3may be supplied to the load4.

In the step S17, the power formed by the PV charger20is supplied to the electric storage unit29through the input/output unit21and the BMU28. Thus, the electric storage unit29is charged. Next, the processing proceeds to a step S18.

In the step S18, whether the generated voltage V of the solar battery module is equal to or greater than a threshold value Vstopis determined. The threshold value Vstopis set to 90 V, for example. In the case where the generated voltage V of the solar battery module is equal to or greater than the threshold value Vstop, the processing proceeds to a step S19. When the generated voltage V of the solar battery module is smaller than the threshold value Vstop, the processing proceeds to a step S21.

In the step S19, whether it is necessary to supply the power to the load4is determined. This determination is performed by the EMU27, for example. In the case where it is necessary to supply the power to the load4, the processing proceeds to the step S16. As described above, in the step S16, the processing according to the usual charge/discharge mode is performed.

In the case where there is no need of supplying the power to the load4, the processing proceeds to a step S20. In the step S20, whether the state of charge (SOC) of the electric storage unit29is equal to or greater than a threshold value SOCmaxis determined. This determination is performed by the EMU27based on the information transmitted from the BMU28, for example. The threshold value SOCmaxis set to 100%, for example. Incidentally, in the determination in the step S20, in place of the SOC, a depth of discharge (DOD) may be used to determine.

In the case where the SOC of the electric storage unit29is smaller than the threshold value SOCmax, the processing returns to the step S17, and the charge to the electric storage unit29is continued. In the case where the SOC of the electric storage unit29is greater than or equal to the threshold value SOCmax, the processing proceeds to a step S21. In the step S21, the charge is stopped because a capacity of the electric storage unit29increased. Next, the processing proceeds to a step S22.

In the step S22, whether the generated voltage V of the solar battery module is equal to or greater than the threshold value Vstopis determined. In the case where the generated voltage V of the solar battery module is equal to or greater than the threshold value Vstop, the processing returns to the step S20. And, in the case where the SOC is determined to be decreased by the determination in the step S20, the processing returns to the step S17, and the charge to the electric storage unit29is resumed. In the case where the generated voltage V of the solar battery module is smaller than the threshold value Vstop, the processing proceeds to a step S23.

In the step S23, whether a decrement ΔSOC of the capacity of the electric storage unit29is equal to or greater than a threshold value S % is determined. The threshold value S % is set to 2%, for example. In the case where the decrement ΔSOC of the capacity of the electric storage unit29is smaller than the threshold value 2%, the processing returns to the step S22, and the determination of the step S22is performed. In the case where the decrement ΔSOC of the capacity of the electric storage unit29is equal to or greater than the threshold value 2%, the processing proceeds to a step S24.

In the step S24, the electric storage device10is shut down. That is, the EMU27of the electric storage device10controls stoppage of operation of the BMU28, etc. of the electric storage device10, and, after that, turns off itself. Incidentally, in the case where a continuation time of a state where the PV generated voltage is smaller than the threshold value is measured by a timer, and a measurement time has passed a predetermined time, the electric storage device10may be shut down.

The generated voltage of the solar battery module varies depending on the weather, etc. Therefore, without shutting down the electric storage device10immediately after the charge is once stopped, the control in accordance with the generated voltage of the solar battery module is performed. In the case where the generated voltage of the solar battery module is equal to or greater than a certain value and the capacity of the electric storage unit decreased, the charge is performed again.

Further, in the case where a state where the generated voltage of the solar battery module is small continues and the capacity of the electric storage unit decreases by an amount equal to or greater than a certain value, the electric storage device is shut down in order to prevent the power of the electric storage unit from being consumed more by the operation of the EMU, etc.

Thus, in the case where the power is externally supplied in a state where the electric storage device is shut down, the system of the electric storage device is autonomously started up, and the electric storage unit is charged. In the case where the externally supplied power decreased, the electric storage device is shut down, and the standby power in the electric storage device is made zero.

3. Modification Example

In the above, embodiments of the present disclosure have been specifically described. However, the present disclosure can be variously modified without limiting to the above-described embodiments.

In the embodiments described above, the power of the electric storage unit is output through an existing current generation unit when the electric storage device is started up. However, a configuration in which a circuit that generates a constant current is separately disposed and the power of the electric storage unit is output through the circuit may be formed.

The configurations, methods, steps, shapes, materials and numerical values, which are cited in the embodiments described above are only examples, and, as required, configurations, methods, steps, shapes, materials and numerical values, which are different from these may be used. Further, the configurations, methods, steps, shapes, materials and numerical values in each embodiment can be combined with each other as long as a technical contradiction does not occur.

The present technology can also be applied to a so-called cloud system in which the exemplified processes are performed by a plurality of devices in a distributed manner. The present disclosure can be realized as a system that executes the processes exemplified in the embodiments and the modified examples, which is a device that executes at least some of the exemplified processes.

Further, the present disclosure can be realized, without limiting to the devices, as a method, a program, and a recording medium in which the program is recorded.

An electric storage device comprising:

a control unit, a charge/discharge management unit and a current generation unit, which are connected through an input/output unit; and

an electric storage unit that is connected to the charge/discharge management unit and is connected to the current generation unit through a switch.

The electric storage device according to (1), wherein

the control unit and the charge/discharge management unit are turned off and the switch is turned off in a shutdown state, and

the switch is turned on when starting up from the shutdown state.

The electric storage device according to (2), wherein, in response to turning-on of the switch, the current generation unit generates a predetermined current based on power supplied from the electric storage unit, and outputs the generated current to the input/output unit.

The electric storage device according to (3), wherein the control unit and the charge/discharge management unit are turned on in a case where a voltage in the input/output unit reaches a predetermined operating voltage by a current supplied from the current generation unit.

The electric storage device according to any of (1) to (4), wherein

the electric storage unit is charged based on a first current generated by the current generation unit in a case where a voltage of the electric storage unit is smaller than a threshold value, and

the electric storage unit is charged based on a second current that is larger than the first current in a case where the voltage of the electric storage unit is larger than the threshold value.

The electric storage device according to (5), wherein a charge/discharge unit that generates the second current is connected to the input/output unit.

The electric storage device according to any of (1) to (6), wherein the current generation unit is configured with a constant-current direct current (DC)-DC converter.

The electric storage device according to any of (1) to (7), wherein the electric storage unit is configured with a plurality of lithium ion batteries.

The electric storage device according to any of (2) to (8), wherein, in a case where external power is supplied in the shutdown state, the control unit and the charge/discharge management are turned on based on the external power, and the electric storage unit is charged by the power.

An electric storage device comprising:

an electric storage unit; and

a current generation unit that generates a charge current smaller than a usual charge current in a case where a voltage of the electric storage unit is smaller than a threshold value,

wherein power output from the electric storage unit is supplied to the current generation unit at a time of start-up.

A start-up method of an electric storage device, the electric storage device including a control unit, a charge/discharge management unit and a current generation unit, which are connected through an input/output unit, and an electric storage unit that is connected to the charge/discharge management unit and is connected to the current generation unit through a switch, the start-up method comprising:

turning off the control unit and the charge/discharge management unit and turning off the switch in a shutdown state and turning on the switch in a case of start-up from the shutdown state;

generating, by the current generation unit, a predetermined current based on power supplied from the electric storage unit in response to turning-on of the switch, and outputting the generated current to the input/output unit; and

turning on the control unit and the charge/discharge management unit in a case where a voltage in the input/output unit reaches an operating voltage by a current supplied from the current generation unit.

4. Application Example

“Power Storage Device in House as Application Example”

An example in which the present disclosure is applied to a power storage device for houses will be described with reference toFIG. 11. For example, in a power storage device100for a house101, power is supplied to an electric storage device103from a centralized power system102such as thermal power102a, nuclear power102b, and hydraulic power102cthrough a power network109, an information network112, a smart meter107, a power hub108, etc. Together with this, power is supplied to the electric storage device103from an independent power source such as a domestic power generation device104. The power supplied to the electric storage device103is stored. The power used in the house101is supplied using the electric storage device103. The same power storage device can be used not only in the house101but also in buildings.

The house101is provided with the domestic power generation device104, a power consumption device105, the electric storage device103, a control device110controlling each device, the smart meter107, and sensors111acquiring various kinds of information. The devices are connected through the power network109and the information network112. A solar cell, a fuel cell, etc. are used as the domestic power generation device104, and generated power is supplied to the power consumption device105and/or the electric storage device103. The power consumption device105is a refrigerator105a, an air conditioner105b, a television receiver105c, a bath105d, etc. Moreover, the power consumption device105includes an electric vehicle106. The electric vehicle106is an electric car106a, a hybrid car106b, and an electric motorcycle106c.

The electric storage device103is constituted by secondary batteries or a capacitor. For example, the electric storage device103is constituted by lithium ion secondary batteries. The electric storage device10of the present disclosure described above is applied to the electric storage device103. The lithium ion secondary battery may be a stationary type or may be one used in the electric vehicle106. The smart meter107has a function of measuring a use amount of commercial power and transmitting the measured use amount to an electric power company. The power network109may be of one of direct current power supply, alternating current power supply, and noncontact power supply or of the combination of a plurality of them.

The various sensors111are a human sensor, an illumination sensor, an object detection sensor, a power consumption sensor, a vibration sensor, a contact sensor, a temperature sensor, an infrared sensor, etc., for example. The information acquired by the various sensors111is transmitted to the control device110. Weather conditions, human conditions, etc. are grasped based on the information from the sensors111, and it is possible to automatically control the electric consumption device105so that energy consumption is minimum. Moreover, the control device110can transmit information about the house101to an external electric power company, etc. through an internet.

The power hub108performs processing of branch of a power line, direct current-alternating current conversion, etc. As a communication system of the information network112connected to the control device110, there are a method of using a communication interface such as a universal asynchronous receiver-transmitter (UART (transmission and reception circuit for asynchronous serial communication)) and a method of using a sensor network by a wireless communication standard such as Bluetooth (registered trademark), ZigBee (registered trademark), and Wi-Fi (registered trademark). The Bluetooth system is applied to multimedia communication, and the communication of one-to-many connection is possible. The ZigBee uses a physical layer of institute of electrical and electronics engineers (IEEE) 802.15.4. The IEEE802.15.4 is a name of a short distance wireless network standard referred to as personal area network (PAN) or Wireless (W) PAN.

The control device110is connected to an external server113. The server113may be managed by any of the house101, an electric power company, and a service provider. The information transmitted and received by the server113is power consumption information, life pattern information, power rates, weather information, natural disaster information, and information about power transaction, for example. Such information may be transmitted and received by a domestic electric consumption device (a television receiver, for example), and may be transmitted and received by a device outside home (a cellular phone, etc., for example). Such information may be displayed on a device having a display function, e.g. a television receiver, a cellular phone, personal digital assistants (PDA), etc.

The control device110controlling each unit is constituted by a CPU, a RAM, a ROM, etc., and stored in the electric storage device103in this example. The control device110is connected to the electric storage device103, the domestic power generation device104, the power consumption device105, the various sensors111, and the server113through the information network112, and has a function of adjusting a use amount of commercial power and a power generation amount. In addition, the control device110may have a function of performing power transaction in the power market, etc.

As illustrated above, not only power from the centralized power system102such as the thermal power102a, the nuclear power102b, and the hydraulic power102cbut also power generated by the domestic power generation device104(solar power generation, wind power generation) can be stored in the electric storage device103. Therefore, even when power generated by the domestic power generation device104is varied, it is possible to perform control of keeping electric energy transmitted to the outside constant or discharging only a required amount. For example, it is also possible to adopt a use in which power obtained by solar power generation is stored in the electric storage device103and, at the same time, midnight power that is cheaper in cost during night is stored in the electric storage device103so that the power stored by the electric storage device103is discharged and used in the daytime period when the cost is high.

Note that although this example describes the case in which the control device110is stored in the electric storage device103, the control device110may be stored in the smart meter107or may be constituted individually. Moreover, the power storage device100may be used for a plurality of households in an apartment house, or may be used for a plurality of detached houses.

“Power Storage Device in Vehicle as Application Example”

An example in which the present disclosure is applied to the power storage device for vehicles will be described with reference toFIG. 12.FIG. 12schematically illustrates an example of a configuration of a hybrid vehicle adopting a series hybrid system to which the present disclosure is applied. The series hybrid system is a car traveling by power driving force conversion device using power generated by a power generator driven by an engine or such power stored temporarily in a battery.

On this hybrid vehicle200, an engine201, a power generator202, a power driving force conversion device203, a driving wheel204a, a driving wheel204b, a wheel205a, a wheel205b, a battery208, a vehicle control device209, various sensors210, and a charging port211are mounted.

The hybrid vehicle200travels with the power driving force conversion device203as a driving source. One example of the power driving force conversion device203is a motor. The power driving force conversion device203is driven by power of the battery208, and the rotation force of the power driving force conversion device203is transmitted to the driving wheels204aand204b. Note that with the use of direct current-alternating current (DC-AC) or inverse conversion (AC-DC conversion) at necessary parts, the power driving force conversion device203can be also applied to an alternating current motor and a direct current motor. The various sensors210control engine speed through the vehicle control device209and controls opening of a throttle valve not illustrated (throttle opening). The various sensors210include a speed sensor, an acceleration sensor, an engine speed sensor, etc.

The rotation force of the engine201is transmitted to the power generator202, and power generated by the power generator202using the rotation force can be stored in the battery208.

When the speed of the hybrid vehicle is reduced by a braking mechanism not illustrated, the resistance at the time of reduction of speed is added to the power driving force conversion device203as rotation force, and regenerative electric power generated by the power driving force conversion device203using the rotation force is stored in the battery208.

The battery208is connected to an external power source of the hybrid vehicle, and thus receives power supply from the external power source with the charging port211as an input port and can also store the received power. The electric storage device10, for example, may be applied to the battery208.

Although not illustrated, there may be provided an information processing device performing information processing regarding vehicle control based on information about the secondary batteries. Such an information processing device includes an information processing device performing battery remaining amount display based on information about a battery remaining amount.

The above has described, as an example, the series hybrid car traveling by a motor using power generated by the power generator driven by the engine or such power temporarily stored in the battery. However, the present disclosure can be also applied effectively to a parallel hybrid car having output of both an engine and a motor as a driving source and using three systems of travel only by the engine, travel only by the motor, and travel by the engine and the motor while switching them appropriately. Moreover, the present disclosure can be also applied effectively to a so-called electric vehicle, which travels by drive by only a driving motor without an engine.

REFERENCE SIGNS LIST

1general electric storage device2DC power unit3AC power unit4load10electric storage device in the present disclosure (one example)21input/output unit24charge/discharge unit26current generation unit27EMU28BMU29electric storage unit