power supply system

Abstract

The present invention relates to a power supply system. In existing power supply systems, there is a problem that even a battery of limited size cannot supply power for a long time. The power supply system of the present invention includes: a battery capable of charging and discharging, and outputting power at the battery output voltage; a charge and discharge control circuit, which controls the charging and discharging of the battery; a power supply, which has at least power supply capability; and a control unit, which controls the operation of the charge and discharge control circuit, wherein the control unit: when the size of the power to be supplied is lower than the upper limit of the power supply capability of the power supply, controls the charge and discharge control circuit to supply the power to be supplied based on the power output of the power supply, and charges the battery with the difference in power obtained by subtracting the power to be supplied from the upper limit of the power supply capability of the power supply; when the size of the power to be supplied is greater than the upper limit of the power supply capability of the power supply, controls the charge and discharge control circuit to supply the power to be supplied from both the power supply and the battery.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefits of Japanese Patent Application No. 2020-191384 filed on November 18, 2020, and Japanese Patent Application No. 2021-139513 filed on August 30, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a power supply system including a storage battery and a generator capable of supplying electric power to a power supply destination such as a home. Background Art

[0004] In recent years, due to the increase in environmental awareness or disaster prevention awareness, the use of household batteries has become popular. However, there is a problem that the capacity of household batteries installed in the home is relatively small to meet the power demand when a power outage occurs for several days during a disaster. In addition, as another method of supplying electricity to the home, it is considered to install a generator. As long as the fuel can be secured, the generator can provide continuous power supply. Therefore, in Japanese Patent Laid-Open No. 2020-102916, an example of a power supply system is disclosed, which uses an electric vehicle as a movable battery, and connects the electric vehicle's driving battery and fixed battery in parallel.

[0005] The power supply system described in Japanese Patent Laid-Open No. 2020-102916 includes: a stationary battery installed at a communications business office and discharging to a load, an electric vehicle equipped with a traveling battery for mobility, and a DC interconnection (DC Interconnection) charger and discharger that connects the traveling battery and the stationary battery in parallel when the electric vehicle returns to the communications business office. When the stationary battery discharges to the load, the traveling battery is discharged through the charger and discharger. Summary of the Invention

[0006] Although the technology described in Japanese Patent Application Laid-Open No. 2020-102916 allows for longer operating time by connecting to an electric vehicle than when using only a stationary battery, when the electric vehicle is not in use, the vehicle is operated using only the stationary battery. Therefore, even with the technology described in Japanese Patent Application Laid-Open No. 2020-102916, there is a problem in not being able to significantly extend operating time.

[0007] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to realize a power supply system that is equipped with a storage battery of limited size and can supply power for a long period of time.

[0008] One aspect of the power supply system of the present invention includes: a battery capable of being charged and discharged to output power at a battery output voltage; a charge and discharge control circuit that controls the charge and discharge power of the battery; a power supply that has at least a power supply capability; and a control unit that controls the operation of the charge and discharge control circuit, wherein the control unit controls, when the magnitude of the supply target power is lower than an upper limit value of the power supply capability of the power supply, the charge and discharge control circuit to supply the supply target power based on the power output by the power supply and to charge the battery with the difference in power obtained by subtracting the supply target power from the upper limit value of the power supply capability of the power supply, wherein the supply target power is the power consumed by the power supply target to which power is supplied by the power supply, and when the magnitude of the supply target power is greater than the upper limit value of the power supply capability of the power supply, the charge and discharge control circuit is controlled to supply the supply target power from both the power supply and the battery.

[0009] In the power supply system of the present invention, if the power generation capacity of the power generation device exceeds the power demand of the supply target, the battery is charged. If the power generation capacity of the power generation device is lower than the power demand of the supply target, power is supplied using both the battery and the power generation device.

[0010] According to the power supply system of the present invention, it is possible to realize a power supply system that is equipped with a storage battery of limited size and can supply electric power for a long period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a block diagram of the power supply system according to the first embodiment.

[0012] Figure 2 This is a flowchart illustrating the operation of the power supply system according to the first embodiment.

[0013] Figure 3 This is a table explaining an example of the operation of the power supply system according to the second embodiment.

[0014] Figure 4 This is a table illustrating another example of the operation of the power supply system according to the second embodiment.

[0015] Figure 5 This is a table illustrating still another example of the operation of the power supply system according to the second embodiment.

[0016] Figure 6 This is a flowchart illustrating the operation of the power supply system according to the third embodiment.

[0017] Figure 7 This is a block diagram of a power supply system according to a fourth embodiment.

[0018] Figure 8 This is a block diagram of a power supply system according to the fifth embodiment. DETAILED DESCRIPTION

[0019] In order to make the description clear, the following description and drawings are appropriately omitted and simplified. In addition, the various components recorded in the drawings as functional blocks for performing various processes can be composed of a CPU (Central Processing Unit), a memory, and other circuits in terms of hardware, and implemented by programs loaded into the memory in terms of software. Therefore, it should be understood by those skilled in the art that these functional blocks can be implemented in various forms by hardware alone, software alone, or a combination thereof, and are not limited to any one of them. In addition, in the drawings, the same reference numerals are used for the same components, and repeated descriptions are omitted as needed.

[0020] Furthermore, the above-mentioned program can be stored using various types of non-transitory computer-readable media and provided to the computer. Non-transitory computer-readable media include various types of tangible recording media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., floppy disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (read-only memories), CD-Rs, CD-R / Ws, semiconductor memories (e.g., mask ROMs, PROMs (programmable ROMs), EPROMs (erasable PROMs), flash ROMs, RAMs (random access memories)). In addition, the program can also be provided to the computer via various types of temporary computer-readable media. Examples of temporary computer-readable media include electrical signals, optical signals, and electromagnetic waves. Temporary computer-readable media can provide the program to the computer via wired communication paths such as wires and optical fibers, or wireless communication paths.

[0021] Implementation Method 1

[0022] Figure 1 FIG. 1 shows a block diagram of a power supply system 1 according to Embodiment 1. Figure 1 As shown, the power supply system 1 includes a battery 10 , a charge and discharge control circuit 11 , a first conversion circuit (eg, an AC / DC conversion circuit 12 ), a second conversion circuit (eg, a power conversion circuit 13 ), a control unit 14 , and a power measurement unit 15 .

[0023] In addition, a power source having at least the ability to supply electric power is connected to the power supply system 1. In the power supply system 1 according to the first embodiment, a power generation device 20 that only generates and outputs electric power is connected as a power source. The power generation device 20 includes, for example, a solar panel, a hybrid vehicle to which a fuel that can be added to generate electric power can be added, a generator, or a battery that chemically stores / releases electric energy (e.g., a fuel cell). In addition, a rechargeable and dischargeable battery can also be used as a power source, but an example of using a battery is described in other embodiments. In the first embodiment, as the power generation device 20, an example of using a generator having a maximum power generation capacity of about 1500W and outputting 100V AC power is described. When a car is used as the power generation device 20, the car's 100V AC power socket can be used. In addition, in the car's power supply or household generator, as a general specification, it is possible to output 100V AC power with a maximum power generation capacity of about 1500W.

[0024] Preferred vehicles are hybrid vehicles or fuel cell vehicles that use a combination of an internal combustion engine (using gasoline or hydrogen) and a battery as their driving source. Electric vehicles that do not use gasoline or other fuels are also considered as vehicles powered by batteries, but using only the battery installed in an electric vehicle will inevitably reduce the maximum power generation capacity (battery capacity). On the other hand, hybrid vehicles, etc., can generate electricity using gasoline or hydrogen, thus increasing their maximum power generation capacity. This allows for continued power supply even during a power outage, which takes time until power is restored. Furthermore, the ability to refuel with gasoline allows for even longer periods of power supply.

[0025] Furthermore, in the power supply system 1 according to the first embodiment, the target of power supply is assumed to be, for example, a typical residence or a power grid line. When the power supply target is a residence, the target AC high-voltage power supply is supplied to the target at 200V, and the target AC low-voltage power supply is supplied at 100V. Furthermore, when the power supply target is a power grid line, the target AC high-voltage power supply is supplied at 200V, and the target AC low-voltage power supply is supplied at 100V, depending on the use of the power grid line. Furthermore, the power supply system 1 according to the first embodiment can also be used as a power storage system for a power system connected to the power grid.

[0026] The battery 10 can be charged and discharged, and outputs DC power at the battery output voltage. Figure 1The example shown shows 48V, but the battery output voltage does not necessarily need to be 48V. For example, a battery capable of outputting 1000W at room temperature can be used, using a single module (six cells) of nickel-metal hydride batteries used in hybrid vehicles. Alternatively, a lithium-ion secondary battery can be used. Using high-output batteries reduces the minimum unit of capacity, allowing for small adjustments to the system capacity, making it easier to set the system's output power to the minimum required.

[0027] Furthermore, the storage battery 10 is preferably composed of a plurality of cells. Since it is composed of a plurality of cells, the system can be operated even if some of the cells fail. In particular, in the event of a power outage from the power company, it is necessary to avoid the system failing and becoming unusable, so it is preferable to connect the batteries in parallel, but a system connected in series can also be used. Furthermore, since a parallel circuit using a small number of cells is configured, battery replacement is easy in the event of a battery failure, and commercially available reconstructed batteries can be utilized, making repairs and replacements easy and inexpensive. Furthermore, by configuring the circuit in parallel, some of the cells in the parallel circuit can be removed and used as mobile batteries. In this case, large nickel-metal hydride batteries that are not suitable for portability can be used exclusively as fixed storage batteries, and lightweight and small lithium-ion secondary batteries that are suitable for portability can be used as part of the portable battery pack, thereby mixing nickel-metal hydride batteries and lithium-ion secondary batteries within the system.

[0028] The charge and discharge control circuit 11 controls the charge and discharge power of the battery 10. More specifically, the charge and discharge control circuit 11 cooperates with the AC / DC conversion circuit 12 to control the amount of power charged to the battery 10 and the amount of power discharged from the battery 10 based on the instructions of the control unit 14. Figure 1 In the example shown, the charge and discharge control circuit 11 does not perform voltage conversion, but the charge and discharge control circuit 11 may also have a voltage conversion function.

[0029] The AC / DC conversion circuit 12 is connected to the power generation device 20 and converts the AC generator output voltage output by the power generation device 20 into a DC battery output voltage. Figure 1 In the example shown, the AC / DC converter circuit 12 converts the 100 V AC voltage output by the power generator 20 into a 48 V DC voltage, which is the battery output voltage. Furthermore, the AC / DC converter circuit 12 adjusts the amount of power drawn from the power generator 20 based on instructions from the control unit 14 .

[0030] The power conversion circuit 13 converts the battery output voltage (for example, 48V DC voltage) into AC supply target power. Figure 1In the example shown, the power conversion circuit 13 outputs a converted voltage of 200 V AC to the power supply destination. Alternatively, if the power supply destination utilizes 100 V AC power, the 200 V AC voltage is converted to 100 V AC voltage at a distribution board at the power supply destination.

[0031] The power conversion circuit 13 includes a third conversion circuit (e.g., a DC / AC conversion circuit 13a) and a fourth conversion circuit (e.g., a transformer 13b). The DC / AC conversion circuit 13a converts the generator output voltage (48V DC voltage) into AC low-voltage power (100V AC voltage). Furthermore, the transformer 13b converts the low-voltage power (100V AC voltage) into AC high-voltage power (200V AC voltage). Furthermore, in the power supply system 1 according to Embodiment 1, the power demand of the power supply destination is measured by the power measurement unit 15.

[0032] The control unit 14 can be implemented, for example, by a program-executable computing device such as an MCU (microcontroller unit) or dedicated hardware. When a program-executable computing device is used as the control unit 14, a power supply control program that implements the operations described below is loaded into the control unit 14 through a program executed by the control unit 14.

[0033] The control unit 14 controls the operation of the charge and discharge control circuit 11, the AC / DC converter circuit 12, and the power conversion circuit 13. The control unit 14 controls the operation of the charge and discharge control circuit 11, the AC / DC converter circuit 12, and the power conversion circuit 13 based on the charge rate of the storage battery 10 and the power generation capacity of the power generation device 20. More specifically, when the amount of the target power to be supplied is lower than the upper limit of the power generation capacity of the power generation device 20, the control unit 14 controls the charge and discharge control circuit 11, the AC / DC converter circuit 12, and the power conversion circuit 13 to supply the target power based on the power output by the power generation device 20. In this case, the control unit 14 also controls the charge and discharge control circuit 11, the AC / DC converter circuit 12, and the power conversion circuit 13 to charge the storage battery 10 with the difference in power obtained by subtracting the target power from the upper limit of the power generation capacity of the power generation device 20. Furthermore, when the magnitude of the target power to be supplied is greater than or equal to the upper limit of the power generation capacity of the power generation device 20, the control unit 14 controls the charge and discharge control circuit 11, the AC / DC converter circuit 12, and the power conversion circuit 13 so that the target power to be supplied is supplied from both the power generation device 20 and the storage battery 10. In this embodiment, the upper limit of the power generation device 20 is defined as the upper limit of the power generation capacity of the power generation device 20, but it may also be a control upper limit.

[0034] Here, the operation of the power supply system 1 according to the first embodiment will be described. In the power supply system 1 according to the first embodiment, power can be supplied to the supply target even if only the storage battery 10 is used. However, the operation when the power generation device 20, which is one of the characteristics of the power supply system 1, is connected will be described below. For this purpose, Figure 2 A flowchart illustrating the operation of the power supply system 1 according to the first embodiment is shown. Figure 2 1 is a diagram illustrating the operation of the power supply system 1 when the power generation device 20 is connected to the power supply system 1 .

[0035] like Figure 2 As shown, in the power supply system 1, when the power generation device 20 is connected to the AC / DC conversion circuit 12, power supply from the power generation device 20 begins (step S1). Next, in the power supply system 1, the control unit 14 checks the charge rate of the battery 10 to determine whether the battery 10 can output power (step S2). In this step S2, if the charge rate (SOC) of the battery 10 is below a preset battery output threshold (for example, 40%), the control unit 14 determines that battery output is not possible. On the other hand, if the charge rate of the battery 10 is higher than 40%, the control unit 14 determines that power supply from the battery 10 can continue.

[0036] If, in step S2, it is determined that power cannot be supplied from battery 10 ("NO" branch of step S2), the charge / discharge control circuit 11, AC / DC converter circuit 12, and power converter circuit 13 are controlled to charge battery 10 with power extracted from power generator 20 (step S3). In step S3, battery 10 is charged until the charge rate reaches approximately 50%, for example. Thus, the determination in step S2 indicates that power can be supplied from battery 10 to the target device.

[0037] On the other hand, if it is determined in step S2 that power supply from battery 10 is possible ("YES" branch of step S2), control unit 14 determines whether the power demand of the power supply target is less than the upper limit of the output capacity of power generator 20 (step S4). If it is determined in step S4 that the power demand of the power supply target is less than the upper limit of the power generation capacity of power generator 20 ("No" branch of step S4), in power supply system 1, control unit 14 controls charge and discharge control circuit 11, AC / DC converter circuit 12, and power conversion circuit 13 to charge battery 10 using the difference between the power demand and the upper limit of the power generation capacity of power generator 20 until battery 10 reaches the upper limit voltage (e.g., fully charged) (steps S4, S5, and S7). Then, after battery 10 reaches full charge, control unit 14 stops charging battery 10 and reduces the power generation capacity of power generator 20 to a level sufficient to supply the power demand of the power supply target (steps S4, S5, and S6).

[0038] Next, in step S4, if it is determined that the power demand of the power supply destination exceeds the upper limit of the power generation capacity of the power generation device 20 ("Yes" branch of step S4), the control unit 14 in the power supply system 1 controls the charge and discharge control circuit 11, the AC / DC converter circuit 12, and the power conversion circuit 13 to supply power to the power supply destination not only from the power generation device 20 but also from the storage battery 10 (step S8). At this time, the control unit 14 monitors the charge rate of the storage battery 10 and calculates the allowable output time of the storage battery 10 (step S9).

[0039] If the battery 10's output time limit is less than the preset threshold value A ("Yes" branch of step S10), the control unit 14 notifies the user to request a reduction in power demand (step S11). Following the notification in step S11, the power supply system 1 executes the process of step S2. On the other hand, if the battery 10's output time limit is greater than the preset threshold value A ("No" branch of step S10), the control unit 14 repeats the process from step S4 onward.

[0040] The threshold value A is set to a time sufficient for the user to change their power demand. For example, approximately 15 minutes is considered. Alternatively, the charge rate of the battery 10 may be used as the threshold value A and the judgment criterion instead of time.

[0041] As described above, the power supply system 1 according to Embodiment 1 supplies power to the target device using the power output by the power generator 20 after the power generator 20 is connected. If there is any excess power generation capacity in the power generator 20, this excess is used to charge the storage battery 10. Thus, the power supply system 1 according to Embodiment 1 can extend the time during which power can be supplied by the storage battery 10 while the power generator 20 is removed.

[0042] Furthermore, in the power supply system 1 according to Embodiment 1, if the power demand of a target user exceeds the upper limit of the power generation capacity of the power generation device 20, the shortfall can be compensated by power output from the storage battery 10. Typically, a household requires approximately 3000W to 6000W of power for consumption, and the 1500W typical specification of a generator may not be sufficient. However, in the power supply system 1 according to Embodiment 1, power demand exceeding the power generation capacity of the power generation device 20 is met by power output from the storage battery 10, eliminating the need to limit the power demand of the target user.

[0043] Implementation Method 2

[0044] In the second embodiment, the details of the charging process in the power supply system 1 will be described. Figure 3 A table illustrating an example of the operation of the power supply system according to Embodiment 2 is shown. In the power supply system 1, the control unit 14 controls the charge and discharge control circuit 11 and the AC / DC converter circuit 12 to change the power generation capacity of the AC generator allocated to charging the battery 10 based on the charge rate of the battery 10 and the amount of power to be supplied.

[0045] Figure 3 The illustrated example describes the power allocated by control unit 14 to charge battery 10 when battery 10 is left at a temperature determined to be normal (e.g., approximately 25°C). Control unit 14 allocates the remaining power, obtained by subtracting the power demand from the upper limit of power generation device 20's power generation capacity, to charge battery 10, and varies this allocated power based on the charge rate of battery 10. This allocation ratio is altered by control unit 14 controlling charge and discharge control circuit 11.

[0046] exist Figure 3 In the example shown, the control unit 14 does not charge the battery 10 when the power demand is higher than the power generation upper limit and the power supply by the power generation device 20 alone is insufficient (1500 W to 3000 W in this embodiment).

[0047] When the power demand is below the upper limit of power generation and the power supply is sufficient (in this embodiment, 1000 W or more and less than 1500 W), the control unit 14 allocates the remaining power generated by the power generator 20 to charging the battery 10 as follows. When the charge rate of the battery 10 is less than 40%, the entire remaining power is allocated to charging the battery 10. Furthermore, when the charge rate of the battery 10 is less than 50%, 80% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 60%, 60% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 70%, 40% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 80%, 20% of the remaining power is allocated to charging the battery 10. Furthermore, when the charge rate is 80% or higher, charging using the remaining power is not performed.

[0048] When the power demand is below the upper limit of power generation and the power supply is sufficient (less than 1000 W in this embodiment), the control unit 14 allocates the remaining power generated by the power generator 20 to charging the battery 10 as follows. When the charge rate of the battery 10 is less than 50%, the entire remaining power is allocated to charging the battery 10. Furthermore, when the charge rate of the battery 10 is less than 60%, 80% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 70%, 60% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 70%, 20% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 90%, 20% of the remaining power is allocated to charging the battery 10. Furthermore, when the charge rate is 90% or higher, charging using the remaining power is not performed.

[0049] In addition, the control unit 14 determines the ambient temperature of the location where the battery 10 is placed based on the Figure 3 The remaining power is charged to the battery 10 using a different map from the distribution map shown. Figure 4 A table illustrating another example of the operation of the power supply system according to the second embodiment is shown. Figure 4 The distribution map shown explains the charging power that the control unit 14 distributes to the storage battery 10 when the storage battery 10 is left at a temperature determined to be high (eg, approximately 40° C. or higher).

[0050] exist Figure 4 In the example shown, the control unit 14 does not charge the battery 10 when the power demand is higher than the power generation upper limit and the power supply by the power generation device 20 alone is insufficient (1500 W to 3000 W in this embodiment).

[0051] When the power demand is below the upper limit of power generation and the power supply is sufficient (in this embodiment, 1000 W or more and less than 1500 W), the control unit 14 allocates the remaining power generated by the power generator 20 to charging the battery 10 as follows. When the charge rate of the battery 10 is less than 20%, the entire remaining power is allocated to charging the battery 10. Furthermore, when the charge rate of the battery 10 is less than 30%, 80% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 40%, 60% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 50%, 40% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 60%, 20% of the remaining power is allocated to charging the battery 10. Furthermore, when the charge rate is 60% or higher, charging using the remaining power is not performed.

[0052] When the power demand is below the upper limit of power generation and the power supply is sufficient (less than 1000 W in this embodiment), the control unit 14 allocates the remaining power generated by the power generator 20 to charging the battery 10 as follows. When the charge rate of the battery 10 is less than 30%, the entire remaining power is allocated to charging the battery 10. Furthermore, when the charge rate of the battery 10 is less than 40%, 80% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 50%, 60% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 60%, 40% of the remaining power is allocated to charging the battery 10. When the charge rate is less than 70%, 20% of the remaining power is allocated to charging the battery 10. Furthermore, when the charge rate is 70% or higher, charging using the remaining power is not performed.

[0053] As described in Embodiment 2, when the charge level of battery 10 is sufficient, control unit 14 allocates only a portion of the remaining power to charging battery 10. By thus using the remaining power generation capacity of power generation unit 20 to charge battery 10, fuel consumption by power generation unit 20 can be reduced. Furthermore, by using only a portion of the remaining power to charge battery 10, it is easier to cope with sudden changes in power demand. Furthermore, when the charge rate of battery 10 is low, by allocating the entire remaining power to charging battery 10, the charge rate of battery 10 can be quickly restored to a level sufficient for power supply from battery 10.

[0054] Furthermore, the control unit 14 changes the relationship between the charging rate and the proportion of surplus power allocated for charging based on the temperature of the location where the battery 10 is placed. As the temperature of the battery 10 increases, the battery's charging efficiency decreases, thus limiting the amount of charging power in areas with high charging rates. On the other hand, although not specifically mentioned above, the charging rate can be increased at room temperature to allocate the entire surplus power to charging. By controlling charging based on the temperature characteristics of the battery's 10's outputtable power, battery degradation can be suppressed while maximizing the total outputtable time.

[0055] Here, considering the charge and discharge characteristics of the battery 10, the charging current is characterized by being small in a region with a high charge rate. Figure 3 and Figure 4 The distribution map shown is an example in which the less the remaining power allocable to charging, the less charging is done on the storage battery 10 with a higher charging rate. However, other distribution maps are conceivable depending on the characteristics of the storage battery 10 described above. Figure 5 This is a table illustrating still another example of the operation of the power supply system according to the second embodiment.

[0056] Figure 5 The example shown is a distribution map when the temperature of the installation location of the power generation device 20 is normal temperature. Figure 5 In the example shown, the less the remaining power is, the higher the charging rate of the battery 10 is charged. By using such a distribution map, it is possible to improve the charging efficiency while suppressing the fuel consumption of the battery 10. Figure 5 The example shown can also be used with Figure 3 、 4 The example shown also uses two maps separately according to temperature.

[0057] Implementation 3

[0058] In the third embodiment, the operation of the power supply system 1 when the fuel for operating the power generation device 20 becomes low will be described. Figure 6 A flowchart illustrating the operation of the power supply system according to the third embodiment is shown. Figure 6 1 is a diagram illustrating the operation of the power supply system 1 when the generator is disconnected from the power supply system after the fuel amount of the power generation device 20 is reduced. Figure 6 In the illustrated example, the power generation device 20 performs a forced charging process executed by a user's operation of issuing a forced charging instruction to the power supply system 1 after the fuel is reduced.

[0059] exist Figure 6In the example shown, the control unit 14 first continues charging the battery 10 via the power generation device 20 until the battery 10 is fully charged (steps S21 and S22). Then, upon completion of charging of the battery 10, the control unit 14 stops the power generation device 20 (step S23). Subsequently, upon completion of charging of the battery 10, the control unit 14 notifies the user of the completion of charging (step S24).

[0060] As described above, in the power supply system 1 according to the third embodiment, even when the power generation device 20 is disconnected from the power supply system 1 due to refueling of the power generation device 20, the battery 10 can continue to supply power at the maximum amount. In particular, when using an automobile as the power generation device 20, it is important to charge the battery 10 in advance to prevent power supply interruption.

[0061] Implementation 4

[0062] In the fourth embodiment, another aspect of the power supply system 1 described in the first embodiment will be described. Figure 7 FIG. 2 shows a block diagram of a power supply system 2 according to Embodiment 4. Figure 7 As shown, the power supply system 2 according to the fourth embodiment is a system in which a photovoltaic panel 30 and a power conditioner 31 are added to the power supply system 1 according to the first embodiment.

[0063] The photovoltaic panel 30 is a power generation device that generates electricity using sunlight. The power conditioner 31 converts the voltage of the power generated by the photovoltaic panel 30 into a high-voltage supply voltage to be supplied to a high-voltage power supply destination.

[0064] In this manner, by installing photovoltaic panels 30 and power conditioners 31 in power supply system 2, it is possible to generate power not only from power generation device 20 but also from other sources, thereby further improving the power supply capacity of the power supply system. Furthermore, the power generated by photovoltaic panels 30 can be charged to battery 10 in the same manner as the power generated by power generation device 20.

[0065] Implementation 5

[0066] If the storage battery 10 used in the power supply system prioritizes capacity, measures such as increasing the number of batteries connected in parallel are necessary to improve adaptability to output fluctuations, leading to increases in system size and cost. Therefore, by replacing the power generation device 20 as a power source with a storage battery 40 that prioritizes capacity and combining storage batteries 10 with output-focused batteries, combining batteries with different characteristics can improve adaptability to output fluctuations while simultaneously suppressing increases in system size and cost. Therefore, in Embodiment 5, an example using the storage battery 40 as a power source is described.

[0067] Figure 8 FIG. 1 shows a block diagram of a power supply system 3 according to Embodiment 5. Figure 8 As shown, the power supply system 3 according to the fifth embodiment includes a storage battery 40 instead of the power generation device 20, a charge and discharge control circuit 42 instead of the AC / DC conversion circuit 12, and a control unit 44 instead of the control unit 14. Furthermore, in the power supply system 3 according to the fifth embodiment, an output-oriented storage battery having high adaptability to rapid fluctuations in output power is used as the storage battery 10.

[0068] Battery 40 is, for example, a capacity-focused battery with a large capacity relative to its volume. Compared to the performance of battery 10, battery 40 has a large capacity but poor adaptability to sudden fluctuations in output. Battery 10 and battery 40 can be lithium-ion batteries (ternary system - liquid system), lithium-ion batteries (iron phosphate system - liquid system), lithium-ion batteries (LTO system - liquid system), nickel-metal hydride batteries, lead-acid batteries, RF (Redox Flow) batteries, NAS batteries, and the like. NAS batteries use sodium (Na) at the negative electrode and sulfur (S) at the positive electrode, and fine ceramics as the electrolyte separating the two electrodes, allowing for repeated charging and discharging through a chemical reaction between sulfur and sodium ions. The relative performance of the combined batteries is considered to determine which battery to use as battery 10 or battery 40.

[0069] The charge and discharge control circuit 42 is provided for the battery 40 and controls the charging and discharging of the battery 40 according to instructions from the control unit 44. The control unit 44 varies the ratio of the amount of power extracted from the battery 10 to the amount of power extracted from the battery 40 based on the rate of change in the target power and the states of the batteries 10 and 40. Specifically, the control unit 44 determines the power that the battery 40 can output based on the battery states, such as the charge rate and degree of degradation (output resistance, etc.) of the batteries 10 and 40. The control unit 44 controls the charge and discharge control circuit 11 and the charge and discharge control circuit 42 so that the difference between the amount and fluctuation of the target power and the power that can be output from the battery 40 is compensated by the power output from the battery 10. Thus, the power supply system 3 according to the fifth embodiment can cope with fluctuations in the target power that exceed the output fluctuation capacity of the battery 40.

[0070] More specifically, the control unit 44 controls the charge-discharge control circuit 11 and the charge-discharge control circuit 42 so that power is supplied primarily from the battery 40 to the target device. Furthermore, if the rate of change in the power of the target device is estimated to exceed the output fluctuation capacity of the battery 40, the control unit 44 issues a discharge instruction to the charge-discharge control circuit 11 to actively supply power from the battery 10. Furthermore, if the battery 40 is removed or is being actively charged from the system power supply or solar panels, the control unit 44 issues an instruction to urge discharge from the battery 10 to the charge-discharge control circuit 11 and the charge-discharge control circuit 42.

[0071] In the power supply system 3 according to the fifth embodiment, by combining storage batteries with different characteristics, it is possible to improve the ability to follow output fluctuations while suppressing increases in device size and cost. In addition, by considering the status of each storage battery in the control unit 44 to respond to power demand, the storage batteries can be used safely for a long time.

[0072] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the present invention can be applied not only to household use but also to large-scale power supply systems such as commercial use and power systems.

Claims

1. A power supply system, comprising: a battery capable of being charged and discharged and outputting electricity at a battery output voltage; a charge and discharge control circuit, the charge and discharge control circuit controlling the charge and discharge power of the battery; a power supply, the power supply having at least power supply capability; as well as a control unit, the control unit controlling the operation of the charge and discharge control circuit, The control unit, When the magnitude of the target power is lower than an upper limit of the power supply capacity of the power source, the charge and discharge control circuit is controlled so that the target power is supplied based on the power output by the power source and the storage battery is charged with a difference in power obtained by subtracting the target power from the upper limit of the power supply capacity of the power source; the target power being the power consumed by the target power supplied by the power source; controlling the charge and discharge control circuit so as to supply the target power from both the power supply and the storage battery when the magnitude of the target power is equal to or greater than an upper limit of the power supply capability of the power supply; The control unit controls the charge and discharge control circuit to change the power supply capacity of the power source allocated to charging the storage battery based on the charge rate of the storage battery and the magnitude of the supply target power.

2. The power supply system according to claim 1, wherein: The control unit controls the charge and discharge control circuit to further change the power supply capacity of the power source allocated to charging the storage battery based on the ambient temperature of a location where the storage battery is installed.

3. The power supply system according to claim 1, wherein: The control unit, When a forced charging instruction is given by a user, the charge and discharge control circuit is controlled to charge until the battery is fully charged, and a charging completion notification is notified to the user when charging of the battery is completed. The power supply system according to claim 1 , wherein: The power source includes any one of a solar panel, a hybrid vehicle capable of adding fuel that can be used to generate electricity, a generator, or a secondary battery. 5 . The power supply system according to claim 1 , further comprising a photovoltaic panel for supplying electric power to the supply target. The power supply system according to claim 1 , wherein: The power source is a secondary battery having a higher priority on storage capacity performance than the storage battery. The control unit controls the charge and discharge control circuit to change the ratio of the power extracted from the power source to the power extracted from the battery according to a fluctuation rate of the supply target power and states of the power source and the battery.

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