JP2021145465A - Autonomous power supply system and control method thereof - Google Patents

Abstract

To propose an autonomous power supply system that can reduce energy loss and generate electricity with high efficiency, and a control method thereof.SOLUTION: In an autonomous power supply system that supplies power generated by a power generation element to a load, and a control method thereof, the autonomous power supply system includes a primary power storage element that stores the power generated by the power generation element, a secondary power storage element that supplies the power to the load, and a power supply control unit that controls charging from the primary power storage element to the secondary power storage element, and the power control unit monitors a terminal voltage of the primary power storage element and a terminal voltage of the secondary power storage element, and controls the charging from the primary power storage element to the secondary power storage element such that charging is performed from the primary power storage element to the secondary power storage element in stages.SELECTED DRAWING: Figure 1

Description

The present invention relates to a self-sustaining power supply system and a control method thereof, and is suitable for application to, for example, a wireless sensor system.

Energy harvesting technology, which converts minute environmental energy into electrical energy using power generation elements such as solar cells and thermoelectric power generation elements, is used in environments where power supply is difficult or where wiring work is required to supply power. It is used as an effective self-sustaining power supply technology when installing electronic devices that operate with low power underneath.

In a self-sustaining power generation system using such energy harvesting technology, the power output from the power generation element is very small, and the amount of power generated by the power generation element fluctuates greatly depending on the environmental conditions. It is common to store power in a power storage element such as a capacitor to some extent before using it.

In this case, it is necessary to increase the capacity of the power storage element in order to operate the electronic device stably. However, when the capacity of the power storage element is increased, the terminal voltage of the power storage element becomes a usable voltage and is transferred to the load side. There is a problem that it takes a considerable amount of time before the power supply can be started.

As one method for solving this problem, Patent Document 1 describes a power generation control circuit that controls the power generation efficiency of a power generation element, a power storage element group that charges the power generated by the power generation element, and a charge of the power generation element group. A charge control circuit that controls the discharge operation is provided, and the power generation element group is composed of at least a primary power storage element that supplies power to the power generation control circuit and the charge control circuit, and a secondary power storage element that supplies power to the load device. Then, the capacity of the primary power storage element is made smaller than the capacity value of the secondary power storage element, and the power generated by the power generation element is preferentially charged over the primary power storage element, and then the primary power storage element is changed to the secondary power storage element. A self-sustaining power system for charging is disclosed.

According to this self-sustaining power supply system, even if the power generation element generates power from minute and unstable environmental energy, the period until the power generation control circuit is started or stopped can be minimized. As a result, it is possible to obtain the effect that power supply to the load device can be started in a short time.

JP-A-2015-15848

により表される。 By the way, in the self-sustaining power generation system disclosed in Patent Document 1, the amount of energy loss when transferring an electric charge from the primary storage element to the secondary storage element is such that the terminal voltage of the primary storage element is changed to V1 or the secondary storage element. The terminal voltage of is V2, and the capacity of the secondary power storage element is C2.

Represented by.

As is clear from the equation (1), in the self-sustaining power generation system disclosed in Patent Document 1, the larger the capacity of the secondary power storage element C2, the more the voltage between the primary power storage element and the secondary power storage element. There is a problem that the larger the difference (V1-V2) is, the larger the amount of energy loss when the charge is transferred from the primary power storage element to the secondary power storage element to charge the secondary power storage element.

The present invention has been made in consideration of the above points, and an object of the present invention is to propose an independent power supply system capable of generating electricity with high efficiency by reducing the amount of energy loss and a control method thereof.

In order to solve such a problem, in the present invention, in the self-sustaining power supply system that supplies the electric power generated by the power generation element to the load, the primary power storage element that stores the electric power generated by the power generation element and the electric power are supplied to the load. A power supply control unit that controls charging from the primary power storage element to the secondary power storage element so that the secondary power storage element and the secondary power storage element are charged in stages. And so on.

Further, in the present invention, in the control method of the self-sustaining power supply system that supplies the power generated by the power generation element to the load, the self-sustaining power supply system includes the primary power storage element that stores the power generated by the power generation element and the load. It has a secondary power storage element that supplies power to the secondary power storage element and a power supply control unit that controls charging from the primary power storage element to the secondary power storage element, and the power supply control unit controls the terminal voltage of the primary power storage element. And the first step of monitoring the terminal voltage of the secondary power storage element, and the primary so that the power supply control unit gradually charges the secondary power storage element from the primary power storage element. A second step of controlling charging from the power storage element to the secondary power storage element is provided.

According to the self-sustaining power supply system of the present invention and its control method, the potential difference between the terminal voltage of the primary power storage element and the terminal voltage of the secondary power storage element can be suppressed within a certain range (within the difference in the voltage values of each stage).

According to the present invention, it is possible to realize an independent power supply system capable of generating electricity with high efficiency by reducing the amount of energy loss and a control method thereof.

Issues, configurations and effects other than those described above will be clarified by the following description of the embodiments for carrying out the invention.

It is a block diagram which shows the structure of the wireless sensor terminal by this embodiment. It is a waveform diagram which provides the explanation of the on / off control of a switch by a voltage monitoring unit. It is a figure which shows the structure of the threshold voltage management table. It is a waveform figure which shows the state of the change of the terminal voltage of the primary power storage element in this embodiment. It is a waveform diagram which shows the state of the change of the terminal voltage of the secondary power storage element in this embodiment. It is a flowchart which shows the processing procedure of the threshold voltage setting process. It is a graph which shows the experimental result. It is a graph which shows the experimental result.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The embodiments described below are examples for explaining the present invention, and are appropriately omitted or simplified for the purpose of clarifying the description. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range and the like disclosed in the drawings.

Examples of various information may be described by expressions such as "table", "list", and "queue", but various information may be expressed by data structures other than these. For example, various information such as "XX table", "XX list", and "XX queue" may be "XX information". When describing the identification information, expressions such as "identification information", "identifier", "name", "ID", and "number" are used, but these can be replaced with each other.

When there are a plurality of components having the same or similar functions, they may be described by adding different subscripts to the same reference numerals. Further, when it is not necessary to distinguish between these a plurality of components, the subscripts may be omitted for explanation.

In the embodiment, a process performed by executing the program may be described. Here, the computer is defined by the program by executing the program by the processor (for example, CPU (Central Processing Unit), GPU (Graphics)) and using the storage resource (for example, memory) and the interface device (for example, communication port). Perform the processing.

Therefore, the main body of the processing performed by executing the program may be a processor. Similarly, the subject of processing for executing a program may be a controller, a device, a system, a computer, or a node having a processor. The main body of the processing performed by executing the program may be an arithmetic unit, and may include a dedicated circuit for performing a specific processing. Here, the dedicated circuit is, for example, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), a CPLD (Complex Programmable Logic Device), or the like.

The program may be installed on the computer from the program source. The program source may be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server includes a processor and a storage resource for storing the program to be distributed, and the processor of the program distribution server may distribute the program to be distributed to other computers. Further, in the embodiment, two or more programs may be realized as one program, or one program may be realized as two or more programs.

(1) Configuration of Wireless Sensor Terminal According to the Present Embodiment FIG. 1 shows the configuration of the wireless sensor terminal 1 according to the present embodiment. The wireless sensor terminal 1 includes an independent power supply system 2, and supplies the generated power and the power supplied from the primary battery 3 via the diode 4 to the sensor 6 and the communication device 7 constituting the load 5.

In the case of the present embodiment, the sensor 6 is assumed to be an ammeter that measures the motor current of the transport device or the cutting machine, but may be another sensor that measures various physical quantities other than the current. The communication device 7 is composed of a wireless communication device. The communication device 7 wirelessly transmits the physical quantity measured by the sensor 6 to a receiving device (not shown) via the antenna 8 periodically or irregularly.

The self-sustaining power supply system 2 includes a power generation element 10, a rectifier circuit 11, a primary power storage element C1, a secondary power storage element C2, and a power supply control unit 12.

The power generation element 10 is composed of, for example, a current transformer. In the case of the present embodiment, the power generation element 10 is installed so that the primary coil surrounds the cable 13 through which the target motor current flows. Then, the power generation element 10 transfers the generated power based on the electromagnetic induction current generated in the primary side coil from the secondary side coil to the rectifying circuit 11 in response to the fluctuation of the magnetic flux around the cable 13 generated by the motor current flowing through the cable 13. Output.

The rectifier circuit 11 is composed of four bridge-connected diodes D1 to D4. The rectifier circuit 11 rectifies the generated power output from the power generation element 10 and applies the rectified generated power to the primary power storage element C1. Further, the primary power storage element C1 is composed of a capacitor having a capacity of about several tens [μF], and stores the generated power applied by the rectifier circuit 11.

The electric power stored in the primary power storage element C1 is supplied to the secondary power storage element C2 via a switch 20 described later in the power supply control unit 12. The secondary power storage element C2 is composed of a capacitor having a capacity of several tens [mF], which is larger than that of the primary power storage element C1, and stores the electric power supplied from the primary power storage element C1.

As the capacitor constituting the primary power storage element C1 and the secondary power storage element C2, it is preferable to use a multilayer ceramic capacitor having a small leakage current and a small internal resistance. However, an electric field capacitor other than the monolithic ceramic capacitor, a tantalum electric field capacitor, an electric double layer capacitor, or the like can also be used. Further, the primary power storage element C1 and the secondary power storage element C2 may each be configured by one capacitor, or may be configured by connecting a plurality of them in parallel.

The power supply control unit 12 is a functional unit that controls charging from the primary power storage element C1 to the secondary power storage element C2, and is a switch 20, a voltage monitoring unit 21, and a control unit (hereinafter referred to as an MCU (Micro Controller Unit)). 22 is provided.

The switch 20 is composed of a general switching element such as a field effect transistor having a small resistance when it is turned on and a large resistance when it is turned off. The switch 20 is on / off controlled by the voltage monitoring unit 21.

The voltage monitoring unit 21 monitors the terminal voltage V1 of the primary power storage element C1 and controls the switch 20 on / off according to the voltage value of the terminal voltage V1. Specifically, as shown in FIG. 2, the voltage monitoring unit 21 turns off the switch 20 when the terminal voltage V1 of the primary power storage element C1 is less than the first threshold voltage Va previously specified by the MCU 22. By doing so, the primary power storage element C1 is charged by the generated power applied from the rectifier circuit 11.

After that, when the terminal voltage V1 of the primary storage element C1 reaches the first threshold voltage Va, the voltage monitoring unit 21 turns on the switch 20 to transfer the electric charge accumulated in the primary storage element C1 to the switch 20. The secondary power storage element C2 is charged by supplying it to the secondary power storage element C2 via the device.

Further, when the terminal voltage V1 of the primary storage element C1 drops to the second threshold voltage Vb, which is lower than the first threshold voltage Va by a predetermined voltage, the voltage monitoring unit 21 returns the switch 20 to the off state again. After that, the same control operation as described above for turning on / off the switch 20 according to the magnitude of the terminal voltage V1 of the primary power storage element C1 is repeated. As a result, charging / discharging of the primary power storage element C1 is repeated as the switch 20 is turned on / off, and the secondary power storage element C2 is charged until the first threshold voltage Va is reached.

At this time, the voltage monitoring unit 21 detects the terminal voltage V2 of the secondary power storage element C2 and constantly notifies the MCU 22 of the detected terminal voltage V2 of the secondary power storage element C2.

The MCU 22 is composed of a microprocessor including a CPU and a memory. The MCU 22 starts operating with the electric power stored in the primary storage element C1 at the initial stage, and operates by the electric power stored in the secondary storage element C2 after a certain amount of electric power is stored in the secondary storage element C2. do.

The MCU 22 holds a threshold voltage management table 23 as shown in FIG. 3 in a memory. The threshold voltage management table 23 has a voltage value Vt (Vt1, Vt2, Vt3) to be set as the first threshold voltage Va in each stage in order to gradually increase the first threshold voltage Va set in the voltage monitoring unit 21. , ...) Are registered tables, and as shown in FIG. 3, the stage column 23A and the voltage value column 23B are provided.

A numerical value representing each stage is stored in the stage column 23A, and a voltage value Vt to be set as the first threshold voltage Va in the voltage monitoring unit 21 in the corresponding stage is stored in the voltage value column 23B. .. In this case, the magnitude of the voltage value Vt in each stage is determined so that the voltage value Vt in the first stage (Vt1 in FIG. 3) is the smallest and gradually increases as the stage increases.

Further, in the threshold voltage management table 23, voltage values Vt for at least three stages are registered in advance. In this case, as the voltage value Vt (Vt1) of the first stage, the minimum voltage value at which the MCU 22 can start the operation (hereinafter, this is referred to as an operable voltage value) is registered. Further, as the voltage values Vt (Vt2, Vt3, ... In FIG. 3) of the second and subsequent stages, the voltage values selected so that the voltage difference from the voltage value Vt of the next stage does not exceed a certain level are registered. Will be done. Further, as the voltage value Vt at the final stage, a voltage value Vt having a size necessary and sufficient for supplying power to the load 5 is selected and registered.

Then, the MCU 22 starts operating when the terminal voltage V1 of the primary power storage element C1 becomes the operable voltage of the MCU 22, and first, the voltage value of the first stage among the voltage values Vt registered in the threshold voltage management table 23. The value of Vt is acquired and set in the voltage monitoring unit 21 as the first threshold voltage Va.

As a result, the primary power storage element C1 is charged by the voltage applied from the rectifier circuit 11 to the primary power storage element C1, and the terminal voltage V1 of the primary power storage element C1 is eventually set as the first threshold voltage Va by the MCU 22. When the voltage value Vt is reached, the voltage monitoring unit 21 starts the on / off control of the switch 20 as described above, so that the charging of the secondary power storage element C2 is started.

Further, the MCU 22 monitors the terminal voltage V2 of the secondary storage element C2 notified from the voltage monitoring unit 21, and the terminal voltage V2 is the voltage value set in the voltage monitoring unit 21 as the first threshold voltage Va at that time. When Vt is reached, the voltage value Vt of the next stage is acquired from the threshold voltage management table 23, and the acquired voltage value Vt is set in the voltage monitoring unit 21 as a new first threshold voltage Va.

As a result, the voltage monitoring unit 21 keeps the switch 20 in the off state until the terminal voltage V1 of the primary power storage element C1 becomes the voltage value Vt set as the new first threshold voltage Va by the MCU 22 at this time. At the same time, when the terminal voltage V1 of the primary power storage element C1 reaches the individual voltage values Vt, the voltage monitoring unit 21 starts the on / off control of the switch 20 as described above to charge the secondary power storage element C2. Is restarted.

After that, the terminal voltage V1 of the primary power storage element C1 is registered in the threshold voltage management table 23 as the second-stage voltage value Vt (Vt2), the third-stage voltage value Vt (Vt3), and so on. Each time, the same process as described above is repeated between the MCU 22 and the voltage monitoring unit 21.

As a result, the terminal voltage V1 of the first power storage element C1 rises stepwise as shown in FIG. 4, and the terminal voltage V2 of the secondary power storage element C2 gradually increases to the final voltage value as shown in FIG. It gradually rises toward (the last voltage value Vt registered in the threshold voltage management table 23). Then, when the terminal voltage V2 of the secondary power storage element C2 reaches the final voltage value Vt, the voltage monitoring unit 21 controls the switch 20 to maintain the ON state, whereby the terminal of the secondary power storage element C2 is maintained. The voltage V2 is maintained at a voltage value around the final voltage value Vt.

In addition, after the process of raising the first threshold voltage Va toward the final voltage value Vt and after the first threshold voltage Va reaches the final voltage value Vt, it is stored in the secondary storage element C2. The power is consumed by the load 5, and the terminal voltage V2 of the secondary storage element C2 is set as the first threshold voltage Va, which is the voltage value at the stage immediately before the voltage value Vt set in the voltage monitoring unit 21 at that time. There is a possibility that the voltage will be lower than Vt.

In such a case, the MCU 22 changes the voltage value Vt set as the first threshold voltage Va in the voltage monitoring unit 21 to the voltage value Vt of the previous step. In this way, the MCU 22 is set so that the voltage difference between the terminal voltage V1 of the primary storage element C1 and the terminal voltage V2 of the secondary storage element C2 does not exceed a constant voltage (difference in voltage value Vt at each stage). By controlling the value of the threshold voltage Va of 1, it is possible to prevent an increase in energy loss when the electric charge is transferred from the primary storage element C1 to the secondary storage element C2.

(2) Threshold Voltage Setting Process FIG. 6 shows a specific processing procedure of the threshold voltage setting process executed by the MCU 22 regarding the setting of the first threshold voltage Va as described above. The MCU 22 appropriately updates the voltage value Vt set as the first threshold voltage Va for the voltage monitoring unit 21 according to the processing procedure shown in FIG.

In practice, when the terminal voltage V1 of the first power storage element C1 reaches the operating voltage and starts operating, the MCU 22 starts this threshold voltage setting process, and first registers it in the threshold voltage management table 23 (FIG. 3). The value of the voltage value Vt of the first stage is acquired, and this is set in the voltage monitoring unit 21 as the first threshold voltage Va (S1).

Subsequently, in the MCU 22, the terminal voltage V2 of the secondary power storage element C2 notified from the voltage monitoring unit 21 is equal to or higher than the operable voltage of the MCU 22 (the first-stage voltage value Vt set in the voltage monitoring unit 21 in step S1). Wait for it to become (S2).

Then, when the terminal voltage V2 of the secondary power storage element C2 eventually becomes equal to or higher than the operable voltage of the MCU 22, the MCU 22 reads the voltage value Vt of the next stage (here, the voltage value Vt2 of the second stage) from the threshold voltage management table 23. , This is set in the voltage monitoring unit 21 as a new first threshold voltage Va (S3).

Next, the MCU 22 determines whether or not the terminal voltage V2 has reached the voltage value Vt currently set in the voltage monitoring unit 21 based on the terminal voltage V2 of the secondary storage element C2 notified from the voltage monitoring unit 21. Is determined (S4). Further, when the MCU 22 obtains a negative result in this determination, whether or not the terminal voltage V2 of the secondary power storage element C2 has dropped to less than the voltage value Vt immediately before the voltage value Vt currently set in the voltage monitoring unit 21. Is determined (S6).

When the MCU22 obtains a negative result in the judgment of step S6, the MCU 22 returns to step S4, and then repeats the loop of step S4-step S6-step S4 until a positive result is obtained in step S4 or step S6.

Then, when the terminal voltage of the secondary power storage element C2 eventually reaches the voltage value Vt currently set in the voltage monitoring unit 21, the MCU 22 obtains an affirmative result in step S4, and the voltage monitoring unit 21 first receives a positive result. The voltage value Vt one step higher than the voltage value Vt currently set as the threshold voltage Va of is read from the threshold voltage management table 23, and this is set in the voltage monitoring unit 21 as a new first threshold voltage Va ( S5). Then, the MCU 22 returns to step S4, and after that, the processes after step S4 are repeated in the same manner as described above.

However, even when an affirmative result is obtained in step S4, the MCU 22 has a voltage value Vt at the final stage in which the voltage value Vt currently set in the voltage monitoring unit 21 is registered in the threshold voltage management table 23 ( In the case of the largest voltage value Vt) registered in the threshold voltage management table 23, the process of step S5 is omitted and the process returns to step S4, after which the processes of step S4 and subsequent steps are repeated in the same manner as described above.

Further, the MCU 22 is affirmed in step S6 because the terminal voltage V2 of the secondary power storage element C2 becomes a value less than the voltage value Vt one step below the voltage value Vt currently set in the voltage monitoring unit 21. When the result is obtained, the voltage value Vt one step lower than the voltage value Vt currently set as the first threshold voltage Va in the voltage monitoring unit 21 is read from the threshold voltage management table 23, and this is read out from the threshold voltage management table 23. The threshold voltage Va is set in the voltage monitoring unit 21 (S7). Then, the MCU 22 returns to step S4, and after that, the processes after step S4 are repeated in the same manner as described above.

However, in the MCU 22, even when a positive result is obtained in step S6, the voltage value Vt currently set in the voltage monitoring unit 21 is the voltage value Vt of the first stage registered in the threshold voltage management table 23. If it is (the smallest voltage value Vt registered in the threshold voltage management table 23), the process of step S7 is omitted and the process returns to step S4, and then the processes of step S4 and subsequent steps are repeated.

(3) Effect of the present embodiment As described above, in the wireless sensor terminal 1 according to the present embodiment, the voltage monitoring unit 21 and the MCU 22 switch 20 so as to gradually increase the terminal voltage V2 of the secondary power storage element C2. Since the on / off control is executed, the potential difference between the terminal voltage V1 of the primary power storage element C1 and the terminal voltage V2 of the secondary power storage element C2 can be suppressed within a certain range (within the difference between the voltage values Vt of each stage). Therefore, according to the wireless sensor terminal 1, the amount of energy loss during charge transfer from the primary power storage element C1 to the secondary power storage element C2 can be reduced, and power can be generated with high efficiency.

In fact, according to an experiment, the result shown in FIG. 7 was obtained as a change in the terminal voltage of the secondary power storage element C2 by the on / off control of the switch 20 according to the present embodiment. As is clear from FIG. 7, a conventional method in which the terminal voltage V2 of the secondary power storage element C2 is charged so as to be gradually increased (curve K1) as in the present embodiment, so that the terminal voltage V2 is not increased stepwise. It was confirmed that the secondary power storage element C2 can be charged more efficiently than in the case of charging the secondary power storage element (curve K2).

Further, as shown in FIG. 8, the charging method of the secondary power storage element C2 (curve K3) according to the present embodiment and the charging method of the conventional secondary power storage element C2 (curve K4) are combined with each other of the secondary power storage element C2. Even when the square of the terminal voltage V2 is taken and compared in terms of energy, it was confirmed that the former can charge the secondary power storage element C2 with higher efficiency (the self-sustaining power supply system 2 can generate electricity with higher efficiency).

(4) Other Embodiments In the above-described embodiment, the case where the self-sustaining power supply system 2 according to the present invention is applied to the wireless sensor terminal 1 has been described, but the present invention is not limited to this. The invention can be widely applied to various devices other than the wireless sensor terminal 1.

Further, in the above-described embodiment, the case where the voltage monitoring unit 21 and the MCU 22 are separately provided has been described, but the present invention is not limited to this, and the voltage monitoring unit 21 and the MCU 22 are configured as one functional unit. You may try to do it.

Further, in the above-described embodiment, the case where the current transformer is applied as the power generation element 10 has been described, but the present invention is not limited to this, and environmental energy such as light, vibration, heat, and radio waves is collected. As long as it is an element that converts into electric energy, various power generation elements such as a solar cell, a thermal power generation element, and a piezoelectric element can be widely applied.

Further, in the above-described embodiment, the case where the primary battery 3 is used in addition to the self-supporting power supply system 2 has been described, but the present invention is not limited to this, and the present invention is applied even when the primary battery 3 is not used. can do.

In the present invention, the electric power generated by the power generation element is stored in the primary power storage element, and the electric charge stored in the primary power storage element is transferred to the secondary power storage element to charge the secondary power storage element. It can be widely applied to self-sustaining power supply systems having various configurations for supplying the electric power stored in the load to the load.

1 ... Wireless sensor terminal, 2 ... Independent power supply system, 5 ... Load, 10 ... Power generation element, 11 ... Rectifier circuit, 12 ... Power control unit, 20 ... Switch, 21 ... Voltage monitoring unit, 22 ... MCU, 23 ... Threshold voltage management table, C1 ... Primary power storage element, C2 ... Secondary power storage element, V1, V2 ... Terminal voltage, Vt ... Voltage value.

Claims (8)

In an independent power supply system that supplies the power generated by the power generation element to the load
A primary power storage element that stores the electric power generated by the power generation element, and
A secondary power storage element that supplies power to the load,
It is characterized by including a power supply control unit that controls charging from the primary power storage element to the secondary power storage element so that the primary power storage element charges the secondary power storage element in stages. Independent power supply system. The power supply control unit
By monitoring the terminal voltage of the primary power storage element and supplying the power stored in the primary power storage element to the secondary power storage element when the terminal voltage exceeds a preset threshold voltage. While charging the secondary storage element, the terminal voltage of the secondary storage element is monitored, and when the terminal voltage exceeds the threshold voltage, the set threshold voltage is changed from the current threshold voltage. The self-sustaining power supply system according to claim 1, wherein the voltage value is changed to the threshold voltage of the next stage having a large voltage value. The power supply control unit
The self-sustaining aspect according to claim 2, wherein when the terminal voltage of the secondary power storage element becomes less than the threshold voltage one step before, the terminal voltage is changed to the threshold voltage one step before. Power system. The power supply control unit
A switch that connects the primary power storage element and the secondary power storage element,
A voltage monitoring unit that monitors the terminal voltage of the primary power storage element, controls the switch on / off based on the terminal voltage, and detects the terminal voltage of the secondary power storage element.
The voltage monitoring unit is provided with a control unit that sets a threshold voltage based on the terminal voltage of the secondary power storage element detected by the monitoring unit.
The voltage monitoring unit
When the terminal voltage of the primary power storage element reaches the threshold voltage set by the control unit, the switch is controlled to be turned on / off so that the primary power storage element charges the secondary power storage element.
The control unit
When the terminal voltage of the secondary power storage element detected by the voltage monitoring unit reaches the threshold voltage set in the voltage monitoring unit, the threshold voltage set in the voltage monitoring unit is set to the current threshold voltage. The self-sustaining power supply system according to claim 1, wherein the voltage value is updated to the threshold voltage of the next stage having a voltage value larger than the voltage. In the control method of the self-sustaining power supply system that supplies the power generated by the power generation element to the load,
The self-sustaining power supply system
A primary power storage element that stores the electric power generated by the power generation element, and
A secondary power storage element that supplies power to the load,
It has a power supply control unit that controls charging from the primary power storage element to the secondary power storage element.
The first step in which the power supply control unit monitors the terminal voltage of the primary power storage element and the terminal voltage of the secondary power storage element, and
A second step in which the power supply control unit controls charging from the primary power storage element to the secondary power storage element so that the primary power storage element charges the secondary power storage element in stages. A method of controlling a self-sustaining power supply system, which comprises. In the second step, the power supply control unit
When the terminal voltage of the primary power storage element exceeds a preset threshold voltage, the power stored in the primary power storage element is supplied to the secondary power storage element to supply the secondary power storage element. While charging, the threshold voltage set when the terminal voltage of the secondary power storage element exceeds the threshold voltage is changed to the threshold voltage of the next stage in which the voltage value is larger than the current threshold voltage. The control method for an independent power supply system according to claim 5, wherein the method is changed. In the second step, the power supply control unit
The self-sustaining aspect according to claim 6, wherein when the terminal voltage of the secondary power storage element becomes less than the threshold voltage one step before, the terminal voltage is changed to the threshold voltage one step before. How to control the power system. The power supply control unit
A switch that connects the primary power storage element and the secondary power storage element,
A voltage monitoring unit that monitors the terminal voltage of the primary power storage element, controls the switch on / off based on the terminal voltage, and detects the terminal voltage of the secondary power storage element.
The voltage monitoring unit has a control unit that sets a threshold voltage based on the terminal voltage of the secondary power storage element detected by the monitoring unit.
In the first and second steps,
The voltage monitoring unit
When the terminal voltage of the primary power storage element reaches the threshold voltage set by the control unit, the switch is controlled to be turned on / off so that the primary power storage element charges the secondary power storage element.
The control unit
When the terminal voltage of the secondary power storage element detected by the voltage monitoring unit reaches the threshold voltage set in the voltage monitoring unit, the threshold voltage set in the voltage monitoring unit is set to the current threshold voltage. The control method for an independent power supply system according to claim 5, wherein the threshold voltage is updated to the threshold voltage in the next stage in which the voltage value is larger than the voltage.

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