JP6786999B2 - Power supply device, communication device, communication system and control method of power supply device - Google Patents

Description

The present invention relates to a power supply device, a communication device, a communication system, and a control method for the power supply device.

In recent years, the rapid deterioration of social infrastructure developed after the period of high economic growth has become a social problem. For this reason, structures as social infrastructure require automatic and regular inspections and monitoring using sensors. In addition, since structures as social infrastructure have various shapes and structures, it is not always possible to install communication devices in an environment with good radio wave visibility. Therefore, the monitoring system for monitoring the social infrastructure is provided with a communication device having a wireless multi-hop function, and the communication device is configured to perform a wide range of monitoring by wirelessly relaying sensor data.

On the other hand, solar cells are suitable as power generation elements for infrastructure monitoring. However, since the generated power of a solar cell depends on the weather, the solar power generation system will be stopped if it is rained or cloudy for a long time. Therefore, the monitoring system combines a solar battery, a large-capacity capacitor, and a secondary battery, and uses the secondary battery as an auxiliary power source to reduce the capacity of the capacitor, or uses the secondary battery as the charging destination when the capacitor is fully charged. The main purpose was to increase the capacity of the secondary battery and reduce the capacity of the expensive capacitor for the purpose of long life such as switching, and for the purpose of utilizing a large capacity capacitor and suppressing the cost due to its high price.

For example, Patent Document 1 describes "a power supply device for a terminal network control device used in a telemeter system that performs remote meter reading using a communication line, and a large-capacity capacitor that stores electric power obtained by a solar cell. A power supply device for a terminal network control device, which comprises a lithium battery as a spare battery, is disclosed. Further, Patent Document 2 switches whether the output of the capacitor is connected to the terminal network control main body or the output of the secondary battery is connected to the terminal network control main body based on the voltage of the capacitor. A terminal network control device characterized by having a switching unit is disclosed.

Japanese Unexamined Patent Publication No. 2009-148604 Japanese Unexamined Patent Publication No. 2012-39279

Since the techniques of Patent Documents 1 and 2 described above use a large-capacity capacitor, they do not lead to cost reduction. Further, according to the techniques of Patent Documents 1 and 2, if the capacity of the secondary battery as an auxiliary power source is increased, the solar cell (power generation device) cannot be charged when the generated power is small due to the characteristics of the secondary battery. There was a problem. That is, there is a problem that the secondary battery cannot be charged with a small current, and charging starts from the minimum charging current peculiar to the secondary battery.

The present invention has been made to solve such a problem, and is a control method for a power supply device, a communication device, a communication system, and a power supply device that can efficiently charge even when the generated power of the power generation device is low. The purpose is to provide.

In order to achieve the above object, the present invention is a power supply device that switches the charging destination according to the generated power of the power generation device (for example, a solar battery), and maintains the maximum generated power (maximum output) of the power generation device. While controlling the output current value, the power supply unit that outputs the charging voltage of the secondary battery, the output current monitor unit that monitors the output current of the power supply unit, and the current value monitored by the output current monitor unit. Is a control unit that charges the secondary battery when it exceeds the minimum charging current peculiar to the secondary battery, and charges the capacitor when the current value monitored by the output current monitoring unit is equal to or less than the minimum charging current. It is characterized by having.

According to the present invention, it is possible to efficiently charge the power generation device even when the generated power is low.

It is a block diagram (1) of the communication apparatus which is 1st Embodiment of this invention. It is a block diagram (2) of the communication apparatus which is 1st Embodiment of this invention. It is a flowchart explaining operation of a communication device. It is a flowchart explaining the maximum power point tracking control. It is a PV curve for demonstrating the maximum power point tracking control. It is a block diagram of the communication system for demonstrating multi-hop communication.

Hereinafter, embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail with reference to the drawings. In addition, each figure is only shown schematicly to the extent that the present embodiment can be fully understood. Further, in each figure, common components and similar components are designated by the same reference numerals, and duplicate description thereof will be omitted.

(First Embodiment)
1 and 2 are block diagrams of a communication device according to a first embodiment of the present invention.
The communication device 100 includes a power supply device 10, a solar cell 20 as a power generation device, a wireless device 30, and a sensor device 40. For example, the state of a social infrastructure structure is monitored and monitored. It has a function as a monitoring device that transmits information to an external communication device.

The solar cell 20 is, for example, an amorphous solar cell and has a function of generating electricity even with weak light. The sensor device 40 uses the generated power generated by the solar cell 20 to monitor, for example, vibration and distortion of a structure of social infrastructure. The wireless device 30 has a function of communicating with another terminal and transmitting the power supply voltage of the power supply device 10, the abnormality information of the power supply device 10, and the monitor information of the sensor device 40. The wireless device 30 and the sensor device 40 are driven by the DC power output by the power supply device 10.

The power supply device 10 includes a power supply unit 11, a power generation current monitor unit 12, a capacitor 14, a secondary battery 15, a control unit 50 which is a CPU (Central Processing Unit), and three switches SW13, 15, and 17. .. The power supply unit 11 has a maximum power point tracking (HPPT) function that maintains the solar cell at a voltage that generates electricity most efficiently by controlling the output current. The power supply unit 11 internally controls its maximum voltage so as to match the secondary battery 15. The capacitor 14 is, for example, an electric double layer capacitor or a lithium ion capacitor, and temporarily stores the generated power generated by the solar cell 20 and discharges the stored energy to the secondary battery 15.

The secondary battery 15 is, for example, a lithium ion battery, a nickel hydrogen battery, a NiCd battery, or a lead storage battery, and stores the generated power generated by the solar battery 20 or the energy temporarily stored in the capacitor 14. The secondary battery 15 has a characteristic that charging is not performed with a minute current and charging is started with an inherent current (hereinafter, minimum charging current). That is, the secondary battery 15 has a characteristic that charging is performed with a specific minimum charging current or more. The minimum charging current value [A] peculiar to the secondary battery 15 is determined in advance depending on the type, structure, and the like, and is, for example, 0.02 times the value of the capacity [Ah] of the secondary battery 15.

The control unit 50 (FIG. 1) is driven by the energy stored in the capacitor 14 or the secondary battery 15, and the precharged secondary battery 15 is used for the initial drive. The control unit 50 (FIG. 1) controls the current of the power supply unit 11. Further, the control unit 50 monitors the output current of the power supply unit 11 using the power generation current monitor unit 12, monitors the voltage of the capacitor 14 and the secondary battery 15, and switches the switches SW13, SW15, and SW17. .. Further, the control unit 50 acquires the sensor information output by the sensor device 40 and outputs the CPU information to the wireless device 30.

The control unit 50 (FIG. 2) includes a power supply unit control means 55, a monitoring means 60, a communication control unit 65, and a switch control means 70. The power supply unit control means 55 includes a maximum power point tracking means 56 and an output current control means 57. The maximum power point tracking means 56 causes the power supply unit 11 to execute the maximum power point tracking control. When the secondary battery 15 is stored, the output current control means 57 limits the generated current of the solar cell 20 when the charging current exceeds the set current (maximum charging current value).

The monitoring means 60 includes a generated current monitoring means 61 and a voltage monitoring means 62.
The power generation current monitoring means 61 monitors the current monitored by the power generation current monitoring unit 12. That is, the power generation current monitoring means 61 monitors the power generation current output by the power supply unit 11. The voltage monitoring means 62 monitors the voltage of the capacitor 14 and the voltage of the secondary battery 15. The switch control means 70 has three switches SW13 based on the value of the generated current monitored by the generated current monitoring means 61, the value of the voltage of the capacitor 14 monitored by the voltage monitoring means 62, and the value of the voltage of the secondary battery 15. , SW15, SW17 are switched.

The communication control unit 65 includes a secondary battery voltage transmitting means 66, an abnormality information notifying means 67, and a sensor information notifying means 68.
The secondary battery voltage transmitting means 66 causes the wireless device 30 to transmit the voltage of the secondary battery 15 to another terminal. When the values of the output current of the power supply unit 11, the voltage of the secondary battery 15, and the voltage of the capacitor 14 do not change for a long period of time, the abnormality information notification means 67 determines that the abnormality is present, and determines that the wireless device 30 is abnormal. Have the other terminal send the abnormal information. It should be noted that since sunlight becomes dark twice at sunrise and sunset, there is a time to charge the capacitor 14 at least twice a day. That is, when the voltage of the capacitor 14 does not change from 12 hours to 24 hours (when it shows a constant voltage), the abnormality information notification means 67 determines that it is abnormal. The sensor information notification means 68 causes the wireless device 30 to transmit the information monitored by the sensor device 40 to another terminal.

The power supply device 10 further includes a volatile storage unit 16, a non-volatile storage unit 17, and a communication unit 19. The volatile storage unit 16 is a RAM (Random Access Memory) and is used as a working memory. The non-volatile storage unit 17 is a ROM (Read Only Memory) or an HDD (Hard Disk Drive), and stores the program 18. The communication unit 19 communicates with the wireless device 30 and receives monitor information transmitted by the sensor device 40.

FIG. 3 is a flowchart illustrating the operation of the communication device.
This flow is activated by turning on the power or resetting.
The power supply unit control means 55 (FIG. 2) determines whether or not the voltage of the power storage means 13 is equal to or higher than the set voltage (S5). That is, the power supply unit control means 55 determines whether or not the voltage of the secondary battery 15 monitored by the voltage monitoring means 62 or the voltage of the capacitor 14 is equal to or higher than the set voltage. If the voltage of the power storage means 13 is equal to or higher than the set voltage (or higher in S5), the power supply unit control means 55 repeats the determination in S5. On the other hand, if the voltage of the power storage means 13 is less than the set voltage (less than in S5), the maximum power point tracking means 56 causes the power supply unit 11 to perform the maximum power point tracking control (S10).

FIG. 4 is a flowchart for explaining the maximum power point tracking control, and FIG. 5 is a PV curve for explaining the maximum power point tracking control. Although the flow of FIG. 4 is sequentially executed by interrupting the timer, it may be executed inside the power supply unit 11. FIG. 5 shows the PV characteristic when the irradiation light amount of the solar cell 20 is constant, and this characteristic varies depending on the setting location of the solar cell 20, the weather, and the like. The horizontal axis of FIG. 5 is voltage, and the vertical axis is generated power. This PV curve shows that the output current I is varied to change the voltage V, and as a result, the electric power P, which is the product of the voltage V and the current I, changes.

The power supply unit 11 (FIGS. 1 and 2) changes the output current to slightly change the voltage of the solar cell 20 by ΔV (S12). After S12, the maximum power point tracking means 56 calculates the generated power before and after the change (S14). After S14, the maximum power point tracking means 56 determines the increase / decrease in the generated power calculated in S14 (S16). If the increase / decrease in the generated power is the same as the increase / decrease direction of the voltage (the same increase / decrease direction in S16), the maximum power point tracking means 56 returns the process to S12, and further slightly changes the voltage of the solar cell 20 in the same direction.

For example, the power supply unit 11 (FIGS. 1 and 2) slightly increases the output current from voltage V ₀ to voltage V ₁ by controlling the output current to decrease. As a result, the power increases from P ₀ to P ₁ . Since the increase in power is the same as the direction in which the voltage increases, the power supply unit 11 increases the voltage of the solar cell 20 from V ₁ to V ₂ . As a result, the electric power increases from P ₁ to P ₂ . Since the increase in power is the same as the direction in which the voltage increases, the power supply unit 11 increases the voltage of the solar cell 20 from V ₂ to V ₃ . Then, power is reduced from _{P 2} to _{P 3.}

On the other hand, if the increase / decrease in the generated power is reversed with respect to the increase / decrease direction of the voltage (inversion in the increase / decrease in S16), the maximum power point tracking means 56 reverses the direction of the voltage change (S18) and returns the process to S12. For example, since the decrease in power from P ₂ to P ₃ is reversed with respect to the direction of increase in voltage, the maximum power point tracking means 56 reduces the voltage from V ₃ to V ₂ . As a result, the power returns from _{P 3} to _{P 2.} As a result, the power supply unit 11 can operate the solar cell 20 at the optimum operating point (maximum output of the solar cell 20).

Returning to the flowchart of FIG. 3, the power generation current monitoring means 61 determines whether or not the output current of the power supply unit 11 monitored by the power generation current monitoring unit 12 exceeds the minimum charging current inherent in the secondary battery 15 (S20). .. When the output current of the power supply unit 11 is equal to or less than the minimum charging current (below the minimum charging current in S20), the switch control means 70 charges the capacitor 14 (S22). That is, the switch control means 70 sets the switch SW13 on the capacitor 14 side and opens S15. Due to the opening of S15, the secondary battery 15 is not charged. At this time, S17 is in a short-circuited state, and the secondary battery 15 is driving the wireless device 30.

After S22, the voltage monitoring means 62 determines whether or not the voltage of the capacitor 14 is equal to or higher than a predetermined voltage (S24). When the voltage of the capacitor 14 is less than the predetermined voltage (threshold value) (less than the predetermined voltage in S24), the determination of the voltage of the capacitor 14 is repeated and charging is continued. On the other hand, when the voltage of the capacitor 14 becomes equal to or higher than the predetermined voltage (threshold voltage) (greater than or equal to the predetermined voltage in S24), the switch control means 70 discharges the capacitor 14 to the secondary battery 15 (S26). That is, the switch control means 70 short-circuits the switch SW15 and discharges the secondary battery 15 (S26).

After the process of S26, the voltage monitoring means 62 determines whether or not the voltage of the secondary battery 15 is equal to or higher than the predetermined voltage (S28). When the voltage is equal to or lower than the predetermined voltage (less than or equal to the predetermined voltage in S28), the monitoring means 60 returns the process to S30 and charges the secondary battery 15 while monitoring the charging current. On the other hand, when the voltage of the secondary battery 15 exceeds the predetermined voltage (exceeding the predetermined voltage in S28), the switch control means 70 stops charging the secondary battery 15 (S30). That is, the switch control means 70 opens the switch SW15 and stops charging the secondary battery 15 (S30). At this time, since the switch SW17 is in a short-circuited state, the secondary battery 15 is gradually discharged.

Then, after S30, the process is returned to S5, and charging is repeated after the voltage of the secondary battery 15 drops to the set voltage. The control unit 50 is interrupted to stop the iterative processing.

In the determination of S20, when the output current of the power supply unit 11 exceeds the minimum charging current inherent in the secondary battery 15 (exceeding the minimum charging current in S20), the switch control means 70 charges the secondary battery 15 ( S32). That is, the switch control means 70 pushes the switch SW13 toward the secondary battery 15. At this time, the switch control means 70 may short-circuit the switch SW15 so that the capacitor 14 and the secondary battery 15 have the same potential.

The power generation current monitoring means 61 determines whether or not the charging current of the secondary battery 15 exceeds the set current (S34). That is, the power generation current monitoring means 61 determines whether or not the value of the output current of the power supply unit 11 monitored by the power generation current monitoring unit 12 exceeds the set current (maximum charging current value) (S34). If the charging current of the secondary battery 15 exceeds the set current (exceeds the set current in S34), the generated current monitoring means 61 causes the output current control means 57 to limit the current to the power supply unit 11 ( S36), protect the secondary battery 15. After S36, the process is returned to S5, and charging is repeated after the voltage of the secondary battery 15 drops to the set voltage.

The switch SW17 is short-circuited when the voltage of the secondary battery 15 exceeds the set value, and is opened when the voltage of the secondary battery 15 is equal to or less than the set value. That is, the wireless device 30 and the sensor device 40 are activated when the voltage of the secondary battery 15 exceeds the set value.

As described above, since the secondary battery 15 has a characteristic that charging is started at a specific minimum charging current value or more, it cannot be charged when the generated power of the solar cell is low. Therefore, the power storage means 13 of the communication device 100 of the present embodiment combines the capacitor 14 and the secondary battery 15. That is, the capacitor 14 uses a small-capacity capacitor 14 as a storage means when the generated power of the solar cell 20 is low by taking advantage of the characteristic that it can be charged even during low power generation. On the other hand, the secondary battery 15 uses a large-capacity battery as the main battery when the generated power of the solar cell 20 is large.
In other words, the communication device 100 has a route for discharging the energy once charged by the capacitor 14 to the secondary battery 15, and when the capacitor 14 is fully charged, the energy is always discharged to the secondary battery 15 to increase the operating rate. Can be up. As a result, the communication device 100 can lead to an increase in charge / discharge efficiency of the solar cell 20 during low-power power generation.

Further, the communication device 100 can realize efficient charging by combining the capacitor 14 for charging at the time of low power generation and the secondary battery 15 at the time of high power generation. That is, since the communication device 100 can efficiently utilize the power generated by the solar cell 20, the amount of power generated by the solar cell 20 is reduced, and the solar cell 20 can be miniaturized. Further, the miniaturization of the solar cell 20 makes it less likely to be affected by shadows and the like due to the surrounding environment due to the smaller area, and it becomes possible to improve the power generation efficiency.

Further, the communication device 100 suppresses the size and capacity of the costly capacitor 14 and the solar cell 20, and increases the capacity of the low-cost secondary battery 15 to improve power generation and charging efficiency while suppressing the cost. In the communication device 100, the size of the entire device is also reduced, the cost of parts is suppressed, and the installation work is simplified, so that the cost of the entire device can be suppressed. Further, since the communication device 100 uses a capacitor 14 having no limitation on the number of times of charging and a secondary battery 15 capable of charging a small current and having a wide usable temperature range, maintenance-free for a long period of time can be expected.

(Usage pattern)
FIG. 6 is a configuration diagram of a communication system for explaining multi-hop communication.
The communication system 200 includes a plurality of communication devices 100 (100a, 100b, 100c, 100d, 100e, 100f), and each communication device 100 is distributed and attached to, for example, a structure of social infrastructure (for example, an iron bridge). ing. The communication system 200 performs short-distance communication from the communication device 100a to the communication device 100d and the communication device 100f. However, in the communication system 200, since there is an obstacle between the communication device 100a and the communication device 100d and the distance between the communication device 100a and the communication device 100f is long, direct communication is difficult. Further, any of the communication devices 100 is installed in a place where the solar cell 20 (FIG. 1) is in the shadow, and the charging voltage of the secondary battery 15 (FIG. 1) drops due to insufficient sunlight irradiation amount. Therefore, communication may become difficult.

Therefore, the communication device 100 has a wireless device 30 (FIG. 1) including a multi-hop communication means 35, and the wireless device 30 is configured to perform short-range communication with another communication device 100. That is, the communication system 200 can avoid obstacles and perform communication from the communication device 100a to the communication device 100f via the communication device 100c and the communication device 100d. Further, the communication system 200 can communicate from the communication device 100a to the communication device 100f via the communication device 100e. That is, the communication system 200 can communicate from the communication device 100a to the communication device 100f by a plurality of routes, but the optimum route such as communication quality is automatically selected and the communication is performed.

The communication device 100 can transmit the power generation value of the solar cell 20, the voltage value between the secondary battery 15 and the capacitor 14, and the sensor device information to the communication device 100f as a management device (monitoring terminal). The communication system 200 can be expected to be utilized for network route selection, terminal state information (for example, abnormality information), and sensor information transmission by using the information received by the communication device 100f as a management device.

(Modification example)
The present invention is not limited to the above-described embodiment, and various modifications such as the following are possible.
(1) Although the communication device 100 of the above embodiment uses the solar cell 20 (FIG. 1) as the power generation device, wind power generation or geothermal power generation may be used. Further, the power generation device may be a power generation member such as a thermoelectric conversion element, a piezoelectric element (for example, a piezo element), or a power generation element (for example, a rectenna) that rectifies and converts the received radio wave into a direct current.

(2) The control unit 50 (FIGS. 1 and 2) of the embodiment is programming the determination (S20 of FIG. 3) of whether or not the output current of the power supply unit 11 is equal to or less than the minimum charging current peculiar to the secondary battery 15. It was executed in, but it may be executed sequentially by interrupting the timer.

(3) The communication device 100 of the above embodiment includes a sensor device 40 (FIG. 1) and functions as a monitoring device. However, for example, if the communication device 100 functions as a relay device, the sensor device 40 becomes unnecessary.

10 Power supply device 11 Power supply unit 12 Power generation current monitor unit 13 Power storage means 14 Capacitor 15 Secondary battery 16 Volatile storage unit 17 Non-volatile storage unit 18 Program 19 Communication unit 20 Solar cell (power generation equipment)
30 Wireless device 35 Multi-hop communication means 40 Sensor device 50 Control unit (CPU)
55 Power supply unit control means 56 Maximum power point tracking means 57 Output current control means 60 Monitoring means 61 Power generation current monitoring means 62 Voltage monitoring means 65 Communication control unit 66 Secondary battery voltage transmission means 67 Abnormality information notification means 68 Sensor information notification means 70 Switch control means 100, 100a, 100b, 100c, 100d, 100e, 100f Communication device 200 Communication system SW13, SW15, SW17 Switch

Claims (10)

It is a power supply device that switches the charging destination according to the generated power of the power generation device.
A power supply unit that outputs the charging voltage of the secondary battery by controlling the output current value while maintaining the maximum generated power of the power generation device.
An output current monitor unit that monitors the output current of the power supply unit and
When the current value monitored by the output current monitor unit exceeds the minimum charging current specific to the secondary battery, the secondary battery is charged and the current value monitored by the output current monitoring unit is the minimum charging current. In the following cases, the control unit that charges the capacitor and
A power supply device characterized by being provided with. The power supply device according to claim 1.
The control unit is a power supply device characterized in that, when the capacitor is charged, when the voltage of the capacitor becomes a predetermined voltage or more, the charging power of the capacitor is discharged to the secondary battery. The power supply device according to claim 2.
The control unit is a power supply device characterized in that when the secondary battery is being charged, charging of the secondary battery is stopped when the charging voltage of the secondary battery exceeds a set voltage. The power supply device according to claim 1.
When the secondary battery is being charged, the control unit limits the output current of the power supply unit when the charging current of the secondary battery exceeds the maximum charging current set value of the secondary battery. Characterized power supply. The power supply device according to any one of claims 1 to 4.
The power generation device is a power supply device characterized by being a solar cell. A communication device having the power supply device according to any one of claims 1 to 5 and a wireless device driven by DC power output by the power supply device. The communication device according to claim 6.
The wireless device is a communication device characterized by transmitting the voltage value of the secondary battery to an external terminal. The communication device according to claim 6.
The control unit monitors the current value monitored by the output current monitor unit , the voltage value of the secondary battery, and the voltage value of the capacitor.
The wireless device is a communication device characterized in that an abnormality is notified to an external terminal when the value monitored by the control unit does not change for a long period of time. A communication system including a plurality of communication devices including the power supply device according to any one of claims 1 to 5 and a wireless device driven by DC power output by the power supply device.
When the voltage of the secondary battery and the charging voltage of the capacitor are lowered and communication is difficult, the plurality of communication devices perform multi-hop communication via another communication device.
A communication system characterized by that. By controlling the output current value, the maximum generated power of the power generation equipment is maintained, and by controlling the output current value, the power supply unit that outputs the charging voltage of the secondary battery and the output current of the power supply unit are monitored. It is a control method of a power supply device which is provided with an output current monitor unit and switches a charging destination according to the generated power of the power generation device.
When the current value monitored by the output current monitor unit exceeds the intrinsic minimum charging current of the secondary battery, the secondary battery is charged and the current value monitored by the output current monitor unit is the intrinsic minimum of the secondary battery. A method for controlling a power supply device, which comprises charging a capacitor when the current is less than or equal to the charging current.

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