JP2016119733A - Power storage system and power storage method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage system capable of recovering operation of a load device in a short time when a power generation element performs power generation, and a power storage method.SOLUTION: A power storage system comprises: a power generation element for environmental power generation; a first storage battery to which power is supplied from the power generation element and which supplies power to a load device; a second storage battery of which capacity is smaller than that of the first storage battery and which is connected to the first storage battery in series; a first switch part that is connected to the second storage battery in parallel; and a changeover part which controls opening/closing of the first switch part. When the first switch part is in a closed state and power is to be supplied from the first storage battery to the load device via the first switch part, the changeover part controls the first switch part into an open state of a voltage of the first storage battery is lower than or equal to a voltage of a first threshold, and controls the first switch part into the closed state when the first switch part is in the open state and a charge voltage or the like of a series circuit of the first storage battery and the second storage battery to which power is supplied from the power generation element is equal to or higher than a voltage of a second threshold.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power storage system and a power storage method for storing power generated by a power generation element that performs environmental power generation in a storage battery and supplying power to a load device.

  In recent years, energy harvesting devices (energy harvesting elements) such as wireless sensors and remote control switches that operate without wiring or battery replacement by obtaining electrical energy from the surrounding environment due to low power consumption of electronic circuits and wireless technologies. Attention has been paid. For this reason, for example, development of a low illuminance dye-sensitized solar cell for energy harvesting that is supposed to be used in indoor light such as a fluorescent lamp or LED lighting is being promoted.

  There is a power supply device using a related lithium ion capacitor (see Patent Document 1). The power supply installation device described in Patent Document 1 is a power supply device including a lithium ion capacitor, and includes a power control unit that operates the lithium ion capacitor in a voltage range of 2.0V to 3.2V.

  Commercially available lithium ion capacitors are mainly 40F (Farad), 100F or more. Moreover, as described in Patent Document 1, the lithium ion capacitor is preferably used at a voltage of 2.0 V or more from the viewpoint of preventing cell deterioration. For this reason, in a power supply device, the voltage of a lithium ion capacitor may not be a voltage of 2.5 V or less, for example, with a margin. For this reason, when the charging voltage of the lithium ion capacitor drops below 2.5 V, the operation of the load device is temporarily stopped to stop the supply of power. Thereafter, in the power supply device, when the power generation element starts power generation, recharging of the lithium ion capacitor is started by the power generation element.

JP 2013-78235 A

  When recharging the lithium ion capacitor, if the operation of the load device is resumed immediately when the charging voltage of the lithium ion capacitor exceeds 2.5 V, the load device starts and stops operation due to the power consumption of the load device. The problem that is repeated. In other words, the system is driven by repeating the operation of the load device, the reduction of the charging voltage of the lithium ion capacitor due to the power consumption when the operation of the load device is restored, and the stop of the operation of the load device due to the reduction of the charging voltage. The problem of being unable to do so arises.

  In addition, when the load device is a communication device such as a sensor node that measures information about the environment, it is desired that the operation of the system be restored about 10 minutes after the power generation element starts generating power. However, since the conventional power supply device charges a large-capacity lithium ion capacitor such as 40 F, the output voltage supplied to the load device cannot be quickly raised, and it takes several hours until the operation of the load device is restored. There was a problem that it took. This problem cannot be solved even in the power supply device described in Patent Document 1.

  The present invention has been made in view of the above problems, and provides a power storage system and a power storage method capable of returning the operation of a load device in a short time when a power generation element generates power. For the purpose.

  In order to solve the above problem, after the recharge of the lithium ion capacitor is started, the minimum voltage necessary for returning the operation of the load device is, for example, 2.7 V (margin of 0.2 V), for example, when the operation is stopped It is necessary to have a hysteresis width between the voltage of the current and the voltage at the time of returning from the operation. However, for example, when the voltage value of the capacitor having a capacity of 40F is charged from 2.5 V to 2.7 V and the operation of the load device is restored, the charging current supplied from the energy harvesting element is small. A long charging time is required, and the load device is stopped for several hours. As a result of further intensive studies, the inventors have derived the present invention.

  In order to achieve the above object, a power storage system according to one aspect of the present invention includes a power generation element that performs environmental power generation, a first storage battery that is supplied with power generated by the power generation element and that supplies power to a load device, and A second storage battery having a smaller capacity than the first storage battery and connected in series to the first storage battery, and connected in parallel to the second storage battery, short-circuiting both ends of the second storage battery in the closed state, and an open state A first switch unit that opens a short-circuit state of the second storage battery, and a switching unit that controls an open / closed state of the first switch unit. When both ends of the two storage batteries are short-circuited and power is supplied from the first storage battery to the load device via the first switch unit, the charging voltage of the first storage battery is compared with a predetermined first threshold voltage. And the first storage When the charging voltage of the battery becomes equal to or lower than the first threshold voltage, the first switch unit is controlled to be in an open state, and both ends of the second storage battery are opened from a short circuit state by the first switch unit. When the power generation element charges the series circuit of the first storage battery and the second storage battery, the charging voltage of the entire series circuit or a predetermined part is detected, and the entire series circuit is charged. When the voltage becomes equal to or higher than a predetermined second threshold voltage that is higher than the first threshold voltage, the first switch unit is controlled to be closed.

In the power storage system having such a configuration, the second storage battery having a small capacity is connected in series to the first storage battery, and the first switch unit is connected in parallel to the second storage battery. The first switch unit short-circuits both ends of the second storage battery in the closed state, and opens the short-circuit state of the second storage battery in the open state. The switching unit controls the open / closed state of the first switch unit. The switching unit charges the first storage battery when both ends of the second storage battery are short-circuited by the first switch unit and power is supplied from the first storage battery to the load device via the first switch unit. The voltage is compared with a first threshold voltage.
Then, in a state where power is being supplied from the first storage battery to the load device via the first switch unit, the switching unit is configured such that when the charging voltage of the first storage battery is equal to or lower than the first threshold voltage, The switch part is opened to open the short circuit between both ends of the second storage battery. In addition, when the short-circuit state of the second storage battery is released and power is supplied from the power generation element to the series circuit of the first storage battery and the second storage battery, the switching unit, for example, the first storage battery and the second storage battery When the charging voltage with the storage battery (the charging voltage of the entire series circuit) is detected and the charging voltage becomes equal to or higher than a predetermined second threshold voltage, the first switch unit is closed to connect both ends of the second storage battery. Short circuit.

Further, for example, the switching unit detects the charging voltage of the second storage battery alone (charging voltage of a predetermined part of the series circuit), and the total charging voltage of the charging voltage of the second storage battery and the charging voltage of the first storage battery. When the (charging voltage of the entire series circuit) becomes equal to or higher than a predetermined second threshold voltage, the first switch unit may be closed to short-circuit both ends of the second storage battery.
Thus, in the power storage system, when the power generation element generates power, the operation of the load device can be restored in a short time.
Moreover, since the charging voltage of the second storage battery having a small capacity increases in a short time, it can be increased to a voltage equal to or higher than the second threshold value in a short time. For this reason, the power storage system can restore the operation of the load device in a short time.
In a normal state, the second storage battery is short-circuited by the first switch unit, and both the positive electrode and the negative electrode have the same potential as the positive electrode of the first storage battery. Therefore, when the first switch unit is opened, Charging to the second storage battery is started from the potential of the first storage battery. For this reason, the power storage system can charge the second storage battery to a voltage equal to or higher than the second threshold value in a short time. In other words, the second storage battery is connected in series with the first storage battery, so that the charging operation is started from the potential of the first storage battery even if the potential difference between the positive electrode and the negative electrode of the second storage battery itself is small. For this reason, the power storage system can restore the operation of the load device in a short time.

  Further, in the power storage system according to one aspect of the present invention, the capacity of the first storage battery is a power generation amount of the power generation element, an average value of power consumption of the load device that supplies power from the first storage battery, and A time for continuously driving the load device with the power stored in the first storage battery, and the capacity of the second storage battery is an average value of the power generation amount of the power generation element and the power consumption of the load device. And the time from when the operation of the load device stops due to a decrease in the charging voltage of the first storage battery until the power generation element generates power and restores the operation of the load device. It may be.

In the power storage system having such a configuration, when determining the capacity of the first storage battery that supplies power to the load device, the power generation amount of the power generation element, the average value of the power consumption of the load device, and the first storage battery The capacity of the first storage battery is determined based on the time during which the load device is continuously driven by the accumulated power. Further, in the power storage system, when determining the capacity of the second storage battery having a small capacity, the power generation amount of the power generation element, the average value of the power consumption of the load device, and power generation by the power generation element return the operation of the load device. The capacity of the second storage battery is determined based on time until
Thereby, in an electrical storage system, a load apparatus can be continuously driven for desired time with the electric power accumulate | stored in the 1st storage battery. Further, in the power storage system, when the power generation is performed by the power generation element, the operation of the load device can be restored in a desired time.

Moreover, the electrical storage system which concerns on 1 aspect of this invention WHEREIN: You may make it a said 1st storage battery be a capacitor of a kind with a smaller leakage current than a said 2nd storage battery.
In the power storage system having such a configuration, the first storage battery is a capacitor that holds electric power for a long time, and in order not to waste the stored electric power, the first storage battery includes a capacitor with a small leakage current. Used. On the other hand, the second storage battery is a capacitor that is used only for a short time from when power is supplied to the second storage battery by the power generation element until the operation of the load device is restored, and the maximum voltage to be charged is The difference between the first threshold value and the second threshold value is used only at a low charging voltage. For this reason, in a power storage system, a capacitor having a large leakage current can be used as the second storage battery.
Thereby, the 1st storage battery can hold electric power for a long time, without consuming the accumulated electric power wastefully.

  Further, in the power storage system according to one aspect of the present invention, the power storage system further includes a second switch unit that connects or opens the power storage system and the load device, and the switching unit is configured to supply a charging voltage of the first storage battery. When the charging voltage of the first storage battery exceeds the third threshold voltage compared to the third threshold voltage that is equal to or higher than the first threshold voltage, the second switch unit is connected, and When the charging voltage of one storage battery is equal to or lower than the third threshold voltage, the second switch unit may be opened.

In the power storage system having such a configuration, the switching unit has a second state when the charging voltage of the first storage battery exceeds the voltage of the third threshold and the power necessary for the load device can be supplied from the first storage battery. The switch unit is connected to supply power to the load device. On the other hand, when the charging voltage of the first storage battery is equal to or lower than the voltage of the third threshold and the power required for the load device cannot be supplied from the first storage battery, the switching unit opens the second switch unit, Stop supplying power to the load device.
Thereby, the power storage system can supply the necessary power to the load device by stopping the power supply to the load device by opening the second switch unit in a state where the necessary power cannot be supplied to the load device. In the case of the state, the second switch unit can be connected to supply power to the load device.

In the power storage system according to one aspect of the present invention, the voltage of the third threshold is set to the same voltage as the voltage of the first threshold, and the switching unit closes the first switch and When short-circuiting both ends of the second storage battery, the second switch portion is connected, and when the first switch portion is opened and both ends of the second storage battery are opened from the short-circuit state, the second switch The part may be in an open state.
In the power storage system having such a configuration, the switching unit is in a state in which the first switch unit is closed and both ends of the second storage battery are short-circuited, that is, a state in which necessary power can be supplied from the first storage battery to the load device. In this case, the second switch unit is connected to supply power to the load device. In addition, the switching unit charges the series circuit of the first storage battery and the second storage battery from the power generation element in a state where both ends of the second storage battery are opened from the short-circuited state by opening the first switch unit. If so, the second switch unit is opened.
Accordingly, the power storage system can place the second switch unit in the connected state when the first switch unit is in the closed state, and can open the second switch unit when the first switch unit is in the open state. . That is, the power storage system can control the open / close state of the first switch unit and the open / close state of the second switch unit at the same timing.

The power storage system according to one aspect of the present invention includes a DC / DC converter that converts an output voltage of the power generation element into a predetermined voltage and supplies power to the first storage battery and the second storage battery, and the DC The / DC converter may control the output voltage so that the charging voltage of the first storage battery does not exceed a predetermined upper limit voltage.
In the power storage system having such a configuration, a DC / DC converter is connected to the output side of the power generation element. This DC / DC converter converts the output voltage of the power generation element into a voltage corresponding to the power supply voltage supplied to the load device. The DC / DC converter uses the converted voltage to supply power to the first storage battery when the first switch part is closed, and when the first switch part is open, the first storage battery and the second storage battery are connected in series. Supply power to the circuit. Further, the DC / DC converter controls the output voltage so as not to exceed a predetermined upper limit voltage so that the first storage battery is not overcharged.
Accordingly, the power storage system can convert the output voltage of the power generation element into a voltage that can operate the load device. Further, the DC / DC converter can prevent the first storage battery from being overcharged.

In the power storage system according to one aspect of the present invention, the first storage battery may be a lithium ion capacitor.
In the power storage system having such a configuration, the large-capacity first storage battery needs to retain electric charge for a long time. For this reason, a lithium ion capacitor with a small leakage current is used for the first storage battery.
Thus, the first storage battery can be held for a long time without wastefully consuming the power supplied from the power generation element. Therefore, the power storage system of the present invention operates the load device for a long time even when the power generation element stops power generation or when the power generation amount of the power generation element is smaller than the power consumption of the load device. be able to.

In order to achieve the above object, a power storage method according to an aspect of the present invention includes a power generation element that performs environmental power generation, a first storage battery that is fed with power generated by the power generation element and that supplies power to a load device, and A second storage battery having a smaller capacity than the first storage battery and connected in series to the first storage battery, and connected in parallel to the second storage battery, short-circuiting both ends of the second storage battery in the closed state, and an open state In this case, a power storage method in a power storage system comprising: a first switch unit that opens a short circuit state of the second storage battery; and a switching unit that controls an open / close state of the first switch unit, wherein the switching unit includes: When both ends of the second storage battery are short-circuited by the first switch unit and power is supplied from the first storage battery to the load device via the first switch unit, the charging voltage of the first storage battery is set to a predetermined value. of A step of controlling the first switch unit to be in an open state when a charging voltage of the first storage battery is equal to or lower than the voltage of the first threshold value compared to a voltage of one threshold value; In the case where both ends of the second storage battery are opened from the short-circuit state by the first switch unit, and the series circuit of the first storage battery and the second storage battery is charged from the power generation element, the entire series circuit Or detecting a charging voltage at a predetermined part and controlling the first switch unit to be closed when the charging voltage is equal to or higher than a predetermined second threshold voltage.
Thus, in the power storage system, when the power generation element generates power, the operation of the load device can be restored in a short time.

  According to the power storage system of the present invention, when the power generation element generates power, the operation of the load device can be restored in a short time.

It is explanatory drawing which shows the outline | summary of a wireless sensor system. It is a block diagram which shows the structural example of the sensor node using the electrical storage system which concerns on 1st Embodiment. It is explanatory drawing which shows the aspect of the consumption current in the load apparatus which concerns on 1st Embodiment. It is explanatory drawing which shows the external appearance of the solar cell which concerns on 1st Embodiment, and the connection state of a photovoltaic cell. It is a block diagram which shows the connection structure of the 1st storage battery and 2nd storage battery which concern on 1st Embodiment. It is explanatory drawing which shows the electric power feeding state to the load apparatus when the 1st switch part which concerns on 1st Embodiment is an ON state. It is explanatory drawing which shows the electric power feeding state from a solar cell to a 2nd storage battery when the 1st switch part which concerns on 1st Embodiment is an OFF state. It is a flowchart which shows the process sequence in the electrical storage system which concerns on 1st Embodiment. It is an image figure which shows the operation example of the electrical storage system which concerns on 1st Embodiment. FIG. 10 is a partially enlarged view of FIG. 9. It is an image figure which shows the operation example of the electrical storage system in the case of the three-day holiday which concerns on 1st Embodiment. It is a block diagram which shows the structural example of the electrical storage system which concerns on 2nd Embodiment. It is a 1st flowchart which shows the process sequence in the electrical storage system which concerns on 2nd Embodiment. It is a 2nd flowchart which shows the process sequence in the electrical storage system which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is an explanatory diagram showing an outline of the wireless sensor system 1. As shown in the figure, the wireless sensor system 1 includes a monitoring center 20 and sensor nodes 10a and 10b. Each of the sensor nodes 10a and 10b includes a power storage system 100 (see FIG. 2) of the present invention described later.
The monitoring center 20 collects the measurement results of the surrounding environment at the sensor nodes 10a and 10b, and performs arithmetic processing on the collected measurement results. The sensor nodes 10a and 10b wirelessly transmit the measurement results to the monitoring center 20.

Here, the measurement result includes information detected by the sensor nodes 10a and 10b, for example, information indicating temperature, humidity, CO ₂ concentration, vibration, water level, illuminance, voltage, current, sound, image, and the like. included. Further, the measurement result may include a result of determining the presence or absence of a person using an infrared sensor or the like. Furthermore, the sensor nodes 10a and 10b may be stationary devices, or may be wall-mounted devices or devices that are attached to walls.

The sensor nodes 10a and 10b operate by being supplied with power from an energy harvest (Energy Harvest) power supply, and do not require laying of power supply wiring or the like, thus increasing the degree of freedom in arrangement.
In FIG. 1, two sensor nodes 10a and 10b are shown as sensor nodes. However, there may be one sensor node or three or more sensor nodes.
In addition, the sensor node 10a and the sensor node 10b have the same configuration, and in the following description, either one or both are described as the sensor node 10.

  FIG. 2 is a configuration diagram illustrating a configuration example of the sensor node 10 using the power storage system 100 according to the present embodiment. The sensor node 10 is a sensor node installed in a room such as an office, for example, and is a sensor node to which power is supplied by sunlight or indoor light power generation. The sensor node 10 acquires environmental information on temperature and humidity, and periodically transmits the environmental information to the monitoring center 20 by radio. For example, the sensor node 10 transmits environmental information to the monitoring center 20 at intervals of 5 minutes.

As shown in FIG. 2, the sensor node 10 includes a power storage system 100 that stores the generated power of a solar battery 110 (power generation element) that performs environmental power generation in a storage battery, and a load device 200 that is fed from the power storage system 100. Is done.
The load device 200 is, for example, an environment monitoring device 210 that functions as a wireless sensor that operates without wiring or battery replacement. The environmental monitoring device 210 includes a temperature sensor 211 that measures the temperature in a room such as an office, and a humidity sensor 212 that measures the humidity in the room. The environment monitoring device 210 periodically wirelessly transmits the indoor temperature information measured by the temperature sensor 211 and the indoor humidity information measured by the humidity sensor 212 to the external monitoring center 20 by the wireless communication unit 213.

In the following description, when “the load device 200 stops operation”, since the power supply voltage required by the load device 200 cannot be received from the power storage system 100, the load device 200 performs the measurement operation and the communication operation. This means a state where it cannot be performed, and is different from the sleep period (pause period) when the load device 200 performs periodic transmission.
Further, when “the load device 200 returns to operation”, the load device 200 temporarily stops its operation due to a power supply voltage drop, and then the power supply voltage required by the load device 200 can be received again from the power storage system 100. This means that the load device 200 is ready to perform the measurement operation and the communication operation.

First, the load device 200 will be described.
In FIG. 2, the load device 200 operates by receiving power from the power storage system 100, and starts operation when the power supply voltage supplied from the power storage system 100 is, for example, 2.7 V or more. The operation is stopped when the power supply voltage supplied from the power supply becomes 2.5 V or less. In other words, the load device 200 stops operating when the power supply voltage supplied from the power storage system 100 is, for example, 2.5 V or less, and once stopped, the power supply voltage is increased to, for example, 2.7 V or more. Then, the operation is restored again, and has a hysteresis characteristic of 0.2 V with respect to the power supply voltage.

  The temperature sensor 211 and the humidity sensor 212 are configured by measuring instruments and detectors according to the intended use of the sensor node 10. The temperature sensor 211 and the humidity sensor 212 perform measurement in accordance with the control of the wireless communication unit 213 and output information indicating the obtained measurement result to the wireless communication unit 213. The measurement by the temperature sensor 211 and the humidity sensor 212 is performed in accordance with the timing at which the wireless communication unit 213 performs wireless transmission, for example.

  The wireless communication unit 213 encodes and modulates the measurement results input from the temperature sensor 211 and the humidity sensor 212 to generate a transmission signal, and periodically transmits the transmission signal to the monitoring center 20 by wireless communication. Note that most of the power consumption in the environment monitoring device 210 is spent on transmission power when the wireless communication unit 213 performs wireless transmission. In the present embodiment, the wireless communication unit 213 does not have a wireless reception function in order to reduce power consumption. However, the wireless communication unit 213 is not necessarily limited to this, and if desired, the wireless communication unit 213 213 may have a reception function.

  In addition, the environment monitoring device 210 shifts to a sleep state (rest period) and reduces power consumption when the wireless communication unit 213 does not perform wireless transmission. For example, when the transmission interval time is set to T1 minutes, the environment monitoring device 210 enters a sleep state for T1 minutes, and returns again after the T1 minutes have elapsed. When returning, the environment monitoring device 210 again acquires temperature and humidity information and wirelessly transmits the information. That is, the environment monitoring device 210 is configured not to acquire temperature and humidity information and wirelessly transmit during sleep.

FIG. 3 is an explanatory diagram showing an aspect of current consumption in the load device 200 according to the present embodiment. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the amount of current consumption. The load device 200 transmits, for example, every 5 minutes. For example, as illustrated in FIG. 3, the load device 200 starts a communication operation from time t11 and ends the communication operation at time t13.
Then, in the communication period Tm from time t11 to t13, current flows at a peak value of about the maximum current A2 (several mA) at the time t12. Thereafter, a suspension period (sleep period) Ts from time t13 to time t21 has elapsed, and at time t21 after five minutes have elapsed from time t11, the load device 200 starts the communication operation again, and performs communication operation at time t23. finish. In the communication period Tm from time t21 to time t23, current flows at a peak value of about the maximum current A2 (several mA) at time t22.
In this case, the current flowing from the power storage system 100 to the load device 200 is a current consumption of about the current A1 (several tens of μA) as an average value.

Returning to FIG. 2, the power storage system 100 will be described.
The power storage system 100 supplies power to the load device 200 and operates the load device 200. This power storage system 100 includes a solar battery 110 using an energy harvesting element, a DC / DC converter 120 (DC voltage-DC voltage converter), a first storage battery 130, a second storage battery 140, a switching unit 150, A first switch unit 160 and a voltage detection unit 170 are provided.

  The solar cell 110 is a low-illuminance solar cell, for example, a solar cell that is used at an illuminance of 10,000 (Lux) or less. In the present embodiment, the power generation capability of the solar cell 110 has a power generation capability of about 200 to 500 (μW) when the brightness of the lamp is about 200 lux. The solar battery 110 charges the first storage battery 130 and the second storage battery 140 and supplies power to the load device 200 during a period when an electric lamp is turned on in an office or the like.

  FIG. 4 is an explanatory diagram showing an overview of the solar battery according to the present embodiment and the connection state of the solar battery cells. As shown in the plan view of FIG. 4A, on the light-receiving surface side of the solar battery 110, four solar battery cells of the solar battery cell A111, the solar battery cell B112, the solar battery cell C113, and the solar battery cell D114. However, these four solar cells A111 to D114 are connected in series to obtain a predetermined output voltage Vs as shown in FIG. 4B. Has been.

  The solar battery 110 shown in FIG. 4 is an example in which four solar cells A111 to D1 are connected in series. The number of solar cells connected in series is selected so that the voltage Vs output to the DC / DC converter 120 is a voltage at which the DC / DC converter 120 can perform step-up and step-down operations with a predetermined efficiency or higher. Is done. For example, when the solar cell is a low illuminance dye-sensitized solar cell, it is desirable that the number of solar cells connected in series is, for example, at least 3 or more.

Returning to FIG. 2, the description of the power storage system 100 will be continued.
The input side of the DC / DC converter 120 is connected to the output side of the solar cell 110. The output voltage Vs of the solar battery 110 is input to the DC / DC converter 120. The DC / DC converter 120 converts the input voltage Vs into a voltage corresponding to the power supply voltage to the load device 200. Note that the DC / DC converter 120 is configured with a boost converter device or the like when the output voltage Vs of the solar cell 110 is lower than the voltage required by the load device 200, for example. The DC / DC converter 120 outputs the converted voltage to the power supply line DCL1, and charges the first storage battery 130 or the series circuit of the first storage battery 130 and the second storage battery 140. Note that the output voltage of the DC / DC converter 120 is controlled so as not to exceed a predetermined upper limit voltage (for example, 3.7 V), so that the charging voltage of the first storage battery 130 is not overcharged. For example, when the input voltage Vs exceeds the upper limit voltage (3.7 V), the DC / DC converter 120 steps down to a voltage corresponding to the power supply voltage to the load device 200.
Normally, even when the output voltage (power generation voltage) Vs of the solar battery 110 is maximum, the upper limit voltage of the first storage battery 130 is not exceeded.
The DC / DC converter 120 includes an integrated circuit. For example, the DC / DC converter 120 is configured to set the upper limit value of the output voltage by adjusting the resistance value of an external external resistor.

The first storage battery 130 and the second storage battery 140 are connected in series. The first storage battery 130 and the second storage battery 140 are charged by the solar battery 110 and accumulate electric charges.
The first storage battery 130 is a lithium ion capacitor (LIC), for example, a 40 F (Farad) large capacity lithium ion capacitor having a larger capacity than the second storage battery 140. Note that the 40 F lithium ion capacitor constituting the first storage battery 130 has less leakage current than the second storage battery 140. The first storage battery 130 is supplied with the generated power of the solar battery 110 via the DC / DC converter 120 when the first switch unit 160 is in an ON state while the lamp is lit in an office or the like. The Moreover, the 1st storage battery 130 is the electric power charged by the 1st storage battery 130, when the solar cell 110 is not generating electric power, or when the electric power generation amount of the solar cell 110 is less than the electric power consumption of the load apparatus 200. Is supplied to the load device 200. For example, the first storage battery 130 supplies electric power charged in the first storage battery 130 to the load device 200 when the first switch unit 160 is in an ON state during a period when the lamp is turned off in an office or the like.
Note that the lithium ion capacitor of the first storage battery 130 is charged to a voltage of, for example, about 2.5V to 3.7V at the time of shipment.

  The second storage battery 140 is a capacitor having a smaller capacity than that of the first storage battery 130, and is, for example, a 1F (Farad) electric double layer capacitor (EDLC). The second storage battery 140 is connected to the first storage battery 130 in series. Further, the electric double layer capacitor constituting the second storage battery 140 has a leakage current larger than that of the lithium ion capacitor of the first storage battery 130. The second storage battery 140 is supplied with the generated power of the solar battery 110 via the DC / DC converter 120 when the first switch unit 160 is in an OFF state while the lamp is lit in an office or the like. The Moreover, the 2nd storage battery 140 supplies the electric power currently charged by the 2nd storage battery 140 to the load apparatus 200, when a battery value is more than predetermined value.

  In addition, since the 1st storage battery 130 needs to preserve | save an electric charge over a long time, the lithium ion capacitor with few leak currents is used as the 1st storage battery 130. FIG. On the other hand, the second storage battery 140 is a capacitor that is short-circuited at both ends in a normal state and used only for a short time when the operation of the load device 200 is restored, and the maximum voltage to be charged is the first threshold value. The voltage is about the difference voltage (0.2 V) from the second threshold, and is used at a very low charging voltage. For this reason, a capacitor having a larger leakage current than the first storage battery 130 can be used for the second storage battery 140. The second storage battery 140 has a capacity of a voltage difference between 2.7 V (second threshold voltage) and 2.5 V (first threshold voltage) of the second storage battery 140, and at least one load device. 200 operations are possible. Thereby, in the electrical storage system 100, after connecting the 1st switch part 160, it can avoid that the voltage Va of the 1st storage battery 130 will be 2.5V (voltage of the 1st threshold value) or less immediately again. .

  Further, the capacity of the first storage battery 130 is not limited to 40 F, and is appropriately determined based on the power generation amount of the solar battery 110, the average value of the power consumption of the load device 200, and the time for which the load device 200 is to be continuously driven. Capacitors with a large capacity can be selected. The capacity of the second storage battery 140 is not limited to 1F, and is appropriately determined based on the power generation amount of the solar battery 110, the average value of the power consumption of the load device 200, and the time for which the load device 200 is to be restored. Capacitors with a large capacity can be selected.

FIG. 5 is a configuration diagram showing a connection configuration between the first storage battery 130 and the second storage battery 140 according to the present embodiment. FIG. 5A shows an example in which the first storage battery 130 and the second storage battery 140 are configured by a single capacitor. FIG. 5B shows an example in which the first storage battery 130 and the second storage battery 140 are configured with a plurality of capacitors.
As shown in FIG. 5A, the first storage battery 130 is composed of a 40F large-capacity lithium ion capacitor, and the second storage battery 140 is composed of a 1F small-capacity electric double layer capacitor. The terminal of the positive electrode (+) of the second storage battery 140 is connected to the power supply line DCL1, and the negative electrode (−) terminal of the second storage battery 140 is connected to the positive electrode (+) of the first storage battery 130 via the power supply line DCL2. Connected to the terminal. The negative electrode (−) terminal of the first storage battery 130 is connected to the ground G.

Returning to FIG. 2, the description of the power storage system 100 will be continued.
The first switch unit 160 is connected to the second storage battery 140 in parallel. The first switch unit 160 short-circuits both ends of the second storage battery 140 in the ON state (closed state), and opens both ends of the second storage battery 140 from the short-circuit state in the OFF state (open state). .

  The terminal a in the first switch unit 160 is connected to the node Nb of the power supply line DCL1, and is connected to the positive electrode (+) terminal of the second storage battery 140 via the node Nb. The terminal b in the first switch unit 160 is connected to the node Nc of the feeder line DCL2, and the negative electrode (−) terminal of the second storage battery 140 and the positive electrode (+) of the first storage battery 130 are connected via the node Nc. Is connected to the terminal.

  And when the 1st switch part 160 is an ON state, ie, when the both ends of the 2nd storage battery 140 are short-circuited, feeding line DCL1 and feeding line DCL2 are connected, and the positive electrode (+) terminal of the 1st storage battery 130 Are directly connected to the feeder line DCL1 via the first switch section 160. When the first switch unit 160 is in the ON state, the charging voltage Va of the first storage battery 130 is output to the power supply line DCL1.

  On the other hand, when the 1st switch part 160 is an OFF state, the 1st storage battery 130 and the 2nd storage battery 140 are connected in series. And when the 1st switch part 160 is an OFF state, the voltage Vb of the positive electrode (+) terminal of the 2nd storage battery 140 is output to feeder line DCL1. The voltage Vb of the positive electrode (+) terminal of the second storage battery 140 is a charging voltage Vb of a series circuit of the first storage battery 130 and the second storage battery 140, the charging voltage of the second storage battery 140 itself, and the first storage battery 130. Is a voltage obtained by adding the charging voltage Va.

  In the following description, “the voltage Vb of the positive electrode (+) terminal of the second storage battery 140” or “the charging voltage Vb of the series circuit of the first storage battery 130 and the second storage battery 140” is simply referred to as “the second storage battery 140. May be referred to as “voltage Vb”. Further, the charging voltage Va of the first storage battery 130 is a voltage of the positive electrode (+) terminal of the first storage battery 130, and this “voltage Va of the positive electrode (+) terminal of the first storage battery 130” or “ “Charge voltage Va” may be simply referred to as “voltage Va of first storage battery 130”.

  5A shows an example in which the first storage battery 130 and the second storage battery 140 are configured by a single capacitor. However, as shown in FIG. 5B, the first storage battery 130 and the second storage battery 140 are shown. 140 may be composed of a plurality of storage capacitors. That is, each of the first storage battery 130 and the second storage battery 140 can be configured by an arbitrary number of storage capacitors.

Returning to FIG. 2, the description of the power storage system 100 will be continued.
The first switch unit 160 is turned on or off according to the instruction content of the control signal CNT1 input from the switching unit 150. 2 shows an example in which the first switch unit 160 is configured by a switch using a mechanical contact, but in actuality, the switch is a MOSFET (Metal Oxide Field Effect Transistor) or an IGBT (IGBT). It includes a semiconductor switch using a semiconductor switching element such as Insulated Gate Bipolar Transistor).

  The voltage detector 170 is configured using, for example, a resistance voltage dividing circuit, and detects the voltage Vout of the feeder line DCL1. The voltage detection unit 170 outputs the voltage detection signal Vf of the voltage Vout of the power supply line DCL1 to the switching unit 150. The voltage detected by the voltage detection unit 170 is the voltage Va of the first storage battery 130 when the first switch unit 160 is in the ON state, and the voltage Vb of the second storage battery 140 when the first switch unit 160 is in the OFF state.

The switching unit 150 includes a comparison unit 151.
The comparison unit 151 compares the voltage detection signal Vf of the voltage Vout of the feeder line DCL1 input from the voltage detection unit 170 with predetermined reference voltages Ref1 and Ref2 included in the own unit.
The switching unit 150 outputs to the first switch unit 160 a control signal CNT1 for turning on / off (opening / closing) the first switch unit 160 according to the comparison result in the comparison unit 151.

  When the comparison unit 151 determines that the voltage Vout of the power supply line DCL1 is 2.5 V (first threshold voltage) or less, the switching unit 150 outputs the control signal CNT1 that turns the first switch unit 160 to the OFF state. Output. In addition, the switching unit 150 outputs the control signal CNT1 that turns off the first switch unit 160, and then the voltage Vout of the feeder line DCL1 becomes 2.7 V (second threshold voltage) or higher by the comparison unit 151. When the determination is made, the control signal CNT1 for turning on the first switch unit 160 is output. That is, the switching unit 150 controls the open / close state of the first switch unit 160 with a hysteresis characteristic of 0.2V width between 2.5V and 2.7V.

  More specifically, when the first switch unit is in the ON state, the comparison unit 151 compares the voltage detection signal Vf of the voltage Vout of the feeder line DCL1 with a predetermined reference voltage Ref1. The reference voltage Ref1 corresponds to a voltage of 2.5 V (first threshold voltage) used when determining that the first storage battery 130 is approaching an overdischarged state. Whether the voltage Va of the first storage battery 130 is 2.5 V or less by comparing the voltage detection signal Vf of the feeder line DCL1 with a predetermined reference voltage Ref1 when the first switch unit 160 is ON. Determine whether or not. Then, when the voltage Va of the first storage battery 130 is 2.5 V or less, the switching unit 150 outputs the control signal CNT1 to the first switch unit 160 and turns off the first switch unit 160. First storage battery 130 and second storage battery 140 are connected in series. Thereby, as for the electrical storage system 100, the charge to the 1st storage battery 130 and the electric power feeding to the load apparatus 200 from the 1st storage battery 130 stop.

Further, the comparison unit 151 compares the voltage detection signal Vf of the voltage Vout of the feeder line DCL1 with a predetermined reference voltage Ref2 in a state where the first switch unit 160 is OFF. This reference voltage Ref2 is a state in which the power storage system 100 stops charging from the solar battery 110 to the first storage battery 130 and feeding from the first storage battery 130 to the load device 200 (hereinafter referred to as feeding from the first storage battery). This corresponds to a voltage of 2.7 V (second threshold voltage) used when determining whether or not to return to the normal state from the stop state.
The comparison unit 151 compares the voltage detection signal Vf of the feeder line DCL1 with the reference voltage Ref2 in a state where the first switch unit 160 is OFF, thereby determining whether or not the voltage Vb of the second storage battery 140 is 2.7 V or higher. Determine whether. Then, when the voltage Vb of the second storage battery 140 is 2.7 V or higher, the switching unit 150 turns on the first switch unit 160 and short-circuits both ends of the second storage battery 140 so that the first storage battery The positive electrode (+) terminal 130 is directly connected to the power supply line DCL1. Thereby, as for the electrical storage system 100, the charge to the 1st storage battery 130 and the electric power feeding to the load apparatus 200 from the 1st storage battery 130 are restarted.

  The switching unit 150 detects the charging voltage of the second storage battery 140 alone (charging voltage of a predetermined part of the series circuit) by the voltage detection unit 170, and the charging voltage of the second storage battery 140 and the first storage battery 130. When the total charging voltage (charging voltage of the entire series circuit) becomes equal to or higher than a predetermined second threshold voltage, both ends of the second storage battery 140 are short-circuited by closing the first switch unit 160. You may do it. In this case, the switching unit 150 may consider the voltage of the first storage battery 130 as the first threshold value, and determine the charging voltage of the entire series circuit using only the storage capacity of the second storage battery 140 alone. Then, when both ends of the second storage battery 140 are opened from the short-circuited state by the first switch unit 160, the switching unit 150 is charged from the solar battery 110 to the series circuit of the first storage battery 130 and the second storage battery 140. In addition, when the charging voltage of the entire series circuit or a predetermined portion is detected, and the charging voltage of the entire series circuit becomes equal to or higher than a predetermined second threshold voltage that is higher than the first threshold voltage, The first switch unit 160 may be controlled to be turned on.

Next, the operation of the power storage system 100 will be described.
In the power storage system 100, the power (charge) accumulated in the first storage battery 130 when the solar battery 110 is not generating power or when the power generation amount of the solar battery 110 is less than the power consumption of the load device 200. Thus, the load device 200 is driven. The power storage system 100 is configured so that, for example, the load device 200 can be driven for about 60 hours continuously by the electric power stored in the first storage battery 130. In addition, in the power storage system 100, when the operation of the load device 200 is temporarily stopped due to a decrease in the charging voltage Va of the first storage battery 130 in a state where the power supply from the solar battery 110 is stopped, the power generation of the solar battery 110 starts again. After that, the operation of the load device 200 can be restored in about 10 minutes.
In addition, when the power generation amount of the solar battery 110 is smaller than the power consumption amount of the load device 200, the power storage system 100 once stops the operation of the load device 200 due to the decrease in the charging voltage Va of the first storage battery 130. Of course, when the power generation amount of the solar cell 110 is increased, and even when the power generation amount of the solar cell 110 is small, the load device 200 is reduced in a short time according to the power generation amount of the solar cell 110. It is configured to be able to restore the operation.

  In this specification, “when the solar cell 110 stops power generation and the load device 200 stops operation and then the solar cell 110 starts power generation again” or “the amount of power generated by the solar cell 110 depends on the load device. If the power generation amount of the solar cell 110 increases or the state where the power generation amount is low continues after the load device 200 stops operating, the solar cell 110 generates power. The case of being in a state may be simply referred to as “when solar cell 110 generates power”.

  In the power storage system 100, from the viewpoint of preventing the deterioration of the lithium ion capacitor cell of the first storage battery 130, the charging voltage Va of the first storage battery 130 is set to 2.5 V (first threshold voltage) so as not to be overdischarged. The voltage is not low. For this reason, the storage system 100 stops supplying power from the first storage battery 130 to the load device 200 when the charging voltage of the first storage battery 130 is in a voltage state close to an overdischarge state of 2.5V. For example, when the power supply voltage supplied from the power storage system 100 becomes 2.5 V or less, the load device 200 stops its operation.

Here, if only the first storage battery 130 is recharged to a predetermined voltage value and the operation of the load device 200 is restored by the first storage battery 130, the following points need to be considered.
For example, the recharge of the first storage battery 130 by the solar battery 110, the return of the operation of the load device 200, the decrease of the charge voltage Va of the first storage battery 130 due to the restart of the load device 200, and the decrease of the charge voltage Va It is necessary to prevent the repeated operation of stopping the operation of the load device 200 due to the above. For this purpose, in the power storage system 100, the voltage at which power supply to the load device 200 is started is set to, for example, 2.7 V (second threshold voltage). In accordance with this, the load device 200 itself returns to operate at a power supply voltage of 2.7 V or higher.

  However, in the power storage system 100, the charging current that can be supplied from the solar battery 110, which is an energy harvesting element, to the first storage battery 130 is as small as several tens of μA. When charging the battery, it takes a long charge time such as several hours. For this reason, the load device 200 has a problem that the operation stops for several hours when the first storage battery 130 is recharged.

  Therefore, in the power storage system 100 of the present embodiment, the second storage battery 140 and the first switch unit 160 as a switching mechanism are used together with the first storage battery 130. In the normal state where the first storage battery 130 is equal to or higher than the first threshold voltage, the power storage system 100 short-circuits both ends of the second storage battery 140 by the first switch unit 160 and performs charge / discharge using only the first storage battery 130. I am doing so. Then, when the charging voltage Va of the first storage battery 130 becomes 2.5 V, the power storage system 100 stops the supply of power to the load device 200 and sets the first switch unit 160 to the OFF state so that the first The second storage battery 140 is connected to the storage battery 130 in series.

  Thereafter, when power is generated by the solar battery 110, the solar battery 110 passes a charging current through a series circuit of the first storage battery 130 and the second storage battery 140. In this case, since the capacity of the second storage battery 140 is significantly smaller than the capacity of the first storage battery 130, the charging voltage of the second storage battery 140 rapidly increases due to the charging current from the solar battery 110. For this reason, the charging voltage Vb of the series circuit of the first storage battery 130 and the second storage battery 140 can reach the voltage of 2.7 V necessary for returning the operation of the load device 200 in a short time. Thereby, the electrical storage system 100 can return the load apparatus 200 in a short time (for example, about 10 minutes).

As described above, the power storage system 100 of the present embodiment uses the first storage battery 130 having a large capacity such that the charging time takes several hours depending on the amount of power generated by the solar battery 110, so that the output voltage that supplies power to the load device 200 is used. Vout can be raised quickly. Therefore, in the power storage system 100, for example, when the power generation of the solar battery 110 is stopped and the operation of the load device 200 is temporarily stopped due to a decrease in the voltage Va of the first storage battery 130, the solar battery 110 starts power generation. Then, the operation of the load device 200 can be restored in a short time.
In addition, the power storage system 100 outputs an output voltage Vout that supplies power to the load device 200 when the state where the power generation amount is low after the operation of the load device 200 is stopped in a state where the power generation amount of the solar battery 110 is small. Can be launched quickly. For this reason, in the power storage system 100, when the operation of the load device 200 is temporarily stopped in a state where the power generation amount of the solar cell 110 is small, the operation of the load device 200 is restored in a short time according to the power generation amount of the solar cell 110. be able to.
In addition, when the state where the amount of power generation of the solar battery 110 is small continues, after the load device 200 operates for a certain period of time, the charging voltage Va of the first storage battery 130 decreases to 2.5 V or less before the load device 200 Operation stops again. That is, in a state where the power generation amount of the solar battery 110 is small, the operation stop and the operation return of the load device 200 are repeated. However, when the operation of the load device 200 is restored, the load device 200 can continuously perform measurement and communication operation for a certain period of time.

Further, in the power storage system 100 described above, the first threshold voltage is 2.5 V, but this voltage may be a value equal to or higher than the voltage at which the lithium ion capacitor is not overdischarged. For example, if the voltage at which the lithium ion capacitor is overdischarged is 2.2V, the first threshold voltage may be a voltage exceeding 2.2V, such as 2.3V.
In the power storage system 100, the second threshold voltage is set to 2.7V so that the charging voltage of the second storage battery 140 is 0.2V. However, the present invention is not limited to this. For example, 2.6V or the like. can do. Further, the capacity of the second storage battery 140 may be changed according to the voltage of the second threshold. For example, in the power storage system 100, when the second threshold voltage is 2.6V, the capacity of the second storage battery 140 is set to 2F, and the same amount of charge as when the second threshold voltage is 2.7V can be accumulated. You may do it.

  FIG. 6 is an explanatory diagram showing a power supply state to the load device 200 when the first switch unit 160 according to the present embodiment is in the ON state. Hereinafter, with reference to FIG. 6, the aspect of the electric power feeding to the load apparatus 200 when the 1st switch part 160 is ON is demonstrated.

In the example shown in FIG. 6A, the first switch unit 160 is in the ON state, the solar battery 110 is generating power, and the charging voltage Va of the first storage battery 130 is 2.5 V (first threshold). It is an example when it exceeds.
In the state shown in FIG. 6A, when the generated power of the solar cell 110 is sufficiently large, for example, when the output voltage of the DC / DC converter 120 that converts the output voltage Vs of the solar cell 110 is 3.0V or the like. The DC / DC converter 120 supplies the power by supplying the current I1 to the load device 200, and supplies the charging current I2 to the first storage battery 130 via the first switch unit 160. Further, in the state shown in FIG. 6A, when the generated power of the solar battery 110 decreases and the generated power of the solar battery 110 becomes smaller than the power consumption of the load device 200, the first storage battery 130 starts the first switch. The electric power is supplied by supplying the current I3 to the load device 200 via the unit 160. That is, when the power generation amount of the solar battery 110 is smaller than the power consumption amount of the load device 200, the first storage battery 130 supplies the power by supplying the current I3 to the load device 200 via the first switch unit 160.

  On the other hand, as shown in FIG. 6B, when the solar cell 110 is not generating power and no power is supplied from the DC / DC converter 120, the first storage battery 130 is connected via the first switch unit 160. A current I3 is supplied to the load device 200 to supply power. In the state shown in FIG. 6B, when the output voltage of the first storage battery 130 becomes 2.5 V or less, the load device 200 stops the measurement operation and the communication operation, and from the first storage battery 130 to the load device 200. No current I3 flows. Thus, in the state shown in FIG. 6B, when the output voltage of the first storage battery 130 becomes 2.5 V or lower, the switching unit 150 turns the first switch unit 160 to the OFF state. Thereby, the electrical storage system 100 stops the charge to the 1st storage battery 130, and the electric power feeding to the load apparatus 200 from the 1st storage battery 130, and connects the 1st storage battery 130 and the 2nd storage battery 140 in series.

  FIG. 7 is an explanatory diagram showing a power supply state from the solar cell 110 to the second storage battery 140 when the first switch unit 160 according to the present embodiment is in the OFF state. Hereinafter, with reference to FIG. 7, the aspect of the electric power feeding from the solar cell 110 to the 2nd storage battery 140 and the 1st storage battery 130 when the 1st switch part 160 is OFF is demonstrated.

  FIG. 7A shows a state in which the solar battery 110 is charging the series circuit of the first storage battery 130 and the second storage battery 140 after the first switch unit 160 is turned off, and the load device. 200 shows the state which has stopped operation | movement. Immediately after the first switch unit 160 is turned off, the voltage Vout of the feeder line DCL1 becomes the voltage Vb of the second storage battery 140, but the charging voltage of the second storage battery 140 is initially approximately 0V, The voltage Vb is substantially equal to the charging voltage 2.5V of the first storage battery 130.

  Then, after the first switch unit 160 is turned off, the current I11 flows from the solar battery 110 to the series circuit of the first storage battery 130 and the second storage battery 140 connected in series. Thereby, charge to the 1st storage battery 130 and the 2nd storage battery 140 is started. In this case, since the capacity of the first storage battery 130 is significantly larger than the capacity of the second storage battery 140, the increase in the voltage Vb of the second storage battery 140 accounts for most of the increase in the charging voltage of the second storage battery 140 itself. . Therefore, charging from the solar battery 110 to the series circuit of the first storage battery 130 and the second storage battery 140 can be regarded as charging from the solar battery 110 to the second storage battery 140. For this reason, in the following description, “the operation of charging the series circuit of the first storage battery 130 and the second storage battery 140 from the solar battery 110” is referred to as “the operation of charging the solar battery 110 to the second storage battery 140”. Sometimes called.

And when the charging from the solar battery 110 to the second storage battery 140 is started, the capacity of the second storage battery 140 is as small as 1F, so the voltage Vb of the second storage battery 140 is the first storage battery 130 of 40F from the solar battery 110. As compared with the case of charging the battery, it is rapidly increased. When the voltage Vb of the second storage battery 140 rises to 2.7 V, the operation of the load device 200 is restored as shown in FIG. 7B, and a current I12 flows from the solar cell 110 to the load device 200. Further, when the power generation amount of the solar battery 110 is smaller than the power consumption amount of the load device 200, the current I13 flows from the second storage battery 140 to the load device 200.
As a result, the load device 200 can perform measurement and communication operation. Since the voltage Vb of the second storage battery 140 has increased to 2.7 V, the first switch unit 160 shifts from the OFF state to the ON state, and the power storage system 100 returns to the operation in the normal state shown in FIG.
When the first switch unit 160 changes from the OFF state to the ON state, the current I14 is supplied from the second storage battery 140 to the first storage battery 130 via the first switch unit 160, as shown in FIG. The first storage battery 130 is charged by the charge stored in the second storage battery 140.

  FIG. 8 is a flowchart showing a processing procedure in the power storage system 100 according to the present embodiment. FIG. 8 is a flowchart showing an operation flow in the above-described power storage system 100. Hereinafter, the flow of the process will be described with reference to FIG.

  First, it is assumed that the power storage system 100 is operating in a normal state (step S100). That is, in the power storage system 100, it is assumed that the first switch unit 160 is in the ON state, the voltage Va of the first storage battery 130 exceeds 2.5V, and the load device 200 is operating.

  Subsequently, the voltage detection unit 170 detects the voltage of the power supply line DCL1 (in this case, the voltage Va of the first storage battery 130), and outputs the voltage detection signal Vf to the switching unit 150 (step S105).

  Subsequently, the switching unit 150 determines whether or not the voltage Va of the first storage battery 130 exceeds 2.5 V (first threshold voltage) by comparing the voltage detection signal Vf with a predetermined reference voltage Ref1. (Step S110).

  In step S110, when it is determined that the voltage Va of the first storage battery 130 exceeds 2.5V (first threshold voltage) (step S110: Yes), that is, the voltage Va of the first storage battery 130 is When it is not 2.5 V or less, the load device 200 continues to operate (step S115), and the power storage system 100 returns to the process of step S105. Subsequently, the power storage system 100 executes the processing from step S105 onward again.

  On the other hand, when it is determined in step S110 that the voltage Va of the first storage battery 130 does not exceed 2.5V (the voltage of the first threshold) (step S110: No), that is, the voltage Va of the first storage battery 130 is When it becomes 2.5V or less, while the load apparatus 200 stops operation | movement (step S120), the electrical storage system 100 transfers to the process of step S130. When the voltage Va of the first storage battery 130 becomes 2.5 V or less, the load device 200 supplies the power supply voltage (in this case, the first storage battery 130 of the first storage battery 130) supplied from the first storage battery 130 via the feeder line DCL1. The device detects that the voltage Va) is 2.5 V or less and stops the measurement and the communication operation by itself.

  Subsequently, the switching unit 150 switches the first switch unit 160 from the ON state to the OFF state (step S130). Thereby, the electrical storage system 100 stops the charge to the 1st storage battery 130, and the electric power feeding to the load apparatus 200 from the 1st storage battery 130, and connects the 1st storage battery 130 and the 2nd storage battery 140 in series. And when the solar cell 110 is generating electric power, the 2nd storage battery 140 is charged from the solar cell 110 (step S140).

Subsequently, the voltage detection unit 170 detects the voltage of the power supply line DCL1 (in this case, the voltage Vb of the second storage battery 140), and outputs the voltage detection signal Vf to the switching unit 150 (step S150).
The switching unit 150 determines whether or not the voltage Vb of the second storage battery 140 is equal to or higher than 2.7 V (second threshold voltage) by comparing the voltage detection signal Vf with a predetermined reference voltage Ref2 (Step S1). S160).

In step S160, when it is determined that the voltage Vb of the second storage battery 140 is not equal to or higher than 2.7 V (second threshold voltage) (step S160: No), the process returns to step S130, and the switching unit 150 The OFF state of the first switch unit 160 is maintained as it is (step S130). Subsequently, the power storage system 100 repeatedly executes the processes after step S140.
That is, when the power storage system 100 shifts to a state where power supply from the first storage battery is stopped, the solar battery 110 does not generate power and the solar battery 110 does not charge the second storage battery 140. Since the voltage Vb does not increase, the processing from step S130 to step S160 is repeatedly executed. Even when the second storage battery 140 is charged from the solar battery 110, the processing from step S130 to step S160 is repeatedly executed until the voltage Vb of the second storage battery 140 becomes 2.7 V or higher.

When the solar battery 110 generates power, the voltage Vb of the second storage battery 140 increases to 2.7 V or higher, and the switching unit 150 causes the voltage Vb of the second storage battery 140 to be 2.7 V (second threshold value). Voltage) or higher (step S160: Yes), that is, when the voltage Vb of the second storage battery 140 rises to 2.7 V, the operation of the load device 200 is restored (step S170), and the switching unit 150 switches the first switch unit 160 from the OFF state to the ON state (step S175). When the voltage Vb of the second storage battery 140 becomes 2.7 V or more, the load device 200 supplies the power supply voltage (in this case, the second storage battery 140) supplied from the second storage battery 140 via the feeder line DCL1. The voltage Vb) is detected to be 2.7 V or more by itself and the operation is restored by itself. Thereby, the electrical storage system 100 returns to a normal state.
In addition, the switching unit 150 may delay the timing at which the first switch unit 160 is switched from the OFF state to the ON state in Step S175 by a predetermined time after the operation of the load device 200 is restored. Thereby, the 2nd storage battery 140 can supply the electric power for at least 1 time, when the load apparatus 200 performs a measurement operation and a communication operation.
Subsequently, the power storage system 100 returns to the process of step S105, and executes the processes after step S105 again.

Due to the above processing flow, the power storage system 100 charges the first storage battery 130 when power generation by the solar battery 110 is not performed or when the power generation amount of the solar battery 110 is smaller than the power consumption of the load device 200. When the voltage Va drops to 2.5 V or less, the discharge from the first storage battery 130 to the load device 200 is stopped.
Then, after the second storage battery 140 is connected in series to the first storage battery 130, the power storage system 100 charges the second storage battery 140 from the solar battery 110 when the solar battery 110 generates power. The power storage system 100 can rapidly charge the second storage battery 140 because the capacity of the second storage battery 140 is smaller than the capacity of the first storage battery 130. Thereby, the power storage system 100 can quickly start up the voltage output to the load device 200 using the power charged in the second storage battery 140. As a result, in the power storage system 100, the operation of the load device 200 whose operation has been temporarily stopped due to a decrease in the voltage value of the first storage battery 130 can be restored in a short time.

FIG. 9 is an image diagram illustrating an operation example of the power storage system 100 according to the present embodiment. In the example shown in FIG. 9, the vertical axis indicates the voltage value, the horizontal axis indicates the elapsed time (h: hour), and the change characteristics of the output voltage Vout appearing on the power supply line DCL1 are conceptually illustrated.
In FIG. 9, a period indicated by “bright” indicates a time zone in which the office room is brightened by illumination or external light, and a period indicated by “dark” indicates that the room in the office is turned off at night or when the illumination is turned off. It indicates a time zone in which the image becomes dark, and a period indicated by “ON” indicates a period in which the first switch unit 160 is in an ON state, and a period indicated by “OFF” indicates a period in which the first switch unit 160 is in an OFF state ing.

  In FIG. 9, the voltage Vout appearing on the power supply line DCL1 becomes the voltage Va of the first storage battery 130 when the first switch unit 160 is in the ON state, and the voltage Vout of the second storage battery 140 when the first switch unit 160 is in the OFF state. The voltage becomes Vb. For this reason, the first switch unit 160 is in the ON state during the period from the elapsed time “0 hour” to the elapsed time “72 hours” and from the elapsed time t41 to the elapsed time “120 hours”. The output voltage Vout is indicated by the voltage Va of the first storage battery 130. Further, during the period from the elapsed time “72 hours” to the elapsed time t41, the first switch unit 160 is in the OFF state, and therefore the output voltage Vout of the feeder line DCL1 is indicated by the voltage Vb of the second storage battery 140. .

  In FIG. 9, the first day is, for example, 24 hours from 8:00 am on the weekend Friday (for example, the time when the room becomes bright in the office or the like) to 8:00 am the next day. The second day is 24 hours from 8am on Saturday to 8am on the following day. The third day is 24 hours from 8 am on Sunday to 8 am on the following day. The fourth day is 24 hours from 8 am on Monday the next week to 8 am on the following day. The fifth day is 24 hours from 8am Tuesday morning to 8am the next day.

  In the example shown in FIG. 9, the first day (Friday morning from 8:00 am to Saturday morning at 8:00 am), the fourth day (Monday morning from 8:00 am to Tuesday morning at 8:00 am), and the fifth day ( From 8 am Tuesday morning to 8 am Wednesday morning), the “light” period and the “dark” period are repeated on a daily basis. On the other hand, on the second day (Saturday morning 8:00 to Sunday morning 8:00) and the third day (Sunday morning 8:00 to Monday morning 8:00), the “dark” period It is continuous. Further, at the first time point on the first day (elapsed time “0 hour”: 8:00 am on Friday morning), the first switch unit 160 is in the ON state, and the voltage Vout of the power supply line DCL1 (the voltage of the first storage battery 130 It is assumed that Va) is in a state of about 2.9V. The voltage 2.9V of the power supply line DCL1 is supplied as a power supply voltage from the power supply line DCL1 to the load device 200, and the load device 200 is in an operable state.

  Then, at the elapsed time “0 hour”, the “bright” period in which the interior of the office is brightened by external light (or illumination light) starts. The “bright” period starting at the elapsed time “0 hour” continues until the elapsed time t31 after the elapsed time “0 hour”. Then, after the elapsed time “0 hours”, when the solar cell 110 begins to hit light and the power generation of the solar cell 110 is started, charging of the first storage battery 130 from the solar cell 110 is started, and the power supply line DCL1 The voltage Vout begins to rise. At this time, since the first switch unit 160 is in the ON state, the voltage Vout of the feeder line DCL1 becomes the voltage Va of the first storage battery 130.

  Then, during the “bright” period from the elapsed time 0:00 to the elapsed time t31, the voltage Va of the first storage battery 130 gradually increases, and at time t31, the voltage Va of the first storage battery 130 reaches the maximum value Vmax.

  Subsequently, at an elapsed time t31, a “dark” period in which the office room becomes dark begins. The “dark” period starting from the elapsed time t31 continues until the elapsed time “72 hours” after the elapsed time t31. Then, after the elapsed time t31, the power generation of the solar cell 110 is stopped, and the charging from the solar cell 110 to the first storage battery 130 is stopped. Then, during the “dark” period after the elapsed time t31, the measurement and communication operation of the load device 200 are periodically repeated, whereby the charge accumulated in the first storage battery 130 gradually decreases, and the voltage of the first storage battery 130 is reduced. Va gradually decreases. This “dark” period is from the elapsed time t31 through the elapsed time “24 hours” on the second day and the elapsed time “48 hours” on the third day to the elapsed time “72 hours” on the third day. continue.

In the “dark” period from the elapsed time t31 to the elapsed time “72 hours”, the voltage Va of the first storage battery 130 gradually decreases. In this “dark” period, the voltage Va of the first storage battery 130 is 2 Since it exceeds .5V, the first switch section 160 maintains the ON state. Further, during this “dark” period, the voltage Va of the first storage battery 130 exceeds 2.5 V, so the load device 200 continues to operate.
Thus, when the load device 200 is operated on a weekly basis, the power storage system 100 charges the first storage battery 130 from the solar battery 110 by Friday (first day) on weekdays, And the third day), the load device 200 is operated using the electric power stored in the first storage battery 130.

In the example shown in FIG. 9, at the elapsed time “72 hours”, the voltage of the first storage battery 130 decreases to 2.5 V or less, and the “light” period starts immediately after the elapsed time “72 hours”. .
For this reason, at the storage elapsed time “72 hours”, the voltage Va of the first storage battery 130 decreases to 2.5 V or less, the load device 200 stops operating, and the first switch unit 160 is turned off. And when the 1st switch part 160 will be in an OFF state, the 2nd storage battery 140 is connected to the 1st storage battery 130 in series. Since the charging voltage of the second storage battery 140 is 0 V when the first switch unit 160 is turned off, the voltage Vb of the second storage battery 140 (more precisely, the first storage battery 130 and the second storage battery 140 is The charging voltage (2.5 V) of the first storage battery 130 appears as it is in the charging voltage Vb) of the series circuit.

  Then, when the “bright” period starts immediately after the elapsed time “72 hours”, light starts to hit the solar cell 110, and the solar cell 110 starts power generation and starts charging the second storage battery 140. In this case, the second storage battery 140 having a small capacity is rapidly charged by the solar battery 110, and the voltage Vb of the second storage battery 140 rises to 2.7 V at an elapsed time t41 10 minutes (min) after the start of charging. . That is, when charging the second storage battery 140 from the solar battery 110, the charging voltage Vb of the second storage battery 140 is about 40 times that when charging the first storage battery 130 with a large capacity from the solar battery 110. Ascend at a speed of. For this reason, the voltage Vb of the second storage battery 140 increases to 2.7 V after 10 minutes (min) from the start of charging.

  Then, at the elapsed time t41, when the voltage of the second storage battery 140 increases to 2.7 V, the operation of the load device 200 is restored, and the load device 200 starts the measurement operation and the communication operation. Further, at the elapsed time t41, the first switch unit 160 shifts from the OFF state to the ON state, whereby the power storage system 100 shifts to the normal state. After this elapsed time t41, the first switch unit 160 is turned on, and the voltage Va of the first storage battery 130 appears in Vout of the feeder line DCL1. And after elapsed time t41, the voltage Va of the 1st storage battery 130 changes by repeating the period of "bright" and "dark". From the fourth day onward, the first storage battery 130 gradually stores the amount of power consumed on the next Saturday and Sunday.

FIG. 10 is a partially enlarged view of FIG. FIG. 10 is an enlarged view of a portion of a region H surrounded by a broken-line circle in FIG.
In FIG. 10, at the elapsed time “72 hours”, the first switch unit 160 is turned off, and the second storage battery 140 and the first storage battery 130 are connected in series. Then, immediately after this elapsed time “72 hours”, light begins to hit the solar cell 110, and the solar cell 110 starts charging the series circuit of the second storage battery 140 and the first storage battery 130. Then, between the elapsed time “72 hours” and the elapsed time t41, the voltage Vb of the small-capacity second storage battery 140 increases rapidly, and reaches 2.7 V at the elapsed time t41.
On the other hand, the voltage Va of the large-capacity first storage battery 130 hardly changes between the elapsed time “72 hours” and the elapsed time t41 (strictly speaking, the voltage Va of the second storage battery 140 increases by about 1 / Increase by a voltage of 40).

  When the elapsed time t41 is reached and the voltage Vb of the second storage battery 140 reaches 2.7 V, the first switch unit 160 is turned on, both ends of the second storage battery 140 are short-circuited, and the first storage battery 130 The voltage Va increases by ΔV (for example, 0.05V). Moreover, the voltage Vb of the 2nd storage battery 140 falls to the voltage (2.5V + (DELTA) V) of the 1st storage battery 130. FIG. After this elapsed time t41, charging from the solar battery 110 to the first storage battery 130 is started. After this elapsed time t41, the first switch unit 160 is in the ON state (the short state of the second storage battery 140), so the voltage Vb of the second storage battery 140 and the voltage Va of the first storage battery 130 are the same voltage. In the figure, for the sake of clarity, the voltage Va is shown to be lower than the voltage Vb after the elapsed time t41, but in reality, the voltage Va and the voltage Vb are The same voltage.

  In the example shown in FIG. 9 and FIG. 10, the voltage Va of the first storage battery 130 starts to decrease from the elapsed time t31 and is just 2.5 V at the elapsed time “72 hours”. For example, the voltage Va of the first storage battery 130 may reach 2.5 V in the middle of the third day in the case of three consecutive holidays. This is because the continuous drive capability of the load device 200 required for the sensor node 10 is set to drive continuously for 60 hours.

  For example, FIG. 11 is an image diagram illustrating an operation example of the power storage system 100 in the case of three consecutive holidays according to the present embodiment. In FIG. 11, similarly to FIG. 9, the vertical axis indicates the voltage value, the horizontal axis indicates the elapsed time (h), and the voltage Va of the first storage battery 130 and the voltage Vb of the second storage battery 140 appear on the feeder line DCL <b> 1. The change characteristics of are conceptually illustrated. FIG. 11 is different from FIG. 10 in that the first day to the third day are holidays (three consecutive holidays), and the elapsed time “0 hour” on the first day to the elapsed time “72 hours” on the third day. The point that the “dark” period continues until “.

  In this example, at the elapsed time t32 on the third day, the voltage Va of the first storage battery 130 decreases to 2.5V. That is, the voltage Va of the first storage battery 130 decreases to 2.5 V at a time point t32 before the elapsed time “72 hours” on the third day. Then, at the elapsed time t32, when the voltage Va of the first storage battery 130 reaches 2.5V, the load device 200 stops its operation. Further, at this elapsed time t32, the first switch unit 160 is turned off, and the second storage battery 140 is connected to the first storage battery 130 in series. Then, since the period Tk from the elapsed time t32 to the elapsed time “72 hours” is a “dark” period, the second storage battery 140 is not charged from the solar battery 110, and the first storage battery 130 in this period Tk. The charging voltage (2.5V) appears on the power supply line DCL1 as it is.

  Then, when the elapsed time “72 hours” on the third day is reached, a period of “bright” starts from this elapsed time “72 hours”, light begins to hit the solar cell 110, the solar cell 110 starts power generation, Charging to the second storage battery 140 is started. In this case, in the solar battery 110, the second storage battery 140 having a small capacity is rapidly charged by the solar battery 110, and the voltage Vb of the second storage battery 140 is 2 at an elapsed time t41 after 10 minutes (min) from the start of charging. Raise to 7V. Then, when the voltage Vb of the second storage battery 140 rises to 2.7 V at the elapsed time t41, the operation of the load device 200 returns, and the load device 200 starts measurement and communication operations.

  Thus, even when consecutive holidays such as three consecutive holidays continue and the load device 200 stops operating from the middle of the consecutive holidays, in the power storage system 100, the solar cell 110 begins to hit light, and the solar cell 110 starts power generation. In this case, the operation of the load device 200 can be recovered in a short time.

  In the power storage system 100, when the voltage Va of the first storage battery 130 is lower than a predetermined threshold voltage (a voltage equal to or higher than the first threshold value), the communication time interval of the load device 200 may be increased. As a result, the power storage system 100 supplies the first storage battery 130 to the load device 200 when the solar cell 110 is not generating power or when the power generation amount of the solar cell 110 is less than the power consumption of the load device 200. The amount of power to be reduced can be reduced. For this reason, the electrical storage system 100 can lengthen the period which supplies electric power to the load apparatus 200. FIG.

Moreover, in the said electrical storage system 100, after the said switch part 150 makes the 1st switch part 160 OFF state, the voltage Vout of the series circuit of the 1st storage battery 130 and the 2nd storage battery 140 is 2.7V (2nd threshold value). The first switch section 160 is turned on. However, the switching unit 150 may determine the voltage of the second threshold value by looking at the potential difference (charging voltage) of the second storage battery 140.
That is, the switching unit 150 detects the charging voltage of the second storage battery 140 alone (charging voltage of a predetermined part of the series circuit) by the voltage detection unit 170, and the charging voltage of the second storage battery 140 and the first storage battery 130. When the total charging voltage (charging voltage of the entire series circuit) becomes equal to or higher than a predetermined second threshold voltage, both ends of the second storage battery 140 are short-circuited by closing the first switch unit 160. You may do it. In this case, the switching unit 150 may consider the voltage of the first storage battery 130 as the first threshold value, and determine the charging voltage of the entire series circuit using only the storage capacity of the second storage battery 140 alone. Then, when both ends of the second storage battery 140 are opened from the short-circuited state by the first switch unit 160, the switching unit 150 is charged from the solar battery 110 to the series circuit of the first storage battery 130 and the second storage battery 140. In addition, when the charging voltage of the entire series circuit or a predetermined portion is detected, and the charging voltage of the entire series circuit becomes equal to or higher than a predetermined second threshold voltage that is higher than the first threshold voltage, The first switch unit 160 may be controlled to be turned on.

As described above, the power storage system 100 of the present embodiment includes the solar battery 110 (power generation element) that performs environmental power generation, and the first storage battery that is supplied with power from the generated power of the solar battery 110 and supplies power to the load device 200. 130, a second storage battery 140 having a capacity smaller than that of the first storage battery 130 and connected in series to the first storage battery 130, and connected in parallel to the second storage battery 140. In the closed state, both ends of the second storage battery 140 are connected. A first switch unit 160 that short-circuits and opens the short-circuit state of the second storage battery 140 in the open state, and a switching unit 150 that controls the open / close state of the first switch unit 160 are provided.
When both ends of the second storage battery 140 are short-circuited by the first switch unit 160 and power is supplied from the first storage battery 130 to the load device 200 via the first switch unit 160, the switching unit 150 is switched to the first storage battery 130. When the charging voltage Va of the first storage battery 130 becomes 2.5 V or less, the first switch unit 160 is opened. When both ends of the second storage battery 140 are opened from the short-circuit state by the first switch unit 160 and the series circuit of the first storage battery 130 and the second storage battery 140 is charged from the solar battery 110, The charging voltage of the whole series circuit (the charging voltage of the first storage battery 130 and the second storage battery 140 (charging voltage of the entire series circuit) Vb) or a predetermined part is detected, and the charging voltage of the entire series circuit is If it becomes more than a high voltage 2.7V (voltage of a predetermined second threshold value) than the voltage of the first threshold value, the first switch unit 160 controls to the closed state.

  In the power storage system 100 having such a configuration, the second storage battery 140 having a small capacity is connected in series to the first storage battery 130, and the first switch unit 160 is connected in parallel to the second storage battery 140. The first switch unit 160 short-circuits both ends of the second storage battery 140 when closed, and opens the short-circuit state of the second storage battery 140 when open. The open / close state of the switching unit 150 and the first switch unit 160 is controlled. And the switching part 150 is when the both ends of the 2nd storage battery 140 are short-circuited by the 1st switch part 160, and electric power feeding is performed to the load apparatus 200 via the 1st switch part 160 from the 1st storage battery 130. The charging voltage Va of the first storage battery 130 is compared with 2.5 V (the first threshold voltage). Then, in the state where power is being supplied from the first storage battery 130 to the load device 200 via the first switch unit 160, the switching unit 150 sets the charging voltage Va of the first storage battery 130 to 2.5 V (the first threshold value). Voltage) or less, the first switch unit 160 is opened, and the short-circuited state at both ends of the second storage battery 140 is opened.

  In addition, the switching unit 150, for example, when the short-circuit state of the second storage battery 140 is released and power is supplied from the solar battery 110 to the series circuit of the first storage battery 130 and the second storage battery 140, for example, When the charging voltage (charging voltage of the entire series circuit) with the first storage battery 130 and the second storage battery 140 is detected and the charging voltage becomes 2.7 V (a predetermined second threshold voltage) or more, the first switch The both ends of the 2nd storage battery 140 are short-circuited by making the part 160 into a closed state.

Thereby, in the electrical storage system 100, when the solar cell 110 (power generation element) generates electric power, the operation of the load device 200 can be restored in a short time.
Further, in the power storage system 100, the charging voltage of the second storage battery 140 having a small capacity can be increased to a voltage of 2.7 V (second threshold voltage) or more in a short time because the charging voltage is increased in a short time. For this reason, the power storage system 100 can restore the operation of the load device 200 in a short time.
In a normal state, the second storage battery 140 is short-circuited by the first switch unit 160, and both the positive electrode and the negative electrode have the same potential as that of the positive electrode of the first storage battery 130. For this reason, when the 1st switch part 160 is open | released, the electrical storage to the 2nd storage battery 140 is started from the same electric potential as the 1st storage battery 130 in that case. Thereby, the second storage battery 140 can be charged to a voltage of 2.7 V (second threshold voltage) or more in a short time. In other words, since the second storage battery 140 is connected in series with the first storage battery 130, the charging operation starts from the potential of the first storage battery 130 even if the potential difference between the positive electrode and the negative electrode of the second storage battery 140 itself is small. Is done. For this reason, the power storage system 100 can restore the operation of the load device 200 in a short time.

  Moreover, in the said electrical storage system 100, the capacity | capacitance of the 1st storage battery 130 is the average value of the electric power generation amount of the solar cell 110 (electric power generation element), the power consumption of the load apparatus 200 which supplies electric power from the 1st storage battery 130, and 1st. It is set based on the time for which the load device 200 is continuously driven by the power stored in the storage battery 130, and the capacity of the second storage battery 140 is the power generation amount of the solar battery 110 and the average value of the power consumption of the load device 200. And the time from when the operation of the load device 200 is stopped due to the decrease in the charging voltage Va of the first storage battery 130 until the power is generated by the solar cell 110 and the operation of the load device 200 is restored. .

In the power storage system configured as described above, the power generation amount of the solar battery 110 (power generation element) and the consumption of the load device 200 are determined when the capacity of the first storage battery 130 that supplies power to the load device 200 is determined. The capacity of the first storage battery 130 is determined based on the average value of the power and the time during which the load device 200 is continuously driven by the power stored in the first storage battery 130. Further, in the power storage system 100, when determining the capacity of the second storage battery 140 having a small capacity, the amount of power generated by the solar battery 110, the average power consumption of the load device 200, and the operation after the load device 200 stops operating The capacity of the second storage battery 140 is determined based on the time until the battery 110 generates power and restores the operation of the load device 200.
Thereby, in the electrical storage system 100, the load device 200 can be continuously driven for a desired time by the electric power stored in the first storage battery 130. Moreover, in the electrical storage system 100, after the operation | movement of the load apparatus 200 stops, when the solar cell 110 produces electric power, the operation | movement of the load apparatus 200 can be returned in desired time.

In the power storage system 100, the first storage battery 130 is a type of capacitor that has a smaller leakage current than the second storage battery 140.
In the power storage system 100 having such a configuration, the first storage battery 130 is a capacitor that holds electric power for a long time, and in order not to waste the stored electric power, the first storage battery 130 has a leakage current. Fewer capacitors are used. On the other hand, the second storage battery 140 is a capacitor that is used only for a short time after the operation of the load device 200 stops and until the solar cell 110 generates power and restores the operation of the load device 200, and is charged. The maximum voltage is 0.2 V (the difference voltage between the first threshold value and the second threshold value), and is used only at a low charging voltage. For this reason, in the power storage system, a capacitor having a larger leakage current than the first storage battery 130 can be used as the second storage battery 140.
Thereby, the 1st storage battery 130 can hold | maintain electric power for a long time, without consuming the accumulated electric power wastefully.

  The power storage system 100 includes a DC / DC converter 120 that converts the output voltage Vs of the solar battery 110 (power generation element) into a predetermined voltage and supplies power to the first storage battery 130 and the second storage battery 140, The DC / DC converter 120 controls the output voltage so that the charging voltage Va of the first storage battery 130 does not exceed a predetermined upper limit voltage (for example, 3.7 V).

In the power storage system 100 having such a configuration, the DC / DC converter 120 is connected to the output side of the solar cell 110 (power generation element). The DC / DC converter 120 converts the output voltage Vs of the solar battery 110 into a voltage corresponding to the power supply voltage supplied to the load device 200. The DC / DC converter 120 supplies power to the first storage battery 130 when the first switch unit 160 is in a closed state by the converted voltage. When the first switch unit 160 is in an open state, the DC / DC converter 120 Power is supplied to the series circuit with the two storage batteries 140. Further, the DC / DC converter 120 controls the output voltage so as not to exceed a predetermined upper limit voltage (for example, 3.7 V) so that the first storage battery 130 is not overcharged.
Thereby, the electrical storage system 100 can convert the output voltage Vs of the solar cell 110 (power generation element) into a voltage that allows the load device 200 to operate. Further, the DC / DC converter 120 can prevent the first storage battery 130 from being overcharged.

In the power storage system 100, a lithium ion capacitor is used as the large-capacity first storage battery 130.
In the power storage system 100 having such a configuration, the large-capacity first storage battery 130 needs to hold a charge for a long time. For this reason, a lithium ion capacitor with a small leakage current is used for the first storage battery 130.
Thereby, the 1st storage battery 130 can be hold | maintained for a long time, without consuming the electric power electrically fed from the solar cell 110 (power generation element) wastefully. For this reason, the power storage system 100 of the present invention increases the length of the load device 200 even when the solar cell 110 stops power generation or when the power generation amount of the solar cell 110 is smaller than the power consumption of the load device 200. Can be operated over time.

Second Embodiment
FIG. 12 is a configuration diagram illustrating a configuration example of the power storage system 100A according to the present embodiment. Compared with the power storage system 100 shown in FIG. 2, the power storage system 100A shown in FIG. 12 includes a point where a second switch unit 180 is newly added, a point where the switching unit 150 is changed to a switching unit 150A, and a load device. The difference is that 200 is changed to a load device 200A. Further, the load device 200A is different from the load device 200 in that the load device 200A is configured to start the operation as it is when supplied with a power supply voltage exceeding 2.5 V, which is an input power supply specification. Other configurations are the same as those of the power storage system 100 shown in FIG. For this reason, the same code | symbol is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

  In FIG. 12, the second switch unit 180 has one terminal a connected to the power supply line DCL1, and the other terminal b connected to the load device 200A via the power supply line DCL10. The second switch unit 180 connects or opens the power supply line DCL1 and the power supply line DCL10 by setting the ON state or the OFF state according to the instruction content of the control signal CNT2 input from the switching unit 150A. . That is, when the second switch unit 180 is turned on, the power supply line DCL1 and the power supply line DCL10 are connected, and power is supplied from the power storage system 100A to the load device 200A.

  The switching unit 150A includes a comparison unit 151A. In the comparison unit 151A, the voltage Va of the first storage battery 130 is 2.5 V (the first threshold voltage) or less when the first switch unit 160 is ON. In this case, the first storage battery 130 and the second storage battery 140 are connected in series by outputting the control signal CNT1 to the first switch section 160 and turning off the first switch section 160. Thereby, power storage system 100A shifts to a state where power supply from the first storage battery is stopped.

  The switching unit 150A compares the voltage detection signal Vf with a predetermined reference voltage Ref3 to determine whether or not the voltage Va of the first storage battery 130 exceeds a predetermined third threshold voltage. Note that the third threshold voltage may be a voltage of 2.5 V or more and 2.7 V (second threshold voltage) or less, for example, the first threshold voltage. The voltage may be the same as 5 V, or may be 2.55 V, 2.6 V, or a voltage higher than the first threshold voltage of 2.5 V.

When the voltage Va of the first storage battery 130 is equal to or lower than the third threshold voltage, the switching unit 150A outputs the control signal CNT2 to the second switch unit 180 and sets the second switch unit 180 to the OFF state. Then, the supply of power to the load device 200A is stopped. In addition, when the voltage Va of the first storage battery 130 exceeds the third threshold voltage, the switching unit 150A outputs the control signal CNT2 to the second switch unit 180 and turns on the second switch unit 180. Thus, power is supplied to the load device 200A.
Thereby, in power storage system 100A, power can be supplied to load device 200A only when charging voltage Va of first storage battery 130 exceeds the voltage of the third threshold.

  In addition, the comparison unit 151A sets the first switch unit 160 to the ON state when the voltage Vb of the second storage battery 140 becomes 2.7 V or more in the state where the first switch unit 160 is OFF. Both ends of 140 are short-circuited, and the first storage battery 130 is directly connected to the feeder line DCL1. Thereby, power storage system 100A returns to the normal state from the power supply stop state from the first storage battery.

  Thus, in the power storage system 100A, the load device 200A does not need to determine the magnitude of the power supply voltage supplied from the power supply line DCL1, and the second switch unit 180 is turned on, and the power storage system 100A. When the power supply voltage is supplied from, the operation can be started immediately.

  In the power storage system 100A, the first switch unit 160 and the second switch unit 180 are turned on at the same timing by setting the third threshold voltage to 2.5 V (the same voltage as the first threshold voltage). Can be turned off. That is, when the first switch unit 160 is in the ON state, the second switch unit 180 is in the ON state, and when the first switch unit 160 is in the OFF state, the second switch unit 180 is in the OFF state.

  FIG. 13 is a first flowchart showing a processing procedure in the power storage system 100A according to the present embodiment. FIG. 13 is a flowchart showing an operation flow in the above-described power storage system 100A. Hereinafter, the flow of the processing will be described with reference to FIG.

  First, it is assumed that the power storage system 100A is operating in a normal state (step S200). That is, in the power storage system 100A, the first switch unit 160 is in the ON state, the voltage Va of the first storage battery 130 exceeds 2.5V, the second switch unit 180 is in the ON state, and the load device 200A operates. Suppose that it is inside.

Subsequently, the voltage detection unit 170 detects the voltage of the power supply line DCL1 (in this case, the voltage Va of the first storage battery 130), and outputs the voltage detection signal Vf to the switching unit 150A (step S205).
Subsequently, the switching unit 150A determines whether or not the voltage Va of the first storage battery 130 exceeds the third threshold voltage by comparing the voltage detection signal Vf with a predetermined reference voltage Ref3 (step S210). .

  In step S210, when it is determined that the voltage Va of the first storage battery 130 exceeds the third threshold voltage (step S210: Yes), the switching unit 150A is in the case where the second switch unit 180 is in the OFF state. Is switched to the ON state, and in the ON state, the ON state is continued as it is (step S215). Thereby, power storage system 100A supplies power to load device 200A to operate load device 200A (step S220). Subsequently, the power storage system 100A proceeds to the process of step S240.

  On the other hand, when it is determined in step S210 that the voltage Va of the first storage battery 130 does not exceed the voltage of the third threshold (step S210: No), the switching unit 150A is in the case where the second switch unit 180 is in the ON state. Is switched to the OFF state, and in the OFF state, the OFF state is continued as it is (step S225). Thereby, power storage system 100A stops the supply of electric power to load device 200A, and stops the operation of load device 200A (step S230). Subsequently, the power storage system 100A proceeds to the process of step S240.

  Subsequently, the switching unit 150A determines whether or not the voltage Va of the first storage battery 130 exceeds 2.5V (first threshold voltage) by comparing the voltage detection signal Vf with a predetermined reference voltage Ref1. (Step S240).

If it is determined in step S240 that the voltage Va of the first storage battery 130 exceeds 2.5 V (first threshold voltage) (step S240: Yes), the process returns to step S205, and the storage system 100A Repeats the processes in and after step S205.
On the other hand, when it is determined in step S240 that the voltage Va of the first storage battery 130 does not exceed 2.5V (first threshold voltage) (step S240: No), that is, the voltage of the first storage battery 130 is 2. When the voltage is less than or equal to 5 V, the switching unit 150A switches the first switch unit 160 from the ON state to the OFF state (step S250). Thereby, power storage system 100A shifts to a state where power supply from the first storage battery is stopped, and first storage battery 130 and second storage battery 140 are connected in series. Then, when the solar cell 110 generates power, the second storage battery 140 is charged from the solar cell 110 (step S260).

  Subsequently, the voltage detection unit 170 detects the voltage of the power supply line DCL1 (in this case, the voltage Vb of the second storage battery 140), and outputs the voltage detection signal Vf to the switching unit 150A (step S270). The switching unit 150A determines whether or not the voltage Vb of the second storage battery 140 is equal to or higher than 2.7 V (second threshold voltage) by comparing the voltage detection signal Vf with a predetermined reference voltage Ref2 (Step S1). S280).

  And when it determines with the voltage Vb of the 2nd storage battery 140 not being 2.7 V or more in step S280 (step S280: No), it returns to the process of step S250 and the switching part 150A turns OFF the 1st switch part 160. The state is maintained as it is (step S250), and then the power storage system 100A repeatedly executes the processes after step S260.

  When the switching unit 150A determines that the voltage Vb of the second storage battery 140 is equal to or higher than 2.7 V (second threshold voltage) (step S280: Yes), the switching unit 150A includes the first switch unit 160. Is switched from the OFF state to the ON state (step S290). Subsequently, the power storage system 100A returns to the process of step S100, and executes the processes after step S205 again.

  Through the above processing flow, the power storage system 100A can quickly load the load device 200 when the solar cell 110 generates power after the operation of the load device 200A temporarily stops due to the decrease in the charging voltage Va of the first storage battery 130. The operation of 200A can be restored. Also, the power storage system 100A can supply power to the load device 200A only when the voltage exceeding the third threshold voltage at which the load device 200A can operate can be supplied.

FIG. 14 is a second flowchart showing a processing procedure in the power storage system 100A according to the present embodiment. FIG. 14 is an example in the case where the third threshold voltage and the first threshold voltage are set to the same voltage of 2.5 V in the power storage system 100A.
Compared with the flowchart shown in FIG. 13, the flowchart shown in FIG. 14 is different from FIG. 13 in processing steps S210A to 230A surrounded by a broken line in FIG. Other processing steps are the same as those in the flowchart shown in FIG. For this reason, the same code | symbol is attached | subjected to the step of the same processing content, and the overlapping description is abbreviate | omitted.

Referring to FIG. 14, in step S205, voltage detection unit 170 detects the voltage of power supply line DCL1 (in this case, voltage Va of first storage battery 130), and outputs voltage detection signal Vf to switching unit 150A. .
Subsequently, the switching unit 150A determines whether or not the voltage Va of the first storage battery 130 exceeds 2.5 V (the voltage of the third threshold and the first threshold) (step S210A).

In step S210A, when it is determined that the voltage Va of the first storage battery 130 exceeds 2.5 V (step S210A: Yes), the switching unit 150A is ON when the second switch unit 180 is in the OFF state. In the ON state, the ON state is continued as it is (step S215A). Thereby, power storage system 100A supplies power to load device 200A to operate load device 200A (step S220A). Subsequently, the power storage system 100A returns to the process of step S205, and repeatedly executes the processes of step S210A and the subsequent steps.
On the other hand, when it is determined in step S210A that the voltage Va of the first storage battery 130 does not exceed 2.5V (step S210A: No), that is, the charging voltage Va of the first storage battery 130 is 2.5V or less. The switching unit 150A turns off the second switch unit 180 (step S225A). Thereby, power storage system 100A stops the supply of electric power to load device 200A and stops the operation of load device 200A (step S230A). Subsequently, the switching unit 150A proceeds to the process of step S250. The subsequent processing after step S250 is the same as the processing shown in FIG.

  As described above, in the power storage system 100A, by setting the third threshold voltage to 2.5 V (the same voltage as the first threshold voltage), the first switch unit 160 and the second switch unit 180 have the same timing. Can be turned on and off. That is, when the first switch unit 160 is in the ON state, the second switch unit 180 can be in the ON state, and when the first switch unit 160 is in the OFF state, the second switch unit 180 can be in the OFF state. For this reason, compared with the case of FIG. 13, the control in the switching unit 150A is simplified.

  As described above, the power storage system 100A further includes the second switch unit 180 that connects or opens the power storage system 100A and the load device 200A, and the switching unit 150A determines the charging voltage Va of the first storage battery 130 as follows. When the charging voltage Va of the first storage battery 130 exceeds the third threshold voltage as compared to the third threshold voltage which is 2.5 V (first threshold voltage) or higher, the second switch unit 180 is connected. When the charging voltage Va of the first storage battery 130 is equal to or lower than the third threshold voltage, the second switch unit 180 is opened.

In the power storage system 100A having such a configuration, the switching unit 150A has a state in which the charging voltage Va of the first storage battery 130 exceeds the third threshold voltage and can supply necessary power from the first storage battery 130 to the load device 200A. In this case, the second switch unit 180 is connected to supply power to the load device 200A. On the other hand, when the charging voltage Va of the first storage battery 130 is equal to or lower than the third threshold voltage and the necessary power cannot be supplied from the first storage battery 130 to the load device 200A, the switching unit 150A is switched to the second switch unit 180. Is opened, and the supply of power to the load device 200A is stopped.
As a result, when the power storage system 100A cannot supply the necessary power to the load device 200A, the power storage system 100A stops the supply of power to the load device 200A by opening the second switch unit 180 and is necessary for the load device 200A. In a state where a large amount of power can be supplied, the power can be supplied to the load device 200A with the second switch unit 180 connected.

  In the power storage system 100A, the voltage of the third threshold is set to 2.5 V (the same voltage as the voltage of the first threshold), and the switching unit 150A closes the first switch unit 160 and sets the second storage battery. When both ends of 140 are short-circuited, the second switch unit 180 is connected, and the first switch unit 160 is opened and both ends of the second storage battery 140 are released from the short-circuited state. Leave it open.

In the power storage system 100A having such a configuration, the switching unit 150A is necessary for the load device 200A from the first storage battery 130 in a state where the first switch unit 160 is closed and both ends of the second storage battery 140 are short-circuited. In a state where a large amount of power can be supplied, the second switch unit 180 is connected to supply power to the load device 200A. In addition, the switching unit 150A opens the first switch unit 160 and opens both ends of the second storage battery 140 from the short-circuited state, that is, from the solar battery 110 (power generation element) to the first storage battery 130 and the second storage battery 150A. When charging the series circuit with the storage battery 140, the second switch unit 180 is opened.
Accordingly, the power storage system 100A places the second switch unit 180 in the connected state when the first switch unit 160 is in the closed state, and opens the second switch unit 180 when the first switch unit 160 is in the open state. Can be. That is, the power storage system 100A can control the open / close state of the first switch unit 160 and the open / close state of the second switch unit 180 at the same timing.

As mentioned above, although this invention was demonstrated, the electrical storage system of this invention is not limited only to the above-mentioned illustration example, Of course, in the range which does not deviate from the summary of this invention, a various change can be added.
For example, in the example illustrated in FIGS. 2 and 12, the example of the solar cell 110 using the environmental power generation element as the power generation element is illustrated, but the present invention is not limited thereto. The power generation element may be any power generation element that can perform environmental power generation. Here, energy harvesting other than light is, for example, power generation by heat, vibration, wind power, radio waves, and the like.

In the example of the load device 200 illustrated in FIG. 2, the environment monitor device 210 includes the temperature sensor 211 and the humidity sensor 212, but the environment monitor device 210 includes the temperature sensor 211 and the humidity sensor 212. Any one sensor may be provided. In addition, the environment monitoring device 210 may include a sensor that detects information related to other environments. Examples of other environmental information include illuminance, CO ₂ concentration, vibration, water level, voltage, current, sound, and image.
The power storage systems 100 and 100A can be used as a power source for opening and closing a door and a power source for an electrical switch. When the power storage system is used as a power source for opening and closing a door, the power consumption of the power source for opening and closing the door and the power source of the electric switch varies depending on the installation environment and usage conditions. Even if it hits, the balance of power generation and power consumption may be negative. In such a case, the power storage systems 100 and 100A can be suitably used.

100, 100A ... power storage system, 110 ... solar cell (power generation element),
120 ... DC / DC converter, 130 ... first storage battery, 140 ... second storage battery,
150, 150A ... switching unit, 151, 151A ... comparison unit,
160 ... 1st switch part, 170 ... Voltage detection part, 180 ... 2nd switch part,
200, 200A ... load device, 210 ... environmental monitoring device,
211 ... temperature sensor, 212 ... humidity sensor, 213 ... wireless communication unit

In order to achieve the above object, a power storage system according to one aspect of the present invention includes a power generation element that performs environmental power generation, a first storage battery that is supplied with power generated by the power generation element and that supplies power to a load device, and A second storage battery having a smaller capacity than the first storage battery and connected in series to the first storage battery, and connected in parallel to the second storage battery, short-circuiting both ends of the second storage battery in the closed state, and an open state A first switch unit that opens a short-circuit state of the second storage battery, and a switching unit that controls an open / closed state of the first switch unit. When both ends of the two storage batteries are short-circuited and power is supplied from the first storage battery to the load device via the first switch unit, the charging voltage of the first storage battery is compared with a predetermined first threshold voltage. And the first storage When the charging voltage of the battery becomes equal to or lower than the first threshold voltage, the first switch unit is controlled to be in an open state, and both ends of the second storage battery are opened from a short circuit state by the first switch unit. when the charge from the power generation element being in series circuit between the second battery and the first battery is made, whether or the second battery single charge voltage for detecting the charging voltage across the series circuit The charging voltage of the whole series circuit is obtained by detecting and summing the detected charging voltage and the charging voltage of the first storage battery, and the charging voltage of the whole series circuit is higher than the first threshold voltage. When the voltage exceeds a predetermined second threshold voltage, the first switch unit is controlled to be closed.

Further, in the power storage system according to one aspect of the present invention, the power storage system further includes a second switch unit that connects or opens the power storage system and the load device, and the switching unit is configured to supply a charging voltage of the first storage battery. When the charging voltage of the first storage battery exceeds the third threshold voltage when compared with the third threshold voltage that is equal to or higher than the first threshold voltage, the second switch unit is connected, When the charging voltage of the first storage battery is equal to or lower than the third threshold voltage, the second switch unit may be opened.

In order to achieve the above object, a power storage method according to an aspect of the present invention includes a power generation element that performs environmental power generation, a first storage battery that is fed with power generated by the power generation element and that supplies power to a load device, and A second storage battery having a smaller capacity than the first storage battery and connected in series to the first storage battery, and connected in parallel to the second storage battery, short-circuiting both ends of the second storage battery in the closed state, and an open state In this case, a power storage method in a power storage system comprising: a first switch unit that opens a short circuit state of the second storage battery; and a switching unit that controls an open / close state of the first switch unit, wherein the switching unit includes: When both ends of the second storage battery are short-circuited by the first switch unit and power is supplied from the first storage battery to the load device via the first switch unit, the charging voltage of the first storage battery is set to a predetermined value. of A step of controlling the first switch unit to be in an open state when a charging voltage of the first storage battery is equal to or lower than the voltage of the first threshold value compared to a voltage of one threshold value; In the case where both ends of the second storage battery are opened from the short-circuit state by the first switch unit, and the series circuit of the first storage battery and the second storage battery is charged from the power generation element, the entire series circuit obtains the charging voltage across said series circuit by summing charging voltage of or the second battery itself detects the charging voltage and the detected charging voltage the detected charging voltage of the first battery and the said series circuit Controlling the first switch unit to be closed when the overall charging voltage is equal to or higher than a predetermined second threshold voltage that is higher than the first threshold voltage. Including.
Thus, in the power storage system, when the power generation element generates power, the operation of the load device can be restored in a short time.

Claims (8)

A power generation element that performs energy harvesting,
A first storage battery that is fed by the power generated by the power generation element and supplies power to the load device;
A second storage battery having a smaller capacity than the first storage battery and connected in series to the first storage battery;
A first switch connected to the second storage battery in parallel, short-circuits both ends of the second storage battery in a closed state, and opens a short-circuit state of the second storage battery in an open state;
A switching unit for controlling an open / close state of the first switch unit;
With
The switching unit is
When both ends of the second storage battery are short-circuited by the first switch unit and power is supplied from the first storage battery to the load device via the first switch unit, the charging voltage of the first storage battery is set to a predetermined value. And when the charging voltage of the first storage battery is equal to or lower than the first threshold voltage, the first switch unit is controlled to be in an open state.
When both ends of the second storage battery are opened from the short-circuit state by the first switch unit and the series circuit of the first storage battery and the second storage battery is charged from the power generation element, the entire series circuit is Alternatively, when the charging voltage of a predetermined portion is detected and the charging voltage of the entire series circuit becomes equal to or higher than a predetermined second threshold voltage that is higher than the first threshold voltage, the first switch The power storage system is characterized in that control is performed so as to close the unit. The capacity of the first storage battery is determined based on the amount of power generated by the power generation element, the average value of power consumption of the load device that supplies power from the first storage battery, and the power stored in the first storage battery. Set based on the continuous driving time,
The capacity of the second storage battery is the power generation amount after the operation of the load device is stopped due to a decrease in the power generation amount of the power generation element, the average power consumption of the load device, and the charge voltage of the first storage battery. The power storage system according to claim 1, wherein the power storage system is set based on a time until the element generates power and returns the operation of the load device. The power storage system according to claim 1 or 2, wherein the first storage battery is a capacitor of a type having a smaller leakage current than the second storage battery. A second switch for connecting or opening between the power storage system and the load device;
The switching unit is
When the charging voltage of the first storage battery exceeds the voltage of the third threshold by comparing the charging voltage of the first storage battery with the voltage of the third threshold that is equal to or higher than the voltage of the first threshold, the second 4. The switch according to claim 1, wherein the switch part is connected and the second switch part is opened when the charging voltage of the first storage battery is equal to or lower than the third threshold voltage. The electricity storage system according to claim 1. The third threshold voltage is set to the same voltage as the first threshold voltage;
The switching unit is
When the first switch unit is closed and both ends of the second storage battery are short-circuited, the second switch unit is connected,
5. The power storage system according to claim 4, wherein when the first switch unit is opened and both ends of the second storage battery are opened from a short-circuited state, the second switch unit is opened. A DC / DC converter that converts the output voltage of the power generation element into a predetermined voltage and supplies power to the first storage battery and the second storage battery;
The power storage according to any one of claims 1 to 5, wherein the DC / DC converter controls an output voltage so that a charging voltage of the first storage battery does not exceed a predetermined upper limit voltage. system. The power storage system according to any one of claims 1 to 6, wherein the first storage battery is a lithium ion capacitor. A power generation element that performs environmental power generation, a first storage battery that is supplied with power generated by the power generation element and that supplies power to a load device, and has a smaller capacity than the first storage battery and is connected in series to the first storage battery A first switch unit connected in parallel to the second storage battery, short-circuiting both ends of the second storage battery in a closed state, and opening a short-circuit state of the second storage battery in an open state; A power storage method in a power storage system comprising: a switching unit that controls an open / closed state of the first switch unit,
When the switching unit is short-circuited at both ends of the second storage battery by the first switch unit and is fed from the first storage battery to the load device via the first switch unit, the first storage battery Is compared with a predetermined first threshold voltage, and when the charging voltage of the first storage battery is equal to or lower than the first threshold voltage, the first switch unit is controlled to be in an open state. Steps,
When the switching unit is opened from the short-circuited state at both ends of the second storage battery by the first switch unit, and the series circuit of the first storage battery and the second storage battery is charged from the power generation element, Detecting a charging voltage of the entire series circuit or of a predetermined part, and controlling the first switch unit to be closed when the charging voltage is equal to or higher than a predetermined second threshold voltage; ,
A power storage method comprising:

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