JP2010098827A - Charge/discharge control method, charge/discharge controller, and self-supporting power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent overdischarge of a storage battery in a self-supporting power supply system. <P>SOLUTION: In the self-supporting power supply system, the overdischarge detection unit 51 of a controller 5 obtains the battery voltage of a nickel-hydrogen storage battery 2 and detects a state immediately before the nickel-hydrogen storage battery 2 is overdischarged. When it is detected by the overdischarge detection unit 51 that the storage battery is in a state immediately before overdischarge, a battery disconnection unit 52 controls a battery disconnection switch 7 to OFF state to disconnect the nickel-hydrogen storage battery 2 from the self-supporting power supply system. A generated power determination unit 53 determines whether or not the generated power of a PV panel 1 meets a predetermined condition. When it is determined by the generated power determination unit 53 that the predetermined condition has been met, a battery connection unit 54 controls the battery disconnection switch 7 to ON state to connect the nickel-hydrogen storage battery 2, disconnected by the battery disconnection unit 52, to the self-supporting power supply system. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charge / discharge control method, a charge / discharge controller, and a self-supporting power supply system.

  In recent years, a self-supporting power supply system having a solar battery and a storage battery has been used as a power supply in places where it is difficult to secure a power supply infrastructure such as a place where people cannot approach or a dangerous place. In general, a stand-alone power supply system supplies the generated power of a solar cell to a load during daytime when the amount of sunlight is high and charges the storage battery with surplus power, and discharges the storage battery during daytime or nighttime when the amount of sunlight is low. Supply to the load.

  For example, Patent Documents 1 and 2 disclose a solar cell system combined with a commercial power source. Further, for example, Patent Document 3 discloses a portable solar cell system that has internal and external storage batteries and prevents overdischarge of the internal battery by mainly discharging from the external battery.

JP 2006-340578 A JP 2006-339077 A JP 2006-296134 A

  By the way, in the above-described conventional technology, there has been a problem that overdischarge of the storage battery cannot be prevented in the self-supporting power supply system.

  As described above, the self-supporting power supply system supplies the discharge power of the storage battery to the load during the daytime or nighttime when the amount of sunlight is small. For this reason, the storage battery in the self-supporting power supply system may be overdischarged, and may be greatly damaged by the overdischarge. Since nickel-metal hydride storage batteries and the like are expensive batteries, it is strongly desired to prevent overdischarge. However, the solar cell system combined with a commercial power source as in Patent Documents 1 and 2 assumes overdischarge of the storage battery in the first place. It is not a thing. Moreover, the solar cell system which has a storage battery inside and outside like patent document 3 only assumes preventing the overdischarge of an internal battery.

  Therefore, the present invention has been made to solve the above-described problems of the prior art, and a charge / discharge control method, a charge / discharge controller, and a charge / discharge controller capable of preventing overdischarge of a storage battery in a self-supporting power supply system An object is to provide a self-supporting power supply system.

  In order to solve the above-described problems and achieve the object, charging / discharging control for controlling charging / discharging of the storage battery in a self-supporting power supply system having a solar battery and a storage battery that performs charging / discharging using generated power of the solar battery The method includes a detection step of detecting a state immediately before the storage battery is overdischarged. Moreover, when it is detected by the detection step that the state is immediately before, a disconnecting step of disconnecting the storage battery from the self-supporting power supply system is included. Further, the method includes a determination step of determining whether or not the generated power of the solar cell satisfies a predetermined condition. Moreover, when it determines with satisfy | filling predetermined conditions by the said determination step, the connection step which connects the said storage battery separated by the said isolation | separation step to the said self-supporting power supply system is included.

  It becomes possible to prevent overdischarge of the storage battery in the self-supporting power supply system.

  Exemplary embodiments of a charge / discharge control method, a charge / discharge controller, and a self-supporting power supply system according to the present invention will be described below in detail with reference to the accompanying drawings. Below, the outline | summary of the self-supporting power supply system which concerns on Example 1 is demonstrated first, and the structure and process sequence by the self-supporting power supply system which concern on Example 1 are demonstrated sequentially.

[Outline of Self-supporting Power Supply System According to Embodiment 1]
First, the outline of the self-supporting power supply system according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating the configuration of the self-supporting power supply system according to the first embodiment.

  As shown in FIG. 1, the self-supporting power supply system according to the first embodiment includes a PV panel 1 that performs photovoltaic power generation (Photo Voltaic), and a nickel-metal hydride storage battery 2 that performs charging and discharging using generated power of the PV panel 1. Have The nickel metal hydride storage battery 2 charges the generated power of the PV panel 1 and discharges the charged power to the load 4.

  Here, as shown in FIG. 1, the self-supporting power supply system according to the first embodiment includes a battery disconnecting switch 7. The battery disconnecting switch 7 is controlled by the controller 5 to disconnect or connect the nickel hydride storage battery 2 from the self-supporting power supply system.

  For example, it is assumed that the battery disconnect switch 7 is controlled to be turned on by the controller 5 and the nickel metal hydride storage battery 2 is connected to the self-supporting power system. Then, the electric power charged in the nickel-metal hydride storage battery 2 is discharged to the load 4 during daytime or nighttime when the amount of sunlight is small.

  At this time, the overdischarge detection part 51 of the controller 5 detects the state immediately before the nickel metal hydride storage battery 2 is overdischarged by detecting the battery voltage of the nickel hydride storage battery 2. For example, when the overdischarge detection unit 51 detects that the battery voltage of the nickel metal hydride storage battery 2 has fallen below a predetermined minimum voltage (for example, 10.0 V), it is in a state immediately before the nickel metal hydride storage battery 2 is overdischarged. Detect that.

  Subsequently, the battery disconnecting unit 52 controls the battery disconnecting switch 7 to be in an OFF state, thereby disconnecting the nickel hydride storage battery 2 from the self-supporting power supply system. Thus, the self-supporting power supply system according to the first embodiment can prevent the nickel metal hydride storage battery 2 from being overdischarged.

  Now, if the nickel metal hydride storage battery 2 is disconnected from the self-supporting power supply system, the self-supporting power supply system cannot operate as a power source. Therefore, the generated power determination unit 53 of the controller 5 determines whether or not the generated power of the PV panel 1 satisfies a predetermined condition. For example, the generated power determination unit 53 obtains a minimum charging current value corresponding to the battery temperature measured by the temperature sensor 8 and determines whether or not the generated power of the PV panel 1 satisfies the minimum charging current value.

  When the generated power determining unit 53 determines that the predetermined condition is satisfied, the battery connecting unit 54 is disconnected by the battery disconnecting unit 52 by controlling the battery disconnecting switch 7 to be in an ON state. The nickel metal hydride storage battery 2 is connected to a self-supporting power supply system. Thus, the self-supporting power supply system according to the first embodiment can automatically return the nickel-metal hydride storage battery 2 that has been disconnected to prevent overdischarge.

[Configuration of Self-supporting Power Supply System According to Embodiment 1]
Next, the configuration of the self-supporting power supply system according to the first embodiment will be described with reference to FIGS.

  As shown in FIG. 1, the self-supporting power supply system according to the first embodiment includes a PV panel 1, a nickel metal hydride storage battery 2, a controller 3, a load 4, a controller 5, a shunt resistor 6, and a battery disconnection. And a switch 7. In FIG. 1, a solid line indicates a power line, and a dotted line indicates a correspondence relationship of control by the controller 5.

  The PV panel 1 performs solar power generation. Specifically, the PV panel 1 is connected to the load 4 via the controller 3, and the generated power of the PV panel 1 is supplied to the load 4. The PV panel 1 is connected to the nickel metal hydride storage battery 2 via the controller 3, the battery disconnect switch 7 and the shunt resistor 6, and surplus power in the generated power of the PV panel 1 is charged to the nickel metal hydride storage battery 2. The

  The nickel metal hydride storage battery 2 charges the generated power of the PV panel 1 and discharges the charged power to the load 4. Specifically, the nickel metal hydride storage battery 2 is connected to the PV panel 1 via the shunt resistor 6, the battery disconnecting switch 7 and the controller 3, and charges surplus power in the generated power of the PV panel 1. The nickel metal hydride storage battery 2 is connected to the load 4 via the shunt resistor 6 and the battery disconnecting switch 7 and discharges the charged power to the load 4. For example, the power generated by the PV panel 1 is not sufficiently supplied to the load 4 during daytime or nighttime when the amount of sunlight is small due to the bad weather, and the power charged in the nickel metal hydride storage battery 2 is supplied to the load 4. become. As shown in FIG. 1, the battery voltage and battery temperature of the nickel-metal hydride storage battery 2 are acquired by the controller 5 and used for control by the controller 5.

  Here, the nickel metal hydride storage battery 2 in the first embodiment is disconnected from or connected to the self-supporting power supply system when the battery disconnect switch 7 is controlled by the controller 5. Specifically, the controller 5 detects the battery voltage of the nickel metal hydride storage battery 2 to detect the state immediately before the nickel metal hydride storage battery 2 is overdischarged, and controls the battery disconnect switch 7 to be in the OFF state. By doing so, the nickel-metal hydride storage battery 2 is disconnected from the self-supporting power supply system. Further, the controller 5 determines whether or not the generated power of the PV panel 1 satisfies the minimum charging current value according to the battery temperature, and controls the battery disconnect switch 7 to be in an ON state. The nickel metal hydride storage battery 2 separated by the unit 52 is connected to the self-supporting power supply system.

  For example, the nickel metal hydride storage battery 2 in Example 1 has ten battery cells with a rating of 95 Ah in series as shown in FIG. 2, and a temperature sensor 8 attached to the battery cell, and a temperature sensor 8. And a connector for taking out the power line, a cooling fan, and a storage box. In addition, FIG. 2 is a figure for demonstrating a nickel hydride storage battery.

  The controller 3 has an MPPT (Maximum Power Point Tracker) and a DC / DC converter, and controls the generated power of the PV panel 1. Specifically, the controller 3 is connected to the PV panel 1 and is driven by the generated power of the PV panel 1, and the generated power of the PV panel 1 is output at a maximum power point (MPP). The generated power of the PV panel 1 is controlled. The controller 3 is interposed between the PV panel 1 and the load 4 and controls the voltage so as to maintain a voltage range in which the load 4 is operated. The controller 3 is interposed between the PV panel 1 and the nickel hydride storage battery 2 and controls the voltage so as to maintain a voltage range for charging the nickel hydride storage battery 2.

  The load 4 is operated by the generated power of the PV panel 1 or the discharge of the nickel metal hydride storage battery 2. Specifically, the load 4 is connected to the PV panel 1 via the controller 3 and is operated by the generated power of the PV panel 1. The load 4 is connected to the nickel metal hydride storage battery 2 via the battery disconnect switch 7 and the shunt resistor 6, and operates by discharging the nickel metal hydride storage battery 2.

  For example, the load 4 is a monitoring monitor that continuously consumes power and operates, a wireless transmitter that operates and consumes power periodically (for example, at intervals of one minute), and the like.

  The controller 5 controls the self-supporting power supply system. Specifically, the controller 5 is connected to the PV panel 1 via the controller 3 and is driven by the generated power of the PV panel 1. Moreover, the controller 5 has the overdischarge detection part 51, the battery disconnection part 52, the generated electric power determination part 53, and the battery connection part 54, as shown in FIG.

  The overdischarge detector 51 detects a state immediately before the nickel metal hydride storage battery 2 is overdischarged. Specifically, when the overdischarge detection unit 51 is notified from the shunt resistor 6 that the power charged in the nickel hydride storage battery 2 is being discharged to the load 4, the battery voltage of the nickel hydride storage battery 2 is detected. To get. When the overdischarge detection unit 51 detects that the battery voltage of the nickel metal hydride storage battery 2 is lower than a predetermined minimum voltage (for example, 10.0 V), the overdischarge detection unit 51 notifies the battery disconnection unit 52 to that effect.

  Here, the overdischarge detection part 51 in Example 1 detects a battery voltage in steps before detecting that the battery voltage of the nickel-metal hydride storage battery 2 is lower than the minimum voltage. And the overdischarge detection part 51 controls according to the detected battery voltage so that the operation mode of the controller 3 of the self-supporting power supply system, the controller 5, or the load 4 may become an energy saving mode (henceforth, energy saving mode). .

  For example, the overdischarge detection unit 51 detects that the battery voltage of the nickel metal hydride storage battery 2 has become 11.5 V or less in a state where the power charged in the nickel metal hydride storage battery 2 is discharged to the load 4. Then, the overdischarge detection unit 51 controls the controller 3 and the controller 5 so that the controller 3 and the controller 5 enter the energy saving mode such as widening the time interval for executing the processing.

  Further, for example, the overdischarge detection unit 51 detects that the battery voltage of the nickel metal hydride storage battery 2 has become 11.0 V or less in a state where the power charged in the nickel metal hydride storage battery 2 is discharged to the load 4. . Then, the overdischarge detection unit 51 controls the load 4 so that the load 4 is in the energy saving mode. For example, the overdischarge detection unit 51 performs control so that the load 4 is in the energy saving mode, for example, the load 4 is dimmed if the light is illuminated and the transmission interval is widened if the wireless transmitter is used.

  The battery disconnecting unit 52 disconnects the nickel metal hydride storage battery 2 from the self-supporting power supply system. Specifically, when the battery disconnection unit 52 is notified by the overdischarge detection unit 51 that the battery voltage of the nickel-metal hydride storage battery 2 has fallen below a predetermined minimum voltage, the battery disconnection switch 7 is turned off. Control and shut down and restart the stand-alone power system.

  The generated power determination unit 53 determines whether or not surplus power among the generated power of the PV panel 1 satisfies a predetermined condition. Specifically, the generated power determination unit 53 periodically acquires the battery temperature measured by the temperature sensor 8 of the nickel metal hydride storage battery 2 from the temperature sensor 8, and among the generated power of the PV panel 1, the load 4 Surplus power other than the power supplied to the controller 3 is periodically acquired from the controller 3. And the generated electric power determination part 53 calculates | requires regularly the minimum charging current value according to the battery temperature measured by the temperature sensor 8, and regularly determines whether the surplus electric power of the PV panel 1 satisfy | fills the minimum charging current value. It is judged. Then, when the generated power determination unit 53 determines that the surplus power of the PV panel 1 satisfies the minimum charging current value, the generated power determination unit 53 notifies the battery connection unit 54 to that effect.

  Here, the predetermined conditions will be described with reference to FIGS. 3 is a diagram for explaining the relationship between the charging current and the capacity, FIG. 4 is a diagram for explaining the relationship between the battery temperature and the capacity, and FIG. 5 is a diagram illustrating the relationship between the battery temperature and the charging current. It is a figure for demonstrating the relationship of these.

  For example, an alkaline storage battery such as a nickel metal hydride storage battery or a nickel cadmium storage battery has a minimum charging current value corresponding to the battery temperature. FIG. 3 shows the experimental results when a nickel-metal hydride storage battery having 10 battery cells with a rating of 95 Ah in series is used, and shows the relationship between the charging current and the capacity at a battery temperature of 20 ° C. As shown in FIG. 3, when the charging current is about 1 to 2 A, it can be seen that the chargeable capacity is remarkably reduced.

  FIG. 4 shows experimental results when a similar nickel-metal hydride storage battery is used, and shows the relationship between battery temperature and capacity at a charging current of 1A. As shown in FIG. 4, when the battery temperature is as high as 45 ° C., it can be seen that the chargeable capacity is remarkably reduced.

  As shown in FIGS. 3 and 4, when the charging current is very small or the battery temperature is high, it is considered that the reaction in the storage battery is changed to heat instead of charging. In other words, charging when the charging current is very small or the battery temperature is high is thought to lead to deterioration of the storage battery and shorten its life, and is therefore desirably avoided.

  Therefore, the generated power determination unit 53 according to the first embodiment uses a minimum charging current value corresponding to the battery temperature as a condition for determining whether the generated power of the PV panel 1 satisfies a predetermined condition. That is, the generated power determination unit 53 obtains a minimum charging current value corresponding to the battery temperature measured by the temperature sensor 8, and the generated power of the PV panel 1 satisfies a predetermined condition on the condition of the obtained minimum charging current value. It is determined whether or not.

For example, the generated power determination unit 53 stores the following Table 1 as a condition for maintaining 90% as a chargeable capacity.

  Then, the generated power determination unit 53 refers to Table 1 using the battery temperature measured by the temperature sensor 8, and acquires the “minimum charging current value” associated with the “battery temperature”. Then, the generated power determination unit 53 sets the contents described in “Chargeability determination” in Table 1 as a predetermined condition. FIG. 5 shows the contents shown in Table 1 in relation to the battery temperature and the charging current. As shown in FIG. 5, when the battery temperature reaches 60 ° C. or higher, charging is prohibited (stopped).

  The battery connection unit 54 connects the nickel metal hydride storage battery 2 to the self-supporting power supply system. Specifically, when notified from the generated power determination unit 53 that the generated power of the PV panel 1 satisfies the minimum charging current value, the battery connection unit 54 controls the battery disconnect switch 7 to be in an ON state.

  The shunt resistor 6 monitors the discharge current discharged from the nickel metal hydride storage battery 2 toward the load 4. Specifically, the shunt resistor 6 is inserted between the nickel metal hydride storage battery 2 and the load 4, and the discharge current is measured by measuring the voltage generated at both ends of the shunt resistor 6. If a value occurs, it is considered a discharge. When the shunt resistor 6 detects that the power charged in the nickel metal hydride storage battery 2 is being discharged to the load 4, the shunt resistor 6 notifies the overdischarge detection unit 51 to that effect.

  The battery disconnection switch 7 disconnects or connects the nickel metal hydride storage battery 2 from the self-supporting power supply system. Specifically, the battery disconnect switch 7 is inserted between the nickel metal hydride storage battery 2 and the load 4 (PV panel 1), and is controlled to be in an OFF state by the battery disconnect unit 52, thereby The storage battery 2 is disconnected from the self-supporting power system. Further, the battery disconnecting switch 7 is controlled to be turned on by the battery connecting unit 54, thereby connecting the nickel-metal hydride storage battery 2 to the self-supporting power supply system.

[Processing Procedure by Self-supporting Power Supply System According to Embodiment 1]
Next, a processing procedure performed by the self-supporting power supply system according to the first embodiment will be described with reference to FIGS. 6 and 7. 6 and 7 are flowcharts illustrating a processing procedure performed by the self-supporting power supply system according to the first embodiment.

  Here, for example, the processing procedure shown in FIG. 6 is started (started) from the time of installation of the self-supporting power supply system, that is, the time before the system is started. Further, it is assumed that the battery disconnect switch 7 is controlled to be OFF at the time of installation, that is, the nickel-metal hydride storage battery 2 is disconnected from the self-supporting power supply system.

  Now, when the self-supporting power supply system is activated and sunlight is irradiated onto the PV panel 1, the PV panel 1 starts photovoltaic power generation (step S101). For example, when the amount of sunlight is large and the generated power of the PV panel 1 exceeds the driving power of the controller 3 (Yes in step S102), as in the case of sunny weather, the controller 3 is driven (step S103). On the other hand, for example, when the amount of sunlight is small and the generated power of the PV panel 1 is lower than the driving power of the controller 3 (No in step S102), such as in the case of rainy weather, the controller 3 cannot be driven and the PV panel 1 The system waits until the generated power exceeds the drive power of the controller 3.

  In step S103, the controller 3 is driven. Subsequently, when the output power of the controller 3 exceeds the drive power of the controller 5 (Yes in step S104), the controller 5 is driven (step S105). Here, while the controller 3 has an MPPT and a DC / DC converter, the controller 5 only has a microcomputer, and the power consumption of the controller 3 is overwhelmingly larger than the power consumption of the controller 5. it is conceivable that. If this is the case, if the PV panel 1 generates enough power to drive the controller 3, the controller 5 is likely to be driven. In such a case, the controller 3 and the controller 5 are likely to be driven. Can be driven simultaneously.

  On the other hand, for example, when the output power of the controller 3 is lower than the drive power of the controller 5 (No in step S104), the controller 5 cannot be driven until the output power of the controller 3 exceeds the drive power of the controller 5. I will wait.

  Next, when the controller 5 is driven, the controller 5 controls the controller 3 so that the controller 3 starts feeding to supply the generated power of the PV panel 1 to the load 4 (step S106). At this time, the controller 3 controls the generated power of the PV panel 1 so that the generated power of the PV panel 1 is output at the maximum power point, and also controls the voltage so as to maintain the voltage range for operating the load 4. Then, the generated power of the PV panel 1 is supplied to the load 4. Further, the controller 5 monitors the operation of the load 4.

  When sufficient power for operating the load 4 is output from the controller 3 (Yes in step S107), power supply from the controller 3 to the load 4 is continuously performed (step S111).

  On the other hand, if the controller 3 does not output enough power to operate the load 4, that is, if the power is insufficient, the controller 5 monitors the operation of the load 4, so Is detected (No at step S107).

  Then, the controller 5 controls the self-supporting power supply system so as to wait for a specified time (for example, 1 minute) (step S108). Here, the case where sufficient power for operating the load 4 is not output from the controller 3 is, for example, a case where it is not sunny, but the weather changes and there is a possibility that it will become sunny again. Yes. Therefore, the controller 5 in the first embodiment waits for a predetermined time before shutting down and restarting the stand-alone power supply system, and restarts the stand-alone power supply system when the weather does not change after the stand-by. The processing procedure from S101 is resumed.

  That is, after waiting for the specified time in step S108, the controller 5 confirms again whether or not the operation of the load 4 has been started (step S109). If the load 4 is still stopped (No at Step S109), the controller 5 restarts the self-supporting power supply system (Step S110) and returns to the process at Step S101. On the other hand, when the operation of the load 4 is started after waiting for a specified time (Yes at Step S109), the power supply from the controller 3 to the load 4 is continuously performed (Step S111). By setting the standby time, the number of startup operations of the self-supporting power supply system can be reduced, and the life can be extended.

  In step S111, when power is continuously supplied from the controller 3 to the load 4, the generated power determination unit 53 of the controller 5 determines that the generated power of the PV panel 1 has a minimum charging current value corresponding to the battery temperature. It is determined whether or not it is satisfied (step S112). In the first embodiment, the determination by the generated power determination unit 53 is performed periodically.

  Then, when notified from the generated power determination unit 53 that the generated power of the PV panel 1 satisfies the minimum charging current value (Yes in step S112), the battery connection unit 54 controls the battery disconnect switch 7 to be in an ON state. (Step S113). Thus, the nickel metal hydride storage battery 2 is connected to the self-supporting power supply system, and surplus power in the generated power of the PV panel 1 is charged to the nickel metal hydride storage battery 2.

  As shown in FIG. 7, the self-supporting power supply system is in operation (step S201). While the generated power of the PV panel 1 is sufficiently supplied to the load 4, the power charged in the nickel-metal hydride storage battery 2 is not discharged to the load 4, so the processing procedure shown in FIG. 7 is not started ( Step S202 negative). However, for example, when the amount of sunlight is small as in the case of cloudy weather and the generated power of the PV panel 1 is not sufficiently supplied to the load 4, the power charged in the nickel hydride storage battery 2 is discharged to the load 4. 7 is started (Yes at step S202). Note that the shunt resistor 6 notifies the overdischarge detection unit 51 that the power charged in the nickel metal hydride storage battery 2 is discharged to the load 4, so that the processing procedure after step S <b> 203 by the overdischarge detection unit 51 is performed. Be started.

  When the overdischarge detection unit 51 is notified from the shunt resistor 6 that the power charged in the nickel metal hydride storage battery 2 is discharged to the load 4 (Yes in step S202), the overdischarge detection unit 51 acquires the battery voltage of the nickel metal hydride storage battery 2. Then, it is determined whether or not the battery voltage of the nickel-metal hydride storage battery 2 has become a specified value (for example, 11.5 V) or less (step S203).

  When it is determined that the voltage is not lower than 11.5 V (No at Step S203), the overdischarge detection unit 51 keeps the operation mode of the load 4, the controller 3, and the controller 5 in the normal mode (Step S204). The process returns to step S202. In addition, when the operation mode of the controller 3 or the controller 5 is in the energy saving mode by the subsequent processing procedure, the overdischarge detection unit 51 sets the operation mode of the controller 3 or the controller 5 to the normal mode. Control (step S204).

  On the other hand, when it is determined that the voltage is 11.5 V or less (Yes at Step S203), the overdischarge detection unit 51 controls the controller 3 and the control so that the operation mode of the controller 3 and the controller 5 is in the energy saving mode. The device 5 is controlled (step S205).

  Subsequently, the overdischarge detection unit 51 determines whether or not the battery voltage of the nickel hydride storage battery 2 has become 11.0 V or less (step S206). If it is determined that the voltage is not lower than 11.0 V (No at Step S206), the overdischarge detection unit 51 returns to the process of Step S203 while keeping the operation mode of the load 4 in the normal mode (Step S207). When the operation mode of the load 4 is in the energy saving mode by the subsequent processing procedure, the overdischarge detection unit 51 controls the operation mode of the load 4 to be in the normal mode (step S207).

  On the other hand, when it is determined that the voltage is 11.0 V or less (Yes at Step S206), the overdischarge detection unit 51 controls the load 4 so that the operation mode of the load 4 is in the energy saving mode (Step S208). ).

  Next, the overdischarge detection unit 51 determines whether or not the battery voltage of the nickel-metal hydride storage battery 2 has become 10.0 V or less (step S209). When it is determined that the voltage is not 10.0 V or less (No at Step S209), the overdischarge detection unit 51 returns to the process at Step S206.

  On the other hand, when it is determined that the voltage is 10.0 V or less (Yes at Step S209), the battery disconnecting unit 52 controls the battery disconnecting switch 7 to be in an OFF state (Step S210). Thus, the nickel metal hydride storage battery 2 is disconnected from the self-supporting power supply system before being overdischarged. Thereafter, since the battery disconnecting unit 52 shuts down and restarts the self-supporting power supply system (step S211), the processing procedure of step S101 in FIG. 6 is resumed.

[Effect of Example 1]
As described above, in the self-supporting power supply system, the overdischarge detection unit 51 of the controller 5 acquires the battery voltage of the nickel metal hydride storage battery 2 and detects the state immediately before the nickel metal hydride storage battery 2 is overdischarged. When it is detected by the overdischarge detection unit 51 that the state is just before overdischarge, the battery disconnecting unit 52 controls the battery disconnecting switch 7 to be turned off, so that the nickel metal hydride storage battery 2 is removed from the self-supporting power supply system. Separate. Further, the generated power determination unit 53 determines whether or not the generated power of the PV panel 1 satisfies a predetermined condition. When the generated power determining unit 53 determines that the predetermined condition is satisfied, the battery connecting unit 54 controls the battery disconnecting switch 7 to be turned on so that the nickel metal hydride storage battery 2 disconnected by the battery disconnecting unit 52 is Connect to a stand-alone power system.

  For this reason, according to the self-supporting power supply system according to the first embodiment, it is possible to prevent the nickel metal hydride storage battery 2 from being overdischarged. Moreover, according to the self-supporting power supply system according to the first embodiment, it is possible to automatically return the nickel-metal hydride storage battery 2 that has been disconnected in order to prevent overdischarge.

  In addition, the overdischarge detection unit 51 in the first embodiment first switches the operation mode of a predetermined circuit element included in the self-supporting power supply system to the energy saving mode, and when the state immediately before the overdischarge is still not improved, The battery disconnecting unit 52 is notified that the previous state has been detected. In other words, the overdischarge detection unit 51 in the first embodiment first loads the load 4, the controller 3, the controller 5, etc. in a situation where overdischarge is not imminent before disconnecting the nickel metal hydride storage battery 2 from the self-supporting power supply system. Switch the operation mode of the circuit element to energy saving mode.

  For this reason, according to the self-supporting power supply system according to the first embodiment, it is possible to reduce power consumption as compared with a method in which no countermeasure is taken until a situation in which overdischarge is imminent.

  The self-supporting power supply system according to the first embodiment further includes a temperature sensor 8 that measures the temperature of the nickel metal hydride storage battery 2. The generated power determination unit 53 derives the minimum charging current value for charging the nickel metal hydride storage battery 2 from the temperature measured by the temperature sensor 8, and determines whether the generated power of the PV panel 1 satisfies the minimum charging current value. judge. Further, when the generated power determination unit 53 determines that the generated power of the PV panel 1 satisfies the minimum charging current value, the battery connecting unit 54 connects the nickel metal hydride storage battery 2 to the self-supporting power system.

  For this reason, according to the self-supporting power supply system according to the first embodiment, charging is not performed when the charging current is very small or when the battery temperature is high. It is also possible to extend the battery life.

[Other embodiments]
Although the first embodiment of the present invention has been described so far, the present invention may be implemented in various different forms other than the above-described embodiments.

[System configuration, etc.]
The processing procedures (such as FIGS. 6-7), specific names (such as FIGS. 1-2), and information including various data and parameters (such as FIGS. It can be changed arbitrarily except in some cases.

  Further, each circuit element of the self-supporting power supply system shown in FIGS. 1 and 2 does not necessarily need to be physically configured as illustrated. That is, the specific form of each circuit element is not limited to that shown in the figure, and for example, all or a part of the controller 5 can be distributed or integrated in arbitrary units.

  The charge / discharge control method described in the above embodiments can be distributed as a program executed by a microcomputer via a network such as the Internet. The program can also be executed by being recorded on a recording medium readable by a microcomputer and being read from the recording medium by the microcomputer.

  As described above, the charge / discharge control method, the charge / discharge controller and the self-supporting power supply system according to the present invention are useful for controlling the charge / discharge of the storage battery in the self-supporting power supply system having the solar battery and the storage battery, In particular, it is suitable for preventing overdischarge of the storage battery.

1 is a block diagram illustrating a configuration of a self-supporting power supply system according to Embodiment 1. FIG. It is a figure for demonstrating a nickel hydride storage battery. It is a figure for demonstrating the relationship between a charging current and a capacity | capacitance. It is a figure for demonstrating the relationship between battery temperature and a capacity | capacitance. It is a figure for demonstrating the relationship between battery temperature and charging current. 3 is a flowchart illustrating a processing procedure by the self-supporting power supply system according to the first embodiment. 3 is a flowchart illustrating a processing procedure by the self-supporting power supply system according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PV panel 2 Nickel metal hydride storage battery 3 Controller 4 Load 5 Controller 51 Overdischarge detection part 52 Battery disconnection part 53 Generated electric power determination part 54 Battery connection part 6 Shunt resistance 7 Battery disconnection switch 8 Temperature sensor

Claims (5)

In a self-supporting power supply system having a solar battery and a storage battery that charges and discharges using the generated power of the solar battery, a charge / discharge control method for controlling charge / discharge of the storage battery,
A detection step of detecting a state immediately before the storage battery is overdischarged;
A disconnecting step of disconnecting the storage battery from the self-contained power supply system when it is detected by the detecting step that the state is immediately before;
A determination step of determining whether the generated power of the solar cell satisfies a predetermined condition;
When it is determined that a predetermined condition is satisfied by the determination step, a connection step of connecting the storage battery disconnected by the disconnection step to the self-supporting power supply system;
A charge / discharge control method comprising:   In the disconnecting step, when it is detected by the detecting step that the state is immediately before, the operation mode of a predetermined circuit element included in the self-supporting power supply system is first switched to an energy saving mode, and then the storage battery is connected to the self-supporting device. The charge / discharge control method according to claim 1, wherein the charge / discharge control method is separated from the mold power supply system. It further comprises a measuring step for measuring the temperature of the storage battery,
The determination step derives a minimum charge current value when charging the storage battery from the temperature measured in the measurement step, determines whether or not the generated power of the solar cell satisfies the minimum charge current value,
The said connection step connects the said storage battery to the said self-supporting power supply system, when it determines with the generation | occurrence | production electric power of the said solar cell satisfy | filling the minimum charging current value by the said determination step. The charge / discharge control method as described. In a self-supporting power supply system having a solar battery and a storage battery that charges and discharges using generated power of the solar battery, a charge / discharge controller that controls the charge / discharge of the storage battery,
A detection unit for detecting a state immediately before the storage battery is overdischarged;
When the detection unit detects that the state is immediately before, a disconnecting unit that disconnects the storage battery from the self-supporting power supply system;
A determination unit that determines whether or not the generated power of the solar cell satisfies a predetermined condition;
When the determination unit determines that a predetermined condition is satisfied, a connection unit that connects the storage battery separated by the separation unit to the self-supporting power supply system;
A charge / discharge controller comprising: A self-supporting power supply system having a solar cell and a storage battery that charges and discharges using generated power of the solar cell,
The solar cell;
The storage battery;
A detection unit for detecting whether or not the storage battery is in a state immediately before being overdischarged,
When it is detected by the detection unit that the state is immediately before, a disconnecting unit that disconnects the storage battery from the self-supporting power supply system;
A determination unit that determines whether or not the generated power of the solar cell satisfies a predetermined condition;
When the determination unit determines that a predetermined condition is satisfied, a connection unit that connects the storage battery separated by the separation unit to the self-supporting power supply system;
A self-supporting power supply system characterized by comprising:

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