JP2014209827A - Independent power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an independent power supply using a solar cell capable of solving a problem in conventional secondary batteries which are repeatedly used from a full-charged state to a point immediately before the charged electric quantity runs out resulting in unsatisfactory service life by means of a float charging.SOLUTION: The independent power supply sequentially calculates the current amount flowing in/out a secondary battery. After charging the secondary battery to a certain level in a manner of bulk charge, the charging is continued up so as to replenish the discharged electric quantity. After the discharged electric quantity becomes equal to the charged electric quantity, the charging mode enters into a zero-charge mode to stop the charging. Also, the charging is continued exceeding the rated capacity once every 5-6 days, and the electric quantity value of charge and discharge is reset. Thereby the electric quantity accumulated in the secondary battery can be precisely obtained, even when the charge from full-charge to a point immediately before run-out is made repeatedly, satisfactory service life of the secondary battery is ensured.

Description

  The present invention relates to an independent power supply device combining a solar cell module and a secondary battery.

  A solar cell is a battery that generates power using sunlight. Because it uses sunlight, which can be said to be inexhaustible, it is attracting attention as a clean and safe energy. However, there was a problem that power generation could not be performed during the time when there was no sunlight at night. Therefore, an independent power source that stores the electricity generated by the solar cell in a secondary battery, uses the electricity generated by sunlight during the daytime, and supplies the secondary battery electricity that was charged during the daytime to the load. An apparatus has been proposed (Patent Document 1).

  Moreover, regarding the charging method of the secondary battery, methods such as trickle charging and float charging have been proposed (Patent Document 2). Here, trickle charging refers to a method of continuing charging with a minute current so as to charge only the self-discharge of the secondary battery. In this charging method, although it takes time to recharge the largely discharged power, it is not necessary to worry about overcharging.

  On the other hand, the float charging is a method of reducing a burden on the secondary battery by flowing current to another (load or the like) by a bypass circuit after charging until the battery is fully charged. Since the voltage remains applied to the secondary battery, power is supplied to the load while charging. In order to charge by such a method, it is said that float charging can make a secondary battery last longer.

Japanese Patent Laid-Open No. 05-074499 Japanese Patent Laid-Open No. 08-017473

  The independent power supply device using a solar cell outputs power from the solar cell module to a load. Therefore, when the night solar cell module does not generate power, the power of the secondary battery is supplied to the load. That is, in an independent power supply device using a solar battery, it can be said that the secondary battery repeatedly discharges and charges at night and daytime, and thus has a heavy burden.

  When charging such a secondary battery, bulk charging for charging the discharged power up to a predetermined voltage at maximum power, absorption charging for performing constant voltage charging for a predetermined time to prevent overcharging, and then self-discharge Float charging is performed to charge and supply power to the load with a voltage that compensates for the amount.

  However, although float charging is effective in extending the life of secondary batteries that are always used in a state close to full charge, the independent power supply using solar cells depletes the stored power from full charge. Since the period until immediately before is repeated every day, there is a problem that the life of the secondary battery cannot be extended as is usually said.

  The present invention has been conceived in view of the above problems. The inventor of the present invention, in a secondary battery that repeats a full charge and a large amount of power discharge, to zero charge after the bulk charge and constant voltage charge, to extend the battery life. It has been found through experiments that it is effective and has been completed.

More specifically, the independent power supply device of the present invention is:
A solar cell module that generates power with solar energy;
An independent power supply that supplies generated power generated by the solar cell module to a load, charges surplus power to a secondary battery, and supplies insufficient power from the secondary battery to the load when the generated power is insufficient Because
Charge / discharge control means for controlling a charge amount of the power generated by the solar cell module to the secondary battery and a power supply amount to the load;
A voltage sensor for measuring the voltage of the secondary battery;
A charge / discharge current sensor for measuring a charge current to the secondary battery and a discharge current from the secondary battery;
Charging / discharging electric quantity which calculates the charging / discharging electric quantity which is the sum total of the charging electric quantity to the said secondary battery, and the discharging electric quantity from the said secondary battery based on the measured value from the said voltage sensor and the said charging / discharging current sensor Having an arithmetic means;
When the charge / discharge control means charges the secondary battery,
After the voltage of the secondary battery reaches a constant voltage setting value (V2), the charging voltage of the secondary battery is maintained at the constant voltage setting value (V2) until the charge / discharge electricity amount reaches zero from a negative value. It is characterized by.

Moreover, in the independent power supply device according to the present invention,
The charge / discharge control means uses the generated power only for power supply to the load when the secondary battery is charged until the charge / discharge electricity amount reaches zero from a negative value.

Moreover, in the independent power supply device according to the present invention,
The charge / discharge control means performs charging until the charge / discharge electricity amount becomes equal to or greater than a preset value every predetermined period, and resets the value of the charge / discharge electricity amount.

Moreover, in the independent power supply device according to the present invention,
When the time interval between the time when the secondary battery voltage reaches the constant voltage set value (V2) and the time when the charge / discharge electric quantity reaches zero is less than or equal to a predetermined time, the charge / discharge control means In addition, charging is performed until the charge / discharge electricity amount is equal to or higher than a preset value.

The independent power supply device according to the present invention is
The charge / discharge control means charges the shortage on the next day if the charge / discharge control unit becomes unable to charge before the charge / discharge electricity amount becomes equal to or greater than the preset value.

  The independent power supply according to the present invention records the amount of charge / discharge electricity used from the fully charged state of the secondary battery to be used, and when charging, the amount of electricity to be charged and the amount of charge / discharge electricity used It was decided to charge at a constant voltage until. Therefore, there is no possibility of overcharging.

  In addition, after charging the discharged amount of electricity, the zero charge mode is entered in which no charging is performed. Therefore, even if it is the secondary battery of the independent power supply device using a solar cell module which repeats full charge and a large amount of discharge, the lifetime of a secondary battery can be extended.

  In addition, the life can be further extended by overcharging more than the rated capacity at a predetermined number of times (every 5 to 6 times, that is, once every 5 to 6 days) in the charge / discharge cycle. At this time, since the calculated charge / discharge electricity amount is reset, it is possible to correct the difference between the charge / discharge electricity amount that causes an error and the amount of electricity accumulated in the actual secondary battery due to the charge loss. it can. As a result, the battery can be used while correctly grasping the remaining amount of electricity.

  Further, the charge / discharge control means is configured such that when the time interval between the time when the secondary battery voltage reaches the constant voltage set value and the time when the charge / discharge electricity amount reaches zero becomes a predetermined time or less. The charging is performed until the amount of charge / discharge electricity is equal to or greater than a preset value. Such an independent power supply device can extend the battery life without considering the history of the secondary battery used.

  Furthermore, if overcharge at a given time is not possible to charge up to the target charge / discharge electricity amount on the day of overcharge, the overcharge amount is charged by charging the insufficient overcharge amount the next day. Is maintained.

It is a figure which shows the structure of the independent power supply device which concerns on this invention. It is a figure which shows the detailed structure of a charging / discharging control means. It is a figure which shows the flow of a charging / discharging electric quantity calculating means. It is the graph which showed the charging process of the independent power supply device which concerns on this invention on the time-axis. It is a figure which shows the flow of a charging process. It is a graph which shows transition of charging / discharging electric energy (FIG. 6 (a)) in the case of overcharging every predetermined day, and actual battery capacity (FIG. 6 (b)). It is a graph which shows the judgment phenomenon when the other independent power supply device which concerns on Embodiment 2 performs an overcharge process. FIG. 10 is a diagram illustrating a processing flow of the independent power supply device according to the second embodiment. It is a figure which shows the flow which explained a part of flow of FIG. 8 in detail. It is a figure which shows the charge behavior which the independent power supply which concerns on Embodiment 3 performs an overcharge process over several days. FIG. 10 is a diagram illustrating a processing flow of the independent power supply device according to the third embodiment. It is a figure which shows the partial detailed flow of FIG. It is a figure which shows the structure of the independent power supply device which concerns on Embodiment 4. FIG. It is a figure which shows the detailed structure of the charging / discharging control means of FIG. It is a figure which shows the case where a battery capacity does not return even if a secondary battery deteriorates and performs an overcharge process. FIG. 10 is a diagram illustrating a processing flow of the independent power supply device according to the fourth embodiment. It is a graph which shows the relationship between an open terminal voltage and battery capacity.

  Hereinafter, an independent power supply apparatus according to the present invention will be described with reference to the drawings. The following description exemplifies some embodiments of the present invention, and the present invention is not limited to the following description. The following embodiments can be modified without departing from the spirit of the present invention.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of an independent power supply device 1 according to the present invention. The independent power supply device 1 of the present invention includes a solar cell module 10, a secondary battery 12, charge / discharge control means 11, a voltage sensor 13, a charge / discharge current sensor 14, and an output terminal 15. The solar cell module 10 is connected to the charge / discharge control means 11 by the wiring L1. The charge / discharge control means 11 is connected to the secondary battery 12 via a wiring L2, and is connected to the output terminal 15 via a wiring L3. The output terminal 15 is connected to the load 19 through the wiring L4. These wirings are indicated by bold lines in FIG. A current supplied to the load 19 or charged to the secondary battery 12 flows through the wirings L1 to L4.

  The solar cell module 10 is a device that extracts electricity from solar rays by the photovoltaic effect, and is not particularly limited to silicon, a compound semiconductor, and a dye-sensitized type. The secondary battery 12 is not particularly limited as long as it is a secondary battery such as a lead battery, nickel metal hydride, or lithium ion, but a lead battery can be preferably used.

  The voltage sensor 13 is not particularly limited as long as it detects the voltage of the secondary battery 12. The voltage sensor 13 is connected to the charge / discharge control means 11 by a signal line SL1. The voltage sensor 13 transmits the measured voltage value SV to the charge / discharge control means 11 through the signal line SL1.

  The charge / discharge current sensor 14 is a current sensor that can determine whether the current flowing is a current for charging (charging current) or a discharging current (discharge current). The charge / discharge current sensor 14 is connected to the charge / discharge control means 11 by a signal line SL2. The charge / discharge current sensor 14 transmits the measured current value SA to the charge / discharge control means 11 through the signal line SL2.

  Based on the output (SA) of the charge / discharge current sensor 14, the charge / discharge control means 11 calculates an amount of electricity such as a charge / discharge amount ΣC described later. The charge / discharge control means 11 can be realized by, for example, a combination computer such as an MPU (Micro Processor Unit) and a memory.

  Moreover, the solar cell module 10 has an electromotive force monitor 16, and is connected to the charge / discharge control means 11 by a signal line SL3. The electromotive force monitor 16 can send out the current electromotive force value SPv of the solar cell module 10 as an output. The electromotive force monitor 16 may not be incorporated in the solar cell module 10. This is because the charge / discharge control means 11 only needs to be able to know the electromotive force of the solar cell module 10 and may be a voltmeter disposed between the solar cell module 10 and the charge / discharge control means 11.

  FIG. 2 shows a detailed view of the charge / discharge control means 11. The charge / discharge control means 11 includes at least a control unit (MPU) 20, a memory 24, a power control unit 22, and a timer 25. The control device 20 is connected to the memory 24, the electromotive force monitor 16 of the solar cell module 10, the power control unit 22, the charge / discharge current sensor 14, the voltage sensor 13, and the timer 25.

  The power control unit 22 is connected to the solar cell module 10, the secondary battery 12, and the output terminal 15 through wirings L1 to L3. A load 19 is connected to the output terminal 15 (see FIG. 1).

  The electric power control part 22 adjusts the electric power supplied to the secondary battery 12 and the output terminal 15 (load 19) among the electric power generated in the solar cell module 10. In addition, it has voltage conversion means (not shown) such as a DC-DC converter inside, and the charging voltage to the secondary battery 12, the supply voltage to the output terminal 15 (load 19), etc. Can be output as a value. Further, at night when the solar cell module 10 does not generate electricity, control is performed to supply the amount of electricity stored in the secondary battery 12 to the output terminal 15 (load 19), and the current from the secondary battery 12 is transferred to other than the output terminal 15. Has a circuit or the like for preventing flow. Note that these functions of the power control unit 22 are activated, changed, or stopped by an instruction Cov from the control device 20.

  Next, functions of the charge / discharge control means 11 will be described. At least the charge / discharge control means 11 according to the present invention realizes the function of charge / discharge electricity quantity calculation means. The charge / discharge electricity amount calculating means calculates a charge / discharge electricity amount ΣC, which is the sum of the amount of electricity charged to the secondary battery 12 and the amount of electricity discharged from the secondary battery 12. As described above, the independent power supply device 1 according to the present invention manages the electricity stored in the secondary battery 12 by converting it into the amount of electricity (Ah).

  The charge / discharge control means 11 realizes charge / discharge electricity calculation means for calculating the charge / discharge electricity ΣC from the signal (SA) from the charge / discharge current sensor 14. This is calculated | required when the control apparatus 20 calculates | requires the amount of electricity from the product of the electric current which flowed through the secondary battery 12, and the flow time, and integrates sequentially. FIG. 3 shows a flow of the charge / discharge electric quantity calculation means.

  Referring to FIG. 3, when this process starts (step S1000), an initial value is set. The initial value is ΔC, which is the amount of electricity during a minute time, and the accumulated charge / discharge amount of electricity ΣC. These values are set to zero (step S1010). Next, end determination is performed (step S1020). When the process is to be ended, the flow is shifted to the end process (step S1070).

  The end determination can be ended if there is an operation stop signal or an action even during this processing or other processing. In other words, the process is not returned from anywhere in step S1020, which is an end determination process, but this indicates that the end determination can be returned from any subsequent flow.

  Next, the control device 20 acquires the current value SA and the current direction from the charge / discharge current sensor 14 (step S1030). At this time, for example, it is preferable that the current to be acquired be handled with a positive sign if the current flows for charging and with a negative sign if the current flows toward the load 19. At this time, the voltage value SV may be acquired from the voltage sensor 13.

  Next, the current value SA is multiplied by a predetermined minute time ΔT to obtain a minute charge / discharge amount of electricity ΔC (step S1040). Then, the small charge / discharge electricity amount ΔC is added to the charge / discharge electricity amount ΣC to obtain a new charge / discharge electricity amount ΣC (step S1050). And it waits as it is until minute time (DELTA) T passes (step S1060). And it returns to step S1030 again and acquires electric current value SA. By doing in this way, the control apparatus 20 can always hold | maintain charging / discharging electricity amount (SIGMA) C (total amount of electricity as a result of discharging or charging from the secondary battery 12).

  Next, the operation of the independent power supply device 1 of the present invention will be described. Here, the full charge capacity FC is determined. The full charge capacity FC is the amount of electricity from when the secondary battery 12 is fully charged until it is fully discharged, and is expressed as current × time (A · hr: written as “Ah”). This can be obtained from a characteristic curve of the battery, usually called a discharge curve.

  FIG. 4 shows a graph for explaining the basic operation of the independent power supply device 1. FIG. 5 shows a flow of operations for FIG. In FIGS. 4A, 4B, and 4C, the horizontal axis represents time. From time t1 to t4 is a time zone in which sunlight can be obtained, and is a chargeable time zone. The vertical axis in FIG. 4A is the terminal voltage (V) of the secondary battery 12. The voltage V1 is a nominal voltage. For example, in the case of a lead storage battery, it is about 13.0V.

  V2 is the maximum voltage allowed at the time of charging and is a constant voltage setting value. The constant voltage set value is a value that serves as a guide when shifting from bulk charging (described later) to absorption charging. In the case of a lead storage battery, it is about 14.9V.

  In FIG. 4B, the vertical axis represents the charge / discharge current (A) flowing through the secondary battery 12. When the current value is positive, the current flows into the secondary battery 12, that is, the charged current. When the current value is negative, the current flows out from the secondary battery 12. In FIG. 4C, the vertical axis represents the charge / discharge electricity amount ΣC (Ah) of the secondary battery 12.

  Referring to the flow of FIG. 5, when this process is started (step S100), initial setting is performed (step S102), and an end determination is performed (step S104). The end determination may include not only a case where the power switch of the independent power supply 1 is stopped, but also a case where a trouble occurs in the independent power supply 1 and an interrupt is generated. In the case of termination (Y branch of step S104), the independent power supply device 1 is terminated (step S140).

  In order to simplify the explanation, it is assumed that the nighttime secondary battery 12 supplies power to the load 19 and is at time t0 in FIG. At this time, the integration of the charge / discharge electricity amount ΣC is continued (step S106), and it is determined whether or not the electromotive force of the solar cell module 10 is generated (step S108). In FIG. 5, “panel on (Vth)” is displayed.

  This is performed by referring to the value SPv from the electromotive force monitor 16. More specifically, the determination is made based on whether or not the value SPv is greater than a predetermined voltage Vth. Here, the voltage Vth is a threshold value for determining whether or not the power generated by the solar cell module 10 can be used.

  At this time, in FIG. 4, the time is between t0 and t1, the voltage of the secondary battery 12 (FIG. 4A) gradually decreases, and the flowing current (FIG. 4B) is loaded from the secondary battery 12 to the load. It flows toward 19 (the sign is negative). Therefore, the charge / discharge electricity amount ΣC (FIG. 4C) is integrated with minus values, and the absolute value of the minus value increases. That is, it can be said that the secondary battery 12 is decreasing toward a depleted state. When the charge / discharge electricity amount ΣC becomes “−FC (Ahr)”, the electricity amount of the secondary battery 12 is all discharged.

  At time t1, the sun rises and the solar cell module 10 starts generating power. When it is confirmed that the value SPv from the electromotive force monitor 16 exceeds a predetermined value (Vth) (Y branch in step S108), the process proceeds to bulk charging (step S110). Bulk charging refers to a charging mode in which charging of the secondary battery 12 is performed by MPPT (Maximum Power Point Tracker) control.

  Here, all the power generated by the solar cell module 10 other than the power required by the load 19 is used for charging the secondary battery 12. The control device 20 instructs the power control unit 22 to perform such charging with an instruction Cov. It should be noted that the charge / discharge electricity calculation means performs processing even during bulk charging, calculates the flow of electricity, and integrates the charge / discharge electricity ΣC.

  In bulk charging, current flows into the secondary battery 12, so that the charge / discharge current is positive (see FIG. 4B). In addition, the terminal voltage of the secondary battery 12 increases (see FIG. 4A). Bulk charging is continued until the terminal voltage of the secondary battery 12 reaches the constant voltage set value V2 (N branch in step S112). During this time, since a current flows to the secondary battery 12, the charge / discharge electricity amount ΣC increases from a negative value toward zero (see FIG. 4C).

  When the terminal voltage value (SV) of the secondary battery 12 reaches the constant voltage set value V2 (Y branch in step S112), the battery voltage shifts to a constant voltage charging mode (also called absorption charging) in which charging is performed with a constant charging voltage (referred to as absorption charging) ( Step S118). In the constant voltage charging mode, the power control unit 22 performs adjustment so that the voltage between the terminals of the secondary battery 12 becomes a predetermined value (here, the constant voltage setting value V2). On the other hand, the charge / discharge current gradually decreases (see FIG. 4B).

  Even during this time, the charge / discharge control means 11 supplies necessary power to the load 19. In addition, the charge / discharge electricity calculation means continues to calculate the charge / discharge electricity ΣC. The charge / discharge electricity amount ΣC increases from a negative value toward zero because a current flows into the secondary battery 12.

  In the constant voltage charging mode, the control device 20 detects whether the charge / discharge electricity amount ΣC has reached the target value TC. (Step S120). Note that immediately before entering the constant voltage charging mode, it is checked whether or not a predetermined number of days have passed (step S114), and the target value TC is set to zero (step S116). Here, the description is continued for a case where the predetermined number of days has not elapsed (N branch in step S114). The determination of whether the predetermined number of days has passed will be described later.

  When the charge / discharge electricity amount ΣC changes from a negative value to a target value TC (here, “zero”), the constant voltage charging mode is terminated (Y branch in step S120). That is, in the independent power supply device 1 of the present invention, the charge / discharge electricity amount ΣC discharged from the secondary battery 12 is accumulated as a negative value, and the secondary battery 12 is charged until the charge / discharge electricity amount ΣC returns to zero. . In other words, it is not determined that the battery is fully charged based on the voltage between the terminals of the secondary battery 12 as conventionally performed. By performing such charge control, the secondary battery 12 can be used with almost no deterioration.

  When the constant voltage charging mode ends (time t3 in FIG. 4), the process proceeds to the zero charging mode (step S122). The zero charge mode is a mode in which the secondary battery 12 is not charged at all. Of the electric power generated by the solar cell module 10, electric power required by the load 19 is supplied from the electric power control unit 22. Therefore, the charge / discharge current becomes zero (see time t3 to t4 in FIG. 4B). Further, the value of the charge / discharge current amount ΣC does not change.

  After shifting to the zero charge mode, it is monitored whether or not it has become nightfall (step S124). This can be realized by the control device 20 monitoring the value SPv of the electromotive force monitor 16. As in step S108, the threshold value to be compared with the value SPv is replaced with Vss, which is lower than the threshold value Vth in step S108. In other words, the zero charge mode is continued until the sunset and the power supply from the solar cell module 10 is completely eliminated (Y branch in step S124).

  When the sun sets and the electromotive force of the solar cell module 10 disappears (N branch in step S124), the secondary battery 12 starts to discharge the load 19 from the stored amount of electricity. At this time, the secondary battery 12 and the load 19 are connected by the power control unit 22 according to an instruction Cov from the control device 20. The process flow increments the date DL (step S126) and returns to step S104. In step S104, after the end determination (N branch in step S104), electricity is supplied to the load 19 while adding a negative value to the charge / discharge electricity amount ΣC, and the solar cell module 10 is activated (Y branch in step S108). Wait for.

  In the independent power supply device 1 of the present invention, charging is performed in the constant voltage charging mode at intervals of about once every few days until the charge / discharge electricity quantity ΣC becomes equal to or greater than a preset value. The preset value is about 0.2 times the full charge capacity FC. That is, as viewed from the charge / discharge electricity amount calculation means, the secondary battery 12 is charged so that the amount of electricity is about 1.2 times the full charge capacity. The life of the secondary battery 12 is further extended by the overcharge performed occasionally.

  In the independent power supply device 1, the charge / discharge electricity amount calculation means calculates the amount of electricity in and out of the secondary battery 12 (charge / discharge electricity amount ΣC), and performs charging based on the value. More specifically, a charge amount of electricity CC (sign is plus) that is the same as the amount of electricity EC (sign is minus) discharged from the secondary battery 12 is charged. This means that charging is performed such that the charge / discharge electricity amount ΣC becomes zero.

  However, in reality, charging loss occurs, and even when electricity is supplied to the secondary battery 12 until the charge / discharge electricity amount ΣC becomes zero, an electricity amount that is not charged is generated. That is, the amount of electricity that is actually charged in the secondary battery 12 is ΣC−δ even though the charge / discharge amount ΣC is zero in the calculation. Here, δ is a minute electric quantity. On the other hand, there is almost no error regarding the amount of electricity emitted from the secondary battery 12. That is, the amount of electricity EC discharged and the amount of electricity actually lost from the secondary battery 12 are substantially equal.

  Therefore, when the number of times of charging / discharging increases, the amount of electricity stored in the secondary battery 12 decreases when the secondary battery 12 reaches zero charge. Therefore, overcharge is performed every few days, and the amount of electricity actually stored in the secondary battery 12 is returned to the fully charged state.

  Referring to FIG. 5 again, when the date DL = M in step S114, the process proceeds to the Y branch in the sense that the Y branch is selected every M days. Usually, M is preferably set to 4 to 7, more preferably 5 to 6.

  If it progresses to Y branch in step S114, it will charge until it becomes an overcharge in constant voltage charge mode. In the processing flow, the target value TC is set as α (α is a positive numerical value), and the date DL is reset (= 0) (step S130). Then, constant voltage charging is performed (steps S132 to S134). The processing here is the same as in steps S118 to S120.

  However, what is determined in step S134 is whether or not the charge / discharge electricity amount ΣC has reached the target value TC (= α). α is preferably about 0.2 times the full charge capacity FC. That is, the secondary battery 12 is apparently overcharged with an amount of electricity that is about 1.2 times the full charge capacity FC. Therefore, α is an amount of electricity of about 0.2FC.

  In order for the charge / discharge electricity amount ΣC to be a positive value, it can be performed by lengthening the charging time.

  However, as described above, the charge electricity amount ΣC is actually lost. Then, even if electricity is supplied until the charge / discharge electricity amount ΣC becomes 0 or more, in practice, only an electricity amount of about the full charge capacity FC can be charged. Therefore, from the charge / discharge electricity amount ΣC, which is a calculated value, the secondary battery 12 is charged with 1.2FC electricity, but the amount of electricity actually stored in the secondary battery 12 is fully charged. There is a divergence between the calculated value that only the charging capacity FC is charged and the actual accumulated amount of electricity.

  When charging / discharging is repeated, this divergence becomes larger and it cannot be said that the charge / discharge electricity quantity ΣC of the secondary battery 12 is correctly controlled. Therefore, when overcharging is performed, the value of charge / discharge electricity amount ΣC is reset to zero (step S136). By doing so, the zero point of the charge / discharge electricity amount ΣC becomes almost the same value as the full charge capacity FC every time overcharge is performed, so that the electricity amount of the secondary battery 12 can be controlled correctly. it can.

  When the charge / discharge electricity amount ΣC is reset (step S136), the process shifts to the zero charge mode (step S122). The subsequent processing is as described above. Since the date DL is reset when the process proceeds to the overcharge process (after step S130), when the date DL is incremented in step S126, the increment starts again from the zero day.

  FIG. 6 shows a daily cycle when the processing flow of FIG. 5 is performed. In this case, the above M is set to 5 days. FIG. 6A shows a change in the charge / discharge electricity quantity ΣC by the flow of FIG. FIG. 6B shows an assumption diagram of changes in the battery capacity of an actual battery. In each case, the horizontal axis is the date. According to the flow of FIG. 5, until the M day, the same amount of electricity (up to ΣC = 0) as that used at night is charged every day (see FIG. 6A).

  However, the battery capacity of an actual battery gradually decreases (see FIG. 6B). On the fifth day, charging is performed up to ΣC = 0.2FC in the flow of FIG. As a result, the actual battery capacity returns to the initial capacity.

  As described above, in the independent power supply device 1 according to the present invention, the amount of electricity from the secondary battery 12 is calculated and the charge from the solar cell module 10 is performed based on the calculated amount of electricity. Even if the stable solar cell module 10 is used, the secondary battery 12 is hardly deteriorated.

  The charging from the solar cell module 10 to the secondary battery 12 shown in FIGS. 4 and 5 is when the weather is ideal, and when the power generation of the constantly changing solar cell module 10 decreases, Other processing may interrupt the above flow. The independent power supply device 1 of the present invention only needs to charge the secondary battery 12 through the above-described steps at least in the case of ideal weather.

(Embodiment 2)
The independent power supply device 2 of the present embodiment has the same configuration as the independent power supply device 1 shown in the first embodiment. Therefore, the hardware configuration is as shown in FIG. 1 and FIG. The independent power supply 2 has a part in which the processing according to FIG.

  Please refer to FIG. FIG. 7 is almost the same as FIG. As shown in FIG. 6B, when the secondary battery 12 is repeatedly charged and discharged, even if only the discharged amount of electricity is charged, it does not return to the original battery capacity. This fact can be confirmed when t3 shown in FIG. 4 gradually approaches t2, and eventually t2 = t3 as shown in FIG. That is, when the charge / discharge electricity amount ΣC is charged to zero by bulk charging, the terminal voltage of the battery reaches the constant voltage set value V2, and the constant voltage mode is not performed.

  In this embodiment, when such a situation occurs, overcharge is performed until the charge / discharge electricity amount ΣC becomes 0.2. The state of deterioration of the battery depends on the use history so far (the charge amount depends on the daily weather, and the discharge amount depends on the power consumption of the load 19). Therefore, as shown in the first embodiment, when overcharging is performed every certain number of days, the actual battery capacity of the secondary battery 12 when the secondary battery 12 to be used is overcharged is different each time.

  As a result of studying this point, the inventor has reached a time when the constant voltage set value (V2) is reached when performing bulk charging (t2 in FIG. 4), and a time when the constant charge is performed and the charge / discharge electric quantity ΣC becomes zero ( Paying attention to the time interval with t3) in FIG. 4, when this time interval (hereinafter referred to as “degradation index time”) reaches a predetermined time (hereinafter referred to as “Tth”), if overcharging is performed, It has been found that charging can be started from the state where the battery capacity of the actual battery is almost the same, and the battery can be overcharged, and the life can be extended without considering the influence of the usage history.

  Here, it is most preferable that the overcharge process is always performed with the same “degradation index time”. However, when the solar cell module 10 is used, it is necessary to assume a case where charging is stopped halfway due to the weather. Therefore, when the “deterioration index time” becomes equal to or shorter than the predetermined time, the process may be performed so that the overcharge process is given the highest priority.

  FIG. 8 shows a flow of processing according to the present embodiment. Since there are the same parts as the flow of FIG. 5, different parts will be described. In addition, about the part different from the flow of FIG. 5, the underline was attached | subjected to the step number. In the flow of the independent power supply device 2, the time t2 when the constant voltage set value (V2) is reached by bulk charging and the time t3 when the charge / discharge electricity amount ΣC is restored to zero by constant voltage charging are recorded. An overcharge process is performed when the difference falls below a predetermined value (Tth).

  First, bulk charging is performed in steps S110 and S112. When bulk charging ends (Y branch of step S112), the time t2 at that time is recorded as a variable Tsv (step S1111). Next, constant voltage charging is performed in steps S118 and S120. When the constant voltage charging is completed (Y branch of step S120), the time t3 at that time is recorded as a variable Tec (step S1112).

  Then, the process proceeds to overcharge processing (step S1113). In the overcharge process (step S1113), “deterioration index time” is obtained, and based on the value, it is determined whether or not overcharge is to be performed.

  FIG. 9 shows details of step S1113. First, a “deterioration index time” that is the difference between the variable Tec and the variable Tsv is obtained, and it is determined whether or not it is smaller than the predetermined time Tth (step S1201). If the “degradation index time” is shorter than the predetermined time Tth, it is determined that overcharge is performed, and a predetermined value is entered as the target value TC of the charge amount (step S1202). Overcharge is about 20% of the full charge capacity FC. Therefore, here, the target value TC in the overcharge process is set to 0.2.

  If the “deterioration index time” is not shorter than the predetermined time Tth, the secondary battery 12 determines that it can still be used, and sets the target value TC of the charge amount to zero (step S1203). Then, constant voltage charging is performed (step S1204). If it is not an overcharge process, the target value TC is zero, and the charge / discharge electricity quantity ΣC is already charged to zero in the step before step S1113. Therefore, the comparison between the charge / discharge electricity amount ΣC and the target value TC is immediately lost (Y branch in step S1205).

  Further, when the overcharge process is performed, the target value TC is set to 0.2, and therefore, constant voltage charging is performed until the charge / discharge electricity amount ΣC becomes zero.

  When the constant voltage charging is completed (Y branch of step S1205), it is next determined whether or not the target value TC is zero (step S1206). If the target value TC is not zero (N branch of step S1206), it means that the overcharge process has been completed, and thus the charge / discharge electricity amount ΣC and the target value TC are reset to zero (step S1207). When the target value TC is zero (Y branch of step S1206), step S1207 is skipped because the overcharge process is not performed.

  As described above, when the “degradation index time” reaches the predetermined time Tth in step S1113 for performing the overcharge process, the overcharge process can be performed. As described above, since the overcharge is performed based on the “degradation index time”, the independent power supply device 2 can start charging from a state where the actual battery capacity of the secondary battery 12 is substantially the same, and can enter the overcharge state. The life can be extended without considering the influence of usage history.

(Embodiment 3)
The independent power supply device 3 according to the present embodiment includes processing when the solar cell module 10 cannot perform predetermined power generation due to weather when overcharging. More specifically, the independent power supply 3 charges the remaining amount of electricity when charging the next day when it cannot be charged to a predetermined charge / discharge amount ΣC.

  FIG. 10 shows a model of this charging. The vertical axis represents the charge / discharge electricity amount ΣC. The horizontal axis is the date. It is assumed that the independent power supply 3 is overcharged on a certain K day. The overcharge target value TC is the charge / discharge electricity amount ΣC = 0.2. However, it is assumed that charging is stopped at time EM due to the weather and the like, and only charging up to DC1 is possible. The independent power supply 3 charges at least the remaining DC 2 on the next day (K + 1 day). Here, DC1 + DC2 = α (0.2). Thus, even if overcharging is performed the next day, the life of the battery can be extended.

  FIG. 11 shows a flow of the independent power supply device 3. Bulk charging is performed in steps S110 and S112, and constant voltage charging is performed in steps S118 and S120, as in the case of the second embodiment. Also, the time t2 and the time t3 (see FIG. 4) are recorded in steps S1111 and S1112 as described in the second embodiment.

  The contents of the overcharge process in step S1114 are shown in FIG. Referring to FIG. 12, it is first determined whether or not variable NX is 1 (step S1301). The variable NX is a flag that is set when charging is interrupted during the overcharge process. If the variable NX is 1 (Y branch of step S1301), it means that the overcharge process was performed the day before and was interrupted halfway.

  If the variable NX is not 1 (N branch of step S1301), it is determined whether or not the “degradation index time” is shorter than the predetermined time Tth (step S1201). The following is almost the same as in the second embodiment. If the “degradation index time” is shorter than the predetermined time Tth, it is determined that overcharge is performed, and a predetermined value is entered as the target value TC of the charge amount (step S1202).

  If the “deterioration index time” is not shorter than the predetermined time Tth, the secondary battery 12 determines that it can still be used, and sets the target value TC of the charge amount to zero (step S1203). Then, constant voltage charging is performed (step S1204). If it is not an overcharge process, the target value TC is zero, and the charge / discharge electricity quantity ΣC has already been charged to zero in the step before this step S1114. Therefore, the comparison between the charge / discharge electricity amount ΣC and the target value TC is immediately lost (Y branch in step S1205).

  Next, it is determined whether or not the target value TC is zero (step S1206). If the target value TC is other than zero, it means that the overcharge process has been completed, and the charge / discharge electricity amount ΣC and the target value TC are reset to zero (step S1207). If the overcharge process has not been performed (Y branch of step S1206), step S1207 is skipped. The above steps are the same as those in the second embodiment.

  On the other hand, the case of performing the overcharge process, that is, the case of performing the overcharge process in which the target value TC for charging is set to 0.2 is different from that of the second embodiment. That is, since the target value TC is set to 0.2, constant voltage charging is performed until the charge / discharge electricity amount ΣC becomes zero. Is the electromotive force SPv of the solar cell module 10 larger than the predetermined voltage Vth? It is always determined whether or not (step S1303).

  When the solar cell module 10 is generating power (Y branch in step S1303), constant voltage charging is continued (step S1204). However, if the solar cell module 10 no longer generates power during constant voltage charging (N branch in step S1303), the variable NX is set to 1, and the charge / discharge electricity amount ΣC, which is the charge amount up to that, is recorded as DC1. To do. Then, the process goes through step S1114.

  If step S1114 which is an overcharge process is passed, it will return to FIG. 11 and zero charge (step S122) will be performed. In this way, the flow returns to step S104. On the next day, bulk charging and constant voltage charging are performed again, and the process returns to step S1114.

  Referring to FIG. 12 again, since the overcharge process is stopped halfway on the previous day, 1 is assigned to variable NX. Accordingly, the process proceeds to the Y branch in step S1301. Here, the charging target value TC is obtained as α (0.2) −DC1. Here, α (0.2) is a target value for charging when performing the overcharge process. The variable NX is reset here (step S1302).

  The process then proceeds to constant voltage charging (step S1204). Here, since the charging target value TC is the difference between the value reached on the previous day and the overcharging processing target value of 0.2, the remaining amount is charged (step S1205).

  When the constant voltage charging is completed, it is determined whether or not the target value TC is zero (step S1206). When the overcharge process is performed, the target value TC is not zero, so the parameters are reset (step S1207).

  As described above, when performing the overcharge process, the independent power supply device 3 charges the remaining portion on the next day if the charging is interrupted in the middle. As a result, the overcharge performed based on the “degradation index time” is reliably executed, and the life of the secondary battery 12 is extended.

(Embodiment 4)
As shown in Embodiments 1 to 3, the lifetime of the secondary battery 12 can be extended by performing the overcharge process at a predetermined timing. However, if the secondary battery 12 is deteriorated, the capacity of the secondary battery 12 is not restored even if the overcharge process is performed. In such a case, it is necessary to replace the secondary battery 12 itself. The independent power supply device 4 according to the present embodiment has a function of notifying that when it can be determined that the capacity of the secondary battery 12 does not return to the original state even if the overcharge process is performed.

  FIG. 13 shows the configuration of the independent power supply device 4. The same parts as those in FIG. 1 described in the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 13, the difference from Embodiments 1 to 3 is that the charge / discharge control means 11 has a notification means 40. In FIG. 13, the notification means 40 is represented by lighting a display 42 that notifies the outside that the secondary battery 12 has deteriorated.

  The display 42 is an example, and may be a display on a graphic screen or a notification signal to another device. Further, it may be used as an activation signal for performing some processing inside the independent power supply device 4. The independent power supply device 4 measures the voltage of the secondary battery 12 after performing the overcharge process. If the voltage is equal to or lower than the predetermined voltage, the independent power supply device 4 determines that the secondary battery 12 has deteriorated and notifies the outside by the notification means 40. To do.

  FIG. 14 is a diagram showing a detailed configuration of the charge / discharge control means 11. The same parts as those in FIG. 2 are denoted by the same reference numerals and description thereof is omitted. The notification means 40 is configured as an output of the control device 20. More specifically, when the control device 20 determines that the secondary battery 12 has deteriorated, the control device 20 generates a notification signal Sbd and flows it to the wiring L10.

  Whether or not the battery capacity of the secondary battery 12 has been restored is determined by the voltage SV between the electrodes of the secondary battery 12. This is because the control device 20 that receives the signal of the voltage sensor 13 outputs the signal most easily.

  FIG. 15 shows an example in which the battery capacity does not return because the secondary battery 12 has deteriorated. Referring to FIG. 15, charging is performed so that ΣC becomes zero from the first day to the fourth day. However, in actuality, a loss occurs, and the battery capacity falls below the original (zero) capacity. Therefore, the overcharge process is performed on the fifth day (point A). Therefore, the battery capacity returns to the original (zero) capacity (point B).

  However, if the secondary battery 12 is used for a long time, the electrolyte and the electrodes change over time, and can no longer be reversibly changed. In such a case, the secondary battery 12 is deteriorated, and the battery capacity does not return to the original (zero) capacity even if the overcharge process is performed. In FIG. 15, the overcharge process was performed on the N + 4th day (AN point), but the battery capacity does not recover to the original capacity (BN point).

  If the constituent material of the secondary battery 12 changes in this way and the secondary battery 12 deteriorates, the battery capacity will not be restored no matter how charging is performed from the outside. Then, there is a possibility that supply to the planned load cannot be performed. Therefore, the deteriorated secondary battery 12 needs to be replaced.

  FIG. 16 shows a processing flow of the independent power supply device 4. This is almost the same processing as the processing flow of the independent power supply device 1 shown in FIG. The difference from FIG. 5 is that a flow (steps S140 and S142) for confirming the battery capacity is added to the portion (steps S130 to S136) where the overcharge process is performed.

  The flow for checking the battery capacity is performed immediately after the overcharge process is completed. Or it may be said that it is just before zero charge processing. That is, it is inserted after step S136 (before step S122). This is because the deterioration of the secondary battery 12 is examined based on the presence or absence of the effect of overcharge processing (recovery of battery capacity). In addition, as a circuit adjustment, it is necessary to set it as the zero charge mode so that it may mention later.

  An overcharge process is performed in steps S130 to S134, and the charge / discharge electricity quantity ΣC is reset to zero in step S136. Next, in step S140, it is determined whether or not the voltage SV between the terminals of the secondary battery 12 is greater than a predetermined voltage value SVth. Here, the predetermined voltage value SVth is a voltage value at which it can be determined that the battery has deteriorated, and may be referred to as a deterioration determination voltage. The deterioration determination voltage SVth is, for example, a value corresponding to 80% of the nominal voltage at full charge. The value of degradation determination voltage SVth itself may be a value determined in advance at the time of design.

  The measured value SV from the voltage sensor 13 may be used as the terminal voltage of the secondary battery 12. The voltage sensor 13 does not measure the open voltage of the secondary battery 12. This is because the secondary battery 12 is connected to the independent power supply device 4. However, if the power control unit 22 (see FIG. 14) is adjusted to the zero charge mode, the inter-terminal voltage SV of the secondary battery 12 may be considered to be substantially equal to the open circuit voltage. This is because the zero charge mode is a mode in which the secondary battery 12 is not charged / discharged.

  Further, it may be considered that the voltage between the terminals of the secondary battery 12 and the battery capacity have a substantially proportional relationship. In FIG. 17, the graph which investigated the voltage between terminals of a lead battery and battery capacity is shown. The vertical axis is the open circuit voltage (V), and the horizontal axis is the battery capacity (%). The black circle is when the secondary battery 12 is 0 (zero) ° C., and the white circle is when it is 40 ° C. FIG. 17 is a right-downward graph, and the open-circuit voltage and the battery capacity are generally proportional.

  In order to measure the open circuit voltage of the secondary battery 12 incorporated in a normal system, a mechanism for mechanically disconnecting and measuring the terminal of the secondary battery 12 and the system is required. However, in the independent power supply device 4 according to the present invention, the same effect as that obtained by measuring the open-circuit voltage is obtained by using the zero charge mode.

  Referring to FIG. 16 again, if inter-terminal voltage SV is higher than deterioration determination voltage SVth (Y branch in step S140), it is determined that secondary battery 12 is not deteriorated, and the process is performed in the next step (step S122). Move. If the inter-terminal voltage SV is lower than the deterioration determination voltage SVth (N branch of step S140), the control device 20 determines that the secondary battery 12 has deteriorated and activates the notification means 40 (step S142). More specifically, the control device 20 generates a notification signal Sbd and transmits the notification signal Sbd through a predetermined path (L10). Then, the process proceeds to the next step S122.

  By adding the above processing, the independent power supply device 4 determines the deterioration of the secondary battery 12 when the overcharge processing is performed, and generates the notification signal Sbd if the secondary battery 12 has deteriorated.

  In the above description, the deterioration determination process of the secondary battery 12 is added in the case of the first embodiment, but may be added in the cases of the second and third embodiments. Specifically, in the case of the process flow of the independent power supply device 2 shown in FIG. 8, steps S140 and S142 shown in FIG. 16 are added between the overcharge process in step S1113 and the zero charge flow in step S122. To do.

  In the case of the independent power supply device 3 shown in FIG. 11, the steps S140 and S142 may be added between the overcharge process in step S1114 and the zero charge flow in step S122.

The independent power supply device of the present invention can be widely used not only for a power supply device using a solar battery module but also for charging control of a secondary battery.

DESCRIPTION OF SYMBOLS 1 Independent power supply apparatus 10 Solar cell module 11 Charging / discharging control means 12 Secondary battery 13 Voltage sensor 14 Charging / discharging current sensor 15 Output terminal 16 Electromotive force monitor 19 Load 20 Control apparatus 22 Power control part 24 Memory 25 Timer 40 Notification means 42 Display

Claims (6)

A solar cell module that generates power with solar energy;
An independent power supply that supplies generated power generated by the solar cell module to a load, charges surplus power to a secondary battery, and supplies insufficient power from the secondary battery to the load when the generated power is insufficient Because
Charge / discharge control means for controlling a charge amount of the power generated by the solar cell module to the secondary battery and a power supply amount to the load;
A voltage sensor for measuring the voltage of the secondary battery;
A charge / discharge current sensor for measuring a charge current to the secondary battery and a discharge current from the secondary battery;
Charging / discharging electric quantity which calculates the charging / discharging electric quantity which is the sum total of the charging electric quantity to the said secondary battery, and the discharging electric quantity from the said secondary battery based on the measured value from the said voltage sensor and the said charging / discharging current sensor Having an arithmetic means;
When the charge / discharge control means charges the secondary battery,
An independent power source characterized in that the charging voltage of the secondary battery is maintained at the constant voltage set value until the charge / discharge electricity amount reaches zero from a negative value after the voltage of the secondary battery reaches a constant voltage set value. apparatus. The charge / discharge control means uses the generated power only for power supply to the load when the secondary battery is charged until the charge / discharge electricity amount reaches zero from a negative value. 1. The independent power supply device described in 1. The charge / discharge control means performs charging until the charge / discharge electricity amount becomes equal to or higher than a preset value every predetermined period, and resets the value of the charge / discharge electricity amount.
Or the independent power supply device described in any one of 2. When the time interval between the time when the voltage of the secondary battery reaches the constant voltage set value and the time when the charge / discharge electricity amount reaches zero is less than or equal to a predetermined time, the charge / discharge control means, 2. Charging is performed until the charge / discharge electricity amount is equal to or higher than a preset value.
Or the independent power supply device described in any one of 2. The charge / discharge control means charges the shortage on the next day if the charge / discharge control unit becomes unable to be charged before the charge / discharge electricity amount becomes equal to or greater than the preset value. The independent power supply device described in any one of the items.   After charging until the predetermined value or more is reached, the value of the voltage sensor is examined, and if the value of the voltage sensor is lower than a predetermined value, a battery deterioration signal is generated. The independent power supply device according to claim 3, wherein the power supply device is independent.