JP2010054470A - Device and method for estimating capacity of battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To estimate the capacity of a battery, even if it is a battery to be used in a stand-alone power supply. <P>SOLUTION: A controller 100 controls a solar battery system which includes a solar battery 1, a battery module 2, and a load 3. In the controller, an open-circuit voltage setting part 120 sets an open-circuit voltage of the battery module 2, based on a battery voltage acquired by measurement, immediately prior to the interruption of charging and a battery voltage acquired by measurement, after the interruption of the charging. Moreover, a voltage-drop value calculation part 130 calculates the value of the voltage drop between the battery voltage acquired by the measurement, immediately prior to the charging interruption and the open-circuit voltage. A battery-capacity estimation part 140 estimates the capacity of the battery module 2, based on the calculated voltage drop value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a storage battery capacity estimation device and a storage battery capacity estimation method for estimating the capacity of a storage battery, and in particular, a storage battery capacity estimation device and a storage battery capacity estimation capable of estimating a capacity even for a storage battery used in a stand-alone power source. It is about the method.

  Generally, when a nickel metal hydride storage battery deteriorates, its internal resistance increases. In addition, the nickel metal hydride storage battery is in an open circuit state when charging is interrupted, but a voltage drop occurs at that time. The drop value of this voltage drop is the product of the current and the internal resistance. Normally, since the nickel metal hydride storage battery is charged with a constant current, the magnitude of the voltage drop value depends on the internal resistance. That is, in the nickel metal hydride storage battery, when the internal resistance increases due to deterioration, the voltage drop value when the open circuit state is reached increases.

  In recent years, a method for estimating the capacity of a nickel-metal hydride storage battery from a voltage drop value in an open circuit state has been devised using such properties (see, for example, Non-Patent Document 1). Specifically, in this method, the nickel metal hydride storage battery is charged with a constant current, and when the battery is fully charged, the charging is interrupted and the nickel metal hydride battery is brought into an open circuit state. Then, the internal resistance is estimated from the drop value of the voltage drop generated when the open circuit state is set, and the capacity of the nickel metal hydride battery is estimated.

Akira Yamashita, Hiroshi Wakaki, Keiichi Saito, Takahisa Shodai, “Capacity Estimation of Nickel Metal Hydride Backup Batteries”, Abstracts of INTELEC'03 (The 25th International Telecommunications Energy Conference), 2003, p. 739

  However, when a storage battery such as a nickel metal hydride storage battery is used in a self-supporting power source having a power generation means such as a solar battery, when the power generation means is disconnected and charging of the storage battery is interrupted, the open circuit state or the discharge state from the charged state To change. In other words, depending on the circuit configuration, the self-supporting power source may not be in an open circuit state even when charging is interrupted. For this reason, the capacity of the storage battery used in the self-supporting power source cannot be estimated from the voltage drop value in the open circuit state as in the conventional method described above.

  The present invention has been made to solve the above-described problems caused by the prior art, and provides a storage battery capacity calculation device and a storage battery capacity calculation method capable of estimating the capacity even for a storage battery used in a self-supporting power source. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, the present invention is a storage battery capacity estimation device that estimates the capacity of a storage battery, and the storage battery voltage measured immediately before charging is interrupted and after charging is interrupted An open circuit voltage setting means for setting an open circuit voltage of the storage battery based on the measured storage battery voltage, a storage battery voltage measured immediately before the charging is interrupted, and an open circuit set by the open circuit voltage setting means Voltage drop value calculating means for calculating a voltage drop value between the voltage and storage battery capacity estimating means for estimating the capacity of the storage battery based on the voltage drop value calculated by the voltage drop value calculating means. It is characterized by that.

  The present invention is also a storage battery capacity estimation method for estimating the capacity of a storage battery, wherein the storage battery voltage is measured based on a storage battery voltage measured immediately before charging is interrupted and a storage battery voltage measured after charging is interrupted. An open circuit voltage setting step for setting the open circuit voltage of the battery, and a voltage drop value between the storage battery voltage measured immediately before the interruption of charging and the open circuit voltage set by the open circuit voltage setting step is calculated The method includes a voltage drop value calculating step and a storage battery capacity estimating step of estimating the capacity of the storage battery based on the voltage drop value calculated by the voltage drop value calculating step.

  According to the present invention, there is an effect that it is possible to estimate the capacity even for a storage battery used in a self-supporting power source.

  Exemplary embodiments of a storage battery capacity estimation device and a storage battery capacity estimation method according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, the Example shown below demonstrates the case where this invention is applied to the control apparatus of the solar cell system provided with the solar cell, the storage battery module, and load.

  First, the configuration of the solar cell system according to the first embodiment will be described. FIG. 1 is a block diagram illustrating the configuration of the solar cell system according to the first embodiment. As shown in the figure, this solar cell system includes a solar cell 1, a storage battery module 2, a load 3, a backflow prevention diode 4, a charge stop switch 5, a storage battery voltage measurement unit 6, a storage battery temperature measurement unit 7, and a charge / discharge current measurement. Unit 8 and control device 100. Here, the solar cell 1 and the storage battery module 2 constitute a self-supporting power source.

  The solar cell 1 generates electric power by converting solar energy into electric energy, and supplies the generated electric power to the storage battery module 2 and the load 3. As this solar cell 1, for example, a silicon single crystal solar cell or the like is used.

  The storage battery module 2 stores power supplied from the solar battery 1 and supplies power to the load 3 when charging by the solar battery 1 is interrupted. As the storage battery module 2, for example, a plurality of nickel hydride storage batteries connected in series are used.

  The load 3 consumes power supplied from the solar cell 1 and the storage battery module 2. For example, an LED (Light Emitting Diode) illuminator or the like is used as the load 3.

  The backflow prevention diode 4 has a cathode-side terminal connected between the solar cell 1 and the load 3, and an anode-side terminal connected to the plus terminal of the storage battery module 2. The backflow prevention diode 4 controls the flow of current from the solar cell 1 to the storage battery module 2 in cooperation with the charge stop switch 5.

  The charge stop switch 5 is connected so as to bridge both sides of the backflow prevention diode 4 and controls charging from the solar cell 1 to the storage battery module 2. When the charge stop switch 5 is turned on, a charging current flows from the solar cell 1 to the storage battery module 2 via the charge stop switch 5, and the storage battery module 2 is charged. On the other hand, when the charge stop switch 5 is turned off, the charging current flowing from the solar cell 1 to the storage battery module 2 is interrupted by the backflow prevention diode 4, and the charging of the storage battery module 2 is interrupted.

  The storage battery voltage measurement unit 6 measures the voltage (storage battery voltage) of the storage battery module 2. The storage battery temperature measurement unit 7 measures the temperature of the storage battery module 2. The charge / discharge current measuring unit 8 measures the charge current and the discharge current of the storage battery module 2.

  The control device 100 performs overall control of the solar cell system. The control device 100 is connected to the charge stop switch 5 via the switch control line 10 and is connected to the storage battery voltage measuring unit 6 via the measurement line 9a. Moreover, the control apparatus 100 is connected to the storage battery temperature measurement part 7 via the measurement line 9b, and is connected to the charging / discharging current measurement part 8 via the measurement line 9c.

  Under such a configuration, in the first embodiment, the control device 100 uses the storage battery module 2 based on the storage battery voltage measured immediately before the charging is interrupted and the storage battery voltage measured after the charging is interrupted. Set the open circuit voltage of. Then, the control device 100 calculates a voltage drop value between the storage battery voltage and the open circuit voltage measured immediately before the charging is interrupted, and estimates the capacity of the storage battery module 2 based on the calculated voltage drop value. To do. Thereby, in the present Example 1, even if it is the storage battery used with a self-supporting power supply, it can be estimated.

  As shown in FIG. 1, the control device 100 particularly includes a capacity estimation start determination unit 110, an open circuit voltage setting unit 120, a voltage drop value calculation unit 130, and a storage battery capacity estimation unit 140.

  The capacity estimation start determination unit 110 performs capacity estimation start determination based on a predetermined start condition. The start condition used here is hereinafter referred to as “capacity estimation start condition”.

  Specifically, the capacity estimation start determination unit 110, when the charge stop switch 5 is on, the storage battery voltage measured by the storage battery voltage measurement unit 6, the temperature measured by the storage battery temperature measurement unit 7, the charge / discharge current The charging current measured by the measuring unit 8 is measured. Then, the capacity estimation start determination unit 110 determines whether the capacity estimation start condition is satisfied based on the measured storage battery voltage, temperature, and charging current, and determines that the capacity estimation start condition is satisfied. In that case, the charging stop switch 5 is turned off to interrupt the charging.

  Here, an example of the start determination by the capacity estimation start determination unit 110 will be described. For example, the capacity estimation start determination unit 110 sets the capacity estimation start condition when one of the conditions 1 and 2 is satisfied and the condition 3 is satisfied in the following conditions 1, 2 and 3. It is determined that it has been established. For determining the charging rate in Condition 1, a publicly known publicly known charging rate measuring method is used.

Condition 1: The estimated charging rate is 90% or more.
Condition 2: The charging voltage is 14.0 V or more.
Condition 3: More than 30 days have passed since the end of the previous capacity determination.

  The open circuit voltage setting unit 120 sets the open circuit voltage of the storage battery module 2 based on the storage battery voltage measured immediately before the charging is interrupted and the storage battery voltage measured after the charging is interrupted.

  Specifically, the open circuit voltage setting unit 120 starts time measurement when the capacity estimation start determination unit 110 determines that the capacity estimation start condition is satisfied. Thereafter, the open circuit voltage setting unit 120, when a predetermined standby time has elapsed, the storage battery voltage measured by the storage battery voltage measurement unit 6 and the charge / discharge current (current value zero) measured by the charge / discharge current measurement unit 8. Measure. Then, the open circuit voltage setting unit 120 sets the storage battery voltage measured here as the open circuit voltage of the storage battery module 2. For example, the open circuit voltage setting unit 120 sets, as an open circuit voltage, a voltage measured at the time when 10 seconds have elapsed since charging was interrupted.

FIG. 2 is a diagram for explaining a method of setting an open circuit voltage in the first embodiment. In the figure, V _c indicates the battery voltage measured immediately before the charging is interrupted, V ₀ denotes a battery voltage measured when a predetermined standby time has elapsed. In this case, the open circuit voltage setting unit 120 sets the V ₀ shown in the figure as the open circuit voltage.

  Returning to FIG. 1, the voltage drop value calculation unit 130 calculates a voltage drop value between the storage battery voltage measured immediately before the charging is interrupted and the open circuit voltage set by the open circuit voltage setting unit 120. .

  Specifically, when the open circuit voltage is set by the open circuit voltage setting unit 120, the voltage drop value calculation unit 130 and the capacity estimation start determination unit 110 immediately before the set open circuit voltage and charging are interrupted. The voltage drop value between the two voltages is calculated by obtaining the difference from the storage battery voltage measured by the above.

  The storage battery capacity estimation unit 140 estimates the capacity of the storage battery module 2 based on the voltage drop value calculated by the voltage drop value calculation unit 130.

  Specifically, when the voltage drop value is calculated by the voltage drop value calculation unit 130, the storage battery capacity estimation unit 140 first calculates the voltage drop value and the capacity estimation start determination unit immediately before the charging is interrupted. The internal resistance value of the storage battery module 2 is calculated from the charging current measured by 110.

For example, when the voltage drop value calculated by the voltage drop value calculation unit 130 is ΔV and the charging current measured by the capacity estimation start determination unit 110 is I _c , the storage battery capacity estimation unit 140 The resistance value r is calculated by r = ΔV / I _c .

  Subsequently, the storage battery capacity estimation unit 140 estimates the capacity of the storage battery module 2 by comparing the calculated internal resistance value with a reference resistance value defined as a function of the temperature of the storage battery module 2. The reference resistance value used here is defined based on an internal resistance value measured in advance with the capacity of the storage battery module 2 as a reference value.

  For example, a storage battery module in which 10 cells of nickel hydrogen storage batteries with a rated capacity of 95 Ah are connected in series is accelerated and deteriorated until the capacity reaches 80% of the initial value. Next, in an environment where the temperature is between −5 ° C. and 45 ° C., the storage battery module is charged with a current of 20 A until the temperature rise per minute reaches 0.3 ° C.

  Thereafter, the storage battery module is allowed to stand for 10 minutes, and the voltage drop value during that period is measured. Then, the measured voltage drop value is divided by the charging current value to obtain an internal resistance value, which is approximated by a parabola as a function of the temperature of the storage battery at the end of charging. Thereby, the function of the temperature T represented by the following formula (1) is obtained. A function of the temperature T is defined as a reference resistance value R used by the storage battery capacity estimation unit 140.

R = aT ² −bT + c (1)

Here, a = 5.8 × 10 ⁻⁶ , b = 6.3 × 10 ⁻⁴ , and c = 0.059.

  Returning to the description of the capacity estimation, the storage battery capacity estimation unit 140 substitutes the temperature of the storage battery module 2 measured by the capacity estimation start determination unit 110 immediately before the charging is interrupted into the function of the temperature T described above. Thus, the reference resistance value R is calculated.

  Then, the storage battery capacity estimation unit 140 compares the calculated reference resistance value R with the previously calculated internal resistance value r, and if the internal resistance value r exceeds the reference resistance value R, the storage battery capacity is estimated. It is estimated that the capacity of module 2 is below 80%.

  Here, for example, when it is estimated that the capacity of the storage battery module 2 is less than 80%, the storage battery capacity estimation unit 140 outputs a message prompting the replacement of the storage battery module 2 to an output device such as a display or a printer. .

  Next, a processing procedure for capacity estimation by the control device 100 according to the first embodiment will be described. FIG. 3 is a flowchart illustrating the processing procedure of capacity estimation performed by the control device 100 according to the first embodiment.

  As shown in the figure, in the control device 100, the capacity estimation start determination unit 110 measures the storage battery voltage, temperature, and charging current of the storage battery module 2 (step S101).

  Subsequently, the capacity estimation start determination unit 110 determines whether or not a capacity estimation start condition is satisfied based on the measured storage battery voltage, temperature, and charging current. Here, the capacity estimation start determination unit 110 repeats the measurement of the storage battery voltage, temperature, and charging current until the capacity estimation start condition is satisfied (No in step S102).

  And when it determines with the capacity | capacitance estimation start conditions being satisfied (step S102, Yes), the capacity | capacitance estimation start determination part 110 turns off the charge stop switch 5, and interrupts charge (step S103).

  When charging is interrupted, the open circuit voltage setting unit 120 starts measuring time (step S104). Then, the open circuit voltage setting unit 120 measures the storage battery voltage and the charge / discharge current (current value zero) of the storage battery module 2 when the predetermined standby time has elapsed (step S105, Yes) (step S106). The stored battery voltage is set as an open circuit voltage (step S107).

  When the open circuit voltage is set, the voltage drop value calculation unit 130 determines a voltage drop value between the storage battery voltage measured immediately before the charging is interrupted and the open circuit voltage set by the open circuit voltage setting unit 120. Is calculated (step S108).

  Then, the storage battery capacity estimation unit 140 estimates the capacity of the storage battery module 2 based on the voltage drop value calculated by the voltage drop value calculation unit 130 (step S109).

  As described above, in the first embodiment, the open circuit voltage setting unit 120 is based on the storage battery voltage measured immediately before the charging is interrupted and the storage battery voltage measured after the charging is interrupted. Set the open circuit voltage of 2. Further, the voltage drop value calculation unit 130 calculates a voltage drop value between the storage battery voltage and the open circuit voltage measured immediately before the charging is interrupted. Then, the storage battery capacity estimation unit 140 estimates the capacity of the storage battery module 2 based on the calculated voltage drop value. Therefore, according to the first embodiment, it is possible to estimate the capacity of the storage battery in the self-supporting power source that is in an open circuit state when charging is interrupted.

  The first embodiment has been described above. Here, a specific example of capacity estimation in the first embodiment will be described. FIG. 4 is a diagram for explaining a specific example of capacity estimation in the first embodiment. For example, as shown in the figure, in the solar cell system shown in FIG. 1, instead of the backflow prevention diode 4, a switch 21 is provided between the solar cell 1 and the storage battery module 2, and a switch 22 is the storage battery module 2. And the load 3 are considered.

  In the figure, a solar cell 1 is a silicon single crystal solar cell with a rated output of 90 W. In addition, the storage battery module 2 is a module in which 10 cells of nickel hydride storage batteries having a rated capacity of 95 Ah are connected in series. The solar cell 1 and the storage battery module 2 constitute a self-supporting power source.

  The load 3 is an LED illuminator with a power consumption of 15 W. The load 3 is disconnected from the self-supporting power source by a switch 22 during the daytime, and is lit only at night by a timer. Therefore, in the daytime, when the solar cell 1 is disconnected by turning off the switch 21, the storage battery module 2 is in an open circuit state.

  The control device 200 has the same configuration as the control device 100 shown in FIG. The control device 200 is connected to the switch 21 via the switch control line 20a and is connected to the switch 22 via the switch control line 20b, and controls on / off of each switch.

  Under such a configuration, for example, when the charging voltage of the storage battery module 2 is 14.8 V, the charging current is 4.1 A, and the temperature is 35.2 ° C., the solar cell 1 is disconnected and charging is interrupted. Assume that the voltage of the storage battery module 2 becomes 14.6 V after 10 seconds. In this case, when the internal resistance value is calculated, the internal resistance value is 49 mV. This value exceeds 44 mV obtained by substituting the temperature of 35.2 ° C. into the equation (1). Therefore, it is estimated that the capacity | capacitance of the storage battery module 2 has degraded to less than 80% at this time.

  By the way, in the said Example 1, the case where the storage battery voltage measured when the predetermined standby | waiting time passed after charging was interrupted was set as an open circuit voltage was demonstrated. However, the present invention is not limited to this.

  For example, the amount of change of the storage battery voltage is calculated every predetermined time interval after the charging is interrupted, and the storage battery voltage at the time when the calculated amount of change becomes a predetermined threshold or less is set as the open circuit voltage. Also good. Hereinafter, such a case will be described as a second embodiment.

  Note that the configurations of the solar cell system and the control device in the second embodiment are basically the same as those shown in FIG. 1, and only the processing performed by the open circuit voltage setting unit 120 is different. Therefore, here, the processing procedure of capacity estimation performed by the control device 100 according to the second embodiment will be described focusing on the processing performed by the open circuit voltage setting unit 120.

  FIG. 5 is a flowchart illustrating the processing procedure of capacity estimation performed by the control device 100 according to the second embodiment. In the same figure, the processes (steps S201 to S203) until the charging is interrupted by the capacity estimation start determination unit 110 are the same as the processes of steps S101 to S103 shown in FIG.

  When charging is interrupted, the open circuit voltage setting unit 120 starts measuring time (step S204). And the open circuit voltage setting part 120 measures the storage battery voltage and charging / discharging electric current (current value zero) of the storage battery module 2, when predetermined time passes (step S205, Yes) (step S206).

  Subsequently, the open circuit voltage setting unit 120 calculates a voltage drop gradient from the amount of change between the previously measured storage battery voltage and the currently measured storage battery voltage (step S207). Here, the open circuit voltage setting unit 120 does not set the open circuit voltage while the voltage drop gradient exceeds a predetermined threshold (No in step S208), and repeatedly performs the processes in steps S204 to S207 described above. .

  When the voltage drop gradient becomes equal to or less than the predetermined threshold, the open circuit voltage setting unit 120 sets the storage battery voltage at that time as an open circuit voltage (Yes in step S208).

  For example, the open circuit voltage setting unit 120 measures the voltage of the storage battery module 2 with an accuracy of 10 mV every 5 seconds after charging is interrupted, and the amount of change in the storage voltage (voltage drop gradient) becomes zero. Set the battery voltage as an open circuit voltage. In that case, for example, if the amount of change between the voltage after 10 seconds and the voltage after 15 seconds is zero after the charging is interrupted, and the voltage measured at the time after 15 seconds is 13.45 V, The open circuit voltage is 13.45V.

  When the open circuit voltage is set, the voltage drop value calculation unit 130 calculates a voltage drop value between the storage battery voltage just before the charging is interrupted and the open circuit voltage set by the open circuit voltage setting unit 120. (Step S209). Then, the storage battery capacity estimation unit 140 estimates the capacity of the storage battery module 2 based on the voltage drop value calculated by the voltage drop value calculation unit 130 (step S210).

  As described above, in the second embodiment, the open circuit voltage setting unit 120 calculates the change amount of the storage battery voltage at every predetermined time interval after the charging is interrupted, and the calculated change amount is equal to or less than the predetermined threshold value. The storage battery voltage at that time is set as an open circuit voltage. Therefore, according to the second embodiment, even when the time until the discharge state is changed for each storage battery, it is possible to accurately detect the timing when the discharge state is set for each storage battery and estimate the capacity. .

  By the way, in Examples 1 and 2 described above, when the storage battery voltage measured at the time when the predetermined standby time has elapsed after the charging is interrupted or the amount of change per predetermined time becomes equal to or less than the predetermined threshold value. The case where the storage battery voltage is set as an open circuit voltage has been described. However, the present invention is not limited to this.

  For example, the storage battery voltage measured at the time when a predetermined standby time has elapsed after the charging is interrupted is determined as the discharging voltage of the storage battery, and the determined discharging voltage and the storage battery voltage measured immediately before the charging is interrupted are: The open circuit voltage may be set by proportionally distributing the charging current measured immediately before the charging is interrupted and the discharging current measured when a predetermined standby time has elapsed. Hereinafter, such a case will be described as a third embodiment.

  First, the configuration of the solar cell system according to Example 3 will be described. FIG. 6 is a block diagram illustrating the configuration of the solar cell system according to the third embodiment. Here, for convenience of explanation, functional units that play the same functions as the respective units shown in FIG.

  As shown in the figure, this solar cell system includes a solar cell 1, a storage battery module 2, a load 3, a charge stop switch 31, a storage battery voltage measurement unit 6, a storage battery temperature measurement unit 7, a charge / discharge current measurement unit 8, and a control device. 300. Here, the solar cell 1 and the storage battery module 2 constitute a self-supporting power source.

  The charge stop switch 31 is connected between the solar battery 1 and the storage battery module 2 and controls charging from the solar battery 1 to the storage battery module 2. Here, when the charging stop switch 31 is turned on, a charging current flows from the solar cell 1 to the storage battery module 2 via the charging stop switch 31, and the storage battery module 2 is charged. When the charge stop switch 31 is turned off, the charging current flowing from the solar cell 1 to the storage battery module 2 via the charge stop switch 31 is interrupted, and the charging of the storage battery module 2 is interrupted.

  The control device 300 performs overall control of the solar cell system. The control device 300 is connected to the charge stop switch 31 via the switch control line 30a, and is connected to the storage battery voltage measuring unit 6 via the measurement line 9a. Moreover, the control apparatus 300 is connected to the storage battery temperature measurement part 7 via the measurement line 9b, and is connected to the charging / discharging current measurement part 8 via the measurement line 9c.

  As shown in FIG. 6, the control device 300 includes a capacity estimation start determination unit 310, an open circuit voltage setting unit 320, a voltage drop value calculation unit 130, and a storage battery capacity estimation unit 140.

  Similar to the capacity estimation start determination unit 110 in the first embodiment, the capacity estimation start determination unit 310 performs capacity estimation start determination based on the capacity estimation start condition.

  Specifically, when the charge stop switch 31 is on, the capacity estimation start determination unit 310 determines the storage battery voltage measured by the storage battery voltage measurement unit 6, the temperature measured by the storage battery temperature measurement unit 7, and the charge / discharge current. The charging current measured by the measuring unit 8 is measured.

  Then, the capacity estimation start determination unit 310 determines whether the capacity estimation start condition is satisfied based on the measured storage battery voltage, temperature, and charging current, and determines that the capacity estimation start condition is satisfied. In this case, the charging stop switch 31 is turned off to interrupt the charging.

  The open circuit voltage setting unit 320 sets the open circuit voltage of the storage battery module 2 based on the storage battery voltage measured immediately before the charging is interrupted and the storage battery voltage measured after the charging is interrupted.

  Specifically, open circuit voltage setting section 320 starts measuring time when capacity estimation start determining section 310 determines that the capacity estimation start condition is satisfied. Thereafter, the open circuit voltage setting unit 320 measures the storage battery voltage measured by the storage battery voltage measurement unit 6 and the discharge current measured by the charge / discharge current measurement unit 8 when a predetermined standby time has elapsed.

  And the open circuit voltage setting part 320 determines the storage battery voltage measured here as a discharge voltage. For example, the open circuit voltage setting unit 320 determines, as the discharge voltage, a voltage measured when 15 seconds have elapsed since charging was interrupted.

  Subsequently, the open circuit voltage setting unit 320 uses the storage battery voltage measured by the capacity estimation start determination unit 310 immediately before the determined discharge voltage and charging are interrupted, and the capacity estimation start determination unit 310 immediately before the charging is interrupted. The open circuit voltage is set by proportionally allocating at a ratio between the charging current measured by the above and the discharging current measured when a predetermined standby time has elapsed.

FIG. 7 is a diagram for explaining a method of setting an open circuit voltage in the third embodiment. In the figure, V _c indicates the battery voltage measured immediately before the charging is interrupted, V _d represents the battery voltage measured when a predetermined standby time has elapsed.

Here, assuming that the charging current measured immediately before the interruption of charging is I _c and the discharging current measured when a predetermined standby time has elapsed is I _d , the open circuit voltage setting unit 320 may, for example, The open circuit voltage V ₀ is set by the equation (2) shown in FIG.

  Next, a processing procedure for capacity estimation performed by the control device 300 according to the third embodiment will be described. FIG. 8 is a flowchart illustrating the processing procedure of capacity estimation performed by the control device 300 according to the third embodiment. As shown in the figure, in the control device 300, the capacity estimation start determining unit 310 measures the storage battery voltage, temperature, and charging current of the storage battery module 2 (step S301).

  Subsequently, the capacity estimation start determination unit 310 determines whether or not a capacity estimation start condition is satisfied based on the measured storage battery voltage, temperature, and charging current. Here, the capacity estimation start determination unit 310 repeats the measurement of the storage battery voltage, the temperature, and the charging current until the capacity estimation start condition is satisfied (No in step S302).

  And when it determines with the capacity | capacitance estimation start conditions being satisfied (step S302, Yes), the capacity | capacitance estimation start determination part 310 turns off the charge stop switch 31, and interrupts charge (step S303).

  When the charging is interrupted, the open circuit voltage setting unit 320 starts measuring time (step S304). Then, the open circuit voltage setting unit 320 measures the storage battery voltage and the discharge current of the storage battery module 2 when the predetermined standby time has elapsed (step S305, Yes), and uses the measured voltage as the discharge voltage. decide.

  Subsequently, the open circuit voltage setting unit 320 uses the determined discharge voltage and the storage battery voltage measured by the capacity estimation start determination unit 310 as a ratio between the measured discharge current and the charge current measured by the capacity estimation start determination unit 310. The open circuit voltage is set by proportionally allocating (step S307).

  When the open circuit voltage is set, the voltage drop value calculating unit 130 calculates a voltage drop value between the storage battery voltage just before the charging is interrupted and the open circuit voltage set by the open circuit voltage setting unit 320. (Step S308). Then, the storage battery capacity estimation unit 140 estimates the capacity of the storage battery module 2 based on the voltage drop value calculated by the voltage drop value calculation unit 130 (step S309).

  As described above, in the third embodiment, the open circuit voltage setting unit 320 determines the storage battery voltage measured when a predetermined standby time has elapsed after the charging is interrupted as the discharge voltage of the storage battery module 2. The determined discharge voltage and the storage battery voltage measured immediately before the charging is interrupted, the ratio of the charging current measured immediately before the charging is interrupted and the discharge current measured when a predetermined standby time has elapsed. The open circuit voltage is set by proportionally allocating. Therefore, according to the third embodiment, it is possible to estimate the capacity of the storage battery even when the open circuit voltage cannot be measured.

  By the way, in the said Example 3, the case where the storage battery voltage measured when the predetermined | prescribed standby | waiting time passed after charging was interrupted was determined as a discharge voltage was demonstrated. However, the present invention is not limited to this.

  For example, the change amount of the storage battery voltage may be calculated at every predetermined time interval after the charging is interrupted, and the storage battery voltage at the time when the calculated change amount becomes a predetermined threshold value or less may be determined as the discharge voltage. Hereinafter, such a case will be described as a fourth embodiment.

  Note that the configurations of the solar cell system and the control device in the fourth embodiment are basically the same as those shown in FIG. 6, and only the processing performed by the open circuit voltage setting unit 320 is different. Therefore, here, the processing procedure of capacity estimation performed by the control device 300 according to the fourth embodiment will be described focusing on the processing performed by the open circuit voltage setting unit 320.

  FIG. 9 is a flowchart illustrating the processing procedure of capacity estimation performed by the control device 300 according to the fourth embodiment. In the same figure, the processes (steps S401 to S403) until the charging is interrupted by the capacity estimation start determination unit 310 are the same as the processes of steps S301 to S303 shown in FIG.

  When charging is interrupted, the open circuit voltage setting unit 320 starts measuring time (step S404). Then, the open circuit voltage setting unit 320 measures the storage battery voltage and the discharge current of the storage battery module 2 when a predetermined time has elapsed (step S405, Yes) (step S406).

  Subsequently, the open circuit voltage setting unit 320 calculates a voltage drop gradient from the amount of change between the storage battery voltage measured last time and the storage battery voltage measured this time (step S407). Here, the open circuit voltage setting unit 320 repeats the processes of steps S404 to S407 described above without determining the discharge voltage while the voltage drop gradient exceeds the predetermined threshold (No in step S408).

  When the voltage drop gradient becomes equal to or less than the predetermined threshold, the open circuit voltage setting unit 320 determines the storage battery voltage at that time as the discharge voltage (Yes in step S408).

  For example, the open circuit voltage setting unit 320 measures the voltage of the storage battery module 2 with an accuracy of 10 mV every 5 seconds after the charging is interrupted, and the amount of change in the storage voltage (voltage drop gradient) becomes zero. The storage voltage is set as the discharge voltage. In that case, for example, if the amount of change between the voltage after 10 seconds and the voltage after 15 seconds is zero after the charging is interrupted, and the voltage measured at the time after 15 seconds is 13.12 V, The discharge voltage is 13.45V.

  Subsequently, the open circuit voltage setting unit 320 uses the determined discharge voltage and the storage battery voltage measured by the capacity estimation start determination unit 310 as a ratio between the measured discharge current and the charge current measured by the capacity estimation start determination unit 310. The open circuit voltage is set by proportionally allocating (step S409).

  When the open circuit voltage is set, the voltage drop value calculation unit 130 calculates a voltage drop value between the storage battery voltage just before the charging is interrupted and the open circuit voltage set by the open circuit voltage setting unit 120. (Step S410). Then, the storage battery capacity estimation unit 140 estimates the capacity of the storage battery module 2 based on the voltage drop value calculated by the voltage drop value calculation unit 130 (step S411).

  As described above, in the fourth embodiment, the open circuit voltage setting unit 320 calculates the change amount of the storage battery voltage at every predetermined time interval after the charging is interrupted, and the calculated change amount is equal to or less than the predetermined threshold value. The storage battery voltage at that time is determined as the discharge voltage of the storage battery module 2. Therefore, according to the fourth embodiment, even when it is impossible to actually measure the open circuit voltage and the time until the discharge state is different for each storage battery, the timing at which the discharge state is set for each storage battery is accurately determined. It is possible to detect and estimate the capacity.

  As mentioned above, although Example 1-4 which concerns on this invention was demonstrated, according to these Examples, it became possible to estimate the capacity | capacitance of storage batteries, such as a nickel hydride storage battery used with a self-supporting power supply, and the extent of deterioration of a storage battery And the need for replacement.

  As described above, the storage battery capacity estimation device and the storage battery capacity estimation method according to the present invention are useful when estimating the capacity of a storage battery used in a self-supporting power source, and particularly when estimating the capacity of a nickel metal hydride storage battery. Is suitable.

1 is a block diagram illustrating a configuration of a solar cell system according to Example 1. FIG. It is a figure for demonstrating the setting method of the open circuit voltage in the present Example 1. FIG. 3 is a flowchart illustrating a processing procedure of capacity estimation by the control device according to the first embodiment. It is a figure for demonstrating the specific example of the capacity | capacitance estimation in the present Example 1. FIG. 12 is a flowchart illustrating a processing procedure of capacity estimation by the control device according to the second embodiment. It is a block diagram which shows the structure of the solar cell system which concerns on the present Example 3. It is a figure for demonstrating the setting method of the open circuit voltage in the present Example 3. FIG. 12 is a flowchart illustrating a processing procedure of capacity estimation by a control device according to the third embodiment. 14 is a flowchart illustrating a processing procedure of capacity estimation by a control device according to a fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Storage battery module 3 Load 4 Backflow prevention diode 5, 31 Charge stop switch 6 Storage battery voltage measurement part 7 Storage battery temperature measurement part 8 Charge / discharge current measurement part 9a, 9b, 9c Measurement line 10, 20a, 20b, 30a Switch control Lines 21, 22 Switches 100, 200, 300 Controllers 110, 310 Capacity estimation start determination units 120, 320 Open circuit voltage setting unit 130 Voltage drop value calculation unit 140 Storage battery capacity estimation unit

Claims (8)

A storage battery capacity estimation device for estimating the capacity of a storage battery,
An open circuit voltage setting means for setting the open circuit voltage of the storage battery based on the storage battery voltage measured immediately before the charge is interrupted and the storage battery voltage measured after the charge is interrupted;
Voltage drop value calculating means for calculating a voltage drop value between the storage battery voltage measured immediately before charging is interrupted and the open circuit voltage set by the open circuit voltage setting means;
A storage battery capacity estimation means for estimating the capacity of the storage battery based on the voltage drop value calculated by the voltage drop value calculation means;
A storage battery capacity estimation device comprising:   2. The storage battery capacity estimation according to claim 1, wherein the open circuit voltage setting unit sets a storage battery voltage measured when a predetermined standby time has elapsed after charging is interrupted as the open circuit voltage. apparatus.   The open circuit voltage setting means calculates a change amount of the storage battery voltage at predetermined time intervals after the charging is interrupted, and the storage battery voltage at the time when the calculated change amount becomes equal to or less than a predetermined threshold value. The storage battery capacity estimation apparatus according to claim 1, which is set as a voltage.   The open circuit voltage setting means determines a storage battery voltage measured when a predetermined standby time has elapsed after charging is interrupted as a discharging voltage of the storage battery, and immediately before the determined discharging voltage and charging are interrupted. By dividing the measured storage battery voltage proportionally by the ratio of the charging current measured immediately before the interruption of charging and the discharging current measured when the predetermined standby time has elapsed, the open circuit voltage is The storage battery capacity estimation apparatus according to claim 1, wherein the storage battery capacity estimation apparatus is set.   The open circuit voltage setting means calculates a change amount of the storage battery voltage at every predetermined time interval after the charging is interrupted, and the storage battery voltage at the time when the calculated change amount becomes equal to or less than a predetermined threshold value. Determined as the discharge voltage, the determined discharge voltage and the storage battery voltage measured immediately before the charging is interrupted are measured when the charging current measured immediately before the charging is interrupted and the predetermined waiting time has elapsed. 2. The storage battery capacity estimation apparatus according to claim 1, wherein the open circuit voltage is set by proportionally distributing in proportion to the discharged current.   The storage battery capacity estimation means calculates the internal resistance value of the storage battery based on the voltage drop value calculated by the voltage drop value calculation means, and measures the calculated internal resistance value and the capacity of the storage battery in advance as a reference value. The capacity of the storage battery is estimated by comparing with a reference resistance value defined as a function of the temperature of the storage battery based on the internal resistance value. The storage battery capacity estimation apparatus according to one. Capacity estimation start determining means for determining to start capacity estimation when the estimated charging rate or charging voltage of the storage battery is equal to or greater than a predetermined threshold and a predetermined period has elapsed since the end of the previous capacity determination; Prepared,
The said open circuit voltage setting means sets the said open circuit voltage, when it determines with the capacity | capacitance estimation start determination means having started capacity | capacitance estimation, The open circuit voltage is set as described in any one of Claims 1-6 characterized by the above-mentioned. Storage battery capacity estimation device. A storage battery capacity estimation method for estimating the capacity of a storage battery,
An open circuit voltage setting step for setting an open circuit voltage of the storage battery based on a storage battery voltage measured immediately before the charging is interrupted and a storage battery voltage measured after the charging is interrupted;
A voltage drop value calculating step for calculating a voltage drop value between the storage battery voltage measured immediately before charging is interrupted and the open circuit voltage set by the open circuit voltage setting step;
A storage battery capacity estimation step for estimating the capacity of the storage battery based on the voltage drop value calculated by the voltage drop value calculation step;
A storage battery capacity estimation method comprising:

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