WO2018066243A1 - Lead-acid battery device, uninterruptible power source, power source system, lead-acid battery control device, and lead-acid battery charging method - Google Patents

Abstract

This lead-acid battery device may be equipped with a lead-acid battery. This lead-acid battery device may be equipped with a charging control unit that charges the lead-acid battery by repeating alternately high-voltage charging, which applies a pulsed high-voltage to the lead-acid battery, and low-voltage charging, which applies to the lead-acid battery a low voltage that is lower than the high voltage. This lead-acid battery device may be equipped with a high-voltage setting unit for raising the high voltage applied to the lead-acid battery during the high-voltage charging when the cell voltage variation among a plurality of battery cells in the lead-acid battery is greater than a predetermined value.

Description

Lead storage battery device, uninterruptible power supply, power supply system, lead storage battery control device, lead storage battery charging method

The present invention relates to a lead storage battery device, an uninterruptible power supply, a power supply system, a lead storage battery control device, and a lead storage battery charging method.

A technique for increasing the charging voltage when the voltage per cell of a certain group with respect to the voltage per cell of the entire assembled battery having a plurality of cells is reduced by 20 mV or more (for example, see Patent Document 1), There exists a technique (for example, refer patent document 2) which changes a charging current or a charging voltage by the comparison result of these.
Patent Document 1 Japanese Patent Application Laid-Open No. 8-17473 Patent Document 2 Japanese Patent Application Laid-Open No. 51-85437

Challenges to be solved

単 に Simply increasing the charging voltage may greatly promote overcharge degradation of some battery cells.

General disclosure

In the first aspect of the present invention, the lead storage battery device may include a lead storage battery. The lead storage battery device is a charge control that charges a lead storage battery by alternately repeating high voltage charging that applies a pulsed high voltage to the lead storage battery and low voltage charging that applies a low voltage lower than the high voltage to the lead storage battery. May be provided. The lead-acid battery device may include a high-voltage setting unit that increases a high voltage applied to the lead-acid battery in high-voltage charging when the cell voltage variation of the plurality of battery cells included in the lead-acid battery is larger than a predetermined value. .

The high voltage setting unit may increase the time for performing high voltage charging when increasing the high voltage.

The high voltage setting unit may shorten the time interval for performing low voltage charging when increasing the high voltage.

The high voltage setting unit reads lead in high voltage charging when the variation in the cell voltage of the plurality of battery cells after the high voltage charging is performed with the high voltage increased by the high voltage setting unit is larger than a predetermined value. The high voltage applied to the storage battery may be further increased.

The high voltage setting unit may reduce the high voltage to a predetermined voltage when variations in cell voltages of the plurality of battery cells are equal to or less than a predetermined value.

The high voltage setting unit determines the high voltage in advance when the cell voltage variation of the plurality of battery cells is larger than the cell voltage variation of the plurality of battery cells before the high voltage setting unit increases the high voltage. The voltage may be lowered to

The high voltage setting unit calculates the difference between the average value of the cell voltages of the plurality of battery cells and the cell voltage of the plurality of battery cells, and there is a battery cell in which the magnitude of the difference is greater than a predetermined value. High voltage may be increased.

The high voltage setting unit calculates a difference between the average value of the cell voltages of the plurality of battery cells and the cell voltage of the plurality of battery cells, and the magnitude of the difference is larger than a predetermined value and lower than the average value. When a battery cell having a cell voltage is present, the high voltage may be increased.

In the second aspect of the present invention, the uninterruptible power supply may include a lead storage battery device.

In the third aspect of the present invention, the power supply system may include a lead storage battery device.

In the fourth aspect of the present invention, the lead storage battery control device performs high voltage charging for applying a pulsed high voltage to the lead storage battery and low voltage charging for applying a low voltage lower than the high voltage to the lead storage battery. You may provide the charge control part which charges a lead storage battery by repeating alternately. The control device may include a high voltage setting unit that increases a high voltage applied to the lead storage battery in high voltage charging when the variation in the cell voltage of the plurality of battery cells included in the lead storage battery is larger than a predetermined value.

In the fifth aspect of the present invention, a method for charging a lead storage battery includes a high voltage charge for applying a pulsed high voltage to the lead storage battery and a low voltage charge for applying a low voltage lower than the high voltage to the lead storage battery. It may be repeated alternately. In the charging method, when the variation in the cell voltage of the plurality of battery cells of the lead storage battery is larger than a predetermined value, the high voltage applied to the lead storage battery in the high voltage charging may be higher than the voltage applied last time.

The above summary of the invention does not enumerate all the features of the present invention. A sub-combination of these feature groups can also be an invention.

1 schematically illustrates functional blocks and load 90 of a power supply system 120 in one embodiment. The timing chart of the charging voltage of the secondary battery 40 is shown typically. The timing chart of the charging voltage when _VH is raised by the setting unit 33 is schematically shown. An example of the waveform of the voltage between electrodes of a battery cell at the time of applying a high voltage in intermittent charge is shown typically. 3 is a flowchart showing a method for controlling secondary battery 40 by control device 30.

Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

FIG. 1 schematically shows functional blocks and a load 90 of the power supply system 120 according to an embodiment. The power supply system 120 includes the power supply device 10 and the power storage system 20. Power supply device 10 is connected to input terminal 12 of power storage system 20. A load 90 is connected to the output terminal 14 of the power storage system 20. The power supply device 10 may be an AC power supply. The load 90 may be a load that operates with alternating current. The power storage system 20 may be used in an uninterruptible power supply (UPS). The power storage system 20 may be used in a power generation device such as a solar power generation device, a wind power generation device, or a fuel cell device.

The power storage system 20 includes a converter 22, an inverter 24, and a secondary battery device 100. The secondary battery device 100 includes a control device 30, a secondary battery 40, a charge / discharge device 50, and a cell voltage measurement device 60. The control device 30 includes a charge / discharge control unit 31 and a setting unit 33. In FIG. 1, the electrical connection of the power supply device 10, the converter 22, the inverter 24, the secondary battery 40, the charging / discharging device 50, and the load 90 is shown by a single line diagram.

One end of the charging / discharging device 50 is electrically connected to the node 16 between the converter 22 and the inverter 24. The other end of the charging / discharging device 50 is electrically connected to the secondary battery 40.

The converter 22 converts the alternating current output from the power supply device 10 into a direct current. The direct current converted by the converter 22 can be output to at least one of the inverter 24 and the charge / discharge device 50. The charging / discharging device 50 performs charging / discharging of the secondary battery 40. Specifically, the charging / discharging device 50 has a charging circuit that converts a direct current from the converter 22 into a direct current for charging the secondary battery 40 and outputs the same to the secondary battery 40 side. The secondary battery 40 is charged by a charging direct current output from the charging / discharging device 50. In addition, charging / discharging device 50 includes a discharge circuit that converts a direct current output from secondary battery 40 into a direct current for power supply and outputs the direct current to node 16 side. The direct current for feeding is supplied to the inverter 24. The control device 30 controls charging / discharging of the secondary battery 40 by controlling the charging / discharging device 50. The control device 30 functions as a charge control device for the secondary battery 40. The control device 30 functions as a discharge control device for the secondary battery 40.

The inverter 24 converts at least one of the direct current output from the converter 22 and the direct current output from the charging / discharging device 50 into an alternating current and outputs the alternating current. The alternating current output from the inverter 24 is supplied to the load 90. When the load 90 operates with direct current, the inverter 24 may be omitted. Further, when the power supply device 10 supplies direct current, the converter 22 may be omitted.

During normal operation, the power supply system 120 may supply the power of the power supply device 10 to the load 90 via the converter 22 and the inverter 24. Further, during normal operation, the control device 30 may charge the secondary battery 40 with the power of the power supply device 10. During the non-normal operation, the power storage system 20 may supply the power stored in the secondary battery 40 to the load 90.

When the power storage system 20 is used for a UPS, when the input power is normal, power is supplied from the power supply device 10 to the load 90 via the converter 22 and the inverter 24. On the other hand, when the input power supply is abnormal, such as a power failure, power is supplied from the secondary battery 40 to the load 90 via the charging / discharging device 50 and the inverter 24. When the input power supply is abnormal, for example, for power from the power supply device 10, when at least one of the voltage and frequency is out of the steady state and the transient fluctuation range, or the distortion or power interruption time is a predetermined limit value. May be exceeded. In addition, when the electrical storage system 20 is used for UPS, the power supply device 10 may be a commercial AC power supply. The power supply device 10 may be a power source other than a commercial AC power source. The power supply system 120 may include a direct transmission circuit that bypasses the power storage system 20 and supplies the power of the power supply device 10 to the load 90 without passing through the input terminal 12 and the output terminal 14.

Further, when the power storage system 20 is used for a power generation device, the power supply device 10 may be a generator. For example, the power supply device 10 may be a generator such as a solar cell, a wind power generator, a fuel cell, or an internal combustion power generator. In this case, the power storage system 20 may function as an auxiliary power source for the power supply device 10. When the output of the power supply device 10 is a specified value, power is supplied from the power supply device 10 to the load 90 via the converter 22 and the inverter 24. In this case, the secondary battery 40 may be charged with surplus power that is not consumed by the load 90 among the power from the power supply device 10. On the other hand, when an abnormality occurs in the power supply device 10, power is supplied from the secondary battery 40 to the load 90 via the charging / discharging device 50 and the inverter 24. Further, when the power supplied from the power supply device 10 to the load 90 is smaller than the power required by the load 90, the power shortage from the secondary battery 40 to the load 90 via the charging / discharging device 50 and the inverter 24. May be supplied.

The secondary battery 40 is a lead storage battery. The secondary battery 40 includes at least one positive electrode and at least one negative electrode as electrodes, a separator provided between the positive electrode and the negative electrode, and an electrolyte that fills a space in which the positive electrode, the negative electrode, and the separator are provided. It has the above battery cell. The secondary battery 40 may be a unit having six battery cells connected in series, for example. In the secondary battery 40, the battery cell refers to the minimum unit of a lead storage battery having a pair of positive and negative electrodes connected in series. In the present embodiment, the secondary battery 40 includes six battery cells connected in series, unless otherwise specified for the number of battery cells.

The cell voltage measuring device 60 measures the terminal voltage of the battery cell of the secondary battery 40. The measured value of the cell voltage by the cell voltage measuring device 60 is supplied to the control device 30.

The control device 30 intermittently charges the secondary battery 40 by controlling the charge / discharge device 50. In the control device 30, the charge / discharge control unit 31 alternately performs high voltage charging for applying a pulsed high voltage to the secondary battery 40 and low voltage charging for applying a low voltage lower than the high voltage to the secondary battery 40. The secondary battery 40 is charged by repeating the above. Intermittent means that there are repeated periods in which no high voltage is applied.

Here, the deterioration of the negative electrode and the positive electrode of the lead storage battery will be described. In a lead storage battery, the following half reaction proceeds during charging.
(Positive electrode reaction) PbSO ₄ + 2H ₂ O → PbO ₂ + 4H ⁺ + SO ₄ ^{2 −} + 2e ⁻
(Negative electrode reaction) PbSO ₄ + 2e ⁻ → Pb + SO ₄ ²⁻
Further, at the time of discharging, the following half reaction that is opposite to that at the time of charging proceeds.
(Positive electrode reaction) PbO ₂ + 4H ⁺ + SO ₄ ^{2 −} + 2e ⁻ → PbSO ₄ + 2H ₂ O
(Negative electrode reaction) Pb + SO ₄ ²⁻ → PbSO ₄ + 2e ⁻
In lead-acid batteries, sulfation may be promoted by lead sulfate formed on the negative electrode by discharge.

The lead sulfate formed on the electrode can be decomposed and returned to the electrolyte if it is fully charged quickly. However, if the state in which the lead sulfate is adhered continues, the lead sulfate formed on the electrode crystallizes and hardens. When lead sulfate is hardened, the above reaction does not substantially occur even by charging. Therefore, the crystallized lead sulfate covers the electrode, thereby reducing the effective area of the electrode. This makes it difficult for the reaction at each electrode to proceed, and the discharge performance can be reduced. In addition, as the amount of crystallized lead sulfate increases, lead ions and sulfate ions in the electrolytic solution responsible for the accumulation of electrical energy decrease. Therefore, as the crystallized lead sulfate increases, the power storage performance can be lowered. In some cases, it may be difficult to charge the lead storage battery. In this way, the negative electrode can be degraded primarily by lead sulfate.

Also, when the lead storage battery is overcharged, the water in the electrolyte is electrolyzed and lost outside the lead storage battery. Moreover, electrolyte solution is lost outside lead acid battery by evaporation, moisture permeability, etc. Thereby, electrolyte solution concentration can rise with time. For example, the loss of moisture in the electrolytic solution can increase the sulfuric acid concentration over time when the charge rate of the lead storage battery is a specified value. Thereby, corrosion of the electrode grid of the positive electrode proceeds. In this way, the deterioration of the positive electrode proceeds.

In the power supply system 120, the secondary battery 40 is charged by alternately repeating high voltage charging and low voltage charging under the control of the charge / discharge control unit 31. Since the low voltage charging period exists, it is possible to suppress water in the electrolytic solution from being lost from the secondary battery due to electrolysis. Moreover, decomposition | disassembly of the lead sulfate formed in the negative electrode can be accelerated | stimulated by switching and applying a low voltage and a high voltage. Thereby, deterioration of the electrode of the secondary battery 40 can be suppressed. Specific examples of intermittent charging and suppression of electrode deterioration will be described later.

In addition, a lead storage battery is manufactured using a plurality of battery cells in order to ensure a desired voltage and a desired capacity. The plurality of battery cells have different battery characteristics such as charge characteristics and self-discharge characteristics due to individual differences. The lead storage battery is normally charged by collectively applying a charging voltage to the entire lead storage battery. Therefore, the cell voltage varies due to the difference in battery characteristics of each battery cell. Even if the difference in battery characteristics of the battery cells is slight, the variation in the cell voltage increases as the operation period of the lead storage battery becomes longer. As a result, when a state in which a battery cell with insufficient charge and a battery cell without insufficient charge coexist in one lead storage battery continues, the sulfate is converted into a negative electrode in a specific battery cell with insufficient charge. The attached state continues and lead sulfate becomes hard. If a high charging voltage is continuously applied to decompose lead sulfate in a specific battery cell, it will overcharge the battery cell that is not insufficiently charged. Deterioration may be greatly advanced. Therefore, when the charging voltage for trickle charging or float charging is increased, the deterioration of the secondary battery 40 may be accelerated instead.

In the control device 30, the charge / discharge control unit 31 applies a voltage to the secondary battery 40 so as to equalize the cell voltages of the plurality of battery cells included in the secondary battery 40 while suppressing overcharge deterioration of the positive electrode. To control. Specifically, the setting unit 33 applies to the secondary battery 40 in pulsed high-voltage charging when the variation in the cell voltage of the plurality of battery cells included in the secondary battery 40 is larger than a predetermined value. Increase high voltage. Thereby, the high voltage of the high voltage charge performed on both sides of low voltage charge can be raised. Since high voltage charging is performed across low voltage charging, the comparison required to equalize the cell voltage of the battery cells while lowering the average charging voltage compared to the case where high voltage is continuously applied A period during which a high voltage is applied can be provided. Therefore, it is possible to suppress overcharging of the battery cells in which insufficient charging has occurred. In addition, as described later, switching from low voltage charging to high voltage charging can increase the amount of charge of a battery cell that has deteriorated, thereby suppressing overcharge of a battery cell that is not insufficiently charged. However, the cell voltage of the battery cell can be made uniform.

When the high voltage is increased, the setting unit 33 may lengthen the time for performing high voltage charging. Thereby, charge of the battery cell in which insufficient charge has arisen can be accelerated | stimulated. The setting unit 33 may shorten the time interval for performing low-voltage charging when increasing the high voltage. Thereby, it is possible to suppress overcharging of the battery cells that are not insufficiently charged while promoting the charging of the battery cells that are insufficiently charged. In addition, it is possible to suppress the hardening of lead sulfate and to promote the uniformization of the cell voltage.

The setting unit 33 is configured to recharge the secondary battery in the high voltage charging when the variation in the cell voltages of the plurality of battery cells after the high voltage charging is performed with the high voltage increased by the setting unit 33 is larger than a predetermined value. The high voltage applied to 40 may be further increased. Thereby, the high voltage in high voltage charge can be raised in steps. Therefore, it is possible to promote uniform cell voltage.

The setting unit 33 may reduce the high voltage to a predetermined value when the variation in the cell voltage of the plurality of battery cells is equal to or less than a predetermined value. Thereby, the overcharge of the battery cell in which insufficient charging has not occurred can be suppressed.

The setting unit 33 sets the high voltage to a predetermined value when the cell voltage variation of the plurality of battery cells is larger than the cell voltage variation of the plurality of battery cells before the setting unit 33 increases the high voltage. The voltage may be lowered to Thereby, the overcharge of the battery cell in which insufficient charging has not occurred can be suppressed.

The setting unit 33 calculates the difference between the average value of the cell voltages of the plurality of battery cells and the cell voltage of the plurality of battery cells, and there is a battery cell in which the magnitude of the difference is greater than a predetermined value. In addition, the high voltage may be increased. More specifically, the setting unit 33 calculates the difference between the average value of the cell voltages of the plurality of battery cells and the cell voltage of the plurality of battery cells, and the magnitude of the difference is greater than a predetermined value, and When there is a battery cell having a cell voltage lower than the average value, the high voltage may be increased.

The setting unit 33 may calculate the difference between the average value of the cell voltages of the plurality of battery cells and the minimum value of the cell voltages of the plurality of battery cells as the cell voltage variation. The setting unit 33 may calculate the difference between the maximum value of the cell voltages of the plurality of battery cells and the average value of the cell voltages of the plurality of battery cells as the variation in the cell voltage. The setting unit 33 may calculate a difference between the maximum value of the cell voltages of the plurality of battery cells and the minimum value of the cell voltages of the plurality of battery cells as the variation in the cell voltage. The setting unit 33 may calculate the cell voltage variation by any other calculation method.

The setting unit 33 may increase the high voltage without increasing the low voltage applied to the secondary battery 40 in the high voltage charging when the variation of the cell voltages of the plurality of battery cells is larger than a predetermined value. Thereby, the overcharge of the battery cell in which insufficient charging has not occurred can be suppressed.

The setting unit 33 applies not only the high voltage applied in the high voltage charging but also the secondary battery 40 in the low voltage charging when the cell voltage variation of the plurality of battery cells is larger than a predetermined value. Low voltage may be increased. In this case, the increase amount of the high voltage may be larger than the increase amount of the low voltage. The value of the low voltage may remain constant or be changed.

As described above, according to the control device 30, it is possible to equalize the cell voltage of the battery cells while suppressing overcharge of the battery cells that are not insufficiently charged.

FIG. 2 schematically shows a timing chart of the charging voltage of the secondary battery 40. The horizontal axis of the timing chart in FIG. 2 indicates time. The vertical axis of the timing chart in FIG. 2 indicates voltage. As shown in the timing chart of FIG. 2, the charge / discharge control unit 31 charges the secondary battery 40 by intermittent charging.

T _H indicates the time length of a high voltage charging period in which a high voltage is applied between the terminals of the secondary battery 40. On the horizontal axis, ts indicates one of the times when the application of the high voltage starts from the state where the low voltage is applied, and te indicates one of the times when the application of the low voltage starts. Therefore, T _H = te−ts. The charge / discharge control unit 31 switches the voltage applied to the secondary battery 40 from the low voltage to the high voltage at ts, and switches the voltage applied to the secondary battery 40 from the high voltage to the low voltage at te.

Discharge control unit 31 controls the charging and discharging device 50, one cycle one or more times with a T _L for applying a low voltage to the T _H and a secondary battery 40 for applying a high voltage to the secondary battery 40 By repeating, the secondary battery 40 is intermittently charged. V _H , V _L , T _H and T _L are examples of charging parameters set by the setting unit 33 in intermittent charging.

In the high voltage charging, the charge / discharge control unit 31 applies a pulsed high voltage to the secondary battery 40 by controlling the charge / discharge device 50. Pulsed high voltage shown in FIG. 2, has a square wave shape with a peak voltage value V _H determined in advance. The pulsed high voltage may mean a voltage waveform in which the voltage value increases sharply in a short time. The pulsed high voltage may have a waveform shape of a partial period including a peak in a sine wave, a triangular wave, or a saw wave, for example, in addition to a rectangular wave.

Here, V _H , V _L , T _H, and T _L are exemplified to show the values of V _H , V _L , T _H, and T _H for the purpose of explaining the effect obtained by intermittent charging. Specific numerical values of _TL are exemplified.

T _H is, for example, 60 seconds. _TL is, for example, 3600 seconds. The intermittent charging, since a high voltage is applied in a pulsed manner, it is possible to shorten the T _H. As the _TH is shorter, the water in the electrolytic solution can be prevented from being lost from the secondary battery due to electrolysis. Moreover, by applying a pulsed high voltage, lead sulfate generated in the negative electrode may be easily decomposed. Further, by shortening the T _H, it can suppress deterioration of the positive electrode of the secondary battery 40. For example, volume expansion caused by lead oxide formed on the positive electrode can be suppressed.

V _H may be a specification value specified by the battery manufacturer. The specification value may be 13.65V. Accordingly, a voltage of 2.275 V (= 13.65 V / 6) may be applied to each battery cell as V _H. Note that the value of V _H may be changed according to the specifications of the secondary battery 40.

V _L is, for example, 12.6V. In this case, within the period of T _L, the voltage of 2.1V per battery cell is applied. Note that _VL may be higher than 0V. V _L may be equal to or greater than the electromotive force during complete discharge of the secondary battery 40. For example, when the electromotive force at the time of complete discharge of one battery cell is 1.95V, _{V L} may be more than 11.7 V.

When the applied voltage to the lead storage battery is extremely low, self-discharge proceeds, and lead sulfate formation and crystallization proceeds at the negative electrode. For example, when the charging voltage is 0 V, crystallization of lead sulfate easily proceeds at the negative electrode. On the other hand, in the electrical storage system 20, the progress of crystallization of lead sulfate can be suppressed by making _VL higher than 0V. Moreover, the progress of crystallization of lead sulfate can also be suppressed by setting _VL equal to or higher than the electromotive force during complete discharge. In this way, the charge / discharge control unit 31 applies a voltage value that can suppress the deterioration of the negative electrode of the secondary battery 40 to the secondary battery 40 during the low-voltage charging period.

Note that V _L may be 74% or more of the theoretical electromotive force in the secondary battery 40. For example, when the theoretical electromotive force of one battery cell is 2.04, _{V L} may be more than 9.06V. _VL may be 93% or more of the theoretical electromotive force in the secondary battery 40. For example, when the theoretical electromotive force of one battery cell is 2.04, _{V L} may be more than 11.4 V. The case where _VL is 74% or more or 93% or more of the theoretical electromotive force may mean that the instantaneous minimum value in the low voltage charging period is 74% or more or 93% or more of the theoretical electromotive force. When _VL is 74% or more or 93% or more of the theoretical electromotive force, there can be a certain effect in suppressing sulfation.

Further, _VL may be equal to or lower than the electromotive force when the secondary battery 40 is fully charged. When the electromotive force of the full charge when the one battery cell is 2.1V, _{V L} may be less 12.6V.

Further, V _L may be 121% or less of the voltage value of the theoretical electromotive force in the secondary battery 40. When the theoretical electromotive force of one battery cell is 2.04V, _VL may be 14.8V or less.

In addition, _{T L} may be longer than the _{T H.} Moreover, _TH may be 60 seconds and _TL may be 240 seconds or more. Moreover, _TH may be 60 seconds and _TL may be 30 minutes or more. _TH may be 60 seconds and _TL may be 1 hour or longer. _TH may be 60 seconds and _TL may be 2 hours or more. Thus, the ratio of _{T L} and _{T H} can be a _{4 ≦ T L / T H,} 30 ≦ T L / T H, 60 ≦ T L / T H, or 120 ≦ _T L / _{T H} .

Moreover, _TH may be 60 seconds and _TL may be 5 hours or less. _TH may be 60 seconds and _TL may be 3 hours or less. Thus, the ratio of _{T L} and _{T H can} be set to T L / _{T H} ≦ 180 or _T L / _{T H} ≦ 300. In particular, in lead-acid batteries, it has been confirmed in experiments by the inventors of the present application that the deterioration of the negative electrode may be accelerated when _TL is 3 hours or more and 5 hours or less. Therefore, it can be said that setting _TL to 5 hours or less, more preferably 3 hours or less is effective in suppressing deterioration of the lead-acid battery.

FIG. 3 schematically shows a timing chart of the charging voltage when V _H is increased by the setting unit 33. In the waveform of FIG. 3, the horizontal axis indicates time and the vertical axis indicates voltage. ts and te correspond to ts and te in FIG. 2, respectively. A waveform 300 shows a charging voltage waveform when V _H is a specified value. A waveform 310 indicates a charging voltage waveform when the setting unit 33 increases _VH .

In the example of this figure, the specified value of _VL is 12.6V. In this case, the average voltage applied to one battery cell is 2.1V. Specified value of V _H is 13.38V. In this case, the average voltage applied to one battery cell is 2.23V.

If it is determined that the cell voltage varies, the setting unit 33 increases _VH by 60 mV per battery cell. That is, the setting unit 33 increases the voltage applied to the secondary battery 40 in the high voltage charging to 13.74V. Thereby, the average value of the voltage applied to one battery cell in high voltage charge increases to 2.29V. Note that the setting unit 33 maintains _VL at 12.6 V even when it is determined that the cell voltage has varied.

When it is determined that the cell voltage variation has been eliminated, the setting unit 33 reduces V _H to a specified value. The setting unit 33 maintains _VL at 12.6V even when the variation in the cell voltage is eliminated.

FIG. 4 schematically shows an example of the waveform of the voltage between the electrodes of the battery cell when a high voltage is applied in intermittent charging. In the waveform of FIG. 4, the horizontal axis indicates time and the vertical axis indicates voltage. ts and te correspond to ts and te in FIGS. 2 and 3, respectively.

The waveform 400 shows the voltage waveform of the battery cell in which charging is insufficient. That is, the waveform 400 shows the voltage waveform of the battery cell with a lot of lead sulfate formed on the electrode. A waveform 410 shows a voltage waveform of a battery cell in which insufficient charging has occurred. That is, the waveform 410 shows a voltage waveform of a battery cell with a small amount of lead sulfate formed on the electrode.

In general, battery cells with insufficient charge have more lead sulfate formed on the electrodes than battery cells without insufficient charge. The liquid concentration is low. Therefore, the electromotive force of the battery cell in which insufficient charging has occurred is lower than the electromotive force of the battery cell in which insufficient charging has occurred. Therefore, when a high voltage is applied, the cell voltage of the battery cell that is insufficiently charged rises relatively quickly. On the other hand, since the electromotive force of the battery cell that is not insufficiently charged is higher than the electromotive force of the battery cell that is insufficiently charged, the battery cell that is not insufficiently charged when the same high voltage is applied. The cell voltage rises only slowly compared to the cell voltage of the battery cell in which charging is insufficient. That is, during the high voltage charging period, the charge amount of the battery cell in which insufficient charging has occurred is greater than the charge amount of the battery cell in which insufficient charge has occurred. Therefore, by increasing the high voltage, the cell voltage variation in the secondary battery 40 can be effectively reduced.

In addition, in a battery cell in which insufficient charging has not occurred, there is a possibility that electrolysis of water in the electrolyte solution occurs during the high voltage charging period. However, when electrolysis occurs, an increase in cell voltage is suppressed by the electrolysis reaction overvoltage. Therefore, since overcharge of the battery cell in which insufficient charging has not occurred is suppressed, variation in cell voltage in the secondary battery 40 is reduced.

Also, by applying a high voltage in a pulsed manner, the voltage rise is slow for battery cells that are not insufficiently charged, so the time-average voltage value can be kept low, while a large amount of lead sulfate is generated due to insufficient charging. For battery cells, lead sulfate with poor electrical conductivity increases the battery resistance and the voltage rises quickly, so the time-average voltage value is kept higher than undercharged batteries, and the effect of reducing voltage variation is obtained. .

As described above, by applying a high voltage in a pulsed manner, it is possible to eliminate the insufficient charging of the insufficiently charged battery cell and at the same time minimize the influence on the battery cell that is not insufficiently charged.

FIG. 5 is a flowchart showing a method for controlling the secondary battery 40 by the control device 30. The control device 30 may be a main body that controls the operation of each stage in this control method. In order to realize this, the control device 30 may include a processing device such as a CPU or an ASIC, a memory, and the like. Note that the flowchart in FIG. 5 only shows an example of a control method in the power storage system 20. Each step of the flowchart of FIG. 5 may be appropriately recombined, some steps of the flowchart of FIG. 5 may be omitted, and other steps may be added to the flowchart of FIG.

In S502 of this flowchart, the charge / discharge control unit 31 uses the power of the power supply device 10 to charge the secondary battery 40 until the charging rate of the secondary battery 40 reaches a specified charging rate (S502). The specified charging rate may be determined for each secondary battery 40. For example, the specified charging rate may be a value within the range of 80% to 100% of the fully charged state. The fully charged state may be a state in which the secondary battery 40 is determined to be fully charged. The fully charged state may be a state in which the secondary battery 40 is charged until the rated capacity of the secondary battery 40 is reached under predetermined charging conditions.

In S504, the setting unit 33 sets the value of the high voltage _{V H} in the intermittent charge on the default value. For example, setting unit 33 sets the value of _{V H} to 13.38V. Moreover, the setting part 33 sets the value of the low voltage _VL in intermittent charge to a default value. For example, the setting unit 33 sets the value of _VL to 12.6V.

In step S <b> 506, the charge / discharge control unit 31 starts intermittent charging using the high voltage and the low voltage set by the setting unit 33. Thus, for example, at least a portion of the charge lost due to self-discharge or the like, can be at least supplemented in the high voltage charging period T _H.

In S510, the charge / discharge control unit 31 determines whether or not to continue charging. For example, the charging / discharging control unit 31 determines to stop charging when an abnormality occurs in the power supply device 10. In this case, the control of this flowchart is terminated, and the charge / discharge control unit 31 controls the charge / discharge device 50 to discharge the secondary battery 40 and supply power from the secondary battery 40 to the load 90. In addition, when the charge / discharge control unit 31 receives an operation stop signal or intermittent charge stop signal of the secondary battery 40, the charge / discharge control unit 31 determines that charging is not continued, and stops the operation stop signal or intermittent charge of the secondary battery 40. When the signal is not received, it may be determined that the charging is continued. When it is determined in S510 that the charging is continued, the process proceeds to S512.

In S512, the setting unit 33 acquires the cell voltage of each battery cell of the secondary battery 40. Specifically, the setting unit 33 acquires the cell voltage measured by the cell voltage measurement device 60. The cell voltage measuring device 60 may measure the cell voltage of each battery cell of the secondary battery 40 during the low voltage charging period. The cell voltage measuring device 60 may measure the cell voltage immediately before switching from the low voltage charging period to the high voltage charging period. The timing at which the cell voltage measuring device 60 measures the cell voltage may be another timing during the low voltage charging period.

In S514, the setting unit 33 determines whether or not the variation in the cell voltage is equal to or less than a predetermined value. For example, the setting unit 33 calculates the average value of the cell voltage of the secondary battery 40. The setting unit 33 may apply the difference between the average value of the cell voltages and the minimum value of the cell voltages as the variation in the cell voltages. The setting unit 33 may apply 20 mV as a predetermined value. If the cell voltage variation is less than or equal to the predetermined value, the process returns to S510. When the cell voltage variation is larger than the predetermined value, the process proceeds to S516.

In S516, the setting unit 33 increases the high voltage _VH by 60 mV per battery cell. That is, the setting unit 33 increases the overall V _H of the secondary battery 40 by 360 mV. When _{V H} in the immediately preceding S516 is 13.38V, _{V H} is increased to 13.74V.

Subsequently, in S520, the charge / discharge control unit 31 determines whether or not to continue charging. Since the determination in S520 is the same as the determination in S510, description thereof is omitted. When charging is not continued, the control of this flowchart is terminated. When charging is continued, the process proceeds to S522.

In S522, the setting unit 33 acquires the cell voltage of each battery cell of the secondary battery 40. The process of S522 is the same as the process of S512.

In S524, the setting unit 33 determines the variation in the cell voltage. Specifically, the setting unit 33 determines whether the cell voltage variation is equal to or less than a predetermined value, whether the cell voltage variation is greater than a predetermined value, and whether the cell voltage variation has increased. to decide. If the cell voltage variation is equal to or smaller than the predetermined value, or if the cell voltage variation is larger than the variation calculated in S514, the process proceeds to S530. If the cell voltage variation does not increase and the cell voltage variation is greater than the predetermined value, the process proceeds to S532.

In S530, the setting unit 33 sets the value of _VH to a default value. For example, setting unit 33 sets the value of _{V H} to 13.38V. It progresses to S510 after S530.

In S532, the setting unit 33 increases the value of _VH by 40 mV per battery cell. That is, the setting unit 33 increases the overall V _H of the secondary battery 40 by 240 mV. When _{V H} in the immediately preceding S532 is 13.74V, _{V H} is increased to 13.98V. After S532, the process returns to S520.

According to the control of this flowchart, when the variation in the cell voltage becomes larger than a predetermined value, V _H is increased stepwise until the variation in the cell voltage is eliminated. Thereby, the charge rate and cell voltage of each cell can be made uniform, suppressing the overcharge deterioration of the battery cell which has not insufficiently charged. As a result, it is possible to suppress a situation in which insufficient charging has occurred in a specific battery cell, and in turn, it is possible to suppress the hardening of lead sulfate in the specific battery cell.

An upper limit value may be set for the voltage for increasing _VH . The upper limit value may be 300 mV per battery cell. That is, the upper limit value of the voltage for increasing V _H may be 3.6 V for the entire secondary battery 40. Thus, setting unit 33, the upper limit of the _{V H} may be a 16.98V. The setting unit 33 may return V _H to the default value when the time during which intermittent charging is performed in a state where V _H is set to the upper limit exceeds a predetermined time.

In the above description, the control example for increasing V _H has been mainly described with reference to FIGS. 2 to 5 in particular. As another example of control, setting unit 33, if the value is greater than the variation in the cell voltage reaches a predetermined battery cell, it may be longer T _H. For example, in S516 of FIG. 5, in addition to increasing the V _H, and, instead of increasing the V _H, may be extended by a predetermined value T _H. Further, in S532 of FIG. 5, in addition to increasing the V _H, and, instead of increasing the V _H, may be extended by a predetermined value T _H. Thus, by increasing the T _H stepwise, it is possible to promote the elimination of variation in the cell voltage.

Moreover, the setting part 33 may shorten _TL , when the dispersion | variation in the cell voltage of a battery cell is larger than a predetermined value. For example, in S516 of FIG. 5, in addition to increasing the V _H, and, instead of increasing the V _H, may be shortened by a predetermined value T _L. Further, in S532 of FIG. 5, in addition to increasing the V _H, and, instead of increasing the V _H, may be shortened by a predetermined value T _L. Thereby, by shortening _TL step by step, it is possible to promote the elimination of cell voltage variations while suppressing overcharging of battery cells in which insufficient charging has occurred. Moreover, hardening of lead sulfate can be suppressed.

The control to increase the V _H described above, it controls to increase the T _H, and a control to shorten the T _L can be performed in any combination.

The control device 30 may be realized by a computer. When the computer executes the program, the program may function as the control device 30 by controlling each unit such as a processor and a memory included in the computer. The program may cause the computer to function as the charge / discharge control unit 31 and the setting unit 33.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

The execution order of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior”. It should be noted that they can be implemented in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for the sake of convenience, it means that it is essential to carry out in this order. is not.

DESCRIPTION OF SYMBOLS 10 Power supply device 12 Input terminal 14 Output terminal 16 Node 20 Power storage system 22 Converter 24 Inverter 30 Control device 31 Charge / discharge control unit 33 Setting unit 40 Secondary battery 50 Charge / discharge device 60 Cell voltage measurement device 90 Load 100 Secondary battery device 120 Power supply system 300 Waveform 310 Waveform 400 Waveform 410 Waveform

Claims (12)

1. Lead acid battery,
   A charge controller for charging the lead storage battery by alternately repeating high voltage charging for applying a pulsed high voltage to the lead storage battery and low voltage charging for applying a low voltage lower than the high voltage to the lead storage battery When,
   A lead storage battery comprising: a high voltage setting unit that increases the high voltage applied to the lead storage battery in the high voltage charging when variation in cell voltages of the plurality of battery cells of the lead storage battery is greater than a predetermined value. apparatus.
2. The lead-acid battery device according to claim 1, wherein the high voltage setting unit lengthens a time for performing the high voltage charging when the high voltage is increased.
3. The lead-acid battery device according to claim 1 or 2, wherein the high voltage setting unit shortens a time interval for performing the low voltage charging when the high voltage is increased.
4. The high voltage setting unit is configured such that cell voltage variation of the plurality of battery cells after the high voltage charging is performed with the high voltage increased by the high voltage setting unit is larger than the predetermined value. The lead storage battery device according to any one of claims 1 to 3, wherein the high voltage applied to the lead storage battery in the high voltage charging is further increased.
5. 5. The high voltage setting unit according to claim 1, wherein the high voltage setting unit reduces the high voltage to a predetermined voltage when cell voltage variation of the plurality of battery cells is equal to or less than the predetermined value. 6. The lead storage battery device according to one item.
6. The high voltage setting unit, when the variation of the cell voltage of the plurality of battery cells is larger than the variation of the cell voltage of the plurality of battery cells before the high voltage setting unit increases the high voltage, The lead storage battery device according to any one of claims 1 to 4, wherein the high voltage is reduced to a predetermined voltage.
7. The high voltage setting unit calculates a difference between an average value of the cell voltages of the plurality of battery cells and a cell voltage of the plurality of battery cells, and there is a battery cell in which the magnitude of the difference is larger than a predetermined value. The lead storage battery device according to any one of claims 1 to 6, wherein, when present, the high voltage is increased.
8. The high voltage setting unit calculates a difference between an average value of the cell voltages of the plurality of battery cells and a cell voltage of the plurality of battery cells, the magnitude of the difference is larger than a predetermined value, and The lead storage battery device according to any one of claims 1 to 6, wherein the high voltage is increased when battery cells having a cell voltage lower than the average value exist.
9. An uninterruptible power supply comprising the lead storage battery device according to any one of claims 1 to 8.
10. A power supply system comprising the lead storage battery device according to any one of claims 1 to 8.
11. A charge control unit for charging the lead storage battery by alternately repeating a high voltage charge for applying a pulsed high voltage to the lead storage battery and a low voltage charge for applying a low voltage lower than the high voltage to the lead storage battery; ,
    A lead storage battery comprising: a high voltage setting unit that increases the high voltage applied to the lead storage battery in the high voltage charging when variation in cell voltages of the plurality of battery cells of the lead storage battery is greater than a predetermined value. Control device.
12. A lead-acid battery charging method that alternately repeats high-voltage charging for applying a pulsed high voltage to a lead-acid battery and low-voltage charging for applying a low voltage lower than the high voltage to the lead-acid battery, the lead-acid battery A method for charging a lead storage battery, wherein when a variation in cell voltages of a plurality of battery cells included in the battery is larger than a predetermined value, the voltage applied to the lead storage battery in the high voltage charging is higher than the previously applied voltage.

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