JP2021016282A - Zinc battery control method and electrical power system - Google Patents

Abstract

To provide a zinc battery control method and electrical power system using the zinc battery that can extend the life of the zinc battery in a standby state while holding a charged state.SOLUTION: A control method, being a method of placing a zinc battery in a standby state while holding a charged state, includes: a charging step S1 of charging a zinc battery; and a self discharging step S2 of suspending charging/discharging control for the zinc battery and reducing the charging rate of the zinc battery through self discharging. The charging step S1 and the self discharging step S2 are continuously and alternately repeated.SELECTED DRAWING: Figure 4

Description

The present invention relates to a zinc battery control method and a power supply system.

Patent Document 1 discloses a technique relating to a storage battery control device. This storage battery control device includes an information acquisition unit and a control unit. The information acquisition unit acquires charge rate information regarding the charge rate of the storage battery and temperature information regarding the temperature of the storage battery. Based on the charge rate information and temperature information acquired by the information acquisition unit, the control unit performs when the charge rate of the storage battery is equal to or higher than the first threshold charge rate and the temperature of the storage battery drops below the first threshold temperature. , Switch the storage battery to the discharged state.

JP-A-2019-4565

There is known a power supply system in which a storage battery is kept on standby in a charged state and the power source is switched to the storage battery when the power of the storage battery is needed. For example, in an uninterruptible power system (UPS), a storage battery charged by using a commercial power supply is made to stand by in a charged state, and the power supply is switched from the commercial power supply to the storage battery in the event of a power failure. In such a power supply system, the life of the storage battery is important. This is because the longer the life of the storage battery, the longer the replacement cycle of the storage battery, and the longer the operating cost can be suppressed. In recent years, zinc batteries have been attracting attention as storage batteries for power supply systems used in such applications. For example, a nickel-zinc battery is an aqueous battery that uses an aqueous electrolytic solution such as an aqueous potassium hydroxide solution, and therefore has high safety, and a combination of a zinc electrode and a nickel electrode has a high electromotive force as an aqueous battery. .. Further, the nickel-zinc battery has advantages such as low cost in addition to excellent input / output performance.

One aspect of the present invention is to provide a method for controlling a zinc battery and a power supply system including the zinc battery, which can extend the life of the zinc battery in an application of standby in a charged state.

In order to solve the above-mentioned problems, the control method of the zinc battery according to one aspect of the present invention is a method of making the zinc battery stand by in a charged state, and is a charging step for charging the zinc battery and charging the zinc battery. The charge step and the self-discharge step are continuously and alternately repeated, including a self-discharge step in which control related to discharge is suspended and the charge rate of the zinc battery is lowered by self-discharge. Further, the power supply system according to one aspect of the present invention includes a zinc battery and a control unit that controls charging and discharging of the zinc battery. When the control unit puts the zinc battery on standby in a charged state, the control unit suspends the first operation of charging the zinc battery and the control regarding charge / discharge of the zinc battery, and lowers the charge rate of the zinc battery by self-discharge. The operation of is continuously and alternately repeated.

For example, in a power supply system using a lead storage battery or a lithium ion battery, a constant voltage is continuously applied to the storage battery when the storage battery is put on standby in a charged state. Such a method is called a float charging method or a trickle charging method. In the case of a power supply system using a zinc battery, unlike the case of using a lead storage battery, if a constant voltage is continuously applied, the electrodes are deteriorated and the battery life is suppressed. In the above control method and power supply system, when the zinc battery is put on standby in a charged state, the charging operation of the zinc battery and the operation of suspending the control regarding charge / discharge of the zinc battery and lowering the charge rate of the zinc battery by self-discharge are performed. Is continuously and alternately repeated. In the case of lead-acid batteries, the operation method of repeating charging and hibernation can be a factor of shortening the battery life, but in the case of zinc batteries, such an operation method is an electrode as compared with the case where a constant voltage is continuously applied. It suppresses the deterioration of the battery and contributes to the extension of life. That is, according to the above control method and power supply system, the life of the zinc battery can be extended in the application of waiting in the charged state.

In the above-mentioned zinc battery control method, the repetition cycle of the charging step and the self-discharge step may be constant. Similarly, in the above power supply system, the repetition period of the first and second operations may be constant. In this case, the switching timing between the charging period and the self-discharge period can be easily determined based only on the timing.

In the above-mentioned zinc battery control method, the timing of switching from the charging step to the self-discharge step and the switching from the self-discharge step to the charging step are based on the magnitude of the partial charge state (SOC: State Of Charge) of the zinc battery. At least one of the timings may be determined. Similarly, the power supply system further includes an SOC measuring unit that measures the SOC of the zinc battery, and the control unit operates from the first operation to the second operation based on the magnitude of the SOC measured by the SOC measuring unit. At least one of the timing of switching to and the timing of switching from the second operation to the first operation may be determined. In this case, for example, the operation such as maintaining the SOC level of the standby period at a certain level or higher can be performed with high accuracy.

In the above-mentioned zinc battery control method and power supply system, the SOC of the zinc battery, which is a reference for determining the switching timing from the charging step (first operation) to the self-discharge step (second operation), is 80 to 100%. It may be within the range. In this way, by setting the SOC of the zinc battery that determines the completion of charging to be relatively low, the upper limit of the SOC of the zinc battery during standby is kept low, and the deterioration of the zinc battery due to overcharging (mainly the positive electrode) is prevented. It can be suppressed and the life of the zinc battery can be further extended. The lower limit SOC of charging completion may be set to a value that can secure the amount of power required for UPS.

In the above-mentioned zinc battery control method and power supply system, the SOC of the zinc battery, which is a reference for determining the switching timing from the self-discharge step (second operation) to the charging step (first operation), is 50% or more and 100%. It may be less than. In this way, by setting the SOC of the zinc battery that determines the completion of self-discharge to be relatively high, the lower limit of the SOC of the zinc battery during standby can be maintained high, which is sufficient when the power of the zinc battery is required. Power can be supplied.

According to the zinc battery control method and power supply system according to one aspect of the present invention, the life of the zinc battery can be extended in the application of waiting in a charged state.

FIG. 1 is a diagram schematically showing an example of the configuration of the power supply system 1 and its surroundings. FIG. 2 is a diagram showing a hardware configuration example of the control unit 14. FIG. 3 is an enlarged graph showing the change in SOC during the waiting period. FIG. 4 is a flowchart showing a control method of the zinc battery 10. FIG. 5 is a graph showing the transition of the initial specific volume retention rate according to the examples, and shows the case where the test temperature is 25 ° C. FIG. 6 is a graph showing the transition of the initial specific volume retention rate according to the examples, and shows the case where the test temperature is 40 ° C. FIG. 7 is a graph showing the transition of the initial specific volume maintenance rate according to the comparative example.

Hereinafter, the method for controlling the zinc battery and the embodiment of the power supply system according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a diagram schematically showing an example of the configuration of the power supply system 1 and its surroundings. The power supply system 1 keeps the storage battery charged and puts it on standby in an unused state, and supplies power to the storage battery as needed. The situation where the power supply system 1 is applied is not limited, and for example, the power supply system 1 can be applied to both a fixed object and a moving body. As an example of application to fixed objects, the power supply system 1 can be used as an UPS in various places such as homes, offices, factories, and farms.

The power supply system 1 is provided between a supply element 2 capable of supplying electric power to the power supply system 1 and a demand element (load) 4 capable of receiving electric power from the power supply system 1. The power supply system 1, the supply element 2, and the demand element 4 are electrically connected via a wiring 6 through which a direct current or an alternating current flows. The electricity generated by the supply element 2 or the electric power stored in the power supply system 1 is supplied to the demand element 4 through the wiring 6.

The supply element 2 is a device or equipment capable of supplying electric power to the power supply system 1. The type of supply element 2 is not limited in any way. For example, the supply element 2 may be a power generation device that uses renewable energy to generate power. The power generation method and the type of the power generation device are not limited in any way. For example, the power generation device may be a solar power generation device or a wind power generator. Alternatively, the supply element 2 may be an external power system that is a commercial power supply facility that integrates power generation, substation, power transmission, and distribution. The external power grid is provided, for example, by a power company.

The demand element 4 is a device or equipment capable of receiving electric power from the power supply system 1. The type of demand element 4 is not limited in any way. The demand element 4 may be a load that is a set of one or more devices or devices that consume power. Examples of loads include one or more sets of various household or commercial electrical equipment and any component of any device.

The power supply system 1 includes a power converter 8, a zinc battery 10, a battery control unit (BCU) 12, and a control unit 14. The zinc battery 10 and the power converter 8 are electrically connected to each other via the DC wiring 7. In the example of FIG. 1, the power supply system 1 includes one set of the power converter 8 and the zinc battery 10, but the number of sets is not limited and may be two or more. When a plurality of sets exist, the performance of the zinc battery 10 (for example, rated capacity, response speed, etc.) and the performance of the power converter 8 (for example, rated output, response speed, etc.) may be unified or unified. It does not have to be done. The control unit 14 is communicably connected to the power converter 8 via a communication line.

The zinc battery 10 is a device that converts electricity provided by the supply element 2 into chemical energy and stores it, and can be charged and discharged. The zinc battery 10 is, for example, a nickel-zinc battery, and includes a plurality of cells connected in series. A BCU 12 as a control function is connected to the zinc battery 10. The BCU 12 transmits data regarding the zinc battery 10 to the control unit 14.

The BCU 12 also serves as an SOC measurement unit in this embodiment. That is, the BCU 12 measures the charge state (SOC) of the zinc battery 10. For example, the BCU 12 measures the SOC by measuring and integrating the current energized in the zinc battery 10. The information about the SOC measured by the BCU 12 is transmitted to the control unit 14 together with other data. The BCU 12 transmits information necessary for calculating SOC (for example, battery open circuit voltage, discharge current amount and charge current amount, or discharge current integrated amount and charge current integrated amount) to the control unit 14, and the control unit 14 may calculate the SOC.

SOC is measured, for example, as follows. First, the amount of current flowing through the zinc battery 10 during charging of the zinc battery 10 is acquired. Then, the charge capacity is calculated from the amount of current. Next, the amount of current flowing from the zinc battery 10 during discharging of the zinc battery 10 is acquired. Then, the discharge capacity is calculated from the amount of current. The SOC can be calculated based on these charge capacity and discharge capacity.

The power converter 8 is a device that controls charging / discharging of the zinc battery 10. The power converter 8 receives an instruction signal (data signal) from the control unit 14 and controls charging / discharging of the zinc battery 10 based on the instruction signal. In particular, the control unit 14 of the present embodiment controls the charging / discharging of the zinc battery 10 by controlling the operation of the power converter 8 based on the SOC of the zinc battery 10 obtained from the BCU 12. In the charge mode, the power converter 8 stores the electricity flowing from the supply element 2 in the zinc battery 10, and in the discharge mode, the zinc battery 10 is forcibly discharged to supply power to the outside. The power converter 8 can be, for example, a DC / DC converter or an AC / DC converter.

The control unit 14 is a computer (for example, a microcomputer) that controls charging and discharging of the zinc battery 10. FIG. 2 is a diagram showing a hardware configuration example of the control unit 14. As shown in this figure, the control unit 14 includes a processor 141, a memory 142, and a communication interface 143. The processor 141 is, for example, a CPU, and the memory 142 is composed of, for example, a flash memory, but the type of hardware device constituting the control unit 14 is not limited to these, and may be arbitrarily selected. Each function of the control unit 14 is realized by the processor 141 executing a program stored in the memory 142. For example, the processor 141 executes a predetermined operation on the data read from the memory 142 or the data received via the communication interface 143, and outputs the calculation result to another device to display the other device. Control. Alternatively, the processor 141 stores the received data or the calculation result in the memory 142. The control unit 14 may be composed of one computer or a set of a plurality of computers (that is, a distributed system).

For example, the power supply system 1 such as UPS causes the zinc battery 10 to stand by in an unused state while maintaining the charged state of the zinc battery 10 in normal times when the electric power of the zinc battery 10 is not required. At that time, the control unit 14 controls the SOC of the zinc battery 10 so as to have a certain size (for example, 100%). This period lasts for a long period of time, for example several months (eg about 3 months).

Here, the above charge / discharge control will be described in detail. FIG. 3 is a graph showing an enlarged change in SOC during a period in which the zinc battery 10 is kept in an unused state (hereinafter referred to as a standby period) while maintaining the charged state of the zinc battery 10. As shown in FIG. 3, during the standby period, the control unit 14 suspends the charging operation of the zinc battery 10 (first operation, period P11) and the control regarding charging / discharging of the zinc battery 10, and self-discharges the zinc battery. The operation of lowering the charge rate of 10 (second operation, period P12) is continuously and alternately repeated.

The charging operation means supplying electric power from the wiring 6 to the zinc battery 10 by the operation of the power converter 8 shown in FIG. 1 and storing the electric charge in the zinc battery 10. The charging operation is performed, for example, by applying a constant voltage to the zinc battery 10. Further, suspending the control related to charging / discharging means stopping the operation of the power converter 8. In this case, the power converter 8 does not charge or discharge the electric power stored in the zinc battery 10, and does not cause the transfer of electric charge between the wiring 6 and the zinc battery 10. During that time, the electric charge stored in the zinc battery 10 gradually decreases with the passage of time due to natural discharge.

Further, repeating the above-mentioned charging operation and hibernation operation continuously and alternately means that when the charging operation → pausing operation → charging operation → hibernation operation ... is repeated, between the charging operation and the next hibernation operation, and It means that no other operation (for example, forced discharge operation) intervenes in any of the pause operation and the subsequent charging operation. In other words, during the standby period, the power converter 8 repeats only the charging operation and the hibernation operation.

In the standby period, shallow charging / discharging is periodically repeated. The repeating cycle Ta of the charging operation and the pause operation is, for example, in the range of 1 second to 90 days, and in one embodiment, the cycle is 5 days, 15 days, or 30 days. However, the charging operation is much shorter than the hibernation operation, for example, several tens of minutes. Therefore, most of one cycle is assigned to hibernation. Even when the pause operation is set to 30 days, the amount of decrease in SOC of the zinc battery 10 is small, for example, about 3% at 25 ° C.

The repeating cycle Ta of the charging operation and the pause operation may be a predetermined constant cycle. In that case, the repetition period Ta is input in advance from the outside via, for example, the communication interface 143 shown in FIG. 2, and is stored in the memory 142.

The repetition cycle Ta of the charging operation and the pause operation may be indefinite. In that case, the control unit 14 may control switching between the charging operation and the pause operation based on the SOC size of the zinc battery 10 measured in the BCU 12. For example, when the SOC of the zinc battery 10 rises to a predetermined size, the control unit 14 may switch from the charging operation to the hibernation operation. The SOC of the zinc battery 10 as a reference for determining the switching timing from the charging operation to the hibernation operation is, for example, in the range of 80 to 100%. Further, when the SOC of the zinc battery 10 is lowered to a predetermined size, the control unit 14 may switch from the hibernation operation to the charging operation. The SOC of the zinc battery 10 as a reference for determining the switching timing from the hibernation operation to the charging operation is, for example, 50% or more and less than 100%.

Alternatively, the period from the start of the charging operation to the switching to the hibernation operation is set to a fixed value in advance, and the SOC of the zinc battery 10 measured in the BCU 12 after the start of the hibernation operation has a predetermined size (for example, 50% or more 100). When the temperature is lowered to less than%), the control unit 14 may switch from the hibernation operation to the charging operation.

When a certain period is set from the start of the charging operation to the switching to the hibernation operation, the SOC after the charging operation depends on the SOC at the start of charging, the charging voltage (constant voltage), and the charging time. The length of the period from the start of the charging operation to the switching to the hibernation operation and the charging voltage may be set so that the SOC after the charging operation is in the range of, for example, 80 to 100%.

Here, a method of controlling the zinc battery 10 using the power supply system 1 will be described. FIG. 4 is a flowchart showing a control method of the zinc battery 10 of the present embodiment. This control method is a method of keeping the zinc battery 10 in an unused state while maintaining the charged state, and suspends the charging step S1 for charging the zinc battery 10 and the control for charging / discharging the zinc battery 10. The self-discharge step S2, which reduces the charge rate of the zinc battery 10 by self-discharge, is continuously and alternately repeated. As described above, the repetition cycle of the charging step S1 and the self-discharge step S2 may be constant, and the switching timing from the charging step S1 to the self-discharge step S2 is based on the magnitude of the SOC of the zinc battery 10. , And at least one of the switching timings from the self-discharge step S2 to the charging step S1 may be determined. In that case, as described above, the SOC of the zinc battery 10 as a reference for determining the switching timing from the charging step S1 to the self-discharge step S2 may be in the range of 80 to 100%. Further, the SOC of the zinc battery 10 as a reference for determining the switching timing from the self-discharge step S2 to the charging step S1 may be 50% or more and less than 100%.

The control method of the zinc battery 10 of the present embodiment described above and the effect obtained by the power supply system 1 will be described. In the present embodiment, when the zinc battery 10 is made to stand by in a charged state, the charging operation of the zinc battery 10 and the operation of suspending the control regarding charging / discharging of the zinc battery 10 and lowering the charging rate of the zinc battery 10 by self-discharge are performed. Is continuously and alternately repeated. In the case of a lead-acid battery, the operation method of repeating charging and hibernation can be a factor of shortening the battery life, but as shown in Examples described later, in the case of the zinc battery 10, such an operation method is constant. Compared with the case where the voltage is continuously applied, the deterioration of the electrode is suppressed and the life is extended. That is, according to the control method and the power supply system 1 of the present embodiment, the life of the zinc battery 10 can be extended in the application of making the zinc battery stand by in a charged state.

As described above, the repeating cycle of the charging operation (charging step S1) and the pause operation (self-discharge step S2) may be constant. In this case, the switching timing between the charging operation and the hibernation operation can be easily determined based only on the timing.

As described above, at least one of the timing of switching from the charging step S1 to the self-discharge step S2 and the timing of switching from the self-discharge step S2 to the charging step S1 is determined based on the magnitude of the SOC of the zinc battery 10. You may. In this case, for example, the operation such as maintaining the SOC level of the standby period at a certain level or higher can be performed with high accuracy. In this case, the SOC of the zinc battery 10 as a reference for determining the switching timing from the charging step S1 (charging operation) to the self-discharge step S2 (pause operation) may be in the range of 80 to 100%. In this way, by setting the SOC of the zinc battery 10 for determining the completion of charging to be relatively low, the upper limit of the SOC of the zinc battery 10 during standby is maintained low, and deterioration of the zinc battery 10 due to overcharging is suppressed. , The life of the zinc battery 10 can be further extended. Further, the SOC of the zinc battery 10 as a reference for determining the switching timing from the self-discharge step S2 (pause operation) to the charging step S1 (charging operation) may be 50% or more and less than 100%. By setting the SOC of the zinc battery 10 for determining the completion of self-discharge to be relatively high in this way, the lower limit of the SOC of the zinc battery 10 during standby is maintained high, and the electric power of the zinc battery 10 is required. In that case, sufficient power can be supplied.

(Example)
In order to confirm the effect of the above embodiment, the present inventor conducted the following test using a nickel-zinc battery (nominal voltage 1.65V, rated capacity 8Ah @ 8A). The procedure is as follows A1 to A10.
A1) In order to measure the discharge capacity, the zinc battery is fully charged (SOC 100%).
A2) Rest at 25 ° C for 6 hours to stabilize the battery condition.
A3) In order to confirm the discharge capacity (8Ah @ 32A), the initial discharge capacity is measured.
A4) In order to start the life test, the zinc battery is put into a fully charged state (SOC 100%) again.
A5) Rest at 25 ° C or 40 ° C for a predetermined period (5 days, 15 days, or 30 days). At this time, the SOC of the battery gradually decreases due to self-discharge.
A6) A battery having a predetermined period of 5 days or 15 days is charged when the predetermined period elapses, and the SOC lowered by self-discharge is restored to a fully charged state.
A7) After 30 days have passed, all the batteries are fully charged (SOC 100%) in order to measure the discharge capacity.
A8) The discharge capacity (@ 32A) is measured, and the discharge capacity retention rate is calculated.
A9) To continue the test, restore the zinc battery to a fully charged state (SOC 100%) again.
A10) Repeat steps A5 to A9.

The charging conditions for A1, A4, A7, and A9 are as follows.
・ Charging method CC-CV charging ・ Temperature 25 ℃
・ Current 8A, 0.4A-cutoff
・ Voltage 1.9V
-Pause time after charging 6 hours-Sampling time 60 seconds The discharge conditions for A3 and A8 are as follows.
・ Temperature 25 ℃
・ Current 32A
・ Discharge end voltage 1.1V
-Pause time after discharge 0 hours-Sampling time 1 second The charging conditions for A6 are as follows.
<At 25 ° C>
・ Charging method CC-CV charging ・ Current 8A, 0.4A-cutoff
・ Voltage 1.9V
・ Sampling time 1 second ・ 5 days interval Charge upper limit capacity 0.112Ah
・ 15-day interval Charge upper limit capacity 0.32Ah
<At 40 ° C>
・ Charging method CC-CV charging ・ Current 8A, 0.4A-cutoff
・ Voltage 1.89V
・ Sampling time 1 second ・ 5 days interval Charge upper limit capacity 0.224Ah
・ 15-day interval Charge upper limit capacity 0.672Ah

For comparison, the following tests were conducted using nickel-zinc batteries with the same specifications as above. The procedure is as follows B1 to B7.
B1) In order to measure the discharge capacity, the zinc battery is fully charged (SOC 100%).
B2) Rest at 25 ° C. for 6 hours to stabilize the battery condition.
B3) In order to confirm the discharge capacity (8Ah @ 32A), the initial discharge capacity is measured.
B4) After the discharge is completed, the battery is charged with the float charging voltage for 30 days.
B5) In order to adjust the battery temperature to the test temperature, rest at 25 ° C. for 12 hours.
B6) Measure the discharge capacity (@ 32A) and calculate the discharge capacity retention rate.
B7) Repeat steps B4 to B6.

The charging conditions of B1 are the same as the charging conditions of A1, A4, A7, and A9 described above. Further, the discharge conditions of B3 and B6 are the same as the charging conditions of A3 and A8 described above. The charging conditions for B4 are as follows.
・ Charging method CC-CV charging ・ Temperature 25 ℃ or 40 ℃
・ Upper limit current 1.6A
・ Voltage 1.83V
・ Float charging time 30 days ・ Pause time after charging 0 hours ・ Sampling time 1800 seconds

5 and 6 are graphs showing changes in the initial specific volume retention rate in the tests (Examples) of A1 to A10. In these figures, the vertical axis represents the initial specific volume retention rate (unit:%), and the horizontal axis represents the test period (unit: day). FIG. 5 shows a case where the test temperature is 25 ° C., and FIG. 6 shows a case where the test temperature is 40 ° C. Further, FIG. 7 is a graph showing the transition of the initial specific volume retention rate in the tests (comparative examples) of B1 to B7. In FIG. 7, the vertical axis represents the initial specific volume retention rate (unit:%), and the horizontal axis represents the test period (unit: day). Furthermore, Table 1 below shows the initial specific volume retention rate after 210 days.

With reference to FIG. 5 and Table 1, the initial specific volume retention rate after 210 days in the examples when the test temperature was 25 ° C. was 97 at any charging interval (5 days, 15 days, 30 days). It exceeds%. On the other hand, referring to FIG. 7 and Table 1, the initial specific volume retention rate after 210 days in the comparative example when the test temperature is 25 ° C. is slightly higher than 90%. Further, referring to FIG. 6 and Table 1, the initial specific volume retention rate after 210 days in the example when the test temperature was 40 ° C. was any charging interval (5 days, 15 days, 30 days). Also exceeds 87%. On the other hand, referring to FIG. 7 and Table 1, the initial specific volume retention rate after 210 days in the comparative example when the test temperature was 40 ° C. was less than 55%. That is, according to the above embodiment, the life of the zinc battery 10 can be effectively extended as compared with the conventional float charging method.

The control method and power supply system of the zinc battery according to the present invention are not limited to the examples of the above-described embodiments, but are indicated by the scope of claims and all meanings and scope equivalent to the scope of claims. It is intended to include changes.

1 ... power supply system, 2 ... supply element, 4 ... demand element, 6 ... wiring, 7 ... DC wiring, 8 ... power converter, 10 ... zinc battery, 14 ... control unit, 141 ... processor, 142 ... memory, 143 ... Communication interface, Ta ... Cycle.

Claims (10)

It is a method to make the zinc battery stand by in a charged state.
The charging step for charging the zinc battery and
A self-discharge step that suspends control of charge / discharge of the zinc battery and lowers the charge rate of the zinc battery by self-discharge.
Including
A method for controlling a zinc battery, in which the charging step and the self-discharge step are continuously and alternately repeated. The method for controlling a zinc battery according to claim 1, wherein the repeating cycle of the charging step and the self-discharge step is constant. The first aspect of the present invention is to determine at least one of the timing of switching from the charging step to the self-discharge step and the timing of switching from the self-discharge step to the charging step based on the magnitude of the SOC of the zinc battery. The described method for controlling a zinc battery. The method for controlling a zinc battery according to claim 3, wherein the SOC of the zinc battery, which is a reference for determining the switching timing from the charging step to the self-discharge step, is in the range of 80 to 100%. The method for controlling a zinc battery according to claim 3 or 4, wherein the SOC of the zinc battery, which is a reference for determining the switching timing from the self-discharge step to the charging step, is 50% or more and less than 100%. With zinc batteries
A control unit that controls charging and discharging of the zinc battery,
With
When the zinc battery is made to stand by in a charged state, the control unit suspends the first operation of charging the zinc battery and the control regarding charge / discharge of the zinc battery, and self-discharges the charge rate of the zinc battery. A power supply system that continuously and alternately repeats the second operation of reducing the battery charge. The power supply system according to claim 6, wherein the repetition period of the first and second operations is constant. A SOC measuring unit for measuring the SOC of the zinc battery is further provided.
The control unit determines the switching timing from the first operation to the second operation and the switching timing from the second operation to the first operation based on the magnitude of the SOC of the zinc battery. The power supply system according to claim 6, wherein at least one of them is determined. The power supply system according to claim 8, wherein the SOC of the zinc battery, which is a reference for determining the switching timing from the first operation to the second operation, is in the range of 80 to 100%. The power supply system according to claim 8 or 9, wherein the SOC of the zinc battery, which is a reference for determining the switching timing from the second operation to the first operation, is 50% or more and less than 100%.

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