JP5053322B2 - Storage battery capacity estimation apparatus and method - Google Patents

Description

  The present invention relates to a storage battery capacity estimation apparatus and method for estimating the capacity of a storage battery.

  In order to accurately determine the capacity of the storage battery, that is, how much capacity can be discharged to the storage battery, the storage battery is actually discharged to the discharge end voltage, and the amount of discharge electricity (the integrated value of the discharge current and discharge time) is calculated. Need to ask. However, in this method, since the storage battery is actually discharged, there is a problem that it cannot be performed while maintaining the capacity of the storage battery, and it takes time. Therefore, a method for estimating the capacity of the storage battery in a short time while maintaining the capacity of the storage battery has been proposed. This method has a high correlation with the capacity of the storage battery, finds the physical property value of the storage battery that can be measured in a short time, and indirectly seeks the capacity of the storage battery by measuring the physical property value. . Typical examples of such physical property values include the internal impedance and terminal voltage of the storage battery.

  As a method of estimating the capacity of the storage battery from the internal impedance of the former storage battery, for example, an AC voltage is applied to the storage battery using an AC power source, the internal impedance is obtained from the current response of the storage battery at this time, There has been considered a method for estimating the capacity of a storage battery from a relational expression or a relationship diagram between a predetermined internal impedance and the capacity of the storage battery. The internal impedance is also obtained from the response voltage of the storage battery when an alternating current is passed through the storage battery. Further, without using an AC power supply, a pulsed discharge current or charging current is instantaneously supplied to the storage battery, and the voltage change of the storage battery at this time is divided by the current value of the pulse. In addition, a method of estimating the capacity of a storage battery based on a tendency between an integrated value of charging current and an integrated value of discharge current using internal impedance has been considered (see, for example, Patent Document 1).

  In addition, as a method of estimating the capacity of the storage battery by the latter terminal voltage, the terminal voltage of the storage battery is measured at the time of discharging or charging, and the relational expression between this terminal voltage and the terminal voltage obtained in advance and the capacity of the storage battery or A method of estimating the capacity of a storage battery from a relationship diagram has been considered (for example, see Patent Document 2).

  Further, a method of estimating the capacity of the storage battery while referring to a map showing the relationship between the temperature of the storage battery, the charge / discharge current, and the upper limit or lower limit voltage value has been considered (for example, see Patent Document 3).

JP 2003-294817 A JP 2006-300561 A JP 2000-217261 A

  However, as described above, the method for estimating the capacity of the storage battery from the internal impedance and terminal voltage of the storage battery is not applicable to all types of storage batteries, and the storage battery's capacity, such as a nickel hydride storage battery or a nickel cadmium storage battery, can be used. In a storage battery in which the internal impedance and the terminal voltage hardly change even when the capacity changes, there is a problem that it is difficult to estimate the capacity. Moreover, in the thing using a map, there exists a problem that it becomes necessary to prepare a map beforehand and a process will become complicated in order to refer a map.

  The present invention has been made in view of the problems of the prior art as described above, and the storage battery capacity is not limited to the storage battery whose internal impedance and terminal voltage hardly change even when the storage battery capacity changes. An object of the present invention is to provide a storage battery capacity estimation apparatus and method capable of estimating capacity without complicating processing in a short time while maintaining the above.

In order to achieve the above object, the present invention provides:
A storage battery capacity estimation device for estimating the capacity of a storage battery,
After supplying a charging current having a first current value to the storage battery for a certain time, a current value of the charging current supplied to the storage battery is changed from the first current value to a second current smaller than the first current value. Current supply means for switching to the current value and supplying the storage battery with a charging current having the second current value;
Voltage measuring means for measuring a first voltage which is a voltage of the storage battery in a state where a charging current having the second current value is supplied to the storage battery;
Change point detection means for detecting timing at which the first voltage measured by the voltage measurement means changes from a drop to an increase;
The time from the timing when the current value of the charging current supplied to the storage battery is switched from the first current value to the second current value until the timing detected by the change point detecting means is a predetermined time or more. Capacity determining means for determining the capacity of the storage battery according to whether

Further, a storage battery capacity estimation method for estimating a storage battery capacity,
Supplying a charging current having a first current value to the storage battery for a certain period of time;
The current value of the charging current supplied to the storage battery is switched from the first current value to a second current value smaller than the first current value, and the charging current having the second current value is switched to the storage battery. Supplying to,
Timing when the current value of the charging current supplied to the storage battery is switched from the first current value to the second current value in a state where the charging current having the second current value is supplied to the storage battery And measuring the time from when the voltage of the storage battery starts to fall to when it rises; and
Estimating the capacity of the storage battery according to whether the measured time is equal to or longer than a predetermined time.

  Since the present invention is configured as described above, even for a storage battery whose internal impedance and terminal voltage hardly change even when the capacity of the storage battery changes, processing is complicated in a short time while maintaining the capacity of the storage battery. The capacity can be estimated without doing so.

It is a figure which shows one Embodiment of the storage battery capacity estimation apparatus of this invention. It is a flowchart for demonstrating the capacity | capacitance estimation method of the nickel metal hydride storage battery using the storage battery capacity estimation apparatus shown in FIG. It is a graph which shows the change of the voltage of a nickel hydride storage battery when an electric current is supplied to the nickel hydride storage battery using the storage battery capacity estimation apparatus shown in FIG. The relationship between the time from when the current value of the charging current supplied to the hydrogen storage battery is switched from the storage battery capacity estimation device shown in FIG. FIG. It is a figure which shows the relationship between the voltage of a nickel hydride storage battery and the capacity | capacitance of a nickel hydride storage battery just before the electric current value of the charging current supplied to a hydrogen storage battery is switched from the storage battery capacity estimation apparatus shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing an embodiment of a storage battery capacity estimation device of the present invention.

  As shown in FIG. 1, the storage battery capacity estimation device according to the present embodiment estimates the capacity of a nickel-metal hydride storage battery 20. The current supply unit 11 supplies current to the nickel-metal hydride storage battery 20, and the voltage of the nickel-metal hydride storage battery 20. A voltage measuring unit 12 that measures the voltage, a change point detecting unit 14 that detects timing when the voltage of the nickel hydride storage battery 20 measured by the voltage measuring unit 12 changes from a drop to an increase, and a nickel hydride storage battery at the current supply unit 11 20 includes a capacity determination unit 15 that determines the capacity of the nickel-metal hydride storage battery 20 based on the time from the timing corresponding to the current supplied to the timing 20 to the timing detected by the change point detection unit 14, and a timer 13. Yes.

  The current supply unit 11 supplies the current value of the charging current supplied to the nickel-metal hydride storage battery 20 from 1C to the nickel-metal hydride storage battery 20 after supplying the charging current of 1 C, which is the first current value, for 60 seconds. The current value of 2 is switched to 0.2 C, and a charging current of 0.2 C is supplied to the nickel metal hydride storage battery 20.

  The voltage measuring unit 12 measures the voltage of the nickel metal hydride storage battery 20. The voltage of the nickel-metal hydride storage battery 20 is measured in a state where at least a charge current of 0.2 C is supplied to the nickel-metal hydride storage battery 20, and the measured voltage becomes the first voltage.

  The change point detection unit 14 detects the timing at which the first voltage measured by the voltage measurement unit 12 changes from a drop to an increase.

  The capacity determination unit 15 is from the timing when the current value of the charging current supplied from the current supply unit 11 to the nickel metal hydride storage battery 20 is switched from 1C to 0.2C to the timing detected by the change point detection unit 14. The time is measured by the timer 13, and the capacity of the nickel metal hydride storage battery 20 is determined depending on whether the measured time is 100 seconds or more, which is a predetermined time.

  Below, the capacity | capacitance estimation method of the nickel hydride storage battery 20 using the storage battery capacity estimation apparatus 10 comprised as mentioned above is demonstrated.

  FIG. 2 is a flowchart for explaining a capacity estimation method of the nickel-metal hydride storage battery 20 using the storage battery capacity estimation apparatus 10 shown in FIG.

  First, in an environment of 0 ° C., 1 C charging current is supplied from the open state to the nickel metal hydride storage battery 20 by the current supply unit 11 to start charging (step S1).

  FIG. 3 is a graph showing a change in voltage of the nickel-metal hydride storage battery 20 when a current is supplied to the nickel-metal hydride storage battery 20 using the storage battery capacity estimation device 10 shown in FIG.

  As shown in FIG. 3, when 1 C charging current is supplied from the open state to the nickel hydride storage battery 20 by the current supply unit 11, the voltage of the nickel hydride storage battery 20 gradually increases.

  Then, after 60 seconds have passed since the 1 C charging current began to be supplied from the current supply unit 11 to the nickel metal hydride storage battery 20 (step S2), the current supply unit 11 supplies the charging current to the nickel metal hydride storage battery 20 The current value is switched from 1C to 0.2C, a charging current of 0.2C is supplied to the nickel metal hydride storage battery 20, and the nickel metal hydride storage battery 20 is continuously charged (step S3). The voltage measurement unit 12 measures the voltage of the nickel hydride storage battery 20, and the capacity determination unit 15 switches the current value of the charging current supplied to the nickel hydride storage battery 20 from 1C to 0.2C. Time is measured from the timing (step S4). Here, as shown in FIG. 3, at the moment when the current value of the charging current supplied from the current supply unit 11 to the nickel hydride storage battery 20 is switched from 1 C to 0.2 C, the voltage of the nickel storage battery 20 is 1.375 V. After an instantaneous drop from 1.294V to 1.294V, it rises instantly to 1.308V. This is because an overvoltage is required to charge the nickel metal hydride storage battery 20, and the overvoltage increases as the charging current increases. Therefore, the current value of the charging current supplied from the current supply unit 11 to the nickel hydride storage battery 20 is This is because the overvoltage is reduced due to the reduction from 1 C to 0.2 C, and the overvoltage of the storage battery voltage corresponding to the current value of 0.2 C is about to decrease.

  Thereafter, as shown in FIG. 3, the voltage of the nickel-metal hydride storage battery 20 gradually decreases and then increases after decreasing to 1.302V. This is because the voltage of the nickel metal hydride storage battery 20 has reached an overvoltage corresponding to a current value of 0.2 C, and thereafter the overvoltage increases with the progress of charging of the storage battery. When the timing at which the voltage of the nickel metal hydride storage battery 20 changes from a drop to an increase is detected in the change point detection unit 12 (step S5), the current value of the charging current supplied to the nickel metal hydride storage battery 20 in the capacity determination unit 14 Since the time is measured from the timing when the battery is switched from 1C to 0.2C, the time from this timing to the timing when the voltage of the nickel metal hydride storage battery 20 starts to rise is measured, and the time is 100 seconds or more. It is determined whether or not there is (step S6).

  FIG. 4 shows the time from when the current value of the charging current supplied to the hydrogen storage battery 20 from the storage battery capacity estimation device 10 shown in FIG. FIG. 3 is a diagram showing a relationship with the capacity of a storage battery 20. In FIG. 4, the results obtained with the four nickel-metal hydride storage batteries 20 are plotted together, and the storage battery capacity is normalized with the nominal capacity being 100%.

  The trend of FIG. 4 shows that the capacity of the nickel metal hydride storage battery 20 is equal to the nominal capacity ratio when the charging current of the nickel metal hydride storage battery 20 is switched from 1 C to 0.2 C and when the charge current is switched from 1 C to 0.1 C. From about 0 to about 50 to 60%, as the capacity of the nickel-metal hydride storage battery 20 increases, the time until the voltage of the nickel-metal hydride storage battery 20 starts to drop increases. On the other hand, when the capacity of the nickel metal hydride storage battery 20 is larger than about 50 to 60% in the nominal capacity ratio, the time until the voltage of the nickel metal hydride storage battery 20 starts to increase from the drop as the capacity of the nickel metal hydride storage battery 20 increases. It is getting shorter.

  From the relationship obtained in FIG. 4, when the environmental temperature of the nickel metal hydride storage battery 20 is 0 ° C. and the charging current is switched from 1 C to 0.2 C, the capacity determination unit 15 determines the nickel hydride storage battery from the switching timing. If the time until the timing at which the voltage of 20 turns from rising to rising is 100 seconds or more, it is determined that the capacity of the nickel-metal hydride storage battery 20 is in the range of 30 to 70% in nominal capacity ratio (step S7).

  Further, if the time from the switching timing of the charging current of the nickel metal hydride storage battery 20 to the timing at which the voltage of the nickel metal hydride storage battery 20 changes from a drop to an increase is less than 100 seconds, the capacity of the nickel hydride storage battery 20 is 30 in nominal capacity ratio. It is determined that it is less than 70% or over 70% (step S8).

  This determination result is output from the capacity determination unit 15 as the estimated capacity of the nickel-metal hydride storage battery 20.

  Thus, in this embodiment, by measuring the time from the timing when the charging current of the nickel metal hydride storage battery 20 is switched from 1 C to 0.2 C to the timing when the voltage of the nickel metal hydride storage battery 20 changes from a drop to an increase. The capacity of the nickel metal hydride storage battery 20 can be estimated. The time required for capacity estimation in this case is 160 seconds obtained by adding 100 seconds to 60 seconds, and the discharge capacity of the storage battery at this time is 1 C × (60/3600) time + 0.2 C × (100/3600). ) Only time = 2.2% (nominal capacity ratio), and the capacity can be estimated in a short time while the capacity of the nickel-metal hydride storage battery 20 is substantially maintained.

  In addition, although the method mentioned above is characterized by estimating the capacity of the storage battery as a capacity range, as an application of the storage battery, for example, in the wind power generation or solar power generation, the use for stabilizing the fluctuating generated power, In applications that absorb steep load fluctuations in fuel cell power generation that uses hydrogen reformed from hydrocarbons as fuel, keep the storage battery at an intermediate capacity that can be charged and discharged for a certain period of time. Since it is necessary, it is a particularly effective method for estimating the capacity of a storage battery for use in determining whether such a storage battery is in an intermediate capacity state.

  In addition, as described above, when the capacity is estimated based on the result when the charging current of the nickel-metal hydride storage battery 20 is switched from 1 C to 0.2 C, the voltage of the nickel-metal hydride storage battery 20 changes from a drop to an increase. When the measurement time is less than 100 seconds, it may be desired to know whether the capacity of the nickel metal hydride storage battery 20 is less than 30% or more than 70% in the nominal capacity ratio. In that case, the voltage measurement unit 12 measures the voltage of the nickel hydride storage battery 20 immediately before the charging current of the nickel hydride storage battery 20 is switched from 1 C to 0.2 C as the second voltage, and the capacity determination unit 15 If the capacity of the nickel-metal hydride storage battery 20 is determined using the second voltage measured by the voltage measuring unit 12, the capacity of the nickel-metal hydride storage battery 20 is less than 30% or more than 70% in the nominal capacity ratio. You can know what it is.

  FIG. 5 shows the relationship between the voltage of the nickel hydride storage battery 20 and the capacity of the nickel hydride storage battery 20 immediately before the current value of the charging current supplied from the storage battery capacity estimation device 10 shown in FIG. 1 to the hydrogen storage battery 20 is switched. FIG.

  As shown in FIG. 5, the voltage measurement unit 12 measures the voltage of the nickel metal hydride storage battery 20 immediately before the charging current of the nickel metal hydride storage battery 20 is switched from 1 C to 0.2 C as the second voltage. If the voltage of 2 is 1.45V or less, the capacity of the nickel-metal hydride storage battery 20 is less than 30%, and if it is 1.52V or more, it may be determined that the capacity of the nickel-metal hydride storage battery 20 exceeds 70%. it can.

  As described above, in the present embodiment, by measuring the time from the timing when the charging current of the nickel-metal hydride storage battery 20 is switched from 1 C to 0.2 C to the timing when the voltage of the nickel-metal hydride storage battery 20 changes from a drop to an increase. The capacity of the nickel metal hydride storage battery 20 can be estimated, but by measuring the voltage of the nickel metal hydride storage battery 20 immediately before the charging current of the nickel metal hydride storage battery 20 is switched from 1 C to 0.2 C, the nickel metal hydride storage battery 20 The accuracy of the capacity estimation of 20 can be improved.

  In this embodiment, the nickel-metal hydride storage battery 20 is described as an example of the storage battery for estimating the capacity. However, as the storage battery whose capacity can be estimated by the storage battery capacity estimation device of the present invention, the charging current value is switched. As long as there is a correlation between the time until the voltage of the storage battery changes from falling to rising and the storage battery capacity, it can be applied regardless of the type of storage battery.

DESCRIPTION OF SYMBOLS 10 Storage battery capacity estimation apparatus 11 Current supply part 12 Voltage measurement part 13 Timer 14 Change point detection part 15 Capacity determination part 20 Nickel metal hydride storage battery

Claims (4)

A storage battery capacity estimation device for estimating the capacity of a storage battery,
After supplying a charging current having a first current value to the storage battery for a certain time, a current value of the charging current supplied to the storage battery is changed from the first current value to a second current smaller than the first current value. Current supply means for switching to the current value and supplying the storage battery with a charging current having the second current value;
Voltage measuring means for measuring a first voltage which is a voltage of the storage battery in a state where a charging current having the second current value is supplied to the storage battery;
Change point detection means for detecting timing at which the first voltage measured by the voltage measurement means changes from a drop to an increase;
The time from the timing when the current value of the charging current supplied to the storage battery is switched from the first current value to the second current value until the timing detected by the change point detecting means is a predetermined time or more. A storage battery capacity estimation device comprising: capacity determination means for determining the capacity of the storage battery according to whether In the storage battery capacity estimation device according to claim 1,
The voltage measuring means measures a second voltage that is the voltage of the storage battery immediately before the current value of the charging current supplied to the storage battery is switched from the first current value to the second current value;
The capacity determination unit is a storage battery capacity estimation device that determines the capacity of the storage battery also using the second voltage measured by the voltage measurement unit. A storage battery capacity estimation method for estimating a storage battery capacity,
Supplying a charging current having a first current value to the storage battery for a certain period of time;
The current value of the charging current supplied to the storage battery is switched from the first current value to a second current value smaller than the first current value, and the charging current having the second current value is switched to the storage battery. Supplying to,
Timing when the current value of the charging current supplied to the storage battery is switched from the first current value to the second current value in a state where the charging current having the second current value is supplied to the storage battery And measuring the time from when the voltage of the storage battery starts to fall to when it rises; and
Estimating the capacity of the storage battery according to whether the measured time is a predetermined time or more. In the storage battery capacity estimation method according to claim 3,
Measuring a second voltage that is a voltage of the storage battery immediately before the current value of the charging current supplied to the storage battery is switched from the first current value to the second current value;
The step of estimating the capacity of the storage battery is a storage battery capacity estimation method for determining the capacity of the storage battery also using the measured second voltage.

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