JP2011015590A - Secondary battery charging controller and secondary battery charging control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the service life of a secondary battery by reducing deterioration of the secondary battery.SOLUTION: A secondary battery charging controller 10 includes a fully charged capacity calculating section 116 for calculating a fully charged capacity of the secondary battery 200, a charging depth determining section 117 for determining a charging depth of the secondary battery 200, and a charging control section 112 for charging the secondary battery 200 at the charging depth determined by the charging depth determining section 117. The charging depth determining section 117 determines the charging depth of the secondary battery 200 in accordance with the fully charged capacity calculated by the fully charged capacity calculating section 116.

Description

  The present invention relates to a secondary battery charge control technique.

  Secondary batteries such as lithium ion batteries and nickel metal hydride batteries have a reduced full charge capacity due to deterioration due to repeated charge / discharge cycles and deterioration over time. The secondary battery reaches the end of its life when the full charge capacity falls below the required discharge capacity. Needless to say, a longer lifetime is preferable. Therefore, various techniques for extending the life of the secondary battery have been proposed. For example, Patent Documents 1 to 3 disclose the following techniques.

  The battery control device for a hybrid vehicle disclosed in Patent Document 1 sets the upper limit voltage and the lower limit voltage of the input / output voltage of the secondary battery according to the battery temperature. That is, the upper limit voltage when the battery temperature is low is equal to or higher than the upper limit voltage when the battery temperature is high, and the lower limit voltage when the battery temperature is low is equal to or lower than the lower limit voltage when the battery temperature is high. Further, charging / discharging of the battery is controlled within the range of the upper limit voltage and the lower limit voltage set in this way.

  The power supply device disclosed in Patent Document 2 is based on the standard deviation of the battery temperature, the voltage between terminals, the charge / discharge current value, and the state of charge (State of Charge (SOC)) of the secondary battery in a predetermined period. The fan operating temperature of the cooling fan that cools the secondary battery is determined.

  In the method for charging a storage battery disclosed in Patent Document 3, the deterioration state of the storage battery charged and discharged when the SOC of the storage battery (secondary battery) is less than 100% is determined, and the charging voltage is determined based on the determination result. Control.

JP 2006-81300 A Japanese Patent Laid-Open No. 2006-32013 JP 2003-338325 A

  By the way, if the secondary battery is stored for a long time at a deep charging depth close to the fully charged state or the charge / discharge cycle is repeated, the secondary battery is stored at a shallow charging depth, or charged with the charging depth kept shallow. As compared with the case where the discharge cycle is repeated, the deterioration of the secondary battery is promoted. As described above, although the charging depth is an element that affects the life of the secondary battery, the technologies disclosed in Patent Documents 1 to 3 consider the charging depth as an element related to the life extension of the secondary battery. It has not been.

  The present invention has been made in order to solve the above-described problems, and reduces deterioration of a secondary battery accelerated by charging the secondary battery at a deep charging depth close to a fully charged state. The purpose is to extend the life of the battery.

  A secondary battery charge control device according to claim 1 of the present invention includes a full charge capacity calculation means for calculating a full charge capacity of a secondary battery, a charge depth determination means for determining a charge depth of the secondary battery, Control means for charging the secondary battery at the charging depth determined by the charging depth determining means, the charging depth determining means according to the full charge capacity calculated by the full charge capacity calculating means, The charging depth of the secondary battery is determined.

  A secondary battery charge control program according to claim 6 of the present invention includes a first step of calculating a full charge capacity of a secondary battery, and the second battery according to the full charge capacity calculated in the first step. The computer executes a second step of determining the charging depth of the secondary battery and a third step of charging the secondary battery at the charging depth determined in the second step.

  According to the first or sixth aspect of the invention, the charging depth of the secondary battery is determined according to the full charge capacity of the secondary battery, and the secondary battery is charged at the charging depth. Therefore, it becomes possible to charge the secondary battery at a charging depth with little deterioration of the secondary battery, and the life of the secondary battery can be extended.

  A secondary battery charge control device according to claim 2 of the present invention is the secondary battery charge control device according to claim 1, wherein the first charge depth corresponding to at least a first full charge capacity, and the first full charge capacity. Storage means for storing a plurality of charge depths including a second charge depth greater than the first charge depth corresponding to a second full charge capacity less than the charge capacity; and According to the full charge capacity calculated by the charge capacity calculation means, the charge depth of the secondary battery is determined by selecting from the plurality of charge depths stored in the storage means.

  According to the second aspect of the present invention, the charging depth determining means sets the charging depth to be increased when the full charge capacity of the secondary battery is small. Therefore, when the secondary battery deteriorates from the initial state and the full charge capacity decreases, the secondary battery is charged with the charging depth deeper than the charging depth in the initial state. Therefore, even when the secondary battery is deteriorated from the initial state and the full charge capacity is reduced, a necessary discharge capacity can be ensured.

  The secondary battery charge control device according to claim 3 of the present invention is the secondary battery charge control device according to claim 2, wherein the plurality of charge depths stored in the storage means are associated with the full charge capacity. The charging depth of the table is increased as the full charge capacity is reduced, and the charge depth determining means is responsive to the full charge capacity calculated by the full charge capacity calculating means. Then, the charging depth of the secondary battery is determined by selecting from the table.

  According to the invention of claim 3, the plurality of charging depths and the full charge capacity are stored in the storage means as a table associated with a relationship in which the charge depth increases as the full charge capacity decreases. Therefore, the secondary battery can be charged at a more accurate charging depth.

  The secondary battery charge control device according to claim 4 of the present invention is the secondary battery charge control device according to claim 2 or 3, wherein the first full charge capacity is an initial value of the full charge capacity of the secondary battery. The first charging depth is 80%.

  According to the fourth aspect of the present invention, since the charging depth is 80% in the initial state of the secondary battery, the life extension of the secondary battery and the discharge capacity of the secondary battery can be balanced. That is, since the secondary battery is charged at a deep charging depth close to a fully charged state, it is possible to prevent the deterioration of the secondary battery from being accelerated, and unlike the case where the charging depth is too shallow, a necessary discharge is required. Since it is not necessary to prepare a large-capacity secondary battery to secure the capacity, it is excellent in cost effectiveness.

  The secondary battery charge control device according to claim 5 of the present invention is the secondary battery charge control device according to any one of claims 2 to 4, wherein the storage means is a charge / discharge schedule of the secondary battery. Is further stored, and the control means completely discharges the secondary battery after full charge at a predetermined time, and the full charge capacity calculation means calculates the amount of discharge during the full discharge of the secondary battery. Calculated as the full charge capacity.

  According to the invention of claim 5, since the full charge capacity calculating means periodically measures the full charge capacity, even when the secondary battery is deteriorated from an initial state and the full charge capacity is reduced. The charging depth determining means can accurately determine the charging depth.

  According to the present invention, it is possible to shorten the period during which the secondary battery is operated in a fully charged state, and as a result, it is possible to extend the life of the secondary battery. Therefore, since the replacement frequency of the secondary battery is reduced, the cost can be reduced in the application using the secondary battery.

It is a block diagram which shows the outline of the secondary battery charge control apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating an example of the relationship between the charge depth of a secondary battery, and aged deterioration. It is a flowchart which shows the charge control which the secondary battery charge control apparatus which concerns on one Embodiment of this invention performs.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an outline of a secondary battery charge control device 10 according to an embodiment of the present invention. The secondary battery charge control device 10 performs charge control of the secondary battery 200 connected to the secondary battery charge control device 10. The secondary battery charge control device 10 is connected to an external power source 2, and a load 3 is connected to the secondary battery 200 and the external power source 2.

  The secondary battery charge control device 10 receives supply of electric power from the external power source 2 that is a commercial power source, for example, and charges the secondary battery 200 that is a lithium ion battery, for example.

  The secondary battery charge control device 10 includes a control unit 100 (control means), a current / voltmeter 130, a wattmeter 140, an AC / DC conversion unit 150, and a grid reactor 160.

  The ammeter / voltmeter 130 measures a discharge current value and a discharge voltage value of electric power discharged from the secondary battery 200 when the secondary battery 200 is discharged. The wattmeter 140 measures the amount of power used by the load 3.

  The AC / DC converter 150 functions as a rectifier that converts AC power supplied from the external power source 2 into DC power and supplies the DC power to the secondary battery 200 when the secondary battery 200 is charged. The inverter functions as an inverter that converts the DC power discharged from the secondary battery 200 into AC power having a voltage value, current value, or power value corresponding to the load 3 and supplies the AC power to the load 3. Further, the AC / DC converter 150 uses the electric power supplied from the external power supply 2 to charge the secondary battery 200 by, for example, a constant voltage / constant current charging method.

The interconnecting reactor 160 is provided between the AC / DC converter 150 and the external power supply 2. The AC / DC converter 150 advances the phase of the AC power V ₂ on the AC / DC converter 150 side more than the phase of the AC power V ₁ on the external power source 2 side, so that the power stored in the secondary battery 200 is increased. Supply to load 3. When the secondary battery 200 is charged, the AC / DC converter 150 supplies the power of the external power source 2 to the secondary battery 200 by delaying the phase of V _{2 from} the phase of V ₁ . When AC / DC converter 150 equalizes the phase of V _{2 and} the phase of V ₁ , secondary battery 200 enters a standby state in which neither charging nor discharging is performed.

  The control unit 100 includes a CPU (Central Processing Unit) 110, a time measuring unit 101, and a storage unit 102 (storage means).

  The storage unit 102 includes, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and when the secondary battery 200 is fully charged, the secondary battery charging control program, the charging / discharging schedule of the secondary battery 200, and the like. And a table that associates the full charge capacity with the charge depth.

  The timer unit 101 includes a clock transmitter that generates a clock signal at a constant period, and outputs the clock signal to the CPU 110. Based on the clock signal and the charge / discharge schedule stored in the storage unit 102, the full charge capacity calculation unit 116 described later determines the timing for updating the full charge capacity of the secondary battery 200.

  The CPU 110 executes the secondary battery charge control program stored in advance in the storage unit 102, thereby causing the discharge control unit 111, the charge control unit 112, the charge / discharge switching instruction unit 113, the discharge amount calculation unit 114, the remaining capacity. The calculation unit 115, the full charge capacity calculation unit 116 (full charge capacity calculation unit), and the charge depth determination unit 117 (charge depth determination unit) function as software. It should be noted that each of the above-described units can be provided inside the CPU 110 as hardware.

  The discharge control unit 111 detects the voltage value and current value of the AC power supplied to the load 3 based on at least one of the measurement values measured by the current / voltmeter 130 and the wattmeter 140 when the secondary battery 200 is discharged. At least one of the power values is determined. Then, the discharge control unit 111 controls the AC / DC conversion unit 150 so that the power supplied to the load 3 becomes the AC power having the value thus determined.

  Based on the current value and voltage value of the secondary battery 200 measured by the current / voltmeter 130, the charging control unit 112 is a current value that the AC / DC conversion unit 150 applies to the secondary battery 200 when the secondary battery 200 is charged. And determine the voltage value. The charge control unit 112 instructs the AC / DC conversion unit 150 to charge the secondary battery 200 with the current value and the voltage value.

  The charge / discharge switching instruction unit 113 determines whether to charge or discharge the secondary battery 200 based on the charge / discharge schedule stored in the storage unit 102 and the clock signal output from the time measuring unit 101, and performs AC / DC conversion. The unit 150 is instructed to switch between charge and discharge.

  The discharge amount calculation unit 114 samples the current value measured by the current / voltmeter 130 at a predetermined interval when the secondary battery 200 is discharged based on the clock signal output from the time measuring unit 101, and integrates the current value. By doing so, the discharge amount (unit: Ah) of the secondary battery 200 is calculated.

  The remaining capacity calculation unit 115 calculates the remaining capacity of the secondary battery 200 by subtracting the discharge amount calculated by the discharge amount calculation unit 114 from the full charge capacity stored in the storage unit 102.

  The full charge capacity calculation unit 116 periodically calculates the full charge capacity of the secondary battery 200 and updates the full charge capacity stored in the storage unit 102 to the calculated value. That is, based on the charging / discharging schedule stored in the storage unit 102 and the clock signal output from the timing unit 101, the charging control unit 112 fully charges the secondary battery 200 at a predetermined time, and after the full charging The discharge control unit 111 completely discharges the secondary battery 200, and the full charge capacity calculation unit 116 calculates the discharge amount at the time of the complete discharge as the full charge capacity of the secondary battery 200. Then, the full charge capacity calculation unit 116 updates the conventional full charge capacity stored in the storage unit 102 to the full charge capacity calculated at this time.

  The charging depth determination unit 117 selects the charging depth corresponding to the full charge capacity stored in the storage unit 102 from the table stored in the storage unit 102 in advance, thereby charging the secondary battery 200 with a charging depth. To decide. In the table, the charge depth and the full charge capacity are associated with a relationship in which the charge depth increases as the full charge capacity decreases. In the table, the charging depth corresponding to the initial value of the full charge capacity of the secondary battery 200, that is, the maximum value of the full charge capacity is set to 80%.

  FIG. 2 is a diagram for explaining an example of the relationship between the charging depth of the secondary battery 200 and aging deterioration. The horizontal axis indicates the number of years elapsed from the start of use of the secondary battery 200, and the vertical axis indicates the full charge capacity of the secondary battery 200 as a capacity ratio with respect to the required discharge capacity. Further, the charging depth of the secondary battery 200 is also shown on the vertical axis.

  Since the full charge capacity of the secondary battery 200 decreases due to aging deterioration, the initial value of the full charge capacity of the secondary battery 200 is set to a capacity larger than the necessary discharge capacity in anticipation of the aging deterioration. In the example shown in FIG. 2, the initial value of the full charge capacity of the secondary battery 200 is 125 with respect to the required discharge capacity 100 because the charge depth in the initial state of the secondary battery 200 is 80%. Yes.

  A change with time in the capacity ratio of the secondary battery 200 when the charge depth is fixed at 100% and the secondary battery 200 is always charged to a fully charged state in the charge / discharge cycle is indicated by a two-dot chain line. On the other hand, the charging depth in the initial state of the secondary battery 200 is set to 80%, and the charging depth is increased as the full charge capacity decreases due to deterioration over time, so that the charging capacity of the secondary battery 200 is limited to the necessary discharge capacity. In the case, the change with time of the capacity ratio of the secondary battery 200 is shown by a solid line. As shown in FIG. 2, by limiting the charging depth of the secondary battery to 80%, deterioration of the secondary battery 200 is suppressed, and the life of the secondary battery 200 is extended by the period indicated by the double-headed arrow.

  FIG. 3 is a flowchart showing charge control performed by the secondary battery charge control device 10. When the secondary battery charge control device 10 is activated, the full charge capacity calculation unit 116 is fully charged based on the charge / discharge schedule stored in the storage unit 102 and the clock signal output from the time measuring unit 101. It is determined whether or not it is time to update the capacity (step S1). If it is time to update the full charge capacity (YES in step S1), the charging control unit 112 instructs the AC / DC conversion unit 150 to fully charge the secondary battery 200 (step S2). Subsequently, the discharge controller 111 instructs the AC / DC converter 150 to completely discharge the secondary battery 200 (step S3). The full charge capacity calculation unit 116 calculates the discharge amount at the time of complete discharge in step S3 as the full charge capacity of the secondary battery 200, and calculates the conventional full charge capacity stored in the storage unit 102 to the calculated full charge capacity. Update (step S4) and proceed to step S5. Even when it is not time to update the full charge capacity (NO in step S1), the process proceeds to step S5.

  In step S <b> 5, the charging control unit 112 determines whether or not it is a time zone for charging based on the charging / discharging schedule and the clock signal. If it is a time zone for charging (YES in step S5), the charging depth determination unit 117 stores in advance the charging depth corresponding to the full charge capacity stored in the storage unit 102 in the storage unit 102. By selecting from the table, the charging depth of the secondary battery 200 is determined (step S6). Subsequent to step S6, the charging controller 112 instructs the AC / DC converter 150 to start charging the secondary battery 200 (step S7).

  After starting charging, the charging control unit 112 causes the AC / DC converter 150 to continue charging the secondary battery 200 until the secondary battery 200 reaches the charging depth (NO in step S8). Reaches the above-mentioned charging depth (YES in step S8), the AC / DC converter 150 is instructed to finish charging the secondary battery 200 (step S9).

  If it is not the time zone for charging in step S5 (NO in step S5) but the time zone for discharging (YES in step S10), the remaining capacity calculation unit 115 calculates the remaining capacity of the secondary battery 200 ( Step S11). If the remaining capacity is not 0 (NO in step S11), the discharge control unit 111 instructs the AC / DC conversion unit 150 to start discharging the secondary battery 200, and the DC power discharged from the secondary battery 200 is It is converted into predetermined AC power and supplied to the load 3 (step S12).

  The discharge controller 111 causes the AC / DC converter 150 to continue discharging the secondary battery 200 after the start of discharging, unless the remaining capacity of the secondary battery 200 becomes zero (NO in step S13). At the time when the discharge of the secondary battery 200 ends in the charge / discharge schedule (YES in step S13), the discharge control unit 111 instructs the AC / DC converter 150 to end the discharge of the secondary battery 200. (Step S14).

  If it is neither a time zone for charging nor a time zone for discharging (NO in step S10), or if the remaining capacity of the secondary battery 200 is 0 in step S11, or if charging is terminated in step S9, Alternatively, if the discharge is completed in step S14, the secondary battery charge control device 10 enters a standby state if any of the cases is satisfied (step S15). During the operation of the secondary battery charge control device 10, steps S1 to S15 are repeated.

  According to the above-described embodiment, the secondary battery charge control device 10 increases the charge depth as the secondary battery 200 deteriorates and the full charge capacity decreases, so that the required discharge amount can be ensured. That is, the secondary battery 200 is charged with a charging depth as shallow as possible. Therefore, it becomes possible to charge the secondary battery 200 at a charging depth with little deterioration of the secondary battery 200, and the life of the secondary battery 200 can be extended. In addition, even when the secondary battery 200 is deteriorated from the initial state and the full charge capacity is reduced, a necessary discharge capacity can be ensured.

  Moreover, according to the said embodiment, since the charge depth is 80% in the initial state of the secondary battery 200, the life extension of the secondary battery 200 and the discharge capacity of the secondary battery 200 can be balanced. . In other words, not only can the life of the secondary battery 200 be extended, but unlike the case where the charging depth is too shallow, it is not necessary to prepare a large capacity secondary battery in order to ensure the necessary discharge capacity. Excellent effect.

  Further, according to the above embodiment, the full charge capacity calculation unit 116 periodically measures and updates the full charge capacity, so that when the secondary battery 200 deteriorates from the initial state and the full charge capacity decreases. However, the charging depth determination unit 117 can accurately determine the charging depth.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention. For example, as the secondary battery 200 for storing electric power, another secondary battery such as a nickel metal hydride battery can be used instead of the lithium ion battery. Further, for example, the remaining capacity may be calculated based on the discharge voltage value of the secondary battery 200 or the like.

DESCRIPTION OF SYMBOLS 10 Secondary battery charge control apparatus 100 Control part (control means)
101 Timekeeping Unit 102 Storage Unit (Storage Unit)
110 CPU
111 discharge control unit 112 charge control unit 113 charge / discharge switching instruction unit 114 discharge amount calculation unit 115 remaining capacity calculation unit 116 full charge capacity calculation unit (full charge capacity calculation means)
117 Charging depth determining unit (charging depth determining means)
200 Secondary battery

Claims (6)

A full charge capacity calculating means for calculating the full charge capacity of the secondary battery;
A charging depth determining means for determining a charging depth of the secondary battery;
Control means for charging the secondary battery at the charging depth determined by the charging depth determining means,
The charging depth determination unit is a secondary battery charge control device that determines the charging depth of the secondary battery according to the full charge capacity calculated by the full charge capacity calculation unit. A plurality including a first charge depth corresponding to at least a first full charge capacity and a second charge depth corresponding to a second full charge capacity smaller than the first full charge capacity and larger than the first charge depth. Further comprising storage means for storing the charging depth of
The charging depth determination means selects the charging depth of the secondary battery from the plurality of charging depths stored in the storage means according to the full charge capacity calculated by the full charge capacity calculation means. The secondary battery charge control device according to claim 1 to be determined. The plurality of charge depths stored in the storage means are stored as a table associated with the full charge capacity,
The charging depth of the table is set to increase as the full charge capacity decreases,
The charge depth determination unit determines the charge depth of the secondary battery by selecting from the table according to the full charge capacity calculated by the full charge capacity calculation unit. Secondary battery charge control device. The first full charge capacity is an initial value of the full charge capacity of the secondary battery,
The secondary battery charging control device according to claim 2, wherein the first charging depth is 80%. The storage means further stores a charge / discharge schedule of the secondary battery,
The control means completely discharges the secondary battery after full charge at a predetermined time point,
The secondary battery charge control device according to any one of claims 2 to 4, wherein the full charge capacity calculation unit calculates a discharge amount at the time of the complete discharge as the full charge capacity of the secondary battery. A first step of calculating a full charge capacity of the secondary battery;
A second step of determining the charging depth of the secondary battery according to the full charge capacity calculated in the first step;
A secondary battery charging control program for causing a computer to execute a third step of charging the secondary battery at the charging depth determined in the second step.

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