JP7152903B2 - Charging control method and charging control system for secondary battery - Google Patents

Description

The present invention relates to a charge control method and charge control system for a secondary battery.

A secondary battery is a battery that can be charged, and can be used repeatedly by charging. For this reason, secondary batteries have found various uses such as power sources for portable electronic devices, power sources for electric vehicles, and emergency power sources, and their uses are increasing more and more.

One type of such secondary batteries is, for example, an alkaline secondary battery that uses an alkaline aqueous solution as an electrolyte. As a general charging method for this alkaline secondary battery, a constant current charging method is used. In this charging method, charging is performed by supplying a constant current from the start of charging, and the supply of current is stopped when it is considered that the alkaline secondary battery has been charged to the maximum capacity that can be stored. Then, control to terminate charging is performed. Here, it is assumed that the alkaline secondary battery has been charged to the maximum capacity that it can store, that is, it is fully charged, and the charging is terminated at that point. is mentioned.

First, when an alkaline secondary battery reaches a fully charged state, the voltage of the battery reaches a maximum value and then drops by several mV. There is a method of controlling charging by stopping current supply when is detected. This control method is hereinafter referred to as -ΔV control.

Next, when the alkaline secondary battery reaches a fully charged state, a phenomenon occurs in which the temperature of the battery rises rapidly. There is a method of controlling charging by stopping the supply of current when it reaches . This control method is hereinafter referred to as dT/dt control.

By the way, in -ΔV control and dT/dt control, a phenomenon that can be recognized as a fully charged state occurs when the overcharged state has progressed considerably. As described above, when the alkaline secondary battery is overcharged, the amount of gas generated in the battery increases and the internal pressure rises. In other words, when the battery is being charged and the battery voltage reaches its maximum value and then enters a region where the phenomenon of a few mV drop can be grasped, or when it enters a region where it can be grasped that the rate of rise of the battery temperature has changed, The pressure rises rapidly inside the battery.

Here, depending on the battery, there are cases where an increased battery internal pressure cannot be allowed structurally. In addition, as the internal pressure of the battery rises, the safety valve of the battery opens, and the electrolytic solution is released to the outside together with the gas, which may shorten the life of the battery. In order to avoid such problems, these -ΔV control and dT/dt control cannot be used.

Moreover, the -ΔV control and the dT/dt control described above are premised on the use of the constant current charging method. Therefore, these controls cannot be used even when charging with a constant current is not performed.

Therefore, various battery charging control methods different from the above-described -ΔV control and dT/dt control have been proposed in which full charge cannot be recognized until the gas pressure rises. As one of them, a method of controlling charging by grasping the state of charge (hereinafter referred to as SOC) of a battery (hereinafter referred to as SOC control method) as used in Patent Document 1 and the like is known. It is

SOC is the ratio of the battery's stored capacity to its full charge capacity, also called the state of charge. Basically, when the SOC is 0%, the stored capacity of the battery is empty, when the SOC is 50%, the stored battery capacity is half full, and the SOC is 100%, the battery is fully charged.

As a method of grasping the SOC, the charging/discharging current of the secondary battery is measured, the current value is integrated to calculate the charging/discharging capacity, and the SOC of the secondary battery is calculated from the charging/discharging capacity.

The SOC control method starts charging when the SOC value obtained as described above reaches 0% or a preset lower limit value, and ends charging when the SOC value reaches 100%. . That is, in the SOC control method, it is determined whether or not the battery is fully charged from the amount of charge. Therefore, the SOC control method can terminate charging before the battery reaches an overcharged state, and can be employed not only for charging with a constant current. Therefore, the SOC control method can avoid the problems when the -ΔV control and the dT/dt control described above are adopted.

JP 2005-269824 A

By the way, in the case of the SOC control method, the current value during charging and discharging is measured, and the SOC is calculated from the integrated value. Errors may accumulate in integrated values. This is because the more times the battery is charged and discharged, and the longer the battery is left for, the more error accumulates.

When errors are accumulated in the SOC calculated in this manner, deviation from the actual SOC of the battery occurs. For example, when the actual SOC of the battery is smaller than the calculated SOC, the battery capacity is actually insufficient even though the calculation result indicates that the battery still has capacity. Therefore, there is a risk that a voltage drop will occur and a problem that discharge will not be possible will occur.

Therefore, it is desired to improve the SOC control method so as to avoid the above problems.

SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances, and an object of the present invention is to provide a charging control method and a charging control system for a secondary battery that can suppress the occurrence of defects in the conventional SOC control method. to provide.

In order to achieve the above object, according to the present invention, the full charge capacity of a secondary battery, the charging current supplied to the secondary battery, and the discharging current emitted from the secondary battery are measured, and these charging The charging rate of the secondary battery is calculated based on the capacity stored in the secondary battery obtained from the values of the current and the discharge current, and the obtained calculated charging rate reaches a predetermined lower limit. A charging control method for a secondary battery, comprising: controlling charging of the secondary battery by starting charging at a point in time and stopping charging when the obtained calculated charging rate reaches a predetermined upper limit value, wherein any a correction step of correcting the value of the calculated charging rate at the timing of , and the correcting operation includes control to stop charging when the calculated charging rate reaches a predetermined upper limit value. Charging is continued in the temporarily interrupted state, during which the battery internal pressure value, which is the value of the internal pressure of the secondary battery, is measured, and when the battery internal pressure value reaches a preset set pressure value, the charging is continued. There is provided a charge control method for a secondary battery that stops and corrects by rewriting the calculated charge rate at the time when the set pressure value is reached to a new charge rate.

Further, the new charging rate is the actual charging rate corresponding to the set pressure value, which is obtained from the corresponding relationship between the previously grasped battery internal pressure value and the actual charging rate of the secondary battery. , the set pressure value is equal to or greater than the battery internal pressure value corresponding to the case where the actual charging rate of the secondary battery is 100%, and is equal to or higher than the secondary battery pressure value obtained when the secondary battery is charged, which is grasped in advance. It is preferable that the pressure value is set in a range equal to or lower than the battery internal pressure value corresponding to the maximum value of the voltage obtained from the relationship between the voltage of the next battery and the battery internal pressure value.

Moreover, it is preferable that the arbitrary timing is a point in time when the number of times of charging reaches a predetermined number of times.

The arbitrary timing is the time when the elapsed time from the time when the secondary battery is fully charged for the first time or the time when the time has elapsed since the correction work is performed reaches a predetermined time. It is preferable to set it as a structure.

Further, according to the present invention, a current measuring unit for measuring a charging current supplied to a secondary battery and a discharging current discharged from the secondary battery, and a pressure measuring unit for measuring the internal pressure of the secondary battery. and a control unit that controls charging and discharging of the secondary battery, wherein the control unit determines the secondary battery obtained from the values of the charging current and the discharging current measured by the current measurement unit a process of obtaining a calculated charging rate by calculating the charging rate of the secondary battery based on the obtained capacity and the previously obtained full charge capacity of the secondary battery, and a process of stopping the supply of the charging current from the external power source when the calculated charging rate reaches a predetermined upper limit value, and making the secondary battery into a dischargeable state with respect to the load; a process of disconnecting the secondary battery from the load when the charging rate reaches a predetermined lower limit value, connecting the secondary battery to the external power supply, supplying the charging current to start charging; wherein the suspension of the supply of the charging current from the external power supply is temporarily interrupted when the calculated charging rate reaches a predetermined upper limit value. Then, charging is continued even if the calculated charging rate exceeds a predetermined upper limit value, and when the internal pressure of the secondary battery measured by the pressure measuring unit reaches a preset set pressure value, the and a correction process of stopping the supply of the charging current from the external power supply and correcting the calculated charging rate at the time when the set pressure value is reached by rewriting it to a new charging rate. charging control system.

The new charging rate is an actual charging rate corresponding to the set pressure value, which is obtained from the corresponding relationship between the previously grasped battery internal pressure value and the actual charging rate of the secondary battery, and The set pressure value is equal to or greater than the battery internal pressure value corresponding to the case where the actual charging rate of the secondary battery is 100%, and the secondary battery when the secondary battery is charged which is grasped in advance. and the battery internal pressure value, the pressure value is set in a range equal to or lower than the battery internal pressure value corresponding to the maximum value of the voltage.

In addition, it is preferable that the control unit further includes a counter that counts the number of times of charging, and that the correction process is executed when the number of times counted by the counter reaches a predetermined number.

In addition, the control unit further includes a timer capable of measuring the elapsed time, and the timer is used to determine the elapsed time from the time when the secondary battery is first fully charged, or to perform the correction work. It is preferable to measure the elapsed time from the point in time and execute the correction process at the timing when the elapsed time reaches a predetermined time.

A charging control method for a secondary battery according to the present invention includes a correction step of performing a correction operation to match the calculated charging rate with the actual charging rate of the secondary battery at arbitrary timing during charging and discharging of the secondary battery. , the correction work includes measuring a battery internal pressure value, which is the value of the internal pressure of the secondary battery, continuing charging until the battery internal pressure value reaches a preset set pressure value, and reaching the set pressure value. It is a work to stop the charging at the point in time when the charging is completed and to rewrite the calculated charging rate to a new charging rate for correction. Such correction work corrects the deviation between the calculated charging rate and the actual charging rate of the secondary battery.

Therefore, according to the present invention, it is possible to provide a charging control method and charging control system for a secondary battery that can suppress the occurrence of defects in the conventional SOC control method.

1 is a block diagram schematically showing the configuration of a charging control system according to a first embodiment of the invention; FIG. 4 is a graph showing the relationship between changes in battery voltage, battery temperature, battery internal pressure, and SOC when a nickel-metal hydride secondary battery is charged. FIG. 2 is a block diagram schematically showing the configuration of a charging control system according to a second embodiment of the invention; FIG.

[First Embodiment]
A power supply device 4 including a charge control system 2 using a charge control method for a secondary battery according to the present invention will be described below with reference to the drawings.

The power supply device 4 includes a first output terminal portion 8 to which the first cable K1 of the load 6 to be driven is connected, a second output terminal portion 10 to which the second cable K2 of the load 6 is connected, A first input terminal portion 14 to which the first cable K3 of the external power source 12 that supplies the power of the external power source 12 is connected, a second input terminal portion 16 to which the second cable K4 of the external power source 12 is connected, and the control of the external power source 12 and a power supply terminal 17 to which a control signal line 15 extending from the signal input terminal 13 is connected. Here, the load 6 is not particularly limited, and examples thereof include a motor, an electronic device, and the like. Moreover, the external power source 12 is not particularly limited, and examples thereof include a generator.

The power supply device 4 includes a secondary battery, which is a power source for supplying power to the load 6 and a charging target, and the charging control system 2 . The charging control system 2 includes various sensors for grasping the state of the secondary battery, a control device for performing various calculations based on the information from the above sensors and controlling charging, and the obtained calculation results. A switch is included that switches the current flow according to a command output from the control device.

The secondary battery is not particularly limited, but includes, for example, a nickel-hydrogen secondary battery 18 . In the nickel-hydrogen secondary battery 18, an electrode group 19 formed by stacking a positive electrode and a negative electrode with a separator interposed therebetween is accommodated in a container 20 together with an alkaline electrolyte. A sealed nickel-hydrogen secondary battery 18 is used. In this embodiment, a tube 22 having one end inserted into the container 20 is attached to the container 20 described above. A pressure sensor 24 capable of measuring the internal pressure of the nickel-hydrogen secondary battery 18 is attached to the other end of the tube 22 . The pressure sensor 24 is not particularly limited, and for example, a diaphragm gauge or the like can be used. The pressure sensor 24 has a pressure value output terminal 26 for outputting information on the measured pressure value inside the nickel-hydrogen secondary battery 18 . One end of the tube 22 is inserted into the container 20 while maintaining airtightness and liquidtightness.

The nickel-hydrogen secondary battery 18 has a switch 44 provided in the middle of the first wiring 28 extending between the first output terminal portion 8 and the first input terminal portion 14, and the positive electrode terminal 32 connects the positive electrode side wiring 34 to the switch 44. The negative electrode terminal 40 connects the negative electrode side wiring 42 to the first contact 38 provided in the middle of the second wiring 36 extending between the second output terminal portion 10 and the second input terminal portion 16 . connected through

Here, the switch 44 switches connection of the nickel-hydrogen secondary battery 18 to either the load 6 or the external power supply 12 . The switch 44 has a switching signal input terminal 74 to which a command signal for switching the connection destination is input.

A current sensor 48 capable of measuring the charging current supplied to the nickel-metal hydride secondary battery 18 and the discharging current discharged from the nickel-metal hydride secondary battery 18 is arranged in the negative electrode wiring 42 . . It should be noted that the current sensor 48 may be arranged in the portion of the positive electrode side wiring 34 . The current sensor 48 is not particularly limited, and may be, for example, a Hall current detector type sensor, a shunt resistor type sensor, or the like. The current sensor 48 has a current value output terminal 50 for outputting information on measured values of the charging current supplied to the nickel-hydrogen secondary battery 18 and the discharge current discharged from the nickel-hydrogen secondary battery 18 .

Furthermore, it is preferable to dispose a voltage sensor 52 for measuring the voltage of the nickel-hydrogen secondary battery 18 as necessary. The voltage sensor 52 is not particularly limited as long as it is commonly used. The voltage sensor 52 has one probe 54 connected to the positive electrode wiring 34 and the other probe 56 connected to the negative electrode wiring 42 . The voltage sensor 52 has a voltage value output terminal 58 for outputting information on the measured voltage value of the nickel-hydrogen secondary battery.

The control device 60 has a pressure signal input terminal 64 connected to the pressure value output terminal 26 of the pressure sensor 24 via a lead wire 62 and a current value output terminal 50 of the current sensor 48 via a lead wire 66 . a voltage signal input terminal 72 connected to the voltage value output terminal 58 of the voltage sensor 52 via a lead wire 70; and a switching signal input terminal 74 of the switch 44 via a lead wire 76. , a control signal output terminal 79 connected to the power supply terminal 17 via a lead wire 77, a counter 86 capable of counting the number of times of charging, and a timer 88 capable of measuring time. and an arithmetic processing unit 90 that integrates the current values sent from the current sensor 48 and performs arithmetic processing of the state of charge (SOC) of the nickel-metal hydride secondary battery 18 from the obtained integrated value.

Next, a charge control method for charging the nickel-hydrogen secondary battery 18 using the charge control system 2 according to the present invention will be described.

First, assume that the SOC of the nickel-hydrogen secondary battery 18 is 0%. When charging is started from this state, the controller 60 sends a command signal to the switch 44 to connect the nickel-metal hydride secondary battery 18 and the external power source 12 as the first charging mode. As a result, the switch 44 disconnects the nickel-metal hydride secondary battery 18 from the load 6 and connects the nickel-hydrogen secondary battery 18 to the external power supply 12 . After that, the control device 60 sends a drive start command signal to the external power source 12 . If the external power source 12 is not a generator (for example, a battery, a solar battery, etc.), it is not necessary to send a drive start command signal. As a result, a charging current is supplied from the external power supply 12 to the nickel-hydrogen secondary battery 18, and charging is performed. During this charging, current sensor 48 measures the charging current and sends the resulting charging current value to controller 60 . The arithmetic processing unit 90 of the control device 60 integrates the current value from the current sensor 48, calculates the charged capacity from the obtained integrated value, and calculates the capacity of the nickel-metal hydride secondary battery 18 when fully charged. The ratio of the charged capacity to the value is calculated to grasp the SOC of the nickel-metal hydride secondary battery 18 being charged. Here, the fully charged capacity of the nickel-metal hydride secondary battery 18 is obtained by measuring in advance, or the rated capacity of the nickel-hydrogen secondary battery 18 is used.

When the SOC value calculated as described above reaches 100%, the control device 60 determines that the nickel-metal hydride secondary battery 18 is fully charged, and drives the battery toward the external power supply 12. send a signal to stop the If the external power supply 12 is not a generator (for example, a battery, a solar battery, etc.), it is not necessary to send a command signal to stop driving. Next, the control device 60 sends a command signal to the switch 44 to disconnect the nickel-hydrogen secondary battery 18 from the external power supply 12 and connect the nickel-hydrogen secondary battery 18 to the load 6. . The switch 44 receives the signal, disconnects the nickel-hydrogen secondary battery 18 and the external power supply 12 , and connects the nickel-hydrogen secondary battery 18 and the load 6 . As a result, charging is terminated and at the same time, a state in which discharging is possible is achieved.

During discharge, the current sensor 48 measures the discharge current and sends the obtained discharge current value to the controller 60 . The arithmetic processing unit 90 of the control device 60 integrates the current value from the current sensor 48, calculates the discharged capacity from the obtained integrated value, and calculates the capacity of the nickel-metal hydride secondary battery 18 when fully charged. A ratio of the discharged capacity to the value is calculated to grasp the SOC of the nickel-hydrogen secondary battery 18 during discharge. In other words, during discharging, how much capacity is consumed from the fully charged state where the SOC is 100%, and what percentage the current SOC is.

After that, discharge progresses, and when the SOC value calculated as described above becomes, for example, 0%, the control device 60 causes the switch 44 to connect the nickel-metal hydride secondary battery 18. A command to switch the destination from the load 6 to the external power source 12 is sent. Upon receipt of this command, the switch 44 disconnects the nickel-hydrogen secondary battery 18 from the load 6 and simultaneously connects the nickel-hydrogen secondary battery 18 to the external power source 12 . After that, the control device 60 sends a drive start command signal to the external power source 12 . If the external power source 12 is not a generator (for example, a battery, a solar battery, etc.), it is not necessary to send a drive start command signal. As a result, a charging current is supplied from the external power supply 12 to the nickel-hydrogen secondary battery 18, and charging is performed.

Here, the timing of starting charging is not limited to the time when the SOC becomes 0% as described above. In order to start charging from a state in which a certain amount of dischargeable capacity remains, charging may be started before the SOC reaches 0%, for example, when the SOC is 10% or 20%. .

It is also possible to refer to the voltage of the nickel-metal hydride secondary battery 18 obtained from the voltage sensor 52 to find the timing to start charging. For example, when the information that the voltage of the nickel-hydrogen secondary battery 18 has become 0 V is sent to the control device 60 , the control device 60 changes the connection destination of the nickel-hydrogen secondary battery 18 from the load 6 to the switch 44 . A command to switch to the external power supply 12 is sent. As a result, nickel-metal hydride secondary battery 18 is disconnected from load 6 and nickel-metal hydride secondary battery 18 is connected to external power source 12 . Charging is started from this state. Note that when the timing for starting charging is determined by referring to the voltage value, the voltage value for starting charging is not limited to the point in time when the voltage reaches 0 V, as described above. It may be set to the lowest drive voltage value.

The nickel-metal hydride secondary battery 18 is used to drive the load 6 by sequentially repeating the charging operation and discharging operation as described above.

By the way, when charging and discharging are repeatedly performed, a deviation may occur between the SOC value calculated based on the integrated value of the current value and the actual SOC value of the battery. Factors that cause such a deviation include the difference between the charging efficiency and the discharging efficiency, such as the inability to discharge the charged capacity, self-discharge of the battery, and the current used to operate the various memories and computers included in the control device 60. (dark current). The actual stored capacity is obtained by subtracting the amount of capacity consumed due to these factors. A discrepancy occurs when comparing

As described above, if the calculated SOC and the actual SOC deviate, for example, even if the calculated SOC indicates that the battery still has capacity, the actual SOC will drop below the indicated value. In this case, the voltage of the battery may drop earlier than estimated and discharge may not be possible. Therefore, it is important to correct the SOC deviation.

As a procedure for the correction work, the control device 60 continues charging without issuing a command to stop charging even if the SOC reaches 100% at an arbitrary timing during charging and discharging. At this time, the control device 60 monitors the internal pressure of the nickel-hydrogen secondary battery 18 with the pressure sensor 24, and when the value of this pressure reaches a preset set pressure value, the external power supply 12 is Sends a command signal to stop charging. This terminates charging. Then, the control device 60 sends a command to the switch 44 to switch the connection destination of the nickel-hydrogen secondary battery 18 from the external power source 12 to the load 6 . As a result, the nickel-metal hydride secondary battery 18 is disconnected from the external power source 12 and connected to the load 6 so that it can be discharged.

Here, in the present invention, regarding the nickel-metal hydride secondary battery 18, changes in the actual SOC, the pressure inside the battery (battery internal pressure value), the temperature of the battery, and the voltage of the battery during charging. Investigate the relationship with The results are shown in FIG. Since the correspondence between the battery internal pressure value and the actual SOC can be grasped from FIG. 2, the actual SOC value can be obtained by measuring the battery internal pressure value. Therefore, when the battery internal pressure value reaches a preset set pressure value, if the calculated SOC value is rewritten to an actual SOC value that can be grasped from the battery internal pressure value, the calculated SOC value and the actual SOC value can be corrected.

The above set pressure value is set within the following range.
First, the lower limit is set to a battery internal pressure value corresponding to an actual SOC value of 100%. On the other hand, the upper limit is set to the battery internal pressure value corresponding to the SOC when the battery voltage exhibits the maximum value M in FIG. Within this range, the actual SOC exceeds 100% and the battery is fully charged, and charging can be terminated before the battery internal pressure value becomes too high.

Here, based on FIG. 2, the SOC control method according to the present invention will be described in more detail in comparison with -ΔV control and dT/dt control.

In the -ΔV control, the battery voltage is monitored, and after the voltage value shows the maximum value M, the phenomenon that the voltage value drops by several mV, that is, the phenomenon that appears in the area indicated by A in FIG. .

In the dT/dt control, the temperature of the battery is monitored, and charging is terminated when a phenomenon in which the rate of temperature rise rises rapidly, that is, a phenomenon appearing in the region indicated by A in FIG. 2 is detected.

In these -ΔV control and dT/dt control, at the stage of terminating charging, the SOC exceeds the 100% state (fully charged state) and is in a significantly overcharged state, and the internal pressure of the battery has risen. state. In other words, the battery is in a severe state.

On the other hand, in the SOC control method, the amount of current supplied to the battery is measured, the charge capacity is calculated from the integrated value, the ratio between this charge capacity and the full charge capacity is calculated, the SOC is obtained, and this SOC is calculated. reaches 100%, that is, when the battery is fully charged as indicated by B in FIG. 2, charging is terminated. When the SOC is 100%, as is clear from FIG. 2, the degree of increase in pressure inside the battery is slight, and the battery is not in a severe state.

However, in the SOC control method, although there is not much difference between the calculated SOC value and the actual SOC value at the beginning, the calculated SOC value and the actual SOC value become larger as the charging and discharging are repeated. , and even if the calculated SOC value indicates 100% full charge, the actual charge may not be fully charged.

Therefore, in the SOC control method, correction work is required to correct the difference between the calculated SOC value and the actual SOC value. This correction work continues charging even if the calculated SOC value exceeds 100%. Charging is terminated when the pressure of the battery reaches a predetermined pressure value (set pressure value) set in advance within the range of P in FIG. Then, when this charging is completed, the calculated SOC value is rewritten to the actual SOC value corresponding to the set pressure value for correction.

In this correction work, charging is performed until the internal pressure of the battery rises to some extent. . Specifically, the set pressure value is the pressure value ( The pressure value corresponding to the portion indicated by line C in FIG. (Pressure value indicated by point D intersecting line C in FIG. 2) (within range indicated by P in FIG. 2).

As described above, the set pressure value used in the correction work is lower than the pressure value corresponding to the region A reached by the -ΔV control, so the load on the battery is lower than in the case of the -ΔV control.

Next, as a method of determining an arbitrary timing for performing the correction work, it is preferable to set the timing so that the difference between the calculated SOC and the actual SOC becomes too large to be ignored. The magnitude of the difference between the calculated SOC and the actual SOC is basically proportional to the number of charge/discharge cycles. For this reason, for example, it is preferable to set the fact that the number of times of charging has passed a predetermined number of times as a condition that requires correction. Specifically, the control device 60 counts the number of charging times with the counter 86, determines that correction is necessary when the obtained number of times reaches the preset number of times, and starts the correction work. . Since the specific number of times depends on the type of battery and the environment in which it is used, it is preferable to conduct tests in advance and collect data to determine the appropriate number of times. As an example, in a combination of a nickel-hydrogen secondary battery with a rated capacity of 250 Ah and a control device with a power consumption of 9 W, it is preferable to perform correction work when the number of charging reaches 20 times.

Moreover, the magnitude of the difference between the calculated SOC and the actual SOC is also proportional to the passage of time. Specifically, the nickel-metal hydride secondary battery 18 undergoes self-discharge over time, and its actual capacity decreases. In particular, self-discharge progresses when the load 6 is not driven and the nickel-hydrogen secondary battery 18 is left for a long period of time without being discharged. Therefore, the longer the elapsed time, the greater the difference between the calculated SOC and the actual SOC. Therefore, it is preferable that the condition that the correction is required is that the elapsed time from the time when the battery is first fully charged or the time elapsed from the time when the correction work is performed has reached a predetermined time. Specifically, the controller 60 uses the timer 88 to measure the elapsed time from when the nickel-metal hydride secondary battery 18 is first fully charged or the elapsed time from when the correction work is performed. When the elapsed time reaches a preset time, it is determined that correction is necessary, and correction work is started. Since the specific time depends on the type of battery and the environment in which it is used, it is preferable to conduct a test in advance, collect data, and grasp the appropriate time. As an example, in a combination of a nickel-metal hydride secondary battery with a rated capacity of 250 Ah and a control device with a power consumption of 0.2 W when stopped, the elapsed time from the first full charge, or the correction work It is preferable to perform the next correction work when 1000 hours have passed since the time when the above was performed.

Here, even if the number of times of charging has not reached a predetermined number, if the elapsed time reaches the predetermined time, it is preferable to give priority to the elapsed time and perform the correction work.

[Second embodiment]
A power supply device 104 including a charging control system 102 using a secondary battery charging control method according to the present invention will be described below with reference to FIG. In describing the power supply device 104 according to the second embodiment, the same reference numerals as those of the power supply device 4 according to the first embodiment refer to the same configurations as those of the power supply device 4 according to the first embodiment already described. , a detailed description thereof will be omitted, and portions different from the power supply device 4 according to the first embodiment will be described in detail.

In the power supply device 104 , the switch 44 in the power supply device 4 of the first embodiment is omitted, and the positive electrode wiring 34 is directly connected to the first wiring 28 . Furthermore, in the power supply device 104 , an ON/OFF switch 106 is arranged in the middle of the first wiring 28 . The ON/OFF switch 106 switches between a state in which the battery 18 and the external power source 12 are connected and a state in which the battery 18 and the external power source 12 are disconnected. The control device 60 has a switching signal output terminal 178 connected to a switching signal input terminal 174 of the ON/OFF switch 106 via a lead wire 176 .

When charging using the power supply device 104, first, the first cable K1 and the second cable K2 of the load 6 are disconnected from the first output terminal portion 8 and the second output terminal portion 10 of the power supply device 104, respectively. . In this state, control device 60 sends a command signal to ON/OFF switch 106 to connect nickel-metal hydride secondary battery 18 and external power source 12 . The ON/OFF switch 106 connects the nickel-hydrogen secondary battery 18 and the external power supply 12 . After that, the control device 60 sends a drive start command signal to the external power source 12 . As a result, a charging current is supplied from the external power supply 12 to the nickel-hydrogen secondary battery 18, and charging is performed.

When charging is to be terminated, control device 60 sends a command signal to stop charging to external power supply 12 . This completes charging. The controller 60 then sends a command signal to the ON/OFF switch 106 to disconnect the nickel-hydrogen secondary battery 18 from the external power supply 12 . As a result, the nickel-metal hydride secondary battery 18 is disconnected from the external power source 12, and the power supply device 104 is ready for discharge.

The first cable K1 and the second cable K2 of the load 6 are connected to the first output terminal section 8 and the second output terminal section 10 of the power supply device 104 in the dischargeable state, respectively. Thereby, power is supplied to the load 6 .

In the charging operation as described above, charging control based on the SOC similar to that of the first embodiment is performed. Further, the SOC correction work is performed at an arbitrary timing in the same manner as in the first embodiment.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications are possible. In the above-described embodiment, the pressure sensor 24 is separate from the nickel-hydrogen secondary battery 18, but the present invention is not limited to this aspect. It may be built in.
In the present invention, the secondary battery may be a secondary battery such as a nickel-cadmium secondary battery, a lithium-ion secondary battery, or the like, in addition to the nickel-hydrogen secondary battery.

<Aspect of the present invention>

A first aspect of the present invention measures the full charge capacity of a secondary battery, the charging current supplied to the secondary battery, and the discharging current emitted from the secondary battery, and measures these charging currents and discharging currents. The charging rate of the secondary battery is calculated based on the capacity stored in the secondary battery obtained from the value and the charging is started when the obtained calculated charging rate reaches a predetermined lower limit value. and stopping charging when the obtained calculated charging rate reaches a predetermined upper limit value, thereby controlling charging of the secondary battery. A correction step of correcting the value of the calculated charging rate is provided, and the correcting operation is performed in a state in which control for stopping charging is temporarily interrupted when the calculated charging rate reaches a predetermined upper limit value. Charging is continued, during which the battery internal pressure value, which is the internal pressure value of the secondary battery, is measured, and the charging is stopped when the battery internal pressure value reaches a preset pressure value. A charging control method for a secondary battery, wherein the calculated charging rate at the time when the set pressure value is reached is corrected by rewriting it to a new charging rate.

According to a second aspect of the present invention, in the first aspect of the present invention described above, the new charging rate is a correspondence between the previously grasped battery internal pressure value and the actual charging rate of the secondary battery. is the actual charging rate corresponding to the set pressure value obtained from the relationship, and the set pressure value is equal to or greater than the battery internal pressure value corresponding to the case where the actual charging rate of the secondary battery is 100%, and , the range below the battery internal pressure value corresponding to the maximum value of the voltage, which is obtained from the relation between the voltage of the secondary battery and the battery internal pressure value when the secondary battery is charged, which is grasped in advance. This is a charging control method for a secondary battery that is set to a pressure value.

According to a third aspect of the present invention, in the above-described first or second aspect of the present invention, the arbitrary timing is a point in time when the number of times of charging reaches a predetermined number of times. The method.

According to a fourth aspect of the present invention, in the above-described first or second aspect of the present invention, the arbitrary timing is the elapsed time from the first full charge of the secondary battery, or the correction work is a point in time when the elapsed time from the point in time when (1) is performed reaches a predetermined time.

A fifth aspect of the present invention includes a current measuring unit for measuring a charging current supplied to a secondary battery and a discharging current discharged from the secondary battery, and a pressure measuring unit for measuring the internal pressure of the secondary battery. and a control unit for controlling charging and discharging of the secondary battery, wherein the control unit controls the secondary battery obtained from the values of the charging current and the discharging current measured by the current measuring unit. A process of obtaining a calculated charging rate by calculating the charging rate of the secondary battery based on the obtained capacity and the previously obtained full charge capacity of the secondary battery. a process of stopping the supply of the charging current from the external power source when the calculated charging rate reaches a predetermined upper limit value, and making the secondary battery in a state in which it can be discharged to the load; a process of disconnecting the secondary battery from the load when the calculated charging rate reaches a predetermined lower limit value, connecting the secondary battery to the external power supply, supplying the charging current, and starting charging; A correction process for correcting the calculated charging rate, which is performed at an arbitrary timing, wherein once the supply of the charging current from the external power supply is stopped when the calculated charging rate reaches a predetermined upper limit value. Charging is continued even if the calculated charging rate exceeds a predetermined upper limit value after being interrupted, and when the internal pressure of the secondary battery measured by the pressure measuring unit reaches a preset pressure value and a correction process of stopping the supply of the charging current from the external power supply and rewriting the calculated charging rate at the time when the set pressure value is reached to a new charging rate for correction. charging control system.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention described above, the new charging rate is a correspondence between the previously grasped battery internal pressure value and the actual charging rate of the secondary battery. is the actual charging rate corresponding to the set pressure value obtained from the relationship, and the set pressure value is equal to or greater than the battery internal pressure value corresponding to the case where the actual charging rate of the secondary battery is 100%, and , the range below the battery internal pressure value corresponding to the maximum value of the voltage, which is obtained from the relation between the voltage of the secondary battery and the battery internal pressure value when the secondary battery is charged, which is grasped in advance. It is a charging control system for a secondary battery that is set to a pressure value.

According to a seventh aspect of the present invention, in the fifth or sixth aspect of the present invention described above, the control unit further includes a counter for counting the number of times of charging, and the number of times counted by the counter is predetermined. In the charging control system for a secondary battery, the correction process is executed at the timing when the number of times of charging is reached.

According to an eighth aspect of the present invention, in the fifth or sixth aspect of the present invention described above, the control unit further includes a timer capable of measuring elapsed time, and the timer is used to operate the secondary battery. (ii) measuring the elapsed time from the time when the battery is fully charged for the first time, or the elapsed time from the time when the correction work is performed, and executing the correction process when the elapsed time reaches a predetermined time; It is a charging control system for the next battery.

2 charging control system 4 power supply device 6 load 12 external power supply 18 nickel metal hydride secondary battery 24 pressure sensor 48 current sensor 52 voltage sensor 60 control device 86 counter 88 timer

Claims (8)

The full charge capacity of the secondary battery, the charging current supplied to the secondary battery, and the discharging current emitted from the secondary battery are measured, and the secondary battery obtained from these charging current and discharging current values The charging rate of the secondary battery is calculated based on the stored capacity and the charging rate is started when the obtained calculated charging rate reaches a predetermined lower limit value, and the obtained calculated charging rate is In a charging control method for a secondary battery, the charging of the secondary battery is controlled by stopping charging when a predetermined upper limit is reached,
A correction step of performing a correction operation of correcting the value of the calculated charging rate at an arbitrary timing,
In the correction work, charging is continued in a state in which control for stopping charging is temporarily interrupted when the calculated charging rate reaches a predetermined upper limit value, and during that time, the pressure inside the secondary battery is measured. The battery internal pressure value is measured, and the charging is stopped when the battery internal pressure value reaches a preset set pressure value, and the calculated charging rate at the time when the set pressure value is reached is used as a new charging rate. A charge control method for a secondary battery that rewrites and corrects. The new charging rate is an actual charging rate corresponding to the set pressure value, which is obtained from the corresponding relationship between the previously grasped battery internal pressure value and the actual charging rate of the secondary battery,
The set pressure value is equal to or greater than the battery internal pressure value corresponding to the case where the actual charging rate of the secondary battery is 100%, and the secondary 2. The charging of the secondary battery according to claim 1, wherein the pressure value is set within a range equal to or less than the battery internal pressure value corresponding to the maximum value of the voltage, which is obtained from the relationship between the battery voltage and the battery internal pressure value. control method. 3. The charging control method for a secondary battery according to claim 1, wherein said arbitrary timing is a point in time when said number of times of charging reaches a predetermined number of times. The arbitrary timing is the point in time when the elapsed time from the time when the secondary battery is fully charged for the first time or the time elapsed from the time when the correction work is performed reaches a predetermined time. Item 3. The charging control method for a secondary battery according to Item 1 or 2. a current measuring unit that measures a charging current supplied to a secondary battery and a discharging current that is discharged from the secondary battery; and a pressure measuring unit that measures a battery internal pressure value, which is the internal pressure value of the secondary battery. , and a control unit that controls charging and discharging of the secondary battery,
The control unit
The capacity stored in the secondary battery obtained from the values of the charging current and the discharging current measured by the current measuring unit is obtained, and the obtained capacity and the previously obtained full capacity of the secondary battery are obtained. A process of calculating the charging rate of the secondary battery based on the charging capacity and obtaining the calculated charging rate;
a process of stopping the supply of the charging current from the external power supply when the calculated charging rate reaches a predetermined upper limit value, and making the secondary battery into a dischargeable state with respect to the load;
a process of disconnecting the secondary battery from the load when the calculated charging rate reaches a predetermined lower limit, connecting the secondary battery to the external power supply, supplying the charging current, and starting charging; ,
A correction process for correcting the calculated charging rate, which is performed at an arbitrary timing, wherein once the supply of the charging current from the external power supply is stopped when the calculated charging rate reaches a predetermined upper limit value. Charging is continued even if the calculated charging rate exceeds a predetermined upper limit value after being interrupted, and when the internal pressure of the secondary battery measured by the pressure measuring unit reaches a preset pressure value and a correction process of stopping the supply of the charging current from the external power supply and rewriting the calculated charging rate at the time when the set pressure value is reached to a new charging rate for correction. charging control system. The new charging rate is an actual charging rate corresponding to the set pressure value, which is obtained from the corresponding relationship between the previously grasped battery internal pressure value and the actual charging rate of the secondary battery,
The set pressure value is equal to or greater than the battery internal pressure value corresponding to the case where the actual charging rate of the secondary battery is 100%, and the secondary 6. The charging of the secondary battery according to claim 5, wherein the pressure value is set within a range equal to or less than the battery internal pressure value corresponding to the maximum value of the voltage, which is obtained from the relationship between the battery voltage and the battery internal pressure value. control system. 7. The control unit according to claim 5, further comprising a counter that counts the number of times of charging, and executing the correction process when the number of times counted by the counter reaches a predetermined number of times. Charging control system for secondary batteries. The control unit further includes a timer capable of measuring the elapsed time, and using the timer, the elapsed time from the time when the secondary battery is first fully charged, or the time from the time when the correction process is performed 7. The charging control system for a secondary battery according to claim 5, wherein the elapsed time is measured, and the correction process is executed when the elapsed time reaches a predetermined time.

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