JP2011192425A - Memory effect reducing circuit, battery power supply device, battery utilization system, and memory effect reducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a memory effect reducing method capable of reducing a memory effect without discharging an alkali storage battery, a memory effect reducing circuit, a battery power supply device using the memory effect reducing circuit, and a battery utilization system using the memory effect reducing circuit. <P>SOLUTION: The battery utilization system is provided with a charge discharge control circuit 22 charging a secondary battery 21, a heating fan 26 heating the secondary battery 21, and a memory effect reducing treatment part 285 raising a temperature of the secondary battery 21 above a first temperature T1d with the heating fan 26, and charging the secondary battery 21 with a charge discharge control circuit 22 until a charging ratio Rc that is a ratio of a charged electricity volume Q to a theoretical electric capacity Qs reaches a first ratio R1d or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a memory effect reduction method for reducing the memory effect of a secondary battery, a memory effect reduction circuit, a battery power supply device using the memory effect reduction circuit, and a battery utilization system using the memory effect reduction circuit.

  Secondary batteries include lead storage batteries, alkaline storage batteries, and lithium ion secondary batteries. Among them, demand for alkaline storage batteries such as nickel metal hydride storage batteries is expanding mainly in industrial applications such as hybrid vehicles (hereinafter referred to as HEV) and emergency power supplies. For example, in HEV applications, it is used as a main power source for driving a motor. And the alkaline storage battery which is a main power supply performs both motor drive (discharge) and storage (charge) of regenerative power from the generator.

  When the storage battery is used for both power supply (discharge) for driving a load, recovery of regenerative power, and storage, as in the HEV described above, the storage battery is completely discharged (SOC is almost 0%). ), The load cannot be driven. On the other hand, if the battery is fully charged (SOC is almost 100%), the regenerative power cannot be charged any more, resulting in wasted energy.

  Therefore, in a battery power supply device used for such applications, SOC (State Of Charge) is an intermediate value while avoiding complete discharge (SOC is almost 0%) and full charge (SOC is almost 100%) of the storage battery. The charging / discharging of the storage battery is controlled so as to be maintained in the range.

  In addition, in battery power supply devices that are continuously charged and discharged with a large current instantaneously, such as in HEV applications, when a plurality of storage batteries having different capacity are connected individually, the storage battery with the smallest capacity is overcharged. In order to avoid overdischarge, the end voltage at the upper limit SOC (for example, about 80% SOC) that prohibits the charge reaching the SOC more than that, and the lower limit SOC (for example, the SOC20, for example) that prohibits the discharge to the SOC lower than this. %), And a method of controlling charging / discharging between the two end voltages is employed. For this reason, in applications such as HEV, charging / discharging in the intermediate SOC region is repeated.

  By the way, alkaline storage batteries, such as nickel hydride secondary batteries using nickel hydroxide as the positive electrode active material, and alkaline storage batteries such as nickel cadmium secondary batteries, increase the charge voltage when repeated partial charge / discharge cycles without complete discharge. It is known that a so-called memory effect occurs in which the charge / discharge capacity that can actually be used is reduced due to a decrease in the discharge voltage.

  Therefore, as in the above-described battery power supply device for HEV, the user can repeat charging / discharging of the alkaline storage battery in the intermediate SOC region, or the user can use a general battery-equipped device such as a portable personal computer or a mobile phone. When the battery is used for repeated charging before fully discharging the storage battery, there is a disadvantage that the memory effect occurs and the substantial charge / discharge capacity decreases.

  Various techniques have been proposed to reduce the influence of the memory effect. For example, a method is known in which the number of shallow charging / discharging times is counted, and when the specified number of times is reached, it is determined that the memory effect has occurred in the battery, and the battery is forcibly completely discharged (see, for example, Patent Document 1). .)

  Moreover, in the system which controls charging / discharging so as to maintain the SOC within a certain range when using an alkaline storage battery, such as the HEV described above, the memory effect is determined while detecting the voltage, current, and temperature of the battery, When it is determined that the memory effect has occurred, a method of reducing the memory effect by widening the allowable range of the SOC and consequently causing a discharge close to a complete discharge is known (see, for example, Patent Document 2). .)

JP-A-7-122304 Japanese Patent Laid-Open No. 2003-9408

  However, in the method described in Patent Document 1, since the alkaline storage battery is completely discharged in order to eliminate the memory effect, there is an inconvenience that the user cannot use the battery-equipped device until the storage battery is charged again. Moreover, since the alkaline storage battery is completely discharged only to eliminate the memory effect, there is a disadvantage that energy is wasted.

  Moreover, in the method described in Patent Document 2, since the allowable range of SOC of the storage battery in the use state is expanded, as a result, a discharge close to complete discharge is performed, so that it is more than the allowable range of SOC originally required by the system. However, it is not preferable because the storage battery is discharged until the SOC becomes small.

  An object of the present invention is to provide a memory effect reduction method, a memory effect reduction circuit, a battery power supply device using the memory effect reduction circuit, and a memory effect reduction circuit capable of reducing the memory effect without discharging the alkaline storage battery. It is to provide a used battery utilization system.

  A memory effect reduction circuit according to the present invention includes a charging unit that charges an alkaline storage battery, a heating unit that heats the alkaline storage battery, and a memory effect reduction processing unit that performs a memory effect reduction process that reduces the memory effect of the alkaline storage battery. The memory effect reduction processing is performed by causing the temperature of the alkaline storage battery to be equal to or higher than a preset first temperature by the heating unit, and charging that is a ratio of a charge electricity amount to a theoretical electric capacity of the alkaline storage battery. This is a process of charging by the charging unit until the ratio becomes equal to or higher than a preset first ratio.

  In addition, the memory effect reduction method according to the present invention includes a charging step for charging an alkaline storage battery, a heating step for heating the alkaline storage battery, and a memory effect reduction process for executing a memory effect reduction process for reducing the memory effect of the alkaline storage battery. The memory effect reducing process includes a step of causing the temperature of the alkaline storage battery to be equal to or higher than a preset first temperature, and a charge ratio that is a ratio of a charged electricity amount to a theoretical electric capacity of the alkaline storage battery. This is a process of charging the alkaline storage battery until it reaches a preset first ratio or higher.

  According to this configuration, the temperature of the alkaline storage battery is set to be equal to or higher than a first preset temperature, and the charge ratio that is the ratio of the charge electricity amount to the theoretical electric capacity of the alkaline storage battery is set to a first preset ratio. The memory effect reduction process for charging the alkaline storage battery is executed until the above is reached, and the memory effect of the alkaline storage battery is reduced. The present inventors have found that the memory effect of the alkaline storage battery is reduced by such a memory effect reduction process. Thereby, the memory effect can be reduced without discharging the alkaline storage battery.

  In the memory effect reduction processing, the memory effect reduction processing unit causes the temperature of the alkaline storage battery to be higher than the first temperature and lower than a preset second temperature by the heating unit. It is preferable.

  According to this configuration, in the memory effect reduction process, the alkaline storage battery is charged in a state where the temperature of the alkaline storage battery is equal to or higher than the first temperature and equal to or lower than the second temperature. The present inventors have found that the memory effect of the alkaline storage battery is reduced by such a memory effect reduction process. Thereby, the memory effect can be reduced without discharging the alkaline storage battery.

  The first temperature is preferably 40 ° C, and the second temperature is preferably 60 ° C.

  According to this configuration, in the memory effect reduction process, the alkaline storage battery is charged in a state where the temperature of the alkaline storage battery is 40 ° C. or higher and 60 ° C. or lower. The present inventors have found that the memory effect of the alkaline storage battery is reduced by such a memory effect reduction process. Thereby, the memory effect can be reduced without discharging the alkaline storage battery.

  In the memory effect reduction processing, the memory effect reduction processing unit performs the memory effect reduction processing so that the charging ratio is equal to or higher than the first ratio and equal to or lower than a preset second ratio. It is preferable to charge.

  According to this configuration, in the memory effect reduction process, the alkaline storage battery is charged such that the charging ratio is equal to or higher than the first ratio and equal to or lower than the second ratio. The present inventors have found that the memory effect of the alkaline storage battery is reduced by such a memory effect reduction process. Thereby, the memory effect can be reduced without discharging the alkaline storage battery.

  The first ratio is preferably 80%, and the second ratio is preferably 140%.

  According to this configuration, in the memory effect reduction process, the alkaline storage battery is charged so that the charging ratio is 80% or more and 140% or less. The present inventors have found that the memory effect of the alkaline storage battery is reduced by such a memory effect reduction process. Thereby, the memory effect can be reduced without discharging the alkaline storage battery.

  The memory effect detection unit further detects a memory effect occurrence in the alkaline storage battery, and the memory effect reduction processing unit is configured to detect the memory effect when the memory effect detection unit detects the occurrence of the memory effect. It is preferable to perform a reduction process.

  According to this configuration, when a memory effect occurs in the alkaline storage battery, the memory effect detection unit detects the occurrence of the memory effect. The memory effect reduction processing unit automatically executes the memory effect reduction processing when the memory effect is detected by the memory effect detection unit, that is, when the memory effect occurs in the alkaline storage battery. Since the memory effect is reduced, user convenience is improved.

  Moreover, it is preferable to further include a cooling unit that cools the alkaline storage battery, and the memory effect reduction processing unit cools the alkaline storage battery by the cooling unit after the memory effect reduction processing is completed.

  When the alkaline storage battery is used and charged / discharged while being heated in the memory effect reduction process and in a high temperature state, the alkaline storage battery may be deteriorated. Therefore, according to this configuration, when the memory effect reduction process is completed, the alkaline storage battery is cooled by the cooling unit, so that the possibility that the alkaline storage battery is used while being in a high temperature state after the memory effect reduction process is reduced. Therefore, it is possible to reduce the risk of deterioration of the alkaline storage battery.

  Further, by integrating the current value detected by the current detection unit and the current detection unit that detects the current value of the charge / discharge current of the alkaline storage battery, the amount of electricity charged in the alkaline storage battery is converted into the charge electricity. It is preferable to further include a charge electricity amount calculation unit that calculates the amount.

  According to this configuration, the current value of the charge / discharge current of the alkaline storage battery detected by the current detection unit is integrated by the charge electricity amount calculation unit, and the charge electricity amount is calculated. The memory effect reduction processing can be executed based on the charge electricity amount calculated by the charge electricity amount calculation unit.

  The alkaline storage battery is preferably a nickel hydride secondary battery.

  The memory effect reduction process described above can be suitably applied to a nickel metal hydride secondary battery.

  In addition, a battery power supply device according to the present invention includes the above-described memory effect reduction circuit and the alkaline storage battery.

  According to this configuration, in the battery power supply device including the alkaline storage battery, the memory effect can be reduced without discharging the alkaline storage battery.

  In addition, a battery utilization system according to the present invention includes the above-described memory effect reduction circuit, the alkaline storage battery, and a drive unit for realizing an application, and the heating unit is discharged along with the operation of the drive unit. It is preferable to heat the alkaline storage battery by transporting the waste heat to the alkaline storage battery.

  According to this configuration, in the battery utilization system including the above-described memory effect reduction circuit, the alkaline storage battery, and the driving unit for realizing the application, the memory effect can be reduced without discharging the alkaline storage battery. . Moreover, since the alkaline storage battery can be heated by the waste heat discharged with the operation of the drive unit, it is easy to reduce energy for heating the alkaline storage battery.

  The memory effect reduction circuit, the battery power supply device, the battery utilization system, and the memory effect reduction method having such a configuration can reduce the memory effect without discharging the alkaline storage battery.

It is a block diagram which shows notionally an example of a structure of the memory effect reduction circuit using the memory effect reduction method which concerns on one Embodiment of this invention, a battery power supply device, and a battery utilization system. It is a flowchart which shows an example of operation | movement of the battery power supply device shown in FIG. It is a flowchart which shows an example of operation | movement of the battery power supply device shown in FIG. It is a table | surface which shows the experimental result performed in order to confirm the cancellation effect of a memory effect using the nickel hydride secondary battery which is an example of an alkaline storage battery.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. FIG. 1 is a block diagram conceptually showing an example of the configuration of a memory effect reduction circuit, a battery power supply device, and a battery utilization system using a memory effect reduction method according to an embodiment of the present invention.

  A battery utilization system 1 shown in FIG. 1 is a simplified illustration of a hybrid vehicle, for example, and includes a battery power supply device 2, a motor 3, an engine 4, and ducts 6 and 7. The motor 3 and the engine 4 are accommodated in the engine room 5. In this case, the motor 3 and the engine 4 correspond to an example of a drive unit for realizing a hybrid vehicle.

  The battery utilization system is not limited to a hybrid vehicle. For example, tough uses such as home cogeneration systems and industrial power systems, solar power generation systems, backup power supply devices such as UPS, portable personal computers, digital cameras, mobile phones, electric vehicles, etc. The battery power supply device 2 can be used as a power source for battery-utilizing systems such as devices and systems.

  The battery power supply 2 includes a secondary battery 21, a charge / discharge control circuit 22 (charging unit), a voltage detecting unit 23, a current detecting unit 24, a temperature detecting unit 25, a heating fan 26 (heating unit), and a cooling fan 27 ( A cooling unit) and a control unit 28. The motor 3 is connected to the charge / discharge control circuit 22. In this case, the remaining part excluding the secondary battery 21 from the battery power supply device 2 corresponds to an example of a memory effect reduction circuit.

  The duct 6 is disposed so as to guide the high-temperature air in the engine room 5 to the heating fan 26. The duct 7 is disposed so as to guide outside air outside the vehicle to the cooling fan 27.

  The secondary battery 21 is an alkaline storage battery, for example, a nickel hydride secondary battery. The secondary battery 21 may be configured as an assembled battery in which a plurality of cells are combined. The secondary battery 21 is connected to the charge / discharge control circuit 22 via the current detection unit 24.

  When the motor 3 is driven, the charge / discharge control circuit 22 discharges the secondary battery 21 and supplies the discharge current to the motor 3. The charge / discharge control circuit 22 charges the secondary battery 21 with the regenerative current generated by the motor 3. Based on the SOC (State Of Charge) of the secondary battery 21 transmitted from the control unit 28, the charge / discharge control circuit 22 normally has the SOC of the secondary battery 21 within a range of about 20 to 80%. The charging / discharging of the secondary battery 21 is controlled.

  The battery utilization system 1 may include a load circuit driven by the power from the secondary battery 21 and a power generation device instead of the motor 3. Then, the charge / discharge control circuit 22 charges the secondary battery 21 with surplus power from the power generation device, or when the consumption current of the load circuit suddenly increases, or the power generation amount of the power generation device decreases to request the load device. When the electric power to be exceeded exceeds the output of the power generation device, insufficient power may be supplied from the secondary battery 21 to the load device.

  Alternatively, the charge / discharge control circuit 22 may be connected to, for example, a commercial power source and charge the secondary battery 21 with electric power obtained from the commercial power source.

  The voltage detection unit 23 is configured by an analog-digital converter, for example, and detects the terminal voltage of the secondary battery 21. Then, the voltage detection unit 23 outputs a signal indicating a terminal voltage value Vt that is a voltage value of the terminal voltage to the control unit 28.

  The current detection unit 24 includes, for example, a resistance element connected in series with the secondary battery 21, a current transformer, an analog-digital converter, and the like, and detects a charge / discharge current flowing through the secondary battery 21. Then, the current detector 24 outputs a signal indicating the detected charge / discharge current value Ic to the controller 28. For example, when the detected charging / discharging current is in the charging direction of the secondary battery 21, the current detection unit 24 indicates the current value Ic as a positive value, and in the discharging direction of the secondary battery 21, The current value Ic is indicated by a negative value.

  The temperature detection unit 25 includes, for example, a thermocouple, a thermistor, an analog / digital converter, and the like, and detects the temperature t of the secondary battery 21. Then, the temperature detection unit 25 outputs a signal indicating the temperature t to the control unit 28.

  The heating fan 26 is driven in accordance with a control signal from the control unit 28, sucks high-temperature air in the engine room 5 due to waste heat of the motor 3 and the engine 4 through the duct 6, and recharges the secondary battery. By hitting 21, the secondary battery 21 is heated. The heating unit is not limited to one that heats the secondary battery 21 by conveying high-temperature air generated by the waste heat of the drive unit. For example, the waste heat is removed using a heat conductive material or a heat pipe. The secondary battery 21 may be heated by being transported to the secondary battery 21.

  The heating unit may be a heater. However, by configuring the heating unit using a configuration that conveys waste heat using the heating fan 26, heat conduction, or the like, the energy required for heating is higher than when the secondary battery 21 is heated using a heater. It is easy to reduce.

  The cooling fan 27 is driven according to a control signal from the control unit 28, sucks outside air through the duct 7, and applies it to the secondary battery 21 to cool the secondary battery 21. The cooling unit may cool the secondary battery 21 using, for example, a Peltier element, and the cooling means is not limited.

  The control unit 28 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a nonvolatile ROM (Read Only Memory) that stores a predetermined control program, and a RAM (Random) that temporarily stores data. Access Memory) and its peripheral circuits and the like.

  Further, the control unit 28 executes, for example, a control program stored in the ROM, so that the charge amount calculation unit 281, the SOC calculation unit 282, the charge ratio calculation unit 283, the memory effect detection unit 284, and the memory effect reduction process It functions as the unit 285.

  The charge amount calculation unit 281 continuously accumulates the current value Ic output from the current detection unit 24, for example, every unit time, and thereby the charge amount that is charged in the secondary battery 21. The quantity Q is calculated. At the time of this integration, for example, when the current value Ic indicates the charging direction (+), the charging electricity amount calculation unit 281 multiplies the current value Ic by the charging efficiency (a coefficient smaller than 1, for example, 0.8). Accumulate from

  The SOC calculation unit 282 uses the following formula (1) based on the charge electricity amount Q calculated by the charge electricity amount calculation unit 281 and the full charge capacity FCC of the secondary battery 21 to The SOC is calculated and transmitted to the charge / discharge control circuit 22.

SOC = (Q / FCC) × 100 (%) (1)
Here, the full charge capacity FCC of the secondary battery 21 is equal to the theoretical electric capacity Qs in the initial state where the secondary battery 21 has not deteriorated. However, when the secondary battery 21 deteriorates with use, the full charge capacity FCC decreases, and becomes smaller than the theoretical electric capacity Qs.

  Therefore, the SOC calculation unit 282, for example, the current value detected by the current detection unit 24 when the secondary battery 21 is discharged from the fully charged state until the terminal voltage value Vt reaches a preset discharge end voltage. By calculating Ic, the discharge charge amount from the fully charged state to the complete discharge is calculated, and the discharge charge amount is used as the full charge capacity FCC to correct the decrease in the full charge capacity FCC due to deterioration. It is like that.

  The theoretical electric capacity Qs is a theoretical battery capacity of the secondary battery 21 determined by the composition of the active material used for the electrode of the secondary battery 21 and the amount of the active material.

  The charge ratio calculation unit 283 is based on the charge electricity amount Q calculated by the charge electricity amount calculation unit 281 and the theoretical electric capacity Qs of the secondary battery 21, for example, using the following formula (2), the secondary battery. A charging ratio Rc of 21 is calculated. Formula (2) shows an example in which the charge ratio Rc is expressed as a percentage.

Rc = (Q / Qs) × 100 (%) (2)
The memory effect detection unit 284 detects the occurrence of the memory effect in the secondary battery 21. Specifically, for example, the memory effect detection unit 284 is configured to detect the terminal voltage detected by the voltage detection unit 23 when the charging ratio Rc calculated by the charging ratio calculation unit 283 reaches a preset reference ratio Rref. When the value Vt is less than the preset reference voltage Vref, it is determined that the memory effect has occurred in the secondary battery 21.

  The reference voltage Vref can be set as follows, for example. For example, when the secondary battery 21 in the initial state that has not yet deteriorated is charged so that the charging ratio Rc becomes the reference ratio Rref, the terminal voltage value Vt has a margin and is slightly lower than the terminal voltage value Vt. The voltage value can be set as the reference voltage Vref.

  Also, any value can be selected as the reference ratio Rref. However, from the viewpoint of increasing the chance of detecting the occurrence of the memory effect in the secondary battery 21, it is desirable to set the value of the charging ratio Rc that is likely to be actual in the normal use state as the reference ratio Rref. For example, 50% can be used as the reference ratio Rref.

  For example, when the secondary battery 21 is a single cell of a nickel hydride secondary battery and the reference ratio Rref is 50%, 1.20 V can be used as the reference voltage Vref. When the secondary battery 21 is an assembled battery in which a plurality of nickel-hydrogen secondary battery cells are connected in series, a value obtained by multiplying the series number by 1.20 V can be used as the reference voltage Vref.

  The memory effect detection unit 284 is not limited to a specific method for detecting the memory effect. The memory effect detection unit 284 detects the occurrence of the memory effect in the secondary battery 21 by, for example, the method described in Japanese Patent Laid-Open No. 7-122304, the method described in Japanese Patent Laid-Open No. 2003-9408, or other methods. You may do.

  The memory effect reduction processing unit 285 executes the following memory effect reduction processing only when the memory effect detection unit 284 detects the occurrence of the memory effect. That is, the memory effect reduction processing unit 285 drives the heating fan 26 so that the temperature t detected by the temperature detection unit 25, that is, the temperature t of the secondary battery 21, is equal to or higher than the first temperature T1d and the second temperature T2u. Increase to the following temperature.

  Then, when the temperature t falls within the temperature range of the first temperature T1d and the second temperature T2u, the memory effect reduction processing unit 285 sets the charge ratio Rc calculated by the charge ratio calculation unit 283 to the first ratio. Charging current is supplied from the charge / discharge control circuit 22 to the secondary battery 21 to charge the secondary battery 21 until the set ratio Rs is set to a ratio not less than R1d and not more than the second ratio R2u.

  The first temperature T1d can be 40 ° C., and the second temperature T2u can be 60 ° C. Further, 80% can be used as the first ratio R1d, and 140% can be used as the second ratio R2u. The first temperature T1d, the second temperature T2u, the first ratio R1d, and the second ratio R2u are not necessarily limited to 40 ° C., 60 ° C., 80%, and 140%. By performing the above, it can be appropriately set according to the characteristics of the secondary battery 21 actually used.

  Next, the operation of the battery power supply device 2 using the memory effect reduction circuit configured as described above will be described. 2 and 3 are flowcharts showing an example of the operation of the battery power supply device 2 shown in FIG.

  First, the voltage detection unit 23 detects the terminal voltage value Vt of the secondary battery 21, the current detection unit 24 detects the current value Ic of the current flowing through the secondary battery 21, and the temperature detection unit 25 detects the secondary battery 21. The temperature t is detected (step S1).

  Next, the charge electricity amount calculation unit 281 integrates the current value Ic detected by the current detection unit 24, for example, per unit time to calculate the charge electricity amount Q (step S2).

  Then, based on the charge electricity amount Q calculated by the charge electricity amount calculation unit 281 and the theoretical electric capacity Qs of the secondary battery 21 by the charge ratio calculation unit 283, for example, using the above equation (2), The charging ratio Rc of the secondary battery 21 is calculated (step S3).

  The processes of steps S1 to S3 are always executed continuously, and are executed in parallel with the process shown in the flowchart of FIG. As a result, the terminal voltage value Vt, current value Ic, temperature t, and charge ratio Rc are constantly updated to the latest values.

  Next, referring to FIG. 3, the memory effect detection unit 284 compares the charge ratio Rc with the reference ratio Rref (step S11). Then, the memory effect detection unit 284 repeats step S11 until the charge ratio Rc and the reference ratio Rref become equal by discharging (NO in step S11), and when the charge ratio Rc and the reference ratio Rref become equal by discharging (step S11). YES), the process proceeds to step S12.

  In step S12, the memory effect detection unit 284 compares the terminal voltage value Vt with the reference voltage Vref (step S12). If the terminal voltage value Vt is equal to or higher than the reference voltage Vref, it is determined that no memory effect has occurred. Then, the process proceeds again to step S11 (NO in step S12).

  On the other hand, if the terminal voltage value Vt does not satisfy the reference voltage Vref (YES in step S12), the memory effect detection unit 284 determines that the memory effect is occurring, and hereinafter, the memory effect reduction in steps S13 to S19. The process proceeds to step S13 to execute the process.

  As described above, the battery detection device further includes a voltage detection unit that detects a terminal voltage of the alkaline storage battery, and the memory effect detection unit is configured to detect the voltage detection unit when the charge ratio of the alkaline storage battery reaches a preset reference ratio. When the terminal voltage detected by the above is less than a preset reference voltage, the occurrence of the memory effect in the alkaline storage battery is detected.

  According to this configuration, the memory effect detection unit can detect the occurrence of the memory effect in the alkaline storage battery when the terminal voltage when the charging ratio of the alkaline storage battery becomes the reference ratio is less than the reference voltage.

  As described above, according to the processes of steps S1 to S3 and steps S11 and S12, it is detected that the memory effect has occurred in the secondary battery 21, and the memory effect reduction process is automatically executed. Improves.

  Note that the memory effect detection unit 284 may execute step S12 using the terminal voltage value Vt that is a discharge voltage only when the secondary battery 21 is discharged, that is, when the current value Ic is a negative value. Good. In the secondary battery 21, the voltage drops more due to the memory effect than the open circuit voltage (OCV). Therefore, it is better to use the discharge voltage to determine whether the memory effect occurs or not. The detection accuracy of the memory effect is improved as compared with the case where the presence or absence of the memory effect is determined using the voltage.

  In addition, the memory effect detection unit 284 performs step S12 using the terminal voltage value Vt that is the discharge voltage in a state where the secondary battery 21 is discharged at a preset reference current value, for example, 1 It. It may be. In this case, since the discharge current value of the secondary battery 21 at the time of determining the memory effect is always a constant value, variation in determination conditions for determining whether or not the memory effect has occurred is reduced, and the memory effect is improved. Detection accuracy is improved.

  Here, 1 It (battery capacity (Ah) / 1 (h)) is a theoretical electric capacity (nominal capacity) of the secondary battery 21 discharged at a constant current, and the remaining capacity of the secondary battery 21 is zero in one hour. Is a current value.

  Next, the heating fan 26 is driven by the memory effect reduction processing unit 285, and hot air in the engine room 5 is taken in through the duct 6 and supplied to the secondary battery 21 (step S13). Thereby, the secondary battery 21 is heated and the temperature t rises.

  Next, the memory effect reduction processing unit 285 compares the temperature t with the first temperature T1d (for example, 40 ° C.) (step S14), and if the temperature t does not satisfy the first temperature T1d (NO in step S14), Returning to step S13, heating of the secondary battery 21 is continued. On the other hand, when the temperature t becomes equal to or higher than the first temperature T1d (YES in step S14), a request signal for requesting charging is output from the memory effect reduction processing unit 285 to the charge / discharge control circuit 22, and the charge / discharge control circuit 22 A charging current is supplied to the secondary battery 21, and the secondary battery 21 is charged (step S15).

  Next, the memory effect reduction processing unit 285 compares the charge ratio Rc and the set ratio Rs (step S16). If the charge ratio Rc does not satisfy the set ratio Rs (NO in step S16), the process proceeds to step S17. Then, the temperature t is compared with the second temperature T2u (for example, 60 ° C.) (step S17).

  If the temperature t does not reach the second temperature T2u (NO in step S17), the temperature t is within the range of the first temperature T1d and the second temperature T2u, and therefore the memory effect reduction processing unit 285. Moves directly to step S14 and repeats the subsequent processing. On the other hand, if the temperature t is equal to or higher than the second temperature T2u (YES in step S17), since the temperature t exceeds the second temperature T2u if heating is continued as it is, the memory effect reduction processing unit 285 causes the heating fan 26 to be heated. Is stopped and the temperature t is maintained within the range of the first temperature T1d or higher and the second temperature T2u or lower (step S18).

  On the other hand, in step S16, when the charging ratio Rc increases with charging and becomes equal to or greater than the set ratio Rs (YES in step S16), the set ratio Rs is within the range of the first ratio R1d and the second ratio R2u. Therefore, the charging ratio Rc of the secondary battery 21 is in the range of the first ratio R1d or more and the second ratio R2u or less. At this time, the inventors of the present invention have found that the memory effect in the secondary battery 21 is eliminated, as shown in Examples described later.

  Therefore, when the charge ratio Rc is equal to or higher than the set ratio Rs (YES in step S16), it is considered that the memory effect in the secondary battery 21 has been eliminated, so that the charge / discharge control circuit 22 is charged from the memory effect reduction processing unit 285. A request signal for requesting a stop is output, charging of the secondary battery 21 by the charge / discharge control circuit 22 is stopped (step S19), and the memory effect reduction process is terminated.

  And the memory effect reduction process part 285 stops the fan 26 for a heating after completion | finish of a memory effect reduction process. Then, the memory effect reduction processing unit 285 cools the secondary battery 21 by driving the cooling fan 27 and sucking low temperature outside air through the duct 7 and supplying it to the secondary battery 21 (step). S20).

  The secondary battery 21 is heated to the first temperature T1d or higher during the memory effect reduction process. However, when the secondary battery 21 is used in a high temperature state equal to or higher than the first temperature T1d and is charged / discharged, there is a risk of deterioration, which is not preferable. Therefore, the memory effect reduction processing unit 285 cools the secondary battery 21 to a temperature suitable for use after the memory effect reduction process is finished, so that the secondary battery 21 is used after the memory effect reduction process is finished. The risk of deterioration during charging and discharging is reduced.

  In step S16, the first ratio R1d may be used instead of the set ratio Rs. In step S16, instead of comparing the charging ratio Rc and the set ratio Rs, it is directly determined whether or not the charging ratio Rc is within the range of the first ratio R1d and the second ratio R2u. If it is within the range, the process may proceed to step S19, and if it is out of the range, the process may proceed to step S17.

  However, for example, in a battery-based system that does not need to leave room for regenerative power in the secondary battery 21, such as a portable personal computer, a digital camera, a mobile phone, and an electric vehicle, the setting ratio Rs is set to 100%, for example. By setting, the secondary battery 21 can be fully charged when the memory effect reduction processing is completed, so that convenience for the user is improved.

  Further, in a battery utilization system that needs to leave room for regenerative power in the secondary battery 21 as in a hybrid vehicle, the setting ratio Rs is set to, for example, the first ratio R1d (for example, 80%). Thus, the possibility that the secondary battery 21 cannot accept the regenerative power and wastes energy is reduced.

  As described above, according to the memory effect reduction processing in steps S13 to S19, the secondary battery 21 is charged in a state where the temperature t is maintained within the range of the first temperature T1d and the second temperature T2u. Charging is performed until the ratio Rc falls within the range of the first ratio R1d or more and the second ratio R2u or less. Thereby, since the memory effect can be reduced, the memory effect can be reduced without discharging the secondary battery 21.

  Note that the temperature detection unit 25 is provided, and the temperature t of the secondary battery 21 is set to the first temperature T1d or higher and the second temperature T2u by the processes of steps S14 and S17 based on the temperature t detected by the temperature detection unit 25. Although an example of maintaining within the following range has been shown, the temperature detector 25 is not necessarily provided.

  For example, by using a heating unit such as a heating fan 26 or a heater, the heating time required to bring the temperature t of the secondary battery 21 into the range between the first temperature T1d and the second temperature T2u is obtained in advance. In step S14, after such a heating time has elapsed, the process may move to step S15.

  Further, the memory effect detection unit 284 and steps S11 and S12 may not be provided, and the memory effect reduction process after step S13 may be executed at an arbitrary timing, for example, in response to a user operation instruction.

  FIG. 4 is a table showing the results of an experiment conducted to confirm the elimination effect of the memory effect using a nickel hydride secondary battery which is an example of an alkaline storage battery. The nickel hydride secondary battery used in the experiment was manufactured as follows.

  First, add nickel hydroxide to cobalt hydroxide, carboxymethylcellulose (CMC, degree of etherification 0.7, degree of polymerization 1600), polytetrafluoroethylene (PTFE), add water and knead, paste Obtained. This paste was applied to both sides of a foam type nickel substrate. The coating film of the paste was pressed with a roller together with the substrate after drying. Thus, a positive electrode having a thickness of 0.4 mm, a width of 40 mm, a length of 850 mm, and a capacity of 5000 mAh was obtained. In addition, the lead part was provided in the one end part along the longitudinal direction of a positive electrode.

An LmNi ₅ system having an exposed portion at one end along the longitudinal direction and having a thickness of 0.3 mm, a width of 40 mm, a length of 930 mm, and a capacity of 7500 mAh (where Lm is a light rare earth element, ie, La, Nd, Ce, Pr) A nickel-hydrogen secondary battery having a nominal capacity (theoretical electric capacity) of 5000 mAh in D size was manufactured using a negative electrode using a hydrogen storage alloy of (showing the mixture).

  Specifically, the positive electrode and the negative electrode were wound through a separator (thickness: 100 μm) made of a sulfonated polypropylene nonwoven fabric to produce a cylindrical electrode plate group. In the electrode plate group, the exposed portion of the positive electrode core material that does not carry the positive electrode mixture and the exposed portion of the negative electrode core material that does not carry the negative electrode mixture were exposed on the opposite end surfaces. A positive electrode current collector plate was welded to the end face of the electrode plate group from which the positive electrode core material was exposed. The negative electrode current collector plate was welded to the end face of the electrode plate group where the negative electrode core material was exposed, while the positive electrode tab connected to the positive electrode current collector plate was welded to the sealing plate.

  Then, after the negative electrode current collector plate was placed downward and the electrode plate group was accommodated in a battery case made of a cylindrical bottomed can, the negative electrode tab connected to the negative electrode current collector plate was welded to the bottom of the battery case. Further, after injecting an alkaline electrolyte mainly composed of potassium hydroxide, the opening of the battery case was sealed with a sealing plate having a gasket on the periphery, and a nickel metal hydride secondary battery was produced.

  The nickel-metal hydride secondary battery (theoretical electric capacity 5000 mAh) produced in this way is charged from 30% to 70% with a discharge current of 1 It (5000 mA) in a 25 ° C. atmosphere and from 70% to 30%. 50 charge / discharge cycles were carried out to discharge until.

  At this time, during the discharge in the first charge / discharge cycle, the discharge voltage when the charge ratio Rc was 50% was 1.25V. Further, 1.20 V was used as the reference voltage Vref for determining that the memory effect occurred.

  When discharging in the 50th charge / discharge cycle, the discharge voltage when the charge ratio Rc was 50% was 1.14 V, which was lower than the reference voltage Vref. Thereby, it was confirmed that the memory effect occurred in the nickel-hydrogen secondary battery to be tested.

  The nickel hydride secondary battery in which the memory effect is generated in this manner is placed in each atmosphere of 35 ° C., 40 ° C., 50 ° C., 60 ° C., and 70 ° C., and the temperature t of the nickel hydride secondary battery is set to After the temperature was reached, charging was performed at a charging current of 1 It (5000 mA) at each temperature until the charging ratio Rc reached 75%, 80%, 110%, 140%, and 150%, respectively. Thereafter, the nickel-hydrogen secondary battery charged at each ratio was discharged at 1 It (5000 mA), and the discharge voltage when the charge ratio Rc was 50% was measured. The measured value Vm of the discharge voltage thus obtained is shown in the table of FIG.

  First, when the ambient temperature (temperature t) is 35 ° C., the measured value Vm is less than 1.20 V which is the reference voltage Vref in all cases where the charge ratio Rc is charged to 75% to 150%, Therefore, the memory effect has not been eliminated.

  When the ambient temperature (temperature t) is 70 ° C., the measured value Vm is less than the reference voltage Vref 1.20 V when the charging ratio Rc is 75% or 85%, and therefore the memory effect is eliminated. There wasn't. Further, when the ambient temperature (temperature t) is 70 ° C. and the charging ratio Rc is 110% or more, the oxygen overvoltage decreases, the electrolytic solution is decomposed excessively, and the generation of oxygen is excessive. A liquid was generated, and the measured value Vm could not be measured.

  When the charging ratio Rc is 150%, the measured value Vm is less than 1.20 V which is the reference voltage Vref in the entire temperature range of 35 ° C. to 60 ° C. in which the measured value Vm can be measured. The effect did not go away.

  On the other hand, when the ambient temperature (temperature t) is in the temperature range of 40 ° C. or higher and 60 ° C. or lower, and when the charging ratio Rc is in the range of 80% or higher and 140% or lower, all measured values are obtained. Vm was 1.24 V to 1.25 V, exceeding the reference voltage Vref of 1.20 V, and it was confirmed that the memory effect was eliminated.

  In particular, the nickel hydride secondary battery used in the experiment has a measured value Vm of 1.25 V at the time of discharge in the first charge / discharge cycle, that is, when neither deterioration nor memory effect occurs in the initial state.

  Then, when the temperature range is 40 ° C. or more and 60 ° C. or less, and the charging ratio Rc is charged until the range is 80% or more and 140% or less, the measured value Vm is 1.24V to 1.25V. This means that the measured value Vm after the memory effect elimination processing is within the error range of the effective number of 1.25 V, which is the initial value, and the memory effect is almost completely eliminated, which is extremely good. The experimental results were obtained.

  From this experimental result, it was confirmed that 40 ° C. as the first temperature T1d, 60 ° C. as the second temperature T2u, 80% as the first ratio R1d, and 140% as the second ratio R2u were preferable. .

  The first ratio R1d, the second ratio R2u, the first temperature T1d, and the second temperature T2u can be appropriately set by the same experiment, and are heated to a temperature exceeding 60 ° C. If it can be confirmed that the effect of eliminating the memory effect can be obtained even when charging is performed at a charge ratio exceeding%, the second ratio R2u and the second temperature T2u may not be used.

  The memory effect reduction circuit, the battery power supply device, the battery utilization system, and the memory effect reduction method according to the present invention can implement a power supply system that reduces the memory effect with a simple configuration. (HEV, household cogeneration, industrial use) The applicability is high and the effect is considered high. In addition, the memory effect reduction circuit, battery power supply device, battery utilization system, and memory effect reduction method according to the present invention can be suitably used in various systems that use an alkaline battery that produces a memory effect.

DESCRIPTION OF SYMBOLS 1 Battery utilization system 2 Battery power supply device 3 Motor 4 Engine 5 Engine room 6, 7 Duct 21 Secondary battery 22 Charge / discharge control circuit 23 Voltage detection part 24 Current detection part 25 Temperature detection part 26 Heating fan 27 Cooling fan 28 Control Unit 281 charge amount calculation unit 282 SOC calculation unit 283 charge ratio calculation unit 284 memory effect detection unit 285 memory effect reduction processing unit Ic current value Q charge amount Qs theoretical electric capacity R1d first ratio R2u second ratio Rc charge ratio Rref Reference ratio Rs Setting ratio T1d First temperature T2u Second temperature Vm Measured value Vref Reference voltage Vt Terminal voltage value

Claims (12)

A charging unit for charging the alkaline storage battery;
A heating unit for heating the alkaline storage battery;
A memory effect reduction processing unit for executing a memory effect reduction process for reducing the memory effect of the alkaline storage battery,
The memory effect reduction process is:
The heating unit causes the temperature of the alkaline storage battery to be equal to or higher than a preset first temperature, and a charging ratio that is a ratio of the charged electricity amount to the theoretical electric capacity of the alkaline storage battery is equal to or higher than a preset first ratio. The memory effect reduction circuit, which is a process of charging by the charging unit until. The memory effect reduction processing unit
In the memory effect reduction process,
2. The memory effect reduction circuit according to claim 1, wherein the temperature of the alkaline storage battery is set to a temperature not lower than the first temperature and not higher than a preset second temperature by the heating unit. The first temperature is 40 ° C.
The memory effect reduction circuit according to claim 2, wherein the second temperature is 60 ° C. The memory effect reduction processing unit
In the memory effect reduction process,
The charging part is charged by the charging unit such that the charging ratio is equal to or higher than the first ratio and equal to or lower than a preset second ratio. The memory effect reducing circuit according to 1. The first ratio is 80%;
The memory effect reduction circuit according to claim 4, wherein the second ratio is 140%. A memory effect detection unit for detecting occurrence of a memory effect in the alkaline storage battery;
The memory effect reduction processing unit
The memory effect reduction circuit according to claim 1, wherein when the occurrence of the memory effect is detected by the memory effect detection unit, the memory effect reduction process is executed. A cooling unit for cooling the alkaline storage battery;
The memory effect reduction processing unit
The memory effect reduction circuit according to claim 1, wherein the alkaline storage battery is cooled by the cooling unit after completion of the memory effect reduction process. A current detector for detecting a current value of a charge / discharge current of the alkaline storage battery;
The electric charge amount calculation part which calculates the electric charge currently charged in the alkaline storage battery as the charge electric quantity by accumulating the electric current value detected by the current detection part further comprises the above-mentioned. The memory effect reduction circuit according to any one of 1 to 7. The memory effect reduction circuit according to claim 1, wherein the alkaline storage battery is a nickel metal hydride secondary battery. The memory effect reduction circuit according to any one of claims 1 to 9,
A battery power supply comprising the alkaline storage battery. The memory effect reduction circuit according to any one of claims 1 to 9,
The alkaline storage battery;
A drive unit for realizing the application,
The heating unit is
A battery utilization system, wherein the alkaline storage battery is heated by carrying waste heat discharged along with the operation of the drive unit to the alkaline storage battery. A charging process for charging the alkaline storage battery;
A heating step of heating the alkaline storage battery;
A memory effect reduction processing step for executing a memory effect reduction process for reducing the memory effect of the alkaline storage battery,
The memory effect reduction process is:
Until the temperature of the alkaline storage battery is equal to or higher than a preset first temperature, and the charge ratio that is the ratio of the amount of charge to the theoretical electrical capacity of the alkaline storage battery is equal to or higher than a preset first ratio, A method for reducing the memory effect, which is a process of charging the alkaline storage battery.

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