JP4724047B2 - Charging system, battery pack and charging method thereof - Google Patents

Description

  The present invention relates to a charging system, a battery pack, and a charging method thereof, and more particularly to a charging method for cell balance disruption due to deterioration of a secondary battery in which a plurality of cells are connected in series.

  FIG. 7 is a graph for explaining a general charging voltage and current management method during charging of the secondary battery. FIG. 7 is a graph in the case of a lithium ion battery. Reference numeral α1 indicates a change in voltage of the secondary battery, and reference numeral α2 indicates a change in charging current supplied to the secondary battery.

  First, with regard to the voltage, a trickle charge region is reached from the start of charging, a small constant current I1, for example, 50 mA of charging current is supplied, and the cell voltage of each of the plurality of cells is the end voltage Vm of trickle charging, for example 2. This trickle charge is continued until 5V is reached.

  When the cell voltage reaches the end voltage Vm, it switches to the constant current (CC) charge region, and the terminal voltage at the charge terminal of the battery pack is 4.2 V per cell. In this case, the end voltage Vf is applied to the charging terminal until the voltage reaches 12.6 V), and a predetermined constant current I2, for example, a nominal capacity value NC is discharged at a constant current to a level that can be discharged in one hour. As 1C, a charging current obtained by multiplying 70% of the number by the number P of parallel cells is supplied, and constant current (CC) charging is performed.

  As a result, when the terminal voltage of the charging terminal reaches the termination voltage Vf, the charging voltage is switched to the constant voltage (CV) charging region, the charging current value is decreased so as not to exceed the termination voltage Vf, and the charging current value is When the current value I3 set by the temperature decreases, it is determined that the battery is fully charged, and the supply of the charging current is stopped. The charge control method as described above can be read from Patent Document 1, for example.

  On the other hand, in the case of overcharging, the safety of the lithium secondary battery is deteriorated. Therefore, in Patent Document 2, when overcharging is detected, subsequent charging is prohibited, but by allowing discharging, overcharging is prevented. There has been proposed a charge / discharge control circuit capable of responding to an emergency (use of a load device) while suppressing the accompanying decrease in safety.

In Patent Document 3, information associated with charging / discharging, particularly overcharge information is detected by self-diagnosis and stored in a memory, and the data is later analyzed by the manufacturer, which is useful for improvement and design. Such a battery pack has been proposed.
JP-A-6-78471 Japanese Patent No. 3469711 JP 2003-17138 A

  However, although the prior art of Patent Document 2 has extremely high safety, there is a problem that a battery pack that has been overcharged once becomes unusable and wasteful. Further, in the prior art of Patent Document 3, when the overcharge state is resolved (cell voltage decreases), the battery is restored so that it can be charged again. However, the overcharge information is not reflected at the time of charge, and the overcharge is performed. There is a problem that the life of the battery pack is shortened repeatedly.

  Particularly in recent years, since it is desired to fully charge the battery, the end voltage Vf is close to an overcharge detection voltage, for example, 4.35 V. Has risen from about 75 to 80 ° C. to about 80 to 85 ° C., and overcharge and overtemperature abnormalities are likely to occur.

  Further, in the case of a secondary battery in which a plurality of cells are connected in series, the charger controls the terminal voltage of the charging terminal by the total voltage of the number of series cells. For example, the end voltage Vf is 3 cell series In this case, the voltage is controlled to be 12.6V. For this reason, even if the terminal voltage of the charging terminal is accurately controlled to the final voltage Vf, if the deterioration of a specific cell progresses and the cell balance is lost, a large voltage is applied only to that cell, resulting in overcharging. There is a problem that the deterioration further proceeds.

  An object of the present invention is to provide a charging system, a battery pack, and a charging method thereof that can extend the life of a battery by suppressing characteristic deterioration while ensuring safety.

A charging system according to the present invention includes a secondary battery, a battery pack including a communication unit and a charge / discharge control unit, and a charger including a charging current supply unit, a communication unit and a charge control unit. The charging / discharging control means transmits at least information on a charging voltage and a charging current to be requested when charging a secondary battery built in the battery pack to the charging control means of the charger via the communication means, and the charger The charge control means causes the charge current supply means to supply the charge voltage and charge current in response to the request to the battery pack, so that in the battery pack, the cell voltage of the secondary battery is preset. Constant current charging is performed to supply a constant charging current so as to be a voltage, and when the final voltage is reached, the charging current is decreased so as to maintain the final voltage. Yuku in the charging system constant voltage charging is performed, the battery pack, a voltage detector, a temperature sensor, overcharge determines whether the cell voltage detected by said voltage detecting means becomes overcharged In response to the determination results of the determination unit, the over-temperature determination unit that determines whether or not the temperature detected by the temperature sensor is in an over-temperature state, and the over-charge determination unit and the over-temperature determination unit, A counter that counts the number of times of overheating and the number of times of overtemperature, and a threshold value that is set in advance in response to the count result of the counter. exceeds the number, the with the charge and discharge control means reduces by previously determining a voltage the end voltage to request a charging voltage to the charger, it overcharged in the counter Characterized in that it comprises a setting means for both resetting the number of times and the number of times that the over temperature.

The battery pack of the present invention includes a secondary battery, a communication unit, and a charge / discharge control unit, and the charge / discharge control unit transmits a request for a charge voltage and a charge current to the charger via the communication unit. Thus, constant current charging is performed to supply a constant charging current to the secondary battery so that the cell voltage of the secondary battery becomes a preset end voltage by the charging voltage and charging current supplied from the charger. reaches the end voltage, so as to maintain the end voltage in the battery pack the constant voltage charging Yuku reduces the charging current is performed, a voltage detector, a temperature sensor, by the voltage detecting means and overcharge determination unit that determines whether the cell voltage detected becomes overcharged, and determining the over temperature determining unit that determines whether the temperature detected by the temperature sensor reaches an over-temperature condition, the In response to the determination results of the charge determination unit and the overtemperature determination unit, the counter that counts the number of times of overcharge and the number of times of overtemperature, and the overcharge in response to the count result of the counter When any one of the number of times or the number of times of overtemperature exceeds a predetermined threshold number of times, the charge / discharge control means reduces the end voltage required as a charging voltage to the charger by a predetermined voltage, and And setting means for resetting both the number of times of overcharging and the number of times of overtemperature in the counter .

According to the above configuration, the overcharge state and the over-temperature condition of the above is a parameter indicating the deterioration of the secondary battery, and use it we determine the presence or absence of deterioration of the secondary battery, it is determined that the degradation Then, the setting means sets the end voltage that the charge / discharge control means requests as a charging voltage to the charger to be low.

  Therefore, the secondary battery can be charged so as not to be overcharged, safety can be improved, and battery life can be extended by suppressing characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

Furthermore , since the end voltage is lowered as the number of times of overcharge or overtemperature, that is, the degree of deterioration increases, it is possible to always fully charge the actual capacity at that time. Here, the setting means does not directly request the end voltage, but simply notifies the charge control means of the charger via the communication means that the overcharge state or the overtemperature state has occurred. The same effect can be obtained even if the charge control means is made to determine the optimum end voltage.

The battery pack of the present invention includes a secondary battery, a communication unit, and a charge / discharge control unit, and the charge / discharge control unit transmits a request for a charge voltage and a charge current to the charger via the communication unit. Thus, constant current charging is performed to supply a constant charging current to the secondary battery so that the cell voltage of the secondary battery becomes a preset end voltage by the charging voltage and charging current supplied from the charger. reaches the end voltage, so as to maintain the end voltage in the battery pack the constant voltage charging Yuku reduces the charging current is performed, a voltage detector, a temperature sensor, by the voltage detecting means and overcharge determination unit that determines whether the cell voltage detected becomes overcharged, and determining the over temperature determining unit that determines whether the temperature detected by the temperature sensor reaches an over-temperature condition, the In response to the determination results of the charge determination unit and the overtemperature determination unit, the counter that counts the number of times of overcharge and the number of times of overtemperature, and the overcharge in response to the count result of the counter When either one of the number of times or the number of times of overtemperature exceeds a predetermined threshold number of times, the voltage applied to the secondary battery is reduced , and the number of times of overcharge and the overtemperature in the counter are reduced. And a voltage drop means for resetting the number of occurrences together.

According to the above configuration, the overcharge state and the over-temperature condition of the above is a parameter indicating the deterioration of the secondary battery, and use it we determine the presence or absence of deterioration of the secondary battery, it is determined that the degradation Then, a voltage reduction means reduces the end voltage of the constant voltage charge provided from a charger.

  Therefore, the secondary battery can be charged so as not to be overcharged, safety can be improved, and battery life can be extended by suppressing characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

Furthermore , since the voltage applied to the secondary battery decreases as the number of overcharged or overheated conditions, that is, the degree of deterioration increases, always charge to the full capacity at that time. Can do.

The charging system of the present invention includes a secondary battery, a battery pack including a communication unit and a charge / discharge control unit, and a charger including a charging current supply unit, a communication unit and a charge control unit, and the battery The charging / discharging control means of the pack transmits at least information on the charging voltage and charging current that should be requested when charging the secondary battery built in the battery pack to the charging control means of the charger via the communication means, In the battery pack, the charging control means of the charger causes the charging current supply means to supply the charging voltage and charging current in response to the request to the battery pack, so that in the battery pack, the charging / discharging control means includes the secondary battery. Constant current charging is performed to supply a constant charging current to the secondary battery so that the cell voltage of the cell reaches a preset end voltage, and when the end voltage is reached, the charging current is reduced to O When the cell voltage reaches a preset charge resumption voltage lower than the end voltage within a predetermined period, the charge current is turned on, and when the cell voltage does not drop to the charge resumption voltage within a predetermined period, in it it is determined that charging has to perform the pulse charging to stop charging the charging system, the battery pack, a voltage detector, a temperature sensor, the cell voltage detected by said voltage detecting means and overcharged An overcharge determination unit that determines whether or not the temperature is detected , an overtemperature determination unit that determines whether or not the temperature detected by the temperature sensor is in an overtemperature state, and the overcharge determination unit and the overtemperature determination unit A counter that counts the number of times of overcharge and overtemperature in response to the determination result, and the number of times of overcharge in response to the count result of the counter. Either the number of the over temperature, advance exceeds a threshold number of times determined in advance, and the final voltage of the charge and discharge control means for requesting a charging voltage to the charger, at least one of said charge resumption voltage And setting means for resetting both the number of overcharges and the number of overtemperatures in the counter while reducing the voltage by a predetermined voltage .

According to the above configuration, the overcharge state and the over-temperature condition of the above is a parameter indicating the deterioration of the secondary battery, and use it we determine the presence or absence of deterioration of the secondary battery, it is determined that the degradation Then, the setting means sets the end voltage requested by the charging / discharging control means to the charger as a charging voltage, or lowers the charging resumption voltage when the charging / discharging control means performs pulse charging.

  Therefore, the secondary battery can be charged so as not to be overcharged, safety can be improved, and battery life can be extended by suppressing characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

Furthermore, the battery pack of the present invention comprises a secondary battery and a charge / discharge control means, and the charge / discharge control means determines the cell voltage of the secondary battery in advance by the charge voltage and the charge current supplied from the charger. Constant current charging is performed to supply a constant charging current to the secondary battery so as to achieve a set end voltage. When the end voltage is reached, the charge current is turned off, and the cell voltage is stopped within a predetermined period. The charging current is turned on when a preset charging resumption voltage lower than the voltage is reached, and when the cell voltage does not drop to the charging resumption voltage within a predetermined period, it is determined that the battery is fully charged and pulse charging is performed to stop charging. in the battery pack as a voltage detecting means, a temperature sensor, and the voltage overcharge determination unit that determines whether the cell voltage detected is overcharged by the detection means, the temperature An over temperature determining section determines whether the temperature detected becomes over-temperature condition by a sensor, responsive to said overcharge determination unit and the over temperature determining portion of the determination results, the number of times and over temperatures overcharged A counter that counts the number of times each becomes, and in response to the count result of the counter, when either the number of times of overcharging or the number of times of overtemperature exceeds a predetermined threshold number of times, And a setting means for reducing the charge resumption voltage by a predetermined voltage and resetting both the number of overcharges and the number of overtemperatures in the counter .

According to the above configuration, the overcharge state and the over-temperature condition of the above is a parameter indicating the deterioration of the secondary battery, and use it we determine the presence or absence of deterioration of the secondary battery, it is determined that the degradation Then, the setting means reduces the charge resumption voltage when the charge / discharge control means performs pulse charging.

  Therefore, the secondary battery can be charged so as not to be overcharged, safety can be improved, and battery life can be extended by suppressing characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

  In the battery pack of the present invention, the secondary battery is characterized in that a plurality of cells are connected in series.

  According to the above configuration, even if charging is performed by controlling the voltage of a secondary battery in which a plurality of cells are connected in series in response to the request for the charging voltage, the secondary battery is deteriorated. The cell balance can be prevented from being overcharged with respect to the loss of cell balance due to the above, and the present invention is particularly suitable.

Furthermore, the charging method of the present invention performs constant current charging for supplying a constant charging current toward a preset end voltage to the secondary battery, and maintains the end voltage when the end voltage is reached. , in the charging method of performing constant-voltage charging Yuku reduces the charging current, when the secondary battery is on purpose overcharged or over-temperature shape,-out the number of times counted respectively Teyu, a said overcharge When either one of the number of times or the number of times of over-temperature exceeds a predetermined threshold number of times , the end voltage is reduced, and the count value of the number of times of over-charging and the number of times of over-temperature is set. Both are reset .

According to the above configuration, the overcharge state and the over-temperature condition of the above is a parameter indicating the deterioration of the secondary battery, and use it we determine the presence or absence of deterioration of the secondary battery, it is determined that the degradation Then, the end voltage of constant voltage charging is set low.

  Therefore, the secondary battery can be charged so as not to be overcharged, safety can be improved, and battery life can be extended by suppressing characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

Further, the charging method of the present invention performs constant current charging for supplying a constant charging current toward a preset end voltage to the secondary battery, and maintains the end voltage when the end voltage is reached. in charging method of performing pulse charging, when the battery is on purpose made overcharged or over-temperature form, the number-out count respectively Teyu, any number of times said overcharged and since the number of times or over-temperature If either of these exceeds a predetermined threshold number of times , at least one of the charge resumption voltage or the charge voltage used for the pulse charging is lowered, and the count value of the number of times of overcharge and the number of times of overtemperature is set. Both are reset .

According to the above configuration, the overcharge state and the over-temperature condition of the above is a parameter indicating the deterioration of the secondary battery, and use it we determine the presence or absence of deterioration of the secondary battery, it is determined that the degradation Then, at least one of the charge resumption voltage or the charge voltage for pulse charging is set low.

  Therefore, the secondary battery can be charged so as not to be overcharged, safety can be improved, and battery life can be extended by suppressing characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

Charging system and the battery pack of the present invention, as described above, overcharge and over-temperature conditions, by utilizing the fact that a parameter representing the deterioration of the secondary battery, the secondary battery using it al The presence / absence of deterioration is determined, and when it is determined that the battery is deteriorated, the setting means causes the setting means to set the charging voltage required by the charger as the end voltage.

  Therefore, the secondary battery can be charged so as not to be overcharged, the safety can be improved, and the battery life can be extended by suppressing the characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

The battery pack of the present invention, as described above, overcharge and over-temperature conditions, by utilizing the fact that a parameter representing the deterioration of the secondary battery, deterioration of the secondary battery using it al When it is determined that the battery has deteriorated, the voltage reduction means lowers the end voltage of the constant voltage charge applied from the charger to the secondary battery.

  Therefore, the secondary battery can be charged so as not to be overcharged, the safety can be improved, and the battery life can be extended by suppressing the characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

The charging system of the present invention, as described above, overcharge and over-temperature conditions, by utilizing the fact that a parameter representing the deterioration of the secondary battery, deterioration of the secondary battery using it al When it is determined that the battery has deteriorated, the setting means causes the charge / discharge control means to set the end voltage required as a charging voltage to the charger to be low, or the charge when the charge / discharge control means performs pulse charging. Reduce restart voltage.

  Therefore, the secondary battery can be charged so as not to be overcharged, the safety can be improved, and the battery life can be extended by suppressing the characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

The battery pack of the present invention, as described above, overcharge and over-temperature conditions, by utilizing the fact that a parameter representing the deterioration of the secondary battery, deterioration of the secondary battery using it al When it is determined that the battery has deteriorated, the setting means reduces the charge resumption voltage when the charge / discharge control means performs pulse charging.

  Therefore, the secondary battery can be charged so as not to be overcharged, the safety can be improved, and the battery life can be extended by suppressing the characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

Furthermore, the charging method of the present invention, as described above, overcharge and over-temperature conditions, by utilizing the fact that a parameter representing the deterioration of the secondary battery, the secondary battery using it al The presence / absence of deterioration is determined, and when it is determined that deterioration occurs, the end voltage of constant voltage charging is set low.

  Therefore, the secondary battery can be charged so as not to be overcharged, the safety can be improved, and the battery life can be extended by suppressing the characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

Furthermore, the charging method of the present invention, as described above, overcharge and over-temperature conditions, by utilizing the fact that a parameter representing the deterioration of the secondary battery, the secondary battery using it al The presence / absence of deterioration is determined, and when it is determined that deterioration occurs, at least one of the charge resumption voltage or the charging voltage for pulse charging is set low.

  Therefore, the secondary battery can be charged so as not to be overcharged, the safety can be improved, and the battery life can be extended by suppressing the characteristic deterioration. In addition, overcharge can be prevented against a failure in which the output voltage on the charger side increases.

[Embodiment 1]
FIG. 1 is a block diagram showing an electrical configuration of a charging system using a charging method according to an embodiment of the present invention. The charging system includes a battery pack 1 and a charger 2 that charges the battery pack 1. However, an electronic device system may be configured to further include a load device (not shown) that receives power from the battery pack 1. . In that case, although the battery pack 1 is charged from the charger 2 in FIG. 1, the battery pack 1 may be attached to the load device and charged through the load device. The battery pack 1 and the charger 2 are connected to each other by DC high-side terminals T11 and T21 that supply power, communication signal terminals T12 and T22, and GND terminals T13 and T23 for power supply and communication signals. . Similar terminals are also provided when the load device is provided.

  In the battery pack 1, the DC high-side charging path 11 extending from the terminal T11 includes FETs 12 and 13 having different conductivity types for charging and discharging, and the charging path 11 Is connected to the high-side terminal of the battery pack 14. A low side terminal of the assembled battery 14 is connected to the GND terminal T13 via a DC low side charging path 15, and the charging path 15 includes a current detection resistor 16 that converts charging current and discharging current into voltage values. Is intervened.

  The assembled battery 14 includes a plurality of secondary battery cells connected in series and parallel, and the temperature of the cells is detected by a temperature sensor 17 and input to an analog / digital converter 19 in a control IC 18. The voltage between the terminals of each cell is read by the voltage detection circuit 20 and input to the analog / digital converter 19 in the control IC 18. Furthermore, the current value detected by the current detection resistor 16 is also input to the analog / digital converter 19 in the control IC 18. The analog / digital converter 19 converts each input value into a digital value and outputs the digital value to the charge control determination unit 21.

  The charge control determination unit 21 includes a microcomputer and its peripheral circuits, etc., and in response to each input value from the analog / digital converter 19, a charge current for requesting an output from the charger 2. The voltage value, current value, and pulse width (duty) are calculated and transmitted from the communication unit 22 to the charger 2 via the terminals T12 and T22; T13 and T23. In addition, the charging control determination unit 21 detects an abnormality outside the battery pack 1 such as a short circuit between the terminals T11 and T13 or an abnormal current from the charger 2 from each input value from the analog / digital converter 19. A protection operation such as blocking the FETs 12 and 13 is performed against an abnormal temperature rise of the assembled battery 14.

  In the charger 2, the control IC 30 receives the request by the communication unit 32 that is the communication unit, and the charge control unit 31 that is the charge control unit controls the charge current supply circuit 33 that is the charge current supply unit. The charging current is supplied with the voltage value, the current value, and the pulse width. The charging current supply circuit 33 is composed of an AC-DC converter, a DC-DC converter, etc., and converts an input voltage into a voltage value, a current value, and a pulse width instructed by the charging control unit 31, and a terminal T21, T11: Supply to charging paths 11 and 15 via T23 and T13.

  In the battery pack 1, a trickle charging circuit 25 is provided in the DC high-side charging path 11 in parallel with the normal (rapid) charging FET 12. The trickle charging circuit 25 includes a series circuit of a current limiting resistor 26 and an FET 27, and the charge control determination unit 21 sets the discharging FET 13 at the initial stage of charging and when performing auxiliary charging near full charge. The FET 12 for rapid charging is turned OFF while the FET 12 is ON, and the trickle charging FET 27 is turned ON to perform trickle charging. During normal charging and discharging, the FET 12 is turned ON while the FET 13 remains ON. Is turned off, and charging / discharging with normal current is performed.

  It should be noted that in the present embodiment, the charging control determination unit 21 transmits a request for a charging voltage and a charging current to the charger 2 via the communication unit 22 which is a communication unit. In the charge control of trickle charge, constant current (CC) charge, and constant voltage (CV) charge as shown, when the cell voltage detected by the voltage detection circuit 20 as the voltage detection means is in an overcharge state, the temperature When the temperature detected by the temperature sensor 17 serving as the detection means becomes an overtemperature state, the information is stored, and the end voltage Vf is set based on the stored information.

  FIG. 2 is a block diagram showing a specific configuration example of the charge control determination unit 21 of the control IC 18. The charge control determination unit 21 includes a charge / discharge control unit 41, a setting unit 42, a counter 43, an overcharge determination unit 44, and an overtemperature determination unit 45.

  The charge / discharge control unit 41, which is a charge / discharge control means, performs charge / discharge control and protection operation against abnormality, and information on cell voltage, charge / discharge current, and cell temperature input from the analog / digital converter 19. Based on the above, the voltage value, current value, pulse width (duty) and presence / absence of abnormality of the charging current required for the charger 2 are transmitted from the communication unit 22 via the terminal T12, or the FETs 12, 13, 27 ON / OFF control etc. are performed.

  Of the input values from the analog / digital converter 19, the cell voltage and the cell temperature are also input to an overcharge determination unit 44 and an overtemperature determination unit 45, respectively. The overcharge determination unit 44 determines an overcharge state when the cell voltage detected by the voltage detection circuit 20 exceeds a predetermined voltage, for example, 4.35 V, and adds the count value of the number of overcharges in the counter 43. Update. The over temperature determination unit 45 detects that the cell temperature detected by the temperature sensor 17 is over a predetermined temperature, for example, less than 0 ° C. or 60 ° C. or more at the time of charging and 80 ° C. or more at the temperature of discharging. The temperature state is determined, and the count value of the number of overtemperatures in the counter 43 is added and updated.

  When the overcharge determining unit 44 determines that the battery is in an overcharged state during charging, the charge / discharge control unit 41 turns off the FETs 12 and 27 to stop the charging operation, and the cell voltage is lowered and excessively charged. When the charge state is canceled, the battery returns to a chargeable state. Similarly, when it is determined by the overtemperature determination unit 45 that the overtemperature state is during charge / discharge, the charge / discharge control unit 41 turns off the FETs 12, 13, and 27 to stop the charge / discharge, When the temperature of the cell decreases or rises and the overtemperature state is resolved, the cell returns to a chargeable / dischargeable state. The cancellation threshold value for the overcharge state and the cancellation threshold value for the overtemperature state may be the same as the above-described determination threshold value, but may be set to be stricter and have hysteresis.

  On the other hand, when the deterioration of the cell is determined from the count values of the overcharge count and the overtemperature count in the counter 43 serving as the storage section, the setting section 42 serving as the setting section determines the constant in the charge / discharge control section 41. The end voltage Vf at the time of voltage (CV) charging is lowered. Thus, the charge / discharge control unit 41 requests the charging voltage from the communication unit 22 to the charger 2 with a new end voltage Vf. Further, when the end voltage Vf is changed, the count values of the overcharge count and the overtemperature count in the counter 43 are reset so that the overcharge count and the overtemperature count can be counted again.

  FIG. 3 is a flowchart for explaining the operation of the setting unit 42 as described above. When switching from trickle charging to constant current constant voltage (CC-CV) charging, the count values of the overcharge number Novp and the overtemperature number Notp are read out from the counter 43 in step S1, and each of the threshold values 3 is set in step S2. It is determined whether or not the first and second times are exceeded, and if neither is exceeded, the end voltage Vf is not changed and the process is terminated.

  In contrast, in step S2, if any one of the count values of the overcharge number Novp and the overtemperature number Notp exceeds the threshold value, the process proceeds to step S3, where the current end voltage Vfn is changed to the charge / discharge control unit. 41. In step S4, a value obtained by subtracting 50 mV per series cell from the end voltage Vfn is obtained as a new end voltage Vfn + 1. In step S5, the charge / discharge control unit 41 is set, and a request to the charger 2 is made. Done. Thereafter, in step S6, the counter 43 is reset, and the process ends.

  As described above, in the charging method according to the present embodiment, the overcharge state and the overtemperature state are parameters representing the deterioration of the secondary battery. Therefore, these overcharge determination and overtemperature determination essential for safety control are performed. The result is used to determine whether or not the secondary battery has deteriorated. When the deterioration is determined, the setting unit 42 sets the constant voltage (CV) charge end voltage Vf from the charge / discharge control unit 41 to the charger 2 low. Therefore, the secondary battery can be charged so as not to be overcharged, safety can be improved, and battery life can be extended by suppressing characteristic deterioration. In addition, overcharge can be prevented against a failure that increases the output voltage on the charger 2 side.

  Furthermore, the setting unit 42 sets the end voltage Vf lower as the number of times Novp, Notp, that is, the degree of deterioration, that has become the overcharged state or the overtemperature state is increased. It can be fully charged up to the actual capacity.

  Further, when the assembled battery 14 is formed by connecting a plurality of cells in series, the charger 2 performs charging by totally controlling the voltage between the charging terminals T11 and T13 in response to the request for the charging voltage. However, it is possible to perform charging so that a specific cell does not become overcharged against the loss of cell balance due to deterioration of the secondary battery, and the present invention is particularly suitable.

[Embodiment 2]
FIG. 4 is a block diagram showing an electrical configuration of a charging system using a charging method according to another embodiment of the present invention. This charging system is similar to the charging system shown in FIG. 1, and corresponding portions are denoted by the same reference numerals, and the description thereof is omitted. It should be noted that in this charging system, the battery pack 1 a is provided with a decompression circuit 51 in parallel with the trickle charging circuit 25. The decompression circuit 51 is formed by connecting a variable resistor 52 in series with an FET 53, and the resistance value of the variable resistor 52 and ON / OFF of the FET 53 are controlled by the charge control determination unit 21a of the control IC 18a.

  FIG. 5 is a block diagram showing a specific configuration example of the charge control determination unit 21a of the control IC 18a. The charge control determination unit 21a includes a charge / discharge control unit 41a, a resistance adjustment unit 46, a counter 43, an overcharge determination unit 44, and an overtemperature determination unit 45.

  The charge / discharge control unit 41a, which is a charge / discharge control means, performs charge / discharge control and a protection operation against an abnormality, as with the charge / discharge control unit 41, and is a cell input from the analog / digital converter 19 Based on the information on the voltage, charging / discharging current and cell temperature, the voltage value, current value, pulse width (duty) of the charging current required for the charger 2 and the presence / absence of abnormality are communicated from the communication unit 22 via the terminal T12. Transmission or ON / OFF control of the FETs 12, 13, and 27 is performed.

  On the other hand, when the deterioration of the cell is determined from the count values of the overcharge count and the overtemperature count in the counter 43, the resistance adjustment section 46 causes the charge / discharge control section 41a to charge the constant voltage (CV). The FET 12 that is the charging path is turned off, and the FET 53 of the decompression circuit 51 is turned on instead, and the resistance value of the variable resistor 52 is set to a value corresponding to the count value of the counter 43.

  Specifically, during the charging control as shown in FIG. 7, the charging / discharging control unit 41a cannot maintain the constant current I2 because the charging current detected by the current detection resistor 16 becomes constant current (CC) charging. When it is detected that the region has been switched to the constant voltage (CV) charging region, the resistance adjusting unit 46 turns off the charging FET 12 in the charging / discharging control unit 41a and turns on the FET 53 of the decompression circuit 51 instead. Then, corresponding to the current value at that time, a voltage to be reduced from the final voltage Vf, for example, when abnormality determination is performed three times in the past and three cells are connected in series as the assembled battery 14, 50 mV × 3 The resistance value of the variable resistor 52 is controlled so that x3 = 450 mV. At this time, the charging voltage requested by the charging / discharging control unit 41a to the charger 2 remains the final voltage Vf. Therefore, the resistance adjusting unit 46 and the decompression circuit 51 constitute a voltage lowering unit.

  Even with this configuration, the secondary battery can be charged so as not to be overcharged, safety can be improved, and battery life can be reduced by suppressing characteristic deterioration. Can be extended. In addition, overcharge can be prevented against a failure that increases the output voltage on the charger 2 side.

  In general, in the constant current (CC) charging region, charging is performed with a large current of 0.7 C or more as described above, and the voltage actually applied to each cell due to the internal resistance of the secondary battery is: It is considerably smaller than the voltage applied between the terminals. For this reason, in the above description, even for abnormal batteries, the FET 53 of the decompression circuit 51 is turned on after switching to the constant voltage (CV) charging region, and the applied voltage is decompressed, but the constant current (CC) The pressure may be reduced from the second half of the charging area.

[Embodiment 3]
FIG. 6 is a graph for explaining a charging method according to still another embodiment of the present invention. The charging system shown in FIG. 1 can be used for this charging method. In the battery pack 1a described above, as the capacity of the assembled battery 14 increases, the current value that the variable resistor 52 of the decompression circuit 51 must limit, and thus the voltage value that must cause a voltage drop, increases. Therefore, it should be noted in the present embodiment that charging / discharging control of the charge control determination unit 21 is not performed by the decompression circuit 51 but when the constant voltage (CV) charging region is switched in the configuration shown in FIG. The unit 41 performs the constant voltage (CV) charging by pulse charging for turning on / off the FET 12 for charging, and the cell voltage detected by the voltage detection circuit 20 during the OFF is the predetermined charging resumption voltage Vr. Then, when resuming charging, the setting unit 42 decreases the charging resumption voltage Vr by the number of overcharges and the number of overtemperatures.

  This will be described in detail with reference to FIG. When charging is started, as described above with reference to FIG. 7, the voltage Vcv (which is switched to the constant voltage (CV) charging) or the pulse charging is changed from the trickle charging region to the constant current (CC) charging region. Rapid charging is performed toward the switching voltage Vpulse). In FIG. 6, the voltage and current waveforms after the constant current (CC) charging region are shown by (a) and (b), respectively. When the cell voltage detected by the voltage detection circuit 20 reaches the end voltage Vf at time t1, the charge / discharge control unit 41 switches to a constant voltage (CV) charge region that maintains the end voltage Vf, and is used for charging. The FET 12 is temporarily turned off. At this time, the charging voltage required for the charger 2 is kept constant at the end voltage Vf. The requested charging current may remain constant or may be a small value.

  Thereafter, the voltage drop due to the internal resistance decreases due to the stop of the charging current, and the cell voltage decreases, and at time t2 from the stop of the charging current at time t1 until time t3 when a predetermined time W elapses. When the charge resumption voltage Vr is reached, the charge / discharge control unit 41 turns on the FET 12 again at the time t3. As a result, the same operation as at the time t1, t2, t3 is repeated at the time t4, t5, t6..., And the cell voltage is applied until the time W elapses after the FET 12 is turned off at the time t7. If the voltage does not drop to the charging restart voltage Vr, it is determined that the battery is fully charged, and the charging operation is terminated.

  When performing such a charging operation, the rechargeable voltage Vr is decreased by the number of overcharges and the number of overtemperatures so that the secondary battery is not overcharged as described above. Thus, safety can be improved and battery life can be extended by suppressing characteristic deterioration. In addition, overcharge can be prevented against a failure that increases the output voltage on the charger 2 side. Furthermore, according to this configuration, in the case of a battery pack that performs pulse charging, the charger 2 side can be handled only by the battery pack 1 side with the conventional state.

  Furthermore, in the configuration in which the same pulse charging is performed, when the charging voltage is requested to the battery pack 2 as in the case of the battery pack 1, the setting unit 42 sets the end voltage Vf according to the number of times of overcharge and the number of overtemperatures. However, both the end voltage Vf and the charge resumption voltage Vr may be decreased. Various aspects of such pulse charging are described in detail in Japanese Patent No. 3580828 previously proposed by the present applicant.

  The present invention can charge a battery pack in which the secondary battery has been deteriorated so that the secondary battery is not overcharged, thereby improving safety and reducing characteristics. By suppressing it, the battery life can be extended, and overcharge can be prevented against failures that increase the output voltage on the charger side. The charging system and the battery pack can be suitably implemented.

It is a block diagram which shows the electric constitution of the charging system using the charging method which concerns on one Embodiment of this invention. It is a block diagram which shows one specific structural example of the charge control determination part which implement | achieves the charging method of one Embodiment of this invention. It is a flowchart for demonstrating the charging method of one Embodiment of this invention. It is a block diagram which shows the electric constitution of the charging system using the charging method which concerns on other embodiment of this invention. It is a block diagram which shows one specific structural example of the charge control determination part which implement | achieves the charging method of other form of implementation of this invention. It is a graph for demonstrating the charging method of other form of implementation of this invention. It is a graph for demonstrating the general management method of charging voltage and electric current.

1, 1a Battery pack 2 Charger 11, 15 Charging path 12, 13, 27, 53 FET
14 assembled battery 16 current detection resistor 17 temperature sensor 18, 18a, 30 control IC
19 Analog / digital converter 20 Voltage detection circuit 21, 21a Charging control determination unit 22, 32 Communication unit 25 Trickle charging circuit 26 Current limiting resistor 31 Charging control unit 33 Charging current supply circuit 41, 41a Charging / discharging control unit 42 Setting unit 43 Counter 44 Overcharge determination unit 45 Over temperature determination unit 46 Resistance adjustment unit 51 Depressurization circuit 52 Variable resistors T11, T21; T12, T22; T13, T23 terminals

Claims (8)

A battery pack comprising a secondary battery, communication means and charge / discharge control means, and a charger comprising charge current supply means, communication means and charge control means, wherein the charge / discharge control means of the battery pack comprises Information on at least the charging voltage and charging current to be required for charging the secondary battery built in the battery pack is transmitted to the charging control means of the charger via the communication means, and the charging control means of the charger is configured as described above. By causing the charging current supply means to supply the charging voltage and charging current in response to the request to the battery pack, in the battery pack, the cell voltage of the secondary battery is constant so as to be a preset end voltage. Constant current charging for supplying a charging current is performed, and when the end voltage is reached, constant voltage charging is performed to decrease the charging current so as to maintain the end voltage. In the charging system,
The battery pack is
Voltage detection means ;
And the temperature sensor,
An overcharge determination unit for determining whether or not the cell voltage detected by the voltage detection means has become an overcharge state ;
An overtemperature determination unit that determines whether or not the temperature detected by the temperature sensor is in an overtemperature state ;
In response to the determination results of the overcharge determination unit and the overtemperature determination unit, a counter that counts the number of times of overcharge and the number of times of overtemperature, respectively,
In response to the count result of the counter, when either the number of times of overcharging or the number of times of overtemperature exceeds a predetermined threshold number of times, the charge / discharge control means sends a charge voltage to the charger. A charging system comprising: setting means for lowering the requested end voltage by a predetermined voltage and resetting both the number of overcharges and the number of overtemperatures in the counter . Charge provided from the charger by providing a secondary battery, a communication means and a charge / discharge control means, wherein the charge / discharge control means transmits a charge voltage and charge current request to the charger via the communication means. Constant current charging is performed to supply a constant charging current to the secondary battery so that the cell voltage of the secondary battery becomes a preset termination voltage by the voltage and the charging current, and when the termination voltage is reached, In the battery pack in which constant voltage charging is performed to reduce the charging current so as to maintain the end voltage,
Voltage detection means ;
And the temperature sensor,
An overcharge determination unit for determining whether or not the cell voltage detected by the voltage detection means has become an overcharge state ;
An overtemperature determination unit that determines whether or not the temperature detected by the temperature sensor is in an overtemperature state ;
In response to the determination results of the overcharge determination unit and the overtemperature determination unit, a counter that counts the number of times of overcharge and the number of times of overtemperature, respectively,
In response to the count result of the counter, when either the number of times of overcharging or the number of times of overtemperature exceeds a predetermined threshold number of times, the charge / discharge control means sends a charge voltage to the charger. A battery pack comprising: setting means for reducing the requested end voltage by a predetermined voltage and resetting both the number of overcharges and the number of overtemperatures in the counter . Charge provided from the charger by providing a secondary battery, a communication means and a charge / discharge control means, wherein the charge / discharge control means transmits a charge voltage and charge current request to the charger via the communication means. Constant current charging is performed to supply a constant charging current to the secondary battery so that the cell voltage of the secondary battery becomes a preset termination voltage by the voltage and the charging current, and when the termination voltage is reached, In the battery pack in which constant voltage charging is performed to reduce the charging current so as to maintain the end voltage,
Voltage detection means ;
And the temperature sensor,
An overcharge determination unit for determining whether or not the cell voltage detected by the voltage detection means has become an overcharge state ;
An overtemperature determination unit that determines whether or not the temperature detected by the temperature sensor is in an overtemperature state ;
In response to the determination results of the overcharge determination unit and the overtemperature determination unit, a counter that counts the number of times of overcharge and the number of times of overtemperature, respectively,
In response to the count result of the counter, the voltage applied to the secondary battery is reduced when either the number of times of overcharging or the number of times of overtemperature exceeds a predetermined threshold number of times. And a voltage reduction means for resetting both the number of times of overcharging and the number of times of overtemperature in the counter . A battery pack comprising a secondary battery, communication means and charge / discharge control means, and a charger comprising charge current supply means, communication means and charge control means, wherein the charge / discharge control means of the battery pack comprises Information on at least the charging voltage and charging current to be required for charging the secondary battery built in the battery pack is transmitted to the charging control means of the charger via the communication means, and the charging control means of the charger is configured as described above. By causing the charging current supply means to supply the charging voltage and charging current in response to the request to the battery pack, in the battery pack, the charging / discharging control means stops the cell voltage of the secondary battery being preset. Constant current charging is performed to supply a constant charging current to the secondary battery so that the voltage reaches a voltage, and when the end voltage is reached, the charging current is turned off and the cell power is turned on within a predetermined period. Is a pulse that turns on the charging current when a preset charging resumption voltage lower than the end voltage is reached, and stops charging when the cell voltage does not drop to the charging resumption voltage within a predetermined period. In a charging system designed to charge,
The battery pack is
Voltage detection means ;
And the temperature sensor,
An overcharge determination unit for determining whether or not the cell voltage detected by the voltage detection means has become an overcharge state ;
An overtemperature determination unit that determines whether or not the temperature detected by the temperature sensor is in an overtemperature state ;
In response to the determination results of the overcharge determination unit and the overtemperature determination unit, a counter that counts the number of times of overcharge and the number of times of overtemperature, respectively,
In response to the count result of the counter, when either the number of times of overcharging or the number of times of overtemperature exceeds a predetermined threshold number of times, the charge / discharge control means sends a charge voltage to the charger. A setting means for reducing at least one of the requested end voltage and the charge resumption voltage by a predetermined voltage and resetting both the number of times of overcharge and the number of overtemperatures in the counter. Charging system characterized by A secondary battery and charging / discharging control means, wherein the charging / discharging control means is configured such that a cell voltage of the secondary battery becomes a preset end voltage by a charging voltage and a charging current supplied from a charger. Performing constant current charging for supplying a constant charging current to the next battery, and when the end voltage is reached, the charging current is turned off, and the cell voltage is set in advance within a predetermined period of time. In the battery pack that turns on the charging current and performs pulse charging to stop charging by determining that the cell voltage does not drop to the charging resumption voltage within a predetermined period of time and fully charged,
Voltage detection means ;
And the temperature sensor,
An overcharge determination unit for determining whether or not the cell voltage detected by the voltage detection means has become an overcharge state ;
An overtemperature determination unit that determines whether or not the temperature detected by the temperature sensor is in an overtemperature state ;
In response to the determination results of the overcharge determination unit and the overtemperature determination unit, a counter that counts the number of times of overcharge and the number of times of overtemperature, respectively,
In response to the count result of the counter, when either the number of times of overcharging or the number of times of overtemperature exceeds a predetermined threshold number, the charging resumption voltage is decreased by a predetermined voltage. And a setting means for resetting both the number of overcharges and the number of overtemperatures in the counter .   The battery pack according to claim 2, 3 or 5, wherein the secondary battery comprises a plurality of cells connected in series. Constant current charging is performed to supply a constant charging current toward a preset end voltage to the secondary battery, and when the end voltage is reached, the charge current is decreased so as to maintain the end voltage. In a charging method for performing constant voltage charging,
When the secondary battery is on purpose overcharged or over-temperature shape,-out the number of times counted respectively Teyu,
When either one of the number of times of overcharging or the number of times of overtemperature exceeds a predetermined threshold number of times , the end voltage is lowered, and the number of times of overcharging and overtemperature are reached. A charging method, wherein the count value of the number of times is reset together . In a charging method in which constant current charging is performed to supply a constant charging current toward a preset end voltage to a secondary battery, and when the end voltage is reached, pulse charging is performed so as to maintain the end voltage.
When the secondary battery is on purpose overcharged or over-temperature shape,-out the number of times counted respectively Teyu,
When either one of the number of times of overcharge or the number of times of overtemperature exceeds a predetermined threshold number of times , at least one of the charge resumption voltage or the charge voltage used for the pulse charge is lowered and the overcharge is performed. A charging method characterized by resetting both count values of the number of times of charging and the number of times of overtemperature .

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