JP5887531B2 - Charger - Google Patents

Description

  The present invention relates to a charger for charging a secondary battery.

  Conventionally, a secondary battery has been used as a power source for various portable devices. Since the secondary battery has a reduced discharge capacity as the number of repeated charge / discharge cycles increases, there is a limit to the number of times it can be repeatedly used. For this reason, some chargers that charge the secondary battery determine the life of the secondary battery when charging the secondary battery.

  As this type of charger, a battery voltage detection circuit that detects a battery voltage of a battery pack including a secondary battery, and a battery voltage gradient that calculates a battery voltage gradient from the detected battery voltage and a battery voltage a predetermined time ago 2. Description of the Related Art A charging device having an arithmetic means is known (for example, see Patent Document 1).

  When the battery pack voltage before starting charging is equal to or lower than a predetermined voltage value and the battery voltage gradient within a predetermined time after starting charging is equal to or higher than a first predetermined value, Is determined to be a lifetime. Moreover, the charging device is provided with LED, and displays the lifetime deterioration condition of a battery pack.

  Thereby, the charging device can determine the lifetime of the secondary battery, and can make the user easily recognize the deterioration state of the secondary battery.

  In addition, as a battery deterioration measuring device for measuring deterioration of a battery cell that is a secondary battery, a voltage measuring unit that measures the voltage of the battery cell, a current measuring unit that measures a charging current of the battery cell, and a deterioration rate of the battery cell There is also known one provided with a control unit for judging the above (for example, see Patent Document 2).

  In the battery deterioration measuring apparatus of Patent Document 2, when the charging current supplied during constant current charging to the battery cell is the first charging current value, the first cell voltage is calculated from the voltage value measured by the voltage measuring unit. Get. The battery deterioration measuring device obtains the second cell voltage from the voltage value measured by the voltage measuring unit when the charging current changes to the second charging current value lower than the first charging current value. In the battery deterioration measuring apparatus, the control unit calculates the internal resistance of the battery cell based on the first cell voltage and the second cell voltage, and determines the deterioration rate of the battery cell.

  Thereby, the battery deterioration measuring device of Patent Document 2 is able to accurately determine the deterioration of the secondary battery and charge the secondary battery.

JP 2007-24541 A JP 2008-123961 A

  By the way, there are various types of secondary batteries depending on the type and variation of the secondary battery, such as those having a high internal resistance from the initial stage where the number of times of charging is low and those having a low internal resistance. In addition, secondary batteries tend to have greatly different voltages of secondary batteries before charging due to the remaining capacity of the secondary battery to be charged.

  However, in the charging device described in Patent Document 1, since the voltage before the start of charging is used for determining the life, there is a possibility of erroneous determination depending on the type of secondary battery and the remaining capacity of the secondary battery. May increase. In the battery deterioration measuring apparatus of Patent Document 2, it is necessary to accurately measure the charging current and voltage of the secondary battery, and there is a risk that measurement errors are likely to occur.

  The present invention has been made in view of the above reasons, and it is possible to more accurately determine the deterioration of the secondary battery regardless of the type of the secondary battery and the remaining capacity of the secondary battery before the start of charging. Is to provide a simple charger.

The charger of the present invention includes an output circuit unit that outputs a charging current to a secondary battery whose internal resistance increases as the number of times of charging is increased, a voltage detection unit that detects the voltage of the secondary battery, and the charging with a constant current. A charger having a control unit for controlling the output circuit unit so as to perform constant current charging for supplying current and constant voltage charging for supplying the charging current at a constant voltage after the constant current charging, wherein the control unit includes: during the constant current charging, a first voltage that detect the above voltage detecting unit, and a second voltage which the voltage detecting unit with the first voltage after detection detects, the first from the detection of the first voltage The gradient of the voltage change between the first voltage and the second voltage is calculated based on the time until the detection of two voltages, and the secondary battery deteriorates when the gradient is equal to or less than a predetermined value. has been carried out and to have a different determine, the constant current charging, constant of the charging current It is performed in a plurality of periods in which the flow value is decreased stepwise, and at least a first period in which charging of the secondary battery is started, a second period immediately before starting charging of the constant voltage charging, and the first A third constant different from the first constant current value output during the first period and the second constant current value output during the second period between the output period and the second period. A third period for outputting a current value, wherein the control unit divides the third period into a plurality of regions, calculates the gradient of each of the plurality of regions, and uses the plurality of gradients to perform the determination. and it said to Rukoto a.

In this charger, Rukoto to have a notification section for notifying the result of determination above SL outside is preferred.

A charger different from the present invention includes an output circuit unit that outputs a charging current to a secondary battery, a voltage detection unit that detects a voltage of the secondary battery, and a constant current charging that causes the charging current to flow at a constant current. And a control unit that controls the output circuit unit so as to perform constant voltage charging that causes the charging current to flow at a constant voltage after the constant current charging, wherein the control unit is configured to perform the constant current charging during the constant current charging. The first voltage detected by the voltage detection unit, the second voltage detected by the voltage detection unit after detecting the first voltage, and the time from the detection of the first voltage to the detection of the second voltage Based on the above, the gradient of the voltage change between the first voltage and the second voltage at the time is calculated, and it is determined that the secondary battery has deteriorated when the gradient is equal to or less than a predetermined value. , storage elements in the battery pack having an upper Symbol secondary battery is provided with, the system The unit stores the number of times of charging the secondary battery and the gradient of the secondary battery at the number of times of charging in the storage element, and stores the gradient at the initial stage where the number of times of charging is equal to or less than a predetermined number of times and the than the initial stage by comparing the slope of the high stage of charging times, it characterized that you eliminate variations in the slope of the initial stage of the secondary battery for each of the battery pack.

  The charger of the present invention can more accurately determine the deterioration of the secondary battery regardless of the type of the secondary battery and the remaining capacity of the secondary battery before the start of charging.

It is a block diagram which shows the battery pack connected to the charger of Embodiment 1, and a charger. It is explanatory drawing explaining the charging current characteristic of the secondary battery charged with the charger same as the above. It is explanatory drawing explaining the battery voltage characteristic of the secondary battery charged with the charger same as the above. It is explanatory drawing explaining the electrical property of the secondary battery detected with the charger same as the above. It is explanatory drawing explaining the charging current characteristic of the secondary battery charged with the charger of Embodiment 2. FIG. It is explanatory drawing explaining the battery voltage characteristic of the secondary battery charged with the charger same as the above. It is explanatory drawing explaining the electrical property of the secondary battery detected with the charger same as the above. It is explanatory drawing explaining the charging current characteristic of the secondary battery charged with the charger of Embodiment 3. FIG. It is explanatory drawing explaining the battery voltage characteristic of the secondary battery charged with the charger same as the above.

(Embodiment 1)
Based on FIG. 1 thru | or FIG. 4, the battery pack 20 connected to the charger 10 of this embodiment and the charger 10 is demonstrated. In addition, in each figure, the same number is attached | subjected with respect to the same component, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 1, the charger 10 of the present embodiment charges a secondary battery 21 using an external power source AC such as a commercial power source. The secondary battery 21 is a case of the charger 10 (FIG. (Not shown) is built in the battery pack 20 that can be detachably disposed. As the secondary battery 21, a battery in which two unit cells E1, E2 are electrically connected in series is used.

  The charger 10 of this embodiment includes an output circuit unit 3 that outputs a charging current to the secondary battery 21 and a voltage detection unit 2 that detects the voltage of the secondary battery 21. The charger 10 also includes a control unit 1 that controls the output circuit unit 3 so as to perform constant current charging in which a charging current is supplied with a constant current and constant voltage charging in which a charging current is supplied with a constant voltage after constant current charging. ing. During the constant current charging, the control unit 1 detects the first voltage detected by the voltage detection unit 2, the second voltage detected by the voltage detection unit 2 after detecting the first voltage, and the second voltage from the time of detection of the first voltage. Based on the time until the voltage is detected, the gradient of the voltage change between the first voltage and the second voltage at the time is calculated. The control unit 1 determines that the secondary battery 21 is deteriorated when the calculated gradient of the voltage change is equal to or less than a predetermined value. The charger 10 of this embodiment has a notification unit 6 that notifies the determined result to the outside.

  More specifically, as shown in FIG. 2, the charger 10 of the present embodiment flows a charging current to the secondary battery 21 with a constant current from time t <b> 11 when charging starts. The charger 10 switches from constant current charging to constant voltage charging by the control unit 1 controlling the output circuit unit 3 based on a signal from a constant voltage control element 26 of the battery pack 20 described later. This is performed at time t16 (see FIG. 3). That is, the charger 10 performs constant current charging from time t11 to a predetermined time t16. Further, the charger 10 performs constant voltage charging in which the charging current is supplied to the secondary battery 21 at a constant voltage from the time t16 after the constant current charging until the time t17. In the charger 10, the charging current gradually decreases as the charging of the secondary battery 21 proceeds during constant voltage charging. The charger 10 stops charging the secondary battery 21 at time t17, assuming that the secondary battery 21 is fully charged by a signal from the constant voltage control element 26 provided in the battery pack 20. Let In other words, the charger 10 of the present embodiment charges the secondary battery 21 by constant current charging and constant voltage charging switched from constant current charging after constant current charging. Thereby, the charger 10 suppresses the overcharge of the secondary battery 21 that is likely to occur when charging is performed only by constant current charging, and compared with the battery that performs charging only by constant voltage charging. The time required for charging can be shortened.

  By the way, in the secondary battery 21 typified by a lithium ion secondary battery (hereinafter also referred to as a lithium secondary battery) or the like, if the secondary battery 21 is charged a number of times, the internal resistance increases. Electric characteristics of charge and discharge tend to deteriorate. Therefore, the secondary battery 21 is different in the electrical characteristics of the secondary battery 21 in the initial stage where the number of times of charging is small and the electrical characteristics of the degraded secondary battery 21 in the stage where the number of times of charging is large. For example, as shown in FIG. 4, the secondary battery 21 has an electrical characteristic of the secondary battery 21 during constant current charging from the electrical characteristic of the secondary battery 21 in the initial stage (refer to the one-dot chain line in FIG. 4). The electrical characteristics of the deteriorated secondary battery 21 change (see the solid line in FIG. 4). The secondary battery 21 in the initial stage exhibits electrical characteristics in which the charging voltage of the secondary battery 21 becomes the voltage Va at time t13 and the voltage Vb at time t15 during constant current charging. That is, the secondary battery 21 in the initial stage shows the characteristics of the gradient of the voltage change between the voltage Va and the voltage Vb in the time from the time t13 when the voltage Va is detected to the time t15 when the voltage Vb is detected. On the other hand, in the deteriorated secondary battery 21, during constant current charging, the voltage Va is at time t12 and the voltage Vb is at time t14. The deteriorated secondary battery 21 shows the characteristics of the gradient of the voltage change between the voltage Va and the voltage Vb in the time from the time t12 when the voltage Va is detected to the time t14 when the voltage Vb is detected. Therefore, the gradient of the deteriorated secondary battery 21 tends to be gentler with respect to time than the gradient of the secondary battery 21 in the initial stage (see FIG. 4).

  The charger 10 of the present embodiment previously sets the voltage Va as a predetermined first voltage, and measures the time t12 at the time of detection when the voltage detector 2 detects the voltage Va. Similarly, the charger 10 of the present embodiment sets the voltage Vb as a predetermined second voltage in advance, and measures the time t14 at the time of detection when the voltage detector 2 detects the voltage Vb. Then, the control unit 1 calculates the gradient of the voltage change between the voltage Va and the voltage Vb in the time (t14-t12) from the time when the voltage Va is detected until the time when the voltage Vb is detected. In addition, the charger 10 of this embodiment is not restricted to what the control part 1 is calculating the gradient of a voltage change based on the preset voltage. Therefore, the charger 10 of the present embodiment may measure the charging voltage of the secondary battery 21 for each preset time and calculate the gradient of the voltage change between the preset times.

  In the charger 10 of the present embodiment, the control unit 1 determines that the secondary battery 21 has deteriorated when the gradient of the voltage change during constant current charging is equal to or less than a predetermined value set in advance. The charger 10 may set the predetermined first voltage and the predetermined second voltage for calculating the gradient of the voltage change as appropriate according to a desired standard for determining the deterioration of the secondary battery 21. . Since the charger 10 determines the deterioration of the secondary battery 21 based on the gradient of voltage change during constant current charging, the charger 10 does not depend on the type of the secondary battery 21 or the remaining capacity of the secondary battery 21 before the start of charging. The deterioration of the secondary battery 21 can be determined. In other words, the charger 10 of this embodiment functions as a battery deterioration determination device that determines the deterioration of the secondary battery 21 by using constant current charging of the secondary battery 21. Note that the charger 10 may calculate a plurality of gradients of the voltage change during constant current charging from time t11 to time t16. The charger 10 can also increase the accuracy of determining deterioration in the secondary battery 21 by using an average value of each of a plurality of gradients.

  Hereinafter, the structure of the charger 10 of this embodiment is demonstrated in detail.

  When the battery pack 20 is attached to the case of the charger 10, the charger 10 electrically connects the charger 10 side and the battery pack 20 side, converts power from the external power supply AC, and supplies power. The secondary battery 21 can be charged. The charger 10 includes a rectifier circuit unit 4 that can be electrically connected to an external power supply AC. Although not shown, the rectifier circuit unit 4 includes, for example, a diode bridge circuit, and is connected to the diode bridge circuit via an external power supply AC and a fuse. The rectifier circuit unit 4 can be configured to connect a smoothing capacitor between the output terminals of the diode bridge circuit and smooth the DC voltage rectified by the diode bridge circuit with the smoothing capacitor. In the charger 10, an output circuit unit 3 that outputs a charging current to the secondary battery 21 is electrically connected to an output terminal of the rectifier circuit unit 4. Moreover, the charger 10 has connected the output terminal of the output circuit part 3 with the primary side of the 1st insulation transformer 7 for secondary battery charge. In the charger 10, the secondary side of the first insulating transformer 7 is connected to the pair of terminals 13 and 13 separately. The charger 10 is configured so that the terminals 13 and 13 of the charger 10 and the terminals 23 and 23 electrically connected to the secondary battery 21 built in the battery pack 20 can be electrically connected. .

  In the charger 10, the terminal 13 of the charger 10 and the terminal 23 of the battery pack 20 are directly and mechanically connected. However, the present invention is not limited to this. The charger 10 may be configured such that the charger 10 side and the battery pack 20 side are electrically connected mechanically without contact using an insulating transformer (not shown). That is, the charger 10 may be configured to be capable of non-contact charging.

  The charger 10 rectifies the alternating current supplied from the external power source AC by the rectifier circuit unit 4, then transforms it to a predetermined voltage via the output circuit unit 3 and the first insulation transformer 7, and converts the battery pack 20 from the terminal 13. Output to the side. Thereby, the charger 10 can supply a charging current to the secondary battery 21 of the battery pack 20 as a DC constant pressure power source.

  The output circuit unit 3 functions as an output adjustment unit that adjusts the on / off of power supply to the first insulation transformer 7 and the amount of current flowing to the first insulation transformer 7. The output circuit unit 3 is connected to the control unit 1 via a photocoupler 9. The control unit 1 is electrically connected to the voltage detection unit 2 provided on the secondary side of the first insulation transformer 7.

  The control unit 1 can be configured by, for example, a microcomputer provided with a CPU (Central Processing Unit) that executes predetermined arithmetic processing. The control unit 1 includes a time measuring unit that measures time so that the gradient of the voltage change of the secondary battery 21 can be calculated. In addition, the control unit 1 includes a memory unit that stores a predetermined first voltage and a predetermined second voltage that are used for determining deterioration of the secondary battery 21. The memory unit can store the time measured by the time measuring unit detected by the voltage detection unit 2. Further, the control unit 1 includes a ROM (Read Only Memory) which is a nonvolatile semiconductor element in which a predetermined control program is recorded as a storage device. The control unit 1 includes an AD converter that converts a voltage signal detected by the voltage detection unit 2 into a digital value. The control unit 1 can control the charging operation to the secondary battery 21 by executing a control program stored in the ROM and outputting a control signal to the output circuit unit 3 via the photocoupler 9.

  The voltage detection part 2 is a circuit which detects the voltage between the terminals 13 and 13 to which the secondary battery 21 is electrically connected, for example, and can be configured using a resistor. The voltage detection unit 2 outputs the voltage generated by the voltage drop of the resistor to the control unit 1 as the voltage of the secondary battery 21.

  The output circuit unit 3 includes a switching element made of, for example, a MOS transistor, and the switching element is on / off controlled by a PWM signal serving as a control signal from the control unit 1. That is, the switching frequency and on-time of the switching element are controlled based on the PWM signal. In the charger 10, the control unit 1 outputs a control signal based on the detection result of the voltage detection unit 2, and the switching element of the output circuit unit 3 is driven in response to the PWM signal serving as the control signal, and the battery pack 20 is driven. A desired charging current is output.

  In addition, a control unit power supply unit 5 is electrically connected to the output terminal of the rectifier circuit unit 4 in the rectifier circuit unit 4 described above. The control unit power supply unit 5 receives an alternating current from the external power supply AC rectified by the rectification circuit unit 4. The control unit power supply unit 5 adjusts the current and voltage supplied to the control unit 1 so as to function as a power source for driving the control unit 1 and the like. The control unit power supply unit 5 has an output terminal electrically connected to the primary side of the control unit second insulating transformer 8. Connected to the secondary side of the second insulating transformer 8 is a peripheral circuit unit 11 that serves as a cooling fan (not shown) for cooling the charger 10 and a circuit block for controlling the driving of the cooling fan. The peripheral circuit unit 11 is electrically connected to the control unit 1 so that a circuit block that controls driving of the cooling fan can be controlled. A voltage conversion circuit unit 12 is connected to the output side of the second insulation transformer 8 on the secondary side of the second insulation transformer 8. The voltage conversion circuit unit 12 is electrically connected to the control unit 1 and provided to stably output power to the control unit 1. The voltage conversion circuit unit 12 is, for example, a series regulator that configures a constant voltage, and can be configured using a three-terminal regulator or the like.

  That is, power is supplied to the control unit 1 from the control unit power supply unit 5 electrically connected to the output terminal of the rectifier circuit unit 4 via the second insulating transformer 8 and the voltage conversion circuit unit 12. Further, on the secondary side of the second insulation transformer 8, there is a notification unit 6 that is connected to the control unit 1 and notifies the outside of the result determined by the control unit 1.

  In addition, the alerting | reporting part 6 can be comprised provided with displays, such as a light emitting diode and an organic EL element, a speaker, a buzzer, etc., for example. In addition, when the alerting | reporting part 6 equips the inside of the alerting | reporting part 6, the limiting resistor which restrict | limits the electric current which flows into a light emitting diode is suitably incorporated. In the notification unit 6, the notification operation of the notification unit 6 is controlled by the control unit 1. The notification unit 6 can notify the outside of the result of determining that the secondary battery 21 is deteriorated by a signal from the control unit 1.

  Hereinafter, the battery pack 20 connected to the charger 10 of the present embodiment will be described in more detail.

  As shown in FIG. 1, the battery pack 20 to be charged by the charger 10 according to the present embodiment stores a secondary battery 21 in which two elementary electrons E1 and E2 are electrically connected in series. . Note that the secondary battery 21 is not limited to one in which two unit cells E1 and E2 are electrically connected in series. The secondary battery 21 may be one in which two unit cells E1 and E2 are electrically connected in parallel, or may be one unit cell. Further, the secondary battery 21 may be a battery in which three or more unit cells are appropriately electrically connected in series, parallel, or series-parallel. As the secondary battery 21 charged by the charger 10 of the present embodiment, for example, a nickel hydride secondary battery or a lithium secondary battery can be used.

  Although the usage application of the secondary battery 21 charged with the charger 10 is not specifically limited, For example, what is attached to an electric tool as a power supply of an electric tool (not shown) is mentioned. When the secondary battery 21 is mounted as a power source of the electric tool, the battery pack 20 in which the secondary battery 21 is housed in a case (not shown) that matches the shape of the electric tool may be used.

  The battery pack 20 is provided with a storage element 27 that can be rewritten from the outside. The storage element 27 can store the number of times of charging the secondary battery 21 and the gradient of voltage change corresponding to the number of times of charging. The storage element 27 is stored by the control unit 1 in association with the number of times of charging the secondary battery 21 and the gradient of the voltage change of the secondary battery 21 at the number of times of charging. As a result, the control unit 1 compares the slope of the voltage change at the initial stage where the number of times of charging is equal to or less than the predetermined number of times with the slope of the voltage change at the stage where the number of times of charging is larger than the initial stage. The variation in the gradient of the voltage change in the initial stage of the battery 21 can be eliminated. For example, the charger 10 reduces the difference between a predetermined reference value and the slope of the voltage change in the initial stage so that the variation in the slope of the voltage change in the initial stage of the secondary battery 21 for each battery pack 20 becomes small. The correction factor can be multiplied by the calculated gradient of voltage change. In addition, the charger 10 has, for example, a reference value larger than a predetermined reference value and a voltage change in the initial stage so as to reduce variation in the gradient of the voltage change in the initial stage of the secondary battery 21 for each battery pack 20. The difference from the gradient may be subtracted from the calculated gradient of voltage change. Similarly, for example, the charger 10 has a reference value and an initial stage voltage smaller than a predetermined reference value so as to reduce the variation in the gradient of the voltage change in the initial stage of the secondary battery 21 for each battery pack 20. The difference from the change gradient may be added from the calculated voltage change gradient. Further, the charger 10 appropriately corrects the value of a predetermined value for determining the deterioration of the secondary battery 21 so that the variation in the gradient of the voltage change in the initial stage of the secondary battery 21 for each battery pack 20 becomes small. May be. Thereby, the charger 10 of the present embodiment can determine the deterioration of the secondary battery 21 more accurately. Note that the memory element 27 may be configured by a nonvolatile semiconductor element such as an EEPROM (Electrically Erasable and Programmable Read Only Memory).

  In addition, the battery pack 20 includes a constant voltage control element 26 for maintaining the voltage of the secondary battery 21 constant when the secondary battery 21 is charged at a constant voltage. The constant voltage control element 26 can be configured by a control IC, for example. The charger 10 of the present embodiment includes a battery pack 20 side terminal 24 electrically connected to the constant voltage control element 26 and a charger electrically connected to the control unit 1 when the secondary battery 21 is charged. A terminal 14 on the 10 side is connected. The constant voltage control element 26 also determines whether or not the end-of-charge voltage has been reached on the battery pack 20 side so that the secondary battery 21 is not overcharged. When the battery voltage of the secondary battery 21 reaches the end-of-charge voltage, the constant voltage control element 26 is controlled from the terminal 24 of the battery pack 20 so as to stop the charging of the secondary battery 21 from the charger 10 side. A signal is output to 1.

  Next, operation | movement of the charger 10 of this embodiment is demonstrated.

  The charger 10 of the present embodiment starts charging when the terminal 23 of the battery pack 20 connected to the secondary battery 21 is electrically connected to the terminal 13 of the charger 10. In the charger 10, first, the control unit 1 controls the output circuit unit 3 to perform constant current charging in which a charging current is supplied to the secondary battery 21 with a constant current. The charger 10 measures the voltage applied to the secondary battery 21 by the voltage detection unit 2 during constant current charging. The control unit 1 determines whether the voltage detected by the voltage detection unit 2 matches the predetermined first voltage Va stored in advance in the memory unit of the control unit 1. When the control unit 1 determines that the voltage detected by the voltage detection unit 2 matches the predetermined first voltage Va, the elapsed time from the time t11 when the constant current charging is started by the timing unit built in the control unit 1 A certain time t12 is stored in the memory unit of the control unit 1 (see FIG. 4). Next, the charger 10 determines whether or not the voltage to be detected matches the predetermined second voltage Vb stored in advance in the memory unit of the control unit 1 during constant current charging. When it is determined that the detected voltage matches the predetermined second voltage Vb, the control unit 1 controls the time t14 that is an elapsed time from the time t11 when the constant current charging is started by the time measuring unit of the control unit 1. The data is stored in the memory unit of unit 1.

  Next, based on the control program, the control unit 1 changes the voltage of the secondary battery 21 (Vb−Va) and the time until the voltage of the secondary battery 21 changes from the voltage Va to the voltage Vb (t14−t12). And the gradient of voltage change ((Vb−Va) / (t14−t12)) is calculated and stored in the memory unit of the control unit 1. The charger 10 transmits the value of the gradient of voltage change from the control unit 1 to the storage element 27 of the battery pack 20 via the terminals 15 and 25. The control unit 1 causes the storage element 27 to appropriately store the number of times of charging and the value of the gradient of the voltage change corresponding to the number of times of charging. The control unit 1 may store the value of the number of times of charging, which is increased by one time to the value of the number of times of previous charging stored in the memory element 27, for example, every time charging is performed.

  Subsequently, the control unit 1 of the charger 10 compares the predetermined value stored in advance in the memory unit of the control unit 1 with the gradient of the voltage change calculated by the control unit 1. The charger 10 of this embodiment determines that the secondary battery 21 has deteriorated when the calculated gradient of the voltage change is equal to or less than a predetermined value stored in advance. When the control unit 1 determines that the secondary battery 21 is deteriorated, the control unit 1 controls the notification unit 6 to notify the determined result to the outside.

  When it is determined that the secondary battery 21 has deteriorated, the charger 10 may control the control unit 1 to stop charging the secondary battery 21, or may charge the secondary battery 21. You may continue. When the charger 10 continues to charge the secondary battery 21, the constant voltage charging is performed so that the charging current is supplied to the secondary battery 21 at a constant voltage from the time t 16 after the constant current charging until the time t 17. I do. In the charger 10, when charging of the secondary battery 21 proceeds, the control unit 1 controls the output circuit unit 3 to reduce the charging current. The charger 10 stops the charging of the secondary battery 21 according to the signal from the constant voltage control element 26 provided in the battery pack 20, assuming that the secondary battery 21 is fully charged.

  Thereby, the charger 10 of the present embodiment can more accurately determine the deterioration of the secondary battery 21 regardless of the type of the secondary battery 21 and the remaining capacity of the secondary battery 21 before the start of charging. Become. Note that the secondary battery 21 determined to be deteriorated also has a smaller battery capacity. Therefore, the charger 10 of this embodiment is provided with the capacity | capacitance of the battery in which the secondary battery 21 operates an electric tool for a predetermined time, for example, when the alerting | reporting part 6 alert | reports deterioration of the secondary battery 21. It becomes possible to provide the user or the like. That is, since the charger 10 includes the notification unit 6 in the charger 10, it is possible to notify the user or the like of the deterioration of the secondary battery 21, and the user uses the battery pack 20 that is charged. It is possible to grasp the amount of work with a tool.

(Embodiment 2)
The charger 10 of this embodiment reduces the constant current value shown in FIGS. 5 and 6 stepwise instead of using the gradient of the voltage change in the constant current charging of the first embodiment shown in FIGS. 2 and 3. The difference is that the deterioration of the secondary battery 21 is determined using the gradient of the voltage change in a specific period in the constant current charging. In addition, the battery pack 20 connected to the charger 10 and the charger 10 of the present embodiment has the same circuit configuration as the charger 10 and the battery pack 20 of the first embodiment shown in FIG. The charger 10 of the present embodiment is different from the charger 10 of the first embodiment in the control program of the control unit 1 that calculates the gradient of voltage change. Here, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  In the charger 10 of the present embodiment, the constant current charging to the secondary battery 21 is performed in a plurality of periods in which the constant current value of the charging current is decreased stepwise. The constant current charging has a first period in which charging of the secondary battery 21 is started and a second period immediately before the start of charging of constant voltage charging. The constant current charging is performed between the first period and the second period, and the first constant current value output from the output circuit unit 3 in the first period and the second constant current value output in the second period. And a third period in which a third constant current value different from that is output. The controller 1 of the charger 10 according to the present embodiment calculates the gradient of voltage change in the third period, which is a specific period in constant current charging.

  In the constant current charging, the charger 10 according to the present embodiment reduces the constant current value of the charging current stepwise as the charging of the secondary battery 21 proceeds, thereby preventing secondary charging. It is possible to further reduce the deterioration of the battery 21. In addition, the charger 10 of the present embodiment can more accurately determine the deterioration of the secondary battery 21.

  Hereinafter, operation | movement of the charger 10 of this embodiment is demonstrated in detail.

  In the charger 10 of the present embodiment, the control unit 1 controls the output circuit unit 3 and, as shown in FIG. 5, the period from time t21 to time t23, which is a period immediately after the start of charging, is transferred to the secondary battery 21. As the first period in which charging is started, constant current charging is performed in which a charging current is supplied at a constant current. Further, the charger 10 decreases the current value of the charging current after the time t23, and performs constant current charging in a period between the time t23 and the time t25. Further, the charger 10 further reduces the current value of the charging current after the elapse of time t25, and performs constant current charging in the period from the elapse of time t25 to the time t26 when switching to constant voltage charging. As shown in FIG. 6, the charger 10 performs constant voltage charging in which a charging current is supplied to the secondary battery 21 at a constant voltage during a period from the elapse of time t26 to time t27. Here, the constant current charging period from the time t25 to the time t26 is the second period immediately before the start of constant voltage charging. For this reason, the constant current charging period between the time t23 and the time t25 is different from the first constant current value I21 output in the first period and the second constant current value I22 output in the second period. The third period during which the third constant current value I23 is output.

  That is, in the charger 10, the control unit 1 controls the output circuit unit 3 to perform constant current charging while gradually reducing the charging current from time t21 to time t26, and then switches to constant voltage charging. ing. The charger 10 stops charging the secondary battery 21 at time t27, assuming that the secondary battery 21 is fully charged by a signal from the constant voltage control element 26 provided in the battery pack 20. I am letting.

  The charger 10 of the present embodiment uses the gradient of the voltage change in the third period to determine the deterioration of the secondary battery 21 in constant current charging in which the constant current value of the charging current is decreased stepwise. The charger 10 measures the voltage of the secondary battery 21 by the voltage detection unit 2 during constant current charging. Here, the control unit 1 measures the time from the time t21 when the constant current charging is started by the time measuring unit built in the control unit 1. Further, the control unit 1 maintains constant current charging at the first constant current value I21 until the voltage detected by the voltage detection unit 2 matches the preset voltage Vc of the secondary battery 21. When the voltage detected by the voltage detection unit 2 matches the voltage Vc, the control unit 1 performs constant current charging by reducing the constant current value of the charging current from the first constant current value I21 to the third constant current value I23. . Here, in the secondary battery 21, the voltage of the secondary battery 21 decreases from the voltage Vc to the voltage Vc1 as the constant current value of the charging current is lowered. The charger 10 detects the voltage value of the reduced voltage Vc1 of the secondary battery 21 and stores it in the memory unit of the control unit 1. Further, the control unit 1 stores in the memory unit of the control unit 1 the time t23 when the constant current value of the charging current is lowered from the first constant current value I21 to the third constant current value I23 by the time measuring unit built in the control unit 1. Let

  Next, the charger 10 performs constant-current charging at the third constant-current value I23 until the voltage detected by the voltage detection unit 2 matches the voltage Vd preset in the control unit 1 during constant-current charging. To maintain. When the voltage detected by the voltage detection unit 2 matches the voltage Vd, the control unit 1 performs constant current charging by decreasing the constant current value of the charging current from the third constant current value I23 to the second constant current value I22. . In the secondary battery 21, the battery voltage of the secondary battery 21 decreases from the voltage Vd to the voltage Vd1 as the current value of constant current charging is decreased. The control unit 1 causes the memory unit of the control unit 1 to store the time t25 when the constant current value of the charging current is lowered from the third constant current value I23 to the second constant current value I22 by the time measuring unit. Thereafter, the control unit 1 switches from constant current charging to constant voltage charging at a time t26 by a signal from the constant voltage control element 26 provided in the battery pack 20. In addition, the charger 10 charges the secondary battery 21 at time t27 on the basis of the signal from the constant voltage control element 26 provided in the battery pack 20 that the control unit 1 has fully charged the secondary battery 21. Stop. The charger 10 takes into consideration the voltage drop of the secondary battery 21 when the constant current value is reduced, the charging end voltage at which the battery pack 20 is fully charged, etc. The voltage Vd having a higher voltage than that of the voltage Vd is stored.

  Based on the control program, the control unit 1 determines the voltage from the voltage change (Vd−Vc1) of the secondary battery 21 and the time (t24−t22) until the voltage of the secondary battery 21 changes from the voltage Vc1 to the voltage Vd. The gradient of change ((Vd−Vc1) / (t24−t22)) is calculated and stored in the memory unit of the control unit 1.

  Here, as shown in FIG. 7, in the secondary battery 21, the electrical characteristics of the secondary battery 21 at the time of constant current charging are the electrical characteristics of the secondary battery 21 in the initial stage (see the one-dot chain line in FIG. 7). The electrical characteristics of the deteriorated secondary battery 21 change (see the solid line in FIG. 7). During the constant current charging, the secondary battery 21 in the initial stage has a voltage Vc1 at which the battery voltage of the secondary battery 21 is reduced from the voltage Vc at time t23, and an electrical characteristic of a voltage change gradient that becomes the voltage Vd at time t25. Show. On the other hand, in the deteriorated secondary battery 21, during constant current charging due to an increase in internal resistance, the voltage Vc2 drops from the voltage Vc at time t22 and becomes voltage Vd at time t24.

  In the charger 10 of the present embodiment, the control unit 1 determines that the secondary battery 21 has deteriorated when the gradient of the voltage change in the third period during constant current charging is equal to or less than a predetermined value set in advance.

  Here, in the charger 10, the remaining capacity of the secondary battery 21 in the first period in which charging of the secondary battery 21 is started among a plurality of periods of constant current charging in which the constant current value decreases stepwise. There is a concern that erroneous determination may occur in determining deterioration of the secondary battery 21, for example, due to fluctuations in battery voltage.

In the charger 10, the voltage of the secondary battery 21 is detected by the voltage detection unit 2, and charging of the secondary battery 21 is controlled. In the battery pack 20, a signal for making the voltage of the secondary battery 21 constant by the constant voltage control element 26 is output to the control unit 1, and signals for starting constant voltage charging and ending constant voltage charging are also output. Here, the charger 10 detects the voltage of the secondary battery 21 on the charger 10 side, and the battery pack 20 detects the voltage of the secondary battery 21 on the battery pack 20 side. Therefore, the charger 10, if a shift in the voltage detection value of the charger 10 and the battery pack 20 side due manufacturing variation of the constant voltage control element 26 has occurred, the a charge immediately before the start of the constant-voltage charge There is a possibility that the two periods become longer or shorter. That is, the charger 10 charges the constant voltage charge when there is a difference between the voltage detection value from the constant voltage control element 26 of the battery pack 20 and the voltage detection value at the voltage detection unit 2 of the charger 10. In the second period immediately before the start, there is a risk of erroneous determination in determining deterioration of the secondary battery 21.

  The charger 10 of the present embodiment performs charging divided into a plurality of periods in which the constant current value of the charging current is reduced stepwise in constant current charging in order to suppress deterioration of the secondary battery 21 due to overcharging or the like. ing. Here, the charger 10 includes the first constant current value and the first constant in the first period between the first period in which charging of the secondary battery 21 is started and the second period immediately before the start of charging of constant voltage charging. A third period for outputting a third constant current value different from the second constant current value for two periods is set. The charger 10 calculates the gradient of the voltage change and determines the deterioration of the secondary battery 21 in the third period. Thereby, the charger 10 of the present embodiment can more accurately determine the deterioration of the secondary battery 21 regardless of the type of the secondary battery 21 and the remaining capacity of the secondary battery 21 before the start of charging. Become.

(Embodiment 3)
The charger 10 of the present embodiment divides the third period into a plurality of areas instead of using the voltage change gradient in the third period of the second embodiment shown in FIG. 5 and FIG. The difference is that the deterioration of the secondary battery 21 is discriminated using the gradient. In addition, the battery pack 20 connected to the charger 10 and the charger 10 of the present embodiment has the same circuit configuration as the charger 10 and the battery pack 20 of the first embodiment shown in FIG. The charger 10 of the present embodiment is different from the charger 10 of the first and second embodiments in the control program of the control unit 1 that calculates the gradient of the voltage change. Here, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  In the charger 10 of the present embodiment, the control unit 1 divides the third period into a plurality of regions, calculates the gradient of voltage change in each of the plurality of regions, and uses the plurality of gradients to degrade the secondary battery 21. To determine.

  More specifically, as shown in FIGS. 8 and 9, the charger 10 of the present embodiment starts charging the secondary battery 21 between time t31 and time t32, which is a period immediately after the start of charging. As the first period, constant current charging is performed in which a charging current is supplied at a constant current. In addition, the charger 10 decreases the current value of the charging current after the time t32 has elapsed, and performs constant current charging in a period between the time t32 and the time t33. Similarly, the charger 10 further reduces the current value of the charging current after the elapse of time t33, and performs constant current charging in a period between the elapse of time t33 and the time t34. Furthermore, the charger 10 further decreases the current value of the charging current after the time t34, and performs constant current charging in a period between the time t34 and the time t35. The charger 10 controls the output circuit unit 3 based on the signal from the constant voltage control element 26 of the battery pack 20, thereby switching from constant current charging to constant voltage charging at time t <b> 36. To do. In other words, the charger 10 performs constant current charging from the time t35 to the time t36. Here, the constant current charging period from the elapse of time t34 to the time t35 is the second period immediately before the start of constant voltage charging. For this reason, the constant current charging period between time t32 and time t34 is different from the first constant current value I31 output in the first period and the second constant current value I32 output in the second period. The third period in which the constant current value I33 and the constant current value I34 that are the third constant current value are output.

  That is, the charger 10 controls the output circuit unit 3 to perform constant current charging while gradually reducing the charging current from time t31 to time t35, and then switches to constant voltage charging. Yes. The charger 10 stops charging the secondary battery 21 at time t36 by the control unit 1 assuming that the secondary battery 21 is fully charged by a signal from the constant voltage control element 26 provided in the battery pack 20. I am letting.

  The charger 10 of the present embodiment uses the gradient of the voltage change in the third period for determining the deterioration of the secondary battery 21 in constant current charging in which the constant current value of the charging current is decreased stepwise. The charger 10 measures the voltage of the secondary battery 21 by the voltage detection unit 2 during constant current charging. Here, the control unit 1 measures the time from the time t31 when the constant current charging is started by the timing unit built in the control unit 1. Further, the control unit 1 maintains constant current charging at the first constant current value I31 until the voltage detected by the voltage detection unit 2 matches the preset voltage Ve of the secondary battery 21. When the voltage detected by the voltage detection unit 2 matches the voltage Ve, the control unit 1 changes the constant current value of the charging current from the first constant current value I31 to the constant current value I33 that is one of the third constant current values. Decrease and perform constant current charging. Here, in the secondary battery 21, as the constant current value of the charging current is lowered, the voltage of the secondary battery 21 is reduced from the voltage Ve to the voltage Ve1. The charger 10 detects the voltage value of the voltage Ve <b> 1 at which the voltage of the secondary battery 21 is reduced, and stores it in the memory unit of the control unit 1. Further, the control unit 1 causes the memory unit of the control unit 1 to store the time t32 when the constant current value of the charging current is lowered from the first constant current value I31 to the constant current value I33 by the time measuring unit built in the control unit 1.

  Subsequently, the control unit 1 maintains constant current charging at the constant current value I33 until the voltage detected by the voltage detection unit 2 matches the preset voltage Vf of the secondary battery 21. When the voltage detected by the voltage detection unit 2 matches the voltage Vf, the control unit 1 decreases the constant current value of the charging current from the constant current value I33 to the constant current value I34 that is also one of the third constant current values. To perform constant current charging. Here, in the secondary battery 21, the voltage of the secondary battery 21 decreases from the voltage Vf to the voltage Vf1 as the constant current value of the charging current is lowered. The charger 10 detects the voltage Vf <b> 1 at which the voltage of the secondary battery 21 is reduced and stores it in the memory unit of the control unit 1. Further, the control unit 1 causes the memory unit of the control unit 1 to store the time t33 when the constant current value of the charging current is lowered from the constant current value I33 to the constant current value I34 by the time measuring unit built in the control unit 1.

  Similarly, the charger 10 maintains constant current charging at the constant current value I34 during constant current charging until the voltage detected by the voltage detection unit 2 matches the voltage Vg preset in the control unit 1. To do. When the voltage detected by the voltage detection unit 2 matches the voltage Vg, the control unit 1 performs constant current charging by reducing the current value of the charging current from the constant current value I34 to the second constant current value I32. In addition, the control unit 1 causes the memory unit of the control unit 1 to store the time t34 when the constant current value of the charging current is decreased from the constant current value I34 to the second constant current value I32 by the time measuring unit. Thereafter, the control unit 1 switches from constant current charging to constant voltage charging at a time t35 by a signal from the constant voltage control element 26 provided in the battery pack 20. In addition, the charger 10 charges the secondary battery 21 at time t36 on the basis of the signal from the constant voltage control element 26 provided in the battery pack 20 that the control unit 1 has fully charged the secondary battery 21. Stop.

  Based on the control program, the control unit 1 determines the voltage from the voltage change (Vf−Ve1) of the secondary battery 21 and the time (t33−t32) until the voltage of the secondary battery 21 changes from the voltage Ve1 to the voltage Vf. The gradient of change ((Vf−Ve1) / (t33−t32)) is calculated and stored in the memory unit of the control unit 1. Similarly, the control unit 1 changes the voltage (Vg−Vf1) of the secondary battery 21 and the time until the voltage of the secondary battery 21 changes from the voltage Vf1 to the voltage Vg based on the control program (t34−t33). And the gradient of the voltage change ((Vf−Ve1) / (t34−t33)) is calculated and stored in the memory unit of the control unit 1.

  The control unit 1 of the charger 10 according to the present embodiment, for example, includes a voltage change gradient (Vf−Ve1) shown between the triangle marks in FIG. 9 and a voltage change gradient (Vg) shown between the circle marks in FIG. 9. The ratio to -Vf1) is calculated.

  In the charger 10 of the present embodiment, the control unit 1 determines that the secondary battery 21 has deteriorated when the ratio of the gradient of the voltage change in the third period during constant current charging is equal to or less than a predetermined value set in advance. To do.

  In the charger 10 of the present embodiment, the control unit 1 calculates the gradient of the voltage change in each of the plurality of regions in the third period, and determines the deterioration of the secondary battery 21 using the ratio of the plurality of gradients. . The charger 10 of the present embodiment discriminates the deterioration of the secondary battery 21 using a plurality of gradient ratios, thereby reducing the gradient variation and increasing the accuracy of the deterioration determination in the secondary battery 21. It becomes possible.

  Note that the battery pack 20 connected to the charger 10 of the present embodiment stores the gradient of the voltage change with the factory shipment of the battery pack 20 as the first time. Moreover, the charger 10 of this embodiment memorize | stores the charging frequency of the secondary battery 21 as shown in Table 1, and the gradient of the voltage change corresponding to the charging frequency in the memory | storage element 27 of the battery pack 20 connected. I will let you.

記憶素子２７は、二次電池２１の充電回数や充電回数に対応する電圧変化の勾配を記憶させるだけでなく、二次電池２１の満充電時の電池電圧、過放電を防止するための放電終止電圧や過充電を防止するための充電終止電圧などを記憶させておいてもよい。

The storage element 27 not only stores the number of times the secondary battery 21 is charged and the gradient of the voltage change corresponding to the number of times of charging, but also the battery voltage when the secondary battery 21 is fully charged, and discharge termination for preventing overdischarge. You may memorize | store a voltage, the charge end voltage for preventing overcharge, etc.

  The charger 10 according to the present embodiment includes a battery pack 20 side terminal 25 electrically connected to the storage element 27 and a charger 10 side electrically connected to the control unit 1 when the secondary battery 21 is charged. Terminal 15 is connected.

  In the charger 10, the control unit 1 determines the initial stage based on the number of times of charging stored in the storage element 27 provided on the battery pack 20 side including the secondary battery 21 and the gradient of voltage change associated with the number of times of charging. The deterioration of the secondary battery 21 can be determined based on the change in the gradient of the voltage change from. The battery charger 10 of the present embodiment has a storage element 27 for each battery pack 20 and can detect a voltage change gradient associated with the number of times the secondary battery 21 is charged. 21 and, conversely, variations among the secondary batteries 21 such as the secondary battery 21 having a low internal resistance can be canceled out.

  In other words, the control unit 1 of the charger 10 of the present embodiment compares the slope of the initial stage in which the number of times of charging is equal to or less than the predetermined number and the slope of the stage in which the number of times of charging is higher than the initial stage, stored in the storage element 27. Thus, the deterioration of the secondary battery 21 is determined. Therefore, the charger 10 according to the present embodiment can eliminate the variation in the gradient at the initial stage of the secondary battery 21 for each battery pack 20. The charger 10 according to the present embodiment can further improve the accuracy of determining deterioration in the secondary battery 21.

DESCRIPTION OF SYMBOLS 1 Control part 2 Voltage detection part 3 Output circuit part 6 Notification part 10 Charger 21 Secondary battery 27 Memory element

Claims (2)

An output circuit unit that outputs a charging current to a secondary battery whose internal resistance increases when the number of times of charging is repeated, a voltage detection unit that detects a voltage of the secondary battery, and a constant current charging that causes the charging current to flow at a constant current; A charger having a control unit that controls the output circuit unit so as to perform constant-voltage charging that causes the charging current to flow at a constant voltage after the constant-current charging;
Wherein, during said constant-current charging, a first voltage that detect said voltage detector, a second voltage by the voltage detecting unit said first voltage after detection detects the detection of the first voltage And calculating a gradient of a voltage change between the first voltage and the second voltage at the time based on a time from when the second voltage is detected to when the second voltage is detected. When the battery has deteriorated and made a different determine,
The constant current charging is performed in a plurality of periods in which the constant current value of the charging current is decreased stepwise, at least a first period in which charging of the secondary battery is started, and charging of the constant voltage charging The first constant current value output from the output circuit unit in the first period and the second period are output between the second period immediately before the start, the first period, and the second period. A third period for outputting a third constant current value different from the second constant current value,
The control unit is divided into the third period a plurality of regions, as well as calculating the slope of each region of the plurality of the charger, wherein to Rukoto the determination using a plurality of the gradient. The charger according to claim 1, further comprising a notification unit that notifies the determined result to the outside.

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