JP2006129540A - Charger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charger performing constant current charging with an optimal voltage value depending on the magnitude of a charging current in order to suppress deterioration of a secondary battery. <P>SOLUTION: The charger performing constant current-constant voltage charging of a secondary battery 5 comprises a power supply section 14 supplying power for charging the secondary battery 5, a section 11 for measuring the voltage of the secondary battery 5, a section 16 for measuring a charging current flowing through the secondary battery 5, a mode selecting section 13 accepting a charging mode of different set current value at the time of constant current charging, and a power supply control section 12 for altering the set current value depending on a set current value in charging mode accepted at the mode selecting section 13, performing constant current charging until that set current value is reached by controlling the power supply section 14 based on a measured charging current value, and then performing constant voltage charging by controlling the power supply section 14 based on a measured battery voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a charging device that controls a charging current so that a battery voltage does not exceed the predetermined value when the battery voltage reaches a predetermined value during constant current charging of a secondary battery.

  In recent years, various secondary batteries such as a nickel cadmium battery, a nickel metal hydride battery, and a lithium ion battery have been widely used as driving power sources in portable electric devices such as electric tools, electric razors, mobile phones, and notebook personal computers. . When charging such a secondary battery, constant current charging is performed so that the current value of the current flowing through the secondary battery (charging current) becomes a constant value. If charging is continued by charging, the battery voltage is overcharged and the battery voltage becomes abnormally high, resulting in deterioration. Therefore, a lithium ion battery cannot be fully charged only by constant current charging, and constant current charging is performed until the voltage value of the secondary battery (battery voltage) reaches a predetermined value. After the voltage value reaches a predetermined value, constant voltage charging is performed in which charging is performed such that the charging current flowing in the secondary battery is gradually decreased and the voltage value of the battery voltage becomes a constant value.

A charging method for charging a secondary battery with such a constant current-constant voltage is disclosed in Patent Document 1, for example. The charging method described in Patent Document 1 performs constant current charging until the voltage value of the battery voltage in the secondary battery reaches the first set voltage value, and then performs constant voltage charge at the second set voltage value. The second set voltage value is set to be equal to or lower than the first set voltage value, and temperature compensation is performed so that the temperature at the low temperature is higher than that at the high temperature.
JP-A-9-149556

  By the way, when charging a secondary battery, in order to complete charging in a short time, the quick charge mode in which charging is performed with a charging current having a relatively large current value and the charging current having a relatively small current value even if time is required. There are a plurality of charging modes including a long-time charging mode for charging. In the background art, the value of the set voltage in constant voltage charging is common even when the charging mode is different, and particularly when charging is performed in the quick charging mode, the heat generated in the secondary battery increases, and the secondary battery As a result of the high temperature of the battery, the secondary battery may be deteriorated.

  The charging method described in Patent Document 1 described above changes the set voltage value according to the temperature of the secondary battery, and it is described that the set voltage value is changed according to the magnitude of the current value of the charging current. There is no suggestion.

  In addition, the voltage value of the battery voltage in the secondary battery measured by the charging device may vary from the voltage measuring unit depending on the arrangement position on the circuit of the voltage measuring unit that measures the voltage value and the magnitude of the current value of the charging current. A voltage drop that cannot be ignored may occur until the next battery. For this reason, an error occurs between the measured voltage value of the battery voltage and the actual battery voltage value, and as a result, there is a possibility that constant voltage charging may not be performed at the intended voltage value.

  The present invention has been made in view of the above-described circumstances, and constant current charging can be performed at an optimum voltage value according to the magnitude of the current value of the charging current in order to suppress deterioration of the secondary battery. An object of the present invention is to provide a charging device that can be used.

  In order to achieve the above-described object, the secondary battery according to one aspect of the present invention is charged with a constant current until the battery voltage of the secondary battery reaches a set voltage value. A charging device that performs constant voltage charging after the battery voltage of the battery reaches the set voltage value, a power supply unit that supplies power for charging the secondary battery, and measures the voltage of the secondary battery as the battery voltage A voltage measuring unit, a current measuring unit that measures a current value flowing through the secondary battery as a charging current, a constant current setting unit that sets a current value in the case of constant current charging as a set current value, and the constant current The set voltage value is changed according to the set current value set by the setting unit, and the power source unit is controlled based on the current value of the charging current measured by the current measuring unit. Until the set voltage value is reached Performing Kijo current charge, then it is characterized by having a power control unit that performs the constant voltage charging by controlling the power supply unit.

  In the charging device, the constant current setting unit includes a long-time charging mode in which the set current value is a first set current value and a second set current in which the set current value is greater than the first set current value. A mode selection unit that accepts a plurality of charge modes having different set current values including a fast charge mode that is a value, and the power supply control unit is configured such that the charge mode accepted by the constant current setting unit is the long-time charge mode. In some cases, the first set voltage value is set as the set voltage value, and when the charge mode received by the constant current setting unit is the rapid charge mode, the first set voltage is set as the set voltage value. A second set voltage value larger than the value is set.

  In the above-described charging device, the second set voltage value is a value obtained by adding a voltage drop generated in a current path through which the charging current flows from the voltage measuring unit to the secondary battery. .

  Furthermore, in the above-described charging devices, the power control unit further corrects the second set voltage value according to a state of the secondary battery.

  In the above-described charging device, the battery charger further includes a temperature measurement unit that measures the temperature of the secondary battery as a battery temperature, and the power supply control unit further includes a battery temperature measured in advance by the battery temperature measured by the temperature measurement unit. When the value is equal to or greater than one predetermined value, the second set voltage value is corrected to be smaller by a predetermined first correction value.

  Further, in the above-described charging device, the power supply control unit further sets the second set voltage value in advance when the battery voltage measured by the voltage measurement unit is greater than or equal to a predetermined second predetermined value. The second correction value is corrected to be smaller.

  Furthermore, in the above-described charging device, the battery charger further includes a temperature measuring unit that repeatedly measures the temperature of the secondary battery as a battery temperature, and the power supply control unit further includes a unit time based on the battery temperature measured by the temperature measuring unit. When the change in the battery temperature per hit is equal to or greater than a predetermined third predetermined value, the second set voltage value is corrected to be smaller by a predetermined third correction value.

  In the above-described charging device, the voltage measurement unit repeatedly measures the voltage of the secondary battery as the battery voltage, and the power supply control unit further includes a unit based on the battery voltage measured by the voltage measurement unit. When the change in battery voltage per time is equal to or greater than a predetermined fourth predetermined value, the second set voltage value is corrected to be decreased by a predetermined fourth correction value.

  The charging device may further include a temperature measuring unit that measures the temperature of the secondary battery as a battery temperature, and the power supply control unit may further include a battery temperature measured by the temperature measuring unit in advance. When the predetermined value is 5 or less, the second set voltage value is corrected to be smaller by a predetermined fifth correction value.

  The charging device for charging the secondary battery to be charged having such a configuration with constant current-constant voltage charging is configured such that the voltage measurement unit measures the voltage of the secondary battery as the battery voltage, and the current measurement unit passes through the secondary battery. Is measured as the charging current, and the current value when the constant current setting unit performs constant current charging is set as the set current value. Then, the power supply control unit of the charging device controls the power supply unit that supplies power for charging the secondary battery based on the current value of the charging current measured by the current measurement unit until the set voltage value is reached. After performing current charging and the voltage value of the battery voltage measured by the voltage measuring unit reaches the set voltage value, constant voltage charging is performed by controlling the power supply unit, and the setting set by the constant current setting unit The set voltage value is changed according to the current value. For this reason, constant current charging can be performed with an optimal voltage value according to the magnitude of the current value of the charging current, and deterioration of the secondary battery can be suppressed.

Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.
(Configuration of the embodiment)
FIG. 1 is a diagram illustrating a configuration of a charging device according to the embodiment. FIG. 2 is a diagram showing a graph of battery voltage and time change of charging voltage in constant current-constant voltage charging. FIG. 2A is a graph of the change in battery voltage over time, the horizontal axis is time, and the vertical axis is battery voltage. FIG. 2B is a graph of the change in charging current with time, the horizontal axis is time, and the vertical axis is charging current.

  In FIG. 1, the charging device 1 includes charging terminals Ts 1 and Ts 2, a charging-side communication terminal Tc 2, a voltage measuring unit 11, a power source control unit 12, a mode selection unit 13, a power source unit 14, and a temperature measuring unit 15. And a current measuring unit 16. The secondary battery 5 includes battery terminals Tb1, Tb2 for connection to the charging terminals Ts1, Ts2 of the charging device 1, one or a plurality of battery cells 51 connected between the battery terminals Tb1, Tb2, A temperature detection unit 52 that detects the temperature as the battery temperature, and a battery side communication terminal Tc1 that outputs a detection result detected by the temperature detection unit 52 and is connected to the charging side communication terminal Tc2 are configured. The battery cell 51 is a unit cell of a secondary battery such as a nickel cadmium battery, a nickel hydride battery, or a lithium ion battery, and the temperature detection unit 52 is an element whose resistance value changes depending on the temperature of a thermistor, for example. is there.

  The charging terminals Ts1, Ts2 are electrode terminals for outputting electric power for charging the secondary battery 5 to be charged and for connecting to the battery terminals Tb1, Tb2 of the secondary battery 5.

  The charging side communication terminal Tc2 is a signal terminal for connecting to the battery side communication terminal Tc1 that outputs the detection result detected by the temperature detection unit 52 of the secondary battery 5.

  The voltage measuring unit 11 is a circuit that is connected to the charging terminals Ts1 and Ts2, measures a voltage (charging voltage) between the charging terminals Ts1 and Ts2 as a battery voltage, and outputs the measured battery voltage to the power supply control unit 12. . The voltage measurement unit 11 includes, for example, two resistance elements connected in series that are connected between the charging terminals Ts1 and Ts2, and the charging terminals Ts1 and Ts2 that are output from the interconnection points of these two resistance elements. An analog / digital conversion circuit (hereinafter abbreviated as “A / D conversion circuit”) that converts a divided voltage with respect to the charging voltage between the analog signal to a digital signal and outputs the voltage as a battery voltage to the power supply control unit 12. It is prepared for.

  The mode selection unit 13 is an input circuit that receives one charging mode from a plurality of charging modes having different set current values including a long-time charging mode and a quick charging mode, and outputs the received charging mode to the power supply control unit 12. It is an example of the constant current setting part which sets the electric current value in the case of constant current charge as a setting electric current value. The mode selection unit 13 includes, for example, a switch such as a push button switch or a rotary switch, accepts one charging mode by switching the switch, and outputs a signal indicating the accepted charging mode to the power supply control unit 12. . The charging device 1 of the present embodiment can set two charging modes, a long-time charging mode and a quick charging mode.

  The power supply unit 14 is a DC power supply circuit that is connected to the charging terminals Ts1 and Ts2 and supplies power for charging the secondary battery 5 to the secondary battery 5 through the charging terminals Ts1 and Ts2. The power supply unit 14 includes, for example, a rectifying circuit that rectifies commercial power into direct current, a smoothing circuit that smoothes the direct current rectified by the rectifying circuit, and DC / DC that converts the direct current voltage value of the smoothing circuit into a desired voltage value. And a converter.

  The temperature measurement unit 15 is a circuit that measures the temperature (battery temperature) of the secondary battery 5 based on the detection result input from the charging side temperature terminal Tc2 and outputs the measured battery temperature to the power supply control unit 12. The temperature measurement unit 15 includes an A / D conversion circuit that A / D converts the detection result input from the charging-side temperature terminal Tc2 and outputs the detection result to the power supply control unit 12 as a battery temperature.

  The current measuring unit 16 is disposed between the power supply unit 14 and the charging terminal Ts2 and measures a current (charging current) flowing from the power supply unit 14 through the charging terminals Ts1 and Ts2 to the secondary battery, and the measured charging current is measured. Output to the power control unit 12. The current measurement unit 16 includes, for example, a resistance element and an A / D conversion circuit that A / D converts the voltage between the terminals generated by the current flowing through the resistance element and outputs the voltage as a charging current to the power supply control unit 12. Configured.

  The power supply control unit 12 includes a battery voltage measured by the voltage measurement unit 11, a charging mode received by the mode selection unit 13, a charging voltage output from the power supply unit 14 based on the charging current measured by the current measurement unit 16, and Control charging current. The power supply control unit 12 functionally includes a constant voltage control unit 21, a mode determination unit 22, and a constant current control unit 23. The power supply control unit 12 stores, for example, a control program such as a central processing unit (CPU) that performs arithmetic processing, a charging program for realizing constant current-constant voltage charging described later, data, and the like. Non-volatile storage elements such as ROM (Read Only Memory) and EEPROM (Electrically Erasable Programmable Read Only Memory), and so-called CPU working memory such as temporary storage of data such as RAM (Random Access Memory) And a volatile memory element.

  The constant current control unit 23 is a power supply unit based on the current value of the charging current measured by the current measurement unit 16 until the voltage value of the battery voltage measured by the voltage measurement unit 11 reaches the set voltage value after the start of charging. 14, constant current charging is performed by charging the secondary battery 5 with a constant charging current. That is, as shown in FIGS. 2A and 2B, the voltage value of the battery voltage V in the secondary battery 5 measured by the voltage measuring unit 11 increases as the charging time elapses. The constant current control unit 23 controls the output of the power supply unit 14 so that the current value of the charging current I measured by the current measurement unit 16 becomes a substantially constant value Ic until the time tc until the set voltage value Vc is reached. .

  The constant voltage control unit 21 controls the power supply unit 14 based on the voltage value of the battery voltage measured by the voltage measurement unit 11 after the voltage value of the battery voltage measured by the voltage measurement unit 11 reaches the set voltage value. As a result, the charging current flowing through the secondary battery 5 is gradually reduced to perform constant voltage charging in which the battery voltage is charged to a constant value. That is, as shown in FIGS. 2A and 2B, the constant voltage control unit 21 determines that the voltage value of the battery voltage V in the secondary battery 5 measured by the voltage measurement unit 11 has reached the set voltage value Vc. After the time tc, the output of the power supply unit 14 is controlled so that the voltage value of the battery voltage V in the secondary battery 5 maintains a substantially constant value at the set voltage value Vc.

  The mode determination unit 22 determines the charging mode set by the mode selection unit 13 based on the signal from the mode selection unit 13, and when the long-time charging mode is accepted as the charging mode, the first setting current value is set. In addition to setting the current value, a second set current value larger than the first set current value is set as the set current value when the quick charge mode is accepted as the charge mode. That is, the current value of the charging current (first setting current value) when performing constant current charging in the long-time charging mode is the current value of the charging current (second setting current value) when performing constant current charging in the rapid charging mode. ) Has been smaller.

  It should be noted that the set voltage value of constant current-constant voltage charging is changed according to the charging mode determined by the mode determining unit 22, that is, according to the set current value.

  FIG. 3 is a diagram showing a graph of changes over time in the battery voltage and the charging voltage in the long-time charging mode and the quick charging mode of constant current-constant voltage charging. FIG. 3A is a graph of the temporal change of the battery voltage in the long charge mode and the quick charge mode, the horizontal axis is time, and the vertical axis is the battery voltage. FIG. 3B is a graph of the temporal change of the charging current in the long-time charging mode and the quick charging mode, the horizontal axis is time, and the vertical axis is the charging current. 3 (A) and 3 (B), the temporal changes in the battery voltage and the charging current in the long-time charging mode are indicated by solid lines, and the temporal changes in the battery voltage and the charging current in the rapid charging mode are indicated by a one-dot chain line. It is shown.

  In the present embodiment, as shown in FIG. 3A, the set voltage value Vc in the long charge mode is set to the first set voltage value Vc1, and the set voltage value Vc in the quick charge mode is set to the first set voltage. The second set voltage value Vc2 that is smaller than the value Vc1 is set. That is, the power supply control unit 12 switches the set voltage value according to the charging mode determined by the mode determination unit 22 (according to the current value Ic of the charging current in constant current charging), and the constant current control unit 23 and the constant voltage The control unit 21 controls the output of the power supply unit 14 as described above to charge the secondary battery 5 by constant current-constant voltage charging. That is, the power supply control unit 12 determines that the charging mode determined by the mode determination unit 22 is the long-time charging mode (when the current value Ic of the charging current in the constant current charging is the first set current value Ic1). The secondary battery 5 is charged by constant current-constant voltage charging by controlling the output of the power supply unit 14 as described above by the constant current control unit 23 and the constant voltage control unit 21 with the 1 set voltage value Vc1. Then, when the charging mode determined by the mode determination unit 22 is the quick charging mode (when the current value Ic of the charging current in the constant current charging is the second set current value Ic2), the power supply control unit 12 The secondary battery 5 is charged by constant current-constant voltage charging by controlling the output of the power source unit 14 as described above by the constant current control unit 23 and the constant voltage control unit 21 with the set voltage value Vc2.

  Also, it should be noted that the power supply control unit 12 sets the second set voltage value Vc2 in the quick charge mode to the state of the secondary battery 5 before the start of charging or to the second during charging in order to suppress the deterioration of the secondary battery 5. Correction is made according to the state of the secondary battery 5.

Next, the operation of this embodiment will be described.
(Operation of the embodiment)
FIG. 4 is a flowchart illustrating an operation of constant current-constant voltage charging of the charging device according to the embodiment. In FIG. 4, when the charging mode is received and set from the mode selection unit 13 and charging of the secondary battery 5 is started, first, the mode determination unit 22 of the power supply control unit 12 is received by the mode selection unit 13. It is determined whether or not the charge mode is the quick charge mode (S11).

  As a result of the determination, when it is not the quick charge mode (No), the power supply control unit 12 sets the long-time charge mode as the charge mode. That is, when the power source control unit 12 determines that the long-time charging mode is accepted and set as the charging mode from the mode selection unit 13 by the mode determination unit 22, the setting voltage value Vc is set to the first setting voltage value Vc1 and set. The current value Ic is set to the first set current value Ic1 (S12). Long-time charging generally has the advantages that the battery temperature rise is low, and the cycle life of the secondary battery 5 is longer than that of rapid charging.

  Next, the power supply control unit 12 controls the power supply unit 14 on the basis of the current value of the charging current measured by the current measurement unit 16 by the constant current control unit 23, so that the power supply control unit 12 has a constant value of the first set current value Ic1. The secondary battery 5 is charged with a constant current (S13).

  Then, the power supply control unit 12 determines whether or not the voltage value of the battery voltage measured by the voltage measurement unit 11 at a predetermined sampling period has reached the first set voltage value Vc1 (S14). As a result of the determination, when the voltage value of the charging voltage has not reached the first set voltage value Vc1 (No), the process is returned to the process S13, and the power supply control unit 12 performs the first operation by the constant current control unit 23. Constant current charging is continued at a constant value of the set current value Ic1. On the other hand, if the voltage value of the charging voltage has reached the first set voltage value Vc1 as a result of the determination (Yes), the control of the power supply unit 14 is switched from the constant current control unit 23 to the constant voltage control unit 21. The power supply control unit 12 controls the power supply unit 14 on the basis of the voltage value of the battery voltage measured by the voltage measurement unit 11 by the constant voltage control unit 21 to obtain a secondary value with a constant value of the substantially first set voltage value Vc1. The battery 5 is charged at a constant voltage (S15).

  And the power supply control part 12 judges whether charge of the secondary battery 5 was completed (S16). This determination of the completion of charging is made, for example, based on the elapsed time from the start of constant voltage charging. If the charging is not completed as a result of the determination (No), the power supply control unit 12 continues the constant voltage charging with the constant value of the first set voltage value Vc1 by the constant voltage control unit 21. On the other hand, as a result of the determination, when the charging is completed (Yes), the power supply control unit 12 ends the process and completes the charging.

  On the other hand, if the result of determination in step S11 is that the quick charge mode is set (Yes), the power supply control unit 12 sets the quick charge mode as the charge mode. In other words, when the mode determination unit 22 determines that the charging mode is the quick charge mode, the power supply control unit 12 sets the set voltage value Vc to the second set voltage value Vc1 that is smaller than the first set voltage value Vc1. The constant current control unit 23 sets the set current value Ic to the second set current value Ic1 that is larger than the first set current value Ic1 (S21). In general, the quick charge is fully charged in a short time, and has an advantage that work by an electric device using the secondary battery 5 can be started at an early stage.

  Next, the power supply control unit 12 determines whether or not the battery temperature measured by the temperature measurement unit 15 is equal to or higher than a first predetermined value before the start of charging (S22).

  As a result of the determination, when the battery temperature is lower than the first predetermined value (No), the power supply control unit 12 executes a process S24 described later, and when the battery temperature is equal to or higher than the first predetermined value (Yes). The power supply control unit 12 resets the second set voltage value Vc2 to a value lower by the first correction value ΔV1 (S23), and executes the process S24. When the secondary battery 5 is at a high temperature before the start of charging, the secondary battery 5 is fixed with the charging current of the second set current value set to a relatively large value in the quick charge mode by operating in this way. Since the time during which the current is charged is shortened and heat generation of the secondary battery 5 can be suppressed, deterioration of the secondary battery 5 can be suppressed. From this viewpoint, the first predetermined value is predetermined in consideration of the temperature at which the secondary battery 5 starts to deteriorate, and is, for example, 60 [° C.] or 50 [° C.]. From this point of view, the first correction value ΔV1 is predetermined in consideration of the degree of suppressing the deterioration of the secondary battery 5 and the like, for example, 0.05 [V / cell] or 0.1 [V / cell]. ] And the like. Second, third, and fifth correction values ΔV2, ΔV3, and ΔV5, which will be described later, are also determined in advance in consideration of the degree of suppressing the deterioration of the secondary battery 5 similarly to the first correction value ΔV1.

  In process S24, the power supply control unit 12 determines whether or not the battery voltage measured by the voltage measurement unit 11 is a second predetermined value in order to determine whether or not the secondary battery 5 is in a fully charged state before starting charging. It is determined whether or not it is greater than or equal to the value. The state of charge close to full charge is, for example, a case where the state of charge is 95% or 97% of full charge. The second predetermined value is a value for determining whether or not the secondary battery 5 is nearly fully charged. For example, the second predetermined value is preset to 0.05 [V / cell], 0.1 [V / cell], or the like. Is done.

  As a result of the determination, when the battery voltage is less than the second predetermined value (No), the power supply control unit 12 executes a process S26 described later, and when the battery voltage is equal to or higher than the second predetermined value (Yes). The power supply control unit 12 determines that the secondary battery 5 is in a charged state close to full charge, resets the second set voltage value Vc2 to a value lower by the second correction value ΔV2 (S25), and performs processing S26 is executed. The second correction value ΔV2 is, for example, 0.05 [V / cell] or 0.1 [V / cell]. In the case where the secondary battery 5 is in a charged state close to full charge before the start of charging, the operation is performed in this manner, so that the second set current value is set to a relatively large value in the quick charge mode. Since the time during which the secondary battery 5 is charged with a constant current is shortened and overcharge of the secondary battery 5 can be avoided, deterioration of the secondary battery 5 can be suppressed.

  In process S26, the power supply control unit 12 controls the power supply unit 14 on the basis of the current value of the charging current measured by the current measurement unit 16 by the constant current control unit 23, thereby substantially maintaining a constant value of the second set current value Ic2. Then, the secondary battery 5 is charged with a constant current.

  Next, the power supply control unit 12 determines whether or not the secondary battery 5 is in a fully charged state based on the battery temperature change during charging, or the internal resistance of the secondary battery 5 is In order to determine whether or not the battery is in a high state, the battery temperature change ΔT / Δt per unit time based on the battery temperature measured by the temperature measurement unit 15 at a predetermined sampling period is equal to or greater than a third predetermined value. It is determined whether or not there is (S27).

  As a result of the determination, when the battery temperature change ΔT / Δt per unit time is less than the third predetermined value (No), the power supply control unit 12 executes a process S28 described later, When the battery temperature change ΔT / Δt is equal to or greater than the third predetermined value (Yes), the power supply control unit 12 resets the second set voltage value Vc2 to a value lower by the third correction value ΔV3. (S29) Processing S30 described later is executed. The third correction value ΔV3 is, for example, 0.05 [V / cell] or 0.1 [V / cell]. When the secondary battery 5 is in a fully charged state during charging, or when the internal resistance of the secondary battery 5 is high during charging, a comparison is made in the quick charge mode by operating in this way. Since the time for which the secondary battery 5 is charged at a constant current with the charging current of the second set current value set to a large value is shortened and heat generation of the secondary battery 5 can be suppressed, the secondary battery 5 Can be prevented.

  In process S28, the power supply control unit 12 determines whether or not the secondary battery 5 is in a state of charge close to full charge based on a change in battery voltage during charging, in a predetermined sampling cycle. Whether or not the change ΔV / Δt of the battery voltage per unit time is equal to or greater than a fourth predetermined value is determined based on the battery voltage measured by the above.

  As a result of the determination, if the change ΔV / Δt in the battery voltage per unit time is less than the fourth predetermined value (No), the power supply control unit 12 executes the process S30, and the battery voltage per unit time When the change ΔV / Δt of the current value is equal to or greater than the fourth predetermined value (Yes), the power supply control unit 12 resets the second set voltage value Vc2 to a value lower by the third correction value ΔV3 (S29). ), Process S30 is executed. When the secondary battery 5 is in a charged state close to full charge during charging, the secondary battery 5 is charged with the second set current value which is set to a relatively large value in the quick charge mode by operating in this way. Since the time during which the battery 5 is charged with a constant current is shortened and heat generation of the secondary battery 5 can be suppressed, the deterioration of the secondary battery 5 can be suppressed.

  In step S30, the power supply control unit 12 corrects the voltage value of the battery voltage measured by the voltage measurement unit 11 at a predetermined sampling period with the second set voltage value Vc2 (correction values ΔV1, ΔV2, and ΔV3). If it is, the corrected second set voltage value Vc2 is included.) Is determined. As a result of the determination, when the voltage value of the charging voltage does not reach the second set voltage value Vc2 (No), the process is returned to the process S26, and the power supply control unit 12 is controlled by the constant current control unit 23. 2 Constant current charging is continued at a constant value of the set current value Ic2. On the other hand, if the voltage value of the charging voltage has reached the second set voltage value Vc2 as a result of the determination (Yes), the control of the power supply unit 14 is switched from the constant current control unit 23 to the constant voltage control unit 21. Then, the power supply control unit 12 controls the power supply unit 14 based on the voltage value of the battery voltage measured by the voltage measurement unit 11 by the constant voltage control unit 21 to obtain a substantially second set voltage value Vc2 (correction value ΔV1). , ΔV2 and ΔV3, the corrected second set voltage value Vc2 is included). The secondary battery 5 is charged at a constant voltage with a constant value (S31).

  And the power supply control part 12 judges whether charge of the secondary battery 5 was completed (S32). This determination of the completion of charging is made, for example, based on the elapsed time from the start of constant voltage charging. If the charging is not completed as a result of the determination (No), the power supply control unit 12 continues the constant voltage charging with the constant value of the second set voltage value Vc2 by the constant voltage control unit 21. On the other hand, as a result of the determination, when the charging is completed (Yes), the power supply control unit 12 ends the process and completes the charging.

  FIG. 5 is a diagram showing a graph of temporal changes in battery voltage and battery temperature in constant current-constant voltage charging. FIG. 5A shows a graph of battery voltage temporal change similar to FIG. 3A, with the horizontal axis representing time and the vertical axis representing battery voltage. FIG. 5B shows a graph of changes in battery temperature over time, the horizontal axis is time, and the vertical axis is battery temperature. In FIG. 5, a solid line indicates a temporal change in battery temperature when the set voltage value is the second set voltage value in the quick charge mode, and a broken line indicates the set voltage value is the first set voltage value in the quick charge mode. The time change of the battery temperature in a certain case is shown.

  When the charging mode is the rapid charging mode by operating as described above with reference to FIG. 4, the setting voltage value is set to the second setting voltage value Vc2 instead of the first setting voltage value Vc1, and the charging is performed. The device 1 charges the secondary battery 5 with a constant current-constant voltage. For this reason, when the secondary battery 5 is rapidly charged by the charging device 1, for example, as shown in FIG. 5, the battery temperature in the rapid charging is changed from the temporal change in the battery temperature indicated by the broken line to the temporal change in the battery temperature indicated by the solid line. The temperature is reduced and the deterioration of the secondary battery 5 is suppressed.

  Here, if the second set voltage value Vc2 is made smaller than the first set voltage value Vc1, the charge time becomes longer in order to fully charge, or the charge time is set to the charge time in the quick charge mode of the background art. Therefore, it is preferable to determine in consideration of the balance among the cycle life, the charging time, and the capacity at the time of completion of charging.

  FIG. 6 shows the battery voltage and charge in the constant current-constant voltage charge long-time charge mode and the quick charge mode when the voltage drop caused by the electrical resistance in the current path from the voltage measuring unit 11 to the secondary battery 5 is considered. It is a figure which shows the graph of the time change of a voltage. FIG. 6A is a graph of the temporal change of the battery voltage in the long charge mode and the quick charge mode, the horizontal axis is time, and the vertical axis is the battery voltage. FIG. 6B is a graph of the temporal change of the charging current in the long-time charging mode and the rapid charging mode, the horizontal axis is time, and the vertical axis is the charging current. 6 (A) and 6 (B), the temporal changes in the battery voltage and the charging current in the long-time charging mode are indicated by solid lines, and the temporal changes in the battery voltage and the charging current in the rapid charging mode are indicated by a one-dot chain line. It is shown.

  Here, the voltage value of the battery voltage in the secondary battery 5 measured by the voltage measuring unit 11 is two from the voltage measuring unit 1 depending on the arrangement position on the circuit of the voltage measuring unit 11 and the current value of the charging current. There may be a voltage drop that cannot be ignored until the secondary battery 5. In particular, as shown in FIG. 3B, the current value of the charging current in the quick charge mode is a relatively large second set current value Ic2, and thus a voltage drop that cannot be ignored may occur. Therefore, only the error that occurs between the voltage value of the battery voltage measured by the voltage measurement unit 11 and the voltage value of the actual battery voltage, that is, the electric resistance in the current path from the voltage measurement unit 11 to the secondary battery 5 occurs. It is preferable to correct the second set voltage Vc2 by adding the voltage drop ΔV5 to the second set voltage value Vc2 by the voltage drop ΔV5. As a result, as shown in FIG. 6, the second set voltage value Vc2 that is the set voltage value in the quick charge mode may exceed the first set voltage value Vc1 that is the set voltage value in the long-time charge mode.

  In this way, by correcting the second set voltage value Vc2 by the voltage drop ΔV5 caused by the electrical resistance in the current path from the voltage measurement unit 11 to the secondary battery 5, the charging device 1 can have the desired voltage value. Constant current-constant voltage charging is possible.

  In the above-described embodiment, it is determined whether or not the secondary battery 5 is at a high temperature before starting charging in the process S24, and if the secondary battery is at a high temperature, the second set voltage value Vc2 is decreased. However, it is determined whether or not the secondary battery 5 is at a low temperature by determining whether or not the battery temperature of the secondary battery 5 is equal to or lower than a fifth predetermined value. When the temperature is low, the second set voltage value Vc2 may be corrected to be lowered by the fifth correction value. When the secondary battery 5 is at a low temperature, it is difficult to carry out a chemical reaction associated with charging, so that it is not preferable to charge by supplying a relatively large charging current. For this reason, in the case where the secondary battery 5 is at a low temperature before the start of charging, the secondary battery is charged with the charging current of the second set current value set to a relatively large value in the quick charge mode. The time during which 5 is charged with a constant current is shortened, and charging with a relatively large value of charging current at low temperatures can be suppressed. The fifth predetermined value is predetermined in consideration of the degree of chemical reaction of the secondary battery 5 and is, for example, 5 [° C.] or 0 [° C.]. The fifth correction value ΔV5 is, for example, 0.05 [V / cell] or 0.1 [V / cell].

  In the above-described embodiment, the state of the secondary battery 5 is determined based on whether or not the battery voltage change ΔV / Δt per unit time is equal to or greater than the fourth predetermined value in the process S28. You may comprise so that the state of the secondary battery 5 may be judged.

  Such a charging device 1 can be applied to various secondary batteries widely used as a driving power source in a battery-powered device. As an example, a lithium ion battery used as a driving power source for an electric tool is described below. Explained.

  FIG. 7 is an external configuration diagram illustrating a main part of a rechargeable power tool set to which the charging device according to the embodiment is applied. FIG. 8 is a diagram illustrating a state in which the battery pack is mounted on the mounting portion of the electric tool main body. FIG. 9 is a diagram illustrating a state in which the battery pack is mounted in the mounting hole of the charging device.

  In FIG. 7, a rechargeable electric tool set 100 includes an electric tool main body 110 that constitutes a rechargeable drill driver, a battery pack 120 that is attached to the electric power tool main body 110, and a charging device 130 that charges the battery pack 120. It has.

  The power tool main body 110 is formed inside the gripping portion of the casing 111 and is provided inside the casing 111 with a mounting portion 112 to which the battery pack 120 is detachably mounted, and current is supplied from the battery pack 120. Motor 113 that is driven by this, and a trigger switch 114 that is provided on the gripping portion of the casing 111 and that controls on / off of the supply of current to the motor 113, and provided at the tip of the casing 111, with drill teeth, etc. And a rotating part 115 to be attached. A pair of electrode terminals 116 connected to the motor 113 are attached to the bottom of the mounting portion 112.

  The battery pack 120 includes a main body portion 123 in which a lithium ion battery 122 and the like are housed in a housing 121, and an electrode portion 124 that protrudes to one surface side of the main body portion 123 and is attached to the attachment portion 112 of the electric power tool main body 110. I have. The electrode unit 124 is detected by a pair of battery terminals 125 connected to the electrode of the lithium ion battery 122 and a temperature detection unit 127 (not shown) that detects the temperature of the lithium ion battery 122 as the battery temperature on the opposite surface of the tip part. A battery side communication terminal 126 for outputting the detection result is provided. When the pair of battery terminals 125 are mounted on the mounting portion 112 of the electric power tool main body 110, the pair of terminal electrodes 116 of the mounting portion 112 are pressed against each other. When the battery-side communication terminal 126 is attached to the attachment hole 132 of the charging device 130, the charge-side communication terminal 134 of the attachment hole 132 is press-contacted. FIG. 8 shows a state in which the battery pack 120 is attached to the attachment portion 112 of the electric power tool main body 110.

  The charging device 130 includes a circuit block 131 that constitutes a power supply unit, a power supply control unit, and the like, and a mounting hole 132 in which the electrode unit 124 of the battery pack 120 is detachably mounted on the upper surface side. . A pair of charging terminals 133 (only one of them is shown) is provided at an opposing position inside the mounting hole 132, and when the electrode part 124 of the battery pack 120 is mounted, the mounting hole 132 is formed in the pair of battery electrodes 125. A pair of charging terminals 133 are pressed against each other. Further, a charging side communication terminal 134 (not shown) is provided inside the mounting hole 132, and when the electrode part 124 of the battery pack 120 is mounted, the charging side of the mounting hole 132 is connected to the battery side communication terminal 126. The communication terminal 134 is press-contacted. A push button switch 135 for inputting the charging mode is disposed on the upper surface side. FIG. 9 shows a state where the battery pack 120 is mounted in the mounting hole 132 of the charging device 130.

  Here, the charging device 130 corresponds to the charging device 1 shown in FIG. 1, and the circuit block 131 corresponds to the voltage measurement unit 11, the power supply control unit 12, the power supply unit 14, the temperature measurement unit 15, and the current measurement unit 16 shown in FIG. 1. Correspondingly, the charging terminal 133 corresponds to the charging terminals Ts1 and Ts2 shown in FIG. 1, the charging side signal terminal 135 corresponds to the charging side signal terminal Tc2 shown in FIG. 1, and the push button switch 135 is shown in FIG. This corresponds to the mode selection unit 13. Further, the battery pack 120 corresponds to the secondary battery 5 shown in FIG. 1, the lithium ion battery 122 corresponds to the battery cell 51 shown in FIG. 1, and the battery terminal 125 corresponds to the battery terminals Tb1 and Tb2 shown in FIG. The battery side communication terminal 126 corresponds to the battery side communication terminal Tc1 shown in FIG.

  As described above, when the battery pack 110 is mounted on the charging device 120 and the both are connected in a circuit, the charging device 120 charges the battery pack 110 with constant current-constant voltage as described above. For this reason, deterioration of the lithium ion battery 122 of the battery pack 110 can be suppressed as compared with the background art.

It is a figure which shows the structure of the charging device in embodiment. It is a figure which shows the graph of the time change of the battery voltage and charging voltage in constant current-constant voltage charge. It is a figure which shows the graph of the time change of the battery voltage and charging voltage in the long-time charge mode and rapid charge mode of constant current-constant voltage charge. It is a flowchart which shows the operation | movement of the constant current-constant voltage charge of the charging device in embodiment. It is a figure which shows the graph of the time change of the battery voltage and battery temperature in constant current-constant voltage charge. When the voltage drop caused by the electrical resistance in the current path from the voltage measuring unit 11 to the secondary battery 5 is taken into consideration, the battery voltage and the charging voltage in the long-time charging mode and the rapid charging mode of constant current-constant voltage charging are temporally determined. It is a figure which shows the graph of a change. It is an external appearance block diagram which shows the principal part of the rechargeable electric tool set to which the charging device which concerns on embodiment is applied. It is a figure which shows the state by which the battery pack was mounted | worn with the mounting part of the electric tool main body. It is a figure which shows the state by which the battery pack was mounted | worn in the mounting hole part of the charging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charging apparatus 2 Secondary battery 11 Voltage measurement part 12 Power supply control part 13 Mode selection part 14 Power supply part 15 Temperature measurement part 16 Current measurement part 21 Constant voltage control part 22 Mode determination part 23 Constant current control part 51 Battery cell 52 Temperature detection Part

Claims (9)

The secondary battery to be charged is charged with constant current until the battery voltage of the secondary battery reaches a set voltage value, and is charged with constant voltage after the battery voltage of the secondary battery reaches the set voltage value. In a charging device that performs
A power supply for supplying power for charging the secondary battery;
A voltage measuring unit that measures the voltage of the secondary battery as the battery voltage;
A current measuring unit that measures a current value flowing through the secondary battery as a charging current;
A constant current setting unit for setting a current value in the case of the constant current charging as a set current value;
By changing the set voltage value according to the set current value set by the constant current setting unit, and by controlling the power supply unit based on the current value of the charging current measured by the current measurement unit A power supply control unit that performs the constant current charging until the set voltage value after the change is reached, and then performs the constant voltage charging by controlling the power supply unit. The constant current setting unit includes a long-time charge mode in which the set current value is a first set current value and a quick charge mode in which the set current value is a second set current value larger than the first set current value. A mode selection unit that accepts a plurality of charge modes having different set current values,
The power supply controller sets the first set voltage value as the set voltage value when the charge mode accepted by the constant current setting unit is the long-time charge mode, and accepts it by the constant current setting unit. 2. The charging device according to claim 1, wherein when the charging mode is the rapid charging mode, a second set voltage value larger than the first set voltage value is set as the set voltage value. The charging device according to claim 2, wherein the second set voltage value is a value obtained by adding a voltage drop generated in a current path through which the charging current flows from the voltage measurement unit to the secondary battery. . 4. The charging device according to claim 2, wherein the power control unit further corrects the second set voltage value according to a state of the secondary battery. 5. A temperature measuring unit that measures the temperature of the secondary battery as a battery temperature;
The power control unit further corrects the second set voltage value by a predetermined first correction value when the battery temperature measured by the temperature measurement unit is equal to or higher than a predetermined first predetermined value. The charging device according to claim 4, wherein: The power supply control unit further corrects the second set voltage value by a predetermined second correction value when the battery voltage measured by the voltage measurement unit is equal to or higher than a second predetermined value set in advance. The charging device according to claim 4, wherein: A temperature measuring unit that repeatedly measures the temperature of the secondary battery as a battery temperature;
The power supply control unit further sets the second set voltage value when the change in the battery temperature per unit time based on the battery temperature measured by the temperature measurement unit is equal to or greater than a predetermined third predetermined value. The charging device according to claim 4, wherein the charging device is corrected to be smaller by a predetermined third correction value. The voltage measuring unit repeatedly measures the voltage of the secondary battery as the battery voltage,
The power supply control unit further sets the second set voltage value when the change in the battery voltage per unit time based on the battery voltage measured by the voltage measurement unit is equal to or greater than a predetermined fourth predetermined value. The charging device according to claim 4, wherein the correction is made to be reduced by a predetermined fourth correction value. A temperature measuring unit that measures the temperature of the secondary battery as a battery temperature;
The power supply controller further corrects the second set voltage value by a predetermined fifth correction value when the battery temperature measured by the temperature measurement unit is equal to or lower than a predetermined fifth predetermined value. The charging device according to claim 4, wherein:

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