JP5502282B2 - How to charge the battery pack - Google Patents

Description

  The present invention relates to a method for charging an assembled battery in which a plurality of batteries are connected in series, and more particularly to a charging method that is optimal for charging an assembled battery in which a plurality of lithium ion secondary batteries are connected in series.

  When an assembled battery in which a plurality of batteries are connected in series is charged, each battery is charged with the same current. For this reason, if the electrical characteristics of all the batteries are exactly the same, the voltage of each battery to be charged becomes the same voltage. However, in the actual charging of the assembled battery, the voltage of each battery is not the same. This is because the electrical characteristics of all the battery cells cannot be completely matched. The voltage difference of each battery increases as it is used. This is because the deterioration of each battery becomes unbalanced. This drawback can be solved by charging each battery connected in series independently, but this charging circuit becomes extremely complicated, and the assembled battery has an external connection point for each battery. In reality, it is not adopted at all. Also, an assembled battery having this structure has not been put into practical use. For this reason, the assembled battery is charged by connecting the positive and negative output terminals to the charger. Therefore, a voltage difference is generated due to battery imbalance.

When charging, if the voltage of a specific battery becomes higher than the maximum set voltage, the battery is significantly deteriorated and the assembled battery cannot be safely charged. For this reason, a method has been proposed in which the assembled battery is charged while detecting the voltage of each battery, and charging is stopped when the voltage of any battery exceeds a maximum set voltage. (See Patent Document 1)
JP 2001-126792 A

  In the above charging method, charging can be performed while controlling the voltage of each battery below the maximum set voltage. However, since this charging method stops charging when the voltage of any one of the batteries rises to the maximum set voltage, there is a drawback that the assembled battery cannot be charged to a sufficient capacity when the battery is unbalanced. This is because charging is stopped even though a battery whose voltage has not increased to the maximum set voltage is in a state where it can be further charged.

  The present invention has been developed for the purpose of solving this drawback. An important object of the present invention is to provide a charging method capable of increasing the charging capacity of an assembled battery while controlling the voltage of each battery to be equal to or lower than the maximum set voltage.

The battery pack charging method of the present invention has the following configuration in order to achieve the above-described object.
In the assembled battery charging method, an assembled battery in which a plurality of batteries are connected in series is charged at a constant voltage and a constant current while detecting the voltage of each battery. This charging method starts charging at a first set current specified from the detected parameter , detects the voltage of each battery cell at a predetermined sampling period, and sets any battery cell voltage in advance. When the maximum set voltage is exceeded, the charging power for charging the battery pack is reduced and constant voltage / constant current charging is performed. During charging, the second set current is identified from the detected battery temperature, and when the voltage of the high voltage battery cell is equal to or lower than the maximum set voltage, the reduced set current is compared with the second set current, and the voltage drops. When the set current and the second set current are not equal, charging is continued with the lower set current.
Further, the initial setting value of the charging current value at the start of charging is determined from two parameters of temperature and remaining capacity or temperature and voltage.

The battery pack charging method of the present invention detects the voltage of each battery cell at a predetermined sampling period, and sets the battery pack to charge when any battery cell voltage exceeds a preset maximum set voltage. Reduce current and charge at constant voltage and constant current.

Charging method of the battery pack of the present invention, the battery cell voltage had Zureka exceeds the maximum set voltage, thereby decreasing the set current for charging the assembled battery in a specific ratio.

Charging method of the battery pack of the present invention, have the battery cell voltage of Zureka exceeds the maximum set voltage, with reducing the set current for charging the battery pack, the rate of lowering the set current, voltage of each battery cell Is specified from the difference voltage between the maximum voltage set per cell and the voltage obtained by multiplying the number of cells connected in series, and if the difference voltage is large, the ratio at which the set current is reduced is increased.

Charging method of the battery pack of the present invention, have the battery cell voltage of Zureka exceeds the maximum set voltage, with reducing the set current for charging the battery pack, the rate of lowering the set current, exceeds the maximum set voltage If the internal resistance of the battery cell is large, the ratio of reducing the set current is increased.

Further, in the battery pack charging method of the present invention, the maximum set voltage is changed by the battery temperature.

Further, the charging method of the battery pack of the present invention, changes the setting current temperature of the battery. Furthermore, in the assembled battery charging method of the present invention, the set current to be reduced is set to a multistage set current.
In the battery pack charging method of the present invention, the set current value that is decreased when the maximum set voltage is exceeded and the initial set value of the charge current value at the start of charging are set from the same value.
The battery pack charging method of the present invention is a battery pack charging method in which a battery pack in which a plurality of batteries are connected in series is charged at a constant voltage and a constant current while detecting the voltage of each battery. The voltage of each battery cell is detected at the sampling period of, and if any battery cell voltage exceeds the preset maximum voltage, the output from the operational amplifier that compares the reference voltage with the battery cell voltage The charging power for charging the assembled battery is reduced.
In addition, charging to charge the assembled battery with the output of the OR circuit to which the output of the operational amplifier to which the positive battery cell voltage is input and the output of the operational amplifier to which the negative battery cell voltage is input is input This is a method of charging an assembled battery that reduces power.

  The battery pack charging method of the present invention is characterized in that the charge capacity of the battery pack can be increased while controlling the voltage of each battery to be equal to or lower than the maximum set voltage. The charging method of the present invention detects the voltage of each battery cell at a predetermined sampling period, and when any battery cell voltage exceeds the maximum set voltage, the set voltage for charging the assembled battery at a constant voltage is lowered. Alternatively, the set current for constant current charging is reduced, and then the assembled battery is charged at a constant voltage / constant current.

  FIG. 4 is a graph showing the voltage and charging current of the battery cell of the assembled battery charged by the charging method according to the embodiment of the present invention. As shown in this figure, when the voltage of the high voltage battery cell exceeds the maximum set voltage, the charging power for charging the assembled battery is controlled to be small at this timing (t1). Since the charging power is controlled to be small, the charging voltage of the assembled battery decreases and the charging current also decreases. For this reason, the voltage of a high voltage battery cell falls by the reduction of charging current, and becomes lower than the maximum setting voltage. Since the assembled battery is further charged in this state, the high voltage battery cell is charged to gradually increase the voltage. When the voltage of the high voltage battery cell again exceeds the maximum set voltage, the charging power is further reduced at this timing (t2). This charging state is repeated at the timing (t3, t4), and the charging is finished when the charging current of the assembled battery decreases to the minimum current. The assembled battery charged in this state always exceeds the maximum set voltage to prevent the voltage of the high-voltage battery cell from exceeding the maximum set voltage. The battery can be charged to a sufficient capacity. In particular, the charging method of the present invention does not control so that the voltage of the high-voltage battery cell does not exceed the maximum set voltage by limiting the charging current to be small from the beginning of charging. In the charging method of the present invention, when the voltage of the high voltage battery cell exceeds the maximum set voltage, the charging power is controlled to be small. Therefore, the charging of the high voltage battery cell is performed while charging with a large current at the beginning of charging. The battery pack can be fully charged while the voltage is lower than the maximum set voltage. For this reason, the charging method of the present invention is characterized in that the voltage of the high-voltage battery cell of the assembled battery can be made lower than the maximum set voltage and the charging capacity of the assembled battery can be increased while fully charging the assembled battery in a short time. Realized.

  Further, according to the charging method of claim 2 of the present invention, when the voltage of the high voltage battery cell exceeds the maximum set voltage, the charging voltage for charging the assembled battery is reduced to limit the charging power to a small value. According to the charging method of claim 7, when the voltage of the high voltage battery cell exceeds the maximum set voltage, the set current for charging the assembled battery is controlled to be small to reduce the charging power. Switching battery power supplies are almost always used for battery chargers. The switching power supply converts the input 100V AC to DC, inputs DC power to the transformer input side via the switching element, rectifies the transformer output side to convert to DC, and charges the assembled battery Output power. This switching power supply stabilizes the output voltage and output current with a duty for switching the switching element on and off. In order to stabilize the output voltage, a voltage feedback circuit for controlling a duty for switching the switching element on and off is provided. Further, in order to stabilize the output current, a current feedback circuit for controlling a duty for switching the switching element on and off is provided. According to the charging method of the second aspect of the present invention, the charging power of the assembled battery can be easily controlled by controlling the voltage feedback circuit. According to the charging method of the seventh aspect of the present invention, the charging power of the assembled battery can be easily controlled by controlling the current feedback circuit.

  Furthermore, in the charging method according to claim 3 of the present invention, when the voltage of the high-voltage battery cell exceeds the maximum set voltage, the charging voltage for charging the assembled battery is reduced at a specific rate. In the charging method according to claim 8 of the present invention, when the voltage of the high voltage battery cell exceeds the maximum set voltage, the set current for charging the assembled battery is reduced at a specific rate. In these charging methods, every time the voltage of the high-voltage battery cell exceeds the maximum set voltage, the charging voltage for charging the assembled battery is reduced by 5% or the set current is reduced by 20%. This method can charge the assembled battery to a sufficient capacity while preventing the voltage of the high-voltage battery cell from becoming abnormally high with a simple circuit configuration.

  In addition, the charging method according to claim 4 and claim 9 of the present invention is configured such that when the voltage of the high-voltage battery cell exceeds the maximum set voltage, the rate at which the charge voltage is reduced or the rate at which the set current is reduced is set to the high-voltage battery. It is specified from the difference voltage between the cell voltage and the maximum set voltage, and when the difference voltage is large, the charging voltage or the set current is reduced. According to this method, after the voltage of the high-voltage battery cell exceeds the maximum set voltage, the voltage and current for charging the assembled battery can be optimized. For this reason, it is possible to charge the assembled battery with a sufficient capacity in a short time while preventing the voltage of the high-voltage battery cell from becoming abnormally high.

  Furthermore, in the charging method according to claim 5 and claim 10 of the present invention, when the voltage of the high-voltage battery cell exceeds the maximum set voltage, the rate at which the charge voltage or set current is reduced is set to a battery exceeding the maximum set voltage. If the internal resistance of the battery cell is large, the rate of reducing the charging voltage or set current is increased. This method can also optimize the voltage and current for charging the assembled battery after the voltage of the high voltage battery cell exceeds the maximum set voltage, while preventing the voltage of the high voltage battery cell from becoming abnormally high. The battery can be charged to a sufficient capacity in a short time.

  Furthermore, in the charging method according to claim 6 of the present invention, when the voltage of the high-voltage battery cell exceeds the maximum set voltage, the charging voltage for charging the assembled battery is a voltage value obtained by adding the voltage of each battery cell. Since charging is performed by reducing the voltage, it is possible to reliably prevent the charging voltage from becoming lower than the battery voltage while simplifying the control of the charging voltage, and to continue charging the assembled battery.

  In the charging method according to claim 11 of the present invention, the maximum set voltage for comparing the voltages of the high-voltage battery cells is changed by the battery temperature. Therefore, even when the battery is in the low temperature range or in the high temperature range. The battery pack can be charged without deteriorating battery performance while protecting the battery.

  Furthermore, in the charging method according to claim 12 of the present invention, since the set current for charging the battery is changed by the battery temperature, the battery is protected even when the battery is in a low temperature range or a high temperature range. However, the assembled battery can be charged without degrading the battery performance. The charging method according to claim 13 of the present invention is a simple charging method because the set current to be reduced is a set current set in multiple stages, and the power supply circuit for performing this method is also simple. It will be cheap.

  Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below exemplify an assembled battery charging method for embodying the technical idea of the present invention, and the present invention does not specify the assembled battery charging method as the following method. Further, this specification does not limit the members shown in the claims to the members of the embodiments.

  FIG. 1 is a block diagram of a charging circuit that charges an assembled battery 1 composed of a plurality of lithium ion secondary batteries 3. The charging circuit of this figure includes a power supply circuit 4 that charges the assembled battery 1 at a constant voltage and a constant current, a control circuit 5 that controls a charging voltage and a set current at which the power supply circuit 4 charges the assembled battery 1, and the control circuit 5, a voltage detection circuit 6 that detects and outputs the voltage of each battery 3, a current detection circuit 7 that detects a charging current of the battery 3, and a temperature detection circuit 8 that detects and outputs the temperature of the battery 3. Prepare.

  The battery pack 1 shown in the figure has three battery cells 2 connected in series. Each battery cell 2 has two lithium ion secondary batteries 3 connected in parallel. As shown in this figure, the battery cell 2 can connect a plurality of unit cells 3 in parallel. However, a battery cell can also be comprised with one unit cell. Furthermore, the assembled battery 1 in the figure has three battery cells 2 connected in series, but the assembled battery charged by the method of the present invention has two battery cells connected in series, or four or more batteries. Battery cells may be connected in series.

  The power supply circuit 4 is a switching power supply. The switching power source switches the direct current obtained by rectifying the alternating current 100V, which is the commercial power source 9, by the switching element 10 and inputs the direct current to the primary side of the transformer 11. The AC output on the secondary side of the transformer 11 is rectified to output power for charging the assembled battery 1. This switching power supply controls the output with a duty for switching the switching element 10 on and off. The output time is increased by increasing the ON time of the switching element 10, and the output is decreased by decreasing the ON time. Since the power supply circuit 4 charges the assembled battery 1 at a constant voltage / constant current, the voltage feedback circuit 12 that controls the maximum value of the output voltage to be constant and the current feedback circuit 13 that restricts the maximum value of the output current to a constant value are switched. The input circuit 14 of the element 10 is connected. The voltage feedback circuit 12 controls the duty of the switching element 10 via the input circuit 14 to control the maximum value of the output voltage to the maximum voltage of the assembled battery 1. For example, in the power supply circuit 4 that charges the assembled battery 1 in which three battery cells 2 are connected in series, the maximum value of the output voltage is set to 12.6V. Further, the current feedback circuit 13 controls the duty of the switching element 10 via the input circuit 14 to control the maximum value of the output current to the maximum current for charging the assembled battery 1.

  The voltage detection circuit 6 detects the voltage of each battery cell 2 connected in series, converts the detected voltage into a digital signal, and inputs the digital signal to the control circuit 5. The current detection circuit 7 detects the charging current of the assembled battery 1, converts the detected current into a digital signal, and inputs the digital signal to the control circuit 5. Further, the temperature detection circuit 8 also detects the surface temperature of the battery 3, converts the detected temperature into a digital signal, and inputs the digital signal to the control circuit 5.

  The control circuit 5 compares the maximum set voltage stored in the storage circuit 15 with the voltage of the battery, and stores the charging voltage and charging current of the assembled battery 1. And a power reduction circuit 16 to be controlled.

  FIG. 2 shows the maximum set voltage stored in the storage circuit 15. Here, the maximum set voltage is a voltage set slightly lower than the overcharge protection voltage that the battery to be charged must never exceed. The storage circuit 15 storing the data of FIG. 2 divides the temperature band of the battery to be charged into a low temperature range, a standard temperature range, and a high temperature range, and the maximum set voltage in each temperature range. Is remembered. The low temperature boundary temperature (T1) between the low temperature region and the standard temperature region is 10 ° C. However, the low temperature boundary temperature (T1) between the low temperature region and the standard temperature region may be 5 ° C to 15 ° C. The high temperature boundary temperature (T2) between the standard temperature range and the high temperature range is 45 ° C. However, the high temperature boundary temperature (T2) between the standard temperature range and the high temperature range may be 40 ° C to 60 ° C. Further, charging can be stopped in a region where the temperature is lower than the low temperature region (for example, less than 0 ° C.) and a region where the temperature is higher than the high temperature region (for example, a region exceeding 60 ° C.).

Here, the overcharge protection voltage that the battery to be charged must not exceed is set by the temperature band of the battery to be charged. The overcharge protection voltage in the low temperature range and the high temperature range is set lower than the overcharge protection voltage in the standard temperature range, and the overcharge protection voltage in the low temperature range is lower than the overcharge protection voltage in the high temperature range. Set low. As shown in FIG. 2, the maximum set voltage in each temperature band is set slightly lower than the overcharge protection voltage set in each temperature band, for example, 20 mV to 100 mV. That is, the first maximum set voltage (V1) for charging the battery in the low temperature range is lower than the second maximum set voltage (V2) for charging the battery in the standard temperature range. In addition, the third maximum set voltage (V3) for charging the battery in the high temperature range is lower than the second maximum set voltage (V2). Furthermore, the first maximum set voltage (V1) is lower than the third maximum set voltage (V3). However, the first maximum set voltage (V1) can be higher than the third maximum set voltage (V3).
When the overcharge protection voltage is undesirably exceeded and the battery voltage exceeds, a protection operation such as turning off a charging switching element connected in series with the battery is performed to stop charging.

  Since the second maximum set voltage (V2) is set to an optimum voltage value for the type of lithium ion secondary battery, overcharge protection is provided for lithium cobaltate-carbon lithium ion secondary batteries. The voltage is set to 4.22 V, which is 20 mV to 100 mV lower than the voltage, for example, 30 mV lower than 4.25 V. However, in this type of lithium ion secondary battery, the second maximum set voltage (V2) can be set in the range of 4.2V to 4.24V. The first maximum set voltage (V1) is set 20 mV to 100 mV lower than the overcharge protection voltage in the low temperature range, and is set to 4.03 V, for example. The third maximum set voltage (V3) is set 20 mV to 100 mV lower than the overcharge protection voltage in the high temperature range, and is set to 4.13 V, for example.

  However, the first maximum setting voltage (V1) and the third maximum setting voltage (V3) can also be specified based on the second maximum setting voltage (V2). For example, the first maximum set voltage (V1) can be set 30 mV to 300 mV lower than the second maximum set voltage (V2). When the third maximum set voltage (V3) is set lower than the second maximum set voltage (V2) and higher than the first maximum set voltage (V1), the third maximum set voltage (V3) ) And the second maximum set voltage (V2) so that the voltage difference between the second maximum set voltage (V2) and the first maximum set voltage (V1) is 30% to 80%. A maximum set voltage (V3) of 3 can also be set.

  The power reduction circuit 16 specifies the maximum set voltage based on the data stored in the storage circuit 15 from the temperature of the battery 3 detected by the temperature detection circuit 8. For example, when the battery temperature is 20 ° C., the maximum set voltage is set lower than 4.25V, for example, 4.22V. Further, the power reduction circuit 16 compares the voltage of each battery cell 2 detected by the voltage detection circuit 6 with the maximum set voltage, and when the voltage of the high voltage battery cell with the highest voltage exceeds the maximum set voltage, The output of the power supply circuit 4 that charges the battery 1 is controlled to be small. The power reduction circuit 16 controls the output power by controlling the duty for switching the switching element 10 on and off via the voltage feedback circuit 12 or the current feedback circuit 13.

  When the high-voltage battery cell exceeds the maximum set voltage, the power reduction circuit 16 reduces the charging voltage for charging the assembled battery 1 at a specific rate, or reduces the set current for charging the assembled battery 1 at a specific rate. Reduce the charging power. Each time the voltage of the high voltage battery cell 2 exceeds the maximum set voltage, the power reduction circuit 16 reduces the charging voltage to, for example, 95% to reduce the charging power. Alternatively, every time the voltage of the high voltage battery cell 2 exceeds the maximum set voltage, the power reduction circuit 16 reduces the set current to, for example, 80% to reduce the charging power. However, the power reduction circuit 16 can reduce the charging voltage and set current to 50% to 99%.

  In addition, when the voltage of the high-voltage battery cell exceeds the maximum set voltage, the power reduction circuit 16 determines the rate at which the charging voltage or set current for charging the assembled battery 1 is reduced by the battery cell voltage (here, each battery cell The voltage value obtained by adding the voltages) and the maximum set voltage (here, the maximum set voltage per cell multiplied by the number of cells connected in series (3 in this embodiment)) When the differential voltage is large, the rate of reducing the charging voltage or the set current can be increased. For example, the power reduction circuit 16 can increase the rate of reducing the charging voltage or the set current in proportion to the difference between the battery cell voltage and the maximum set voltage.

Furthermore, when the voltage of the high-voltage battery cell exceeds the maximum set voltage, the power reduction circuit 16 specifies the rate of reducing the charging voltage from the internal resistance of the battery cell that exceeds the maximum set voltage, and the internal resistance of the battery cell If the value is large, the rate of reducing the charging voltage can be increased. The power reduction circuit 16 includes an internal resistance (R) of the high-voltage battery cell, a charge voltage (Ec) and a charge current (I) in a state where the high-voltage battery cell is charged, and an open-circuit voltage for stopping charging. From (Eo), the following formula is used to calculate the rate at which the charging voltage or set current is reduced from the calculated internal resistance (R). For example, the power reduction circuit 16 increases the rate of decreasing the charging voltage or set current in proportion to the internal resistance (R).
R = (Ec−Eo) / I

  The charging circuit of FIG. 1 charges the assembled battery 1 in the following steps based on the flowchart shown in FIG. This flowchart shows a charging method for reducing the charging voltage (Ec) for charging the battery pack 1 at a constant voltage / constant current when the voltage (Ecell) of the high voltage battery cell exceeds the maximum set voltage (Vmax). Yes. FIG. 4 shows the voltage and current characteristics of the battery charged based on this flowchart. In FIG. 4, a solid line A indicates a change in the voltage of the high-voltage battery cell, a solid line B indicates a change in the voltage of another battery cell, and a one-dot chain line C indicates a charging voltage (Ec for charging the assembled battery at a constant voltage / constant current. ) (A voltage obtained by multiplying the number of cells connected in series with the charging voltage (Ec) of FIG. 4 (3 in this embodiment) is applied to the assembled battery 1), and the solid line D indicates the assembled battery to be charged. The change in charging current (I) is shown respectively.

[Step of n = 1]
A temperature detection circuit 8 detects the temperature of the battery.
[Step of n = 2]
The maximum set voltage (Vmax) is specified from the detected battery temperature.
[Step n = 3]
Start constant voltage / constant current charging.
[Steps n = 4, 5]
It is determined whether the charging current (I) has become smaller than the minimum current (Imin). The minimum current (Imin) is set to a charging current when the assembled battery 1 is fully charged. Therefore, when the charging current (I) of the assembled battery 1 becomes smaller than the minimum current (Imin), it is determined that the battery is fully charged, and charging is terminated.
[Step n = 6]
If the charging current (I) does not decrease to the minimum current (Imin), the voltage (Ecell) of the high voltage battery cell is compared with the maximum set voltage (Vmax). The steps of n = 4 and 6 are looped until the charging current (I) becomes the minimum current (Imin) or the voltage (Ecell) of the high voltage battery cell becomes higher than the maximum set voltage (Vmax).
[Step n = 7]
When the voltage (Ecell) of the high voltage battery cell becomes higher than the maximum set voltage (Vmax), the charging voltage (Ec) at which the power supply circuit 4 charges the assembled battery 1 is charged at, for example, 95% (12.6 V). The power supply circuit 4 is reduced to about 12 V), the power for charging the assembled battery 1 is reduced, and the process returns to the step of n = 3.
Thereafter, until the charging current (I) becomes equal to or less than the minimum current (Imin), the steps of n = 3, 4, 6, and 7 are looped, and the voltage (Ecell) of the high voltage battery cell is set to the maximum set voltage (Vmax). Is exceeded, the battery pack 1 is charged by reducing the charging voltage (Ec), which is the output voltage of the power supply circuit 4, to 95%.
When the charging voltage is lowered at a constant rate, the current battery voltage is set as the lower limit value of the charging voltage calculated by multiplying the constant rate. This is because charging cannot be performed if the charging voltage and the battery voltage are reversed. Therefore, when the charging voltage calculated by multiplying by a constant rate becomes smaller than the battery voltage, the charging voltage is set to the battery voltage. Here, the battery voltage is a voltage value obtained by adding the voltages of the respective battery cells, similarly to the above-described battery cell voltage.
Here, instead of the above, every time the voltage (Ecell) of the high-voltage battery cell exceeds the maximum set voltage (Vmax), when the charge voltage (Ec) is lowered, the charge voltage (Ec) It can also be set as the battery voltage which is the voltage value which added the voltage of the cell.

  Further, the flowchart shown in FIG. 5 is a charging method for reducing the set current (Ic) for charging the assembled battery 1 at a constant voltage / constant current when the voltage (Ecell) of the high voltage battery cell exceeds the maximum set voltage (Vmax). Is shown. FIG. 6 shows the voltage and current characteristics of the battery charged based on this flowchart. In FIG. 6, the solid line A indicates the change in the voltage of the high voltage battery cell, the solid line B indicates the change in the voltage of the other battery cell, and the solid line D indicates the change in the charging current (I) of the assembled battery to be charged. An alternate long and short dash line E indicates a change in the set current (Ic) for charging the assembled battery at a constant voltage and a constant current.

[Step of n = 1]
A temperature detection circuit 8 detects the temperature of the battery.
[Step of n = 2]
The maximum set voltage (Vmax) is specified from the detected battery temperature.
[Step n = 3]
Start constant voltage / constant current charging.
[Steps n = 4, 5]
It is determined whether the charging current (I) has become smaller than the minimum current (Imin). The minimum current (Imin) is set to a charging current when the assembled battery 1 is fully charged. Therefore, when the charging current (I) of the assembled battery 1 becomes smaller than the minimum current (Imin), it is determined that the battery is fully charged, and charging is terminated. ,
[Step n = 6]
If the charging current (I) does not decrease to the minimum current (Imin), the voltage (Ecell) of the high voltage battery cell is compared with the maximum set voltage (Vmax). The steps of n = 4 and 6 are looped until the charging current (I) becomes the minimum current (Imin) or the voltage (Ecell) of the high voltage battery cell becomes higher than the maximum set voltage (Vmax).
[Step n = 7]
When the voltage (Ecell) of the high voltage battery cell becomes higher than the maximum set voltage (Vmax), the set current (Ic) at which the power supply circuit 4 charges the assembled battery 1 is reduced to, for example, 80%, and the assembled battery 1 The power for charging is reduced, and the process returns to the step of n = 3.
Thereafter, until the charging current (I) becomes equal to or less than the minimum current (Imin), the steps of n = 3, 4, 6, and 7 are looped, and the voltage (Ecell) of the high voltage battery cell is set to the maximum set voltage (Vmax). Is exceeded, the set current (Ic) of the power supply circuit 4 is reduced to 80%, and the assembled battery 1 is charged.
Note that if the charging current value calculated by multiplying by a constant ratio is smaller than the full charge detection current setting value, full charging will be erroneously detected, so the lower limit of the charging current to be calculated is the full charge detection current setting value. Up to.

Furthermore, the charging method of the present invention can detect the battery temperature and specify the set current for charging the assembled battery from the detected battery temperature. A charging circuit for realizing this is shown in FIG. This figure shows a state in which the battery pack 100 including the assembled battery 1 composed of a plurality of lithium ion secondary batteries 3 is connected to an electronic device 200 such as a personal computer for charging.
In FIG. 7, the same components as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The electronic device 200 shown in the figure includes a power supply circuit 24 that charges the assembled battery 1 at a constant voltage and a constant current. In the electronic device 200, AC 100 V to 240 V, which is the commercial power source 9, is rectified to 16 V to 20 V DC by the AC adapter 20 and input to the power supply circuit 24. The power supply circuit 24 is a switching power supply and controls the output with a duty for switching the switching element 10 on and off. The battery pack 100 includes a control circuit 25 that controls a charging voltage and a set current at which the power supply circuit 24 charges the assembled battery 1. The temperature detection circuit 8 detects the temperature of the battery 3 and the detected battery temperature. The set current for charging the assembled battery 1 is identified and output to the electronic device 200 side. The control circuit 25 specifies the setting current from the storage circuit 35 storing data for specifying the set current from the battery temperature, the data stored in the storage circuit 35 and the battery temperature detected by the temperature detection circuit 8. In addition, a power reduction circuit 36 that outputs to the power supply circuit 24 is provided.

  An example of data stored in the storage circuit 35 is shown in FIG. As shown in this figure, the storage circuit 35 divides the temperature range of the battery to be charged into a low temperature range, a standard temperature range, and a high temperature range, and stores the set current in each temperature range. ing. The low temperature boundary temperature (T1) between the low temperature region and the standard temperature region is 10 ° C. However, the low temperature boundary temperature (T1) between the low temperature region and the standard temperature region may be 5 ° C to 15 ° C. The high temperature boundary temperature (T2) between the standard temperature range and the high temperature range is 45 ° C. However, the high temperature boundary temperature (T2) between the standard temperature range and the high temperature range may be 40 ° C to 60 ° C. Further, charging can be stopped in a region where the temperature is lower than the low temperature region (for example, less than 0 ° C.) and a region where the temperature is higher than the high temperature region (for example, a region exceeding 60 ° C.).

The set current for charging the battery is set according to the temperature band of the battery. The set current in the low temperature range and the high temperature range is set lower than the set current in the standard temperature range, and the set current in the low temperature range is set lower than the set current in the high temperature range. That is, the low temperature range setting current (I1) for charging the battery in the low temperature range is lower than the standard setting current (I2) for charging the battery in the standard temperature range. Moreover, the high temperature range setting current (I3) for charging the battery in the high temperature range is set lower than the standard setting current (I2). Furthermore, the low temperature region setting current (I1) is set lower than the high temperature region setting current (I3). However, the low temperature region setting current (I1) can be made higher than the high temperature region setting current (I3).
FIG. 8 shows that the set current in the standard temperature range is 0.7 C (can be set in the range of about 0.5 C to 1.2 C), and the set current in the low temperature range is 0.1 C (the current that decreases at full charge). It is set larger than the full charge detection current value.), The set current in the high temperature range is set to 0.35C (set to about half of the set current in the standard temperature range).

In each temperature range, the initial setting value of the charging current value at the start of charging can be determined from two parameters, temperature and remaining capacity, or temperature and voltage. For example, as shown in Table 1 and Table 2 below, the lowest battery voltage detected (battery voltage corresponding to the battery capacity) or the remaining capacity calculated by the microcomputer in the battery pack using a known technique The set current in each temperature range can be changed from (RSOC battery capacity).
Here, for example, A [V] in Table 1 can be set to 3.5V, and B [V] can be set to 4.0V. Further, for example, C [%] in Table 2 may be 40% and D [%] may be 80%.

  Such a set current is mainly used for the following reason. This is because when the battery capacity is large and the battery temperature is low, the battery voltage rises due to a large current and prevents the maximum set voltage and overcharge protection voltage described in FIG. 2 from being exceeded.

  The power reduction circuit 36 specifies a set current for charging the assembled battery 1 from the data stored in the storage circuit 35 and the battery temperature. The power reduction circuit 36 specifies the set current as one of the low temperature range set current (I1), the standard set current (I2), and the high temperature range set current (I3) according to the detected temperature band of the battery. The power reduction circuit 36 outputs a signal specifying the set current to the current feedback circuit 33 of the power supply circuit 24.

  The power supply circuit 24 detects a signal input from the control circuit 25 and controls the maximum value of the output current. The current feedback circuit 33 of the power supply circuit 24 can switch the maximum value of the output current to a three-stage set current composed of a low temperature range set current (I1), a standard set current (I2), and a high temperature range set current (I3). It has a structure. That is, the power supply circuit 24 can be switched to set currents set in multiple stages in advance. The power supply circuit 24 that can be switched to set currents set in multiple stages in this way has a relatively simple structure and is inexpensive, and a charging method that uses this is simple. In the power supply circuit 24, a signal for specifying the set current as one of the low temperature range set current (I1), the standard set current (I2), and the high temperature range set current (I3) is sent from the power reduction circuit 36 to the current feedback circuit 33. When input, the current feedback circuit 33 controls the duty of the switching element 10 via the drive circuit 34 to control the maximum value of the output current to the set current for charging the assembled battery 1. That is, in the power supply circuit 24, the current feedback circuit 33 switches the maximum value of the output current to any one of the low temperature region setting current (I1), the standard setting current (I2), and the high temperature region setting current (I3). Charge the battery pack.

  The above control circuit 25 detects the battery temperature at the start of charging, identifies the set current for charging the assembled battery 1 from the detected battery temperature, and outputs the specified current to the power supply circuit 24. The power supply circuit 24 detects the signal input from the control circuit 25 and charges the assembled battery while controlling the maximum value of the output current to the specified set current. Further, the control circuit 25 detects the battery temperature even during charging of the assembled battery 1, specifies a set current from the detected battery temperature, and outputs the set current to the power supply circuit 24. The power supply circuit 24 detects the signal input from the control circuit 25 and controls the maximum value of the output current to the specified set current. However, if the set current specified from the battery temperature at the start of charging is different from the set current specified from the battery temperature during charging, the lower set current is selected to continue charging. For example, at the start of charging, a battery whose battery temperature is in the standard temperature range starts charging with the set current as the standard set current (I2). Thereafter, when the battery temperature rises to a high temperature range as the charging proceeds, the set current is switched to the high temperature range set current (I3) and the charging is continued. This is because the high temperature region set current (I3) is set lower than the standard set current (I2). Further, at the start of charging, the battery whose battery temperature is in the low temperature range starts charging with the set current as the low temperature set current (I1), but thereafter, as the charging progresses, the battery temperature reaches the standard temperature range. Even if it rises, charging is continued without switching the set current to the standard set current (I3). This is because the low temperature region set current (I1) is set lower than the standard set current (I2). In this way, the method of giving priority to the lower setting current among the setting current specified from the battery temperature at the start of charging and the setting current specified from the battery temperature during charging is the setting current for charging the battery. The battery can be safely charged while reliably preventing the battery from becoming dangerous.

Further, in the control circuit 25, the power reduction circuit 36 controls the charging current of the assembled battery 1 by comparing the maximum set voltage stored in the storage circuit 35 with the voltage of the battery. When the high voltage battery cell exceeds the maximum set voltage, the power reduction circuit 36 reduces the set current for charging the assembled battery 1 to reduce the charging power. When the voltage of the high-voltage battery cell exceeds the maximum set voltage, the power reduction circuit 36 outputs a signal for reducing the set current, which is the maximum value of the output current, to a current value that is one rank lower to the current feedback circuit 33 of the power supply circuit 24. To do. For example, when the current set current (Ic) is the standard set current (I2), the set current (Ic) is lowered to the high temperature range set current (I3), and the current set current (Ic) is reduced to the high temperature range set current (I3). ), The set current (Ic) is lowered to the low temperature range set current (I1). That is, the power supply circuit 24 is controlled by the control circuit 25 and continues charging the assembled battery 1 while reducing the set current to be charged.
That is, when the high-voltage battery cell exceeds the maximum set voltage, the set current for charging the assembled battery 1 is lowered, and the reduced set current is set as a preset set current that is changed and set in advance according to the battery temperature. In other words, such a set current is a set current set in multiple stages.
In the above-mentioned set current, three stages of set currents (I2), (I3), and (I1) are used, but as a multistage set current exceeding three stages, the voltage of the high-voltage battery cell is the battery temperature at that time. When the maximum set voltage at is exceeded, the set current, which is the maximum value of the output current, can be lowered to a current value one rank lower.

  Furthermore, the control circuit 25 sets the set current specified from the temperature range of the battery temperature detected during the charging of the assembled battery 1 and the voltage of the high-voltage battery cell to the maximum while the charging of the assembled battery 1 is continued. Among the set currents that have been lowered beyond the voltage, the lower set current is prioritized and the battery pack is continuously charged with this set current.

  The charging circuit in FIG. 7 charges the assembled battery 1 in the following steps based on the flowchart shown in FIG. As shown in this flowchart, when the voltage (Ecell) of the high voltage battery cell exceeds the maximum set voltage (Vmax), the charging circuit reduces the set current (Ic) for charging the assembled battery 1 at a constant voltage / constant current. To charge. FIG. 10 shows the voltage and current characteristics of the battery to be charged based on this flowchart. In FIG. 10, a solid line A indicates a change in the voltage of the high-voltage battery cell, a solid line B indicates a change in the voltage of another battery cell, and a solid line D indicates a change in the charging current (I) of the assembled battery to be charged. An alternate long and short dash line E indicates a change in the set current (Ic) for charging the assembled battery at a constant voltage and a constant current.

[Step of n = 1]
A temperature detection circuit 8 detects the temperature of the battery.
[Step of n = 2]
The control circuit 25 specifies the maximum set voltage (Vmax) from the detected battery temperature.
[Step n = 3]
The control circuit 25 specifies a set current (Ic) for charging the battery from the detected battery temperature and outputs it to the power supply circuit 24. The control circuit 25 specifies the set current (Ic) from the battery temperature based on the data stored in the storage circuit. As shown in FIG. 8, the set current (Ic) is specified as one of the low temperature range set current (I1), the standard set current (I2), and the high temperature range set current (I3) depending on the detected temperature band of the battery. Is done.
[Step n = 4]
Charging of the assembled battery 1 is started. The power supply circuit 24 charges the assembled battery 1 at a constant voltage / constant current while controlling the maximum value of the output current to the set current (Ic) specified in the step of n = 3.
[Steps n = 5, 6]
It is determined whether or not the charging current (I) has become equal to or less than the minimum current (Imin). The minimum current (Imin) is set to a charging current when the assembled battery 1 is fully charged. Accordingly, when the charging current (I) of the assembled battery 1 becomes equal to or less than the minimum current (Imin), it is determined that the battery is fully charged and the charging is terminated.
[Step n = 7]
If the charging current (I) has not decreased to the minimum current (Imin), the control circuit 25 compares the voltage (Ecell) of the high voltage battery cell with the maximum set voltage (Vmax) in this step.
[Step n = 8]
If the voltage (Ecell) of the high-voltage battery cell is equal to or lower than the maximum set voltage (Vmax), the temperature detection circuit 8 detects the temperature of the battery in this step and specifies the set current (Ic) from the detected battery temperature. .
[Step n = 9]
The control circuit 25 specifies the latest set current (Ic) from the current set current (Ic) and the set current (Ic) specified in the step of n = 8. For example, when the current set current is the set current (Ic) specified in the step n = 3, the set current (Ic) specified in the step n = 8 and the set current specified in the step n = 3 The latest set current (Ic) is specified from (Ic). When the current set current (Ic) is equal to the set current (Ic) specified in the step of n = 8, the control circuit 25 outputs the set current as the latest set current (Ic) to the power supply circuit 24. To do. Further, when the current set current is different from the set current specified in the step of n = 8, the control circuit 25 outputs the lower value to the power supply circuit 24 as the latest set current (Ic).
[Step n = 10]
The power supply circuit 24 continues charging the assembled battery 1 while controlling the maximum value of the output current to the latest set current (Ic) specified in the previous step. Thereafter, the process returns to the step of n = 5.
[Step n = 11]
When the voltage (Ecell) of the high voltage battery cell becomes higher than the maximum set voltage (Vmax), the current set current (Ic) is lowered to the low temperature range set current (I1) which is the lowest set current in this step. Determine whether or not. When the current set current (Ic) is equal to the low temperature range set current (I1), the set current (Ic) cannot be lowered any more, so the process proceeds to step n = 6 and the charging is terminated.
[Step n = 12]
When the current set current (Ic) is not equal to the low temperature range set current (I1), it is determined that the current set current (Ic) is larger than the low temperature range set current (I1), and the set current (Ic) is set to 1. Lower the current value to a lower rank. That is, when the current set current (Ic) is the standard set current (I2), the set current (Ic) is lowered to the high temperature range set current (I3), and the current set current (Ic) is reduced to the high temperature range set current (I3). ), The set current (Ic) is lowered to the low temperature range set current (I1). The control circuit 25 outputs the set current lowered by one rank to the power supply circuit 24 as the latest set current (Ic). Then, it proceeds to the step of n = 10 and continues to charge the assembled battery 1

  In the above embodiment, the battery voltage is detected, and the battery voltage rises to the maximum set voltage to decrease the current, but the current set values are set to the standard temperature range, the low temperature range, and the high temperature range. It is set current. In this battery pack, the circuit value can be simplified because the current value changed to control the current at the battery temperature and the current value changed by increasing the battery voltage are switched to the same set value. Further, the set current for charging the battery can be switched to three stages of a low temperature range, a standard temperature range, and a high temperature range depending on the battery temperature range. However, in the charging method of the present invention, the set current specified by the battery temperature can be two stages or four or more stages.

  Furthermore, the battery pack does not convert the battery voltage or current into a digital signal, and the detection signal for detecting the battery voltage or current is changed to a reference voltage with a differential amplifier as shown in the circuit diagram of FIG. In comparison, the current and voltage can be controlled. The battery pack of FIG. 11 has a maximum voltage detection circuit 60, a set voltage detection circuit 70, a maximum voltage detection circuit 60, and a set voltage detection circuit in order to detect the voltage of the charged battery 53 and prevent overcharge. 70 includes reference voltage circuits 81 and 82 for outputting a reference voltage.

  In the illustrated battery pack, two unit cells 53 are connected in series to form an assembled battery 51. Therefore, in order to detect the voltages of the plus unit cell 53 and the minus unit cell 53, the maximum voltage detection circuit 60 is used. Includes two sets of differential amplifiers 61. The differential amplifier 61B on the negative side inputs the reference voltage from the reference voltage circuit 82 to the negative input terminal, and connects the positive input terminal to the negative unit cell 53 via the resistance voltage dividing circuit 62. ing. The minus side differential amplifier 61B outputs a maximum voltage signal when the voltage of the minus side cell 53 exceeds the maximum voltage. The plus-side differential amplifier 61A inputs the reference voltage from the reference voltage circuit 81 to the plus-side input terminal, and connects the minus-side input terminal to the plus-side cell 53 via the resistance voltage dividing circuit 62. ing. The plus-side differential amplifier 61A outputs a maximum voltage signal when the voltage of the plus-side unit cell 53 exceeds the maximum voltage. For example, in the case of a pack battery in which the unit cell 53 is a lithium ion secondary battery, these differential amplifiers 61 output a maximum voltage signal when the plus and minus unit cells 53 exceed 4.25V. As described above, the resistance voltage dividing circuit 62 and the reference voltage are set.

  The outputs of the positive differential amplifier 61A and the negative differential amplifier 61B are input to the OR circuit 63. The OR circuit 63 outputs a maximum voltage signal when any of the unit cells 53 exceeds the maximum voltage (4.25V in the case of a lithium ion secondary battery), and outputs this signal to a charger (not shown). Output to stop charging. Furthermore, with this signal, the charging voltage and charging current can be reduced as described above.

  The set voltage detection circuit 70 includes a set voltage detection circuit 70A for charge control that detects overcharge of the battery 53, and a set voltage detection circuit 70B for discharge control that detects overdischarge. The set voltage detection circuit 70A for charge control includes two sets of differential amplifiers 71 in order to detect the set voltages of the plus unit cell 53 and the minus unit cell 53. The differential amplifier 71B on the negative side inputs the reference voltage from the reference voltage circuit 82 to the input terminal on the negative side, and connects the input terminal on the positive side to the negative unit cell 53 via the voltage dividing ratio changing circuit 72. Yes. The minus side differential amplifier 71B outputs a voltage signal when the voltage of the minus side cell 53 exceeds a set voltage. The differential amplifier 71A on the plus side inputs the reference voltage from the reference voltage circuit 81 to the plus side input terminal, and connects the minus side input terminal to the plus unit cell 53 via the voltage dividing ratio changing circuit 72. Yes. The plus-side differential amplifier 71A outputs a voltage signal when the voltage of the plus-side unit cell 53 exceeds the set voltage.

  The voltage dividing ratio changing circuit 72 changes the ratio for dividing the voltage of the unit cell 53 and inputs the changed voltage to the differential amplifier 71. Therefore, the differential amplifier 71 that controls charging can detect the first set voltage and the second set voltage set to a voltage lower than the first set voltage and output a voltage signal. The first set voltage is, for example, the maximum set voltage in the standard temperature range (4.22V in FIG. 2), and the second set voltage is the maximum set voltage in the high temperature range or the low temperature range (4. 03V or 4.13V).

  The voltage dividing ratio changing circuit 72 in FIG. 11 shorts a part of the voltage dividing resistor 74 with the switching element 75 to change the voltage dividing ratio. The voltage dividing ratio changing circuit 72 shown in the figure is composed of a series circuit of three resistors 74A, and a switching element 75 is connected in parallel to one resistor 74A. The switching element 75 adjusts the voltage dividing ratio by short-circuiting both ends of one resistor 74A. The voltage dividing ratio changing circuit 72 in the figure has a small voltage dividing ratio when the switching element 75 is turned off, and the switching element 75 is turned on to increase the voltage dividing ratio. That is, the voltage dividing ratio of the voltage of the unit cell 53 input to the differential amplifier 71 can be changed by switching the switching element 75 on and off. The voltage dividing ratio changing circuit 72 is, for example, in a state where the switching element 75 is turned on, the differential amplifier 71 outputs a voltage signal at the first set voltage, and the switching element 75 is turned off. Sets the electrical resistance of the resistor 74A so that a voltage signal is output at the second set voltage.

  The set voltage detection circuit 70A for charge control detects the first set voltage and the second set voltage and outputs a voltage signal because the voltage dividing ratio changing circuit 72 is set on the input side. Here, the voltage dividing ratio changing circuit 72 sets the first or second set voltage. The setting voltage detection circuit 70A for charge control turns off the switching element 75, detects a low second setting voltage and sets the output to “High”, then switches the switching element 75 on, and sets the high first Detect the set voltage.

  A setting voltage detection circuit 70A for charge control that detects overcharge of the battery 53 includes a negative differential amplifier 71B connected to the negative side of the battery 53 and a positive side connected to the positive side of the battery 53. Differential amplifier 71A. In the negative differential amplifier 71B, the reference voltage is input from the reference voltage circuit 82 to the negative input terminal, and the positive input terminal is connected to the negative unit cell 53 via the voltage dividing ratio change circuit 72. ing.

  When the voltage of the minus-side unit cell 53 exceeds the set voltage, the minus-side differential amplifier 71B outputs a second output signal indicating this. Since this second output signal is a signal indicating that the voltage of the battery 53 has exceeded the set voltage, the charging switching element (not shown) provided in series with the assembled battery 51 is turned off by this signal. Also, the charging voltage and charging current can be reduced. For example, the second set voltage is set to the maximum set voltage (4.03 V or 4.13 V in FIG. 2) in the high temperature range and the low temperature range, so that the temperature of the battery 53 is set to the high temperature range or the low temperature range. In this case, charging is stopped by this signal. The second output signal switches on the switching element 75 to increase the voltage dividing ratio of the voltage dividing ratio changing circuit 72 and decreases the input voltage of the differential amplifier 71. Therefore, the differential amplifier 71 is in a state where it does not output the second output signal. The battery in the standard temperature range is not stopped by the second output signal, but is further charged to increase the voltage. When the voltage of the battery 53 exceeds the first set voltage, the differential amplifier 71 outputs a first output signal as a signal exceeding the first set voltage. Since the first output signal is set to, for example, the maximum set voltage in the standard temperature range (4.22 V in FIG. 2), charging of the battery 53 charged in the standard temperature range is stopped by this signal.

  The plus-side differential amplifier 71A inputs the reference voltage from the reference voltage circuit 82 to the plus-side input terminal, and connects the minus-side input terminal to the plus unit cell 53 via the voltage dividing ratio changing circuit 72. ing. Like the minus differential amplifier 71B, the plus differential amplifier 71A outputs a second output signal when the voltage of the plus unit cell 53 exceeds the second set voltage, and the first differential amplifier 71A outputs the second output signal. When the set voltage is exceeded, a first output signal is output to control charging of the battery 53.

  The outputs of the positive differential amplifier 71A and the negative differential amplifier 71B are input to the OR circuit 73. The OR circuit 73 outputs a signal indicating that the first or second set voltage is exceeded when any of the unit cells 53 exceeds the first set voltage and further exceeds the second set voltage. The charging of the battery 53 is controlled. A battery pack in which a plurality of unit cells 53 are connected in series stops charging when the voltage of any one of the batteries 53 exceeds the maximum set voltage. Therefore, the voltage of any one of the batteries 53 has the first or second voltage. Charging stops when the set voltage is exceeded. That is, a charging switching element (not shown) provided in series with the assembled battery 51 is turned off by this signal, and charging is stopped.

  The set voltage detection circuit 70B for discharge control for detecting overdischarge of the battery 53 includes a negative differential amplifier 76B connected to the negative side of the battery 53 and a positive side connected to the positive side of the battery 53. Differential amplifier 76A. The minus side differential amplifier 76B inputs the reference voltage from the reference voltage circuit 82 to the plus side input terminal, and connects the minus side input terminal to the minus unit cell 53 via the voltage dividing ratio changing circuit 77. ing. The plus side differential amplifier 76A inputs the reference voltage from the reference voltage circuit 81 to the minus side input terminal, and connects the plus side input terminal to the plus side cell 53 via the voltage dividing ratio changing circuit 77. ing.

  The discharge control setting voltage detection circuit 70 </ b> B that controls overdischarge also inputs the voltage of the unit cell 53 to the differential amplifier 76 via the voltage division ratio change circuit 77. Therefore, the set voltage detection circuit 70B for discharge control can also control the discharge of the battery 53 with the two set voltages. Further, since the negative differential amplifier 76B for detecting the voltage of the negative battery 53 and the positive differential amplifier 76A for detecting the voltage of the positive battery are provided, either the negative side or the positive side is provided. It is possible to control the discharge by comparing the voltage of the battery 53 with the set voltage and detecting that the voltage of any battery 53 is lower than the set voltage. That is, the discharge switching element (not shown) provided in series with the assembled battery 51 is turned off by this signal, and the discharge is stopped.

  Furthermore, the battery pack 300 shown in the circuit diagram of FIG. 12 has a positive / negative output terminal 97 and a communication terminal 98. The battery pack outputs a voltage signal corresponding to the temperature of the battery 93 from the communication terminal 98. The battery pack includes a voltage detection circuit 94 that detects the voltage of each battery 93, a temperature sensor 95 that detects the temperature of the battery 93, and a signal input from the temperature sensor 95 and the voltage detection circuit 94. An arithmetic circuit 96 that outputs a voltage signal corresponding to the temperature of the battery 93 is provided. The arithmetic circuit 96 detects the temperature of the battery 93 with the temperature signal input from the temperature sensor 95, and as shown in FIG. 13, the temperature of the battery 93 is below the low temperature range, the low temperature range, and the standard temperature. It is determined whether it is in the temperature range of the temperature range, the high temperature range, or the high temperature range. FIG. 13 shows the same contents as in FIG. 2 described above, and the voltage value of the maximum set voltage is appropriately changed. Further, the vertical axis in FIG. 13 indicates the maximum set voltage and also the output voltage from the communication terminal 98 in each temperature band.

  Further, when the temperature of the battery 93 to be charged is in the low temperature range, the arithmetic circuit 96 sets the voltage of the battery 93 to the first maximum set voltage (V1) (4.03 V in FIG. 13). If the temperature of the battery 93 is higher than the first maximum set voltage (V1), a voltage signal (3V in FIG. 13) corresponding to the low temperature range is sent to the communication terminal 98. Output from. Further, in the arithmetic circuit 96, when the temperature of the battery 93 is in the standard temperature range, the voltage of the battery 93 is higher than the second maximum set voltage (V2) (4.22V in FIG. 13). If the voltage of the battery 93 is higher than the second maximum setting voltage (V2), a voltage signal corresponding to the standard temperature range (5 V in FIG. 13) is output from the communication terminal 98. Further, in the arithmetic circuit 96, when the temperature of the battery 93 is in the high temperature range, the voltage of the battery 93 is higher than the third maximum set voltage (V3) (4.13V in FIG. 13). If the temperature of the battery 93 is higher than the third maximum set voltage (V3), a voltage signal corresponding to the high temperature range (4V in FIG. 13) is output from the communication terminal 98. To do. Furthermore, when the temperature of the battery 93 is in the temperature range below the low temperature, the arithmetic circuit 96 outputs a voltage signal (1 V in FIG. 13) corresponding to the temperature range below the low temperature from the communication terminal 98, and the battery 93. In the state where the temperature is in the temperature range above the high temperature, a voltage signal (2 V in FIG. 13) corresponding to the temperature range above the high temperature is output from the communication terminal 98.

  The electronic device 400 to which the battery pack 300 is connected has a voltage signal input from one communication terminal 98, and in addition to whether the voltage of each battery 93 exceeds the set voltage, the temperature of the battery 93 is low. It is possible to detect which temperature range is below the temperature range, the low temperature range, the standard temperature range, the high temperature range, and the high temperature range. In the battery 93, when any of the high voltage battery cells exceeds the maximum set voltage, the charging of the battery can be stopped, the charging power can be lowered, the charging voltage can be lowered, or the setting current to be charged can be lowered. .

It is a block diagram which shows an example of the charging circuit used for the charging method of the assembled battery concerning one Example of this invention. It is a graph which shows the maximum setting voltage with respect to battery temperature. It is a flowchart which shows the charging method of the assembled battery concerning one Example of this invention. It is a graph which shows the characteristic of the voltage and electric current of the battery charged at the process shown in FIG. It is a flowchart which shows the charging method of the assembled battery concerning the other Example of this invention. It is a graph which shows the voltage and the characteristic of the battery charged at the process shown in FIG. It is a block diagram which shows an example of the charging circuit used for the charging method of the assembled battery concerning the other Example of this invention. It is a graph which shows the setting electric current with respect to battery temperature. It is a flowchart which shows the charging method of the assembled battery concerning the other Example of this invention. It is a graph which shows the characteristic of the voltage and electric current of the battery charged at the process shown in FIG. It is a circuit diagram which shows an example of the circuit which detects the overcharge and overdischarge of an assembled battery. It is a block diagram which shows an example of the battery pack which determines and outputs the temperature range of battery temperature. It is a graph which shows an example of the setting voltage with respect to battery temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery pack 2 ... Battery cell 3 ... Battery 4 ... Power supply circuit 5 ... Control circuit 6 ... Voltage detection circuit 7 ... Current detection circuit 8 ... Temperature detection circuit 9 ... Commercial power supply 10 ... Switching element 11 ... Transformer 12 ... Voltage feedback circuit DESCRIPTION OF SYMBOLS 13 ... Current feedback circuit 14 ... Input circuit 15 ... Memory circuit 16 ... Power reduction circuit 20 ... AC adapter 24 ... Power supply circuit 25 ... Control circuit 33 ... Current feedback circuit 34 ... Drive circuit 35 ... Memory circuit 36 ... Power reduction circuit 51 ... Battery pack 53 ... Battery 60 ... Maximum voltage detection circuit 61 ... Differential amplifier 61A ... Plus side differential amplifier
61B ... Negative side differential amplifier 62 ... Resistance voltage dividing circuit 63 ... OR circuit 70 ... Setting voltage detection circuit 70A ... Setting voltage detection circuit for charge control
70B ... Setting voltage detection circuit for discharge control 71 ... Differential amplifier 71A ... Plus side differential amplifier
71B ... Negative side differential amplifier 72 ... Voltage division ratio changing circuit 73 ... OR circuit 74 ... Voltage dividing resistor 74A ... Resistor 75 ... Switching element 76 ... Differential amplifier 76A ... Plus side differential amplifier
76B ... Negative side differential amplifier 77 ... Voltage division ratio changing circuit 81 ... Reference voltage circuit 82 ... Reference voltage circuit 93 ... Battery 94 ... Voltage detection circuit 95 ... Temperature sensor 96 ... Arithmetic circuit 97 ... Output terminal 98 ... Communication terminal 100 ... Pack Battery 200 ... electronic device 300 ... pack battery 400 ... electronic device

Claims (10)

A battery pack charging method in which a battery pack in which a plurality of batteries are connected in series is charged at a constant voltage and a constant current while detecting the voltage of each battery,
Start charging at the first set current specified from the detected parameter ,
The voltage of each battery cell is detected at a predetermined sampling cycle, and when any battery cell voltage exceeds the preset maximum set voltage, the set current for charging the assembled battery is lowered to charge the assembled battery. To reduce the charging power
During charging, the second set current is identified from the detected battery temperature,
If the voltage of the high-voltage battery cell is less than or equal to the maximum set voltage, the reduced set current is compared with the second set current, and when the reduced set current is not equal to the second set current, the lower one Continue charging at the set current of
A charging method for an assembled battery that performs constant voltage / constant current charging, which is a plurality of setting values determined from two parameters of temperature and remaining capacity, or temperature and voltage, regarding an initial setting value of a charging current value at the start of charging. Setting current value that decreases when the maximum setting voltage is exceeded,
The method for charging an assembled battery according to claim 1, wherein the initial setting value of the charging current value at the start of charging is set from the same value.   The assembled battery charging method according to claim 1, wherein when any one of the battery cell voltages exceeds the maximum set voltage, the set current for charging the assembled battery is decreased at a specific rate.   When any of the battery cell voltages exceeds the maximum set voltage, the set current for charging the assembled battery is reduced, and the ratio of the set current is reduced by adding the voltage value of each battery cell and the per-cell voltage. The method for charging an assembled battery according to claim 1, wherein the battery is specified from a difference voltage from a voltage obtained by multiplying the maximum set voltage in series with the number of cells connected in series, and when the difference voltage is large, the ratio of decreasing the set current is increased. If any of the battery cell voltages exceeds the maximum set voltage, the set current for charging the battery pack is reduced, and the rate at which the set current is reduced is specified from the internal resistance of the battery cell that exceeds the maximum set voltage, and the battery The method for charging an assembled battery according to claim 1, wherein the ratio of decreasing the set current is increased when the internal resistance of the cell is large.   The method for charging an assembled battery according to claim 1, wherein the maximum set voltage is changed by the temperature of the battery.   The method for charging an assembled battery according to claim 1, wherein the set current is changed by the temperature of the battery.   The assembled battery charging method according to claim 7, wherein the set current to be reduced is a set current set in multiple stages. When the voltage of each battery cell is detected at a predetermined sampling period and one of the battery cell voltages exceeds a preset maximum set voltage,
The method for charging an assembled battery according to claim 1, wherein constant voltage / constant current charging is performed to reduce charging power for charging the assembled battery with an output from an operational amplifier that compares the reference voltage and the battery cell voltage. The output of the operational amplifier to which the battery cell voltage on the positive side is input,
The assembled battery charging method according to claim 9, wherein charging power for charging the assembled battery is reduced by an output of an OR circuit to which an output of an operation amplifier to which a negative battery cell voltage is input is input.

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