JP2009165303A - Controller for battery circuit, charging controller, electronic equipment using it and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To relax the effect of a detection error, and to charge a secondary battery with a protective circuit up to a desired charging state when the secondary battery is charged. <P>SOLUTION: A controller controls a battery circuit containing a voltage detecting section detecting a battery voltage, the battery protective circuit stopping a charging current when the battery voltage detected by the voltage detecting section exceeds a protective voltage and a charging circuit capable of changing the charging current at the time when the battery is charged. The controller has an input interface reading the battery voltage detected by the voltage detecting section, a decision section deciding whether or not the read battery voltage approaches up to a specified limit at the protective voltage and an output interface outputting a signal controlling the charging current. The controller further has a current control section limiting the charging current at the specified level through the output interface when the battery voltage approaches the specified limit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a battery charge control technique.

  A secondary battery with an upper limit of the charging voltage is provided with a protection circuit that monitors the battery voltage so that the battery does not become overcharged and stops charging when the battery voltage exceeds the upper limit voltage. .

The secondary battery is charged by a charging circuit. The charging circuit is a constant current constant voltage circuit and can control the charging current and the charging voltage. In this case, control is performed so that the charging voltage does not exceed a predetermined upper limit voltage.
JP 2003-307555 A JP-A-6-233468

  However, there is an error in monitoring the battery voltage in the protection circuit and monitoring the charging voltage in the charging circuit. Therefore, although the state of charge is not fully charged, charging may be stopped due to an error between the protection circuit and the charging circuit, and sufficient charging may not be possible.

  An object of the present invention is to provide a secondary battery control technique capable of reducing the influence of the detection error as described above and charging to a desired charged state when charging a secondary battery having a protection circuit. is there.

  In order to solve the above problems, the present invention employs the following configuration. Here, the voltage detection unit that detects the battery voltage, the battery protection circuit that stops the charging current when the battery voltage detected by the voltage detection unit exceeds the protection voltage, and the charging current when charging the battery can be changed A battery circuit control device including a simple charging circuit will be described. Here, the control device controls the charging current, the input interface that reads the battery voltage detected by the voltage detection unit, the determination unit that determines whether or not the read battery voltage is close to the protection voltage to a predetermined limit. An output interface that outputs a signal; and a current control unit that limits the charging current to a predetermined limit through the output interface when it is determined that the signal is close.

  With such a configuration, when the battery voltage is close to the protection voltage, the charging current is limited, and the situation where the battery voltage exceeds the protection voltage and the charging current is stopped can be avoided as much as possible.

Here, the battery includes a plurality of cell blocks each including one cell block or a plurality of cells connected in series, and the voltage detection unit may include a measurement circuit that detects the voltage of each cell block. Good. As a result, the determination unit determines whether the voltage of any cell block is close to a predetermined limit to the protection voltage of the cell block, and the current control unit determines whether the voltage of any cell block is When it is determined that the limit is close to the protection voltage of the block, the charging current may be limited. With such a configuration, it can be determined for each cell block whether or not the voltage is close to a predetermined limit to the protection voltage of the cell block. That is, whether or not the charging current should be limited can be determined from the voltage of each cell block rather than the entire battery.

  In addition, a voltage detection unit for detecting the battery voltage, a battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds the protection voltage, and the charging current for charging the battery can be changed. Another aspect of the battery circuit control device including the charging circuit includes an input interface for inputting a signal indicating an operation state of the battery protection circuit, an output interface for outputting a signal for controlling the charging current, and the battery protection circuit. A protection state determination unit that determines whether or not the charging current is stopped, a voltage state determination unit that determines whether or not the battery voltage has reached the protection voltage after the battery protection circuit stops the charging current, and a battery When the voltage does not reach the protection voltage, the battery protection circuit cancels the charging current stop, and the charging is limited to the specified limit through the output interface. A charge control unit for opening, may be those comprising a. That is, once the battery protection circuit has stopped charging current, if the battery voltage has not reached the protection voltage, the battery protection circuit cancels the suspension of charging current and limits the charging current through the output interface. The charging to the battery can be continued as much as possible by restricting to the above and restarting the charging.

  Moreover, another aspect is good also as a charge control apparatus which combined the said control apparatus and the battery circuit. Moreover, another aspect is good also as an electronic device which combined the battery, the charge control apparatus, and the load.

  ADVANTAGE OF THE INVENTION According to this invention, when charging the secondary battery provided with the protection circuit, the influence of the above detection errors can be relieve | moderated and possibility to charge to a desired charge state can be improved.

  Hereinafter, a charging circuit for a secondary battery and an electronic apparatus using the charging circuit according to the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings. The configuration of the following embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

<< First Embodiment >>
Hereinafter, the charging circuit and the electronic device will be described with reference to FIGS. 1 to 9. FIG. 1 is a diagram illustrating a hardware configuration of the electronic apparatus. This electronic device is a portable device such as a notebook (or laptop) personal computer, portable information terminal, mobile phone, portable game machine, electronic dictionary, portable music player, portable video player. Portable television receivers, portable radios and the like.

  The electronic device includes a battery pack 1 and a main body 2 that is connected to the battery pack 1 and receives power supply from the battery pack 1. As a form of the battery pack 1, the battery pack 1 may be built in the main body 2 or externally attached to the main body 2. The main body 2 can also be supplied with power from a commercial AC power source through the AC adapter 3.

  The battery pack 1 (corresponding to a battery) includes a plurality of battery cells 11-1 to 11-4. In this example, battery cells 11-1 and 11-2 are coupled in parallel to form a battery cell block BLK1. Further, the battery cells 11-3 and 11-4 are coupled in parallel to constitute the battery cell block BLK2. Further, the battery cell blocks BLK1 and BLK2 are connected in series.

However, although the battery cells 11-1 to 11-4 are shown in FIG. 1, the number of battery cells is not limited to four. Further, the battery cell block is not limited to two battery cells. A battery cell block may be configured by connecting three or more battery cells in series or in parallel. Moreover, you may comprise a battery pack by connecting three or more battery cell blocks in series or in parallel. Hereinafter, when battery cells are collectively referred to, they are simply referred to as battery cells 11.

  The battery cell 11 of the battery pack 1 is supplied with electric power from an external terminal through the switch S12 and the current sense resistor 15, and is charged. The switch 12 is a semiconductor switch such as a transistor, for example.

  The switch 12 is switched to an on or off state by a control signal of the protection circuit 13 (corresponding to a battery protection circuit). The protection circuit 13 is supplied with a digital signal from an A / D converter 14 (corresponding to a voltage detection unit) that detects the voltage of the battery cell 11. Here, the battery voltage (the potential at the point A1 in FIG. 1) in which the cell blocks BLK1 and BLK2 are connected in series is A / D converted and transmitted to the protection circuit 13.

  The protection circuit 13 compares the battery voltage from the A / D converter 14 with a predetermined reference value (hereinafter referred to as a protection voltage), and outputs a signal for turning on or off the switch 12. The protection circuit 13 may be composed of a microcomputer and a control program. However, a switch that simply compares the analog signal (voltage before A / D conversion) that is the voltage value at point A1 in FIG. 1 with an analog reference voltage, and the switch 12 is turned on or off by the output signal of the comparator. You may comprise by the circuit to make. In any case, the protection circuit 13 turns off the switch 12 when the voltage of any cell (cell block) of the battery pack 1 configured by combining the battery cells 11 in series and parallel reaches a predetermined protection voltage. . Therefore, the protection circuit 13 prevents the battery cell 11 from being charged excessively. This process is called an overcharge protection process.

The A / D converter 14 performs A / D conversion on the voltage of each battery cell block in addition to the A1 point, and transmits the voltage to the main body 2 through the I2C bus. Further, the current sense resistor 15 generates a voltage drop proportional to the charging current. The A / D converter 14 also A / D converts the voltage at both ends of the current sense resistor 15 and transmits it to the main body 2 through the I2C bus. The I2C bus is a serial interface bus. In the present embodiment, the I ² C bus is referred to as an I2C bus. In this charging circuit, the configuration using the I2C bus is illustrated, but the connection between the main body 2 and the A / D converter 14 is not limited to the I2C bus.

  The main body 2 includes a load 20 and a power control unit 4 that controls the power supplied to the load 20 and the power for charging the battery pack 1. Further, the power supply control unit 4 includes a power supply circuit 21 that supplies power to the load 20, a charging circuit 23 that charges the battery pack 1, and a microcomputer 22 that controls the power supply circuit 21 and the charging circuit 23.

  The load 20 is a main part that realizes the function of the electronic device. The power supply circuit 21 is a so-called constant voltage circuit, for example, a DCDC converter. The power supply circuit 21 converts the voltage from the battery pack 1 or the voltage from the AC adapter 3 into a specified voltage of the load 20.

  The charging circuit 23 is a constant voltage constant current circuit, and charges the battery pack 1 with power from the AC adapter 3 in accordance with a control signal from the microcomputer 22. In the example of FIG. 1, the control signal from the microcomputer 22 is an analog signal that has been D / A converted by the D / A converter.

The microcomputer 22 (corresponding to the control device) includes a CPU (not shown), a memory, an interface such as I2C (corresponding to an input interface), a D / A converter and its output terminal (
Equivalent to an output interface). The CPU of the microcomputer 22 executes a program on the memory and generates control signals for the power supply circuit 21 and the charging circuit 23. For example, the microcomputer 22 monitors the voltage of each part of the battery cell 11 (cell blocks such as A1 point and A2 point, current sense resistor 15 and the like) through a circuit (corresponding to a measurement circuit) connected to the I2C bus. Then, the voltage and current for charging the battery pack 1 are controlled through the charging circuit 23 in accordance with the monitored voltage.

  Further, the microcomputer 22 can input an on / off signal to the on / off input terminal of the protection circuit 13 to switch the switch 12 to an off state. In the on state, the protection circuit 13 executes the above-described overcharge protection process. On the other hand, in the off state, the switch 12 remains off regardless of the state of the overcharge protection processing of the protection circuit 13.

  Incidentally, a so-called hysteresis is set for the determination of overcharge in the overcharge protection process of the protection circuit 13. For example, when the charging voltage reaches 4.25 volts, the switch 12 is turned off and the overcharge protection process is activated. In this case, the overcharge protection process does not stop until the charging voltage reaches 4.20, and the switch 12 remains off. Then, the charging voltage becomes 4.20 volts or less, the overcharge protection process is stopped, and the switch 12 is turned on. Therefore, there is a hysteresis of 0.05 volts in this example between the charging voltage of 4.25 volts for determining the start of the overcharge protection process and the charging voltage of 4.20 volts for determining the end of the overcharge protection process.

  In the present embodiment, when the microcomputer 22 turns off the on / off input terminal of the protection circuit 13, the protection circuit 13 turns off the switch 12 as it is. At this time, the protection circuit 13 operates without hysteresis (however, the switch 12 is kept off). Furthermore, when the microcomputer 22 turns off the protection circuit 13 and then turns it on, the protection circuit 13 performs an operation of turning on or off the switch 12 according to the voltage of the cell block in a state where there is no hysteresis. Will resume. Once the switch 12 is turned on, the hysteresis is formed.

  FIG. 2 illustrates a block diagram of the charging circuit 23. The charging circuit 23 receives a setting from the microcomputer 22 and controls the charging current and the charging voltage. The charging control device 231 controls the charging current and the charging voltage. The charging control device 231 switches the on state and the off state. A coil 234 that generates an electromotive force according to a pulse waveform generated by 233, and a current sense resistor 235 that receives an output from the coil 234 and generates a voltage drop proportional to the current passing therethrough. Although omitted in FIG. 2, a capacitor connecting the node between the coil 234 and the current sense resistor 235 and the ground may be provided.

  The FETs 232 and 233 and the coil 234 as described above form a DCDC converter (synchronous rectifier circuit). The output voltage or output current of the DCDC converter is determined by the duty ratio of the pulse signal that causes the charge control device 231 to turn on or off the FETs 232 and 233.

  The charging control device 231 is provided with a charging current setting input terminal 236 and a charging voltage setting input terminal 237. The microcomputer 22 in FIG. 1 supplies a reference voltage to the charging current setting input terminal 236 through a D / A converter. 1 supplies a reference voltage to the charge voltage setting input terminal 237 through a D / A converter.

The charge control device 231 compares the voltage across the current sense resistor 235 with the reference voltage of the charge current setting input terminal 236 and controls the pulse signals to the FETs 232 and 233. That is, the charging control device 231 controls the duty ratio of the pulse signal by applying negative feedback in a direction in which the difference between the voltage across the current sense resistor 235 and the reference voltage is reduced.

  In addition, the charging control device 231 includes a potential between the current sense resistor 235 and the battery pack 1 (point C) (that is, a voltage between the point C and the ground), and a reference voltage 237 at the charging voltage setting input terminal. To control the pulse signal to the FETs 232 and 233. That is, the charging control device 231 controls the pulse signal by applying negative feedback in a direction in which the difference between the potential at the entrance (point C) of the battery pack 1 and the reference voltage is reduced.

  FIG. 3 illustrates the operation of the charge control device 231. The charging control device 231 controls the charging current and charging voltage of the battery by specifying the target voltage and target current from the outside. As shown in FIG. 3, the control of the charging control device 231 executes a sequence by dividing the time axis into a constant current region and a constant voltage region. First, at the start of charging, before a sufficient charge is accumulated in the battery pack 1, the charging control device 231 uses the FETs 232 and 233 so that the voltage drop across the current sense resistor 235 becomes the charging current setting input value. Controls the duty ratio of the pulse. As a result, charging is performed at a constant current from the beginning of charging until the battery voltage reaches a predetermined limit. Since the battery is charged with a constant current, the charge voltage increases as the charge is stored in the battery.

  On the other hand, when the battery pack 1 is charged to a predetermined degree, the charge control device 231 controls charging in the constant voltage control region. In this case, the charging control device 231 controls the duty ratio of the pulses by the FETs 232 and 233 so that the voltage at the point C that is the entrance of the battery pack becomes the charging voltage setting value. As a result, in this state, the charging current gradually decreases. That is, since charge is accumulated in the battery at a constant voltage, the voltage drop proportional to the internal resistance, and thus the charging current gradually decreases.

<Conventional problems>
FIG. 4 shows a conventional control sequence by the microcomputer 22. This process is realized by a control program executed by the microcomputer 22. In this process, the microcomputer 22 first starts charging (S501). Charging starts, for example, when power is supplied from the AC adapter 3. The microcomputer 22 executes the following steps.

  That is, the microcomputer 22 acquires the terminal voltage of the battery pack 1 corresponding to the point B in FIG. Further, the microcomputer 22 detects the charging current from the current sense resistor 235 of FIG. 2 (S502). Then, the microcomputer 22 predicts the remaining battery level from the terminal voltage of the battery pack 1 and the charging current (S504). For example, the remaining battery level can be predicted by tabulating the terminal voltage value of the battery pack 1, the charging current value, and the ratio of the charge amount to the full charge at that time, and storing it in the memory of the microcomputer 22. Just keep it. Alternatively, an empirical formula indicating the relationship between the terminal voltage value of the battery pack 1, the charging current value, and the ratio of the charge amount to the full charge at that time may be incorporated in the control program of the microcomputer 22.

  Then, the microcomputer 22 determines whether or not the battery is fully charged (S504). If not fully charged, the microcomputer 22 returns the control to S502. On the other hand, if the battery is fully charged, the microcomputer 22 stops charging (S505).

However, this procedure has the following problems. As described in FIG. 2, the current control circuit 231 controls the charging current and the charging voltage at the point C in FIG. 2 (corresponding to the point B in FIG. 1). On the other hand, the battery pack 1 is provided with a protection circuit 13 to monitor the voltage of the battery cell 11. When the voltage of the battery cell 11, for example, the voltage at the point A <b> 1 in FIG. 1 reaches the limit value, the protection circuit 13 shuts off the switch 12. This process is called overcharge protection operation. In this case, the charging voltage measured at point C (point B in FIG. 1) and input to the current control circuit 231 has a measurement error. Further, the voltage measured at the point A1 in FIG. 1 and inputted to the protection circuit 13 also has a measurement error. Therefore, even if the microcomputer 22 correctly specifies the charging voltage and charging current to the current control circuit 231, as a result of these measurement errors, the current control circuit 231 does not sufficiently bring the charging state close to full charge. In some cases, charging may be stopped by the protection circuit 13.

  For example, there is an error of -0.05 volts to 0.05 volts for a charging voltage of 4.2 volts for the cell voltage. On the other hand, for example, when the protection circuit 13 has an error of −0.03 volts to 0.03 volts, the overcharge protection is performed at 4.28 volts or more obtained by adding 0.03 volts to the upper limit voltage 4.25 of the charging circuit 23. If the operation is not performed, charging may stop in the middle.

  Conversely, if the protection circuit 13 stops charging at 4.25 volts, charging may be stopped at the actual charging voltage of 4.22 volts. Therefore, the charging circuit 23 tries to charge at a charging voltage of 4.25 volts with the cell voltage taken into account, and is forcibly stopped at 4.22 volts, and does not reach full charge.

<Example of change in current and voltage during charging>
FIG. 5 shows an example of the charging voltage, the remaining amount of charge, and the change over time of the charging current when charging is performed at a charging voltage of 4.25 volts when there is no protection by the protection circuit 13. In this case, the battery is charged with a constant current until the charging voltage reaches 4.25 volts. When the charging voltage reaches 4.25 volts (time T0), the charging circuit 23 operates in the constant voltage control region, and the charging current is gradually reduced while being charged until it is fully charged.

  FIG. 6 shows an example of the change over time of the charging voltage, the remaining amount of charge, and the charging current when the protection of the protection circuit 13 is activated. Here, for example, it is assumed that there is an error of 0.03 volts in the cell voltage measurement of the protection circuit 13 and the protection circuit 13 is operated at the charging voltage 4.22 (time T1).

  Then, the switch 12 is cut off by the protection circuit 13 and the charging current becomes zero. Even if the charge voltage is 4.22 before the switch 12 is turned off, the charge voltage, and thus the terminal voltage of the battery pack 1, is lowered by a certain value due to the switch 12 being turned off. The decrease value of the terminal voltage can be represented by a product I × R0 of the charging current I and the internal resistance R0 of the battery pack 1. Accordingly, the terminal voltage is reduced by the measurement error ΔV of the protection circuit 13 and the voltage drop I × R0 due to the internal resistance R0, and the charging state is fully charged, compared with the charging voltage that the charging circuit 13 originally intended to charge. On the other hand, the shortage amount ΔQ is insufficient. The supplyable time from the battery pack 1 to the load 20 is shortened by the shortage.

  FIG. 7 illustrates a change in current voltage during charging control through the charging circuit 23 by the microcomputer 22 of the present embodiment. As shown in FIG. 1, the microcomputer 22 monitors the potential of each part of the battery cell 11 (for example, the potential at the points A1 and A2) through the I2C bus. For example, when the potential at the entrance (point A1) of the cell block BLK1 reaches a predetermined value, for example, 4.2 volts (time T2), the microcomputer 22 transfers to the charging current setting input terminal 236 of the charging circuit 23. Is changed, and the charging current is decreased with time.

As a result, the voltage drop I × R0 due to the internal resistance R0 of the battery pack 1 decreases as the charging current decreases. Therefore, as shown in FIG. 7, the charging voltage decreases after the voltage exceeds 4.2 volts. Therefore, the charging voltage does not reach 4.22 volts. As a result, the charging current continues without the protection by the protection circuit 13 being activated. That is, charging is continued with a weaker charging current than in the case of FIG. 6, and the state of charge can be charged to a higher state of charge than when protection by the protection circuit 13 operates as shown in FIG.

  FIG. 8 illustrates charge control processing by the microcomputer 22. In this procedure, first, the microcomputer 22 sets a reference voltage for controlling the constant current value at the charging current setting input terminal 236 and sets a reference voltage for controlling the constant voltage value at the charging voltage setting input terminal 237. To do. Thereby, the microcomputer 22 commands the charging control device 231 to start charging (S1).

  Next, the microcomputer 22 detects the value of the charging current from the voltage across the current sense resistor 15 (see FIG. 1). Further, the microcomputer 22 detects a voltage (voltage between the ground and the point A1 in FIG. 1) in which the cell blocks BLK1 and BLK2 detected by the A / D converter 13 are connected in series through the I2C bus. (S2).

  Then, the microcomputer 22 predicts the remaining battery level (S3). As described above, the remaining battery level is a table storing the charging current value, the charging voltage of the battery pack 1 (the voltage at point A1 in FIG. 1), and the remaining battery level, or the charging current value. And a computer program according to an empirical formula for calculating the remaining battery capacity from the charging voltage of the battery pack 1.

  Next, the microcomputer 22 detects the voltages of the cell blocks BLK1 and BLK2 detected by the A / D converter 13 (the voltage between the points A1 and A2, and the voltage between the point A2 and the ground). Is acquired (S4).

  Next, the microcomputer 22 determines whether or not the voltage of any of the cell blocks BLK1 and BLK2 is equal to or higher than a specified value (S5). The microcomputer 22 that executes this process corresponds to a determination unit.

  Here, the specified voltage is made lower by a predetermined value than the protection voltage at which the protection circuit 13 turns off the switch 12. For example, the protection voltage is 4.25 volts as shown in FIG. 7, and the specified voltage is 4.2 volts. The specified voltage of 4.2 volts may be determined experimentally with a value sufficient to suppress the generation of the protection circuit 13 by reducing the current with respect to the protection voltage of 4.25 volts. If any cell block is equal to or greater than the specified value, the microcomputer 22 executes a charging current reduction control process (S6). The microcomputer 22 that executes this process corresponds to a current limiting unit.

  Then, the microcomputer 22 determines whether or not the battery is fully charged (S7). If not fully charged, the microcomputer 22 returns the control to S2. On the other hand, in the case of full charge, the microcomputer 22 stops the pulse waveform generation operation in the charging circuit 23. Further, the FET 232 and the FET 233 in FIG. 2 are turned off. Further, the switch 12 is turned off. Further, the settings of the charging current setting input terminal 236 and the charging voltage setting input terminal 237 are cleared. Thereby, the microcomputer 22 stops charging (S8).

  FIG. 9 shows details of the charging current reduction control process (S6 in FIG. 8). In this process, the microcomputer 22 detects the charging voltage V1 (S61). That is, the microcomputer 22 acquires the digital value generated from the terminal voltage of the battery pack 1 (the potential at the point A1 in FIG. 1) by the A / D converter 14 in FIG. 1 through the I2C bus.

  Next, the microcomputer 22 calculates a difference ΔV between the protection voltage and the detected charging voltage V1 (S62). Further, the microcomputer 22 calculates a limit current value (ΔV / R0) obtained by dividing the difference ΔV by the internal resistance value R0. Then, the current value I1 is determined within a range of values smaller than the limit current value (S63). The current value I1 may be, for example, the limit current value itself or a value obtained by multiplying a predetermined safety coefficient (for example, 0.9). Then, the microcomputer 22 sets a reference voltage at the charging current setting input terminal 236 that should control the charging current to I1 (S64). As a result, the charging current is controlled to I1. Therefore, the charging voltage V1 does not exceed the protection voltage due to the voltage increase due to the charging current. And the microcomputer 22 complete | finishes a process and advances control to S7 of FIG. The processing from S61 to S64 is repeated in the loop of S2-S7 in FIG. As a result, the current value I1 gradually decreases as the state of charge progresses. The current value I1 is determined according to the difference ΔV between the protection voltage and the detected charging voltage V1.

  As described above, according to the charging circuit of the present embodiment, when the terminal voltage of the battery pack 1 exceeds a predetermined specified value, the charging current is reduced so that the charging voltage does not reach the protection voltage. . Therefore, the charging by the charging circuit 23 can be continued without the switch 12 being turned off by the protection circuit 13. Then, the charging voltage approaches the protection voltage, and the charging current gradually decreases by the process of S63 (FIG. 9). Therefore, the battery pack 1 can be charged to near full charge without activating the protection circuit 13.

  Further, in the present embodiment, the detection of the charging voltage is detected by the A / D converter 13. The charging voltage detected by the A / D converter 13 is used in common by the protection circuit 13 and the microcomputer 22. Therefore, it is possible to reduce the occurrence of measurement error discrepancy between the protection circuit 13 and the microcomputer 22.

<Modification>
In the first embodiment, as shown in FIG. 9, charging is performed so that the increase in charging voltage due to the charging current I1 and the internal resistance R0 does not exceed the difference ΔV between the protection voltage and the detected charging voltage V1. The current I1 was decreased.

  However, for example, when the time lapse of the charging voltage increase during charging is known in advance from experimental results and experience values, the charging current may be simply decreased with time. FIG. 10 shows control in such a case. In this example, it is assumed that the charging voltage has reached a specified voltage at time T2. In that case, the microcomputer 22 decreases the charging current step by step as time passes, as shown in FIG. What is necessary is just to make the grade to reduce rather than the time passage of the raise of charging voltage. What is necessary is just to memorize | store in the memory of the microcomputer 22 what was measured experimentally beforehand about the time passage of the raise of a charging voltage. Or you may memorize | store the variation | change_quantity per unit time which reduces such a charging current in the memory of the microcomputer 22. FIG.

  Conversely, as shown in FIG. 11, when the charging voltage reaches a specified voltage at time T <b> 2, the charging current may be greatly decreased until the charging current approaches zero. Then, the charging current may be gradually increased with time. However, in that case, the charging current may be increased stepwise within a range that does not exceed the difference ΔV between the protection voltage and the detected charging voltage V1 due to the charging current.

In the said embodiment, when the charging voltage exceeded the regulation voltage and approached the protection voltage, the process which reduces charging current to the range which the protection circuit 13 does not operate | move and continued charging was demonstrated. In this case, once the overcharge protection processing of the protection circuit 13 functions and the switch 12 is turned off, the switch 12 is not turned on due to the hysteresis characteristic until the charging voltage is lowered to a predetermined limit. Therefore, even if the overcharge protection process is executed once, the microcomputer 22 monitors the voltages of the cell blocks BLK1 and BLK2, and when the charge voltage drops from the protection voltage, the protection circuit 13 is reset and the hysteresis characteristic is set. You may make it return to an initial state.

  FIG. 12 shows reset processing of the protection circuit 13 by the microcomputer 22. This process is executed after the overcharge protection process of the protection circuit 13 is activated. Whether or not the overcharge protection processing of the protection circuit 13 has been activated can be determined by, for example, the microcomputer 22 reading a register value indicating the status of the protection circuit via the I2C bus. Further, for example, the charging current may be detected through the current sense resistor 15. That is, when charging is performed at a constant current / constant voltage through the charging circuit 23 as shown in FIG. 6 but the charging current is extremely small (for example, a value equal to or less than the leakage current of the switch 12). ), It may be determined that the overcharge protection processing of the protection circuit 13 has started.

  In this process, the microcomputer 22 acquires the voltages of the cell blocks BLK1 and BLK2 through the I2C bus (S11).

  Then, the microcomputer 22 determines whether any cell block voltage is equal to or higher than the protection voltage (S12). The microcomputer 22 that executes this process corresponds to a state determination unit. If any of the cell block voltages is equal to or higher than the protection voltage, the microcomputer 22 returns the control to S11.

  On the other hand, when all the cell block voltages are less than the protection voltage, the microcomputer 22 first turns off the protection circuit 13 (S13). As a result, the protection circuit 13 stops processing, and the switch 12 is temporarily turned on. At this time, the protection circuit 13 stops the comparison process between the voltages of the cell blocks BLK1, BLK2, etc. and the protection voltage, and sets the switch 12 to ON.

  Next, the microcomputer 22 turns on the protection circuit 13 (S14). Thereby, the protection circuit 13 starts the comparison process between the voltages of the cell blocks BLK1, BLK2, etc. and the protection voltage from the beginning. As a result, in a state without hysteresis, the voltages of the cell blocks BLK1, BLK2, etc. are compared with the protection voltage, and the overcharge protection process is executed from the beginning. The microcomputer 22 that executes the processes of S13 and S14 corresponds to a release unit.

  As described above, once the protection circuit 13 is turned off and then turned on, the hysteresis of the overcharge protection processing can be initialized and re-executed. Therefore, it is possible to avoid a situation in which the charging current is not supplied again even if the charging voltage is lowered after the overcharge protection is activated once due to the effect of hysteresis.

<< Second Embodiment >>
FIG. 13 illustrates a detailed configuration example of an electronic device. The electronic device is supplied with power to the main body 2 through the AC adapter 3. The main body 2 has a battery pack 1, a power supply control circuit 4, and a load 20.

  The load 20 includes a CPU 111 that executes a program, a memory 112 that stores a program executed by the CPU 111, or data processed by the CPU 111, and a keyboard 114A and a pointing device 114B that are connected to the CPU 111 via an interface 113. Have. The pointing device 114B is a mouse, a trackball, a touch panel, a flat device having an electrostatic sensor, or the like.

  The load 20 also has a display 116 connected through the interface 115. The display 116 displays information input from the keyboard 114A or data processed by the CPU 111. The display 116 is, for example, a liquid crystal display or an EL (electroluminescence) panel.

  The load 20 includes a communication unit 118 connected via an interface 117. The communication unit 118 is a LAN (local area network) board, a wireless communication interface (including an antenna), a wireless reception unit (including an antenna), or the like.

  The load 20 includes an external storage device 210 connected via the interface 119. The external storage device 120 is, for example, a hard disk drive. Further, the main body 101 has a removable storage medium access device 22 connected via an interface 121. The removable storage medium is, for example, a CD (Compact disc), a DVD (Digital Versatile Disk), a flash memory card, or the like.

  As such an electronic device, this electronic device is a portable device such as a laptop (or laptop) personal computer, a portable information terminal, a mobile phone, a portable game machine, an electronic dictionary, a portable Type music player, portable video player, portable television receiver, portable radio and the like.

  As described above, the voltage of the cell block referred to by the protection circuit 13 is transmitted to the microcomputer 22 through the I2C bus. The microcomputer 22 controls the charging circuit 23 based on the transmitted cell block voltage. With such a configuration, the battery pack 1 can be charged to a voltage very close to the protection voltage. As a result, the electronic device can be used for a long time using the battery pack 1.

<< Third Embodiment >>
In the first embodiment, it is determined whether or not the voltage of one of the cell blocks BLK1 and BLK2 is equal to or higher than a specified value, and when those voltages are equal to or higher than a specified value, the charging current reduction process is executed. Thus, the charging circuit and the electronic device that suppress the charging current in a range in which the protection circuit 13 does not activate the overcharge protection process and continue the charging to near full charge have been described.

  In this embodiment, instead of such control, it is detected whether or not the protection circuit 13 has started the overcharge protection process, and when the protection circuit 13 has started the overcharge protection process, the charging current is reduced. Then, control is performed so that the overcharge protection process is not executed. According to such a procedure, as in the first embodiment, charging can be continued to near full charge. Other configurations and operations are the same as those in the first embodiment. Therefore, the same components are denoted by the same reference numerals and the description thereof is omitted. Further, the drawings in FIGS. 1 to 13 are referred to as necessary. Needless to say, the overcharge protection circuit according to the control of the present embodiment can also be applied to the electronic apparatus of the second embodiment shown in FIG.

  FIG. 14 shows reset processing of the protection circuit 13 by the microcomputer 22. The microcomputer 22 usually acquires the voltages and charging currents of the cell blocks BLK1 and BLK2 through the I2C bus (S102). The voltages of the cell blocks BLK1 and BLK2 are acquired through the A / D converter 14. The charging current is also acquired based on the voltage across the current sense resistor 15 through the A / D converter 14.

Then, the microcomputer 22 predicts the remaining battery level, that is, the state of charge of the battery (S103). The state of charge refers to the current state of charge of the cell relative to full charge. Then, the microcomputer 22 determines whether or not the battery is fully charged (S104). If it is predicted that the battery is fully charged, the microcomputer 22 returns the control to S102 and continues to monitor the voltage and current. That is, the microcomputer 22 thereafter monitors the change in the state of charge of the battery pack accompanying the discharge.

  On the other hand, when it is determined in S104 that the battery is not fully charged, the microcomputer 22 acquires the overcharge protection state of the protection circuit 13 (S105). The overcharge protection state of the protection circuit 13 refers to a state of whether or not the overcharge protection process of the protection circuit 13 is activated and the charging current is interrupted. Whether or not the overcharge protection processing of the protection circuit 13 is activated can be determined, for example, by the microcomputer 22 reading a register value indicating the status of the protection circuit 13 through the I2C bus. Further, for example, the charging current may be detected through the current sense resistor 15. That is, when charging is performed at a constant current / constant voltage through the charging circuit 23 as shown in FIG. 6 but the charging current is extremely small (for example, a value equal to or less than the leakage current of the switch 12). ), It may be determined that the overcharge protection processing of the protection circuit 13 has started.

  Then, the microcomputer 22 determines whether or not the charging is stopped by the overcharge protection process (S106). The microcomputer 22 that executes this processing corresponds to a protection state determination unit. Then, when charging is stopped by the overcharge protection process, the microcomputer 22 resets the overcharge protection process as in S13 and S14 of FIG.

  Here, first, the microcomputer 22 reads the voltage of each cell block through the I2C bus, and determines whether the voltage of any cell block is equal to or higher than the protection voltage (S107). The microcomputer 22 that executes this process corresponds to a voltage state determination unit. If the voltage of any cell block is equal to or higher than the protection voltage (NO in S108), the microcomputer 22 returns the control to S102.

  On the other hand, when the voltages of all the cell blocks are less than the protection voltage (YES in S108), the microcomputer 22 cancels the overcharge protection process (S109) and sets the charging current to a predetermined value, for example, a constant current. The charging current is set to about ½ of the charging current (S110). The microcomputer 22 that executes the processes of S109 and S110 corresponds to a charge control unit. In addition, the charging by a constant current was demonstrated with the constant current of FIG.

  On the other hand, when charging is not stopped by the overcharge protection process, the microcomputer 22 sets the charging current to the maximum. Then, the microcomputer 22 starts charging (S112). Then, the microcomputer 22 acquires the voltages and charging currents of the cell blocks BLK1 and BLK2 through the I2C bus (S120). Then, the microcomputer 22 determines whether or not the charging current is stopped (S121). If the charging current is stopped, the microcomputer 22 stops the charging control (S124), and returns the control to S102. Here, the cause of the stop of the charging current is, for example, overcharge similar to S106, detection of abnormality (for example, heating) of the battery cell 11, abnormality in the balance of the voltage between the battery cells 11 and 11, etc. There is. For example, this is a case where the temperature of the battery cell 11 exceeds a predetermined limit due to heating. In addition, any of the battery cells 11 connected in series has an extremely low voltage compared to the other battery cells 11. Here, in the case of overcharging, since it is protection by the overcharge protection circuit 13 after limiting the charging current in S110, the microcomputer 22 determines that the charging current may be stopped. Furthermore, in the case of an abnormality in the battery cell 11, since it is difficult to continue charging, the microcomputer 22 stops the charging current.

On the other hand, when charging is not stopped by the overcharge protection process, the microcomputer 2
2 predicts the remaining battery level (S122). Then, the microcomputer 22 determines whether or not the battery is fully charged (S123). When it is predicted that the battery is fully charged, the microcomputer 22 stops the charging control (S124), returns the control to S102, and continues to monitor the voltage and current.

  On the other hand, if it is determined in S123 that the battery is not fully charged, the microcomputer 22 returns the control to S120 and continues the process.

  As described above, in the charging circuit according to the present embodiment and an electronic device equipped with such a charging circuit, it is determined whether or not the charging current is interrupted by the overcharge protection process of the protection circuit 13. Furthermore, when the charging current is interrupted by the overcharge protection process, it is determined whether the voltage of the cell block is equal to or higher than the protection voltage. When the cell block voltage is lower than the protection voltage, the protection circuit 13 is reset and the voltage drop due to the charging current is sufficiently small so that the cell block voltage does not reach the protection voltage. Charging is restarted with a current value (for example, in the case of FIG. 14 described above, a current value that is ½ of charging with a normal constant current). That is, according to the process of the present embodiment, unlike the case of the first embodiment, the overcharge protection process by the protection circuit 13 is temporarily performed instead of executing the charge current reduction process with a specified voltage having a lower protection voltage. After that, additional charging is performed if charging is possible. Also by such a process, a battery cell can be charged to near full charge similarly to 1st Embodiment.

In the third embodiment, in the process of S106, the current value is set to ½ during charging with a normal constant current. However, the processing of the present charging control circuit is not limited to such values. That is, after the overcharge protection process by the protection circuit 13 is once performed, charging may be continued in a sufficiently small charging current range within a chargeable range. Such a range of the charging current may be determined experimentally in advance. For example, it may be determined in advance from the internal resistance value of the battery cell 11.
<Others>
The features of this circuit, this device, this device, and this method will be described below.
(Appendix 1)
A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A charging circuit capable of changing a charging current when charging the battery, and a control device for the battery circuit,
An input interface for reading the battery voltage detected by the voltage detector;
A determination unit for determining whether the read battery voltage is close to a predetermined limit to the protection voltage;
An output interface for outputting a signal for controlling the charging current;
A battery circuit control device comprising: a current control unit that limits the charging current to a predetermined limit through the output interface when it is determined to be close.
(Appendix 2)
The battery has a plurality of cell blocks each including a cell block or a plurality of cells connected in series,
The voltage detection unit has a measurement circuit for detecting the voltage of each cell block,
The determination unit determines whether the voltage of any of the cell blocks is close to a predetermined limit to the protection voltage of the cell block,
The battery controller according to claim 1, wherein the current control unit limits the charging current to the limit when it is determined that the voltage of any cell block is close to the limit of the protection voltage of the cell block. Control device.
(Appendix 3)
A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A charging circuit capable of changing the charging current when charging the battery; and
A control device,
The controller is
An input interface for reading the battery voltage detected by the voltage detector;
A determination unit for determining whether the read battery voltage is close to a predetermined limit to the protection voltage;
An output interface for outputting a signal for controlling the charging current;
And a current control unit configured to limit the charging current to a predetermined limit through the output interface when it is determined to be close.
(Appendix 4)
The battery has a plurality of cell blocks each including a cell block or a plurality of cells connected in series,
The voltage detection unit has a measurement circuit for detecting the voltage of each cell block,
The determination unit determines whether the voltage of any cell block is close to a predetermined limit to the protection voltage of the cell block,
The charge control device according to attachment 3, wherein the current control unit limits the charging current to the limit when it is determined that the voltage of any cell block is close to the limit.
(Appendix 5)
The charge control device according to appendix 3 or 4, wherein the input interface reads a voltage detected by the voltage detection unit through serial communication.
(Appendix 6)
The charging control device according to any one of appendices 3 to 5, wherein the output interface adjusts a charging current by a D / A converter.
(Appendix 7)
The charge control device according to appendix 3, 5 or 6, wherein the current limiting unit decreases the charging current stepwise with time when it is determined that the battery voltage has approached the limit. (Appendix 8)
The current limiting unit decreases the charging current by a first change amount when it is determined that the battery voltage is close to the limit, and further, a second change that is smaller than the first change amount as time passes. The charge control device according to appendix 3, 5 or 6, wherein the charge current is increased stepwise by the amount of change.
(Appendix 9)
The charge control device according to appendix 3, 5 or 6, wherein the current limiting unit decreases a charging current according to a difference between the protection voltage and the battery voltage when it is determined that the battery voltage is close to the limit. .
(Appendix 10)
The charging control device according to appendix 3, 5 or 6, wherein the current limiting unit decreases the charging current as the difference between the battery voltage and the protection voltage decreases.
(Appendix 11)
The current limiting unit is configured to reduce the charging current in a stepwise manner as time elapses when it is determined that the voltage of any cell block is close to a predetermined limit to the protection voltage of the cell block. Charge control device.
(Appendix 12)
The current limiting unit decreases a charging current by a first change amount when it is determined that the voltage of any cell block is close to a predetermined limit to the protection voltage of the cell block, and the current limiting unit decreases with time. The charge control device according to appendix 4 or 11, wherein the charge current is increased stepwise by a second change amount smaller than the first change amount.
(Appendix 13)
The current limiting unit is configured to reduce a charging current according to a difference between the protection voltage and the battery voltage when it is determined that the voltage of any cell block is close to a predetermined limit to the protection voltage of the cell block. The charge control device according to 4, 11, or 12.
(Appendix 14)
14. The charge control device according to appendix 4, 11, 12, or 13, wherein the current limiting unit decreases a charging current as a difference between a voltage of any cell block and a protection voltage of the cell block decreases.
(Appendix 15)
The control device, after the battery protection circuit has stopped the charging current, a state determination unit that determines whether the battery voltage exceeds the protection voltage;
The charging control device according to any one of supplementary notes 3, 5, and 6 to 10, further comprising: a release unit that releases protection by the battery protection circuit when the battery voltage does not exceed the protection voltage.
(Appendix 16)
The control device, after the battery protection circuit stops the charging current, a state determination unit that determines whether the voltage of any of the cell blocks exceeds the protection voltage of the cell block;
The charging control according to any one of appendices 4, 11 to 14, further comprising: a release unit that releases protection by the battery protection circuit when the voltages of all the cell blocks do not exceed the protection voltage of the cell block. apparatus.
(Appendix 17)
A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A charging circuit capable of changing the charging current when charging the battery; and
A control device;
A battery charged through the charging circuit under the control of the control device;
A load that receives power supply from the charged battery,
The controller is
An input interface for reading the battery voltage detected by the voltage detector;
A determination unit for determining whether the read battery voltage is close to a predetermined limit to the protection voltage;
An output interface for outputting a signal for controlling the charging current;
An electronic device comprising: a current control unit that restricts the charging current to a predetermined limit through the output interface when it is determined that the proximity has occurred.
(Appendix 18)
A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A battery circuit control device including a charging circuit capable of changing a charging current when charging the battery,
Reading out the battery voltage detected by the voltage detector through an input interface;
A determination step of determining whether the read battery voltage is close to the protection voltage to a predetermined limit;
And a step of limiting the charging current to a predetermined limit through an output interface when the proximity is determined to be close.
(Appendix 19)
A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A charging circuit capable of changing a charging current when charging the battery, and a control device for the battery circuit,
An input interface for inputting a signal indicating an operation state of the battery protection circuit;
An output interface for outputting a signal for controlling the charging current;
A protection state determination unit that determines whether the battery protection circuit has stopped charging current; and
A voltage state determination unit that determines whether or not the battery voltage has reached the protection voltage after the battery protection circuit has stopped charging current;
When the battery voltage has not reached the protection voltage, the charging control unit releases the suspension of the charging current by the battery protection circuit and restarts charging by limiting the charging current to a predetermined limit through the output interface. And a battery circuit control device.
(Appendix 20)
The battery has a plurality of cell blocks each including a cell block or a plurality of cells connected in series,
The battery protection circuit stops the charging current when the voltage of any of the cell blocks reaches the protection voltage of the cell block,
The voltage detection unit has a measurement circuit for detecting the voltage of each cell block,
The voltage state determination unit determines whether or not the voltage of any of the cell blocks has reached the protection voltage of the cell block after the battery protection circuit has stopped charging current,
The charging control unit cancels the suspension of the charging current by the battery protection circuit and charges the battery by limiting the charging current to the limit when the voltages of all the cell blocks are lower than the protection voltage of the cell block. Item 20. The battery circuit control device according to appendix 19, which resumes the operation.
(Appendix 21)
A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit reaches a protection voltage;
A charging circuit capable of changing the charging current when charging the battery; and
A control device,
The controller is
An input interface for inputting a signal indicating an operation state of the battery protection circuit;
An output interface for outputting a signal for controlling the charging current;
A protection state determination unit that determines whether the battery protection circuit has stopped charging current; and
A voltage state determination unit for determining whether or not the battery voltage has reached a protection voltage after the battery protection circuit has stopped charging current;
When the battery voltage has not reached the protection voltage, the charging control unit releases the suspension of the charging current by the battery protection circuit and restarts charging by limiting the charging current to a predetermined limit through the output interface. A charge control device comprising:
(Appendix 22)
The battery has a plurality of cell blocks each including a cell block or a plurality of cells connected in series,
The battery protection circuit stops the charging current when the voltage of any of the cell blocks reaches the protection voltage of the cell block,
The voltage detection unit has a measurement circuit for detecting the voltage of each cell block,
The voltage state determination unit determines whether the voltage of any of the cell blocks has reached the protection voltage of the cell block after the battery protection circuit has stopped charging current,
The charging control unit cancels the suspension of the charging current by the battery protection circuit and charges the battery by limiting the charging current to the limit when the voltages of all the cell blocks are lower than the protection voltage of the cell block. The charge control device according to appendix 21, wherein the charging is resumed.
(Appendix 23)
A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit reaches a protection voltage;
A charging circuit capable of changing the charging current when charging the battery; and
A control device;
A battery charged through the charging circuit under the control of the control device;
A load that receives power supply from the charged battery,
The controller is
An input interface for inputting a signal indicating an operation state of the battery protection circuit;
An output interface for outputting a signal for controlling the charging current;
A protection state determination unit that determines whether the battery protection circuit has stopped charging current; and
A voltage state determination unit that determines whether or not the battery voltage has reached a protection voltage after the battery protection circuit has stopped charging current;
When the battery voltage does not reach the protection voltage, the charging control unit releases the suspension of the charging current by the battery protection circuit and resumes charging by limiting the charging current to a predetermined limit through the output interface. And an electronic device.
(Appendix 24)
A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit reaches a protection voltage;
A battery circuit control device including a charging circuit capable of changing a charging current when charging the battery,
Inputting a signal indicating an operating state of the battery protection circuit through an input interface;
A protection state determination step for determining whether or not the battery protection circuit has stopped charging current;
A voltage state determination step for determining whether or not the battery voltage has reached a protection voltage after the battery protection circuit has stopped charging current; and
When the battery voltage has not reached the protection voltage, canceling the stop of the charging current by the battery protection circuit, limiting the charging current to a predetermined limit through the output interface, and resuming charging. A battery circuit control method to be executed.

It is a figure which illustrates the hardware constitutions of an electronic device. It is a block diagram which illustrates the composition of a charging circuit. It is a figure which illustrates operation | movement of a charge control apparatus. It is a figure which shows the conventional control sequence by a microcomputer. It is a figure which illustrates the change of the current voltage when there is no protection by a protection circuit. It is a figure which illustrates the change of the current voltage when a protection circuit operate | moves. It is a figure which illustrates the change of the current voltage at the time of charge control in a 1st embodiment. It is a figure which illustrates the charge control process in 1st Embodiment. It is a figure which shows the detail of a charging current reduction control process. This is an example in which the charging current is decreased step by step with time. In this example, when the charging voltage reaches a specified voltage, the charging current is greatly reduced until it becomes close to 0, and the charging current is increased stepwise. It is a figure which illustrates the reset process of a protection circuit. It is an example of detailed composition of electronic equipment. It is a figure which illustrates the charge control process in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery pack 2 Main body part 3 AC adapter 4 Power supply control part 11 Battery cell 12 Switch 13 Protection circuit 14 A / D converter 15, 235 Current sense resistor 21 Power supply circuit 22 Microcomputer 23 Charging circuit 232,233 FET
234 Coil 235 Current sense resistor 236 Charging current setting input terminal 237 Charging voltage setting input terminal

Claims (10)

A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A charging circuit capable of changing a charging current when charging the battery, and a control device for the battery circuit,
An input interface for reading the battery voltage detected by the voltage detector;
A determination unit for determining whether the read battery voltage is close to a predetermined limit to the protection voltage;
An output interface for outputting a signal for controlling the charging current;
A battery circuit control device comprising: a current control unit that limits the charging current to a predetermined limit through the output interface when it is determined to be close. A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A charging circuit capable of changing the charging current when charging the battery; and
A control device,
The controller is
An input interface for reading the battery voltage detected by the voltage detector;
A determination unit for determining whether the read battery voltage is close to a predetermined limit to the protection voltage;
An output interface for outputting a signal for controlling the charging current;
And a current control unit configured to limit the charging current to a predetermined limit through the output interface when it is determined to be close. The battery has a plurality of cell blocks each including a cell block or a plurality of cells connected in series,
The voltage detection unit has a measurement circuit for detecting the voltage of each cell block,
The determination unit determines whether the voltage of any cell block is close to a predetermined limit to the protection voltage of the cell block,
The charge control device according to claim 2, wherein the current control unit limits the charging current to the limit when it is determined that the voltage of any cell block is close to the limit.   The charge control device according to claim 2, wherein when the battery voltage is determined to be close to the limit, the current limiting unit decreases the charging current step by step with time.   The current limiting unit decreases the charging current by a first change amount when it is determined that the battery voltage is close to the limit, and further, a second change that is smaller than the first change amount as time passes. The charge control device according to claim 2, wherein the charge current is increased stepwise by the amount of change.   The charge control device according to claim 2, wherein when the battery voltage is determined to be close to the limit, the current limiting unit decreases a charging current according to a difference between the protection voltage and the battery voltage.   The charging control device according to claim 2, wherein the current limiting unit decreases the charging current as the difference between the battery voltage and the protection voltage decreases. A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A charging circuit capable of changing the charging current when charging the battery; and
A control device;
A battery charged through the charging circuit under the control of the control device;
A load that receives power supply from the charged battery,
The controller is
An input interface for reading the battery voltage detected by the voltage detector;
A determination unit for determining whether the read battery voltage is close to a predetermined limit to the protection voltage;
An output interface for outputting a signal for controlling the charging current;
An electronic device comprising: a current control unit that restricts the charging current to a predetermined limit through the output interface when it is determined that the proximity has occurred. A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A battery circuit control device including a charging circuit capable of changing a charging current when charging the battery,
Reading out the battery voltage detected by the voltage detector through an input interface;
A determination step of determining whether the read battery voltage is close to the protection voltage to a predetermined limit;
And a step of limiting the charging current to a predetermined limit through an output interface when the proximity is determined to be close. A voltage detector for detecting the battery voltage;
A battery protection circuit for stopping the charging current when the battery voltage detected by the voltage detection unit exceeds a protection voltage;
A charging circuit capable of changing a charging current when charging the battery, and a control device for the battery circuit,
An input interface for inputting a signal indicating an operation state of the battery protection circuit;
An output interface for outputting a signal for controlling the charging current;
A protection state determination unit that determines whether the battery protection circuit has stopped charging current; and
A voltage state determination unit for determining whether or not the battery voltage has reached a protection voltage after the battery protection circuit has stopped charging current;
When the battery voltage has not reached the protection voltage, the charging control unit releases the suspension of the charging current by the battery protection circuit and restarts charging by limiting the charging current to a predetermined limit through the output interface. And a battery circuit control device.

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