JP2010038592A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine a failure by an extremely simple circuit without providing a special-purpose circuit. <P>SOLUTION: A battery pack includes a rechargeable battery 1, a first charging circuit 10 for detecting the voltage of a battery 1 and converting external input power into charging voltage of the battery 1 to charge the battery 1, and a second charging circuit 20 for charging the battery 1 with device supply power supplied from a connected electronic device 5. The first charging circuit 10 includes a first voltage detection circuit 11 for detecting the voltage of the battery 1. The second charging circuit 20 includes a second voltage detection circuit 21 for detecting the voltage of the battery 1. The battery pack is further provided with a failure determination circuit 2 for determining a failure in the voltage detection circuits from the voltages of the battery 1 detected by the first voltage detection circuit 11 and the second voltage detection circuit 21. The failure determination circuit 2 determines a failure in the voltage detection circuits from the first detection voltage detected by the first voltage detection circuit 11 and the second detection voltage detected by the second voltage detection circuit 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery pack that is detachably connected to an electronic device, and more particularly to a battery pack having a failure determination circuit.

  A battery pack that detects the battery voltage and controls the charging current with the battery voltage to fully charge the battery includes a battery voltage detection circuit. This battery pack cannot be charged normally if the voltage detection circuit fails. In order to avoid this adverse effect, a battery pack that improves safety by determining a failure has been developed. (See Patent Document 1)

The battery pack accumulates the charge capacity during charging, diagnoses whether the charge capacity is greater than a certain set value, turns off the charge FET, and performs failure diagnosis of the charge capacity abnormality. This battery pack can maintain safety even when there is an abnormality in the battery or the battery voltage measurement system.
JP 2002-325363 A

  Since the battery pack of Patent Document 1 detects a charge capacity and determines a failure, it is difficult to always accurately determine the failure. This is because the charge capacity varies depending on the remaining capacity of the battery to be charged, and it is difficult to always accurately determine the remaining capacity even if the charge capacity is detected in consideration of the remaining capacity. In addition, since this battery pack determines a failure from the charging capacity, there is a drawback that a battery that is charged at a constant voltage and a constant current, such as a lithium ion battery, cannot be charged safely. After discharging to the end-of-discharge voltage, the battery pack requires a charge amount of 1.5 to 2 times the nominal capacity value until judgment, and the charge amount is basically a battery no matter how accurate the accumulator is. Never fall below the learning capacity. Therefore, at least charging for the learning capacity is required until the determination, and it takes time to determine the abnormality. For example, the battery pack of Patent Document 1 is not suitable for determining a defect in which heat generation due to an abnormal short circuit on the substrate continues and the substrate is thermally damaged. In addition, a voltage value higher than a specified charging voltage may be applied due to a voltage variation between each series of assembled batteries or a failure on the charger side. When considering the failure in which the voltage measurement value exemplified in Patent Document 1 is small, it takes a determination time as described above. Therefore, normally, the timing for applying overvoltage protection is lost, and the battery is charged to an abnormally high voltage. There is a concern that the safety of this product will be significantly reduced.

  The failure of the voltage detection circuit can be determined, for example, by inputting a reference voltage to the voltage detection circuit and detecting the output voltage. However, this circuit configuration requires the provision of a reference voltage circuit for failure determination, and the output voltage is detected at the timing when this reference voltage is input to the voltage detection circuit, so that the circuit configuration is complicated. .

  The present invention has been developed for the purpose of solving such drawbacks. An important object of the present invention is to provide a battery pack capable of determining a failure with a very simple circuit configuration. In particular, the battery pack of the present invention is to provide a battery pack capable of determining a failure of a detection circuit such as a voltage without providing a dedicated circuit for determining the failure.

  The battery pack according to claim 1 of the present invention is a battery pack that is detachably connected to the electronic device 5, the battery 1 that can be charged, and the voltage of the battery 1 is detected to charge external input power to the battery 1. A first charging circuit 10 that converts the voltage to charge the battery 1 and a second charging circuit 20 that charges the battery 1 with device supply power supplied from the connected electronic device 5 are provided. The first charging circuit 10 includes a first voltage detection circuit 11 that detects the voltage of the battery 1. The second charging circuit 20 includes a second voltage detection circuit 21 that detects the voltage of the battery 1. Further, the battery pack includes a failure determination circuit 2 that determines a failure of the voltage detection circuit from the voltage of the battery 1 detected by the first voltage detection circuit 11 and the second voltage detection circuit 21. In the battery pack, the failure determination circuit 2 detects a failure of the voltage detection circuit from the first detection voltage detected by the first voltage detection circuit 11 and the second detection voltage detected by the second voltage detection circuit 21. Judgment.

  The battery pack according to claim 2 of the present invention is a battery pack that is detachably connected to the electronic device 5, and is a rechargeable battery 1 and a first charging circuit that converts external input power to a charging voltage of the battery 1. 30 and a second charging circuit 40 that charges the battery 1 with device supply power supplied from the connected electronic device 5 or power supplied from the first charging circuit 30. The first charging circuit 30 includes a first voltage detection circuit 31 that detects a voltage supplied to the battery 1. The second charging circuit 40 includes a second voltage detection circuit 21 that detects the voltage of the battery 1. Further, the battery pack determines a failure of the voltage detection circuit from the voltage supplied to the battery 1 detected by the first voltage detection circuit 31 and the voltage of the battery 1 detected by the second voltage detection circuit 21. A circuit 2 is provided. In the battery pack, the failure determination circuit 2 detects a failure of the voltage detection circuit from the first detection voltage detected by the first voltage detection circuit 31 and the second detection voltage detected by the second voltage detection circuit 21. Judgment.

  In the battery pack according to claim 3 of the present invention, the first charging circuits 10 and 30 include the first current detection circuits 12 and 32, and the second charging circuits 20 and 40 include the second current detection circuit 22. The failure determination circuit 2 detects a failure of the current detection circuit from the first detection current detected by the first current detection circuits 12 and 32 and the second detection current detected by the second current detection circuit 22. Judgment.

  In the battery pack according to claim 4 of the present invention, the first charging circuits 10 and 30 include the first temperature detection circuit 13, and the second charging circuits 20 and 40 include the second temperature detection circuit 23. The failure determination circuit 2 determines the failure of the temperature detection circuit from the first detection temperature detected by the first temperature detection circuit 13 and the second detection temperature detected by the second temperature detection circuit 23. .

  In the battery pack according to claim 5 of the present invention, the first charging circuit 10 is connected to the DC / DC converter 17 that converts external input power into DC power and the output side of the DC / DC converter 17. 1 charging control circuit 14.

  Furthermore, in the battery pack of claim 6 of the present invention, the first charging circuit 30 includes the DC / DC converter 17 that converts external input power to DC power, and the second charging circuit 40 is DC / DC. A second charge control circuit 24 connected to the output side of the converter 17 is provided.

  Furthermore, in the battery pack according to claim 7 of the present invention, the failure determination circuit 2 determines the failure of the DC / DC converter 17 by comparing the input power and the output power of the DC / DC converter 17.

  In the battery pack according to claim 8 of the present invention, the first charging circuits 10 and 30 include the first temperature detection circuit 13, and the second charging circuits 20 and 40 include the second temperature detection circuit 23. One of the first temperature detection circuit 13 and the second temperature detection circuit 23 detects the temperature of the battery 1, and the other detects and detects the temperature of the circuit board on which the charging circuit is mounted. The charging current of the battery 1 is controlled by both the temperature of the battery 1 and the temperature of the circuit board.

  The battery pack according to claim 1 of the present invention can determine a failure with an extremely simple circuit configuration, and in particular, can determine a failure of the voltage detection circuit without providing a dedicated circuit for determining the failure. The battery pack includes a first charging circuit for charging the battery with external input power, and a second charging circuit for charging the battery with device supply power supplied from an electronic device connected to the pack battery. This is because the failure detection is determined by comparing the detection voltages detected by the first voltage detection circuit and the second voltage detection circuit using the voltage detection circuit provided in the first and second voltage detection circuits.

  The battery pack according to claim 2 of the present invention can determine a failure with an extremely simple circuit configuration, and in particular, can determine a failure of the voltage detection circuit without providing a dedicated circuit for determining the failure. That is, the battery pack is supplied from a first charging circuit that converts external input power into a battery charging voltage, and device supply power supplied from an electronic device that connects the battery pack, or a first charging circuit. A second charging circuit for charging the battery with electric power, a voltage supplied to the battery detected by the first voltage detection circuit of the first charging circuit, and a second voltage detection circuit of the second charging circuit This is because a failure is determined by comparing the voltage of the battery detected in (1). In particular, this battery pack charges the battery with both external input power and equipment supply power, but does not control charging with a separate charging circuit, but converts it to the battery charging voltage with the first charging circuit. Charging is performed while being controlled by the second charging circuit to which the supplied external input power and the device supply power input from the connected device are input. Both can charge the battery. In this battery pack, since the first voltage detection circuit of the first charging circuit is a voltage detection circuit that detects the voltage supplied to the battery, it is compared with the second voltage detection circuit that detects the voltage of the battery. Thus, it is possible to reliably determine the failure while reducing the manufacturing cost by using the first voltage detection circuit as a simple circuit configuration.

  Furthermore, in the battery pack according to claim 3 of the present invention, the first charging circuit includes the first current detection circuit, the second charging circuit includes the second current detection circuit, and the first current A failure of the current detection circuit is determined from the first detection current detected by the detection circuit and the second detection current detected by the second current detection circuit. This battery pack can determine the failure of the current detection circuit without providing a dedicated circuit for determining the failure.

  Furthermore, the battery pack according to claim 4 of the present invention is such that the first charging circuit includes the first temperature detection circuit, the second charging circuit includes the second temperature detection circuit, and the first temperature. A failure of the temperature detection circuit is determined from the first detection temperature detected by the detection circuit and the second detection temperature detected by the second temperature detection circuit. This battery pack can determine the failure of the temperature detection circuit without providing a dedicated circuit for determining the failure.

  Furthermore, in the battery pack according to claim 5 of the present invention, the first charging circuit is connected to the DC / DC converter for converting the external input power to the DC power and the output side of the DC / DC converter. The charging control circuit is provided. This battery pack can be fully charged in a preferable state with power output from the DC / DC converter.

  Furthermore, in the battery pack according to claim 6 of the present invention, the first charging circuit includes a DC / DC converter that converts external input power into DC power, and the second charging circuit includes an output of the DC / DC converter. A second charge control circuit connected to the side. This battery pack can be fully charged in a preferable state with power output from the DC / DC converter.

  Furthermore, in the battery pack according to claim 7 of the present invention, the failure determination circuit determines the failure of the DC / DC converter by comparing the input power and the output power of the DC / DC converter. This battery pack can easily detect a failure of the DC / DC converter.

  Furthermore, in the battery pack according to claim 8 of the present invention, the first charging circuit includes the first temperature detection circuit, the second charging circuit includes the second temperature detection circuit, Either one of the temperature detection circuit and the second temperature detection circuit detects the temperature of the battery, and the other detects the temperature of the circuit board on which the charging circuit is mounted, and detects the temperature of the battery and the temperature of the circuit board Both control the battery charging current. The battery pack can be charged while protecting the battery from temperature abnormalities even if one temperature detection circuit fails.

  Embodiments of the present invention will be described below with reference to the drawings. However, the example shown below illustrates the battery pack for embodying the technical idea of the present invention, and the present invention does not specify the battery pack as the following structure.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  The battery pack shown in the circuit diagram of FIG. 1 is used by being detachably connected to an electronic device 5 such as a laptop personal computer. The battery pack is connected to the electronic device 5 to charge the battery with electric power supplied from the electronic device 5, and in an unplugged state from the electronic device 5, an AC adapter (not shown) connected to the power supply terminal 3. Etc.) and the battery 1 is charged with electric power input from the outside.

  The battery pack shown in the figure includes a battery 1 that can be charged, a first charging circuit 10 that charges the battery 1 with external input power, and a second battery that charges the battery 1 with device supply power supplied from the connected electronic device 5. Charging circuit 20. The first charging circuit 10 detects the voltage of the battery 1 and converts the external input power into the charging voltage of the battery 1 to charge the battery 1 while controlling the output with the detected voltage.

  The battery 1 is a lithium ion secondary battery. However, the battery can be any battery that can be charged, such as a nickel metal hydride battery or a nickel cadmium battery, instead of a lithium ion battery. The battery pack shown in the figure has two batteries 1 connected in series, but the battery pack contains one battery, or three or more batteries connected in series, or a plurality of batteries connected in parallel. You can also connect to. A battery pack in which a plurality of batteries 1 are connected in series detects both the battery voltage and the total voltage, and fully charges the battery 1 while controlling charging with the detected voltage.

  The first charging circuit 10 charges the battery 1 in a state where device supply power is not supplied from the electronic device 5 and external input power is supplied. Therefore, the first charging circuit 10 detects that the device supply power is not supplied and charges the battery 1. Whether or not the device supply power is supplied can be determined by detecting the voltage of the connector that connects the battery pack to the electronic device 5 by turning off the first switching element 15 and turning on the second switching element 25. Alternatively, the determination may be made simply by the potential of the main body attachment / detachment determination terminal (not shown).

  The first charging circuit 10 includes a first voltage detection circuit 11 that detects the voltage of the battery 1, a first current detection circuit 12 that detects a charging current of the battery 1, a first charging circuit 10, and a second charging circuit 10. The first temperature detection circuit 13 for detecting the temperature of the circuit board on which the charging circuit 20 is mounted, the DC / DC converter 17 for converting the input external input power to the charging voltage of the battery 1, and the DC / DC converter And a first charge control circuit 14 connected to the output side of 17.

  The first voltage detection circuit 11 detects the voltage of the battery 1 and outputs a detection signal to the first charge control circuit 14 and the DC / DC converter 17. Since the battery pack shown in FIG. 1 includes a plurality of batteries 1 connected in series, the first voltage detection circuit 11 detects each battery voltage, detects the total voltage, and outputs a detection signal. 1 to the charge control circuit 14 and the DC / DC converter 17. The battery pack can contain one battery, or a plurality of batteries can be connected in parallel. In these battery packs, the voltage of the battery directly arranged is detected by the first voltage detection circuit.

  The first current detection circuit 12 includes a current detection resistor 12A connected in series with the battery 1 and a differential amplifier 12B that amplifies the voltage at both ends of the current detection resistor 12A. The first current detection circuit 12 detects the current of the battery 1 by amplifying the voltage of the current detection resistor 12A with the differential amplifier 12B. The output voltage of the differential amplifier 12B is the product of the electrical resistance of the current detection resistor 12A, the current value, and the amplification factor of the differential amplifier 12B. Since the electric resistance of the current detection resistor 12A and the amplification factor of the differential amplifier 12B are known values, the current can be detected from the output voltage of the differential amplifier 12B. That is, the output voltage of the differential amplifier 12B is proportional to the current of the battery 1.

  The first temperature detection circuit 13 includes a temperature sensor 13A such as a thermistor. The temperature sensor 13A is disposed in the vicinity of a heat generating component of the circuit board, for example, an FET that is a component constituting the first charge control circuit 14, and detects the temperature of the portion heated to a high temperature of the circuit board. Since the temperature sensor 13A is an element whose electric resistance varies with temperature, the first temperature detection circuit 13 can detect the temperature of the temperature measurement point by detecting the electric resistance of the temperature sensor 13A. However, the first temperature detection circuit detects the battery temperature instead of the circuit temperature by thermally coupling the temperature sensor with the battery in order to directly compare the battery temperature detected by the second temperature detection circuit described later. You can also

  The DC / DC converter 17 converts external input power input from an AC adapter or the like into a charging voltage for the battery 1 using a built-in switching element, coil, and smoothing capacitor (each not shown). The DC / DC converter 17 has a constant voltage / constant current characteristic that stabilizes the maximum output voltage and current by adjusting the duty of switching the switching element on and off. That is, the DC / DC converter 17 has voltage-current characteristics for charging the battery 1 at a constant voltage / constant current. The DC / DC converter 17 includes a voltage feedback circuit (not shown) that feeds back an output voltage and an output current and a current feedback circuit (not shown) in order to charge the battery 1 at a constant voltage / constant current. The voltage feedback circuit stabilizes the maximum output voltage to be constant by controlling the duty of the switching element by the output voltage of the first voltage detection circuit 11. The current feedback circuit controls the duty of the switching element by the output of the first current detection circuit 12 and stabilizes the maximum output current to be constant. For example, the DC / DC converter 17 sets the maximum output voltage to 4.2 V / cell and the maximum output current to 0.5 C to 1 C.

  The first charge control circuit 14 includes a first switching element 15 connected between the output side of the DC / DC converter 17 and the battery 1, a first voltage detection circuit 11, and a first current detection circuit. And a first control circuit 16 that controls the first switching element 15 with 12 outputs. The first control circuit 16 detects the voltage and current of the battery 1 and controls the first switching element 15 to be turned on and off to fully charge the battery 1. The first control circuit 16 turns on the first switching element 15 to charge the battery 1, and when the battery 1 is fully charged, the first switching element 15 is switched from on to off to stop charging.

  A battery pack in which a plurality of batteries 1 are connected in series, when the voltage of any one of the batteries 1 exceeds a pulse charge start voltage (for example, 4.18 V), the first switching element 15 is switched on and off to perform pulse charge. To do. In the pulse charging, when the battery 1 exceeds the full charge start voltage, the first switching element 15 is turned off. After that, when the voltage of the battery 1 drops to the pulse charge restart voltage (for example, 4.15 V), the first switching is performed. Switch element 15 on. When the battery 1 is fully charged by pulse charging, the first control circuit 16 switches off the first switching element 15 and stops charging.

  The second charging circuit 20 includes a second voltage detection circuit 21 that detects the voltage of the battery 1, a second current detection circuit 22 that detects a charging current of the battery 1, and a second voltage that detects the temperature of the battery 1. And a second charge control circuit 24 that charges the battery 1 with device supply power supplied from an electronic device 5 such as a personal computer to which the battery pack is connected.

  Similarly to the first voltage detection circuit 11, the second voltage detection circuit 21 detects the voltage of the battery 1 and outputs a detection signal to the second charge control circuit 24. Since the battery pack shown in the figure incorporates a plurality of batteries 1 connected in series, the second voltage detection circuit 21 detects each battery voltage, detects the total voltage, and outputs a second detection signal. To the charging control circuit 24.

  Similar to the first current detection circuit 12, the second current detection circuit 22 includes a current detection resistor 22A connected in series with the battery 1, and a differential amplifier that amplifies the voltage across the current detection resistor 22A. 22B. The battery pack shown in the figure uses both the current detection resistor 12A of the first current detection circuit 12 and the current detection resistor 22A of the second current detection circuit 22, but the first current detection circuit and the second current detection circuit are different from each other. The current can also be detected by amplifying the voltage of the current detection resistor provided separately by a differential amplifier. Similar to the first current detection circuit 12, the second current detection circuit 22 detects a current with the output voltage of the differential amplifier 22B.

  Since the second temperature detection circuit 23 detects the temperature of the battery 1, a temperature sensor 23 </ b> A such as a thermistor is thermally coupled to the battery 1, that is, is in contact with or close to the battery 1. Similar to the first temperature detection circuit 13, the second temperature detection circuit 23 detects the temperature of the battery 1 by detecting the electrical resistance of the temperature sensor 23A.

  The second charging control circuit 24 charges the battery 1 by controlling the device supply power supplied from the electronic device 5 to which the battery pack is connected. The electronic device 5 has a built-in constant voltage / constant current charging circuit for charging the battery pack, and supplies device supply power to the battery pack from the constant voltage / constant current charging. Therefore, unlike the DC / DC converter 17 of the first charging circuit 10, the second charging control circuit 24 does not require a circuit that stabilizes the input device supply power to a constant voltage and a constant current. The second charge control circuit 24 outputs the second switching element 25 that controls the charging of the battery 1 with the input device supply power, and the outputs of the second voltage detection circuit 21 and the second current detection circuit 22. And a second control circuit 26 that controls the two switching elements 25. The second control circuit 26 detects the voltage and current of the battery 1 and controls the second switching element 25 to be turned on and off to fully charge the battery 1. The second control circuit 26 turns on the second switching element 25 to charge the battery 1. When the battery 1 is fully charged, the second control circuit 26 switches the second switching element 25 from on to off and stops charging.

  As in the case of the first charge control circuit 14, the second charge control circuit 24 is a battery pack in which a plurality of batteries 1 are connected in series. For example, when it exceeds 4.18 V), the second switching element 25 is switched on and off to perform pulse charging. Similarly to the first charge control circuit 14, in the pulse charge, when the battery 1 exceeds the full charge start voltage, the second switching element 25 is turned off, and then the voltage of the battery 1 is changed to the pulse charge restart voltage (for example, 4 .15V), the second switching element 25 is switched on. When the battery 1 is fully charged by pulse charging, the second control circuit 26 switches off the second switching element 25 and stops charging.

  The failure determination circuit 2 determines a failure of the voltage detection circuit from the first detection voltage detected by the first voltage detection circuit 11 and the second detection voltage detected by the second voltage detection circuit 21. When the first voltage detection circuit 11 and the second voltage detection circuit 21 operate normally, the voltage of the battery 1 detected by the first voltage detection circuit 11 and the second voltage detection circuit 21 becomes the same voltage. is there. Therefore, the failure determination circuit 2 compares the detection voltages detected by the first voltage detection circuit 11 and the second voltage detection circuit 21, and if the difference is smaller than the set value, It is determined that the second voltage detection circuit 21 is operating normally. In the failure determination, in the state where the battery 1 is pulse-charged, the set value of the voltage value for failure determination from the first detection voltage and the second detection voltage is made larger than that of the non-pulse charge. This is because the first voltage detection circuit 11 and the second voltage detection circuit 21 do not detect the voltage of the battery 1 at the same timing in synchronization with each other, and thus the detection voltage changes depending on the timing at which the voltage is detected. is there. That is, since pulse charging repeats charging and stopping, the voltage of the battery 1 changes between the charging state and the charging stop state.

  The failure determination circuit 2 determines a failure of the current detection circuit from the first detection current detected by the first current detection circuit 12 and the second detection current detected by the second current detection circuit 22. If the first current detection circuit 12 and the second current detection circuit 22 operate normally, the current of the battery 1 detected by the first current detection circuit 12 and the second current detection circuit 22 becomes the same current. is there. Therefore, the failure determination circuit 2 compares the first detection current detected by the first current detection circuit 12 with the second detection current detected by the second current detection circuit 22, and the difference is smaller than the set value. If it is smaller, it is determined that the first current detection circuit 12 and the second current detection circuit 22 are operating normally.

  Further, the failure determination circuit 2 determines a failure of the temperature detection circuit from the first detection temperature detected by the first temperature detection circuit 13 and the second detection temperature detected by the second temperature detection circuit 23. You can also. When the first temperature detection circuit 13 and the second temperature detection circuit 23 operate normally, the temperature of the battery 1 detected by the first temperature detection circuit 13 and the second temperature detection circuit 23 becomes an approximate temperature. It is. However, since the first temperature detection circuit 13 detects the temperature of the circuit board and the second temperature detection circuit 23 detects the temperature of the battery 1, the first detection temperature and the second detection temperature are the same. It does not reach temperature. However, when the battery 1 is charged and the temperature of the battery 1 rises, the temperature of the circuit board also rises. Therefore, if the detection temperature for detecting the temperature of the circuit board and the battery 1 becomes larger than the set value, the temperature detection circuit fails. Can be determined. The set value for failure determination is small because the temperature difference between the battery 1 and the circuit board is small when the battery 1 is not charged, and the set value is large because the temperature difference is large when the battery 1 is charged. To do.

  In the case of a battery pack in which the first temperature detection circuit 13 for detecting the temperature of the circuit board detects the temperature of a heat generating component such as an FET, the charging current is controlled at the detected temperature as shown in FIG. be able to. This figure allows a constant current until the second detection temperature is 80 ° C., but linearly decreases the charging current as it rises from 80 ° C. to 90 ° C. When the detected temperature exceeds 90 ° C., the charging current is cut off. This charging current limitation due to temperature is useful for improving the reliability of the charging circuit. Further, since there is a certain correlation between the temperature of the charging circuit and the battery temperature, the battery pack controls the charging current at the temperature of the circuit board, so that the second temperature for detecting the temperature of the battery 1 is assumed. Since the current can be limited when the detection circuit 23 fails and the temperature of the battery 1 rises, the battery 1 can be charged while protecting the battery 1 from temperature rise. This battery pack can be safely charged by controlling the charging current of the battery 1 at both the first detection temperature and the second detection temperature. In particular, when the vicinity of the FET on the circuit board detected by the first temperature detection circuit rises to 80 ° C. to 90 ° C., the temperature of the battery detected by the second temperature detection circuit decreases, for example, the charging current. For battery packs with a temperature of ℃, even when the battery temperature cannot be detected, the battery temperature is indirectly detected by the circuit board temperature, limiting the charging current to the optimum current and improving safety. it can.

  Further, FIG. 3 shows a battery pack according to another embodiment. The battery pack shown in the circuit diagram of FIG. 3 includes a battery 1 that can be charged, a first charging circuit 30 that converts external input power to a charging voltage of the battery 1, and device supply power supplied from the connected electronic device 5. Or a second charging circuit 40 that charges the battery 1 with electric power supplied from the first charging circuit 30. In FIG. 3, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The first charging circuit 30 converts the external input power into a charging voltage for the battery 1 and outputs the battery 1 in a state where the external input power is supplied. The first charging circuit 30 includes a first voltage detection circuit 31 that detects a voltage supplied to the battery 1, a first current detection circuit 32 that detects an input current supplied from the outside, and a first charging circuit. 30 and the first temperature detection circuit 13 for detecting the temperature of the circuit board on which the second charging circuit 40 is mounted, the DC / DC converter 17 for converting the input external input power into the charging voltage of the battery 1, and this And a first charge control circuit 34 that controls the DC / DC converter 17.

  The first voltage detection circuit 31 detects a voltage input from the outside and a voltage output from the first charging circuit 30, and sends a detection signal to the first charging control circuit 34 and the DC / DC converter 17. Output. The first voltage detection circuit 31 detects an input voltage and an output voltage of the DC / DC converter 17 as a voltage with respect to the negative potential of the plurality of batteries 1 connected in series.

  The first current detection circuit 32 includes a current detection resistor 32A connected in series to the input side of the DC / DC converter 17, and a differential amplifier 32B that amplifies the voltage across the current detection resistor 32A. The first current detection circuit 32 amplifies the voltage of the current detection resistor 32A by the differential amplifier 32B, and detects the input current supplied to the DC / DC converter 17 from the outside.

  The first charge control circuit 34 includes a first control circuit 36 that controls the DC / DC converter 17 using outputs of the first voltage detection circuit 31 and the first current detection circuit 32. The first control circuit 36 controls the DC / DC converter 17 in a state where the external power is input to the power supply terminal 3, and converts the external input power into the charging voltage of the battery 1.

  The second charging circuit 40 includes a second voltage detection circuit 21 that detects the voltage of the battery 1, a second current detection circuit 22 that detects a charging current of the battery 1, and a second voltage that detects the temperature of the battery 1. The battery 1 is charged with the power supplied from the electronic device 5 such as a personal computer connected to the temperature detection circuit 23 and the battery pack, or the power supplied from the first charging circuit 30. Circuit 24.

  The second charge control circuit 24 controls the device supply power supplied from the electronic device 5 to which the battery pack is connected or the power supplied from the DC / DC converter 17 of the first charge circuit 30 to control the battery 1. To charge. Since the output voltage of the DC / DC converter 17 can be controlled to be equal to the charging condition supplied from the electronic device 5, the output of the DC / DC converter 17 is connected to the charging control circuit 24 as shown in the figure. The battery 1 can be charged. The second charging control circuit 24 includes a second switching element 25 that controls the charging of the battery 1 with the device supply power input from the electronic device 5 or the power supplied from the first charging circuit 30; Voltage detection circuit 21 and a second control circuit 26 for controlling the second switching element 25 by the output of the second current detection circuit 22. The second charging control circuit 24 connects the input terminal 6 to which device supply power is input from the connection device 5 and the output side of the first charging circuit 30 to the input side of the second switching element 25. The second control circuit 26 detects the voltage and current of the battery 1 and controls the second switching element 25 to be turned on and off to fully charge the battery 1. The second control circuit 26 turns on the second switching element 25 to charge the battery 1. When the battery 1 is fully charged, the second control circuit 26 switches the second switching element 25 from on to off and stops charging.

  The battery pack of this structure charges the battery 1 with both external input power and device supply power, but does not charge the battery with a separate charging control circuit, but with the first charging circuit 30 of the battery 1. Both the external input power converted into the charge voltage and the device supply power input from the connected device 5 are input to the second charge control circuit 24, and the second charge control circuit 24 charges the battery 1. Control. For this reason, the battery 1 can be charged with both the external input power and the device supply power while simplifying the circuit configuration for controlling the charging of the battery. In this battery pack, since the first voltage detection circuit 31 of the first charging circuit 30 is a voltage detection circuit that detects the voltage supplied to the battery 1, the plurality of batteries 1 connected in series with each other are connected. Compared to the second voltage detection circuit 21 that requires high accuracy for detecting the voltage, the first voltage detection circuit 31 can have a simple circuit configuration. Therefore, it is possible to reliably determine a failure while simplifying the structure of the entire circuit and reducing the manufacturing cost.

  The failure determination circuit 2 is a first detection voltage that is an output voltage of the DC / DC converter 17 detected by the first voltage detection circuit 31 and a battery total voltage that is detected by the second voltage detection circuit 21. The relative relationship between the two detection voltages is compared to determine whether the voltage detection circuit is faulty. That is, the failure determination circuit 2 compares the detection voltages detected by the first voltage detection circuit 31 and the second voltage detection circuit 21, and if the difference is smaller than the set value, When it is determined that the second voltage detection circuit 21 is operating normally and the difference is larger than the set value, it is determined that one of the first voltage detection circuit 31 and the second voltage detection circuit 21 has failed. To do.

  Further, the failure determination circuit 2 compares the relative relationship between the first detection current detected by the first current detection circuit 32 and the second detection current detected by the second current detection circuit 22, A failure of the current detection circuit is determined. The failure determination circuit 2 compares the first detection current detected by the first current detection circuit 32 with the second detection current detected by the second current detection circuit 22, and if the difference is smaller than the set value The first current detection circuit 32 and the second current detection circuit 22 are determined to be operating normally.

  Further, the failure determination circuit 2 detects the temperature from the first detection temperature detected by the first temperature detection circuit 13 and the second detection temperature detected by the second temperature detection circuit 23, as in the previous embodiment. Circuit faults can also be determined.

  The DC / DC converter 17 includes components such as a switching FET, a coil, a rectifying diode, and a smoothing capacitor. When these components fail, the DC / DC converter 17 cannot convert the input power into a predetermined voltage with a predetermined efficiency and cannot output it. 3 determines the failure of the DC / DC converter 17 by comparing the input power and the output power of the DC / DC converter 17. The failure determination circuit 2 detects the current and voltage on the input side of the DC / DC converter 17 and calculates the input power. This is because the input power can be calculated by the product of an externally input voltage and current. Since the battery pack of FIG. 3 detects both the voltage and current of the external input power, the input power of the DC / DC converter 17 can be detected more accurately. However, the battery pack can detect the input power by detecting only the current on the input side of the DC / DC converter 17 by the input current detection circuit 18 as shown by the chain line in FIG. This is because the voltage of the external input power is almost constant, so that the input power can be calculated by detecting only the current without detecting the voltage. Furthermore, the power on the output side of the DC / DC converter 17 can be detected by the product of the total voltage and current of the battery 1. The ratio of the power on the input side and the power on the output side of the DC / DC converter 17 is specified by the efficiency of the DC / DC converter 17. The efficiency of the DC / DC converter 17 varies depending on the output, for example, as follows.

Output current is 0.5A or less ………… Conversion efficiency is 20% ~ 85%
Output current is 0.5A to 1.8A ... Conversion efficiency is 80% to 95%
Output current is 1.8A or more ………… Conversion efficiency is 93% or more

  However, the conversion efficiency is calculated by (output power / input power) × 100. The failure determination circuit 2 detects the conversion efficiency from the ratio between the input power and the output power based on the output current, and determines that the DC / DC converter 17 has failed when the detected conversion efficiency is not within the above-described range.

1 is a circuit diagram of a battery pack according to an embodiment of the present invention. It is a graph which shows the state which controls charging current with detected temperature. It is a circuit diagram of the battery pack according to another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery 2 ... Failure determination circuit 3 ... Power supply terminal 5 ... Electronic device 6 ... Input terminal 10 ... 1st charging circuit 11 ... 1st voltage detection circuit 12 ... 1st current detection circuit 12A ... Current detection resistance
DESCRIPTION OF SYMBOLS 12B ... Differential amplifier 13 ... 1st temperature detection circuit 13A ... Temperature sensor 14 ... 1st charge control circuit 15 ... 1st switching element 16 ... 1st control circuit 17 ... DC / DC converter 18 ... Input current detection Circuit 20 ... second charging circuit 21 ... second voltage detection circuit 22 ... second current detection circuit 22A ... current detection resistor
22B ... differential amplifier 23 ... second temperature detection circuit 23A ... temperature sensor 24 ... second charge control circuit 25 ... second switching element 26 ... second control circuit 30 ... first charge circuit 31 ... first Voltage detection circuit 32 ... first current detection circuit 32A ... current detection resistor
32B ... Differential amplifier 34 ... First charging control circuit 36 ... First control circuit 40 ... Second charging circuit

Claims (8)

A battery pack detachably connected to an electronic device (5),
A battery (1) that can be charged, and a first charging circuit (10) that detects the voltage of the battery (1), converts external input power into a charging voltage of the battery (1), and charges the battery (1). A second charging circuit (20) for charging the battery (1) with the device supply power supplied from the connected electronic device (5),
The first charging circuit (10) includes a first voltage detection circuit (11) for detecting the voltage of the battery (1), and the second charging circuit (20) detects the voltage of the battery (1). A second voltage detection circuit (21);
Furthermore, a failure determination circuit (2) for determining a failure of the voltage detection circuit from the voltage of the battery (1) detected by the first voltage detection circuit (11) and the second voltage detection circuit (21) is provided. The failure determination circuit (2) detects a failure of the voltage detection circuit from the first detection voltage detected by the first voltage detection circuit (11) and the second detection voltage detected by the second voltage detection circuit (21). A battery pack that is configured to determine whether A battery pack detachably connected to an electronic device (5),
A battery (1) that can be charged, a first charging circuit (30) that converts external input power into a charging voltage of the battery (1), and device supply power supplied from the connected electronic device (5), or A second charging circuit (40) for charging the battery (1) with the electric power supplied from the charging circuit (30) of one;
The first charging circuit (30) includes a first voltage detection circuit (31) for detecting a voltage supplied to the battery (1), and the second charging circuit (40) determines the voltage of the battery (1). A second voltage detection circuit (21) for detection;
Further, the failure of the voltage detection circuit is detected from the voltage supplied to the battery (1) detected by the first voltage detection circuit (31) and the voltage of the battery (1) detected by the second voltage detection circuit (21). A failure determination circuit (2) for determining is provided. The failure determination circuit (2) detects the first detection voltage detected by the first voltage detection circuit (31) and the second voltage detection circuit (21). A battery pack configured to determine a failure of the voltage detection circuit from the second detection voltage.   The first charging circuits (10) and (30) include first current detection circuits (12) and (32), and the second charging circuits (20) and (40) are second current detection circuits. A circuit (22), and the failure determination circuit (2) detects the first detection current and the second current detection circuit (22) detected by the first current detection circuits (12) and (32). The battery pack according to claim 1, wherein a failure of the current detection circuit is determined from the second detection current.   The first charging circuit (10), (30) includes a first temperature detection circuit (13), and the second charging circuit (20), (40) is a second temperature detection circuit (23). And the failure determination circuit (2) detects the temperature from the first detection temperature detected by the first temperature detection circuit (13) and the second detection temperature detected by the second temperature detection circuit (23). The battery pack according to claim 1, wherein a failure of the circuit is determined.   The first charging circuit (10) is connected to the DC / DC converter (17) for converting external input power to DC power, and to the output side of the DC / DC converter (17). A battery pack according to claim 1, comprising a circuit (14).   The first charging circuit (30) includes a DC / DC converter (17) that converts external input power to DC power, and the second charging circuit (40) includes the DC / DC converter (17). The battery pack according to claim 2, further comprising a second charge control circuit (24) connected to the output side of the battery.   The battery pack according to claim 5 or 6, wherein the failure determination circuit (2) determines a failure of the DC / DC converter (17) by comparing input power and output power of the DC / DC converter (17). .   The first charging circuit (10), (30) includes a first temperature detection circuit (13), and the second charging circuit (20), (40) is a second temperature detection circuit (23). Of the circuit board on which one of the first temperature detection circuit (13) and the second temperature detection circuit (23) detects the temperature of the battery (1) and the other is mounted with the charging circuit. The battery pack according to claim 1, wherein the battery pack detects the temperature and controls the charging current of the battery in accordance with both the temperature of the battery to be detected and the temperature of the circuit board.

Images