JP2008005593A - Battery pack, electronic apparatus, and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack which performs the fault diagnosis of parts or the abnormality detection of a charger. <P>SOLUTION: Each measuring part measures terminal voltage, battery voltage, charge/discharge currents, and temperature. In case that the charge/discharge current is flowing, a fault diagnoser diagnoses the fault, based on the variation of circuit impedance obtained from each measurement result. When the charge/discharge current is not flowing, it diagnoses the fault, based on the difference between the terminal voltage and the battery voltage obtained from each measurement result and the state of a charge/discharge control FET. It is determined whether the circuit is abnormal from the result of diagnosis. When it is determined to be abnormal, it inhibits charge/discharge, and stores the diagnosis result in a memory, and also it supplies the result to an external electronic apparatus connected via a communication terminal. Moreover, in case that a charge is connected, it can detect the abnormality of the charger, based on the terminal voltage and the state of the charge/discharge FET. When it is determined that the charger is abnormal, it inhibits the charge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery pack and an electronic device that perform failure diagnosis, and a control method.

  In recent years, portable electronic devices such as notebook PCs (Personal Computers), cellular phones, and PDAs (Personal Digital Assistants) have become widespread, and lithium-ion secondary batteries having advantages such as high voltage, high energy density, and light weight as their power sources. Widely used.

  Lithium ion secondary batteries are composed of single cells or assembled batteries, and have a higher risk of overcharge and overdischarge than other batteries, and it is necessary to improve safety and reliability. A battery pack using such a lithium ion secondary battery is equipped with a control circuit for preventing overcharge and overdischarge of the secondary battery in order to maintain safety and reliability. Such a control circuit is usually mounted on a BMU (Battery Management Unit).

  This BMU is equipped not only with the above-described function for preventing overcharge and overdischarge, but also with a function for detecting a failure of a field effect transistor (FET) used in a control circuit for preventing overcharge and overdischarge. ing.

  Here, the configuration of an example of the conventional battery pack 100 will be schematically described with reference to FIG. As shown in FIG. 5, the battery pack 100 includes a battery 110, a BMU 111, a positive terminal 132, a negative terminal 133, and a communication terminal 134.

  The current measurement unit 124 calculates a current value based on the voltage applied to the current detection resistor 123 provided in the current path, and supplies the current value to the failure diagnosis unit 129. Further, the battery voltage measuring unit 125 measures the voltage value of the battery 110 and supplies it to the failure diagnosis unit 129. Further, the circuit temperature measurement unit 127 generates temperature information based on the temperature measured by the thermistor 126 disposed near the battery 110 and supplies the temperature information to the failure diagnosis unit 129.

  The failure diagnosis unit 129 calculates the remaining battery capacity based on the voltage value of the battery 110 supplied from the battery voltage measurement unit 125. Moreover, the failure diagnosis unit 129 monitors the battery temperature based on the temperature information supplied from the circuit temperature measurement unit 127. The calculated remaining capacity data and battery temperature data are stored in the memory 130. Further, the failure diagnosis unit 129 instructs the charge / discharge control unit 122 to permit / inhibit charging / discharging when the voltage of the battery 110 becomes an overcharge detection voltage or an overdischarge detection voltage based on the voltage value of the battery 110. To prevent overcharge and overdischarge.

  The charge / discharge control unit 122 controls ON / OFF of the switch circuit 121 based on a charge / discharge permission or prohibition command received from the failure diagnosis unit 129. The switch circuit 121 turns on / off the switch based on the control from the charge control unit 122 and cuts off the charge / discharge current flowing through the current path. The switch circuit 121 includes, for example, a charge / discharge control FET (Field Effect Transistor) and a thermal fuse.

  Hereinafter, a failure diagnosis method for the charge / discharge control FET in the battery pack 100 configured as described above will be schematically described. First, when the charge / discharge control unit 122 receives a command from the failure diagnosis unit 129 during charging of the battery 110, the charge control FET is forcibly turned off. In this state, the failure diagnosis unit 129 diagnoses a failure of the charge control FET depending on whether or not a current flows through the current detection resistor 123.

  If the current measurement unit 124 does not detect the current flowing through the current detection resistor 123, that is, if no charge / discharge current flows through the current path, the failure diagnosis unit 129 determines that the charge control FET is normal. On the other hand, when the current measuring unit 124 detects the charging / discharging current flowing through the current detection resistor 123 and a predetermined time elapses, the failure diagnosis unit 129 determines that the charge control FET is abnormal, and the communication unit 131. In contrast, information indicating abnormality of the battery pack 100 is supplied. The communication unit 131 supplies the information received from the failure diagnosis unit 129 to the electronic device connected to the outside via the communication terminal 134 and requests to prohibit the charging operation.

  Thus, the method of detecting a failure of the charge / discharge control FET is described in Patent Document 1 below.

JP 11-234910 A

  The failure detection method described in Patent Document 1 detects a failure of an FET based on whether or not a charge / discharge current flows in the current path when either one of the charge control FET and the discharge control FET is turned OFF. Is.

  However, the above-described failure detection method has a problem that a failure of the charge / discharge control FET cannot be detected, for example, when the charge control FET and the discharge control FET are ON. Therefore, in such a case, even if the charge / discharge control FET is broken, the charge / discharge operation is performed, and the device operates in a dangerous state such as overcharge or overdischarge.

  Therefore, an object of the present invention is to perform charge / discharge control and to perform failure diagnosis of the charge / discharge control FET regardless of the ON / OFF state of the charge / discharge control FET, thereby preventing overcharge and overdischarge in advance. A battery pack, an electronic device, and a control method are provided.

  In order to solve the above-described problems, a first invention includes one or a plurality of batteries connected in series and / or in parallel, a charge control FET and a discharge control FET that control charge / discharge currents for the batteries, A detection unit that detects a first voltage that is a voltage of an electrode terminal to be connected and a second voltage that is a voltage of one or a plurality of batteries, and a control unit that controls the circuit based on the first voltage and the second voltage And a communication unit that communicates with an external electronic device connected to the electrode terminal, and the control unit is in an ON / OFF state of the charge control FET and the discharge control FET when charging or discharging is not performed. In accordance with the difference between the first voltage and the second voltage, output data output to an external electronic device via the communication unit is controlled.

  Further, the second invention is a charge control FET and discharge control FET for controlling a charge / discharge current for a battery connected to the outside, a first voltage and a battery which are voltages of a first electrode terminal connected to the outside, A detection unit that detects a second voltage that is a voltage of a second electrode terminal to be connected, a control unit that controls a circuit based on the first voltage and the second voltage, and a first electrode terminal A communication unit that communicates with an external electronic device, and the control unit turns on the charge control FET and the discharge control FET when a battery is connected to the second electrode terminal and charging or discharging is not performed. A control circuit that controls output data to be output to an external electronic device via a communication unit according to the / OFF state and the difference between the first voltage and the second voltage.

  Moreover, 3rd invention is an electronic device which has a battery pack and performs charging / discharging of a battery pack, Comprising: One or several battery connected in series and / or parallel, and the charging / discharging electric current with respect to a battery are controlled A charge control FET and a discharge control FET that perform detection, a detection unit that detects a first voltage that is a voltage of a first electrode terminal connected to another device and a second voltage that is a voltage of one or more batteries, and A battery pack comprising: a first control unit that controls a circuit based on the first voltage and the second voltage; and a first communication unit that communicates with another device connected to the first electrode terminal; A second electrode terminal connected to the first electrode terminal, a second communication unit connected to the first communication unit to communicate with the battery pack, and exchange output data, and a charge / discharge state of the battery pack An output unit that outputs charging / discharging information indicating And controlling the charging / discharging of the battery pack based on the data, and the second control unit for controlling the output of the charging / discharging information by the output unit, where the first control unit is not charged or discharged Output data to be output to the second communication unit via the first communication unit according to the ON / OFF state of the charge control FET and the discharge control FET and the difference between the first voltage and the second voltage. It is an electronic device characterized by controlling.

  According to a fourth aspect of the present invention, there is provided a detection for detecting a first voltage that is a voltage of an electrode terminal connected to the outside and a second voltage that is a voltage of one or a plurality of batteries connected in series and / or in parallel. A control step for controlling the circuit based on the first voltage and the second voltage, and a communication step for communicating with an external electronic device connected to the electrode terminal. The control step comprises charging or discharging. If the charging control FET for controlling the charging / discharging current and the discharging control FET are turned on and off, and the difference between the first voltage and the second voltage, the external electronic device is communicated. The control method is characterized in that the output data to be output to is controlled.

  The fifth aspect of the invention is a detection step of detecting a first voltage that is a voltage of a first electrode terminal connected to the outside and a second voltage that is a voltage of a second electrode terminal connected to an external battery. And a control step for controlling the circuit based on the first voltage and the second voltage, and a communication step for communicating with an external electronic device connected to the first electrode terminal. Depending on the ON / OFF state of the charge control FET and discharge control FET and the difference between the first voltage and the second voltage when a battery is connected to the electrode terminal 2 and charging or discharging is not performed A control method characterized by controlling output data output to an external electronic device by communication.

  As described above, in the first, second, third, fourth, and fifth inventions, when charging and discharging are not performed, the charge control FET for controlling the charge / discharge current and the ON / OFF of the discharge control FET are controlled. Since the output data output to the external electronic device is controlled by communication according to the OFF state and the difference between the first voltage and the second voltage, the circuit state is notified to the outside.

  In the present invention, when charge / discharge is not performed, failure diagnosis is performed based on the ON / OFF state of the charge / discharge control FET and the difference between the first voltage and the second voltage, and the charge / discharge FET is turned on. Since the failure diagnosis of the charge / discharge control FET can be performed regardless of the / OFF state, there is an effect that overcharge and overdischarge can be prevented in advance.

  Hereinafter, a configuration of an example of a battery pack according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the battery pack 1 includes a battery 10, a BMU (Battery Management Unit) 11, a positive terminal 32, a negative terminal 33, and a communication terminal 34.

  The battery pack 1 is mounted on, for example, an electronic device, and the positive electrode terminal 32 and the negative electrode terminal 33 are connected to the positive electrode terminal and the negative electrode terminal of the electronic device, respectively, and the battery 10 is charged and discharged via the BMU 11.

  The battery 10 is, for example, a lithium ion secondary battery, and is a single battery or a battery pack in which a plurality of battery cells are connected in series and / or in parallel. The BMU 11 performs control for preventing overcharge and overdischarge of the battery pack 1, failure diagnosis of parts and a charger connected to the battery pack 1, and the like. Further, the BMU 11 can communicate with an external electronic device connected via the communication terminal 34 to notify the result of the failure diagnosis.

  The BMU 11 includes a switch circuit 21, a charge / discharge control unit 22, a current detection resistor 23, a current measurement unit 24, a battery voltage measurement unit 25, a thermistor 26, a circuit temperature measurement unit 27, a terminal voltage measurement unit 28, a failure diagnosis unit 29, and a memory. 30 and a communication unit 31.

  The terminal voltage measurement unit 28 measures the terminal voltage of the battery pack 1 that is the first voltage, and supplies the measured voltage value to the failure diagnosis unit 29. The battery voltage measurement unit 25 measures the voltage of the battery 10 that is the second voltage, and supplies the measured voltage value to the failure diagnosis unit 29. The current measuring unit 24 measures the voltage applied to the current detection resistor 23 provided in the current path, and based on the measured voltage value and the resistance value of the current detection resistor 23, the current value of the charge / discharge current flowing through the current path. Is calculated. Then, the current measurement unit 24 supplies the calculated current value to the failure diagnosis unit 29.

  The circuit temperature measurement unit 27 generates temperature information based on the temperature of the components constituting the switch circuit 21 measured by the thermistor 26 disposed near the switch circuit 21, and the generated temperature information is used as the failure diagnosis unit 29. To supply.

  The failure diagnosis unit 29 is connected to the components constituting the current path or the battery pack 1 based on the information supplied from the current measurement unit 24, the battery voltage measurement unit 25, the circuit temperature measurement unit 27, and the terminal voltage measurement unit 28. The failure diagnosis of the charger is performed, and the diagnosis result information is supplied to the memory 30 and / or the communication unit 31.

  The failure diagnosis unit 29 has a measurement function as in the conventional case, and calculates the remaining capacity of the battery 10 based on the voltage value of the battery 10. Moreover, the failure diagnosis unit 29 monitors the battery temperature based on the temperature information measured by the thermistor 26 and the circuit temperature measurement unit 27. Then, the failure diagnosis unit 29 supplies the calculated remaining capacity data and battery temperature data to the memory 30. Further, the failure diagnosis unit 29 has a protection function, and when the voltage of the battery 10 becomes an overcharge detection voltage or an overdischarge detection voltage, a charge / discharge permission / inhibition command is issued to the charge / discharge control unit 22. Sending prevents overcharge and overdischarge.

The memory 30 stores diagnosis result information, remaining capacity data, and battery temperature data received from the failure diagnosis unit 29. The memory 30, the initial circuit impedance _{Z init} for the first time measured in the case of preparing a BMU11 alone or battery pack 1 is stored. As such a memory 30, for example, an EEPROM (Electrically Erasable and Programmable Read Only Memory) which is a nonvolatile memory can be used.

  The charge / discharge control unit 22 controls the switch circuit 21 based on a charge / discharge permission / inhibition command. The switch circuit 21 performs ON / OFF of the switch based on the control from the charge control unit 22 and interrupts the charge / discharge current flowing through the current path.

  The communication unit 31 receives the diagnosis result information and the like received from the failure diagnosis unit 29 via a communication terminal 34 based on a predetermined communication standard, for example, an SMBus (System Management Bus) standard mainly used for power management. Supplied to external chargers and electronic devices. The communication unit 31 requests a charging condition such as a charging voltage and a charging current via the communication terminal 34 when charging, for example.

The battery pack 1 configured as shown in FIG. 1 can be realized by a circuit as shown in FIG. The battery pack 1 includes a battery 10 and a BMU 11, a positive terminal 32, a negative terminal 33, and a communication terminal 34. The BMU 11 includes a charge control FET (Field Effect Transistor) 41a, a discharge control FET 41b, parasitic diodes 42a and 42b, a thermal fuse 43, an FET / Tr ₁ , an MPU (Micro Processing Unit) 45, a current detection resistor 23, a thermistor 44a, 44b and resistors R ₁ , R ₂ , R ₃ , R ₄ .

The resistors R ₁ and R ₂ are connected in series, one end of the resistor R ₁ is connected to the positive terminal 32, and one end of the resistor R ₂ is connected to the negative terminal 33. A line extending from between the resistors R ₁ and R ₂ is connected to the MPU 45. Terminal voltage is measured on the basis of these resistors R ₁ and R _2.

The thermistor 44 a measures the temperature around the charge control FET 41 a and the discharge control FET 41 b described later, and the thermistor 44 b measures the temperature around the thermal fuse 43. The resistors R ₃ and R ₄ are resistors for improving the temperature characteristics in a predetermined temperature range in the thermistors 44 a and 44 b. These thermistors 44a and 44b and the resistors R ₃ and R ₄ constitute the thermistor 26 shown in FIG.

Thermistors 44a and resistor _{R 3} are connected in series, both ends of the thermistor 44a is connected to the MPU 45. One end of the resistor R ₃ is connected to the negative terminal 33. Similarly, the thermistor 44b and the resistor _{R 4} are connected in series, both ends of the thermistor 44b is connected to the MPU 45. One end of the resistor R ₄ is connected to the negative terminal 33.

  The MPU 45 has the functions of the charge / discharge control unit 22, the current measurement unit 24, the battery voltage measurement unit 25, the circuit temperature measurement unit 27, the terminal voltage measurement unit 28, the failure diagnosis unit 29, the memory 30 and the communication unit 31 shown in FIG. The charge / discharge current is measured based on the terminal voltage of the battery pack 1 as the first voltage, the voltage of the battery 10 as the second voltage, and the voltage applied to the current detection resistor 23 provided in the current path. To do. In addition, the MPU 45 generates temperature information based on the ambient temperature of each component measured by the thermistors 44a and 44b disposed in the vicinity of the charge control FET 41a, the discharge control FET 41b, and the temperature fuse 43.

  Then, the MPU 45 performs failure diagnosis of the components constituting the current path and the charger connected to the battery pack 1 based on the measured voltage value, current value, and temperature information, and the result of the failure diagnosis is transmitted to the communication terminal 34. To the externally connected charger or electronic device. Further, the MPU 45 requests charging conditions such as a charging voltage and a charging current via the communication terminal 34 when charging, for example.

  Further, the MPU 45 has a protection function, and controls the charge control FET 41a and the discharge control FET 41b to prevent overcharge and overdischarge when the voltage of the battery 10 becomes an overcharge detection voltage or an overdischarge detection voltage. .

  The charge control FET 41a and the discharge control FET 41b control charging / discharging of the battery pack 1 under the control of the MPU 45. For example, when the voltage of the battery 10 becomes an overcharge detection voltage, the MPU 45 controls the charge control FET 41a to be turned off so that no charging current flows. After the charge control FET 4a is turned off, only discharge is possible through the parasitic diode 42a. Further, when the voltage of the battery 10 becomes equal to or lower than the overdischarge detection voltage, the discharge control FET 41b is turned off by the control from the MPU 45 so that the discharge current does not flow. After the discharge control FET 41b is turned off, only charging is possible via the parasitic diode 42b. Further, the thermal fuse 43 is melted when it reaches a predetermined temperature, thereby interrupting the current flowing through the current path.

Further, the FET · Tr ₁ has a gate terminal connected to the MPU 45, a source terminal connected to the thermal fuse 43, and a drain terminal connected to the negative electrode side of the battery 10. The FET Tr ₁ is normally turned off, and is turned on by the control from the MPU 45 to blow the thermal fuse 43. For example, when charging / discharging the battery 10 is dangerous, the FET · Tr ₁ is turned on based on the control by the MPU 45. By doing so, the current flowing from the battery 10 flows to the GND via the temperature fuse 43 and the FET · Tr ₁ , and the temperature of the temperature fuse 43 rises and can be blown. Note that when the FET · Tr ₁ is OFF, no current flows through the FET · Tr ₁ , so the thermal fuse 43 is not blown. The charge control FET 41a, the discharge control FET 41b, the temperature fuse 43, and the FET · Tr ₁ constitute the switch circuit 21 shown in FIG.

  Next, a failure diagnosis method by failure diagnosis unit 29 of battery pack 1 according to the embodiment of the present invention will be described. In one embodiment of the present invention, circuit failure diagnosis is performed based on voltage values, current values, and the like measured by the respective measurement units provided in the battery pack 1.

  First, a method for diagnosing a circuit failure during charging or discharging will be described. When the circuit is operating normally during charging or discharging, both the charge control FET 41a and the discharge control FET 41b are ON. Therefore, in addition to the resistance component of the thermal fuse 43, the resistance component due to the ON resistance of the charge control FET 41a and the discharge control FET 41b exists in the current path. Therefore, such a resistance component becomes the main circuit impedance.

  Since the circuit impedance shows a substantially constant value when the circuit is operating normally, if this circuit impedance changes, it may be considered that some kind of failure has occurred in the components constituting the circuit. it can.

Therefore, in one embodiment of the present invention, when the battery pack 1 is charged or discharged, the failure diagnosis unit 29 is based on the terminal voltage of the battery pack 1, the battery voltage of the battery 10, the charge / discharge current, and the circuit temperature. Then, the circuit impedance Z of the battery pack 1 is calculated. Then, a change amount ΔZ of the circuit impedance is calculated based on the circuit impedance Z and the initial circuit impedance Z _init, and it is determined whether or not the circuit has failed according to the value of the change amount ΔZ.

A specific calculation method of the circuit impedance change amount ΔZ will be described. First, the failure diagnosis unit 29 uses the battery voltage V _b , the terminal voltage V _p, and the charge / discharge current I measured by the battery voltage measurement unit 25, the terminal voltage measurement unit 28, and the current measurement unit 24, and the equation (1) Based on this, the circuit impedance Z ′ is calculated.
Z ′ = | V _p −V _b | / I (1)

Here, the charge control FET 41a, the discharge control FET 41b, and the thermal fuse 43 have temperature characteristics, and the resistance component of each component varies depending on the temperature used. Therefore, when the circuit impedance is calculated as described above, the value of the circuit impedance Z ′ changes depending on the temperature at the time of measurement. Therefore, the calculated circuit impedance Z ′ is corrected by temperature, and the circuit impedance Z is calculated. The temperature correction of the circuit impedance Z ′ is performed by the equation (2).
Z = Z ′ × F (T) (2)

F (T) is a temperature correction formula for correcting the circuit impedance Z ′ according to the temperatures of the charge / discharge FETs 41a and 41b and the thermal fuse 43. For example, the circuit impedance Z ′ is expressed as the initial circuit impedance Z _init. Is corrected to a circuit impedance corresponding to the temperature at the time of measurement. The temperature correction formula is determined according to the temperature characteristics of the parts used in the circuit. Specifically, for example, the temperature correction formula may be determined based on the temperature characteristics of the charge / discharge FET 41 and the thermal fuse 43 measured by the thermistors 44a and 44b.

Next, the failure diagnosis unit 29 calculates a circuit impedance change amount ΔZ from the circuit impedance Z and the initial circuit impedance Z _init stored in the memory 30 in advance. The change amount ΔZ of the circuit impedance is calculated by Expression (3).
ΔZ = Z−Z _init (3)

  Table 1 shows an example of a circuit failure diagnosis result based on the value of the change amount ΔZ thus calculated. In this example, the determination method when the ON resistance of the charge control FET 41a and the discharge control FET 41b is 3 mΩ is shown.

  When the change amount ΔZ of the circuit impedance is smaller than −6 mΩ, it is determined that the circuit is malfunctioning. That is, since the circuit impedance Z is reduced by 6 mΩ or more which is the ON resistance of the charge control FET 41a and the discharge control FET 41b, for example, it may be considered that a part of the pattern wiring on the circuit board is short-circuited by solder or the like. it can.

  When the change amount ΔZ of the circuit impedance is −6 mΩ or more and −3 mΩ or less, it is determined that the circuit is malfunctioning. That is, in a state where both the charge control FET 41a and the discharge control FET 41b are ON, the circuit impedance Z is 3 mΩ or more which is one ON resistance of the charge control FET 41a and the discharge control FET 41b, and both ON resistances Therefore, for example, it can be considered that the charge control FET 41a and / or the discharge control FET 41b are short-circuited.

  When the change amount ΔZ of the circuit impedance is larger than −3 mΩ and smaller than 10 mΩ, it is determined that the circuit is normal. That is, since the circuit impedance Z is 10 mΩ or more and decreases by less than 3 mΩ, which is one of the ON resistances of the charge control FET 41a and the discharge control FET 41b, for example, impedance change due to measurement error or temperature correction error Can be considered. Here, as an example, the description will be made assuming that the allowable amount of the increase in impedance due to half-cutting of the thermal fuse 43 is 10 mΩ.

  When the change amount ΔZ of the circuit impedance is 10 mΩ or more, it is determined that the circuit has failed. That is, since the circuit impedance Z has increased more than 10 mΩ, it can be considered that the impedance has increased due to, for example, the thermal fuse 43 being cut halfway, so that it can be considered that the circuit has failed.

  Next, a circuit failure diagnosis method when charging or discharging is suspended will be described. When charging or discharging is suspended, there is no external electronic device connected to the battery pack 1 and no load is present, or an external electronic device is connected but not used. Therefore, the charge / discharge current I does not flow in the current path. Therefore, in this case, the circuit impedance Z cannot be calculated.

Therefore, in this case, in accordance with the ON / OFF state of the charging control FET41a and the discharge control FET 41b, to note whether the terminal voltage _{V p} is how to change. Then, based on the value of the difference between the terminal voltage _Vp and the power supply voltage _Vb , it is determined whether or not the circuit has failed.

| V _p −V _b | which is the difference between the terminal voltage V _p and the battery voltage V _b based on the terminal voltage V _p and the battery voltage V _b measured in the battery voltage measuring unit 25 and the terminal voltage measuring unit 28, respectively. Is calculated.

Table 2 shows an example of a determination method of circuit failure diagnosis based on the ON / OFF states of the charge control FET 41a and the discharge control FET 41b and the calculated | V _p −V _b |. In this example, the determination method in the case where the voltage drop of the parasitic diodes 42a and 42b of the charge control FET 41a and the discharge control FET 41b is 0.5V is shown.

When the charge control FET 41a and the discharge control FET 41b are both ON, and the value of | V _p −V _b | is 0 volts, it is determined that the circuit is normal. On the other hand, if the value of | V _p −V _b | is greater than 0 volts, it is determined that the circuit has failed. That is, the terminal voltage V _p becomes less V _b, it is considered to be the cause of voltage drop occurs in any portion of the circuit, for example, charge control FET41a and / or discharge control FET41b has failed Can be considered.

When the charge control FET 41a is ON and the discharge control FET 41b is OFF, if the value of | V _p −V _b | is V _b volts, it is determined that the circuit is normal. On the other hand, if the value of | V _p −V _b | is smaller than V _b volts, it is determined that the circuit is faulty. That is, since the value of _{V p} is greater than 0 volts, for example, the discharge control FET41b is such as are short-circuited, is considered to discharge control FET41b has failed.

When the charge control FET 41a is OFF and the discharge control FET 41b is ON, if the value of | V _p −V _b | is greater than 0.5 volts, it is determined that the circuit is normal. On the other hand, if the value of | V _p −V _b | is 0 volts, it is determined that the circuit is faulty. That is, the voltage drop due to the parasitic diode 42a of the charge control FET 41a does not occur, and it can be considered that the charge control FET 41a is out of order, for example, the charge control FET 41a is short-circuited.

When the charge control FET41a and the discharge control FET41b are both _{OFF, |} V p -V _{b |} value if a _{V b} V, it is determined that the circuit is normal. On the other hand, if the value of | V _p −V _b | is smaller than V _b volts, it is determined that the circuit is faulty. That is, if the value of V _p is greater than 0 volts, the charge control FET 41a and / or the discharge control FET 41b is out of order, for example, the charge control FET 41a and / or the discharge control FET 41b is short-circuited. Conceivable.

  Next, the flow of processing in failure diagnosis unit 29 at the time of failure diagnosis of battery pack 1 according to the embodiment of the present invention will be described using the flowchart shown in FIG. In the following, it is assumed that the process is performed by the failure diagnosis unit 29 unless otherwise specified.

First, in step S1, the terminal voltage measuring unit 28, the battery voltage measuring unit 25, the current measuring unit 24, and the circuit temperature measuring unit 27 are respectively connected to the terminal voltage V _p , the battery voltage V _b , the charging current I, and the charging control FET 41a. Then, the temperatures of the discharge control FET 41b and the thermal fuse 43 are measured, and the data measured by the respective measurement units is supplied to the failure diagnosis unit 29.

  Next, in step S2, the failure diagnosis unit 29 determines whether or not the charge / discharge current I is flowing in the current path. If it is determined that the charge / discharge current I is flowing, the process proceeds to step S3. If it is determined that the charge / discharge current I is not flowing, the process proceeds to step S5. To do.

In step S <b> 3, the failure diagnosis unit 29 calculates the circuit impedance Z of the battery pack 1 based on the various information measured in step S <b> 1, and the calculated circuit impedance Z and the circuit impedance stored in advance in the memory 30. based of the initial value _{Z init,} it calculates a change amount ΔZ of the circuit impedance. Next, in step S4, the failure diagnosis unit 29 performs failure diagnosis based on the circuit impedance change ΔZ calculated in step S3, and the process proceeds to step S7.

On the other hand, in step S5, the failure diagnosis unit 29 calculates | V _p −V _b | which is the difference between the terminal voltage V _p and the battery voltage V _b . In step S6, the failure diagnosis unit 29 performs failure diagnosis based on | V _p −V _b | calculated in step S5 and the ON / OFF states of the charge control FET 41a and the discharge control FET 41b. The process proceeds to S7.

  In step S7, the failure diagnosis unit 29 determines whether or not the circuit is abnormal based on the result of the failure diagnosis performed in step S4 or step S6. If the failure diagnosis unit 29 determines that there is no abnormality as a result of the determination, the process proceeds to step S10, and if it is determined that there is an abnormality, the process proceeds to step S8. In step S <b> 8, failure diagnosis unit 29 prohibits charging / discharging in battery pack 1. In step S <b> 9, the failure diagnosis unit 29 stores the diagnosis result in the memory 30.

  In step S10, the failure diagnosis unit 29 supplies the diagnosis result obtained in step S4 or step S6 to the communication unit 31, supplies the diagnosis result to an external electronic device connected via the communication terminal 34, and This process ends.

In this way, when charging or discharging, the circuit impedance Z of the battery pack 1 is calculated, and the change amount ΔZ from the initial circuit impedance Z _init is calculated, whereby the circuit or circuit is configured according to the value of ΔZ. It is possible to determine whether or not the part to be broken has failed.

When charging or discharging is suspended, by calculating | V _p −V _b |, the ON / OFF state of the charge control FET 41a and the discharge control FET 41b and the value of | V _p −V _b | Accordingly, it can be determined whether or not a part constituting the circuit is out of order.

Furthermore, in this embodiment, abnormality detection of the charger connected to the battery pack 1 can be performed. Abnormality detection of the charger, in a state where the battery pack 1 is connected to the charger is made based on the value of the ON / OFF state and the terminal voltage V _p of the charge control FETs 41a. And a detection result is supplied to a charger via the communication terminal 34, and the charging voltage and charging current for charge are requested | required according to a detection result.

An example of the abnormality detection of the detection result of the charger based on the ON / OFF state of the charging control FET41a and the terminal voltage _{V p} shown in Table 3. Note that V _charge and I _charge shown in Table 3 are determined by the number of battery cells used and the connection method, and V _charge indicates the allowable charge voltage per battery cell by the number of battery cells in series. Indicates what was multiplied. I _charge indicates a value obtained by multiplying the allowable charging current per battery cell by the number of parallel battery cells.

When the charge control FET41a is ON, the when the value of the terminal voltage _{V p} is greater than _{V charge,} it is determined that the charger is abnormal, with respect to the charger, the charging voltage is 0 volt, and, The charging process is requested so that the charging current becomes 0 amperes. That is, charging of the battery pack 1 is prohibited.

In addition, when the value of the terminal voltage _Vp is equal to or higher than _Vb and equal to or lower than _Vcharge, it is determined that the charger is normal, and the charging voltage is _Vcharge volts, The charging process is requested so that the charging current becomes I _charge ampere.

Further, when the value of the terminal voltage V _p is 0 volts or more, and, if less than V _b, it is determined that the charger is abnormal, with respect to the charger, the charging voltage is 0 volt, and, The charging process is requested so that the charging current becomes 0 amperes. That is, charging of the battery pack 1 is prohibited.

On the other hand, when the charge control FET41a is OFF, the when the value of the terminal voltage _{V p} is greater than _{V charge,} it is determined that the charger is abnormal, with respect to the charger, the charging voltage is 0 volts, In addition, the charging process is requested so that the charging current becomes 0 amperes. That is, charging of the battery pack 1 is prohibited.

Further, when the value of the terminal voltage _{V p} is equal to _{V charge,} it is determined that the charger is normal, with respect to the charger, the charging voltage _{V charge} volts, and the charge current is _{I charge} amps So that the charging process is requested.

Furthermore, the value of the terminal voltage V _p is 0 volts or more and is smaller than V _charge, it is determined that the charger is abnormal, with respect to the charger, the charging voltage is 0 volt, and, The charging process is requested so that the charging current becomes 0 amperes. That is, charging of the battery pack 1 is prohibited.

Thus, if the charger is connected to the battery pack 1, depending on the value of the ON / OFF state and the _{V p} of the charge control FET41a and the discharge control FET 41b, abnormality of the connected charger to the battery pack 1 Is detected and charging is prohibited, overcharging and overdischarging can be prevented in advance.

  Here, with reference to FIG. 4, the electronic apparatus 2 applicable to one embodiment of the present invention will be described. The electronic device 2 according to this embodiment is a chargeable / dischargeable device, and specifically, for example, a PC can be applied. The electronic device 2 includes a battery pack 1, an interface (hereinafter referred to as I / F) 51, a CPU (Central Processing Unit) 52, a RAM (Random Access Memory) 53, a ROM (Read Only Memory) 54, a display unit 55, An operation unit 56 is connected via the bus 50.

  The I / F 51 communicates with the connected battery pack 1 and supplies the failure diagnosis result supplied from the battery pack 1 to the CPU 52. Further, the I / F 51 supplies the battery pack 1 with a command related to charging / discharging of the battery pack 1 supplied from the CPU 52.

  The CPU 52 controls each unit connected to the bus 50 using the RAM 53 as a work memory in accordance with a program stored in advance in the ROM 54. Further, the CPU 52 controls charging / discharging of the battery pack 1 based on the failure diagnosis result supplied from the battery pack 1 via the I / F 51. Further, the CPU 52 generates failure information indicating a failure of the battery pack 1 based on the failure diagnosis result and supplies the failure information to the display unit 55.

  The display unit 55 is an output unit for displaying failure information supplied from the CPU 52. For example, a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or a PDP (Plasma Display Panel) is used as the display unit 55. The operation unit 56 includes, for example, a keyboard and a mouse, and outputs various types of information according to user operations and supplies the information to the CPU 52.

  When the battery pack 1 is attached to the electronic device 2, the communication terminal 34 of the battery pack 1 and the I / F 51 of the electronic device are connected. Then, the battery pack 1 transmits output data indicating a failure diagnosis result stored in advance in the memory 30 to the I / F 51 of the electronic device 2 via the communication terminal 34.

  The electronic device 2 supplies the obtained output data to the CPU 52. When the CPU 52 determines that the battery pack 1 has failed based on the supplied output data, the CPU 52 replaces the display 55 indicating that the battery pack 1 has failed, or replaces the battery pack 1. A display or the like for prompting is displayed to notify the user that the battery pack 1 is out of order. In addition, the electronic device 2 supplies a command for prohibiting charging / discharging based on the failure diagnosis result to the battery pack 1 via the I / F 51.

  Note that the method for notifying the user of the failure of the battery pack 1 is not limited to the above example. For example, an audio output unit is provided in the electronic device 2 to notify the user of the failure of the battery pack 1 by voice. May be. Further, for example, an LED (Light Emitting Diode) or the like is provided as the display unit 55 of the electronic device 2, and when the battery pack 1 is out of order, the LED is turned on or blinked to the user. A failure of the battery pack 1 may be notified.

  Further, for example, the content of the output data output from the battery pack 1 is made different according to the failure diagnosis result, and the electronic device 2 may perform different notifications or different processes according to the respective failure states. Good. For example, the electronic device 2 may notify the user of the failure location of the battery pack 1 based on the output data received from the battery pack 1.

  For example, when it is determined that the charge control FET has failed in the battery pack 1, the electronic device notifies the user that only discharge is possible based on the output data received from the battery pack 1, and discharge control is performed. When it is determined that the FET has failed, the electronic device may notify the user that only charging is possible based on the output data.

  As described above, in the embodiment of the present invention, the failure diagnosis of the charge / discharge control FET is performed based on the ON / OFF state of the charge / discharge control FET and the difference between the terminal voltage and the battery voltage. A failure of the charge / discharge control FET can be detected regardless of the ON / OFF state of the charge / discharge control FET.

  Further, in the conventional failure detection method, only the failure of the charge / discharge control FET can be detected, whereas in the embodiment of the present invention, not only the charge / discharge control FET but also the current is determined according to the value of the circuit impedance. It is possible to detect a failure of other parts constituting the route.

  Further, conventionally, the charger connected to the battery pack 1 at the time of charging fails, and for example, even when the charging voltage is abnormal, the charging operation is performed. In one embodiment, the abnormality of the charger can be detected by detecting the abnormality of the charger based on the ON / OFF state of the charge / discharge control FET and the value of the terminal voltage of the battery pack 1.

  The embodiment of the present invention has been specifically described above. However, the present invention is not limited to the above-described embodiment of the present invention, and various modifications can be made without departing from the gist of the present invention. Variations and applications are possible. For example, the value of the ON resistance of the charge control FET 41a and the discharge control FET 41b and the value of the voltage drop of the parasitic diodes 42a and 42b mentioned in the above-described embodiment are merely examples, and may be determined depending on the components used. Different numerical values may be used.

  In the above description, the failure diagnosis is performed for both the case where charging / discharging is performed and the case where charging / discharging is stopped, but this is not limited to this example. For example, the failure diagnosis may be performed only in one of the cases where charging / discharging is performed and charging / discharging is stopped.

  For example, the charge control FET 41a, the discharge control FET 41b, and the thermal fuse 43 are provided on the positive terminal side, but this is not limited to this example, and may be provided on the negative terminal side, for example. Furthermore, although the current detection resistor 23 is provided on the negative electrode terminal side, the current detection resistor 23 is not limited thereto, and may be provided on the positive electrode terminal side, for example.

  Furthermore, in the above description, the PC has been described as an example. However, the present invention is not limited to this. For example, as the electronic device 2, a camcorder (Camcorder: Camera and recorder), a portable electronic device such as a mobile phone or a PDA, a digital camera, etc. It is also possible to use it.

It is a block diagram which shows the structure of an example of the battery pack by one Embodiment of this invention. It is a basic diagram which shows the circuit structure of an example of the battery pack by one Embodiment of this invention. It is a flowchart which shows the flow of a process of the failure diagnosis method in the battery pack by one Embodiment of this invention. It is a basic diagram which shows the structure of an example of the electronic device by one Embodiment of this invention. It is a block diagram which shows the structure of an example of the conventional battery pack.

Explanation of symbols

1 battery pack 10 battery 11 BMU
21 switch circuit 22 charge / discharge control unit 23 current detection resistor 24 current measurement unit 25 battery voltage measurement unit 26 thermistor 27 circuit temperature measurement unit 28 terminal voltage measurement unit 29 fault diagnosis unit 30 memory 31 communication unit 32 positive electrode terminal 33 negative electrode terminal 34 communication Terminal 41a Charge control FET
41b Discharge control FET
42a, 42b Parasitic diode 43 Thermal fuse 44a, 44b Thermistor 45 MPU
51 Interface 52 CPU
55 Display

Claims (17)

One or more batteries connected in series and / or in parallel;
A charge control FET and a discharge control FET for controlling a charge / discharge current for the battery;
A detection unit that detects a first voltage that is a voltage of an electrode terminal connected to the outside and a second voltage that is a voltage of the one or more batteries;
A control unit for controlling the circuit based on the first voltage and the second voltage;
A communication unit that communicates with an external electronic device connected to the electrode terminal;
The control unit
When charging or discharging is not performed, depending on the ON / OFF state of the charge control FET and the discharge control FET and the difference between the first voltage and the second voltage, the communication unit is used. And controlling output data to be output to an external electronic device. The battery pack according to claim 1,
The control unit
When both the charge control FET and the discharge control FET are ON, and the difference is other than 0,
A case where the charge control FET is ON and the discharge control FET is OFF, and the difference is other than the value of the second voltage;
When the charge control FET is OFF and the discharge control FET is ON, and the difference is 0,
In the case where both the charge control FET and the discharge control FET are OFF, and the difference is other than the value of the second voltage, an external device is connected via the communication unit. A battery pack that outputs the output data to an electronic device. The battery pack according to claim 1,
The above output data is
A battery pack including information indicating that charging or discharging is requested to be stopped. The battery pack according to claim 1,
A storage unit for storing the initial circuit impedance detected at the time of manufacture;
A current detector for detecting the charge / discharge current;
The control unit
When one of charging and discharging is performed, circuit impedance is detected based on the first voltage, the second voltage, and the charge / discharge current detected by the current detection unit, and stored in the storage unit A battery pack that controls output data to be output to an external electronic device via the communication unit in accordance with a difference value between the initial circuit impedance and the circuit impedance. The battery pack according to claim 4,
The control unit
The battery pack, wherein the output data is output to an external electronic device via the communication unit when the difference value is outside a predetermined range. The battery pack according to claim 5,
The above output data is
A battery pack including information indicating that charging or discharging is requested to be stopped. The battery pack according to claim 1,
The control unit
When a charger is connected to the electrode terminal, output data output to the charger via the communication unit is controlled according to the ON / OFF state of the charge control FET and the first voltage. A battery pack characterized by that. The battery pack according to claim 7,
The control unit
When the charge control FET is ON, and the value of the first voltage is outside the range of the value of the charging voltage for charging the battery from the value of the second voltage;
In the case where the charge control FET is OFF and the value of the first voltage is other than the value of the charge voltage, the charger is connected to the charger via the communication unit. And outputting the output data. The battery pack according to claim 8, wherein
The above output data is
A battery pack comprising information indicating that charging is requested to be stopped. The battery pack according to claim 4,
A circuit temperature detector for detecting the temperature of the charge control FET and the discharge control FET;
The control unit
A battery pack that controls output data output to an external electronic device via the communication unit based on a detection result of the circuit impedance and a detection result of the temperature detection unit. The battery pack according to claim 1,
A battery pack comprising a storage unit for storing the output data. A charge control FET and a discharge control FET for controlling a charge / discharge current for a battery connected to the outside;
A detection unit for detecting a first voltage that is a voltage of a first electrode terminal connected to the outside and a second voltage that is a voltage of a second electrode terminal connected to the battery;
A control unit for controlling the circuit based on the first voltage and the second voltage;
A communication unit that communicates with an external electronic device connected to the first electrode terminal;
The control unit
When the battery is connected to the second electrode terminal and charging or discharging is not performed, the ON / OFF state of the charge control FET and the discharge control FET, the first voltage, and the second voltage A control circuit that controls output data output to an external electronic device via the communication unit in accordance with a voltage difference. The control circuit according to claim 12, wherein
The control unit
When both the charge control FET and the discharge control FET are ON, and the difference is other than 0,
A case where the charge control FET is ON and the discharge control FET is OFF, and the difference is other than the value of the second voltage;
When the charge control FET is OFF and the discharge control FET is ON, and the difference is 0,
In the case where both the charge control FET and the discharge control FET are OFF, and the difference is other than the value of the second voltage, an external device is connected via the communication unit. A control circuit for outputting the output data to an electronic device. The control circuit according to claim 13,
The above output data is
A control circuit including information indicating that a request to stop charging or discharging is included. An electronic device having a battery pack and charging / discharging the battery pack,
One or more batteries connected in series and / or in parallel;
A charge control FET and a discharge control FET for controlling a charge / discharge current for the battery;
A detection unit that detects a first voltage that is a voltage of a first electrode terminal connected to another device and a second voltage that is a voltage of the one or more batteries;
A first controller that controls the circuit based on the first voltage and the second voltage;
A battery pack comprising a first communication unit that communicates with the other device connected to the first electrode terminal;
A second electrode terminal connected to the first electrode terminal;
A second communication unit connected to the first communication unit to communicate with the battery pack and exchange the output data;
An output unit that outputs charge / discharge information indicating a charge / discharge state of the battery pack;
A charge / discharge control for the battery pack based on the output data, and a second control unit for controlling the output of the charge / discharge information by the output unit,
The first controller is
When charging or discharging is not performed, the first communication is performed according to the ON / OFF state of the charge control FET and the discharge control FET and the difference between the first voltage and the second voltage. An electronic apparatus that controls output data to be output to the second communication unit via the unit. A detection step of detecting a first voltage that is a voltage of an electrode terminal connected to the outside and a second voltage that is a voltage of one or a plurality of batteries connected in series and / or in parallel;
A control step for controlling the circuit based on the first voltage and the second voltage;
A communication step of communicating with an external electronic device connected to the electrode terminal,
The above control steps are:
When charging or discharging is not performed, depending on the ON / OFF state of the charge control FET and the discharge control FET for controlling the charge / discharge current, and the difference between the first voltage and the second voltage A control method comprising: controlling output data output to an external electronic device through the communication. A detection step of detecting a first voltage that is a voltage of a first electrode terminal connected to the outside and a second voltage that is a voltage of a second electrode terminal connected to an external battery;
A control step for controlling the circuit based on the first voltage and the second voltage;
A communication step of communicating with an external electronic device connected to the first electrode terminal,
The above control steps are:
When the battery is connected to the second electrode terminal and charging or discharging is not performed, the ON / OFF state of the charge control FET and the discharge control FET, the first voltage, and the second voltage A control method comprising: controlling output data output to an external electronic device by the communication according to a voltage difference.

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