JP2012010492A - Battery residual quantity notification circuit, battery pack, and electrical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery residual quantity notification circuit, a battery pack, and an electrical equipment capable of reducing a risk of charging a secondary battery before correcting full-charge capacity value resulting in missing an opportunity of correction when correcting the full-charge capacity value of the secondary battery.SOLUTION: A battery residual quantity notification circuit comprises: a correction part 503 performing correction of a full-charge capacity value FCC based on a terminal voltage value Vb when the residual quantity of a secondary battery 4 becomes a reference value Ref that is smaller than an alarm value Alm; and a notification part 504 notifying an apparatus body 3 of information relating to an integrated residual quantity as the residual quantity of the secondary battery 4 when the integrated residual quantity obtained by integrating charge-discharge current exceeds a notification determination value Aj that is larger than the alarm value Alm, and notifying the apparatus body 3 of the notification determination value Aj as the residual quantity of the secondary battery 4 during the period from when the integrated residual quantity becomes the notification determination value Aj following the discharge of the secondary battery 4 to when the correction part 503 performs correction.

Description

  The present invention relates to a battery remaining amount notification circuit for notifying the remaining amount of a secondary battery, and a battery pack and an electric device including the circuit.

  Conventionally, electronic devices such as portable personal computers, digital cameras, video cameras, mobile phones, vehicles such as electric cars and hybrid cars, hybrid elevators, power systems that combine solar batteries and power generators with secondary batteries, Secondary batteries are widely used in various devices and systems such as battery-mounted devices and systems such as uninterrupted power supply devices.

  For example, in an electric device such as a portable personal computer, from the viewpoint of usability, the remaining charge remaining in the secondary battery is displayed, or an alarm is issued before the battery runs out to prompt the user to charge. It is like that.

  Further, the remaining amount of the secondary battery is generally represented by SOC (State Of Charge), which is a ratio (percentage) of charge electricity to full charge capacity (FCC). The amount of electricity charged in the secondary battery is calculated by integrating the current flowing through the secondary battery. The SOC is calculated from the amount of charge electricity thus obtained and the full charge capacity value.

  However, since the full charge capacity of the secondary battery decreases as the secondary battery deteriorates, if the SOC is calculated using the full charge capacity value at the time of shipment as it is, the calculation error of the SOC becomes large. Therefore, a technique for calculating and correcting a full charge capacity value by calculating an integrated amount of discharge current from a fully charged state to a discharge end state is known (see, for example, Patent Document 1).

JP 2003-232839 A

  By the way, in an electric device that issues an alarm before the battery runs out and prompts the user to charge, the alarm is notified before the secondary battery reaches the end-of-discharge state, and the user charges the secondary battery. Therefore, the secondary battery is not discharged until the discharge end state. Therefore, the technique described in Patent Document 1 has a disadvantage that an opportunity to correct the full charge capacity value cannot be obtained.

  It is an object of the present invention to reduce the possibility that, when correcting the full charge capacity value of a secondary battery, the secondary battery is charged before the correction is performed and the opportunity for correction is lost. A battery remaining amount notification circuit, a battery pack, and an electric device are provided.

  The battery remaining amount notification circuit according to the present invention is a battery that notifies the device main body of an alarm that prompts charging of the secondary battery when the remaining amount of the secondary battery falls below a preset alarm value. A remaining amount notification circuit, a voltage detection unit for detecting a terminal voltage value of the secondary battery, a current detection unit for detecting a current value of a charge / discharge current flowing in the secondary battery, and detection by the current detection unit From the integrated value obtained by cumulatively adding and subtracting the amount of charge electricity in the secondary battery based on the charged / discharge current of the secondary battery, the remaining amount of the secondary battery A remaining amount calculation unit that calculates the accumulated remaining amount, a capacity storage unit that stores a full charge capacity value of the secondary battery, and a reference value in which the remaining amount of the secondary battery is set to a value smaller than the alarm value Is detected by the voltage detector. A correction unit that performs correction of the full charge capacity value stored in the capacity storage unit based on the terminal voltage value that has been set, and a notification determination value in which the accumulated remaining amount is set to a value greater than the alarm value Is exceeded, the information indicating the accumulated remaining amount is notified to the device main body as the remaining amount of the secondary battery, and the correction is made after the accumulated remaining amount becomes the notification determination value as the secondary battery is discharged. A notification unit that notifies the device main body of the notification determination value as the remaining amount of the secondary battery until the correction by the unit is executed.

  According to this configuration, when the integrated remaining amount calculated based on the integrated value of the current flowing through the secondary battery exceeds the notification determination value set to a value larger than the alarm value, the notification unit sets the integrated remaining amount. The information shown is notified to the device main body as the remaining amount of the secondary battery. Then, since the remaining amount of the secondary battery is larger than the alarm value, the device main body does not notify the alarm.

  Then, after the accumulated remaining amount decreases with the discharge of the secondary battery and becomes the notification determination value, the accumulated remaining amount becomes the reference value, and the correction unit stores the capacity based on the terminal voltage value of the secondary battery. Until the correction of the full charge capacity value stored in the unit is executed, the notification unit notifies the device main body of the notification determination value as the remaining amount of the secondary battery.

  Then, until the correction of the full charge capacity value is executed, a notification determination value larger than the alarm value is notified to the device body as the remaining amount of the secondary battery, so before the correction of the full charge capacity value is executed. The device body does not issue an alarm prompting the secondary battery to be charged. Thereby, the possibility that the secondary battery is charged before the full charge capacity value of the secondary battery is corrected and the opportunity for correction is lost is reduced.

  In addition, after the correction by the correction unit is performed, the notification unit displays information indicating the accumulated remaining amount until the accumulated remaining amount becomes the notification determination value again due to the discharge of the secondary battery. It is preferable to notify the device main body as the remaining amount of the secondary battery.

  According to this configuration, after the correction of the full charge capacity value by the correction unit is performed, information indicating the accumulated remaining amount is notified to the device main body as the remaining amount of the secondary battery. Then, the device body can issue an alarm for encouraging charging of the secondary battery based on the notified remaining battery level.

  It is preferable that the apparatus further includes a notification determination value setting unit that receives the alarm value from the device main body and sets the notification determination value to a value larger than the received alarm value.

  According to this configuration, even when the alarm value changes due to, for example, the device main body or the OS used in the device main body changing, the correct alarm value is acquired and the notification determination value is obtained. Can be set appropriately.

  In addition, a remaining amount estimation unit that estimates the remaining amount of the secondary battery as an estimated remaining amount based on the terminal voltage value detected by the voltage detection unit, the correction unit, the estimated remaining amount is It is preferable to execute the correction when the reference value is reached.

  The secondary battery has a property that the amount of change in the terminal voltage value with respect to the change in the remaining amount is larger in the region where the remaining amount is smaller than the region where the remaining amount is large. Therefore, according to this configuration, when the estimated remaining amount of the secondary battery estimated based on the terminal voltage value becomes a reference value set to a value smaller than the alarm value, that is, the remaining amount to promote charging. At the timing when the remaining amount is less than the level and therefore the amount of change in the terminal voltage value relative to the change in the remaining amount is considered sufficiently large, the correction unit corrects the full charge capacity value based on the terminal voltage value of the secondary battery Therefore, the correction accuracy of the full charge capacity value is improved.

  The correction unit may execute the correction when the accumulated remaining amount reaches the reference value. However, in this case, when the error of the accumulated remaining amount becomes large, the actual remaining amount of the secondary battery is large, and accordingly, the terminal voltage by the correction unit at a timing at which the change amount of the terminal voltage value with respect to the change of the remaining amount is considered small. The correction of the full charge capacity value based on the value may be executed, and the correction accuracy of the full charge capacity value may be lowered. Therefore, it is more preferable that the correction unit performs correction when the estimated remaining amount reaches the reference value.

  In addition, when the estimated remaining amount becomes the reference value, the correction unit calculates a difference electric quantity corresponding to a difference between the estimated remaining amount and the accumulated remaining amount from the accumulated remaining amount. When there is more, it adds to the full charge capacity value memorize | stored in the said capacity | capacitance memory | storage part, and when the said estimated remaining capacity is smaller than the said accumulation | storage remaining capacity, the full charge capacity value memorize | stored in the said capacity memory | storage part It is preferable to subtract from the correction.

  According to this configuration, the estimated remaining amount of the secondary battery estimated using the integrated value obtained by cumulatively adding the charged electricity amount and subtracting the discharged electricity amount and the terminal voltage value of the secondary battery. The amount of difference electricity, which is the difference from the amount, is considered to correspond to the amount of change in the full charge capacity value, so by correcting the full charge capacity value using the difference amount of electricity, the actual amount accompanying the deterioration of the secondary battery The full charge capacity value stored in the capacity storage unit can be corrected according to the decrease in the full charge capacity.

  Further, the reference value is represented by Ref as a percentage of the full charge capacity value of the secondary battery, Qd as a difference electric quantity corresponding to a difference between the estimated remaining amount and the accumulated remaining amount, and the capacity storage unit. When the full charge capacity value stored in FC is FCC, the correction unit, when the estimated remaining amount becomes the reference value, if the estimated remaining amount is greater than the accumulated remaining amount, A full charge capacity value FCCn is calculated based on A), and if the estimated remaining capacity is less than the accumulated remaining capacity, the full charge capacity value FCCn is calculated based on the following formula (B), and thus calculated. The full charge capacity value FCCn may be stored in the capacity storage unit as a new full charge capacity value FCC to correct the full charge capacity value.

FCCn ← FCC + | Qd | × 100 / (100−Ref) (A)
FCCn ← FCC- | Qd | × 100 / (100-Ref) (B)
The difference electric quantity Qd is considered to be a difference generated by discharging the secondary battery 4 from the fully charged state where the SOC of the secondary battery reaches 100% to the reference value Ref. On the other hand, ideally, the difference electric quantity Qd generated when the SOC is discharged from the fully charged state of 100% to the end of discharge state of 0% is used as the full charge capacity value FCC stored in the capacity storage unit. Is added or subtracted, the correction accuracy of the full charge capacity value FCC is the highest.

  Therefore, according to this configuration, the absolute value of the difference electric quantity Qd when the estimated remaining amount becomes the reference value Ref is multiplied by 100 / (100−Ref), so that the difference electric quantity Qd is 100%. Is converted into a difference electric quantity Qd obtained by an ideal discharge from 0 to 0%, and the converted value is added or subtracted as shown in the equations (A) and (B), so that the full charge capacity value FCC Correction accuracy can be improved.

  The remaining amount calculation unit preferably calculates the SOC of the secondary battery as the accumulated remaining amount based on a full charge capacity value stored in the capacity storage unit and the integrated value.

  According to this configuration, the remaining amount calculation unit calculates the accumulated remaining amount of the secondary battery as the SOC based on the full charge capacity value and the accumulated value stored in the capacity storage unit. When the correction of the full charge capacity value is executed, the accuracy of the SOC calculated by the remaining amount calculation unit is improved.

  A battery pack according to the present invention includes the above-described battery remaining amount notification circuit and the secondary battery.

  An electric device according to the present invention includes the above-described battery remaining amount notification circuit, the secondary battery, and the device main body.

  According to the battery pack and the electric device having such a configuration, when the full charge capacity value of the secondary battery is corrected, an alarm is notified in the device main body before the correction is performed, and the user receives the secondary battery. By performing this charging operation, it is possible to reduce the possibility that the secondary battery is charged and the opportunity for correction is lost.

  The battery remaining amount notification circuit, the battery pack, and the electric device having such a configuration, when correcting the full charge capacity value of the secondary battery, charge the secondary battery before the correction is performed. The possibility that opportunities will be lost can be reduced.

It is a block diagram which shows an example of a structure of a battery pack and an electric equipment provided with the battery residual amount notification circuit which concerns on one Embodiment of this invention. It is explanatory drawing which shows an example of the lookup table memorize | stored in the table memory | storage part shown in FIG. It is a graph which shows an example of the relationship between OCV and SOC of a lithium ion secondary battery. 3 is a flowchart illustrating an example of an operation of a battery remaining amount notification circuit illustrated in FIG. 1. It is explanatory drawing for demonstrating an example of operation | movement of the battery remaining charge notification circuit shown in FIG.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. FIG. 1 is a block diagram showing an example of the configuration of a battery pack 2 and an electric device 1 including a battery remaining amount notification circuit 5 according to an embodiment of the present invention. The electric device 1 shown in FIG. 1 is configured by combining a battery pack 2 and a device main body 3.

  The electric device 1 is an electric device such as a portable personal computer, a digital camera, an electronic device such as a mobile phone, or a vehicle such as an electric vehicle or a hybrid car. And the apparatus main body 3 is a main-body part of these electric devices, for example, and the load circuit 34 is a load circuit which operate | moves by the electric power supply from the battery pack 2 in these electric devices.

  The battery pack 2 includes a secondary battery 4, a remaining battery level notification circuit 5, a current detection resistor 6, a temperature sensor 7, switching elements Q 1 and Q 2, and connection terminals 11, 12, and 13. The battery remaining amount notification circuit 5 includes a control unit 50, a voltage detection unit 51, a current detection unit 52, a temperature detection unit 53, and a communication unit 54.

  Note that the electric device 1 is not necessarily limited to the battery pack 2 and the device main body 3 that are separable, and the entire electric device 1 may include one battery remaining amount notification circuit 5. Further, the battery remaining amount notification circuit 5 may be shared between the battery pack 2 and the device body 3. The secondary battery 4 does not need to be a battery pack. For example, the battery remaining amount notification circuit 5 may be configured as an in-vehicle ECU (Electric Control Unit).

  The device body 3 includes connection terminals 31, 32, 33, a load circuit 34, a charging unit 35, a communication unit 36, a control unit 37, and a display unit 38. The charging unit 35 is connected to power supply connection terminals 31 and 32, and the communication unit 36 is connected to the connection terminal 33.

  When the battery pack 2 is attached to the device main body 3, the connection terminals 11, 12, 13 of the battery pack 2 and the connection terminals 31, 32, 33 of the device main body 3 are connected to each other. Yes.

  The communication units 54 and 36 are communication interface circuits configured to be able to transmit / receive data to / from each other via the connection terminals 13 and 33.

  The charging unit 35 is a power supply circuit that supplies current and voltage according to a control signal from the control unit 37 to the battery pack 2 via the connection terminals 31 and 32. The charging unit 35 may be, for example, a power supply circuit that generates a charging current for the battery pack 2 from a commercial power supply voltage. For example, a power generation device that generates power based on natural energy such as sunlight, wind power, or hydropower, an internal combustion engine, or the like A power generation device that generates power by motive power may be used.

  As the display unit 38, for example, a liquid crystal display or an LED (Light Emitting Diode) is used. For example, when the device body 3 is an electronic device such as a portable personal computer or a digital camera, a display device such as a liquid crystal display provided in the electronic device may be used as the display unit 38.

  The control unit 37 is a control circuit configured using, for example, a microcomputer. For example, when the user performs an operation for charging the secondary battery 4 with respect to the electric device 1, the control unit 37 requests the control unit 50 to start charging via the communication unit 36. For example, when the request instruction transmitted from the control unit 50 in the battery pack 2 by the communication unit 54 is received by the communication unit 36, the control unit 37 receives the request instruction received by the communication unit 36. By controlling the charging unit 35 according to the above, the secondary battery 4 is charged by causing the charging unit 35 to output current and voltage corresponding to the request instruction transmitted from the battery pack 2 to the connection terminals 11 and 12. .

  Further, the control unit 37 receives from the battery remaining amount notification circuit 5 via the communication unit 36 RSOC (Relative State Of Charge) that is information indicating the remaining amount of the secondary battery 4. Then, when the RSOC falls below a preset alarm value Alm, the control unit 37 notifies an alarm for prompting the user to charge by the display unit 38.

  The alarm notification is executed by causing the display unit 38 to emit light, for example, an LED, or to display a message “please charge” on the liquid crystal display, for example.

  The control unit 37 executes an OS (Operating System) such as Windows (registered trademark) stored in an HDD (Hard Disk Drive) (not shown), for example. Such an OS has a power management function, and an initial value of the alarm value Alm is set in advance by the OS. Therefore, when such a general-purpose OS is used, even the manufacturer of the electric device 1 cannot freely set the initial value of the alarm value Alm. The alarm value Alm is set to 10%, for example.

  For example, at the time of activation, the control unit 37 causes the communication unit 36 to transmit the alarm value Alm to the battery remaining amount notification circuit 5.

  In the battery pack 2, the connection terminal 11 is connected to the positive electrode of the secondary battery 4 via the switching element Q2 and the switching element Q1. As the switching elements Q1 and Q2, for example, p-channel FETs (Field Effect Transistors) are used.

  Switching elements Q1, Q2 each have a parasitic diode. And the parasitic diode of the switching element Q2 is arrange | positioned so that the direction (direction which goes to the connecting terminal 11 from the positive electrode of the secondary battery 4) the discharge current of the secondary battery 4 may become a forward direction. Thereby, the switching element Q2 cuts off only the current in the charging direction of the secondary battery 4 (the direction from the connection terminal 11 to the positive electrode of the secondary battery 4) when turned off.

  In addition, the parasitic diode of the switching element Q1 is arranged in a direction in which the charging current flows in the secondary battery 4 in the forward direction. Thereby, the switching element Q1 cuts off only the current in the discharge direction of the secondary battery 4 when turned off. The switching elements Q1, Q2 are normally turned on, and are turned off at the time of abnormality to protect the secondary battery 4.

  The connection terminal 12 is connected to the negative electrode of the secondary battery 4 through the current detection resistor 6, and the connection terminal 11 passes through the switching element Q 2, the switching element Q 1, the secondary battery 4, and the current detection resistor 6. Thus, a current path to the connection terminal 12 is configured.

  The connection terminals 11, 12, 13, 31, 32, and 33 may be any terminals that electrically connect the battery pack 2 and the device body 3, and may be electrodes, connectors, terminal blocks, and the like. Alternatively, a wiring pattern such as a land or a pad may be used.

  The current detection resistor 6 is a so-called shunt resistor for current detection, and converts the charging current and discharging current of the secondary battery 4 into voltage values. Instead of the current detection resistor 6, for example, a current detection element such as a current transformer or a Hall element may be used.

  The temperature sensor 7 is configured using, for example, a thermosensitive element such as a thermistor or a thermocouple, and is disposed in close contact with, for example, the secondary battery 4 or in the vicinity of the secondary battery 4. Then, the temperature sensor 7 outputs a voltage signal indicating the temperature t of the secondary battery 4 to the temperature detection unit 53.

  The secondary battery 4 may be, for example, a single battery, for example, an assembled battery in which a plurality of secondary batteries are connected in series, for example, an assembled battery in which a plurality of secondary batteries are connected in parallel. Alternatively, an assembled battery in which series and parallel are combined and connected may be used. As the secondary battery 4, for example, a lithium ion secondary battery is used. The secondary battery 4 is not limited to a lithium ion secondary battery, and various secondary batteries such as a nickel hydride secondary battery and a nickel cadmium secondary battery can be used.

  However, since the remaining amount estimation unit 502 described later estimates the remaining amount (estimated remaining amount Qe, estimated remaining amount SOCe) of the secondary battery 4 based on the terminal voltage value Vb of the secondary battery 4, the nickel metal hydride secondary battery A lithium ion secondary battery having a larger amount of change in terminal voltage with respect to a change in the remaining amount of the secondary battery 4 is more suitable as the secondary battery 4 than a nickel cadmium secondary battery.

  The voltage detection unit 51 is configured using, for example, an analog-digital converter, detects the terminal voltage (inter-terminal voltage) of the secondary battery 4, and outputs a signal indicating the terminal voltage value Vb to the control unit 50.

  The current detection unit 52 is configured by using, for example, an analog-digital converter, detects the voltage Vr between both ends of the current detection resistor 6, and outputs a current value Ic flowing through the secondary battery 4 as a signal indicating the voltage Vr. It outputs to the control part 50 as information to show. Further, the current detection unit 52 represents the information (voltage Vr) indicating the current value Ic by, for example, expressing the direction in which the secondary battery 4 is charged as a positive value and the direction in which the secondary battery 4 is discharged as a negative value. It has become.

  In the control unit 50, the current value Ic flowing through the secondary battery 4 is obtained by dividing the voltage Vr by the resistance value R of the current detection resistor 6.

  The temperature detection unit 53 is configured using, for example, an analog-digital converter, converts the voltage signal output from the temperature sensor 7 into a digital value, and outputs the digital value to the control unit 50 as a signal indicating the temperature t.

  The control unit 50 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) that stores a predetermined control program, and a RAM (Random Access Memory) that temporarily stores data. And a capacity storage unit 505 configured using, for example, an EEPROM (Electrically Erasable and Programmable Read Only Memory), a table storage unit 506 configured using, for example, a ROM, and peripheral circuits thereof. ing.

  The control unit 50 functions as a notification determination value setting unit 500, a remaining amount calculation unit 501, a remaining amount estimation unit 502, a correction unit 503, and a notification unit 504 by executing a control program stored in the ROM. .

  In the capacity storage unit 505, a full charge capacity value FCC (Full Charge Capacity) as an initial value is stored in advance when the battery pack 2 is shipped, for example. As the initial value of the full charge capacity value FCC, for example, a value measured by theoretical calculation or actual measurement is stored in advance. In addition, the full charge capacity value FCC stored in the capacity storage unit 505 is appropriately corrected by the correction unit 503.

  The table storage unit 506 includes a lookup table LT that associates the SOC of the secondary battery 4, the current value Ic flowing through the secondary battery 4, and the temperature t of the secondary battery with the terminal voltage value Vb of the secondary battery 4. Stored in advance.

  FIG. 2 is an explanatory diagram showing an example of the lookup table LT stored in the table storage unit 506 shown in FIG. FIG. 2A shows a correspondence relationship between the terminal voltage value Vb (V11a to V54a), the current value Ic of the secondary battery 4 and the temperature t of the secondary battery 4 when the SOC is 95%. Yes. The current value Ic indicates a charging direction with a positive value and a discharging direction with a negative value. FIG. 2B shows a correspondence relationship between the terminal voltage value Vb (V11b to V54b), the current value Ic of the secondary battery 4 and the temperature t of the secondary battery 4 when the SOC is 50%. Yes. FIG. 2C shows a correspondence relationship between the terminal voltage value Vb (V11c to V54c), the current value Ic, and the temperature t of the secondary battery 4 when the SOC is 5%.

  The lookup table LT shown in FIG. 2 is configured by storing data experimentally measured using, for example, a new secondary battery 4 in a ROM in advance. In FIG. 2, the lookup table LT corresponding to SOC of 95%, 50%, and 5% is illustrated, but the table storage unit 506 corresponds to the entire range of SOC from 0% to 100%. A lookup table LT is stored.

  Here, as the remaining amount of the secondary battery 4 is larger, that is, as the SOC is larger, the terminal voltage value Vb becomes higher. Therefore, under the conditions where the current value Ic and the temperature t do not change, FIG. In b) and (c), the relationship is V ** a> V ** b> V ** c (* is an arbitrary character).

  When a current flows through the secondary battery 4, the terminal voltage value Vb increases as the current value Ic increases due to the voltage generated by the internal resistance of the secondary battery 4. That is, the charging current increases during charging, and the terminal voltage value Vb increases as the current value Ic increases. On the other hand, during discharge, the current in the discharge direction decreases and the absolute value of the negative current value Ic decreases, that is, the terminal voltage value Vb increases as the current value Ic increases (the amount of decrease in the terminal voltage value Vb). Less). Accordingly, in FIGS. 2A, 2B, and 2C, V1 **> V2 **> V3 **> V4 **> V5 ** (*) under the condition that the SOC and the temperature t do not change. Is an arbitrary character).

  Further, the correspondence relationship between the remaining amount (SOC) of the secondary battery 4 and the terminal voltage value Vb varies depending on the temperature t. Generally, the higher the temperature t, the lower the terminal voltage value Vb corresponding to the same remaining amount (SOC). Therefore, in FIGS. 2A, 2B, and 2C, under conditions where the SOC and the current value Ic do not change, V * 1 *> V * 2 *> V * 3 *> V * 4 * ( * Is an arbitrary character).

  Depending on the materials constituting the positive and negative electrodes of the battery, the terminal voltage value Vb corresponding to the same remaining amount (SOC) may increase as the temperature t increases. Therefore, the relationship of V * 1 *, V * 2 *, V * 3 *, and V * 4 * in FIGS. 2A, 2B, and 2C is appropriately set according to the characteristics of the secondary battery 4. do it.

  The lookup table LT shown in FIG. 2 associates the SOC, the terminal voltage value Vb, the current value Ic flowing through the secondary battery 4, and the temperature t of the secondary battery 4, but the lookup table LT The LT may not include the temperature t of the secondary battery 4 as a parameter. Further, the look-up table LT may not include the temperature t and the current value Ic as parameters.

  The remaining amount calculation unit 501 calculates the remaining amount of electricity charged in the secondary battery 4 as the integrated remaining amount Qa by integrating the current value Ic detected by the current detection unit 52 every unit time. In this case, the current value Ic is represented by a positive current in the direction in which the secondary battery 4 is charged and a negative current in the direction in which the secondary battery 4 is discharged. The amount of charged electricity charged in the battery 4 is added and the amount of discharged electricity discharged from the secondary battery 4 is subtracted to calculate the accumulated remaining amount Qa charged in the secondary battery 4.

  In addition, the remaining amount calculation unit 501 determines the ratio (percentage) of the accumulated remaining amount Qa to the full charge capacity value FCC stored in the capacity storage unit 505 as an accumulated remaining amount that is an SOC (State Of Charge) corresponding to the remaining amount. Calculated as the amount SOCa. Thereby, the remaining amount calculation unit 501 represents the accumulated remaining amount by SOC.

  The accumulated remaining amount SOCa is given by the following equation (1). The remaining amount calculation unit 501 may use the accumulated remaining amount Qa as it is as the remaining amount of the battery.

SOCa = (Qa / FCC) × 100 (%) (1)
The remaining amount estimation unit 502 uses the terminal voltage value Vb detected by the voltage detection unit 51, the current value Ic detected by the current detection unit 52, and the temperature t detected by the temperature detection unit 53 to use the secondary battery. The remaining amount of 4 is estimated as the estimated remaining amount SOCe. Then, the remaining amount estimating unit 502 may use the estimated remaining amount Qe as the estimated remaining amount by converting the estimated remaining amount SOCe into an electrical quantity.

For example, a value of 5.5% is set in advance as the reference value Ref. FIG. 3 is a graph showing an example of the relationship between OCV (Open circuit voltage) and SOC of a lithium ion secondary battery using LiFePO ₄ as a positive electrode active material. In the example shown in FIG. 3, the change amount of the OCV, that is, the terminal voltage value Vb with respect to the change of the SOC is large in the region where the SOC is 10% or less, and small in the region where the SOC exceeds 10%.

  As described above, the secondary battery 4 includes the first region in which the change amount of the terminal voltage value Vb with respect to the change in SOC is large, and the region in which the change amount of the terminal voltage value Vb with respect to the change in SOC is smaller than the first region. There is a second region. In FIG. 3, a region where the SOC is less than 10% corresponds to the first region, and a region where the SOC is 10% or more corresponds to the second region.

  Then, the estimation accuracy of the estimated remaining amount SOCe is improved by estimating the estimated remaining amount SOCe in the first region, rather than estimating the estimated remaining amount SOCe in the second region. Therefore, the reference value Ref is set to 5.5%, for example, as a value belonging to the first area.

  On the other hand, as described above, the alarm value Alm is set to a value of 10%, for example, and in many cases, the value of the second region is set. Therefore, when the value of the first area is set as the reference value Ref, the SOC value smaller than the alarm value Alm is set as the reference value Ref.

  Specifically, the remaining amount estimation unit 502 determines whether the combination of the terminal voltage value Vb, the current value Ic, and the temperature t corresponds to the terminal voltage value Vb, the current value Ic, and the temperature t that are associated in the lookup table LT. When substantially matching the combination, the SOC associated with the terminal voltage value Vb, the current value Ic, and the temperature t by the lookup table LT is set as the amount of electricity charged in the secondary battery 4 as the SOC. Is estimated as the estimated remaining amount SOCe.

  Here, in the lookup table LT, the terminal voltage value Vb and the SOC are associated with each other so that the SOC of the secondary battery 4 increases as the terminal voltage value Vb increases. As the terminal voltage value Vb increases, the estimated remaining amount SOCe is increased.

  In the lookup table LT, the current value Ic and the terminal voltage value are such that the current value Ic increases with respect to the same SOC, that is, the terminal voltage value Vb increases as the current value Ic increases in the charging direction. Vb is associated. In the lookup table LT, the current value Ic and the terminal voltage are set such that the discharge current decreases with respect to the same SOC, that is, the terminal voltage value Vb increases as the absolute value of the current value Ic decreases in the discharge direction. The value Vb is associated.

  Therefore, the remaining amount estimation unit 502 collates the current value Ic detected by the current detection unit 52 and the terminal voltage value Vb detected by the voltage detection unit 51 with the lookup table LT, so that the current value Ic increases. The estimated remaining amount SOCe is estimated so as to decrease the estimated remaining amount SOCe, that is, the charging current increases and the estimated remaining amount SOCe decreases as the discharge current decreases.

  Also, since the temperature t and the terminal voltage value Vb are associated with each other in the look-up table LT so that the terminal voltage value Vb decreases as the temperature t increases with respect to the same SOC, the remaining amount estimation unit When the temperature t detected by the temperature detection unit 53 and the terminal voltage value Vb detected by the voltage detection unit 51 are collated with a lookup table LT, 502 increases the estimated remaining amount SOCe as the temperature t increases. In addition, the estimated remaining amount SOCe is estimated.

  Thus, the lookup table LT includes a plurality of parameters correlated with the SOC (remaining amount) of the secondary battery 4, the terminal voltage value Vb, the current value Ic, the temperature t, and the SOC of the secondary battery 4. Are associated with each other, the influence of the current value Ic and the temperature t is reduced from the estimated remaining amount SOCe. As a result, the remaining amount estimating unit 502 can estimate the estimated remaining amount SOCe with high accuracy.

  Then, the remaining amount estimating unit 502 calculates an estimated remaining amount Qe in which the estimated remaining amount is expressed as an electric quantity using the following equation (2).

Qe = (SOCe × FCC) / 100 (2)
Note that the look-up table LT may represent the set remaining amount in terms of electricity, and in this case, the remaining amount estimation unit 502 uses the set amount of electricity obtained in the look-up table LT as the estimated remaining amount. It may be Qe.

  By the way, the values set in the lookup table LT are discrete values, whereas the terminal voltage value Vb detected by the voltage detection unit 51, the current value Ic detected by the current detection unit 52, and The temperature t detected by the temperature detector 53 changes continuously. For this reason, the remaining amount estimating unit 502 collates the terminal voltage value Vb, the current value Ic, and the temperature t with the lookup table LT after performing an approximation process such as rounding off or rounding off, for example. ing.

  “Substantially match” means that the terminal voltage value Vb detected by the voltage detection unit 51, the current value Ic detected by the current detection unit 52, and the temperature t detected by the temperature detection unit 53 are as described above. For example, it means that the result of approximation processing such as rounding off or rounding off includes matching.

  The remaining amount estimation unit 502 is not limited to the example in which the remaining amount of the secondary battery 4 is estimated using the terminal voltage value Vb, the current value Ic, and the temperature t, and is estimated using only the terminal voltage value Vb. Alternatively, it may be estimated using the terminal voltage value Vb and the current value Ic, or the remaining amount of the secondary battery 4 may be estimated using the terminal voltage value Vb and the temperature t.

  When the estimated remaining amount SOCe estimated by the remaining amount estimating unit 502 reaches the reference value Ref, the correcting unit 503 includes the estimated remaining amount Qe and the accumulated remaining amount Qa calculated by the remaining amount calculating unit 501. Is added to the full charge capacity value FCC stored in the capacity storage section 505.

  That is, when the estimated remaining amount Qe is larger than the accumulated remaining amount Qa, the absolute value of (Qe−Qa) is added to the full charge capacity value FCC stored in the capacity storage unit 505, and the accumulated remaining amount Qa When the estimated remaining amount Qe is smaller, the full charge capacity value FCC is corrected by subtracting the absolute value of (Qe−Qa) from the full charge capacity value FCC stored in the capacity storage unit 505.

  Specifically, the correction unit 503 corrects the full charge capacity value FCC using the following equation (3).

New FCC ← Current FCC + (Qe-Qa) (3)
The correction unit 503 may correct the full charge capacity value FCC using equation (3) when the integrated remaining amount SOCa calculated by the remaining amount calculation unit 501 becomes the reference value Ref. However, when the full charge capacity value FCC is corrected when the integrated remaining amount SOCa reaches the reference value Ref, if the error of the integrated remaining amount SOCa is large, the estimated remaining amount SOCe is 10% or more, that is, the estimated remaining amount. When SOCe is the value of the second area, there is a possibility that correction is executed. Then, as described above, the estimation accuracy of the estimated remaining amount SOCe is reduced, and as a result, the correction accuracy of the full charge capacity value FCC is reduced.

  Therefore, it is more desirable that the correction unit 503 performs correction when the estimated remaining amount SOCe reaches the reference value Ref.

  The correction unit 503 may correct the full charge capacity value FCC based on the terminal voltage value Vb, and may correct the full charge capacity value FCC by any method. For example, when the estimated remaining amount SOCe estimated by the remaining amount estimating unit 502 reaches the reference value Ref, the correcting unit 503 uses the following formula (A) if the estimated remaining amount Qe is greater than the accumulated remaining amount Qa. Based on the following formula (B), the full charge capacity value FCCn is calculated based on the following formula (B), and the full charge capacity value FCCn is calculated based on the following formula (B). The full charge capacity value FCC may be corrected by storing the capacity value FCCn in the capacity storage unit 505 as a new full charge capacity value FCC.

FCCn ← FCC + | Qd | × 100 / (100−Ref) (A)
FCCn ← FCC- | Qd | × 100 / (100-Ref) (B)
The difference electric quantity Qd is considered to be a difference generated by discharging the secondary battery 4 from the fully charged state where the SOC is 100% to the reference value Ref. On the other hand, ideally, the differential charge quantity Qd generated when the SOC is discharged from the fully charged state of 100% to the end of discharge state of 0% is the full charge capacity value stored in the capacity storage unit 505. When added to or subtracted from FCC, the correction accuracy of full charge capacity value FCC is the highest.

  Therefore, by multiplying the absolute value of the difference electric quantity Qd when the estimated remaining amount SOCe becomes the reference value Ref by 100 / (100−Ref), the difference electric quantity Qd is reduced from 100% to 0%. By converting to the difference electric quantity Qd obtained by ideal discharge and adding or subtracting the converted value as shown in the equations (A) and (B), the correction accuracy of the full charge capacity value FCC is improved. be able to.

  When the full charge capacity value FCC is corrected based on the expressions (A) and (B), the larger the reference value Ref, the larger the value of 100 / (100−Ref), and the difference electric quantity Qd The magnification increases. When the magnification of the difference electric quantity Qd increases, the error included in the difference electric quantity Qd also increases. Therefore, if the reference value Ref is set to a value larger than the alarm value Alm, the error included in the difference electric quantity Qd is enlarged, and the correction accuracy of the full charge capacity value FCC is lowered.

  The notification determination value setting unit 500 receives the alarm value Alm transmitted from the control unit 37. Then, the notification determination value setting unit 500 calculates the notification determination value Aj, for example, by adding “1%” or multiplying by “1.1” to the alarm value Alm. Thus, the notification determination value setting unit 500 sets a value larger than the alarm value Alm as the notification determination value Aj.

  When the accumulated remaining amount SOCa exceeds the notification determination value Aj, the notification unit 504 causes the communication units 54 and 36 to transmit information indicating the accumulated remaining amount SOCa to the control unit 37 as RSOC that is the remaining amount of the secondary battery 4. . Thereby, in the control part 37, it becomes possible to grasp | ascertain the residual amount of the secondary battery 4. FIG.

  Further, the notification unit 504 performs correction by the correction unit 503 after the accumulated remaining amount SOCa becomes the notification determination value Aj and the estimated remaining amount SOCe becomes the reference value Ref as the secondary battery 4 is discharged. In the meantime, the notification determination value Aj is transmitted to the control unit 37 by the communication units 54 and 36 as the RSOC of the secondary battery 4.

  Next, the operation of the battery remaining amount notification circuit 5 shown in FIG. 1 will be described. FIG. 4 is a flowchart showing an example of the operation of the battery remaining amount notification circuit 5 shown in FIG. FIG. 5 is an explanatory diagram for explaining an example of the operation of the battery remaining amount notification circuit 5 shown in FIG. In FIG. 5, the horizontal axis indicates the passage of time, and the vertical axis indicates RSOC (Relative State Of Charge) transmitted to the device body 3 as information indicating the remaining amount of the secondary battery 4 by the notification unit 504.

  First, when the electric device 1 is activated, an alarm value Alm set to, for example, 10% is transmitted from the control unit 37 to the control unit 50, and the alarm value Alm is received by the notification determination value setting unit 500 ( Step S1).

  Next, for example, 1% is added to the alarm value Alm by the notification determination value setting unit 500 to calculate the notification determination value Aj (step S2). Note that the notification determination value setting unit 500 may not be provided, and a value larger than the alarm value Alm may be set in advance as the notification determination value Aj.

  However, by providing the notification determination value setting unit 500, even if the alarm value Alm changes due to a change in the model or manufacturer of the device main body 3 combined with the battery pack 2 or an OS change. The notification determination value Aj can be set appropriately.

  Next, the current detection unit 52 detects the current value Ic flowing through the secondary battery 4 (step S3). Next, the remaining amount calculation unit 501 integrates the current value Ic every unit time, and calculates the accumulated remaining amount Qa charged in the secondary battery 4 (step S4). Next, the remaining amount calculating unit 501 calculates the accumulated remaining amount SOCa from the full charge capacity value FCC and the accumulated remaining amount Qa stored in the capacity storage unit 505 using the equation (1) (step S1). S5).

  The processes in steps S2 to S5 are always executed in parallel with the following processes, and the accumulated remaining amount Qa and the accumulated remaining amount SOCa are constantly updated to the latest values.

  Next, the notification unit 504 transmits the latest accumulated remaining amount SOCa as the RSOC to the control unit 37 and notifies the device body 3 (step S6).

  Next, the notification unit 504 compares the current value Ic with 0 (step S7). If the current value Ic is not less than 0 (NO in step S7), that is, if the secondary battery 4 is not discharged, Returning to step S6 again, steps S6 and S7 are repeated.

  On the other hand, when the current value Ic is a negative value that is less than 0 (YES in step S7), that is, when the secondary battery 4 is discharged, the notification unit 504 causes the integrated remaining amount SOCa to be equal to the notification determination value Aj. Comparison is made (step S8). If the accumulated remaining amount SOCa exceeds the notification determination value Aj (NO in step S8), the process returns to step S6 and steps S6 to S8 are repeated, and the notifying unit 504 sets the accumulated remaining amount SOCa as the RSOC. The main body 3 is notified.

  On the other hand, when the secondary battery 4 is being discharged (YES in step S7), if the accumulated remaining amount SOCa becomes equal to or less than the notification determination value Aj (YES in step S8), the notification determination value Aj is set as the RSOC by the notification unit 504. 3 (step S9, timing T1 in FIG. 5).

  Next, the terminal voltage value Vb is detected by the voltage detection unit 51, and the temperature t of the secondary battery 4 is detected by the temperature detection unit 53 (step S10). Then, the remaining amount estimation unit 502 refers to the lookup table LT stored in the table storage unit 506. Then, the SOC that is associated with the current value Ic, the terminal voltage value Vb, and the temperature t in the lookup table LT is acquired by the remaining amount estimation unit 502 as the estimated remaining amount SOCe (step S11).

  The correcting unit 503 compares the estimated remaining amount SOCe with the reference value Ref (step S12). If the estimated remaining amount SOCe and the reference value Ref are not equal (NO in step S12), steps S9 to S12 are repeated. .

  On the other hand, if the estimated remaining amount SOCe and the reference value Ref are equal (YES in step S12, timing T2 in FIG. 5), the correction of the full charge capacity value FCC by the correction unit 503 is executed (step S13). Thereafter, the remaining amount SOCa is calculated by the remaining amount calculation unit 501 based on the corrected full charge capacity value FCC.

  As described above, according to the processing in steps S7 to S13, the period from the timing T1 in FIG. 5 until the correction of the full charge capacity value FCC by the correction unit 503 at the timing T2 is larger than the alarm value Alm. The notification determination value Aj is notified to the device body 3 as the RSOC of the secondary battery 4.

  Then, in the apparatus main body 3, the control unit 37 does not notify the user of an alarm for prompting charging until the correction of the full charge capacity value FCC by the correction unit 503 is executed. Thereby, when correcting the full charge capacity value FCC, it is possible to reduce the possibility that the secondary battery 4 is charged before the correction is performed and the opportunity for correction is lost.

  Then, after the full charge capacity value FCC is corrected, the notification unit 504 proceeds to step S6 again, transmits the integrated remaining amount SOCa as the RSOC to the control unit 37, and notifies the device body 3 (step S6). . Thereafter, the processes of steps S6 to S13 are repeated.

  Since the RSOC is below the alarm value Alm, the control unit 37 that has received the RSOC notifies the user of an alarm for prompting charging by the display unit 38. Thereby, after the full charge capacity value FCC is corrected, the alarm notification by the device main body 3 can be executed.

  A battery remaining amount notification circuit, a battery pack, and an electric device according to the present invention include a portable personal computer, a digital camera, a video camera, an electronic device such as a mobile phone, a vehicle such as an electric vehicle and a hybrid car, a hybrid elevator, and a solar cell. In addition, it can be suitably used in battery mounted devices and systems such as a power supply system in which a power generation device and a secondary battery are combined, and a non-stop power supply device.

DESCRIPTION OF SYMBOLS 1 Electric equipment 2 Battery pack 3 Equipment main body 4 Secondary battery 5 Battery remaining amount notification circuit 6 Current detection resistance 7 Temperature sensor 11, 12, 13, 31, 32, 33 Connection terminal 34 Load circuit 35 Charging part 36, 54 Communication part 37, 50 control unit 38 display unit 51 voltage detection unit 52 current detection unit 53 temperature detection unit 500 notification determination value setting unit 501 remaining amount calculation unit 502 remaining amount estimation unit 503 correction unit 504 notification unit 505 capacity storage unit 506 table storage unit Aj Notification judgment value Alm Alarm value FCC Fully charged capacity value Ic Current value Q1, Q2 Switching element Qa, SOCa Accumulated remaining amount Qd Differential electric quantity Qe, SOCe Estimated remaining amount Ref Reference value Vb Terminal voltage value

Claims (9)

A battery remaining amount notification circuit for notifying the remaining amount of the secondary battery to a device body that notifies an alarm prompting charging of the secondary battery when the remaining amount of the secondary battery is lower than a preset alarm value;
A voltage detection unit for detecting a terminal voltage value of the secondary battery;
A current detector for detecting a current value of a charge / discharge current flowing in the secondary battery;
Based on the charge / discharge current of the secondary battery detected by the current detection unit, from the integrated value obtained by cumulatively performing the addition of the charge electricity amount and the subtraction of the discharge electricity amount in the secondary battery, A remaining amount calculation unit for calculating the remaining amount of the secondary battery as an accumulated remaining amount;
A capacity storage unit for storing a full charge capacity value of the secondary battery;
When the remaining amount of the secondary battery reaches a reference value set to a value smaller than the alarm value, the battery stored in the capacity storage unit is based on the terminal voltage value detected by the voltage detection unit. A correction unit for correcting the charge capacity value;
When the accumulated remaining amount exceeds a notification determination value set to a value larger than the alarm value, information indicating the accumulated remaining amount is notified to the device main body as the remaining amount of the secondary battery, and the secondary battery The notification determination value is notified to the device main body as the remaining amount of the secondary battery until the correction by the correction unit is executed after the accumulated remaining amount becomes the notification determination value with the discharge of A battery level notification circuit comprising: a notification unit; The notification unit
After the correction by the correction unit is performed, information indicating the accumulated remaining amount is used as the remaining amount of the secondary battery until the accumulated remaining amount becomes the notification determination value again due to the discharge of the secondary battery. The battery remaining amount notification circuit according to claim 1, which notifies a device main body.   The battery remaining amount notification circuit according to claim 1, further comprising a notification determination value setting unit that receives the alarm value from the device main body and sets the notification determination value to a value larger than the received alarm value. Based on the terminal voltage value detected by the voltage detection unit, further comprising a remaining amount estimation unit that estimates the remaining amount of the secondary battery as an estimated remaining amount,
The correction unit is
The battery remaining amount notification circuit according to claim 1, wherein the correction is executed when the estimated remaining amount becomes the reference value. The correction unit is
When the estimated remaining amount reaches the reference value, a difference electric quantity corresponding to the difference between the estimated remaining amount and the accumulated remaining amount is set to the capacity when the estimated remaining amount is greater than the accumulated remaining amount. Add to the full charge capacity value stored in the storage unit, and if the estimated remaining amount is less than the accumulated remaining amount, subtract from the full charge capacity value stored in the capacity storage unit to correct Item 5. A battery remaining amount notification circuit according to Item 4. A value representing the reference value as a percentage of the full charge capacity value of the secondary battery is Ref, a difference electric quantity corresponding to a difference between the estimated remaining amount and the accumulated remaining amount is stored in Qd, and the capacity storage unit is stored. If the full charge capacity value is FCC,
The correction unit is
When the estimated remaining amount becomes the reference value, if the estimated remaining amount is larger than the accumulated remaining amount, a full charge capacity value FCCn is calculated based on the following formula (A), and the estimated remaining amount is calculated from the accumulated remaining amount. If the estimated remaining amount is smaller, a full charge capacity value FCCn is calculated based on the following equation (B), and the capacity storage unit uses the calculated full charge capacity value FCCn as a new full charge capacity value FCC. 5. The battery remaining amount notification circuit according to claim 4, wherein the full charge capacity value is corrected by being stored in the battery.
FCCn ← FCC + | Qd | × 100 / (100−Ref) (A)
FCCn ← FCC- | Qd | × 100 / (100-Ref) (B) The remaining amount calculation unit
The battery according to any one of claims 1 to 5, wherein the SOC of the secondary battery is calculated as the accumulated remaining amount based on a full charge capacity value stored in the capacity storage unit and the accumulated value. Remaining amount notification circuit. The battery remaining amount notification circuit according to any one of claims 1 to 7,
A battery pack comprising the secondary battery. The battery remaining amount notification circuit according to any one of claims 1 to 7,
The secondary battery;
An electric device comprising the device main body.

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