TW201725399A - Remaining capacity detection circuit of rechargeable battery, electronic apparatus using the same, automobile, and detecting method for state of charge - Google Patents

Abstract

The present invention improves the detection accuracy of the state of charge of a battery. A coulomb count value CC is generated by integrating a charge/discharge current IBAT of a battery (S100). An SOC value SOC1 is calculated (S102). Based on an SOC-OCV characteristic predetermined for the battery, an OCV value OCV1 corresponding to the value SOC1 is generated (S112). A voltage VBAT of the battery is detected (S104). A voltage drop VDROP1 between OCV1 and a detected value VBAT1 of the voltage VBAT is generated (S114). A value OCV2 greater than the minimum operating voltage of the system by [Delta]V, which corresponds to the voltage drop VDROP1, is generated (S116). Based on the SOC-OCV characteristic, an SOC value SOC2 corresponding to OCV2 is generated (S118). Based on the value SOC2, at least one of the values SOC1, CC, CCFULL, and SOC-OCV characteristics is corrected.

Description

Residual battery detection circuit, electronic device using the same, automobile and charging state detecting method

The present invention is directed to a battery management system.

Among the various battery-driven electronic devices, including mobile phone terminals, digital cameras, tablet terminals, walkmans, portable game machines, and notebook computers, there are built-in rechargeable batteries (batteries) for CPUs for system control or signal processing ( Electronic circuits such as a central processing unit, a liquid crystal panel, a wireless communication module, and other analog/digital circuits are operated by power supply from a battery. Figure 1 is a block diagram of a battery-operated electronic machine. The electronic device 500 includes a battery 502 and a charging circuit 504 that charges the battery 502. The charging circuit 504 receives the power supply voltage V _ADP from an external power adapter or USB (Universal Serial Bus) to charge the battery 502. A load 508 is connected to the battery 502. The current _BAT flowing through the battery 502 becomes the difference between the charging current I _CHG from the charging circuit 504 and the load current (discharge current) I _LOAD flowing through the load 508. In the battery-operated electronic device, the detection of the residual amount of the battery (state of charge: SOC) becomes an indispensable function, and the electronic device 500 is provided with the residual amount detecting circuit 506. The residual amount detecting circuit 506 is also referred to as a fuel gauge IC (Integrated Circuit). As a method of detecting the residual amount of the battery by the residual amount detecting circuit 506, both the (1) voltage method and the (2) coulomb method (charge accumulation method) become mainstream. There is also a case where the residual amount detecting circuit 506 is built in the charging circuit 504. In the voltage method, the open circuit voltage (OCV: Open Circuit Voltage) of the battery is measured in an open state (no load state), and the residual amount is estimated based on the correspondence relationship between OCV and SOC. Since the OCV cannot be measured as long as the battery is unloaded and is not in a relaxed state, the OCV cannot be accurately measured during charge and discharge. In the coulomb method, the charging current flowing into the battery and the discharging current flowing from the battery (hereinafter collectively referred to as charging and discharging current) are integrated, and the amount of charge and the amount of discharged electric charge to the battery are calculated, and the residual amount is estimated. According to the coulomb method, unlike the voltage method, the residual amount can be estimated during the use of the battery in which the open voltage cannot be obtained. The residual amount detecting circuit 506 of FIG. 1 infers the residual amount of the battery 502 by the coulomb counting method. The residual amount detecting circuit 506 includes a coulomb counter circuit 510 and an SOC calculating unit 512. The coulomb counter circuit 510 detects the current I _{BAT of the} battery 502 and accumulates it. The coulomb count CC generated by the coulomb counter circuit 510 is represented by the following equation. CC=∫I _BAT dt Strictly speaking, the battery current I _BAT is discretely sampled in time and is calculated according to the following equation. Δt represents the sampling period. _{CC = Σ (Δt × I BAT} ) of the accumulated (integrated), for example, based on the direction of the current flowing from the battery 502 I _BAT is positive, and the direction of the current flowing into the battery 502 and the I _BAT to be negative for . The SOC calculation unit 512 calculates the SOC of the battery 502 based on the coulomb count CC. The following formula is used in the calculation of the SOC. SOC [%] = (CC _FULL - CC) / CC _FULL × 100 CC _FULL indicates the amount of charge (coulomb value) accumulated in the battery 502 in the fully charged state. [Prior Art Document] [Patent Document] [Patent Document 1] US Patent No. 9,035,616 B2

[Problems to be Solved by the Invention] The inventors of the present invention have studied the residual amount detecting circuit 506 of Fig. 1 and have recognized the following problems. Here, the charging is not considered, but the phenomenon at the time of discharge is explained. Fig. 2 is a view showing changes in the correspondence relationship between OCV and SOC (SOC-OCV characteristics) and battery voltage V _BAT . Here, taking a lithium ion battery as an example, when OCV=4.2 V, it is in a fully charged state, that is, SOC=100%. Further, when the lowest operating voltage at which the system including the load 508 operates can be set to V _{BAT _ MIN} , when OCV = V _{BAT _ MIN} , SOC = 0%. Regarding the intermediate SOC, the OCV system is associated with the one-to-one correspondence. Currently, if the load current I _LOAD flows continuously or discontinuously from the fully charged state, the OCV decreases in the direction indicated by the arrow in the figure. The discharge current I _BAT at this time is accumulated, and the SOC is calculated based on the coulomb count CC, and approaches zero with the passage of time. In addition to the OCV, FIG. 2 also shows the battery voltage V _BAT taken out from the battery 502 to the outside. The battery voltage V _BAT is further reduced than the OCV. The falling amount (voltage drop) V _DROP includes a component based on the history of the past load current I _LOAD in addition to the component proportional to the current load current I _LOAD (ie, the instantaneous value). Therefore, even after the load current I _LOAD becomes zero, the falling amount does not immediately become zero. The voltage drop V _{DROP is} close to zero after a long relaxation time (a few hours or so) under no load. As shown in FIG. 2, before the OCV is lowered to V _{BAT _ MIN} due to the voltage drop V _DROP , if the battery voltage V _{BAT is} lowered to V _{BAT _ MIN} , the system is shut down. At this time, the SOC system calculated by the coulomb method is greater than the value X of 0. That is, although expressed as a residual X (%), the user of the electronic device 500 may also experience a system shutdown condition. The present invention has been made in view of the above problems, and an exemplary object of one aspect thereof is to provide a method and a residual amount detecting circuit capable of improving the detection accuracy of a state of charge of a battery. [Technical means for solving the problem] A certain aspect of the present invention relates to a method of detecting a SOC (State Of Charge) of a rechargeable battery. This party contains the following processing. (1) The coulomb count CC is generated by accumulating the charge and discharge currents of the battery. (2) The value SOC1 of the SOC is generated based on SOC1 = (CC _FULL - CC) / CC _FULL × 100 (1). Among them, CC _FULL is equivalent to the fully charged coulomb capacity value. Further, in the method, the following (3) correction processing is performed. (3-1) The value OCV1 of the OCV corresponding to the value SOC1 is generated based on the correspondence relationship (SOC-OCV characteristic) between the SOC and the OCV (Open Circuit Voltage) specified in advance for the battery. (3-2) Detect the voltage of the battery V _BAT1 . (3-3) The difference V _{DROP1 between the} generated value OCV1 and the detected value V _BAT1 of the voltage V _BAT of the battery. (3-4) A system voltage _{lower limit} voltage V _{BAT _ MIN is} generated higher than the value OCV2 of the voltage amplitude ΔV corresponding to the differential V DROP1 . (3-5) A value SOC2 of the SOC corresponding to the value OCV2 is generated based on the SOC-OCV characteristic. (3-6) The value SOC2 is set to be equal to the residual zero (0%), and at least one of the values SOC1, CC, C _FULL, and SOC-OCV characteristics is corrected. According to this aspect, considering the above-mentioned constantly changing voltage drop V _DROP , when the actual battery voltage V _{BAT is} lowered to the minimum operating voltage V _{BAT _ MIN} , that is, when the system is turned off, the SOC can be corrected to zero. The residual detection processing based on the coulomb counting method can improve the detection accuracy of the SOC. It can also be ΔV=V _DROP1 . It is effective when the SOC dependence of the difference between OCV and battery voltage is small. The SOC dependence of the difference between the OCV and the battery voltage V _DROP can be maintained in advance, or can be maintained in the look-up table, and can be maintained as an arithmetic expression. The correction process may further include the following processing. Calculate the tentative value of OCV OCV3=V _{BAT _ MIN} +V _DROP1 . A tentative value SOC3 of the SOC corresponding to the tentative value OCV3 of the OCV is generated. The voltage drop ΔV at the provisional value SOC3 is calculated based on the difference V _{DROP1 at the} value SOC1 and the SOC dependency of the difference. This can improve accuracy. In addition to the SOC dependence of the voltage drop V _DROP , temperature dependence can be maintained. This can further improve the accuracy. In the correction processing (3-6), the coulomb counter capacity value CC _FULL can also be corrected to the new value CC _FULL ' obtained by the equation (2). CC _FULL '=CC _FULL ×(100-SOC2)/100 (2) In the correction process (3-6), the coulomb value CC can also be corrected to the new value CC' obtained by the equation (3). . _{CC '= CC- (CC FULL -CC} FULL') ... (3) in the correction process (3-6), the coulometer may be corrected to the new value CC value obtained by the formula (4) CC '. CC'=CC-CC _FULL × SOC2/100 (4) In the correction processing (3-6), the new value SOC' obtained by the equation (5) may be used as the corrected SOC. SOC'=SOC1×100/(100-SOC2) (5) In the correction process (3-6), the coulomb count CC may not be corrected. In the correction processing (3-6), the new value SOC' obtained by the equation (6) can also be used as the corrected SOC. SOC'={CC _FULL -CC×100/(100-SOC2)}/CC _FULL ×100 (6) In the correction process (3-6), the coulomb count capacity value CC _FULL may not be corrected, but the coulomb The value CC is corrected to the new value CC' obtained by the equation (7). CC'=CC×100/(100-SOC2) (7) In the correction processing (3-6), the coulomb count CC can also be corrected to the new value CC' obtained by the equation (8). CC'=CC×(100-SOC2)/100 (8) The SOC-OCV characteristic described above may also associate a range of OCV lower than the lowest operating voltage of the system with a negative SOC. In this way, it is also possible to cope with an increase in the effective residual amount. The correction process (3) can be effective when the voltage of the battery is lower than a specific voltage value. Alternatively, the correction process (3) may also be effective when the SOC is lower than a specific value. When the battery residual amount is large, the correction is not performed, whereby the increase in power consumption accompanying the correction can be suppressed. The correction process (3) can also be made effective intermittently for each specific cycle. When the correction is always effective, the power consumption is increased, and by performing the correction processing intermittently for each specific cycle, it is possible to suppress an increase in the power consumption caused by the correction. The specific period can also be longer than 1 second and shorter than 60 seconds. By correcting by this period, it is possible to obtain an effect of improving the SOC accuracy within a range of reasonable power consumption increase. Another aspect of the present invention relates to a residual amount detecting circuit for detecting a SOC (State Of Charge) of a rechargeable battery. The residual amount detecting circuit includes a coulomb counter circuit that generates a coulomb count CC by accumulating a charge and discharge current of the battery, a voltage detecting circuit that detects a voltage V _{BAT of the} battery, and an SOC calculation unit according to the formula (1) And calculating a value SOC1 of the SOC; and a correction circuit that corrects at least one of the values SOC1, CC, C _FULL, and SOC-OCV characteristics. SOC1=(CC _FULL -CC)/CC _FULL ×100 (1) where CC _FULL is equivalent to the coulometric capacity value of the full charge. Correction circuit execution: a step of generating an OCV value OCV1 corresponding to the value SOC1 according to a SOC-OCV characteristic which is a predetermined correspondence between the SOC and the OCV (Open Circuit Voltage) for the battery; generating the value OCV1 and the voltage detection circuit The step of detecting the difference V _DROP1 of the detected value of the voltage V _BAT1 ; generating a step _OCV2 higher than the lowest operating voltage of the system by the voltage amplitude ΔV corresponding to the differential V _DROP1 ; generating the value OCV2 according to the SOC-OCV characteristic a step of SOC2 corresponding to the SOC value; and a step of correcting at least one of the values SOC1, CC, C _FULL, and SOC-OCV characteristics by setting the value SOC2 to be equal to the residual zero (0%). Another aspect of the invention is an electronic machine. The electronic device includes a rechargeable battery and the above-described residual amount detecting circuit for detecting the state of the battery. Another aspect of the invention is a car. The automobile includes a rechargeable battery and the above-described residual amount detecting circuit for detecting the state of the battery. Furthermore, any combination of the above constituent elements, or constituent elements of the present invention or expressions, which are expressed in a method, an apparatus, a system, or the like, are also effectively used as the aspect of the present invention. [Effect of the Invention] According to the present invention, the detection accuracy of the state of charge of the battery can be improved.

Hereinafter, the present invention will be described with reference to the drawings in accordance with preferred embodiments. The same or equivalent constituent elements, members, and processes are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Further, the embodiments are not limited to the inventors, and all the features described in the embodiments or combinations thereof are not necessarily limited to the essentials of the invention. In the present specification, the "state in which the member A and the member B are connected" also includes a case where the member A and the member B are physically directly connected, or a case where the member A and the member B are indirectly connected via other members, and the latter does not The electrical connection state or the like causes substantial influence or does not impair the function or effect exerted by the combination thereof. Similarly, the phrase "the state in which the member C is disposed between the member A and the member B" includes, in addition to the case where the member A and the member C are directly connected to the member C, and the indirect connection via the other members. The latter case does not substantially affect the electrical connection state of the device, or does not impair the function or effect exerted by the combination thereof. Further, in the present specification, the voltage signal, the current signal, or the symbol indicated by the resistor indicates the voltage value, the current value, or the resistance value of each of them as needed. 3 is a block diagram of a battery management system 100 having a residual amount detecting circuit of an embodiment. The battery management system 100 includes a battery 102, a charging circuit 104, a load 108, and a residual amount detecting circuit 200. Battery 102 contains one or more cells. The type of the battery cell is not particularly limited, and examples thereof include a lithium ion battery core, a lithium air battery core, a lithium metal based battery core, a nickel hydride battery core, a nickel cadmium battery core, and a nickel zinc battery core. The number of cells depends on the use of the battery management system 100, but in the case of a portable electronic device, it is one cell to several cells, and is tens to several in the use of a vehicle battery, an industrial machine, or an industrial machine. A hundred batteries around. The configuration of the battery 102 is not particularly limited as the use of the present invention. The battery voltage V _BAT from the battery 102 is supplied to the load 108. The type of the load 108 is not particularly limited. For example, when the battery management system 100 is mounted on an electronic device, the load 108 may include a power supply circuit that boosts or steps down the battery voltage V _{BAT to} generate the power supply voltage V _DD or various electronic circuits that are operated by the power supply voltage V _DD . . When the battery management system 100 is mounted on an automobile or an industrial machine, the load 108 may include a motor and an inverter that converts the battery voltage V _BAT into an alternating current and drives the motor. The charging circuit 104 receives the power supply voltage V _EXT from an external power adapter or a USB (Universal Serial Bus) or a charging station to charge the battery 102. The residual amount detecting circuit 200 detects the state of charge (SOC) of the battery 102. In the present specification, the SOC is described as being easy to understand, and the SOC is set to a minimum value of 0 and a maximum value of 100 (%). However, the present invention is not limited thereto. For example, when the SOC is represented by 10 bits, in the process of digital signal processing, please note that the SOC is represented by 1024 gray scales of 0 to 1023. The residual amount detecting circuit 200 includes a coulomb counter circuit 202, a voltage detecting circuit 204, an SOC calculating unit 206, a correcting circuit 208, and a lookup table 210. The coulomb counter circuit 202 generates a coulomb count CC by accumulating the charge and discharge current (I _BAT ) of the battery 102. The coulomb count CC is expressed by the following formula. The CC=∫I _BAT dt coulomb counter circuit 202 samples the battery current I _BAT at a particular sampling period Δt. The coulomb count CC is calculated using the battery current I _BATi at each sampling time using the following equation. _{CC = Σ i = 1 (Δt} × I BATi) the accumulated (integrated), for example, based on the direction of the current flowing from the battery 102 I _BAT is positive, and the direction of the current flowing into the battery 502 to the I _BAT Negative. The method of detecting the current I _BAT is not particularly limited. For example, the sense resistor R _S can be inserted in series with the battery 102 into the path of the current I _{BAT to} detect the voltage drop of the sense resistor R _S . The sense resistor R _S can be inserted into the positive side of the battery 102 or inserted on the negative side. The coulomb counter circuit 202 can also include an A/D converter that samples the voltage drop V _CS of the sense resistor R _S (or a voltage that amplifies the voltage drop V _CS ) and the output data of the A/D converter. Cumulative accumulator. The voltage detecting circuit 204 monitors the voltage V _{BAT of the} battery 102 and generates data (voltage data) DV _BAT indicating the battery voltage V _BAT1 . The voltage detecting circuit 204 may also include an A/D converter that samples the battery voltage V _BAT or samples and digitizes the voltage whose specific coefficient is multiplied. The SOC calculation unit 206 receives the coulomb count CC from the coulomb counter circuit 202. The SOC calculation unit 206 calculates the value SOC1 of the SOC based on the equation (1). SOC1=(CC _FULL -CC)/CC _FULL ×100 (1) where CC _FULL is equivalent to the coulometric capacity value of the full charge. The correction circuit 208 supplies the value SOC1 and the voltage data DV _BAT . The correction circuit 208 corrects at least one of the values SOC1, CC, C _FULL, and SOC-OCV characteristics based on the values. Hereinafter, the correction processing of the correction circuit 208 will be described. The correspondence relationship between the SOC and the OCV (Open Circuit Voltage) (SOC-OCV characteristic) is measured in advance for the battery 102. Fig. 4 is a view showing an example of SOC-OCV characteristics. The SOC-OCV characteristics are stored, for example, in the lookup table 210 of FIG. The intermediate value that is not stored in the lookup table 210 can be generated by an arithmetic means such as linear interpolation. Alternatively, the correction circuit 208 can also maintain the SOC-OCV characteristics in the form of an arithmetic expression (eg, a polynomial). The correction circuit 208 generates the value OCV1 of the OCV corresponding to the value SOC1 based on the SOC-OCV characteristic. Then, the difference V _DROP1 between the generated value OCV1 and the battery voltage V _BAT1 detected by the voltage detecting circuit 204 is _generated . V _DROP1 = OCV1-V _BAT1 sets the lowest operating voltage of the system containing load 508 to V _{BAT _ MIN} . Correction circuit 208 generates a relatively low operating voltage V _{BAT _ MIN} V _DROP1 comparing the differential value of the amplitude of the voltage ΔV corresponding OCV2 of. OCV2=V _{BAT _ MIN} +ΔV When ΔV=V _DROP1 , OCV2=V _{BAT _ MIN} +V _DROP1 or, when ΔV=V _DROP1 ×α (α is constant), OCV2=V _{BAT _ MIN} +V _DROP1 ×α or ΔV=V _DROP1 +β (β is a constant), OCV2=V _{BAT _ MIN} +V _DROP1 +β or , can also be set to OCV2=V _{BAT _ MIN} +α×V More generally, _DROP1 + β can also define a specific function f() and calculate the voltage amplitude ΔV from ΔV = f(V _DROP1 ). The correction circuit 208 generates a value SOC2 of the SOC corresponding to the value OCV2 based on the SOC-OCV characteristic. Then, the correction circuit 208 sets the value SOC2 to be equal to zero (0%) of the residual value of the battery 102, and corrects at least one of the values SOC1, CC, C _FULL, and SOC-OCV characteristics. The coulomb counter circuit 202 and the voltage detecting circuit 204 may be packaged only by a hard body or may be integrated into a single IC. The SOC calculation unit 206, the correction circuit 208, and the lookup table 210 may be packaged by a processor capable of software control such as a microcomputer. Alternatively, the residual amount detecting circuit 200 may be integrally formed into a single wafer. The SOC generated by the residual amount detecting circuit 200 can be displayed on the display device as a number or as an icon indicating the residual amount, or used as a reminder. The above is the configuration of the residual amount detecting circuit 200 of the embodiment. Then the action will be explained. Fig. 5 is a flow chart showing the residual amount detection in the embodiment. For example, processing starts from a fully charged state. In addition, the flowchart is not limited to the order of each process (step), and the order of each process can be arbitrarily changed as long as the process is not broken. Further, this flowchart does not indicate that the frequency (frequency, period) at which each process is executed is the same. The coulomb counter circuit 202 calculates the coulomb count CC (S100). The SOC calculation unit 206 calculates the value SOC1 based on the equation (1) using the coulomb calculation value CC (S102). For example, the coulomb counter circuit 202 updates the coulomb count CC at a period of several tens to several hundreds Hz, and the SOC calculation unit 206 may calculate the SOC 1 at a lower frequency, for example, a period of about 1 second to 60 seconds. The voltage detecting circuit 204 measures V _BAT (S104). The voltage detection circuit 204 can also measure the battery voltage V _{BAT at a} higher frequency (e.g., the same frequency as the coulomb circuit 202) when the increase in power consumption is not a problem. Then, the correction processing S110 is performed. The correction process S110 can be performed for each operation of the SOC1, or can be performed at a lower cycle. Fig. 6 is a view showing a correction process S110 using the relationship between voltage and SOC. Each value is generated in the order of the numbers (i) to (v) indicated above. The correction circuit 208 converts from SOC1 to OCV1 in accordance with the SOC-OCV characteristic (S112). Then, the voltage drop V _{DROP1 is} calculated (S114). Then, based on the voltage drop V _DROP1 and the minimum operating voltage V _{BAT — MIN} , the value OCV2 of the OCV when the measured value V _BAT1 of the battery voltage V _BAT reaches the minimum operating voltage V _{BAT — MIN} is estimated (S116). Then, the value OCV2 is inversely converted from the value SOCV2 to the value SOC2 of the SOC corresponding thereto according to the SOC-OCV characteristic (S118). The value SOC2 represents the SOC that the system can shut down. In other words, when the SOC1 calculated by the SOC calculation unit 206 is lowered to the value SOC2, the battery voltage V _BAT may be lowered to the lowest operating voltage V _{BAT — MIN} and shut down. Thus, the correction processing in S120 according to the value of SOC2, value SOC2 is set and the remaining amount of zero (0%) were quite, value SOC1, CC, C _FULL and SOC-OCV characteristics of at least one correction. The above is the residual amount detection processing of the embodiment. According to the residual amount detecting circuit 200 (and the residual amount detecting method) described herein, considering the above-mentioned constantly changing voltage drop V _DROP , when the actual battery voltage V _{BAT is} lowered to the lowest operating voltage V _{BAT _ MIN} , that is, When the system is shut down, the residual detection processing based on the coulomb method can be corrected by changing the SOC to zero. Thereby, the detection accuracy of the SOC can be improved. Furthermore, the method of detecting the residual amount of the embodiment cannot be confused with the SOC based on the voltage method. In the present embodiment, the SOC-OCV characteristic is common to the voltage method, but the measurement of the OCV is not necessary, and therefore there is no need to wait for the relaxation time to pass. The present invention relates to various devices, circuits, systems, and methods that can be grasped as the block diagram of FIG. 3 and the flowchart of FIG. 5, or can be derived from the above description, and is not limited to a specific configuration or method. In the following, a more specific configuration or method will be described, and it is not intended to limit the scope of the present invention, but to facilitate understanding of the nature of the invention or the operation of the circuit, and to clarify the details. Next, the correction processing S120 of the flowchart of FIG. 5 will be described. In the correction process, various methods exist as described below. (First Correction Method) FIG. 7 is a view schematically showing a first correction method. The coulomb count capacity value CC _FULL is corrected to the new value CC _FULL ' obtained by equation (2). CC _FULL '=CC _FULL ×(100-SOC2)/100 (2) That is, CC _FULL is converted so that SOC2 becomes zero (SOC = 0%). When K=(100-SOC2)/100 is referred to as a conversion factor, the equation (2) can be rewritten as the equation (2'). CC _FULL '=CC _FULL ×K...(2') Further, the coulomb count CC is corrected to the new value CC' obtained by the equation (3). _{CC '= CC- (CC FULL -CC} FULL') = CC-CC FULL × SOC2 / 100 ... (3) i.e., CC out is also reduced by the correction of the CC _FULL reduce the amount ΔCC (= CC _FULL -CC _FULL '). The corrected coulomb count CC' is written into the scratchpad of the stored coulomb count CC inside the coulomb counter circuit 202 of FIG. Further, the coulomb counter capacity value CC _FULL ' is replaced with the coulomb counter capacity value CC _FULL held by the SOC calculation unit 206 of Fig. 3 . The coulomb count CC can also be corrected to the new value CC' obtained by equation (4). CC'=CC-CC _FULL × SOC2/100 (4) Further, the equation (3) is equivalent to the equation (4). When CC and CC _FULL are corrected, the SOC1' generated by the SOC calculation unit 206 is represented by the following equation. _{SOC1 '= (CC FULL' -CC} ') / CC FULL' × 100 = {(CC FULL -CC FULL × SOC2 / 100) - (CC-CC FULL × SOC2 / 100)} / {CC FULL × K} × 100 =(CC _FULL -CC)/CC _FULL ×100×1/K Here (CC _FULL -CC)/CC _FULL ×100 is equivalent to SOC1 of equation (1), so the corrected SOC' is given by equation (5) Said. SOC'=SOC1×1/K=SOC1×100/(100-SOC2) (5) In the first correction method, the coulomb count CC and the coulomb capacity value CC _FULL are corrected by one correction, and thereafter, The corrected charge and discharge current I _BAT is accumulated by using the corrected coulomb count CC' as an initial value. That is, the SOC detection is performed by the coulomb method in a state in which the correction is reflected. That is, it is not necessary to correct the correction circuit 208 for each calculation of the SOC 1 of the SOC calculation unit 206. (Second correction method) The second correction method is substantially the same as the first correction method. However, the correction of the values CC and CC _FULL is not performed, and the value SOC' calculated according to the equation (5) is corrected as the correction. SOC. The second correction method can be used when the correction processing is performed every time the SOC calculation unit 206 calculates SOC1. (Third Correction Method) In the third correction method, CC _FULL is corrected according to the equation (2), and the coulomb calculation CC is not corrected. In this case, the new value SOC' obtained by the equation (6) is used as the corrected SOC. SOC'=(CC _FULL '-CC)/CC _FULL '×100 =(CC _FULL ×K-CC)/(CC _FULL ×K)×100 =(CC _FULL -CC×1/K)/CC _FULL ×100 ={CC _FULL -CC×100/(100-SOC2)}/CC _FULL ×100 (6) (Fourth correction method) In the fourth correction method, the Coulomb capacity value CC _FULL may not be corrected, but Coulomb may be used. The value CC is corrected to the new value CC' obtained by the equation (7). CC'=CC×100/(100-SOC2) (7) The fourth correction method gives SOC' in the same manner as the third correction method, so it is equivalent. (Fifth Correction Method) In the fifth correction method, the coulomb counter capacity value CC _FULL is corrected based on the equation (2). Further, the coulomb count CC is corrected to the new value CC' obtained by the equation (8). That is, CC _FULL and CC are converted by the same conversion factor K. CC'=CC×(100-SOC2)/100=CC×K (8) In the fifth correction method, the SOC immediately after correction becomes SOC'=(CC _FULL '-CC)/CC _FULL '×100 =( CC _FULL × K - CC × K) / (CC _FULL × K) × 100 = (CC _FULL - CC) / CC _FULL × 100 = SOC1, which maintains the same value as before the correction. Among them, the coulomb count CC and the coulomb count capacity value CC _FULL are corrected, and then the counter further calculates the SOC1 to reflect the corrector. In the case where the discontinuity of the SOC is not good, the fifth correction method can be employed. (Sixth Correction Method) In the first to fifth correction methods, at least one of the values CC, CC _FULL , and SOC is corrected. On the other hand, in the sixth correction method, the SOC-OCV characteristic is corrected. More specifically, in the sixth correction method, the SOC-OCV characteristic is corrected so that SOC2 becomes zero (0%). For example, the SOC (%) before correction and the corrected SOC' (%) may be satisfied as the following equation (9). SOC'=100-(100-SOC)×1/K=100-(100-SOC)×100/(100-SOC2) (9) FIGS. 8 and 9 show an example of correction of SOC-OCV characteristics. Figure. Further, the sixth correction method is not limited to this, and an arithmetic expression different from the equation (9) may be employed. Alternatively, instead of correcting the value of the SOC, the value of the OCV corresponding to each SOC may be corrected, or both may be corrected. The correction of the SOC-OCV characteristic may have a change corresponding to the first to fifth correction methods described above. The changes in the correction method have been described above. It should be understood by those skilled in the art that in addition to the first to sixth correction methods, various correction methods exist and are included in the scope of the present invention. Further, what kind of correction method should be adopted and it is selected according to the use of the battery management system 100. For example, in the first and second correction methods, when K < 1, the SOC value becomes larger due to the correction. On the contrary, in the third and fourth correction methods, when K < 1, the SOC value becomes small due to the correction. In the fifth correction method, the SOC value is maintained before and after the correction. K < 1 indicates that the absolute residual amount is lowered. On the other hand, SOC represents relative residual. The first and second correction methods are correct from the viewpoint of relative residual amount. However, there are cases where a larger number of users do not recognize the SOC indicated by % as a relative residual amount and consider it to be an absolute residual amount. In this case, some people may feel uncomfortable in the case where the residual amount is reduced (that is, the remaining usable time is reduced) but the SOC (%) is increased. In this case, the third to fifth correction methods may be used. The present invention has been described above based on the embodiments. The embodiment is exemplified, and it should be understood by those skilled in the art that various combinations of constituent elements or processing procedures are variously modified, and such variations are also within the scope of the invention. Hereinafter, such a variation will be described. (First Modification) The SOC-OCV characteristic can also associate a range of OCV lower than the lowest operating voltage of the system with a negative SOC. Fig. 10 is a view showing an example of the SOC-OCV characteristics of the first modification. In the description so far, the case where the effective residual amount (absolute value) of the battery is reduced has been described. However, if the voltage drop V _DROP becomes a negative number, the residual amount will increase. By introducing a negative SOC value, it is possible to respond to an increase in the amount of residuals without additional special processing. Fig. 11 is a view showing a correction process when the SOC-OCV characteristic of Fig. 10 is used. (Second Modification) In the processing S116 of the flowchart of Fig. 5, when generating OCV2, the calculation formula OCV2 = V _{BAT _ MIN} + ΔV (10) is used, as shown in Fig. 2, the difference V between OCV and V _{BAT DROP} depends on the SOC. Therefore, in the processing S116, when ΔV=V _DROP1 is used, the error when the difference between SOC1 and SOC2 is large is large. Therefore, in the second variation, the SOC dependency of the voltage drop V _{DROP is} considered. Specifically, the SOC dependency of the voltage drop V _DROP is defined as a lookup table or an arithmetic expression. Figure 12 is a look-up table showing the SOC dependence of the voltage drop V _DROP . The table indicates the relative ratio of voltage drops in a plurality of SOCs, for example, based on a voltage drop of a specific reference SOC (here, 100%), and a ratio (Voltage Drop Ratio: VDR) indicates each SOC. Voltage drop. VDR(x)=V _DROP (x)/V _DROP (100) Therefore, when the voltage drop under a certain SOC (=x ₁ ) is V _DROP1 , the voltage drop V _DROP2 under another SOC (=x ₂ ) can Calculated according to the following formula. V _DROP2 = V _DROP1 × VDR(x ₂ ) / VDR(x ₁ ) FIG. 13 is a flowchart of the residual amount detection in the second variation. In the flowchart, the ΔV calculation routine S115 is added before the process S116 of the flowchart of FIG. Fig. 14 is a flowchart showing the ΔV calculation routine S115. First, based on the voltage drop V _DROP1 and the minimum operating voltage V _{BAT — MIN} , the tentative value OCV3 of the OCV when the measured value V _BAT1 of the battery voltage V _BAT reaches the minimum operating voltage V _{BAT — MIN} is calculated (S130). OCV3 = V _{BAT _ MIN} + V _DROP1 Then, the temporary value OCV3 is inversely converted from the provisional value OCV3 to the value SOC3 of the SOC corresponding thereto according to the SOC-OCV characteristic (S132). Then, based on the lookup table of Fig. 12, the VDR values VDR1 and VDR3 at SOC1 and SOC3 are obtained (S134). Then, ΔV is calculated based on ΔV = V _DROP1 × VDR3 / VDR1 (S136). Using the ΔV thus obtained, OCV2 is calculated in the process S116 of FIG. Fig. 15 is a view showing the estimation result of the SOC in the residual amount detection in the second modification. It represents an inferred value of the SOC when the battery is discharged at a fixed load (0.35 C). (i) is an ideal SOC and becomes a straight line at a fixed load. (ii) shows an estimated value of the SOC based on the flowchart of FIG. 5, and (iii) shows an estimated value of the SOC based on the flowchart of the second variation. Further, the error between each SOC estimated value and the ideal SOC is shown in FIG. As can be seen from Fig. 15, according to the second variation, the error can be reduced by considering the SOC dependency of the voltage drop V _DROP , and the estimation accuracy can be improved. (Third Modification) In the second variation, the SOC dependency of the voltage drop V _DROP is corrected using a lookup table, but it may be approximated by the following expression. VDR(SOC)=10^α*ln(log ₁₀ (β*SOC))+θ α, β, θ are deterioration and temperature coefficient (fourth variation example) The fourth variation is to further improve the accuracy of the second modification. Improver. In the fourth variation, the temperature dependence of the VDR is further considered. Figure 16 is a diagram showing an expanded VDR lookup table. As shown in Figure 16, the VDR lookup table is set for each of a number of temperatures. When the routine of Fig. 14 is executed, the temperature is measured, and the value of VDR is obtained based on the lookup table corresponding to the temperature. Fig. 17 is a view showing the estimation result of the SOC in the residual amount detection in the fourth modification. According to the fourth variation, the error can be further reduced by considering the temperature dependency of the voltage drop V _DROP , and the estimation accuracy can be improved. In the fourth variation, the VDR table for each temperature can also be approximated by an arithmetic expression. (Fifth Modification) When the correction processing is performed all the time, the calculation amount of the correction circuit 208 increases, and the power consumption increases. Therefore, the correction process can also be effective when the voltage V _{BAT of the} battery 102 is lower than the specific voltage value V _TH . The voltage value V _{TH is} selected for each system with an appropriate value. In many cases, the user's concern about the residual amount (SOC) of the battery 102 is when the SOC is lowered, that is, when the V _{BAT is} lowered. According to the second modification, the increase in the power consumption can be requested by making the correction processing effective in the case of the user's concern. Furthermore, the correction process can also be effective when the SOC is lower than a specific value. (Sixth Modification) The correction processing may be intermittently effective for each specific cycle. If the correction is always valid, the power consumption increases. Therefore, by performing the correction processing intermittently at a specific cycle, it is possible to suppress an increase in power consumption caused by the correction. The specific period can also be longer than 1 second and shorter than 60 seconds. By correcting this cycle, it is possible to obtain an effect of improving the SOC accuracy within a range of reasonable power consumption increase. In applications where the time scale of the voltage drop V _DROP changes is longer than 60 seconds, the particular period can be further lengthened. (Seventh Modification) The correction processing may be effective every time the SOC changes by a specific amount (n%, n is an arbitrary real number). According to this modification, it is possible to suppress an increase in power consumption caused by the correction. (Eighth Modification) In the embodiment, a dedicated voltage detecting circuit 204 for monitoring the voltage V _BAT of the battery 502 is provided. However, the present invention is not limited thereto. In the battery management system 100, when the circuit for detecting the battery voltage V _BAT already exists, the value of the battery voltage V _BAT1 detected by the circuit can be used. Further, the battery voltage V _BAT can also monitor the voltage of the positive electrode (+) of the battery 102, but is not limited thereto, and can monitor the voltages of other nodes (lines). For example, in a system in which a load switch is provided between the battery 102 and the load 108, the voltage of the node (line) on the load 108 side of the load switch can also be monitored. This is effective when the voltage drop of the load switch is large. (Variation 9) The correction of the SOC-OCV characteristics and the correction of the values CC, CC _FULL , and SOC can also be used in combination. Finally, the use of the battery management system 100 will be described. FIG. 18 is a view showing a car 300 including the battery management system 100. Automobile 300 series electric vehicle (EV), plug-in hybrid vehicle (PHV), hybrid vehicle (HV), and the like. The inverter 302 is subjected to a voltage V _BAT from the battery management system 100, converted to an alternating current, and supplied to the motor 304 to rotate the motor 304. Further, when decelerating in the case of braking, the inverter 302 performs a recharging operation to recover the current generated by the motor 304 into the battery 102 of the battery management system 100. In addition to the PHV or EV, a charging circuit for charging the battery 102 of the battery management system 100 is provided. FIG. 19 is a diagram showing an electronic device 400 including a battery management system 100. The electronic device 400 includes a PMIC (Power Management IC) 402, a processor 404, and other electronic circuits (not shown) in addition to the battery management system 100. The PMIC 402 is a combined plurality of power supply circuits that supply a suitable supply voltage to the processor 404 or other electronic circuitry. In addition, the battery management system 100 can be used for an industrial machine, an industrial machine, a power storage system for a home/workshop, a power supply for an elevator system, and the like. The present invention has been described with reference to the specific embodiments of the present invention. However, the embodiments of the present invention are intended to be limited to the scope of the present invention. Configuration changes.

100‧‧‧Battery Management System
102‧‧‧Battery
104‧‧‧Charging circuit
108‧‧‧load
200‧‧‧ residual detection circuit
202‧‧‧Coulomb circuit
204‧‧‧Voltage detection circuit
206‧‧‧SOC Computing Department
208‧‧‧Correction circuit
210‧‧‧ lookup table
300‧‧‧Car
302‧‧‧Inverter
304‧‧‧Motor
400‧‧‧Electronic machines
402‧‧‧PMIC
404‧‧‧ processor
500‧‧‧Electronic machines
502‧‧‧Battery
504‧‧‧Charging circuit
506‧‧‧ residual detection circuit
508‧‧‧load
510‧‧‧Coulomb circuit
512‧‧‧SOC Computing Department
DV _BAT ‧‧‧Voltage data
I _BAT ‧‧‧Battery current
I _{BATi ‧‧‧Battery} current
I _CHG ‧‧‧Charging current
I _LOAD ‧‧‧Load current
R _S ‧‧‧resistance resistor
S100～S120‧‧‧Steps
V _ADP ‧‧‧Power supply voltage
V _BAT ‧‧‧Battery voltage
V _{BAT _ MIN} ‧‧‧ minimum operating voltage
V _CS ‧‧‧ voltage drop
V _DD ‧‧‧Power supply voltage
V _DROP ‧‧‧Voltage drop ΔV‧‧‧Voltage amplitude Δt‧‧‧Sampling period

Figure 1 is a block diagram of an electronic machine. Fig. 2 is a view showing changes in the correspondence relationship between OCV and SOC (SOC-OCV characteristics) and battery voltage V _BAT . Fig. 3 is a block diagram of a battery management system including a residual amount detecting circuit of the embodiment. Fig. 4 is a view showing an example of SOC-OCV characteristics. Fig. 5 is a flow chart showing the residual amount detection in the embodiment. Fig. 6 is a view showing a correction process using the relationship between voltage and SOC. Fig. 7 is a view schematically showing a first correction method. Fig. 8 is a view showing an example of correction of the SOC-OCV characteristic. Fig. 9 is a view showing an example of correction of the SOC-OCV characteristic. Fig. 10 is a view showing an example of the SOC-OCV characteristics of the first modification. Fig. 11 is a view showing a correction process when the SOC-OCV characteristic of Fig. 10 is used. Figure 12 is a look-up table showing the SOC dependence of the voltage drop V _DROP . Fig. 13 is a flow chart showing the residual amount detection in the second modification. Fig. 14 is a flow chart showing the ΔV calculation routine of Fig. 13. Fig. 15 is a view showing the estimation result of the SOC in the residual amount detection in the second modification. Figure 16 is a diagram showing an expanded VDR lookup table. Fig. 17 is a view showing the estimation result of the SOC in the residual amount detection in the fourth modification. Fig. 18 is a view showing a car equipped with a battery management system. Fig. 19 is a view showing an electronic apparatus including a battery management system.

S100~S120‧‧‧Steps

Claims (36)

A method for detecting a SOC (State Of Charge) of a rechargeable battery, comprising: (1) a step of generating a coulomb count CC by accumulating charge and discharge currents of the battery; (2) SOC1=(CC _FULL -CC)/CC _FULL ×100 (1) The step of generating the value SOC1 of the SOC, wherein CC _FULL is equivalent to a fully charged coulomb capacity value; and (3) a correction step; The above-mentioned correction step includes: (3-1) a step of generating an OCV value OCV1 corresponding to the value SOC1 based on the SOC-OCV characteristic indicating the correspondence between the SOC and the OCV (Open Circuit Voltage) which is defined in advance for the battery (3-2) a step of detecting the voltage V _BAT of the battery; (3-3) a step of generating a difference V _DROP1 between the value OCV1 and the detected value V _BAT1 of the voltage V _BAT of the battery; (3-4) generating a step of higher than the lowest operating voltage V _{BAT — MIN of the} system by a value OCV2 of the voltage amplitude ΔV corresponding to the differential V _DROP1 ; (3-5) generating a value of the SOC corresponding to the value OCV2 according to the SOC-OCV characteristic described above Step SOC2; and (3-6) setting the value SOC2 to be equal to the residual zero, the value SOC1 The step of correcting at least one of CC, C _FULL , and the SOC-OCV characteristics described above. A method of detecting the SOC of a rechargeable battery of claim 1, wherein ΔV = V _DROP1 . The requested item SOC of the battery pack 1 of the detection method, which further comprises: a pre-step of holding the difference OCV and SOC dependency of the battery voltage V _DROP of; OCV3 calculated provisional value of the OCV = V _{BAT _ MIN} + V _DROP1 of a step of generating a tentative value SOC3 of the SOC corresponding to the tentative value OCV3 of the OCV; and calculating a voltage drop ΔV at the value SOC3 based on the SOC dependency of the difference V _DROP1 and the difference V _{DROP at} the value SOC1. The method of claim 1, wherein the step of modifying (3-6) corrects the coulomb capacity value CC _FULL to be CC _FULL '=CC _FULL ×(100-SOC2)/ 100...(2) The resulting new value CC _FULL '. The method of detecting the SOC of the rechargeable battery according to claim 4, wherein (3-6) the step of modifying the above corrects the coulomb calculation CC to CC'=CC-(CC _FULL -CC _FULL ')... 3) The new value obtained CC'. The method for detecting the SOC of the rechargeable battery according to claim 4, wherein (3-6) the step of modifying the above corrects the coulomb value CC to CC'=CC-CC _FULL ×SOC2/100 (4) The resulting new value CC'. A method for detecting an SOC of a rechargeable battery according to claim 1, wherein the step (3-6) of the above correction is a new value SOC obtained by SOC'=SOC1×100/(100-SOC2) (5) 'As the corrected SOC. The method of detecting the SOC of the rechargeable battery of claim 4, wherein (3-6) the step of modifying the above does not correct the coulomb count CC. The method of claim 1, wherein the step (3-6) of the above correction is performed by SOC'={CC _FULL -CC×100/(100-SOC2)}/CC _FULL ×100 (6) The obtained value SOC' is taken as the corrected SOC. The method of claim 1, wherein the step of modifying (3-6) does not correct the coulomb capacity value CC _FULL , but corrects the coulomb value CC to CC'=CC. ×100/(100-SOC2) (7) The new value CC' obtained. The method for detecting the SOC of the rechargeable battery according to claim 4, wherein (3-6) the step of modifying the correction is to correct the coulomb calculation CC to CC'=CC×(100-SOC2)/100...(8) ) The new value obtained CC'. The method of claim 1, wherein the step (3-6) correcting the SOC-OCV characteristic is SOC'=100-(100-SOC)×100/(100-SOC2). ...(9) Make corrections. A method for detecting an SOC of a rechargeable battery according to claim 1, wherein said SOC-OCV characteristic associates a range of OCV lower than a lowest operating voltage of the system with a negative SOC. A method for detecting an SOC of a rechargeable battery according to claim 1, wherein the correcting step is effective when a voltage of the battery is lower than a specific voltage value. A method of detecting the SOC of a rechargeable battery according to claim 1, wherein the correcting step is effective when the SOC is lower than a specific value. A method of detecting the SOC of a rechargeable battery according to claim 1, wherein said correcting step is intermittently effective for each specific period. A method of detecting an SOC of a rechargeable battery according to claim 16, wherein said specific period is longer than 1 second and shorter than 60 seconds. A residual amount detecting circuit is characterized in that it detects a SOC (State Of Charge) of a rechargeable battery, and includes: a coulomb counter circuit that generates a coulomb count CC by accumulating charge and discharge currents of the battery And a voltage detecting circuit that detects a voltage V _{BAT of} the battery; and an SOC calculating unit that calculates a value SOC1 of the SOC according to the equation (1); SOC1=(CC _FULL −CC)/CC _FULL ×100 (1) CC _FULL is equivalent to a fully charged coulomb capacity value; and a correction circuit; the correction circuit is executed: generating and synchronizing based on a SOC-OCV characteristic indicating a correspondence between SOC and OCV (Open Circuit Voltage) prescribed in advance for the battery a step of the OCV value OCV1 corresponding to the value SOC1; a step of generating a difference V _DROP1 between the value OCV1 and the detected value V _BAT1 of the voltage detected by the voltage detecting circuit; generating a system minimum operating voltage V _{BAT _ MIN} and the step of comparing the difference value OCV2 V _DROP1 correspondence of the amplitude of the voltage ΔV; SOC2 step of generating the value of the SOC corresponding to the value of the above-described OCV2 SOC-OCV characteristics; and the above-described value SOC2 With the remaining amount were quite zero, value SOC1, CC, C _FULL SOC-OCV and said at least one characteristic of the correction step. A residual detection circuit of claim 18, wherein ΔV = V _DROP1 . The residual amount detecting circuit of claim 18, wherein the modifying circuit further performs: a step of maintaining a SOC dependency of a difference between the OCV and the battery voltage V _DROP ; and a step of calculating a tentative value OCV3=V _{BAT _ MIN} +V _DROP1 of the OCV; a step of generating a value SOC3 of the SOC corresponding to the tentative value OCV3 of the OCV; and a step of calculating the voltage drop ΔV of the SOC3 based on the SOC dependency of the difference V _{DROP1 of the} value SOC1 and the difference V _DROP . The residual amount detecting circuit of claim 18, wherein the step of correcting corrects the coulomb counter capacity value CC _FULL to a new one obtained by CC _FULL '=CC _FULL ×(100-SOC2)/100...(2) The value CC _FULL '. The residual amount detecting circuit of claim 21, wherein the step of correcting corrects the coulomb value CC to a new value CC' obtained by CC'=CC-(CC _FULL -CC _FULL ') (3) . The residual amount detecting circuit of claim 21, wherein the step of correcting corrects the coulomb count CC to a new value CC' obtained by CC'=CC-CC _FULL × SOC2/100 (4). The residual amount detecting circuit of claim 18, wherein the step of correcting corrects the SOC1 to a new value SOC' obtained by SOC' = SOC1 × 100 / (100 - SOC2) (5). The residual amount detecting circuit of claim 18, wherein the step of correcting does not correct the coulomb count CC. The residual amount detecting circuit of claim 18, wherein the step of correcting is a value SOC' obtained by SOC'={CC _FULL -CC×100/(100-SOC2)}/CC _FULL ×100 (6) As a corrected SOC. The residual amount detecting circuit of claim 18, wherein the step of correcting does not correct the coulomb counter capacity value CC _FULL , but corrects the coulomb counter value CC to CC'=CC×100/(100-SOC2)... (7) The new value obtained CC'. The residual amount detecting circuit of claim 21, wherein the step of correcting corrects the coulomb count CC to a new value CC' obtained by CC' = CC × (100 - SOC2) / 100 (8). The residual amount detecting circuit of claim 18, wherein (3-6) the step of correcting the SOC-OCV characteristic is SOC'=100-(100-SOC)×100/(100-SOC2) (9) Make corrections. The residual amount detecting circuit of claim 18, wherein the SOC-OCV characteristic associates a range of OCV lower than a lowest operating voltage of the system with a negative SOC. The residual amount detecting circuit of claim 18, wherein the correcting circuit is effective when a voltage of the battery is lower than a specific voltage value. The residual amount detecting circuit of claim 18, wherein the correcting circuit is effective when the SOC is lower than a specific value. A residual amount detecting circuit as claimed in claim 18, wherein said correcting circuit is intermittently enabled for each specific period. The residual amount detecting circuit of claim 33, wherein the specific period is longer than 1 second and shorter than 60 seconds. An electronic apparatus comprising: a rechargeable battery; and a residual amount detecting circuit of any one of claims 18 to 34 for detecting a state of the battery. An automobile characterized by comprising: a rechargeable battery; and a residual amount detecting circuit of any one of claims 18 to 34 for detecting a state of the battery.