Remaining amount notification device, remaining amount notification method, and remaining amount notification program

Abstract

A remaining capacity notification device for providing notification of a remaining capacity of a secondary battery mounted on an apparatus, wherein a reliability determination unit determines the reliability degree of a state of charge (SOC) indicating a secondary-battery remaining capacity which should be notified to a user of the apparatus, on the basis of the slope of a SOC-open circuit voltage (SOC-OCV) curve of the secondary battery, corresponding to the SOC. The notification control unit performs control such that the remaining capacity of the secondary battery is to be notified in a notification mode based on the reliability degree of the determined SOC.

Description

[Technical Field]

[0001] The present disclosure relates to a remaining battery charge notification device, a remaining battery charge notification method, and a remaining battery charge notification program for notifying a user of the remaining battery charge of a secondary battery. [Background technology]

[0002] In recent years, electric vehicles (EVs), plug-in hybrid vehicles (PHVs), and hybrid vehicles (HVs) have become increasingly popular. These electric vehicles are equipped with secondary batteries as key devices. Managing the SOC (State Of Charge) of secondary batteries is important for electric vehicles. The current integration method and the OCV (Open Circuit Voltage) method are mainly used to estimate the SOC of secondary batteries. The current integration method is an estimation method that is mainly used when the vehicle is running or charging, while the OCV method is an estimation method that is mainly used when the vehicle is stopped. With the OCV method, the SOC is estimated based on the SOC-OCV curve.

[0003] When the SOC-OCV curve has a flat region, as in the case of a lithium iron phosphate (LFP) battery, it is difficult to estimate the SOC from the OCV with high accuracy in the flat region. To address this issue, a method has been proposed in which the battery state is determined to be in the flat region of the SOC-OCV curve, and if it is in the flat region, the SOC determined by the OCV method is not adopted (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-38437 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-83474 Summary of the Invention

[0005] In the above-mentioned method, if charging and discharging are repeated in short bursts in the flat region, the OCV will not reset the SOC error or update the FCC (Full Charge Capacity). As a result, the accuracy of the SOC estimation will decrease, and unexpected battery shortages may occur. In addition, some electric vehicles require users to perform operations aimed at resetting the error, which is not in line with the user's intention (for example, discharging to a low SOC, leaving the vehicle idle for a long period of time, and then charging to a fully charged state).

[0006] The present disclosure has been made in light of these circumstances, and its purpose is to provide a technology that allows users to naturally learn how to understand and reset the SOC error during everyday operation.

[0007] In order to solve the above problem, one embodiment of the remaining battery charge notification device of the present invention is a remaining battery charge notification device that notifies the user of the device of the remaining battery charge of a secondary battery installed in the device, and includes a reliability determination unit that determines the reliability of the SOC indicating the remaining battery charge of the secondary battery to be notified to the user of the device based on the slope of the SOC-OCV curve of the secondary battery corresponding to the SOC, and a notification control unit that controls the notification of the remaining battery charge in a notification mode based on the determined reliability of the SOC.

[0008] Any combination of the above components, and conversion of the expression of the present disclosure into an apparatus, method, system, computer program, etc., are also valid aspects of the present disclosure.

[0009] According to the present disclosure, the user can naturally learn how to understand and reset the SOC error during normal operation. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram for explaining an outline of a traffic management support system according to an embodiment; [Figure 2] 1 is a diagram showing a schematic configuration of an electric vehicle according to an embodiment; [Figure 3]FIG. 2 is a diagram illustrating a detailed configuration of a power supply system mounted on an electric vehicle according to an embodiment. [Figure 4] FIG. 2 is a diagram illustrating the configuration of a vehicle control unit. [Figure 5] 10A and 10B are diagrams showing examples of an SOC-OCV curve and a battery remaining capacity reliability curve. [Figure 6A] FIG. 6A is a diagram showing an example of a reliability conversion map used when calculating the reliability of the overall SOC based on the remaining battery capacity reliability and the downtime. [Figure 6B] FIG. 6B is a diagram showing an example of a reliability conversion map used when calculating the reliability of the overall SOC based on the remaining battery capacity reliability and the downtime. [Figure 7A] FIG. 7A is a diagram showing an example of a remaining battery charge displayed on a display unit of an electric vehicle. [Figure 7B] FIG. 7B is a diagram showing an example of a remaining battery charge displayed on a display unit of an electric vehicle. [Figure 7C] FIG. 7C is a diagram showing an example of a remaining battery charge displayed on a display unit of an electric vehicle. [Figure 8] 10 is a diagram showing the correspondence between the length of downtime and the color of the remaining battery capacity display when only the length of downtime is reflected in the remaining battery capacity display. FIG. [Figure 9] 1 is a diagram for explaining a traffic management support system according to an embodiment; [Figure 10] 10A and 10B are diagrams showing specific examples of SOCv, a lower limit SOC, and an SOC error based on the OCV method. [Figure 11] FIG. 10 is a diagram illustrating an example of a format of battery management information. [Figure 12] FIG. 1 is a diagram for explaining an example of a basic algorithm for traffic management. [Figure 13A] FIG. 13A is a diagram showing an example of a remaining battery charge displayed on the fleet management terminal device. [Figure 13B] FIG. 13B is a diagram showing an example of a remaining battery charge displayed on the fleet management terminal device. [Figure 13C] FIG. 13C is a diagram showing an example of a remaining battery charge displayed on the fleet management terminal device. [Figure 14] 4 is a flowchart showing the flow of a process for determining whether to recommend discharging or charging a battery pack mounted on an electric vehicle, performed by the operation management support system according to the embodiment. [Figure 15A] FIG. 15A is a diagram showing another example of the remaining battery charge displayed on the display unit of the electric vehicle. [Figure 15B] FIG. 15B is a diagram showing another example of the remaining battery charge displayed on the display unit of the electric vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 1 is a diagram for explaining an outline of a traffic management support system 1 according to an embodiment.

[0012] The traffic management support system 1 according to the embodiment is a system used by at least one delivery company. The traffic management support system 1 may be constructed, for example, on an in-house server installed in the in-house facility or data center of a service provider that provides traffic management support services for electric vehicles 3. The traffic management support system 1 may also be constructed on a cloud server used based on a cloud service. The traffic management support system 1 may also be constructed on multiple servers distributed across multiple bases (data centers, in-house facilities). The multiple servers may be a combination of multiple in-house servers, a combination of multiple cloud servers, or a combination of an in-house server and a cloud server.

[0013] A delivery company owns multiple electric vehicles 3 and chargers 4, and has a delivery base where the electric vehicles 3 are parked. An operation management terminal device 2 is installed at the delivery base. The operation management terminal device 2 is configured, for example, by a PC. The operation management terminal device 2 is used to manage the multiple electric vehicles 3 belonging to the delivery base. The delivery company's operation manager can use the operation management terminal device 2 to create delivery plans and charging plans for the multiple electric vehicles 3.

[0014] The operation management terminal device 2 can access the operation management support system 1 via the network 5. The operation management terminal device 2 can acquire battery state management information of the multiple electric vehicles 3 held by the operation management support system 1.

[0015] Network 5 is a general term for communication paths such as the Internet, dedicated lines, and VPNs (Virtual Private Networks), and the communication media and protocols are not important. Examples of communication media that can be used include mobile phone networks (cellular networks), wireless LANs, wired LANs, optical fiber networks, ADSL networks, and CATV networks. Examples of communication protocols that can be used include TCP (Transmission Control Protocol) / IP (Internet Protocol), UDP (User Datagram Protocol) / IP, and Ethernet (registered trademark).

[0016] FIG. 2 is a diagram showing a schematic configuration of an electric vehicle 3 according to an embodiment. In this embodiment, the electric vehicle 3 is assumed to be a pure EV that is not equipped with an internal combustion engine. The electric vehicle 3 shown in FIG. 2 is a rear-wheel drive (2WD) EV that has a pair of front wheels 31f, a pair of rear wheels 31r, and a motor 34 as a power source. The pair of front wheels 31f are connected by a front wheel axle 32f, and the pair of rear wheels 31r are connected by a rear wheel axle 32r. A transmission 33 transmits the rotation of the motor 34 to the rear wheel axle 32r at a predetermined conversion ratio. Note that the electric vehicle 3 may be a front-wheel drive (2WD) or 4WD electric vehicle.

[0017] The power supply system 40 includes a battery pack 41 and a battery management unit 42. The battery pack 41 includes a plurality of cells. The cells may be lithium-ion battery cells, nickel-metal hydride battery cells, or the like. In the following description, an example using lithium-ion battery cells is assumed. The battery management unit 42 monitors the voltage, current, temperature, SOC, FCC, and SOH (State Of Health) of the plurality of cells included in the battery pack 41, and transmits the information to the vehicle control unit 30 via an in-vehicle network. For example, a CAN (Controller Area Network) or a LIN (Local Interconnect Network) may be used as the in-vehicle network.

[0018] In EVs, a three-phase AC motor is generally used as the drive motor 34. During power running, the inverter 35 converts DC power supplied from the battery pack 41 into AC power and supplies it to the motor 34. During regeneration, the inverter 35 converts AC power supplied from the motor 34 into DC power and supplies it to the battery pack 41. During power running, the motor 34 rotates in response to the AC power supplied from the inverter 35. During regeneration, the motor 34 converts rotational energy generated by deceleration into AC power and supplies it to the inverter 35.

[0019] The vehicle control unit 30 is a vehicle ECU (Electronic Control Unit) that controls the entire electric vehicle 3, and may be configured as, for example, an integrated VCM (Vehicle Control Module).

[0020] The GPS sensor 361 detects the position information of the electric vehicle 3 and transmits the detected position information to the vehicle control unit 30. Specifically, the GPS sensor 361 receives radio waves, including the respective transmission times, from a plurality of GPS satellites, and calculates the latitude and longitude of the reception point based on the plurality of transmission times included in the plurality of received radio waves.

[0021] The vehicle speed sensor 362 generates a pulse signal proportional to the rotation speed of the front wheel shaft 32f or the rear wheel shaft 32r, and transmits the generated pulse signal to the vehicle control unit 30. The vehicle control unit 30 detects the speed of the electric vehicle 3 based on the pulse signal received from the vehicle speed sensor 362.

[0022] The wireless communication unit 37 performs signal processing for wirelessly connecting to the network 5 via the antenna 37a. Examples of wireless communication networks that can be used by the electric vehicle 3 include a mobile phone network (cellular network), a wireless LAN, V2I (Vehicle-to-Infrastructure), V2V (Vehicle-to-Vehicle), an ETC system (Electronic Toll Collection System), and DSRC (Dedicated Short Range Communications).

[0023] The display unit 38 is a display capable of displaying text and images, and may be a liquid crystal display, an organic EL display, a mini LED display, or the like. The display unit 38 may be a display converted from a tablet device, car navigation system, display audio, drive recorder, or the like installed in the vehicle, or may be a display installed in the meter panel. The display unit 38 may also be a display converted from a user's tablet device or smartphone linked to an in-vehicle device.

[0024] The speaker 39 outputs a voice message. The speaker 39 may be a speaker adapted from a car navigation system, a display audio, a drive recorder, or the like, or may be an independent speaker.

[0025] While the electric vehicle 3 is traveling, the vehicle control unit 30 can transmit traveling data in real time from the wireless communication unit 37 to the traffic management support system 1 via the network 5. The traveling data includes the position data (latitude and longitude) of the electric vehicle 3, the vehicle speed of the electric vehicle 3, and the voltage, current, temperature, SOC, and SOH of multiple cells included in the battery pack 41. The vehicle control unit 30 samples this data periodically (for example, every 10 seconds) and transmits it to the traffic management support system 1 each time.

[0026] The vehicle control unit 30 may accumulate driving data of the electric vehicles 3 in an internal driving data storage unit 321 (see FIG. 4 ) and transmit the driving data accumulated in the driving data storage unit 321 in a lump sum at a predetermined timing. For example, the vehicle control unit 30 may transmit the driving data accumulated in the driving data storage unit 321 in a lump sum to the operation management terminal device 2 installed at the delivery company base after the end of business for the day. The operation management terminal device 2 transmits the driving data of the multiple electric vehicles 3 to the operation management support system 1 at a predetermined timing.

[0027] FIG. 3 is a diagram illustrating a detailed configuration of a power supply system 40 mounted on an electric vehicle 3 according to an embodiment. The power supply system 40 is connected to the motor 34 via a first relay RY1 and an inverter 35. The first relay RY1 is a contactor inserted between the wiring connecting the power supply system 40 and the inverter 35. The vehicle control unit 30 controls the first relay RY1 to an on state (closed state) when the vehicle is running, thereby electrically connecting the power supply system 40 and the power system of the electric vehicle 3. When the vehicle is not running, the vehicle control unit 30 controls the first relay RY1 to an off state (open state) as a general rule, thereby electrically disconnecting the power supply system 40 and the power system of the electric vehicle 3. Note that instead of a relay, other types of switches, such as a semiconductor switch, may be used.

[0028] By connecting the electric vehicle 3 to the charger 4 via a charging cable, the battery pack 41 in the power supply system 40 can be charged externally. The charger 4 is connected to a commercial power grid 6 and charges the battery pack 41 in the electric vehicle 3. In the electric vehicle 3, a second relay RY2 is inserted between the wiring connecting the power supply system 40 and the charger 4. Before charging starts, the battery management unit 42 controls the second relay RY2 to the on state via the vehicle control unit 30 or directly, and controls the second relay RY2 to the off state after charging is completed.

[0029] Generally, normal charging is performed with AC, and rapid charging is performed with DC. When charging with AC (for example, single-phase 100 / 200V), AC power is converted to DC power by an AC / DC converter (not shown) inserted between second relay RY2 and power supply system 40. When charging with DC, charger 4 generates DC power by full-wave rectifying AC power supplied from commercial power system 6 and smoothing it with a filter.

[0030] The battery pack 41 includes a plurality of cells E1-En connected in series. The number of cells E1-En connected in series is determined according to the drive voltage of the motor 34. The battery pack 41 may be configured by combining a plurality of battery modules.

[0031] A shunt resistor Rs is connected in series with the cells E1-En. The shunt resistor Rs functions as a current detection element. A Hall element may be used instead of the shunt resistor Rs. A plurality of temperature sensors T1 and T2 are installed in the battery pack 41 to detect the temperatures of the cells E1-En. The temperature sensors T1 and T2 may be, for example, thermistors.

[0032] The battery management unit 42 includes a voltage measurement unit 43, a temperature measurement unit 44, a current measurement unit 45, and a battery control unit 46. Multiple voltage lines connect each node of the multiple series-connected cells E1-En to the voltage measurement unit 43. The voltage measurement unit 43 measures the voltage of each cell E1-En by measuring the voltage between each two adjacent voltage lines. The voltage measurement unit 43 transmits the measured voltage of each cell E1-En to the battery control unit 46.

[0033] Because the voltage measurement unit 43 has a higher voltage than the battery control unit 46, the voltage measurement unit 43 and the battery control unit 46 are connected by a communication line while being insulated from each other. The voltage measurement unit 43 can be configured using an ASIC (Application Specific Integrated Circuit) or a general-purpose analog front-end IC. The voltage measurement unit 43 includes a multiplexer and an A / D converter. The multiplexer outputs the voltage between two adjacent voltage lines to the A / D converter in order from top to bottom. The A / D converter converts the analog voltage input from the multiplexer into a digital value.

[0034] The temperature measurement unit 44 includes a voltage dividing resistor and an A / D converter. The A / D converter sequentially converts multiple analog voltages, each divided by the multiple temperature sensors T1 and T2 and the multiple voltage dividing resistors, into digital values ​​and outputs them to the battery control unit 46. The battery control unit 46 estimates the temperatures of the multiple cells E1-En based on the digital values. For example, the battery control unit 46 estimates the temperature of each cell E1-En based on the value measured by the temperature sensor closest to each cell E1-En.

[0035] The current measurement unit 45 includes a differential amplifier and an A / D converter. The differential amplifier amplifies the voltage across the shunt resistor Rs and outputs the amplified voltage to the A / D converter. The A / D converter converts the analog voltage input from the differential amplifier into a digital value and outputs the digital value to the battery control unit 46. The battery control unit 46 estimates the current flowing through the multiple cells E1-En based on the digital value.

[0036] In addition, if an A / D converter is installed in the battery control unit 46 and an analog input port is installed in the battery control unit 46, the temperature measurement unit 44 and the current measurement unit 45 may output analog voltages to the battery control unit 46, which may be converted into digital values ​​by the A / D converter in the battery control unit 46.

[0037] The battery control unit 46 manages the states of the cells E1-En based on the voltages, temperatures, and currents of the cells E1-En measured by the voltage measurement unit 43, temperature measurement unit 44, and current measurement unit 45. The battery control unit 46 can be configured with a microcontroller and non-volatile memory (e.g., an EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory). The battery control unit 46 estimates the SOC, FCC, and SOH of each of the cells E1-En.

[0038] The battery control unit 46 estimates the SOC by combining the current integration method and the OCV method. The OCV method estimates the OCV from the voltage of each cell E1-En measured by the voltage measurement unit 43, the temperature of each cell E1-En measured by the temperature measurement unit 44, and the current of each cell E1-En measured by the current measurement unit 45. The OCV method then estimates the SOC based on the estimated OCV and the SOC-OCV curve of each cell E1-En. Because the OCV is the voltage component obtained by subtracting the polarization voltage from the measured voltage, the SOC based on the OCV method can be calculated even during charging and discharging by estimating the polarization voltage from the current, temperature, SOH, etc. The SOC-OCV curve of each cell E1-En is created in advance based on performance tests conducted by the battery manufacturer and is registered in the microcontroller's internal memory at the time of shipment.

[0039] The current integration method is a method for estimating the SOC based on the OCV of each cell E1-En at the start of charging / discharging and the integrated value of the current measured by the current measurement unit 45. Specifically, the SOCi using the current integration method is calculated using the following formula (1).

[0040] SOCi = SOCv at the start of charging / discharging ± (integrated current value / FCC) (Equation 1) In the current integration method, measurement errors by the current measurement unit 45 accumulate as the charge / discharge time increases. On the other hand, the OCV method is affected by measurement errors by the voltage measurement unit 43 and errors due to polarization voltage. Therefore, the battery control unit 46 may estimate the SOC by taking a weighted average of the SOCi estimated by the current integration method and the SOCv estimated by the OCV method, as shown in the following (Equation 2).

[0041] SOC=SOCi*x+SOCv*(1-x) (Formula 2) x indicates the degree of contribution, and is set, for example, to approach 1 during charging / discharging and to approach 0 during rest. Note that the SOCi during charging / discharging may be corrected by a method other than the weighted average using SOCv, and used as the SOC during charging / discharging.

[0042] The battery control unit 46 can estimate the FCC based on the difference between two SOCv values ​​corresponding to two OCV values ​​measured before and after charging and discharging, and the integrated current value between the two points, as shown in the following equation (3).

[0043] FCC = current integrated value / ΔSOCv (Equation 3) SOH is defined as the ratio of the current FCC to the initial FCC, and a lower value (closer to 0%) indicates more advanced deterioration. The battery control unit 46 can estimate SOH based on the initial FCC and the current FCC, as shown in the following (Equation 4).

[0044] SOH = current FCC / initial FCC (Equation 4) The battery control unit 46 estimates the SOC, FCC, and SOH of the battery pack 41 based on the SOC, FCC, and SOH of the multiple cells E1-En. The battery control unit 46 transmits the voltage, current, temperature, SOC, FCC, and SOH of each of the cells E1-En and the battery pack 41 to the vehicle control unit 30 via the in-vehicle network.

[0045] The vehicle control unit 30 can estimate the cruising distance based on the SOC of the battery pack 41 and the cruising distance coefficient, as shown in the following (Equation 5) to (Equation 7).

[0046] Cruising range = SOC × Cruising range coefficient (Equation 5) Cruising range coefficient = Δ driving distance / ΔSOCv (Equation 6) ΔSOCv = SOCv before driving - SOCv after driving (Equation 7) 4 is a diagram illustrating the configuration of vehicle control unit 30. Vehicle control unit 30 includes processing unit 310 and storage unit 322. Processing unit 310 includes SOC acquisition unit 311, reliability determination unit 312, display control unit 313, and voice synthesis unit 314. Note that processing unit 310 only illustrates functional blocks related to the remaining current notification process, which is of interest in this embodiment.

[0047] The functions of the processing unit 310 can be realized by a combination of hardware and software resources, or by hardware resources alone. Hardware resources include a CPU, ROM, RAM, GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), and other LSIs. Software resources include an operating system, application programs, and other programs.

[0048] The storage unit 320 includes a travel data holding unit 321. The storage unit 320 includes a non-volatile recording medium such as an HDD or SSD, and stores various data. The travel data holding unit 321 holds travel data including the voltage, current, temperature, SOC, FCC, and SOH of each cell E1-En and the battery pack 41 received from the battery control unit 46, as well as position data of the electric vehicle 3, vehicle speed, and accumulated travel distance obtained from various sensors within the electric vehicle 3.

[0049] The SOC acquisition unit 311 acquires the SOC of the battery pack 41 (hereinafter referred to as the presented SOC), which indicates the remaining battery power to be notified to a passenger (mainly the driver) in the electric vehicle 3, from the battery control unit 46. The presented SOC can also be estimated by the operation management support system 1. In this case, the SOC acquisition unit 311 receives the presented SOC from the operation management support system 1 via the network 5.

[0050] The reliability determination unit 312 determines the reliability of the presented SOC based on the slope of the SOC-OCV curve corresponding to the presented SOC. The reliability determination unit 312 evaluates the reliability of the presented SOC higher the greater the slope of the SOC-OCV curve corresponding to the presented SOC. The slope of the SOC-OCV curve can be defined by the differential curve of the SOC-OCV curve. This differential curve of the SOC-OCV curve is used as the remaining battery capacity reliability curve.

[0051] FIG. 5 is a diagram showing an example of an SOC-OCV curve and a battery remaining capacity reliability curve. FIG. 5 shows the SOC-OCV curve and the battery remaining capacity reliability curve of a certain lithium iron phosphate (LFP) battery. As shown in FIG. 5, a high reliability threshold and a low reliability threshold are set for the battery remaining capacity reliability. The region above the high reliability threshold (hereinafter referred to as the high reliability region) is a region where the reliability of the SOCv estimated by the OCV method is high, and the region below the low reliability threshold (hereinafter referred to as the low reliability region) is a region where the reliability of the SOCv is low. The region above the low reliability threshold and below the high reliability threshold (hereinafter referred to as the medium reliability region) is a region where the reliability of the SOCv is intermediate.

[0052] The display control unit 313 controls the display unit 38 to display the remaining battery level in a display manner based on the reliability of the presented SOC determined by the reliability determination unit 312. More specifically, the display control unit 313 controls the display unit 38 to display the remaining battery level in a manner that is more noticeable as the reliability of the presented SOC increases.

[0053] The display control unit 313 controls the display color of the remaining battery level so that, for example, when the remaining battery level reliability is in the high reliability range, the display color is a first color, when the remaining battery level reliability is in the low reliability range, the display color is a second color, and when the remaining battery level reliability is in the medium reliability range, the display color is a gradation between the first color and the second color. The first color may be a light color and the second color may be a dark color, for example, the first color may be green and the second color may be blue. In the medium reliability range, the gradation level changes in proportion to the remaining battery level reliability. Note that when a monochrome display is used for the display unit 38, the first color is white and the second color is black, and the medium reliability range is expressed in grayscale.

[0054] In the example shown in Fig. 5, the range of OCV to be expressed in gradations is narrowed by setting a high reliability threshold and a low reliability threshold. This prevents a change in display color in response to a small change in OCV from becoming so minute that the user cannot visually recognize it. Note that the display control unit 313 may simply control the display color of the remaining battery capacity so that a first color is displayed when the remaining battery capacity reliability is in the high reliability range, and a second color is displayed when the remaining battery capacity reliability is outside the high reliability range.

[0055] As described above, the SOCv estimated by the OCV method is affected by diffusion polarization. After charging and discharging of the battery pack 41 is stopped, it takes time for the polarization to disappear and for the measured voltage value to converge to the OCV. Therefore, after the electric vehicle 3 stops traveling or charging from the charger 4 is stopped, the elapsed time from the stop (hereinafter referred to as the downtime) also affects the reliability of the presented SOC.

[0056] 6A and 6B are diagrams showing examples of reliability conversion maps used to calculate the overall SOC reliability based on the remaining battery capacity reliability and downtime. FIG. 6A is a map for converting the remaining battery capacity reliability shown in FIG. 5 into a normalized reliability. The normalized SOC reliability ranges from 0 to 1, with values ​​closer to 1 indicating higher reliability. FIG. 6B is a map for converting downtime into a normalized reliability. The normalized downtime reliability ranges from 0 to 1, with values ​​closer to 1 indicating higher reliability. Note that the characteristics of the downtime reliability curve are highly dependent on the material used for the cell electrodes. In the example shown in FIG. 6B, the polarization voltage disappears from the measured voltage after a three-hour downtime.

[0057] The reliability determination unit 312 can calculate the reliability Rsoc of the presented SOC by taking a weighted average of the reliability Rsoci of SOCi estimated by the current integration method and the reliability Rsocv of SOCv estimated by the OCV method, as shown in the following (Equation 8). When taking the weighted average of the two reliabilities Rsoci and Rsocv, the reliability Rrest of the downtime is used as the contribution of the reliability Rsocv of SOCv.

[0058] Rsoc=Rsoci*(1-Rrest)+Rsocv*Rrest (Formula 8) The map shown in FIG. 6B shows an example in which the contribution of the SOCv estimated by the OCV method is 0 while driving or charging (the SOCi estimated by the current integration method becomes the presented SOC as is), but the SOCv estimated by the OCV method may also have a certain contribution while driving or charging.

[0059] The reliability determination unit 312 calculates the reliability of the remaining battery capacity based on the SOCi estimated by the current integration method and the SOC-OCV curve (see FIG. 5), and calculates the reliability Rsoci of SOCi based on the calculated reliability of the remaining current capacity (see FIG. 6A).The reliability determination unit 312 calculates the reliability of the remaining battery capacity based on the SOCv estimated by the OCV method and the SOC-OCV curve (see FIG. 5), and calculates the reliability Rsocv of SOCv based on the calculated reliability of the remaining current capacity (see FIG. 6A).

[0060] The reliability determination unit 312 calculates the reliability Rrest of the rest time based on the rest time of the battery pack 41 (see FIG. 6B). The reliability determination unit 312 calculates the reliability Rsoc of the presented SOC based on the reliability Rsoci of SOCi, the reliability Rsocv of SOCv, and the reliability Rrest of the rest time (see Equation 8). The reliability determination unit 312 calculates the reliability of the remaining battery capacity based on the calculated presented SOC and the SOC-OCV curve (see FIG. 5). The display control unit 313 controls the display unit 38 to display the remaining battery capacity corresponding to the presented SOC in a display mode according to the calculated reliability of the remaining battery capacity.

[0061] 7A to 7C show examples of remaining battery capacity displayed on the display unit 38 of the electric vehicle 3. Fig. 7A shows an example of the display when the remaining battery capacity reliability is in the low reliability region, Fig. 7B shows an example of the display when the remaining battery capacity reliability is in the medium reliability region, and Fig. 7C shows an example of the display when the remaining battery capacity reliability is in the high reliability region.

[0062] While the electric vehicle 3 is running or charging, the display color of the remaining battery capacity changes mainly due to changes in the presented SOC associated with changes in SOCi. While the vehicle is stopped, the display color of the remaining battery capacity changes mainly due to changes in the presented SOC associated with changes in SOCv. When polarization is eliminated, the change in the presented SOC stops.

[0063] For example, if the battery level indicator is in the second color (e.g., blue) when the vehicle is stopped and remains in the second color while stopped, this indicates that the error in SOCi is small. On the other hand, if the battery level indicator is in the second color when the vehicle is stopped and changes to the first color (e.g., green) while stopped, this indicates that the error in SOCi is large. In other words, there is a possibility that the FCC, a parameter required for estimating SOCi, is out of sync.

[0064] Furthermore, if the vehicle is stopped while the remaining battery capacity indicator is in the first color and remains in the first color while stopped, this indicates that the error in SOCi is small. However, this is significantly affected by measurement errors in the voltage measurement unit 43. In contrast, if the vehicle is stopped while the remaining battery capacity indicator is in the first color and changes to the second color while stopped, this indicates that the error in SOCi is large. In other words, there is a possibility that the FCC, which is a parameter required to estimate SOCi, is out of sync.

[0065] After the electric vehicle 3 stops, the remaining battery capacity display may reflect only the length of the downtime. In this case, the display control unit 313 displays the remaining battery capacity display in the first color when the electric vehicle 3 stops traveling, and changes the color closer to the second color as the downtime becomes longer. The same control may be performed after charging from the charger 4 stops.

[0066] 8 is a diagram showing the correspondence relationship between the length of the downtime and the color of the remaining battery capacity display when only the length of the downtime is reflected in the remaining battery capacity display. In this case, the user can understand the reliability of the remaining battery capacity from the color of the remaining battery capacity display, as well as the elapsed time since the electric vehicle 3 stopped traveling or charging from the charger 4 stopped.

[0067] Returning to Fig. 4, the voice synthesis unit 314 outputs a battery remaining amount notification message, which reflects the reliability of the presented SOC determined by the reliability determination unit 312, from the speaker 39. For example, when the electric vehicle 3 stops traveling, the voice synthesis unit 314 outputs the value of the presented SOC indicating the remaining battery amount, and the value and classification level of the reliability of the presented SOC (see Fig. 6A) from the speaker 39. Note that it is sufficient to include at least one of the display control unit 313 and the voice synthesis unit 314, and either one can be omitted.

[0068] 9 is a diagram illustrating a traffic management support system 1 according to an embodiment. The traffic management support system 1 includes a processing unit 11, a storage unit 12, and a communication unit 13. The communication unit 13 is a communication interface for connecting to a network 5 via a wired or wireless connection.

[0069] The processing unit 11 includes a driving data acquisition unit 111, a corrected SOC calculation unit 112, a charge / discharge recommendation determination unit 113, and a battery management information generation unit 114. The functions of the processing unit 11 can be realized by a combination of hardware resources and software resources, or by hardware resources alone. As hardware resources, a CPU, ROM, RAM, GPU, ASIC, FPGA, and other LSIs can be used. As software resources, programs such as an operating system and applications can be used.

[0070] The storage unit 12 includes a traveling data storage unit 121 and a battery management information storage unit 122. The storage unit 12 includes a non-volatile recording medium such as an HDD or SSD, and stores various data. The traveling data acquisition unit 111 acquires traveling data from each electric vehicle 3 via the network 5 and stores the data in the traveling data storage unit 121.

[0071] First, the worst downward value of the offset error of the voltage sensor used as the voltage measurement unit 43 is set as the voltage margin. The corrected SOC calculation unit 112 calculates the lower limit SOC by subtracting the voltage margin from the SOCv based on the OCV method. The corrected SOC calculation unit 112 calculates the SOC error by subtracting the lower limit SOC from the presented SOC. It is desirable to calculate the SOC error when the reliability of the downtime is equal to or greater than a set value (e.g., 0.67).

[0072] The SOCv and presented SOC based on the OCV method may be obtained from the vehicle control unit 30 of the electric vehicle 3, or may be calculated by the operation management support system 1. When calculated by the operation management support system 1, it is necessary to prepare SOC-OCV curves for cells E1-En included in the battery pack 41 mounted on each electric vehicle 3. This SOC-OCV curve may be prepared based on catalog values ​​from the battery manufacturer, or may be generated based on battery data collected from each electric vehicle 3. In the latter case, an SOC-OCV curve may be generated for each electric vehicle 3, or an SOC-OCV curve may be generated for each vehicle of the same model.

[0073] 10 is a diagram showing specific examples of SOCv, lower limit SOC, and SOC error based on the OCV method. The corrected SOC calculation unit 112 calculates the corrected SOC by subtracting the SOC error from the presented SOC. The charge / discharge recommendation determination unit 113 recommends charging if the corrected SOC is less than the low SOC threshold (20% in FIG. 10), and recommends discharging if the corrected SOC is equal to or greater than the low SOC threshold.

[0074] The battery management information generating unit 114 generates battery management information for each battery pack 41 mounted on each electric vehicle 3 and stores the information in the battery management information holding unit 122 .

[0075] Fig. 11 is a diagram showing an example of the format of battery management information. In the format shown in Fig. 11, the vehicle ID, message (charging recommended / discharging recommended), presented SOC, corrected SOC, reliability of presented SOC, and reliability of downtime are managed as battery management information.

[0076] The operations manager of the delivery company can refer to the battery management information of the multiple electric vehicles 3 owned by the company, which has been generated by the operations management support system 1, from the operations management terminal device 2. The operations manager can create delivery plans and charging plans based on the battery management information of the multiple electric vehicles 3. To avoid the risk of the electric vehicles 3 running out of battery, the operations manager urges the drivers of electric vehicles 3 that are recommended to be charged to charge them as soon as possible.

[0077] The operations manager creates a delivery plan and a charging plan for each electric vehicle 3 so that the vehicle will be parked for a long period of time while the SOC of the battery pack 41 of each electric vehicle 3 is in a highly reliable range. That is, the operations manager creates a delivery plan or a charging plan so that the predicted SOC value after delivery or charging is completed falls within a highly reliable range. The predicted SOC value after delivery or charging is completed is calculated taking into account the above-mentioned SOC error.

[0078] The delivery plan and the charging plan may be automatically created by a predetermined operation management program. The operation management program may be installed in the operation management terminal device 2 or in the operation management support system 1. In the latter case, the operation management terminal device 2 can download an operation management table of the multiple electric vehicles 3 owned by the company from the operation management support system 1.

[0079] FIG. 12 is a diagram illustrating an example of a basic algorithm for operation management. In the example shown in FIG. 12, 0 to 20% is set as the low SOC region. An electric vehicle 3 whose battery pack 41 has an SOC in the low SOC region needs to be charged. At that time, the charge rate and charge time are determined so that the SOC after charging is complete falls within the high reliability region. For an electric vehicle 3 whose battery pack 41 has an SOC outside the low SOC region, a delivery route is determined so that the SOC after delivery is complete falls within the high reliability region.

[0080] 13A-13C show examples of remaining battery capacity displayed on the fleet management terminal device 2. Fig. 13A shows an example of the display when the remaining battery capacity reliability is in the normal range, Fig. 13B shows an example of the display when the remaining battery capacity reliability is in the high reliability range, and Fig. 13C shows an example of the display when the remaining battery capacity reliability is in the low SOC range. In each example, the display shows whether discharging / charging is recommended and the maximum error between the presented SOC and SOCv.

[0081] 14 is a flowchart showing the flow of a process for determining whether to recommend discharging or charging the battery pack 41 mounted on the electric vehicle 3, performed by the operation management support system 1 according to the embodiment. The corrected SOC calculation unit 112 calculates a lower limit SOC by subtracting a voltage margin (maximum downward offset error of the voltage sensor) from the SOCv based on the OCV method (S10). When the rest time of the battery pack 41 has elapsed for a set time (e.g., one hour) (Y in S11), the corrected SOC calculation unit 112 calculates an SOC error by subtracting the lower limit SOC from the presentation SOC calculated to be presented in the vehicle (S12). The corrected SOC calculation unit 112 calculates a corrected SOC by subtracting the SOC error from the presentation SOC (S13).

[0082] The charge / discharge recommendation determination unit 113 compares the SOC error with a low SOC threshold (e.g., 20%) (S14). If the SOC error is equal to or greater than the low SOC threshold (Y in S14), the charge / discharge recommendation determination unit 113 determines that the target electric vehicle 3 should be discharged (S15). If the SOC error is less than the low SOC threshold (N in S14), the charge / discharge recommendation determination unit 113 determines that the target electric vehicle 3 should be charged (S16).

[0083] While the remaining charge of the battery pack 41 of the electric vehicle 3 continues to be monitored (N in S17), the process proceeds to step S12, and the processes of steps S12 to S16 are repeatedly executed. As described above, the presented SOC changes depending on the length of the pause time.

[0084] As described above, according to this embodiment, adding qualitative information visually indicating reliability to the remaining battery capacity display allows the user to naturally learn to grasp and reset the SOC error in daily operation. Specifically, in the region where the SOC-OCV curve has a steep slope (high SOC reliability region), the remaining battery capacity display is displayed in a conspicuous color, making it possible to make the user aware of the need to stop or park the vehicle for long periods of time in the non-flat region of the SOC-OCV curve.

[0085] Furthermore, as shown in Figure 5 above, by regarding battery remaining capacity reliability above the high reliability threshold as equivalent, local peaks such as those around 70% SOC for lithium iron phosphate (LFP) batteries can be highlighted.

[0086] In the high reliability region, SOCv can be estimated with high accuracy. Since SOCv is a parameter required to calculate SOCi, presented SOC, FCC, ΔSOCv, range coefficient, and range (see Equations 1 to 7 above), a high accuracy of SOCv also increases the accuracy of these parameters. Conversely, a low accuracy of SOCv also decreases the accuracy of these parameters.

[0087] For example, in an electric vehicle 3 equipped with a lithium iron phosphate (LFP) battery, the displayed driving range may be shorter in winter. In winter, the diffusion polarization of the lithium iron phosphate (LFP) battery increases and persists for a long time, resulting in an underestimated SOCv after driving. In other words, the OCV after driving becomes lower than the true OCV due to diffusion polarization, resulting in a larger ΔSOCv. This reduces the range coefficient and estimated driving range (see Equations 5-7 above). Furthermore, the accuracy of SOCv decreases in areas where the SOC-OCV curve is flat, so in areas where the SOC-OCV curve is flat, a large discrepancy may occur between the actual driving range and the estimated driving range.

[0088] In response to this, vehicle manufacturers advise that if you leave the vehicle in a low SOC range for a long time, then fully charge the vehicle and leave it for a specified period of time, you can reset the range to the correct value. In this way, if you change the SOC significantly between high-reliability ranges, you can reset various parameters correctly.

[0089] However, requiring users to perform operations that require such long charging and discharging times reduces user convenience. If users make an effort to normally rest the electric vehicle 3 in a range where the SOC error is small, the possibility of a large error occurring in the display of the cruising range can be significantly reduced.

[0090] Furthermore, in this embodiment, quantitative and specific battery management information (for example, SOC reliability, SOC error, charge / discharge recommendation) can be notified to the delivery company's operations manager. By encouraging charging when the SOC is low, unexpected battery shortages can be avoided. If the SOC is not low, driving to a low SOC range (discharging) can be encouraged. This improves the accuracy of operations management and contributes to the efficiency of delivery work.

[0091] The present disclosure has been described above based on the embodiments. The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and processing steps, and that such modifications are also within the scope of the present disclosure.

[0092] The SOC-OCV curve described above depends on temperature and SOH. Therefore, it is desirable to use an SOC-OCV curve corrected using a temperature map and an SOH map. The same applies to the polarization convergence curve.

[0093] In the above-described embodiment, the display control unit 313 displays the remaining battery amount pictogram on the display unit 38 in a darker color as the reliability of the presented SOC increases. In this regard, the size of the remaining battery amount pictogram may be increased as the reliability of the presented SOC increases. Furthermore, the remaining battery amount pictogram may be made to blink faster as the reliability of the presented SOC increases. Furthermore, the pattern of the remaining battery amount pictogram may be made denser as the reliability of the presented SOC increases. Furthermore, a mark indicating the reliability of the remaining battery amount (such as a good mark or a bad mark) may be displayed around the remaining battery amount display. Furthermore, the remaining battery amount reliability may be displayed as a numerical value around the remaining battery amount display.

[0094] 15A and 15B show another example of the remaining battery capacity displayed on the display unit 38 of the electric vehicle 3. This display example displays the SOC as a bar in increments of x%. The example shown in FIGS. 15A and 15B displays up to 10 bars in 10% SOC increments, with one bar increasing or decreasing for every 10% increase or decrease in SOC. In other words, the number of bars changes depending on the currently presented SOC, and the display color of each bar does not change for factors other than the currently presented SOC. The display color of each bar is determined by applying the high reliability threshold and low reliability threshold shown in FIG. 5 based on a representative value (e.g., average value) of the remaining battery capacity reliability in each SOC interval in increments of x%.

[0095] In the above-described embodiment, the electric vehicle 3 is assumed to be a four-wheeled electric vehicle that uses an inverter 35. In this regard, it may also be an electric motorcycle (electric scooter) or an electric bicycle. Furthermore, electric vehicles include not only full-scale electric vehicles but also low-speed electric vehicles such as golf carts and land cars used in shopping malls, entertainment facilities, etc.

[0096] Furthermore, the remaining battery charge notification according to the present disclosure can be applied to devices equipped with a battery pack 41 other than the electric vehicle 3. For example, it can be applied to electronic devices such as notebook PCs and home appliances such as vacuum cleaners. Even in these devices, parameters such as FCC may deviate with use, and it is beneficial for the user to naturally learn to understand the SOC error and reset it.

[0097] The embodiment may be specified by the following items.

[0098] [Item 1] A remaining battery level notification device (30) that notifies the user of the remaining battery level of a secondary battery (41) installed in a device (3), a reliability determination unit (312) that determines the reliability of an SOC indicating a remaining capacity of the secondary battery (41) to be notified to a user of the device (3) based on a slope of an SOC-OCV curve of the secondary battery (41) corresponding to the SOC; a notification control unit (313, 314) that controls the secondary battery (41) so that the remaining capacity is notified in a notification mode based on the determined reliability of the SOC; A remaining amount notification device (30) characterized by comprising:

[0099] This allows users to naturally learn how to understand and reset SOC errors during everyday operation.

[0100] [Item 2] 2. The remaining amount notifying device (30) according to item 1, wherein the reliability determination unit (312) evaluates the reliability of the SOC indicating the remaining amount to be notified to be higher as the slope on the SOC-OCV curve corresponding to the SOC indicating the remaining amount to be notified increases.

[0101] This allows the reliability of the SOC to be quantitatively understood.

[0102] [Item 3] The remaining battery level notification device (30) described in item 2 is characterized in that the notification control unit (313, 314) controls the remaining battery level of the secondary battery (41) to be displayed or output as audio in a more noticeable manner as the reliability of the determined SOC becomes higher.

[0103] This makes it possible to impress on the user areas where the SOC is highly reliable.

[0104] [Item 4] The remaining charge notification device (30) according to item 2 or 3, characterized in that the notification control unit (313, 314) controls the remaining charge of the secondary battery (41) to be displayed in a first color when a slope on the SOC-OCV curve corresponding to the SOC indicating the remaining charge to be notified is less than a low reliability threshold, to be displayed in a second color when a slope on the SOC-OCV curve is equal to or greater than a high reliability threshold, and to be displayed in a gradation color between the first color and the second color when a slope on the SOC-OCV curve is equal to or greater than the low reliability threshold and less than the high reliability threshold.

[0105] This narrows the range of OCV that expresses gradation, and prevents the change in display color from becoming minute in response to a small change in OCV.

[0106] [Item 5] The remaining charge notification device (30) according to item 2 or 3, characterized in that the notification control unit (313, 314) controls so that the remaining charge of the secondary battery (41) is displayed in a first color when a slope on the SOC-OCV curve corresponding to the SOC indicating the remaining charge to be notified is less than a threshold, and so that the remaining charge of the secondary battery (41) is displayed in a second color when the slope on the SOC-OCV curve is equal to or greater than the threshold.

[0107] This allows the user to be notified of the reliability of the SOC with a simple display.

[0108] [Item 6] 6. The remaining battery charge notification device (30) according to any one of items 1 to 5, characterized in that after charging / discharging of the device (3) is stopped, the SOC indicating the remaining battery charge to be notified is calculated as a weighted average of the SOC calculated by the current integration method and the SOC calculated by the OCV method, and the longer the elapsed time after charging / discharging of the device (3) is stopped, the higher the contribution of the SOC calculated by the OCV method.

[0109] This allows the user to understand the change in the reliability of the SOC after charging and discharging has stopped, thereby making the user aware of the need for parameter resetting.

[0110] [Item 7] A remaining charge notification method for notifying a remaining charge of a secondary battery (41) mounted in a device (3), comprising: determining the reliability of the SOC indicating the remaining capacity of the secondary battery (41) to be notified to a user of the device (3) based on the slope of the SOC-OCV curve of the secondary battery (41) corresponding to the SOC; controlling the secondary battery (41) so that the remaining capacity is notified in a notification mode based on the determined reliability of the SOC; A remaining amount notification method comprising:

[0111] This allows users to naturally learn how to understand and reset SOC errors during everyday operation.

[0112] [Item 8] A remaining battery notification program for notifying the user of the remaining battery capacity of a secondary battery (41) mounted in a device (3), determining the reliability of the SOC indicating the remaining capacity of the secondary battery (41) to be notified to the user of the device (3) based on the slope of the SOC-OCV curve of the secondary battery (41) corresponding to the SOC; a process of controlling the secondary battery (41) so that the remaining capacity is notified in a notification mode based on the determined reliability of the SOC; A remaining amount notification program that causes a computer to execute the following.

[0113] This allows users to naturally learn how to understand and reset SOC errors during everyday operation. [Explanation of symbols]

[0114] 1 Traffic management support system, 2 Traffic management terminal device, 3 Electric vehicle, 4 Charger, 5 Network, 6 Commercial power system, 11 Processing unit, 111 Traveling data acquisition unit, 112 Corrected SOC calculation unit, 113 Charge / discharge recommendation determination unit, 114 Battery management information generation unit, 12 Memory unit, 121 Traveling data storage unit, 122 Battery management information storage unit, 13 Communication unit, 30 Vehicle control unit, 310 Processing unit, 311 SOC acquisition unit, 312 Reliability determination unit, 313 Display control unit, 314 Voice synthesis unit, 320 Memory unit, 321 Traveling data storage unit, 31f Front wheels, 31r Rear wheels, 32f Front wheel axle, 32r Rear wheel axle, 33 Transmission, 34 Motor, 35 Inverter, 361 GPS sensor, 362 vehicle speed sensor, 37 wireless communication unit, 37a antenna, 38 display unit, 39 speaker, 40 power supply system, 41 battery pack, 42 ​​battery management unit, 43 voltage measurement unit, 44 temperature measurement unit, 45 current measurement unit, 46 battery control unit, E1-En cell, RY1-RY2 relay, T1-T2 temperature sensor, Rs shunt resistor.

Claims

1. A remaining battery capacity notification device that notifies the user of the remaining battery capacity of a secondary battery mounted on a device, a reliability determination unit that determines the reliability of a State Of Charge (SOC) indicating a remaining capacity of the secondary battery to be notified to a user of the device based on a slope of an SOC-Open Circuit Voltage (OCV) curve of the secondary battery corresponding to the SOC; a notification control unit that controls the secondary battery to be notified of the remaining charge in a notification manner based on the determined reliability of the SOC; Equipped with the reliability determination unit evaluates the reliability of the SOC indicating the remaining amount to be notified higher as the slope of the SOC-OCV curve corresponding to the SOC indicating the remaining amount to be notified increases, the notification control unit controls the remaining capacity notification device so that the remaining capacity of the secondary battery is displayed in a first color when a slope on the SOC-OCV curve corresponding to the SOC indicating the remaining capacity to be notified is less than a low reliability threshold, the remaining capacity of the secondary battery is displayed in a second color when the slope on the SOC-OCV curve is equal to or greater than a high reliability threshold, and the remaining capacity of the secondary battery is displayed in a gradation color between the first color and the second color when the slope on the SOC-OCV curve is equal to or greater than the low reliability threshold and less than the high reliability threshold.

2. A remaining battery level notification device that notifies the user of the remaining battery level of a secondary battery installed in a device, a reliability determination unit that determines the reliability of a State Of Charge (SOC) indicating a remaining capacity of the secondary battery to be notified to a user of the device based on a slope of an SOC-Open Circuit Voltage (OCV) curve of the secondary battery corresponding to the SOC; a notification control unit that controls the secondary battery to be notified of the remaining charge in a notification manner based on the determined reliability of the SOC; Equipped with the reliability determination unit evaluates the reliability of the SOC indicating the remaining amount to be notified higher as the slope of the SOC-OCV curve corresponding to the SOC indicating the remaining amount to be notified increases, The notification control unit controls the remaining capacity notification device so that the remaining capacity of the secondary battery is displayed in a first color when a slope on the SOC-OCV curve corresponding to the SOC indicating the remaining capacity to be notified is less than a threshold, and the remaining capacity of the secondary battery is displayed in a second color when the slope on the SOC-OCV curve is equal to or greater than the threshold.

3. 3. The remaining charge notification device according to claim 1, wherein the notification control unit controls the display or audio output of the remaining charge of the secondary battery to be more conspicuous the higher the reliability of the determined SOC.

4. 4. The remaining charge notification device according to claim 1, wherein, after charging or discharging of the device is stopped, the SOC indicating the remaining charge to be notified is calculated as a weighted average of the SOC calculated by the current integration method and the SOC calculated by the OCV method, and the longer the elapsed time since charging or discharging of the device was stopped, the higher the contribution of the SOC calculated by the OCV method.

5. A remaining charge notification method for notifying a remaining charge of a secondary battery mounted in a device, comprising: a first step of determining the reliability of a State Of Charge (SOC) indicating a remaining capacity of the secondary battery to be notified to a user of the device based on a slope of an SOC-Open Circuit Voltage (OCV) curve of the secondary battery corresponding to the SOC; a second step of controlling the secondary battery to notify the remaining charge in a notification manner based on the determined reliability of the SOC; and the first step evaluates the reliability of the SOC indicating the remaining amount to be notified higher as the slope of the SOC-OCV curve corresponding to the SOC indicating the remaining amount to be notified increases, the second step controls the remaining capacity of the secondary battery so that when a slope of the SOC-OCV curve corresponding to the SOC indicating the remaining capacity to be notified is less than a low reliability threshold, the remaining capacity of the secondary battery is displayed in a first color, when the slope of the SOC-OCV curve is equal to or greater than a high reliability threshold, the remaining capacity of the secondary battery is displayed in a second color, and when the slope of the SOC-OCV curve is equal to or greater than the low reliability threshold and less than the high reliability threshold, the remaining capacity of the secondary battery is displayed in a gradation color between the first color and the second color.

6. A remaining charge notification method for notifying a remaining charge of a secondary battery mounted in a device, comprising: a first step of determining the reliability of a State Of Charge (SOC) indicating a remaining capacity of the secondary battery to be notified to a user of the device based on a slope of an SOC-Open Circuit Voltage (OCV) curve of the secondary battery corresponding to the SOC; a second step of controlling the secondary battery to notify the remaining charge in a notification manner based on the determined reliability of the SOC; and the first step evaluates the reliability of the SOC indicating the remaining amount to be notified higher as the slope of the SOC-OCV curve corresponding to the SOC indicating the remaining amount to be notified increases, the second step controls the remaining capacity of the secondary battery to be displayed in a first color when a slope on the SOC-OCV curve corresponding to the SOC indicating the remaining capacity to be notified is less than a threshold, and to be displayed in a second color when the slope on the SOC-OCV curve is equal to or greater than the threshold.

7. A remaining battery capacity notification program for notifying a user of a remaining battery capacity of a secondary battery mounted in a device, a first process of determining the reliability of a State Of Charge (SOC) indicating a remaining capacity of the secondary battery to be notified to a user of the device based on a slope of an SOC-Open Circuit Voltage (OCV) curve of the secondary battery corresponding to the SOC; a second process of controlling the secondary battery to notify the remaining charge in a notification manner based on the determined reliability of the SOC; on the computer, the first process evaluates the reliability of the SOC indicating the remaining amount to be notified higher as the slope of the SOC-OCV curve corresponding to the SOC indicating the remaining amount to be notified increases, the second processing controls the remaining capacity of the secondary battery to be displayed in a first color when a slope on the SOC-OCV curve corresponding to the SOC indicating the remaining capacity to be notified is less than a low reliability threshold, to be displayed in a second color when the slope on the SOC-OCV curve is equal to or greater than a high reliability threshold, and to be displayed in a gradation color between the first color and the second color when the slope on the SOC-OCV curve is equal to or greater than the low reliability threshold and less than the high reliability threshold.

8. A remaining battery capacity notification program for notifying the remaining battery capacity of a secondary battery mounted on a device, comprising: a first process of determining the reliability of a State Of Charge (SOC) indicating a remaining capacity of the secondary battery to be notified to a user of the device based on a slope of an SOC-Open Circuit Voltage (OCV) curve of the secondary battery corresponding to the SOC; a second process of controlling the secondary battery to notify the remaining charge in a notification manner based on the determined reliability of the SOC; on the computer, the first process evaluates the reliability of the SOC indicating the remaining amount to be notified higher as the slope of the SOC-OCV curve corresponding to the SOC indicating the remaining amount to be notified increases, the second processing controls the remaining capacity of the secondary battery to be displayed in a first color when a slope on the SOC-OCV curve corresponding to the SOC indicating the remaining capacity to be notified is less than a threshold, and to be displayed in a second color when the slope on the SOC-OCV curve is equal to or greater than the threshold.

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