JP6449609B2 - Secondary battery charging rate estimation method and charging rate estimation device - Google Patents

Description

  The present invention relates to a charging rate estimation method and a charging rate estimation device for a secondary battery.

  Accurately grasping the remaining capacity of the secondary battery installed for driving prevents overcharge and overdischarge of the secondary battery and accurately conveys the charge rate of the secondary battery during driving to the driver. Is very important in terms.

  Conventionally, a method for estimating a charging rate using a relationship between an open-circuit voltage of a secondary battery and a charging rate is known (see, for example, Patent Document 1 and Patent Document 2).

JP 2011-215125 A

  However, the above conventional method has room for improvement in the estimation accuracy of the charging rate of the secondary battery.

  Then, an object of this invention is to improve the estimation precision of the charging rate of a secondary battery.

  In order to improve the estimation accuracy of the charging rate of the secondary battery, it is necessary to consider the difference in the open voltage between charging and discharging due to hysteresis in the change characteristic of the open circuit voltage with respect to the change in the charging rate of the secondary battery There is.

  Therefore, according to one aspect of the present invention, the secondary battery charge rate estimation method separately prepares related information indicating the relationship between the open-circuit voltage of the secondary battery and the charge rate after discharge and after charge, respectively. , Acquire the open-circuit voltage of the secondary battery, acquire the battery state indicating whether it is after charging or after discharging as the battery state before acquisition, and acquire based on the acquired battery state and the open-circuit voltage The charging rate of the secondary battery is estimated using related information corresponding to the battery state.

  According to the above method, the charging rate can be accurately estimated in consideration of the hysteresis characteristics of the secondary battery by differentiating the charging rate obtained from the open circuit voltage after discharging and after charging. Here, the related information may be, for example, a correction formula other than the map information.

  In the estimation of the charging rate, the related information is map information for obtaining the charging rate for each open-circuit voltage, and is map information separately prepared after discharging and after charging, and the acquired battery state is In the case of after discharging, the charging rate is estimated using the corresponding map information after discharging, and in the case of the acquired battery state after charging, the charging rate is estimated using the corresponding map information after charging. Also good.

  According to the above method, by referring to the map information and setting the charging rate prepared by measurement or calculation in advance according to the battery state, compared with the case where the charging rate is calculated using an arithmetic expression. The charge rate can be easily estimated.

  The secondary battery may be mounted on the electric vehicle as an energy source for driving the electric vehicle.

  According to the above method, since the SOC of the secondary battery mounted on the electric vehicle can be accurately estimated, the driver can monitor the remaining amount of the secondary battery with high accuracy.

  In the method for estimating the charging rate of the secondary battery, the open voltage is acquired before the electric vehicle starts to travel, the charging rate is estimated using the related information after discharging, and the open voltage is acquired after external charging. Thus, the charging rate may be estimated using the related information after charging.

  According to the above method, in the electric vehicle, it is possible to improve the estimation accuracy of the charging rate by making the related information different between before the start of traveling with high possibility after discharging and after external charging that is after charging. it can.

  In the method for estimating the charging rate of the secondary battery, when the electric vehicle is traveling, the charging rate estimated before the start of traveling is used as the initial charging rate, and the charging / discharging rate during traveling is integrated by integrating the current flowing in and out of the secondary battery. And the charging rate estimated immediately before the end of travel may be recorded at the end of travel of the electric vehicle. Here, “current flowing in and out of the secondary battery” means “discharge current and charging current of the secondary battery”. The current is integrated with the discharge current from the secondary battery being positive and the charge current to the secondary battery being negative.

  According to the above method, the charging rate can be accurately estimated even during traveling by using the charging rate estimated before traveling of the electric vehicle.

  In the method for estimating the charging rate of the secondary battery, when the electric vehicle starts to travel, if the elapsed time since the end of the previous travel is equal to or longer than a predetermined time after the travel, the open voltage is acquired before the travel starts. Then, using the related information after discharging, it is estimated as the charging rate before the start of traveling, and when the elapsed time since the end of traveling previously is less than the predetermined time after the traveling, it is stored at the end of traveling You may estimate as a charging rate before a driving | running | working start using a charging rate.

  According to the above method, the charging rate before the start of traveling of the electric vehicle can be accurately estimated by considering the stable state of the open-circuit voltage from the end of the previous travel to the start of traveling.

  In the method for estimating the charging rate of the secondary battery, after the external charging of the secondary battery is completed, the charging rate that is estimated immediately before the external charging is stored is stored. If the elapsed time is equal to or longer than a predetermined time after charging, an open circuit voltage is acquired before starting running, and the charge rate before starting running is estimated using the related information after charging. When the elapsed time after the end of charging is less than the predetermined time after the charging, the charging rate stored at the end of the external charging may be used to estimate the charging rate before the start of traveling.

  According to the above method, the charging rate before the start of traveling can be accurately estimated by considering the stable state of the open circuit voltage from the end of the previous external charging to the start of traveling.

  The secondary battery charge rate estimation apparatus according to another aspect of the present invention is a storage unit that individually stores related information indicating the relationship between the open-circuit voltage of the secondary battery and the charge rate after discharge and after charge, respectively. And an open-circuit voltage acquisition means for acquiring the open-circuit voltage of the secondary battery based on information given from the sensor, and a state for acquiring a battery state indicating whether the battery state before acquisition is after charging or after discharging Based on the acquisition means, the acquired battery state, and the open circuit voltage, the estimation means for estimating the charging rate of the secondary battery using the related information stored in the storage means, and since the charge / discharge has been completed previously A time measuring means for measuring an elapsed time until the secondary battery operation starts next, and the estimating means is a secondary time elapsed from the end of the secondary battery operation before the secondary battery operation is started. If it is longer than a certain time after battery operation Before starting the secondary battery operation, obtain the open-circuit voltage, and use the related information based on the battery state when the secondary battery operation ended before, and estimate the charge rate before starting the secondary battery operation. If the elapsed time since the end of the secondary battery operation is less than the predetermined time after the secondary battery operation, using the charge rate stored at the end of the previous secondary battery operation, Estimated as the charge rate, during secondary battery operation, the charge rate estimated before the start of secondary battery operation is taken as the initial charge rate, and charging during secondary battery operation is performed by integrating the current flowing in and out of the secondary battery. The rate is estimated, and when the secondary battery operation ends, the charging rate estimated immediately before the end of the secondary battery operation is stored in the storage means.

  The present invention has the above-described configuration and can improve the estimation accuracy of the SOC of the secondary battery.

  The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments with reference to the accompanying drawings.

It is a schematic block diagram of the secondary battery charging system containing the charging rate estimation apparatus of the secondary battery which concerns on 1st Embodiment. It is a block diagram which shows the structure of the charging rate estimation apparatus of FIG. It is an OCV-SOC map of the secondary battery corresponding after discharge and after charge. It is a flowchart which shows the charging rate estimation method of the secondary battery of 1st Embodiment. It is a block diagram which shows the structure of the outline of the secondary battery charging system containing the charging rate estimation apparatus of the secondary battery which concerns on 2nd Embodiment. It is a flowchart which shows the charging rate estimation method of the secondary battery of 2nd Embodiment. It is a timing chart of the charging rate estimation method of FIG. It is a flowchart which shows the charging rate estimation method of the secondary battery of 3rd Embodiment. It is a flowchart following the flowchart of FIG. It is a timing chart of the charging rate estimation method of FIG.7 and FIG.8. It is an OCV-SOC map of a typical secondary battery.

  Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a secondary battery charging system including a secondary battery charging rate estimation apparatus according to the first embodiment. As shown in FIG. 1, the secondary battery charging system 100 includes a secondary battery 1, a voltage sensor 2, a current sensor 3, and a battery management unit (hereinafter referred to as BMU) 4 including a charging rate estimation device 10. .

  The secondary battery 1 is configured, for example, by connecting a plurality of battery modules in a series or parallel manner or a combination thereof. The secondary battery 1 is, for example, a lithium ion battery.

  The voltage sensor 2 detects a battery voltage that is a terminal voltage of the secondary battery 1. The voltage sensor 2 is connected in parallel with the secondary battery 1 and configured to output the detected battery voltage to the BMU 4. A terminal voltage V measured in a state where no current flows through the secondary battery 1 corresponds to an open circuit voltage (OCV) of the secondary battery 1.

  The current sensor 3 detects a battery current that is a charge / discharge current of the secondary battery 1. The current sensor 3 is connected in series with the secondary battery 1 and configured to output the detected battery current to the BMU 4.

  The BMU 4 monitors the charge state and battery state of the secondary battery 1. The BMU 4 is configured by a microcontroller including a CPU and a memory, for example. In the BMU 4, the charging rate estimation device 10 calculates an estimated value of a charging rate (SOC: State of Charge) based on the battery voltage and the battery current detected by the voltage sensor 2 and the current sensor 3. In addition, a switch (not shown) is provided in the charge / discharge current path for the secondary battery 1, and the switch is turned on / off by the control of the BMU 4. Then, the voltage measured by the voltage sensor 2 in a state where the switch is turned off is used as the open circuit voltage OCV of the secondary battery 1.

  FIG. 2 is a block diagram illustrating a configuration of the charging rate estimation apparatus 10. As shown in FIG. 2, the charging rate estimation device 10 includes a memory 11 including a ROM, a RAM, and the like, a battery state acquisition unit 12, an SOC estimation unit 13, and a timer 14. Here, each part of the charging rate estimation apparatus 10 is a functional block realized by executing a charging rate estimation program in the BMU 4.

  The memory 11 stores information on the charge state and battery state of the secondary battery 1. In the present embodiment, the memory 11 individually stores related information indicating the relationship between the open circuit voltage OCV and the charge rate SOC of the secondary battery 1 after discharging and after charging.

  The battery state acquisition unit 12 acquires the open circuit voltage OCV of the secondary battery 1 based on the information given from the voltage sensor 2 and the current sensor 3, and after charging or after discharging as the battery state before acquisition. Get the battery status. The battery state acquisition unit 12 acquires, for example, the voltage across the secondary battery 1 in a non-opened state (a state in which a switch (not shown) is turned on) using the voltage sensor 2 in time series, If it decreases, it is determined that the battery is in a discharged state, and if the voltage across the terminal increases in time series, it is determined that the battery is in a charged state, or the current state is directly detected by the current sensor 3 to obtain the battery state. To do.

  The SOC estimation unit 13 charges the secondary battery 1 using related information stored in the memory 11 based on the battery state (after discharging or after charging) acquired by the battery state acquiring unit 12 and the open circuit voltage OCV. Estimate the rate SOC.

  The timer 14 is a time measuring unit that measures the elapsed time from the end of charge / discharge before the start of the operation of the secondary battery 1 next time. In the present embodiment, the timer 14 is configured to count the elapsed time by counting the clock pulses of the CPU configuring the BMU 4.

  Next, the charging rate estimation method of the secondary battery 1 of this embodiment will be described. The charging rate estimation method is performed by the operation of the charging rate estimation device 10.

  In this method for estimating the charging rate of the secondary battery, related information indicating the relationship between the open-circuit voltage OCV of the secondary battery 1 and the charging rate SOC is separately prepared separately after discharging and after charging. That is, related information indicating the relationship between the open circuit voltage OCV of the secondary battery 1 and the charge rate SOC in the battery state after discharge, and the open circuit voltage OCV and the charge rate SOC of the secondary battery 1 in the battery state after charge. And related information indicating the relationship of. This related information is, for example, map information (hereinafter referred to as an OCV-SOC map) obtained for the charging rate SOC for each open circuit voltage OCV. FIG. 3 is an example of the OCV-SOC map of the secondary battery 1 corresponding to after discharge and after charge. The solid line shows the SOC characteristics relative to the OCV after discharge. The alternate long and short dash line indicates the SOC characteristics with respect to the OCV after charging. As shown in FIG. 3, the secondary battery 1 shows hysteresis after discharging and after charging, and there is a difference between the characteristics of both. These maps are created based on results measured or calculated by experiments or simulations. In the present embodiment, these maps are stored in advance in the memory 11 of the charging rate estimation apparatus 10.

  FIG. 4 is a flowchart showing the charging rate estimation method of the present embodiment. As shown in FIG. 4, first, the battery state acquisition unit 12 acquires the open circuit voltage OCV of the secondary battery 1, and the battery state indicating whether it is after charging or after discharging as the battery state before acquisition. Obtain (step 1).

  Next, the SOC estimation unit 13 uses the OCV-SOC map corresponding to the acquired battery state based on the battery state acquired by the battery state acquisition unit 12 and the open circuit voltage OCV, and the charging rate of the secondary battery 1. The SOC is estimated (step 2). Specifically, when the battery state is after discharging, SOC estimating unit 13 estimates the charging rate SOC using the corresponding OCV-SOC map after discharging (step 3). On the other hand, when the battery state is after charging, SOC estimating unit 13 estimates the charging rate SOC using the corresponding OCV-SOC map after charging (step 4).

  According to the present embodiment, the charge rate SOC is accurately estimated in consideration of the hysteresis characteristics of the secondary battery 1 by making the charge rate SOC obtained from the open circuit voltage OCV different between after discharge and after charge. be able to.

  In addition, since the SOC prepared by measurement or calculation is set in advance according to the battery state with reference to the OCV-SOC map which is map information, charging is easier than in the case of calculating using an arithmetic expression. The rate SOC can be estimated.

(Second Embodiment)
Next, a second embodiment will be described. Below, the description of the configuration common to the first embodiment will be omitted, and the description will focus on the configuration that is different.

  The secondary battery 1 of the present embodiment is mounted on an electric vehicle and operates as an energy source for driving the electric vehicle. Examples of electric vehicles include plug-in hybrid vehicles (PHV / PHEV) and electric vehicles (EV). In the present embodiment, the secondary battery 1 is mounted on a saddle-ride type electric vehicle.

  FIG. 5 is a schematic configuration diagram of an in-vehicle secondary battery charging system including a charging rate estimation device for a secondary battery according to the present embodiment mounted on an electric vehicle. The electric vehicle is controlled by the vehicle control system 20 so as to have two operation modes: a traveling mode in which the electric vehicle is driven by the discharge of the secondary battery 1 and a charging mode in which the secondary battery 1 is charged in the traveling stopped state. Is done. For the driver of the electric vehicle, the remaining amount of the secondary battery 1 is important information for knowing the distance that can be traveled, and it is desired that the remaining battery can be monitored with high accuracy. Therefore, as shown in FIG. 5, in the secondary battery charging system 100A, the BMU 4 that monitors the charging state and the battery state of the secondary battery 1 includes a vehicle control system 20 that controls the entire vehicle and a network such as CAN. It is connected to be able to communicate through.

  Next, the charging rate estimation method of the secondary battery 1 of the present embodiment will be described with reference to the flowchart of FIG. The charging rate estimation method is performed by the operation of the charging rate estimation device 10. Here, it is assumed that the charge rate SOC is estimated when the electric vehicle operates, that is, in the travel mode in which the secondary battery 1 is discharged. The memory 11 stores the SOC at the end of the previous vehicle system in addition to the OCV-SOC map corresponding to after discharge and after charge. In addition, other information is temporarily or permanently stored in the memory 11 in conjunction with the operation of the vehicle system.

  As shown in FIG. 6, when the vehicle system is activated, the charging rate estimation apparatus 10 first acquires an elapsed time measured from the end of the previous vehicle system to the activation (step S21). The vehicle system is activated under the control of the vehicle control system 20 when, for example, a key on the vehicle body is turned on by the driver. The charging rate estimation apparatus 10 receives from the vehicle control system 20 that this vehicle system has been activated.

  Next, the charging rate estimation apparatus 10 determines whether or not the elapsed time after the end of the vehicle system is a predetermined time (step S22). The predetermined time is a time required for the open circuit voltage OCV after discharge to be stabilized after discharge, and is set based on, for example, a result measured or calculated by experiment or simulation. In the present embodiment, this predetermined time is stored in the memory 11 in advance.

  In step S22, when the elapsed time after the end of the vehicle system is equal to or longer than the predetermined period, the charging rate estimation apparatus 10 acquires the open circuit voltage OCV, and the battery state before acquisition is a battery state indicating after discharging. And the initial charge rate SOC is estimated with reference to the OCV-SOC map after discharge (step S23). On the other hand, when the elapsed time after the end of the vehicle system is less than the predetermined period, the charging rate estimation apparatus 10 reads the previous charging rate SOC stored in the memory 11 and sets it as the initial charging rate SOC. Set (step S24).

  After the estimation or setting of the initial charging rate SOC, the charging rate estimation device 10 starts sequential integration of charge / discharge current (step S25).

Next, the charging rate estimation device 10 sequentially updates the charging rate SOC based on the following equation (1) using the current integrated value (step S26).
SOC change amount [%] = current integrated value [Ah] / {(SOH [%] / 100) × rated capacity [Ah]} × 100 (1)

SOH (State of Health) in the formula (1) indicates the degree of deterioration of the battery capacity of the secondary battery 1. The calculation of SOH will be described in detail in the third embodiment.

  The charging rate estimation apparatus 10 performs the update of the SOC in step 26 until the vehicle system stops (step S27). When the vehicle system stops, the charging rate estimation device 10 stores the charging rate SOC at that time as the final SOC in the memory 11 of the BMU (step S28), and ends the charging rate estimation operation. The vehicle system is stopped by the control of the vehicle control system 20 when, for example, the key of the vehicle main body is turned off by the driver. The charging rate estimation apparatus 10 receives from the vehicle control system 20 that this vehicle system has been stopped.

  An example of the above operation will be described with reference to the timing chart of FIG. The upper graph in FIG. 7 shows the estimated SOC value in time series. The middle graph shows the open circuit voltage OCV voltage in time series. The lower graph shows charging / discharging currents entering and exiting the secondary battery 1 in time series.

  As shown in FIG. 7, the vehicle system is activated at time t1. At this time, the electric vehicle is in a stopped state. At this time, the initial value of SOC estimation is set from the open circuit voltage OCV. That is, before starting the running of the electric vehicle, the open circuit voltage OCV is acquired, and the charge rate SOC is estimated using the OCV-SOC map after discharge. Specifically, at the start of traveling of the electric vehicle, when the elapsed time since the end of traveling is equal to or longer than a predetermined time after traveling, the open circuit voltage OCV is acquired before starting traveling, and the OCV after discharging Using the SOC map, estimate the charging rate SOC before the start of traveling. On the other hand, when the elapsed time since the end of traveling is less than a predetermined time after traveling, the charging rate SOC stored at the end of traveling is used to estimate the charging rate SOC before the start of traveling.

  At time t2, the electric vehicle starts running. During operation at a low load (after time t2), the estimated SOC value and the open circuit voltage OCV gradually decrease. During this time, the current is sequentially accumulated and the SOC is updated.

  At time t3, the load on the electric vehicle increases. During operation with the increased load (after time t3), the estimated SOC value and the open circuit voltage OCV drop rapidly. Also during this time, the current increased with the load is sequentially accumulated and the SOC is updated.

  As described above, during the traveling of the electric vehicle, the charging rate SOC estimated before starting the traveling is set as the initial charging rate SOC, and the charging rate SOC during the traveling is estimated by integrating the current flowing in and out of the secondary battery 1. .

  At time t4, the electric vehicle ends traveling. At the end of traveling of the electric vehicle, the charging rate SOC estimated immediately before the end of traveling is recorded. After traveling (after time t4), the SOC is not updated and becomes a constant value, and the current becomes zero.

  Therefore, according to the present embodiment, when the electric vehicle starts to travel, if the elapsed time since the end of traveling is equal to or longer than the predetermined time after traveling, the open circuit voltage OCV is acquired before starting traveling, Using the OCV-SOC map after discharge, the charge rate SOC before the start of travel is estimated. If the elapsed time since the end of travel is less than a predetermined time after travel, the charge stored at the end of travel is stored. By using the rate SOC to estimate the charging rate before the start of travel, the stable state of the open circuit voltage OCV from the end of the previous travel to the start of travel can be taken into account, and the charge rate before the start of travel of the electric vehicle Can be estimated with high accuracy.

  While the electric vehicle is traveling, the charging rate SOC estimated before the start of traveling is set as the initial charging rate SOC, and the charging rate SOC during traveling is estimated by integrating the current flowing in and out of the secondary battery 1 to By recording the charging rate SOC estimated immediately before the end of traveling at the end of traveling of the vehicle, the charging rate SOC can be accurately estimated even during traveling by using the charging rate SOC estimated before traveling of the electric vehicle.

(Third embodiment)
Next, a third embodiment will be described. Similarly to the second embodiment, the secondary battery 1 of the present embodiment is also mounted on a saddle-ride type electric vehicle and operates as an energy source for driving the electric vehicle. In the following, description of the configuration common to the second embodiment will be omitted, and the description will focus on the configuration that is different.

  Next, the charging rate estimation method of the secondary battery 1 of the present embodiment will be described with reference to the flowcharts of FIGS. 8 and 9 and the timing chart of FIG. The upper graph in FIG. 10 shows the estimated SOC value and the open circuit voltage OCV voltage in time series. The lower graph shows charging / discharging currents entering and exiting the secondary battery 1 in time series.

  Here, it is assumed that the charging rate SOC is estimated in the charging mode in which the electric vehicle is charged in the traveling stop state. SOH estimation will also be described. In addition, the OCV-SOC map corresponding to after discharge and after charge is stored in the memory 11 in advance. In addition, the memory 11 temporarily or permanently stores the SOC and other information at the end of the previous external charging in conjunction with the operation of the charging system.

  In the charging mode of the present embodiment, the secondary battery 1 reaches a predetermined voltage by constant current charging by constant current / constant voltage charging, and then reaches a charging completion state by constant voltage charging. Charging of the secondary battery 1 is controlled by the vehicle control system 20. This will be specifically described below.

  First, the charging mode is started. In the present embodiment, the charging mode is started, for example, from time t2 after the traveling of the electric vehicle is completed.

  After starting the charging mode at time t2, a predetermined amount of constant current charging (hereinafter also referred to as CC charging) is performed, and CC charging is interrupted at time t3 (step S31). At this time, the charge rate SOC at the time of CC charge interruption is stored in the memory 11. Here, the specified amount of CC charging means, for example, that CC charging is performed until the SOC value is 30% or more. The reason is as follows. FIG. 11 is a graph showing an example of an OCV-SOC map of a typical secondary battery. As shown in FIG. 11, in the region where the charging rate SOC is 30% or less, the open circuit voltage OCV drops rapidly as the charging rate SOC decreases, so that a measurement error at the time of creating the OCV-SOC map is likely to occur. The SOC estimation accuracy of the OCV-SOC map is lowered. Therefore, after charging the secondary battery 1 with a specified amount of CC, by avoiding the start of SOC estimation from the region where the accuracy of the OSV-SOC map is reduced, the CC charging is interrupted, thereby depending on the charge / discharge history. The influence of hysteresis can be reduced. For this reason, when the SOC is 30% or less, a configuration may be adopted in which the driver is alerted by turning on a charge lamp provided in the electric vehicle.

  Next, it is determined whether or not the elapsed time after the interruption of CC charging is a predetermined time (step S32). The predetermined time is a time required for the open circuit voltage OCV after the CC charging interruption to be stabilized after the charging, and is set based on, for example, a result measured or calculated by an experiment or a simulation. In the present embodiment, this predetermined time is stored in the memory 11 in advance.

  In step 32, when the elapsed time after the interruption of CC charging reaches a predetermined period, the charging rate estimation apparatus 10 acquires the open circuit voltage OCV (1) at time t4, and the battery state before acquisition is after the charging. The battery state shown is acquired, and the initial charge rate SOC (1) is estimated with reference to the OCV-SOC map after charging (step S33). On the other hand, the charging rate estimation device 10 reads the charging rate SOC at the time of the previous CC charging interruption stored in the memory 11 and sets it as the initial charging rate SOC while the elapsed time after the interruption of CC charging does not reach the predetermined period. (Step S34). When the elapsed time after the CC charging interruption reaches a predetermined period, the charging rate estimation apparatus 10 proceeds to step S32 and estimates SOC (1).

  Next, at time t4, CC charging is resumed, and the charging rate estimation apparatus 10 integrates the charging current (step S35). CC charging is continued until a predetermined voltage is reached. After reaching a predetermined voltage by CC charging at time t5, the process proceeds from CC charging to CV charging (step S36). Charging is interrupted at the time of transition to CV charging, and the charging rate estimation apparatus 10 determines the charging amount from the current integrated value. At this time, the charge rate SOC at the time of CV charge interruption is stored in the memory 11. When the charger is stopped halfway, the charging rate estimation device 10 stops the SOH estimation and sets the previous value as the latest SOH. This is because a sufficient SOC difference cannot be secured and the estimation accuracy may be reduced.

  Next, the charging rate estimation apparatus 10 determines whether or not the elapsed time after interruption of CV charging is a predetermined time (step S37). This predetermined time is a time required for the open circuit voltage OCV after interruption of CV charging to be stabilized after charging, and is set based on, for example, a result measured or calculated by experiment or simulation. In the present embodiment, this predetermined time is stored in the memory 11 in advance.

  In step S37, when the elapsed time after interruption of CV charging reaches a predetermined period, the charging rate estimation apparatus 10 acquires the open circuit voltage OCV (2) at time t6, and the battery state before acquisition is after charging. The initial state of charge SOC (2) is estimated with reference to the OCV-SOC map after charging (step S38). On the other hand, the charging rate estimation device 10 reads the charging rate SOC at the time of the previous CV charging interruption stored in the memory 11 and sets it as the initial charging rate SOC while the elapsed time after interruption of CV charging does not reach the predetermined period. (Step S39). When the elapsed time after interruption of CV charging reaches a predetermined period, the charging rate estimation apparatus 10 proceeds to step S38 and estimates SOC (2).

And the charging rate estimation apparatus 10 performs SOH estimation (1) (step S40). SOH (1) is estimated by the following equation (2) from SOC (1), SOC (2), and the amount of charge of CC. When the vehicle shifts to the traveling mode on the way, the charging rate estimation device 10 stops the SOH estimation and sets the previous value as the latest SOH.
SOH (1) [%] = CC charge [Ah] / {(SOC (2) [%] / 100) − (SOC (1) [%] / 100)} × rated capacity [Ah]} × 100 · (2)

  After the SOH estimation (1), CV charging is resumed, and the charging current is additionally integrated (step S41 in FIG. 9).

  Next, when the CV charge is completed at time t7, the charge amount is determined from the current integrated value (step S42). Similarly, when the charger is stopped halfway, SOH estimation is stopped and the previous value is set as the latest SOH.

  Next, the charging rate estimation apparatus 10 determines whether or not the elapsed time after the end of CV charging is a predetermined time (step S43). This predetermined time is the time required for the open circuit voltage OCV after the end of CV charging to stabilize after charging, and is set based on, for example, a result measured or calculated by experiment or simulation. In the present embodiment, this predetermined time is stored in the memory 11 in advance.

  In step S43, when the elapsed time after the end of CV charging reaches a predetermined period, the charging rate estimation apparatus 10 acquires the open circuit voltage OCV (3) at time t8, and the battery state before acquisition is after charging. It determines with it being a battery state to show, and charging rate SOC (3) is estimated with reference to the OCV-SOC map after charge (step S44). On the other hand, the charging rate estimation device 10 reads the charging rate SOC at the end of the previous CV charging stored in the memory 11 and sets it as the charging rate SOC while the elapsed time after interruption of CV charging does not reach the predetermined period. (Step S45). When the elapsed time after the end of CV charging reaches a predetermined period, the charging rate estimation apparatus 10 proceeds to step S44 and estimates SOC (3). When the vehicle shifts to the traveling mode on the way, the charging rate estimation apparatus 10 sets the SOH estimated in step S40 as the latest SOH.

And the charging rate estimation apparatus 10 performs SOH estimation (2) (step S46). SOH (2) is re-estimated by the following equation (3) from SOC (1), SOC (3), and the total charge.
SOH (2) [%] = total charge [Ah] / {(SOC (3) [%] / 100) − (SOC (1) [%] / 100)} × rated capacity [Ah]} × 100 · (3)

  The charging rate estimation apparatus 10 stores the latest SOC and SOH in the memory 11 when the charging system ends (power off).

In the present embodiment, the remaining amount estimation of the secondary battery 1 is calculated by the following equation (4) using the average values of the estimated SOC and estimated SOH of all the cells in the pack.
Battery remaining amount [Ah] = (average SOC [%] / 100) × (average SOH [%] / 100) × rated capacity [Ah] (4)

  Therefore, according to the present embodiment, after the external charging of the secondary battery 1 is finished, the charging rate SOC estimated immediately before the end of the external charging is stored, and the elapsed time since the end of the external charging before the start of traveling of the electric vehicle. If the time is equal to or longer than the predetermined time after charging, an open-circuit voltage is acquired before starting running, and the charging rate before starting running is estimated using the OCV-SOC map after charging. If the elapsed time from the end is less than a predetermined time after charging, the charging rate SOC stored at the end of external charging is used to estimate the charging rate before the start of travel, so that the previous external charging ends. The stable state of the open circuit voltage before the start of traveling can be taken into account, and the charging rate before the start of traveling can be accurately estimated.

  In the above embodiment, the open circuit voltage OCV is acquired before the electric vehicle starts to travel, and the charge rate SOC is estimated using the OCV-SOC map after discharge. By obtaining the OCV and using the OCV-SOC map after charging to estimate the charging rate SOC, in the electric vehicle, before the start of traveling with high possibility after discharging, and after external charging that is after charging Thus, since the map information to be referred to is different, the estimation accuracy of the charging rate SOC can be improved.

  In the above embodiment, since the secondary battery 1 is mounted on the electric vehicle as an energy source for driving the electric vehicle, the SOC of the secondary battery 1 can be accurately estimated, and the driver can The remaining battery level can be monitored with high accuracy.

  Moreover, in the said embodiment, since the secondary battery 1 is mounted in the saddle-ride type electric vehicle, the capacity | capacitance of the secondary battery 1 is smaller than the case where it mounts in large vehicles, such as a motor vehicle, and charging / discharging is carried out. It is performed more frequently and the deterioration is severe. For this reason, this invention is used more suitably.

  In the above embodiment, the secondary battery is CC-charged so that charging is interrupted, and the OCV-SOC map corresponding to the open circuit voltage OCV after charging is used when the CC charging is interrupted. Then, the SOC (1) of the secondary battery 1 is estimated, and after the CC charging is completed, the OCV-SOC map corresponding to the open circuit voltage OCV after the charging is used and applied. 2) is estimated, and SOH (1) of the secondary battery is estimated based on SOC (1) and SOC (2) and the integrated value of the charging current from the interruption of CC charging to the end of CC flow charging. The estimated SOH is set as the estimated SOH, and then the secondary battery 1 is CV charged to a predetermined SOC.

  In general, when SOH is estimated only in a fully charged state, SOH cannot be estimated when charging is stopped halfway. According to the above configuration, the SOC and SOH can be estimated while reducing the influence of hysteresis during the charging of the secondary battery.

  Furthermore, after the constant voltage charging is completed, the SOC (3) of the secondary battery is estimated by applying the OCV-SOC map corresponding to the open circuit voltage after charging, and the SOC (1) and SOC are applied. The SOH (2) of the secondary battery 1 is estimated based on (3) and the integrated value of the charging current from the interruption of charging to the end of CV charging, and the estimated SOH is updated to the estimated SOH (2).

  According to the above configuration, SOC (3) can be estimated while reducing the influence of hysteresis after the secondary battery is charged. Further, since the difference between the SOC (3) after charging and the SOC (1) at the time of charging interruption can be made large, the SOH estimation (2) with higher accuracy than the SOH estimation (1) during the charging can be performed.

  Further, in the present embodiment, the charging is interrupted after the secondary battery is charged with a predetermined amount of electricity (charge) CC, so that the influence of hysteresis due to the charge / discharge history can be reduced.

  In addition, in the said 1st Embodiment and 2nd Embodiment, although the secondary battery 1 was mounted in the electric vehicle, you may mount in the other apparatus which operate | moves electrically. In that case, the same effect can be obtained by performing the portions described as running, running start and running end for the electric vehicle instead of the secondary battery operation start and the secondary battery operation end during the secondary battery operation, respectively. Can be obtained.

  In the above-described embodiment, the related information indicating the relationship between the open circuit voltage OCV and the charging rate SOC of the secondary battery 1 is the OCV-SOC map. However, for example, a correction formula other than the map information may be used.

  In the above embodiment, the charging estimation method for the secondary battery is performed by the operation of the charging rate estimation device 10 for the secondary battery 1, but may be performed by a person.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. Details of both the structure and / or function can be substantially changed without departing from the spirit of the invention.

  The present invention is useful for a secondary battery mounted on an electric vehicle.

1 Secondary battery 2 Voltage sensor 3 Current sensor 4 BMU
DESCRIPTION OF SYMBOLS 10 Charging rate estimation apparatus 11 Memory 12 Battery state acquisition part 13 SOC estimation part 14 Timer 20 Vehicle control system 100,100A Secondary battery charging system

Claims (5)

Relevant information indicating the relationship between the open-circuit voltage and the charging rate of the secondary battery mounted on the electric vehicle as an energy source for driving the electric vehicle is separately prepared after discharging and charging,
Acquires the open battery voltage of the secondary battery and the battery state indicating whether it is after external charging or after discharging discharged after external charging as the battery state before acquiring the open voltage of the secondary battery And
Based on the acquired battery state and an open circuit voltage, the charge rate of the secondary battery is estimated using the related information corresponding to the acquired battery state ,
In starting the running of the electric vehicle,
If the elapsed time from the end of the previous run is more than a predetermined time after running,
Before starting running, get the open circuit voltage, using the related information after discharging, estimate as the charging rate before starting running,
If the elapsed time from the end of the previous travel is less than a predetermined time after the travel,
A method for estimating a charging rate of a secondary battery, wherein the charging rate stored at the end of traveling is used to estimate the charging rate before starting traveling . In the estimation of the charging rate,
The related information is map information for obtaining a charging rate for each open-circuit voltage, and is map information separately prepared after external charging and after discharging discharged after external charging,
If the obtained battery state is after discharge, the charge rate is estimated using the map information corresponding after discharge,
The method for estimating a charging rate of a secondary battery according to claim 1, wherein, when the acquired battery state is after external charging, the charging rate is estimated using the map information corresponding to after external charging. On the basis of the detected value of the voltage sensor or current sensor in the external charging time, acquiring the battery state, charge rate estimating method for a secondary battery according to claim 1 or 2. Relevant information indicating the relationship between the open-circuit voltage and the charging rate of the secondary battery mounted on the electric vehicle as an energy source for driving the electric vehicle is separately prepared after discharging and charging,
Acquire the open circuit voltage of the secondary battery, and acquire the battery state indicating whether it is after charging or after discharging as the battery state before acquisition,
A charge rate estimation method for estimating a charge rate of a secondary battery using the related information corresponding to the acquired battery state based on the acquired battery state and an open circuit voltage,
After the external charging of the secondary battery is finished, the charging rate estimated immediately before the end of the external charging is stored,
In starting the running of the electric vehicle,
If the time elapsed since the end of external charging is equal to or longer than the specified time after charging,
Before starting running, obtain the open circuit voltage, use the related information after charging, estimate as the charging rate before starting running,
If the elapsed time since the end of external charging is less than the predetermined time after the charging, the charging rate stored before the end of external charging is used to estimate the charging rate before the start of travel. Charge rate estimation method. Storage means for individually storing related information indicating the relationship between the open-circuit voltage of the secondary battery and the charging rate after discharging and after charging,
An open-circuit voltage acquisition means for acquiring an open-circuit voltage of the secondary battery based on information given from the sensor;
State acquisition means for acquiring a battery state indicating whether it is after charging or after discharging as a battery state before acquisition;
Estimating means for estimating a charging rate of the secondary battery using the related information stored in the storage means based on the obtained battery state and the open circuit voltage;
A time measuring means for measuring the elapsed time from the end of charge / discharge before the start of the secondary battery operation,
When the elapsed time since the end of the secondary battery operation is equal to or longer than the predetermined time after the secondary battery operation, the estimation means starts the secondary battery operation before starting the secondary battery operation. And using the related information based on the battery state at the time when the secondary battery operation ended before, estimating the charge rate before starting the secondary battery operation, If the elapsed time is less than a predetermined time after the secondary battery operation, using the charge rate stored at the end of the previous secondary battery operation, estimated as the charge rate before starting the secondary battery operation,
During secondary battery operation, the charge rate estimated before the start of secondary battery operation is used as the initial charge rate, and the charge rate during secondary battery operation is estimated by integrating the current that enters and exits the secondary battery. A secondary battery charge rate estimation device that stores in the storage means the charge rate estimated immediately before the secondary battery operation ends when the secondary battery operation ends.

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