JP6606153B2 - Battery state estimation method and battery state estimation device - Google Patents

Description

  The present invention relates to a battery state estimation method and a battery state estimation device. More specifically, the present invention relates to a battery state estimation method and a battery state estimation device that acquire a correlation characteristic between an open-circuit voltage of a battery that changes due to the deterioration and a charging rate.

  The input / output performance of a secondary battery mounted on a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), a battery-powered electric vehicle (BEV), etc., is secondary such as its charging rate, battery capacity, and resistance. Varies depending on the internal state of the battery. For this reason, in order to use the secondary battery in a mode suitable for its input / output performance, such an internal state is particularly designated as a charging rate (hereinafter, abbreviated as “SOC (State Of Charge)”). Need to be estimated with high accuracy. Further, there is a correlation characteristic between the charging rate of the secondary battery and its open-circuit voltage (hereinafter, the abbreviation “OCV (Open Circuit Voltage)” may be used). Therefore, when estimating the SOC of the secondary battery in the traveling vehicle, the OCV of the secondary battery is estimated, and the estimated OCV is input to the SOC-OCV map in which the correlation characteristics are mapped, In many cases, the SOC is estimated.

  By the way, the correlation characteristic between SOC and OCV in a secondary battery generally varies depending not only on the type of battery but also on its deterioration state. Therefore, in Patent Document 1, a plurality of SOC-OCV maps as described above are created in advance, and an appropriate one according to the deterioration state of the secondary battery is selected from the plurality of SOC-OCV maps. A technique for estimating a charging rate of a secondary battery using a selected SOC-OCV map is shown.

JP 2016-23970 A

  However, according to the technique of Patent Document 1, in order to improve the estimation accuracy, it is necessary to create as many SOC-OCV maps in advance as that amount, and therefore enormous work time is required. When a plurality of SOC-OCV maps are used, it is necessary to use a large memory for storing these maps.

  An object of the present invention is to provide a battery state estimation method and a battery state estimation device that can acquire a correlation characteristic between SOC and OCV with high accuracy without creating a plurality of maps in advance.

  (1) The battery state estimation method of the present invention is a method for acquiring a correlation characteristic between an open-ended voltage and a charging rate of a battery (for example, a high voltage battery 2 described later) that changes due to deterioration, and the battery is supplied with a power supply ( For example, a first charging step (for example, step S4 in FIG. 6 to be described later) in which an external power source 95 described later is connected and the battery is charged until it reaches a fully charged state, and the battery is charged from the fully charged state to the lower limit charge. A discharge step (for example, step S6 in FIG. 6 to be described later) for calculating the battery capacity of the battery by discharging until reaching a state and integrating the discharge current during that time, and the battery is fully charged from the lower limit charge state The battery is recharged until it reaches a state, and charging is stopped for a predetermined time each time a plurality of defined measurement points are reached between the lower limit charge state and the full charge state, and after the predetermined time has passed, Measured at the second charging step (for example, steps S9 to S12 in FIG. 6 to be described later), the charging rate at each measurement point, and each measurement point to measure the open end voltage and resume charging after the measurement. A correlation characteristic acquisition step (for example, step S13 in FIG. 6 described later) for acquiring the correlation characteristic of the battery based on the open-circuit voltage.

  (2) In this case, the battery is mounted on a moving body (for example, a vehicle V described later), and the power source is an external power source (for example, an external power source 95 described later) provided outside the moving body. The first charging step, the discharging step, the second charging step, and the correlation characteristic acquisition step are preferably executed in response to the connection of the external power source while the moving body is stopped.

  (3) In this case, the mobile unit is charged externally with the power supplied from the external power source, and external power supply is discharged from the battery to an external supply target provided outside the mobile unit. It is preferable that the bidirectional charger is provided, and the charging in the first charging step and the second charging step and the discharging in the discharging step are performed using the bidirectional charger.

  (4) In this case, the moving body is equipped with acquisition possibility determination means operable by a user to select whether or not the correlation characteristic can be newly acquired, and the first charging step and the discharging step The second charging step and the correlation characteristic acquisition step are preferably executed only when it is selected that the correlation characteristic can be acquired via the necessity determination unit.

  (5) In this case, the first charging step, the discharging step, the second charging step, and the correlation characteristic acquisition step are at least a predetermined usage period from the use start time of the battery or the previous correlation characteristic acquisition time. It is preferable to be executed on the condition that elapses.

  (6) A battery state estimation device (for example, a charging system S described later) of the present invention acquires a correlation characteristic between an open-ended voltage and a charging rate of a battery (for example, a high voltage battery 2 described later) that changes due to deterioration. A voltage detection means for detecting the voltage of the battery (for example, a battery voltage sensor 62 described later), a current detection means for detecting the current of the battery (for example, a battery current sensor 61 described later), and a power source. Charging / discharging means (for example, supplying power from the battery to a discharge target and discharging the battery until it reaches a lower limit charging state after supplying power to the battery and charging the battery until the battery is fully charged (for example, The discharge current detected by the current detecting means is integrated between the charging ECU 56), which will be described later, and the charging / discharging means until the battery changes from the fully charged state to the lower limit charging state. And a battery capacity calculating means for calculating the battery capacity of the battery (for example, a battery ECU 60 and a battery capacity calculating unit 672, which will be described later), and supplying power from the power source to the battery. Intermittent charging until charging state is reached and charging is temporarily stopped for a predetermined time or more each time a plurality of defined measurement points are reached between the lower limit charging state and the full charging state. An open-ended voltage for acquiring an open-ended voltage of the battery by the voltage detecting means while charging is temporarily stopped by the charging means (for example, a charge ECU 56 described later) and the intermittent charging means at each measurement point. Acquisition means (for example, an open end voltage acquisition unit 673 of the battery ECU 60 to be described later), a charge rate at each measurement point, and the open end voltage acquisition A correlation characteristic acquisition unit (for example, a correlation characteristic acquisition unit 674 described later) that acquires the correlation characteristic of the battery based on the open-circuit voltage measured at each measurement point by the stage; To do.

  (1) In the battery state estimation method of the present invention, first, the battery is charged until it reaches a fully charged state (first charging step), and further, the battery is discharged from the fully charged state to the lower limit charged state. The battery capacity of the battery is calculated by integrating the discharge current (discharge process). Therefore, according to the present invention, the battery capacity of the battery can be accurately estimated. Thereafter, in the present invention, the battery is charged again from the lower limit charge state to the full charge state, and a plurality of measurement points are defined between the lower limit charge state and the full charge state, and each time the measurement point is reached during charging. The charging is stopped for a predetermined time or more, the open-circuit voltage of the battery is measured after elapse of the predetermined time or more, and the charging is restarted after the measurement (second charging step). Therefore, according to this invention, the fall of the measurement precision of the open end voltage in each measurement point can be suppressed. Further, in the present invention, by previously executing the discharging step and estimating the battery capacity, the measurement point can be defined with reference to the battery capacity, and as a result, it is possible to suppress a decrease in the estimation accuracy of the charging rate at each measurement point. . Moreover, in this invention, the correlation characteristic between the open circuit voltage of a battery and a charge rate is acquired based on the charge rate and open circuit voltage in each measurement point obtained as mentioned above. As described above, according to the present invention, it is possible to accurately acquire a correlation characteristic that changes due to deterioration. Moreover, in the battery state estimation method of the present invention, since the estimation of the correlation characteristics can be completed in a state where the battery is fully charged, convenience is good.

  (2) As described above, in the battery state estimation method of the present invention, it is necessary to perform charging, discharging, and recharging in order to obtain the correlation characteristics, and thus it takes time. Therefore, in the battery state estimation method of the present invention, the first charging step, the discharging step, the second charging step, and the correlation characteristic obtaining step are performed while the moving body is stopped, that is, a period in which the user does not use the moving body. To obtain the correlation characteristics. Thereby, it is possible to prevent the convenience for the user from being impaired.

  (3) In the battery state estimation method of the present invention, charging in the first charging step and the second charging step and discharging in the discharging step are performed using a bidirectional charger. Thereby, in the discharging step, the electric power discharged from the battery until it reaches the lower limit charging state from the fully charged state can be effectively used by an electric power network or an electric load connected to the bidirectional charger.

  (4) Since the correlation characteristics of the battery gradually change as the deterioration progresses, it is not necessary to update frequently. Further, the battery state estimation method of the present invention takes time because it is necessary to perform discharging and recharging. Therefore, in the battery state estimation method of the present invention, the first charging step is performed only when it is selected that a new acquisition of the correlation characteristic is possible from the user via the acquisition propriety determination unit mounted on the mobile body. The discharge process, the second charging process, and the correlation characteristic acquisition process are executed to acquire the correlation characteristic of the battery. Thereby, it is possible to prevent a correlation property from being newly acquired against the user's intention and to impair convenience.

  (5) As described above, the correlation characteristics of the battery gradually change as the deterioration progresses, so that it is not necessary to update frequently. Therefore, in the battery state estimation method of the present invention, the first charging step, the discharging step, the second charging step, on the condition that at least a predetermined usage period has elapsed from the start of use of the battery or the acquisition time of the previous correlation characteristic, And a correlation characteristic acquisition process is performed. As a result, it is possible to prevent the correlation characteristics from being acquired more frequently than necessary, and the convenience for the user from being lost.

  (6) According to the battery state estimation device of the present invention, the same effect as the above-described battery state estimation method of (1) can be obtained.

It is a figure which shows the structure of a charging system provided with the battery state estimation apparatus which concerns on one Embodiment of this invention. It is a functional block diagram which shows the structure of the part which concerns on estimation of SOC of a high voltage battery among the control modules implement | achieved in battery ECU. It is a figure which shows the structure of the equivalent circuit model of the high voltage battery used when estimating OCV of a high voltage battery. It is a figure which shows an example of a SOC-OCV map. It is a figure for demonstrating the procedure of an intermittent charge process. It is a flowchart which shows the specific procedure of the battery state estimation method of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a charging system S including a battery state estimation device according to the present embodiment. The charging system S includes a high-voltage battery 2 and an electric vehicle V (hereinafter simply referred to as “vehicle V”) including an inlet 51 connected to the high-voltage battery 2, and a connector 91 connected to the inlet 51. 2 and an external charger 9 capable of transmitting and receiving electric power.

  The external charger 9 is installed, for example, in the home of the user of the vehicle V. The external charger 9 includes a connector 91 that can be connected to the inlet 51, an external power source 95, a first power supply line 92 that connects the external power source 95 and the connector 91, an electrical load 96 installed in a house, and an electrical load. 96 and a second power supply line 93 that connects the first power supply line 92.

  The external power source 95 is an AC power source, specifically, an AC power source for home use that outputs, for example, AC 200V, but the present invention is not limited to this. The electrical load 96 is a specific electrical product (for example, lighting or a water heater) provided in the house, but the present invention is not limited to this. The electric load 96 may be an electric discharge target of the high-voltage battery 2 of the vehicle V, and may be a household secondary battery, a power system, or the like in addition to a specific electric product.

  The user connects the external charger 9 and the vehicle V and charges the high voltage battery 2 of the vehicle V with the electric power supplied from the external power source 95, or uses the electric power supplied from the high voltage battery 2 of the vehicle V as an electric load. When power is supplied to 96, the connector 91 is connected to the inlet 51. When the connector 91 is connected to the inlet 51, the first power supply line 92 and power lines 21p and 21n described later are electrically connected. Thereby, the supply of power from the external power supply 95 of the external charger 9 to the high-voltage battery 2 (hereinafter also simply referred to as “external charging”) and the supply of power from the high-voltage battery 2 to the electric load 96 (hereinafter simply “ This is also called “external power feeding”).

  The vehicle V includes a travel motor M mechanically coupled to drive wheels (not shown), a power supply system 1 that supplies power to the travel motor M, an inverter 71 that converts power supplied from the power supply system 1, and voltage conversion. (Hereinafter, abbreviated as “VCU”) 72 and a touch panel P that can be viewed and operated by the driver. As this touch panel P, for example, a car navigation system mounted on the vehicle V is used.

  The traveling motor M is, for example, a three-phase AC motor. The VCU 72 is, for example, a bidirectional DC-DC converter including a plurality of switching elements (for example, IGBT). The VCU 72 boosts a DC voltage supplied from the high voltage battery 2 via main power lines 21p and 21n, which will be described later, and supplies the boosted voltage to the inverter 71, or steps down a DC voltage supplied from the inverter 71, and supplies the high voltage battery 2 to the VCU 72. Or to supply. The inverter 71 is, for example, a PWM inverter based on pulse width modulation including a bridge circuit configured by bridge-connecting a plurality of switching elements (for example, IGBTs). The inverter 71 has a DC input / output side connected to the VCU 72 via main power lines 21p and 21n, and an AC input / output side connected to the U-phase, V-phase, and W-phase coils of the traveling motor M. The traveling motor M travels by generating driving force when electric power is supplied from the high voltage battery 2 via the VCU 72 and the inverter 71. Moreover, the traveling motor M generates electric power by performing regenerative operation. The electric power generated by the regenerative operation of the traveling motor M is supplied to the high voltage battery 2 via the inverter 71 and the VCU 72 and is charged.

  The power supply system 1 includes a high-voltage battery 2, a positive-side main power line 21 p and a negative-side main power line 21 n (hereinafter collectively referred to as “main power lines 21 p and 21 n”) that connect the high-voltage battery 2 to the VCU 72 and the inverter 71 described above. ), An external charging unit 5 to which the external charger C is connected, a battery ECU 60 that is an electronic control unit that estimates the internal state of the high-voltage battery 2, and sensors 61, 62, and 63 that detect the state of the high-voltage battery 2. .

  The high-voltage battery 2 is a secondary battery capable of both discharging for converting chemical energy into electric energy and charging for converting electric energy into chemical energy. Hereinafter, as the high-voltage battery 2, a case where a so-called lithium ion storage battery that performs charging / discharging by moving lithium ions between electrodes will be described, but the present invention is not limited thereto.

  Among the main power lines 21p and 21n, the high-voltage battery 2 side of the VCU 72 is connected to the positive-side main contactor 22p and the negative-side main contactor 22n (hereinafter referred to as “main contactor 22p, 22n ").

  The main contactors 22p and 22n are normally open types that are opened when no external command signal is input, and that disconnects the connection between the high voltage battery 2 and the VCU 72. These main contactors 22p and 22n are closed or opened according to a command signal from the battery ECU 60. More specifically, these main contactors 22p and 22n are closed in accordance with a command signal from the battery ECU 60, for example, when charging / discharging between the high voltage battery 2 and the VCU 72 while the vehicle V is traveling. Then, the high voltage battery 2 and the VCU 72 are connected.

  The battery current sensor 61 is a discharge current that flows through the high-voltage battery 2 when power is supplied from the high-voltage battery 2 to a load such as the travel motor M or the external charger 9, or the high-voltage battery 2 from the travel motor M or the external charger 9. When the electric power is supplied to the battery, a charging current flowing through the high voltage battery 2 is detected, and a signal corresponding to the detected value is transmitted to the battery ECU 60. Battery voltage sensor 62 detects the terminal voltage of high-voltage battery 2 and transmits a signal corresponding to the detected value to battery ECU 60. Battery temperature sensor 63 detects the temperature of high-voltage battery 2 and transmits a signal corresponding to the detected value to battery ECU 60.

  The battery ECU 60 is a microcomputer that performs control related to the estimation of the internal state of the high-voltage battery 2 (more specifically, the SOC [%] of the high-voltage battery 2) in addition to the opening / closing control of the main contactors 22p and 22n. Here, the SOC is a percentage of the remaining capacity of the high voltage battery 2 with respect to the battery capacity. A specific procedure for estimating the SOC of the high voltage battery 2 in the battery ECU 60 will be described later with reference to FIG.

  The external charging unit 5 includes an inlet 51 that can be connected to the connector 91 of the external charger 9, a charging lid 52 that protects the inlet 51, a connector sensor 53 that detects the connection of the connector 91 to the inlet 51, and the inlet 51. Are connected to the main power lines 21p and 21n and the sub power lines 54n and 54n (hereinafter collectively referred to as “sub power lines 54p and 54n”) and the sub power lines 54p and 54n. The vehicle-mounted charger 55 and a charge ECU 56 that is an electronic control unit that controls the vehicle-mounted charger 55 are provided.

  The sub power lines 54p and 54n extend from the inlet 51 and reach between the main contactors 22p and 22n and the VCU 72 of the main power lines 21p and 21n. When the connector 91 is connected to the inlet 51, the first power supply line 92 of the external charger C and the auxiliary power lines 54p and 54n and the main power lines 21p and 21n on the vehicle V side are electrically connected.

  The charging lid 52 has a plate shape and is pivotally supported by a hinge 52a provided on a vehicle body (not shown) of the vehicle V so as to be opened and closed. When the charging lid 52 is closed, the charging lid 52 forms a part of the outer panel of the vehicle V, so that the inlet 51 is protected. Further, when the charging lid 52 is opened, the inlet 51 is exposed to the outside, and thus the user can connect the connector 91 to the inlet 51.

  The connector sensor 53 is turned off while the connector 91 is not connected to the inlet 51, and transmits a signal indicating that to the charging ECU 56 when the connector 91 is connected to the inlet 51. Whether or not the connector 91 is connected to the inlet 51 is determined by the charging ECU 56 based on a detection signal from the connector sensor 53.

  The in-vehicle charger 55 includes a power factor correction circuit, a rectifier, a smoothing circuit, an inverter circuit, and the like. The on-vehicle charger 55 uses these circuits to convert an alternating current supplied from the external power supply 95 of the external charger 9 into a direct current and supply the high voltage battery 2 to charge the high voltage battery 2, and a high voltage battery. It is possible to selectively exert two functions according to a control signal from the charging ECU 56, that is, an external power feeding function that converts a direct current supplied from the power source 2 into an alternating current and discharges it to the electric load 96 of the external charger 9. It has become.

  When the SOC of the high-voltage battery 2 estimated by the battery ECU 60 is equal to or less than a predetermined value, the charging ECU 56 performs on-vehicle charging triggered by detecting that the connector 91 is connected to the inlet 51 via the connector sensor 53. The external charging from the external power source 95 to the high voltage battery 2 is performed by causing the device 55 to exhibit the external charging function. In addition, the charging ECU 56 indicates that the connector 91 is connected to the inlet 51 via the connector sensor 53 when the SOC of the high voltage battery 2 is equal to or higher than the predetermined value and the user is requested to perform external power feeding. When the vehicle charger 55 exhibits an external power supply function triggered by the detection of the power supply, external power supply from the high voltage battery 2 to the electric load 96 is performed.

  In addition, when the battery ECU 60 is required to execute a learning process described later, the charging ECU 56 performs a learning process that causes the in-vehicle charger 55 to perform the external charging function and the external power feeding function in a predetermined order. A specific procedure of the learning process in the charging ECU 56 will be described later in detail with reference to FIGS.

  The control devices such as the charging ECU 56 and the battery ECU 60 are connected to each other via a CAN bus 57 that is a bus network for transmitting and receiving various types of control information. It is possible.

  FIG. 2 is a functional block diagram showing a configuration of a part related to the estimation of the SOC of the high-voltage battery 2 in the control module realized by the battery ECU 60.

  The battery ECU 60 determines the open-circuit voltage of the high-voltage battery 2 (the terminal voltage of the high-voltage battery 2 in a state where no current flows through the high-voltage battery 2 based on the detection signals of the sensors 61 to 63, and hereinafter referred to as “OCV”. Based on the OCV estimation value obtained by the OCV estimation unit 65 on the basis of the OCV estimation unit 65 that estimates the correlation characteristics between the SOC and the OCV in the high-voltage battery 2 and the OCV estimation unit 65 An SOC estimation unit 66 for estimating the SOC, and a map learning device 67 for executing a learning process for updating the SOC-OCV map defined in the SOC estimation unit 66 to one according to deterioration of the high-voltage battery 2; Prepare.

The OCV estimation unit 65 calculates an OCV estimated value corresponding to the estimated value of the OCV of the high voltage battery 2 based on the detection signals of the sensors 61 to 63 connected to the high voltage battery 2. The OCV estimation unit 65 includes, for example, an RC parallel circuit including a first internal resistance having a resistance value R ₀ as shown in FIG. 3, a second internal resistance having a resistance value R ₁ , and an internal capacitor having a capacitance value C _1. Based on the equivalent circuit model of the high voltage battery 2 configured by connecting the two in series, the OCV estimated value is calculated.

According to the equivalent circuit model of FIG. 3, when the current flowing through the battery is I, the terminal voltage of the battery is CCV, and the open-circuit voltage of the battery is OCV, the terminal voltage CCV is as shown in the following equation (1). The first voltage drop (R ₀ I) in the first resistor and the second voltage drop (V _C ) in the RC parallel circuit are subtracted from the open-circuit voltage OCV. In the following formula (1), the value of the terminal voltage CCV can be specified based on the detection value of the battery voltage sensor 62, the value of the current I can be specified based on the detection value of the battery current sensor 61, and the resistance value R ₀ and the value of the voltage drop V _C can be identified on the basis of the detected value of the detection value and the battery temperature sensor 63 of the battery current sensor 61. Therefore, the OCV estimation unit 65 calculates an OCV estimated value in the energized high voltage battery 2 by using the detected values of the sensors 61 to 63 and the equivalent circuit model.
CCV = OCV-R ₀ I-V _C (1)

  Returning to FIG. 2, the SOC estimation unit 66 includes an SOC-OCV map (for example, see FIG. 4) that represents the correlation characteristics between the SOC and the OCV of the high-voltage battery 2 and is calculated by the OCV estimation unit 65. By inputting the estimated OCV estimated value into this SOC-OCV map, the estimated SOC value corresponding to the OCV estimated value is calculated. As shown in FIG. 4, the correlation characteristic between the SOC and the OCV of the high voltage battery 2 shows a non-linear change according to the progress of the deterioration of the high voltage battery 2. Therefore, the content of the SOC-OCV map defined by the SOC estimation unit 66 is appropriately updated according to the progress of the deterioration of the high voltage battery 2 by the learning process executed by the map learning device 67. Moreover, the SOC estimated value of the high voltage battery 2 calculated by the SOC estimating unit 66 while the vehicle V is traveling is used, for example, for energy management control (not shown) of the vehicle V.

  The map learning device 67 includes a learning necessity determination unit 671, a battery capacity calculation unit 672, an open-end voltage acquisition unit 673, and a correlation characteristic acquisition unit 674, and executes a learning process using these.

  The learning necessity determination unit 671 determines whether or not the learning process is necessary by inquiring about the intention of the user via the touch panel P. Since the deterioration of the high voltage battery 2 gradually proceeds with its use, the correlation characteristic between the SOC and the OCV of the high voltage battery 2 also gradually proceeds. As will be described in detail later, the learning process takes about several hours from the start to the end. For this reason, even if learning processing is performed frequently, there is little profit.

  Therefore, the learning necessity determination unit 671 determines whether or not the learning process needs to be performed on the touch panel P when the predetermined use period has elapsed since the use start time of the high-voltage battery 2 or the previous learning process execution time. A message to be inquired (specifically, for example, “Do you want to learn battery characteristics?”) Is displayed when the vehicle V is stopped, for example. Here, the use period is a period in which a significant change is expected to appear in the contents of the SOC-OCV map, and specifically, for example, half a year. In addition, as a result of displaying a message on the touch panel P, the learning necessity determination unit 671 receives an operation that does not require execution of the learning process from the user (specifically, an operation that touches a “NO” button, for example). Does not require execution of the learning process.

  Further, when the learning necessity determination unit 671 displays a message on the touch panel P, the learning necessity determination unit 671 receives an operation requesting execution of the learning process (specifically, an operation of touching a “YES” button, for example) from the user. The charging ECU 56 and the battery capacity calculation unit 672 are requested to execute the learning process.

  When the charging ECU 56 receives a learning process execution request from the learning necessity determination unit 671, the charging ECU 56 executes the first charging process, the discharging process, and the intermittent charging process in this order.

  First, in the first charging process, the charging ECU 56 charges the high voltage battery 2 until the high voltage battery 2 is fully charged. Here, the fully charged state is a state where the SOC of the high voltage battery 2 is 100%. Whether or not the high voltage battery 2 is fully charged can be determined, for example, depending on whether or not the voltage of the high voltage battery 2 is equal to or higher than a predetermined upper limit voltage.

  In the discharging process, the charging ECU 56 discharges the high voltage battery 2 until the high voltage battery 2 changes from the fully charged state to the lower limit charged state. Here, the lower limit charging state is a state in which the SOC of the high voltage battery 2 is 0%. Whether or not the high voltage battery 2 is in the lower limit charged state can be determined, for example, depending on whether or not the voltage of the high voltage battery 2 is equal to or lower than a predetermined lower limit voltage.

In the intermittent charging process, the charging ECU 56 intermittently charges the high voltage battery 2 until the high voltage battery 2 changes from the lower limit charged state to the fully charged state again. More specifically, as shown in FIG. 5, the charging ECU 56 is described later between a lower limit charging state indicating a state where the SOC is 0% and a fully charged state indicating a state where the SOC is 100%. Three or more (N) measurement points P ₁ , P ₂ ,..., P _N−1 , P _N are defined based on the estimated battery capacity value calculated by the battery capacity calculation unit 672. Here, the measurement point P ₁ of the smallest number corresponds to the lower limit charge state, the measurement point P _N of the higher number corresponds to a fully charged state. The charging ECU 56 determines the estimated SOC value of the high-voltage battery 2 for each of the measurement points P ₁ , P ₂ ,..., P _N−1 , P _N while charging from the lower limit charging state to the full charging state. When the SOC threshold values SOC ₁ (= 0), SOC ₂ ,..., SOC _N−1 , SOC _N (= 100) are reached, the high voltage battery 2 is charged for a predetermined waiting time (for example, several times) For a minute or so), and after a time longer than this waiting time has elapsed, charging is resumed.

  Note that the position of the measurement point, that is, the magnitude of the SOC threshold value determined for the SOC for each measurement point may be set to be equidistant between the lower limit charge state and the full charge state. You may set so that it may become especially dense in the specific area | region where it is anticipated that a big change will appear in the correlation characteristic between OCV.

  Returning to FIG. 2, the battery capacity calculation unit 672 is detected by the battery current sensor 61 until the high-voltage battery 2 is changed from the fully charged state to the lower limit charged state by the discharge process being performed in the charge ECU 56. By integrating the discharge current of the high voltage battery 2, an estimated battery capacity value that is an estimated value of the current battery capacity of the high voltage battery 2 is calculated.

The open end voltage acquisition unit 673 is configured to measure each of the measurement points P _{1 to} P as described above after the first charging process or the discharging process by the charging ECU 56 or while the intermittent charging process is being performed in the charging ECU 56. The detected value of the OCV of the high-voltage battery 2 is acquired using the battery voltage sensor 62 within a period in which charging is temporarily stopped over a waiting time at _N. Here, the open-ended voltage acquisition unit 673 uses the battery voltage sensor 62 to detect the OCV as accurately as possible, so that the charging is temporarily performed instead of immediately after the charging is temporarily stopped at each of the measurement points P _{0 to} P _N. It is preferable to read the detection value of the battery voltage sensor 62 after a time equal to or longer than the waiting time has elapsed since the operation was stopped, that is, immediately before charging is resumed by the charging ECU 56. In an open circuit voltage acquisition unit 673 by the above, each measurement point _{P 1,} P 2 as shown in FIG. _{5, ..., P N-1} , P N OCV detection value for each _{OCV 1, OCV 2, ...,} OCV N- ₁ , OCV _N is acquired.

Correlation characteristic acquisition unit 674, the measurement points _{P 1, P 2, ...,} P N-1, SOC threshold _SOC in _{P N 1,} SOC 2, _..., and _SOC N-1, SOC _N, open circuit voltage acquisition unit each measurement point by _{673 P 1, P 2, ...} , P N-1, P OCV detected values obtained in _{N OCV 1, OCV 2, ...} , on the basis of the _{OCV N-1, OCV} N, the current high pressure A new SOC-OCV map that conforms to battery 2 is constructed. More specifically, the correlation characteristic acquisition unit 674 uses a known interpolation algorithm for a curve that passes through N detection points specified by the SOC threshold values SOC _{1 to} SOC _N and the OCV detection values OCV _{1 to} OCV _N. A new SOC-OCV map is constructed by using this, and the SOC-OCV map defined in the SOC estimation unit 66 is replaced with the newly constructed SOC-OCV map.

  FIG. 6 is a flowchart showing a specific procedure of a learning process in which the charging ECU 56 and the battery ECU 60 learn the correlation characteristics between the SOC and the OCV of the high-voltage battery 2. The flowchart of FIG. 6 starts in response to, for example, the charging lid 52 being opened by the user, the connector 91 being further inserted into the inlet 51, and the charging ECU 56 and the battery ECU 60 being activated.

  First, in S1, the charging ECU 56 determines whether or not an external charger capable of performing bidirectional charging (that is, both external charging and external power feeding of the high-voltage battery 2) is connected. If the determination in S1 is YES, the process proceeds to S2, and if NO, the process proceeds to S15.

  In S2, the charging ECU 56 acquires the current temperature of the high-voltage battery 2 using the battery temperature sensor 63, and determines whether or not the battery temperature is equal to or higher than a specified temperature (for example, 0 ° C.). When the determination in S2 is YES, it is determined that the temperature of the high voltage battery 2 is a temperature suitable for executing the learning process described below, and the process proceeds to S3. If the determination in S2 is NO, it is determined that the temperature of the high voltage battery 2 is not suitable for executing the learning process, and the process proceeds to S15. If the temperature of the high-voltage battery 2 is too low, the performance of the high-voltage battery 2 is deteriorated, which is not suitable for executing the learning process.

  In S <b> 3, the charging ECU 56 determines whether the learning necessity determination unit 671 has requested execution of the learning process. As described above, in the learning necessity determination unit 671, the use period has elapsed from the start of use of the high-voltage battery 2 or the previous execution time of the learning process, and an operation for requesting the execution of the learning process is performed by the user. If yes, the execution of the learning process is requested. If the determination in S3 is YES, the process moves to S4 and a series of learning processes is started. If the determination in S3 is NO, the process proceeds to S15.

  First, in S4, the charging ECU 56 executes the first charging process, and proceeds to S5. More specifically, the charging ECU 56 causes the in-vehicle charger 55 to perform an external charging function, so that the battery voltage detected by the battery voltage sensor 62 reaches the upper limit voltage, that is, the high voltage battery 2 is in a fully charged state. The electric power of the external power source 95 is supplied to the high voltage battery 2 until the voltage becomes high voltage. When the high voltage battery 2 becomes fully charged, the charging ECU 56 stops the on-vehicle charger 55 and stops charging and discharging of the high voltage battery 2.

In S5, the open-ended voltage acquisition unit 673 of the battery ECU 60 causes the high-voltage battery 2 to be charged to the high-voltage battery 2 over a predetermined waiting time (for example, about several minutes) after the high-voltage battery 2 is fully charged and stops charging and discharging. After maintaining the state in which no current flows, the open voltage value OCV _N at full charge is obtained by reading the detection value of the battery voltage sensor 62.

  In S6, the charging ECU 56 executes a discharging process and proceeds to S7. More specifically, the charging ECU 56 causes the in-vehicle charger 55 to perform an external power feeding function, so that the battery voltage detected by the battery voltage sensor 62 reaches the lower limit voltage, that is, the high voltage battery 2 is in the lower limit charging state. Electric power is supplied from the high-voltage battery 2 to the electric load 96 until the voltage becomes high, and the high-voltage battery 2 is discharged. When the high-voltage battery 2 is in the lower limit charging state, the charging ECU 56 stops the on-vehicle charger 55 and stops charging and discharging of the high-voltage battery 2. While the discharging process is being executed in the charging ECU 56, the battery capacity calculating unit 672 of the battery ECU 60 reads the detection value of the battery current sensor 61 at a predetermined cycle, and further calculates the integrated value.

In S7, the open-ended voltage acquisition unit 673 of the battery ECU 60 maintains the state where no current flows through the high-voltage battery 2 for the waiting time or longer after the high-voltage battery 2 enters the lower limit charge state and stops charging and discharging. By reading the detection value of the battery voltage sensor 62, the lower limit charging open circuit voltage value OCV ₁ is obtained.

  In S8, the battery capacity calculation unit 672 of the battery ECU 60 calculates the integrated value of the detection values of the battery current sensor 61 during the discharge process until the high voltage battery 2 changes from the fully charged state to the lower limit charged state. Is the battery capacity value Capa.

  Next, in S9, the charging ECU 56 and the battery ECU 60 determine that the value of the counter i (an integer from 2 to N described later) is the number of measurement points until the high voltage battery 2 changes from the lower limit charging state to the full charging state. The process of S10 to S12 is repeatedly executed until N is reached. Here, whether or not the high-voltage battery 2 is fully charged can be determined, for example, based on whether or not the battery voltage has reached the upper limit voltage as in S4. It can also be determined by whether or not the integrated value of the detected values has reached the battery capacity value Capa calculated in S8.

In S10, the charging ECU 56 performs an intermittent charging process, and proceeds to S11. More specifically, the charging ECU 56 defines _N measurement points P _{1 to} P _N between the lower limit charging state and the full charging state with reference to the battery capacity value Capa calculated in S9, and is mounted on the vehicle. By causing the charger 55 to perform an external charging function, the measurement point P _i where the high voltage battery 2 is specified by the counter i (where the counter i is an integer with an initial value of 2 and is 1 in S12 described later) Power of the external power source 95 is supplied to the high voltage battery 2 until the high voltage battery 2 is fully charged, that is, until the high voltage battery 2 is fully charged. Charging ECU56, when the high-voltage battery 2 reaches the measurement point P _i, stop the vehicle charger 55, the charging and discharging of the high-voltage battery 2 is stopped for more than latency. Not here whether the high-voltage battery 2 reaches the measurement point P _i, for example, whether the integrated value of the detected value of the battery current sensor 61 during charging has reached the charge amount (Capa / N-1) × i It can be judged by.

In S11, an open circuit voltage acquiring unit 673 of the battery ECU60 is high-voltage battery 2 reaches the measurement point P _i, maintenance stop the charging and discharging, a state where no current flows through the high-voltage battery 2 for over latency After that, the OCV detection value OCV _i at the measurement point P _i is obtained by reading the detection value of the battery voltage sensor 62. In S12, the charging ECU 56 adds 1 to the counter i, returns to S10, and resumes charging toward the next measurement point P _{i + 1} . As described above, in the processing of S9~S12 while performing an intermittent charging process by the charging ECU 56, the measurement points by the open circuit voltage acquiring section 673 _P 2 _{~P N-1} in the OCV value detected _OCV 2 _{~OCV N- 1} is acquired. Note that the OCV detection values OCV ₁ and OCV _N are acquired in S7 and S5 executed earlier, respectively, and therefore do not need to be positively acquired in S9 to S12.

In S13, the correlation characteristic acquisition unit 674 of the battery ECU60, such as passing through the N-number of detection points that are identified by the previous SOC threshold _SOC 1 obtained in the processing of ～SOC _N and OCV value detected _OCV 1 ～OCV _N A new SOC-OCV map is constructed by creating a curve using a known interpolation algorithm, and the process proceeds to S14.

  In S14, the correlation characteristic acquisition unit 674 replaces the SOC-OCV map defined in the current SOC estimation unit 66 with the SOC-OCV map newly constructed in S13 this time, and proceeds to S15.

  In S15, the charging system S is turned off, and the process of FIG. Note that the learning process as described above takes about several hours from the start in S4 to the end in S14. For this reason, the connector 91 may be removed by the user and the vehicle V may be activated during the execution of the learning process. In such a case, it is preferable to interrupt the learning process being executed and continue to use the old SOC-OCV map.

According to the battery state estimation method of the present embodiment, the following effects can be obtained.
(1) In the battery state estimation method, first, the high voltage battery 2 is charged until the fully charged state is reached (first charging step of S4), and then the high voltage battery 2 is discharged until the fully charged state reaches the lower limit charged state. At the same time, the estimated battery capacity of the high-voltage battery 2 is calculated by integrating the discharge currents during that time (discharge process of S6). Here, in the battery state estimation method, the battery capacity of the high-voltage battery 2 can be accurately estimated although it takes time by using the integrated value of the discharge current from the fully charged state to the lower limit charged state. Thereafter, in the battery state estimation method, the high-voltage battery 2 is charged again from the lower limit charge state to the full charge state, and a plurality of measurement points P _{1 to} P _N are defined between the lower limit charge state and the full charge state, The charging is stopped for a predetermined waiting time or more each time the measurement point is reached during charging, and the OCV of the high-voltage battery 2 is measured after the waiting time or more has elapsed, and the charging is restarted after the measurement (S9 to S9). (Second charging step of S12). Here, in the battery state estimation method, each time it reaches each of the measurement points P _{1 to} P _N during charging, the charging is stopped over the waiting time and then the OCV is measured. The OCV at the measurement points P _{1 to} P _N can be measured with high accuracy. Further, as described above, since the battery capacity can be accurately estimated by executing the discharging process first in the battery state estimation method, the measurement points P _{1 to} P _N can be defined on the basis of the battery capacity, and as a result, each measurement point P It is also possible to accurately estimate the SOC in _{1 to PN} . In the battery state estimating method, based on the SOC threshold value _SOC 1 _{~SOC N} and OCV value detected _OCV 1 _{~OCV N} at each measurement point _P 1 to P _N obtained as described above, the high-voltage battery 2 SOC- Build a new OCV map. As described above, according to the battery state estimation method, it takes time to charge until it reaches a fully charged state, then discharge until it reaches a lower limit charged state, and then charge until it reaches a fully charged state. An SOC-OCV map that changes due to deterioration can be constructed with high accuracy. In addition, by using an accurate SOC-OCV map in this way, the SOC of the high voltage battery 2 can also be accurately estimated. Moreover, in the battery state estimation method, the construction of the SOC-OCV map can be completed in a state where the high voltage battery 2 is in a fully charged state, which is convenient.

  (2) The battery state estimation method takes time because it is necessary to perform charging, discharging, and recharging in order to newly construct an SOC-OCV map. Therefore, in the battery state estimation method, the first charging step, the discharging step, the second charging step, and the correlation characteristic obtaining step are performed while the vehicle V is stopped, that is, using a period in which the user does not use the vehicle V. Get correlation characteristics. Thereby, it is possible to prevent the convenience for the user from being impaired.

  (3) In the battery state estimation method, a bidirectional in-vehicle charger 55 capable of exhibiting an external charging function and an external power feeding function is used for charging in the first charging process and the second charging process and discharging in the discharging process. Do it. Thereby, in the discharging step, the electric power discharged from the high voltage battery 2 until it reaches the lower limit charging state from the fully charged state can be effectively used by an electric power network or an electric load connected to the in-vehicle charger 55.

  (4) Since the correlation characteristics of the high-voltage battery 2 gradually change as the deterioration progresses, it is not necessary to update it frequently. Further, the battery state estimation method takes time because it is necessary to perform discharging and recharging. Therefore, in the battery state estimation method, the learning process is executed only when a new acquisition of correlation characteristics is requested from the user via the touch panel P mounted on the vehicle V, and the SOC-OCV map of the high voltage battery 2 is obtained. To get. Thereby, it is possible to prevent the SOC-OCV map from being newly constructed against the user's intention, and the convenience from being impaired.

  (5) As described above, the correlation characteristics of the high-voltage battery 2 gradually change with the progress of the deterioration, and therefore do not need to be updated frequently. Therefore, in the battery state estimation method, the learning process is executed on the condition that at least a predetermined use period has elapsed since the use start time of the high voltage battery 2 or the previous acquisition time of the correlation characteristics. Thereby, it is possible to prevent the learning process from being performed more frequently than necessary and the convenience for the user from being impaired.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to this. Within the scope of the gist of the present invention, the detailed configuration may be changed as appropriate.

  For example, in the above-described embodiment, the learning necessity determination unit 671 executes the learning process via the touch panel P when a predetermined usage period has elapsed from the start of use of the high voltage battery 2 or the previous learning process. The user is inquired of necessity, and when the user performs an operation for requesting execution of the learning process, the charging ECU 56 and the battery capacity calculation unit 672 are requested to execute the learning process. That is, in the above embodiment, the use period has elapsed from the start of use or the previous execution time of the learning process (first condition), and the user has performed an operation requesting the execution of the learning process (first 2), the learning process is requested to be executed, but the present invention is not limited to this. For example, the learning necessity determination unit may request execution of the learning process when any one of the two conditions is satisfied. That is, the learning necessity determination unit may request execution of the learning process regardless of the user's intention when the use period has elapsed from the start of use or the previous execution time of the learning process. . In addition, when the user performs an operation requesting execution of the learning process via the touch panel P at an arbitrary timing, the learning necessity determination unit determines that the use period has elapsed from the use start time or the previous learning process execution time. You may make it request | require execution of a learning process, even if it has not passed.

  Further, for example, in the above-described embodiment, the case where the present invention is applied to the vehicle V equipped with the in-vehicle charger 55 capable of selectively exerting two functions of the external charging function and the external power feeding function has been described, but the present invention is not limited thereto. . The battery state estimation method and the battery state estimation device according to the present invention can be applied to a vehicle equipped with an in-vehicle charger that does not have an external power feeding function and has an external charging function. When applied to such a vehicle, in the discharge process in S6 of FIG. 6, the high voltage battery is detected until the battery voltage detected by the battery voltage sensor 62 reaches the lower limit voltage, that is, until the high voltage battery 2 is in the lower limit charged state. It is preferable to forcibly discharge from 2 to a vehicle-mounted load (specifically, for example, a traveling motor M, an auxiliary machine load, a discharge resistor, etc.) mounted on the vehicle.

S ... Charging system (battery state estimation device)
V ... Vehicle (moving body)
1 ... Power system 2 ... High voltage battery (battery)
5 ... External charging unit 55 ... In-vehicle charger (bidirectional charger)
56 ... Charging ECU (charging / discharging means, intermittent charging means)
60 ... Battery ECU (battery capacity calculation means, open-end voltage acquisition means, correlation characteristic acquisition means)
65 ... OCV estimation unit 66 ... SOC estimation unit 67 ... Map learning device 671 ... Learning necessity determination unit 672 ... Battery capacity calculation unit (battery capacity calculation means)
673... Open end voltage acquisition unit (open end voltage acquisition means)
674 ... Correlation characteristic acquisition unit (correlation characteristic acquisition means)
61 ... Battery current sensor (current detection means)
62 ... Battery voltage sensor (voltage detection means)
P ... Touch panel (Acquisition decision unit)
9 ... External charger 95 ... External power supply (power supply, external power supply)
96 ... Electric load

Claims (6)

A battery state estimation method for obtaining a correlation characteristic between an open-circuit voltage of a battery that changes due to deterioration and a charging rate,
A first charging step of connecting a power source to the battery and charging the battery until the battery is fully charged;
Discharging the battery until the battery is discharged from a fully charged state to a lower limit charged state, and calculating the battery capacity of the battery by integrating the discharging current during the discharge,
The battery is charged again until it reaches the fully charged state from the lower limit charged state, and charging is stopped for a predetermined time or more each time a plurality of defined measurement points are reached between the lower limit charged state and the fully charged state, A second charging step of measuring the open-circuit voltage of the battery after elapse of the predetermined time and restarting charging after the measurement;
A battery state estimation method comprising: a correlation characteristic acquisition step of acquiring the correlation characteristic of the battery based on a charging rate at each measurement point and an open-circuit voltage measured at each measurement point. The battery is mounted on a moving body,
The power source is an external power source provided outside the moving body,
The first charging step, the discharging step, the second charging step, and the correlation characteristic acquisition step are performed in response to the connection of the external power source while the moving body is stopped. The battery state estimation method according to claim 1. The mobile body can perform both external charging for charging the battery with power supplied from the external power source and external power feeding for discharging from the battery to an external supply target provided outside the mobile body. Equipped with a charger
The battery state estimation method according to claim 2, wherein the charging in the first charging step and the second charging step and the discharging in the discharging step are performed using the bidirectional charger. The mobile body is equipped with acquisition possibility determination means operable by a user to select whether or not to newly acquire the correlation characteristic,
The first charging step, the discharging step, the second charging step, and the correlation characteristic acquisition step are executed only when the acquisition of the correlation characteristic is selected via the acquisition possibility determination unit. The battery state estimation method according to claim 2, wherein the battery state is estimated.   The first charging step, the discharging step, the second charging step, and the correlation characteristic acquisition step are performed on the condition that at least a predetermined usage period has elapsed from the use start time of the battery or the previous correlation property acquisition time. The battery state estimation method according to claim 1, wherein the battery state estimation method is executed as follows. A battery state estimation device that acquires a correlation characteristic between an open-circuit voltage of a battery that changes due to deterioration and a charging rate,
Voltage detecting means for detecting the voltage of the battery;
Current detection means for detecting the current of the battery;
Charging / discharging means for supplying power from the power source to the battery, charging the battery until it reaches a fully charged state, supplying power from the battery to a discharge target, and discharging the battery until it reaches a lower limit charging state; ,
Battery capacity calculation means for calculating the battery capacity of the battery by integrating the discharge current detected by the current detection means until the battery is changed from the fully charged state to the lower limit charged state by the charge / discharge means; ,
Power is supplied from the power source to the battery, the battery is charged until it reaches the fully charged state from the lower limit charged state, and a plurality of defined measurement points are reached between the lower limit charged state and the fully charged state. Intermittent charging means for temporarily recharging after temporarily stopping charging for a predetermined time or more each time,
Open-circuit voltage acquisition means for acquiring the open-circuit voltage of the battery by the voltage detection means while charging is temporarily stopped by the intermittent charging means at each measurement point;
Correlation characteristic acquisition means for acquiring the correlation characteristic of the battery based on the charging rate at each measurement point and the open-end voltage measured at each measurement point by the open-end voltage acquisition means. A battery state estimation device.

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