JP2020139846A - State estimation device - Google Patents

Abstract

To provide a state estimation device capable of preventing errors in SOC values of secondary cells.SOLUTION: In a state estimation device 20, a voltage acquisition section 21 acquires voltage measured values E1 and E2 from a voltage sensor measuring terminal voltage representing voltage between an anode terminal of a secondary cell and a cathode terminal of the secondary cell. The voltage measured value E1 expresses terminal voltage at a first time of day when current flown through the secondary cell becomes zero. The voltage measured value E2 expresses terminal voltage at a time of day when a prescribed stand-by time has elapsed from the first time of day. A voltage estimation section 24 estimates, based on the acquired voltage measured values E1 and E2, open-circuit voltage of the secondary cell at the first time of day. A charge state estimation section 25 estimates, based on the estimated open-circuit voltage, a charge state of the secondary cell.SELECTED DRAWING: Figure 2

Description

The present invention relates to a state estimation device that estimates the state of charge of a secondary battery.

Electric vehicles such as hybrid vehicles and electric vehicles are equipped with a power source that supplies electric power to a motor that is a power source. A secondary battery is mainly used as a power source. The secondary battery supplies electric power to the motor by discharging, and stores the regenerative electric power generated by the motor by charging.

The electric vehicle is equipped with a state estimation device that estimates the SOC (State Of Charge) value of the secondary battery so that the electric power of the secondary battery can be stably supplied to the motor. The SOC value indicates the state of charge of the secondary battery. The state estimation device acquires a current measurement value from a current sensor that measures the current flowing through the secondary battery, and estimates the SOC value using the integrated value of the acquired current measurement value.

Since the current measurement contains an error, the error in the current measurement is accumulated in the estimated SOC value. That is, the error of the estimated SOC value increases with the passage of time. Over-discharging or over-charging may occur in the secondary battery as the error in the estimated SOC value increases.

In order to maintain the accuracy of the SOC value estimated using the integrated value of the current measurement value, the state estimator uses the SOC value estimated using the integrated value as the OCV (Open Circuit Voltage) of the secondary battery. Use to correct. Specifically, the state estimation device acquires the OCV of the secondary battery and specifies the SOC value of the secondary battery based on the acquired OCV and the SOC-OCV characteristics of the secondary battery set in advance. The state estimation device corrects the SOC value estimated by using the current measurement value by using the SOC value specified by OCV.

Unlike the integrated value of the current measurement value, the OCV does not accumulate an error. Therefore, the accuracy of the SOC can be maintained by correcting the SOC value estimated using the current measurement value with the SOC value specified by using the OCV.

Patent Document 1 discloses a battery state estimation device that estimates the OCV of a secondary battery. When the ignition switch is turned off, the battery state estimator periodically measures the current flowing through the secondary battery, the terminal voltage of the secondary battery, and the temperature of the secondary battery. When the elapsed time since the ignition switch is turned off is 2 hours or more and less than 6 hours, the battery state estimator is secondary based on the measured value of the current, the measured value of the terminal voltage, and the measured value of the temperature. Calculate the OCV of the battery.

The battery state estimation device according to Patent Document 1 cannot estimate the OCV of the secondary battery until 2 hours have passed since the ignition switch was turned off. Since the SOC value estimated using the current measurement value is rarely corrected, the battery state estimation device cannot suppress the error of the SOC value estimated using the current measurement value.

Japanese Unexamined Patent Publication No. 2017-129402

In view of the above problems, an object of the present invention is to provide a state estimation device capable of suppressing an error in the SOC value of the secondary battery.

In order to solve the above problems, the first invention is a state estimation device including a voltage acquisition unit, a voltage estimation unit, and a charging state estimation unit. The voltage acquisition unit is the first time when the power of the device equipped with the secondary battery is turned off from the voltage sensor that measures the terminal voltage, which is the voltage between the positive terminal of the secondary battery and the negative terminal of the secondary electron. The first voltage measurement value in the above and the second voltage measurement value at the second time when a predetermined standby time has elapsed from the first time are acquired. The voltage estimation unit estimates the open circuit voltage of the secondary battery at the first time based on the first voltage measurement value acquired by the voltage acquisition unit and the second voltage measurement value acquired by the voltage acquisition unit. The charge state estimation unit estimates the charge state of the secondary battery based on the open circuit voltage estimated by the voltage estimation unit.

According to the first invention, the voltage estimator is based on the voltage of the secondary battery at each of the first time when the current flowing through the secondary battery becomes zero and the time when the standby time elapses from the first time. To estimate the open circuit voltage of the secondary battery. In the first invention, since the time for estimating the open circuit voltage of the secondary battery can be shortened, the chance of estimating the SOC value based on the open circuit voltage can be increased, so that the error of the SOC value of the secondary battery can be suppressed. ..

The second invention is the first invention, and further includes a temperature acquisition unit. The temperature acquisition unit acquires a temperature measurement value from a temperature sensor that measures the temperature of the secondary battery. The voltage estimation unit estimates the open circuit voltage based on the temperature measurement value acquired by the temperature acquisition unit.

According to the second invention, the temperature of the secondary battery is taken into account when estimating the open circuit voltage of the secondary battery. Thereby, the estimation accuracy of the open circuit voltage of the secondary battery can be improved.

The third invention is the first or second invention, and the voltage estimation unit includes a selection unit and a specific unit. The selection unit corresponds to the acquired first voltage measurement value and second voltage measurement value from a plurality of voltage change data indicating the time change of the open circuit voltage of the secondary battery after the power of the device is turned off. Select the voltage change data to be used. The specific unit specifies the open circuit voltage of the secondary battery at the first time with reference to the voltage change data selected by the selection unit.

According to the third invention, the SOC of the secondary battery based on the open circuit voltage can be quickly estimated by specifying the open circuit voltage of the secondary battery with reference to the voltage change data.

The fourth invention is a state estimation method including a) step, b) step, and c) step. a) The step is the first time when the power of the device equipped with the secondary battery is turned off from the voltage sensor that measures the terminal voltage, which is the voltage between the positive terminal of the secondary battery and the negative terminal of the secondary electron. The first voltage measurement value in the above and the second voltage measurement value at the second time when a predetermined standby time has elapsed from the first time are acquired. b) The step estimates the open circuit voltage of the secondary battery at the first time based on the acquired first voltage measurement value and the acquired second voltage measurement value. c) The step estimates the charge state of the secondary battery based on the estimated open circuit voltage.

The fourth invention is used in the first invention.

According to the present invention, it is possible to provide a state estimation device capable of suppressing an error in the SOC value of the secondary battery.

It is a functional block diagram which shows the structure of the in-vehicle system including the state estimation device which concerns on embodiment of this invention. It is a functional block diagram which shows the structure of the state estimation apparatus shown in FIG. It is a functional block diagram which shows the structure of the voltage estimation part shown in FIG. It is a flowchart which shows the operation of the state estimation apparatus shown in FIG. It is a figure which shows the time change of the terminal voltage when the secondary battery shown in FIG. 1 was discharged before the ignition signal was turned off. It is a figure which shows an example of the voltage change table shown in FIG. It is a figure which shows the time change of the terminal voltage when the secondary battery shown in FIG. 1 was charged before the ignition signal was turned off. It is a figure which shows another example of the voltage change table shown in FIG. It is a figure which shows the CPU bus configuration.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

[1. Configuration of in-vehicle system 100]
FIG. 1 is a functional block diagram showing a configuration of an in-vehicle system 100 including a state estimation device 20 according to an embodiment of the present invention. With reference to FIG. 1, the in-vehicle system 100 is mounted on a vehicle such as a hybrid electric vehicle (HEV) (not shown), for example. The in-vehicle system 100 supplies electric power from the secondary battery 5 to the motor generator 4, and supplies the regenerated electric power of the motor generator 4 to the secondary battery 5.

The in-vehicle system 100 includes a power management device 1, a vehicle control device 2, a conversion unit 3, a motor generator 4, a secondary battery 5, a relay 6, a current sensor 7A, a voltage sensor 7B, and a temperature sensor 7C. And an ignition switch 8.

The power management device 1 connects the conversion unit 3 and the secondary battery 5 according to the state of the ignition switch 8. When the conversion unit 3 is connected to the secondary battery 5, the power management device 1 calculates the SOC (state of charge) value 11. The power management device 1 outputs the calculated SOC value 11 to the vehicle control device 2 as an estimation result of the SOC of the secondary battery 5.

The SOC value 11 indicates the charge rate of the secondary battery 5 in the present embodiment. Alternatively, the SOC value 11 may be the residual capacity (Ah) of the secondary battery 5.

When the ignition switch 8 is turned on, the SOC value 11 is calculated based on the current measurement value Io generated by the current sensor 7A. When the ignition switch 8 is turned off, the SOC value 11 is corrected based on the open circuit voltage of the secondary battery 5. Specifically, the open circuit voltage of the secondary battery 5 is OCV (Open Circuit Voltage). Details of the calculation and correction of the SOC value 11 will be described later.

The vehicle control device 2 performs charge control or discharge control of the secondary battery 5 based on the SOC value 11 received from the power management device 1. When the vehicle control device 2 performs discharge control, the conversion unit 3 converts the direct current supplied from the secondary battery 5 into a three-phase alternating current according to the instruction of the vehicle control device 2. The motor generator 4 is driven by the converted three-phase alternating current to start an engine of an electric vehicle (not shown).

When the vehicle control device 2 performs charge control, the conversion unit 3 converts the three-phase alternating current supplied from the motor generator 4 into direct current in response to the instruction from the vehicle control device 2. For example, the motor generator 4 generates a three-phase alternating current when operating as a regenerative brake, and supplies the generated three-phase alternating current to the conversion unit 3. Further, the motor generator 4 generates electric power by the driving force of an engine of an electric vehicle (not shown) to generate three-phase alternating current.

The secondary battery 5 is, for example, an assembled battery and includes a plurality of battery stacks connected in series. Each of the plurality of battery stacks contains a plurality of cells connected in series. The cell is, for example, a lithium ion secondary battery or a nickel hydrogen secondary battery.

The relay 6 is turned on and off by the power management device 1. By turning on the relay 6, the secondary battery 5 is electrically connected to the conversion unit 3. By turning off the relay 6, the electrical connection between the conversion unit 3 and the secondary battery 5 is released.

The current sensor 7A measures the current flowing through the secondary battery 5 and generates a current measurement value Io as a measurement result. The current sensor 7A outputs the generated current measurement value Io to the power management device 1.

The voltage sensor 7B measures the terminal voltage of the secondary battery 5 and generates a voltage measurement value Eo as a measurement result. The terminal voltage is the potential difference between the positive electrode terminal and the negative electrode terminal of the secondary battery 5. The voltage sensor 7B outputs the generated voltage measurement value Eo to the power management device 1.

The temperature sensor 7C measures the temperature of the secondary battery 5 and generates a temperature measurement value To as a measurement result. The temperature sensor 7C outputs the generated temperature measurement value To to the power management device 1.

[2. Configuration of power management device 1]
The power management device 1 includes a relay control device 10 and a state estimation device 20.

The relay control device 10 controls the on / off of the relay 6 based on the ignition signal 81 from the ignition switch 8. When the ignition signal 81 is on, the ignition signal 81 indicates that the ignition switch 8 is on. In this case, the relay control device 10 turns on the relay 6 and electrically connects the secondary battery 5 to the conversion unit 3. When the ignition signal 81 is off, the ignition signal 81 indicates that the ignition switch 8 is off. In this case, the relay control device 10 turns off the relay 6 to release the electrical connection between the conversion unit 3 and the secondary battery 5.

The state estimation device 20 estimates the state of the secondary battery 5. Specifically, when the ignition signal 81 is on, the state estimation device 20 estimates the SOC value 11 based on the current measurement value Io received from the current sensor 7A. When the ignition signal 81 is turned off, the state estimation device 20 estimates the open circuit voltage of the secondary battery and corrects the SOC value 11 based on the estimated open circuit voltage.

[3. Configuration of state estimation device 20]
FIG. 2 is a functional block diagram showing the configuration of the state estimation device 20 shown in FIG. With reference to FIG. 2, the state estimation device 20 includes a current acquisition unit 21, a voltage acquisition unit 22, a temperature acquisition unit 23, a voltage estimation unit 24, a charging state estimation unit 25, and a storage unit 26. ..

The current acquisition unit 21 acquires the current measurement value Io from the current sensor 7A, and supplies the acquired current measurement value Io to the voltage estimation unit 24 and the charging state estimation unit 25.

The voltage acquisition unit 22 acquires the voltage measurement value Eo from the voltage sensor 7B, and supplies the acquired voltage measurement value Eo to the voltage estimation unit 24.

Specifically, the voltage acquisition unit 22 acquires the voltage measurement value E1 at the power-off time and the voltage measurement value E2 at the standby end time. The voltage acquisition unit 22 supplies the acquired voltage measurement values E1 and E2 to the voltage estimation unit 24. The power-off time is the time when the ignition signal 81 changes from on to off. The standby end time is a time when a preset standby time has elapsed from the power-off time.

The temperature acquisition unit 23 acquires the temperature measurement value To from the temperature sensor 7C, and supplies the acquired temperature measurement value To to the voltage estimation unit 24 and the charge state estimation unit 25. Specifically, the temperature acquisition unit 23 acquires the temperature measurement value T1 indicating the temperature of the secondary battery 5 at the power-off time.

The voltage estimation unit 24 receives the voltage measurement values E1 and E2 from the voltage acquisition unit 22, and receives the temperature measurement value T1 from the temperature acquisition unit 23. When the ignition signal 81 supplied from the ignition switch 8 is turned off, the voltage estimation unit 24 determines 2 at the power-off time based on the received voltage measurement values E1 and E2 and the received temperature measurement value T1. The open circuit voltage Es of the next battery 5 is estimated. The voltage estimation unit 24 supplies the estimated open circuit voltage Es to the charge state estimation unit 25. The configuration of the voltage estimation unit 24 will be described later.

The charge state estimation unit 25 receives the current measurement value Io from the voltage acquisition unit 22 during the period when the ignition signal 81 is on. The charge state estimation unit 25 estimates the SOC value 11 of the secondary battery 5 during the period when the ignition signal 81 is on, based on the acquired current measurement value Io. The charge state estimation unit 25 outputs the SOC value 11 to the vehicle control device 2 as the estimation result of the charge state of the secondary battery. Further, the charge state estimation unit 25 corrects the SOC 11 of the secondary battery 5 at the power-off time based on the open circuit voltage Es estimated by the voltage estimation unit 24.

The storage unit 26 is a non-volatile storage device, and stores the voltage change tables 31 and 32, the SOC determination data 33, and the corrected SOC value 12.

The voltage change table 31 shows the time change of the terminal voltage when the secondary battery 5 is discharged before the ignition signal 81 is turned off. The voltage change table 31 includes a plurality of terminal voltage change data 311. Each of the plurality of terminal voltage change data 311 records the change in the terminal voltage after the ignition signal 81 is turned off.

The voltage change table 32 shows the time change of the terminal voltage when the secondary battery 5 is charged before the ignition signal 81 is turned off. The voltage change table 32 includes a plurality of terminal voltage change data 321. Each of the plurality of terminal voltage change data 321 records the change in the terminal voltage after the ignition signal 81 is turned off.

The SOC determination data 33 records the SOC-OCV characteristics of the secondary battery 5. The corrected SOC value 11 is the SOC value 11 corrected by the charging state estimation unit 25.

[4. Configuration of voltage estimation unit 24]
FIG. 3 is a functional block diagram showing the configuration of the voltage estimation unit 24 shown in FIG. With reference to FIG. 3, the voltage estimation unit 24 includes a selection unit 241 and a specific unit 242.

The selection unit 241 receives the ignition signal 81 from the ignition switch 8. When the received ignition signal 81 is turned off, the selection unit 241 receives the voltage measurement values E1 and E2 from the voltage acquisition unit 22, and receives the temperature measurement value T1 from the temperature acquisition unit 23.

The selection unit 241 selects one of the voltage change tables 31 and 32 stored in the storage unit 26 based on the received voltage measurement values E1 and E2. The selection unit 241 selects the voltage change data corresponding to the received voltage measurement values E1 and E2 and the received temperature measurement value T1 from the plurality of voltage change data recorded in the selected voltage change table. The selection unit 241 supplies the selected voltage change data as the selection data 35 to the specific unit 242.

The specific unit 242 receives the selection data 35 from the selection unit 241 and specifies the open circuit voltage Es of the secondary battery 5 at the power-off time based on the received selection data. The identification unit 242 outputs the obtained open circuit voltage Es to the charge state estimation unit 25.

[5. Operation of state estimation device 20]
[5.1. When the ignition signal 81 is on]
With reference to FIG. 2, when the ignition signal 81 is on, the state estimation device 20 estimates the SOC value 11 of the secondary battery 5 based on the current measurement value Io supplied from the current sensor 7A.

Specifically, when the ignition signal 81 is turned on, the charging state estimation unit 25 reads out the corrected SOC value 12 stored in the storage unit 26. During the period when the ignition signal 81 is on, the current acquisition unit 21 acquires the current measurement value Io from the current sensor 7A at a frequency of 100 times per second, and transfers the acquired current measurement value Io to the charging state estimation unit 25. Supply.

Each time the charging state estimation unit 25 receives the current measurement value Io from the current acquisition unit 21, the charging state estimation unit 25 repeats the process of adding the received current measurement value Io to the current cumulative value. The current cumulative value is updated every time the charge state estimation unit 25 receives the current measurement value Io.

The charge state estimation unit 25 calculates the SOC change amount by dividing the updated current cumulative value by the full charge capacity of the secondary battery 5. The charging state estimation unit 25 calculates the SOC value 11 at the time when the current measurement value Io is acquired by adding the calculated SOC change amount to the corrected SOC value 12 read from the storage unit 26. The calculated SOC value 11 is stored in the storage unit 26.

If the charging state estimation unit 25 can calculate the SOC value 11 based on the current flowing through the secondary battery 5 during the period when the ignition signal 81 is on, the algorithm for calculating the SOC value 11 is particularly suitable. Not limited. Further, when the voltage measurement value Eo is within a preset range, the charge state estimation unit 25 has an SOC value based on the voltage measurement value and the SOC-CCV (Closed Circuit Voltage) characteristic of the secondary battery 5. 11 may be determined.

[5.2. When the ignition signal 81 is turned off]
[5.2.1. Estimating SOC value 11 based on open circuit voltage Es]
FIG. 4 is a flowchart showing the operation of the state estimation device 20 after the ignition signal 81 is turned off. When the ignition signal 81 changes from on to off, the state estimation device 20 starts the process shown in FIG.

With reference to FIG. 4, the voltage acquisition unit 22 acquires the voltage measurement value Eo at the power-off time from the voltage sensor 7B as the voltage measurement value E1 (step S1). The voltage acquisition unit 22 supplies the voltage measurement value E1 acquired in step S1 to the selection unit 241.

The temperature acquisition unit 23 acquires the temperature measurement value To at the power-off time as the temperature measurement value T1 from the temperature sensor 7C (step S2). The temperature acquisition unit 23 supplies the temperature measurement value T1 acquired in step S2 to the selection unit 241.

The voltage acquisition unit 22 waits until a preset standby time elapses from the power-off time (Yes in step S3). When the current time is the standby end time when the standby time has elapsed from the power off time (Yes in step S3), the voltage acquisition unit 22 sets the voltage measurement value Eo at the standby end time as the voltage measurement value E2 and sets the voltage sensor. Obtained from 7B (step S4). The voltage acquisition unit 22 supplies the voltage measurement value E2 acquired in step S4 to the selection unit 241.

The selection unit 241 of the voltage change tables 31 and 32 stored in the storage unit 26 based on the temperature measurement values T1 received from the temperature acquisition unit 23 and the voltage measurement values E1 and E2 received from the voltage acquisition unit 22. A voltage change table used to specify the open circuit voltage of the secondary battery 5 is selected from the above (step S5).

Specifically, the selection unit 241 compares the voltage measurement value E1 with the voltage measurement value E2. When the voltage measurement value E1 is lower than the voltage measurement value E2, the selection unit 241 determines that the secondary battery 5 has been discharged before the power-off time, and selects the voltage change table 31. This is because the voltage change table 31 includes the terminal voltage change data 321 that records the time change of the terminal voltage after the secondary battery 5 stops discharging. When the voltage measurement value E2 is higher than the voltage measurement value E2, the selection unit 241 determines that the secondary battery 5 was charged immediately before the power-off time, and selects the voltage change table 32. This is because the voltage change table 32 includes the terminal voltage change data 321 that records the time change of the terminal voltage after the secondary battery 5 stops charging.

The selection unit 241 receives the voltage measurement values E1 and E2 received from the voltage acquisition unit 22 and the temperature measurement values received from the temperature acquisition unit 23 from the terminal voltage change data included in the voltage change table selected in step S5. The terminal voltage change data corresponding to T1 is selected (step S6). The selection unit 241 outputs the terminal voltage change data selected in step S6 to the specific unit 242 as selection data 35.

The specifying unit 242 receives the selection data 35 from the selection unit 241 and specifies the open circuit voltage Es of the secondary battery 5 at the power-off time based on the received selection data 35 (step S7). The specific unit 242 outputs the specified open circuit voltage Es to the charge state estimation unit 25. In this way, the state estimation device 20 estimates the open circuit voltage Es more quickly by specifying the open circuit voltage Es based on the terminal voltage change data selected from the plurality of terminal voltage change data created in advance. it can.

Steps S5 to S7 will be described in detail later depending on whether the secondary battery 5 has been discharged or charged before the ignition signal 81 is turned off.

When the charging state estimation unit 25 receives the specified open circuit voltage Es from the specific unit 242 and receives the temperature measurement value T1 acquired in step S2 from the temperature acquisition unit 23, the charging state estimation unit 25 reads the SOC determination data 33 from the storage unit 26. The charging state estimation unit 25 determines the corrected SOC value 12 based on the received open circuit voltage Es, the received temperature measurement value T1, and the read SOC determination data 33 (step S8). The corrected SOC value 12 is the SOC value 11 of the secondary battery 5 at the time when the power is turned off.

The SOC determination data 33 records a plurality of curves, each of which indicates the SOC-OCV characteristics of the secondary battery 5. Each of the plurality of curves corresponds to the temperature of the secondary battery 5. The charging state estimation unit 25 identifies a curve corresponding to the temperature measurement value T1 received from the temperature acquisition unit 23 from among the plurality of curves. The charging state estimation unit 25 determines the corrected SOC value 12 based on the specified curve and the open circuit voltage Es received from the specific unit 242. Each of the plurality of curves may be specified by a numerical value that specifies each curve, or may be specified by a mathematical formula that indicates each curve. The algorithm in step S8 is not limited to the above as long as the charging state estimation unit 25 can determine the SOC value 11 of the secondary battery 5 based on the open circuit voltage Es of the secondary battery 5.

The charging state estimation unit 25 corrects the SOC value 11 by replacing the SOC value 11 stored in the storage unit 26 with the corrected SOC value 12 determined in step S8. After that, the state estimation device 20 ends the process shown in FIG. The SOC value 11 stored in the storage unit 26 is then used to estimate the SOC value 11 of the secondary battery 5 after the ignition signal 81 is turned on.

[When the 5.2.2.2 secondary battery 5 is discharged]
The operation of the state estimation device 20 when the secondary battery 5 is discharged before the ignition signal 81 is turned off will be described in detail.

(Acquisition of measured values)
FIG. 5 is a diagram showing an example of a time change of the terminal voltage of the secondary battery 5 when the secondary battery 5 is discharged before the ignition signal 81 is turned off. With reference to FIG. 5, the ignition signal 81 is off in the period prior to time t11. The terminal voltage of the secondary battery 5 maintains the measured voltage value E8 in the period before the time t11.

When the ignition signal 81 is turned on at time t11, the secondary battery 5 starts discharging, for example, to supply electric power to the vehicle equipped with the in-vehicle system 100. During the period from time t11 to time t12, the secondary battery 5 continues to discharge, so that the terminal voltage of the secondary battery 5 decreases.

The ignition signal 81 is turned off at time t12. Since the time t12 is the power off time, the voltage acquisition unit 22 acquires the voltage measurement value Eo at the time t12 as the voltage measurement value E1 (step S1 shown in FIG. 4). The temperature acquisition unit 23 acquires the temperature measurement value To at the time t12 as the temperature measurement value T1 (step S2 shown in FIG. 4).

The state estimation device 20 waits until the preset standby time Tw elapses from the time t12 (Yes in step S3 shown in FIG. 4). The standby time Tw is, for example, 1 minute. The time t13 is the waiting end time when the waiting time Tw has elapsed from the time t12. When the current time is the standby end time (time t13), the voltage acquisition unit 22 acquires the voltage measurement value Eo at the time t13 as the voltage measurement value E2 (step S4 shown in FIG. 4).

(Selection of voltage change table)
The selection unit 241 selects one of the voltage change tables 31 and 32 stored in the storage unit 26 (step S5 shown in FIG. 4). The voltage change table 31 shows the change in the terminal voltage of the secondary battery 5 when the secondary battery 5 is discharged before the ignition signal 81 is turned off. The voltage change table 32 shows the change in the terminal voltage of the secondary battery 5 when the secondary battery 5 is charged before the ignition signal 81 is turned off.

The secondary battery 5 is discharged before the ignition signal 81 is turned off at time t12. In the secondary battery 5, the transition from the non-equilibrium state at the time of discharge to the equilibrium state at the time of opening starts at time t12. As a result, as shown in FIG. 5, the terminal voltage of the secondary battery 5 continues to increase in the period after the time t12.

As shown in FIG. 5, since the voltage measurement value E1 is lower than the voltage measurement value E2, the selection unit 241 determines that the secondary battery 5 has been discharged before the ignition signal 81 is turned off. The selection unit 241 selects the voltage change table 31 in step S5 shown in FIG.

(Selection of terminal voltage change data 311)
The selection unit 241 selects the temperature measurement value T1 and the terminal voltage change data 311 corresponding to the voltage measurement values E1 and E2 from the terminal voltage change data 311 included in the selected voltage change table 31 (FIG. 4). Step S6) shown in.

FIG. 6 is a diagram showing an example of the voltage change table 31 shown in FIG. With reference to FIG. 6, each of the terminal voltage change data 311a to 311f is data for one row of the voltage change table 31. Each of the terminal voltage change data 311a to 311f records the temperature, the first voltage, the second voltage, and the open circuit voltage.

The temperature is the temperature of the secondary battery 5 when the discharge of the secondary battery 5 is stopped. The first voltage is the terminal voltage of the secondary battery 5 when the discharge of the secondary battery 5 is stopped. The second voltage is the terminal voltage of the secondary battery 5 at the standby end time. The open circuit voltage is the terminal voltage after a predetermined time has elapsed since the secondary battery 5 stopped discharging. The predetermined time is the time from when the secondary battery 5 stops discharging until the internal state of the secondary battery 5 becomes equilibrium. Therefore, the predetermined time is longer than the standby time Tw, and is preferably a time of, for example, 2 hours or more. In the terminal voltage change data, the standby end time is the time when the standby time Tw has elapsed since the discharge was stopped. The voltage change table 31 may include various terminal voltage change data 311 in addition to the terminal voltage change data 311a to 311f shown in FIG.

It is assumed that the temperature measurement value T1 acquired by the temperature acquisition unit 23 is 15 ° C., and the voltage measurement values E1 and 2 acquired by the voltage acquisition unit 22 are E1q (V) and E2q (V). In this case, the selection unit 241 selects the terminal voltage change data 311f included in the voltage change table 31. The selection unit 241 outputs the selected terminal voltage change data 311f as the selection data 35 to the specific unit 242.

The voltage measurement values E1 and E2 acquired by the voltage acquisition unit 22 may not match the first voltage and the second voltage recorded in the terminal voltage change data 311. In this case, the selection unit 241 specifies a plurality of terminal voltage change data 311 corresponding to the temperature measurement value T1 acquired by the temperature acquisition unit 23 from the voltage change table 31. When the temperature measurement value T1 acquired by the temperature acquisition unit 23 is 14 ° C., the selection unit 241 identifies the terminal voltage change data 311a to 311c.

The selection unit 241 selects any one from the specified terminal voltage change data 311 based on at least one of the voltage measurement values E1 and E2 acquired by the voltage acquisition unit 22. For example, the selection unit 241 may select the terminal voltage change data 311 that records the first voltage closest to the acquired voltage measurement value E1, or may select the second voltage closest to the acquired voltage measurement value E2. The terminal voltage change data 311 to be recorded may be selected.

Alternatively, the selection unit 241 has the terminal voltage change having the smallest average of the subtracted value obtained by subtracting the acquired voltage measured value E1 from the first voltage and the subtracted value obtained by subtracting the acquired voltage measured value E2 from the second voltage. Data 311 may be selected. The selection unit 241 may select the terminal voltage change data 311 having the smallest sum of the absolute values of the two calculated subtraction values.

(Specification of open circuit voltage)
The specific unit 242 receives the terminal voltage change data 311f as the selection data 35 from the selection unit 241. The identification unit 242 specifies the open circuit voltage recorded in the received terminal voltage change data 311f as the open circuit voltage Es of the secondary battery 5 at the power off time (step S7 shown in FIG. 4). In the example shown in FIG. 5, the identification unit 242 specifies the open circuit voltage Es of the secondary battery 5 at time t12 based on the selection data 35.

Hereinafter, the generation of the terminal voltage change data 311 will be described. The terminal voltage change data 311 is generated by measuring in advance the time change of the terminal voltage after the secondary battery has stopped discharging. For example, the discharge of the secondary battery 5 is stopped while maintaining the temperature of the secondary battery 5 at 14 ° C. The terminal voltage at the discharge stop time is recorded as the first voltage of the terminal voltage change data 311. The terminal voltage at the time when the standby time Tw has elapsed from the discharge stop time is recorded as the second voltage. The terminal voltage when the secondary battery 5 is in the equilibrium state is recorded as the OCV of the terminal voltage change data 311. The time when the secondary battery 5 is in the equilibrium state is specifically the terminal voltage of the secondary battery 5 at the time when the above-mentioned predetermined time has elapsed from the discharge stop time.

Various terminal voltage change data 311 is generated by measuring the terminal voltage when the discharge is stopped, the terminal voltage at the standby end time, and the terminal voltage when the secondary battery 5 is in the balanced state under various measurement conditions. be able to.

For example, the measurement conditions can be changed by changing the temperature of the secondary battery 5. This is because the time change of the terminal voltage after the secondary battery 5 stops discharging depends on the temperature of the secondary battery 5. Alternatively, the measurement conditions can be changed by changing the terminal voltage when the discharge is stopped. This is because the time change of the terminal voltage after the secondary battery 5 stops discharging depends on the terminal voltage when discharging is stopped.

[When the secondary battery 5 is charged]
The operation of the state estimation device 20 when the secondary battery 5 is charged before the ignition signal 81 is turned off will be described in detail.

(Acquisition of measured values)
FIG. 7 is a diagram showing an example of a time change of the terminal voltage of the secondary battery 5 when the secondary battery 5 is charged before the ignition signal 81 is turned off. With reference to FIG. 7, the ignition signal 81 is off in the period prior to time t21. The terminal voltage of the secondary battery 5 maintains the measured voltage value E9 in the period before the time t21.

After the ignition signal 81 is turned on at time t21, the secondary battery 5 starts charging with, for example, the electric power received from the motor generator 4. As a result, the terminal voltage of the secondary battery 5 continues to increase during the period from time t21 to time t22.

The terminal voltage of the secondary battery 5 may temporarily decrease during the period from time t21 to time t22, but FIG. 7 omits the temporary decrease in terminal voltage. The temporary drop in terminal voltage is generated, for example, by the secondary battery 5 supplying power to the motor generator 4 to start the vehicle engine at time t21.

The ignition signal 81 is turned off at time t22. Since the time t22 is the power-off time, the voltage acquisition unit 22 acquires the voltage measurement value Eo at the time t22 as the voltage measurement value E1 (step S1 shown in FIG. 4). The temperature acquisition unit 23 acquires the temperature measurement value To at the time t22 as the temperature measurement value T1 (step S2 shown in FIG. 4).

The state estimation device 20 waits until the time t23, which is the standby end time (Yes in step S3 shown in FIG. 4). The time t23 is the time when the waiting time Tw has elapsed from the time t22. The voltage acquisition unit 22 acquires the voltage measurement value Eo at time t23 as the voltage measurement value E2 (step S4 shown in FIG. 4).

(Selection of voltage change table)
Since the secondary battery 5 is discharged before the time t22, the secondary battery 5 shifts from the non-equilibrium state at the time of charging to the equilibrium state at the time of opening. As shown in FIG. 5, the terminal voltage of the secondary battery 5 continuously decreases in a period after the time t12.

As shown in FIG. 7, since the voltage measurement value E1 acquired at time t22 is higher than the voltage measurement value E2 acquired at time t23, the selection unit 241 is charging the secondary battery before time t22. It is judged that it was. The selection unit 241 selects the voltage change table 32 based on the determination result (step S5 shown in FIG. 4). This is because the voltage change table 32 shows the change in the terminal voltage of the secondary battery 5 when the secondary battery 5 is charged before the ignition signal 81 is turned off.

(Selection of terminal voltage change data)
The selection unit 241 selects the temperature measurement value T1 and the terminal voltage change data 321 corresponding to the voltage measurement values E1 and E2 from the terminal voltage change data 321 included in the selected voltage change table 32 (FIG. 4). Step S6) shown in.

FIG. 8 is a diagram showing an example of the voltage change table 32 shown in FIG. With reference to FIG. 7, the terminal voltage change data 321a to 321f are data for one row of the voltage change table 32. Each of the terminal voltage change data 321a to 321f records the temperature, the first voltage, the second voltage, and the open circuit voltage of the secondary battery 5 in the same manner as the terminal voltage change data 311. The voltage change table 32 may include various terminal voltage change data 321 in addition to the terminal voltage change data 321a to 321f shown in FIG.

It is assumed that the temperature measurement value T1 acquired by the temperature acquisition unit 23 is 14 ° C., and the voltage measurement values E1 and E2 acquired by the voltage acquisition unit 22 are E1m (V) and E2m (V). In this case, the selection unit 241 selects the terminal voltage change data 321b included in the voltage change table 32. The selection unit 241 outputs the selected terminal voltage change data 321b as the selection data 35 to the specific unit 242.

Since the operation of the selection unit 241 when the acquired voltage measurement values E1 and E2 do not match the first voltage and the second voltage recorded in the terminal voltage change data 321 is the same as the above, the description thereof is omitted. To do.

(Specification of open circuit voltage)
The specific unit 242 receives the terminal voltage change data 321b as the selection data 35 from the selection unit 241. The identification unit 242 specifies the open circuit voltage recorded in the received terminal voltage change data 321b as the open circuit voltage Es of the secondary battery 5 at time t22 (power off time) (step S7 shown in FIG. 4).

Hereinafter, the generation of the terminal voltage change data 321 will be described. The terminal voltage change data 321 is generated by measuring in advance the change in the terminal voltage after the secondary battery has stopped charging. For example, the discharge of the secondary battery 5 is stopped while maintaining the temperature of the secondary battery 5 at 14 ° C. After that, the terminal voltage change data 321 can be generated by measuring the first voltage, the second voltage, and the OCV. Since the generation of the terminal voltage change data 321 is the same as the generation of the terminal voltage change data 311, detailed description thereof will be omitted.

As described above, when the ignition signal 81 is turned off, the state estimation device 20 estimates the open circuit voltage of the secondary battery 5 based on the voltage measurement value E1 at the power-off time and the voltage measurement value E2 at the standby end time. To do. Since the state estimation device 20 can quickly estimate the open circuit voltage of the secondary battery 5, it is possible to increase the chances of correcting the SOC value 11 based on the estimated open circuit voltage. As a result, the state estimation device 20 can suppress the error of the SOC value 11.

Further, the voltage estimation unit 24 estimates the open circuit voltage Es of the secondary battery 5 in consideration of the temperature of the secondary battery 5 at the time when the power is turned off. Thereby, the estimation accuracy of the open circuit voltage Es of the secondary battery 5 can be improved.

In the above embodiment, an example in which the state estimation device 20 estimates the open circuit voltage Es of the secondary battery 5 using the temperature measurement value T1 has been described. However, the state estimation device 20 does not have to use the temperature measurement value T1 when estimating the open circuit voltage Es. The state estimation device 20 estimates the open circuit voltage Es using the voltage change tables 31 and 32 having no temperature column. Even in this case, the open circuit voltage Es of the secondary battery 5 can be quickly estimated.

In the above embodiment, an example of determining whether or not the state estimation device 20 is charging before the ignition signal 81 is turned off has been described based on the result of comparing the voltage measurement value E1 with the voltage measurement value E2. However, when the ignition signal 81 is turned off, the state estimation device 20 determines whether or not charging is performed before the ignition signal 81 is turned off, based on the current measurement value Io acquired before the power off time. You may.

In the above embodiment, an example in which the state estimation device 20 acquires the voltage measurement value Eo at the power-off time as the voltage measurement value E1 has been described, but the present invention is not limited to this. The state estimation device 20 may acquire the voltage measurement value Eo at the time when the current flowing through the secondary battery 5 becomes zero as the voltage measurement value E1. In this case, the state estimation device 20 may acquire the voltage measurement value E2 at the time when the standby time elapses from the time when the current flowing through the secondary battery 5 becomes zero.

For example, the state estimation device 20 may determine whether or not the current flowing through the secondary battery 5 becomes zero based on the state of the relay 6. The state estimation device 20 acquires the voltage measurement value Eo at the time when the relay 6 is turned off as the voltage measurement value E1. When the relay 6 is turned off, the secondary battery 5 is in an open state. As a result, the current flowing through the secondary battery 5 becomes zero.

Further, in the above embodiment, each functional block of the state estimation device 20 may be individually integrated into one chip by a semiconductor device such as an LSI, or may be integrated into one chip so as to include a part or all of them. .. Although it is referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

The method of making an integrated circuit is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection and settings of circuit cells inside the LSI may be used.

Further, a part or all of the processing executed by the state estimation device 20 may be realized by a program. Then, a part or all of the processing of each functional block of each of the above embodiments is performed by the central processing unit (CPU) in the computer. Further, the program for performing each process is stored in a storage device such as a hard disk or a ROM, and is read and executed in the ROM or the RAM.

Further, each process of the above embodiment may be realized by hardware, or may be realized by software (including a case where it is realized together with an OS (operating system), middleware, or a predetermined library). .. Further, it may be realized by mixed processing of software and hardware.

For example, when each functional block of the state estimation device 20 is realized by software, the hardware configuration shown in FIG. 11 (for example, the hardware configuration in which the CPU, ROM, RAM, input unit, output unit, etc. are connected by the bus Bus) ) May be used to realize each functional unit by software processing.

Further, the execution order of the processing methods in the above-described embodiment is not limited to the description of the above-described embodiment, and the execution order may be changed without departing from the gist of the invention.

A computer program that causes a computer to perform the above-mentioned method and a computer-readable recording medium that records the program are included in the scope of the present invention. Here, examples of computer-readable recording media include flexible disks, hard disks, CD-ROMs, MOs, DVDs, DVD-ROMs, DVD-RAMs, large-capacity DVDs, next-generation DVDs, and semiconductor memories. ..

Although the embodiment of the present invention has been described above, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented within a range that does not deviate from the gist thereof.

100 In-vehicle system 1 Power supply management device 2 Vehicle control device 3 Conversion unit 4 Motor generator 5 Secondary battery 7A Current sensor 7B Voltage sensor 7C Temperature sensor 20 State estimation device 21 Current acquisition unit 22 Voltage acquisition unit 23 Temperature acquisition unit 24 Voltage estimation unit 25 Charging state estimation unit 26 Storage unit 241 Selection unit 242 Specific unit

Claims (4)

The first voltage measurement at the first time when the current flowing through the secondary battery becomes zero from the voltage sensor that measures the terminal voltage, which is the voltage between the positive terminal of the secondary battery and the negative terminal of the secondary electron. A voltage acquisition unit that acquires a value and a second voltage measurement value at a second time when a predetermined standby time has elapsed from the first time.
Voltage estimation that estimates the open circuit voltage of the secondary battery at the first time based on the first voltage measurement value acquired by the voltage acquisition unit and the second voltage measurement value acquired by the voltage acquisition unit. Department and
A state estimation device including a charge state estimation unit that estimates the charge state of the secondary battery based on the open circuit voltage estimated by the voltage estimation unit. The state estimation device according to claim 1, further
A temperature acquisition unit for acquiring a temperature measurement value from a temperature sensor for measuring the temperature of the secondary battery is provided.
The voltage estimation unit is a state estimation device that estimates the open circuit voltage based on a temperature measurement value acquired by the temperature acquisition unit. The state estimation device according to claim 1 or 2.
The voltage estimation unit
Corresponds to the acquired first voltage measurement value and second voltage measurement value from a plurality of terminal voltage change data indicating the time change of the open circuit voltage of the secondary battery after the power of the device is turned off. Terminal voltage change data to be selected
A state estimation device including a specific unit that specifies the open circuit voltage of the secondary battery at the first time with reference to the voltage change data selected by the selection unit. The first voltage measurement at the first time when the current flowing through the secondary battery becomes zero from the voltage sensor that measures the terminal voltage, which is the voltage between the positive terminal of the secondary battery and the negative terminal of the secondary electron. A step of acquiring the value and the second voltage measurement value at the second time when a predetermined standby time has elapsed from the first time, and
A step of estimating the open circuit voltage of the secondary battery at the first time based on the acquired first voltage measurement value and the acquired second voltage measurement value.
A state estimation method including a step of estimating the charge state of the secondary battery based on the estimated open circuit voltage.

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