JP7295658B2 - state estimator - Google Patents

Description

The present invention relates to a state estimation device for estimating the state of charge of a secondary battery.

2. Description of the Related Art Electric vehicles such as hybrid vehicles and electric vehicles are equipped with a power supply 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 power to the motor by discharging, and accumulates regenerated power generated by the motor by charging.

An electric vehicle is equipped with a state estimating 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 values.

Since the current measurements are erroneous, the errors in the current measurements accumulate in the estimated SOC value. That is, the error in the estimated SOC value increases over time. As the error in the estimated SOC value increases, over-discharging or over-charging may occur in the secondary battery.

In order to maintain the accuracy of the SOC value estimated using the integrated value of the current measurement value, the state estimation device uses the SOC value estimated using the integrated value as the OCV (Open Circuit Voltage) of the secondary battery. corrected using 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 preset SOC-OCV characteristics of the secondary battery. The state estimator uses the SOC value identified using the OCV to correct the SOC value estimated using the current measurements.

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

Patent Literature 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 estimation device periodically measures the current flowing through the secondary battery, the terminal voltage of the secondary battery, and the temperature of the secondary battery. If the elapsed time since the ignition switch was turned off is 2 hours or more and less than 6 hours, the battery state estimation device secondary 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 two hours have passed since the ignition switch was turned off. Since there are few opportunities to correct the SOC value estimated using the current measurement value, the battery state estimation device cannot suppress errors in the SOC value estimated using the current measurement value.

JP 2017-129402 A

SUMMARY OF THE INVENTION 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 a secondary battery.

In order to solve the above problems, a first invention is a state estimating device that includes a voltage acquiring section, a voltage estimating section, and a state of charge estimating section. A voltage acquisition unit detects a terminal voltage, which is a voltage between a positive terminal of a secondary battery and a negative terminal of secondary electrons, from a voltage sensor that measures a terminal voltage, which is a voltage between a positive terminal of the secondary battery and a negative terminal of secondary electrons, and obtains a first time when the power of the device in which the secondary battery is mounted is turned off. and a second voltage measurement value at a second time after a predetermined waiting time has elapsed from the first time. The voltage estimator estimates an open-circuit voltage of the secondary battery at a 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 state-of-charge estimator estimates the state of charge of the secondary battery based on the open-circuit voltage estimated by the voltage estimator.

According to the first invention, the voltage estimating unit 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 after the standby time has elapsed from the first time. to estimate the open-circuit voltage of the secondary battery. The first invention can shorten the time for estimating the open-circuit voltage of the secondary battery, so that the chances of estimating the SOC value based on the open-circuit voltage can be increased, so the error in the SOC value of the secondary battery can be suppressed. .

A second invention is the first invention, further comprising 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 estimator estimates the open-circuit voltage based on the temperature measurement value acquired by the temperature acquirer.

According to the second invention, the temperature of the secondary battery is considered 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.

A third invention is the first or second invention, wherein the voltage estimation unit includes a selection unit and a specification unit. The selection unit corresponds to the first voltage measurement value and the second voltage measurement value acquired from among a plurality of voltage change data indicating the time change of the open-circuit voltage of the secondary battery after the power supply of the device is turned off. Select the voltage change data to be used. The identifying unit refers to the voltage change data selected by the selecting unit and identifies the open-circuit voltage of the secondary battery at the first time.

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

A fourth invention is a state estimation method comprising a) step, b) step, and c) step. In step a), a voltage sensor that measures a terminal voltage, which is the voltage between the positive terminal of the secondary battery and the negative terminal of the secondary electron, detects a first time when the power of the device in which the secondary battery is mounted is turned off. and a second voltage measurement value at a second time after a predetermined waiting time has elapsed from the first time. The b) step estimates an open-circuit voltage of the secondary battery at a first time based on the obtained first voltage measurement value and the obtained second voltage measurement value. The c) step estimates the state of charge of the secondary battery based on the estimated open-circuit voltage.

A fourth invention is used for the first invention.

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

BRIEF DESCRIPTION OF THE DRAWINGS It is a functional block diagram which shows the structure of an in-vehicle system provided with the state estimation apparatus which concerns on embodiment of this invention. 2 is a functional block diagram showing the configuration of the state estimation device shown in FIG. 1; FIG. 3 is a functional block diagram showing the configuration of a voltage estimator shown in FIG. 2; FIG. 2 is a flowchart showing the operation of the state estimation device shown in FIG. 1; FIG. 2 is a diagram showing temporal changes in terminal voltage when the secondary battery shown in FIG. 1 is discharged before an ignition signal is turned off; 3 is a diagram showing an example of a voltage change table shown in FIG. 2; FIG. FIG. 2 is a diagram showing temporal changes in terminal voltage when the secondary battery shown in FIG. 1 is being charged before an ignition signal is turned off; 3 is a diagram showing another example of the voltage change table shown in FIG. 2; FIG. FIG. 2 is a diagram showing a CPU bus configuration; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same reference numerals are given to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

[1. Configuration of in-vehicle system 100]
FIG. 1 is a functional block diagram showing the configuration of an in-vehicle system 100 including a state estimation device 20 according to an embodiment of the invention. Referring to FIG. 1, an in-vehicle system 100 is mounted in a vehicle such as a hybrid electric vehicle (HEV) (not shown). The in-vehicle system 100 supplies power from the secondary battery 5 to the motor generator 4 and supplies regenerated 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 converter 3 is connected to the secondary battery 5 , the power management device 1 calculates an SOC (state of charge) value 11 . The power supply management device 1 outputs the calculated SOC value 11 to the vehicle control device 2 as the estimation result of the SOC of the secondary battery 5 .

The SOC value 11 indicates the charging rate of the secondary battery 5 in this embodiment. Alternatively, the SOC value 11 may be the remaining 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 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 converter 3 converts direct current supplied from the secondary battery 5 into three-phase alternating current in accordance with an instruction from the vehicle control device 2 . The motor generator 4 is driven by the converted three-phase alternating current to start the engine of the electric vehicle (not shown).

When the vehicle control device 2 performs charging control, the conversion unit 3 converts the three-phase alternating current supplied from the motor generator 4 into direct current according to an instruction from the vehicle control device 2 . For example, the motor generator 4 generates a 3-phase alternating current when operating as a regenerative brake, and supplies the generated 3-phase alternating current to the conversion unit 3 . Further, the motor generator 4 generates power by driving force of an engine of an electric vehicle (not shown) to generate a 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 multiple battery stacks includes multiple cells connected in series. The cell is, for example, a lithium-ion secondary battery or a nickel-metal hydride 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 converter 3 . By turning off the relay 6, the electrical connection between the converter 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 terminal and the negative terminal of the secondary battery 5 . The voltage sensor 7</b>B 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 7</b>C 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 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, relay control device 10 turns on relay 6 to electrically connect secondary battery 5 to 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 disconnect the electrical connection between the conversion unit 3 and the secondary battery 5 .

State estimation device 20 estimates the state of 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 state estimation device 20 shown in FIG. Referring to FIG. 2 , 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 state of charge 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 state of charge 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 section 22 supplies the acquired voltage measurement values E1 and E2 to the voltage estimation section 24 . The power off time is the time when the ignition signal 81 changes from on to off. The standby end time is the time when a preset standby time has elapsed since 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 state of charge estimation unit 25 . Specifically, the temperature acquisition unit 23 acquires a temperature measurement value T1 that indicates the temperature of the secondary battery 5 at the power-off time.

Voltage estimation unit 24 receives voltage measurement values E1 and E2 from voltage acquisition unit 22 and temperature measurement value T1 from temperature acquisition unit 23 . When the ignition signal 81 supplied from the ignition switch 8 is turned off, the voltage estimating unit 24 calculates the voltage estimator 24 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 secondary battery 5 is estimated. The voltage estimator 24 supplies the estimated open-circuit voltage Es to the state-of-charge estimator 25 . The configuration of the voltage estimator 24 will be described later.

The state-of-charge estimation unit 25 receives the current measurement value Io from the voltage acquisition unit 22 while the ignition signal 81 is on. The state-of-charge estimator 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 state-of-charge estimator 25 outputs the SOC value 11 to the vehicle control device 2 as an estimation result of the state of charge of the secondary battery. Also, the state-of-charge estimation unit 25 corrects the SOC11 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 voltage change tables 31 and 32, SOC determination data 33, and correction SOC value 12. FIG.

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

The voltage change table 32 shows temporal changes in the terminal voltage when the secondary battery 5 is charged before the ignition signal 81 is turned off. The voltage change table 32 includes multiple terminal voltage change data 321 . Each of the plurality of terminal voltage change data 321 records changes in 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 . Corrected SOC value 11 is SOC value 11 corrected by state-of-charge estimator 25 .

[4. Configuration of Voltage Estimating Unit 24]
FIG. 3 is a functional block diagram showing the configuration of voltage estimator 24 shown in FIG. Referring to FIG. 3 , voltage estimating portion 24 includes a selecting portion 241 and a specifying portion 242 .

Selector 241 receives ignition signal 81 from ignition switch 8 . When the received ignition signal 81 turns 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 voltage change data corresponding to the received voltage measurement values E1 and E2 and the received temperature measurement value T1 from a 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 identification unit 242 .

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

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

Specifically, when the ignition signal 81 is turned on, the state-of-charge estimation unit 25 reads 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 sends the acquired current measurement value Io to the state of charge estimation unit 25. supply.

Each time the state-of-charge estimation unit 25 receives the measured current value Io from the current acquisition unit 21, it repeats the process of adding the received measured current value Io to the accumulated current value. The accumulated current value is updated each time state-of-charge estimator 25 receives a current measurement value Io.

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

Note that if the state-of-charge estimation unit 25 can calculate the SOC value 11 based on the current flowing through the secondary battery 5 while the ignition signal 81 is on, the algorithm for calculating the SOC value 11 is particularly Not limited. Further, when the voltage measurement value Eo is within a preset range, the state-of-charge estimation unit 25 calculates the SOC value based on the voltage measurement value and the SOC-CCV (Closed Circuit Voltage) characteristics of the secondary battery 5. 11 may be determined.

[5.2. When the ignition signal 81 is turned off]
[5.2.1. Estimation of SOC value 11 based on open-circuit voltage Es]
FIG. 4 is a flow chart showing the operation of the state estimation device 20 after the ignition signal 81 is turned off. The state estimation device 20 starts the processing shown in FIG. 4 when the ignition signal 81 changes from ON to OFF.

Referring to FIG. 4, voltage acquisition unit 22 acquires voltage measurement value Eo at the power-off time from voltage sensor 7B as 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 from the temperature sensor 7C as the temperature measurement value T1 (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 waiting time elapses from the power-off time (Yes in step S3). If the current time is the standby end time after the standby time has elapsed from the power-off time (Yes in step S3), the voltage acquisition unit 22 takes the voltage measurement value Eo at the standby end time as the voltage measurement value E2 from the voltage sensor. 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 selects voltage change tables 31 and 32 stored in the storage unit 26 based on the temperature measurement value 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 for specifying the open-circuit voltage of the secondary battery 5 is selected from among them (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 was 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 selects the voltage measurement values E1 and E2 received from the voltage acquisition unit 22 and the temperature measurement value received from the temperature acquisition unit 23 from among the terminal voltage change data included in the voltage change table selected in step S5. Terminal voltage change data corresponding to T1 is selected (step S6). The selection unit 241 outputs the terminal voltage change data selected in step S<b>6 to the identification unit 242 as the selection data 35 .

The identification unit 242 receives the selection data 35 from the selection unit 241, and identifies 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 identifying unit 242 outputs the identified open-circuit voltage Es to the state-of-charge estimating unit 25 . In this way, the state estimating device 20 more quickly estimates the open-circuit voltage Es by specifying the open-circuit voltage Es based on the terminal voltage change data selected from a plurality of terminal voltage change data created in advance. can.

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

State-of-charge estimating unit 25 reads out SOC determination data 33 from storage unit 26 when receiving specified open-circuit voltage Es from specifying unit 242 and temperature measurement value T1 acquired in step S2 from temperature acquiring unit 23 . State-of-charge estimator 25 determines corrected SOC value 12 based on received open-circuit voltage Es, received temperature measurement value T1, and read SOC determination data 33 (step S8). The corrected SOC value 12 is the SOC value 11 of the secondary battery 5 at the power-off time.

The SOC determination data 33 records a plurality of curves each representing the SOC-OCV characteristics of the secondary battery 5 . Each of the plurality of curves corresponds to the temperature of secondary battery 5 . State of charge estimation unit 25 identifies a curve corresponding to temperature measurement value T1 received from temperature acquisition unit 23 from among the plurality of curves. State-of-charge estimating unit 25 determines corrected SOC value 12 based on the specified curve and open-circuit voltage Es received from specifying unit 242 . Each of the plurality of curves may be specified by a numerical value specifying each curve, or may be specified by a mathematical formula representing each curve. Note that if the state-of-charge 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 algorithm of step S8 is not limited to the above.

State of charge estimation unit 25 corrects SOC value 11 by replacing SOC value 11 stored in storage unit 26 with corrected SOC value 12 determined in step S8. After that, the state estimation device 20 ends the processing shown in FIG. The SOC value 11 stored in the storage unit 26 is used for estimating the SOC value 11 of the secondary battery 5 after the ignition signal 81 is next turned on.

[5.2.2. When 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.

(Obtaining measured values)
FIG. 5 is a diagram showing an example of temporal changes in the terminal voltage of the secondary battery 5 when the secondary battery 5 is discharged before the ignition signal 81 is turned off. Referring to FIG. 5, ignition signal 81 is off during a period prior to time t11. The terminal voltage of the secondary battery 5 maintains the voltage measurement value E8 during the period before time t11.

When the ignition signal 81 is turned on at time t11, the secondary battery 5 starts discharging, for example, in order to supply electric power to the vehicle in which the in-vehicle system 100 is mounted. During the period from time t11 to time t12, the secondary battery 5 continues discharging, so 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 time t12 as the temperature measurement value T1 (step S2 shown in FIG. 4).

State estimating device 20 waits from time t12 until preset waiting time Tw elapses (Yes in step S3 shown in FIG. 4). The waiting time Tw is, for example, 1 minute. Time t13 is the standby end time after the standby time Tw has passed from 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 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 changes 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 changes in the terminal voltage of the secondary battery 5 when the secondary battery 5 is being 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, transition from the unbalanced state during discharging to the balanced state during release starts at time t12. As a result, the terminal voltage of the secondary battery 5 continues to increase in the period after time t12, as shown in FIG.

As shown in FIG. 5, the voltage measurement value E1 is lower than the voltage measurement value E2, so the selector 241 determines that the secondary battery 5 was discharged before the ignition signal 81 was 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 terminal voltage change data 311 corresponding to the temperature measurement value T1 and the voltage measurement values E1 and E2 from among the terminal voltage change data 311 included in the selected voltage change table 31 (see FIG. 4). step S6).

FIG. 6 is a diagram showing an example of the voltage change table 31 shown in FIG. 2. As shown in FIG. 6, each of terminal voltage change data 311a to 311f is data for one row of voltage change table 31. In FIG. Each of the terminal voltage change data 311a-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 secondary battery 5 stops discharging. The first voltage is the terminal voltage of the secondary battery 5 when the secondary battery 5 stops discharging. 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 passed 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 reaches equilibrium. Therefore, the predetermined time is preferably longer than the standby time Tw, for example, two hours or longer. In the terminal voltage change data, the standby end time is the time when the standby time Tw has passed 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.

Assume 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 311 f included in the voltage change table 31 . The selection unit 241 outputs the selected terminal voltage change data 311 f to the identification unit 242 as the selection data 35 .

The voltage measurement values E<b>1 and E<b>2 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 identifies a plurality of terminal voltage change data 311 corresponding to the temperature measurement value T<b>1 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 one of 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 select the second voltage that is 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 selects a terminal voltage change in which the average of the subtraction value obtained by subtracting the obtained voltage measurement value E1 from the first voltage and the subtraction value obtained by subtracting the obtained voltage measurement value E2 from the second voltage is the smallest. Data 311 may be selected. The selection unit 241 may select the terminal voltage change data 311 with the smallest sum of the absolute values of the two calculated subtraction values.

(Specification of open-circuit voltage)
The specifying unit 242 receives the terminal voltage change data 311 f as the selection data 35 from the selection unit 241 . The identifying unit 242 identifies 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 identifying unit 242 identifies the open-circuit voltage Es of the secondary battery 5 at time t12 based on the selection data 35 .

Generation of the terminal voltage change data 311 will be described below. The terminal voltage change data 311 is generated by measuring in advance the time change of the terminal voltage after the secondary battery stops 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 equilibrium is recorded as the OCV of the terminal voltage change data 311 . Specifically, the time when the secondary battery 5 is in an equilibrium state is the terminal voltage of the secondary battery 5 at the time when the above-described predetermined time has elapsed from the discharge stop time.

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

For example, by changing the temperature of the secondary battery 5, the measurement conditions can be changed. This is because the temporal change in 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 temporal change in the terminal voltage after the secondary battery 5 stops discharging depends on the terminal voltage at the time of stopping discharging.

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

(Obtaining measured values)
FIG. 7 is a diagram showing an example of temporal changes in the terminal voltage of the secondary battery 5 when the secondary battery 5 is being charged before the ignition signal 81 is turned off. Referring to FIG. 7, ignition signal 81 is off during a period prior to time t21. The terminal voltage of the secondary battery 5 maintains the voltage measurement value E9 during the period before time t21.

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

Although the terminal voltage of the secondary battery 5 may temporarily drop during the period from time t21 to time t22, the temporary drop in the terminal voltage is omitted in FIG. A temporary drop in terminal voltage occurs, for example, when secondary battery 5 supplies electric power to motor generator 4 to start the engine of the vehicle 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 time t22 as the temperature measurement value T1 (step S2 shown in FIG. 4).

The state estimation device 20 waits until time t23, which is the standby end time (Yes in step S3 shown in FIG. 4). A time t23 is a time after the waiting time Tw has passed 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 has been discharged before time t22, it transitions from the unbalanced state during charging to the balanced state during release. As shown in FIG. 5, the terminal voltage of secondary battery 5 continues to decrease in a period after 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 determines that the secondary battery is being charged before time t22. It is judged that it was. The selection unit 241 selects the voltage change table 32 based on this determination result (step S5 shown in FIG. 4). This is because the voltage change table 32 shows changes in the terminal voltage of the secondary battery 5 when the secondary battery 5 is being charged before the ignition signal 81 is turned off.

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

FIG. 8 is a diagram showing an example of the voltage change table 32 shown in FIG. 2. As shown in FIG. Referring to FIG. 7, terminal voltage change data 321a to 321f are data for one row of voltage change table 32. FIG. As with the terminal voltage change data 311, 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. FIG. 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.

Assume 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. FIG. The selection unit 241 outputs the selected terminal voltage change data 321 b as the selection data 35 to the identification 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 described above, the description thereof is omitted. do.

(Specification of open-circuit voltage)
The specifying unit 242 receives the terminal voltage change data 321 b as the selection data 35 from the selection unit 241 . The identification unit 242 identifies 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).

Generation of the terminal voltage change data 321 will be described below. The terminal voltage change data 321 is generated by measuring in advance the change in terminal voltage after the secondary battery stops 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. The generation of the terminal voltage change data 321 is similar to the generation of the terminal voltage change data 311, so detailed description thereof will be omitted.

As described above, when the ignition signal 81 is turned off, the state estimating device 20 estimates the open-circuit voltage of the secondary battery 5 from the voltage measurement value E1 at the power-off time and the voltage measurement value E2 at the standby end time. 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 errors in the SOC value 11 .

Also, the voltage estimator 24 estimates the open-circuit voltage Es of the secondary battery 5 in consideration of the temperature of the secondary battery 5 at the power-off time. Thereby, the estimation accuracy of the open-circuit voltage Es of the secondary battery 5 can be improved.

In the above embodiment, an example has been described in which the state estimation device 20 estimates the open-circuit voltage Es of the secondary battery 5 using the temperature measurement value T1. 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 voltage change tables 31 and 32 that do not have temperature columns. Even in this case, the open-circuit voltage Es of the secondary battery 5 can be quickly estimated.

In the above-described embodiment, an example has been described in which the state estimation device 20 determines whether or not the battery is being charged before the ignition signal 81 is turned off, 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 the battery is being charged before the ignition signal 81 is turned off, based on the current measurement value Io obtained before the power-off time. may

In the above-described embodiment, an example in which the state estimation device 20 obtains 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 has passed since the time when the current flowing through the secondary battery 5 became 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 obtains 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 open. As a result, the current flowing through the secondary battery 5 becomes zero.

Further, in the above-described 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 LSI is used here, it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

The method of circuit integration is not limited to LSI, and may be implemented using 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 connections and settings of the circuit cells inside the LSI may be used.

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

Further, each process of the above embodiment may be realized by hardware, or may be realized by software (including cases where it is realized together with an OS (operating system), middleware, or a predetermined library). . Furthermore, 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. ) may be used to realize each functional unit by software processing.

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

A computer program that causes a computer to execute the method described above and a computer-readable recording medium that records the program are included in the scope of the present invention. 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 embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit of the present invention.

100 In-vehicle system 1 Power 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 state of charge estimation unit 26 storage unit 241 selection unit 242 identification unit

Claims (2)

When the secondary battery is discharged before the ignition signal is turned off, a plurality of voltage change data indicating temporal changes in the terminal voltage of the secondary battery after the ignition signal is turned off are collected from the discharge of the secondary battery. a first voltage change table stored together with the temperature at the time of stop;
When the secondary battery is charged before the ignition signal is turned off, a plurality of voltage change data indicating temporal changes in the terminal voltage of the secondary battery after the ignition signal is turned off are obtained from the secondary battery. and a second voltage change table stored with the temperature when charging is stopped,
A first voltage measurement value, which is the voltage of the secondary battery at a first time when the ignition signal changes from on to off, and the internal state of the secondary battery after the first time is in equilibrium. If the secondary battery was discharged before the first time based on a second voltage measurement value that is the voltage of the secondary battery at a second time that is a time before selecting a voltage change table, selecting the second voltage change table if the secondary battery was charged before the first time,
Selecting and selecting voltage change data corresponding to the first voltage measurement value, the second voltage measurement value, and the temperature measurement value, which is the temperature of the secondary battery at the first time, from the selected voltage change table identifying the open-circuit voltage of the secondary battery at the first time from the obtained voltage change data ,
Identifying the curve corresponding to the temperature measurement value from a plurality of curves showing the SOC-OCV characteristics of the secondary battery corresponding to the temperature of the secondary battery, and comparing the identified curve and the identified open circuit voltage determining and storing an SOC value indicating the state of charge of the secondary battery at the first time based on the
Next, after the ignition signal turns on , the state estimation device estimates the SOC value of the secondary battery by adding the SOC value calculated by current integration to the stored SOC value . When the secondary battery is discharged before the ignition signal is turned off, a plurality of voltage change data indicating temporal changes in the terminal voltage of the secondary battery after the ignition signal is turned off are collected from the discharge of the secondary battery. a first voltage change table stored together with the temperature at the time of stop;
When the secondary battery is charged before the ignition signal is turned off, a plurality of voltage change data indicating temporal changes in the terminal voltage of the secondary battery after the ignition signal is turned off are obtained from the secondary battery. and a second voltage change table stored with the temperature when charging is stopped,
A first voltage measurement value, which is the voltage of the secondary battery at a first time when the ignition signal changes from on to off, and an internal state of the secondary battery after the first time are in equilibrium. If the secondary battery was discharged before the first time based on a second voltage measurement value that is the voltage of the secondary battery at a second time that is a time before selecting a voltage change table, and selecting the second voltage change table if the secondary battery was charged before the first time;
Selecting and selecting voltage change data corresponding to the first voltage measurement value, the second voltage measurement value, and the temperature measurement value, which is the temperature of the secondary battery at the first time, from the selected voltage change table identifying the open-circuit voltage of the secondary battery at the first time from the obtained voltage change data ;
Identifying the curve corresponding to the temperature measurement value from a plurality of curves showing the SOC-OCV characteristics of the secondary battery corresponding to the temperature of the secondary battery, and comparing the identified curve and the identified open circuit voltage determining and storing an SOC value indicating the state of charge of the secondary battery at the first time based on the SOC value;
estimating the SOC value of the secondary battery by adding the SOC value calculated by current integration to the stored SOC value after the ignition signal is turned on.

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