JP2019184316A - Device and method for estimation - Google Patents

Abstract

To provide a device and a method for estimation which can output a highly reliable SOC estimation value.SOLUTION: The estimation device according to an embodiment includes a first calculation unit, a second calculation unit, and a determination unit. The first calculation unit calculates a first estimation value of the SOC of a battery by a current integration system. The second calculation unit calculates the second estimation value of the SOC by an equivalent circuit model system using the Kalman filter. The determination unit determines whether the second estimation value is similar to the true value of the SOC or not on the basis of the similarity between the change with time of the first estimation value obtained by the first calculation unit and the change with time of the second estimation value obtained by the second calculation unit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an estimation apparatus and an estimation method.

  Conventionally, a state of charge (SOC) of a lithium-ion secondary battery (LIB) mounted on a hybrid electric vehicle (HEV) or an electric vehicle (EV) is estimated by a predetermined algorithm. The technique to do is known (for example, refer patent document 1).

  Such algorithms include, for example, SOC estimation using a current integration method, SOC estimation using an equivalent circuit model method using a Kalman filter, and the like.

JP 2015-38444 A

  By the way, the current integration method and the equivalent circuit model method are affected by the initial value of the SOC to be used first when the calculation of the SOC is started. For example, when the initial value is different from the true value of the SOC, the current integration method follows the same time change as the true value, so the deviation is not filled and it cannot be said that the SOC is highly reliable.

  For this reason, the SOC estimation is performed by utilizing the fact that the equivalent circuit model method using the Kalman filter finally converges to the true value. At this time, it is determined whether or not the SOC estimated value has converged to the true value. Since there is no index, there is a possibility that an estimated SOC value with low reliability is output.

  The present invention has been made in view of the above, and an object of the present invention is to provide an estimation device and an estimation method capable of outputting a highly reliable SOC estimation value.

  In order to solve the above-described problems and achieve the object, an estimation apparatus according to the present invention includes a first calculation unit, a second calculation unit, and a determination unit. The first calculation unit calculates a first estimated value of battery SOC by a current integration method. The second calculation unit calculates a second estimated value of the SOC by an equivalent circuit model method using a Kalman filter. The determination unit determines whether the second estimated value is in the state based on a similarity between a time change of the first estimated value by the first calculating unit and a time change of the second estimated value by the second calculating unit. It is determined whether or not the value is similar to the true value.

  According to the present invention, a highly reliable SOC estimated value can be output.

FIG. 1A is a block diagram illustrating a configuration of a power supply system according to the embodiment. FIG. 1B is a diagram illustrating an overview of the SOC estimation method according to the embodiment. FIG. 2 is a block diagram illustrating a configuration of the SOC estimation apparatus according to the embodiment. FIG. 3 is a diagram showing SOC map information. FIG. 4 is a diagram showing initial value information. FIG. 5 is a diagram illustrating processing contents of the determination unit. FIG. 6 is a diagram illustrating processing contents of the determination unit. FIG. 7 is a flowchart illustrating a processing procedure of estimation processing executed by the SOC estimation apparatus according to the embodiment.

  Hereinafter, embodiments of an estimation apparatus and an estimation method disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment. In the following, an example in which the SOC estimation device (an example of an estimation device) estimates the state of charge of a lithium ion battery (hereinafter referred to as LiB) mounted on a vehicle, so-called SOC (State Of Charge). I will give you a description. Note that the target of the SOC estimation device is not limited to LiB mounted on a vehicle, and may be LiB mounted on an arbitrary device.

  First, the outline of the SOC estimation method (an example of the estimation method) according to the embodiment will be described with reference to FIGS. 1A and 1B. FIG. 1A is a block diagram illustrating a configuration of a power supply system S according to the embodiment. As shown in FIG. 1A, the power supply system S includes an SOC estimation apparatus 1, a host ECU 10, a generator 11, a starter 12, a lead battery 13, an auxiliary machine 14, a LiB 15, a DCDC converter 16, 1 switch 17 and 2nd switch 18 are provided. That is, the power supply system S is a two-power supply system including two batteries of the lead battery 13 and the LiB15. Note that the power supply system S is not limited to the two-power supply system, and may be one battery or three or more batteries as long as the power supply system includes at least a lithium ion battery.

  The host ECU (Electronic Control Unit) 10 includes, for example, a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), an input / output port, and various circuits.

  The host ECU 10 is a control device that controls the first switch 17 and the second switch 18 based on the SOC estimated by the SOC estimation device 1, for example. Note that the SOC is a state value indicating the state of charge in the LiB 15. The host ECU 10 controls the DCDC converter 16 when supplying power from the LiB 15 to other devices (the lead battery 13 and the auxiliary machine 14), for example. To do.

  The generator 11 is a device that generates electric power using the rotation of the engine as a power source. Further, regenerative electric power is generated by regenerative braking when the vehicle is decelerated. The generator 11 is also called an alternator or a generator.

  Moreover, the generator 11 produces | generates electric power according to the instruction | indication from the engine control apparatus which is not shown in figure, for example. For example, the lead battery 13 and the LiB 15 are charged by supplying the generated power to the lead battery 13 and the LiB 15.

  The starter 12 is a starting device that includes, for example, an electric motor and starts the engine. In the example shown in FIG. 1, the power supply system S includes the starter 12 and the generator 11. For example, the power supply system S uses an integrated starter generator (ISG) instead of the starter 12 and the generator 11. You may prepare.

  The lead battery 13 is a secondary battery using lead as an electrode. The auxiliary machine 14 is a load such as an electronic device provided in the vehicle. For example, the auxiliary machine 14 that is a load includes a navigation device, an audio, an air conditioner, and the like. Alternatively, the auxiliary machine 14 may be a vehicle control device that performs vehicle control such as PCS (Pre-crash Safety System) and AEB (Advanced Emergency Braking System).

  LiB15 is a secondary battery that performs charging or discharging. The DCDC converter 16 is provided between the lead battery 13 and the LiB 15 and between the auxiliary machine 14 and the LiB 15.

  For example, when power is supplied from the LiB 15 to the lead battery 13, the DCDC converter 16 boosts the voltage of the LiB 15. Further, when power is supplied from the LiB 15 to the auxiliary machine 14, the DCDC converter 16 boosts or lowers the voltage of the LiB 15.

  The first switch 17 and the second switch 18 are switches (relays) that control a short circuit and an open circuit. The first switch 17 is provided so that the lead battery 13 and the generator 11 (or starter 12) can be disconnected. The 2nd switch 18 is provided so that LiB15 and the generator 11 can be disconnected. The opening and closing of the first switch 17 and the second switch 18 are controlled by the host ECU 10 described above.

  The SOC estimation apparatus 1 executes a process of calculating a first estimated value of SOC by a current integration method and a process of calculating a second estimated value of SOC by an equivalent circuit model method using a Kalman filter. The current integration method is a method of estimating the current SOC from the previous SOC based on the integral value of the actual current value detected by the current sensor. The equivalent circuit model method is a method of estimating the current SOC from the previous SOC using an equivalent circuit model that simulates a battery.

  And the SOC estimation apparatus 1 performs the SOC estimation method which concerns on embodiment shown to FIG. 1B.

  FIG. 1B is a diagram illustrating an overview of the SOC estimation method according to the embodiment. FIG. 1B shows a graph in which the horizontal axis represents time and the vertical axis represents SOC (first estimated value or second estimated value). The time zero is, for example, the time when the ignition is turned on and the time when the SOC calculation process is started. In FIG. 1B, the initial value used for the SOC calculation process is different from the initial value of the true value.

  Conventionally, the current integration method and the equivalent circuit model method are affected by the initial value of the SOC to be used first when the calculation of the SOC is started. For example, when the initial value is different from the true value of the SOC, the current integration method follows the same time change as the true value, so the deviation is not filled, and when the current integration method is used alone, the reliability is high. It cannot be said that the SOC is output.

  For this reason, the SOC estimation is performed by utilizing the fact that the equivalent circuit model method using the Kalman filter finally converges to the true value. At this time, it is determined whether or not the SOC estimated value has converged to the true value. Since there is no index, there is a possibility that an estimated SOC value with low reliability is output. Thus, there has been room for improvement in terms of outputting highly reliable SOC estimation values.

  Therefore, in the SOC estimation method according to the embodiment, the second estimated value is the SOC based on the similarity between the time variation of the first estimated value by the current integration method and the time variation of the second estimated value by the equivalent circuit model method. It is determined whether or not it is similar to a true value.

  For example, in FIG. 1B, the time change of the equivalent circuit model method and the time change of the current integration method are aligned (similarity is a predetermined value or more) near time t. It is determined that the estimated value is similar to the true value. That is, when the waveform of the first estimated value is similar to the waveform of the second estimated value, it is determined that the second estimated value is similar to the true value.

  Note that the similarity is, for example, a ratio between an increase / decrease value due to a time change of the first estimated value and an increase / decrease value due to a time change of the second estimate value, a difference between the first estimate value and the second estimate value, or the first estimate. It is represented by the difference between the increase / decrease value of the value and the increase / decrease value of the second estimated value.

  As described above, in the SOC estimation method according to the embodiment, reliability is obtained by using the characteristic that converges to the true value of the equivalent circuit model method and the characteristic that the time change of the current integration method is substantially the same as the true value. A high estimated SOC value can be output.

  Next, with reference to FIG. 2, the structure of the SOC estimation apparatus 1 which concerns on embodiment is demonstrated. FIG. 2 is a block diagram illustrating a configuration of the SOC estimation apparatus 1 according to the embodiment. As shown in FIG. 2, the SOC estimation apparatus 1 according to the embodiment includes a control unit 2 and a storage unit 3. The control unit 2 includes a detection unit 21, a first calculation unit 22, a second calculation unit 23, a determination unit 24, and an abnormality determination unit 25. The storage unit 3 stores SOC map information 31 and initial value information 32.

  Here, the SOC estimation apparatus 1 includes, for example, a computer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a data flash, an input / output port, and various circuits.

  The CPU of the computer reads, for example, a program stored in the ROM and executes it as the detection unit 21, the first calculation unit 22, the second calculation unit 23, the determination unit 24, and the abnormality determination unit 25 of the control unit 2. Function.

  In addition, at least one or all of the detection unit 21, the first calculation unit 22, the second calculation unit 23, the determination unit 24, and the abnormality determination unit 25 of the control unit 2 are connected to an ASIC (Application Specific Integrated Circuit) or an FPGA (Field It can also be configured with hardware such as a Programmable Gate Array.

  The storage unit 3 corresponds to, for example, a RAM or a data flash. The RAM and data flash can store SOC map information 31, initial value information 32, information on various programs, and the like. In addition, the SOC estimation apparatus 1 is good also as acquiring the above-mentioned program and various information via the other computer and portable recording medium which were connected by the wired or wireless network.

  The SOC map information 31 is information used when the second calculation unit described later calculates the SOC. FIG. 3 is a diagram showing the SOC map information 31. FIG. 3 shows an OCV-SOC characteristic curve showing the relationship between the open voltage of LiB 15, so-called OCV (Open Circuit Voltage), and the SOC. Further, FIG. 3 shows OCV-SOC characteristic curves at the time of charging and discharging of LiB15.

  As shown in FIG. 3, the OCV-SOC characteristic curve is a polynomial function. The second calculation unit 23 described later estimates the SOC from the OCV using the OCV-SOC characteristic curve and the Kalman filter.

  The initial value information 32 stored in the storage unit 3 is information including the initial value of the SOC used when the first calculation unit 22 and the second calculation unit 23 described later start SOC calculation. FIG. 4 is a diagram showing the initial value information 32. As shown in FIG. 4, the initial value information 32 includes items such as update date and time and final SOC.

  For example, the example shown in FIG. 4 indicates that the SOC was updated on March 6, 2018, and the SOC at that time was 60%. The final SOC update timing is, for example, the timing when the ignition is turned off.

  The detection unit 21 includes various sensors, detects the current value and voltage value of the LiB 15, and outputs the detected current value and voltage value to the first calculation unit 22 and the second calculation unit 23.

  The first calculator 22 calculates a first estimated value of the SOC by a current integration method. Specifically, the first calculator 22 calculates the current first estimated value from the integrated value of the actual current values detected by the detector 21 and the previous first estimated value. The first calculation unit 22 outputs the calculated first estimated value to the determination unit 24. Note that the first calculation unit 22 uses the initial SOC value of the initial value information 32 (the final SOC shown in FIG. 4) as the previous first estimated value for the first estimated value that is calculated first after the ignition is turned on. use.

  The second calculator 23 calculates the second estimated value of the SOC by an equivalent circuit model method using a Kalman filter. Specifically, first, the second calculation unit 23 calculates an OCV (Open Circuit Voltage) from the internal resistance, the actual current value, and the actual voltage value of an equivalent circuit model simulating LiB15. The detailed calculation method of the OCV is well known and will be omitted.

  The internal resistance of the equivalent circuit model is calculated based on the resistance value of the resistance element in the circuit and the capacitance of the capacitor. As a calculation method of the internal resistance, a method of calculating the internal resistance from the resistance value of the resistance element whose value is determined in advance and the capacitance of the capacitor, a method of calculating by a recursive least square (RLS) method, and There is. In the RLS calculation method, the internal resistance is calculated from the fluctuation value of the actual current value (difference between the current value and the previous value) detected by the detection unit 21 and the fluctuation value of the actual voltage value.

  Subsequently, the second calculation unit 23 refers to the SOC map information 31 and calculates the second estimated value of the SOC from the OCV using the Kalman filter. Specifically, first, the second calculation unit 23 calculates an SOC (hereinafter referred to as a current SOC described later) from the OCV based on the SOC map information 31.

  Subsequently, the second calculation unit 23 calculates a second estimated value using the state space model of LiB15. Specifically, first, the second calculator 23 predicts the current second estimated value from the previous second estimated value in the state space model of LiB15. Then, the second calculation unit corrects the predicted second estimated value using the current SOC calculated from the SOC map information 31, and determines the final second estimated value as a final current second estimate. Output.

  Note that the second calculation unit 23 uses the initial SOC value (the final SOC shown in FIG. 4) of the initial value information 32 as the previous second estimated value for the second estimated value that is calculated first after the ignition is turned on. use.

  The determination unit 24 determines the validity of the second estimated value. Specifically, the determination unit 24 determines the second estimated value based on the similarity between the time change of the first estimated value by the first calculating unit 22 and the time change of the second estimated value by the second calculating unit 23. It is determined whether or not it is similar to the true value of the SOC.

  Here, the processing content of the determination part 24 is demonstrated using FIG. 5 and FIG. FIG. 5 and FIG. 6 are diagrams showing the processing contents of the determination unit 24. 5 shows a graph in which the horizontal axis is time and the vertical axis is the estimated SOC value (first estimated value and second estimated value), and in the lower stage, the horizontal axis is time and the vertical axis is the first estimated value. The graph which is a ratio of the increase / decrease value by the time change of the 2nd estimated value with respect to the increase / decrease value by the time change of a value is shown.

  The increase / decrease value is a difference between the current SOC estimated value (first estimated value and second estimated value) and the previous SOC estimated value. The increase / decrease value is not limited to the current SOC estimated value and the previous SOC estimated value, but may be a difference between the current SOC estimated value and the SOC estimated value of the previous time (or more).

  The determination unit 24 determines that the second estimated value is similar to the true value when the ratio between the increase / decrease value due to the time change of the first estimated value and the increase / decrease value due to the time change of the second estimated value satisfies a predetermined similarity condition. judge.

  In the example illustrated in the lower part of FIG. 5, the determination unit 24 determines that the similarity condition is satisfied when the ratio of the increase / decrease value of the second estimate value to the increase / decrease value of the first estimate value is less than a predetermined threshold value TH. It is determined that the second estimated value at is similar to the true value.

  Thus, by determining the similarity to the true value based on the ratio of the increase / decrease value of the first estimated value and the increase / decrease value of the second estimated value, it can be reliably determined that the second estimated value is similar to the true value. Therefore, a highly reliable SOC estimated value can be output.

  The above increase / decrease value is preferably a value having a certain size. For example, when the increase / decrease value is less than a predetermined value, the ratio described above fluctuates greatly, and the reliability of the ratio decreases. Therefore, when the increase / decrease value of at least one of the first estimated value and the second estimated value is less than the predetermined value, the determination unit 24 does not perform similarity determination of the true value of the second estimated value.

  In other words, the determination unit 24 reduces the reliability of the determination by performing the similarity determination of the true value only when the increase / decrease value of at least one of the first estimated value and the second estimated value is equal to or greater than the predetermined value. Can be prevented.

  Note that if the determination unit 24 determines that the second estimated value is similar to the true value at time t, the determination unit 24 does not determine similarity with the true value at subsequent times. Thereby, since unnecessary processing can be reduced, it is possible to prevent the processing load of the control unit 2 from increasing.

  Further, the determination unit 24 may determine that the ratio is similar to the true value when the ratio is less than the threshold TH even once, but for example, the ratio is continuously less than the threshold TH a plurality of times. If it becomes, it may be determined that it is similar to the true value. This point will be described with reference to FIG.

  As shown in FIG. 6, for example, it is assumed that the ratio is less than the threshold value TH at the time ta. That is, it is assumed that the ratio satisfying the similarity condition is only once. In such a case, the determination unit 24 determines that the second estimated value is not similar to the true value, assuming that the ratio satisfying the similarity condition has not continued for a predetermined number of times.

  Then, the determination unit 24 determines that the second estimated value is similar to the true value, assuming that the ratio satisfying the similarity condition continues for a predetermined number of times or more (four or more times in FIG. 6) at time t. As described above, when the ratio satisfying the similarity condition can be held for a certain number of times, it is determined that the second estimated value is similar to the true value, thereby preventing erroneous determination such as noise that temporarily becomes less than the threshold value TH. Can do.

  If the determination unit 24 determines that the second estimated value is similar to the true value, the determination unit 24 outputs the second estimated value to the host ECU 10 as the determined value of the SOC. The determination unit 24 is not limited to the case where the second estimated value is output as a confirmed value.

  For example, the determination unit 24 may use an average value of the first estimated value and the second estimated value as a definite value, and sets a value calculated by weighting each of the first estimated value and the second estimated value as a definite value. It is good. In addition, after determining that the second estimated value is similar to the true value, in the OCV-SOC characteristic shown in FIG. When the first estimated value is replaced with the second estimated value, the first estimated value may be output to the host ECU 10 as the determined SOC value thereafter.

  The abnormality determination unit 25 determines whether or not the initial SOC value of the initial value information 32 is abnormal. For example, when the abnormality determination unit 25 determines that the initial value of the SOC is abnormal, the abnormality determination unit 25 outputs the determination result to the first calculation unit 22 and the second calculation unit 23.

  The abnormality in the abnormality determination unit 25 is, for example, a previous SOC writing error in the storage unit 3 or a read error in the first calculation unit 22 and the second calculation unit 23 (the abnormality determination unit 25 itself reads out). Determination), data is destroyed, LiB 15 is not depolarized, SOC cannot be estimated uniquely from the acquired voltage, and the like. In addition, that the SOC cannot be uniquely estimated from the voltage refers to a case where the detected OCV corresponds to a flat region (central portion) in the OCV-SOC characteristic curve.

  Then, the first calculation unit 22 and the second calculation unit 23 perform an estimated value calculation process by replacing the initial value with a predetermined alternative value based on the determination result. The substitute value may be, for example, an arbitrary value set in advance (range of 0 to 100%).

  Alternatively, the substitute value may be an actual voltage value of LiB 15 that has not been depolarized or an SOC calculated from an OCV in a flat region in the OCV-SOC characteristic curve.

  In addition, when the abnormality determination unit 25 determines that the initial value of the SOC is not abnormal, the abnormality determination unit 25 outputs the determination result to the first calculation unit 22 and the second calculation unit 23. Then, the first calculation unit 22 and the second calculation unit 23 perform an estimated value calculation process using the initial value of the initial value information 32 based on the determination result.

  As described above, when the initial value of the SOC is determined to be abnormal by the abnormality determination unit 25, it is possible to prevent the SOC from being continuously calculated with the abnormal initial value by replacing it with the alternative value.

  Next, the processing procedure of the estimation process executed by the SOC estimation apparatus 1 according to the embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing a processing procedure of estimation processing executed by the SOC estimation apparatus 1 according to the embodiment.

  As shown in FIG. 7, first, the abnormality determination unit 25 detects that the ignition is turned on (step S101). When the ignition is turned on, abnormality determination unit 25 determines whether or not the initial value of the SOC is normal (step S102).

  When the initial value of the SOC is normal (Yes at Step S102), the second calculation unit 23 calculates the second estimated value based on the initial value (Step S103).

  Then, the control unit 2 notifies the host ECU 10 of the second estimated value calculated by the second calculating unit 23 as the determined value of the SOC (Step S104), and the process is terminated. Note that the control unit 2 may notify the host ECU 10 of the first estimated value calculated by the first calculation unit 22 as the determined value of the SOC.

  On the other hand, if the initial value of the SOC is abnormal (No in step S102), the first calculation unit 22 calculates the first estimated value by replacing the initial value with a predetermined alternative value (step S105).

  Subsequently, the second calculator 23 calculates a second estimated value by replacing the initial value with a predetermined alternative value (step S106). Note that the processing order of step S105 and step S106 may be interchanged. Subsequently, the determination unit 24 calculates an increase / decrease value due to a time change of the first estimated value (step S107). Subsequently, the determination unit 24 calculates an increase / decrease value due to a time change of the second estimated value (step S108).

  Subsequently, the determination unit 24 determines whether or not the increase / decrease value due to the temporal change of the first estimated value and the increase / decrease value due to the temporal change of the second estimated value are each greater than or equal to a predetermined value (step S109). When each increase / decrease value is equal to or greater than the predetermined value (Yes in step S109), the determination unit 24 determines whether the ratio of the increase / decrease value satisfies a predetermined similarity condition (step S110).

  Then, when the ratio of the increase / decrease value satisfies a predetermined similarity condition (step S110, Yes), the determination unit 24 increases the condition satisfaction count (step S111). Subsequently, the determination unit 24 determines whether or not the condition satisfaction count is greater than or equal to a threshold value (step S112).

  The determination unit 24 determines that the second estimated value is similar to the true value, assuming that the ratio satisfying the similarity condition continues a predetermined number of times or more when the condition satisfaction count is equal to or greater than the threshold (Yes in Step S112) (Step S112). S113), the process proceeds to step S104.

  On the other hand, in step S109, the determination part 24 transfers a process to step S105, when at least one is less than predetermined value among each increase / decrease values (step S109, No).

  In Step S110, when the ratio of the increase / decrease value does not satisfy the predetermined similarity condition (No in Step S110), the determination unit 24 resets the condition establishment count (Step S114), and the process proceeds to Step S105. Note that the processing in step S114 may be performed by subtracting a predetermined number instead of resetting. In this case, it is desirable that the value to be subtracted is larger than the value counted up in step S111.

  Moreover, in step S112, the determination part 24 transfers a process to step S105, when the condition satisfaction count number is less than a threshold value (step S112, No). That is, the condition satisfaction count is not reset.

  As described above, the SOC estimation apparatus 1 according to the embodiment includes the first calculation unit 22, the second calculation unit 23, and the determination unit 24. The first calculator 22 calculates a first estimated value of the SOC in the LiB 15 by a current integration method. The second calculator 23 calculates the second estimated value of the SOC by an equivalent circuit model method using a Kalman filter. The determining unit 24 determines that the second estimated value is a true value of the state value based on the similarity between the time change of the first estimated value by the first calculating unit 22 and the time change of the second estimated value by the second calculating unit 23. It is determined whether or not it is similar. Thereby, a highly reliable SOC estimated value can be output.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 SOC estimation apparatus 2 Control part 3 Memory | storage part 10 Host ECU
11 Generator 12 Starter 13 Lead battery 14 Auxiliary machine 15 LiB
16 DCDC converter 17 1st switch 18 2nd switch 21 Detection part 22 1st calculation part 23 2nd calculation part 24 Determination part 25 Abnormality determination part 31 SOC map information 32 Initial value information S Power supply system

Claims (5)

A first calculation unit that calculates a first estimated value of a state value indicating a state of charge in the battery by a current integration method;
A second calculation unit for calculating a second estimated value of the state value by an equivalent circuit model method using a Kalman filter;
The second estimated value becomes a true value of the state value based on the similarity between the time change of the first estimated value by the first calculating unit and the time change of the second estimated value by the second calculating unit. An estimation device comprising: a determination unit that determines whether or not they are similar. The determination unit
When the ratio between the increase / decrease value due to the time change of the first estimated value and the increase / decrease value due to the time change of the second estimate value satisfies a predetermined similarity condition, it is determined that the second estimate value is similar to the true value The estimation apparatus according to claim 1, wherein: The determination unit
The estimation apparatus according to claim 2, wherein when the ratio that satisfies the similarity condition continues for a predetermined number of times or more, the second estimated value is determined to be similar to the true value. When the ignition of the vehicle is turned on, further comprising an abnormality determination unit that determines whether the initial value of the state value is abnormal,
The first calculation unit and the second calculation unit are:
When the abnormality determination unit determines that the initial value is abnormal, the initial value is replaced with a predetermined alternative value, and an estimated value calculation process is performed. The estimation device described. A first calculation step of calculating a first estimated value of a state value indicating a state of charge in the battery by a current integration method;
A second calculation step of calculating a second estimated value of the state value by an equivalent circuit model method using a Kalman filter;
The second estimated value becomes the true value of the state value based on the similarity between the time change of the first estimated value by the first calculating step and the time change of the second estimated value by the second calculating step. A determination step of determining whether or not they are similar to each other.

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