US-12625189-B2 - Estimation device, estimation method, and computer program

Abstract

The estimation device 4 is provided with: a first acquisition unit 41 for acquiring SOC values obtained at the start and end of charging, discharging, or float-charging of a power storage element 3 ; a storage unit 42 storing multiple deterioration coefficients corresponding to multiple SOC ranges; an identification unit 41 for identifying, on the basis of the start and end SOC values acquired by the first acquisition unit 41 , a corresponding deterioration coefficient from among the multiple deterioration coefficients stored in the storage unit 42 ; and an estimation unit 41 for estimating the deterioration of the power storage element 3 on the basis of the deterioration coefficient identified by the identification unit 41.

Inventors

• Katsuya Oji

Assignees

• GS YUASA INTERNATIONAL LTD.

Dates

Publication Date

20260512

Application Date

20200521

Priority Date

20190524

Claims (4)

1. 1 . A charge-discharge system of an energy storage device, the charge-discharge system comprising: a voltage sensor connected in parallel to the energy storage device; a current sensor connected in series to the energy storage device; a temperature sensor connected adjacent to the energy storage device; and an electronic control unit comprising: a controller; and a storage that is preloaded with a degradation coefficient table which stores a plurality of degradation coefficients in association with a plurality of state of charge (SOC) ranges obtained by dividing SOCs of 0 to 100% at different intervals and that stores an estimation program which is a computer program, wherein the controller is configured to: receive detection results of a voltage, a current, and a temperature, the detection results being generated by the voltage sensor, the current sensor, and the temperature sensor, respectively; and upon determination that a switching is performed between the charge and discharge and based upon the received detection results: (i) calculate SOCs at a start and an end in charge, discharge, or floating charge of the energy storage device; (ii) calculate a change amount of current, voltage, power, or an SOC in a unit time; (iii) determine presence or absence of switching from leaving to charge, switching from leaving to discharge, or switching between charge-discharge based on the change amount of the current, the voltage, the power, or the SOC presently acquired and the change amount of the current, the voltage, the power, or the SOC previously acquired; (iv) identify a corresponding degradation coefficient from the degradation coefficient table based on the SOCs acquired at the start and the end; and (v) calculate estimated degradation of the energy storage device based on the degradation coefficient identified, wherein the degradation coefficient identified is of an SOC range including the SOCs acquired at the start and end and having a smallest range width in the plurality of SOC ranges.
2. 2 . The charge-discharge system according to claim 1 , wherein the controller of the electronic control unit is further configured to calculate the SOC based on the change amount of the current, the voltage, the power, or the SOC presently acquired and the change amount of the current, the voltage, the power, or the SOC previously acquired.
3. 3 . The charge-discharge system according to claim 2 , wherein the controller of the electronic control unit is further configured to: determine whether a state is a charge-discharge state, a leaving state, or a floating state based on a change amount of current, voltage, power, or an SOC acquired for a unit time acquired, and estimate the degradation based on the determined state.
4. 4 . The charge-discharge system according to claim 1 , wherein the controller of the electronic control unit is further configured to determine a number of the energy storage device replaced or added after a predetermined period.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a national stage application, filed under 35 U.S.C. § 371, of International Application No. PCT/JP2020/020136, filed May 21, 2020, which international application claims priority to and the benefit of Japanese Application No. 2019-097998, filed May 24, 2019; the contents of both of which as are hereby incorporated by reference in their entireties. BACKGROUND Technical Field The present invention relates to an estimation device, an estimation method, and a computer program for estimating degradation of an energy storage device. Description of Related Art An energy storage device capable of storing electric energy and supplying energy as a power source when necessary is used. The energy storage device is applied to a portable instrument, a power supply device, a transportation instrument including automobiles and railways, an industrial instrument including aerospace and construction, and the like. It is important to constantly grasp a storage capacity of the energy storage device such that the energy stored as much as necessary can be used when necessary. It is known that the energy storage device is mainly chemically degraded with time and a use frequency. Thus, the energy that can be utilized decreases with time and use frequency. It is important to grasp a degradation state of the energy storage device in order to use the energy as much as necessary when necessary. A technique for estimating the degradation of the energy storage device has been developed so far. For example, when the energy storage device is used in a wind power generation facility, the amount of power generation is frequently switched by wind power, and the pattern of the power generation is complicated, so that a charge-discharge pattern of the energy storage device is also complicated. In the case of solar power generation, for instance, because power is generated in the daytime, a substantially constant power generation pattern is provided, and the charge-discharge pattern of the energy storage device is also substantially constant. Thus, the degradation of the energy storage device can be estimated by acquiring the charge-discharge pattern for a predetermined period. Also in an on-vehicle energy storage device, the degradation of the energy storage device is estimated by acquiring the charge-discharge pattern for the predetermined period. Patent Document WO 2013/099401 discloses a storage battery system that distributes a current from a power generation device to a plurality of storage battery blocks and distributes a constant current to at least one storage battery block, and estimates a state of charge (SOC) from a current, a voltage, and a temperature of the storage battery block to which the constant current is distributed. BRIEF SUMMARY In the conventional method, particularly in the case of a complicated charge-discharge pattern in which the charge-discharge is frequently switched, estimation accuracy of the degradation of the energy storage device may not be sufficient. In the storage battery system of Patent Document WO 2013/099401, the SOC can be measured by applying a constant current during a measurement time, but a degradation amount accumulated in the storage battery cannot be estimated. There is a demand for better estimation of the degradation even for the complicated charge-discharge pattern. An object of the present invention is to provide an estimation device, an estimation method, and a computer program capable of accurately estimating the degradation of the energy storage device. According to an aspect of the present invention, an estimation device includes: a first acquisition unit that acquires SOCs at a start and an end in charge, discharge, or floating charge of an energy storage device; a storage that stores a plurality of degradation coefficients corresponding to a plurality of SOC ranges; an identification unit that identifies a corresponding degradation coefficient from the plurality of degradation coefficients stored in the storage based on the SOCs at the start and the end acquired by the first acquisition unit; and an estimation unit that estimates degradation of the energy storage device based on the degradation coefficient identified by the identification unit. According to another aspect of the present invention, an estimation method includes: acquiring SOCs at a start and an end in charge, discharge, or floating charge of an energy storage device; and estimating degradation of the energy storage device using a degradation coefficient previously determined from a plurality of SOC ranges based on the acquired SOCs at the start and the end. According to still another aspect of the present invention, a computer program causing a computer to execute: acquiring SOCs at a start and an end in charge, discharge, or floating charge of an energy storage device; and estimating degradation of the energy storage device using a degradation coefficient pre