US-12618911-B2 - Battery control device

US12618911B2US 12618911 B2US12618911 B2US 12618911B2US-12618911-B2

Abstract

A battery control device which obtains a state of charge of a secondary battery from characteristics representing a relationship of a state of charge and a voltage of the secondary battery comprises a calling unit which calls a first characteristic among a plurality of the characteristics stored in advance based on use history information of the secondary battery, a correction limit width designation unit which designates a correction limit width for prescribing a tolerance level of correcting the first characteristic, and a direct detection correction unit which creates a second characteristic in which the first characteristic has been corrected according to the correction limit width based on a current value and a voltage value of the secondary battery, wherein the state of charge of the secondary battery is obtained using the second characteristic.

Inventors

Shunya NAITO
Ryohhei NAKAO
Daiki Komatsu

Assignees

Vehicle Energy Japan Inc.

Dates

Publication Date: 20260505
Application Date: 20240620
Priority Date: 20181026

Claims (11)

1 . A battery control device which obtains a state of charge of a secondary battery from characteristics representing a relationship of a state of charge and a voltage of the secondary battery, comprising: a calling circuit which calls a first characteristic among a plurality of the characteristics stored in advance based on use history information of the secondary battery; a correction limit width designation circuit which designates a correction limit width for prescribing a tolerance level of correcting the first characteristic; a direct detection correction circuit structured to acquire data indicative of a current value and a voltage value in the secondary battery and create a second characteristic in which the first characteristic has been corrected based on a current value and a voltage value of the secondary battery, wherein when the first characteristic after correction is outside a range of the correction limit width, the detection correction circuit limits the first characteristic after correction to be within the range of the correction limit width; and a control circuit structured to provide an instruction to an inverter coupled to the secondary battery to control at least one of a power input to or a power output from the secondary battery based on the state of charge, wherein the state of charge of the secondary battery is obtained using the second characteristic.
2 . The battery control device according to claim 1 , wherein the calling circuit calls the first characteristic by using at least one among a state of health, a current history, a temperature history and a state of charge history of the secondary battery as the use history information.
3 . The battery control device according to claim 1 , wherein the correction limit width designation circuit designates, as the correction limit width, a certain voltage width for each state of charge or a certain state of charge width for each voltage.
4 . The battery control device according to claim 1 , wherein the correction limit width designation circuit designates, as the correction limit width, a voltage width which differs for each predetermined state of charge or a state of charge width which differs for each predetermined voltage.
5 . The battery control device according to claim 1 , wherein the correction limit width designation circuit changes the correction limit width according to an operating history of the secondary battery.
6 . The battery control device according to claim 5 , wherein the correction limit width designation circuit changes the correction limit width according to the operating history of the secondary battery by selecting one correction limit width among a plurality of the correction limit widths stored in advance based on the first characteristic.
7 . The battery control device according to claim 1 , further comprising: a voltage operation circuit which calculates an open voltage value and a polarization voltage value of the secondary battery based on a current value and a voltage value of the secondary battery, wherein the direct detection correction circuit acquires, a plurality of times within a predetermined time range, an open voltage value of the secondary battery when the current value and the polarization voltage value are respectively smaller than a predetermined threshold, and creates the second characteristic by using each of the acquired open voltage values, a current integrated value in an acquisition period of each of the open voltage values, and the first characteristic.
8 . The battery control device according to claim 1 , wherein: the correction limit width designation circuit designates a second correction limit width for prescribing a tolerance level of correcting the second characteristic created in a past by the direct detection correction circuit; and the direct detection correction circuit creates the second characteristic by using the correction limit width designated by the correction limit width designation circuit for a present first characteristic and the second correction limit width designated by the correction limit width designation circuit for a past second characteristic.
9 . The battery control device according to claim 1 , wherein the direct detection correction circuit updates the use history information based on the first characteristic after correction including parts outside the range of the correction limit width.
10 . The battery control device according to claim 9 , wherein the direct detection correction circuit determines whether the first characteristic after correction is within the range of the correction limit width, and updates the use history information when the first characteristic after correction determined to be outside the range of the correction limit width satisfies a predetermined convergence condition.
11 . The battery control device according to claim 10 , wherein the convergence condition includes at least one of either a first condition in which a number of times that the first characteristic after correction was continuously determined to be outside the range of the correction limit width is equal to or greater than a predetermined number of times, or a second condition in which a variance in the first characteristic after correction is equal to or less than a predetermined threshold.

Description

TECHNICAL FIELD The present invention relates to a battery control device. BACKGROUND ART Conventionally, chargeable/dischargeable secondary batteries have been used in a variety of fields including mobile phones and other mobile terminals, and in the stabilization of power system interconnections. Furthermore, in recent years, electric vehicles, hybrid vehicles and other vehicles that use the power of secondary batteries as its power source are attracting attention in light of global warming countermeasures, emission controls, and measures for preventing the depletion of fossil fuels. A system equipped with these secondary batteries generally comprises a battery control device for using the batteries safely and for maximizing the performance of the batteries. A battery control device detects the voltage, temperature and current of the batteries, and operates battery parameters such as the state of charge (SOC) and the state of health (SOH) of the batteries based on the results of such detection. The state of charge (SOC) of a battery can generally be acquired using an SOC-OCV characteristic, which is the relationship between the SOC and the open circuit voltage (OCV) of the battery. Nevertheless, the SOC-OCV characteristic is known to change depending on the degradation or individual variation of the battery. In recent years, inclination of the SOC-OCV characteristic is decreasing due to the improvement of electrode materials, and the degradation or individual variation of the SOC-OCV characteristic is becoming a problem as the cause of an SOC error. Thus, in order to calculate the SOC accurately, a logic for detecting and correcting the changes in the SOC-OCV characteristic is required. As methods of operating the SOC according to the changes in the SOC-OCV characteristic, for example, known are the technologies described in PTL 1 and PTL 2 below. PTL 1 discloses a controller of an electricity storage system which calculates, by using an average SOC and an average battery temperature of a period in which a full charge capacity has not been estimated (unestimated period) from the time that the full charge capacity was previously calculated to date and a decrease rate map in which a decrease rate that changes according to the average SOC and the average battery temperature is prescribed in advance, the decrease rate during the unestimated period, and calculates a first elapsed time of an electrical storage device when the full charge capacity was previously calculated based on the decrease rate during the unestimated period and an initial full charge capacity. PTL 1 further discloses that the controller of the electricity storage system calculates a present full charge capacity based on a present second elapsed period of the electrical storage device calculated from the first elapsed period and the unestimated period, the decrease rate during the unestimated period, and the initial full charge capacity. PTL 2 discloses a method of estimating a state of charge of a secondary battery based on an open voltage value and a current integrated value including the steps of updating an instantaneous state of charge map which prescribes a relationship of an instantaneous open voltage value when estimating a state of charge and a state of charge estimated value based on charge/discharge characteristic data after start of use of the secondary battery, calculating an instantaneous state of charge estimated value when estimating a state of charge based on the updated instantaneous state of charge map, calculating the state of charge estimated value based on an integrated value of a current flowed through the secondary battery, and calculating a control state of charge estimated value for use in controlling the secondary battery based on the instantaneous state of charge estimated value and the state of charge estimated value based on the current integrated value. CITATION LIST Patent Literature [PTL 1] Japanese Unexamined Patent Application Publication No. 2015-40832[PTL 2] Japanese Unexamined Patent Application Publication No. 2016-114469 SUMMARY OF THE INVENTION Problems to be Solved by the Invention With the method of PTL 1, it is not possible to deal with differences in the SOC-OCV characteristics based on individual variations that occur during the manufacture of the batteries. Moreover, when the actual conditions of use of the battery and the degradation condition prescribed in the decrease rate map stored in the controller are different, an error will occur between the prediction result of the SOC-OCV characteristic and the actual SOC-OCV characteristic. Thus, there is a problem in that the operational precision of the SOC will be low. Meanwhile, with the method of PTL 2, when there is a measurement error in the OCV or the current integrated value, there is a problem in that it is not possible to accurately update the instantaneous state of charge map corresponding to the SOC-OCV characteristic, and that a gross e