Battery system

Abstract

To accurately estimate whether a secondary battery including a nonaqueous electrolyte solution deteriorates.SOLUTION: A battery system is to estimate whether a secondary battery including a nonaqueous electrolyte solution deteriorates. The battery system includes a voltage sensor 21 and an ECU 40. The voltage sensor 21 detects a voltage value VV of a battery 20. The ECU 40 is configured to perform a stopping process, a calculating process, and an estimating process. The stopping process includes a process of stopping charging of the battery 20 when the change rate of dQ / dV of the battery 20 to SOC of the battery 20 is less than a threshold. The term dQ / dV is the ratio of a power storage quantity change quantity dQ of the battery 20 to a voltage change quantity dV of the battery 20. The calculating process includes a process of calculating an evaluation value for evaluating the degree of polarization relaxation after the battery 20 is charged, in accordance with the voltage value after the stopping process. The estimating process includes a process of estimating whether the deterioration occurs in accordance with the evaluation value.SELECTED DRAWING: Figure 2

Claims

1. A battery system for estimating whether or not a secondary battery containing a non-aqueous electrolyte has deteriorated, wherein the deterioration is a phenomenon in which the internal resistance of the secondary battery increases due to an imbalance in the ion concentration in the non-aqueous electrolyte. A voltage sensor for detecting the voltage value of the secondary battery, The system includes a processing unit configured to perform a stop process, a calculation process, and an estimation process, The aforementioned stopping process includes stopping the charging of the secondary battery when the rate of change of the dQ / dV of the secondary battery with respect to the SOC of the secondary battery is smaller than a threshold value. The dQ / dV is the ratio of the change in the amount of charge stored in the secondary battery dQ to the change in the voltage of the secondary battery dV, The calculation process includes a process to calculate an evaluation value for evaluating the degree of polarization relaxation after charging of the secondary battery, according to the voltage value after the stop process. The battery system includes a process for estimating whether or not degradation has occurred according to the evaluation value, wherein the estimation process is performed according to the evaluation value.

2. The evaluation value is the difference between the voltage value at the time the charging stops and the voltage value at the time the secondary battery is depolarized after the charging stops. The aforementioned estimation process is, If the difference value is smaller than the reference value, a process is performed to estimate that there is no deterioration. The battery system according to claim 1, further comprising a process of estimating that deterioration has occurred if the difference value is equal to or greater than the reference value.

3. The aforementioned battery system is mounted on the vehicle, The battery system according to claim 1 or 2, wherein the processing device performs the stop process when external charging is being performed, which charges the secondary battery with a charging current supplied from a charging facility located outside the vehicle.

4. The battery system according to claim 3, wherein the processing device performs the estimation process if the charging current during a predetermined period before the cessation of the external charging is equal to or greater than the threshold current.

5. A battery system for estimating whether or not a secondary battery containing a non-aqueous electrolyte has deteriorated, wherein the deterioration is a phenomenon in which the internal resistance of the secondary battery increases due to an imbalance in the ion concentration in the non-aqueous electrolyte, The aforementioned battery system is mounted on the vehicle, A voltage sensor for detecting the voltage value of the secondary battery, The system comprises a processing unit configured to perform calculation and estimation processes, The calculation process includes a post-driving system shutdown calculation process that calculates an evaluation value for evaluating the degree of polarization relaxation after discharge of the secondary battery, according to the voltage value after the vehicle's driving system has been shut down. The calculation process after the driving system has stopped is performed when the rate of change of the secondary battery's dQ / dV relative to the secondary battery's SOC is smaller than a threshold value after the driving system has stopped. The dQ / dV is the ratio of the change in the amount of charge stored in the secondary battery dQ to the change in the voltage of the secondary battery dV, The battery system includes a process for estimating whether or not deterioration has occurred according to the evaluation value calculated by the calculation process after the driving system has stopped.

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