Battery system

Abstract

It also suppresses lithium deposition on the negative electrode when the battery degrades. [Solution] The ECU obtains the State of Charge (SOC), State of Health (SOH), and degradation time Dt (S20). The negative electrode degradation coefficient Ka is calculated from the SOH and effective temperature TBm (S30), and the time degradation coefficient Kt is calculated from the degradation time Dt and effective temperature TBm (S40). The smaller of the negative electrode degradation coefficient Ka and the time degradation coefficient Kt is calculated as the overall degradation coefficient Ko (S50), and the initial input current limit value IinB is calculated from the SOC and effective temperature TBm (S60). The initial input current limit value IinB and the overall degradation coefficient Ko are multiplied to calculate the input current limit value IinR (S70). The battery input current is controlled so as not to exceed the input current limit value IinR. The negative electrode degradation coefficient Ka is set as the reciprocal of the negative electrode degradation degree SOHR (=SOH × negative electrode resistance increase rate) if the negative electrode degradation degree SOHR is greater than 1.

Claims

1. A battery system comprising a battery containing lithium in its electrodes, a temperature sensor for detecting the battery temperature, a current sensor for detecting the input and output current of the battery, and a control device, The control device is A SOH estimation unit for estimating the capacity retention rate of the aforementioned battery, A negative electrode degradation coefficient calculation unit calculates the negative electrode degradation coefficient based on the capacity retention rate and the battery temperature, Includes a limit value calculation unit that calculates an input current limit value based on the negative electrode degradation coefficient, A battery system that controls the input current of the battery so that it does not exceed the input current limit value.

2. The control device is A State of Charge (SOC) calculation unit for calculating the charge level of the aforementioned battery, The system further includes an initial limit value calculation unit that calculates an initial input current limit value based on the charge level and the battery temperature, The battery system according to claim 1, wherein the limit value calculation unit calculates the input current limit value by multiplying the initial input current limit value by the negative electrode degradation coefficient.

3. The negative electrode degradation coefficient is determined by the rate of increase in the negative electrode resistance of the battery and the capacity retention rate. When the degree of negative electrode degradation is defined as capacity retention rate × negative electrode resistance increase rate, If the degree of deterioration of the negative electrode is greater than 1, the negative electrode deterioration coefficient is set as the reciprocal of the degree of deterioration of the negative electrode. The battery system according to claim 2, wherein if the degree of negative electrode degradation is less than 1, the negative electrode degradation coefficient is set to the degree of negative electrode degradation.

4. The aforementioned battery is configured as a battery pack, and multiple temperature sensors are provided. The battery system according to any one of claims 1 to 3, wherein the negative electrode degradation coefficient calculation unit calculates the negative electrode degradation coefficient based on the lowest battery temperature among the battery temperatures detected by the temperature sensor.

5. The control device is A degradation time calculation unit that calculates the degradation time, which is the elapsed time from the start of use of the aforementioned battery, A time degradation coefficient calculation unit calculates a time degradation coefficient based on the aforementioned degradation time and the aforementioned battery temperature, The system further includes a selection unit that uses the smaller of the negative electrode degradation coefficient and the time degradation coefficient as the overall degradation coefficient, The battery system according to claim 4, wherein the limit value calculation unit calculates the input current limit value based on the overall degradation coefficient.

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