Battery state estimation device

Abstract

The purpose of the present invention is to provide a battery state estimation device capable of reducing the time it takes to estimate the state of a battery, without requiring synchronization between voltage measurement and current measurement.　A battery state estimation device (1A) according to the present invention comprises: a current application unit (2A) that applies a current having a falling waveform to a battery; a voltage measurement unit (3) that measures the voltage of the battery to which the current has been applied; and a monitoring unit (4A) that estimates the state of the battery on the basis of the measured voltage. The monitoring unit (4A) converts, into a complex frequency, a transient change in the waveform of the voltage of the battery measured by the voltage measurement unit (3) when the current is applied by the current application unit (2A), converts a transient change in the falling waveform of the current into a complex frequency, and estimates the state of the battery by creating a Cole-Cole plot of the impedance of the battery from the transient change in the waveform of the voltage converted into the complex frequency and the transient change in the waveform of the current converted into the complex frequency.

Claims

1. An equivalent circuit constant is the solution resistance R １ , the resistance component R of the negative electrode ２ and the capacitance component C of the negative electrode ２ , a battery state estimation device for estimating the state of a battery, a current application unit that applies a current having a waveform that falls so that the difference between the maximum applied current value and the minimum applied current value to the battery is greater than a first predetermined value, a voltage measurement unit that measures the voltage of the battery to which the current is applied by the current application unit, and a monitoring unit that estimates the state of the battery based on the voltage measured by the voltage measurement unit. The current application unit １ T = 1 / ω １ ×2 applies a current having a waveform, and the time T １ T = 1 / ω １ ×2, the third frequency ω １ is greater than the first frequency ω ２ = 1 / RC ２ C ２ and, in the Cole-Cole plot of the impedance of the equivalent circuit, the real axis is the solution resistance R １ value, the second frequency ω ０ is greater than the first frequency ω ２ and smaller than the second frequency ω ０ . The monitoring unit ２ converts the transient change of the voltage waveform of the battery measured by the voltage measurement unit when the current is applied by the current application unit into a complex frequency, and creates a current that falls so that the difference between the maximum created current value and the minimum created current value is greater than a second predetermined value, and the time T from when the maximum created current value starts to fall until the minimum created current value is reached ０ T = 1 / ω ０ ×2 is greater than the time T １ and smaller than the time T. The transient change of the current waveform is converted into a complex frequency, and the state of the battery is estimated by creating a Cole-Cole plot of the impedance of the battery from the transient change of the voltage waveform converted into a complex frequency and the transient change of the current waveform converted into a complex frequency. A battery state estimation device characterized by the above.

2. The battery state estimation device according to claim 1, characterized in that the monitoring unit performs the conversion of transient changes in the voltage waveform to complex frequencies and the conversion of transient changes in the current waveform to complex frequencies by Fourier transform.

3. The first frequency ω ２ The frequency is 20 to 80 Hz, and the second frequency ω ０ The battery state estimation device according to claim 1, characterized in that the frequency is 1 kHz.

4. The battery state estimation device according to claim 1, characterized in that the minimum value of the current applied by the current application unit is 0 A.

5. If the difference between the phase with respect to frequency during the transient change of the voltage waveform converted to a complex frequency and the phase with respect to frequency during the transient change of the current waveform converted to a complex frequency is not within the third predetermined value in any frequency band, the monitoring unit will adjust the current waveform over the time T so that the difference between the phase with respect to frequency during the transient change of the voltage waveform converted to a complex frequency and the phase with respect to frequency during the transient change of the current waveform converted to a complex frequency is within the third predetermined value in any frequency band. ２ The battery state estimation device according to claim 1, characterized by adjusting the battery state.

6. The monitoring unit determines the value of the real axis where the imaginary axis is zero in the created Cole-Cole plot, which corresponds to the current solution resistance R'. １ The first frequency ω is calculated and used in the resulting call-call plot. ２ The fourth frequency ω is the inflection point of the arc containing it. ４ The value on the real axis and the solution resistance R' １ The difference is the current resistance component R' ２ The current resistance component R' is calculated as follows: ２ The battery state estimation device according to claim 1, characterized in that it estimates the remaining capacity of the battery from the above.

7. The monitoring unit determines the value of the real axis where the imaginary axis is zero in the created Cole-Cole plot, which corresponds to the current solution resistance R'. １ The first frequency ω is calculated and used in the resulting call-call plot. ２ The value on the real axis and the current solution resistance R' １ The difference is the current resistance component R' ３ The current resistance component R' is calculated as follows: ３ The battery state estimation device according to claim 1, characterized in that it estimates the remaining capacity of the battery from the above.

8. The monitoring unit determines the value of the real axis where the imaginary axis is zero in the created Cole-Cole plot, which corresponds to the current solution resistance R'. １ The first frequency ω is calculated and used in the resulting call-call plot. ２ The fourth frequency ω is the inflection point of the arc containing it. ４ The value on the real axis and the current solution resistance 'R'. １ The difference is the current resistance component R' ２ The value of the imaginary axis in the created Cole-Cole plot is calculated as the current solution resistance R' on the real axis. １ From the current solution resistance R' １ and the aforementioned current resistance component R' ２ The battery state estimation device according to claim 1, characterized in that it estimates the remaining capacity of the battery from the area calculated by integrating over the interval up to the sum of the two.

9. The monitoring unit determines the value of the real axis where the imaginary axis is zero in the created Cole-Cole plot, which corresponds to the current solution resistance R'. １ The first frequency ω is calculated and used in the resulting call-call plot. ２ The value on the real axis and the solution resistance R' １ The difference is the current resistance component R' ３ The value of the imaginary axis in the created Cole-Cole plot is calculated as the current solution resistance R' on the real axis. １ From the current solution resistance R' １ and the aforementioned current resistance component R' ３ The battery state estimation device according to claim 1, characterized in that it estimates the remaining capacity of the battery from the area calculated by integrating over the interval up to the sum of the two.

10. The battery state estimation device according to claim 1, characterized in that an alternating current is applied to the battery while sweeping the frequency, and the monitoring unit calculates a correction value from the second distribution result of the resistance and capacity of the created Cole-Cole plot of the battery impedance to convert the second distribution result to a third distribution result corresponding to the first distribution result, based on the second distribution result of the created Cole-Cole plot of the battery impedance, and converts the second distribution result to the third distribution result from the second distribution result and the correction value.

11. The monitoring unit controls the first frequency ω ２ Based on the third distribution results in the following frequency band, the first frequency ω ２ The battery state estimation device according to claim 10, characterized in that a fourth distribution result is created by interpolating the first distribution result for the following frequency bands.

12. The battery state estimation device according to claim 1, characterized in that the monitoring unit estimates the temperature of the battery from the relationship between the phase change with respect to frequency in the transient change of the voltage waveform converted to a complex frequency and the temperature of the battery.

13. The monitoring unit determines the value of the real axis where the imaginary axis is zero in the created Cole-Cole plot, which corresponds to the current solution resistance R'. １ The battery temperature and the current solution resistance R' are calculated and estimated as follows. １ Based on the temperature characteristics, the current solution resistance R' １ The room temperature solution resistance R' ｎｔ１ Converted to, in the created call-call plot, the first frequency ω ２ The fourth frequency ω is the inflection point of the arc containing it. ４ The value on the real axis and the current solution resistance R' １ The difference is the current resistance component R' ２ The battery temperature and the current resistance component R' are calculated and estimated as follows: ２ From the temperature characteristics, the current resistance component R' ２ The room temperature resistance component R' at room temperature ｎｔ２ Converted to the room temperature solution resistance R' ｎｔ１ The state of the battery solution is estimated from the above, and the room temperature resistance component R' ｎｔ２ The battery state estimation device according to claim 12, characterized in that it estimates the remaining capacity of the battery from the above.

14. The monitoring unit determines the value of the real axis where the imaginary axis is zero in the created Cole-Cole plot, which corresponds to the current solution resistance R'. １ The battery temperature and the current solution resistance R' are calculated and estimated as follows. １ Based on the temperature characteristics, the current solution resistance R' １ The room temperature solution resistance R' ｎｔ１ Converted to, in the created call-call plot, the first frequency ω ２ The fourth frequency ω is the inflection point of the arc containing it. ４ The value on the real axis and the solution resistance R' １ The difference is the current resistance component R' ２ The battery temperature and the current resistance component R' are calculated and estimated as follows: ２ From the temperature characteristics, the current resistance component R' ２ The room temperature resistance component R' at room temperature ｎｔ２ Converted to, in the created call-call plot, the first frequency ω ２ The value of the imaginary axis in the current capacity component R' ｊ The battery temperature and the current capacity component R' are calculated and estimated as follows: ｊ Based on the temperature characteristics, the imaginary axis values ​​of the created Cole-Cole plot are converted, and the imaginary axis values ​​in the converted Cole-Cole plot are used to represent the room temperature solution resistance R' on the real axis. ｎｔ１ From the above room temperature solution resistance R' ｎｔ１ and the aforementioned room-temperature resistance component R' ｎｔ２ The battery state estimation device according to claim 12, characterized in that it estimates the remaining capacity of the battery from the area calculated by integrating over the interval up to the sum of the two.

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