Measuring Online Battery AC Resistance Using a DC-DC Converter With Time and Frequency Hybrid Method

This is the authors' abstract. We don't add key points for this paper.

The estimation of battery state is important for ensuring the stability of batteries. The AC resistance of a battery is one of the factors used to estimate the battery state, and is measured using a Fast Fourier Transform (FFT), a technique that analyzes the frequency components. The power converter can implement the dual functionality of power conversion and online AC resistance measurements and achieve high cost-effectiveness with the addition of only a control algorithm. However, the high FFT resolution in a Digital Signal Processor (DSP) requires a long computation time and Random-Access Memory (RAM) to process large amounts of data. Therefore, it is difficult to measure low-frequency ranges using AC resistance calculations based on the FFT. In this study, a time- and frequency-domain hybrid measurement method to enhance low-frequency AC resistance measurements with the desired frequency resolution is proposed. This study investigates frequency resolution in the low-frequency range using time- and frequency-domain measurement methods. The operational principle of the proposed method was analyzed to design a measurement algorithm. The experimental results verified the performance of the proposed method by measuring the AC resistance of a battery within the desired frequency range.