On-Line Capacitance Estimation Method of Parallel DC-DC Converters using Beat Frequency Component

This paper presents an algorithm for online estimation of capacitance and ESR using the beat frequency components of parallel DC–DC converters. The beat frequency is generated by the different switching frequencies of the parallel DC–DC converters. The amplitude and phase information of the beat frequency components are extracted through the short-time Fourier transform (STFT) to estimate the capacitance and ESR. The proposed algorithm does not require the injection of external signals for the online estimation. The performance of the proposed algorithm is verified through real-time simulations and FPGA controller-based experiments with 800 W parallel buck DC–DC converters implemented in the Typhoon HIL 404 system.