An Online Impedance Spectrum Measurement Method Based on Dual Active Bridge Converter

An online impedance spectrum measurement method based on a dual active bridge (DAB) converter is proposed in this article. This work integrates AC impedance measurement technology into the DAB converter in the charging interface device, and achieves online measurement of the AC impedance spectrum by applying sinusoidal disturbance signals of different frequencies to a given part of the PI controller. Through frequency sweep verification and PI controller design, high-quality sinusoidal disturbance signals are achieved. A high-bandwidth operational amplifier was used to build a signal conditioning circuit, and the USB-6211 data acquisition card was used to implement signal acquisition. The fast Fourier transform (FFT) algorithm was used to extract the amplitude and phase information of the impedance. The experimental results show that the error rates of the impedance measurement results are less than ±10%, confirming the functionality and feasibility, and providing a basis for online AC impedance spectroscopy. At the same time, it also provides a low-cost and practical solution strategy.