Chirp Signal Injection Method and Real-Time Impedance Characteristic Measurement of Electric Energy Router

The plug-and-play capability of electric energy router (EER) is a hot topic in recent years, and the impedance measurement is one of the key technologies in the field of stability estimation for plug-and-play. In this article, EER injects a small chirp signal to the dc equipment and measures the corresponding response signal, thereby calculating its impedance characteristic in real time. Since the conventional control method of dc port is difficult to superimpose high-frequency perturbing signal on the power components, a closed-loop control method for injecting chirp signal is proposed, based on the modulation-demodulation process in communication principles. In addition, an impedance measurement method using short-time Fourier transform (STFT) is proposed, which splits the time-consuming Fourier transform to the same time as sampling. A 10-kW noninverting buck-boost (NIBB) converter was built as the dc/dc stage of EER to verify the above methods. The experimental results show that the chirp signal can be injected well using the proposed methods. Also, the impedance can be accurately measured within 2 s.