Impedance computation for power electronic converters with Hilbert transform

The Hilbert transform (HT) is widely used in signal processing and it has been found as a good tool to understand some physical phenomena in electrical systems. This paper presents a methodology to derive the input impedance of a power electronic converter with the application of the Hilbert transform. The results in the frequency domain based on the Fourier transform are compared with the HT calculations. After an initial example based on a linear circuit, the paper presents the application of the Hilbert transform to calculate the input impedance of a two level power electronics voltage source converter. The results are proved to be in agreement with those obtained from the FFT application. The proposed technique is able to capture the negative resistor behaviour of VSC and an online implementation can be envisioned in the future.