Application of Dynamic Phasor for Internal and Dynamic Stability Assessment of Aeronautic AC-DC-AC Converter System

In this paper, the internal stability and dynamic stability of the aeronautic AC-DC-AC converter are studied. The harmonic state-space (HSS) equation of the DC-AC inverter and the sequence impedance of the AC-DC rectifier are derived based on the dynamic phasor theory. Firstly, the distribution of the characteristic roots of the HSS equation with consideration of different dynamic phasor orders is illustrated. The simulation results show that the higher harmonic components are easy to cause the instability of the converter system. Secondly, the linearization model of the switching functions of the rectifier is established under the condition of small voltage perturbation. According to the mapping relationship between the input-terminal and output-terminal of the auto-transformer and the rectifier bridge, the analytic expression of the input sequence impedance for the rectifier system is derived. The Nyquist curve and zero-pole distribution indicate that the sequence impedance model derived with the dynamic phasor can effectively reveal the dynamic impedance characteristics of the converter system. Thus, the methods proposed in this paper provide a reference for the rapid analysis and calculation of the stability of the dynamic converter of the aeronautic AC-DC-AC Converter System.