Stability analysis of the shunt regulator in PCU with describing function method

The shunt regulator (SR) is a key part of the power conditioning unit, which is a kind of power supply system for spacecrafts. SR is a strong nonlinear system due to the hysteresis control adopted, but the stability analysis for SR is still ground on the approximate linearization. In this paper, a novel stability analysis method for strong nonlinear systems is proposed based on describing function, which is used to model the nonlinear link of SR. Further, two different conclusions about the stability of SR are drawn, obtained by the approximate linearization method and the describing function (DF) method, respectively. Finally, the simulation and experimental results prove the correctness of the stability analysis method proposed in this paper and discover the limitation of the linearization method for analyzing the stabilities of the nonlinear systems.