Voltage Stability Analysis and Sliding-Mode Control Method for Rectifier in DC Systems With Constant Power Loads

Voltage stability draws more and more attentions in dc systems due to the high penetration of constant power loads. This paper gives comprehensive analysis for the voltage stability and proposes a sliding-mode control method to enhance the voltage stability margin of dc systems. First, by the impedance-based stability analysis approach, the voltage stability of the three-phase rectifier serving as the source converter is examined when interacted with tightly regulated load converter. The dynamic input characteristics of the load side converter are investigated to find the relationship between the negative incremental impedance and the output power of the load converter. Second, a new sliding-mode control method is proposed to achieve the large-signal stability. Lyapunov function is used to ensure the stability of the proposed controller. Finally, the effectiveness of the proposed control method is verified by simulation results.