10 kV, 120 A SiC MOSFET Modules for a Power Electronics Building Block (PEBB)
Stability analysis of modern three-phase AC power systems is performed using small-signal impedances identified in a synchronous reference DQ frame. A single-phase series voltage injection is used to perturb AC and DC systems in order to perform small-signal impedance identification. This paper proposes using an interleaved cascaded H-bridge converter to generate a voltage perturbation in series with the power system. Special attention is focused on the design procedure, including the selection of inductor and capacitor values, in an attempt to optimize the converter's performance and maximize the injection range. Decoupling control is proposed to regulate AC injection voltage, providing a robust and reliable strategy for regulating series volt-age injection. Furthermore, low bandwidth DC voltage control is incorporated into the control, assuring DC voltage control for each H-bridge module. Analytical expressions, which describe the control procedure, are derived and presented in the analysis. The proposed converter is extensively simulated using a switching simulation model, and subsequent results show the excellence of the developed design procedure. The simulation model and hardware prototype results verify the effectiveness of the proposed series voltage injection solution.