Improved Single-Loop Voltage Control with Stability Enhancement Using Second Order Generalized Integrator (SOGI)

摘要

Single-loop voltage control of LC-filtered inverters has been investigated for many years because of the low cost and high reliability. However, the conventional single-loop resonant control is only possible if the resonance frequency of LC-filter higher than one-sixth of the sampling frequency. To expand stability region and optimize performance of LC-filtered inverters, a single-loop voltage control scheme using second order generalized integrator (SOGI) is proposed in this paper. The influences of control structure and SOGI parameters on system stability are discussed. The analysis results indicate that the stability region can be widened when the SOGI compensator is in the feedforward path and the SOGI center frequency is higher than the resonance frequency. A root-loci-based design procedure is applied to determine the controller parameters. Simulation results verify the effectiveness of the proposed scheme and confirm the robustness against system parameters and load variations.