基于电压-电流滑模控制的三相四桥臂有源变换器策略

A three-phase, four-arm cascaded H-bridge (CHB) topology is proposed to reduce the power-electronic hardware required by conventional three-phase, direct-hanging flexible arc-suppression devices (FASDs), in which each arm is subjected to the line voltage. By limiting the per-arm voltage stress to the phase-to-ground level, the required cascade count is reduced. To address the limitations of flexible current arc suppression method based on proportional–integral–derivative (PID) control and linear active disturbance rejection control (LADRC)—which exhibit nonzero steady-state current-tracking error under high-resistance ground faults—as well as those of traditional flexible voltage arc suppression method—which become unreliable under low-resistance faults due to line-impedance voltage drop—a flexible fusion arc suppression method based on sliding-mode control with an exponential reaching law (SMC-ERL) is developed. In this method, the device output current and the neutral-point voltage are regulated in parallel, simultaneously suppressing ground-fault current and voltage and mitigating the effects of fault resistance and line-impedance voltage drop. The SMC-ERL strategy enables fast and accurate tracking of the compensation-current reference. The effectiveness of the proposed approach is validated by simulation and experimental results.