A Current Limiting Method with Distortion Suppression for Stand-Alone Three-Phase Inverter

Current limiting control is the key to continuous power supply of inverters. The inverters are generally switched to the current limiting mode to limit the fault currents when short-circuit faults happen. However, the fault currents will be distorted seriously due to the zero-current clamping effect as analyzed in this paper. In order to limit fault currents and suppress the fault current distortion, this paper presents a novel current limiting method. In the proposed method, the hardware current limiting circuit and the software current limiting scheme can immediately limit fault currents in cooperation. The switching frequency switchover strategy can effectively mitigate the fault current distortion. The purpose of the method is to prevent power devices from being damaged, and to ensure breakers to reliably operate and effectively support the subsequent relay protection. Simulation and experimental results verify the feasibility of the proposed method.