A Current Sensor-Less Controller for Grid-Connected Inverters

With mass application of large-scare gridconnected inverters (GCI) in distributed grid, the GCI should avoid resonance with adjacent power electronics equipments and possess low or high voltage ride-through capability, as well as fast current tracking. In addition, the simplicity and cost of GCI controllers should be considered. To meet aforementioned requirements, a new open-loop current controller is proposed in this paper. This open-loop current controller is originated from an ideal differentiator and consists of a proportional, a proportional and a delay (PPD) blocks. Furthermore, the parameters design method of proposed PPD controller is discussed, and the static and dynamic performance of this controller is analyzed under different operation conditions. Compared with conventional PI and PR controllers, the PPD controller owns stability with no condition and reduces cost with no current sensor. Finally, some simulation and experimental results provided verify that the control scheme is feasible and effective.