Unified Constant-frequency Integration control of Three-phase Grid-connected Inverter for Alternative Energy Power Generation

Abstract-A new control approach for three-phase gridconnected inverters is presented. The inverter stage is a standard three-phase half bridge. During each 60° of line cycle, the three-phase half bridge can be de-coupled into parallel-connected a dual-buck inverter. Based on Onecycle control, a Unified Constant-frequency Integration controller (UCI) is proposed for the dual-buck inverter. The controller is comprised of an integrator with reset, along with some linear and logic components. No multipliers are required. Low current distortion and unity-power-factor are achieved in the control loop. Its simplicity and performance make it a great candidate for grid-connected alternative energy generation. The alternative energy source can be fuel cell, photovoltaic, wind power, etc. The current injected to the grid are sinusoidal.