A low cost solution to grid-connected distributed generation inverters

A low cost utility interactive inverter is valuable to the residential PV or fuel cell distributed generations. This paper presents a low cost solution to the single-phase grid-connected inverters, including the inverter topology, filter structure, and the current control methods. The reason for choosing the proposed converter topology is given. A novel current control method using the combinatorial feedback of the grid current and the capacitor voltage is introduced for the inverter, so that a low cost non-damped or slightly damped LCL-filter can be employed to attenuate the switch frequency current ripple and the system can be optimized easily for minimum steady-state error and current harmonic distortions, as well as the system stability. The characteristics of the inverter system with the proposed controller are investigated. Simulations and experimental results on a 5 kW fuel cell inverter are provided to verify the proposed solution and its control strategy.