A Cost-effective Three-phase Grid-connected Inverter with Maximum Power Point Tracking

Solar energy is desirable due to its renewable and pollution-free properties. In order to utilize the present utility grid infrastructure for power transmission and distribution, grid connected dc-to-ac inverters are needed for solar power generation. However, previously proposed voltage source inverters with a two-power-stage structure or a cascaded structure increase the circuit complexity, power losses, and system cost. In addition, conventional maximum power point tracking (MPPT) methods usually need power calculation and complex logic judgment, so expensive multipliers and/or microprocessors are needed. This leads to high inverter capital cost, which becomes a major barrier for the wide use of solar power generation. A cost-effective MPPT method integrated within the one-cycle control (OCC) core is proposed in this paper. When integrated with a three-phase boost type inverter, the proposed method tracks MPP with good precision, and solar power is converted into three-phase ac power with a single power stage. There is no power calculation in the controller, which yields a simple and cost-effective solution. Experiments have been carried out with a photovoltaic source to verify good performance