A novel single-stage solar inverter using hybrid active filter with power quality improvement

Grid-connected photovoltaic (PV) systems with power electronic interfaces are becoming popular since they do not contribute to environmental pollution. However, one of the issues with grid feeding inverter is the requirement of high dc-link voltage. In view of this, single stage solar inverters using conventional inverters may not be suitable, since they require input dc voltage higher than the peak of line-line voltage. Therefore, two-stage topologies which typically consist of one dc-dc power stage to boost the dc voltage, in addition to a Current Source Inverter (CSI) for dc-ac conversion are reported for applications where the input voltage is lower than the peak of the output voltage. However, this increases the circuitry complexity. In addition, CSI requires bulky inductance in DC side, which increases losses. Hence, In this paper a novel single stage solar inverter using shunt active hybrid filter is presented. The inverter features a single power stage, with dc link voltage less than the peak line-line voltage, which will reduce the power losses and circuit complexity. In addition, the proposed solar inverter can also provide harmonic filtering to improve the power quality of the system. The operation and control of the novel single stage solar inverter for active power control and harmonic control is described. A detailed analysis, simulation along with the hardware results for the proposed single stage solar inverter is presented. Experiments are carried out on a 1.5kW laboratory prototype which demonstrated the performance of the inverter for active power control and harmonic compensation. The proposed inverter has an efficiency of 94%, compared to an conventional active filter based solar inverter´s efficiency of 90%. Moreover, it has been shown that the switching ripple injected by the proposed solar inverter is just half of the conventional active filter based solar inverter.