New Control Strategy for 2-stage Utility-Connected Photovoltaic Power Conditioning System with a low cost digital processor

In this paper, a simple control method for two-stage utility grid-connected photovoltaic power conditioning systems (PCS) is proposed. This approach enables maximum power point tracking control with post-stage inverter current information instead of calculating solar array power, which significantly simplifies the controller and the sensing part. Furthermore, there is no feedback loop in the pre-stage converter to control solar array voltage because the MPP tracker drives the converter switch duty-cycle. This simple PCS control strategy can reduce the cost and size, and can be utilized with a low cost digital processor. For verification of the proposed control strategy, the 2.5 kW two-stage photovoltaic grid-connected PCS hardware that consists of boost converter cascaded with a single-phase inverter has been built and tested