Hybrid Modulation Technique for Grid-Connected Cascaded Photovoltaic Systems

In this paper, a control method based on the derivative of power is introduced for single-stage single-phase grid-connected cascaded H-bridge (CHB) photovoltaic inverters. The proposed scheme uses solar arrays derivative of power with respect to current to track maximum power point of each array individually. Using this method along with hybrid modulation technique allows utilization of CHB cells up to their full potential. The control system has a simple structure, and is inherently able to stabilize the system under heavy mismatching conditions where the modulation index goes higher than unity. The effectiveness of the proposed technique is verified by simulation and experimental results.