A Sensorless Control of H-bridge Multilevel Converter for Maximum Power Point Tracking in Grid Connected Photovoltaic Systems

There is a high development of grid-connected photovoltaic systems that utilize static converter which influence the efficiency of the system. The energy conversion depends on the architecture of the converter, different solutions are available and H-bridge multilevel converters seem to be an optimal solution also for the power quality. It is important to utilize a proper architecture of converter but also to set up a control optimized to have the energy conversion at maximum efficiency. The persistence of the maximum efficiency condition is related, depending on the atmospheric conditions, to the tracking of the Maximum Power Point (MPP) by modifying the operating conditions of the system (Maximum Power Point Tracking -MPPT). In the paper is proposed a sensorless control set up to deliver the maximum power to the grid in presence of variations of incident irradiation on the photovoltaic arrays. The control technique is presented and validated by simulation implemented on a photovoltaic system with H-bridge 5-levels converter. The simulation results confirm that the control is able to effectively track the MPP and to stabilize immediately in the new steady-state condition.