A DC-Side Sensorless Cascaded H-Bridge Multilevel Converter-Based Photovoltaic System

In this paper, a cascaded H-Bridge (CHB)-multilevel converter (MC)-based photovoltaic (PV) system with no voltage or current sensors at the dc-side is proposed. Eliminating the dc-side sensors simplifies the hardware, leading to lower cost and higher reliability of the PV system. A novel scheme estimating the capacitors' voltages from the ac output voltage of the inverter is developed. The scheme allows replacing all dc-side voltage sensors by a single-voltage sensor at the ac-side of the converter. Furthermore, the dc current sensors, conventionally required for the maximum power point tracking (MPPT), are also eliminated. Instead, the outputs from the capacitors' voltage control systems are utilized for the MPPT. The effectiveness of the proposed dc-side sensorless system is experimentally demonstrated on a 2-kW single-phase seven-level CHB converter-based PV system.