Current sensorless maximum power point tracking in a cascaded h-bridge photovoltaic power system

Multilevel Cascaded H-Bridge (CHB) converters have attractive features for the implementation of large scale photovoltaic systems. They can be directly connected to high voltages and the multilevel voltage synthesis reduces the harmonic distortion introduced. In addition, they have individual DC links ideal for connecting photovoltaic arrays. Existing high performance voltage balancing techniques can also be adapted to integrate Maximum Power Point Tracking (MPPT). However, MPPT schemes typically require a measurement of the generated photovoltaic power to operate, leading to a significant number of current sensors in a multilevel system. This paper considers a 19 level three-phase CHB converter photovoltaic power system without sensing the photovoltaic array current for MPPT. The converter control strategy is used to infer the information necessary for the MPPT algorithms to operate. Simulation results are presented to demonstrate the performance of the proposed implementation of MPPT.