Hybrid maximum power point tracking method with variable step size for photovoltaic systems

A hybrid maximum power point tracking (MPPT) method with variable step size for photovoltaic (PV) systems is proposed. The proposed MPPT method combines a new modified fractional open-circuit voltage (FOCV) method and the current sensorless method with auto-modulation (CSAM) to achieve fast and accurate tracking. This method not only has fast tracking but also automatically adjusts the step size according to the conditions of PV array. A modified FOCV is designed to move the operating points fast to approach the maximum power points. Afterwards, the CSAM is used for fine tuning, thus the PV system with the proposed MPPT can produce a stable and maximum possible output power. The theoretical analysis of the proposed MPPT is provided, and the laboratory prototype was constructed based on a boost converter with only a single voltage sensor. The simulation and experimental results are presented to verify the system performance.