Perturb and Observe with Momentum Term applied to Current Referenced Boost Converter for PV Interface

The Photovoltaic (PV) current follows the same direction as the perturbed duty cycle for a DC-DC converter interfaced PV system. Hence current referenced control is well suited for Maximum Power Point Tracking (MPPT). A small signal model for a Boost converter with PV is developed, which gives the input current to duty cycle control signal transfer function in order to design the controller. In addition to the inner current control loop, an MPPT control loop is added to track the Maximum Power Point (MPP). The standard Perturb and Observe (P&O) Algorithm has an inherent trade-off between dynamic performance during rapidly changing irradiation conditions and oscillations about the MPP. To overcome this problem a Momentum term is introduced in the perturbation of the reference control signal in order to accelerate tracking and to reduce oscillations. The Momentum term which is a scaled version of the previous perturbation can be easily implemented in the existing P&O algorithms, with only slight modification and almost no change in computational effort.