Scaling factor design issues in variable step size incremental resistance MPPT in PV systems

Conventional maximum power point tracker (MPPT) uses fixed step size perturbation in order to track the maximum power point (MPP), therefore the tracking efficiency has decreased due to steady state oscillations around the MPP. Recently, many techniques have been developed proposing new approaches in the field of variable step size MPPT to overcome the shortcoming of the fixed step size techniques. These approaches update the controlling parameters adaptively using a convenient scaling factor (N) to pick the MPP. However most of them need some prior analysis in order to design the appropriate value of N, which control the hall performance of the variable step size tracker. In this paper, a new approach has proposed to design N. this approach has been develop based on the overall small signal model of the PV system around the MPP. Therefore using linear control techniques the bounded value of the scaling factor has been calculated. The validity and the feasibility of the proposed analysis have been verified using MATLAB SIMULINK toolbox, and also experimental using digital signal processor (DSP).