Optimization of the maximum power point tracking method for peak-current controlled flyback micro-inverter

The Maximum power point tracking (MPPT) algorithms are widely used in micro-inverters to maximize the PV panel's output power. The perturb and observe (P&O) algorithm is the most commonly used method due to its simple implementation. However, since the switching frequency of the BCM micro-inverter is variable, the switching duty ratio or the panel voltage could not be simply used as the perturbed signal. In this paper, it is shown that the current reference amplitude value can be utilized to implement the P&O function. Besides, an improved adaptive-step method is also proposed to alleviate the tradeoff problem between faster response and steady-state oscillations. The design considerations of some parameters like sampling interval and perturb step limitations are also given in this paper. Simulation and experimental results are provided to validate the proposed techniques.