Aimed at reducing adjusting time of the maximum power point tracking(MPPT)of photovoltaic system when the environment suddenly changes

fuzzy control was introduced to the segmentation variable step algorithm.This algorithm takes duty cycle as the control variable directly

applies the fuzzy control to make the system working point track to the maximum power point(MPP)area rapidly when the photovoltaic system power changes violently.Otherwise

the step size will be determined according to whether the power quadratic differential is positive or negative.A large step size will be adopted to make the system approach the MPP quickly if the power quadratic differential is positive

and an adaptive step size will be adopted to make the system work at the MPP stably if the power quadratic differential is negative.Moreover

the MPPT effects of the photovoltaic system employing the segmentation variable step algorithm and fuzzy variable step algorithm were compared when the illumination intensity changes suddenly

through simulation test.The experimental results show that

when the environment changes suddenly

the above improved algorithm has better tracking performance in adjusting time and stability.