Effects of different slopes of membership functions on the fuzzy control of DC-DC converters

The triangular membership function has been primarily considered in fuzzy control for DC-DC converters. By changing the slope of the triangular membership function, its influences on the performance of the converters are studied by simulations. The simulations show that, for fuzzifying the change of error, increasing the slope of the triangular membership functions can significantly reduce the initial current of the controlled converters. In the defuzzification procedure, increasing the slope of the triangular membership functions can slightly lessen the initial current. Increasing the slopes for both the membership functions for fuzzifying the change of error and the membership functions for defuzzifying the change of duty ratio (output) can further improve the starting performance of the converter. But increasing the slope of membership functions for fuzzifying error shows worse performance in the fuzzy control of DC-DC converters.