说明：  This paper investigates the effect of membership functions in the fuzzy control of a chopper fed dc drive. A Sugeno type fuzzy controller for closed loop control of dc drive fed by buck type dc-to-dc converter is designed and considered for evaluation. The controller is used to change the duty cycle of the converter and thereby, the voltage fed to the armature of the separately excited dc motor to regulate the speed. Sugeno type fuzzy controller is selected for evaluation, as it is easy to implement in any embedded microcontroller or DSP processor. The membership functions selected for evaluation are triangular, trapezoidal, Gaussian, bell shaped and PI functions. Above evaluation is done considering both five and seven linguistic sets for error and change in error. The results of the simulated performances are compared. The triangular membership function shows better performance compared to other membership functions