Speed control of electrical drives, based upon fuzzy logic — A synthesis

The paper presents a synthesis of some author´s activity. A speed control system for dc drives, based upon a PI fuzzy controller with integration at the output, with a simple rule base with only 9 rules is developed, analyzed and simulated. The sum-prod inference method is used with the center of gravity defuzzification. The performance criteria of the fuzzy control system are compared with the performance criteria of a conventional speed control system based upon a linear PI controller. By simulation is shown that the fuzzy control system has better performance criteria and it is more robust at the parameter identification errors than the conventional linear PI controller. Also, a method to analyze the stability based upon circle´s criterion is developed. This method is based upon an algebraic property of the fozzy controller, presented in the paper.