A novel fuzzy controller for DC motor drives

Fuzzy control theory is somewhat new to the power electronics community. The paper describes a method of fuzzy logic in a speed control system that uses a phase-controlled bridge converter and a separately excited DC machine. The method is unique in that it is a straight-forward method of creating a mathematical model that has been successfully applied to a variety of membership functions. Moreover, the current loop is replaced by a prediction method based on the DC motor equations. Performance of the control algorithm is evaluated through a laboratory implementation as well as a simulation implementation. A faster and more efficient software/hardware arrangement are merged for implementations. Load disturbances are generated by variable resistances connected to the DC generator. The smoothness of response, response time and disturbance due to load torque are discussed. To demonstrate the effectiveness of the fuzzy logic, the conventional controllers PI and IP are replaced and are applied on the same model. The versatility of the motor/controller arrangement is displayed through real-time plots of the controlled states