State feedback fuzzy control solution for BLDC drives

The paper proposes a cost-effective Takagi-Sugeno state feedback fuzzy controller (T-S SFFC) meant for speed control of brushless direct current (BLDC) drives. The simplified process models of BLDC drives at several operating points are characterized by second-order linear dynamics with an integral component and variable parameters. The discrete-time dynamic Takagi-Sugeno fuzzy models of the process are derived by the modal equivalence principle to merge the discrete-time linear process models in the rule consequents. The parallel distributed compensation is applied to obtain the state feedback gain matrices in the rule consequents of the T-S SFFC which shares the same inference engine, defuzzification method and input membership functions with the Takagi-Sugeno fuzzy models of the process. The T-S SFFC merges a set of separately pole placement-based designed local linear state feedback controllers in the rule consequents. A system of linear matrix inequalities is solved in the design of the T-S SFFC to guarantee the global stability of the fuzzy control system.