The fuzzy logic-based stator-flux-oriented direct torque control for three-phase asynchronous motor

This article proposes a Takagi-Sugeno fuzzy logic-based (TS-FLB) controller applied to the stator-fluxoriented direct torque control (SFO-DTC) scheme. The conventional SFO-DTC scheme has two PI regulators to generate the reference stator voltage vector necessary to maintain the load. The objective is to reduce the quantity of these controllers, hence we propose a single TS-FLB controller to substitute both PI regulators. The rule base for the proposed TS-FLB controller is defined in function of the stator flux error and the electromagnetic torque error, and it utilizes trapezoidal and triangular membership functions (MFs) for the fuzzification of its inputs. Constant switching frequency and low torque ripple are obtained using the space vector modulation technique. The simulation and experimental results show that the TS-FLB controller obtains a decoupling torque and stator flux control and low torque ripple. These results were obtained for various operating conditions such as step change in the motor load, speed reversion with no load and the application of an arbitrary speed profile. These results show that the TS-FLB controller achieves a good performance as expected, validating the proposed scheme. © Brazilian Society for Automatics-SBA 2013.