This work deals with the performance improvement study of the direct torque control (DTC) of a Double Star Permanent Magnet Synchronous Machine (DSPMSM) based on Second Order Sliding Mode Control (SOSMC), powered by two voltage source inverters. DTC control using conventional PI regulators has certain disadvantages such as significant flux, torque ripples and sensitivity to parametric variations. To overcome these drawbacks, we apply a new type with more robust regulators such as the second order sliding mode control. Simulation results demonstrate the feasibility and validity of the proposed DTCSOSMC system by effectively accelerating system response, reducing torque and flux ripple and a very satisfactory performance has been achieved.
Robust control often requires some adaptive approach in evaluating systems dynamics to handle parameters variations and external disturbances. Therefore, an error due to dynamics approximation is inevitably added to uncertainties already present in the model. This issue is addressed in this paper, through the combination of two robust techniques, Hinf and synergetic control. These latter are used to ensure reducing tracking error in the overall closed-loop system while guaranteeing stability via Lyapunov synthesis. With the aim of handling parameters variations, an indirect adaptive fuzzy scheme is used to elaborate system model. Simulation studies are conducted to assess the proposed approach on two practical systems, and the results are compared to a sliding mode proportional integral (PI)-based technique. It is to be noted that a large class of systems depicted as control affine systems will be considered in this paper. An induction motor and an inverted pendulum representing, respectively, a linear and a nonlinear system are utilized in this study showing improvement due to the suggested approach, in overall performance over its sliding mode control counterpart.
Finite time convergence based on robust synergetic control (SC) theory and terminal attractor techniques is investigated. To this end a fast terminal synergetic control law (FTSC) is applied to drive a DC–DC Buck converter via simulation and through a dSpace based experimental setup to validate the approach. As robust as sliding mode control, the synergetic approach used is chattering free and provides rapid convergence. Efficacy of the proposed fast terminal synergetic controller is tested for step load change and output voltage variation and results compared to classical synergetic and PI control. Experimental validation using dSpace DS1104 confirms the results obtained in simulation showing the soundness of this approach compared to synergetic and PI controllers.
In this paper, a new control stra¬tegy is deve¬loped; an adaptive fuzzy controller based on Lyapunov's stability theory (AFLC) recalculates the real-time PI-fuzzy gains and combines the advantages of two robust techniques i.e. the fuzzy logic control and the adaptive one. For the new adaptive fuzzy control, we followed two steps: in the first one, a PI-fuzzy controller is designed, in the second step, the gains of a fuzzy regulator are determined. Extensive simulation results are presented to validate the proposed technique. The system is tested at different speeds and a very satisfactory performance has been achieved.