The matrix converter is a new generation of power electronic converters and is an alternative to back-to-back converters in applications that dimensions and weight are important. In this paper, a simple control algorithm for a three-phase asynchronous motor based on a direct torque control technique, which is fed through a three-phase direct matrix converter, is presented. For direct matrix converters, 27 switching modes are possible, which using the predictive control technique and for the different modes of the matrix converter, the motor behavior is estimated at the next sampling interval. Then the objective function is determined and the optimal possible mode is selected. Finally, the best switching mode is applied to the direct matrix converter. In order to evaluate the proposed method, simulation of the system in Matlab/Simulink software environment is performed. The results show the effectiveness of the proposed method.
This paper presents a predictive torque and flux control algorithm for the synchronous reluctance machine. The algorithm performs a voltage space phasor pre-selection, followed by the computation of the switching instants for the optimum switching space phasors, with the advantages of inherently constant switching frequency and time equidistant implementation on a DSP based system. The criteria used to choose the appropriate voltage space phasor depend on the state of the machine and the deviations of torque and flux at the end of the cycle. The model of the machine has been developed on a d-q frame of coordinates attached to the rotor and takes into account the magnetic saturation in both d-q axes and the cross saturation phenomenon between both axes. Therefore, a very good approximation of this effect is achieved and the performance of the machine is improved. Several simulations and experimental results using a DSP and a commercially available machine show the validity of the proposed control scheme.