This paper presents a comparative study between direct torque control (DTC) and predictive torque control (PTC) of Axial Flux Permanent magnet Machines (AFPM). In conventional DTC method for permanent magnet machines, only six actives voltage vectors of inverter are used to control torque and flux of machine. But in predictive torque control, in addition to six active voltage vectors, zero voltage vectors are used to control machine. So number of voltage vectors to control AFPM increases that leads to lower ripple of torque and flux. In predictive torque control, the response of torque and flux are computed for all possible switching states of inverter at every sample time according to discrete time model of machine, and then the switching state that optimizes ripple of torque and flux, will be applied in next discrete-time interval. Simulation results which compare the results of implementation of both methods and confirm the good performance of the proposed predictive torque control are presented.

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This paper presents a new predictive direct torque and stator flux control of a permanent magnet synchronous machine by a matrix converter. Unlike conventional direct torque control for permanent magnet machine that only 18 actives voltage vectors of matrix converter with fix direction are used, in the proposed predictive control all 27 possible switching states including fixed direction voltage vectors, zero voltage vectors and also rotational voltage vectors are used to control the machine. So, the number of voltage vectors to control increases that leads to faster dynamic torque response and lower ripple of torque and flux. Furthermore, an extension of the predictive control is proposed to make it more efficient. Simulation results which confirm the good performance of the proposed methods are presented.