Elimination of position sensor in direct torque control of brushless trapezoidal axial flux synchronous motor

In this paper, a novel algorithm is proposed in order to direct torque control of axial flux permanent magnet (AFPM) motor without position sensors by using back-EMF. Utilizing back-EMF to estimate the rotor position and speed is one of the few methods that have satisfying performance in low speeds. This method does not require a high speed processor. Capable of controlling the motor over a wide speed range, this method is suitable for hybrid electric vehicles. This method directly controls the wheels and due to its direct performance, it has more efficiency and makes it possible to have a compact circuit. This control method has a relatively quick response to torque variations but the torque ripple is relatively high, which is normal for this method. Moreover, this method is dependent on the machine's internal parameters. Simple implementation and reduced amount of required calculations are the other advantages of the proposed method. The simulation results will verify the proper operation of this algorithm.