Problems of stator flux oriented torque controllers for the interior permanent magnet motor

This paper reviews the problems associated with the implementation of the so-called direct torque control (DTC) strategy for the interior permanent magnet motors. Such control techniques are increasingly drawing interest because of the simplicity of its structure, elimination of the current controllers and hence their inherent delays and the elimination of the rotor position sensor. The latter advantage is perhaps the main impetus for considering this new approach of control. The sources of difficulties, namely, the stator resistance variation, the offsets in measurements and the error in the detection of the initial rotor position are discussed.