Maximum torque high speed microprocessor based control of induction motors

In the paper a novel method for high speed maximum torque control of induction motors is suggested. It is based on the condition that in every moment, for every speed the torque should be maximum or at least near the maximal value. This is achieved by calculation of the optimal frequency of the supply voltage, which is function of the rotation speed n in the moment and the parameters of the motor. The calculations can be done on-line by an embedded microprocessor (or fast one-chip controller) or in advance, off-line, for a sufficient number of n and the results are introduced into the memory of the on-line controller. The second method is suboptimal but faster and should be applied when the controller is not fast enough compared with dynamical characteristics of the object, driven by the induction motor. In the paper the algorithm for maximum torque control and computer simulation program for a concrete induction motor are given. A theorem is proven concerning one of the suggested methods of control.