Control-Action Optimization in Synchronous Reluctance and Inductor Alternating-Current Drives

An algorithm for optimizing the control action in the torque contours of synchronous reluctance and inductor ac drives is described in this paper. It allows one to search for an optimal principle for electric-drive operation that is suitable for any electromechanical converter with magnetic asymmetry of the rotor. The harmonic composition of phase currents serves as the optimization parameter. The optimization criteria are specific electric and magnetic losses. The functional relations presented by a set of equations describing the mathematical model of an object for optimization are given in analytical and numerical forms. The analytical case implies the optimization calculations at the following assumption: the drive is unsaturated, the magnetic conductivity of steel is infinite, and there are no scattering currents. The optimization data are to be refined via the numerical method, in which the electric drive is to be as a system with distributed parameters. An example of synthesis of the best configuration of phase currents through the torque contour of an electric drive with a synchronous independent-excitation reluctance machine is considered as well. The optimum current shape is established to be a trapezoid, while the time of the control signal variation is determined by the time after which the rotor-pole edge overcomes a distance equal to a phase area of the stator winding. The algorithm for control-action optimization proposed in this work enables one to increase the energy efficiency of synchronous reluctance and inductor ac electric drives.