VECTOR CONTROL OF INDUCTION MOTOR WITH MAXIMUM TORQUE-CURRENT RATIO

Abstract

The paper analyzes the dynamic model and vector control of an three phase induction motor. The structure of losses was analyzed and their minimization was set as the basic goal of optimal control. In the case of low speeds, it is recognized that losses in iron can be neglected, which minimized the amplitude of the stator current, as a set condition for minimizing losses. For this reason, the MAPT (Minimum Ampere per Torque) strategy was derived, which gives such coordinates of the stator current vector that achieve the reference torque, with a minimum stator current amplitude. As the system of equa­tions is complex and has no analytical solution, Newton-Raphson's iterative method was used to solve complex equations. First, the principle of operation of the Newton-Raphson method was described, and later, using this method, simulations of stator currents and magnetization inductances in relation to different values of a given torque were obtained.