Controle de torque sensorless de um motor de indução com injeção de sinal de alta frequência no eixo de quadratura

Abstract

In the presented work, a sensorless method based on the injection of a high-frequency voltage signal was investigated. A 1:5cv motor was used as a testbed, driven by a commercial inverter according to the Field-Oriented Control method. Experimental observations indicated that a modification on the spatial direction of the injection signal is advantageous when compared with the original proposed method. The differences between the strategies were modelled, as was the high-frequency impedance modulation mechanism of the machine’s magnetic circuit. An identification algorithm was used to determine the dynamical characteristics of the extraction and processing of the injected signal. It was observed that the identified transfer function presents a variable gain, which is sensible to the value of the stator quadrature current. A torque control loop was obtained successfully. The poposed technique was applied to a sensorless torque control scheme, allowing the motor to follow step and torque references while the motor flux angle was calculated by the estimation method. The machine successfuly produced an output torque between 1;0N:m and 2;5N:m with an angular estimation error of about 50o (electrical).