Desenvolvimento de um analisador de parâmetros elétricos e mecânicos de baixo custo aplicado à motores de indução trifásicos

Abstract

Electric motors occupy a prominent position in the ranking of the main inventions that have changed the way human beings live. To achieve its goal of transforming electrical energy into mechanical energy, most electric motors use two magnetic fields: the stator and the rotor. Only through the interaction between these fields does the movement of its shaft become possible, and thus the transformation of energy takes place. In this context, it is essential to measure the parameters, both electrical and mechanical, of the motors, seeking their point of maximum efficiency. Thus, the present work seeks to develop a low-cost electric and mechanical parameter analyzer for a three-phase induction motor, where through the measurement of sensors and data provided by the user, it is possible to verify the value of both electrical and mechanical magnitudes in real time. To achieve the proposed objective, sensors were used to measure current, voltage and speed. For current, the SCT-013-020 sensor coupled to a signal conditioning circuit was used. For voltage measurement a ZMPT101b transformerbased circuit was chosen, and for speed measurement an optically coupled encoder module was chosen for this task. During development, several tests were performed with the selected sensors in order to validate their operation in conjunction with the ESP32 and the aid of the serial monitor tool. In parallel, the parameters of the equivalent circuit of the three-phase induction motor of 0.16 HP and 380/220 V supply voltage were obtained via testing. Subsequently, the graphic software of the work was developed, where the data is presented. The software was developed in the Python programming language. At the end, all the previous steps were put together to build the final prototype, with the inclusion of the sensors with the ESP32 and its communication with the developed software via serial communication. In order to validate the electrical measurements made, their values were compared with measurements made with an IMS PQ600 power analyzer. In this comparison, the voltage and current values presented good accuracy values: the voltage measurements had an average relative percentage error below 1.5%, and the current measurements below 4%. The mechanical measurement of the speed value was compared to a digital tachometer, showing an average relative error percentage of only 0.25%, which is a very good result. Although the torque and efficiency measurements did not have adequate equipment in order to perform a comparison, their values respect the curves provided by the motor manufacturer, indicating plausible results. Thus, with the development of the proposed analyzer, it becomes possible to measure in real time relevant magnitudes of the three-phase induction motor, and the parameters can be viewed in a simple and friendly interface.