Investigação das estratégias de controle DTC e IFOC para acionamento de motores de indução trifásicos

Abstract

Among the eletric motors, the induction motor stands out in therms of robustness, overload capacibility and simplificated construction. However, because of its complex operation, its application in high perfomances functions were limitated at first. From vector control and its approach, verious methods were proposed later and among these, two of them are the focus of this work: Indirect Field Oriented Control (IFOC) and Direct Torque Control (DTC). On IFOC, from the motor slip estimation is possible to make the reference system, where the quantities is analyzed, alignment so that the flux and torque control is decoupled. This method allows using linear control methods, such as PI controllers. For DTC, a non linear control method, through the stator flux estimation and flux torque references, a control table is used to drive the inverter’s transistors, aided by two hysteresis controllers. On this work, the induction motor modeling were studied so that the project and applications of the methods can be done in simulation. Once the effectiveness of the methods is confirmed, these were implemented on a drive platform. With the results, the methods were compared and discussed for better application with some performances parameters in mind such as response time, torque and currents ripples. While the IFOC, a linear control method, presents smoothness in its drive, it does have a slower response when compared to the newer method DTC. This technique does have a short response time with high accuracy control. Although, this non-linear method generates torque and current ripples while driving. To choose the best technique for each high performance application, the pros and cons must was considered. It can be concluded that, with respect to speed response, the DTC strategy has an advantage over IFOC. Although, with respect to stability and ripples in its responses while driving, the strategy IFOC stands out over the DTC strategy. Others performance aspects was approached for a better comparision between these two techniques.