Modeling and vector control of three-phase induction motor when two phases of the stator are open circuit

Abstract

Variable Frequency Drives (VFDs) are used to provide reliable dynamic systems and significant reduction in usage of energy and costs of the induction motors. Over the past decades, many control techniques have been proposed for induction motors drive system. One of the most well-known control method for controlling the speed and torque of the induction motor is Field-Oriented Control (FOC) technique. Modeling and control of faulty or an unbalanced three-phase induction motor (two stator phases open-circuit) is obviously different from healthy three-phase induction motor. Using conventional FOC for faulty three-phase induction motor, results in a significant torque and speed oscillation under fault conditions. Modeling and vector control of a faulty three-phase induction motor is extremely important in some critical applications, such as traction drive in military and space explorations, to ensure fault-tolerant operations. This research presented a new method for modeling and control of three-phase induction motor under fault condition (two-phase open circuit fault). The proposed method for modeling and vector control of faulty induction motor are based on d-q and Rotor FOC (RFOC) methods. It is shown the d-q model of faulty three-phase induction motor has the same structure of equations as the balanced three-phase induction motor. Therefore, by using some modifications to the conventional controller such as FOC, a novel technique for three-phase induction motor with two stator phases open-circuit (faulty three-phase induction motor) has been developed. A comparison between conventional and modified controller showed that the modified controller has been significantly reduced the torque and speed oscillations.