Broken bar fault diagnosis on various control methods of vsi fed induction motor drives

Abstract

Squirrel Cage Induction Motor (SCIM) occupies 85% of the industry because of reliability, robustness, and low cost. For the energisation of Induction Motor (IM), the constant frequency supplies or adjustable speed AC drives are preferred. So, it is essential to maintain IM healthy to continue the seamless operation of the industries. There are two major categories of faults in the machine: a) electrical faults such as stator side 30-40% and rotor side 5-10% and b) mechanical related faults like bearing faults and air-gap eccentricity fault 40-50%. Rotor failures result from a mixture of different stresses that occur on the rotor. Broken Rotor Bar (BRB) fault produces fluctuations and reduces the amplitude of the torque. As a result, they can develop mechanical vibrations and more significant fluctuation, that leads to harmful effects on the machine. Increase in the number of broken bars creates a high impact on the rotor side during the open-loop drive system. To avoid the above issues, the fault detection and diagnosis method play a vital role to protect the AC drives.In recent years, the high-performance Voltage Source Inverter (VSI) fed variable speed AC drives, mainly IM drives have been influenced by different control methods. The extensively used methods are Voltage/Frequency (V/F) control, Vector based Indirect Field Oriented Control (IFOC), and Direct Torque Control (DTC), as each method has its unique features. The V/F control method is the most uncomplicated drive because it needs less knowledge of parameters. The IFOC provides the same dynamic torque control performance, allowing quick response near step changes in motor torque. DTC offers a more accessible control structure with identical dynamic control as that of IFOC.Hilbert Transform (HT) is a time-frequency signal processing tool, and it is one of the predominant high-frequency rotor fault diagnostic techniques. By using HT, low sensitivity to different motor loading performance can be analysed. newline