INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 03, MARCH 2020 ISSN 2277-8616 1140 IJSTR©2020 www.ijstr.org Simulation Studies On Performance Analysis Of Variable Frequency Induction Motor Drive And Incipient Fault Diagnosis Using Wavelets D Venkata Ramana, P.Chandrasekar, R.Sreedhar Abstract: The advent of Power Electronic Devices capable of handling high currents, aided the design of Variable frequency drive (VFD) with Induction motor or inverter fed induction motor drive, which can be characterized by increased reliability and reduced cost. Though taken care highly, such type of drive system is prone for different kinds of faults. When fault occurs, the drive operation has to be stopped if it is designed for general fault detection. The cost of this schedule can be high, and this justifies the development of incipient fault diagnosis. Finding the fault immediately after it occurs is general method of diagnosing the fault. In this case the damage occurs to component or system. If the fault is detected just before it damages the component or system is much better than general fault diagnosis. i.e. diagnosing the fault at developing stage. It saves the system or component from damage. In turn the cost of damage is reduced. This is called the incipient fault detection. In this paper, general fault detection as well as incipient fault detection using the wavelets has been simulated using MATLAB/SIMULINK package. Simulation results are presented showing both the general fault detection and incipient fault detection using the Wavelets. Index Terms: Fast Fourier Transform (FFT), Insulated Gate Bipolar Transistor (IGBT), perfect reconstruction (PR), Sinusoidal Pulse Width Modulation technique (SPWM), Variable frequency drive (VFD), Voltage/Frequency (V/F). Wavelet Transform (WT). ——————————  —————————— 1 INTRODUCTION Implementation of Induction motor, in industries, is used for constant speed operations, but not for variable speed operations. It would be most helpful to industries, if the induction motor is used for variable speed operations, because of its low cost, consistent performance and robust nature. But, the less efficiency and high cost penalty due to low Power factor must be improved when it is used for variable speed operations. The innovative devices in power electronics made speed control of induction motor effective and now they are acceptable in industries for wide speed variation applications with lessen making and maintenance cost. The Inverter fed induction motor drive is used for applications, where the control of the speed or torque is required [1-2]. Inverter controls the speed of the motor by changing the frequency of the input to the machine, thus the Induction motor will run at demanded speed. Mainly, it allows transformation of power from one frequency to another. Also, output frequency can be varied from 10KHz to 30KHz to vary speed for wide range. In diverse applications, such as, mine mills, oxygenating of huge buildings, air blowers which save energy by allowing air volume to match the demand of the application, pumps, the Inverter fed Induction Motor Drive is used. Also, this drive is used in industrial air grade compressors to save the energy consumed [3]. 2 VARIABLE FREQUENCY DRIVE OPERATION The basic building block of Inverter fed Induction motor has AC-DC and DC to AC conversion and connected by DC bus. Whole unit displayed in fig.2.1, i.e. The three-phase full wave diode rectifier considered would convert 3- phase input AC supply into DC supply. The DC link connected at the output terminals of rectifier reduces the ripple contents in the DC output [4-5]. The three-phase inverter section consists of IGBT‘s where the filtered DC supply is being converted into stepped AC supply, fed to the induction motor. It is renowned that the synchronous speed (Ns) of an Induction motor is subjected to the supply frequency [6-7]. Therefore, the speed of the motor can be controlled using VFD is given by, Speed (rpm) (1) Where; f = Frequency in Hz, p = Number of poles. The Table. 2.1, shows the speed variation as frequency changes and it is represented as Frequency Vs speed curve in Fig.2.2, below. Thus, speed of a motor can be conveniently adjusted widely with gradual change of frequency fed to the motor under the condition of constant poles. Pole changing method also gives speed change, but not in gradual change and it requires a physical change of poles to the motor. Therefore, the Inverter fed induction motor drive provides smooth and precise change in speed by changing in the frequency supplied to the motor through sinusoidal pulse width modulation technique (SPWM) implemented in the Inverter. By changing the frequency of the drive, the speed gets varied, so, the term VFD [8]. __________________________________________ • D.Venkata Ramana, Research Scholar, Electrical and Electronics Engineering, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Avadi Chennai 600 062, India. Email : dvnkata@gmail.com • P.Chandrasekar, Professor and Head, Electrical and Electronics Engineering, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Avadi Chennai 600 062, India. Email : hodeee@veltech.edu.in, • R.Sreedhar, Assistant Professor, Electrical and Electronics Engineering, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Avadi Chennai 600 062, India. Email : rsreedhareeeped@gmail.com