International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: 03 204 119703-02-5454 IJET-IJENS @ June 2011 IJENS I J E N S Implementation of a Passive Tune Filter to Reduce Harmonics in Single Phase Induction Motor with Varying Load M. Shuja Khan*, I. Intesar, M. S. Raheel, M. Babar Ali, U. Asad, M. Farid, U. Ahmed, P. Ali Ayub Department of Electrical Engineering, COMSATS Institute of Information Technology, Lahore, Pakistan Email: *shuja@ciitlahore.edu.pk Abstract - Technology has its limitations and problems. Power generation and transmission systems also have some intricacies. Major hindrances involved in achieving efficient power transmission are the effect of harmonics that distorts the required waveform. The paper proposed a methodology that detects the harmonics present in the current drawn by the induction motor by analyzing current waveform through oscilloscope. And then design the harmonic filter using MATLAB programming and implement it on a single phase induction motor for removing the harmonics. The starting and overall performance of motor is important to all the applications. When the motor is started, it draws high starting current. This high current cause’s dip in the voltage therefore it is necessary to take into account the remedial measures to remove harmonics in single phase induction motor. Keywords ― Induction Motor, MATLAB, Filters, Harmonics. Modeling. I. INTRODUCTION Induction motor having single phase is a single-phase motor. In single-phase induction motors the stator windings consist of one phase, so there is no rotation of magnetic fields. There is no starting torque in a motor because of the absence of rotating magnetic field of stator. Single phase induction motors are a common part of home and industrial appliances which cause the phenomenon of harmonics in the system they are integrated with. Other major sources include non linear loads like a diode, saturated transformers and more importantly large rectifiers and Adjustable Speed Drives (ASD’s) [1]. Power systems are designed to operate at frequencies of 50 or 60 Hz; but, some types of electronic loads produce currents and voltages with frequencies which are integer multiples of the 50 or 60 Hz. These higher frequencies are known as power system harmonics. Today, harmonics are mostly created by electronic loads such as adjustable-speed drives (ASD) and inverters. However due to many advantages like efficiency and controllability, almost all the power equipments from low voltage appliances to high- voltage converters contain power electronic loads. Hence due to more use of electronic loads, power system harmonics is the big problem [2]. Although the starting current of single phase induction motors also causes performance and efficiency loss but this problem has been handled effectively in past researches, one of which suggests the use of classical LC circuit integrated with the capacitor run induction motor to reduce starting high current and thus improving the efficiency [3]. Disturbance in the power system is often caused by non- linear loads. The non-linear load draws non-sinusoidal periodic current even when sinusoidal voltage is applied to these loads. The current waveform becomes very complex due to the type of load and its interaction with other components of the system. . As an example, consider the supply voltage and current of a three phase variable Speed drives [4]. There are a number of ways to overcome the problems of power quality and Harmonics. Reduce mutual coupling between circuits by shielding. [5]. Harmonics can be reduced and eliminated through transformer connections. A separate delta connected tertiary winding is usually wound on high power transformers to provide a path for circulating triple harmonics to flow. However, losses increase because of circulating current in the delta connection [6]. Generator voltage harmonics can be reduced by the use of distributed windings [6]. Install power harmonics filters. The purpose for power harmonic filters installed at the connection of power electronic equipment to the power system is to bypass the harmonic current generated by the equipment from entering the power system [6]. Harmonic injection can be used. For power systems serving non-linear loads, a power electronic converter generates harmonic current demanded by the loads. That eliminates the need for such current to flow in the power system [6]. Install the active filter; an active harmonic filter boosts voltage throughout each half AC cycle, providing the load with a regular voltage waveform [7]. This paper implemented a modern technique that is to design a filter that install in series or in shunt with the induction motor to reduce harmonics during starting of the motor as well as at fully loaded condition. Four different approaches are implemented to overcome harmonics induced from the motor and finally concluded a technique that suits the best above all. II. PROPOSED METHODOLOGY This paper proposed a filter design to reduce the harmonics generated by the single phase induction motor with varying load. Fig.1 describes the complete flow chart of the proposed system. How the frequency components of the input signal accompanied with harmonics are analyzed using Matlab tool. After analyzing the signal behavior, different approaches have been made to design a filter