IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 7, Issue 2 (Jul. - Aug. 2013), PP 36-40 www.iosrjournals.org www.iosrjournals.org 36 | Page Effect of Inductive Loads on IGBT Based Digital Voltage Controllers Jyoti Lalotra 1 , Saleem Khan 2 , Shavet Sharma 3 , Parveen Lehana 4 1 M.Tech Student, Department of EEE, Arni University, India 2 PhD Student, Department of Physics and Electronics, University of Jammu, India 3 Assistant Professor, Department of EEE, Arni University, India 4 Associate Professor, Department of Physics and Electronics, University of Jammu, India Abstract : Power systems with low harmonic distortion are the key requirement in the modern electronic power systems. Investigations are carried out to analyze the effect of load (combination of resistive and inductive) on the designed IGBT based power system. Harmonic distortions in the input and output voltage of the system are calculated. Input and output voltages waveforms were recorded for all combinations by using signal recording software having duration of 1 s with sampling rate of 16,000. Computer algorithm is designed to calculate Total Harmonic Distortion (THD) in the system. Reduction in the THD was seen in the designed microcontroller and IGBT based power system. Keywords: THD, impedance, power system, load effect, harmonics. I. Introduction Power electronics is need of our which is developing extensively in industry, transportation, residential, commercial and in aerospace application [1-3]. The power semiconductor device was firstly introduced in 1950’s [4] [5]. Nowadays, power electronics becomes important field in electrical engineering as demand of using power electronics devices such as inverter, converter and power supplies in daily life are increasing day by day. Many power electronics converter are on switching mode because the power semiconductor devices can be considered as controllable ideal switches that can turn on and off according to the corresponding gate signal. There are some popular power devices such as Gate-turn-off-Thyristor (GTO), insulated-gate-bipolar transistor (IGBT), Metal-oxide-semiconductor field effect transistors (MOSFETs) [6-8] and MOS-controlled thyristor (MCT). Power system harmonic are not new fact. It is mainly caused by saturation of loads such as transformers, industrial arc furnaces, cables, switching mode power supplies and other devices [9-10]. Harmonic is a sinusoidal component of periodic wave or quantity having a frequency that is integer multiple of the fundamental frequency. An AC periodic voltage or current can be represented by Fourier series of pure sinusoidal waves which contain the fundamental frequency and its multiple is called harmonic [11]. A term called distortion factor or harmonic factor is often used to express the amount of harmonic distortion. It can be used to express the amount of voltage distortion or current distortion in a system. The distortion factor is determined as follows [12]. -1 2 2 2 [( )/( )] 100% harmonic Fundamental DF X X    (1) The purposed research work is carried out to investigate the effect of impedance i.e. change in the inductance keeping resistance constant on IGBT based digital voltage controllers. Signal processing technique is used to evaluate the effect of the impedance and calculation of total harmonic distortion. II. Causes and Effect of Harmonic Distortion Harmonics are electric voltages and currents that appear on the electric power system as a result of non-linear electric loads. Harmonic frequencies in the power grid are a frequent cause of power quality problems. Harmonic components should be reduced as much as possible. These are causes of harmonic distortion can be described as: 2.1 Causes of Dips, Sags and Surges Rural location remote from power source, unbalanced load on a three phase system, switching of heavy loads, long distance from a distribution transformer with interposed loads, unreliable grid systems and equipments not suitable for local supply. 2.2 Causes of Transients and Spikes Lightening, arc welding, switching on heavy or reactive equipments such as motors, transformers, motor drives and electric grade switching, Non–linear loads, power electronic devices, load switching [13].