International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 12 | Dec 2018 www.irjet.net p-ISSN: 2395-0072 © 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1312 Analysis of Sine Pulse width Modulation (SPWM) and Third Harmonic Pulse Width Modulation(THPWM) with Various Amplitude and Frequency Modulation of Three Phase Voltage Source Inverter Mohd Mustafa Mohiuddin Khan 1 , Syed Mohammed Uddin 2 1,2 M.E. Student, EED, Muffakham Jah College of Engineering and Technology, Hyderabad, India ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract - The intent of this paper is to analyze sine pulse width modulation(SPWM) and third harmonic pulse width modulation (THPWM). The purpose of adopting for different techniques of inverter design is to decrease the harmonic content from the output waves of voltage source inverter (VSI). Amplitude modulation and frequency modulation are varied to examine their effects. Third harmonic pulse width modulation has been observed as superior than sine pulse width modulation technique by simulation results. The simulations are carried out in MATLAB/SIMULINK. Key Words: Amplitude Modulation, SPWM, THPWM, VSI, Frequency Modulation 1. INTRODUCTION In present time, the application of the voltage source inverter (VSI) are rapidly been increasing. Different designing methods are followed for the construction of VSI. The main function of voltage source inverter is to convert DC supply into AC supply of desired magnitude and frequency [1]. Ideally, the output waveforms of inverter should be sinusoidal but in practical, the output waveforms are not pure sinusoidal and contains different harmonics. Fig -1: Voltage Source Inverter Harmonics in any system reduces the quality of electrical supply which can cause several negative effects in the system. RMS current will get increased when harmonic will increase which cause increase in loss. Electrical system starts getting premature ageing due to harmonics. For low and moderate power applications, square and quasi-square waves are allowed but for high power application, we need sinusoidal waveforms with very low harmonic content. That’s how, by using semiconductor based devices and different methods of switches pulse generation (SPWM & THIPWM) the value of harmonic content can be minimized. Hence the comparison of two different voltage source inverters with their different techniques is discussed in this paper for the purpose of reduction in harmonics. Total harmonic distortion (THD) analysis of VSI has been done.THD analysis of sine pulse width modulation (SPWM) and third harmonic injection pulse width modulation (THIPWM) is further discussed in three manners – over modulation, linear modulation and under modulation. 2. Pulse Width Modulation (PWM) Pulse width modulation (PWM) is a strong method to control the analog circuits with a processed digital output. PWM of power devices modulate its duty cycle to commit the control or amount of power delivered to the load. Single PWM is not suited for all type of applications. By the help of advanced technology, various methods of PWM are there for use in any application. The major aim of PWM is to maintain the output voltage and reduce the harmonic content from it [4] . The different PWM techniques being used are: 1. Sinusoidal Pulse Width Modulation (SPWM) 2. Third Harmonic Pulse Width Modulation (THPWM) 3. Space Vector Pulse Width Modulation (SVPWM) 2.1 Sine Pulse Width Modulation (SPWM) The method of sinusoidal pulse width modulation approaches the generation of sinusoidal waveform by comparing the reference to carrier waves or by filtering the pulse output waveform by varying widths of triangular waveform [1]. Low frequency reference sinusoidal wave form is compared with high frequency triangular waves which are called carrier waves(V∆) . When crossing of sine and carrier waves are happen, the switching phase gets changed at that time. In three phases, three low frequency sinusoidal reference waves ( Va ,Vb , and Vc) which are 120 o out of phase from each other, are compared with the triangular voltage waveform as a result we get three switching pulses for three different phases.