Comparison of PWM techniques in a voltage source inverter

Abstract

In the last two decades, the electrification of multiple processes and operations —such as the case of the electric vehicle or the growth of photovoltaic energy— has led to the need for greater development of inverters. These devices are responsible for transforming direct current into alternating current. In the case of the electric vehicle with a voltage source inverter, the direct current comes from the vehicle’s battery, which is transformed into alternating current by the inverter. Finally, this alternating current is used to power the alternating current (AC) electric motor, which moves the vehicle. In addition to converting energy from direct to alternating current, inverters can also control the amplitude and frequency of the output voltage using pulse width modulation (PWM) techniques. Over the years, various modulation techniques have been developed to improve the output parameters and the performance of inverters. The aim of this final degree project is to compare, using Simulink simulations, the methodology of various pulse width modulation techniques as Sinusoidal Pulse Width Modulation (SPWM), Space Vector Pulse Width Modulation (SVPWM), Third Harmonic Injection (THIPWM) and Discontinuous Pulse Width Modulation (DPWM). In addition, the goal is to analyze their effects on the output signals of inverters using various parameters, such as an analysis using the Fast Fourier Transform (FFT). To facilitate the comparison of these techniques, an application (APP) has been developed with the Matlab software, which allows for a quick and clear visualisation of the results obtained from the simulations carried out with Simulink, depending on the selected modulation technique and other variables. This digital tool, in addition to being useful for the objectives of this project, can also be a tool used in teaching, as it allows intuitive and agile observation of the changes caused by each technique and variable, which facilitates explanation by the teaching staff.