Switched capacitor multilevel inverter using PWM technique

Abstract

For the last decades, the increasing demand for renewable energy resources and their applications of high voltage, multilevel inverter (MLI) become very popular and globally recognized for several industrial applications and it has been under research and development with successful industrial applications due to its capacity to produce high levels of voltage output, low THD, low EMI and reduced switching stress on switching devices. However, renewable energy resources such as solar and wind energy for their output are not always fixed due to changes of their input constantly. To boost their output and to convert into alternate current (AC) at the same time with one circuit, switched capacitor inverter is required. In this project, a Switched-Capacitor multilevel inverter with 7-level output comparing between different kinds of pulse width modulation (PWM) technique namely, phase disposition (PD-SPWM), phase opposition disposition (POD-SPWM), and Alternate phase opposition disposition (APOD-SPWM) has been proposed. The main objectives of this project are to simulate the modelled 7-level switched capacitor multilevel inverter using pulse width modulation technique with different modulation index, to observe the performance of the switching patterns of various switches, output voltage, and FFT analysis of modified multilevel inverter, to perform analysis of the charging and discharging time of the capacitors and to analyze using PD-SPWM for pure resistive load and RL load and step change of load from no load to RL load and from low RL load to high RL load. The proposed topology uses a smaller number of switches and produces less harmonic output voltage using the strategy of pulse width modulation (PWM). To validate the viability of the proposed topography and its strategy of switching, a circuit for seven-level MLI is developed and done in MATLAB/SIMULINK software tool.