FPGA based quasi z-source cascaded multilevel inverter using multicarrier PWM techniques

Ranjith Kumar Kalilasam,Venkatesan Mani

doi:10.21595/jve.2017.18180

Abstract

FPGA based Quasi Z-Source Cascaded Multilevel Inverter (Quasi Zs-CMLI) using multicarrier PluseWidth Modulation (PWM) techniques are presented in this paper. Multicarrier based PWM techniques have been proposed for seven level Quasi Zs-CMLI and implemented using Field Programmable Gate Array (FPGA). For generating gating pulses to the inverter switches, Phase Disposition (PD), Inverted Phase Disposition (IPD), Phase Opposition Disposition (POD) and Alternative Phase Opposition Disposition (APOD) techniques are programmed on FPGA. In the proposed system, three solar PV emulator modules are used. These are acting as input source to the inverter. Finally, THD comparison made between different carrier based modulation with shoot through and non-shoot through the states. The proposed quasi Zs-CMLI and PWM techniques are verified through MATLAB/Simulink. For confirmation of simulation results, A laboratory prototype model have been implemented using FPGA. The capture hardware results are matched with simulation results.

Highlights

In recent years, Multilevel inverters(MLIs) have drawn tremendous interest in the area of high voltage and high-power applications along with renewable energy sources such as wind energy systems, Photovoltaic (PV) systems, Fuel cell etc
Alternative Phase Opposition Disposition (APOD) Switching methods is very similar to Phase Disposition (PD) but only difference is each carrier signals phase shifted by 180° from the adjust carrier
The PD, Inverted Phase Disposition (IPD), Phase Opposition Disposition (POD), and APOD modulation schemes are used for the six multicarrier SPWM techniques

Summary

Introduction

Multilevel inverters(MLIs) have drawn tremendous interest in the area of high voltage and high-power applications along with renewable energy sources such as wind energy systems, Photovoltaic (PV) systems, Fuel cell etc. The Quasi Zs-CMLIs are mainly used in the photovoltaic power generation system that has advantage of balanced DC-link voltage control, distributed maximum power tracking, modular structure and reduced AC side filter requirements. These features cannot be realized in traditional CMI. The multicarrier PWM can be implemented with less complexity, offers better performance in all the operating conditions and allow the over modulation region [7,8,9,10] The contribution of this papers: Six different carrier based PWM techniques such as triangular, sawtooth, unipolar, sine(regular), stepped wave and staircase with four modulation schemes (PD, IPD, POD and APOD) are implemented for Quasi Zs-CMLI. The prototype model of the proposed system has been implemented using FGPA and tested with different modulation schemes for the seven level quasi under ST and NST conditions

Quasi Z-source inverter

Seven level quasi Z-source cascaded multilevel inverter

Multicarrier based sine pulse width modulation techniques

Simulation results

Hardware results

Conclusions