Simulation of Different Third Harmonic Injected PWM Strategies for 5-Level Diode-Clamped Multilevel Inverter

Abstract

Multilevel Inverters (MLI) have widespread use in industrial drive applications, HVDC transmission with Uninterruptable Power Supply systems. They also have applications in the stand-alone and the grid connected renewable energy systems. Multi-level Inverters also find optimum application in Stand-alone and Grid-connected Systems. Majority of losses i.e. switching losses are considered with constrained device rating, the traditional two-level inverters face limits especially when operating at high frequency. The solution which is optimum and appropriate by many power quality researchers is the use of MLIs. Among various MLI topologies the Diode-Clamped Multilevel Inverter (DCMLI) give a promising solution as they can give better voltage performance for different switching frequencies and an improved total harmonic distortion (THD) profile without the use of filter. To meet the voltage and frequency requirement various modulation techniques are applied to MLIs. The additional switching states created by these topologies provide greater flexibility to control more circuit breakers. This paper presents the comparison of a 5-level DCMLIs with several modulation schemes. The simulation results are discussed in detail and the comparison table is presented in terms of Output voltage and THD.