Comparison 5 Level Cascade H-bridge Multilevel Inverter Circuit with LC Filter and Without LC Filter

The 5-level Cascade H-bridge multilevel inverter has become an attractive choice in industrial applications and renewable power systems. The output wave quality produced by this multilevel inverter has an important role in ensuring optimal performance of the system. In this study, a performance comparison analysis was carried out between a 5-level Cascade H-bridge multilevel inverter with the use of an LC filter after the inverter and a configuration without an LC filter. The simulation results show that the use of an LC filter after the inverter produces a purer output signal by reducing unwanted harmonic components. The inverter without LC filter has a THD of 28.99%, while with an LC filter the THD is 8%. The use of LC filters improves the quality of the output signal and the performance of a 5-level multilevel inverter.

I. Introduction

Multilevel inverter circuits have become an attractive option in power conversion applications requiring high quality wave output. Compared to conventional inverters that produce square waves or pulse width modulation (PWM) waves, the use of multilevel inverters is capable of producing an output wave that is closer to a pure sinusoidal wave. Multilevel inverters are capable of producing a sinusoidal output voltage and to reduce Total Harmonic Distortion to the desired voltage level [1]. Therefore, multilevel inverters are used to produce a pure sinusoidal stepped output voltage or step voltage wave synthesis and thereby reduce the harmonic content [2]. However, the quality of the output waveform from a multilevel inverter can be improved by using an LC filter. Inverters are usually used with LC filter outputs to provide high quality sinusoidal output voltages with low total harmonic distortion (THD) for various types of loads, especially for unbalanced or nonlinear loads [3].