Mitigation of Harmonics from Output of Cascaded H Bridge Multilevel Inverter Using SHE PWM and AI Technique: A Review

Abstract

An extensive use of fossil fuel has led to an extreme increment of carbon footprint in the world globally. Glaciers are melting on the earth’s poles due to the greenhouse effect. Many such natural indications urge us to adopt renewable energy sources. In most cases, renewable power is generated in electrical form, which does not suit the existing grid requirements. Cascaded H bridge with multilevel inverter topology is promising in this context. The output of the multilevel inverter is near to sinusoidal. It has added advantages of low device stress, no need for step-up transformers, low common-mode voltage, near sinusoidal input current, low switching frequency, and reduced harmonics. The direct output of Cascaded H bridge multilevel inverters may not be suitable for many applications like integrating solar panel output with an existing grid where harmonic reduction is necessary. Various modulation techniques are available like sinusoidal pulse width modulation, space vector modulation, and selective harmonic elimination. Among the listed modulation techniques, selective harmonic elimination can be implemented with the low switching frequency, and it is suitable where low electromagnetic interference, low switching loss, and good power quality are required. To reduce the harmonics, one must solve the non-linear transcendental output equations of the cascaded H-bridge Multilevel inverter (CHB-MLI). Various Artificial Intelligent (AI) algorithms are introduced, and researchers have worked on eliminating harmonics or minimizing Total Harmonics Distortion (THD) from the output of CHB-MLI. This paper gives a review of the harmonic reduction using some of the well-known explored AI algorithms. It also provides insight into some of the unexplored algorithms in this area.