A Single-Phase Cascaded H-Bridge Multilevel Inverter with Reduced Switching Devices and Harmonics

This paper presents the design and implementation of microcontroller-based single-phase multilevel inverters for reducing the number of switching devices and total harmonic content at the output voltage. Multilevel inverters are suitable for high-voltage and high-current applications. The proposed system consists of a microcontroller, three separate input dc sources, isolating circuit and three cascaded H-bridge MOSFET-based voltage source inverters. A microcontroller has been used to generate proper gate signals for MOSFETs of the three H-bridge inverters. The complexity of generating gate drive signals for higher levels of inverter output voltage can be reduced dramatically using microcontroller. Maximum thirteen-level output voltage has been obtained experimentally using three number of cascaded H-bridge inverters which require less power switching devices. It is found that total harmonic distortion is reduced with increasing number of levels at the output voltage of the multilevel inverter.