Single phase 9 level MLDCL inverter with half bridge cell topology: Performance analysis

Abstract

This paper presents the implementation of Single Phase 9 level MLDCL Inverter with Half Bridge Cell topology. For N level inverter, (N-1)/2 half bridge cells are required with the same number of voltage sources. One voltage source is used for each half bridge cell. These N levels are obtained in every half cycle of the output. So, in all 2×N levels are obtained in each full cycle. In the proposed inverter topology, 4 Half Bridge Cells are used along with 4 voltage sources, each of 24V DC. These half bridges are connected in series to form a Multilevel DC Link (MLDCL). The DC link provides 9 levels in each half cycle. The output obtained from this link is of unidirectional nature. H-Bridge network is connected through Multilevel DC Link and used to convert unidirectional output into bidirectional output. Power MOSFETs are used as switching devices. Each half bridge cell uses two MOSFETs whereas H-Bridge requires four MOSFETs. In this inverter topology, twelve Power MOSFETs along with gate drive circuit for each MOSFET is used. The simulation and experimental results are included to verify the working principle of Single Phase 9 level MLDCL Inverter with Half Bridge Cell topology and the Total Harmonic Distortion (THD) in each case is measured.