A Six-Switch Seven-Level Triple-Boost Inverter

Multilevel inverters in renewable applications usually require a high-voltage dc link fed by a front-end dc--dc boost stage. Such a two-stage power conversion, however, increases the switch count, leading to higher costs and power losses. To lower the number of switches, this letter proposes a six-switch inverter, capable of generating a seven-level voltage and a triple-voltage boost. Both features are achieved with only four switches operating at a high frequency while clamped by low-voltage capacitors. The remaining two switches must, however, endure higher voltage stresses but fortunately operate at a much lower frequency. The overall switching losses of the inverter are, thus, significantly reduced. Besides, the inverter shares a common ground between its dc input and ac output, which theoretically helps to eliminate the leakage current, if powered by photovoltaic sources. The operating principles of the inverter have been described and verified through experiments with an 800-W prototype.