## Abstract

This paper presents a new switching strategy controlling a new three-level voltage source inverter, resulting in different 25 space voltage-vectors. The new inverter combines some desirable features of two and three-level inverters. The proposed open-leg switching strategy intentionally opens one of the three inverter-legs per-time, in a pre-planned sequence. Thus, the number of allowed states becomes 64 compared to 27 originally proposed by other modulation strategies. For a wye-connected load operating at low modulation index (M<0.5 p.u.), the output phase-voltage becomes a seven-level, 12-step waveform, instead of the 6-step one. Thus, the total harmonic distortion is highly reduced. Three new conduction-modes are presented, each verifies a reduced common-mode-voltage time-variation [dv/dt), low third harmonic content, and reduced switching frequency harmonics. For higher modulation indexes, a 4 ^{th} conduction mode is presented, eliminating the low frequency harmonics in the neutral-point current, consequently reducing the dc-link capacitors sizes, and cost. Analytical models, computer simulation results, and experimental verification are presented.

Original language | English |
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Pages (from-to) | 297-308 |

Number of pages | 12 |

Journal | AEJ - Alexandria Engineering Journal |

Volume | 46 |

Issue number | 3 |

Publication status | Published - May 2007 |

Externally published | Yes |

## Keywords

- 150° conduction-mode
- Neutral point clamped
- Three-level converter
- Total harmonic distortion
- Voltage source inverters

## ASJC Scopus subject areas

- Engineering(all)