Three-level circuit and control method for balancing neutral point voltage of the same
US10374522B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 7, 2018 |
| Grant date | Aug 6, 2019 |
| Priority date | — |
| Expiry date | Nov 7, 2038 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M7/5395
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The present invention relates to a control method for balancing a neutral point voltage of a three-level circuit, comprising obtaining the neutral point voltage through sampling, adjusting a duty ratio of a zero level in one phase to maintain balance of the neutral point voltage when an absolute value of the neutral point voltage is larger than a threshold value, and distributing duty ratios of positive and negative levels in the phase, such that an output voltage of switch bridge arm in the phase includes positive, negative and zero levels in at least one switch period. The present invention can be carried out in a three-phase four-wire system and a three-phase three-wire system. In the three-phase three-wire system, it may also be combined with zero sequence voltage injection to form a mixed modulation method, thereby acquiring more effective neutral point balance control performance, and reducing switch loss.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.