Power-cell switching-cycle capacitor voltage control for modular multi-level converters
US9966874B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 2014 |
| Grant date | May 8, 2018 |
| Priority date | — |
| Expiry date | Dec 4, 2036 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M1/0003
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In a modular multi-level power converter, additional switching states are interleaved between main switching states that control output voltage or waveform. The additional switching states provide current from a DC-link to charge capacitors in respective modules or cells to an offset voltage from which the capacitor voltages are controlled toward a reference voltage during each switching cycle rather than being allowed to build up over a period of an output waveform of variable line frequency, possibly including zero frequency. Since the switching cycle is much shorter than the duration of a line frequency cycle and the capacitor voltages are balanced during each switching cycle, output voltage ripple can be limited as desired with a capacitor of much smaller value and size than would otherwise be required.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.