Flyback constant voltage converter having both a PWFM mode and a PWM mode
US7746673B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 10, 2008 |
| Grant date | Jun 29, 2010 |
| Priority date | — |
| Expiry date | Mar 7, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M3/33515
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A flyback AC/DC switching converter has a constant voltage (CV) mode. The CV mode has sub-modes. In one sub-mode (“mid output power sub-mode”), the output voltage (VOUT) of the converter is regulated using both pulse width modulation and pulse frequency modulation. Both types of modulation are used simultaneously. In a second sub-mode (“low output power sub-mode”), VOUT is regulated using pulse width modulation, but the converter switching frequency is fixed at a first frequency. By setting the first frequency at a frequency above the frequency limit of human hearing, an undesirable audible transformer humming that might otherwise occur is avoided. In some embodiments, the converter has a third sub-mode (“high output power sub-mode”), in which pulse width modulation is used but the switching frequency is fixed at a second frequency. By proper setting of the second frequency, undesirable EMI radiation and other problems that might otherwise occur are avoided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.