Closed loop active EMI filter for reducing common or differential noise based on an error value
US6775157B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 24, 2003 |
| Grant date | Aug 10, 2004 |
| Priority date | — |
| Expiry date | Jun 24, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M1/123
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An active EMI filter senses current in a ground line or a power transmission line as a voltage cross a capacitor coupled to the line. The EMI filter senses common mode voltage and determines a difference between the common mode voltage and noise to provide an output to drive the difference to zero. The resulting active closed loop EMI filter produces good EMI dampening with greatly increased performance over a current transformer type EMI filter. A voltage regulator for the error amplifier improves noise reduction while increasing filter efficiency. The active EMI filter operates in a wide linear range that is greater than that of an equivalent current transformer circuit, while providing low cost and reliability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.