Active EMI filter with feed forward cancellation
US6839250B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 3, 2003 |
| Grant date | Jan 4, 2005 |
| Priority date | — |
| Expiry date | Jan 3, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M1/123
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An active EMI filter for reducing common mode current in a circuit comprising a rectifier coupled to an AC network, the rectifier supplying DC power to a DC bus, the DC bus feeding an inverter stage for providing AC power to a load, the load having a ground return line to a ground connection of the AC network, the active filter comprising: a transistor switching stage coupled across the DC bus, a current sensor coupled to the DC bus for sensing the common mode current flowing in the DC bus and proportional to the common mode current flowing in the ground return line from or to the load, the current sensor having inputs coupled to respective legs of the DC bus and an output driving the transistor switching stage, the transistor switching stage comprising two transistors driven by said output of the current sensor whereby one of said transistors is turned on by said current sensor output depending on the direction of common mode current in said DC bus, a capacitor coupling said transistor switching stage and said ground return line and wherein said current sensor and said switching stage are coupled in a feed forward arrangement whereby the switching stage is coupled across said DC b…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.