Static current limiting switch with soft forced commutation
US4174495A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 30, 1978 |
| Grant date | Nov 13, 1979 |
| Priority date | — |
| Expiry date | Jun 30, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S323/908
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Disclosed is a force commutated static switch composed of inverse parallel connected thyristors. A bilateral commutation circuit is connected across the thyristors. The commutation circuit includes a switched capacitor which, during a current commutation interval, provides the dual functions of contributing to the current commutation operation and of acting as a current source for one of the thyristors. The capacitor discharge current interacts with the intrinsic resistance of the thyristor to provide a relatively low forward voltage drop which is a reverse voltage drop for the other thyristor. The low reverse voltage is known as soft biasing voltage. This voltage is utilized in conjunction with the most recently turned off thyristor to prevent reconduction thereof during the critical recovery time of the thyristor. The commutation circuit cooperates with its control circuit to provide an abort capability for its current limiting operation. Furthermore, the commutating circuit cooperates with its control circuit to eliminate repeated current reversals of the capacitor's discharge current.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.