Means for controlling a forced commutated hybrid a-c to d-c electric rectifying bridge to avoid reverse recovery overvoltage in the diode leg
US4471421A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1982 |
| Grant date | Sep 11, 1984 |
| Priority date | — |
| Expiry date | Sep 30, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M7/19
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A hybrid phase-controlled rectifying bridge includes both controlled and uncontrolled electric valves referred to as thyristors and diodes, respectively. Each of a pair of thyristors is periodically fired at an "angle" that can be advanced or retarded as desired, whereupon load current commutates to the thyristor from the corresponding diode. Subsequently the thyristor is turned off at a desired extinction angle by the action of cyclically operative forced commutation means. To avoid reverse recovery overvoltages across a diode when the desired extinction angle is only slightly larger than the firing angle, means is provided for temporarily preventing any turnoff action during the diode-to-thyristor commutation interval and for an additional interval that gives the diode sufficient time to fully recover its reverse blocking capability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.