Short-circuit protection for forward-phase-control AC power controller
US6175220A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 22, 1999 |
| Grant date | Jan 16, 2001 |
| Priority date | — |
| Expiry date | Oct 22, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/30
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A thyristor-based forward phase control (FPC) system for controlling the power delivered to a load from an AC power source employs a short-circuit test cycle to protect the thyristor from damage. Upon activation of the FPC system, the thyristor is triggered at a phase less than one-twelfth cycle before a zero crossing so that, if there is a short, the resulting peak current will be insufficient to damage the thyristor but will exceed a predetermined threshold current corresponding to a repetitive overload current. If during the test cycle, the threshold current value is crossed, the FPC system does not trigger the thyristor again and does indicate that a short exists. The threshold current value is selected to correspond to the thyristor's steady-state load rating. If it is exceeded during normal (including warm-up and request-based) operation, steps can be taken to address an overload condition. Accordingly, the same circuitry used for general overload protection can be used as well for short-circuit protection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.