Fault protection circuit
US4139885A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 20, 1977 |
| Grant date | Feb 13, 1979 |
| Priority date | — |
| Expiry date | Jun 20, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M5/4505
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An a-c supply system includes an input bridge circuit, connected to receive a-c input voltage and produce an output d-c voltage which is passed through a filter to an inverter having a plurality of thyristor switches, which switches are regulated to produce an a-c output voltage for supplying a load. If two of the switches are inadvertently triggered on to produce a fault across the bus, the rapid discharge of the filter capacitor into this fault is sensed, and the protection circuit provides both simultaneous turn-on of all of the inverter power switches, and turn-off of the input bridge. The input bridge turn-off is achieved by simultaneous removal of the gate drive from all the power switches in the input bridge and commutation of all the power switches in the input bridge circuit, or by interrupting power transfer from the input bridge toward the inverter. In addition to sensing the filter capacitor current, the level of current supplied to the input bridge is monitored so that a sudden rise is detected and utilized to initiate the same protective functions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.