AC-DC CONVERTERS WITH BI-DIRECTIONAL VALVES

摘要

An ac-dc converter has bi-directional thyristor valves (VR1-VF6) made up of back-to-back connected thyristors as converter valves. The bi-directional thyristor valves (VR1-VF6) permit operation of the converter as a rectifier or an inverter with both polarities of the voltage across the dc terminals (DCH , DCL) of the converter. The bi-directional valves (VR1-VF6) can be used to prevent the reversal of the polarity of the dc voltage across the dc termina ls (DCH, DCL) of the converter or to minimize the magnitude of the reverse voltage. The bi-directional thyristor valves (VR1-VF6) can be used to provid e protection against overvoltage across the converter valves and eliminate or reduce the energy rating of converter valve arresters. AC-DC converters coul d also be provided with some bi-directional thyristor valves as converter valv es while retaining regular thyristor valves in other converter valve positions.