Thyristors DC=AC converter with sum cancellation circuit - has anti-parallel feedback thyristors across each series main thyristor pair

摘要

The converter, providing a variable frequency 3-phase voltage from a constant DC source, has a smoothing capacitor (Cp) in series with a semiconductor switch (S1) on the DC side across which a second switch (S2) and a series voltage source (E) are connected in parallel. The second series circuit (S2,E) is used for cancellation of the main transistors (T1,T6) in the 3-phase thyristor bridge circuit. Each phase of the bridge circuit has two main transistors (T1..T6) in series across which anti-parallel feedback thyristors (T10,T20..T60) are connected, with the output phases (R,S,T) connected directly to the junctions between each two series main transistors (T1..T6).