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by tim333 661 days ago
Apparently they use thyristors https://en.wikipedia.org/wiki/Thyristor#HVDC_electricity_tra...

https://en.wikipedia.org/wiki/HVDC_converter#Thyristor_valve...

1 comments

Thyristors require you have at least one transformer operate at AC line frequency (50/60Hz). That costs a lot, since you need enough steel to store 20 milliseconds of your total power as a magnetic field. Thyristors are on-off devices (like most semiconductors when used for power conversion), but cannot turn off without zero current, which precludes a bunch of high frequency designs which are better for harmonics and weight-of-steel.

Overall, they were a popular choice in the 90's and 2010's, but I don't think we'll see any new designs installed with them.

Ah - right you are. Seems IGBTs are the thing now.