RC snubbers for 12-pulse thyristor bridge
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I am trying to simulate an AC-DC power supply (12-pulse thyristor bridge connected in series) with an RC snubber. The real power supply has a snubber circuit with RC in series (C=4.4uF and R=5.1ohm) and the combination in parallel across each Thyristor. So, there are 12 RC snubbers in total for the 12-pulse thyristor.
I am using a Universal bridge with thyrsitors as power electronics device. I am also using current-control in order to generate the firing angle for the thyristor bridge. When I use the default values (Rs = 1e6, Cs = inf) for the snubbers provided in the thyristor bridge, the load current tracks the reference current as expected. However, when I use Rs = 5.1 ohm, Cs = 4.4uF, the load current is always near zero and never tracks the reference profile. Everything else in the circuit is the same.
How are the RC snubbers modeled in the universal bridge? Are the snubbers across each thyristor or across the entire bridge?
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