>>198843068 tonnes is indeed far more than "at most a couple hundred kilograms", and 9kV -> 3kV is substantially more difficult than 3kV to 3 phase, you run out of off the shelf IGBTs with sufficient voltage ratings, so need to go multilevel topologies with capacitor banks.
For existing off the shelf traction inverters you're getting around a tonne per megawatt at best, see some examples