This discussion is akin of how to use power electronics to convert a 110 VAC light bulb to operate on 135 volts. It might not actually workable (or even be worth the cost) and buying a different bulb may be the only solution. But for the sake of discussion here's my proposition.
My transit agency here in San Francisco will be decommissioning about 150 subway cars (AKA- light rail vehicles) and there's a possibility that the surplus vehicles could be sold for reuse in a foreign country such as Metro Manila in the Philippines.
The cars run on a nominal voltage of 615 VDC which is supplied by an overhead wire similar to a street car. However, the overhead voltage for transit vehicles in most other countries is 750 VDC.
The 615 VDC subsystems are the following:
There are only three options for adapting these vehicles to 750 VDC:
Also, the mechanical components and the car shell (the body and chassis) are in fairly good condition and the old cars could be run for at least 10 years. There are several rail car builders in Asia (Japan, China, and South Korea) that could retrofit all the 600 VDC subsystems for operation on 750 volts and the cars would run like new.
My transit agency here in San Francisco will be decommissioning about 150 subway cars (AKA- light rail vehicles) and there's a possibility that the surplus vehicles could be sold for reuse in a foreign country such as Metro Manila in the Philippines.
The cars run on a nominal voltage of 615 VDC which is supplied by an overhead wire similar to a street car. However, the overhead voltage for transit vehicles in most other countries is 750 VDC.
The 615 VDC subsystems are the following:
- The traction motors and their VVVF inverters use GTO thyristor control
- The low voltage power supply/battery charger (615 VDC to 36 VDC converter) using GTO thyristor control
- The auxiliary inverter (615 VDC to 230 VAC/3 phase convert) using GTO thyristor control
- The HVAC has an IGBT inverter for the compressor and fans and the heater is powered directly from the 615 volts.
There are only three options for adapting these vehicles to 750 VDC:
- Use a step down converter on each car to change 750 volts to 615 volts. This would be quite expensive and may not be workable because of electromagnetic compatibility with the existing subsystems.
- Use a large resistor on each car to drop the 750 volts to 615 volts, but a 135 volt drop would dissipate a huge amount of power and waste energy.
- Finally, replace all the 615 VDC subsystems on each car with all new rated for 750 volts. This would be quite expensive, but the results would be predictable and everything would work.
Also, the mechanical components and the car shell (the body and chassis) are in fairly good condition and the old cars could be run for at least 10 years. There are several rail car builders in Asia (Japan, China, and South Korea) that could retrofit all the 600 VDC subsystems for operation on 750 volts and the cars would run like new.
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