I recently learned that train engines have been using electric motors powered by diesel generators since at least the 30’s, which surprised me. It made me wonder why cars or at least trucks and busses don’t do something similar, and why “parallel” hybrids are the only type of hybrid engine widely available.
I assume it has to do with the size difference, but what specifically? Needs to carry too much liquid fuel? Generator or electronics can’t be miniaturized? Or is it a purely economic problem and not a technological one?
In: Engineering
Trains use diesel-electric because they need the high torque a large electric motor provides. Their top speed is similar to a car’s highway speed, but they are thousands of times heavier than a car, so acceleration using just diesel motors would be almost impossible.
Some plug-in hybrids can operate this way, using the engine to charge a battery and just running the wheels off electricity. But the power still has to go through the transmission, so you don’t gain anything from it. And cars are light enough that a gas engine easily provides enough torque to get moving.
Latest Answers